From 3c3b5c3b0bf798316a410e27e3d7e6f015663602 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Sat, 16 Aug 2008 03:39:26 -0400 Subject: [PATCH] x86: correct register constraints for 64-bit atomic operations x86_64 add/sub atomic ops does not seems to accept integer values bigger than 32 bits as immediates. Intel's add/sub documentation specifies they have to be passed as registers. The only operations in the x86-64 architecture which accept arbitrary 64-bit immediates is "movq" to any register; similarly, the only operation which accept arbitrary 64-bit displacement is "movabs" to or from al/ax/eax/rax. http://gcc.gnu.org/onlinedocs/gcc-4.3.0/gcc/Machine-Constraints.html states : e 32-bit signed integer constant, or a symbolic reference known to fit that range (for immediate operands in sign-extending x86-64 instructions). Z 32-bit unsigned integer constant, or a symbolic reference known to fit that range (for immediate operands in zero-extending x86-64 instructions). Since add/sub does sign extension, using the "e" constraint seems appropriate. It applies to 2.6.27-rc, 2.6.26, 2.6.25... Signed-off-by: Mathieu Desnoyers Signed-off-by: H. Peter Anvin Signed-off-by: Ingo Molnar --- include/asm-x86/atomic_64.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/include/asm-x86/atomic_64.h b/include/asm-x86/atomic_64.h index a0095191c02e..91c7d03e65bc 100644 --- a/include/asm-x86/atomic_64.h +++ b/include/asm-x86/atomic_64.h @@ -228,7 +228,7 @@ static inline void atomic64_add(long i, atomic64_t *v) { asm volatile(LOCK_PREFIX "addq %1,%0" : "=m" (v->counter) - : "ir" (i), "m" (v->counter)); + : "er" (i), "m" (v->counter)); } /** @@ -242,7 +242,7 @@ static inline void atomic64_sub(long i, atomic64_t *v) { asm volatile(LOCK_PREFIX "subq %1,%0" : "=m" (v->counter) - : "ir" (i), "m" (v->counter)); + : "er" (i), "m" (v->counter)); } /** @@ -260,7 +260,7 @@ static inline int atomic64_sub_and_test(long i, atomic64_t *v) asm volatile(LOCK_PREFIX "subq %2,%0; sete %1" : "=m" (v->counter), "=qm" (c) - : "ir" (i), "m" (v->counter) : "memory"); + : "er" (i), "m" (v->counter) : "memory"); return c; } @@ -341,7 +341,7 @@ static inline int atomic64_add_negative(long i, atomic64_t *v) asm volatile(LOCK_PREFIX "addq %2,%0; sets %1" : "=m" (v->counter), "=qm" (c) - : "ir" (i), "m" (v->counter) : "memory"); + : "er" (i), "m" (v->counter) : "memory"); return c; }