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 <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(_ASM_INC "%0"
  22                      : "+m" (l->a.counter));
  23 }
  24
  25 static inline void local_dec(local_t *l)
  26 {
  27         asm volatile(_ASM_DEC "%0"
  28                      : "+m" (l->a.counter));
  29 }
  30
  31 static inline void local_add(long i, local_t *l)
  32 {
  33         asm volatile(_ASM_ADD "%1,%0"
  34                      : "+m" (l->a.counter)
  35                      : "ir" (i));
  36 }
  37
  38 static inline void local_sub(long i, local_t *l)
  39 {
  40         asm volatile(_ASM_SUB "%1,%0"
  41                      : "+m" (l->a.counter)
  42                      : "ir" (i));
  43 }
  44
  45 /**
  46  * local_sub_and_test - subtract value from variable and test result
  47  * @i: integer value to subtract
  48  * @l: pointer to type local_t
  49  *
  50  * Atomically subtracts @i from @l and returns
  51  * true if the result is zero, or false for all
  52  * other cases.
  53  */
  54 static inline int local_sub_and_test(long i, local_t *l)
  55 {
  56         unsigned char c;
  57
  58         asm volatile(_ASM_SUB "%2,%0; sete %1"
  59                      : "+m" (l->a.counter), "=qm" (c)
  60                      : "ir" (i) : "memory");
  61         return c;
  62 }
  63
  64 /**
  65  * local_dec_and_test - decrement and test
  66  * @l: pointer to type local_t
  67  *
  68  * Atomically decrements @l by 1 and
  69  * returns true if the result is 0, or false for all other
  70  * cases.
  71  */
  72 static inline int local_dec_and_test(local_t *l)
  73 {
  74         unsigned char c;
  75
  76         asm volatile(_ASM_DEC "%0; sete %1"
  77                      : "+m" (l->a.counter), "=qm" (c)
  78                      : : "memory");
  79         return c != 0;
  80 }
  81
  82 /**
  83  * local_inc_and_test - increment and test
  84  * @l: pointer to type local_t
  85  *
  86  * Atomically increments @l by 1
  87  * and returns true if the result is zero, or false for all
  88  * other cases.
  89  */
  90 static inline int local_inc_and_test(local_t *l)
  91 {
  92         unsigned char c;
  93
  94         asm volatile(_ASM_INC "%0; sete %1"
  95                      : "+m" (l->a.counter), "=qm" (c)
  96                      : : "memory");
  97         return c != 0;
  98 }
  99
 100 /**
 101  * local_add_negative - add and test if negative
 102  * @i: integer value to add
 103  * @l: pointer to type local_t
 104  *
 105  * Atomically adds @i to @l and returns true
 106  * if the result is negative, or false when
 107  * result is greater than or equal to zero.
 108  */
 109 static inline int local_add_negative(long i, local_t *l)
 110 {
 111         unsigned char c;
 112
 113         asm volatile(_ASM_ADD "%2,%0; sets %1"
 114                      : "+m" (l->a.counter), "=qm" (c)
 115                      : "ir" (i) : "memory");
 116         return c;
 117 }
 118
 119 /**
 120  * local_add_return - add and return
 121  * @i: integer value to add
 122  * @l: pointer to type local_t
 123  *
 124  * Atomically adds @i to @l and returns @i + @l
 125  */
 126 static inline long local_add_return(long i, local_t *l)
 127 {
 128         long __i;
 129 #ifdef CONFIG_M386
 130         unsigned long flags;
 131         if (unlikely(boot_cpu_data.x86 <= 3))
 132                 goto no_xadd;
 133 #endif
 134         /* Modern 486+ processor */
 135         __i = i;
 136         asm volatile(_ASM_XADD "%0, %1;"
 137                      : "+r" (i), "+m" (l->a.counter)
 138                      : : "memory");
 139         return i + __i;
 140
 141 #ifdef CONFIG_M386
 142 no_xadd: /* Legacy 386 processor */
 143         local_irq_save(flags);
 144         __i = local_read(l);
 145         local_set(l, i + __i);
 146         local_irq_restore(flags);
 147         return i + __i;
 148 #endif
 149 }
 150
 151 static inline long local_sub_return(long i, local_t *l)
 152 {
 153         return local_add_return(-i, l);
 154 }
 155
 156 #define local_inc_return(l)  (local_add_return(1, l))
 157 #define local_dec_return(l)  (local_sub_return(1, l))
 158
 159 #define local_cmpxchg(l, o, n) \
 160         (cmpxchg_local(&((l)->a.counter), (o), (n)))
 161 /* Always has a lock prefix */
 162 #define local_xchg(l, n) (xchg(&((l)->a.counter), (n)))
 163
 164 /**
 165  * local_add_unless - add unless the number is a given value
 166  * @l: pointer of type local_t
 167  * @a: the amount to add to l...
 168  * @u: ...unless l is equal to u.
 169  *
 170  * Atomically adds @a to @l, so long as it was not @u.
 171  * Returns non-zero if @l was not @u, and zero otherwise.
 172  */
 173 #define local_add_unless(l, a, u)                               \
 174 ({                                                              \
 175         long c, old;                                            \
 176         c = local_read((l));                                    \
 177         for (;;) {                                              \
 178                 if (unlikely(c == (u)))                         \
 179                         break;                                  \
 180                 old = local_cmpxchg((l), c, c + (a));           \
 181                 if (likely(old == c))                           \
 182                         break;                                  \
 183                 c = old;                                        \
 184         }                                                       \
 185         c != (u);                                               \
 186 })
 187 #define local_inc_not_zero(l) local_add_unless((l), 1, 0)
 188
 189 /* On x86_32, these are no better than the atomic variants.
 190  * On x86-64 these are better than the atomic variants on SMP kernels
 191  * because they dont use a lock prefix.
 192  */
 193 #define __local_inc(l)          local_inc(l)
 194 #define __local_dec(l)          local_dec(l)
 195 #define __local_add(i, l)       local_add((i), (l))
 196 #define __local_sub(i, l)       local_sub((i), (l))
 197
 198 /* Use these for per-cpu local_t variables: on some archs they are
 199  * much more efficient than these naive implementations.  Note they take
 200  * a variable, not an address.
 201  *
 202  * X86_64: This could be done better if we moved the per cpu data directly
 203  * after GS.
 204  */
 205
 206 /* Need to disable preemption for the cpu local counters otherwise we could
 207    still access a variable of a previous CPU in a non atomic way. */
 208 #define cpu_local_wrap_v(l)             \
 209 ({                                      \
 210         local_t res__;                  \
 211         preempt_disable();              \
 212         res__ = (l);                    \
 213         preempt_enable();               \
 214         res__;                          \
 215 })
 216 #define cpu_local_wrap(l)               \
 217 ({                                      \
 218         preempt_disable();              \
 219         (l);                            \
 220         preempt_enable();               \
 221 })                                      \
 222
 223 #define cpu_local_read(l)    cpu_local_wrap_v(local_read(&__get_cpu_var((l))))
 224 #define cpu_local_set(l, i)  cpu_local_wrap(local_set(&__get_cpu_var((l)), (i)))
 225 #define cpu_local_inc(l)     cpu_local_wrap(local_inc(&__get_cpu_var((l))))
 226 #define cpu_local_dec(l)     cpu_local_wrap(local_dec(&__get_cpu_var((l))))
 227 #define cpu_local_add(i, l)  cpu_local_wrap(local_add((i), &__get_cpu_var((l))))
 228 #define cpu_local_sub(i, l)  cpu_local_wrap(local_sub((i), &__get_cpu_var((l))))
 229
 230 #define __cpu_local_inc(l)      cpu_local_inc((l))
 231 #define __cpu_local_dec(l)      cpu_local_dec((l))
 232 #define __cpu_local_add(i, l)   cpu_local_add((i), (l))
 233 #define __cpu_local_sub(i, l)   cpu_local_sub((i), (l))
 234
 235 #endif /* _ASM_X86_LOCAL_H */