include/asm-x86/local.h

   1 #ifndef _ARCH_LOCAL_H
   2 #define _ARCH_LOCAL_H
   3
   4 #include <linux/percpu.h>
   5
   6 #include <asm/system.h>
   7 #include <asm/atomic.h>
   8 #include <asm/asm.h>
   9
  10 typedef struct {
  11         atomic_long_t a;
  12 } local_t;
  13
  14 #define LOCAL_INIT(i)   { ATOMIC_LONG_INIT(i) }
  15
  16 #define local_read(l)   atomic_long_read(&(l)->a)
  17 #define local_set(l, i) atomic_long_set(&(l)->a, (i))
  18
  19 static inline void local_inc(local_t *l)
  20 {
  21         __asm__ __volatile__(
  22                 _ASM_INC "%0"
  23                 :"+m" (l->a.counter));
  24 }
  25
  26 static inline void local_dec(local_t *l)
  27 {
  28         __asm__ __volatile__(
  29                 _ASM_DEC "%0"
  30                 :"+m" (l->a.counter));
  31 }
  32
  33 static inline void local_add(long i, local_t *l)
  34 {
  35         __asm__ __volatile__(
  36                 _ASM_ADD "%1,%0"
  37                 :"+m" (l->a.counter)
  38                 :"ir" (i));
  39 }
  40
  41 static inline void local_sub(long i, local_t *l)
  42 {
  43         __asm__ __volatile__(
  44                 _ASM_SUB "%1,%0"
  45                 :"+m" (l->a.counter)
  46                 :"ir" (i));
  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                 _ASM_SUB "%2,%0; sete %1"
  64                 :"+m" (l->a.counter), "=qm" (c)
  65                 :"ir" (i) : "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                 _ASM_DEC "%0; sete %1"
  83                 :"+m" (l->a.counter), "=qm" (c)
  84                 : : "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                 _ASM_INC "%0; sete %1"
 102                 :"+m" (l->a.counter), "=qm" (c)
 103                 : : "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                 _ASM_ADD "%2,%0; sets %1"
 122                 :"+m" (l->a.counter), "=qm" (c)
 123                 :"ir" (i) : "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;
 137 #ifdef CONFIG_M386
 138         unsigned long flags;
 139         if (unlikely(boot_cpu_data.x86 <= 3))
 140                 goto no_xadd;
 141 #endif
 142         /* Modern 486+ processor */
 143         __i = i;
 144         __asm__ __volatile__(
 145                 _ASM_XADD "%0, %1;"
 146                 :"+r" (i), "+m" (l->a.counter)
 147                 : : "memory");
 148         return i + __i;
 149
 150 #ifdef CONFIG_M386
 151 no_xadd: /* Legacy 386 processor */
 152         local_irq_save(flags);
 153         __i = local_read(l);
 154         local_set(l, i + __i);
 155         local_irq_restore(flags);
 156         return i + __i;
 157 #endif
 158 }
 159
 160 static inline long local_sub_return(long i, local_t *l)
 161 {
 162         return local_add_return(-i, l);
 163 }
 164
 165 #define local_inc_return(l)  (local_add_return(1, l))
 166 #define local_dec_return(l)  (local_sub_return(1, l))
 167
 168 #define local_cmpxchg(l, o, n) \
 169         (cmpxchg_local(&((l)->a.counter), (o), (n)))
 170 /* Always has a lock prefix */
 171 #define local_xchg(l, n) (xchg(&((l)->a.counter), (n)))
 172
 173 /**
 174  * local_add_unless - add unless the number is a given value
 175  * @l: pointer of type local_t
 176  * @a: the amount to add to l...
 177  * @u: ...unless l is equal to u.
 178  *
 179  * Atomically adds @a to @l, so long as it was not @u.
 180  * Returns non-zero if @l was not @u, and zero otherwise.
 181  */
 182 #define local_add_unless(l, a, u)                               \
 183 ({                                                              \
 184         long c, old;                                            \
 185         c = local_read(l);                                      \
 186         for (;;) {                                              \
 187                 if (unlikely(c == (u)))                         \
 188                         break;                                  \
 189                 old = local_cmpxchg((l), c, c + (a));   \
 190                 if (likely(old == c))                           \
 191                         break;                                  \
 192                 c = old;                                        \
 193         }                                                       \
 194         c != (u);                                               \
 195 })
 196 #define local_inc_not_zero(l) local_add_unless((l), 1, 0)
 197
 198 /* On x86_32, these are no better than the atomic variants.
 199  * On x86-64 these are better than the atomic variants on SMP kernels
 200  * because they dont use a lock prefix.
 201  */
 202 #define __local_inc(l)          local_inc(l)
 203 #define __local_dec(l)          local_dec(l)
 204 #define __local_add(i, l)       local_add((i), (l))
 205 #define __local_sub(i, l)       local_sub((i), (l))
 206
 207 /* Use these for per-cpu local_t variables: on some archs they are
 208  * much more efficient than these naive implementations.  Note they take
 209  * a variable, not an address.
 210  *
 211  * X86_64: This could be done better if we moved the per cpu data directly
 212  * after GS.
 213  */
 214
 215 /* Need to disable preemption for the cpu local counters otherwise we could
 216    still access a variable of a previous CPU in a non atomic way. */
 217 #define cpu_local_wrap_v(l)             \
 218         ({ local_t res__;               \
 219            preempt_disable();           \
 220            res__ = (l);                 \
 221            preempt_enable();            \
 222            res__; })
 223 #define cpu_local_wrap(l)               \
 224         ({ preempt_disable();           \
 225            l;                           \
 226            preempt_enable(); })         \
 227
 228 #define cpu_local_read(l)    cpu_local_wrap_v(local_read(&__get_cpu_var(l)))
 229 #define cpu_local_set(l, i)  cpu_local_wrap(local_set(&__get_cpu_var(l), (i)))
 230 #define cpu_local_inc(l)     cpu_local_wrap(local_inc(&__get_cpu_var(l)))
 231 #define cpu_local_dec(l)     cpu_local_wrap(local_dec(&__get_cpu_var(l)))
 232 #define cpu_local_add(i, l)  cpu_local_wrap(local_add((i), &__get_cpu_var(l)))
 233 #define cpu_local_sub(i, l)  cpu_local_wrap(local_sub((i), &__get_cpu_var(l)))
 234
 235 #define __cpu_local_inc(l)      cpu_local_inc(l)
 236 #define __cpu_local_dec(l)      cpu_local_dec(l)
 237 #define __cpu_local_add(i, l)   cpu_local_add((i), (l))
 238 #define __cpu_local_sub(i, l)   cpu_local_sub((i), (l))
 239
 240 #endif /* _ARCH_LOCAL_H */