Merge branch 'tracing/ftrace' into auto-ftrace-next

Makefile

@@ -528,6 +528,10 @@ KBUILD_CFLAGS	+= -g
 KBUILD_AFLAGS	+= -gdwarf-2
 endif
 
+ifdef CONFIG_FTRACE
+KBUILD_CFLAGS	+= -pg
+endif
+
 # We trigger additional mismatches with less inlining
 ifdef CONFIG_DEBUG_SECTION_MISMATCH
 KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)

arch/arm/Kconfig

@@ -14,6 +14,8 @@ config ARM
 	select HAVE_OPROFILE
 	select HAVE_KPROBES if (!XIP_KERNEL)
 	select HAVE_KRETPROBES if (HAVE_KPROBES)
+	select HAVE_FTRACE if (!XIP_KERNEL)
+	select HAVE_DYNAMIC_FTRACE if (HAVE_FTRACE)
 	help
 	  The ARM series is a line of low-power-consumption RISC chip designs
 	  licensed by ARM Ltd and targeted at embedded applications and

arch/arm/boot/compressed/Makefile

@@ -69,6 +69,12 @@ SEDFLAGS	= s/TEXT_START/$(ZTEXTADDR)/;s/BSS_START/$(ZBSSADDR)/
 
 targets       := vmlinux vmlinux.lds piggy.gz piggy.o font.o font.c \
 		 head.o misc.o $(OBJS)
+
+ifeq ($(CONFIG_FTRACE),y)
+ORIG_CFLAGS := $(KBUILD_CFLAGS)
+KBUILD_CFLAGS = $(subst -pg, , $(ORIG_CFLAGS))
+endif
+
 EXTRA_CFLAGS  := -fpic -fno-builtin
 EXTRA_AFLAGS  :=
 

arch/arm/kernel/Makefile

@@ -4,6 +4,10 @@
 
 AFLAGS_head.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
 
+ifdef CONFIG_DYNAMIC_FTRACE
+CFLAGS_REMOVE_ftrace.o = -pg
+endif
+
 # Object file lists.
 
 obj-y		:= compat.o entry-armv.o entry-common.o irq.o \
@@ -18,6 +22,7 @@ obj-$(CONFIG_ARTHUR)		+= arthur.o
 obj-$(CONFIG_ISA_DMA)		+= dma-isa.o
 obj-$(CONFIG_PCI)		+= bios32.o isa.o
 obj-$(CONFIG_SMP)		+= smp.o
+obj-$(CONFIG_DYNAMIC_FTRACE)	+= ftrace.o
 obj-$(CONFIG_KEXEC)		+= machine_kexec.o relocate_kernel.o
 obj-$(CONFIG_KPROBES)		+= kprobes.o kprobes-decode.o
 obj-$(CONFIG_ATAGS_PROC)	+= atags.o

arch/arm/kernel/armksyms.c

@@ -18,6 +18,7 @@
 #include <asm/io.h>
 #include <asm/system.h>
 #include <asm/uaccess.h>
+#include <asm/ftrace.h>
 
 /*
  * libgcc functions - functions that are used internally by the
@@ -181,3 +182,7 @@ EXPORT_SYMBOL(_find_next_bit_be);
 #endif
 
 EXPORT_SYMBOL(copy_page);
+
+#ifdef CONFIG_FTRACE
+EXPORT_SYMBOL(mcount);
+#endif

arch/arm/kernel/entry-common.S

@@ -9,6 +9,7 @@
  */
 
 #include <asm/unistd.h>
+#include <asm/ftrace.h>
 #include <asm/arch/entry-macro.S>
 
 #include "entry-header.S"
@@ -99,6 +100,56 @@ ENTRY(ret_from_fork)
 #undef CALL
 #define CALL(x) .long x
 
+#ifdef CONFIG_FTRACE
+#ifdef CONFIG_DYNAMIC_FTRACE
+ENTRY(mcount)
+	stmdb sp!, {r0-r3, lr}
+	mov r0, lr
+	sub r0, r0, #MCOUNT_INSN_SIZE
+
+	.globl mcount_call
+mcount_call:
+	bl ftrace_stub
+	ldmia sp!, {r0-r3, pc}
+
+ENTRY(ftrace_caller)
+	stmdb sp!, {r0-r3, lr}
+	ldr r1, [fp, #-4]
+	mov r0, lr
+	sub r0, r0, #MCOUNT_INSN_SIZE
+
+	.globl ftrace_call
+ftrace_call:
+	bl ftrace_stub
+	ldmia sp!, {r0-r3, pc}
+
+#else
+
+ENTRY(mcount)
+	stmdb sp!, {r0-r3, lr}
+	ldr r0, =ftrace_trace_function
+	ldr r2, [r0]
+	adr r0, ftrace_stub
+	cmp r0, r2
+	bne trace
+	ldmia sp!, {r0-r3, pc}
+
+trace:
+	ldr r1, [fp, #-4]
+	mov r0, lr
+	sub r0, r0, #MCOUNT_INSN_SIZE
+	mov lr, pc
+	mov pc, r2
+	ldmia sp!, {r0-r3, pc}
+
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+	.globl ftrace_stub
+ftrace_stub:
+	mov pc, lr
+
+#endif /* CONFIG_FTRACE */
+
 /*=============================================================================
  * SWI handler
  *-----------------------------------------------------------------------------

arch/arm/kernel/ftrace.c

@@ -0,0 +1,116 @@
+/*
+ * Dynamic function tracing support.
+ *
+ * Copyright (C) 2008 Abhishek Sagar <sagar.abhishek@gmail.com>
+ *
+ * For licencing details, see COPYING.
+ *
+ * Defines low-level handling of mcount calls when the kernel
+ * is compiled with the -pg flag. When using dynamic ftrace, the
+ * mcount call-sites get patched lazily with NOP till they are
+ * enabled. All code mutation routines here take effect atomically.
+ */
+
+#include <linux/ftrace.h>
+
+#include <asm/cacheflush.h>
+#include <asm/ftrace.h>
+
+#define PC_OFFSET      8
+#define BL_OPCODE      0xeb000000
+#define BL_OFFSET_MASK 0x00ffffff
+
+static unsigned long bl_insn;
+static const unsigned long NOP = 0xe1a00000; /* mov r0, r0 */
+
+unsigned char *ftrace_nop_replace(void)
+{
+	return (char *)&NOP;
+}
+
+/* construct a branch (BL) instruction to addr */
+unsigned char *ftrace_call_replace(unsigned long pc, unsigned long addr)
+{
+	long offset;
+
+	offset = (long)addr - (long)(pc + PC_OFFSET);
+	if (unlikely(offset < -33554432 || offset > 33554428)) {
+		/* Can't generate branches that far (from ARM ARM). Ftrace
+		 * doesn't generate branches outside of kernel text.
+		 */
+		WARN_ON_ONCE(1);
+		return NULL;
+	}
+	offset = (offset >> 2) & BL_OFFSET_MASK;
+	bl_insn = BL_OPCODE | offset;
+	return (unsigned char *)&bl_insn;
+}
+
+int ftrace_modify_code(unsigned long pc, unsigned char *old_code,
+		       unsigned char *new_code)
+{
+	unsigned long err = 0, replaced = 0, old, new;
+
+	old = *(unsigned long *)old_code;
+	new = *(unsigned long *)new_code;
+
+	__asm__ __volatile__ (
+		"1:  ldr    %1, [%2]  \n"
+		"    cmp    %1, %4    \n"
+		"2:  streq  %3, [%2]  \n"
+		"    cmpne  %1, %3    \n"
+		"    movne  %0, #2    \n"
+		"3:\n"
+
+		".section .fixup, \"ax\"\n"
+		"4:  mov  %0, #1  \n"
+		"    b    3b      \n"
+		".previous\n"
+
+		".section __ex_table, \"a\"\n"
+		"    .long 1b, 4b \n"
+		"    .long 2b, 4b \n"
+		".previous\n"
+
+		: "=r"(err), "=r"(replaced)
+		: "r"(pc), "r"(new), "r"(old), "0"(err), "1"(replaced)
+		: "memory");
+
+	if (!err && (replaced == old))
+		flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
+
+	return err;
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+	int ret;
+	unsigned long pc, old;
+	unsigned char *new;
+
+	pc = (unsigned long)&ftrace_call;
+	memcpy(&old, &ftrace_call, MCOUNT_INSN_SIZE);
+	new = ftrace_call_replace(pc, (unsigned long)func);
+	ret = ftrace_modify_code(pc, (unsigned char *)&old, new);
+	return ret;
+}
+
+int ftrace_mcount_set(unsigned long *data)
+{
+	unsigned long pc, old;
+	unsigned long *addr = data;
+	unsigned char *new;
+
+	pc = (unsigned long)&mcount_call;
+	memcpy(&old, &mcount_call, MCOUNT_INSN_SIZE);
+	new = ftrace_call_replace(pc, *addr);
+	*addr = ftrace_modify_code(pc, (unsigned char *)&old, new);
+	return 0;
+}
+
+/* run from kstop_machine */
+int __init ftrace_dyn_arch_init(void *data)
+{
+	ftrace_mcount_set(data);
+	return 0;
+}

arch/arm/kernel/kprobes.c

@@ -274,7 +274,7 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
  * for kretprobe handlers which should normally be interested in r0 only
  * anyway.
  */
-static void __attribute__((naked)) __kprobes kretprobe_trampoline(void)
+void __naked __kprobes kretprobe_trampoline(void)
 {
 	__asm__ __volatile__ (
 		"stmdb	sp!, {r0 - r11}		\n\t"

arch/powerpc/Kconfig

@@ -105,11 +105,13 @@ config ARCH_NO_VIRT_TO_BUS
 config PPC
 	bool
 	default y
+	select HAVE_DYNAMIC_FTRACE
+	select HAVE_FTRACE
 	select HAVE_IDE
-	select HAVE_OPROFILE
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
 	select HAVE_LMB
+	select HAVE_OPROFILE
 
 config EARLY_PRINTK
 	bool

arch/powerpc/kernel/Makefile

@@ -12,6 +12,18 @@ CFLAGS_prom_init.o      += -fPIC
 CFLAGS_btext.o		+= -fPIC
 endif
 
+ifdef CONFIG_FTRACE
+# Do not trace early boot code
+CFLAGS_REMOVE_cputable.o = -pg
+CFLAGS_REMOVE_prom_init.o = -pg
+
+ifdef CONFIG_DYNAMIC_FTRACE
+# dynamic ftrace setup.
+CFLAGS_REMOVE_ftrace.o = -pg
+endif
+
+endif
+
 obj-y				:= cputable.o ptrace.o syscalls.o \
 				   irq.o align.o signal_32.o pmc.o vdso.o \
 				   init_task.o process.o systbl.o idle.o \
@@ -78,6 +90,8 @@ obj-$(CONFIG_KEXEC)		+= machine_kexec.o crash.o \
 obj-$(CONFIG_AUDIT)		+= audit.o
 obj64-$(CONFIG_AUDIT)		+= compat_audit.o
 
+obj-$(CONFIG_DYNAMIC_FTRACE)	+= ftrace.o
+
 obj-$(CONFIG_8XX_MINIMAL_FPEMU) += softemu8xx.o
 
 ifneq ($(CONFIG_PPC_INDIRECT_IO),y)

arch/powerpc/kernel/entry_32.S

@@ -30,6 +30,7 @@
 #include <asm/ppc_asm.h>
 #include <asm/asm-offsets.h>
 #include <asm/unistd.h>
+#include <asm/ftrace.h>
 
 #undef SHOW_SYSCALLS
 #undef SHOW_SYSCALLS_TASK
@@ -1035,3 +1036,129 @@ machine_check_in_rtas:
 	/* XXX load up BATs and panic */
 
 #endif /* CONFIG_PPC_RTAS */
+
+#ifdef CONFIG_FTRACE
+#ifdef CONFIG_DYNAMIC_FTRACE
+_GLOBAL(mcount)
+_GLOBAL(_mcount)
+	stwu	r1,-48(r1)
+	stw	r3, 12(r1)
+	stw	r4, 16(r1)
+	stw	r5, 20(r1)
+	stw	r6, 24(r1)
+	mflr	r3
+	stw	r7, 28(r1)
+	mfcr	r5
+	stw	r8, 32(r1)
+	stw	r9, 36(r1)
+	stw	r10,40(r1)
+	stw	r3, 44(r1)
+	stw	r5, 8(r1)
+	subi	r3, r3, MCOUNT_INSN_SIZE
+	.globl mcount_call
+mcount_call:
+	bl	ftrace_stub
+	nop
+	lwz	r6, 8(r1)
+	lwz	r0, 44(r1)
+	lwz	r3, 12(r1)
+	mtctr	r0
+	lwz	r4, 16(r1)
+	mtcr	r6
+	lwz	r5, 20(r1)
+	lwz	r6, 24(r1)
+	lwz	r0, 52(r1)
+	lwz	r7, 28(r1)
+	lwz	r8, 32(r1)
+	mtlr	r0
+	lwz	r9, 36(r1)
+	lwz	r10,40(r1)
+	addi	r1, r1, 48
+	bctr
+
+_GLOBAL(ftrace_caller)
+	/* Based off of objdump optput from glibc */
+	stwu	r1,-48(r1)
+	stw	r3, 12(r1)
+	stw	r4, 16(r1)
+	stw	r5, 20(r1)
+	stw	r6, 24(r1)
+	mflr	r3
+	lwz	r4, 52(r1)
+	mfcr	r5
+	stw	r7, 28(r1)
+	stw	r8, 32(r1)
+	stw	r9, 36(r1)
+	stw	r10,40(r1)
+	stw	r3, 44(r1)
+	stw	r5, 8(r1)
+	subi	r3, r3, MCOUNT_INSN_SIZE
+.globl ftrace_call
+ftrace_call:
+	bl	ftrace_stub
+	nop
+	lwz	r6, 8(r1)
+	lwz	r0, 44(r1)
+	lwz	r3, 12(r1)
+	mtctr	r0
+	lwz	r4, 16(r1)
+	mtcr	r6
+	lwz	r5, 20(r1)
+	lwz	r6, 24(r1)
+	lwz	r0, 52(r1)
+	lwz	r7, 28(r1)
+	lwz	r8, 32(r1)
+	mtlr	r0
+	lwz	r9, 36(r1)
+	lwz	r10,40(r1)
+	addi	r1, r1, 48
+	bctr
+#else
+_GLOBAL(mcount)
+_GLOBAL(_mcount)
+	stwu	r1,-48(r1)
+	stw	r3, 12(r1)
+	stw	r4, 16(r1)
+	stw	r5, 20(r1)
+	stw	r6, 24(r1)
+	mflr	r3
+	lwz	r4, 52(r1)
+	mfcr	r5
+	stw	r7, 28(r1)
+	stw	r8, 32(r1)
+	stw	r9, 36(r1)
+	stw	r10,40(r1)
+	stw	r3, 44(r1)
+	stw	r5, 8(r1)
+
+	subi	r3, r3, MCOUNT_INSN_SIZE
+	LOAD_REG_ADDR(r5, ftrace_trace_function)
+	lwz	r5,0(r5)
+
+	mtctr	r5
+	bctrl
+
+	nop
+
+	lwz	r6, 8(r1)
+	lwz	r0, 44(r1)
+	lwz	r3, 12(r1)
+	mtctr	r0
+	lwz	r4, 16(r1)
+	mtcr	r6
+	lwz	r5, 20(r1)
+	lwz	r6, 24(r1)
+	lwz	r0, 52(r1)
+	lwz	r7, 28(r1)
+	lwz	r8, 32(r1)
+	mtlr	r0
+	lwz	r9, 36(r1)
+	lwz	r10,40(r1)
+	addi	r1, r1, 48
+	bctr
+#endif
+
+_GLOBAL(ftrace_stub)
+	blr
+
+#endif /* CONFIG_MCOUNT */

arch/powerpc/kernel/entry_64.S

@@ -31,6 +31,7 @@
 #include <asm/bug.h>
 #include <asm/ptrace.h>
 #include <asm/irqflags.h>
+#include <asm/ftrace.h>
 
 /*
  * System calls.
@@ -870,3 +871,67 @@ _GLOBAL(enter_prom)
 	ld	r0,16(r1)
 	mtlr    r0
         blr
+
+#ifdef CONFIG_FTRACE
+#ifdef CONFIG_DYNAMIC_FTRACE
+_GLOBAL(mcount)
+_GLOBAL(_mcount)
+	/* Taken from output of objdump from lib64/glibc */
+	mflr	r3
+	stdu	r1, -112(r1)
+	std	r3, 128(r1)
+	subi	r3, r3, MCOUNT_INSN_SIZE
+	.globl mcount_call
+mcount_call:
+	bl	ftrace_stub
+	nop
+	ld	r0, 128(r1)
+	mtlr	r0
+	addi	r1, r1, 112
+	blr
+
+_GLOBAL(ftrace_caller)
+	/* Taken from output of objdump from lib64/glibc */
+	mflr	r3
+	ld	r11, 0(r1)
+	stdu	r1, -112(r1)
+	std	r3, 128(r1)
+	ld	r4, 16(r11)
+	subi	r3, r3, MCOUNT_INSN_SIZE
+.globl ftrace_call
+ftrace_call:
+	bl	ftrace_stub
+	nop
+	ld	r0, 128(r1)
+	mtlr	r0
+	addi	r1, r1, 112
+_GLOBAL(ftrace_stub)
+	blr
+#else
+_GLOBAL(mcount)
+	blr
+
+_GLOBAL(_mcount)
+	/* Taken from output of objdump from lib64/glibc */
+	mflr	r3
+	ld	r11, 0(r1)
+	stdu	r1, -112(r1)
+	std	r3, 128(r1)
+	ld	r4, 16(r11)
+
+	subi	r3, r3, MCOUNT_INSN_SIZE
+	LOAD_REG_ADDR(r5,ftrace_trace_function)
+	ld	r5,0(r5)
+	ld	r5,0(r5)
+	mtctr	r5
+	bctrl
+
+	nop
+	ld	r0, 128(r1)
+	mtlr	r0
+	addi	r1, r1, 112
+_GLOBAL(ftrace_stub)
+	blr
+
+#endif
+#endif

arch/powerpc/kernel/ftrace.c

@@ -0,0 +1,154 @@
+/*
+ * Code for replacing ftrace calls with jumps.
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ *
+ * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.
+ *
+ */
+
+#include <linux/spinlock.h>
+#include <linux/hardirq.h>
+#include <linux/ftrace.h>
+#include <linux/percpu.h>
+#include <linux/init.h>
+#include <linux/list.h>
+
+#include <asm/cacheflush.h>
+#include <asm/ftrace.h>
+
+
+static unsigned int ftrace_nop = 0x60000000;
+
+#ifdef CONFIG_PPC32
+# define GET_ADDR(addr) addr
+#else
+/* PowerPC64's functions are data that points to the functions */
+# define GET_ADDR(addr) *(unsigned long *)addr
+#endif
+
+
+static unsigned int notrace ftrace_calc_offset(long ip, long addr)
+{
+	return (int)(addr - ip);
+}
+
+notrace unsigned char *ftrace_nop_replace(void)
+{
+	return (char *)&ftrace_nop;
+}
+
+notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
+{
+	static unsigned int op;
+
+	/*
+	 * It would be nice to just use create_function_call, but that will
+	 * update the code itself. Here we need to just return the
+	 * instruction that is going to be modified, without modifying the
+	 * code.
+	 */
+	addr = GET_ADDR(addr);
+
+	/* Set to "bl addr" */
+	op = 0x48000001 | (ftrace_calc_offset(ip, addr) & 0x03fffffc);
+
+	/*
+	 * No locking needed, this must be called via kstop_machine
+	 * which in essence is like running on a uniprocessor machine.
+	 */
+	return (unsigned char *)&op;
+}
+
+#ifdef CONFIG_PPC64
+# define _ASM_ALIGN	" .align 3 "
+# define _ASM_PTR	" .llong "
+#else
+# define _ASM_ALIGN	" .align 2 "
+# define _ASM_PTR	" .long "
+#endif
+
+notrace int
+ftrace_modify_code(unsigned long ip, unsigned char *old_code,
+		   unsigned char *new_code)
+{
+	unsigned replaced;
+	unsigned old = *(unsigned *)old_code;
+	unsigned new = *(unsigned *)new_code;
+	int faulted = 0;
+
+	/*
+	 * Note: Due to modules and __init, code can
+	 *  disappear and change, we need to protect against faulting
+	 *  as well as code changing.
+	 *
+	 * No real locking needed, this code is run through
+	 * kstop_machine.
+	 */
+	asm volatile (
+		"1: lwz		%1, 0(%2)\n"
+		"   cmpw	%1, %5\n"
+		"   bne		2f\n"
+		"   stwu	%3, 0(%2)\n"
+		"2:\n"
+		".section .fixup, \"ax\"\n"
+		"3:	li %0, 1\n"
+		"	b 2b\n"
+		".previous\n"
+		".section __ex_table,\"a\"\n"
+		_ASM_ALIGN "\n"
+		_ASM_PTR "1b, 3b\n"
+		".previous"
+		: "=r"(faulted), "=r"(replaced)
+		: "r"(ip), "r"(new),
+		  "0"(faulted), "r"(old)
+		: "memory");
+
+	if (replaced != old && replaced != new)
+		faulted = 2;
+
+	if (!faulted)
+		flush_icache_range(ip, ip + 8);
+
+	return faulted;
+}
+
+notrace int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+	unsigned long ip = (unsigned long)(&ftrace_call);
+	unsigned char old[MCOUNT_INSN_SIZE], *new;
+	int ret;
+
+	memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
+	new = ftrace_call_replace(ip, (unsigned long)func);
+	ret = ftrace_modify_code(ip, old, new);
+
+	return ret;
+}
+
+notrace int ftrace_mcount_set(unsigned long *data)
+{
+	unsigned long ip = (long)(&mcount_call);
+	unsigned long *addr = data;
+	unsigned char old[MCOUNT_INSN_SIZE], *new;
+
+	/*
+	 * Replace the mcount stub with a pointer to the
+	 * ip recorder function.
+	 */
+	memcpy(old, &mcount_call, MCOUNT_INSN_SIZE);
+	new = ftrace_call_replace(ip, *addr);
+	*addr = ftrace_modify_code(ip, old, new);
+
+	return 0;
+}
+
+int __init ftrace_dyn_arch_init(void *data)
+{
+	/* This is running in kstop_machine */
+
+	ftrace_mcount_set(data);
+
+	return 0;
+}
+

arch/powerpc/kernel/io.c

@@ -120,7 +120,8 @@ EXPORT_SYMBOL(_outsl_ns);
 
 #define IO_CHECK_ALIGN(v,a) ((((unsigned long)(v)) & ((a) - 1)) == 0)
 
-void _memset_io(volatile void __iomem *addr, int c, unsigned long n)
+notrace void
+_memset_io(volatile void __iomem *addr, int c, unsigned long n)
 {
 	void *p = (void __force *)addr;
 	u32 lc = c;

arch/powerpc/kernel/irq.c

@@ -98,7 +98,7 @@ EXPORT_SYMBOL(irq_desc);
 
 int distribute_irqs = 1;
 
-static inline unsigned long get_hard_enabled(void)
+static inline notrace unsigned long get_hard_enabled(void)
 {
 	unsigned long enabled;
 
@@ -108,13 +108,13 @@ static inline unsigned long get_hard_enabled(void)
 	return enabled;
 }
 
-static inline void set_soft_enabled(unsigned long enable)
+static inline notrace void set_soft_enabled(unsigned long enable)
 {
 	__asm__ __volatile__("stb %0,%1(13)"
 	: : "r" (enable), "i" (offsetof(struct paca_struct, soft_enabled)));
 }
 
-void raw_local_irq_restore(unsigned long en)
+notrace void raw_local_irq_restore(unsigned long en)
 {
 	/*
 	 * get_paca()->soft_enabled = en;

arch/powerpc/kernel/ppc_ksyms.c

@@ -42,6 +42,7 @@
 #include <asm/div64.h>
 #include <asm/signal.h>
 #include <asm/dcr.h>
+#include <asm/ftrace.h>
 
 #ifdef CONFIG_PPC32
 extern void transfer_to_handler(void);
@@ -67,6 +68,10 @@ EXPORT_SYMBOL(single_step_exception);
 EXPORT_SYMBOL(sys_sigreturn);
 #endif
 
+#ifdef CONFIG_FTRACE
+EXPORT_SYMBOL(_mcount);
+#endif
+
 EXPORT_SYMBOL(strcpy);
 EXPORT_SYMBOL(strncpy);
 EXPORT_SYMBOL(strcat);

arch/powerpc/kernel/setup_32.c

@@ -81,7 +81,7 @@ int ucache_bsize;
  * from the address that it was linked at, so we must use RELOC/PTRRELOC
  * to access static data (including strings).  -- paulus
  */
-unsigned long __init early_init(unsigned long dt_ptr)
+notrace unsigned long __init early_init(unsigned long dt_ptr)
 {
 	unsigned long offset = reloc_offset();
 	struct cpu_spec *spec;
@@ -111,7 +111,7 @@ unsigned long __init early_init(unsigned long dt_ptr)
  * This is called very early on the boot process, after a minimal
  * MMU environment has been set up but before MMU_init is called.
  */
-void __init machine_init(unsigned long dt_ptr, unsigned long phys)
+notrace void __init machine_init(unsigned long dt_ptr, unsigned long phys)
 {
 	/* Enable early debugging if any specified (see udbg.h) */
 	udbg_early_init();
@@ -133,7 +133,7 @@ void __init machine_init(unsigned long dt_ptr, unsigned long phys)
 
 #ifdef CONFIG_BOOKE_WDT
 /* Checks wdt=x and wdt_period=xx command-line option */
-int __init early_parse_wdt(char *p)
+notrace int __init early_parse_wdt(char *p)
 {
 	if (p && strncmp(p, "0", 1) != 0)
 	       booke_wdt_enabled = 1;

arch/powerpc/platforms/powermac/Makefile

@@ -1,5 +1,10 @@
 CFLAGS_bootx_init.o  		+= -fPIC
 
+ifdef CONFIG_FTRACE
+# Do not trace early boot code
+CFLAGS_REMOVE_bootx_init.o = -pg
+endif
+
 obj-y				+= pic.o setup.o time.o feature.o pci.o \
 				   sleep.o low_i2c.o cache.o pfunc_core.o \
 				   pfunc_base.o

arch/sparc64/Kconfig

@@ -11,6 +11,8 @@ config SPARC
 config SPARC64
 	bool
 	default y
+	select HAVE_DYNAMIC_FTRACE
+	select HAVE_FTRACE
 	select HAVE_IDE
 	select HAVE_LMB
 	select HAVE_ARCH_KGDB

arch/sparc64/Kconfig.debug

@@ -33,7 +33,7 @@ config DEBUG_PAGEALLOC
 
 config MCOUNT
 	bool
-	depends on STACK_DEBUG
+	depends on STACK_DEBUG || FTRACE
 	default y
 
 config FRAME_POINTER

arch/sparc64/kernel/Makefile

@@ -14,6 +14,7 @@ obj-y		:= process.o setup.o cpu.o idprom.o \
 		   power.o sbus.o sparc64_ksyms.o chmc.o \
 		   visemul.o prom.o of_device.o hvapi.o sstate.o mdesc.o
 
+obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o
 obj-$(CONFIG_STACKTRACE) += stacktrace.o
 obj-$(CONFIG_PCI)	 += ebus.o pci_common.o \
 			    pci_psycho.o pci_sabre.o pci_schizo.o \

arch/sparc64/kernel/ftrace.c

@@ -0,0 +1,94 @@
+#include <linux/spinlock.h>
+#include <linux/hardirq.h>
+#include <linux/ftrace.h>
+#include <linux/percpu.h>
+#include <linux/init.h>
+#include <linux/list.h>
+
+#include <asm/ftrace.h>
+
+static const u32 ftrace_nop = 0x01000000;
+
+notrace unsigned char *ftrace_nop_replace(void)
+{
+	return (char *)&ftrace_nop;
+}
+
+notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
+{
+	static u32 call;
+	s32 off;
+
+	off = ((s32)addr - (s32)ip);
+	call = 0x40000000 | ((u32)off >> 2);
+
+	return (unsigned char *) &call;
+}
+
+notrace int
+ftrace_modify_code(unsigned long ip, unsigned char *old_code,
+		   unsigned char *new_code)
+{
+	u32 old = *(u32 *)old_code;
+	u32 new = *(u32 *)new_code;
+	u32 replaced;
+	int faulted;
+
+	__asm__ __volatile__(
+	"1:	cas	[%[ip]], %[old], %[new]\n"
+	"	flush	%[ip]\n"
+	"	mov	0, %[faulted]\n"
+	"2:\n"
+	"	.section .fixup,#alloc,#execinstr\n"
+	"	.align	4\n"
+	"3:	sethi	%%hi(2b), %[faulted]\n"
+	"	jmpl	%[faulted] + %%lo(2b), %%g0\n"
+	"	 mov	1, %[faulted]\n"
+	"	.previous\n"
+	"	.section __ex_table,\"a\"\n"
+	"	.align	4\n"
+	"	.word	1b, 3b\n"
+	"	.previous\n"
+	: "=r" (replaced), [faulted] "=r" (faulted)
+	: [new] "0" (new), [old] "r" (old), [ip] "r" (ip)
+	: "memory");
+
+	if (replaced != old && replaced != new)
+		faulted = 2;
+
+	return faulted;
+}
+
+notrace int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+	unsigned long ip = (unsigned long)(&ftrace_call);
+	unsigned char old[MCOUNT_INSN_SIZE], *new;
+
+	memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
+	new = ftrace_call_replace(ip, (unsigned long)func);
+	return ftrace_modify_code(ip, old, new);
+}
+
+notrace int ftrace_mcount_set(unsigned long *data)
+{
+	unsigned long ip = (long)(&mcount_call);
+	unsigned long *addr = data;
+	unsigned char old[MCOUNT_INSN_SIZE], *new;
+
+	/*
+	 * Replace the mcount stub with a pointer to the
+	 * ip recorder function.
+	 */
+	memcpy(old, &mcount_call, MCOUNT_INSN_SIZE);
+	new = ftrace_call_replace(ip, *addr);
+	*addr = ftrace_modify_code(ip, old, new);
+
+	return 0;
+}
+
+
+int __init ftrace_dyn_arch_init(void *data)
+{
+	ftrace_mcount_set(data);
+	return 0;
+}

arch/sparc64/kernel/sparc64_ksyms.c

@@ -53,6 +53,7 @@
 #include <asm/ns87303.h>
 #include <asm/timer.h>
 #include <asm/cpudata.h>
+#include <asm/ftrace.h>
 
 struct poll {
 	int fd;
@@ -111,8 +112,7 @@ EXPORT_SYMBOL(__write_trylock);
 EXPORT_SYMBOL(smp_call_function);
 #endif /* CONFIG_SMP */
 
-#if defined(CONFIG_MCOUNT)
-extern void _mcount(void);
+#ifdef CONFIG_MCOUNT
 EXPORT_SYMBOL(_mcount);
 #endif
 

arch/sparc64/lib/mcount.S

@@ -28,10 +28,13 @@ ovstack:
 	.skip		OVSTACKSIZE
 #endif
 	.text
-	.align 32
-	.globl mcount, _mcount
-mcount:
+	.align		32
+	.globl		_mcount
+	.type		_mcount,#function
+	.globl		mcount
+	.type		mcount,#function
 _mcount:
+mcount:
 #ifdef CONFIG_STACK_DEBUG
 	/*
 	 * Check whether %sp is dangerously low.
@@ -55,6 +58,53 @@ _mcount:
 	 or		%g3, %lo(panicstring), %o0
 	call		prom_halt
 	 nop
+1:
+#endif
+#ifdef CONFIG_FTRACE
+#ifdef CONFIG_DYNAMIC_FTRACE
+	mov		%o7, %o0
+	.globl		mcount_call
+mcount_call:
+	call		ftrace_stub
+	 mov		%o0, %o7
+#else
+	sethi		%hi(ftrace_trace_function), %g1
+	sethi		%hi(ftrace_stub), %g2
+	ldx		[%g1 + %lo(ftrace_trace_function)], %g1
+	or		%g2, %lo(ftrace_stub), %g2
+	cmp		%g1, %g2
+	be,pn		%icc, 1f
+	 mov		%i7, %o1
+	jmpl		%g1, %g0
+	 mov		%o7, %o0
+	/* not reached */
+1:
 #endif
-1:	retl
+#endif
+	retl
 	 nop
+	.size		_mcount,.-_mcount
+	.size		mcount,.-mcount
+
+#ifdef CONFIG_FTRACE
+	.globl		ftrace_stub
+	.type		ftrace_stub,#function
+ftrace_stub:
+	retl
+	 nop
+	.size		ftrace_stub,.-ftrace_stub
+#ifdef CONFIG_DYNAMIC_FTRACE
+	.globl		ftrace_caller
+	.type		ftrace_caller,#function
+ftrace_caller:
+	mov		%i7, %o1
+	mov		%o7, %o0
+	.globl		ftrace_call
+ftrace_call:
+	call		ftrace_stub
+	 mov		%o0, %o7
+	retl
+	 nop
+	.size		ftrace_caller,.-ftrace_caller
+#endif
+#endif

arch/x86/Kconfig

@@ -23,6 +23,8 @@ config X86
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
+	select HAVE_DYNAMIC_FTRACE
+	select HAVE_FTRACE
 	select HAVE_KVM if ((X86_32 && !X86_VOYAGER && !X86_VISWS && !X86_NUMAQ) || X86_64)
 	select HAVE_ARCH_KGDB if !X86_VOYAGER
 

arch/x86/Kconfig.debug

@@ -172,6 +172,14 @@ config IOMMU_LEAK
 	  Add a simple leak tracer to the IOMMU code. This is useful when you
 	  are debugging a buggy device driver that leaks IOMMU mappings.
 
+config PAGE_FAULT_HANDLERS
+	bool "Custom page fault handlers"
+	depends on DEBUG_KERNEL
+	help
+	  Allow the use of custom page fault handlers. A kernel module may
+	  register a function that is called on every page fault. Custom
+	  handlers are used by some debugging and reverse engineering tools.
+
 #
 # IO delay types:
 #

arch/x86/kernel/Makefile

@@ -6,6 +6,13 @@ extra-y                := head_$(BITS).o head$(BITS).o init_task.o vmlinux.lds
 
 CPPFLAGS_vmlinux.lds += -U$(UTS_MACHINE)
 
+ifdef CONFIG_FTRACE
+# Do not profile debug utilities
+CFLAGS_REMOVE_tsc_64.o = -pg
+CFLAGS_REMOVE_tsc_32.o = -pg
+CFLAGS_REMOVE_rtc.o = -pg
+endif
+
 #
 # vsyscalls (which work on the user stack) should have
 # no stack-protector checks:
@@ -56,6 +63,7 @@ obj-$(CONFIG_X86_MPPARSE)	+= mpparse.o
 obj-$(CONFIG_X86_LOCAL_APIC)	+= apic_$(BITS).o nmi_$(BITS).o
 obj-$(CONFIG_X86_IO_APIC)	+= io_apic_$(BITS).o
 obj-$(CONFIG_X86_REBOOTFIXUPS)	+= reboot_fixups_32.o
+obj-$(CONFIG_DYNAMIC_FTRACE)	+= ftrace.o
 obj-$(CONFIG_KEXEC)		+= machine_kexec_$(BITS).o
 obj-$(CONFIG_KEXEC)		+= relocate_kernel_$(BITS).o crash.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump_$(BITS).o

arch/x86/kernel/alternative.c

@@ -1,6 +1,6 @@
 #include <linux/module.h>
 #include <linux/sched.h>
-#include <linux/spinlock.h>
+#include <linux/mutex.h>
 #include <linux/list.h>
 #include <linux/kprobes.h>
 #include <linux/mm.h>
@@ -143,7 +143,7 @@ static const unsigned char *const p6_nops[ASM_NOP_MAX+1] = {
 #ifdef CONFIG_X86_64
 
 extern char __vsyscall_0;
-static inline const unsigned char*const * find_nop_table(void)
+const unsigned char *const *find_nop_table(void)
 {
 	return boot_cpu_data.x86_vendor != X86_VENDOR_INTEL ||
 	       boot_cpu_data.x86 < 6 ? k8_nops : p6_nops;
@@ -162,7 +162,7 @@ static const struct nop {
 	{ -1, NULL }
 };
 
-static const unsigned char*const * find_nop_table(void)
+const unsigned char *const *find_nop_table(void)
 {
 	const unsigned char *const *noptable = intel_nops;
 	int i;
@@ -279,7 +279,7 @@ struct smp_alt_module {
 	struct list_head next;
 };
 static LIST_HEAD(smp_alt_modules);
-static DEFINE_SPINLOCK(smp_alt);
+static DEFINE_MUTEX(smp_alt);
 static int smp_mode = 1;	/* protected by smp_alt */
 
 void alternatives_smp_module_add(struct module *mod, char *name,
@@ -312,12 +312,12 @@ void alternatives_smp_module_add(struct module *mod, char *name,
 		__func__, smp->locks, smp->locks_end,
 		smp->text, smp->text_end, smp->name);
 
-	spin_lock(&smp_alt);
+	mutex_lock(&smp_alt);
 	list_add_tail(&smp->next, &smp_alt_modules);
 	if (boot_cpu_has(X86_FEATURE_UP))
 		alternatives_smp_unlock(smp->locks, smp->locks_end,
 					smp->text, smp->text_end);
-	spin_unlock(&smp_alt);
+	mutex_unlock(&smp_alt);
 }
 
 void alternatives_smp_module_del(struct module *mod)
@@ -327,17 +327,17 @@ void alternatives_smp_module_del(struct module *mod)
 	if (smp_alt_once || noreplace_smp)
 		return;
 
-	spin_lock(&smp_alt);
+	mutex_lock(&smp_alt);
 	list_for_each_entry(item, &smp_alt_modules, next) {
 		if (mod != item->mod)
 			continue;
 		list_del(&item->next);
-		spin_unlock(&smp_alt);
+		mutex_unlock(&smp_alt);
 		DPRINTK("%s: %s\n", __func__, item->name);
 		kfree(item);
 		return;
 	}
-	spin_unlock(&smp_alt);
+	mutex_unlock(&smp_alt);
 }
 
 void alternatives_smp_switch(int smp)
@@ -359,7 +359,7 @@ void alternatives_smp_switch(int smp)
 		return;
 	BUG_ON(!smp && (num_online_cpus() > 1));
 
-	spin_lock(&smp_alt);
+	mutex_lock(&smp_alt);
 
 	/*
 	 * Avoid unnecessary switches because it forces JIT based VMs to
@@ -383,7 +383,7 @@ void alternatives_smp_switch(int smp)
 						mod->text, mod->text_end);
 	}
 	smp_mode = smp;
-	spin_unlock(&smp_alt);
+	mutex_unlock(&smp_alt);
 }
 
 #endif

arch/x86/kernel/entry_32.S

@@ -51,6 +51,7 @@
 #include <asm/percpu.h>
 #include <asm/dwarf2.h>
 #include <asm/processor-flags.h>
+#include <asm/ftrace.h>
 #include "irq_vectors.h"
 
 /*
@@ -1110,6 +1111,77 @@ ENDPROC(xen_failsafe_callback)
 
 #endif	/* CONFIG_XEN */
 
+#ifdef CONFIG_FTRACE
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+ENTRY(mcount)
+	pushl %eax
+	pushl %ecx
+	pushl %edx
+	movl 0xc(%esp), %eax
+	subl $MCOUNT_INSN_SIZE, %eax
+
+.globl mcount_call
+mcount_call:
+	call ftrace_stub
+
+	popl %edx
+	popl %ecx
+	popl %eax
+
+	ret
+END(mcount)
+
+ENTRY(ftrace_caller)
+	pushl %eax
+	pushl %ecx
+	pushl %edx
+	movl 0xc(%esp), %eax
+	movl 0x4(%ebp), %edx
+	subl $MCOUNT_INSN_SIZE, %eax
+
+.globl ftrace_call
+ftrace_call:
+	call ftrace_stub
+
+	popl %edx
+	popl %ecx
+	popl %eax
+
+.globl ftrace_stub
+ftrace_stub:
+	ret
+END(ftrace_caller)
+
+#else /* ! CONFIG_DYNAMIC_FTRACE */
+
+ENTRY(mcount)
+	cmpl $ftrace_stub, ftrace_trace_function
+	jnz trace
+.globl ftrace_stub
+ftrace_stub:
+	ret
+
+	/* taken from glibc */
+trace:
+	pushl %eax
+	pushl %ecx
+	pushl %edx
+	movl 0xc(%esp), %eax
+	movl 0x4(%ebp), %edx
+	subl $MCOUNT_INSN_SIZE, %eax
+
+	call *ftrace_trace_function
+
+	popl %edx
+	popl %ecx
+	popl %eax
+
+	jmp ftrace_stub
+END(mcount)
+#endif /* CONFIG_DYNAMIC_FTRACE */
+#endif /* CONFIG_FTRACE */
+
 .section .rodata,"a"
 #include "syscall_table_32.S"
 

arch/x86/kernel/entry_64.S

@@ -51,9 +51,115 @@
 #include <asm/page.h>
 #include <asm/irqflags.h>
 #include <asm/paravirt.h>
+#include <asm/ftrace.h>
 
 	.code64
 
+#ifdef CONFIG_FTRACE
+#ifdef CONFIG_DYNAMIC_FTRACE
+ENTRY(mcount)
+
+	subq $0x38, %rsp
+	movq %rax, (%rsp)
+	movq %rcx, 8(%rsp)
+	movq %rdx, 16(%rsp)
+	movq %rsi, 24(%rsp)
+	movq %rdi, 32(%rsp)
+	movq %r8, 40(%rsp)
+	movq %r9, 48(%rsp)
+
+	movq 0x38(%rsp), %rdi
+	subq $MCOUNT_INSN_SIZE, %rdi
+
+.globl mcount_call
+mcount_call:
+	call ftrace_stub
+
+	movq 48(%rsp), %r9
+	movq 40(%rsp), %r8
+	movq 32(%rsp), %rdi
+	movq 24(%rsp), %rsi
+	movq 16(%rsp), %rdx
+	movq 8(%rsp), %rcx
+	movq (%rsp), %rax
+	addq $0x38, %rsp
+
+	retq
+END(mcount)
+
+ENTRY(ftrace_caller)
+
+	/* taken from glibc */
+	subq $0x38, %rsp
+	movq %rax, (%rsp)
+	movq %rcx, 8(%rsp)
+	movq %rdx, 16(%rsp)
+	movq %rsi, 24(%rsp)
+	movq %rdi, 32(%rsp)
+	movq %r8, 40(%rsp)
+	movq %r9, 48(%rsp)
+
+	movq 0x38(%rsp), %rdi
+	movq 8(%rbp), %rsi
+	subq $MCOUNT_INSN_SIZE, %rdi
+
+.globl ftrace_call
+ftrace_call:
+	call ftrace_stub
+
+	movq 48(%rsp), %r9
+	movq 40(%rsp), %r8
+	movq 32(%rsp), %rdi
+	movq 24(%rsp), %rsi
+	movq 16(%rsp), %rdx
+	movq 8(%rsp), %rcx
+	movq (%rsp), %rax
+	addq $0x38, %rsp
+
+.globl ftrace_stub
+ftrace_stub:
+	retq
+END(ftrace_caller)
+
+#else /* ! CONFIG_DYNAMIC_FTRACE */
+ENTRY(mcount)
+	cmpq $ftrace_stub, ftrace_trace_function
+	jnz trace
+.globl ftrace_stub
+ftrace_stub:
+	retq
+
+trace:
+	/* taken from glibc */
+	subq $0x38, %rsp
+	movq %rax, (%rsp)
+	movq %rcx, 8(%rsp)
+	movq %rdx, 16(%rsp)
+	movq %rsi, 24(%rsp)
+	movq %rdi, 32(%rsp)
+	movq %r8, 40(%rsp)
+	movq %r9, 48(%rsp)
+
+	movq 0x38(%rsp), %rdi
+	movq 8(%rbp), %rsi
+	subq $MCOUNT_INSN_SIZE, %rdi
+
+	call   *ftrace_trace_function
+
+	movq 48(%rsp), %r9
+	movq 40(%rsp), %r8
+	movq 32(%rsp), %rdi
+	movq 24(%rsp), %rsi
+	movq 16(%rsp), %rdx
+	movq 8(%rsp), %rcx
+	movq (%rsp), %rax
+	addq $0x38, %rsp
+
+	jmp ftrace_stub
+END(mcount)
+#endif /* CONFIG_DYNAMIC_FTRACE */
+#endif /* CONFIG_FTRACE */
+
 #ifndef CONFIG_PREEMPT
 #define retint_kernel retint_restore_args
 #endif	

arch/x86/kernel/ftrace.c

@@ -0,0 +1,141 @@
+/*
+ * Code for replacing ftrace calls with jumps.
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ *
+ * Thanks goes to Ingo Molnar, for suggesting the idea.
+ * Mathieu Desnoyers, for suggesting postponing the modifications.
+ * Arjan van de Ven, for keeping me straight, and explaining to me
+ * the dangers of modifying code on the run.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/hardirq.h>
+#include <linux/ftrace.h>
+#include <linux/percpu.h>
+#include <linux/init.h>
+#include <linux/list.h>
+
+#include <asm/alternative.h>
+#include <asm/ftrace.h>
+
+
+/* Long is fine, even if it is only 4 bytes ;-) */
+static long *ftrace_nop;
+
+union ftrace_code_union {
+	char code[MCOUNT_INSN_SIZE];
+	struct {
+		char e8;
+		int offset;
+	} __attribute__((packed));
+};
+
+
+static int notrace ftrace_calc_offset(long ip, long addr)
+{
+	return (int)(addr - ip);
+}
+
+notrace unsigned char *ftrace_nop_replace(void)
+{
+	return (char *)ftrace_nop;
+}
+
+notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
+{
+	static union ftrace_code_union calc;
+
+	calc.e8		= 0xe8;
+	calc.offset	= ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr);
+
+	/*
+	 * No locking needed, this must be called via kstop_machine
+	 * which in essence is like running on a uniprocessor machine.
+	 */
+	return calc.code;
+}
+
+notrace int
+ftrace_modify_code(unsigned long ip, unsigned char *old_code,
+		   unsigned char *new_code)
+{
+	unsigned replaced;
+	unsigned old = *(unsigned *)old_code; /* 4 bytes */
+	unsigned new = *(unsigned *)new_code; /* 4 bytes */
+	unsigned char newch = new_code[4];
+	int faulted = 0;
+
+	/*
+	 * Note: Due to modules and __init, code can
+	 *  disappear and change, we need to protect against faulting
+	 *  as well as code changing.
+	 *
+	 * No real locking needed, this code is run through
+	 * kstop_machine.
+	 */
+	asm volatile (
+		"1: lock\n"
+		"   cmpxchg %3, (%2)\n"
+		"   jnz 2f\n"
+		"   movb %b4, 4(%2)\n"
+		"2:\n"
+		".section .fixup, \"ax\"\n"
+		"3:	movl $1, %0\n"
+		"	jmp 2b\n"
+		".previous\n"
+		_ASM_EXTABLE(1b, 3b)
+		: "=r"(faulted), "=a"(replaced)
+		: "r"(ip), "r"(new), "c"(newch),
+		  "0"(faulted), "a"(old)
+		: "memory");
+	sync_core();
+
+	if (replaced != old && replaced != new)
+		faulted = 2;
+
+	return faulted;
+}
+
+notrace int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+	unsigned long ip = (unsigned long)(&ftrace_call);
+	unsigned char old[MCOUNT_INSN_SIZE], *new;
+	int ret;
+
+	memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
+	new = ftrace_call_replace(ip, (unsigned long)func);
+	ret = ftrace_modify_code(ip, old, new);
+
+	return ret;
+}
+
+notrace int ftrace_mcount_set(unsigned long *data)
+{
+	unsigned long ip = (long)(&mcount_call);
+	unsigned long *addr = data;
+	unsigned char old[MCOUNT_INSN_SIZE], *new;
+
+	/*
+	 * Replace the mcount stub with a pointer to the
+	 * ip recorder function.
+	 */
+	memcpy(old, &mcount_call, MCOUNT_INSN_SIZE);
+	new = ftrace_call_replace(ip, *addr);
+	*addr = ftrace_modify_code(ip, old, new);
+
+	return 0;
+}
+
+int __init ftrace_dyn_arch_init(void *data)
+{
+	const unsigned char *const *noptable = find_nop_table();
+
+	/* This is running in kstop_machine */
+
+	ftrace_mcount_set(data);
+
+	ftrace_nop = (unsigned long *)noptable[MCOUNT_INSN_SIZE];
+
+	return 0;
+}

arch/x86/kernel/i386_ksyms_32.c

@@ -1,7 +1,14 @@
 #include <linux/module.h>
+
 #include <asm/checksum.h>
-#include <asm/desc.h>
 #include <asm/pgtable.h>
+#include <asm/desc.h>
+#include <asm/ftrace.h>
+
+#ifdef CONFIG_FTRACE
+/* mcount is defined in assembly */
+EXPORT_SYMBOL(mcount);
+#endif
 
 /* Networking helper routines. */
 EXPORT_SYMBOL(csum_partial_copy_generic);

arch/x86/kernel/machine_kexec_32.c

@@ -11,6 +11,8 @@
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/numa.h>
+#include <linux/ftrace.h>
+
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
@@ -107,6 +109,8 @@ NORET_TYPE void machine_kexec(struct kimage *image)
 	unsigned long page_list[PAGES_NR];
 	void *control_page;
 
+	tracer_disable();
+
 	/* Interrupts aren't acceptable while we reboot */
 	local_irq_disable();
 

arch/x86/kernel/machine_kexec_64.c

@@ -11,6 +11,8 @@
 #include <linux/string.h>
 #include <linux/reboot.h>
 #include <linux/numa.h>
+#include <linux/ftrace.h>
+
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 #include <asm/mmu_context.h>
@@ -184,6 +186,8 @@ NORET_TYPE void machine_kexec(struct kimage *image)
 	unsigned long page_list[PAGES_NR];
 	void *control_page;
 
+	tracer_disable();
+
 	/* Interrupts aren't acceptable while we reboot */
 	local_irq_disable();
 

arch/x86/kernel/process_32.c

@@ -185,7 +185,10 @@ void cpu_idle(void)
 
 			local_irq_disable();
 			__get_cpu_var(irq_stat).idle_timestamp = jiffies;
+			/* Don't trace irqs off for idle */
+			stop_critical_timings();
 			idle();
+			start_critical_timings();
 		}
 		tick_nohz_restart_sched_tick();
 		preempt_enable_no_resched();

arch/x86/kernel/process_64.c

@@ -165,7 +165,10 @@ void cpu_idle(void)
 			 */
 			local_irq_disable();
 			enter_idle();
+			/* Don't trace irqs off for idle */
+			stop_critical_timings();
 			idle();
+			start_critical_timings();
 			/* In many cases the interrupt that ended idle
 			   has already called exit_idle. But some idle
 			   loops can be woken up without interrupt. */

arch/x86/kernel/vsyscall_64.c

@@ -42,7 +42,8 @@
 #include <asm/topology.h>
 #include <asm/vgtod.h>
 
-#define __vsyscall(nr) __attribute__ ((unused,__section__(".vsyscall_" #nr)))
+#define __vsyscall(nr) \
+		__attribute__ ((unused, __section__(".vsyscall_" #nr))) notrace
 #define __syscall_clobber "r11","cx","memory"
 
 /*

arch/x86/kernel/x8664_ksyms_64.c

@@ -2,13 +2,20 @@
    All C exports should go in the respective C files. */
 
 #include <linux/module.h>
-#include <net/checksum.h>
 #include <linux/smp.h>
 
+#include <net/checksum.h>
+
 #include <asm/processor.h>
-#include <asm/uaccess.h>
 #include <asm/pgtable.h>
+#include <asm/uaccess.h>
 #include <asm/desc.h>
+#include <asm/ftrace.h>
+
+#ifdef CONFIG_FTRACE
+/* mcount is defined in assembly */
+EXPORT_SYMBOL(mcount);
+#endif
 
 EXPORT_SYMBOL(kernel_thread);
 

arch/x86/lib/Makefile

@@ -5,6 +5,7 @@
 obj-$(CONFIG_SMP) := msr-on-cpu.o
 
 lib-y := delay_$(BITS).o
+lib-y += thunk_$(BITS).o
 lib-y += usercopy_$(BITS).o getuser_$(BITS).o putuser_$(BITS).o
 lib-y += memcpy_$(BITS).o
 

arch/x86/lib/thunk_32.S

@@ -0,0 +1,47 @@
+/*
+ * Trampoline to trace irqs off. (otherwise CALLER_ADDR1 might crash)
+ * Copyright 2008 by Steven Rostedt, Red Hat, Inc
+ *  (inspired by Andi Kleen's thunk_64.S)
+ * Subject to the GNU public license, v.2. No warranty of any kind.
+ */
+
+	#include <linux/linkage.h>
+
+#define ARCH_TRACE_IRQS_ON			\
+	pushl %eax;				\
+	pushl %ecx;				\
+	pushl %edx;				\
+	call trace_hardirqs_on;			\
+	popl %edx;				\
+	popl %ecx;				\
+	popl %eax;
+
+#define ARCH_TRACE_IRQS_OFF			\
+	pushl %eax;				\
+	pushl %ecx;				\
+	pushl %edx;				\
+	call trace_hardirqs_off;		\
+	popl %edx;				\
+	popl %ecx;				\
+	popl %eax;
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+	/* put return address in eax (arg1) */
+	.macro thunk_ra name,func
+	.globl \name
+\name:
+	pushl %eax
+	pushl %ecx
+	pushl %edx
+	/* Place EIP in the arg1 */
+	movl 3*4(%esp), %eax
+	call \func
+	popl %edx
+	popl %ecx
+	popl %eax
+	ret
+	.endm
+
+	thunk_ra trace_hardirqs_on_thunk,trace_hardirqs_on_caller
+	thunk_ra trace_hardirqs_off_thunk,trace_hardirqs_off_caller
+#endif

arch/x86/lib/thunk_64.S

@@ -2,6 +2,7 @@
  * Save registers before calling assembly functions. This avoids
  * disturbance of register allocation in some inline assembly constructs.
  * Copyright 2001,2002 by Andi Kleen, SuSE Labs.
+ * Added trace_hardirqs callers - Copyright 2007 Steven Rostedt, Red Hat, Inc.
  * Subject to the GNU public license, v.2. No warranty of any kind.
  */
 
@@ -42,8 +43,22 @@
 #endif	
 	
 #ifdef CONFIG_TRACE_IRQFLAGS
-	thunk trace_hardirqs_on_thunk,trace_hardirqs_on
-	thunk trace_hardirqs_off_thunk,trace_hardirqs_off
+	/* put return address in rdi (arg1) */
+	.macro thunk_ra name,func
+	.globl \name
+\name:
+	CFI_STARTPROC
+	SAVE_ARGS
+	/* SAVE_ARGS pushs 9 elements */
+	/* the next element would be the rip */
+	movq 9*8(%rsp), %rdi
+	call \func
+	jmp  restore
+	CFI_ENDPROC
+	.endm
+
+	thunk_ra trace_hardirqs_on_thunk,trace_hardirqs_on_caller
+	thunk_ra trace_hardirqs_off_thunk,trace_hardirqs_off_caller
 #endif
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC

arch/x86/mm/fault.c

@@ -49,6 +49,60 @@
 #define PF_RSVD		(1<<3)
 #define PF_INSTR	(1<<4)
 
+#ifdef CONFIG_PAGE_FAULT_HANDLERS
+static HLIST_HEAD(pf_handlers); /* protected by RCU */
+static DEFINE_SPINLOCK(pf_handlers_writer);
+
+void register_page_fault_handler(struct pf_handler *new_pfh)
+{
+	unsigned long flags;
+	spin_lock_irqsave(&pf_handlers_writer, flags);
+	hlist_add_head_rcu(&new_pfh->hlist, &pf_handlers);
+	spin_unlock_irqrestore(&pf_handlers_writer, flags);
+}
+EXPORT_SYMBOL_GPL(register_page_fault_handler);
+
+/**
+ * unregister_page_fault_handler:
+ * The caller must ensure @old_pfh is not in use anymore before freeing it.
+ * This function does not guarantee it. The list of handlers is protected by
+ * RCU, so you can do this by e.g. calling synchronize_rcu().
+ */
+void unregister_page_fault_handler(struct pf_handler *old_pfh)
+{
+	unsigned long flags;
+	spin_lock_irqsave(&pf_handlers_writer, flags);
+	hlist_del_rcu(&old_pfh->hlist);
+	spin_unlock_irqrestore(&pf_handlers_writer, flags);
+}
+EXPORT_SYMBOL_GPL(unregister_page_fault_handler);
+#endif
+
+/* returns non-zero if do_page_fault() should return */
+static int handle_custom_pf(struct pt_regs *regs, unsigned long error_code,
+							unsigned long address)
+{
+#ifdef CONFIG_PAGE_FAULT_HANDLERS
+	int ret = 0;
+	struct pf_handler *cur;
+	struct hlist_node *ncur;
+
+	if (hlist_empty(&pf_handlers))
+		return 0;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(cur, ncur, &pf_handlers, hlist) {
+		ret = cur->handler(regs, error_code, address);
+		if (ret)
+			break;
+	}
+	rcu_read_unlock();
+	return ret;
+#else
+	return 0;
+#endif
+}
+
 static inline int notify_page_fault(struct pt_regs *regs)
 {
 #ifdef CONFIG_KPROBES
@@ -606,6 +660,8 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
 
 	if (notify_page_fault(regs))
 		return;
+	if (handle_custom_pf(regs, error_code, address))
+		return;
 
 	/*
 	 * We fault-in kernel-space virtual memory on-demand. The

arch/x86/mm/init_32.c

@@ -710,6 +710,8 @@ void mark_rodata_ro(void)
 	unsigned long start = PFN_ALIGN(_text);
 	unsigned long size = PFN_ALIGN(_etext) - start;
 
+#ifndef CONFIG_DYNAMIC_FTRACE
+	/* Dynamic tracing modifies the kernel text section */
 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
 	printk(KERN_INFO "Write protecting the kernel text: %luk\n",
 		size >> 10);
@@ -722,6 +724,8 @@ void mark_rodata_ro(void)
 	printk(KERN_INFO "Testing CPA: write protecting again\n");
 	set_pages_ro(virt_to_page(start), size>>PAGE_SHIFT);
 #endif
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
 	start += size;
 	size = (unsigned long)__end_rodata - start;
 	set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);

arch/x86/mm/init_64.c

@@ -767,6 +767,13 @@ EXPORT_SYMBOL_GPL(rodata_test_data);
 void mark_rodata_ro(void)
 {
 	unsigned long start = PFN_ALIGN(_stext), end = PFN_ALIGN(__end_rodata);
+	unsigned long rodata_start =
+		((unsigned long)__start_rodata + PAGE_SIZE - 1) & PAGE_MASK;
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+	/* Dynamic tracing modifies the kernel text section */
+	start = rodata_start;
+#endif
 
 	printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
 	       (end - start) >> 10);
@@ -776,8 +783,7 @@ void mark_rodata_ro(void)
 	 * The rodata section (but not the kernel text!) should also be
 	 * not-executable.
 	 */
-	start = ((unsigned long)__start_rodata + PAGE_SIZE - 1) & PAGE_MASK;
-	set_memory_nx(start, (end - start) >> PAGE_SHIFT);
+	set_memory_nx(rodata_start, (end - rodata_start) >> PAGE_SHIFT);
 
 	rodata_test();
 

arch/x86/vdso/vclock_gettime.c

@@ -23,7 +23,7 @@
 
 #define gtod vdso_vsyscall_gtod_data
 
-static long vdso_fallback_gettime(long clock, struct timespec *ts)
+notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
 {
 	long ret;
 	asm("syscall" : "=a" (ret) :
@@ -31,7 +31,7 @@ static long vdso_fallback_gettime(long clock, struct timespec *ts)
 	return ret;
 }
 
-static inline long vgetns(void)
+notrace static inline long vgetns(void)
 {
 	long v;
 	cycles_t (*vread)(void);
@@ -40,7 +40,7 @@ static inline long vgetns(void)
 	return (v * gtod->clock.mult) >> gtod->clock.shift;
 }
 
-static noinline int do_realtime(struct timespec *ts)
+notrace static noinline int do_realtime(struct timespec *ts)
 {
 	unsigned long seq, ns;
 	do {
@@ -54,7 +54,8 @@ static noinline int do_realtime(struct timespec *ts)
 }
 
 /* Copy of the version in kernel/time.c which we cannot directly access */
-static void vset_normalized_timespec(struct timespec *ts, long sec, long nsec)
+notrace static void
+vset_normalized_timespec(struct timespec *ts, long sec, long nsec)
 {
 	while (nsec >= NSEC_PER_SEC) {
 		nsec -= NSEC_PER_SEC;
@@ -68,7 +69,7 @@ static void vset_normalized_timespec(struct timespec *ts, long sec, long nsec)
 	ts->tv_nsec = nsec;
 }
 
-static noinline int do_monotonic(struct timespec *ts)
+notrace static noinline int do_monotonic(struct timespec *ts)
 {
 	unsigned long seq, ns, secs;
 	do {
@@ -82,7 +83,7 @@ static noinline int do_monotonic(struct timespec *ts)
 	return 0;
 }
 
-int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
+notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
 {
 	if (likely(gtod->sysctl_enabled && gtod->clock.vread))
 		switch (clock) {
@@ -96,7 +97,7 @@ int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
 int clock_gettime(clockid_t, struct timespec *)
 	__attribute__((weak, alias("__vdso_clock_gettime")));
 
-int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
+notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
 {
 	long ret;
 	if (likely(gtod->sysctl_enabled && gtod->clock.vread)) {

arch/x86/vdso/vgetcpu.c

@@ -13,7 +13,8 @@
 #include <asm/vgtod.h>
 #include "vextern.h"
 
-long __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
+notrace long
+__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
 {
 	unsigned int p;
 

include/asm-arm/ftrace.h

@@ -0,0 +1,14 @@
+#ifndef _ASM_ARM_FTRACE
+#define _ASM_ARM_FTRACE
+
+#ifdef CONFIG_FTRACE
+#define MCOUNT_ADDR		((long)(mcount))
+#define MCOUNT_INSN_SIZE	4 /* sizeof mcount call */
+
+#ifndef __ASSEMBLY__
+extern void mcount(void);
+#endif
+
+#endif
+
+#endif /* _ASM_ARM_FTRACE */

include/asm-arm/kprobes.h

@@ -59,6 +59,7 @@ struct kprobe_ctlblk {
 };
 
 void arch_remove_kprobe(struct kprobe *);
+void kretprobe_trampoline(void);
 
 int kprobe_trap_handler(struct pt_regs *regs, unsigned int instr);
 int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr);

include/asm-powerpc/ftrace.h

@@ -0,0 +1,14 @@
+#ifndef _ASM_POWERPC_FTRACE
+#define _ASM_POWERPC_FTRACE
+
+#ifdef CONFIG_FTRACE
+#define MCOUNT_ADDR		((long)(_mcount))
+#define MCOUNT_INSN_SIZE	4 /* sizeof mcount call */
+
+#ifndef __ASSEMBLY__
+extern void _mcount(void);
+#endif
+
+#endif
+
+#endif /* _ASM_POWERPC_FTRACE */

include/asm-powerpc/hw_irq.h

@@ -59,6 +59,11 @@ extern void iseries_handle_interrupts(void);
 		get_paca()->hard_enabled = 0;	\
 	} while(0)
 
+static inline int irqs_disabled_flags(unsigned long flags)
+{
+	return flags == 0;
+}
+
 #else
 
 #if defined(CONFIG_BOOKE)
@@ -113,6 +118,11 @@ static inline void local_irq_save_ptr(unsigned long *flags)
 #define hard_irq_enable()	local_irq_enable()
 #define hard_irq_disable()	local_irq_disable()
 
+static inline int irqs_disabled_flags(unsigned long flags)
+{
+	return (flags & MSR_EE) == 0;
+}
+
 #endif /* CONFIG_PPC64 */
 
 /*

include/asm-sparc64/ftrace.h

@@ -0,0 +1,14 @@
+#ifndef _ASM_SPARC64_FTRACE
+#define _ASM_SPARC64_FTRACE
+
+#ifdef CONFIG_MCOUNT
+#define MCOUNT_ADDR		((long)(_mcount))
+#define MCOUNT_INSN_SIZE	4 /* sizeof mcount call */
+
+#ifndef __ASSEMBLY__
+extern void _mcount(void);
+#endif
+
+#endif
+
+#endif /* _ASM_SPARC64_FTRACE */

include/asm-x86/alternative.h

@@ -72,6 +72,8 @@ static inline void alternatives_smp_module_del(struct module *mod) {}
 static inline void alternatives_smp_switch(int smp) {}
 #endif	/* CONFIG_SMP */
 
+const unsigned char *const *find_nop_table(void);
+
 /*
  * Alternative instructions for different CPU types or capabilities.
  *

include/asm-x86/ftrace.h

@@ -0,0 +1,14 @@
+#ifndef _ASM_X86_FTRACE
+#define _ASM_SPARC64_FTRACE
+
+#ifdef CONFIG_FTRACE
+#define MCOUNT_ADDR		((long)(mcount))
+#define MCOUNT_INSN_SIZE	5 /* sizeof mcount call */
+
+#ifndef __ASSEMBLY__
+extern void mcount(void);
+#endif
+
+#endif /* CONFIG_FTRACE */
+
+#endif /* _ASM_X86_FTRACE */

include/asm-x86/irqflags.h

@@ -179,8 +179,6 @@ static inline void trace_hardirqs_fixup(void)
  * have a reliable stack. x86_64 only.
  */
 #define SWAPGS_UNSAFE_STACK	swapgs
-#define ARCH_TRACE_IRQS_ON		call trace_hardirqs_on_thunk
-#define ARCH_TRACE_IRQS_OFF		call trace_hardirqs_off_thunk
 #define ARCH_LOCKDEP_SYS_EXIT		call lockdep_sys_exit_thunk
 #define ARCH_LOCKDEP_SYS_EXIT_IRQ	\
 	TRACE_IRQS_ON; \
@@ -192,24 +190,6 @@ static inline void trace_hardirqs_fixup(void)
 	TRACE_IRQS_OFF;
 
 #else
-#define ARCH_TRACE_IRQS_ON			\
-	pushl %eax;				\
-	pushl %ecx;				\
-	pushl %edx;				\
-	call trace_hardirqs_on;			\
-	popl %edx;				\
-	popl %ecx;				\
-	popl %eax;
-
-#define ARCH_TRACE_IRQS_OFF			\
-	pushl %eax;				\
-	pushl %ecx;				\
-	pushl %edx;				\
-	call trace_hardirqs_off;		\
-	popl %edx;				\
-	popl %ecx;				\
-	popl %eax;
-
 #define ARCH_LOCKDEP_SYS_EXIT			\
 	pushl %eax;				\
 	pushl %ecx;				\
@@ -223,8 +203,8 @@ static inline void trace_hardirqs_fixup(void)
 #endif
 
 #ifdef CONFIG_TRACE_IRQFLAGS
-#  define TRACE_IRQS_ON		ARCH_TRACE_IRQS_ON
-#  define TRACE_IRQS_OFF	ARCH_TRACE_IRQS_OFF
+#  define TRACE_IRQS_ON		call trace_hardirqs_on_thunk;
+#  define TRACE_IRQS_OFF	call trace_hardirqs_off_thunk;
 #else
 #  define TRACE_IRQS_ON
 #  define TRACE_IRQS_OFF

include/asm-x86/kdebug.h

@@ -35,4 +35,13 @@ extern void show_regs(struct pt_regs *regs);
 extern unsigned long oops_begin(void);
 extern void oops_end(unsigned long, struct pt_regs *, int signr);
 
+struct pf_handler {
+	struct hlist_node hlist;
+	int (*handler)(struct pt_regs *regs, unsigned long error_code,
+						unsigned long address);
+};
+
+extern void register_page_fault_handler(struct pf_handler *new_pfh);
+extern void unregister_page_fault_handler(struct pf_handler *old_pfh);
+
 #endif

include/asm-x86/vsyscall.h

@@ -24,7 +24,8 @@ enum vsyscall_num {
 	((unused, __section__ (".vsyscall_gtod_data"),aligned(16)))
 #define __section_vsyscall_clock __attribute__ \
 	((unused, __section__ (".vsyscall_clock"),aligned(16)))
-#define __vsyscall_fn __attribute__ ((unused,__section__(".vsyscall_fn")))
+#define __vsyscall_fn \
+	__attribute__ ((unused, __section__(".vsyscall_fn"))) notrace
 
 #define VGETCPU_RDTSCP	1
 #define VGETCPU_LSL	2

include/linux/ftrace.h

@@ -0,0 +1,143 @@
+#ifndef _LINUX_FTRACE_H
+#define _LINUX_FTRACE_H
+
+#ifdef CONFIG_FTRACE
+
+#include <linux/linkage.h>
+#include <linux/fs.h>
+
+extern int ftrace_enabled;
+extern int
+ftrace_enable_sysctl(struct ctl_table *table, int write,
+		     struct file *filp, void __user *buffer, size_t *lenp,
+		     loff_t *ppos);
+
+typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip);
+
+struct ftrace_ops {
+	ftrace_func_t	  func;
+	struct ftrace_ops *next;
+};
+
+/*
+ * The ftrace_ops must be a static and should also
+ * be read_mostly.  These functions do modify read_mostly variables
+ * so use them sparely. Never free an ftrace_op or modify the
+ * next pointer after it has been registered. Even after unregistering
+ * it, the next pointer may still be used internally.
+ */
+int register_ftrace_function(struct ftrace_ops *ops);
+int unregister_ftrace_function(struct ftrace_ops *ops);
+void clear_ftrace_function(void);
+
+extern void ftrace_stub(unsigned long a0, unsigned long a1);
+
+#else /* !CONFIG_FTRACE */
+# define register_ftrace_function(ops) do { } while (0)
+# define unregister_ftrace_function(ops) do { } while (0)
+# define clear_ftrace_function(ops) do { } while (0)
+#endif /* CONFIG_FTRACE */
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+# define FTRACE_HASHBITS	10
+# define FTRACE_HASHSIZE	(1<<FTRACE_HASHBITS)
+
+enum {
+	FTRACE_FL_FREE		= (1 << 0),
+	FTRACE_FL_FAILED	= (1 << 1),
+	FTRACE_FL_FILTER	= (1 << 2),
+	FTRACE_FL_ENABLED	= (1 << 3),
+	FTRACE_FL_NOTRACE	= (1 << 4),
+	FTRACE_FL_CONVERTED	= (1 << 5),
+	FTRACE_FL_FROZEN	= (1 << 6),
+};
+
+struct dyn_ftrace {
+	struct hlist_node node;
+	unsigned long	  ip; /* address of mcount call-site */
+	unsigned long	  flags;
+};
+
+int ftrace_force_update(void);
+void ftrace_set_filter(unsigned char *buf, int len, int reset);
+
+/* defined in arch */
+extern int ftrace_ip_converted(unsigned long ip);
+extern unsigned char *ftrace_nop_replace(void);
+extern unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr);
+extern int ftrace_dyn_arch_init(void *data);
+extern int ftrace_mcount_set(unsigned long *data);
+extern int ftrace_modify_code(unsigned long ip, unsigned char *old_code,
+			      unsigned char *new_code);
+extern int ftrace_update_ftrace_func(ftrace_func_t func);
+extern void ftrace_caller(void);
+extern void ftrace_call(void);
+extern void mcount_call(void);
+
+extern int skip_trace(unsigned long ip);
+
+void ftrace_disable_daemon(void);
+void ftrace_enable_daemon(void);
+
+#else
+# define skip_trace(ip)				({ 0; })
+# define ftrace_force_update()			({ 0; })
+# define ftrace_set_filter(buf, len, reset)	do { } while (0)
+# define ftrace_disable_daemon()		do { } while (0)
+# define ftrace_enable_daemon()			do { } while (0)
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+/* totally disable ftrace - can not re-enable after this */
+void ftrace_kill(void);
+
+static inline void tracer_disable(void)
+{
+#ifdef CONFIG_FTRACE
+	ftrace_enabled = 0;
+#endif
+}
+
+#ifdef CONFIG_FRAME_POINTER
+/* TODO: need to fix this for ARM */
+# define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
+# define CALLER_ADDR1 ((unsigned long)__builtin_return_address(1))
+# define CALLER_ADDR2 ((unsigned long)__builtin_return_address(2))
+# define CALLER_ADDR3 ((unsigned long)__builtin_return_address(3))
+# define CALLER_ADDR4 ((unsigned long)__builtin_return_address(4))
+# define CALLER_ADDR5 ((unsigned long)__builtin_return_address(5))
+# define CALLER_ADDR6 ((unsigned long)__builtin_return_address(6))
+#else
+# define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
+# define CALLER_ADDR1 0UL
+# define CALLER_ADDR2 0UL
+# define CALLER_ADDR3 0UL
+# define CALLER_ADDR4 0UL
+# define CALLER_ADDR5 0UL
+# define CALLER_ADDR6 0UL
+#endif
+
+#ifdef CONFIG_IRQSOFF_TRACER
+  extern void time_hardirqs_on(unsigned long a0, unsigned long a1);
+  extern void time_hardirqs_off(unsigned long a0, unsigned long a1);
+#else
+# define time_hardirqs_on(a0, a1)		do { } while (0)
+# define time_hardirqs_off(a0, a1)		do { } while (0)
+#endif
+
+#ifdef CONFIG_PREEMPT_TRACER
+  extern void trace_preempt_on(unsigned long a0, unsigned long a1);
+  extern void trace_preempt_off(unsigned long a0, unsigned long a1);
+#else
+# define trace_preempt_on(a0, a1)		do { } while (0)
+# define trace_preempt_off(a0, a1)		do { } while (0)
+#endif
+
+#ifdef CONFIG_TRACING
+extern void
+ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3);
+#else
+static inline void
+ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
+#endif
+
+#endif /* _LINUX_FTRACE_H */

include/linux/irqflags.h

@@ -12,10 +12,10 @@
 #define _LINUX_TRACE_IRQFLAGS_H
 
 #ifdef CONFIG_TRACE_IRQFLAGS
-  extern void trace_hardirqs_on(void);
-  extern void trace_hardirqs_off(void);
   extern void trace_softirqs_on(unsigned long ip);
   extern void trace_softirqs_off(unsigned long ip);
+  extern void trace_hardirqs_on(void);
+  extern void trace_hardirqs_off(void);
 # define trace_hardirq_context(p)	((p)->hardirq_context)
 # define trace_softirq_context(p)	((p)->softirq_context)
 # define trace_hardirqs_enabled(p)	((p)->hardirqs_enabled)
@@ -41,6 +41,15 @@
 # define INIT_TRACE_IRQFLAGS
 #endif
 
+#if defined(CONFIG_IRQSOFF_TRACER) || \
+	defined(CONFIG_PREEMPT_TRACER)
+ extern void stop_critical_timings(void);
+ extern void start_critical_timings(void);
+#else
+# define stop_critical_timings() do { } while (0)
+# define start_critical_timings() do { } while (0)
+#endif
+
 #ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
 
 #include <asm/irqflags.h>

include/linux/kprobes.h

@@ -259,6 +259,10 @@ void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head);
 struct jprobe;
 struct kretprobe;
 
+static inline struct kprobe *get_kprobe(void *addr)
+{
+	return NULL;
+}
 static inline struct kprobe *kprobe_running(void)
 {
 	return NULL;

include/linux/linkage.h

@@ -3,6 +3,8 @@
 
 #include <asm/linkage.h>
 
+#define notrace __attribute__((no_instrument_function))
+
 #ifdef __cplusplus
 #define CPP_ASMLINKAGE extern "C"
 #else

include/linux/marker.h

@@ -44,8 +44,8 @@ struct marker {
 				 */
 	char state;		/* Marker state. */
 	char ptype;		/* probe type : 0 : single, 1 : multi */
-	void (*call)(const struct marker *mdata,	/* Probe wrapper */
-		void *call_private, const char *fmt, ...);
+				/* Probe wrapper */
+	void (*call)(const struct marker *mdata, void *call_private, ...);
 	struct marker_probe_closure single;
 	struct marker_probe_closure *multi;
 } __attribute__((aligned(8)));
@@ -58,8 +58,12 @@ struct marker {
  * Make sure the alignment of the structure in the __markers section will
  * not add unwanted padding between the beginning of the section and the
  * structure. Force alignment to the same alignment as the section start.
+ *
+ * The "generic" argument controls which marker enabling mechanism must be used.
+ * If generic is true, a variable read is used.
+ * If generic is false, immediate values are used.
  */
-#define __trace_mark(name, call_private, format, args...)		\
+#define __trace_mark(generic, name, call_private, format, args...)	\
 	do {								\
 		static const char __mstrtab_##name[]			\
 		__attribute__((section("__markers_strings")))		\
@@ -72,15 +76,14 @@ struct marker {
 		__mark_check_format(format, ## args);			\
 		if (unlikely(__mark_##name.state)) {			\
 			(*__mark_##name.call)				\
-				(&__mark_##name, call_private,		\
-				format, ## args);			\
+				(&__mark_##name, call_private, ## args);\
 		}							\
 	} while (0)
 
 extern void marker_update_probe_range(struct marker *begin,
 	struct marker *end);
 #else /* !CONFIG_MARKERS */
-#define __trace_mark(name, call_private, format, args...) \
+#define __trace_mark(generic, name, call_private, format, args...) \
 		__mark_check_format(format, ## args)
 static inline void marker_update_probe_range(struct marker *begin,
 	struct marker *end)
@@ -88,15 +91,30 @@ static inline void marker_update_probe_range(struct marker *begin,
 #endif /* CONFIG_MARKERS */
 
 /**
- * trace_mark - Marker
+ * trace_mark - Marker using code patching
  * @name: marker name, not quoted.
  * @format: format string
  * @args...: variable argument list
  *
- * Places a marker.
+ * Places a marker using optimized code patching technique (imv_read())
+ * to be enabled when immediate values are present.
  */
 #define trace_mark(name, format, args...) \
-	__trace_mark(name, NULL, format, ## args)
+	__trace_mark(0, name, NULL, format, ## args)
+
+/**
+ * _trace_mark - Marker using variable read
+ * @name: marker name, not quoted.
+ * @format: format string
+ * @args...: variable argument list
+ *
+ * Places a marker using a standard memory read (_imv_read()) to be
+ * enabled. Should be used for markers in code paths where instruction
+ * modification based enabling is not welcome. (__init and __exit functions,
+ * lockdep, some traps, printk).
+ */
+#define _trace_mark(name, format, args...) \
+	__trace_mark(1, name, NULL, format, ## args)
 
 /**
  * MARK_NOARGS - Format string for a marker with no argument.
@@ -117,9 +135,9 @@ static inline void __printf(1, 2) ___mark_check_format(const char *fmt, ...)
 extern marker_probe_func __mark_empty_function;
 
 extern void marker_probe_cb(const struct marker *mdata,
-	void *call_private, const char *fmt, ...);
+	void *call_private, ...);
 extern void marker_probe_cb_noarg(const struct marker *mdata,
-	void *call_private, const char *fmt, ...);
+	void *call_private, ...);
 
 /*
  * Connect a probe to a marker.

include/linux/preempt.h

@@ -10,7 +10,7 @@
 #include <linux/linkage.h>
 #include <linux/list.h>
 
-#ifdef CONFIG_DEBUG_PREEMPT
+#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)
   extern void add_preempt_count(int val);
   extern void sub_preempt_count(int val);
 #else
@@ -52,6 +52,34 @@ do { \
 	preempt_check_resched(); \
 } while (0)
 
+/* For debugging and tracer internals only! */
+#define add_preempt_count_notrace(val)			\
+	do { preempt_count() += (val); } while (0)
+#define sub_preempt_count_notrace(val)			\
+	do { preempt_count() -= (val); } while (0)
+#define inc_preempt_count_notrace() add_preempt_count_notrace(1)
+#define dec_preempt_count_notrace() sub_preempt_count_notrace(1)
+
+#define preempt_disable_notrace() \
+do { \
+	inc_preempt_count_notrace(); \
+	barrier(); \
+} while (0)
+
+#define preempt_enable_no_resched_notrace() \
+do { \
+	barrier(); \
+	dec_preempt_count_notrace(); \
+} while (0)
+
+/* preempt_check_resched is OK to trace */
+#define preempt_enable_notrace() \
+do { \
+	preempt_enable_no_resched_notrace(); \
+	barrier(); \
+	preempt_check_resched(); \
+} while (0)
+
 #else
 
 #define preempt_disable()		do { } while (0)
@@ -59,6 +87,10 @@ do { \
 #define preempt_enable()		do { } while (0)
 #define preempt_check_resched()		do { } while (0)
 
+#define preempt_disable_notrace()		do { } while (0)
+#define preempt_enable_no_resched_notrace()	do { } while (0)
+#define preempt_enable_notrace()		do { } while (0)
+
 #endif
 
 #ifdef CONFIG_PREEMPT_NOTIFIERS

include/linux/sched.h

@@ -246,6 +246,8 @@ extern asmlinkage void schedule_tail(struct task_struct *prev);
 extern void init_idle(struct task_struct *idle, int cpu);
 extern void init_idle_bootup_task(struct task_struct *idle);
 
+extern int runqueue_is_locked(void);
+
 extern cpumask_t nohz_cpu_mask;
 #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ)
 extern int select_nohz_load_balancer(int cpu);
@@ -2131,6 +2133,18 @@ static inline void arch_pick_mmap_layout(struct mm_struct *mm)
 }
 #endif
 
+#ifdef CONFIG_TRACING
+extern void
+__trace_special(void *__tr, void *__data,
+		unsigned long arg1, unsigned long arg2, unsigned long arg3);
+#else
+static inline void
+__trace_special(void *__tr, void *__data,
+		unsigned long arg1, unsigned long arg2, unsigned long arg3)
+{
+}
+#endif
+
 extern long sched_setaffinity(pid_t pid, const cpumask_t *new_mask);
 extern long sched_getaffinity(pid_t pid, cpumask_t *mask);
 
@@ -2225,6 +2239,8 @@ static inline void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
 }
 #endif /* CONFIG_MM_OWNER */
 
+#define TASK_STATE_TO_CHAR_STR "RSDTtZX"
+
 #endif /* __KERNEL__ */
 
 #endif

include/linux/writeback.h

@@ -105,6 +105,8 @@ extern int vm_highmem_is_dirtyable;
 extern int block_dump;
 extern int laptop_mode;
 
+extern unsigned long determine_dirtyable_memory(void);
+
 extern int dirty_ratio_handler(struct ctl_table *table, int write,
 		struct file *filp, void __user *buffer, size_t *lenp,
 		loff_t *ppos);

kernel/Makefile

@@ -11,6 +11,18 @@ obj-y     = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
 	    hrtimer.o rwsem.o nsproxy.o srcu.o semaphore.o \
 	    notifier.o ksysfs.o pm_qos_params.o sched_clock.o
 
+CFLAGS_REMOVE_sched.o = -pg -mno-spe
+
+ifdef CONFIG_FTRACE
+# Do not trace debug files and internal ftrace files
+CFLAGS_REMOVE_lockdep.o = -pg
+CFLAGS_REMOVE_lockdep_proc.o = -pg
+CFLAGS_REMOVE_mutex-debug.o = -pg
+CFLAGS_REMOVE_rtmutex-debug.o = -pg
+CFLAGS_REMOVE_cgroup-debug.o = -pg
+CFLAGS_REMOVE_sched_clock.o = -pg
+endif
+
 obj-$(CONFIG_SYSCTL_SYSCALL_CHECK) += sysctl_check.o
 obj-$(CONFIG_STACKTRACE) += stacktrace.o
 obj-y += time/
@@ -69,6 +81,8 @@ obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
 obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o
 obj-$(CONFIG_MARKERS) += marker.o
 obj-$(CONFIG_LATENCYTOP) += latencytop.o
+obj-$(CONFIG_FTRACE) += trace/
+obj-$(CONFIG_TRACING) += trace/
 
 ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
 # According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is

kernel/fork.c

@@ -909,7 +909,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 
 	rt_mutex_init_task(p);
 
-#ifdef CONFIG_TRACE_IRQFLAGS
+#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_LOCKDEP)
 	DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
 	DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
 #endif

kernel/lockdep.c

@@ -39,6 +39,7 @@
 #include <linux/irqflags.h>
 #include <linux/utsname.h>
 #include <linux/hash.h>
+#include <linux/ftrace.h>
 
 #include <asm/sections.h>
 
@@ -81,6 +82,8 @@ static int graph_lock(void)
 		__raw_spin_unlock(&lockdep_lock);
 		return 0;
 	}
+	/* prevent any recursions within lockdep from causing deadlocks */
+	current->lockdep_recursion++;
 	return 1;
 }
 
@@ -89,6 +92,7 @@ static inline int graph_unlock(void)
 	if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
 		return DEBUG_LOCKS_WARN_ON(1);
 
+	current->lockdep_recursion--;
 	__raw_spin_unlock(&lockdep_lock);
 	return 0;
 }
@@ -982,7 +986,7 @@ check_noncircular(struct lock_class *source, unsigned int depth)
 	return 1;
 }
 
-#ifdef CONFIG_TRACE_IRQFLAGS
+#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
 /*
  * Forwards and backwards subgraph searching, for the purposes of
  * proving that two subgraphs can be connected by a new dependency
@@ -1680,7 +1684,7 @@ valid_state(struct task_struct *curr, struct held_lock *this,
 static int mark_lock(struct task_struct *curr, struct held_lock *this,
 		     enum lock_usage_bit new_bit);
 
-#ifdef CONFIG_TRACE_IRQFLAGS
+#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
 
 /*
  * print irq inversion bug:
@@ -2013,11 +2017,13 @@ void early_boot_irqs_on(void)
 /*
  * Hardirqs will be enabled:
  */
-void trace_hardirqs_on(void)
+void trace_hardirqs_on_caller(unsigned long a0)
 {
 	struct task_struct *curr = current;
 	unsigned long ip;
 
+	time_hardirqs_on(CALLER_ADDR0, a0);
+
 	if (unlikely(!debug_locks || current->lockdep_recursion))
 		return;
 
@@ -2055,16 +2061,23 @@ void trace_hardirqs_on(void)
 	curr->hardirq_enable_event = ++curr->irq_events;
 	debug_atomic_inc(&hardirqs_on_events);
 }
+EXPORT_SYMBOL(trace_hardirqs_on_caller);
 
+void trace_hardirqs_on(void)
+{
+	trace_hardirqs_on_caller(CALLER_ADDR0);
+}
 EXPORT_SYMBOL(trace_hardirqs_on);
 
 /*
  * Hardirqs were disabled:
  */
-void trace_hardirqs_off(void)
+void trace_hardirqs_off_caller(unsigned long a0)
 {
 	struct task_struct *curr = current;
 
+	time_hardirqs_off(CALLER_ADDR0, a0);
+
 	if (unlikely(!debug_locks || current->lockdep_recursion))
 		return;
 
@@ -2082,7 +2095,12 @@ void trace_hardirqs_off(void)
 	} else
 		debug_atomic_inc(&redundant_hardirqs_off);
 }
+EXPORT_SYMBOL(trace_hardirqs_off_caller);
 
+void trace_hardirqs_off(void)
+{
+	trace_hardirqs_off_caller(CALLER_ADDR0);
+}
 EXPORT_SYMBOL(trace_hardirqs_off);
 
 /*
@@ -2246,7 +2264,7 @@ static inline int separate_irq_context(struct task_struct *curr,
  * Mark a lock with a usage bit, and validate the state transition:
  */
 static int mark_lock(struct task_struct *curr, struct held_lock *this,
-		     enum lock_usage_bit new_bit)
+			     enum lock_usage_bit new_bit)
 {
 	unsigned int new_mask = 1 << new_bit, ret = 1;
 
@@ -2686,7 +2704,7 @@ static void check_flags(unsigned long flags)
  * and also avoid lockdep recursion:
  */
 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
-		  int trylock, int read, int check, unsigned long ip)
+			  int trylock, int read, int check, unsigned long ip)
 {
 	unsigned long flags;
 
@@ -2708,7 +2726,8 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 
 EXPORT_SYMBOL_GPL(lock_acquire);
 
-void lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
+void lock_release(struct lockdep_map *lock, int nested,
+			  unsigned long ip)
 {
 	unsigned long flags;
 

kernel/marker.c

@@ -55,8 +55,8 @@ static DEFINE_MUTEX(markers_mutex);
 struct marker_entry {
 	struct hlist_node hlist;
 	char *format;
-	void (*call)(const struct marker *mdata,	/* Probe wrapper */
-		void *call_private, const char *fmt, ...);
+			/* Probe wrapper */
+	void (*call)(const struct marker *mdata, void *call_private, ...);
 	struct marker_probe_closure single;
 	struct marker_probe_closure *multi;
 	int refcount;	/* Number of times armed. 0 if disarmed. */
@@ -91,15 +91,13 @@ EXPORT_SYMBOL_GPL(__mark_empty_function);
  * marker_probe_cb Callback that prepares the variable argument list for probes.
  * @mdata: pointer of type struct marker
  * @call_private: caller site private data
- * @fmt: format string
  * @...:  Variable argument list.
  *
  * Since we do not use "typical" pointer based RCU in the 1 argument case, we
  * need to put a full smp_rmb() in this branch. This is why we do not use
  * rcu_dereference() for the pointer read.
  */
-void marker_probe_cb(const struct marker *mdata, void *call_private,
-	const char *fmt, ...)
+void marker_probe_cb(const struct marker *mdata, void *call_private, ...)
 {
 	va_list args;
 	char ptype;
@@ -120,8 +118,9 @@ void marker_probe_cb(const struct marker *mdata, void *call_private,
 		/* Must read the ptr before private data. They are not data
 		 * dependant, so we put an explicit smp_rmb() here. */
 		smp_rmb();
-		va_start(args, fmt);
-		func(mdata->single.probe_private, call_private, fmt, &args);
+		va_start(args, call_private);
+		func(mdata->single.probe_private, call_private, mdata->format,
+			&args);
 		va_end(args);
 	} else {
 		struct marker_probe_closure *multi;
@@ -136,9 +135,9 @@ void marker_probe_cb(const struct marker *mdata, void *call_private,
 		smp_read_barrier_depends();
 		multi = mdata->multi;
 		for (i = 0; multi[i].func; i++) {
-			va_start(args, fmt);
-			multi[i].func(multi[i].probe_private, call_private, fmt,
-				&args);
+			va_start(args, call_private);
+			multi[i].func(multi[i].probe_private, call_private,
+				mdata->format, &args);
 			va_end(args);
 		}
 	}
@@ -150,13 +149,11 @@ EXPORT_SYMBOL_GPL(marker_probe_cb);
  * marker_probe_cb Callback that does not prepare the variable argument list.
  * @mdata: pointer of type struct marker
  * @call_private: caller site private data
- * @fmt: format string
  * @...:  Variable argument list.
  *
  * Should be connected to markers "MARK_NOARGS".
  */
-void marker_probe_cb_noarg(const struct marker *mdata,
-	void *call_private, const char *fmt, ...)
+void marker_probe_cb_noarg(const struct marker *mdata, void *call_private, ...)
 {
 	va_list args;	/* not initialized */
 	char ptype;
@@ -172,7 +169,8 @@ void marker_probe_cb_noarg(const struct marker *mdata,
 		/* Must read the ptr before private data. They are not data
 		 * dependant, so we put an explicit smp_rmb() here. */
 		smp_rmb();
-		func(mdata->single.probe_private, call_private, fmt, &args);
+		func(mdata->single.probe_private, call_private, mdata->format,
+			&args);
 	} else {
 		struct marker_probe_closure *multi;
 		int i;
@@ -186,8 +184,8 @@ void marker_probe_cb_noarg(const struct marker *mdata,
 		smp_read_barrier_depends();
 		multi = mdata->multi;
 		for (i = 0; multi[i].func; i++)
-			multi[i].func(multi[i].probe_private, call_private, fmt,
-				&args);
+			multi[i].func(multi[i].probe_private, call_private,
+				mdata->format, &args);
 	}
 	preempt_enable();
 }

kernel/printk.c

@@ -1041,7 +1041,9 @@ void release_console_sem(void)
 		_log_end = log_end;
 		con_start = log_end;		/* Flush */
 		spin_unlock(&logbuf_lock);
+		stop_critical_timings();	/* don't trace print latency */
 		call_console_drivers(_con_start, _log_end);
+		start_critical_timings();
 		local_irq_restore(flags);
 	}
 	console_locked = 0;

kernel/sched.c

@@ -70,6 +70,7 @@
 #include <linux/bootmem.h>
 #include <linux/debugfs.h>
 #include <linux/ctype.h>
+#include <linux/ftrace.h>
 
 #include <asm/tlb.h>
 #include <asm/irq_regs.h>
@@ -607,6 +608,24 @@ static inline void update_rq_clock(struct rq *rq)
 # define const_debug static const
 #endif
 
+/**
+ * runqueue_is_locked
+ *
+ * Returns true if the current cpu runqueue is locked.
+ * This interface allows printk to be called with the runqueue lock
+ * held and know whether or not it is OK to wake up the klogd.
+ */
+int runqueue_is_locked(void)
+{
+	int cpu = get_cpu();
+	struct rq *rq = cpu_rq(cpu);
+	int ret;
+
+	ret = spin_is_locked(&rq->lock);
+	put_cpu();
+	return ret;
+}
+
 /*
  * Debugging: various feature bits
  */
@@ -831,7 +850,7 @@ static unsigned long long __cpu_clock(int cpu)
  * For kernel-internal use: high-speed (but slightly incorrect) per-cpu
  * clock constructed from sched_clock():
  */
-unsigned long long cpu_clock(int cpu)
+unsigned long long notrace cpu_clock(int cpu)
 {
 	unsigned long long prev_cpu_time, time, delta_time;
 	unsigned long flags;
@@ -2149,6 +2168,9 @@ out_activate:
 	success = 1;
 
 out_running:
+	trace_mark(kernel_sched_wakeup,
+		"pid %d state %ld ## rq %p task %p rq->curr %p",
+		p->pid, p->state, rq, p, rq->curr);
 	check_preempt_curr(rq, p);
 
 	p->state = TASK_RUNNING;
@@ -2279,6 +2301,9 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
 		p->sched_class->task_new(rq, p);
 		inc_nr_running(p, rq);
 	}
+	trace_mark(kernel_sched_wakeup_new,
+		"pid %d state %ld ## rq %p task %p rq->curr %p",
+		p->pid, p->state, rq, p, rq->curr);
 	check_preempt_curr(rq, p);
 #ifdef CONFIG_SMP
 	if (p->sched_class->task_wake_up)
@@ -2451,6 +2476,11 @@ context_switch(struct rq *rq, struct task_struct *prev,
 	struct mm_struct *mm, *oldmm;
 
 	prepare_task_switch(rq, prev, next);
+	trace_mark(kernel_sched_schedule,
+		"prev_pid %d next_pid %d prev_state %ld "
+		"## rq %p prev %p next %p",
+		prev->pid, next->pid, prev->state,
+		rq, prev, next);
 	mm = next->mm;
 	oldmm = prev->active_mm;
 	/*
@@ -4021,26 +4051,44 @@ void scheduler_tick(void)
 #endif
 }
 
-#if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
+#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
+				defined(CONFIG_PREEMPT_TRACER))
+
+static inline unsigned long get_parent_ip(unsigned long addr)
+{
+	if (in_lock_functions(addr)) {
+		addr = CALLER_ADDR2;
+		if (in_lock_functions(addr))
+			addr = CALLER_ADDR3;
+	}
+	return addr;
+}
 
 void __kprobes add_preempt_count(int val)
 {
+#ifdef CONFIG_DEBUG_PREEMPT
 	/*
 	 * Underflow?
 	 */
 	if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
 		return;
+#endif
 	preempt_count() += val;
+#ifdef CONFIG_DEBUG_PREEMPT
 	/*
 	 * Spinlock count overflowing soon?
 	 */
 	DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
 				PREEMPT_MASK - 10);
+#endif
+	if (preempt_count() == val)
+		trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
 }
 EXPORT_SYMBOL(add_preempt_count);
 
 void __kprobes sub_preempt_count(int val)
 {
+#ifdef CONFIG_DEBUG_PREEMPT
 	/*
 	 * Underflow?
 	 */
@@ -4052,7 +4100,10 @@ void __kprobes sub_preempt_count(int val)
 	if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
 			!(preempt_count() & PREEMPT_MASK)))
 		return;
+#endif
 
+	if (preempt_count() == val)
+		trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
 	preempt_count() -= val;
 }
 EXPORT_SYMBOL(sub_preempt_count);
@@ -5384,7 +5435,7 @@ out_unlock:
 	return retval;
 }
 
-static const char stat_nam[] = "RSDTtZX";
+static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
 
 void sched_show_task(struct task_struct *p)
 {

kernel/semaphore.c

@@ -31,6 +31,7 @@
 #include <linux/sched.h>
 #include <linux/semaphore.h>
 #include <linux/spinlock.h>
+#include <linux/ftrace.h>
 
 static noinline void __down(struct semaphore *sem);
 static noinline int __down_interruptible(struct semaphore *sem);

kernel/spinlock.c

@@ -436,7 +436,7 @@ int __lockfunc _spin_trylock_bh(spinlock_t *lock)
 }
 EXPORT_SYMBOL(_spin_trylock_bh);
 
-int in_lock_functions(unsigned long addr)
+notrace int in_lock_functions(unsigned long addr)
 {
 	/* Linker adds these: start and end of __lockfunc functions */
 	extern char __lock_text_start[], __lock_text_end[];

kernel/sysctl.c

@@ -46,6 +46,7 @@
 #include <linux/nfs_fs.h>
 #include <linux/acpi.h>
 #include <linux/reboot.h>
+#include <linux/ftrace.h>
 
 #include <asm/uaccess.h>
 #include <asm/processor.h>
@@ -455,6 +456,16 @@ static struct ctl_table kern_table[] = {
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec,
 	},
+#ifdef CONFIG_FTRACE
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "ftrace_enabled",
+		.data		= &ftrace_enabled,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= &ftrace_enable_sysctl,
+	},
+#endif
 #ifdef CONFIG_KMOD
 	{
 		.ctl_name	= KERN_MODPROBE,

kernel/trace/Kconfig

@@ -0,0 +1,127 @@
+#
+# Architectures that offer an FTRACE implementation should select HAVE_FTRACE:
+#
+config HAVE_FTRACE
+	bool
+
+config HAVE_DYNAMIC_FTRACE
+	bool
+
+config TRACER_MAX_TRACE
+	bool
+
+config TRACING
+	bool
+	select DEBUG_FS
+	select STACKTRACE
+
+config FTRACE
+	bool "Kernel Function Tracer"
+	depends on HAVE_FTRACE
+	select FRAME_POINTER
+	select TRACING
+	select CONTEXT_SWITCH_TRACER
+	help
+	  Enable the kernel to trace every kernel function. This is done
+	  by using a compiler feature to insert a small, 5-byte No-Operation
+	  instruction to the beginning of every kernel function, which NOP
+	  sequence is then dynamically patched into a tracer call when
+	  tracing is enabled by the administrator. If it's runtime disabled
+	  (the bootup default), then the overhead of the instructions is very
+	  small and not measurable even in micro-benchmarks.
+
+config IRQSOFF_TRACER
+	bool "Interrupts-off Latency Tracer"
+	default n
+	depends on TRACE_IRQFLAGS_SUPPORT
+	depends on GENERIC_TIME
+	depends on HAVE_FTRACE
+	select TRACE_IRQFLAGS
+	select TRACING
+	select TRACER_MAX_TRACE
+	help
+	  This option measures the time spent in irqs-off critical
+	  sections, with microsecond accuracy.
+
+	  The default measurement method is a maximum search, which is
+	  disabled by default and can be runtime (re-)started
+	  via:
+
+	      echo 0 > /debugfs/tracing/tracing_max_latency
+
+	  (Note that kernel size and overhead increases with this option
+	  enabled. This option and the preempt-off timing option can be
+	  used together or separately.)
+
+config PREEMPT_TRACER
+	bool "Preemption-off Latency Tracer"
+	default n
+	depends on GENERIC_TIME
+	depends on PREEMPT
+	depends on HAVE_FTRACE
+	select TRACING
+	select TRACER_MAX_TRACE
+	help
+	  This option measures the time spent in preemption off critical
+	  sections, with microsecond accuracy.
+
+	  The default measurement method is a maximum search, which is
+	  disabled by default and can be runtime (re-)started
+	  via:
+
+	      echo 0 > /debugfs/tracing/tracing_max_latency
+
+	  (Note that kernel size and overhead increases with this option
+	  enabled. This option and the irqs-off timing option can be
+	  used together or separately.)
+
+config SCHED_TRACER
+	bool "Scheduling Latency Tracer"
+	depends on HAVE_FTRACE
+	select TRACING
+	select CONTEXT_SWITCH_TRACER
+	select TRACER_MAX_TRACE
+	help
+	  This tracer tracks the latency of the highest priority task
+	  to be scheduled in, starting from the point it has woken up.
+
+config CONTEXT_SWITCH_TRACER
+	bool "Trace process context switches"
+	depends on HAVE_FTRACE
+	select TRACING
+	select MARKERS
+	help
+	  This tracer gets called from the context switch and records
+	  all switching of tasks.
+
+config DYNAMIC_FTRACE
+	bool "enable/disable ftrace tracepoints dynamically"
+	depends on FTRACE
+	depends on HAVE_DYNAMIC_FTRACE
+	default y
+	help
+         This option will modify all the calls to ftrace dynamically
+	 (will patch them out of the binary image and replaces them
+	 with a No-Op instruction) as they are called. A table is
+	 created to dynamically enable them again.
+
+	 This way a CONFIG_FTRACE kernel is slightly larger, but otherwise
+	 has native performance as long as no tracing is active.
+
+	 The changes to the code are done by a kernel thread that
+	 wakes up once a second and checks to see if any ftrace calls
+	 were made. If so, it runs stop_machine (stops all CPUS)
+	 and modifies the code to jump over the call to ftrace.
+
+config FTRACE_SELFTEST
+	bool
+
+config FTRACE_STARTUP_TEST
+	bool "Perform a startup test on ftrace"
+	depends on TRACING
+	select FTRACE_SELFTEST
+	help
+	  This option performs a series of startup tests on ftrace. On bootup
+	  a series of tests are made to verify that the tracer is
+	  functioning properly. It will do tests on all the configured
+	  tracers of ftrace.

kernel/trace/Makefile

@@ -0,0 +1,22 @@
+
+# Do not instrument the tracer itself:
+
+ifdef CONFIG_FTRACE
+ORIG_CFLAGS := $(KBUILD_CFLAGS)
+KBUILD_CFLAGS = $(subst -pg,,$(ORIG_CFLAGS))
+
+# selftest needs instrumentation
+CFLAGS_trace_selftest_dynamic.o = -pg
+obj-y += trace_selftest_dynamic.o
+endif
+
+obj-$(CONFIG_FTRACE) += libftrace.o
+
+obj-$(CONFIG_TRACING) += trace.o
+obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
+obj-$(CONFIG_FTRACE) += trace_functions.o
+obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
+obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o
+obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
+
+libftrace-y := ftrace.o

kernel/trace/ftrace.c

@@ -0,0 +1,1710 @@
+/*
+ * Infrastructure for profiling code inserted by 'gcc -pg'.
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ * Copyright (C) 2004-2008 Ingo Molnar <mingo@redhat.com>
+ *
+ * Originally ported from the -rt patch by:
+ *   Copyright (C) 2007 Arnaldo Carvalho de Melo <acme@redhat.com>
+ *
+ * Based on code in the latency_tracer, that is:
+ *
+ *  Copyright (C) 2004-2006 Ingo Molnar
+ *  Copyright (C) 2004 William Lee Irwin III
+ */
+
+#include <linux/stop_machine.h>
+#include <linux/clocksource.h>
+#include <linux/kallsyms.h>
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
+#include <linux/hardirq.h>
+#include <linux/kthread.h>
+#include <linux/uaccess.h>
+#include <linux/kprobes.h>
+#include <linux/ftrace.h>
+#include <linux/sysctl.h>
+#include <linux/ctype.h>
+#include <linux/hash.h>
+#include <linux/list.h>
+
+#include <asm/ftrace.h>
+
+#include "trace.h"
+
+/* ftrace_enabled is a method to turn ftrace on or off */
+int ftrace_enabled __read_mostly;
+static int last_ftrace_enabled;
+
+/*
+ * ftrace_disabled is set when an anomaly is discovered.
+ * ftrace_disabled is much stronger than ftrace_enabled.
+ */
+static int ftrace_disabled __read_mostly;
+
+static DEFINE_SPINLOCK(ftrace_lock);
+static DEFINE_MUTEX(ftrace_sysctl_lock);
+
+static struct ftrace_ops ftrace_list_end __read_mostly =
+{
+	.func = ftrace_stub,
+};
+
+static struct ftrace_ops *ftrace_list __read_mostly = &ftrace_list_end;
+ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
+
+static void ftrace_list_func(unsigned long ip, unsigned long parent_ip)
+{
+	struct ftrace_ops *op = ftrace_list;
+
+	/* in case someone actually ports this to alpha! */
+	read_barrier_depends();
+
+	while (op != &ftrace_list_end) {
+		/* silly alpha */
+		read_barrier_depends();
+		op->func(ip, parent_ip);
+		op = op->next;
+	};
+}
+
+/**
+ * clear_ftrace_function - reset the ftrace function
+ *
+ * This NULLs the ftrace function and in essence stops
+ * tracing.  There may be lag
+ */
+void clear_ftrace_function(void)
+{
+	ftrace_trace_function = ftrace_stub;
+}
+
+static int __register_ftrace_function(struct ftrace_ops *ops)
+{
+	/* Should never be called by interrupts */
+	spin_lock(&ftrace_lock);
+
+	ops->next = ftrace_list;
+	/*
+	 * We are entering ops into the ftrace_list but another
+	 * CPU might be walking that list. We need to make sure
+	 * the ops->next pointer is valid before another CPU sees
+	 * the ops pointer included into the ftrace_list.
+	 */
+	smp_wmb();
+	ftrace_list = ops;
+
+	if (ftrace_enabled) {
+		/*
+		 * For one func, simply call it directly.
+		 * For more than one func, call the chain.
+		 */
+		if (ops->next == &ftrace_list_end)
+			ftrace_trace_function = ops->func;
+		else
+			ftrace_trace_function = ftrace_list_func;
+	}
+
+	spin_unlock(&ftrace_lock);
+
+	return 0;
+}
+
+static int __unregister_ftrace_function(struct ftrace_ops *ops)
+{
+	struct ftrace_ops **p;
+	int ret = 0;
+
+	spin_lock(&ftrace_lock);
+
+	/*
+	 * If we are removing the last function, then simply point
+	 * to the ftrace_stub.
+	 */
+	if (ftrace_list == ops && ops->next == &ftrace_list_end) {
+		ftrace_trace_function = ftrace_stub;
+		ftrace_list = &ftrace_list_end;
+		goto out;
+	}
+
+	for (p = &ftrace_list; *p != &ftrace_list_end; p = &(*p)->next)
+		if (*p == ops)
+			break;
+
+	if (*p != ops) {
+		ret = -1;
+		goto out;
+	}
+
+	*p = (*p)->next;
+
+	if (ftrace_enabled) {
+		/* If we only have one func left, then call that directly */
+		if (ftrace_list == &ftrace_list_end ||
+		    ftrace_list->next == &ftrace_list_end)
+			ftrace_trace_function = ftrace_list->func;
+	}
+
+ out:
+	spin_unlock(&ftrace_lock);
+
+	return ret;
+}
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+static struct task_struct *ftraced_task;
+
+enum {
+	FTRACE_ENABLE_CALLS		= (1 << 0),
+	FTRACE_DISABLE_CALLS		= (1 << 1),
+	FTRACE_UPDATE_TRACE_FUNC	= (1 << 2),
+	FTRACE_ENABLE_MCOUNT		= (1 << 3),
+	FTRACE_DISABLE_MCOUNT		= (1 << 4),
+};
+
+static int ftrace_filtered;
+static int tracing_on;
+static int frozen_record_count;
+
+static struct hlist_head ftrace_hash[FTRACE_HASHSIZE];
+
+static DEFINE_PER_CPU(int, ftrace_shutdown_disable_cpu);
+
+static DEFINE_SPINLOCK(ftrace_shutdown_lock);
+static DEFINE_MUTEX(ftraced_lock);
+static DEFINE_MUTEX(ftrace_regex_lock);
+
+struct ftrace_page {
+	struct ftrace_page	*next;
+	unsigned long		index;
+	struct dyn_ftrace	records[];
+};
+
+#define ENTRIES_PER_PAGE \
+  ((PAGE_SIZE - sizeof(struct ftrace_page)) / sizeof(struct dyn_ftrace))
+
+/* estimate from running different kernels */
+#define NR_TO_INIT		10000
+
+static struct ftrace_page	*ftrace_pages_start;
+static struct ftrace_page	*ftrace_pages;
+
+static int ftraced_trigger;
+static int ftraced_suspend;
+static int ftraced_stop;
+
+static int ftrace_record_suspend;
+
+static struct dyn_ftrace *ftrace_free_records;
+
+
+#ifdef CONFIG_KPROBES
+static inline void freeze_record(struct dyn_ftrace *rec)
+{
+	if (!(rec->flags & FTRACE_FL_FROZEN)) {
+		rec->flags |= FTRACE_FL_FROZEN;
+		frozen_record_count++;
+	}
+}
+
+static inline void unfreeze_record(struct dyn_ftrace *rec)
+{
+	if (rec->flags & FTRACE_FL_FROZEN) {
+		rec->flags &= ~FTRACE_FL_FROZEN;
+		frozen_record_count--;
+	}
+}
+
+static inline int record_frozen(struct dyn_ftrace *rec)
+{
+	return rec->flags & FTRACE_FL_FROZEN;
+}
+#else
+# define freeze_record(rec)			({ 0; })
+# define unfreeze_record(rec)			({ 0; })
+# define record_frozen(rec)			({ 0; })
+#endif /* CONFIG_KPROBES */
+
+int skip_trace(unsigned long ip)
+{
+	unsigned long fl;
+	struct dyn_ftrace *rec;
+	struct hlist_node *t;
+	struct hlist_head *head;
+
+	if (frozen_record_count == 0)
+		return 0;
+
+	head = &ftrace_hash[hash_long(ip, FTRACE_HASHBITS)];
+	hlist_for_each_entry_rcu(rec, t, head, node) {
+		if (rec->ip == ip) {
+			if (record_frozen(rec)) {
+				if (rec->flags & FTRACE_FL_FAILED)
+					return 1;
+
+				if (!(rec->flags & FTRACE_FL_CONVERTED))
+					return 1;
+
+				if (!tracing_on || !ftrace_enabled)
+					return 1;
+
+				if (ftrace_filtered) {
+					fl = rec->flags & (FTRACE_FL_FILTER |
+							   FTRACE_FL_NOTRACE);
+					if (!fl || (fl & FTRACE_FL_NOTRACE))
+						return 1;
+				}
+			}
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static inline int
+ftrace_ip_in_hash(unsigned long ip, unsigned long key)
+{
+	struct dyn_ftrace *p;
+	struct hlist_node *t;
+	int found = 0;
+
+	hlist_for_each_entry_rcu(p, t, &ftrace_hash[key], node) {
+		if (p->ip == ip) {
+			found = 1;
+			break;
+		}
+	}
+
+	return found;
+}
+
+static inline void
+ftrace_add_hash(struct dyn_ftrace *node, unsigned long key)
+{
+	hlist_add_head_rcu(&node->node, &ftrace_hash[key]);
+}
+
+/* called from kstop_machine */
+static inline void ftrace_del_hash(struct dyn_ftrace *node)
+{
+	hlist_del(&node->node);
+}
+
+static void ftrace_free_rec(struct dyn_ftrace *rec)
+{
+	/* no locking, only called from kstop_machine */
+
+	rec->ip = (unsigned long)ftrace_free_records;
+	ftrace_free_records = rec;
+	rec->flags |= FTRACE_FL_FREE;
+}
+
+static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
+{
+	struct dyn_ftrace *rec;
+
+	/* First check for freed records */
+	if (ftrace_free_records) {
+		rec = ftrace_free_records;
+
+		if (unlikely(!(rec->flags & FTRACE_FL_FREE))) {
+			WARN_ON_ONCE(1);
+			ftrace_free_records = NULL;
+			ftrace_disabled = 1;
+			ftrace_enabled = 0;
+			return NULL;
+		}
+
+		ftrace_free_records = (void *)rec->ip;
+		memset(rec, 0, sizeof(*rec));
+		return rec;
+	}
+
+	if (ftrace_pages->index == ENTRIES_PER_PAGE) {
+		if (!ftrace_pages->next)
+			return NULL;
+		ftrace_pages = ftrace_pages->next;
+	}
+
+	return &ftrace_pages->records[ftrace_pages->index++];
+}
+
+static void
+ftrace_record_ip(unsigned long ip)
+{
+	struct dyn_ftrace *node;
+	unsigned long flags;
+	unsigned long key;
+	int resched;
+	int atomic;
+	int cpu;
+
+	if (!ftrace_enabled || ftrace_disabled)
+		return;
+
+	resched = need_resched();
+	preempt_disable_notrace();
+
+	/*
+	 * We simply need to protect against recursion.
+	 * Use the the raw version of smp_processor_id and not
+	 * __get_cpu_var which can call debug hooks that can
+	 * cause a recursive crash here.
+	 */
+	cpu = raw_smp_processor_id();
+	per_cpu(ftrace_shutdown_disable_cpu, cpu)++;
+	if (per_cpu(ftrace_shutdown_disable_cpu, cpu) != 1)
+		goto out;
+
+	if (unlikely(ftrace_record_suspend))
+		goto out;
+
+	key = hash_long(ip, FTRACE_HASHBITS);
+
+	WARN_ON_ONCE(key >= FTRACE_HASHSIZE);
+
+	if (ftrace_ip_in_hash(ip, key))
+		goto out;
+
+	atomic = irqs_disabled();
+
+	spin_lock_irqsave(&ftrace_shutdown_lock, flags);
+
+	/* This ip may have hit the hash before the lock */
+	if (ftrace_ip_in_hash(ip, key))
+		goto out_unlock;
+
+	node = ftrace_alloc_dyn_node(ip);
+	if (!node)
+		goto out_unlock;
+
+	node->ip = ip;
+
+	ftrace_add_hash(node, key);
+
+	ftraced_trigger = 1;
+
+ out_unlock:
+	spin_unlock_irqrestore(&ftrace_shutdown_lock, flags);
+ out:
+	per_cpu(ftrace_shutdown_disable_cpu, cpu)--;
+
+	/* prevent recursion with scheduler */
+	if (resched)
+		preempt_enable_no_resched_notrace();
+	else
+		preempt_enable_notrace();
+}
+
+#define FTRACE_ADDR ((long)(ftrace_caller))
+
+static int
+__ftrace_replace_code(struct dyn_ftrace *rec,
+		      unsigned char *old, unsigned char *new, int enable)
+{
+	unsigned long ip, fl;
+
+	ip = rec->ip;
+
+	if (ftrace_filtered && enable) {
+		/*
+		 * If filtering is on:
+		 *
+		 * If this record is set to be filtered and
+		 * is enabled then do nothing.
+		 *
+		 * If this record is set to be filtered and
+		 * it is not enabled, enable it.
+		 *
+		 * If this record is not set to be filtered
+		 * and it is not enabled do nothing.
+		 *
+		 * If this record is set not to trace then
+		 * do nothing.
+		 *
+		 * If this record is set not to trace and
+		 * it is enabled then disable it.
+		 *
+		 * If this record is not set to be filtered and
+		 * it is enabled, disable it.
+		 */
+
+		fl = rec->flags & (FTRACE_FL_FILTER | FTRACE_FL_NOTRACE |
+				   FTRACE_FL_ENABLED);
+
+		if ((fl ==  (FTRACE_FL_FILTER | FTRACE_FL_ENABLED)) ||
+		    (fl ==  (FTRACE_FL_FILTER | FTRACE_FL_NOTRACE)) ||
+		    !fl || (fl == FTRACE_FL_NOTRACE))
+			return 0;
+
+		/*
+		 * If it is enabled disable it,
+		 * otherwise enable it!
+		 */
+		if (fl & FTRACE_FL_ENABLED) {
+			/* swap new and old */
+			new = old;
+			old = ftrace_call_replace(ip, FTRACE_ADDR);
+			rec->flags &= ~FTRACE_FL_ENABLED;
+		} else {
+			new = ftrace_call_replace(ip, FTRACE_ADDR);
+			rec->flags |= FTRACE_FL_ENABLED;
+		}
+	} else {
+
+		if (enable) {
+			/*
+			 * If this record is set not to trace and is
+			 * not enabled, do nothing.
+			 */
+			fl = rec->flags & (FTRACE_FL_NOTRACE | FTRACE_FL_ENABLED);
+			if (fl == FTRACE_FL_NOTRACE)
+				return 0;
+
+			new = ftrace_call_replace(ip, FTRACE_ADDR);
+		} else
+			old = ftrace_call_replace(ip, FTRACE_ADDR);
+
+		if (enable) {
+			if (rec->flags & FTRACE_FL_ENABLED)
+				return 0;
+			rec->flags |= FTRACE_FL_ENABLED;
+		} else {
+			if (!(rec->flags & FTRACE_FL_ENABLED))
+				return 0;
+			rec->flags &= ~FTRACE_FL_ENABLED;
+		}
+	}
+
+	return ftrace_modify_code(ip, old, new);
+}
+
+static void ftrace_replace_code(int enable)
+{
+	int i, failed;
+	unsigned char *new = NULL, *old = NULL;
+	struct dyn_ftrace *rec;
+	struct ftrace_page *pg;
+
+	if (enable)
+		old = ftrace_nop_replace();
+	else
+		new = ftrace_nop_replace();
+
+	for (pg = ftrace_pages_start; pg; pg = pg->next) {
+		for (i = 0; i < pg->index; i++) {
+			rec = &pg->records[i];
+
+			/* don't modify code that has already faulted */
+			if (rec->flags & FTRACE_FL_FAILED)
+				continue;
+
+			/* ignore updates to this record's mcount site */
+			if (get_kprobe((void *)rec->ip)) {
+				freeze_record(rec);
+				continue;
+			} else {
+				unfreeze_record(rec);
+			}
+
+			failed = __ftrace_replace_code(rec, old, new, enable);
+			if (failed && (rec->flags & FTRACE_FL_CONVERTED)) {
+				rec->flags |= FTRACE_FL_FAILED;
+				if ((system_state == SYSTEM_BOOTING) ||
+				    !core_kernel_text(rec->ip)) {
+					ftrace_del_hash(rec);
+					ftrace_free_rec(rec);
+				}
+			}
+		}
+	}
+}
+
+static void ftrace_shutdown_replenish(void)
+{
+	if (ftrace_pages->next)
+		return;
+
+	/* allocate another page */
+	ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL);
+}
+
+static int
+ftrace_code_disable(struct dyn_ftrace *rec)
+{
+	unsigned long ip;
+	unsigned char *nop, *call;
+	int failed;
+
+	ip = rec->ip;
+
+	nop = ftrace_nop_replace();
+	call = ftrace_call_replace(ip, MCOUNT_ADDR);
+
+	failed = ftrace_modify_code(ip, call, nop);
+	if (failed) {
+		rec->flags |= FTRACE_FL_FAILED;
+		return 0;
+	}
+	return 1;
+}
+
+static int __ftrace_update_code(void *ignore);
+
+static int __ftrace_modify_code(void *data)
+{
+	unsigned long addr;
+	int *command = data;
+
+	if (*command & FTRACE_ENABLE_CALLS) {
+		/*
+		 * Update any recorded ips now that we have the
+		 * machine stopped
+		 */
+		__ftrace_update_code(NULL);
+		ftrace_replace_code(1);
+		tracing_on = 1;
+	} else if (*command & FTRACE_DISABLE_CALLS) {
+		ftrace_replace_code(0);
+		tracing_on = 0;
+	}
+
+	if (*command & FTRACE_UPDATE_TRACE_FUNC)
+		ftrace_update_ftrace_func(ftrace_trace_function);
+
+	if (*command & FTRACE_ENABLE_MCOUNT) {
+		addr = (unsigned long)ftrace_record_ip;
+		ftrace_mcount_set(&addr);
+	} else if (*command & FTRACE_DISABLE_MCOUNT) {
+		addr = (unsigned long)ftrace_stub;
+		ftrace_mcount_set(&addr);
+	}
+
+	return 0;
+}
+
+static void ftrace_run_update_code(int command)
+{
+	stop_machine_run(__ftrace_modify_code, &command, NR_CPUS);
+}
+
+void ftrace_disable_daemon(void)
+{
+	/* Stop the daemon from calling kstop_machine */
+	mutex_lock(&ftraced_lock);
+	ftraced_stop = 1;
+	mutex_unlock(&ftraced_lock);
+
+	ftrace_force_update();
+}
+
+void ftrace_enable_daemon(void)
+{
+	mutex_lock(&ftraced_lock);
+	ftraced_stop = 0;
+	mutex_unlock(&ftraced_lock);
+
+	ftrace_force_update();
+}
+
+static ftrace_func_t saved_ftrace_func;
+
+static void ftrace_startup(void)
+{
+	int command = 0;
+
+	if (unlikely(ftrace_disabled))
+		return;
+
+	mutex_lock(&ftraced_lock);
+	ftraced_suspend++;
+	if (ftraced_suspend == 1)
+		command |= FTRACE_ENABLE_CALLS;
+
+	if (saved_ftrace_func != ftrace_trace_function) {
+		saved_ftrace_func = ftrace_trace_function;
+		command |= FTRACE_UPDATE_TRACE_FUNC;
+	}
+
+	if (!command || !ftrace_enabled)
+		goto out;
+
+	ftrace_run_update_code(command);
+ out:
+	mutex_unlock(&ftraced_lock);
+}
+
+static void ftrace_shutdown(void)
+{
+	int command = 0;
+
+	if (unlikely(ftrace_disabled))
+		return;
+
+	mutex_lock(&ftraced_lock);
+	ftraced_suspend--;
+	if (!ftraced_suspend)
+		command |= FTRACE_DISABLE_CALLS;
+
+	if (saved_ftrace_func != ftrace_trace_function) {
+		saved_ftrace_func = ftrace_trace_function;
+		command |= FTRACE_UPDATE_TRACE_FUNC;
+	}
+
+	if (!command || !ftrace_enabled)
+		goto out;
+
+	ftrace_run_update_code(command);
+ out:
+	mutex_unlock(&ftraced_lock);
+}
+
+static void ftrace_startup_sysctl(void)
+{
+	int command = FTRACE_ENABLE_MCOUNT;
+
+	if (unlikely(ftrace_disabled))
+		return;
+
+	mutex_lock(&ftraced_lock);
+	/* Force update next time */
+	saved_ftrace_func = NULL;
+	/* ftraced_suspend is true if we want ftrace running */
+	if (ftraced_suspend)
+		command |= FTRACE_ENABLE_CALLS;
+
+	ftrace_run_update_code(command);
+	mutex_unlock(&ftraced_lock);
+}
+
+static void ftrace_shutdown_sysctl(void)
+{
+	int command = FTRACE_DISABLE_MCOUNT;
+
+	if (unlikely(ftrace_disabled))
+		return;
+
+	mutex_lock(&ftraced_lock);
+	/* ftraced_suspend is true if ftrace is running */
+	if (ftraced_suspend)
+		command |= FTRACE_DISABLE_CALLS;
+
+	ftrace_run_update_code(command);
+	mutex_unlock(&ftraced_lock);
+}
+
+static cycle_t		ftrace_update_time;
+static unsigned long	ftrace_update_cnt;
+unsigned long		ftrace_update_tot_cnt;
+
+static int __ftrace_update_code(void *ignore)
+{
+	int i, save_ftrace_enabled;
+	cycle_t start, stop;
+	struct dyn_ftrace *p;
+	struct hlist_node *t, *n;
+	struct hlist_head *head, temp_list;
+
+	/* Don't be recording funcs now */
+	ftrace_record_suspend++;
+	save_ftrace_enabled = ftrace_enabled;
+	ftrace_enabled = 0;
+
+	start = ftrace_now(raw_smp_processor_id());
+	ftrace_update_cnt = 0;
+
+	/* No locks needed, the machine is stopped! */
+	for (i = 0; i < FTRACE_HASHSIZE; i++) {
+		INIT_HLIST_HEAD(&temp_list);
+		head = &ftrace_hash[i];
+
+		/* all CPUS are stopped, we are safe to modify code */
+		hlist_for_each_entry_safe(p, t, n, head, node) {
+			/* Skip over failed records which have not been
+			 * freed. */
+			if (p->flags & FTRACE_FL_FAILED)
+				continue;
+
+			/* Unconverted records are always at the head of the
+			 * hash bucket. Once we encounter a converted record,
+			 * simply skip over to the next bucket. Saves ftraced
+			 * some processor cycles (ftrace does its bid for
+			 * global warming :-p ). */
+			if (p->flags & (FTRACE_FL_CONVERTED))
+				break;
+
+			/* Ignore updates to this record's mcount site.
+			 * Reintroduce this record at the head of this
+			 * bucket to attempt to "convert" it again if
+			 * the kprobe on it is unregistered before the
+			 * next run. */
+			if (get_kprobe((void *)p->ip)) {
+				ftrace_del_hash(p);
+				INIT_HLIST_NODE(&p->node);
+				hlist_add_head(&p->node, &temp_list);
+				freeze_record(p);
+				continue;
+			} else {
+				unfreeze_record(p);
+			}
+
+			/* convert record (i.e, patch mcount-call with NOP) */
+			if (ftrace_code_disable(p)) {
+				p->flags |= FTRACE_FL_CONVERTED;
+				ftrace_update_cnt++;
+			} else {
+				if ((system_state == SYSTEM_BOOTING) ||
+				    !core_kernel_text(p->ip)) {
+					ftrace_del_hash(p);
+					ftrace_free_rec(p);
+				}
+			}
+		}
+
+		hlist_for_each_entry_safe(p, t, n, &temp_list, node) {
+			hlist_del(&p->node);
+			INIT_HLIST_NODE(&p->node);
+			hlist_add_head(&p->node, head);
+		}
+	}
+
+	stop = ftrace_now(raw_smp_processor_id());
+	ftrace_update_time = stop - start;
+	ftrace_update_tot_cnt += ftrace_update_cnt;
+	ftraced_trigger = 0;
+
+	ftrace_enabled = save_ftrace_enabled;
+	ftrace_record_suspend--;
+
+	return 0;
+}
+
+static int ftrace_update_code(void)
+{
+	if (unlikely(ftrace_disabled) ||
+	    !ftrace_enabled || !ftraced_trigger)
+		return 0;
+
+	stop_machine_run(__ftrace_update_code, NULL, NR_CPUS);
+
+	return 1;
+}
+
+static int ftraced(void *ignore)
+{
+	unsigned long usecs;
+
+	while (!kthread_should_stop()) {
+
+		set_current_state(TASK_INTERRUPTIBLE);
+
+		/* check once a second */
+		schedule_timeout(HZ);
+
+		if (unlikely(ftrace_disabled))
+			continue;
+
+		mutex_lock(&ftrace_sysctl_lock);
+		mutex_lock(&ftraced_lock);
+		if (!ftraced_suspend && !ftraced_stop &&
+		    ftrace_update_code()) {
+			usecs = nsecs_to_usecs(ftrace_update_time);
+			if (ftrace_update_tot_cnt > 100000) {
+				ftrace_update_tot_cnt = 0;
+				pr_info("hm, dftrace overflow: %lu change%s"
+					" (%lu total) in %lu usec%s\n",
+					ftrace_update_cnt,
+					ftrace_update_cnt != 1 ? "s" : "",
+					ftrace_update_tot_cnt,
+					usecs, usecs != 1 ? "s" : "");
+				ftrace_disabled = 1;
+				WARN_ON_ONCE(1);
+			}
+		}
+		mutex_unlock(&ftraced_lock);
+		mutex_unlock(&ftrace_sysctl_lock);
+
+		ftrace_shutdown_replenish();
+	}
+	__set_current_state(TASK_RUNNING);
+	return 0;
+}
+
+static int __init ftrace_dyn_table_alloc(void)
+{
+	struct ftrace_page *pg;
+	int cnt;
+	int i;
+
+	/* allocate a few pages */
+	ftrace_pages_start = (void *)get_zeroed_page(GFP_KERNEL);
+	if (!ftrace_pages_start)
+		return -1;
+
+	/*
+	 * Allocate a few more pages.
+	 *
+	 * TODO: have some parser search vmlinux before
+	 *   final linking to find all calls to ftrace.
+	 *   Then we can:
+	 *    a) know how many pages to allocate.
+	 *     and/or
+	 *    b) set up the table then.
+	 *
+	 *  The dynamic code is still necessary for
+	 *  modules.
+	 */
+
+	pg = ftrace_pages = ftrace_pages_start;
+
+	cnt = NR_TO_INIT / ENTRIES_PER_PAGE;
+
+	for (i = 0; i < cnt; i++) {
+		pg->next = (void *)get_zeroed_page(GFP_KERNEL);
+
+		/* If we fail, we'll try later anyway */
+		if (!pg->next)
+			break;
+
+		pg = pg->next;
+	}
+
+	return 0;
+}
+
+enum {
+	FTRACE_ITER_FILTER	= (1 << 0),
+	FTRACE_ITER_CONT	= (1 << 1),
+	FTRACE_ITER_NOTRACE	= (1 << 2),
+	FTRACE_ITER_FAILURES	= (1 << 3),
+};
+
+#define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
+
+struct ftrace_iterator {
+	loff_t			pos;
+	struct ftrace_page	*pg;
+	unsigned		idx;
+	unsigned		flags;
+	unsigned char		buffer[FTRACE_BUFF_MAX+1];
+	unsigned		buffer_idx;
+	unsigned		filtered;
+};
+
+static void *
+t_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct ftrace_iterator *iter = m->private;
+	struct dyn_ftrace *rec = NULL;
+
+	(*pos)++;
+
+ retry:
+	if (iter->idx >= iter->pg->index) {
+		if (iter->pg->next) {
+			iter->pg = iter->pg->next;
+			iter->idx = 0;
+			goto retry;
+		}
+	} else {
+		rec = &iter->pg->records[iter->idx++];
+		if ((!(iter->flags & FTRACE_ITER_FAILURES) &&
+		     (rec->flags & FTRACE_FL_FAILED)) ||
+
+		    ((iter->flags & FTRACE_ITER_FAILURES) &&
+		     (!(rec->flags & FTRACE_FL_FAILED) ||
+		      (rec->flags & FTRACE_FL_FREE))) ||
+
+		    ((iter->flags & FTRACE_ITER_FILTER) &&
+		     !(rec->flags & FTRACE_FL_FILTER)) ||
+
+		    ((iter->flags & FTRACE_ITER_NOTRACE) &&
+		     !(rec->flags & FTRACE_FL_NOTRACE))) {
+			rec = NULL;
+			goto retry;
+		}
+	}
+
+	iter->pos = *pos;
+
+	return rec;
+}
+
+static void *t_start(struct seq_file *m, loff_t *pos)
+{
+	struct ftrace_iterator *iter = m->private;
+	void *p = NULL;
+	loff_t l = -1;
+
+	if (*pos != iter->pos) {
+		for (p = t_next(m, p, &l); p && l < *pos; p = t_next(m, p, &l))
+			;
+	} else {
+		l = *pos;
+		p = t_next(m, p, &l);
+	}
+
+	return p;
+}
+
+static void t_stop(struct seq_file *m, void *p)
+{
+}
+
+static int t_show(struct seq_file *m, void *v)
+{
+	struct dyn_ftrace *rec = v;
+	char str[KSYM_SYMBOL_LEN];
+
+	if (!rec)
+		return 0;
+
+	kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
+
+	seq_printf(m, "%s\n", str);
+
+	return 0;
+}
+
+static struct seq_operations show_ftrace_seq_ops = {
+	.start = t_start,
+	.next = t_next,
+	.stop = t_stop,
+	.show = t_show,
+};
+
+static int
+ftrace_avail_open(struct inode *inode, struct file *file)
+{
+	struct ftrace_iterator *iter;
+	int ret;
+
+	if (unlikely(ftrace_disabled))
+		return -ENODEV;
+
+	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
+	if (!iter)
+		return -ENOMEM;
+
+	iter->pg = ftrace_pages_start;
+	iter->pos = -1;
+
+	ret = seq_open(file, &show_ftrace_seq_ops);
+	if (!ret) {
+		struct seq_file *m = file->private_data;
+
+		m->private = iter;
+	} else {
+		kfree(iter);
+	}
+
+	return ret;
+}
+
+int ftrace_avail_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *m = (struct seq_file *)file->private_data;
+	struct ftrace_iterator *iter = m->private;
+
+	seq_release(inode, file);
+	kfree(iter);
+
+	return 0;
+}
+
+static int
+ftrace_failures_open(struct inode *inode, struct file *file)
+{
+	int ret;
+	struct seq_file *m;
+	struct ftrace_iterator *iter;
+
+	ret = ftrace_avail_open(inode, file);
+	if (!ret) {
+		m = (struct seq_file *)file->private_data;
+		iter = (struct ftrace_iterator *)m->private;
+		iter->flags = FTRACE_ITER_FAILURES;
+	}
+
+	return ret;
+}
+
+
+static void ftrace_filter_reset(int enable)
+{
+	struct ftrace_page *pg;
+	struct dyn_ftrace *rec;
+	unsigned long type = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
+	unsigned i;
+
+	/* keep kstop machine from running */
+	preempt_disable();
+	if (enable)
+		ftrace_filtered = 0;
+	pg = ftrace_pages_start;
+	while (pg) {
+		for (i = 0; i < pg->index; i++) {
+			rec = &pg->records[i];
+			if (rec->flags & FTRACE_FL_FAILED)
+				continue;
+			rec->flags &= ~type;
+		}
+		pg = pg->next;
+	}
+	preempt_enable();
+}
+
+static int
+ftrace_regex_open(struct inode *inode, struct file *file, int enable)
+{
+	struct ftrace_iterator *iter;
+	int ret = 0;
+
+	if (unlikely(ftrace_disabled))
+		return -ENODEV;
+
+	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
+	if (!iter)
+		return -ENOMEM;
+
+	mutex_lock(&ftrace_regex_lock);
+	if ((file->f_mode & FMODE_WRITE) &&
+	    !(file->f_flags & O_APPEND))
+		ftrace_filter_reset(enable);
+
+	if (file->f_mode & FMODE_READ) {
+		iter->pg = ftrace_pages_start;
+		iter->pos = -1;
+		iter->flags = enable ? FTRACE_ITER_FILTER :
+			FTRACE_ITER_NOTRACE;
+
+		ret = seq_open(file, &show_ftrace_seq_ops);
+		if (!ret) {
+			struct seq_file *m = file->private_data;
+			m->private = iter;
+		} else
+			kfree(iter);
+	} else
+		file->private_data = iter;
+	mutex_unlock(&ftrace_regex_lock);
+
+	return ret;
+}
+
+static int
+ftrace_filter_open(struct inode *inode, struct file *file)
+{
+	return ftrace_regex_open(inode, file, 1);
+}
+
+static int
+ftrace_notrace_open(struct inode *inode, struct file *file)
+{
+	return ftrace_regex_open(inode, file, 0);
+}
+
+static ssize_t
+ftrace_regex_read(struct file *file, char __user *ubuf,
+		       size_t cnt, loff_t *ppos)
+{
+	if (file->f_mode & FMODE_READ)
+		return seq_read(file, ubuf, cnt, ppos);
+	else
+		return -EPERM;
+}
+
+static loff_t
+ftrace_regex_lseek(struct file *file, loff_t offset, int origin)
+{
+	loff_t ret;
+
+	if (file->f_mode & FMODE_READ)
+		ret = seq_lseek(file, offset, origin);
+	else
+		file->f_pos = ret = 1;
+
+	return ret;
+}
+
+enum {
+	MATCH_FULL,
+	MATCH_FRONT_ONLY,
+	MATCH_MIDDLE_ONLY,
+	MATCH_END_ONLY,
+};
+
+static void
+ftrace_match(unsigned char *buff, int len, int enable)
+{
+	char str[KSYM_SYMBOL_LEN];
+	char *search = NULL;
+	struct ftrace_page *pg;
+	struct dyn_ftrace *rec;
+	int type = MATCH_FULL;
+	unsigned long flag = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
+	unsigned i, match = 0, search_len = 0;
+
+	for (i = 0; i < len; i++) {
+		if (buff[i] == '*') {
+			if (!i) {
+				search = buff + i + 1;
+				type = MATCH_END_ONLY;
+				search_len = len - (i + 1);
+			} else {
+				if (type == MATCH_END_ONLY) {
+					type = MATCH_MIDDLE_ONLY;
+				} else {
+					match = i;
+					type = MATCH_FRONT_ONLY;
+				}
+				buff[i] = 0;
+				break;
+			}
+		}
+	}
+
+	/* keep kstop machine from running */
+	preempt_disable();
+	if (enable)
+		ftrace_filtered = 1;
+	pg = ftrace_pages_start;
+	while (pg) {
+		for (i = 0; i < pg->index; i++) {
+			int matched = 0;
+			char *ptr;
+
+			rec = &pg->records[i];
+			if (rec->flags & FTRACE_FL_FAILED)
+				continue;
+			kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
+			switch (type) {
+			case MATCH_FULL:
+				if (strcmp(str, buff) == 0)
+					matched = 1;
+				break;
+			case MATCH_FRONT_ONLY:
+				if (memcmp(str, buff, match) == 0)
+					matched = 1;
+				break;
+			case MATCH_MIDDLE_ONLY:
+				if (strstr(str, search))
+					matched = 1;
+				break;
+			case MATCH_END_ONLY:
+				ptr = strstr(str, search);
+				if (ptr && (ptr[search_len] == 0))
+					matched = 1;
+				break;
+			}
+			if (matched)
+				rec->flags |= flag;
+		}
+		pg = pg->next;
+	}
+	preempt_enable();
+}
+
+static ssize_t
+ftrace_regex_write(struct file *file, const char __user *ubuf,
+		   size_t cnt, loff_t *ppos, int enable)
+{
+	struct ftrace_iterator *iter;
+	char ch;
+	size_t read = 0;
+	ssize_t ret;
+
+	if (!cnt || cnt < 0)
+		return 0;
+
+	mutex_lock(&ftrace_regex_lock);
+
+	if (file->f_mode & FMODE_READ) {
+		struct seq_file *m = file->private_data;
+		iter = m->private;
+	} else
+		iter = file->private_data;
+
+	if (!*ppos) {
+		iter->flags &= ~FTRACE_ITER_CONT;
+		iter->buffer_idx = 0;
+	}
+
+	ret = get_user(ch, ubuf++);
+	if (ret)
+		goto out;
+	read++;
+	cnt--;
+
+	if (!(iter->flags & ~FTRACE_ITER_CONT)) {
+		/* skip white space */
+		while (cnt && isspace(ch)) {
+			ret = get_user(ch, ubuf++);
+			if (ret)
+				goto out;
+			read++;
+			cnt--;
+		}
+
+		if (isspace(ch)) {
+			file->f_pos += read;
+			ret = read;
+			goto out;
+		}
+
+		iter->buffer_idx = 0;
+	}
+
+	while (cnt && !isspace(ch)) {
+		if (iter->buffer_idx < FTRACE_BUFF_MAX)
+			iter->buffer[iter->buffer_idx++] = ch;
+		else {
+			ret = -EINVAL;
+			goto out;
+		}
+		ret = get_user(ch, ubuf++);
+		if (ret)
+			goto out;
+		read++;
+		cnt--;
+	}
+
+	if (isspace(ch)) {
+		iter->filtered++;
+		iter->buffer[iter->buffer_idx] = 0;
+		ftrace_match(iter->buffer, iter->buffer_idx, enable);
+		iter->buffer_idx = 0;
+	} else
+		iter->flags |= FTRACE_ITER_CONT;
+
+
+	file->f_pos += read;
+
+	ret = read;
+ out:
+	mutex_unlock(&ftrace_regex_lock);
+
+	return ret;
+}
+
+static ssize_t
+ftrace_filter_write(struct file *file, const char __user *ubuf,
+		    size_t cnt, loff_t *ppos)
+{
+	return ftrace_regex_write(file, ubuf, cnt, ppos, 1);
+}
+
+static ssize_t
+ftrace_notrace_write(struct file *file, const char __user *ubuf,
+		     size_t cnt, loff_t *ppos)
+{
+	return ftrace_regex_write(file, ubuf, cnt, ppos, 0);
+}
+
+static void
+ftrace_set_regex(unsigned char *buf, int len, int reset, int enable)
+{
+	if (unlikely(ftrace_disabled))
+		return;
+
+	mutex_lock(&ftrace_regex_lock);
+	if (reset)
+		ftrace_filter_reset(enable);
+	if (buf)
+		ftrace_match(buf, len, enable);
+	mutex_unlock(&ftrace_regex_lock);
+}
+
+/**
+ * ftrace_set_filter - set a function to filter on in ftrace
+ * @buf - the string that holds the function filter text.
+ * @len - the length of the string.
+ * @reset - non zero to reset all filters before applying this filter.
+ *
+ * Filters denote which functions should be enabled when tracing is enabled.
+ * If @buf is NULL and reset is set, all functions will be enabled for tracing.
+ */
+void ftrace_set_filter(unsigned char *buf, int len, int reset)
+{
+	ftrace_set_regex(buf, len, reset, 1);
+}
+
+/**
+ * ftrace_set_notrace - set a function to not trace in ftrace
+ * @buf - the string that holds the function notrace text.
+ * @len - the length of the string.
+ * @reset - non zero to reset all filters before applying this filter.
+ *
+ * Notrace Filters denote which functions should not be enabled when tracing
+ * is enabled. If @buf is NULL and reset is set, all functions will be enabled
+ * for tracing.
+ */
+void ftrace_set_notrace(unsigned char *buf, int len, int reset)
+{
+	ftrace_set_regex(buf, len, reset, 0);
+}
+
+static int
+ftrace_regex_release(struct inode *inode, struct file *file, int enable)
+{
+	struct seq_file *m = (struct seq_file *)file->private_data;
+	struct ftrace_iterator *iter;
+
+	mutex_lock(&ftrace_regex_lock);
+	if (file->f_mode & FMODE_READ) {
+		iter = m->private;
+
+		seq_release(inode, file);
+	} else
+		iter = file->private_data;
+
+	if (iter->buffer_idx) {
+		iter->filtered++;
+		iter->buffer[iter->buffer_idx] = 0;
+		ftrace_match(iter->buffer, iter->buffer_idx, enable);
+	}
+
+	mutex_lock(&ftrace_sysctl_lock);
+	mutex_lock(&ftraced_lock);
+	if (iter->filtered && ftraced_suspend && ftrace_enabled)
+		ftrace_run_update_code(FTRACE_ENABLE_CALLS);
+	mutex_unlock(&ftraced_lock);
+	mutex_unlock(&ftrace_sysctl_lock);
+
+	kfree(iter);
+	mutex_unlock(&ftrace_regex_lock);
+	return 0;
+}
+
+static int
+ftrace_filter_release(struct inode *inode, struct file *file)
+{
+	return ftrace_regex_release(inode, file, 1);
+}
+
+static int
+ftrace_notrace_release(struct inode *inode, struct file *file)
+{
+	return ftrace_regex_release(inode, file, 0);
+}
+
+static ssize_t
+ftraced_read(struct file *filp, char __user *ubuf,
+		     size_t cnt, loff_t *ppos)
+{
+	/* don't worry about races */
+	char *buf = ftraced_stop ? "disabled\n" : "enabled\n";
+	int r = strlen(buf);
+
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t
+ftraced_write(struct file *filp, const char __user *ubuf,
+		      size_t cnt, loff_t *ppos)
+{
+	char buf[64];
+	long val;
+	int ret;
+
+	if (cnt >= sizeof(buf))
+		return -EINVAL;
+
+	if (copy_from_user(&buf, ubuf, cnt))
+		return -EFAULT;
+
+	if (strncmp(buf, "enable", 6) == 0)
+		val = 1;
+	else if (strncmp(buf, "disable", 7) == 0)
+		val = 0;
+	else {
+		buf[cnt] = 0;
+
+		ret = strict_strtoul(buf, 10, &val);
+		if (ret < 0)
+			return ret;
+
+		val = !!val;
+	}
+
+	if (val)
+		ftrace_enable_daemon();
+	else
+		ftrace_disable_daemon();
+
+	filp->f_pos += cnt;
+
+	return cnt;
+}
+
+static struct file_operations ftrace_avail_fops = {
+	.open = ftrace_avail_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = ftrace_avail_release,
+};
+
+static struct file_operations ftrace_failures_fops = {
+	.open = ftrace_failures_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = ftrace_avail_release,
+};
+
+static struct file_operations ftrace_filter_fops = {
+	.open = ftrace_filter_open,
+	.read = ftrace_regex_read,
+	.write = ftrace_filter_write,
+	.llseek = ftrace_regex_lseek,
+	.release = ftrace_filter_release,
+};
+
+static struct file_operations ftrace_notrace_fops = {
+	.open = ftrace_notrace_open,
+	.read = ftrace_regex_read,
+	.write = ftrace_notrace_write,
+	.llseek = ftrace_regex_lseek,
+	.release = ftrace_notrace_release,
+};
+
+static struct file_operations ftraced_fops = {
+	.open = tracing_open_generic,
+	.read = ftraced_read,
+	.write = ftraced_write,
+};
+
+/**
+ * ftrace_force_update - force an update to all recording ftrace functions
+ */
+int ftrace_force_update(void)
+{
+	int ret = 0;
+
+	if (unlikely(ftrace_disabled))
+		return -ENODEV;
+
+	mutex_lock(&ftrace_sysctl_lock);
+	mutex_lock(&ftraced_lock);
+
+	/*
+	 * If ftraced_trigger is not set, then there is nothing
+	 * to update.
+	 */
+	if (ftraced_trigger && !ftrace_update_code())
+		ret = -EBUSY;
+
+	mutex_unlock(&ftraced_lock);
+	mutex_unlock(&ftrace_sysctl_lock);
+
+	return ret;
+}
+
+static void ftrace_force_shutdown(void)
+{
+	struct task_struct *task;
+	int command = FTRACE_DISABLE_CALLS | FTRACE_UPDATE_TRACE_FUNC;
+
+	mutex_lock(&ftraced_lock);
+	task = ftraced_task;
+	ftraced_task = NULL;
+	ftraced_suspend = -1;
+	ftrace_run_update_code(command);
+	mutex_unlock(&ftraced_lock);
+
+	if (task)
+		kthread_stop(task);
+}
+
+static __init int ftrace_init_debugfs(void)
+{
+	struct dentry *d_tracer;
+	struct dentry *entry;
+
+	d_tracer = tracing_init_dentry();
+
+	entry = debugfs_create_file("available_filter_functions", 0444,
+				    d_tracer, NULL, &ftrace_avail_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'available_filter_functions' entry\n");
+
+	entry = debugfs_create_file("failures", 0444,
+				    d_tracer, NULL, &ftrace_failures_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs 'failures' entry\n");
+
+	entry = debugfs_create_file("set_ftrace_filter", 0644, d_tracer,
+				    NULL, &ftrace_filter_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'set_ftrace_filter' entry\n");
+
+	entry = debugfs_create_file("set_ftrace_notrace", 0644, d_tracer,
+				    NULL, &ftrace_notrace_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'set_ftrace_notrace' entry\n");
+
+	entry = debugfs_create_file("ftraced_enabled", 0644, d_tracer,
+				    NULL, &ftraced_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'ftraced_enabled' entry\n");
+	return 0;
+}
+
+fs_initcall(ftrace_init_debugfs);
+
+static int __init ftrace_dynamic_init(void)
+{
+	struct task_struct *p;
+	unsigned long addr;
+	int ret;
+
+	addr = (unsigned long)ftrace_record_ip;
+
+	stop_machine_run(ftrace_dyn_arch_init, &addr, NR_CPUS);
+
+	/* ftrace_dyn_arch_init places the return code in addr */
+	if (addr) {
+		ret = (int)addr;
+		goto failed;
+	}
+
+	ret = ftrace_dyn_table_alloc();
+	if (ret)
+		goto failed;
+
+	p = kthread_run(ftraced, NULL, "ftraced");
+	if (IS_ERR(p)) {
+		ret = -1;
+		goto failed;
+	}
+
+	last_ftrace_enabled = ftrace_enabled = 1;
+	ftraced_task = p;
+
+	return 0;
+
+ failed:
+	ftrace_disabled = 1;
+	return ret;
+}
+
+core_initcall(ftrace_dynamic_init);
+#else
+# define ftrace_startup()		do { } while (0)
+# define ftrace_shutdown()		do { } while (0)
+# define ftrace_startup_sysctl()	do { } while (0)
+# define ftrace_shutdown_sysctl()	do { } while (0)
+# define ftrace_force_shutdown()	do { } while (0)
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+/**
+ * ftrace_kill - totally shutdown ftrace
+ *
+ * This is a safety measure. If something was detected that seems
+ * wrong, calling this function will keep ftrace from doing
+ * any more modifications, and updates.
+ * used when something went wrong.
+ */
+void ftrace_kill(void)
+{
+	mutex_lock(&ftrace_sysctl_lock);
+	ftrace_disabled = 1;
+	ftrace_enabled = 0;
+
+	clear_ftrace_function();
+	mutex_unlock(&ftrace_sysctl_lock);
+
+	/* Try to totally disable ftrace */
+	ftrace_force_shutdown();
+}
+
+/**
+ * register_ftrace_function - register a function for profiling
+ * @ops - ops structure that holds the function for profiling.
+ *
+ * Register a function to be called by all functions in the
+ * kernel.
+ *
+ * Note: @ops->func and all the functions it calls must be labeled
+ *       with "notrace", otherwise it will go into a
+ *       recursive loop.
+ */
+int register_ftrace_function(struct ftrace_ops *ops)
+{
+	int ret;
+
+	if (unlikely(ftrace_disabled))
+		return -1;
+
+	mutex_lock(&ftrace_sysctl_lock);
+	ret = __register_ftrace_function(ops);
+	ftrace_startup();
+	mutex_unlock(&ftrace_sysctl_lock);
+
+	return ret;
+}
+
+/**
+ * unregister_ftrace_function - unresgister a function for profiling.
+ * @ops - ops structure that holds the function to unregister
+ *
+ * Unregister a function that was added to be called by ftrace profiling.
+ */
+int unregister_ftrace_function(struct ftrace_ops *ops)
+{
+	int ret;
+
+	mutex_lock(&ftrace_sysctl_lock);
+	ret = __unregister_ftrace_function(ops);
+	ftrace_shutdown();
+	mutex_unlock(&ftrace_sysctl_lock);
+
+	return ret;
+}
+
+int
+ftrace_enable_sysctl(struct ctl_table *table, int write,
+		     struct file *file, void __user *buffer, size_t *lenp,
+		     loff_t *ppos)
+{
+	int ret;
+
+	if (unlikely(ftrace_disabled))
+		return -ENODEV;
+
+	mutex_lock(&ftrace_sysctl_lock);
+
+	ret  = proc_dointvec(table, write, file, buffer, lenp, ppos);
+
+	if (ret || !write || (last_ftrace_enabled == ftrace_enabled))
+		goto out;
+
+	last_ftrace_enabled = ftrace_enabled;
+
+	if (ftrace_enabled) {
+
+		ftrace_startup_sysctl();
+
+		/* we are starting ftrace again */
+		if (ftrace_list != &ftrace_list_end) {
+			if (ftrace_list->next == &ftrace_list_end)
+				ftrace_trace_function = ftrace_list->func;
+			else
+				ftrace_trace_function = ftrace_list_func;
+		}
+
+	} else {
+		/* stopping ftrace calls (just send to ftrace_stub) */
+		ftrace_trace_function = ftrace_stub;
+
+		ftrace_shutdown_sysctl();
+	}
+
+ out:
+	mutex_unlock(&ftrace_sysctl_lock);
+	return ret;
+}

kernel/trace/trace.c

@@ -0,0 +1,3100 @@
+/*
+ * ring buffer based function tracer
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
+ *
+ * Originally taken from the RT patch by:
+ *    Arnaldo Carvalho de Melo <acme@redhat.com>
+ *
+ * Based on code from the latency_tracer, that is:
+ *  Copyright (C) 2004-2006 Ingo Molnar
+ *  Copyright (C) 2004 William Lee Irwin III
+ */
+#include <linux/utsrelease.h>
+#include <linux/kallsyms.h>
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
+#include <linux/pagemap.h>
+#include <linux/hardirq.h>
+#include <linux/linkage.h>
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <linux/module.h>
+#include <linux/percpu.h>
+#include <linux/ctype.h>
+#include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/gfp.h>
+#include <linux/fs.h>
+#include <linux/kprobes.h>
+#include <linux/writeback.h>
+
+#include <linux/stacktrace.h>
+
+#include "trace.h"
+
+unsigned long __read_mostly	tracing_max_latency = (cycle_t)ULONG_MAX;
+unsigned long __read_mostly	tracing_thresh;
+
+static unsigned long __read_mostly	tracing_nr_buffers;
+static cpumask_t __read_mostly		tracing_buffer_mask;
+
+#define for_each_tracing_cpu(cpu)	\
+	for_each_cpu_mask(cpu, tracing_buffer_mask)
+
+static int trace_alloc_page(void);
+static int trace_free_page(void);
+
+static int tracing_disabled = 1;
+
+static unsigned long tracing_pages_allocated;
+
+long
+ns2usecs(cycle_t nsec)
+{
+	nsec += 500;
+	do_div(nsec, 1000);
+	return nsec;
+}
+
+cycle_t ftrace_now(int cpu)
+{
+	return cpu_clock(cpu);
+}
+
+/*
+ * The global_trace is the descriptor that holds the tracing
+ * buffers for the live tracing. For each CPU, it contains
+ * a link list of pages that will store trace entries. The
+ * page descriptor of the pages in the memory is used to hold
+ * the link list by linking the lru item in the page descriptor
+ * to each of the pages in the buffer per CPU.
+ *
+ * For each active CPU there is a data field that holds the
+ * pages for the buffer for that CPU. Each CPU has the same number
+ * of pages allocated for its buffer.
+ */
+static struct trace_array	global_trace;
+
+static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
+
+/*
+ * The max_tr is used to snapshot the global_trace when a maximum
+ * latency is reached. Some tracers will use this to store a maximum
+ * trace while it continues examining live traces.
+ *
+ * The buffers for the max_tr are set up the same as the global_trace.
+ * When a snapshot is taken, the link list of the max_tr is swapped
+ * with the link list of the global_trace and the buffers are reset for
+ * the global_trace so the tracing can continue.
+ */
+static struct trace_array	max_tr;
+
+static DEFINE_PER_CPU(struct trace_array_cpu, max_data);
+
+/* tracer_enabled is used to toggle activation of a tracer */
+static int			tracer_enabled = 1;
+
+/*
+ * trace_nr_entries is the number of entries that is allocated
+ * for a buffer. Note, the number of entries is always rounded
+ * to ENTRIES_PER_PAGE.
+ */
+static unsigned long		trace_nr_entries = 65536UL;
+
+/* trace_types holds a link list of available tracers. */
+static struct tracer		*trace_types __read_mostly;
+
+/* current_trace points to the tracer that is currently active */
+static struct tracer		*current_trace __read_mostly;
+
+/*
+ * max_tracer_type_len is used to simplify the allocating of
+ * buffers to read userspace tracer names. We keep track of
+ * the longest tracer name registered.
+ */
+static int			max_tracer_type_len;
+
+/*
+ * trace_types_lock is used to protect the trace_types list.
+ * This lock is also used to keep user access serialized.
+ * Accesses from userspace will grab this lock while userspace
+ * activities happen inside the kernel.
+ */
+static DEFINE_MUTEX(trace_types_lock);
+
+/* trace_wait is a waitqueue for tasks blocked on trace_poll */
+static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
+
+/* trace_flags holds iter_ctrl options */
+unsigned long trace_flags = TRACE_ITER_PRINT_PARENT;
+
+static notrace void no_trace_init(struct trace_array *tr)
+{
+	int cpu;
+
+	if(tr->ctrl)
+		for_each_online_cpu(cpu)
+			tracing_reset(tr->data[cpu]);
+	tracer_enabled = 0;
+}
+
+/* dummy trace to disable tracing */
+static struct tracer no_tracer __read_mostly = {
+	.name		= "none",
+	.init		= no_trace_init
+};
+
+
+/**
+ * trace_wake_up - wake up tasks waiting for trace input
+ *
+ * Simply wakes up any task that is blocked on the trace_wait
+ * queue. These is used with trace_poll for tasks polling the trace.
+ */
+void trace_wake_up(void)
+{
+	/*
+	 * The runqueue_is_locked() can fail, but this is the best we
+	 * have for now:
+	 */
+	if (!(trace_flags & TRACE_ITER_BLOCK) && !runqueue_is_locked())
+		wake_up(&trace_wait);
+}
+
+#define ENTRIES_PER_PAGE (PAGE_SIZE / sizeof(struct trace_entry))
+
+static int __init set_nr_entries(char *str)
+{
+	unsigned long nr_entries;
+	int ret;
+
+	if (!str)
+		return 0;
+	ret = strict_strtoul(str, 0, &nr_entries);
+	/* nr_entries can not be zero */
+	if (ret < 0 || nr_entries == 0)
+		return 0;
+	trace_nr_entries = nr_entries;
+	return 1;
+}
+__setup("trace_entries=", set_nr_entries);
+
+unsigned long nsecs_to_usecs(unsigned long nsecs)
+{
+	return nsecs / 1000;
+}
+
+/*
+ * trace_flag_type is an enumeration that holds different
+ * states when a trace occurs. These are:
+ *  IRQS_OFF	- interrupts were disabled
+ *  NEED_RESCED - reschedule is requested
+ *  HARDIRQ	- inside an interrupt handler
+ *  SOFTIRQ	- inside a softirq handler
+ */
+enum trace_flag_type {
+	TRACE_FLAG_IRQS_OFF		= 0x01,
+	TRACE_FLAG_NEED_RESCHED		= 0x02,
+	TRACE_FLAG_HARDIRQ		= 0x04,
+	TRACE_FLAG_SOFTIRQ		= 0x08,
+};
+
+/*
+ * TRACE_ITER_SYM_MASK masks the options in trace_flags that
+ * control the output of kernel symbols.
+ */
+#define TRACE_ITER_SYM_MASK \
+	(TRACE_ITER_PRINT_PARENT|TRACE_ITER_SYM_OFFSET|TRACE_ITER_SYM_ADDR)
+
+/* These must match the bit postions in trace_iterator_flags */
+static const char *trace_options[] = {
+	"print-parent",
+	"sym-offset",
+	"sym-addr",
+	"verbose",
+	"raw",
+	"hex",
+	"bin",
+	"block",
+	"stacktrace",
+	"sched-tree",
+	NULL
+};
+
+/*
+ * ftrace_max_lock is used to protect the swapping of buffers
+ * when taking a max snapshot. The buffers themselves are
+ * protected by per_cpu spinlocks. But the action of the swap
+ * needs its own lock.
+ *
+ * This is defined as a raw_spinlock_t in order to help
+ * with performance when lockdep debugging is enabled.
+ */
+static raw_spinlock_t ftrace_max_lock =
+	(raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
+
+/*
+ * Copy the new maximum trace into the separate maximum-trace
+ * structure. (this way the maximum trace is permanently saved,
+ * for later retrieval via /debugfs/tracing/latency_trace)
+ */
+static void
+__update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
+{
+	struct trace_array_cpu *data = tr->data[cpu];
+
+	max_tr.cpu = cpu;
+	max_tr.time_start = data->preempt_timestamp;
+
+	data = max_tr.data[cpu];
+	data->saved_latency = tracing_max_latency;
+
+	memcpy(data->comm, tsk->comm, TASK_COMM_LEN);
+	data->pid = tsk->pid;
+	data->uid = tsk->uid;
+	data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
+	data->policy = tsk->policy;
+	data->rt_priority = tsk->rt_priority;
+
+	/* record this tasks comm */
+	tracing_record_cmdline(current);
+}
+
+#define CHECK_COND(cond)			\
+	if (unlikely(cond)) {			\
+		tracing_disabled = 1;		\
+		WARN_ON(1);			\
+		return -1;			\
+	}
+
+/**
+ * check_pages - integrity check of trace buffers
+ *
+ * As a safty measure we check to make sure the data pages have not
+ * been corrupted.
+ */
+int check_pages(struct trace_array_cpu *data)
+{
+	struct page *page, *tmp;
+
+	CHECK_COND(data->trace_pages.next->prev != &data->trace_pages);
+	CHECK_COND(data->trace_pages.prev->next != &data->trace_pages);
+
+	list_for_each_entry_safe(page, tmp, &data->trace_pages, lru) {
+		CHECK_COND(page->lru.next->prev != &page->lru);
+		CHECK_COND(page->lru.prev->next != &page->lru);
+	}
+
+	return 0;
+}
+
+/**
+ * head_page - page address of the first page in per_cpu buffer.
+ *
+ * head_page returns the page address of the first page in
+ * a per_cpu buffer. This also preforms various consistency
+ * checks to make sure the buffer has not been corrupted.
+ */
+void *head_page(struct trace_array_cpu *data)
+{
+	struct page *page;
+
+	if (list_empty(&data->trace_pages))
+		return NULL;
+
+	page = list_entry(data->trace_pages.next, struct page, lru);
+	BUG_ON(&page->lru == &data->trace_pages);
+
+	return page_address(page);
+}
+
+/**
+ * trace_seq_printf - sequence printing of trace information
+ * @s: trace sequence descriptor
+ * @fmt: printf format string
+ *
+ * The tracer may use either sequence operations or its own
+ * copy to user routines. To simplify formating of a trace
+ * trace_seq_printf is used to store strings into a special
+ * buffer (@s). Then the output may be either used by
+ * the sequencer or pulled into another buffer.
+ */
+int
+trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
+{
+	int len = (PAGE_SIZE - 1) - s->len;
+	va_list ap;
+	int ret;
+
+	if (!len)
+		return 0;
+
+	va_start(ap, fmt);
+	ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
+	va_end(ap);
+
+	/* If we can't write it all, don't bother writing anything */
+	if (ret >= len)
+		return 0;
+
+	s->len += ret;
+
+	return len;
+}
+
+/**
+ * trace_seq_puts - trace sequence printing of simple string
+ * @s: trace sequence descriptor
+ * @str: simple string to record
+ *
+ * The tracer may use either the sequence operations or its own
+ * copy to user routines. This function records a simple string
+ * into a special buffer (@s) for later retrieval by a sequencer
+ * or other mechanism.
+ */
+static int
+trace_seq_puts(struct trace_seq *s, const char *str)
+{
+	int len = strlen(str);
+
+	if (len > ((PAGE_SIZE - 1) - s->len))
+		return 0;
+
+	memcpy(s->buffer + s->len, str, len);
+	s->len += len;
+
+	return len;
+}
+
+static int
+trace_seq_putc(struct trace_seq *s, unsigned char c)
+{
+	if (s->len >= (PAGE_SIZE - 1))
+		return 0;
+
+	s->buffer[s->len++] = c;
+
+	return 1;
+}
+
+static int
+trace_seq_putmem(struct trace_seq *s, void *mem, size_t len)
+{
+	if (len > ((PAGE_SIZE - 1) - s->len))
+		return 0;
+
+	memcpy(s->buffer + s->len, mem, len);
+	s->len += len;
+
+	return len;
+}
+
+#define HEX_CHARS 17
+static const char hex2asc[] = "0123456789abcdef";
+
+static int
+trace_seq_putmem_hex(struct trace_seq *s, void *mem, size_t len)
+{
+	unsigned char hex[HEX_CHARS];
+	unsigned char *data = mem;
+	unsigned char byte;
+	int i, j;
+
+	BUG_ON(len >= HEX_CHARS);
+
+#ifdef __BIG_ENDIAN
+	for (i = 0, j = 0; i < len; i++) {
+#else
+	for (i = len-1, j = 0; i >= 0; i--) {
+#endif
+		byte = data[i];
+
+		hex[j++] = hex2asc[byte & 0x0f];
+		hex[j++] = hex2asc[byte >> 4];
+	}
+	hex[j++] = ' ';
+
+	return trace_seq_putmem(s, hex, j);
+}
+
+static void
+trace_seq_reset(struct trace_seq *s)
+{
+	s->len = 0;
+	s->readpos = 0;
+}
+
+ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
+{
+	int len;
+	int ret;
+
+	if (s->len <= s->readpos)
+		return -EBUSY;
+
+	len = s->len - s->readpos;
+	if (cnt > len)
+		cnt = len;
+	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
+	if (ret)
+		return -EFAULT;
+
+	s->readpos += len;
+	return cnt;
+}
+
+static void
+trace_print_seq(struct seq_file *m, struct trace_seq *s)
+{
+	int len = s->len >= PAGE_SIZE ? PAGE_SIZE - 1 : s->len;
+
+	s->buffer[len] = 0;
+	seq_puts(m, s->buffer);
+
+	trace_seq_reset(s);
+}
+
+/*
+ * flip the trace buffers between two trace descriptors.
+ * This usually is the buffers between the global_trace and
+ * the max_tr to record a snapshot of a current trace.
+ *
+ * The ftrace_max_lock must be held.
+ */
+static void
+flip_trace(struct trace_array_cpu *tr1, struct trace_array_cpu *tr2)
+{
+	struct list_head flip_pages;
+
+	INIT_LIST_HEAD(&flip_pages);
+
+	memcpy(&tr1->trace_head_idx, &tr2->trace_head_idx,
+		sizeof(struct trace_array_cpu) -
+		offsetof(struct trace_array_cpu, trace_head_idx));
+
+	check_pages(tr1);
+	check_pages(tr2);
+	list_splice_init(&tr1->trace_pages, &flip_pages);
+	list_splice_init(&tr2->trace_pages, &tr1->trace_pages);
+	list_splice_init(&flip_pages, &tr2->trace_pages);
+	BUG_ON(!list_empty(&flip_pages));
+	check_pages(tr1);
+	check_pages(tr2);
+}
+
+/**
+ * update_max_tr - snapshot all trace buffers from global_trace to max_tr
+ * @tr: tracer
+ * @tsk: the task with the latency
+ * @cpu: The cpu that initiated the trace.
+ *
+ * Flip the buffers between the @tr and the max_tr and record information
+ * about which task was the cause of this latency.
+ */
+void
+update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
+{
+	struct trace_array_cpu *data;
+	int i;
+
+	WARN_ON_ONCE(!irqs_disabled());
+	__raw_spin_lock(&ftrace_max_lock);
+	/* clear out all the previous traces */
+	for_each_tracing_cpu(i) {
+		data = tr->data[i];
+		flip_trace(max_tr.data[i], data);
+		tracing_reset(data);
+	}
+
+	__update_max_tr(tr, tsk, cpu);
+	__raw_spin_unlock(&ftrace_max_lock);
+}
+
+/**
+ * update_max_tr_single - only copy one trace over, and reset the rest
+ * @tr - tracer
+ * @tsk - task with the latency
+ * @cpu - the cpu of the buffer to copy.
+ *
+ * Flip the trace of a single CPU buffer between the @tr and the max_tr.
+ */
+void
+update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
+{
+	struct trace_array_cpu *data = tr->data[cpu];
+	int i;
+
+	WARN_ON_ONCE(!irqs_disabled());
+	__raw_spin_lock(&ftrace_max_lock);
+	for_each_tracing_cpu(i)
+		tracing_reset(max_tr.data[i]);
+
+	flip_trace(max_tr.data[cpu], data);
+	tracing_reset(data);
+
+	__update_max_tr(tr, tsk, cpu);
+	__raw_spin_unlock(&ftrace_max_lock);
+}
+
+/**
+ * register_tracer - register a tracer with the ftrace system.
+ * @type - the plugin for the tracer
+ *
+ * Register a new plugin tracer.
+ */
+int register_tracer(struct tracer *type)
+{
+	struct tracer *t;
+	int len;
+	int ret = 0;
+
+	if (!type->name) {
+		pr_info("Tracer must have a name\n");
+		return -1;
+	}
+
+	mutex_lock(&trace_types_lock);
+	for (t = trace_types; t; t = t->next) {
+		if (strcmp(type->name, t->name) == 0) {
+			/* already found */
+			pr_info("Trace %s already registered\n",
+				type->name);
+			ret = -1;
+			goto out;
+		}
+	}
+
+#ifdef CONFIG_FTRACE_STARTUP_TEST
+	if (type->selftest) {
+		struct tracer *saved_tracer = current_trace;
+		struct trace_array_cpu *data;
+		struct trace_array *tr = &global_trace;
+		int saved_ctrl = tr->ctrl;
+		int i;
+		/*
+		 * Run a selftest on this tracer.
+		 * Here we reset the trace buffer, and set the current
+		 * tracer to be this tracer. The tracer can then run some
+		 * internal tracing to verify that everything is in order.
+		 * If we fail, we do not register this tracer.
+		 */
+		for_each_tracing_cpu(i) {
+			data = tr->data[i];
+			if (!head_page(data))
+				continue;
+			tracing_reset(data);
+		}
+		current_trace = type;
+		tr->ctrl = 0;
+		/* the test is responsible for initializing and enabling */
+		pr_info("Testing tracer %s: ", type->name);
+		ret = type->selftest(type, tr);
+		/* the test is responsible for resetting too */
+		current_trace = saved_tracer;
+		tr->ctrl = saved_ctrl;
+		if (ret) {
+			printk(KERN_CONT "FAILED!\n");
+			goto out;
+		}
+		/* Only reset on passing, to avoid touching corrupted buffers */
+		for_each_tracing_cpu(i) {
+			data = tr->data[i];
+			if (!head_page(data))
+				continue;
+			tracing_reset(data);
+		}
+		printk(KERN_CONT "PASSED\n");
+	}
+#endif
+
+	type->next = trace_types;
+	trace_types = type;
+	len = strlen(type->name);
+	if (len > max_tracer_type_len)
+		max_tracer_type_len = len;
+
+ out:
+	mutex_unlock(&trace_types_lock);
+
+	return ret;
+}
+
+void unregister_tracer(struct tracer *type)
+{
+	struct tracer **t;
+	int len;
+
+	mutex_lock(&trace_types_lock);
+	for (t = &trace_types; *t; t = &(*t)->next) {
+		if (*t == type)
+			goto found;
+	}
+	pr_info("Trace %s not registered\n", type->name);
+	goto out;
+
+ found:
+	*t = (*t)->next;
+	if (strlen(type->name) != max_tracer_type_len)
+		goto out;
+
+	max_tracer_type_len = 0;
+	for (t = &trace_types; *t; t = &(*t)->next) {
+		len = strlen((*t)->name);
+		if (len > max_tracer_type_len)
+			max_tracer_type_len = len;
+	}
+ out:
+	mutex_unlock(&trace_types_lock);
+}
+
+void tracing_reset(struct trace_array_cpu *data)
+{
+	data->trace_idx = 0;
+	data->overrun = 0;
+	data->trace_head = data->trace_tail = head_page(data);
+	data->trace_head_idx = 0;
+	data->trace_tail_idx = 0;
+}
+
+#define SAVED_CMDLINES 128
+static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
+static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
+static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
+static int cmdline_idx;
+static DEFINE_SPINLOCK(trace_cmdline_lock);
+
+/* temporary disable recording */
+atomic_t trace_record_cmdline_disabled __read_mostly;
+
+static void trace_init_cmdlines(void)
+{
+	memset(&map_pid_to_cmdline, -1, sizeof(map_pid_to_cmdline));
+	memset(&map_cmdline_to_pid, -1, sizeof(map_cmdline_to_pid));
+	cmdline_idx = 0;
+}
+
+void trace_stop_cmdline_recording(void);
+
+static void trace_save_cmdline(struct task_struct *tsk)
+{
+	unsigned map;
+	unsigned idx;
+
+	if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
+		return;
+
+	/*
+	 * It's not the end of the world if we don't get
+	 * the lock, but we also don't want to spin
+	 * nor do we want to disable interrupts,
+	 * so if we miss here, then better luck next time.
+	 */
+	if (!spin_trylock(&trace_cmdline_lock))
+		return;
+
+	idx = map_pid_to_cmdline[tsk->pid];
+	if (idx >= SAVED_CMDLINES) {
+		idx = (cmdline_idx + 1) % SAVED_CMDLINES;
+
+		map = map_cmdline_to_pid[idx];
+		if (map <= PID_MAX_DEFAULT)
+			map_pid_to_cmdline[map] = (unsigned)-1;
+
+		map_pid_to_cmdline[tsk->pid] = idx;
+
+		cmdline_idx = idx;
+	}
+
+	memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);
+
+	spin_unlock(&trace_cmdline_lock);
+}
+
+static char *trace_find_cmdline(int pid)
+{
+	char *cmdline = "<...>";
+	unsigned map;
+
+	if (!pid)
+		return "<idle>";
+
+	if (pid > PID_MAX_DEFAULT)
+		goto out;
+
+	map = map_pid_to_cmdline[pid];
+	if (map >= SAVED_CMDLINES)
+		goto out;
+
+	cmdline = saved_cmdlines[map];
+
+ out:
+	return cmdline;
+}
+
+void tracing_record_cmdline(struct task_struct *tsk)
+{
+	if (atomic_read(&trace_record_cmdline_disabled))
+		return;
+
+	trace_save_cmdline(tsk);
+}
+
+static inline struct list_head *
+trace_next_list(struct trace_array_cpu *data, struct list_head *next)
+{
+	/*
+	 * Roundrobin - but skip the head (which is not a real page):
+	 */
+	next = next->next;
+	if (unlikely(next == &data->trace_pages))
+		next = next->next;
+	BUG_ON(next == &data->trace_pages);
+
+	return next;
+}
+
+static inline void *
+trace_next_page(struct trace_array_cpu *data, void *addr)
+{
+	struct list_head *next;
+	struct page *page;
+
+	page = virt_to_page(addr);
+
+	next = trace_next_list(data, &page->lru);
+	page = list_entry(next, struct page, lru);
+
+	return page_address(page);
+}
+
+static inline struct trace_entry *
+tracing_get_trace_entry(struct trace_array *tr, struct trace_array_cpu *data)
+{
+	unsigned long idx, idx_next;
+	struct trace_entry *entry;
+
+	data->trace_idx++;
+	idx = data->trace_head_idx;
+	idx_next = idx + 1;
+
+	BUG_ON(idx * TRACE_ENTRY_SIZE >= PAGE_SIZE);
+
+	entry = data->trace_head + idx * TRACE_ENTRY_SIZE;
+
+	if (unlikely(idx_next >= ENTRIES_PER_PAGE)) {
+		data->trace_head = trace_next_page(data, data->trace_head);
+		idx_next = 0;
+	}
+
+	if (data->trace_head == data->trace_tail &&
+	    idx_next == data->trace_tail_idx) {
+		/* overrun */
+		data->overrun++;
+		data->trace_tail_idx++;
+		if (data->trace_tail_idx >= ENTRIES_PER_PAGE) {
+			data->trace_tail =
+				trace_next_page(data, data->trace_tail);
+			data->trace_tail_idx = 0;
+		}
+	}
+
+	data->trace_head_idx = idx_next;
+
+	return entry;
+}
+
+static inline void
+tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags)
+{
+	struct task_struct *tsk = current;
+	unsigned long pc;
+
+	pc = preempt_count();
+
+	entry->preempt_count	= pc & 0xff;
+	entry->pid		= (tsk) ? tsk->pid : 0;
+	entry->t		= ftrace_now(raw_smp_processor_id());
+	entry->flags = (irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
+		((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
+		((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
+		(need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
+}
+
+void
+trace_function(struct trace_array *tr, struct trace_array_cpu *data,
+	       unsigned long ip, unsigned long parent_ip, unsigned long flags)
+{
+	struct trace_entry *entry;
+	unsigned long irq_flags;
+
+	raw_local_irq_save(irq_flags);
+	__raw_spin_lock(&data->lock);
+	entry			= tracing_get_trace_entry(tr, data);
+	tracing_generic_entry_update(entry, flags);
+	entry->type		= TRACE_FN;
+	entry->fn.ip		= ip;
+	entry->fn.parent_ip	= parent_ip;
+	__raw_spin_unlock(&data->lock);
+	raw_local_irq_restore(irq_flags);
+}
+
+void
+ftrace(struct trace_array *tr, struct trace_array_cpu *data,
+       unsigned long ip, unsigned long parent_ip, unsigned long flags)
+{
+	if (likely(!atomic_read(&data->disabled)))
+		trace_function(tr, data, ip, parent_ip, flags);
+}
+
+void __trace_stack(struct trace_array *tr,
+		   struct trace_array_cpu *data,
+		   unsigned long flags,
+		   int skip)
+{
+	struct trace_entry *entry;
+	struct stack_trace trace;
+
+	if (!(trace_flags & TRACE_ITER_STACKTRACE))
+		return;
+
+	entry			= tracing_get_trace_entry(tr, data);
+	tracing_generic_entry_update(entry, flags);
+	entry->type		= TRACE_STACK;
+
+	memset(&entry->stack, 0, sizeof(entry->stack));
+
+	trace.nr_entries	= 0;
+	trace.max_entries	= FTRACE_STACK_ENTRIES;
+	trace.skip		= skip;
+	trace.entries		= entry->stack.caller;
+
+	save_stack_trace(&trace);
+}
+
+void
+__trace_special(void *__tr, void *__data,
+		unsigned long arg1, unsigned long arg2, unsigned long arg3)
+{
+	struct trace_array_cpu *data = __data;
+	struct trace_array *tr = __tr;
+	struct trace_entry *entry;
+	unsigned long irq_flags;
+
+	raw_local_irq_save(irq_flags);
+	__raw_spin_lock(&data->lock);
+	entry			= tracing_get_trace_entry(tr, data);
+	tracing_generic_entry_update(entry, 0);
+	entry->type		= TRACE_SPECIAL;
+	entry->special.arg1	= arg1;
+	entry->special.arg2	= arg2;
+	entry->special.arg3	= arg3;
+	__trace_stack(tr, data, irq_flags, 4);
+	__raw_spin_unlock(&data->lock);
+	raw_local_irq_restore(irq_flags);
+
+	trace_wake_up();
+}
+
+void
+tracing_sched_switch_trace(struct trace_array *tr,
+			   struct trace_array_cpu *data,
+			   struct task_struct *prev,
+			   struct task_struct *next,
+			   unsigned long flags)
+{
+	struct trace_entry *entry;
+	unsigned long irq_flags;
+
+	raw_local_irq_save(irq_flags);
+	__raw_spin_lock(&data->lock);
+	entry			= tracing_get_trace_entry(tr, data);
+	tracing_generic_entry_update(entry, flags);
+	entry->type		= TRACE_CTX;
+	entry->ctx.prev_pid	= prev->pid;
+	entry->ctx.prev_prio	= prev->prio;
+	entry->ctx.prev_state	= prev->state;
+	entry->ctx.next_pid	= next->pid;
+	entry->ctx.next_prio	= next->prio;
+	entry->ctx.next_state	= next->state;
+	__trace_stack(tr, data, flags, 5);
+	__raw_spin_unlock(&data->lock);
+	raw_local_irq_restore(irq_flags);
+}
+
+void
+tracing_sched_wakeup_trace(struct trace_array *tr,
+			   struct trace_array_cpu *data,
+			   struct task_struct *wakee,
+			   struct task_struct *curr,
+			   unsigned long flags)
+{
+	struct trace_entry *entry;
+	unsigned long irq_flags;
+
+	raw_local_irq_save(irq_flags);
+	__raw_spin_lock(&data->lock);
+	entry			= tracing_get_trace_entry(tr, data);
+	tracing_generic_entry_update(entry, flags);
+	entry->type		= TRACE_WAKE;
+	entry->ctx.prev_pid	= curr->pid;
+	entry->ctx.prev_prio	= curr->prio;
+	entry->ctx.prev_state	= curr->state;
+	entry->ctx.next_pid	= wakee->pid;
+	entry->ctx.next_prio	= wakee->prio;
+	entry->ctx.next_state	= wakee->state;
+	__trace_stack(tr, data, flags, 6);
+	__raw_spin_unlock(&data->lock);
+	raw_local_irq_restore(irq_flags);
+
+	trace_wake_up();
+}
+
+void
+ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
+{
+	struct trace_array *tr = &global_trace;
+	struct trace_array_cpu *data;
+	unsigned long flags;
+	long disabled;
+	int cpu;
+
+	if (tracing_disabled || current_trace == &no_tracer || !tr->ctrl)
+		return;
+
+	local_irq_save(flags);
+	cpu = raw_smp_processor_id();
+	data = tr->data[cpu];
+	disabled = atomic_inc_return(&data->disabled);
+
+	if (likely(disabled == 1))
+		__trace_special(tr, data, arg1, arg2, arg3);
+
+	atomic_dec(&data->disabled);
+	local_irq_restore(flags);
+}
+
+#ifdef CONFIG_FTRACE
+static void
+function_trace_call(unsigned long ip, unsigned long parent_ip)
+{
+	struct trace_array *tr = &global_trace;
+	struct trace_array_cpu *data;
+	unsigned long flags;
+	long disabled;
+	int cpu;
+
+	if (unlikely(!tracer_enabled))
+		return;
+
+	if (skip_trace(ip))
+		return;
+
+	local_irq_save(flags);
+	cpu = raw_smp_processor_id();
+	data = tr->data[cpu];
+	disabled = atomic_inc_return(&data->disabled);
+
+	if (likely(disabled == 1))
+		trace_function(tr, data, ip, parent_ip, flags);
+
+	atomic_dec(&data->disabled);
+	local_irq_restore(flags);
+}
+
+static struct ftrace_ops trace_ops __read_mostly =
+{
+	.func = function_trace_call,
+};
+
+void tracing_start_function_trace(void)
+{
+	register_ftrace_function(&trace_ops);
+}
+
+void tracing_stop_function_trace(void)
+{
+	unregister_ftrace_function(&trace_ops);
+}
+#endif
+
+enum trace_file_type {
+	TRACE_FILE_LAT_FMT	= 1,
+};
+
+static struct trace_entry *
+trace_entry_idx(struct trace_array *tr, struct trace_array_cpu *data,
+		struct trace_iterator *iter, int cpu)
+{
+	struct page *page;
+	struct trace_entry *array;
+
+	if (iter->next_idx[cpu] >= tr->entries ||
+	    iter->next_idx[cpu] >= data->trace_idx ||
+	    (data->trace_head == data->trace_tail &&
+	     data->trace_head_idx == data->trace_tail_idx))
+		return NULL;
+
+	if (!iter->next_page[cpu]) {
+		/* Initialize the iterator for this cpu trace buffer */
+		WARN_ON(!data->trace_tail);
+		page = virt_to_page(data->trace_tail);
+		iter->next_page[cpu] = &page->lru;
+		iter->next_page_idx[cpu] = data->trace_tail_idx;
+	}
+
+	page = list_entry(iter->next_page[cpu], struct page, lru);
+	BUG_ON(&data->trace_pages == &page->lru);
+
+	array = page_address(page);
+
+	WARN_ON(iter->next_page_idx[cpu] >= ENTRIES_PER_PAGE);
+	return &array[iter->next_page_idx[cpu]];
+}
+
+static struct trace_entry *
+find_next_entry(struct trace_iterator *iter, int *ent_cpu)
+{
+	struct trace_array *tr = iter->tr;
+	struct trace_entry *ent, *next = NULL;
+	int next_cpu = -1;
+	int cpu;
+
+	for_each_tracing_cpu(cpu) {
+		if (!head_page(tr->data[cpu]))
+			continue;
+		ent = trace_entry_idx(tr, tr->data[cpu], iter, cpu);
+		/*
+		 * Pick the entry with the smallest timestamp:
+		 */
+		if (ent && (!next || ent->t < next->t)) {
+			next = ent;
+			next_cpu = cpu;
+		}
+	}
+
+	if (ent_cpu)
+		*ent_cpu = next_cpu;
+
+	return next;
+}
+
+static void trace_iterator_increment(struct trace_iterator *iter)
+{
+	iter->idx++;
+	iter->next_idx[iter->cpu]++;
+	iter->next_page_idx[iter->cpu]++;
+
+	if (iter->next_page_idx[iter->cpu] >= ENTRIES_PER_PAGE) {
+		struct trace_array_cpu *data = iter->tr->data[iter->cpu];
+
+		iter->next_page_idx[iter->cpu] = 0;
+		iter->next_page[iter->cpu] =
+			trace_next_list(data, iter->next_page[iter->cpu]);
+	}
+}
+
+static void trace_consume(struct trace_iterator *iter)
+{
+	struct trace_array_cpu *data = iter->tr->data[iter->cpu];
+
+	data->trace_tail_idx++;
+	if (data->trace_tail_idx >= ENTRIES_PER_PAGE) {
+		data->trace_tail = trace_next_page(data, data->trace_tail);
+		data->trace_tail_idx = 0;
+	}
+
+	/* Check if we empty it, then reset the index */
+	if (data->trace_head == data->trace_tail &&
+	    data->trace_head_idx == data->trace_tail_idx)
+		data->trace_idx = 0;
+}
+
+static void *find_next_entry_inc(struct trace_iterator *iter)
+{
+	struct trace_entry *next;
+	int next_cpu = -1;
+
+	next = find_next_entry(iter, &next_cpu);
+
+	iter->prev_ent = iter->ent;
+	iter->prev_cpu = iter->cpu;
+
+	iter->ent = next;
+	iter->cpu = next_cpu;
+
+	if (next)
+		trace_iterator_increment(iter);
+
+	return next ? iter : NULL;
+}
+
+static void *s_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct trace_iterator *iter = m->private;
+	void *last_ent = iter->ent;
+	int i = (int)*pos;
+	void *ent;
+
+	(*pos)++;
+
+	/* can't go backwards */
+	if (iter->idx > i)
+		return NULL;
+
+	if (iter->idx < 0)
+		ent = find_next_entry_inc(iter);
+	else
+		ent = iter;
+
+	while (ent && iter->idx < i)
+		ent = find_next_entry_inc(iter);
+
+	iter->pos = *pos;
+
+	if (last_ent && !ent)
+		seq_puts(m, "\n\nvim:ft=help\n");
+
+	return ent;
+}
+
+static void *s_start(struct seq_file *m, loff_t *pos)
+{
+	struct trace_iterator *iter = m->private;
+	void *p = NULL;
+	loff_t l = 0;
+	int i;
+
+	mutex_lock(&trace_types_lock);
+
+	if (!current_trace || current_trace != iter->trace) {
+		mutex_unlock(&trace_types_lock);
+		return NULL;
+	}
+
+	atomic_inc(&trace_record_cmdline_disabled);
+
+	/* let the tracer grab locks here if needed */
+	if (current_trace->start)
+		current_trace->start(iter);
+
+	if (*pos != iter->pos) {
+		iter->ent = NULL;
+		iter->cpu = 0;
+		iter->idx = -1;
+		iter->prev_ent = NULL;
+		iter->prev_cpu = -1;
+
+		for_each_tracing_cpu(i) {
+			iter->next_idx[i] = 0;
+			iter->next_page[i] = NULL;
+		}
+
+		for (p = iter; p && l < *pos; p = s_next(m, p, &l))
+			;
+
+	} else {
+		l = *pos - 1;
+		p = s_next(m, p, &l);
+	}
+
+	return p;
+}
+
+static void s_stop(struct seq_file *m, void *p)
+{
+	struct trace_iterator *iter = m->private;
+
+	atomic_dec(&trace_record_cmdline_disabled);
+
+	/* let the tracer release locks here if needed */
+	if (current_trace && current_trace == iter->trace && iter->trace->stop)
+		iter->trace->stop(iter);
+
+	mutex_unlock(&trace_types_lock);
+}
+
+#define KRETPROBE_MSG "[unknown/kretprobe'd]"
+
+#ifdef CONFIG_KRETPROBES
+static inline int kretprobed(unsigned long addr)
+{
+	return addr == (unsigned long)kretprobe_trampoline;
+}
+#else
+static inline int kretprobed(unsigned long addr)
+{
+	return 0;
+}
+#endif /* CONFIG_KRETPROBES */
+
+static int
+seq_print_sym_short(struct trace_seq *s, const char *fmt, unsigned long address)
+{
+#ifdef CONFIG_KALLSYMS
+	char str[KSYM_SYMBOL_LEN];
+
+	kallsyms_lookup(address, NULL, NULL, NULL, str);
+
+	return trace_seq_printf(s, fmt, str);
+#endif
+	return 1;
+}
+
+static int
+seq_print_sym_offset(struct trace_seq *s, const char *fmt,
+		     unsigned long address)
+{
+#ifdef CONFIG_KALLSYMS
+	char str[KSYM_SYMBOL_LEN];
+
+	sprint_symbol(str, address);
+	return trace_seq_printf(s, fmt, str);
+#endif
+	return 1;
+}
+
+#ifndef CONFIG_64BIT
+# define IP_FMT "%08lx"
+#else
+# define IP_FMT "%016lx"
+#endif
+
+static int
+seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
+{
+	int ret;
+
+	if (!ip)
+		return trace_seq_printf(s, "0");
+
+	if (sym_flags & TRACE_ITER_SYM_OFFSET)
+		ret = seq_print_sym_offset(s, "%s", ip);
+	else
+		ret = seq_print_sym_short(s, "%s", ip);
+
+	if (!ret)
+		return 0;
+
+	if (sym_flags & TRACE_ITER_SYM_ADDR)
+		ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
+	return ret;
+}
+
+static void print_lat_help_header(struct seq_file *m)
+{
+	seq_puts(m, "#                _------=> CPU#            \n");
+	seq_puts(m, "#               / _-----=> irqs-off        \n");
+	seq_puts(m, "#              | / _----=> need-resched    \n");
+	seq_puts(m, "#              || / _---=> hardirq/softirq \n");
+	seq_puts(m, "#              ||| / _--=> preempt-depth   \n");
+	seq_puts(m, "#              |||| /                      \n");
+	seq_puts(m, "#              |||||     delay             \n");
+	seq_puts(m, "#  cmd     pid ||||| time  |   caller      \n");
+	seq_puts(m, "#     \\   /    |||||   \\   |   /           \n");
+}
+
+static void print_func_help_header(struct seq_file *m)
+{
+	seq_puts(m, "#           TASK-PID   CPU#    TIMESTAMP  FUNCTION\n");
+	seq_puts(m, "#              | |      |          |         |\n");
+}
+
+
+static void
+print_trace_header(struct seq_file *m, struct trace_iterator *iter)
+{
+	unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
+	struct trace_array *tr = iter->tr;
+	struct trace_array_cpu *data = tr->data[tr->cpu];
+	struct tracer *type = current_trace;
+	unsigned long total   = 0;
+	unsigned long entries = 0;
+	int cpu;
+	const char *name = "preemption";
+
+	if (type)
+		name = type->name;
+
+	for_each_tracing_cpu(cpu) {
+		if (head_page(tr->data[cpu])) {
+			total += tr->data[cpu]->trace_idx;
+			if (tr->data[cpu]->trace_idx > tr->entries)
+				entries += tr->entries;
+			else
+				entries += tr->data[cpu]->trace_idx;
+		}
+	}
+
+	seq_printf(m, "%s latency trace v1.1.5 on %s\n",
+		   name, UTS_RELEASE);
+	seq_puts(m, "-----------------------------------"
+		 "---------------------------------\n");
+	seq_printf(m, " latency: %lu us, #%lu/%lu, CPU#%d |"
+		   " (M:%s VP:%d, KP:%d, SP:%d HP:%d",
+		   nsecs_to_usecs(data->saved_latency),
+		   entries,
+		   total,
+		   tr->cpu,
+#if defined(CONFIG_PREEMPT_NONE)
+		   "server",
+#elif defined(CONFIG_PREEMPT_VOLUNTARY)
+		   "desktop",
+#elif defined(CONFIG_PREEMPT_DESKTOP)
+		   "preempt",
+#else
+		   "unknown",
+#endif
+		   /* These are reserved for later use */
+		   0, 0, 0, 0);
+#ifdef CONFIG_SMP
+	seq_printf(m, " #P:%d)\n", num_online_cpus());
+#else
+	seq_puts(m, ")\n");
+#endif
+	seq_puts(m, "    -----------------\n");
+	seq_printf(m, "    | task: %.16s-%d "
+		   "(uid:%d nice:%ld policy:%ld rt_prio:%ld)\n",
+		   data->comm, data->pid, data->uid, data->nice,
+		   data->policy, data->rt_priority);
+	seq_puts(m, "    -----------------\n");
+
+	if (data->critical_start) {
+		seq_puts(m, " => started at: ");
+		seq_print_ip_sym(&iter->seq, data->critical_start, sym_flags);
+		trace_print_seq(m, &iter->seq);
+		seq_puts(m, "\n => ended at:   ");
+		seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
+		trace_print_seq(m, &iter->seq);
+		seq_puts(m, "\n");
+	}
+
+	seq_puts(m, "\n");
+}
+
+static void
+lat_print_generic(struct trace_seq *s, struct trace_entry *entry, int cpu)
+{
+	int hardirq, softirq;
+	char *comm;
+
+	comm = trace_find_cmdline(entry->pid);
+
+	trace_seq_printf(s, "%8.8s-%-5d ", comm, entry->pid);
+	trace_seq_printf(s, "%d", cpu);
+	trace_seq_printf(s, "%c%c",
+			(entry->flags & TRACE_FLAG_IRQS_OFF) ? 'd' : '.',
+			((entry->flags & TRACE_FLAG_NEED_RESCHED) ? 'N' : '.'));
+
+	hardirq = entry->flags & TRACE_FLAG_HARDIRQ;
+	softirq = entry->flags & TRACE_FLAG_SOFTIRQ;
+	if (hardirq && softirq) {
+		trace_seq_putc(s, 'H');
+	} else {
+		if (hardirq) {
+			trace_seq_putc(s, 'h');
+		} else {
+			if (softirq)
+				trace_seq_putc(s, 's');
+			else
+				trace_seq_putc(s, '.');
+		}
+	}
+
+	if (entry->preempt_count)
+		trace_seq_printf(s, "%x", entry->preempt_count);
+	else
+		trace_seq_puts(s, ".");
+}
+
+unsigned long preempt_mark_thresh = 100;
+
+static void
+lat_print_timestamp(struct trace_seq *s, unsigned long long abs_usecs,
+		    unsigned long rel_usecs)
+{
+	trace_seq_printf(s, " %4lldus", abs_usecs);
+	if (rel_usecs > preempt_mark_thresh)
+		trace_seq_puts(s, "!: ");
+	else if (rel_usecs > 1)
+		trace_seq_puts(s, "+: ");
+	else
+		trace_seq_puts(s, " : ");
+}
+
+static const char state_to_char[] = TASK_STATE_TO_CHAR_STR;
+
+static int
+print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
+{
+	struct trace_seq *s = &iter->seq;
+	unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
+	struct trace_entry *next_entry = find_next_entry(iter, NULL);
+	unsigned long verbose = (trace_flags & TRACE_ITER_VERBOSE);
+	struct trace_entry *entry = iter->ent;
+	unsigned long abs_usecs;
+	unsigned long rel_usecs;
+	char *comm;
+	int S, T;
+	int i;
+	unsigned state;
+
+	if (!next_entry)
+		next_entry = entry;
+	rel_usecs = ns2usecs(next_entry->t - entry->t);
+	abs_usecs = ns2usecs(entry->t - iter->tr->time_start);
+
+	if (verbose) {
+		comm = trace_find_cmdline(entry->pid);
+		trace_seq_printf(s, "%16s %5d %d %d %08x %08x [%08lx]"
+				 " %ld.%03ldms (+%ld.%03ldms): ",
+				 comm,
+				 entry->pid, cpu, entry->flags,
+				 entry->preempt_count, trace_idx,
+				 ns2usecs(entry->t),
+				 abs_usecs/1000,
+				 abs_usecs % 1000, rel_usecs/1000,
+				 rel_usecs % 1000);
+	} else {
+		lat_print_generic(s, entry, cpu);
+		lat_print_timestamp(s, abs_usecs, rel_usecs);
+	}
+	switch (entry->type) {
+	case TRACE_FN:
+		seq_print_ip_sym(s, entry->fn.ip, sym_flags);
+		trace_seq_puts(s, " (");
+		if (kretprobed(entry->fn.parent_ip))
+			trace_seq_puts(s, KRETPROBE_MSG);
+		else
+			seq_print_ip_sym(s, entry->fn.parent_ip, sym_flags);
+		trace_seq_puts(s, ")\n");
+		break;
+	case TRACE_CTX:
+	case TRACE_WAKE:
+		T = entry->ctx.next_state < sizeof(state_to_char) ?
+			state_to_char[entry->ctx.next_state] : 'X';
+
+		state = entry->ctx.prev_state ? __ffs(entry->ctx.prev_state) + 1 : 0;
+		S = state < sizeof(state_to_char) - 1 ? state_to_char[state] : 'X';
+		comm = trace_find_cmdline(entry->ctx.next_pid);
+		trace_seq_printf(s, " %5d:%3d:%c %s %5d:%3d:%c %s\n",
+				 entry->ctx.prev_pid,
+				 entry->ctx.prev_prio,
+				 S, entry->type == TRACE_CTX ? "==>" : "  +",
+				 entry->ctx.next_pid,
+				 entry->ctx.next_prio,
+				 T, comm);
+		break;
+	case TRACE_SPECIAL:
+		trace_seq_printf(s, "# %ld %ld %ld\n",
+				 entry->special.arg1,
+				 entry->special.arg2,
+				 entry->special.arg3);
+		break;
+	case TRACE_STACK:
+		for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
+			if (i)
+				trace_seq_puts(s, " <= ");
+			seq_print_ip_sym(s, entry->stack.caller[i], sym_flags);
+		}
+		trace_seq_puts(s, "\n");
+		break;
+	default:
+		trace_seq_printf(s, "Unknown type %d\n", entry->type);
+	}
+	return 1;
+}
+
+static int print_trace_fmt(struct trace_iterator *iter)
+{
+	struct trace_seq *s = &iter->seq;
+	unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
+	struct trace_entry *entry;
+	unsigned long usec_rem;
+	unsigned long long t;
+	unsigned long secs;
+	char *comm;
+	int ret;
+	int S, T;
+	int i;
+
+	entry = iter->ent;
+
+	comm = trace_find_cmdline(iter->ent->pid);
+
+	t = ns2usecs(entry->t);
+	usec_rem = do_div(t, 1000000ULL);
+	secs = (unsigned long)t;
+
+	ret = trace_seq_printf(s, "%16s-%-5d ", comm, entry->pid);
+	if (!ret)
+		return 0;
+	ret = trace_seq_printf(s, "[%02d] ", iter->cpu);
+	if (!ret)
+		return 0;
+	ret = trace_seq_printf(s, "%5lu.%06lu: ", secs, usec_rem);
+	if (!ret)
+		return 0;
+
+	switch (entry->type) {
+	case TRACE_FN:
+		ret = seq_print_ip_sym(s, entry->fn.ip, sym_flags);
+		if (!ret)
+			return 0;
+		if ((sym_flags & TRACE_ITER_PRINT_PARENT) &&
+						entry->fn.parent_ip) {
+			ret = trace_seq_printf(s, " <-");
+			if (!ret)
+				return 0;
+			if (kretprobed(entry->fn.parent_ip))
+				ret = trace_seq_puts(s, KRETPROBE_MSG);
+			else
+				ret = seq_print_ip_sym(s, entry->fn.parent_ip,
+						       sym_flags);
+			if (!ret)
+				return 0;
+		}
+		ret = trace_seq_printf(s, "\n");
+		if (!ret)
+			return 0;
+		break;
+	case TRACE_CTX:
+	case TRACE_WAKE:
+		S = entry->ctx.prev_state < sizeof(state_to_char) ?
+			state_to_char[entry->ctx.prev_state] : 'X';
+		T = entry->ctx.next_state < sizeof(state_to_char) ?
+			state_to_char[entry->ctx.next_state] : 'X';
+		ret = trace_seq_printf(s, " %5d:%3d:%c %s %5d:%3d:%c\n",
+				       entry->ctx.prev_pid,
+				       entry->ctx.prev_prio,
+				       S,
+				       entry->type == TRACE_CTX ? "==>" : "  +",
+				       entry->ctx.next_pid,
+				       entry->ctx.next_prio,
+				       T);
+		if (!ret)
+			return 0;
+		break;
+	case TRACE_SPECIAL:
+		ret = trace_seq_printf(s, "# %ld %ld %ld\n",
+				 entry->special.arg1,
+				 entry->special.arg2,
+				 entry->special.arg3);
+		if (!ret)
+			return 0;
+		break;
+	case TRACE_STACK:
+		for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
+			if (i) {
+				ret = trace_seq_puts(s, " <= ");
+				if (!ret)
+					return 0;
+			}
+			ret = seq_print_ip_sym(s, entry->stack.caller[i],
+					       sym_flags);
+			if (!ret)
+				return 0;
+		}
+		ret = trace_seq_puts(s, "\n");
+		if (!ret)
+			return 0;
+		break;
+	}
+	return 1;
+}
+
+static int print_raw_fmt(struct trace_iterator *iter)
+{
+	struct trace_seq *s = &iter->seq;
+	struct trace_entry *entry;
+	int ret;
+	int S, T;
+
+	entry = iter->ent;
+
+	ret = trace_seq_printf(s, "%d %d %llu ",
+		entry->pid, iter->cpu, entry->t);
+	if (!ret)
+		return 0;
+
+	switch (entry->type) {
+	case TRACE_FN:
+		ret = trace_seq_printf(s, "%x %x\n",
+					entry->fn.ip, entry->fn.parent_ip);
+		if (!ret)
+			return 0;
+		break;
+	case TRACE_CTX:
+	case TRACE_WAKE:
+		S = entry->ctx.prev_state < sizeof(state_to_char) ?
+			state_to_char[entry->ctx.prev_state] : 'X';
+		T = entry->ctx.next_state < sizeof(state_to_char) ?
+			state_to_char[entry->ctx.next_state] : 'X';
+		if (entry->type == TRACE_WAKE)
+			S = '+';
+		ret = trace_seq_printf(s, "%d %d %c %d %d %c\n",
+				       entry->ctx.prev_pid,
+				       entry->ctx.prev_prio,
+				       S,
+				       entry->ctx.next_pid,
+				       entry->ctx.next_prio,
+				       T);
+		if (!ret)
+			return 0;
+		break;
+	case TRACE_SPECIAL:
+	case TRACE_STACK:
+		ret = trace_seq_printf(s, "# %ld %ld %ld\n",
+				 entry->special.arg1,
+				 entry->special.arg2,
+				 entry->special.arg3);
+		if (!ret)
+			return 0;
+		break;
+	}
+	return 1;
+}
+
+#define SEQ_PUT_FIELD_RET(s, x)				\
+do {							\
+	if (!trace_seq_putmem(s, &(x), sizeof(x)))	\
+		return 0;				\
+} while (0)
+
+#define SEQ_PUT_HEX_FIELD_RET(s, x)			\
+do {							\
+	if (!trace_seq_putmem_hex(s, &(x), sizeof(x)))	\
+		return 0;				\
+} while (0)
+
+static int print_hex_fmt(struct trace_iterator *iter)
+{
+	struct trace_seq *s = &iter->seq;
+	unsigned char newline = '\n';
+	struct trace_entry *entry;
+	int S, T;
+
+	entry = iter->ent;
+
+	SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
+	SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
+	SEQ_PUT_HEX_FIELD_RET(s, entry->t);
+
+	switch (entry->type) {
+	case TRACE_FN:
+		SEQ_PUT_HEX_FIELD_RET(s, entry->fn.ip);
+		SEQ_PUT_HEX_FIELD_RET(s, entry->fn.parent_ip);
+		break;
+	case TRACE_CTX:
+	case TRACE_WAKE:
+		S = entry->ctx.prev_state < sizeof(state_to_char) ?
+			state_to_char[entry->ctx.prev_state] : 'X';
+		T = entry->ctx.next_state < sizeof(state_to_char) ?
+			state_to_char[entry->ctx.next_state] : 'X';
+		if (entry->type == TRACE_WAKE)
+			S = '+';
+		SEQ_PUT_HEX_FIELD_RET(s, entry->ctx.prev_pid);
+		SEQ_PUT_HEX_FIELD_RET(s, entry->ctx.prev_prio);
+		SEQ_PUT_HEX_FIELD_RET(s, S);
+		SEQ_PUT_HEX_FIELD_RET(s, entry->ctx.next_pid);
+		SEQ_PUT_HEX_FIELD_RET(s, entry->ctx.next_prio);
+		SEQ_PUT_HEX_FIELD_RET(s, entry->fn.parent_ip);
+		SEQ_PUT_HEX_FIELD_RET(s, T);
+		break;
+	case TRACE_SPECIAL:
+	case TRACE_STACK:
+		SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg1);
+		SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg2);
+		SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg3);
+		break;
+	}
+	SEQ_PUT_FIELD_RET(s, newline);
+
+	return 1;
+}
+
+static int print_bin_fmt(struct trace_iterator *iter)
+{
+	struct trace_seq *s = &iter->seq;
+	struct trace_entry *entry;
+
+	entry = iter->ent;
+
+	SEQ_PUT_FIELD_RET(s, entry->pid);
+	SEQ_PUT_FIELD_RET(s, entry->cpu);
+	SEQ_PUT_FIELD_RET(s, entry->t);
+
+	switch (entry->type) {
+	case TRACE_FN:
+		SEQ_PUT_FIELD_RET(s, entry->fn.ip);
+		SEQ_PUT_FIELD_RET(s, entry->fn.parent_ip);
+		break;
+	case TRACE_CTX:
+		SEQ_PUT_FIELD_RET(s, entry->ctx.prev_pid);
+		SEQ_PUT_FIELD_RET(s, entry->ctx.prev_prio);
+		SEQ_PUT_FIELD_RET(s, entry->ctx.prev_state);
+		SEQ_PUT_FIELD_RET(s, entry->ctx.next_pid);
+		SEQ_PUT_FIELD_RET(s, entry->ctx.next_prio);
+		SEQ_PUT_FIELD_RET(s, entry->ctx.next_state);
+		break;
+	case TRACE_SPECIAL:
+	case TRACE_STACK:
+		SEQ_PUT_FIELD_RET(s, entry->special.arg1);
+		SEQ_PUT_FIELD_RET(s, entry->special.arg2);
+		SEQ_PUT_FIELD_RET(s, entry->special.arg3);
+		break;
+	}
+	return 1;
+}
+
+static int trace_empty(struct trace_iterator *iter)
+{
+	struct trace_array_cpu *data;
+	int cpu;
+
+	for_each_tracing_cpu(cpu) {
+		data = iter->tr->data[cpu];
+
+		if (head_page(data) && data->trace_idx &&
+		    (data->trace_tail != data->trace_head ||
+		     data->trace_tail_idx != data->trace_head_idx))
+			return 0;
+	}
+	return 1;
+}
+
+static int print_trace_line(struct trace_iterator *iter)
+{
+	if (iter->trace && iter->trace->print_line)
+		return iter->trace->print_line(iter);
+
+	if (trace_flags & TRACE_ITER_BIN)
+		return print_bin_fmt(iter);
+
+	if (trace_flags & TRACE_ITER_HEX)
+		return print_hex_fmt(iter);
+
+	if (trace_flags & TRACE_ITER_RAW)
+		return print_raw_fmt(iter);
+
+	if (iter->iter_flags & TRACE_FILE_LAT_FMT)
+		return print_lat_fmt(iter, iter->idx, iter->cpu);
+
+	return print_trace_fmt(iter);
+}
+
+static int s_show(struct seq_file *m, void *v)
+{
+	struct trace_iterator *iter = v;
+
+	if (iter->ent == NULL) {
+		if (iter->tr) {
+			seq_printf(m, "# tracer: %s\n", iter->trace->name);
+			seq_puts(m, "#\n");
+		}
+		if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
+			/* print nothing if the buffers are empty */
+			if (trace_empty(iter))
+				return 0;
+			print_trace_header(m, iter);
+			if (!(trace_flags & TRACE_ITER_VERBOSE))
+				print_lat_help_header(m);
+		} else {
+			if (!(trace_flags & TRACE_ITER_VERBOSE))
+				print_func_help_header(m);
+		}
+	} else {
+		print_trace_line(iter);
+		trace_print_seq(m, &iter->seq);
+	}
+
+	return 0;
+}
+
+static struct seq_operations tracer_seq_ops = {
+	.start		= s_start,
+	.next		= s_next,
+	.stop		= s_stop,
+	.show		= s_show,
+};
+
+static struct trace_iterator *
+__tracing_open(struct inode *inode, struct file *file, int *ret)
+{
+	struct trace_iterator *iter;
+
+	if (tracing_disabled) {
+		*ret = -ENODEV;
+		return NULL;
+	}
+
+	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
+	if (!iter) {
+		*ret = -ENOMEM;
+		goto out;
+	}
+
+	mutex_lock(&trace_types_lock);
+	if (current_trace && current_trace->print_max)
+		iter->tr = &max_tr;
+	else
+		iter->tr = inode->i_private;
+	iter->trace = current_trace;
+	iter->pos = -1;
+
+	/* TODO stop tracer */
+	*ret = seq_open(file, &tracer_seq_ops);
+	if (!*ret) {
+		struct seq_file *m = file->private_data;
+		m->private = iter;
+
+		/* stop the trace while dumping */
+		if (iter->tr->ctrl)
+			tracer_enabled = 0;
+
+		if (iter->trace && iter->trace->open)
+			iter->trace->open(iter);
+	} else {
+		kfree(iter);
+		iter = NULL;
+	}
+	mutex_unlock(&trace_types_lock);
+
+ out:
+	return iter;
+}
+
+int tracing_open_generic(struct inode *inode, struct file *filp)
+{
+	if (tracing_disabled)
+		return -ENODEV;
+
+	filp->private_data = inode->i_private;
+	return 0;
+}
+
+int tracing_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *m = (struct seq_file *)file->private_data;
+	struct trace_iterator *iter = m->private;
+
+	mutex_lock(&trace_types_lock);
+	if (iter->trace && iter->trace->close)
+		iter->trace->close(iter);
+
+	/* reenable tracing if it was previously enabled */
+	if (iter->tr->ctrl)
+		tracer_enabled = 1;
+	mutex_unlock(&trace_types_lock);
+
+	seq_release(inode, file);
+	kfree(iter);
+	return 0;
+}
+
+static int tracing_open(struct inode *inode, struct file *file)
+{
+	int ret;
+
+	__tracing_open(inode, file, &ret);
+
+	return ret;
+}
+
+static int tracing_lt_open(struct inode *inode, struct file *file)
+{
+	struct trace_iterator *iter;
+	int ret;
+
+	iter = __tracing_open(inode, file, &ret);
+
+	if (!ret)
+		iter->iter_flags |= TRACE_FILE_LAT_FMT;
+
+	return ret;
+}
+
+
+static void *
+t_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct tracer *t = m->private;
+
+	(*pos)++;
+
+	if (t)
+		t = t->next;
+
+	m->private = t;
+
+	return t;
+}
+
+static void *t_start(struct seq_file *m, loff_t *pos)
+{
+	struct tracer *t = m->private;
+	loff_t l = 0;
+
+	mutex_lock(&trace_types_lock);
+	for (; t && l < *pos; t = t_next(m, t, &l))
+		;
+
+	return t;
+}
+
+static void t_stop(struct seq_file *m, void *p)
+{
+	mutex_unlock(&trace_types_lock);
+}
+
+static int t_show(struct seq_file *m, void *v)
+{
+	struct tracer *t = v;
+
+	if (!t)
+		return 0;
+
+	seq_printf(m, "%s", t->name);
+	if (t->next)
+		seq_putc(m, ' ');
+	else
+		seq_putc(m, '\n');
+
+	return 0;
+}
+
+static struct seq_operations show_traces_seq_ops = {
+	.start		= t_start,
+	.next		= t_next,
+	.stop		= t_stop,
+	.show		= t_show,
+};
+
+static int show_traces_open(struct inode *inode, struct file *file)
+{
+	int ret;
+
+	if (tracing_disabled)
+		return -ENODEV;
+
+	ret = seq_open(file, &show_traces_seq_ops);
+	if (!ret) {
+		struct seq_file *m = file->private_data;
+		m->private = trace_types;
+	}
+
+	return ret;
+}
+
+static struct file_operations tracing_fops = {
+	.open		= tracing_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= tracing_release,
+};
+
+static struct file_operations tracing_lt_fops = {
+	.open		= tracing_lt_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= tracing_release,
+};
+
+static struct file_operations show_traces_fops = {
+	.open		= show_traces_open,
+	.read		= seq_read,
+	.release	= seq_release,
+};
+
+/*
+ * Only trace on a CPU if the bitmask is set:
+ */
+static cpumask_t tracing_cpumask = CPU_MASK_ALL;
+
+/*
+ * When tracing/tracing_cpu_mask is modified then this holds
+ * the new bitmask we are about to install:
+ */
+static cpumask_t tracing_cpumask_new;
+
+/*
+ * The tracer itself will not take this lock, but still we want
+ * to provide a consistent cpumask to user-space:
+ */
+static DEFINE_MUTEX(tracing_cpumask_update_lock);
+
+/*
+ * Temporary storage for the character representation of the
+ * CPU bitmask (and one more byte for the newline):
+ */
+static char mask_str[NR_CPUS + 1];
+
+static ssize_t
+tracing_cpumask_read(struct file *filp, char __user *ubuf,
+		     size_t count, loff_t *ppos)
+{
+	int len;
+
+	mutex_lock(&tracing_cpumask_update_lock);
+
+	len = cpumask_scnprintf(mask_str, count, tracing_cpumask);
+	if (count - len < 2) {
+		count = -EINVAL;
+		goto out_err;
+	}
+	len += sprintf(mask_str + len, "\n");
+	count = simple_read_from_buffer(ubuf, count, ppos, mask_str, NR_CPUS+1);
+
+out_err:
+	mutex_unlock(&tracing_cpumask_update_lock);
+
+	return count;
+}
+
+static ssize_t
+tracing_cpumask_write(struct file *filp, const char __user *ubuf,
+		      size_t count, loff_t *ppos)
+{
+	int err, cpu;
+
+	mutex_lock(&tracing_cpumask_update_lock);
+	err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
+	if (err)
+		goto err_unlock;
+
+	raw_local_irq_disable();
+	__raw_spin_lock(&ftrace_max_lock);
+	for_each_tracing_cpu(cpu) {
+		/*
+		 * Increase/decrease the disabled counter if we are
+		 * about to flip a bit in the cpumask:
+		 */
+		if (cpu_isset(cpu, tracing_cpumask) &&
+				!cpu_isset(cpu, tracing_cpumask_new)) {
+			atomic_inc(&global_trace.data[cpu]->disabled);
+		}
+		if (!cpu_isset(cpu, tracing_cpumask) &&
+				cpu_isset(cpu, tracing_cpumask_new)) {
+			atomic_dec(&global_trace.data[cpu]->disabled);
+		}
+	}
+	__raw_spin_unlock(&ftrace_max_lock);
+	raw_local_irq_enable();
+
+	tracing_cpumask = tracing_cpumask_new;
+
+	mutex_unlock(&tracing_cpumask_update_lock);
+
+	return count;
+
+err_unlock:
+	mutex_unlock(&tracing_cpumask_update_lock);
+
+	return err;
+}
+
+static struct file_operations tracing_cpumask_fops = {
+	.open		= tracing_open_generic,
+	.read		= tracing_cpumask_read,
+	.write		= tracing_cpumask_write,
+};
+
+static ssize_t
+tracing_iter_ctrl_read(struct file *filp, char __user *ubuf,
+		       size_t cnt, loff_t *ppos)
+{
+	char *buf;
+	int r = 0;
+	int len = 0;
+	int i;
+
+	/* calulate max size */
+	for (i = 0; trace_options[i]; i++) {
+		len += strlen(trace_options[i]);
+		len += 3; /* "no" and space */
+	}
+
+	/* +2 for \n and \0 */
+	buf = kmalloc(len + 2, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	for (i = 0; trace_options[i]; i++) {
+		if (trace_flags & (1 << i))
+			r += sprintf(buf + r, "%s ", trace_options[i]);
+		else
+			r += sprintf(buf + r, "no%s ", trace_options[i]);
+	}
+
+	r += sprintf(buf + r, "\n");
+	WARN_ON(r >= len + 2);
+
+	r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+
+	kfree(buf);
+
+	return r;
+}
+
+static ssize_t
+tracing_iter_ctrl_write(struct file *filp, const char __user *ubuf,
+			size_t cnt, loff_t *ppos)
+{
+	char buf[64];
+	char *cmp = buf;
+	int neg = 0;
+	int i;
+
+	if (cnt >= sizeof(buf))
+		return -EINVAL;
+
+	if (copy_from_user(&buf, ubuf, cnt))
+		return -EFAULT;
+
+	buf[cnt] = 0;
+
+	if (strncmp(buf, "no", 2) == 0) {
+		neg = 1;
+		cmp += 2;
+	}
+
+	for (i = 0; trace_options[i]; i++) {
+		int len = strlen(trace_options[i]);
+
+		if (strncmp(cmp, trace_options[i], len) == 0) {
+			if (neg)
+				trace_flags &= ~(1 << i);
+			else
+				trace_flags |= (1 << i);
+			break;
+		}
+	}
+	/*
+	 * If no option could be set, return an error:
+	 */
+	if (!trace_options[i])
+		return -EINVAL;
+
+	filp->f_pos += cnt;
+
+	return cnt;
+}
+
+static struct file_operations tracing_iter_fops = {
+	.open		= tracing_open_generic,
+	.read		= tracing_iter_ctrl_read,
+	.write		= tracing_iter_ctrl_write,
+};
+
+static const char readme_msg[] =
+	"tracing mini-HOWTO:\n\n"
+	"# mkdir /debug\n"
+	"# mount -t debugfs nodev /debug\n\n"
+	"# cat /debug/tracing/available_tracers\n"
+	"wakeup preemptirqsoff preemptoff irqsoff ftrace sched_switch none\n\n"
+	"# cat /debug/tracing/current_tracer\n"
+	"none\n"
+	"# echo sched_switch > /debug/tracing/current_tracer\n"
+	"# cat /debug/tracing/current_tracer\n"
+	"sched_switch\n"
+	"# cat /debug/tracing/iter_ctrl\n"
+	"noprint-parent nosym-offset nosym-addr noverbose\n"
+	"# echo print-parent > /debug/tracing/iter_ctrl\n"
+	"# echo 1 > /debug/tracing/tracing_enabled\n"
+	"# cat /debug/tracing/trace > /tmp/trace.txt\n"
+	"echo 0 > /debug/tracing/tracing_enabled\n"
+;
+
+static ssize_t
+tracing_readme_read(struct file *filp, char __user *ubuf,
+		       size_t cnt, loff_t *ppos)
+{
+	return simple_read_from_buffer(ubuf, cnt, ppos,
+					readme_msg, strlen(readme_msg));
+}
+
+static struct file_operations tracing_readme_fops = {
+	.open		= tracing_open_generic,
+	.read		= tracing_readme_read,
+};
+
+static ssize_t
+tracing_ctrl_read(struct file *filp, char __user *ubuf,
+		  size_t cnt, loff_t *ppos)
+{
+	struct trace_array *tr = filp->private_data;
+	char buf[64];
+	int r;
+
+	r = sprintf(buf, "%ld\n", tr->ctrl);
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t
+tracing_ctrl_write(struct file *filp, const char __user *ubuf,
+		   size_t cnt, loff_t *ppos)
+{
+	struct trace_array *tr = filp->private_data;
+	char buf[64];
+	long val;
+	int ret;
+
+	if (cnt >= sizeof(buf))
+		return -EINVAL;
+
+	if (copy_from_user(&buf, ubuf, cnt))
+		return -EFAULT;
+
+	buf[cnt] = 0;
+
+	ret = strict_strtoul(buf, 10, &val);
+	if (ret < 0)
+		return ret;
+
+	val = !!val;
+
+	mutex_lock(&trace_types_lock);
+	if (tr->ctrl ^ val) {
+		if (val)
+			tracer_enabled = 1;
+		else
+			tracer_enabled = 0;
+
+		tr->ctrl = val;
+
+		if (current_trace && current_trace->ctrl_update)
+			current_trace->ctrl_update(tr);
+	}
+	mutex_unlock(&trace_types_lock);
+
+	filp->f_pos += cnt;
+
+	return cnt;
+}
+
+static ssize_t
+tracing_set_trace_read(struct file *filp, char __user *ubuf,
+		       size_t cnt, loff_t *ppos)
+{
+	char buf[max_tracer_type_len+2];
+	int r;
+
+	mutex_lock(&trace_types_lock);
+	if (current_trace)
+		r = sprintf(buf, "%s\n", current_trace->name);
+	else
+		r = sprintf(buf, "\n");
+	mutex_unlock(&trace_types_lock);
+
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t
+tracing_set_trace_write(struct file *filp, const char __user *ubuf,
+			size_t cnt, loff_t *ppos)
+{
+	struct trace_array *tr = &global_trace;
+	struct tracer *t;
+	char buf[max_tracer_type_len+1];
+	int i;
+
+	if (cnt > max_tracer_type_len)
+		cnt = max_tracer_type_len;
+
+	if (copy_from_user(&buf, ubuf, cnt))
+		return -EFAULT;
+
+	buf[cnt] = 0;
+
+	/* strip ending whitespace. */
+	for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)
+		buf[i] = 0;
+
+	mutex_lock(&trace_types_lock);
+	for (t = trace_types; t; t = t->next) {
+		if (strcmp(t->name, buf) == 0)
+			break;
+	}
+	if (!t || t == current_trace)
+		goto out;
+
+	if (current_trace && current_trace->reset)
+		current_trace->reset(tr);
+
+	current_trace = t;
+	if (t->init)
+		t->init(tr);
+
+ out:
+	mutex_unlock(&trace_types_lock);
+
+	filp->f_pos += cnt;
+
+	return cnt;
+}
+
+static ssize_t
+tracing_max_lat_read(struct file *filp, char __user *ubuf,
+		     size_t cnt, loff_t *ppos)
+{
+	unsigned long *ptr = filp->private_data;
+	char buf[64];
+	int r;
+
+	r = snprintf(buf, sizeof(buf), "%ld\n",
+		     *ptr == (unsigned long)-1 ? -1 : nsecs_to_usecs(*ptr));
+	if (r > sizeof(buf))
+		r = sizeof(buf);
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t
+tracing_max_lat_write(struct file *filp, const char __user *ubuf,
+		      size_t cnt, loff_t *ppos)
+{
+	long *ptr = filp->private_data;
+	char buf[64];
+	long val;
+	int ret;
+
+	if (cnt >= sizeof(buf))
+		return -EINVAL;
+
+	if (copy_from_user(&buf, ubuf, cnt))
+		return -EFAULT;
+
+	buf[cnt] = 0;
+
+	ret = strict_strtoul(buf, 10, &val);
+	if (ret < 0)
+		return ret;
+
+	*ptr = val * 1000;
+
+	return cnt;
+}
+
+static atomic_t tracing_reader;
+
+static int tracing_open_pipe(struct inode *inode, struct file *filp)
+{
+	struct trace_iterator *iter;
+
+	if (tracing_disabled)
+		return -ENODEV;
+
+	/* We only allow for reader of the pipe */
+	if (atomic_inc_return(&tracing_reader) != 1) {
+		atomic_dec(&tracing_reader);
+		return -EBUSY;
+	}
+
+	/* create a buffer to store the information to pass to userspace */
+	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
+	if (!iter)
+		return -ENOMEM;
+
+	mutex_lock(&trace_types_lock);
+	iter->tr = &global_trace;
+	iter->trace = current_trace;
+	filp->private_data = iter;
+
+	if (iter->trace->pipe_open)
+		iter->trace->pipe_open(iter);
+	mutex_unlock(&trace_types_lock);
+
+	return 0;
+}
+
+static int tracing_release_pipe(struct inode *inode, struct file *file)
+{
+	struct trace_iterator *iter = file->private_data;
+
+	kfree(iter);
+	atomic_dec(&tracing_reader);
+
+	return 0;
+}
+
+static unsigned int
+tracing_poll_pipe(struct file *filp, poll_table *poll_table)
+{
+	struct trace_iterator *iter = filp->private_data;
+
+	if (trace_flags & TRACE_ITER_BLOCK) {
+		/*
+		 * Always select as readable when in blocking mode
+		 */
+		return POLLIN | POLLRDNORM;
+	} else {
+		if (!trace_empty(iter))
+			return POLLIN | POLLRDNORM;
+		poll_wait(filp, &trace_wait, poll_table);
+		if (!trace_empty(iter))
+			return POLLIN | POLLRDNORM;
+
+		return 0;
+	}
+}
+
+/*
+ * Consumer reader.
+ */
+static ssize_t
+tracing_read_pipe(struct file *filp, char __user *ubuf,
+		  size_t cnt, loff_t *ppos)
+{
+	struct trace_iterator *iter = filp->private_data;
+	struct trace_array_cpu *data;
+	static cpumask_t mask;
+	unsigned long flags;
+#ifdef CONFIG_FTRACE
+	int ftrace_save;
+#endif
+	int cpu;
+	ssize_t sret;
+
+	/* return any leftover data */
+	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
+	if (sret != -EBUSY)
+		return sret;
+	sret = 0;
+
+	trace_seq_reset(&iter->seq);
+
+	mutex_lock(&trace_types_lock);
+	if (iter->trace->read) {
+		sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
+		if (sret)
+			goto out;
+	}
+
+	while (trace_empty(iter)) {
+
+		if ((filp->f_flags & O_NONBLOCK)) {
+			sret = -EAGAIN;
+			goto out;
+		}
+
+		/*
+		 * This is a make-shift waitqueue. The reason we don't use
+		 * an actual wait queue is because:
+		 *  1) we only ever have one waiter
+		 *  2) the tracing, traces all functions, we don't want
+		 *     the overhead of calling wake_up and friends
+		 *     (and tracing them too)
+		 *     Anyway, this is really very primitive wakeup.
+		 */
+		set_current_state(TASK_INTERRUPTIBLE);
+		iter->tr->waiter = current;
+
+		mutex_unlock(&trace_types_lock);
+
+		/* sleep for 100 msecs, and try again. */
+		schedule_timeout(HZ/10);
+
+		mutex_lock(&trace_types_lock);
+
+		iter->tr->waiter = NULL;
+
+		if (signal_pending(current)) {
+			sret = -EINTR;
+			goto out;
+		}
+
+		if (iter->trace != current_trace)
+			goto out;
+
+		/*
+		 * We block until we read something and tracing is disabled.
+		 * We still block if tracing is disabled, but we have never
+		 * read anything. This allows a user to cat this file, and
+		 * then enable tracing. But after we have read something,
+		 * we give an EOF when tracing is again disabled.
+		 *
+		 * iter->pos will be 0 if we haven't read anything.
+		 */
+		if (!tracer_enabled && iter->pos)
+			break;
+
+		continue;
+	}
+
+	/* stop when tracing is finished */
+	if (trace_empty(iter))
+		goto out;
+
+	if (cnt >= PAGE_SIZE)
+		cnt = PAGE_SIZE - 1;
+
+	/* reset all but tr, trace, and overruns */
+	memset(&iter->seq, 0,
+	       sizeof(struct trace_iterator) -
+	       offsetof(struct trace_iterator, seq));
+	iter->pos = -1;
+
+	/*
+	 * We need to stop all tracing on all CPUS to read the
+	 * the next buffer. This is a bit expensive, but is
+	 * not done often. We fill all what we can read,
+	 * and then release the locks again.
+	 */
+
+	cpus_clear(mask);
+	local_irq_save(flags);
+#ifdef CONFIG_FTRACE
+	ftrace_save = ftrace_enabled;
+	ftrace_enabled = 0;
+#endif
+	smp_wmb();
+	for_each_tracing_cpu(cpu) {
+		data = iter->tr->data[cpu];
+
+		if (!head_page(data) || !data->trace_idx)
+			continue;
+
+		atomic_inc(&data->disabled);
+		cpu_set(cpu, mask);
+	}
+
+	for_each_cpu_mask(cpu, mask) {
+		data = iter->tr->data[cpu];
+		__raw_spin_lock(&data->lock);
+
+		if (data->overrun > iter->last_overrun[cpu])
+			iter->overrun[cpu] +=
+				data->overrun - iter->last_overrun[cpu];
+		iter->last_overrun[cpu] = data->overrun;
+	}
+
+	while (find_next_entry_inc(iter) != NULL) {
+		int ret;
+		int len = iter->seq.len;
+
+		ret = print_trace_line(iter);
+		if (!ret) {
+			/* don't print partial lines */
+			iter->seq.len = len;
+			break;
+		}
+
+		trace_consume(iter);
+
+		if (iter->seq.len >= cnt)
+			break;
+	}
+
+	for_each_cpu_mask(cpu, mask) {
+		data = iter->tr->data[cpu];
+		__raw_spin_unlock(&data->lock);
+	}
+
+	for_each_cpu_mask(cpu, mask) {
+		data = iter->tr->data[cpu];
+		atomic_dec(&data->disabled);
+	}
+#ifdef CONFIG_FTRACE
+	ftrace_enabled = ftrace_save;
+#endif
+	local_irq_restore(flags);
+
+	/* Now copy what we have to the user */
+	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
+	if (iter->seq.readpos >= iter->seq.len)
+		trace_seq_reset(&iter->seq);
+	if (sret == -EBUSY)
+		sret = 0;
+
+out:
+	mutex_unlock(&trace_types_lock);
+
+	return sret;
+}
+
+static ssize_t
+tracing_entries_read(struct file *filp, char __user *ubuf,
+		     size_t cnt, loff_t *ppos)
+{
+	struct trace_array *tr = filp->private_data;
+	char buf[64];
+	int r;
+
+	r = sprintf(buf, "%lu\n", tr->entries);
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t
+tracing_entries_write(struct file *filp, const char __user *ubuf,
+		      size_t cnt, loff_t *ppos)
+{
+	unsigned long val;
+	char buf[64];
+	int i, ret;
+
+	if (cnt >= sizeof(buf))
+		return -EINVAL;
+
+	if (copy_from_user(&buf, ubuf, cnt))
+		return -EFAULT;
+
+	buf[cnt] = 0;
+
+	ret = strict_strtoul(buf, 10, &val);
+	if (ret < 0)
+		return ret;
+
+	/* must have at least 1 entry */
+	if (!val)
+		return -EINVAL;
+
+	mutex_lock(&trace_types_lock);
+
+	if (current_trace != &no_tracer) {
+		cnt = -EBUSY;
+		pr_info("ftrace: set current_tracer to none"
+			" before modifying buffer size\n");
+		goto out;
+	}
+
+	if (val > global_trace.entries) {
+		long pages_requested;
+		unsigned long freeable_pages;
+
+		/* make sure we have enough memory before mapping */
+		pages_requested =
+			(val + (ENTRIES_PER_PAGE-1)) / ENTRIES_PER_PAGE;
+
+		/* account for each buffer (and max_tr) */
+		pages_requested *= tracing_nr_buffers * 2;
+
+		/* Check for overflow */
+		if (pages_requested < 0) {
+			cnt = -ENOMEM;
+			goto out;
+		}
+
+		freeable_pages = determine_dirtyable_memory();
+
+		/* we only allow to request 1/4 of useable memory */
+		if (pages_requested >
+		    ((freeable_pages + tracing_pages_allocated) / 4)) {
+			cnt = -ENOMEM;
+			goto out;
+		}
+
+		while (global_trace.entries < val) {
+			if (trace_alloc_page()) {
+				cnt = -ENOMEM;
+				goto out;
+			}
+			/* double check that we don't go over the known pages */
+			if (tracing_pages_allocated > pages_requested)
+				break;
+		}
+
+	} else {
+		/* include the number of entries in val (inc of page entries) */
+		while (global_trace.entries > val + (ENTRIES_PER_PAGE - 1))
+			trace_free_page();
+	}
+
+	/* check integrity */
+	for_each_tracing_cpu(i)
+		check_pages(global_trace.data[i]);
+
+	filp->f_pos += cnt;
+
+	/* If check pages failed, return ENOMEM */
+	if (tracing_disabled)
+		cnt = -ENOMEM;
+ out:
+	max_tr.entries = global_trace.entries;
+	mutex_unlock(&trace_types_lock);
+
+	return cnt;
+}
+
+static struct file_operations tracing_max_lat_fops = {
+	.open		= tracing_open_generic,
+	.read		= tracing_max_lat_read,
+	.write		= tracing_max_lat_write,
+};
+
+static struct file_operations tracing_ctrl_fops = {
+	.open		= tracing_open_generic,
+	.read		= tracing_ctrl_read,
+	.write		= tracing_ctrl_write,
+};
+
+static struct file_operations set_tracer_fops = {
+	.open		= tracing_open_generic,
+	.read		= tracing_set_trace_read,
+	.write		= tracing_set_trace_write,
+};
+
+static struct file_operations tracing_pipe_fops = {
+	.open		= tracing_open_pipe,
+	.poll		= tracing_poll_pipe,
+	.read		= tracing_read_pipe,
+	.release	= tracing_release_pipe,
+};
+
+static struct file_operations tracing_entries_fops = {
+	.open		= tracing_open_generic,
+	.read		= tracing_entries_read,
+	.write		= tracing_entries_write,
+};
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+static ssize_t
+tracing_read_long(struct file *filp, char __user *ubuf,
+		  size_t cnt, loff_t *ppos)
+{
+	unsigned long *p = filp->private_data;
+	char buf[64];
+	int r;
+
+	r = sprintf(buf, "%ld\n", *p);
+
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static struct file_operations tracing_read_long_fops = {
+	.open		= tracing_open_generic,
+	.read		= tracing_read_long,
+};
+#endif
+
+static struct dentry *d_tracer;
+
+struct dentry *tracing_init_dentry(void)
+{
+	static int once;
+
+	if (d_tracer)
+		return d_tracer;
+
+	d_tracer = debugfs_create_dir("tracing", NULL);
+
+	if (!d_tracer && !once) {
+		once = 1;
+		pr_warning("Could not create debugfs directory 'tracing'\n");
+		return NULL;
+	}
+
+	return d_tracer;
+}
+
+#ifdef CONFIG_FTRACE_SELFTEST
+/* Let selftest have access to static functions in this file */
+#include "trace_selftest.c"
+#endif
+
+static __init void tracer_init_debugfs(void)
+{
+	struct dentry *d_tracer;
+	struct dentry *entry;
+
+	d_tracer = tracing_init_dentry();
+
+	entry = debugfs_create_file("tracing_enabled", 0644, d_tracer,
+				    &global_trace, &tracing_ctrl_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs 'tracing_enabled' entry\n");
+
+	entry = debugfs_create_file("iter_ctrl", 0644, d_tracer,
+				    NULL, &tracing_iter_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs 'iter_ctrl' entry\n");
+
+	entry = debugfs_create_file("tracing_cpumask", 0644, d_tracer,
+				    NULL, &tracing_cpumask_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs 'tracing_cpumask' entry\n");
+
+	entry = debugfs_create_file("latency_trace", 0444, d_tracer,
+				    &global_trace, &tracing_lt_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs 'latency_trace' entry\n");
+
+	entry = debugfs_create_file("trace", 0444, d_tracer,
+				    &global_trace, &tracing_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs 'trace' entry\n");
+
+	entry = debugfs_create_file("available_tracers", 0444, d_tracer,
+				    &global_trace, &show_traces_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs 'trace' entry\n");
+
+	entry = debugfs_create_file("current_tracer", 0444, d_tracer,
+				    &global_trace, &set_tracer_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs 'trace' entry\n");
+
+	entry = debugfs_create_file("tracing_max_latency", 0644, d_tracer,
+				    &tracing_max_latency,
+				    &tracing_max_lat_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'tracing_max_latency' entry\n");
+
+	entry = debugfs_create_file("tracing_thresh", 0644, d_tracer,
+				    &tracing_thresh, &tracing_max_lat_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'tracing_threash' entry\n");
+	entry = debugfs_create_file("README", 0644, d_tracer,
+				    NULL, &tracing_readme_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs 'README' entry\n");
+
+	entry = debugfs_create_file("trace_pipe", 0644, d_tracer,
+				    NULL, &tracing_pipe_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'tracing_threash' entry\n");
+
+	entry = debugfs_create_file("trace_entries", 0644, d_tracer,
+				    &global_trace, &tracing_entries_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'tracing_threash' entry\n");
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+	entry = debugfs_create_file("dyn_ftrace_total_info", 0444, d_tracer,
+				    &ftrace_update_tot_cnt,
+				    &tracing_read_long_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'dyn_ftrace_total_info' entry\n");
+#endif
+}
+
+static int trace_alloc_page(void)
+{
+	struct trace_array_cpu *data;
+	struct page *page, *tmp;
+	LIST_HEAD(pages);
+	void *array;
+	unsigned pages_allocated = 0;
+	int i;
+
+	/* first allocate a page for each CPU */
+	for_each_tracing_cpu(i) {
+		array = (void *)__get_free_page(GFP_KERNEL);
+		if (array == NULL) {
+			printk(KERN_ERR "tracer: failed to allocate page"
+			       "for trace buffer!\n");
+			goto free_pages;
+		}
+
+		pages_allocated++;
+		page = virt_to_page(array);
+		list_add(&page->lru, &pages);
+
+/* Only allocate if we are actually using the max trace */
+#ifdef CONFIG_TRACER_MAX_TRACE
+		array = (void *)__get_free_page(GFP_KERNEL);
+		if (array == NULL) {
+			printk(KERN_ERR "tracer: failed to allocate page"
+			       "for trace buffer!\n");
+			goto free_pages;
+		}
+		pages_allocated++;
+		page = virt_to_page(array);
+		list_add(&page->lru, &pages);
+#endif
+	}
+
+	/* Now that we successfully allocate a page per CPU, add them */
+	for_each_tracing_cpu(i) {
+		data = global_trace.data[i];
+		page = list_entry(pages.next, struct page, lru);
+		list_del_init(&page->lru);
+		list_add_tail(&page->lru, &data->trace_pages);
+		ClearPageLRU(page);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+		data = max_tr.data[i];
+		page = list_entry(pages.next, struct page, lru);
+		list_del_init(&page->lru);
+		list_add_tail(&page->lru, &data->trace_pages);
+		SetPageLRU(page);
+#endif
+	}
+	tracing_pages_allocated += pages_allocated;
+	global_trace.entries += ENTRIES_PER_PAGE;
+
+	return 0;
+
+ free_pages:
+	list_for_each_entry_safe(page, tmp, &pages, lru) {
+		list_del_init(&page->lru);
+		__free_page(page);
+	}
+	return -ENOMEM;
+}
+
+static int trace_free_page(void)
+{
+	struct trace_array_cpu *data;
+	struct page *page;
+	struct list_head *p;
+	int i;
+	int ret = 0;
+
+	/* free one page from each buffer */
+	for_each_tracing_cpu(i) {
+		data = global_trace.data[i];
+		p = data->trace_pages.next;
+		if (p == &data->trace_pages) {
+			/* should never happen */
+			WARN_ON(1);
+			tracing_disabled = 1;
+			ret = -1;
+			break;
+		}
+		page = list_entry(p, struct page, lru);
+		ClearPageLRU(page);
+		list_del(&page->lru);
+		tracing_pages_allocated--;
+		tracing_pages_allocated--;
+		__free_page(page);
+
+		tracing_reset(data);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+		data = max_tr.data[i];
+		p = data->trace_pages.next;
+		if (p == &data->trace_pages) {
+			/* should never happen */
+			WARN_ON(1);
+			tracing_disabled = 1;
+			ret = -1;
+			break;
+		}
+		page = list_entry(p, struct page, lru);
+		ClearPageLRU(page);
+		list_del(&page->lru);
+		__free_page(page);
+
+		tracing_reset(data);
+#endif
+	}
+	global_trace.entries -= ENTRIES_PER_PAGE;
+
+	return ret;
+}
+
+__init static int tracer_alloc_buffers(void)
+{
+	struct trace_array_cpu *data;
+	void *array;
+	struct page *page;
+	int pages = 0;
+	int ret = -ENOMEM;
+	int i;
+
+	/* TODO: make the number of buffers hot pluggable with CPUS */
+	tracing_nr_buffers = num_possible_cpus();
+	tracing_buffer_mask = cpu_possible_map;
+
+	/* Allocate the first page for all buffers */
+	for_each_tracing_cpu(i) {
+		data = global_trace.data[i] = &per_cpu(global_trace_cpu, i);
+		max_tr.data[i] = &per_cpu(max_data, i);
+
+		array = (void *)__get_free_page(GFP_KERNEL);
+		if (array == NULL) {
+			printk(KERN_ERR "tracer: failed to allocate page"
+			       "for trace buffer!\n");
+			goto free_buffers;
+		}
+
+		/* set the array to the list */
+		INIT_LIST_HEAD(&data->trace_pages);
+		page = virt_to_page(array);
+		list_add(&page->lru, &data->trace_pages);
+		/* use the LRU flag to differentiate the two buffers */
+		ClearPageLRU(page);
+
+		data->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
+		max_tr.data[i]->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
+
+/* Only allocate if we are actually using the max trace */
+#ifdef CONFIG_TRACER_MAX_TRACE
+		array = (void *)__get_free_page(GFP_KERNEL);
+		if (array == NULL) {
+			printk(KERN_ERR "tracer: failed to allocate page"
+			       "for trace buffer!\n");
+			goto free_buffers;
+		}
+
+		INIT_LIST_HEAD(&max_tr.data[i]->trace_pages);
+		page = virt_to_page(array);
+		list_add(&page->lru, &max_tr.data[i]->trace_pages);
+		SetPageLRU(page);
+#endif
+	}
+
+	/*
+	 * Since we allocate by orders of pages, we may be able to
+	 * round up a bit.
+	 */
+	global_trace.entries = ENTRIES_PER_PAGE;
+	pages++;
+
+	while (global_trace.entries < trace_nr_entries) {
+		if (trace_alloc_page())
+			break;
+		pages++;
+	}
+	max_tr.entries = global_trace.entries;
+
+	pr_info("tracer: %d pages allocated for %ld entries of %ld bytes\n",
+		pages, trace_nr_entries, (long)TRACE_ENTRY_SIZE);
+	pr_info("   actual entries %ld\n", global_trace.entries);
+
+	tracer_init_debugfs();
+
+	trace_init_cmdlines();
+
+	register_tracer(&no_tracer);
+	current_trace = &no_tracer;
+
+	/* All seems OK, enable tracing */
+	global_trace.ctrl = tracer_enabled;
+	tracing_disabled = 0;
+
+	return 0;
+
+ free_buffers:
+	for (i-- ; i >= 0; i--) {
+		struct page *page, *tmp;
+		struct trace_array_cpu *data = global_trace.data[i];
+
+		if (data) {
+			list_for_each_entry_safe(page, tmp,
+						 &data->trace_pages, lru) {
+				list_del_init(&page->lru);
+				__free_page(page);
+			}
+		}
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+		data = max_tr.data[i];
+		if (data) {
+			list_for_each_entry_safe(page, tmp,
+						 &data->trace_pages, lru) {
+				list_del_init(&page->lru);
+				__free_page(page);
+			}
+		}
+#endif
+	}
+	return ret;
+}
+fs_initcall(tracer_alloc_buffers);

kernel/trace/trace.h

@@ -0,0 +1,313 @@
+#ifndef _LINUX_KERNEL_TRACE_H
+#define _LINUX_KERNEL_TRACE_H
+
+#include <linux/fs.h>
+#include <asm/atomic.h>
+#include <linux/sched.h>
+#include <linux/clocksource.h>
+
+enum trace_type {
+	__TRACE_FIRST_TYPE = 0,
+
+	TRACE_FN,
+	TRACE_CTX,
+	TRACE_WAKE,
+	TRACE_STACK,
+	TRACE_SPECIAL,
+
+	__TRACE_LAST_TYPE
+};
+
+/*
+ * Function trace entry - function address and parent function addres:
+ */
+struct ftrace_entry {
+	unsigned long		ip;
+	unsigned long		parent_ip;
+};
+
+/*
+ * Context switch trace entry - which task (and prio) we switched from/to:
+ */
+struct ctx_switch_entry {
+	unsigned int		prev_pid;
+	unsigned char		prev_prio;
+	unsigned char		prev_state;
+	unsigned int		next_pid;
+	unsigned char		next_prio;
+	unsigned char		next_state;
+};
+
+/*
+ * Special (free-form) trace entry:
+ */
+struct special_entry {
+	unsigned long		arg1;
+	unsigned long		arg2;
+	unsigned long		arg3;
+};
+
+/*
+ * Stack-trace entry:
+ */
+
+#define FTRACE_STACK_ENTRIES	8
+
+struct stack_entry {
+	unsigned long		caller[FTRACE_STACK_ENTRIES];
+};
+
+/*
+ * The trace entry - the most basic unit of tracing. This is what
+ * is printed in the end as a single line in the trace output, such as:
+ *
+ *     bash-15816 [01]   235.197585: idle_cpu <- irq_enter
+ */
+struct trace_entry {
+	char			type;
+	char			cpu;
+	char			flags;
+	char			preempt_count;
+	int			pid;
+	cycle_t			t;
+	union {
+		struct ftrace_entry		fn;
+		struct ctx_switch_entry		ctx;
+		struct special_entry		special;
+		struct stack_entry		stack;
+	};
+};
+
+#define TRACE_ENTRY_SIZE	sizeof(struct trace_entry)
+
+/*
+ * The CPU trace array - it consists of thousands of trace entries
+ * plus some other descriptor data: (for example which task started
+ * the trace, etc.)
+ */
+struct trace_array_cpu {
+	struct list_head	trace_pages;
+	atomic_t		disabled;
+	raw_spinlock_t		lock;
+	struct lock_class_key	lock_key;
+
+	/* these fields get copied into max-trace: */
+	unsigned		trace_head_idx;
+	unsigned		trace_tail_idx;
+	void			*trace_head; /* producer */
+	void			*trace_tail; /* consumer */
+	unsigned long		trace_idx;
+	unsigned long		overrun;
+	unsigned long		saved_latency;
+	unsigned long		critical_start;
+	unsigned long		critical_end;
+	unsigned long		critical_sequence;
+	unsigned long		nice;
+	unsigned long		policy;
+	unsigned long		rt_priority;
+	cycle_t			preempt_timestamp;
+	pid_t			pid;
+	uid_t			uid;
+	char			comm[TASK_COMM_LEN];
+};
+
+struct trace_iterator;
+
+/*
+ * The trace array - an array of per-CPU trace arrays. This is the
+ * highest level data structure that individual tracers deal with.
+ * They have on/off state as well:
+ */
+struct trace_array {
+	unsigned long		entries;
+	long			ctrl;
+	int			cpu;
+	cycle_t			time_start;
+	struct task_struct	*waiter;
+	struct trace_array_cpu	*data[NR_CPUS];
+};
+
+/*
+ * A specific tracer, represented by methods that operate on a trace array:
+ */
+struct tracer {
+	const char		*name;
+	void			(*init)(struct trace_array *tr);
+	void			(*reset)(struct trace_array *tr);
+	void			(*open)(struct trace_iterator *iter);
+	void			(*pipe_open)(struct trace_iterator *iter);
+	void			(*close)(struct trace_iterator *iter);
+	void			(*start)(struct trace_iterator *iter);
+	void			(*stop)(struct trace_iterator *iter);
+	ssize_t			(*read)(struct trace_iterator *iter,
+					struct file *filp, char __user *ubuf,
+					size_t cnt, loff_t *ppos);
+	void			(*ctrl_update)(struct trace_array *tr);
+#ifdef CONFIG_FTRACE_STARTUP_TEST
+	int			(*selftest)(struct tracer *trace,
+					    struct trace_array *tr);
+#endif
+	int			(*print_line)(struct trace_iterator *iter);
+	struct tracer		*next;
+	int			print_max;
+};
+
+struct trace_seq {
+	unsigned char		buffer[PAGE_SIZE];
+	unsigned int		len;
+	unsigned int		readpos;
+};
+
+/*
+ * Trace iterator - used by printout routines who present trace
+ * results to users and which routines might sleep, etc:
+ */
+struct trace_iterator {
+	struct trace_array	*tr;
+	struct tracer		*trace;
+	void			*private;
+	long			last_overrun[NR_CPUS];
+	long			overrun[NR_CPUS];
+
+	/* The below is zeroed out in pipe_read */
+	struct trace_seq	seq;
+	struct trace_entry	*ent;
+	int			cpu;
+
+	struct trace_entry	*prev_ent;
+	int			prev_cpu;
+
+	unsigned long		iter_flags;
+	loff_t			pos;
+	unsigned long		next_idx[NR_CPUS];
+	struct list_head	*next_page[NR_CPUS];
+	unsigned		next_page_idx[NR_CPUS];
+	long			idx;
+};
+
+void tracing_reset(struct trace_array_cpu *data);
+int tracing_open_generic(struct inode *inode, struct file *filp);
+struct dentry *tracing_init_dentry(void);
+void ftrace(struct trace_array *tr,
+			    struct trace_array_cpu *data,
+			    unsigned long ip,
+			    unsigned long parent_ip,
+			    unsigned long flags);
+void tracing_sched_switch_trace(struct trace_array *tr,
+				struct trace_array_cpu *data,
+				struct task_struct *prev,
+				struct task_struct *next,
+				unsigned long flags);
+void tracing_record_cmdline(struct task_struct *tsk);
+
+void tracing_sched_wakeup_trace(struct trace_array *tr,
+				struct trace_array_cpu *data,
+				struct task_struct *wakee,
+				struct task_struct *cur,
+				unsigned long flags);
+void trace_special(struct trace_array *tr,
+		   struct trace_array_cpu *data,
+		   unsigned long arg1,
+		   unsigned long arg2,
+		   unsigned long arg3);
+void trace_function(struct trace_array *tr,
+		    struct trace_array_cpu *data,
+		    unsigned long ip,
+		    unsigned long parent_ip,
+		    unsigned long flags);
+
+void tracing_start_function_trace(void);
+void tracing_stop_function_trace(void);
+void tracing_start_cmdline_record(void);
+void tracing_stop_cmdline_record(void);
+int register_tracer(struct tracer *type);
+void unregister_tracer(struct tracer *type);
+
+extern unsigned long nsecs_to_usecs(unsigned long nsecs);
+
+extern unsigned long tracing_max_latency;
+extern unsigned long tracing_thresh;
+
+void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu);
+void update_max_tr_single(struct trace_array *tr,
+			  struct task_struct *tsk, int cpu);
+
+extern cycle_t ftrace_now(int cpu);
+
+#ifdef CONFIG_CONTEXT_SWITCH_TRACER
+typedef void
+(*tracer_switch_func_t)(void *private,
+			void *__rq,
+			struct task_struct *prev,
+			struct task_struct *next);
+
+struct tracer_switch_ops {
+	tracer_switch_func_t		func;
+	void				*private;
+	struct tracer_switch_ops	*next;
+};
+
+#endif /* CONFIG_CONTEXT_SWITCH_TRACER */
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+extern unsigned long ftrace_update_tot_cnt;
+#define DYN_FTRACE_TEST_NAME trace_selftest_dynamic_test_func
+extern int DYN_FTRACE_TEST_NAME(void);
+#endif
+
+#ifdef CONFIG_FTRACE_STARTUP_TEST
+#ifdef CONFIG_FTRACE
+extern int trace_selftest_startup_function(struct tracer *trace,
+					   struct trace_array *tr);
+#endif
+#ifdef CONFIG_IRQSOFF_TRACER
+extern int trace_selftest_startup_irqsoff(struct tracer *trace,
+					  struct trace_array *tr);
+#endif
+#ifdef CONFIG_PREEMPT_TRACER
+extern int trace_selftest_startup_preemptoff(struct tracer *trace,
+					     struct trace_array *tr);
+#endif
+#if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
+extern int trace_selftest_startup_preemptirqsoff(struct tracer *trace,
+						 struct trace_array *tr);
+#endif
+#ifdef CONFIG_SCHED_TRACER
+extern int trace_selftest_startup_wakeup(struct tracer *trace,
+					 struct trace_array *tr);
+#endif
+#ifdef CONFIG_CONTEXT_SWITCH_TRACER
+extern int trace_selftest_startup_sched_switch(struct tracer *trace,
+					       struct trace_array *tr);
+#endif
+#endif /* CONFIG_FTRACE_STARTUP_TEST */
+
+extern void *head_page(struct trace_array_cpu *data);
+extern int trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
+extern ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
+				 size_t cnt);
+extern long ns2usecs(cycle_t nsec);
+
+extern unsigned long trace_flags;
+
+/*
+ * trace_iterator_flags is an enumeration that defines bit
+ * positions into trace_flags that controls the output.
+ *
+ * NOTE: These bits must match the trace_options array in
+ *       trace.c.
+ */
+enum trace_iterator_flags {
+	TRACE_ITER_PRINT_PARENT		= 0x01,
+	TRACE_ITER_SYM_OFFSET		= 0x02,
+	TRACE_ITER_SYM_ADDR		= 0x04,
+	TRACE_ITER_VERBOSE		= 0x08,
+	TRACE_ITER_RAW			= 0x10,
+	TRACE_ITER_HEX			= 0x20,
+	TRACE_ITER_BIN			= 0x40,
+	TRACE_ITER_BLOCK		= 0x80,
+	TRACE_ITER_STACKTRACE		= 0x100,
+	TRACE_ITER_SCHED_TREE		= 0x200,
+};
+
+#endif /* _LINUX_KERNEL_TRACE_H */

kernel/trace/trace_functions.c

@@ -0,0 +1,78 @@
+/*
+ * ring buffer based function tracer
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
+ *
+ * Based on code from the latency_tracer, that is:
+ *
+ *  Copyright (C) 2004-2006 Ingo Molnar
+ *  Copyright (C) 2004 William Lee Irwin III
+ */
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <linux/fs.h>
+
+#include "trace.h"
+
+static void function_reset(struct trace_array *tr)
+{
+	int cpu;
+
+	tr->time_start = ftrace_now(tr->cpu);
+
+	for_each_online_cpu(cpu)
+		tracing_reset(tr->data[cpu]);
+}
+
+static void start_function_trace(struct trace_array *tr)
+{
+	function_reset(tr);
+	tracing_start_cmdline_record();
+	tracing_start_function_trace();
+}
+
+static void stop_function_trace(struct trace_array *tr)
+{
+	tracing_stop_function_trace();
+	tracing_stop_cmdline_record();
+}
+
+static void function_trace_init(struct trace_array *tr)
+{
+	if (tr->ctrl)
+		start_function_trace(tr);
+}
+
+static void function_trace_reset(struct trace_array *tr)
+{
+	if (tr->ctrl)
+		stop_function_trace(tr);
+}
+
+static void function_trace_ctrl_update(struct trace_array *tr)
+{
+	if (tr->ctrl)
+		start_function_trace(tr);
+	else
+		stop_function_trace(tr);
+}
+
+static struct tracer function_trace __read_mostly =
+{
+	.name	     = "ftrace",
+	.init	     = function_trace_init,
+	.reset	     = function_trace_reset,
+	.ctrl_update = function_trace_ctrl_update,
+#ifdef CONFIG_FTRACE_SELFTEST
+	.selftest    = trace_selftest_startup_function,
+#endif
+};
+
+static __init int init_function_trace(void)
+{
+	return register_tracer(&function_trace);
+}
+
+device_initcall(init_function_trace);

kernel/trace/trace_irqsoff.c

@@ -0,0 +1,486 @@
+/*
+ * trace irqs off criticall timings
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
+ *
+ * From code in the latency_tracer, that is:
+ *
+ *  Copyright (C) 2004-2006 Ingo Molnar
+ *  Copyright (C) 2004 William Lee Irwin III
+ */
+#include <linux/kallsyms.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <linux/ftrace.h>
+#include <linux/fs.h>
+
+#include "trace.h"
+
+static struct trace_array		*irqsoff_trace __read_mostly;
+static int				tracer_enabled __read_mostly;
+
+static DEFINE_PER_CPU(int, tracing_cpu);
+
+static DEFINE_SPINLOCK(max_trace_lock);
+
+enum {
+	TRACER_IRQS_OFF		= (1 << 1),
+	TRACER_PREEMPT_OFF	= (1 << 2),
+};
+
+static int trace_type __read_mostly;
+
+#ifdef CONFIG_PREEMPT_TRACER
+static inline int
+preempt_trace(void)
+{
+	return ((trace_type & TRACER_PREEMPT_OFF) && preempt_count());
+}
+#else
+# define preempt_trace() (0)
+#endif
+
+#ifdef CONFIG_IRQSOFF_TRACER
+static inline int
+irq_trace(void)
+{
+	return ((trace_type & TRACER_IRQS_OFF) &&
+		irqs_disabled());
+}
+#else
+# define irq_trace() (0)
+#endif
+
+/*
+ * Sequence count - we record it when starting a measurement and
+ * skip the latency if the sequence has changed - some other section
+ * did a maximum and could disturb our measurement with serial console
+ * printouts, etc. Truly coinciding maximum latencies should be rare
+ * and what happens together happens separately as well, so this doesnt
+ * decrease the validity of the maximum found:
+ */
+static __cacheline_aligned_in_smp	unsigned long max_sequence;
+
+#ifdef CONFIG_FTRACE
+/*
+ * irqsoff uses its own tracer function to keep the overhead down:
+ */
+static void
+irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip)
+{
+	struct trace_array *tr = irqsoff_trace;
+	struct trace_array_cpu *data;
+	unsigned long flags;
+	long disabled;
+	int cpu;
+
+	/*
+	 * Does not matter if we preempt. We test the flags
+	 * afterward, to see if irqs are disabled or not.
+	 * If we preempt and get a false positive, the flags
+	 * test will fail.
+	 */
+	cpu = raw_smp_processor_id();
+	if (likely(!per_cpu(tracing_cpu, cpu)))
+		return;
+
+	local_save_flags(flags);
+	/* slight chance to get a false positive on tracing_cpu */
+	if (!irqs_disabled_flags(flags))
+		return;
+
+	data = tr->data[cpu];
+	disabled = atomic_inc_return(&data->disabled);
+
+	if (likely(disabled == 1))
+		trace_function(tr, data, ip, parent_ip, flags);
+
+	atomic_dec(&data->disabled);
+}
+
+static struct ftrace_ops trace_ops __read_mostly =
+{
+	.func = irqsoff_tracer_call,
+};
+#endif /* CONFIG_FTRACE */
+
+/*
+ * Should this new latency be reported/recorded?
+ */
+static int report_latency(cycle_t delta)
+{
+	if (tracing_thresh) {
+		if (delta < tracing_thresh)
+			return 0;
+	} else {
+		if (delta <= tracing_max_latency)
+			return 0;
+	}
+	return 1;
+}
+
+static void
+check_critical_timing(struct trace_array *tr,
+		      struct trace_array_cpu *data,
+		      unsigned long parent_ip,
+		      int cpu)
+{
+	unsigned long latency, t0, t1;
+	cycle_t T0, T1, delta;
+	unsigned long flags;
+
+	/*
+	 * usecs conversion is slow so we try to delay the conversion
+	 * as long as possible:
+	 */
+	T0 = data->preempt_timestamp;
+	T1 = ftrace_now(cpu);
+	delta = T1-T0;
+
+	local_save_flags(flags);
+
+	if (!report_latency(delta))
+		goto out;
+
+	spin_lock_irqsave(&max_trace_lock, flags);
+
+	/* check if we are still the max latency */
+	if (!report_latency(delta))
+		goto out_unlock;
+
+	trace_function(tr, data, CALLER_ADDR0, parent_ip, flags);
+
+	latency = nsecs_to_usecs(delta);
+
+	if (data->critical_sequence != max_sequence)
+		goto out_unlock;
+
+	tracing_max_latency = delta;
+	t0 = nsecs_to_usecs(T0);
+	t1 = nsecs_to_usecs(T1);
+
+	data->critical_end = parent_ip;
+
+	update_max_tr_single(tr, current, cpu);
+
+	max_sequence++;
+
+out_unlock:
+	spin_unlock_irqrestore(&max_trace_lock, flags);
+
+out:
+	data->critical_sequence = max_sequence;
+	data->preempt_timestamp = ftrace_now(cpu);
+	tracing_reset(data);
+	trace_function(tr, data, CALLER_ADDR0, parent_ip, flags);
+}
+
+static inline void
+start_critical_timing(unsigned long ip, unsigned long parent_ip)
+{
+	int cpu;
+	struct trace_array *tr = irqsoff_trace;
+	struct trace_array_cpu *data;
+	unsigned long flags;
+
+	if (likely(!tracer_enabled))
+		return;
+
+	cpu = raw_smp_processor_id();
+
+	if (per_cpu(tracing_cpu, cpu))
+		return;
+
+	data = tr->data[cpu];
+
+	if (unlikely(!data) || atomic_read(&data->disabled))
+		return;
+
+	atomic_inc(&data->disabled);
+
+	data->critical_sequence = max_sequence;
+	data->preempt_timestamp = ftrace_now(cpu);
+	data->critical_start = parent_ip ? : ip;
+	tracing_reset(data);
+
+	local_save_flags(flags);
+
+	trace_function(tr, data, ip, parent_ip, flags);
+
+	per_cpu(tracing_cpu, cpu) = 1;
+
+	atomic_dec(&data->disabled);
+}
+
+static inline void
+stop_critical_timing(unsigned long ip, unsigned long parent_ip)
+{
+	int cpu;
+	struct trace_array *tr = irqsoff_trace;
+	struct trace_array_cpu *data;
+	unsigned long flags;
+
+	cpu = raw_smp_processor_id();
+	/* Always clear the tracing cpu on stopping the trace */
+	if (unlikely(per_cpu(tracing_cpu, cpu)))
+		per_cpu(tracing_cpu, cpu) = 0;
+	else
+		return;
+
+	if (!tracer_enabled)
+		return;
+
+	data = tr->data[cpu];
+
+	if (unlikely(!data) || unlikely(!head_page(data)) ||
+	    !data->critical_start || atomic_read(&data->disabled))
+		return;
+
+	atomic_inc(&data->disabled);
+
+	local_save_flags(flags);
+	trace_function(tr, data, ip, parent_ip, flags);
+	check_critical_timing(tr, data, parent_ip ? : ip, cpu);
+	data->critical_start = 0;
+	atomic_dec(&data->disabled);
+}
+
+/* start and stop critical timings used to for stoppage (in idle) */
+void start_critical_timings(void)
+{
+	if (preempt_trace() || irq_trace())
+		start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+}
+
+void stop_critical_timings(void)
+{
+	if (preempt_trace() || irq_trace())
+		stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+}
+
+#ifdef CONFIG_IRQSOFF_TRACER
+#ifdef CONFIG_PROVE_LOCKING
+void time_hardirqs_on(unsigned long a0, unsigned long a1)
+{
+	if (!preempt_trace() && irq_trace())
+		stop_critical_timing(a0, a1);
+}
+
+void time_hardirqs_off(unsigned long a0, unsigned long a1)
+{
+	if (!preempt_trace() && irq_trace())
+		start_critical_timing(a0, a1);
+}
+
+#else /* !CONFIG_PROVE_LOCKING */
+
+/*
+ * Stubs:
+ */
+
+void early_boot_irqs_off(void)
+{
+}
+
+void early_boot_irqs_on(void)
+{
+}
+
+void trace_softirqs_on(unsigned long ip)
+{
+}
+
+void trace_softirqs_off(unsigned long ip)
+{
+}
+
+inline void print_irqtrace_events(struct task_struct *curr)
+{
+}
+
+/*
+ * We are only interested in hardirq on/off events:
+ */
+void trace_hardirqs_on(void)
+{
+	if (!preempt_trace() && irq_trace())
+		stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+}
+EXPORT_SYMBOL(trace_hardirqs_on);
+
+void trace_hardirqs_off(void)
+{
+	if (!preempt_trace() && irq_trace())
+		start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
+}
+EXPORT_SYMBOL(trace_hardirqs_off);
+
+void trace_hardirqs_on_caller(unsigned long caller_addr)
+{
+	if (!preempt_trace() && irq_trace())
+		stop_critical_timing(CALLER_ADDR0, caller_addr);
+}
+EXPORT_SYMBOL(trace_hardirqs_on_caller);
+
+void trace_hardirqs_off_caller(unsigned long caller_addr)
+{
+	if (!preempt_trace() && irq_trace())
+		start_critical_timing(CALLER_ADDR0, caller_addr);
+}
+EXPORT_SYMBOL(trace_hardirqs_off_caller);
+
+#endif /* CONFIG_PROVE_LOCKING */
+#endif /*  CONFIG_IRQSOFF_TRACER */
+
+#ifdef CONFIG_PREEMPT_TRACER
+void trace_preempt_on(unsigned long a0, unsigned long a1)
+{
+	stop_critical_timing(a0, a1);
+}
+
+void trace_preempt_off(unsigned long a0, unsigned long a1)
+{
+	start_critical_timing(a0, a1);
+}
+#endif /* CONFIG_PREEMPT_TRACER */
+
+static void start_irqsoff_tracer(struct trace_array *tr)
+{
+	register_ftrace_function(&trace_ops);
+	tracer_enabled = 1;
+}
+
+static void stop_irqsoff_tracer(struct trace_array *tr)
+{
+	tracer_enabled = 0;
+	unregister_ftrace_function(&trace_ops);
+}
+
+static void __irqsoff_tracer_init(struct trace_array *tr)
+{
+	irqsoff_trace = tr;
+	/* make sure that the tracer is visible */
+	smp_wmb();
+
+	if (tr->ctrl)
+		start_irqsoff_tracer(tr);
+}
+
+static void irqsoff_tracer_reset(struct trace_array *tr)
+{
+	if (tr->ctrl)
+		stop_irqsoff_tracer(tr);
+}
+
+static void irqsoff_tracer_ctrl_update(struct trace_array *tr)
+{
+	if (tr->ctrl)
+		start_irqsoff_tracer(tr);
+	else
+		stop_irqsoff_tracer(tr);
+}
+
+static void irqsoff_tracer_open(struct trace_iterator *iter)
+{
+	/* stop the trace while dumping */
+	if (iter->tr->ctrl)
+		stop_irqsoff_tracer(iter->tr);
+}
+
+static void irqsoff_tracer_close(struct trace_iterator *iter)
+{
+	if (iter->tr->ctrl)
+		start_irqsoff_tracer(iter->tr);
+}
+
+#ifdef CONFIG_IRQSOFF_TRACER
+static void irqsoff_tracer_init(struct trace_array *tr)
+{
+	trace_type = TRACER_IRQS_OFF;
+
+	__irqsoff_tracer_init(tr);
+}
+static struct tracer irqsoff_tracer __read_mostly =
+{
+	.name		= "irqsoff",
+	.init		= irqsoff_tracer_init,
+	.reset		= irqsoff_tracer_reset,
+	.open		= irqsoff_tracer_open,
+	.close		= irqsoff_tracer_close,
+	.ctrl_update	= irqsoff_tracer_ctrl_update,
+	.print_max	= 1,
+#ifdef CONFIG_FTRACE_SELFTEST
+	.selftest    = trace_selftest_startup_irqsoff,
+#endif
+};
+# define register_irqsoff(trace) register_tracer(&trace)
+#else
+# define register_irqsoff(trace) do { } while (0)
+#endif
+
+#ifdef CONFIG_PREEMPT_TRACER
+static void preemptoff_tracer_init(struct trace_array *tr)
+{
+	trace_type = TRACER_PREEMPT_OFF;
+
+	__irqsoff_tracer_init(tr);
+}
+
+static struct tracer preemptoff_tracer __read_mostly =
+{
+	.name		= "preemptoff",
+	.init		= preemptoff_tracer_init,
+	.reset		= irqsoff_tracer_reset,
+	.open		= irqsoff_tracer_open,
+	.close		= irqsoff_tracer_close,
+	.ctrl_update	= irqsoff_tracer_ctrl_update,
+	.print_max	= 1,
+#ifdef CONFIG_FTRACE_SELFTEST
+	.selftest    = trace_selftest_startup_preemptoff,
+#endif
+};
+# define register_preemptoff(trace) register_tracer(&trace)
+#else
+# define register_preemptoff(trace) do { } while (0)
+#endif
+
+#if defined(CONFIG_IRQSOFF_TRACER) && \
+	defined(CONFIG_PREEMPT_TRACER)
+
+static void preemptirqsoff_tracer_init(struct trace_array *tr)
+{
+	trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
+
+	__irqsoff_tracer_init(tr);
+}
+
+static struct tracer preemptirqsoff_tracer __read_mostly =
+{
+	.name		= "preemptirqsoff",
+	.init		= preemptirqsoff_tracer_init,
+	.reset		= irqsoff_tracer_reset,
+	.open		= irqsoff_tracer_open,
+	.close		= irqsoff_tracer_close,
+	.ctrl_update	= irqsoff_tracer_ctrl_update,
+	.print_max	= 1,
+#ifdef CONFIG_FTRACE_SELFTEST
+	.selftest    = trace_selftest_startup_preemptirqsoff,
+#endif
+};
+
+# define register_preemptirqsoff(trace) register_tracer(&trace)
+#else
+# define register_preemptirqsoff(trace) do { } while (0)
+#endif
+
+__init static int init_irqsoff_tracer(void)
+{
+	register_irqsoff(irqsoff_tracer);
+	register_preemptoff(preemptoff_tracer);
+	register_preemptirqsoff(preemptirqsoff_tracer);
+
+	return 0;
+}
+device_initcall(init_irqsoff_tracer);

kernel/trace/trace_sched_switch.c

@@ -0,0 +1,286 @@
+/*
+ * trace context switch
+ *
+ * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
+ *
+ */
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <linux/kallsyms.h>
+#include <linux/uaccess.h>
+#include <linux/marker.h>
+#include <linux/ftrace.h>
+
+#include "trace.h"
+
+static struct trace_array	*ctx_trace;
+static int __read_mostly	tracer_enabled;
+static atomic_t			sched_ref;
+
+static void
+sched_switch_func(void *private, void *__rq, struct task_struct *prev,
+			struct task_struct *next)
+{
+	struct trace_array **ptr = private;
+	struct trace_array *tr = *ptr;
+	struct trace_array_cpu *data;
+	unsigned long flags;
+	long disabled;
+	int cpu;
+
+	tracing_record_cmdline(prev);
+	tracing_record_cmdline(next);
+
+	if (!tracer_enabled)
+		return;
+
+	local_irq_save(flags);
+	cpu = raw_smp_processor_id();
+	data = tr->data[cpu];
+	disabled = atomic_inc_return(&data->disabled);
+
+	if (likely(disabled == 1))
+		tracing_sched_switch_trace(tr, data, prev, next, flags);
+
+	atomic_dec(&data->disabled);
+	local_irq_restore(flags);
+}
+
+static notrace void
+sched_switch_callback(void *probe_data, void *call_data,
+		      const char *format, va_list *args)
+{
+	struct task_struct *prev;
+	struct task_struct *next;
+	struct rq *__rq;
+
+	if (!atomic_read(&sched_ref))
+		return;
+
+	/* skip prev_pid %d next_pid %d prev_state %ld */
+	(void)va_arg(*args, int);
+	(void)va_arg(*args, int);
+	(void)va_arg(*args, long);
+	__rq = va_arg(*args, typeof(__rq));
+	prev = va_arg(*args, typeof(prev));
+	next = va_arg(*args, typeof(next));
+
+	/*
+	 * If tracer_switch_func only points to the local
+	 * switch func, it still needs the ptr passed to it.
+	 */
+	sched_switch_func(probe_data, __rq, prev, next);
+}
+
+static void
+wakeup_func(void *private, void *__rq, struct task_struct *wakee, struct
+			task_struct *curr)
+{
+	struct trace_array **ptr = private;
+	struct trace_array *tr = *ptr;
+	struct trace_array_cpu *data;
+	unsigned long flags;
+	long disabled;
+	int cpu;
+
+	if (!tracer_enabled)
+		return;
+
+	tracing_record_cmdline(curr);
+
+	local_irq_save(flags);
+	cpu = raw_smp_processor_id();
+	data = tr->data[cpu];
+	disabled = atomic_inc_return(&data->disabled);
+
+	if (likely(disabled == 1))
+		tracing_sched_wakeup_trace(tr, data, wakee, curr, flags);
+
+	atomic_dec(&data->disabled);
+	local_irq_restore(flags);
+}
+
+static notrace void
+wake_up_callback(void *probe_data, void *call_data,
+		 const char *format, va_list *args)
+{
+	struct task_struct *curr;
+	struct task_struct *task;
+	struct rq *__rq;
+
+	if (likely(!tracer_enabled))
+		return;
+
+	/* Skip pid %d state %ld */
+	(void)va_arg(*args, int);
+	(void)va_arg(*args, long);
+	/* now get the meat: "rq %p task %p rq->curr %p" */
+	__rq = va_arg(*args, typeof(__rq));
+	task = va_arg(*args, typeof(task));
+	curr = va_arg(*args, typeof(curr));
+
+	tracing_record_cmdline(task);
+	tracing_record_cmdline(curr);
+
+	wakeup_func(probe_data, __rq, task, curr);
+}
+
+static void sched_switch_reset(struct trace_array *tr)
+{
+	int cpu;
+
+	tr->time_start = ftrace_now(tr->cpu);
+
+	for_each_online_cpu(cpu)
+		tracing_reset(tr->data[cpu]);
+}
+
+static int tracing_sched_register(void)
+{
+	int ret;
+
+	ret = marker_probe_register("kernel_sched_wakeup",
+			"pid %d state %ld ## rq %p task %p rq->curr %p",
+			wake_up_callback,
+			&ctx_trace);
+	if (ret) {
+		pr_info("wakeup trace: Couldn't add marker"
+			" probe to kernel_sched_wakeup\n");
+		return ret;
+	}
+
+	ret = marker_probe_register("kernel_sched_wakeup_new",
+			"pid %d state %ld ## rq %p task %p rq->curr %p",
+			wake_up_callback,
+			&ctx_trace);
+	if (ret) {
+		pr_info("wakeup trace: Couldn't add marker"
+			" probe to kernel_sched_wakeup_new\n");
+		goto fail_deprobe;
+	}
+
+	ret = marker_probe_register("kernel_sched_schedule",
+		"prev_pid %d next_pid %d prev_state %ld "
+		"## rq %p prev %p next %p",
+		sched_switch_callback,
+		&ctx_trace);
+	if (ret) {
+		pr_info("sched trace: Couldn't add marker"
+			" probe to kernel_sched_schedule\n");
+		goto fail_deprobe_wake_new;
+	}
+
+	return ret;
+fail_deprobe_wake_new:
+	marker_probe_unregister("kernel_sched_wakeup_new",
+				wake_up_callback,
+				&ctx_trace);
+fail_deprobe:
+	marker_probe_unregister("kernel_sched_wakeup",
+				wake_up_callback,
+				&ctx_trace);
+	return ret;
+}
+
+static void tracing_sched_unregister(void)
+{
+	marker_probe_unregister("kernel_sched_schedule",
+				sched_switch_callback,
+				&ctx_trace);
+	marker_probe_unregister("kernel_sched_wakeup_new",
+				wake_up_callback,
+				&ctx_trace);
+	marker_probe_unregister("kernel_sched_wakeup",
+				wake_up_callback,
+				&ctx_trace);
+}
+
+static void tracing_start_sched_switch(void)
+{
+	long ref;
+
+	ref = atomic_inc_return(&sched_ref);
+	if (ref == 1)
+		tracing_sched_register();
+}
+
+static void tracing_stop_sched_switch(void)
+{
+	long ref;
+
+	ref = atomic_dec_and_test(&sched_ref);
+	if (ref)
+		tracing_sched_unregister();
+}
+
+void tracing_start_cmdline_record(void)
+{
+	tracing_start_sched_switch();
+}
+
+void tracing_stop_cmdline_record(void)
+{
+	tracing_stop_sched_switch();
+}
+
+static void start_sched_trace(struct trace_array *tr)
+{
+	sched_switch_reset(tr);
+	tracer_enabled = 1;
+	tracing_start_cmdline_record();
+}
+
+static void stop_sched_trace(struct trace_array *tr)
+{
+	tracing_stop_cmdline_record();
+	tracer_enabled = 0;
+}
+
+static void sched_switch_trace_init(struct trace_array *tr)
+{
+	ctx_trace = tr;
+
+	if (tr->ctrl)
+		start_sched_trace(tr);
+}
+
+static void sched_switch_trace_reset(struct trace_array *tr)
+{
+	if (tr->ctrl)
+		stop_sched_trace(tr);
+}
+
+static void sched_switch_trace_ctrl_update(struct trace_array *tr)
+{
+	/* When starting a new trace, reset the buffers */
+	if (tr->ctrl)
+		start_sched_trace(tr);
+	else
+		stop_sched_trace(tr);
+}
+
+static struct tracer sched_switch_trace __read_mostly =
+{
+	.name		= "sched_switch",
+	.init		= sched_switch_trace_init,
+	.reset		= sched_switch_trace_reset,
+	.ctrl_update	= sched_switch_trace_ctrl_update,
+#ifdef CONFIG_FTRACE_SELFTEST
+	.selftest    = trace_selftest_startup_sched_switch,
+#endif
+};
+
+__init static int init_sched_switch_trace(void)
+{
+	int ret = 0;
+
+	if (atomic_read(&sched_ref))
+		ret = tracing_sched_register();
+	if (ret) {
+		pr_info("error registering scheduler trace\n");
+		return ret;
+	}
+	return register_tracer(&sched_switch_trace);
+}
+device_initcall(init_sched_switch_trace);

kernel/trace/trace_sched_wakeup.c

@@ -0,0 +1,447 @@
+/*
+ * trace task wakeup timings
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
+ *
+ * Based on code from the latency_tracer, that is:
+ *
+ *  Copyright (C) 2004-2006 Ingo Molnar
+ *  Copyright (C) 2004 William Lee Irwin III
+ */
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <linux/kallsyms.h>
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <linux/marker.h>
+
+#include "trace.h"
+
+static struct trace_array	*wakeup_trace;
+static int __read_mostly	tracer_enabled;
+
+static struct task_struct	*wakeup_task;
+static int			wakeup_cpu;
+static unsigned			wakeup_prio = -1;
+
+static DEFINE_SPINLOCK(wakeup_lock);
+
+static void __wakeup_reset(struct trace_array *tr);
+
+#ifdef CONFIG_FTRACE
+/*
+ * irqsoff uses its own tracer function to keep the overhead down:
+ */
+static void
+wakeup_tracer_call(unsigned long ip, unsigned long parent_ip)
+{
+	struct trace_array *tr = wakeup_trace;
+	struct trace_array_cpu *data;
+	unsigned long flags;
+	long disabled;
+	int resched;
+	int cpu;
+
+	if (likely(!wakeup_task))
+		return;
+
+	resched = need_resched();
+	preempt_disable_notrace();
+
+	cpu = raw_smp_processor_id();
+	data = tr->data[cpu];
+	disabled = atomic_inc_return(&data->disabled);
+	if (unlikely(disabled != 1))
+		goto out;
+
+	spin_lock_irqsave(&wakeup_lock, flags);
+
+	if (unlikely(!wakeup_task))
+		goto unlock;
+
+	/*
+	 * The task can't disappear because it needs to
+	 * wake up first, and we have the wakeup_lock.
+	 */
+	if (task_cpu(wakeup_task) != cpu)
+		goto unlock;
+
+	trace_function(tr, data, ip, parent_ip, flags);
+
+ unlock:
+	spin_unlock_irqrestore(&wakeup_lock, flags);
+
+ out:
+	atomic_dec(&data->disabled);
+
+	/*
+	 * To prevent recursion from the scheduler, if the
+	 * resched flag was set before we entered, then
+	 * don't reschedule.
+	 */
+	if (resched)
+		preempt_enable_no_resched_notrace();
+	else
+		preempt_enable_notrace();
+}
+
+static struct ftrace_ops trace_ops __read_mostly =
+{
+	.func = wakeup_tracer_call,
+};
+#endif /* CONFIG_FTRACE */
+
+/*
+ * Should this new latency be reported/recorded?
+ */
+static int report_latency(cycle_t delta)
+{
+	if (tracing_thresh) {
+		if (delta < tracing_thresh)
+			return 0;
+	} else {
+		if (delta <= tracing_max_latency)
+			return 0;
+	}
+	return 1;
+}
+
+static void notrace
+wakeup_sched_switch(void *private, void *rq, struct task_struct *prev,
+	struct task_struct *next)
+{
+	unsigned long latency = 0, t0 = 0, t1 = 0;
+	struct trace_array **ptr = private;
+	struct trace_array *tr = *ptr;
+	struct trace_array_cpu *data;
+	cycle_t T0, T1, delta;
+	unsigned long flags;
+	long disabled;
+	int cpu;
+
+	if (unlikely(!tracer_enabled))
+		return;
+
+	/*
+	 * When we start a new trace, we set wakeup_task to NULL
+	 * and then set tracer_enabled = 1. We want to make sure
+	 * that another CPU does not see the tracer_enabled = 1
+	 * and the wakeup_task with an older task, that might
+	 * actually be the same as next.
+	 */
+	smp_rmb();
+
+	if (next != wakeup_task)
+		return;
+
+	/* The task we are waiting for is waking up */
+	data = tr->data[wakeup_cpu];
+
+	/* disable local data, not wakeup_cpu data */
+	cpu = raw_smp_processor_id();
+	disabled = atomic_inc_return(&tr->data[cpu]->disabled);
+	if (likely(disabled != 1))
+		goto out;
+
+	spin_lock_irqsave(&wakeup_lock, flags);
+
+	/* We could race with grabbing wakeup_lock */
+	if (unlikely(!tracer_enabled || next != wakeup_task))
+		goto out_unlock;
+
+	trace_function(tr, data, CALLER_ADDR1, CALLER_ADDR2, flags);
+
+	/*
+	 * usecs conversion is slow so we try to delay the conversion
+	 * as long as possible:
+	 */
+	T0 = data->preempt_timestamp;
+	T1 = ftrace_now(cpu);
+	delta = T1-T0;
+
+	if (!report_latency(delta))
+		goto out_unlock;
+
+	latency = nsecs_to_usecs(delta);
+
+	tracing_max_latency = delta;
+	t0 = nsecs_to_usecs(T0);
+	t1 = nsecs_to_usecs(T1);
+
+	update_max_tr(tr, wakeup_task, wakeup_cpu);
+
+out_unlock:
+	__wakeup_reset(tr);
+	spin_unlock_irqrestore(&wakeup_lock, flags);
+out:
+	atomic_dec(&tr->data[cpu]->disabled);
+}
+
+static notrace void
+sched_switch_callback(void *probe_data, void *call_data,
+		      const char *format, va_list *args)
+{
+	struct task_struct *prev;
+	struct task_struct *next;
+	struct rq *__rq;
+
+	/* skip prev_pid %d next_pid %d prev_state %ld */
+	(void)va_arg(*args, int);
+	(void)va_arg(*args, int);
+	(void)va_arg(*args, long);
+	__rq = va_arg(*args, typeof(__rq));
+	prev = va_arg(*args, typeof(prev));
+	next = va_arg(*args, typeof(next));
+
+	tracing_record_cmdline(prev);
+
+	/*
+	 * If tracer_switch_func only points to the local
+	 * switch func, it still needs the ptr passed to it.
+	 */
+	wakeup_sched_switch(probe_data, __rq, prev, next);
+}
+
+static void __wakeup_reset(struct trace_array *tr)
+{
+	struct trace_array_cpu *data;
+	int cpu;
+
+	assert_spin_locked(&wakeup_lock);
+
+	for_each_possible_cpu(cpu) {
+		data = tr->data[cpu];
+		tracing_reset(data);
+	}
+
+	wakeup_cpu = -1;
+	wakeup_prio = -1;
+
+	if (wakeup_task)
+		put_task_struct(wakeup_task);
+
+	wakeup_task = NULL;
+}
+
+static void wakeup_reset(struct trace_array *tr)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&wakeup_lock, flags);
+	__wakeup_reset(tr);
+	spin_unlock_irqrestore(&wakeup_lock, flags);
+}
+
+static void
+wakeup_check_start(struct trace_array *tr, struct task_struct *p,
+		   struct task_struct *curr)
+{
+	int cpu = smp_processor_id();
+	unsigned long flags;
+	long disabled;
+
+	if (likely(!rt_task(p)) ||
+			p->prio >= wakeup_prio ||
+			p->prio >= curr->prio)
+		return;
+
+	disabled = atomic_inc_return(&tr->data[cpu]->disabled);
+	if (unlikely(disabled != 1))
+		goto out;
+
+	/* interrupts should be off from try_to_wake_up */
+	spin_lock(&wakeup_lock);
+
+	/* check for races. */
+	if (!tracer_enabled || p->prio >= wakeup_prio)
+		goto out_locked;
+
+	/* reset the trace */
+	__wakeup_reset(tr);
+
+	wakeup_cpu = task_cpu(p);
+	wakeup_prio = p->prio;
+
+	wakeup_task = p;
+	get_task_struct(wakeup_task);
+
+	local_save_flags(flags);
+
+	tr->data[wakeup_cpu]->preempt_timestamp = ftrace_now(cpu);
+	trace_function(tr, tr->data[wakeup_cpu],
+		       CALLER_ADDR1, CALLER_ADDR2, flags);
+
+out_locked:
+	spin_unlock(&wakeup_lock);
+out:
+	atomic_dec(&tr->data[cpu]->disabled);
+}
+
+static notrace void
+wake_up_callback(void *probe_data, void *call_data,
+		 const char *format, va_list *args)
+{
+	struct trace_array **ptr = probe_data;
+	struct trace_array *tr = *ptr;
+	struct task_struct *curr;
+	struct task_struct *task;
+	struct rq *__rq;
+
+	if (likely(!tracer_enabled))
+		return;
+
+	/* Skip pid %d state %ld */
+	(void)va_arg(*args, int);
+	(void)va_arg(*args, long);
+	/* now get the meat: "rq %p task %p rq->curr %p" */
+	__rq = va_arg(*args, typeof(__rq));
+	task = va_arg(*args, typeof(task));
+	curr = va_arg(*args, typeof(curr));
+
+	tracing_record_cmdline(task);
+	tracing_record_cmdline(curr);
+
+	wakeup_check_start(tr, task, curr);
+}
+
+static void start_wakeup_tracer(struct trace_array *tr)
+{
+	int ret;
+
+	ret = marker_probe_register("kernel_sched_wakeup",
+			"pid %d state %ld ## rq %p task %p rq->curr %p",
+			wake_up_callback,
+			&wakeup_trace);
+	if (ret) {
+		pr_info("wakeup trace: Couldn't add marker"
+			" probe to kernel_sched_wakeup\n");
+		return;
+	}
+
+	ret = marker_probe_register("kernel_sched_wakeup_new",
+			"pid %d state %ld ## rq %p task %p rq->curr %p",
+			wake_up_callback,
+			&wakeup_trace);
+	if (ret) {
+		pr_info("wakeup trace: Couldn't add marker"
+			" probe to kernel_sched_wakeup_new\n");
+		goto fail_deprobe;
+	}
+
+	ret = marker_probe_register("kernel_sched_schedule",
+		"prev_pid %d next_pid %d prev_state %ld "
+		"## rq %p prev %p next %p",
+		sched_switch_callback,
+		&wakeup_trace);
+	if (ret) {
+		pr_info("sched trace: Couldn't add marker"
+			" probe to kernel_sched_schedule\n");
+		goto fail_deprobe_wake_new;
+	}
+
+	wakeup_reset(tr);
+
+	/*
+	 * Don't let the tracer_enabled = 1 show up before
+	 * the wakeup_task is reset. This may be overkill since
+	 * wakeup_reset does a spin_unlock after setting the
+	 * wakeup_task to NULL, but I want to be safe.
+	 * This is a slow path anyway.
+	 */
+	smp_wmb();
+
+	tracer_enabled = 1;
+	register_ftrace_function(&trace_ops);
+
+	return;
+fail_deprobe_wake_new:
+	marker_probe_unregister("kernel_sched_wakeup_new",
+				wake_up_callback,
+				&wakeup_trace);
+fail_deprobe:
+	marker_probe_unregister("kernel_sched_wakeup",
+				wake_up_callback,
+				&wakeup_trace);
+}
+
+static void stop_wakeup_tracer(struct trace_array *tr)
+{
+	tracer_enabled = 0;
+	unregister_ftrace_function(&trace_ops);
+	marker_probe_unregister("kernel_sched_schedule",
+				sched_switch_callback,
+				&wakeup_trace);
+	marker_probe_unregister("kernel_sched_wakeup_new",
+				wake_up_callback,
+				&wakeup_trace);
+	marker_probe_unregister("kernel_sched_wakeup",
+				wake_up_callback,
+				&wakeup_trace);
+}
+
+static void wakeup_tracer_init(struct trace_array *tr)
+{
+	wakeup_trace = tr;
+
+	if (tr->ctrl)
+		start_wakeup_tracer(tr);
+}
+
+static void wakeup_tracer_reset(struct trace_array *tr)
+{
+	if (tr->ctrl) {
+		stop_wakeup_tracer(tr);
+		/* make sure we put back any tasks we are tracing */
+		wakeup_reset(tr);
+	}
+}
+
+static void wakeup_tracer_ctrl_update(struct trace_array *tr)
+{
+	if (tr->ctrl)
+		start_wakeup_tracer(tr);
+	else
+		stop_wakeup_tracer(tr);
+}
+
+static void wakeup_tracer_open(struct trace_iterator *iter)
+{
+	/* stop the trace while dumping */
+	if (iter->tr->ctrl)
+		stop_wakeup_tracer(iter->tr);
+}
+
+static void wakeup_tracer_close(struct trace_iterator *iter)
+{
+	/* forget about any processes we were recording */
+	if (iter->tr->ctrl)
+		start_wakeup_tracer(iter->tr);
+}
+
+static struct tracer wakeup_tracer __read_mostly =
+{
+	.name		= "wakeup",
+	.init		= wakeup_tracer_init,
+	.reset		= wakeup_tracer_reset,
+	.open		= wakeup_tracer_open,
+	.close		= wakeup_tracer_close,
+	.ctrl_update	= wakeup_tracer_ctrl_update,
+	.print_max	= 1,
+#ifdef CONFIG_FTRACE_SELFTEST
+	.selftest    = trace_selftest_startup_wakeup,
+#endif
+};
+
+__init static int init_wakeup_tracer(void)
+{
+	int ret;
+
+	ret = register_tracer(&wakeup_tracer);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+device_initcall(init_wakeup_tracer);

kernel/trace/trace_selftest.c

@@ -0,0 +1,540 @@
+/* Include in trace.c */
+
+#include <linux/kthread.h>
+#include <linux/delay.h>
+
+static inline int trace_valid_entry(struct trace_entry *entry)
+{
+	switch (entry->type) {
+	case TRACE_FN:
+	case TRACE_CTX:
+	case TRACE_WAKE:
+	case TRACE_STACK:
+	case TRACE_SPECIAL:
+		return 1;
+	}
+	return 0;
+}
+
+static int
+trace_test_buffer_cpu(struct trace_array *tr, struct trace_array_cpu *data)
+{
+	struct trace_entry *entries;
+	struct page *page;
+	int idx = 0;
+	int i;
+
+	BUG_ON(list_empty(&data->trace_pages));
+	page = list_entry(data->trace_pages.next, struct page, lru);
+	entries = page_address(page);
+
+	check_pages(data);
+	if (head_page(data) != entries)
+		goto failed;
+
+	/*
+	 * The starting trace buffer always has valid elements,
+	 * if any element exists.
+	 */
+	entries = head_page(data);
+
+	for (i = 0; i < tr->entries; i++) {
+
+		if (i < data->trace_idx && !trace_valid_entry(&entries[idx])) {
+			printk(KERN_CONT ".. invalid entry %d ",
+				entries[idx].type);
+			goto failed;
+		}
+
+		idx++;
+		if (idx >= ENTRIES_PER_PAGE) {
+			page = virt_to_page(entries);
+			if (page->lru.next == &data->trace_pages) {
+				if (i != tr->entries - 1) {
+					printk(KERN_CONT ".. entries buffer mismatch");
+					goto failed;
+				}
+			} else {
+				page = list_entry(page->lru.next, struct page, lru);
+				entries = page_address(page);
+			}
+			idx = 0;
+		}
+	}
+
+	page = virt_to_page(entries);
+	if (page->lru.next != &data->trace_pages) {
+		printk(KERN_CONT ".. too many entries");
+		goto failed;
+	}
+
+	return 0;
+
+ failed:
+	/* disable tracing */
+	tracing_disabled = 1;
+	printk(KERN_CONT ".. corrupted trace buffer .. ");
+	return -1;
+}
+
+/*
+ * Test the trace buffer to see if all the elements
+ * are still sane.
+ */
+static int trace_test_buffer(struct trace_array *tr, unsigned long *count)
+{
+	unsigned long flags, cnt = 0;
+	int cpu, ret = 0;
+
+	/* Don't allow flipping of max traces now */
+	raw_local_irq_save(flags);
+	__raw_spin_lock(&ftrace_max_lock);
+	for_each_possible_cpu(cpu) {
+		if (!head_page(tr->data[cpu]))
+			continue;
+
+		cnt += tr->data[cpu]->trace_idx;
+
+		ret = trace_test_buffer_cpu(tr, tr->data[cpu]);
+		if (ret)
+			break;
+	}
+	__raw_spin_unlock(&ftrace_max_lock);
+	raw_local_irq_restore(flags);
+
+	if (count)
+		*count = cnt;
+
+	return ret;
+}
+
+#ifdef CONFIG_FTRACE
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+#define __STR(x) #x
+#define STR(x) __STR(x)
+
+/* Test dynamic code modification and ftrace filters */
+int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
+					   struct trace_array *tr,
+					   int (*func)(void))
+{
+	unsigned long count;
+	int ret;
+	int save_ftrace_enabled = ftrace_enabled;
+	int save_tracer_enabled = tracer_enabled;
+	char *func_name;
+
+	/* The ftrace test PASSED */
+	printk(KERN_CONT "PASSED\n");
+	pr_info("Testing dynamic ftrace: ");
+
+	/* enable tracing, and record the filter function */
+	ftrace_enabled = 1;
+	tracer_enabled = 1;
+
+	/* passed in by parameter to fool gcc from optimizing */
+	func();
+
+	/* update the records */
+	ret = ftrace_force_update();
+	if (ret) {
+		printk(KERN_CONT ".. ftraced failed .. ");
+		return ret;
+	}
+
+	/*
+	 * Some archs *cough*PowerPC*cough* add charachters to the
+	 * start of the function names. We simply put a '*' to
+	 * accomodate them.
+	 */
+	func_name = "*" STR(DYN_FTRACE_TEST_NAME);
+
+	/* filter only on our function */
+	ftrace_set_filter(func_name, strlen(func_name), 1);
+
+	/* enable tracing */
+	tr->ctrl = 1;
+	trace->init(tr);
+	/* Sleep for a 1/10 of a second */
+	msleep(100);
+
+	/* we should have nothing in the buffer */
+	ret = trace_test_buffer(tr, &count);
+	if (ret)
+		goto out;
+
+	if (count) {
+		ret = -1;
+		printk(KERN_CONT ".. filter did not filter .. ");
+		goto out;
+	}
+
+	/* call our function again */
+	func();
+
+	/* sleep again */
+	msleep(100);
+
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	ftrace_enabled = 0;
+
+	/* check the trace buffer */
+	ret = trace_test_buffer(tr, &count);
+	trace->reset(tr);
+
+	/* we should only have one item */
+	if (!ret && count != 1) {
+		printk(KERN_CONT ".. filter failed count=%ld ..", count);
+		ret = -1;
+		goto out;
+	}
+ out:
+	ftrace_enabled = save_ftrace_enabled;
+	tracer_enabled = save_tracer_enabled;
+
+	/* Enable tracing on all functions again */
+	ftrace_set_filter(NULL, 0, 1);
+
+	return ret;
+}
+#else
+# define trace_selftest_startup_dynamic_tracing(trace, tr, func) ({ 0; })
+#endif /* CONFIG_DYNAMIC_FTRACE */
+/*
+ * Simple verification test of ftrace function tracer.
+ * Enable ftrace, sleep 1/10 second, and then read the trace
+ * buffer to see if all is in order.
+ */
+int
+trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
+{
+	unsigned long count;
+	int ret;
+	int save_ftrace_enabled = ftrace_enabled;
+	int save_tracer_enabled = tracer_enabled;
+
+	/* make sure msleep has been recorded */
+	msleep(1);
+
+	/* force the recorded functions to be traced */
+	ret = ftrace_force_update();
+	if (ret) {
+		printk(KERN_CONT ".. ftraced failed .. ");
+		return ret;
+	}
+
+	/* start the tracing */
+	ftrace_enabled = 1;
+	tracer_enabled = 1;
+
+	tr->ctrl = 1;
+	trace->init(tr);
+	/* Sleep for a 1/10 of a second */
+	msleep(100);
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	ftrace_enabled = 0;
+
+	/* check the trace buffer */
+	ret = trace_test_buffer(tr, &count);
+	trace->reset(tr);
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+		goto out;
+	}
+
+	ret = trace_selftest_startup_dynamic_tracing(trace, tr,
+						     DYN_FTRACE_TEST_NAME);
+
+ out:
+	ftrace_enabled = save_ftrace_enabled;
+	tracer_enabled = save_tracer_enabled;
+
+	/* kill ftrace totally if we failed */
+	if (ret)
+		ftrace_kill();
+
+	return ret;
+}
+#endif /* CONFIG_FTRACE */
+
+#ifdef CONFIG_IRQSOFF_TRACER
+int
+trace_selftest_startup_irqsoff(struct tracer *trace, struct trace_array *tr)
+{
+	unsigned long save_max = tracing_max_latency;
+	unsigned long count;
+	int ret;
+
+	/* start the tracing */
+	tr->ctrl = 1;
+	trace->init(tr);
+	/* reset the max latency */
+	tracing_max_latency = 0;
+	/* disable interrupts for a bit */
+	local_irq_disable();
+	udelay(100);
+	local_irq_enable();
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	/* check both trace buffers */
+	ret = trace_test_buffer(tr, NULL);
+	if (!ret)
+		ret = trace_test_buffer(&max_tr, &count);
+	trace->reset(tr);
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+	}
+
+	tracing_max_latency = save_max;
+
+	return ret;
+}
+#endif /* CONFIG_IRQSOFF_TRACER */
+
+#ifdef CONFIG_PREEMPT_TRACER
+int
+trace_selftest_startup_preemptoff(struct tracer *trace, struct trace_array *tr)
+{
+	unsigned long save_max = tracing_max_latency;
+	unsigned long count;
+	int ret;
+
+	/* start the tracing */
+	tr->ctrl = 1;
+	trace->init(tr);
+	/* reset the max latency */
+	tracing_max_latency = 0;
+	/* disable preemption for a bit */
+	preempt_disable();
+	udelay(100);
+	preempt_enable();
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	/* check both trace buffers */
+	ret = trace_test_buffer(tr, NULL);
+	if (!ret)
+		ret = trace_test_buffer(&max_tr, &count);
+	trace->reset(tr);
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+	}
+
+	tracing_max_latency = save_max;
+
+	return ret;
+}
+#endif /* CONFIG_PREEMPT_TRACER */
+
+#if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
+int
+trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *tr)
+{
+	unsigned long save_max = tracing_max_latency;
+	unsigned long count;
+	int ret;
+
+	/* start the tracing */
+	tr->ctrl = 1;
+	trace->init(tr);
+
+	/* reset the max latency */
+	tracing_max_latency = 0;
+
+	/* disable preemption and interrupts for a bit */
+	preempt_disable();
+	local_irq_disable();
+	udelay(100);
+	preempt_enable();
+	/* reverse the order of preempt vs irqs */
+	local_irq_enable();
+
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	/* check both trace buffers */
+	ret = trace_test_buffer(tr, NULL);
+	if (ret)
+		goto out;
+
+	ret = trace_test_buffer(&max_tr, &count);
+	if (ret)
+		goto out;
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+		goto out;
+	}
+
+	/* do the test by disabling interrupts first this time */
+	tracing_max_latency = 0;
+	tr->ctrl = 1;
+	trace->ctrl_update(tr);
+	preempt_disable();
+	local_irq_disable();
+	udelay(100);
+	preempt_enable();
+	/* reverse the order of preempt vs irqs */
+	local_irq_enable();
+
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	/* check both trace buffers */
+	ret = trace_test_buffer(tr, NULL);
+	if (ret)
+		goto out;
+
+	ret = trace_test_buffer(&max_tr, &count);
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+		goto out;
+	}
+
+ out:
+	trace->reset(tr);
+	tracing_max_latency = save_max;
+
+	return ret;
+}
+#endif /* CONFIG_IRQSOFF_TRACER && CONFIG_PREEMPT_TRACER */
+
+#ifdef CONFIG_SCHED_TRACER
+static int trace_wakeup_test_thread(void *data)
+{
+	/* Make this a RT thread, doesn't need to be too high */
+	struct sched_param param = { .sched_priority = 5 };
+	struct completion *x = data;
+
+	sched_setscheduler(current, SCHED_FIFO, &param);
+
+	/* Make it know we have a new prio */
+	complete(x);
+
+	/* now go to sleep and let the test wake us up */
+	set_current_state(TASK_INTERRUPTIBLE);
+	schedule();
+
+	/* we are awake, now wait to disappear */
+	while (!kthread_should_stop()) {
+		/*
+		 * This is an RT task, do short sleeps to let
+		 * others run.
+		 */
+		msleep(100);
+	}
+
+	return 0;
+}
+
+int
+trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
+{
+	unsigned long save_max = tracing_max_latency;
+	struct task_struct *p;
+	struct completion isrt;
+	unsigned long count;
+	int ret;
+
+	init_completion(&isrt);
+
+	/* create a high prio thread */
+	p = kthread_run(trace_wakeup_test_thread, &isrt, "ftrace-test");
+	if (IS_ERR(p)) {
+		printk(KERN_CONT "Failed to create ftrace wakeup test thread ");
+		return -1;
+	}
+
+	/* make sure the thread is running at an RT prio */
+	wait_for_completion(&isrt);
+
+	/* start the tracing */
+	tr->ctrl = 1;
+	trace->init(tr);
+	/* reset the max latency */
+	tracing_max_latency = 0;
+
+	/* sleep to let the RT thread sleep too */
+	msleep(100);
+
+	/*
+	 * Yes this is slightly racy. It is possible that for some
+	 * strange reason that the RT thread we created, did not
+	 * call schedule for 100ms after doing the completion,
+	 * and we do a wakeup on a task that already is awake.
+	 * But that is extremely unlikely, and the worst thing that
+	 * happens in such a case, is that we disable tracing.
+	 * Honestly, if this race does happen something is horrible
+	 * wrong with the system.
+	 */
+
+	wake_up_process(p);
+
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	/* check both trace buffers */
+	ret = trace_test_buffer(tr, NULL);
+	if (!ret)
+		ret = trace_test_buffer(&max_tr, &count);
+
+
+	trace->reset(tr);
+
+	tracing_max_latency = save_max;
+
+	/* kill the thread */
+	kthread_stop(p);
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+	}
+
+	return ret;
+}
+#endif /* CONFIG_SCHED_TRACER */
+
+#ifdef CONFIG_CONTEXT_SWITCH_TRACER
+int
+trace_selftest_startup_sched_switch(struct tracer *trace, struct trace_array *tr)
+{
+	unsigned long count;
+	int ret;
+
+	/* start the tracing */
+	tr->ctrl = 1;
+	trace->init(tr);
+	/* Sleep for a 1/10 of a second */
+	msleep(100);
+	/* stop the tracing. */
+	tr->ctrl = 0;
+	trace->ctrl_update(tr);
+	/* check the trace buffer */
+	ret = trace_test_buffer(tr, &count);
+	trace->reset(tr);
+
+	if (!ret && !count) {
+		printk(KERN_CONT ".. no entries found ..");
+		ret = -1;
+	}
+
+	return ret;
+}
+#endif /* CONFIG_CONTEXT_SWITCH_TRACER */

kernel/trace/trace_selftest_dynamic.c

@@ -0,0 +1,7 @@
+#include "trace.h"
+
+int DYN_FTRACE_TEST_NAME(void)
+{
+	/* used to call mcount */
+	return 0;
+}

lib/Kconfig.debug

@@ -634,6 +634,8 @@ config LATENCYTOP
 	  Enable this option if you want to use the LatencyTOP tool
 	  to find out which userspace is blocking on what kernel operations.
 
+source kernel/trace/Kconfig
+
 config PROVIDE_OHCI1394_DMA_INIT
 	bool "Remote debugging over FireWire early on boot"
 	depends on PCI && X86

lib/Makefile

@@ -8,6 +8,15 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 sha1.o irq_regs.o reciprocal_div.o argv_split.o \
 	 proportions.o prio_heap.o ratelimit.o
 
+ifdef CONFIG_FTRACE
+# Do not profile string.o, since it may be used in early boot or vdso
+CFLAGS_REMOVE_string.o = -pg
+# Also do not profile any debug utilities
+CFLAGS_REMOVE_spinlock_debug.o = -pg
+CFLAGS_REMOVE_list_debug.o = -pg
+CFLAGS_REMOVE_debugobjects.o = -pg
+endif
+
 lib-$(CONFIG_MMU) += ioremap.o
 lib-$(CONFIG_SMP) += cpumask.o
 

lib/smp_processor_id.c

@@ -7,7 +7,7 @@
 #include <linux/kallsyms.h>
 #include <linux/sched.h>
 
-unsigned int debug_smp_processor_id(void)
+notrace unsigned int debug_smp_processor_id(void)
 {
 	unsigned long preempt_count = preempt_count();
 	int this_cpu = raw_smp_processor_id();
@@ -37,7 +37,7 @@ unsigned int debug_smp_processor_id(void)
 	/*
 	 * Avoid recursion:
 	 */
-	preempt_disable();
+	preempt_disable_notrace();
 
 	if (!printk_ratelimit())
 		goto out_enable;
@@ -49,7 +49,7 @@ unsigned int debug_smp_processor_id(void)
 	dump_stack();
 
 out_enable:
-	preempt_enable_no_resched();
+	preempt_enable_no_resched_notrace();
 out:
 	return this_cpu;
 }

mm/page-writeback.c

@@ -126,8 +126,6 @@ static void background_writeout(unsigned long _min_pages);
 static struct prop_descriptor vm_completions;
 static struct prop_descriptor vm_dirties;
 
-static unsigned long determine_dirtyable_memory(void);
-
 /*
  * couple the period to the dirty_ratio:
  *
@@ -347,7 +345,13 @@ static unsigned long highmem_dirtyable_memory(unsigned long total)
 #endif
 }
 
-static unsigned long determine_dirtyable_memory(void)
+/**
+ * determine_dirtyable_memory - amount of memory that may be used
+ *
+ * Returns the numebr of pages that can currently be freed and used
+ * by the kernel for direct mappings.
+ */
+unsigned long determine_dirtyable_memory(void)
 {
 	unsigned long x;
 

scripts/Makefile.lib

@@ -96,7 +96,8 @@ basename_flags = -D"KBUILD_BASENAME=KBUILD_STR($(call name-fix,$(basetarget)))"
 modname_flags  = $(if $(filter 1,$(words $(modname))),\
                  -D"KBUILD_MODNAME=KBUILD_STR($(call name-fix,$(modname)))")
 
-_c_flags       = $(KBUILD_CFLAGS) $(ccflags-y) $(CFLAGS_$(basetarget).o)
+orig_c_flags   = $(KBUILD_CFLAGS) $(ccflags-y) $(CFLAGS_$(basetarget).o)
+_c_flags       = $(filter-out $(CFLAGS_REMOVE_$(basetarget).o), $(orig_c_flags))
 _a_flags       = $(KBUILD_AFLAGS) $(asflags-y) $(AFLAGS_$(basetarget).o)
 _cpp_flags     = $(KBUILD_CPPFLAGS) $(cppflags-y) $(CPPFLAGS_$(@F))