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| author | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2011-06-21 12:00:55 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2011-08-29 13:42:20 -0700 |
| commit | 433b3520616be694e0aa777089346c8718c91a7b (patch) | |
| tree | 0d73d7efc65c550a02535c0f10265807402e3617 | |
| parent | e9826380d83d1bda3ee5663bf3fa4667a6fbe60a (diff) | |
| download | lwn-433b3520616be694e0aa777089346c8718c91a7b.tar.gz lwn-433b3520616be694e0aa777089346c8718c91a7b.zip | |
x86: Add xadd helper macro
Add a common xadd implementation.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Link: http://lkml.kernel.org/r/4E5BCC40.3030501@goop.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
| -rw-r--r-- | arch/x86/include/asm/cmpxchg.h | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h index efe3ec778a58..0d0d9cdd3309 100644 --- a/arch/x86/include/asm/cmpxchg.h +++ b/arch/x86/include/asm/cmpxchg.h @@ -6,6 +6,7 @@ /* Non-existant functions to indicate usage errors at link time. */ extern void __xchg_wrong_size(void); extern void __cmpxchg_wrong_size(void); +extern void __xadd_wrong_size(void); /* * Constants for operation sizes. On 32-bit, the 64-bit size it set to @@ -157,4 +158,46 @@ extern void __cmpxchg_wrong_size(void); __cmpxchg_local((ptr), (old), (new), sizeof(*ptr)) #endif +#define __xadd(ptr, inc, lock) \ + ({ \ + __typeof__ (*(ptr)) __ret = (inc); \ + switch (sizeof(*(ptr))) { \ + case __X86_CASE_B: \ + asm volatile (lock "xaddb %b0, %1\n" \ + : "+r" (__ret), "+m" (*(ptr)) \ + : : "memory", "cc"); \ + break; \ + case __X86_CASE_W: \ + asm volatile (lock "xaddw %w0, %1\n" \ + : "+r" (__ret), "+m" (*(ptr)) \ + : : "memory", "cc"); \ + break; \ + case __X86_CASE_L: \ + asm volatile (lock "xaddl %0, %1\n" \ + : "+r" (__ret), "+m" (*(ptr)) \ + : : "memory", "cc"); \ + break; \ + case __X86_CASE_Q: \ + asm volatile (lock "xaddq %q0, %1\n" \ + : "+r" (__ret), "+m" (*(ptr)) \ + : : "memory", "cc"); \ + break; \ + default: \ + __xadd_wrong_size(); \ + } \ + __ret; \ + }) + +/* + * xadd() adds "inc" to "*ptr" and atomically returns the previous + * value of "*ptr". + * + * xadd() is locked when multiple CPUs are online + * xadd_sync() is always locked + * xadd_local() is never locked + */ +#define xadd(ptr, inc) __xadd((ptr), (inc), LOCK_PREFIX) +#define xadd_sync(ptr, inc) __xadd((ptr), (inc), "lock; ") +#define xadd_local(ptr, inc) __xadd((ptr), (inc), "") + #endif /* ASM_X86_CMPXCHG_H */ |