x86, 386 removal: Remove CONFIG_CMPXCHG

All 486+ CPUs support CMPXCHG, so remove the fallback 386 support
code.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1354132230-21854-3-git-send-email-hpa@linux.intel.com

arch/x86/Kconfig.cpu

@@ -297,9 +297,6 @@ config X86_INTERNODE_CACHE_SHIFT
 	default "12" if X86_VSMP
 	default X86_L1_CACHE_SHIFT
 
-config X86_CMPXCHG
-	def_bool y
-
 config X86_L1_CACHE_SHIFT
 	int
 	default "7" if MPENTIUM4 || MPSC

arch/x86/include/asm/cmpxchg_32.h

@@ -34,9 +34,7 @@ static inline void set_64bit(volatile u64 *ptr, u64 value)
 		     : "memory");
 }
 
-#ifdef CONFIG_X86_CMPXCHG
 #define __HAVE_ARCH_CMPXCHG 1
-#endif
 
 #ifdef CONFIG_X86_CMPXCHG64
 #define cmpxchg64(ptr, o, n)						\
@@ -73,59 +71,6 @@ static inline u64 __cmpxchg64_local(volatile u64 *ptr, u64 old, u64 new)
 	return prev;
 }
 
-#ifndef CONFIG_X86_CMPXCHG
-/*
- * Building a kernel capable running on 80386. It may be necessary to
- * simulate the cmpxchg on the 80386 CPU. For that purpose we define
- * a function for each of the sizes we support.
- */
-
-extern unsigned long cmpxchg_386_u8(volatile void *, u8, u8);
-extern unsigned long cmpxchg_386_u16(volatile void *, u16, u16);
-extern unsigned long cmpxchg_386_u32(volatile void *, u32, u32);
-
-static inline unsigned long cmpxchg_386(volatile void *ptr, unsigned long old,
-					unsigned long new, int size)
-{
-	switch (size) {
-	case 1:
-		return cmpxchg_386_u8(ptr, old, new);
-	case 2:
-		return cmpxchg_386_u16(ptr, old, new);
-	case 4:
-		return cmpxchg_386_u32(ptr, old, new);
-	}
-	return old;
-}
-
-#define cmpxchg(ptr, o, n)						\
-({									\
-	__typeof__(*(ptr)) __ret;					\
-	if (likely(boot_cpu_data.x86 > 3))				\
-		__ret = (__typeof__(*(ptr)))__cmpxchg((ptr),		\
-				(unsigned long)(o), (unsigned long)(n),	\
-				sizeof(*(ptr)));			\
-	else								\
-		__ret = (__typeof__(*(ptr)))cmpxchg_386((ptr),		\
-				(unsigned long)(o), (unsigned long)(n),	\
-				sizeof(*(ptr)));			\
-	__ret;								\
-})
-#define cmpxchg_local(ptr, o, n)					\
-({									\
-	__typeof__(*(ptr)) __ret;					\
-	if (likely(boot_cpu_data.x86 > 3))				\
-		__ret = (__typeof__(*(ptr)))__cmpxchg_local((ptr),	\
-				(unsigned long)(o), (unsigned long)(n),	\
-				sizeof(*(ptr)));			\
-	else								\
-		__ret = (__typeof__(*(ptr)))cmpxchg_386((ptr),		\
-				(unsigned long)(o), (unsigned long)(n),	\
-				sizeof(*(ptr)));			\
-	__ret;								\
-})
-#endif
-
 #ifndef CONFIG_X86_CMPXCHG64
 /*
  * Building a kernel capable running on 80386 and 80486. It may be necessary

arch/x86/include/asm/percpu.h

@@ -406,7 +406,6 @@ do {									\
 #define this_cpu_xchg_2(pcp, nval)	percpu_xchg_op(pcp, nval)
 #define this_cpu_xchg_4(pcp, nval)	percpu_xchg_op(pcp, nval)
 
-#ifndef CONFIG_M386
 #define __this_cpu_add_return_1(pcp, val) percpu_add_return_op(pcp, val)
 #define __this_cpu_add_return_2(pcp, val) percpu_add_return_op(pcp, val)
 #define __this_cpu_add_return_4(pcp, val) percpu_add_return_op(pcp, val)
@@ -421,8 +420,6 @@ do {									\
 #define this_cpu_cmpxchg_2(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
 #define this_cpu_cmpxchg_4(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
 
-#endif /* !CONFIG_M386 */
-
 #ifdef CONFIG_X86_CMPXCHG64
 #define percpu_cmpxchg8b_double(pcp1, pcp2, o1, o2, n1, n2)		\
 ({									\

arch/x86/lib/Makefile

@@ -32,7 +32,6 @@ ifeq ($(CONFIG_X86_32),y)
         lib-y += checksum_32.o
         lib-y += strstr_32.o
         lib-y += string_32.o
-        lib-y += cmpxchg.o
 ifneq ($(CONFIG_X86_CMPXCHG64),y)
         lib-y += cmpxchg8b_emu.o atomic64_386_32.o
 endif

arch/x86/lib/cmpxchg.c

@@ -1,54 +0,0 @@
-/*
- * cmpxchg*() fallbacks for CPU not supporting these instructions
- */
-
-#include <linux/kernel.h>
-#include <linux/smp.h>
-#include <linux/module.h>
-
-#ifndef CONFIG_X86_CMPXCHG
-unsigned long cmpxchg_386_u8(volatile void *ptr, u8 old, u8 new)
-{
-	u8 prev;
-	unsigned long flags;
-
-	/* Poor man's cmpxchg for 386. Unsuitable for SMP */
-	local_irq_save(flags);
-	prev = *(u8 *)ptr;
-	if (prev == old)
-		*(u8 *)ptr = new;
-	local_irq_restore(flags);
-	return prev;
-}
-EXPORT_SYMBOL(cmpxchg_386_u8);
-
-unsigned long cmpxchg_386_u16(volatile void *ptr, u16 old, u16 new)
-{
-	u16 prev;
-	unsigned long flags;
-
-	/* Poor man's cmpxchg for 386. Unsuitable for SMP */
-	local_irq_save(flags);
-	prev = *(u16 *)ptr;
-	if (prev == old)
-		*(u16 *)ptr = new;
-	local_irq_restore(flags);
-	return prev;
-}
-EXPORT_SYMBOL(cmpxchg_386_u16);
-
-unsigned long cmpxchg_386_u32(volatile void *ptr, u32 old, u32 new)
-{
-	u32 prev;
-	unsigned long flags;
-
-	/* Poor man's cmpxchg for 386. Unsuitable for SMP */
-	local_irq_save(flags);
-	prev = *(u32 *)ptr;
-	if (prev == old)
-		*(u32 *)ptr = new;
-	local_irq_restore(flags);
-	return prev;
-}
-EXPORT_SYMBOL(cmpxchg_386_u32);
-#endif

arch/x86/xen/Kconfig

@@ -7,7 +7,7 @@ config XEN
 	select PARAVIRT
 	select PARAVIRT_CLOCK
 	depends on X86_64 || (X86_32 && X86_PAE && !X86_VISWS)
-	depends on X86_CMPXCHG && X86_TSC
+	depends on X86_TSC
 	help
 	  This is the Linux Xen port.  Enabling this will allow the
 	  kernel to boot in a paravirtualized environment under the