[PATCH 7/8] x86: add xadd helper macro

[Jeremy Fitzhardinge]

From: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
 arch/x86/include/asm/cmpxchg_32.h |   21 +++++++++++++++++++++
 arch/x86/include/asm/cmpxchg_64.h |   26 ++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/cmpxchg_32.h b/arch/x86/include/asm/cmpxchg_32.h
index 284a6e8..30f0318 100644
--- a/arch/x86/include/asm/cmpxchg_32.h
+++ b/arch/x86/include/asm/cmpxchg_32.h
@@ -280,4 +280,25 @@ static inline unsigned long cmpxchg_386(volatile void *ptr, unsigned long old,
 
 #endif
 
+#define xadd(ptr, inc)							\
+	do {								\
+		switch (sizeof(*(ptr))) {				\
+		case 1:							\
+			asm volatile (LOCK_PREFIX "xaddb %b0, %1\n"	\
+				      : "+r" (inc), "+m" (*(ptr))	\
+				      : : "memory", "cc");		\
+			break;						\
+		case 2:							\
+			asm volatile (LOCK_PREFIX "xaddw %w0, %1\n"	\
+				      : "+r" (inc), "+m" (*(ptr))	\
+				      : : "memory", "cc");		\
+			break;						\
+		case 4:							\
+			asm volatile (LOCK_PREFIX "xaddl %0, %1\n"	\
+				      : "+r" (inc), "+m" (*(ptr))	\
+				      : : "memory", "cc");		\
+			break;						\
+		}							\
+	} while(0)
+
 #endif /* _ASM_X86_CMPXCHG_32_H */
diff --git a/arch/x86/include/asm/cmpxchg_64.h b/arch/x86/include/asm/cmpxchg_64.h
index 423ae58..62da1ff 100644
--- a/arch/x86/include/asm/cmpxchg_64.h
+++ b/arch/x86/include/asm/cmpxchg_64.h
@@ -151,4 +151,30 @@ extern void __cmpxchg_wrong_size(void);
 	cmpxchg_local((ptr), (o), (n));					\
 })
 
+#define xadd(ptr, inc)							\
+	do {								\
+		switch (sizeof(*(ptr))) {				\
+		case 1:							\
+			asm volatile (LOCK_PREFIX "xaddb %b0, %1\n"	\
+				      : "+r" (inc), "+m" (*(ptr))	\
+				      : : "memory", "cc");		\
+			break;						\
+		case 2:							\
+			asm volatile (LOCK_PREFIX "xaddw %w0, %1\n"	\
+				      : "+r" (inc), "+m" (*(ptr))	\
+				      : : "memory", "cc");		\
+			break;						\
+		case 4:							\
+			asm volatile (LOCK_PREFIX "xaddl %0, %1\n"	\
+				      : "+r" (inc), "+m" (*(ptr))	\
+				      : : "memory", "cc");		\
+			break;						\
+		case 8:							\
+			asm volatile (LOCK_PREFIX "xaddq %q0, %1\n"	\
+				      : "+r" (inc), "+m" (*(ptr))	\
+				      : : "memory", "cc");		\
+			break;						\
+		}							\
+	} while(0)
+
 #endif /* _ASM_X86_CMPXCHG_64_H */
-- 
1.7.5.4

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