arch/x86/include/asm/local.h

   1 #ifndef _ASM_X86_LOCAL_H
   2 #define _ASM_X86_LOCAL_H
   3
   4 #include <linux/percpu.h>
   5
   6 #include <linux/atomic.h>
   7 #include <asm/asm.h>
   8
   9 typedef struct {
  10         atomic_long_t a;
  11 } local_t;
  12
  13 #define LOCAL_INIT(i)   { ATOMIC_LONG_INIT(i) }
  14
  15 #define local_read(l)   atomic_long_read(&(l)->a)
  16 #define local_set(l, i) atomic_long_set(&(l)->a, (i))
  17
  18 static inline void local_inc(local_t *l)
  19 {
  20         asm volatile(_ASM_INC "%0"
  21                      : "+m" (l->a.counter));
  22 }
  23
  24 static inline void local_dec(local_t *l)
  25 {
  26         asm volatile(_ASM_DEC "%0"
  27                      : "+m" (l->a.counter));
  28 }
  29
  30 static inline void local_add(long i, local_t *l)
  31 {
  32         asm volatile(_ASM_ADD "%1,%0"
  33                      : "+m" (l->a.counter)
  34                      : "ir" (i));
  35 }
  36
  37 static inline void local_sub(long i, local_t *l)
  38 {
  39         asm volatile(_ASM_SUB "%1,%0"
  40                      : "+m" (l->a.counter)
  41                      : "ir" (i));
  42 }
  43
  44 /**
  45  * local_sub_and_test - subtract value from variable and test result
  46  * @i: integer value to subtract
  47  * @l: pointer to type local_t
  48  *
  49  * Atomically subtracts @i from @l and returns
  50  * true if the result is zero, or false for all
  51  * other cases.
  52  */
  53 static inline int local_sub_and_test(long i, local_t *l)
  54 {
  55         unsigned char c;
  56
  57         asm volatile(_ASM_SUB "%2,%0; sete %1"
  58                      : "+m" (l->a.counter), "=qm" (c)
  59                      : "ir" (i) : "memory");
  60         return c;
  61 }
  62
  63 /**
  64  * local_dec_and_test - decrement and test
  65  * @l: pointer to type local_t
  66  *
  67  * Atomically decrements @l by 1 and
  68  * returns true if the result is 0, or false for all other
  69  * cases.
  70  */
  71 static inline int local_dec_and_test(local_t *l)
  72 {
  73         unsigned char c;
  74
  75         asm volatile(_ASM_DEC "%0; sete %1"
  76                      : "+m" (l->a.counter), "=qm" (c)
  77                      : : "memory");
  78         return c != 0;
  79 }
  80
  81 /**
  82  * local_inc_and_test - increment and test
  83  * @l: pointer to type local_t
  84  *
  85  * Atomically increments @l by 1
  86  * and returns true if the result is zero, or false for all
  87  * other cases.
  88  */
  89 static inline int local_inc_and_test(local_t *l)
  90 {
  91         unsigned char c;
  92
  93         asm volatile(_ASM_INC "%0; sete %1"
  94                      : "+m" (l->a.counter), "=qm" (c)
  95                      : : "memory");
  96         return c != 0;
  97 }
  98
  99 /**
 100  * local_add_negative - add and test if negative
 101  * @i: integer value to add
 102  * @l: pointer to type local_t
 103  *
 104  * Atomically adds @i to @l and returns true
 105  * if the result is negative, or false when
 106  * result is greater than or equal to zero.
 107  */
 108 static inline int local_add_negative(long i, local_t *l)
 109 {
 110         unsigned char c;
 111
 112         asm volatile(_ASM_ADD "%2,%0; sets %1"
 113                      : "+m" (l->a.counter), "=qm" (c)
 114                      : "ir" (i) : "memory");
 115         return c;
 116 }
 117
 118 /**
 119  * local_add_return - add and return
 120  * @i: integer value to add
 121  * @l: pointer to type local_t
 122  *
 123  * Atomically adds @i to @l and returns @i + @l
 124  */
 125 static inline long local_add_return(long i, local_t *l)
 126 {
 127         long __i;
 128 #ifdef CONFIG_M386
 129         unsigned long flags;
 130         if (unlikely(boot_cpu_data.x86 <= 3))
 131                 goto no_xadd;
 132 #endif
 133         /* Modern 486+ processor */
 134         __i = i;
 135         asm volatile(_ASM_XADD "%0, %1;"
 136                      : "+r" (i), "+m" (l->a.counter)
 137                      : : "memory");
 138         return i + __i;
 139
 140 #ifdef CONFIG_M386
 141 no_xadd: /* Legacy 386 processor */
 142         local_irq_save(flags);
 143         __i = local_read(l);
 144         local_set(l, i + __i);
 145         local_irq_restore(flags);
 146         return i + __i;
 147 #endif
 148 }
 149
 150 static inline long local_sub_return(long i, local_t *l)
 151 {
 152         return local_add_return(-i, l);
 153 }
 154
 155 #define local_inc_return(l)  (local_add_return(1, l))
 156 #define local_dec_return(l)  (local_sub_return(1, l))
 157
 158 #define local_cmpxchg(l, o, n) \
 159         (cmpxchg_local(&((l)->a.counter), (o), (n)))
 160 /* Always has a lock prefix */
 161 #define local_xchg(l, n) (xchg(&((l)->a.counter), (n)))
 162
 163 /**
 164  * local_add_unless - add unless the number is a given value
 165  * @l: pointer of type local_t
 166  * @a: the amount to add to l...
 167  * @u: ...unless l is equal to u.
 168  *
 169  * Atomically adds @a to @l, so long as it was not @u.
 170  * Returns non-zero if @l was not @u, and zero otherwise.
 171  */
 172 #define local_add_unless(l, a, u)                               \
 173 ({                                                              \
 174         long c, old;                                            \
 175         c = local_read((l));                                    \
 176         for (;;) {                                              \
 177                 if (unlikely(c == (u)))                         \
 178                         break;                                  \
 179                 old = local_cmpxchg((l), c, c + (a));           \
 180                 if (likely(old == c))                           \
 181                         break;                                  \
 182                 c = old;                                        \
 183         }                                                       \
 184         c != (u);                                               \
 185 })
 186 #define local_inc_not_zero(l) local_add_unless((l), 1, 0)
 187
 188 /* On x86_32, these are no better than the atomic variants.
 189  * On x86-64 these are better than the atomic variants on SMP kernels
 190  * because they dont use a lock prefix.
 191  */
 192 #define __local_inc(l)          local_inc(l)
 193 #define __local_dec(l)          local_dec(l)
 194 #define __local_add(i, l)       local_add((i), (l))
 195 #define __local_sub(i, l)       local_sub((i), (l))
 196
 197 #endif /* _ASM_X86_LOCAL_H */