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Diffstat (limited to 'arch/x86/include/asm/cmpxchg_32.h')
-rw-r--r--arch/x86/include/asm/cmpxchg_32.h366
1 files changed, 69 insertions, 297 deletions
diff --git a/arch/x86/include/asm/cmpxchg_32.h b/arch/x86/include/asm/cmpxchg_32.h
index 82ceb788a98..f8bf2eecab8 100644
--- a/arch/x86/include/asm/cmpxchg_32.h
+++ b/arch/x86/include/asm/cmpxchg_32.h
@@ -1,128 +1,40 @@
#ifndef _ASM_X86_CMPXCHG_32_H
#define _ASM_X86_CMPXCHG_32_H
-#include <linux/bitops.h> /* for LOCK_PREFIX */
-
/*
* Note: if you use set64_bit(), __cmpxchg64(), or their variants, you
* you need to test for the feature in boot_cpu_data.
*/
-#define xchg(ptr, v) \
- ((__typeof__(*(ptr)))__xchg((unsigned long)(v), (ptr), sizeof(*(ptr))))
-
-struct __xchg_dummy {
- unsigned long a[100];
-};
-#define __xg(x) ((struct __xchg_dummy *)(x))
-
/*
- * The semantics of XCHGCMP8B are a bit strange, this is why
- * there is a loop and the loading of %%eax and %%edx has to
- * be inside. This inlines well in most cases, the cached
- * cost is around ~38 cycles. (in the future we might want
- * to do an SIMD/3DNOW!/MMX/FPU 64-bit store here, but that
- * might have an implicit FPU-save as a cost, so it's not
- * clear which path to go.)
+ * CMPXCHG8B only writes to the target if we had the previous
+ * value in registers, otherwise it acts as a read and gives us the
+ * "new previous" value. That is why there is a loop. Preloading
+ * EDX:EAX is a performance optimization: in the common case it means
+ * we need only one locked operation.
*
- * cmpxchg8b must be used with the lock prefix here to allow
- * the instruction to be executed atomically, see page 3-102
- * of the instruction set reference 24319102.pdf. We need
- * the reader side to see the coherent 64bit value.
+ * A SIMD/3DNOW!/MMX/FPU 64-bit store here would require at the very
+ * least an FPU save and/or %cr0.ts manipulation.
+ *
+ * cmpxchg8b must be used with the lock prefix here to allow the
+ * instruction to be executed atomically. We need to have the reader
+ * side to see the coherent 64bit value.
*/
-static inline void __set_64bit(unsigned long long *ptr,
- unsigned int low, unsigned int high)
+static inline void set_64bit(volatile u64 *ptr, u64 value)
{
+ u32 low = value;
+ u32 high = value >> 32;
+ u64 prev = *ptr;
+
asm volatile("\n1:\t"
- "movl (%0), %%eax\n\t"
- "movl 4(%0), %%edx\n\t"
- LOCK_PREFIX "cmpxchg8b (%0)\n\t"
+ LOCK_PREFIX "cmpxchg8b %0\n\t"
"jnz 1b"
- : /* no outputs */
- : "D"(ptr),
- "b"(low),
- "c"(high)
- : "ax", "dx", "memory");
-}
-
-static inline void __set_64bit_constant(unsigned long long *ptr,
- unsigned long long value)
-{
- __set_64bit(ptr, (unsigned int)value, (unsigned int)(value >> 32));
-}
-
-#define ll_low(x) *(((unsigned int *)&(x)) + 0)
-#define ll_high(x) *(((unsigned int *)&(x)) + 1)
-
-static inline void __set_64bit_var(unsigned long long *ptr,
- unsigned long long value)
-{
- __set_64bit(ptr, ll_low(value), ll_high(value));
-}
-
-#define set_64bit(ptr, value) \
- (__builtin_constant_p((value)) \
- ? __set_64bit_constant((ptr), (value)) \
- : __set_64bit_var((ptr), (value)))
-
-#define _set_64bit(ptr, value) \
- (__builtin_constant_p(value) \
- ? __set_64bit(ptr, (unsigned int)(value), \
- (unsigned int)((value) >> 32)) \
- : __set_64bit(ptr, ll_low((value)), ll_high((value))))
-
-/*
- * Note: no "lock" prefix even on SMP: xchg always implies lock anyway
- * Note 2: xchg has side effect, so that attribute volatile is necessary,
- * but generally the primitive is invalid, *ptr is output argument. --ANK
- */
-static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
- int size)
-{
- switch (size) {
- case 1:
- asm volatile("xchgb %b0,%1"
- : "=q" (x)
- : "m" (*__xg(ptr)), "0" (x)
- : "memory");
- break;
- case 2:
- asm volatile("xchgw %w0,%1"
- : "=r" (x)
- : "m" (*__xg(ptr)), "0" (x)
- : "memory");
- break;
- case 4:
- asm volatile("xchgl %0,%1"
- : "=r" (x)
- : "m" (*__xg(ptr)), "0" (x)
- : "memory");
- break;
- }
- return x;
+ : "=m" (*ptr), "+A" (prev)
+ : "b" (low), "c" (high)
+ : "memory");
}
-/*
- * Atomic compare and exchange. Compare OLD with MEM, if identical,
- * store NEW in MEM. Return the initial value in MEM. Success is
- * indicated by comparing RETURN with OLD.
- */
-
-#ifdef CONFIG_X86_CMPXCHG
#define __HAVE_ARCH_CMPXCHG 1
-#define cmpxchg(ptr, o, n) \
- ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o), \
- (unsigned long)(n), \
- sizeof(*(ptr))))
-#define sync_cmpxchg(ptr, o, n) \
- ((__typeof__(*(ptr)))__sync_cmpxchg((ptr), (unsigned long)(o), \
- (unsigned long)(n), \
- sizeof(*(ptr))))
-#define cmpxchg_local(ptr, o, n) \
- ((__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o), \
- (unsigned long)(n), \
- sizeof(*(ptr))))
-#endif
#ifdef CONFIG_X86_CMPXCHG64
#define cmpxchg64(ptr, o, n) \
@@ -133,212 +45,72 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
(unsigned long long)(n)))
#endif
-static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
- unsigned long new, int size)
+static inline u64 __cmpxchg64(volatile u64 *ptr, u64 old, u64 new)
{
- unsigned long prev;
- switch (size) {
- case 1:
- asm volatile(LOCK_PREFIX "cmpxchgb %b1,%2"
- : "=a"(prev)
- : "q"(new), "m"(*__xg(ptr)), "0"(old)
- : "memory");
- return prev;
- case 2:
- asm volatile(LOCK_PREFIX "cmpxchgw %w1,%2"
- : "=a"(prev)
- : "r"(new), "m"(*__xg(ptr)), "0"(old)
- : "memory");
- return prev;
- case 4:
- asm volatile(LOCK_PREFIX "cmpxchgl %1,%2"
- : "=a"(prev)
- : "r"(new), "m"(*__xg(ptr)), "0"(old)
- : "memory");
- return prev;
- }
- return old;
-}
-
-/*
- * Always use locked operations when touching memory shared with a
- * hypervisor, since the system may be SMP even if the guest kernel
- * isn't.
- */
-static inline unsigned long __sync_cmpxchg(volatile void *ptr,
- unsigned long old,
- unsigned long new, int size)
-{
- unsigned long prev;
- switch (size) {
- case 1:
- asm volatile("lock; cmpxchgb %b1,%2"
- : "=a"(prev)
- : "q"(new), "m"(*__xg(ptr)), "0"(old)
- : "memory");
- return prev;
- case 2:
- asm volatile("lock; cmpxchgw %w1,%2"
- : "=a"(prev)
- : "r"(new), "m"(*__xg(ptr)), "0"(old)
- : "memory");
- return prev;
- case 4:
- asm volatile("lock; cmpxchgl %1,%2"
- : "=a"(prev)
- : "r"(new), "m"(*__xg(ptr)), "0"(old)
- : "memory");
- return prev;
- }
- return old;
-}
-
-static inline unsigned long __cmpxchg_local(volatile void *ptr,
- unsigned long old,
- unsigned long new, int size)
-{
- unsigned long prev;
- switch (size) {
- case 1:
- asm volatile("cmpxchgb %b1,%2"
- : "=a"(prev)
- : "q"(new), "m"(*__xg(ptr)), "0"(old)
- : "memory");
- return prev;
- case 2:
- asm volatile("cmpxchgw %w1,%2"
- : "=a"(prev)
- : "r"(new), "m"(*__xg(ptr)), "0"(old)
- : "memory");
- return prev;
- case 4:
- asm volatile("cmpxchgl %1,%2"
- : "=a"(prev)
- : "r"(new), "m"(*__xg(ptr)), "0"(old)
- : "memory");
- return prev;
- }
- return old;
-}
-
-static inline unsigned long long __cmpxchg64(volatile void *ptr,
- unsigned long long old,
- unsigned long long new)
-{
- unsigned long long prev;
- asm volatile(LOCK_PREFIX "cmpxchg8b %3"
- : "=A"(prev)
- : "b"((unsigned long)new),
- "c"((unsigned long)(new >> 32)),
- "m"(*__xg(ptr)),
- "0"(old)
+ u64 prev;
+ asm volatile(LOCK_PREFIX "cmpxchg8b %1"
+ : "=A" (prev),
+ "+m" (*ptr)
+ : "b" ((u32)new),
+ "c" ((u32)(new >> 32)),
+ "0" (old)
: "memory");
return prev;
}
-static inline unsigned long long __cmpxchg64_local(volatile void *ptr,
- unsigned long long old,
- unsigned long long new)
+static inline u64 __cmpxchg64_local(volatile u64 *ptr, u64 old, u64 new)
{
- unsigned long long prev;
- asm volatile("cmpxchg8b %3"
- : "=A"(prev)
- : "b"((unsigned long)new),
- "c"((unsigned long)(new >> 32)),
- "m"(*__xg(ptr)),
- "0"(old)
+ u64 prev;
+ asm volatile("cmpxchg8b %1"
+ : "=A" (prev),
+ "+m" (*ptr)
+ : "b" ((u32)new),
+ "c" ((u32)(new >> 32)),
+ "0" (old)
: "memory");
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
* to simulate the cmpxchg8b on the 80386 and 80486 CPU.
*/
-extern unsigned long long cmpxchg_486_u64(volatile void *, u64, u64);
-
-#define cmpxchg64(ptr, o, n) \
-({ \
- __typeof__(*(ptr)) __ret; \
- if (likely(boot_cpu_data.x86 > 4)) \
- __ret = (__typeof__(*(ptr)))__cmpxchg64((ptr), \
- (unsigned long long)(o), \
- (unsigned long long)(n)); \
- else \
- __ret = (__typeof__(*(ptr)))cmpxchg_486_u64((ptr), \
- (unsigned long long)(o), \
- (unsigned long long)(n)); \
- __ret; \
-})
-#define cmpxchg64_local(ptr, o, n) \
-({ \
- __typeof__(*(ptr)) __ret; \
- if (likely(boot_cpu_data.x86 > 4)) \
- __ret = (__typeof__(*(ptr)))__cmpxchg64_local((ptr), \
- (unsigned long long)(o), \
- (unsigned long long)(n)); \
- else \
- __ret = (__typeof__(*(ptr)))cmpxchg_486_u64((ptr), \
- (unsigned long long)(o), \
- (unsigned long long)(n)); \
- __ret; \
-})
+#define cmpxchg64(ptr, o, n) \
+({ \
+ __typeof__(*(ptr)) __ret; \
+ __typeof__(*(ptr)) __old = (o); \
+ __typeof__(*(ptr)) __new = (n); \
+ alternative_io(LOCK_PREFIX_HERE \
+ "call cmpxchg8b_emu", \
+ "lock; cmpxchg8b (%%esi)" , \
+ X86_FEATURE_CX8, \
+ "=A" (__ret), \
+ "S" ((ptr)), "0" (__old), \
+ "b" ((unsigned int)__new), \
+ "c" ((unsigned int)(__new>>32)) \
+ : "memory"); \
+ __ret; })
+
+
+#define cmpxchg64_local(ptr, o, n) \
+({ \
+ __typeof__(*(ptr)) __ret; \
+ __typeof__(*(ptr)) __old = (o); \
+ __typeof__(*(ptr)) __new = (n); \
+ alternative_io("call cmpxchg8b_emu", \
+ "cmpxchg8b (%%esi)" , \
+ X86_FEATURE_CX8, \
+ "=A" (__ret), \
+ "S" ((ptr)), "0" (__old), \
+ "b" ((unsigned int)__new), \
+ "c" ((unsigned int)(__new>>32)) \
+ : "memory"); \
+ __ret; })
#endif
+#define system_has_cmpxchg_double() cpu_has_cx8
+
#endif /* _ASM_X86_CMPXCHG_32_H */
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