diff options
| author | Chris Wright <chrisw@sous-sol.org> | 2006-09-25 23:32:23 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-09-26 08:48:55 -0700 |
| commit | 027a8c7e6067a1bcdef6775d1b1c08729dfbae51 (patch) | |
| tree | 8c791bb8820d6c0734aded634a045369dd3347cc /include/asm-i386/system.h | |
| parent | 05f4a3ec94281347e05c81eafefcfe5ea545c94c (diff) | |
[PATCH] x86: implement always-locked bit ops, for memory shared with an SMP hypervisor
Add "always lock'd" implementations of set_bit, clear_bit and change_bit and
the corresponding test_and_ functions. Also add "always lock'd"
implementation of cmpxchg. These give guaranteed strong synchronisation and
are required for non-SMP kernels running on an SMP hypervisor.
Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/asm-i386/system.h')
| -rw-r--r-- | include/asm-i386/system.h | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h index 098bcee94e3..a6dabbcd6e6 100644 --- a/include/asm-i386/system.h +++ b/include/asm-i386/system.h @@ -267,6 +267,9 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz #define cmpxchg(ptr,o,n)\ ((__typeof__(*(ptr)))__cmpxchg((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)))) #endif static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, @@ -296,6 +299,39 @@ 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; +} + #ifndef CONFIG_X86_CMPXCHG /* * Building a kernel capable running on 80386. It may be necessary to |