diff options
| author | Jeremy Fitzhardinge <jeremy@goop.org> | 2008-06-25 00:19:10 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-07-08 13:10:58 +0200 |
| commit | 15878c0b21b7b04a08108e9027ebbbd68a2502e0 (patch) | |
| tree | 8f353123bdf455547807b0dec347e8d0618b4b6b /include | |
| parent | 102e3b8d3f3d5556c60f9ab6d92108649b68edc8 (diff) | |
x86, 64-bit: add sync_cmpxchg
Add sync_cmpxchg to match 32-bit's sync_cmpxchg.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include')
| -rw-r--r-- | include/asm-x86/cmpxchg_64.h | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/include/asm-x86/cmpxchg_64.h b/include/asm-x86/cmpxchg_64.h index d9b26b9a28c..17463ccf816 100644 --- a/include/asm-x86/cmpxchg_64.h +++ b/include/asm-x86/cmpxchg_64.h @@ -93,6 +93,39 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, return old; } +/* + * Always use locked operations when touching memory shared with a + * hypervisor, since the system may be SMP even if the guest kernel + * isn't. + */ +static inline unsigned long __sync_cmpxchg(volatile void *ptr, + unsigned long old, + unsigned long new, int size) +{ + unsigned long prev; + switch (size) { + case 1: + asm volatile("lock; cmpxchgb %b1,%2" + : "=a"(prev) + : "q"(new), "m"(*__xg(ptr)), "0"(old) + : "memory"); + return prev; + case 2: + asm volatile("lock; cmpxchgw %w1,%2" + : "=a"(prev) + : "r"(new), "m"(*__xg(ptr)), "0"(old) + : "memory"); + return prev; + case 4: + asm volatile("lock; cmpxchgl %1,%2" + : "=a"(prev) + : "r"(new), "m"(*__xg(ptr)), "0"(old) + : "memory"); + return prev; + } + return old; +} + static inline unsigned long __cmpxchg_local(volatile void *ptr, unsigned long old, unsigned long new, int size) @@ -139,6 +172,10 @@ static inline unsigned long __cmpxchg_local(volatile void *ptr, ((__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o), \ (unsigned long)(n), \ sizeof(*(ptr)))) +#define sync_cmpxchg(ptr, o, n) \ + ((__typeof__(*(ptr)))__sync_cmpxchg((ptr), (unsigned long)(o), \ + (unsigned long)(n), \ + sizeof(*(ptr)))) #define cmpxchg64_local(ptr, o, n) \ ({ \ BUILD_BUG_ON(sizeof(*(ptr)) != 8); \ |