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| author | H. Peter Anvin <hpa@zytor.com> | 2010-07-27 17:01:49 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2010-07-27 17:14:02 -0700 |
| commit | 113fc5a6e8c2288619ff7e8187a6f556b7e0d372 (patch) | |
| tree | 84393467b2174c05e7240db72ffa55ce3da67a70 /arch/x86/include/asm/cmpxchg_64.h | |
| parent | fc0f5ac8fe693d1b05f5a928cc48135d1c8b7f2e (diff) | |
| download | linux-0-day-113fc5a6e8c2288619ff7e8187a6f556b7e0d372.tar.gz linux-0-day-113fc5a6e8c2288619ff7e8187a6f556b7e0d372.tar.xz | |
x86: Add memory modify constraints to xchg() and cmpxchg()
xchg() and cmpxchg() modify their memory operands, not merely read
them. For some versions of gcc the "memory" clobber has apparently
dealt with the situation, but not for all.
Originally-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Glauber Costa <glommer@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Peter Palfrader <peter@palfrader.org>
Cc: Greg KH <gregkh@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Zachary Amsden <zamsden@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: <stable@kernel.org>
LKML-Reference: <4C4F7277.8050306@zytor.com>
Diffstat (limited to 'arch/x86/include/asm/cmpxchg_64.h')
| -rw-r--r-- | arch/x86/include/asm/cmpxchg_64.h | 40 |
1 files changed, 20 insertions, 20 deletions
diff --git a/arch/x86/include/asm/cmpxchg_64.h b/arch/x86/include/asm/cmpxchg_64.h index 485ae415faecd..b92f147339f39 100644 --- a/arch/x86/include/asm/cmpxchg_64.h +++ b/arch/x86/include/asm/cmpxchg_64.h @@ -26,26 +26,26 @@ extern void __cmpxchg_wrong_size(void); switch (size) { \ case 1: \ asm volatile("xchgb %b0,%1" \ - : "=q" (__x) \ - : "m" (*__xg(ptr)), "0" (__x) \ + : "=q" (__x), "+m" (*__xg(ptr)) \ + : "0" (__x) \ : "memory"); \ break; \ case 2: \ asm volatile("xchgw %w0,%1" \ - : "=r" (__x) \ - : "m" (*__xg(ptr)), "0" (__x) \ + : "=r" (__x), "+m" (*__xg(ptr)) \ + : "0" (__x) \ : "memory"); \ break; \ case 4: \ asm volatile("xchgl %k0,%1" \ - : "=r" (__x) \ - : "m" (*__xg(ptr)), "0" (__x) \ + : "=r" (__x), "+m" (*__xg(ptr)) \ + : "0" (__x) \ : "memory"); \ break; \ case 8: \ asm volatile("xchgq %0,%1" \ - : "=r" (__x) \ - : "m" (*__xg(ptr)), "0" (__x) \ + : "=r" (__x), "+m" (*__xg(ptr)) \ + : "0" (__x) \ : "memory"); \ break; \ default: \ @@ -71,27 +71,27 @@ extern void __cmpxchg_wrong_size(void); __typeof__(*(ptr)) __new = (new); \ switch (size) { \ case 1: \ - asm volatile(lock "cmpxchgb %b1,%2" \ - : "=a"(__ret) \ - : "q"(__new), "m"(*__xg(ptr)), "0"(__old) \ + asm volatile(lock "cmpxchgb %b2,%1" \ + : "=a" (__ret), "+m" (*__xg(ptr)) \ + : "q" (__new), "0" (__old) \ : "memory"); \ break; \ case 2: \ - asm volatile(lock "cmpxchgw %w1,%2" \ - : "=a"(__ret) \ - : "r"(__new), "m"(*__xg(ptr)), "0"(__old) \ + asm volatile(lock "cmpxchgw %w2,%1" \ + : "=a" (__ret), "+m" (*__xg(ptr)) \ + : "r" (__new), "0" (__old) \ : "memory"); \ break; \ case 4: \ - asm volatile(lock "cmpxchgl %k1,%2" \ - : "=a"(__ret) \ - : "r"(__new), "m"(*__xg(ptr)), "0"(__old) \ + asm volatile(lock "cmpxchgl %k2,%1" \ + : "=a" (__ret), "+m" (*__xg(ptr)) \ + : "r" (__new), "0" (__old) \ : "memory"); \ break; \ case 8: \ - asm volatile(lock "cmpxchgq %1,%2" \ - : "=a"(__ret) \ - : "r"(__new), "m"(*__xg(ptr)), "0"(__old) \ + asm volatile(lock "cmpxchgq %2,%1" \ + : "=a" (__ret), "+m" (*__xg(ptr)) \ + : "r" (__new), "0" (__old) \ : "memory"); \ break; \ default: \ |