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@@ -2,7 +2,7 @@
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* Code for replacing ftrace calls with jumps.
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*
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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- * Copyright (C) 2009 DSLab, Lanzhou University, China
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+ * Copyright (C) 2009, 2010 DSLab, Lanzhou University, China
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* Author: Wu Zhangjin <wuzhangjin@gmail.com>
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*
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* Thanks goes to Steven Rostedt for writing the original x86 version.
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@@ -12,21 +12,46 @@
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#include <linux/init.h>
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#include <linux/ftrace.h>
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-#include <asm/cacheflush.h>
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#include <asm/asm.h>
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#include <asm/asm-offsets.h>
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+#include <asm/cacheflush.h>
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+#include <asm/uasm.h>
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#ifdef CONFIG_DYNAMIC_FTRACE
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#define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */
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#define ADDR_MASK 0x03ffffff /* op_code|addr : 31...26|25 ....0 */
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-#define jump_insn_encode(op_code, addr) \
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- ((unsigned int)((op_code) | (((addr) >> 2) & ADDR_MASK)))
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#define INSN_B_1F_4 0x10000004 /* b 1f; offset = 4 */
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#define INSN_B_1F_5 0x10000005 /* b 1f; offset = 5 */
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#define INSN_NOP 0x00000000 /* nop */
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-#define INSN_JAL(addr) jump_insn_encode(JAL, addr)
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+#define INSN_JAL(addr) \
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+ ((unsigned int)(JAL | (((addr) >> 2) & ADDR_MASK)))
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+
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+static unsigned int insn_jal_ftrace_caller __read_mostly;
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+static unsigned int insn_lui_v1_hi16_mcount __read_mostly;
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+static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly;
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+
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+static inline void ftrace_dyn_arch_init_insns(void)
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+{
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+ u32 *buf;
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+ unsigned int v1;
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+
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+ /* lui v1, hi16_mcount */
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+ v1 = 3;
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+ buf = (u32 *)&insn_lui_v1_hi16_mcount;
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+ UASM_i_LA_mostly(&buf, v1, MCOUNT_ADDR);
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+
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+ /* jal (ftrace_caller + 8), jump over the first two instruction */
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+ buf = (u32 *)&insn_jal_ftrace_caller;
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+ uasm_i_jal(&buf, (FTRACE_ADDR + 8));
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+
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+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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+ /* j ftrace_graph_caller */
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+ buf = (u32 *)&insn_j_ftrace_graph_caller;
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+ uasm_i_j(&buf, (unsigned long)ftrace_graph_caller);
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+#endif
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+}
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static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
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{
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@@ -43,30 +68,20 @@ static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
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return 0;
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}
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-static int lui_v1;
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-static int jal_mcount;
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-
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int ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned int new;
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- int faulted;
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unsigned long ip = rec->ip;
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- /* We have compiled module with -mlong-calls, but compiled the kernel
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- * without it, we need to cope with them respectively. */
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+ /*
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+ * We have compiled module with -mlong-calls, but compiled the kernel
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+ * without it, we need to cope with them respectively.
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+ */
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if (ip & 0x40000000) {
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- /* record it for ftrace_make_call */
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- if (lui_v1 == 0) {
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- /* lui_v1 = *(unsigned int *)ip; */
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- safe_load_code(lui_v1, ip, faulted);
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-
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- if (unlikely(faulted))
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- return -EFAULT;
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- }
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-
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#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
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- /* lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
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+ /*
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+ * lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
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* addiu v1, v1, low_16bit_of_mcount
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* move at, ra
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* move $12, ra_address
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@@ -76,7 +91,8 @@ int ftrace_make_nop(struct module *mod,
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*/
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new = INSN_B_1F_5;
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#else
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- /* lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
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+ /*
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+ * lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
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* addiu v1, v1, low_16bit_of_mcount
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* move at, ra
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* jalr v1
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@@ -86,36 +102,22 @@ int ftrace_make_nop(struct module *mod,
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new = INSN_B_1F_4;
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#endif
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} else {
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- /* record/calculate it for ftrace_make_call */
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- if (jal_mcount == 0) {
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- /* We can record it directly like this:
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- * jal_mcount = *(unsigned int *)ip;
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- * Herein, jump over the first two nop instructions */
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- jal_mcount = INSN_JAL(MCOUNT_ADDR + 8);
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- }
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-
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- /* move at, ra
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- * jalr v1 --> nop
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+ /*
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+ * move at, ra
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+ * jal _mcount --> nop
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*/
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new = INSN_NOP;
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}
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return ftrace_modify_code(ip, new);
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}
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-static int modified; /* initialized as 0 by default */
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-
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int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned int new;
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unsigned long ip = rec->ip;
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- /* We just need to remove the "b ftrace_stub" at the fist time! */
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- if (modified == 0) {
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- modified = 1;
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- ftrace_modify_code(addr, INSN_NOP);
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- }
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/* ip, module: 0xc0000000, kernel: 0x80000000 */
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- new = (ip & 0x40000000) ? lui_v1 : jal_mcount;
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+ new = (ip & 0x40000000) ? insn_lui_v1_hi16_mcount : insn_jal_ftrace_caller;
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return ftrace_modify_code(ip, new);
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}
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@@ -133,6 +135,12 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
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int __init ftrace_dyn_arch_init(void *data)
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{
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+ /* Encode the instructions when booting */
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+ ftrace_dyn_arch_init_insns();
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+
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+ /* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */
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+ ftrace_modify_code(MCOUNT_ADDR, INSN_NOP);
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+
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/* The return code is retured via data */
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*(unsigned long *)data = 0;
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@@ -145,15 +153,12 @@ int __init ftrace_dyn_arch_init(void *data)
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#ifdef CONFIG_DYNAMIC_FTRACE
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extern void ftrace_graph_call(void);
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-#define JMP 0x08000000 /* jump to target directly */
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-#define CALL_FTRACE_GRAPH_CALLER \
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- jump_insn_encode(JMP, (unsigned long)(&ftrace_graph_caller))
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#define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call))
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int ftrace_enable_ftrace_graph_caller(void)
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{
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return ftrace_modify_code(FTRACE_GRAPH_CALL_IP,
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- CALL_FTRACE_GRAPH_CALLER);
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+ insn_j_ftrace_graph_caller);
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}
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int ftrace_disable_ftrace_graph_caller(void)
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