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x86: Use correct byte-sized register constraint in __xchg_op()

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x86-64 can access the low half of any register, but i386 can only do
it with a subset of registers.  'r' causes compilation failures on i386,
but 'q' expresses the constraint properly.

Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/4F7A3315.501@goop.org
Reported-by: Leigh Scott <leigh123linux@googlemail.com>
Tested-by: Thomas Reitmayr <treitmayr@devbase.at>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: <stable@vger.kernel.org> v3.3
This commit is contained in:
Jeremy Fitzhardinge 2012-04-02 16:15:33 -07:00 committed by H. Peter Anvin
parent 46ed99d1b7
commit 2ca052a371
1 changed files with 1 additions and 1 deletions
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arch/x86/include/asm/cmpxchg.h
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@ -43,7 +43,7 @@ extern void __add_wrong_size(void)
switch (sizeof(*(ptr))) { \
case __X86_CASE_B: \
asm volatile (lock #op "b %b0, %1\n" \
: "+r" (__ret), "+m" (*(ptr)) \
: "+q" (__ret), "+m" (*(ptr)) \
: : "memory", "cc"); \
break; \
case __X86_CASE_W: \