Commit 2ca052a3 authored Apr 02, 2012 by Jeremy Fitzhardinge Committed by H. Peter Anvin Apr 06, 2012

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



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

parent 46ed99d1

arch/x86/include/asm/cmpxchg.h

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -43,7 +43,7 @@ extern void __add_wrong_size(void)
	switch (sizeof(*(ptr))) { \		switch (sizeof(*(ptr))) { \
	case __X86_CASE_B: \		case __X86_CASE_B: \
	asm volatile (lock #op "b %b0, %1\n" \		asm volatile (lock #op "b %b0, %1\n" \
	: "+r" (__ret), "+m" (*(ptr)) \		: "+q" (__ret), "+m" (*(ptr)) \
	: : "memory", "cc"); \		: : "memory", "cc"); \
	break; \		break; \
	case __X86_CASE_W: \		case __X86_CASE_W: \