x86: Fix atomic64_xxx_cx8() functions
Eric Dumazet [Tue, 3 Jan 2012 16:35:40 +0000 (17:35 +0100)]
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@gmail.com>
Acked-by: Jan Beulich <JBeulich@suse.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1325608540.2320.103.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/alternative-asm.h

index 091508b..952bd01 100644 (file)
@@ -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