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Commit 433b3520 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by H. Peter Anvin
Browse files

x86: Add xadd helper macro 



Add a common xadd implementation.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Link: http://lkml.kernel.org/r/4E5BCC40.3030501@goop.org


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent e9826380

arch/x86/include/asm/cmpxchg.h

+43 −0
Original line number Diff line number Diff line
@@ -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 */