include/asm-i386/local.h

   1 #ifndef _ARCH_I386_LOCAL_H
   2 #define _ARCH_I386_LOCAL_H
   3
   4 #include <linux/percpu.h>
   5 #include <asm/system.h>
   6 #include <asm/atomic.h>
   7
   8 typedef struct
   9 {
  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__(
  21                 "incl %0"
  22                 :"+m" (l->a.counter));
  23 }
  24
  25 static __inline__ void local_dec(local_t *l)
  26 {
  27         __asm__ __volatile__(
  28                 "decl %0"
  29                 :"+m" (l->a.counter));
  30 }
  31
  32 static __inline__ void local_add(long i, local_t *l)
  33 {
  34         __asm__ __volatile__(
  35                 "addl %1,%0"
  36                 :"+m" (l->a.counter)
  37                 :"ir" (i));
  38 }
  39
  40 static __inline__ void local_sub(long i, local_t *l)
  41 {
  42         __asm__ __volatile__(
  43                 "subl %1,%0"
  44                 :"+m" (l->a.counter)
  45                 :"ir" (i));
  46 }
  47
  48 /**
  49  * local_sub_and_test - subtract value from variable and test result
  50  * @i: integer value to subtract
  51  * @l: pointer of type local_t
  52  *
  53  * Atomically subtracts @i from @l and returns
  54  * true if the result is zero, or false for all
  55  * other cases.
  56  */
  57 static __inline__ int local_sub_and_test(long i, local_t *l)
  58 {
  59         unsigned char c;
  60
  61         __asm__ __volatile__(
  62                 "subl %2,%0; sete %1"
  63                 :"+m" (l->a.counter), "=qm" (c)
  64                 :"ir" (i) : "memory");
  65         return c;
  66 }
  67
  68 /**
  69  * local_dec_and_test - decrement and test
  70  * @l: pointer of type local_t
  71  *
  72  * Atomically decrements @l by 1 and
  73  * returns true if the result is 0, or false for all other
  74  * cases.
  75  */
  76 static __inline__ int local_dec_and_test(local_t *l)
  77 {
  78         unsigned char c;
  79
  80         __asm__ __volatile__(
  81                 "decl %0; sete %1"
  82                 :"+m" (l->a.counter), "=qm" (c)
  83                 : : "memory");
  84         return c != 0;
  85 }
  86
  87 /**
  88  * local_inc_and_test - increment and test
  89  * @l: pointer of type local_t
  90  *
  91  * Atomically increments @l by 1
  92  * and returns true if the result is zero, or false for all
  93  * other cases.
  94  */
  95 static __inline__ int local_inc_and_test(local_t *l)
  96 {
  97         unsigned char c;
  98
  99         __asm__ __volatile__(
 100                 "incl %0; sete %1"
 101                 :"+m" (l->a.counter), "=qm" (c)
 102                 : : "memory");
 103         return c != 0;
 104 }
 105
 106 /**
 107  * local_add_negative - add and test if negative
 108  * @l: pointer of type local_t
 109  * @i: integer value to add
 110  *
 111  * Atomically adds @i to @l and returns true
 112  * if the result is negative, or false when
 113  * result is greater than or equal to zero.
 114  */
 115 static __inline__ int local_add_negative(long i, local_t *l)
 116 {
 117         unsigned char c;
 118
 119         __asm__ __volatile__(
 120                 "addl %2,%0; sets %1"
 121                 :"+m" (l->a.counter), "=qm" (c)
 122                 :"ir" (i) : "memory");
 123         return c;
 124 }
 125
 126 /**
 127  * local_add_return - add and return
 128  * @l: pointer of type local_t
 129  * @i: integer value to add
 130  *
 131  * Atomically adds @i to @l and returns @i + @l
 132  */
 133 static __inline__ long local_add_return(long i, local_t *l)
 134 {
 135         long __i;
 136 #ifdef CONFIG_M386
 137         unsigned long flags;
 138         if(unlikely(boot_cpu_data.x86 <= 3))
 139                 goto no_xadd;
 140 #endif
 141         /* Modern 486+ processor */
 142         __i = i;
 143         __asm__ __volatile__(
 144                 "xaddl %0, %1;"
 145                 :"+r" (i), "+m" (l->a.counter)
 146                 : : "memory");
 147         return i + __i;
 148
 149 #ifdef CONFIG_M386
 150 no_xadd: /* Legacy 386 processor */
 151         local_irq_save(flags);
 152         __i = local_read(l);
 153         local_set(l, i + __i);
 154         local_irq_restore(flags);
 155         return i + __i;
 156 #endif
 157 }
 158
 159 static __inline__ long local_sub_return(long i, local_t *l)
 160 {
 161         return local_add_return(-i,l);
 162 }
 163
 164 #define local_inc_return(l)  (local_add_return(1,l))
 165 #define local_dec_return(l)  (local_sub_return(1,l))
 166
 167 #define local_cmpxchg(l, o, n) \
 168         (cmpxchg_local(&((l)->a.counter), (o), (n)))
 169 /* Always has a lock prefix */
 170 #define local_xchg(l, n) (xchg(&((l)->a.counter), (n)))
 171
 172 /**
 173  * local_add_unless - add unless the number is a given value
 174  * @l: pointer of type local_t
 175  * @a: the amount to add to l...
 176  * @u: ...unless l is equal to u.
 177  *
 178  * Atomically adds @a to @l, so long as it was not @u.
 179  * Returns non-zero if @l was not @u, and zero otherwise.
 180  */
 181 #define local_add_unless(l, a, u)                               \
 182 ({                                                              \
 183         long c, old;                                            \
 184         c = local_read(l);                                      \
 185         for (;;) {                                              \
 186                 if (unlikely(c == (u)))                         \
 187                         break;                                  \
 188                 old = local_cmpxchg((l), c, c + (a));   \
 189                 if (likely(old == c))                           \
 190                         break;                                  \
 191                 c = old;                                        \
 192         }                                                       \
 193         c != (u);                                               \
 194 })
 195 #define local_inc_not_zero(l) local_add_unless((l), 1, 0)
 196
 197 /* On x86, these are no better than the atomic variants. */
 198 #define __local_inc(l)          local_inc(l)
 199 #define __local_dec(l)          local_dec(l)
 200 #define __local_add(i,l)        local_add((i),(l))
 201 #define __local_sub(i,l)        local_sub((i),(l))
 202
 203 /* Use these for per-cpu local_t variables: on some archs they are
 204  * much more efficient than these naive implementations.  Note they take
 205  * a variable, not an address.
 206  */
 207
 208 /* Need to disable preemption for the cpu local counters otherwise we could
 209    still access a variable of a previous CPU in a non atomic way. */
 210 #define cpu_local_wrap_v(l)             \
 211         ({ local_t res__;               \
 212            preempt_disable();           \
 213            res__ = (l);                 \
 214            preempt_enable();            \
 215            res__; })
 216 #define cpu_local_wrap(l)               \
 217         ({ preempt_disable();           \
 218            l;                           \
 219            preempt_enable(); })         \
 220
 221 #define cpu_local_read(l)    cpu_local_wrap_v(local_read(&__get_cpu_var(l)))
 222 #define cpu_local_set(l, i)  cpu_local_wrap(local_set(&__get_cpu_var(l), (i)))
 223 #define cpu_local_inc(l)     cpu_local_wrap(local_inc(&__get_cpu_var(l)))
 224 #define cpu_local_dec(l)     cpu_local_wrap(local_dec(&__get_cpu_var(l)))
 225 #define cpu_local_add(i, l)  cpu_local_wrap(local_add((i), &__get_cpu_var(l)))
 226 #define cpu_local_sub(i, l)  cpu_local_wrap(local_sub((i), &__get_cpu_var(l)))
 227
 228 #define __cpu_local_inc(l)      cpu_local_inc(l)
 229 #define __cpu_local_dec(l)      cpu_local_dec(l)
 230 #define __cpu_local_add(i, l)   cpu_local_add((i), (l))
 231 #define __cpu_local_sub(i, l)   cpu_local_sub((i), (l))
 232
 233 #endif /* _ARCH_I386_LOCAL_H */