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percpu: Omit segment prefix in the UP case for cmpxchg_double

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Omit the segment prefix in the UP case. GS is not used then
and we will generate segfaults if cmpxchg16b is used otherwise.

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christoph Lameter
2011-03-26 20:57:18 -05:00
committed by Linus Torvalds
parent 76597cd314
commit d7c3f8cee8
2 changed files with 16 additions and 8 deletions
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14
arch/x86/lib/cmpxchg16b_emu.S
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@@ -10,6 +10,12 @@
#include <asm/frame.h>
#include <asm/dwarf2.h>
#ifdef CONFIG_SMP
#define SEG_PREFIX %gs:
#else
#define SEG_PREFIX
#endif
.text
/*
@@ -37,13 +43,13 @@ this_cpu_cmpxchg16b_emu:
pushf
cli
cmpq %gs:(%rsi), %rax
cmpq SEG_PREFIX(%rsi), %rax
jne not_same
cmpq %gs:8(%rsi), %rdx
cmpq SEG_PREFIX 8(%rsi), %rdx
jne not_same
movq %rbx, %gs:(%rsi)
movq %rcx, %gs:8(%rsi)
movq %rbx, SEG_PREFIX(%rsi)
movq %rcx, SEG_PREFIX 8(%rsi)
popf
mov $1, %al