x86: spinlock use LOCK_PREFIX
Since we are now using DS prefixes instead of NOP to remove LOCK
prefixes, there is no longer any problems with instruction boundaries
moving around.
* Linus Torvalds (torvalds@linux-foundation.org) wrote:
>
>
> On Thu, 14 Aug 2008, Mathieu Desnoyers wrote:
> >
> > Changing the 0x90 (single-byte nop) currently used into a 0x3E DS segment
> > override prefix should fix this issue. Since the default of the atomic
> > instructions is to use the DS segment anyway, it should not affect the
> > behavior.
>
> Ok, so I think this is an _excellent_ patch, but I'd like to also then use
> LOCK_PREFIX in include/asm-x86/futex.h.
>
> See commit 9d55b9923a1b7ea8193b8875c57ec940dc2ff027.
>
> Linus
Unless there a rationale for this, I think these be changed to LOCK_PREFIX
too.
grep "lock ;" include/asm-x86/spinlock.h
"lock ; cmpxchgw %w1,%2\n\t"
asm volatile("lock ; xaddl %0, %1\n"
"lock ; cmpxchgl %1,%2\n\t"
Applies to 2.6.27-rc2.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
CC: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/include/asm-x86/spinlock.h b/include/asm-x86/spinlock.h
index 4f9a986..0b4d59a 100644
--- a/include/asm-x86/spinlock.h
+++ b/include/asm-x86/spinlock.h
@@ -97,7 +97,7 @@
"jne 1f\n\t"
"movw %w0,%w1\n\t"
"incb %h1\n\t"
- "lock ; cmpxchgw %w1,%2\n\t"
+ LOCK_PREFIX "cmpxchgw %w1,%2\n\t"
"1:"
"sete %b1\n\t"
"movzbl %b1,%0\n\t"
@@ -135,7 +135,7 @@
int inc = 0x00010000;
int tmp;
- asm volatile("lock ; xaddl %0, %1\n"
+ asm volatile(LOCK_PREFIX "xaddl %0, %1\n"
"movzwl %w0, %2\n\t"
"shrl $16, %0\n\t"
"1:\t"
@@ -162,7 +162,7 @@
"cmpl %0,%1\n\t"
"jne 1f\n\t"
"addl $0x00010000, %1\n\t"
- "lock ; cmpxchgl %1,%2\n\t"
+ LOCK_PREFIX "cmpxchgl %1,%2\n\t"
"1:"
"sete %b1\n\t"
"movzbl %b1,%0\n\t"