arch/x86/include/asm/atomic.h

   1 #ifndef _ASM_X86_ATOMIC_H
   2 #define _ASM_X86_ATOMIC_H
   3
   4 #include <linux/compiler.h>
   5 #include <linux/types.h>
   6 #include <asm/processor.h>
   7 #include <asm/alternative.h>
   8 #include <asm/cmpxchg.h>
   9 #include <asm/rmwcc.h>
  10 #include <asm/barrier.h>
  11
  12 /*
  13  * Atomic operations that C can't guarantee us.  Useful for
  14  * resource counting etc..
  15  */
  16
  17 #define ATOMIC_INIT(i)  { (i) }
  18
  19 /**
  20  * atomic_read - read atomic variable
  21  * @v: pointer of type atomic_t
  22  *
  23  * Atomically reads the value of @v.
  24  */
  25 static __always_inline int atomic_read(const atomic_t *v)
  26 {
  27         return READ_ONCE((v)->counter);
  28 }
  29
  30 /**
  31  * atomic_set - set atomic variable
  32  * @v: pointer of type atomic_t
  33  * @i: required value
  34  *
  35  * Atomically sets the value of @v to @i.
  36  */
  37 static __always_inline void atomic_set(atomic_t *v, int i)
  38 {
  39         WRITE_ONCE(v->counter, i);
  40 }
  41
  42 /**
  43  * atomic_add - add integer to atomic variable
  44  * @i: integer value to add
  45  * @v: pointer of type atomic_t
  46  *
  47  * Atomically adds @i to @v.
  48  */
  49 static __always_inline void atomic_add(int i, atomic_t *v)
  50 {
  51         asm volatile(LOCK_PREFIX "addl %1,%0"
  52                      : "+m" (v->counter)
  53                      : "ir" (i));
  54 }
  55
  56 /**
  57  * atomic_sub - subtract integer from atomic variable
  58  * @i: integer value to subtract
  59  * @v: pointer of type atomic_t
  60  *
  61  * Atomically subtracts @i from @v.
  62  */
  63 static __always_inline void atomic_sub(int i, atomic_t *v)
  64 {
  65         asm volatile(LOCK_PREFIX "subl %1,%0"
  66                      : "+m" (v->counter)
  67                      : "ir" (i));
  68 }
  69
  70 /**
  71  * atomic_sub_and_test - subtract value from variable and test result
  72  * @i: integer value to subtract
  73  * @v: pointer of type atomic_t
  74  *
  75  * Atomically subtracts @i from @v and returns
  76  * true if the result is zero, or false for all
  77  * other cases.
  78  */
  79 static __always_inline int atomic_sub_and_test(int i, atomic_t *v)
  80 {
  81         GEN_BINARY_RMWcc(LOCK_PREFIX "subl", v->counter, "er", i, "%0", "e");
  82 }
  83
  84 /**
  85  * atomic_inc - increment atomic variable
  86  * @v: pointer of type atomic_t
  87  *
  88  * Atomically increments @v by 1.
  89  */
  90 static __always_inline void atomic_inc(atomic_t *v)
  91 {
  92         asm volatile(LOCK_PREFIX "incl %0"
  93                      : "+m" (v->counter));
  94 }
  95
  96 /**
  97  * atomic_dec - decrement atomic variable
  98  * @v: pointer of type atomic_t
  99  *
 100  * Atomically decrements @v by 1.
 101  */
 102 static __always_inline void atomic_dec(atomic_t *v)
 103 {
 104         asm volatile(LOCK_PREFIX "decl %0"
 105                      : "+m" (v->counter));
 106 }
 107
 108 /**
 109  * atomic_dec_and_test - decrement and test
 110  * @v: pointer of type atomic_t
 111  *
 112  * Atomically decrements @v by 1 and
 113  * returns true if the result is 0, or false for all other
 114  * cases.
 115  */
 116 static __always_inline int atomic_dec_and_test(atomic_t *v)
 117 {
 118         GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e");
 119 }
 120
 121 /**
 122  * atomic_inc_and_test - increment and test
 123  * @v: pointer of type atomic_t
 124  *
 125  * Atomically increments @v by 1
 126  * and returns true if the result is zero, or false for all
 127  * other cases.
 128  */
 129 static __always_inline int atomic_inc_and_test(atomic_t *v)
 130 {
 131         GEN_UNARY_RMWcc(LOCK_PREFIX "incl", v->counter, "%0", "e");
 132 }
 133
 134 /**
 135  * atomic_add_negative - add and test if negative
 136  * @i: integer value to add
 137  * @v: pointer of type atomic_t
 138  *
 139  * Atomically adds @i to @v and returns true
 140  * if the result is negative, or false when
 141  * result is greater than or equal to zero.
 142  */
 143 static __always_inline int atomic_add_negative(int i, atomic_t *v)
 144 {
 145         GEN_BINARY_RMWcc(LOCK_PREFIX "addl", v->counter, "er", i, "%0", "s");
 146 }
 147
 148 /**
 149  * atomic_add_return - add integer and return
 150  * @i: integer value to add
 151  * @v: pointer of type atomic_t
 152  *
 153  * Atomically adds @i to @v and returns @i + @v
 154  */
 155 static __always_inline int atomic_add_return(int i, atomic_t *v)
 156 {
 157         return i + xadd(&v->counter, i);
 158 }
 159
 160 /**
 161  * atomic_sub_return - subtract integer and return
 162  * @v: pointer of type atomic_t
 163  * @i: integer value to subtract
 164  *
 165  * Atomically subtracts @i from @v and returns @v - @i
 166  */
 167 static __always_inline int atomic_sub_return(int i, atomic_t *v)
 168 {
 169         return atomic_add_return(-i, v);
 170 }
 171
 172 #define atomic_inc_return(v)  (atomic_add_return(1, v))
 173 #define atomic_dec_return(v)  (atomic_sub_return(1, v))
 174
 175 static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new)
 176 {
 177         return cmpxchg(&v->counter, old, new);
 178 }
 179
 180 static inline int atomic_xchg(atomic_t *v, int new)
 181 {
 182         return xchg(&v->counter, new);
 183 }
 184
 185 #define ATOMIC_OP(op)                                                   \
 186 static inline void atomic_##op(int i, atomic_t *v)                      \
 187 {                                                                       \
 188         asm volatile(LOCK_PREFIX #op"l %1,%0"                           \
 189                         : "+m" (v->counter)                             \
 190                         : "ir" (i)                                      \
 191                         : "memory");                                    \
 192 }
 193
 194 ATOMIC_OP(and)
 195 ATOMIC_OP(or)
 196 ATOMIC_OP(xor)
 197
 198 #undef ATOMIC_OP
 199
 200 /**
 201  * __atomic_add_unless - add unless the number is already a given value
 202  * @v: pointer of type atomic_t
 203  * @a: the amount to add to v...
 204  * @u: ...unless v is equal to u.
 205  *
 206  * Atomically adds @a to @v, so long as @v was not already @u.
 207  * Returns the old value of @v.
 208  */
 209 static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u)
 210 {
 211         int c, old;
 212         c = atomic_read(v);
 213         for (;;) {
 214                 if (unlikely(c == (u)))
 215                         break;
 216                 old = atomic_cmpxchg((v), c, c + (a));
 217                 if (likely(old == c))
 218                         break;
 219                 c = old;
 220         }
 221         return c;
 222 }
 223
 224 /**
 225  * atomic_inc_short - increment of a short integer
 226  * @v: pointer to type int
 227  *
 228  * Atomically adds 1 to @v
 229  * Returns the new value of @u
 230  */
 231 static __always_inline short int atomic_inc_short(short int *v)
 232 {
 233         asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
 234         return *v;
 235 }
 236
 237 #ifdef CONFIG_X86_32
 238 # include <asm/atomic64_32.h>
 239 #else
 240 # include <asm/atomic64_64.h>
 241 #endif
 242
 243 #endif /* _ASM_X86_ATOMIC_H */