Re: [PATCH] x86: fix and improve cmpxchg_double{,_local}()
From: Eric Dumazet <hidden>
Date: 2012-01-03 15:41:38
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lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
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