include/asm-x86_64/local.h

   1 #ifndef _ARCH_X8664_LOCAL_H
   2 #define _ARCH_X8664_LOCAL_H
   3
   4 #include <linux/percpu.h>
   5 #include <asm/atomic.h>
   6
   7 typedef struct
   8 {
   9         atomic_long_t a;
  10 } local_t;
  11
  12 #define LOCAL_INIT(i)   { ATOMIC_LONG_INIT(i) }
  13
  14 #define local_read(l)   atomic_long_read(&(l)->a)
  15 #define local_set(l,i)  atomic_long_set(&(l)->a, (i))
  16
  17 static inline void local_inc(local_t *l)
  18 {
  19         __asm__ __volatile__(
  20                 "incq %0"
  21                 :"=m" (l->a.counter)
  22                 :"m" (l->a.counter));
  23 }
  24
  25 static inline void local_dec(local_t *l)
  26 {
  27         __asm__ __volatile__(
  28                 "decq %0"
  29                 :"=m" (l->a.counter)
  30                 :"m" (l->a.counter));
  31 }
  32
  33 static inline void local_add(long i, local_t *l)
  34 {
  35         __asm__ __volatile__(
  36                 "addq %1,%0"
  37                 :"=m" (l->a.counter)
  38                 :"ir" (i), "m" (l->a.counter));
  39 }
  40
  41 static inline void local_sub(long i, local_t *l)
  42 {
  43         __asm__ __volatile__(
  44                 "subq %1,%0"
  45                 :"=m" (l->a.counter)
  46                 :"ir" (i), "m" (l->a.counter));
  47 }
  48
  49 /**
  50  * local_sub_and_test - subtract value from variable and test result
  51  * @i: integer value to subtract
  52  * @l: pointer to type local_t
  53  *
  54  * Atomically subtracts @i from @l and returns
  55  * true if the result is zero, or false for all
  56  * other cases.
  57  */
  58 static __inline__ int local_sub_and_test(long i, local_t *l)
  59 {
  60         unsigned char c;
  61
  62         __asm__ __volatile__(
  63                 "subq %2,%0; sete %1"
  64                 :"=m" (l->a.counter), "=qm" (c)
  65                 :"ir" (i), "m" (l->a.counter) : "memory");
  66         return c;
  67 }
  68
  69 /**
  70  * local_dec_and_test - decrement and test
  71  * @l: pointer to type local_t
  72  *
  73  * Atomically decrements @l by 1 and
  74  * returns true if the result is 0, or false for all other
  75  * cases.
  76  */
  77 static __inline__ int local_dec_and_test(local_t *l)
  78 {
  79         unsigned char c;
  80
  81         __asm__ __volatile__(
  82                 "decq %0; sete %1"
  83                 :"=m" (l->a.counter), "=qm" (c)
  84                 :"m" (l->a.counter) : "memory");
  85         return c != 0;
  86 }
  87
  88 /**
  89  * local_inc_and_test - increment and test
  90  * @l: pointer to type local_t
  91  *
  92  * Atomically increments @l by 1
  93  * and returns true if the result is zero, or false for all
  94  * other cases.
  95  */
  96 static __inline__ int local_inc_and_test(local_t *l)
  97 {
  98         unsigned char c;
  99
 100         __asm__ __volatile__(
 101                 "incq %0; sete %1"
 102                 :"=m" (l->a.counter), "=qm" (c)
 103                 :"m" (l->a.counter) : "memory");
 104         return c != 0;
 105 }
 106
 107 /**
 108  * local_add_negative - add and test if negative
 109  * @i: integer value to add
 110  * @l: pointer to type local_t
 111  *
 112  * Atomically adds @i to @l and returns true
 113  * if the result is negative, or false when
 114  * result is greater than or equal to zero.
 115  */
 116 static __inline__ int local_add_negative(long i, local_t *l)
 117 {
 118         unsigned char c;
 119
 120         __asm__ __volatile__(
 121                 "addq %2,%0; sets %1"
 122                 :"=m" (l->a.counter), "=qm" (c)
 123                 :"ir" (i), "m" (l->a.counter) : "memory");
 124         return c;
 125 }
 126
 127 /**
 128  * local_add_return - add and return
 129  * @i: integer value to add
 130  * @l: pointer to type local_t
 131  *
 132  * Atomically adds @i to @l and returns @i + @l
 133  */
 134 static __inline__ long local_add_return(long i, local_t *l)
 135 {
 136         long __i = i;
 137         __asm__ __volatile__(
 138                 "xaddq %0, %1;"
 139                 :"+r" (i), "+m" (l->a.counter)
 140                 : : "memory");
 141         return i + __i;
 142 }
 143
 144 static __inline__ long local_sub_return(long i, local_t *l)
 145 {
 146         return local_add_return(-i,l);
 147 }
 148
 149 #define local_inc_return(l)  (local_add_return(1,l))
 150 #define local_dec_return(l)  (local_sub_return(1,l))
 151
 152 #define local_cmpxchg(l, o, n) \
 153         (cmpxchg_local(&((l)->a.counter), (o), (n)))
 154 /* Always has a lock prefix */
 155 #define local_xchg(l, n) (xchg(&((l)->a.counter), (n)))
 156
 157 /**
 158  * atomic_up_add_unless - add unless the number is a given value
 159  * @l: pointer of type local_t
 160  * @a: the amount to add to l...
 161  * @u: ...unless l is equal to u.
 162  *
 163  * Atomically adds @a to @l, so long as it was not @u.
 164  * Returns non-zero if @l was not @u, and zero otherwise.
 165  */
 166 #define local_add_unless(l, a, u)                               \
 167 ({                                                              \
 168         long c, old;                                            \
 169         c = local_read(l);                                      \
 170         for (;;) {                                              \
 171                 if (unlikely(c == (u)))                         \
 172                         break;                                  \
 173                 old = local_cmpxchg((l), c, c + (a));   \
 174                 if (likely(old == c))                           \
 175                         break;                                  \
 176                 c = old;                                        \
 177         }                                                       \
 178         c != (u);                                               \
 179 })
 180 #define local_inc_not_zero(l) local_add_unless((l), 1, 0)
 181
 182 /* On x86-64 these are better than the atomic variants on SMP kernels
 183    because they dont use a lock prefix. */
 184 #define __local_inc(l)          local_inc(l)
 185 #define __local_dec(l)          local_dec(l)
 186 #define __local_add(i,l)        local_add((i),(l))
 187 #define __local_sub(i,l)        local_sub((i),(l))
 188
 189 /* Use these for per-cpu local_t variables: on some archs they are
 190  * much more efficient than these naive implementations.  Note they take
 191  * a variable, not an address.
 192  *
 193  * This could be done better if we moved the per cpu data directly
 194  * after GS.
 195  */
 196
 197 /* Need to disable preemption for the cpu local counters otherwise we could
 198    still access a variable of a previous CPU in a non atomic way. */
 199 #define cpu_local_wrap_v(l)             \
 200         ({ local_t res__;               \
 201            preempt_disable();           \
 202            res__ = (l);                 \
 203            preempt_enable();            \
 204            res__; })
 205 #define cpu_local_wrap(l)               \
 206         ({ preempt_disable();           \
 207            l;                           \
 208            preempt_enable(); })         \
 209
 210 #define cpu_local_read(l)    cpu_local_wrap_v(local_read(&__get_cpu_var(l)))
 211 #define cpu_local_set(l, i)  cpu_local_wrap(local_set(&__get_cpu_var(l), (i)))
 212 #define cpu_local_inc(l)     cpu_local_wrap(local_inc(&__get_cpu_var(l)))
 213 #define cpu_local_dec(l)     cpu_local_wrap(local_dec(&__get_cpu_var(l)))
 214 #define cpu_local_add(i, l)  cpu_local_wrap(local_add((i), &__get_cpu_var(l)))
 215 #define cpu_local_sub(i, l)  cpu_local_wrap(local_sub((i), &__get_cpu_var(l)))
 216
 217 #define __cpu_local_inc(l)      cpu_local_inc(l)
 218 #define __cpu_local_dec(l)      cpu_local_dec(l)
 219 #define __cpu_local_add(i, l)   cpu_local_add((i), (l))
 220 #define __cpu_local_sub(i, l)   cpu_local_sub((i), (l))
 221
 222 #endif /* _ARCH_X8664_LOCAL_H */