x86: Add xadd helper macro

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Link: http://lkml.kernel.org/r/ce03e48f4b70a2a31accf32c8b41b781674e57c3.1308878118.git.jeremy.fitzhardinge@citrix.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/include/asm/cmpxchg_32.h b/arch/x86/include/asm/cmpxchg_32.h
index 284a6e8f7ce167e8e854f47db895a44ee2cfbefa..30f0318bccdd3df69f4bd8140d220fe59f0607ac 100644 (file)
--- 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 423ae58aa0203cf2116b8474609c848ba70694c7..62da1ffc9a310b160b97c94c76a9f514d0c60eff 100644 (file)
--- 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 */