arch/mips/include/asm/cmpxchg.h

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 2003, 06, 07 by Ralf Baechle (ralf@linux-mips.org)
   7  */
   8 #ifndef __ASM_CMPXCHG_H
   9 #define __ASM_CMPXCHG_H
  10
  11 #include <linux/irqflags.h>
  12
  13 #define __HAVE_ARCH_CMPXCHG 1
  14
  15 #define __cmpxchg_asm(ld, st, m, old, new)                              \
  16 ({                                                                      \
  17         __typeof(*(m)) __ret;                                           \
  18                                                                         \
  19         if (kernel_uses_llsc && R10000_LLSC_WAR) {                      \
  20                 __asm__ __volatile__(                                   \
  21                 "       .set    push                            \n"     \
  22                 "       .set    noat                            \n"     \
  23                 "       .set    mips3                           \n"     \
  24                 "1:     " ld "  %0, %2          # __cmpxchg_asm \n"     \
  25                 "       bne     %0, %z3, 2f                     \n"     \
  26                 "       .set    mips0                           \n"     \
  27                 "       move    $1, %z4                         \n"     \
  28                 "       .set    mips3                           \n"     \
  29                 "       " st "  $1, %1                          \n"     \
  30                 "       beqzl   $1, 1b                          \n"     \
  31                 "2:                                             \n"     \
  32                 "       .set    pop                             \n"     \
  33                 : "=&r" (__ret), "=R" (*m)                              \
  34                 : "R" (*m), "Jr" (old), "Jr" (new)                      \
  35                 : "memory");                                            \
  36         } else if (kernel_uses_llsc) {                                  \
  37                 __asm__ __volatile__(                                   \
  38                 "       .set    push                            \n"     \
  39                 "       .set    noat                            \n"     \
  40                 "       .set    mips3                           \n"     \
  41                 "1:     " ld "  %0, %2          # __cmpxchg_asm \n"     \
  42                 "       bne     %0, %z3, 2f                     \n"     \
  43                 "       .set    mips0                           \n"     \
  44                 "       move    $1, %z4                         \n"     \
  45                 "       .set    mips3                           \n"     \
  46                 "       " st "  $1, %1                          \n"     \
  47                 "       beqz    $1, 1b                          \n"     \
  48                 "       .set    pop                             \n"     \
  49                 "2:                                             \n"     \
  50                 : "=&r" (__ret), "=R" (*m)                              \
  51                 : "R" (*m), "Jr" (old), "Jr" (new)                      \
  52                 : "memory");                                            \
  53         } else {                                                        \
  54                 unsigned long __flags;                                  \
  55                                                                         \
  56                 raw_local_irq_save(__flags);                            \
  57                 __ret = *m;                                             \
  58                 if (__ret == old)                                       \
  59                         *m = new;                                       \
  60                 raw_local_irq_restore(__flags);                         \
  61         }                                                               \
  62                                                                         \
  63         __ret;                                                          \
  64 })
  65
  66 /*
  67  * This function doesn't exist, so you'll get a linker error
  68  * if something tries to do an invalid cmpxchg().
  69  */
  70 extern void __cmpxchg_called_with_bad_pointer(void);
  71
  72 #define __cmpxchg(ptr, old, new, pre_barrier, post_barrier)             \
  73 ({                                                                      \
  74         __typeof__(ptr) __ptr = (ptr);                                  \
  75         __typeof__(*(ptr)) __old = (old);                               \
  76         __typeof__(*(ptr)) __new = (new);                               \
  77         __typeof__(*(ptr)) __res = 0;                                   \
  78                                                                         \
  79         pre_barrier;                                                    \
  80                                                                         \
  81         switch (sizeof(*(__ptr))) {                                     \
  82         case 4:                                                         \
  83                 __res = __cmpxchg_asm("ll", "sc", __ptr, __old, __new); \
  84                 break;                                                  \
  85         case 8:                                                         \
  86                 if (sizeof(long) == 8) {                                \
  87                         __res = __cmpxchg_asm("lld", "scd", __ptr,      \
  88                                            __old, __new);               \
  89                         break;                                          \
  90                 }                                                       \
  91         default:                                                        \
  92                 __cmpxchg_called_with_bad_pointer();                    \
  93                 break;                                                  \
  94         }                                                               \
  95                                                                         \
  96         post_barrier;                                                   \
  97                                                                         \
  98         __res;                                                          \
  99 })
 100
 101 #define cmpxchg(ptr, old, new)          __cmpxchg(ptr, old, new, smp_mb__before_llsc(), smp_llsc_mb())
 102 #define cmpxchg_local(ptr, old, new)    __cmpxchg(ptr, old, new, , )
 103
 104 #define cmpxchg64(ptr, o, n)                                            \
 105   ({                                                                    \
 106         BUILD_BUG_ON(sizeof(*(ptr)) != 8);                              \
 107         cmpxchg((ptr), (o), (n));                                       \
 108   })
 109
 110 #ifdef CONFIG_64BIT
 111 #define cmpxchg64_local(ptr, o, n)                                      \
 112   ({                                                                    \
 113         BUILD_BUG_ON(sizeof(*(ptr)) != 8);                              \
 114         cmpxchg_local((ptr), (o), (n));                                 \
 115   })
 116 #else
 117 #include <asm-generic/cmpxchg-local.h>
 118 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
 119 #endif
 120
 121 #endif /* __ASM_CMPXCHG_H */