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authorChristoph Lameter <cl@linux.com>2011-03-27 05:57:18 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2011-03-28 06:25:36 +0400
commitd7c3f8cee81f4548de0513403b74131aee655576 (patch)
tree3512188d9be3e429284d094d4bc1fdc2299b92db /arch/x86/lib/cmpxchg16b_emu.S
parent76597cd31470fa130784c78fadb4dab2e624a723 (diff)
downloadlinux-d7c3f8cee81f4548de0513403b74131aee655576.tar.xz
percpu: Omit segment prefix in the UP case for cmpxchg_double
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>
Diffstat (limited to 'arch/x86/lib/cmpxchg16b_emu.S')
-rw-r--r--arch/x86/lib/cmpxchg16b_emu.S14
1 files changed, 10 insertions, 4 deletions
diff --git a/arch/x86/lib/cmpxchg16b_emu.S b/arch/x86/lib/cmpxchg16b_emu.S
index 3e8b08a6de2b..1e572c507d06 100644
--- a/arch/x86/lib/cmpxchg16b_emu.S
+++ b/arch/x86/lib/cmpxchg16b_emu.S
@@ -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