root/include/asm-x86/cmpxchg_64.h

INCLUDED FROM

DEFINITIONS

1. set_64bit
2. __xchg
3. __cmpxchg
4. __sync_cmpxchg
5. __cmpxchg_local

#ifndef ASM_X86__CMPXCHG_64_H
#define ASM_X86__CMPXCHG_64_H

#include <asm/alternative.h> /* Provides LOCK_PREFIX */

#define xchg(ptr, v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v), \
                                                 (ptr), sizeof(*(ptr))))

#define __xg(x) ((volatile long *)(x))

static inline void set_64bit(volatile unsigned long *ptr, unsigned long val)
{
        *ptr = val;
}

#define _set_64bit set_64bit

/*
 * Note: no "lock" prefix even on SMP: xchg always implies lock anyway
 * Note 2: xchg has side effect, so that attribute volatile is necessary,
 *        but generally the primitive is invalid, *ptr is output argument. --ANK
 */
static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
                                   int size)
{
        switch (size) {
        case 1:
                asm volatile("xchgb %b0,%1"
                             : "=q" (x)
                             : "m" (*__xg(ptr)), "0" (x)
                             : "memory");
                break;
        case 2:
                asm volatile("xchgw %w0,%1"
                             : "=r" (x)
                             : "m" (*__xg(ptr)), "0" (x)
                             : "memory");
                break;
        case 4:
                asm volatile("xchgl %k0,%1"
                             : "=r" (x)
                             : "m" (*__xg(ptr)), "0" (x)
                             : "memory");
                break;
        case 8:
                asm volatile("xchgq %0,%1"
                             : "=r" (x)
                             : "m" (*__xg(ptr)), "0" (x)
                             : "memory");
                break;
        }
        return x;
}

/*
 * Atomic compare and exchange.  Compare OLD with MEM, if identical,
 * store NEW in MEM.  Return the initial value in MEM.  Success is
 * indicated by comparing RETURN with OLD.
 */

#define __HAVE_ARCH_CMPXCHG 1

static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
                                      unsigned long new, int size)
{
        unsigned long prev;
        switch (size) {
        case 1:
                asm volatile(LOCK_PREFIX "cmpxchgb %b1,%2"
                             : "=a"(prev)
                             : "q"(new), "m"(*__xg(ptr)), "0"(old)
                             : "memory");
                return prev;
        case 2:
                asm volatile(LOCK_PREFIX "cmpxchgw %w1,%2"
                             : "=a"(prev)
                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
                             : "memory");
                return prev;
        case 4:
                asm volatile(LOCK_PREFIX "cmpxchgl %k1,%2"
                             : "=a"(prev)
                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
                             : "memory");
                return prev;
        case 8:
                asm volatile(LOCK_PREFIX "cmpxchgq %1,%2"
                             : "=a"(prev)
                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
                             : "memory");
                return prev;
        }
        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)
{
        unsigned long prev;
        switch (size) {
        case 1:
                asm volatile("cmpxchgb %b1,%2"
                             : "=a"(prev)
                             : "q"(new), "m"(*__xg(ptr)), "0"(old)
                             : "memory");
                return prev;
        case 2:
                asm volatile("cmpxchgw %w1,%2"
                             : "=a"(prev)
                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
                             : "memory");
                return prev;
        case 4:
                asm volatile("cmpxchgl %k1,%2"
                             : "=a"(prev)
                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
                             : "memory");
                return prev;
        case 8:
                asm volatile("cmpxchgq %1,%2"
                             : "=a"(prev)
                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
                             : "memory");
                return prev;
        }
        return old;
}

#define cmpxchg(ptr, o, n)                                              \
        ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o),       \
                                       (unsigned long)(n), sizeof(*(ptr))))
#define cmpxchg64(ptr, o, n)                                            \
({                                                                      \
        BUILD_BUG_ON(sizeof(*(ptr)) != 8);                              \
        cmpxchg((ptr), (o), (n));                                       \
})
#define cmpxchg_local(ptr, o, n)                                        \
        ((__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);                              \
        cmpxchg_local((ptr), (o), (n));                                 \
})

#endif /* ASM_X86__CMPXCHG_64_H */