[PATCH] x86: fix atomic64_xxx_cx8() functions

From: Eric Dumazet
Date: Tue Jan 03 2012 - 11:36:08 EST


It appears about all functions in arch/x86/lib/atomic64_cx8_32.S are
wrong in case cmpxchg8b must be restarted, because LOCK_PREFIX macro
defines a label "1" clashing with other local labels :

1:
some_instructions
LOCK_PREFIX
cmpxchg8b (%ebp)
jne 1b / jumps to beginning of LOCK_PREFIX !

A possible fix is to use a magic label "672" in LOCK_PREFIX asm
definition, similar to the "671" one we defined in LOCK_PREFIX_HERE.

Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Acked-by: Jan Beulich <JBeulich@xxxxxxxx>
CC: Christoph Lameter <cl@xxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxx>
CC: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx [2.6.35+]
---
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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