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SubjectRe: [PATCH] x86: fix and improve cmpxchg_double{,_local}()
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Le mardi 03 janvier 2012 à 16:15 +0100, Eric Dumazet a écrit :

> Very old it seems...
>
> arch/x86/lib/atomic64_cx8_32.S
>
> all "jxx 1b" are wrong if a LOCK_PREFIX is included after the 1: label
>
> 1:
> inst1
> LOCK_PREFIX
> cmpxchg8b (%ebp)
> jne 1b / jumps to beginning of LOCK_PREFIX, inst1 is not replayed
>
>
>
>

A possible fix would be to not use "1" label in LOCK_PREFIX macro,
but 672 magic value.

Not sure if we can use a local label in a macro ?

arch/x86/include/asm/alternative-asm.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/alternative-asm.h b/arch/x86/include/asm/alternative-asm.h
index 091508b..952bd01 100644
--- a/arch/x86/include/asm/alternative-asm.h
+++ b/arch/x86/include/asm/alternative-asm.h
@@ -4,10 +4,10 @@

#ifdef CONFIG_SMP
.macro LOCK_PREFIX
-1: lock
+672: lock
.section .smp_locks,"a"
.balign 4
- .long 1b - .
+ .long 672b - .
.previous
.endm
#else

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