Messages in this thread Patch in this message | | | Date | Sat, 16 Aug 2008 03:39:26 -0400 | From | Mathieu Desnoyers <> | Subject | [PATCH] x86_64 : support atomic ops with 64 bits integer values |
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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.
http://gcc.gnu.org/onlinedocs/gcc-4.3.0/gcc/Machine-Constraints.html#Machine-Constraints
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 <mathieu.desnoyers@polymtl.ca> CC: Jeremy Fitzhardinge <jeremy@goop.org> CC: "H. Peter Anvin" <hpa@zytor.com> CC: Andrew Morton <akpm@linux-foundation.org> CC: Ingo Molnar <mingo@elte.hu> CC: Linus Torvalds <torvalds@linux-foundation.org> CC: Joe Perches <joe@perches.com> --- include/asm-x86/atomic_64.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
Index: linux-2.6-lttng/include/asm-x86/atomic_64.h =================================================================== --- linux-2.6-lttng.orig/include/asm-x86/atomic_64.h 2008-08-16 03:19:35.000000000 -0400 +++ linux-2.6-lttng/include/asm-x86/atomic_64.h 2008-08-16 03:21:18.000000000 -0400 @@ -228,7 +228,7 @@ static inline void atomic64_add(long i, { 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, { 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( 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( 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; } -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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