linux/arch/x86/include/asm/cmpxchg_64.h
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   1#ifndef _ASM_X86_CMPXCHG_64_H
   2#define _ASM_X86_CMPXCHG_64_H
   3
   4#include <asm/alternative.h> /* Provides LOCK_PREFIX */
   5
   6#define xchg(ptr, v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v), \
   7                                                 (ptr), sizeof(*(ptr))))
   8
   9#define __xg(x) ((volatile long *)(x))
  10
  11static inline void set_64bit(volatile unsigned long *ptr, unsigned long val)
  12{
  13        *ptr = val;
  14}
  15
  16#define _set_64bit set_64bit
  17
  18/*
  19 * Note: no "lock" prefix even on SMP: xchg always implies lock anyway
  20 * Note 2: xchg has side effect, so that attribute volatile is necessary,
  21 *        but generally the primitive is invalid, *ptr is output argument. --ANK
  22 */
  23static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
  24                                   int size)
  25{
  26        switch (size) {
  27        case 1:
  28                asm volatile("xchgb %b0,%1"
  29                             : "=q" (x)
  30                             : "m" (*__xg(ptr)), "0" (x)
  31                             : "memory");
  32                break;
  33        case 2:
  34                asm volatile("xchgw %w0,%1"
  35                             : "=r" (x)
  36                             : "m" (*__xg(ptr)), "0" (x)
  37                             : "memory");
  38                break;
  39        case 4:
  40                asm volatile("xchgl %k0,%1"
  41                             : "=r" (x)
  42                             : "m" (*__xg(ptr)), "0" (x)
  43                             : "memory");
  44                break;
  45        case 8:
  46                asm volatile("xchgq %0,%1"
  47                             : "=r" (x)
  48                             : "m" (*__xg(ptr)), "0" (x)
  49                             : "memory");
  50                break;
  51        }
  52        return x;
  53}
  54
  55/*
  56 * Atomic compare and exchange.  Compare OLD with MEM, if identical,
  57 * store NEW in MEM.  Return the initial value in MEM.  Success is
  58 * indicated by comparing RETURN with OLD.
  59 */
  60
  61#define __HAVE_ARCH_CMPXCHG 1
  62
  63static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
  64                                      unsigned long new, int size)
  65{
  66        unsigned long prev;
  67        switch (size) {
  68        case 1:
  69                asm volatile(LOCK_PREFIX "cmpxchgb %b1,%2"
  70                             : "=a"(prev)
  71                             : "q"(new), "m"(*__xg(ptr)), "0"(old)
  72                             : "memory");
  73                return prev;
  74        case 2:
  75                asm volatile(LOCK_PREFIX "cmpxchgw %w1,%2"
  76                             : "=a"(prev)
  77                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
  78                             : "memory");
  79                return prev;
  80        case 4:
  81                asm volatile(LOCK_PREFIX "cmpxchgl %k1,%2"
  82                             : "=a"(prev)
  83                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
  84                             : "memory");
  85                return prev;
  86        case 8:
  87                asm volatile(LOCK_PREFIX "cmpxchgq %1,%2"
  88                             : "=a"(prev)
  89                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
  90                             : "memory");
  91                return prev;
  92        }
  93        return old;
  94}
  95
  96/*
  97 * Always use locked operations when touching memory shared with a
  98 * hypervisor, since the system may be SMP even if the guest kernel
  99 * isn't.
 100 */
 101static inline unsigned long __sync_cmpxchg(volatile void *ptr,
 102                                           unsigned long old,
 103                                           unsigned long new, int size)
 104{
 105        unsigned long prev;
 106        switch (size) {
 107        case 1:
 108                asm volatile("lock; cmpxchgb %b1,%2"
 109                             : "=a"(prev)
 110                             : "q"(new), "m"(*__xg(ptr)), "0"(old)
 111                             : "memory");
 112                return prev;
 113        case 2:
 114                asm volatile("lock; cmpxchgw %w1,%2"
 115                             : "=a"(prev)
 116                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
 117                             : "memory");
 118                return prev;
 119        case 4:
 120                asm volatile("lock; cmpxchgl %1,%2"
 121                             : "=a"(prev)
 122                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
 123                             : "memory");
 124                return prev;
 125        }
 126        return old;
 127}
 128
 129static inline unsigned long __cmpxchg_local(volatile void *ptr,
 130                                            unsigned long old,
 131                                            unsigned long new, int size)
 132{
 133        unsigned long prev;
 134        switch (size) {
 135        case 1:
 136                asm volatile("cmpxchgb %b1,%2"
 137                             : "=a"(prev)
 138                             : "q"(new), "m"(*__xg(ptr)), "0"(old)
 139                             : "memory");
 140                return prev;
 141        case 2:
 142                asm volatile("cmpxchgw %w1,%2"
 143                             : "=a"(prev)
 144                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
 145                             : "memory");
 146                return prev;
 147        case 4:
 148                asm volatile("cmpxchgl %k1,%2"
 149                             : "=a"(prev)
 150                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
 151                             : "memory");
 152                return prev;
 153        case 8:
 154                asm volatile("cmpxchgq %1,%2"
 155                             : "=a"(prev)
 156                             : "r"(new), "m"(*__xg(ptr)), "0"(old)
 157                             : "memory");
 158                return prev;
 159        }
 160        return old;
 161}
 162
 163#define cmpxchg(ptr, o, n)                                              \
 164        ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o),       \
 165                                       (unsigned long)(n), sizeof(*(ptr))))
 166#define cmpxchg64(ptr, o, n)                                            \
 167({                                                                      \
 168        BUILD_BUG_ON(sizeof(*(ptr)) != 8);                              \
 169        cmpxchg((ptr), (o), (n));                                       \
 170})
 171#define cmpxchg_local(ptr, o, n)                                        \
 172        ((__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o), \
 173                                             (unsigned long)(n),        \
 174                                             sizeof(*(ptr))))
 175#define sync_cmpxchg(ptr, o, n)                                         \
 176        ((__typeof__(*(ptr)))__sync_cmpxchg((ptr), (unsigned long)(o),  \
 177                                            (unsigned long)(n),         \
 178                                            sizeof(*(ptr))))
 179#define cmpxchg64_local(ptr, o, n)                                      \
 180({                                                                      \
 181        BUILD_BUG_ON(sizeof(*(ptr)) != 8);                              \
 182        cmpxchg_local((ptr), (o), (n));                                 \
 183})
 184
 185#endif /* _ASM_X86_CMPXCHG_64_H */
 186