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/alternative.h>
   7 #include <asm/cmpxchg.h>
   8 #include <asm/rmwcc.h>
   9 #include <asm/barrier.h>
  10
  11 /*
  12  * Atomic operations that C can't guarantee us.  Useful for
  13  * resource counting etc..
  14  */
  15
  16 #define ATOMIC_INIT(i)  { (i) }
  17
  18 /**
  19  * atomic_read - read atomic variable
  20  * @v: pointer of type atomic_t
  21  *
  22  * Atomically reads the value of @v.
  23  */
  24 static __always_inline int atomic_read(const atomic_t *v)
  25 {
  26         return READ_ONCE((v)->counter);
  27 }
  28
  29 /**
  30  * atomic_set - set atomic variable
  31  * @v: pointer of type atomic_t
  32  * @i: required value
  33  *
  34  * Atomically sets the value of @v to @i.
  35  */
  36 static __always_inline void atomic_set(atomic_t *v, int i)
  37 {
  38         WRITE_ONCE(v->counter, i);
  39 }
  40
  41 /**
  42  * atomic_add - add integer to atomic variable
  43  * @i: integer value to add
  44  * @v: pointer of type atomic_t
  45  *
  46  * Atomically adds @i to @v.
  47  */
  48 static __always_inline void atomic_add(int i, atomic_t *v)
  49 {
  50         asm volatile(LOCK_PREFIX "addl %1,%0"
  51                      : "+m" (v->counter)
  52                      : "ir" (i));
  53 }
  54
  55 /**
  56  * atomic_sub - subtract integer from atomic variable
  57  * @i: integer value to subtract
  58  * @v: pointer of type atomic_t
  59  *
  60  * Atomically subtracts @i from @v.
  61  */
  62 static __always_inline void atomic_sub(int i, atomic_t *v)
  63 {
  64         asm volatile(LOCK_PREFIX "subl %1,%0"
  65                      : "+m" (v->counter)
  66                      : "ir" (i));
  67 }
  68
  69 /**
  70  * atomic_sub_and_test - subtract value from variable and test result
  71  * @i: integer value to subtract
  72  * @v: pointer of type atomic_t
  73  *
  74  * Atomically subtracts @i from @v and returns
  75  * true if the result is zero, or false for all
  76  * other cases.
  77  */
  78 static __always_inline bool atomic_sub_and_test(int i, atomic_t *v)
  79 {
  80         GEN_BINARY_RMWcc(LOCK_PREFIX "subl", v->counter, "er", i, "%0", e);
  81 }
  82
  83 /**
  84  * atomic_inc - increment atomic variable
  85  * @v: pointer of type atomic_t
  86  *
  87  * Atomically increments @v by 1.
  88  */
  89 static __always_inline void atomic_inc(atomic_t *v)
  90 {
  91         asm volatile(LOCK_PREFIX "incl %0"
  92                      : "+m" (v->counter));
  93 }
  94
  95 /**
  96  * atomic_dec - decrement atomic variable
  97  * @v: pointer of type atomic_t
  98  *
  99  * Atomically decrements @v by 1.
 100  */
 101 static __always_inline void atomic_dec(atomic_t *v)
 102 {
 103         asm volatile(LOCK_PREFIX "decl %0"
 104                      : "+m" (v->counter));
 105 }
 106
 107 /**
 108  * atomic_dec_and_test - decrement and test
 109  * @v: pointer of type atomic_t
 110  *
 111  * Atomically decrements @v by 1 and
 112  * returns true if the result is 0, or false for all other
 113  * cases.
 114  */
 115 static __always_inline bool atomic_dec_and_test(atomic_t *v)
 116 {
 117         GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", e);
 118 }
 119
 120 /**
 121  * atomic_inc_and_test - increment and test
 122  * @v: pointer of type atomic_t
 123  *
 124  * Atomically increments @v by 1
 125  * and returns true if the result is zero, or false for all
 126  * other cases.
 127  */
 128 static __always_inline bool atomic_inc_and_test(atomic_t *v)
 129 {
 130         GEN_UNARY_RMWcc(LOCK_PREFIX "incl", v->counter, "%0", e);
 131 }
 132
 133 /**
 134  * atomic_add_negative - add and test if negative
 135  * @i: integer value to add
 136  * @v: pointer of type atomic_t
 137  *
 138  * Atomically adds @i to @v and returns true
 139  * if the result is negative, or false when
 140  * result is greater than or equal to zero.
 141  */
 142 static __always_inline bool atomic_add_negative(int i, atomic_t *v)
 143 {
 144         GEN_BINARY_RMWcc(LOCK_PREFIX "addl", v->counter, "er", i, "%0", s);
 145 }
 146
 147 /**
 148  * atomic_add_return - add integer and return
 149  * @i: integer value to add
 150  * @v: pointer of type atomic_t
 151  *
 152  * Atomically adds @i to @v and returns @i + @v
 153  */
 154 static __always_inline int atomic_add_return(int i, atomic_t *v)
 155 {
 156         return i + xadd(&v->counter, i);
 157 }
 158
 159 /**
 160  * atomic_sub_return - subtract integer and return
 161  * @v: pointer of type atomic_t
 162  * @i: integer value to subtract
 163  *
 164  * Atomically subtracts @i from @v and returns @v - @i
 165  */
 166 static __always_inline int atomic_sub_return(int i, atomic_t *v)
 167 {
 168         return atomic_add_return(-i, v);
 169 }
 170
 171 #define atomic_inc_return(v)  (atomic_add_return(1, v))
 172 #define atomic_dec_return(v)  (atomic_sub_return(1, v))
 173
 174 static __always_inline int atomic_fetch_add(int i, atomic_t *v)
 175 {
 176         return xadd(&v->counter, i);
 177 }
 178
 179 static __always_inline int atomic_fetch_sub(int i, atomic_t *v)
 180 {
 181         return xadd(&v->counter, -i);
 182 }
 183
 184 static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new)
 185 {
 186         return cmpxchg(&v->counter, old, new);
 187 }
 188
 189 static inline int atomic_xchg(atomic_t *v, int new)
 190 {
 191         return xchg(&v->counter, new);
 192 }
 193
 194 #define ATOMIC_OP(op)                                                   \
 195 static inline void atomic_##op(int i, atomic_t *v)                      \
 196 {                                                                       \
 197         asm volatile(LOCK_PREFIX #op"l %1,%0"                           \
 198                         : "+m" (v->counter)                             \
 199                         : "ir" (i)                                      \
 200                         : "memory");                                    \
 201 }
 202
 203 #define ATOMIC_FETCH_OP(op, c_op)                                       \
 204 static inline int atomic_fetch_##op(int i, atomic_t *v)         \
 205 {                                                                       \
 206         int old, val = atomic_read(v);                                  \
 207         for (;;) {                                                      \
 208                 old = atomic_cmpxchg(v, val, val c_op i);               \
 209                 if (old == val)                                         \
 210                         break;                                          \
 211                 val = old;                                              \
 212         }                                                               \
 213         return old;                                                     \
 214 }
 215
 216 #define ATOMIC_OPS(op, c_op)                                            \
 217         ATOMIC_OP(op)                                                   \
 218         ATOMIC_FETCH_OP(op, c_op)
 219
 220 ATOMIC_OPS(and, &)
 221 ATOMIC_OPS(or , |)
 222 ATOMIC_OPS(xor, ^)
 223
 224 #undef ATOMIC_OPS
 225 #undef ATOMIC_FETCH_OP
 226 #undef ATOMIC_OP
 227
 228 /**
 229  * __atomic_add_unless - add unless the number is already a given value
 230  * @v: pointer of type atomic_t
 231  * @a: the amount to add to v...
 232  * @u: ...unless v is equal to u.
 233  *
 234  * Atomically adds @a to @v, so long as @v was not already @u.
 235  * Returns the old value of @v.
 236  */
 237 static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u)
 238 {
 239         int c, old;
 240         c = atomic_read(v);
 241         for (;;) {
 242                 if (unlikely(c == (u)))
 243                         break;
 244                 old = atomic_cmpxchg((v), c, c + (a));
 245                 if (likely(old == c))
 246                         break;
 247                 c = old;
 248         }
 249         return c;
 250 }
 251
 252 /**
 253  * atomic_inc_short - increment of a short integer
 254  * @v: pointer to type int
 255  *
 256  * Atomically adds 1 to @v
 257  * Returns the new value of @u
 258  */
 259 static __always_inline short int atomic_inc_short(short int *v)
 260 {
 261         asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
 262         return *v;
 263 }
 264
 265 #ifdef CONFIG_X86_32
 266 # include <asm/atomic64_32.h>
 267 #else
 268 # include <asm/atomic64_64.h>
 269 #endif
 270
 271 #endif /* _ASM_X86_ATOMIC_H */