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>
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@ -6,6 +6,7 @@
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/* Non-existant functions to indicate usage errors at link time. */
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/* Non-existant functions to indicate usage errors at link time. */
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extern void __xchg_wrong_size(void);
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extern void __xchg_wrong_size(void);
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extern void __cmpxchg_wrong_size(void);
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extern void __cmpxchg_wrong_size(void);
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extern void __xadd_wrong_size(void);
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/*
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/*
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* Constants for operation sizes. On 32-bit, the 64-bit size it set to
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* Constants for operation sizes. On 32-bit, the 64-bit size it set to
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@ -157,4 +158,46 @@ extern void __cmpxchg_wrong_size(void);
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__cmpxchg_local((ptr), (old), (new), sizeof(*ptr))
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__cmpxchg_local((ptr), (old), (new), sizeof(*ptr))
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#endif
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#endif
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#define __xadd(ptr, inc, lock) \
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({ \
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__typeof__ (*(ptr)) __ret = (inc); \
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switch (sizeof(*(ptr))) { \
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case __X86_CASE_B: \
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asm volatile (lock "xaddb %b0, %1\n" \
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: "+r" (__ret), "+m" (*(ptr)) \
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: : "memory", "cc"); \
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break; \
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case __X86_CASE_W: \
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asm volatile (lock "xaddw %w0, %1\n" \
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: "+r" (__ret), "+m" (*(ptr)) \
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: : "memory", "cc"); \
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break; \
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case __X86_CASE_L: \
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asm volatile (lock "xaddl %0, %1\n" \
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: "+r" (__ret), "+m" (*(ptr)) \
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: : "memory", "cc"); \
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break; \
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case __X86_CASE_Q: \
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asm volatile (lock "xaddq %q0, %1\n" \
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: "+r" (__ret), "+m" (*(ptr)) \
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: : "memory", "cc"); \
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break; \
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default: \
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__xadd_wrong_size(); \
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} \
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__ret; \
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})
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/*
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* xadd() adds "inc" to "*ptr" and atomically returns the previous
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* value of "*ptr".
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*
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* xadd() is locked when multiple CPUs are online
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* xadd_sync() is always locked
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* xadd_local() is never locked
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*/
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#define xadd(ptr, inc) __xadd((ptr), (inc), LOCK_PREFIX)
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#define xadd_sync(ptr, inc) __xadd((ptr), (inc), "lock; ")
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#define xadd_local(ptr, inc) __xadd((ptr), (inc), "")
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#endif /* ASM_X86_CMPXCHG_H */
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#endif /* ASM_X86_CMPXCHG_H */
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