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Commit 15878c0b authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Ingo Molnar
Browse files

x86, 64-bit: add sync_cmpxchg 



Add sync_cmpxchg to match 32-bit's sync_cmpxchg.

Signed-off-by: default avatarJeremy 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: default avatarIngo Molnar <mingo@elte.hu>
parent 102e3b8d

include/asm-x86/cmpxchg_64.h

+37 −0
Original line number Diff line number Diff line
@@ -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);				\