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Diffstat (limited to 'arch/x86/include/asm/cmpxchg.h')
-rw-r--r--arch/x86/include/asm/cmpxchg.h70
1 files changed, 70 insertions, 0 deletions
diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h
index 97848cdfcb1a..d90296d061e8 100644
--- a/arch/x86/include/asm/cmpxchg.h
+++ b/arch/x86/include/asm/cmpxchg.h
@@ -153,6 +153,76 @@ extern void __add_wrong_size(void)
#define cmpxchg_local(ptr, old, new) \
__cmpxchg_local(ptr, old, new, sizeof(*(ptr)))
+
+#define __raw_try_cmpxchg(_ptr, _pold, _new, size, lock) \
+({ \
+ bool success; \
+ __typeof__(_ptr) _old = (_pold); \
+ __typeof__(*(_ptr)) __old = *_old; \
+ __typeof__(*(_ptr)) __new = (_new); \
+ switch (size) { \
+ case __X86_CASE_B: \
+ { \
+ volatile u8 *__ptr = (volatile u8 *)(_ptr); \
+ asm volatile(lock "cmpxchgb %[new], %[ptr]" \
+ CC_SET(z) \
+ : CC_OUT(z) (success), \
+ [ptr] "+m" (*__ptr), \
+ [old] "+a" (__old) \
+ : [new] "q" (__new) \
+ : "memory"); \
+ break; \
+ } \
+ case __X86_CASE_W: \
+ { \
+ volatile u16 *__ptr = (volatile u16 *)(_ptr); \
+ asm volatile(lock "cmpxchgw %[new], %[ptr]" \
+ CC_SET(z) \
+ : CC_OUT(z) (success), \
+ [ptr] "+m" (*__ptr), \
+ [old] "+a" (__old) \
+ : [new] "r" (__new) \
+ : "memory"); \
+ break; \
+ } \
+ case __X86_CASE_L: \
+ { \
+ volatile u32 *__ptr = (volatile u32 *)(_ptr); \
+ asm volatile(lock "cmpxchgl %[new], %[ptr]" \
+ CC_SET(z) \
+ : CC_OUT(z) (success), \
+ [ptr] "+m" (*__ptr), \
+ [old] "+a" (__old) \
+ : [new] "r" (__new) \
+ : "memory"); \
+ break; \
+ } \
+ case __X86_CASE_Q: \
+ { \
+ volatile u64 *__ptr = (volatile u64 *)(_ptr); \
+ asm volatile(lock "cmpxchgq %[new], %[ptr]" \
+ CC_SET(z) \
+ : CC_OUT(z) (success), \
+ [ptr] "+m" (*__ptr), \
+ [old] "+a" (__old) \
+ : [new] "r" (__new) \
+ : "memory"); \
+ break; \
+ } \
+ default: \
+ __cmpxchg_wrong_size(); \
+ } \
+ if (unlikely(!success)) \
+ *_old = __old; \
+ likely(success); \
+})
+
+#define __try_cmpxchg(ptr, pold, new, size) \
+ __raw_try_cmpxchg((ptr), (pold), (new), (size), LOCK_PREFIX)
+
+#define try_cmpxchg(ptr, pold, new) \
+ __try_cmpxchg((ptr), (pold), (new), sizeof(*(ptr)))
+
/*
* xadd() adds "inc" to "*ptr" and atomically returns the previous
* value of "*ptr".