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 int 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 int 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 int 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 int 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_cmpxchg(atomic_t *v, int old, int new)
 175 {
 176         return cmpxchg(&v->counter, old, new);
 177 }
 178
 179 static inline int atomic_xchg(atomic_t *v, int new)
 180 {
 181         return xchg(&v->counter, new);
 182 }
 183
 184 #define ATOMIC_OP(op)                                                   \
 185 static inline void atomic_##op(int i, atomic_t *v)                      \
 186 {                                                                       \
 187         asm volatile(LOCK_PREFIX #op"l %1,%0"                           \
 188                         : "+m" (v->counter)                             \
 189                         : "ir" (i)                                      \
 190                         : "memory");                                    \
 191 }
 192
 193 ATOMIC_OP(and)
 194 ATOMIC_OP(or)
 195 ATOMIC_OP(xor)
 196
 197 #undef ATOMIC_OP
 198
 199 /**
 200  * __atomic_add_unless - add unless the number is already a given value
 201  * @v: pointer of type atomic_t
 202  * @a: the amount to add to v...
 203  * @u: ...unless v is equal to u.
 204  *
 205  * Atomically adds @a to @v, so long as @v was not already @u.
 206  * Returns the old value of @v.
 207  */
 208 static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u)
 209 {
 210         int c, old;
 211         c = atomic_read(v);
 212         for (;;) {
 213                 if (unlikely(c == (u)))
 214                         break;
 215                 old = atomic_cmpxchg((v), c, c + (a));
 216                 if (likely(old == c))
 217                         break;
 218                 c = old;
 219         }
 220         return c;
 221 }
 222
 223 /**
 224  * atomic_inc_short - increment of a short integer
 225  * @v: pointer to type int
 226  *
 227  * Atomically adds 1 to @v
 228  * Returns the new value of @u
 229  */
 230 static __always_inline short int atomic_inc_short(short int *v)
 231 {
 232         asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
 233         return *v;
 234 }
 235
 236 #ifdef CONFIG_X86_32
 237 # include <asm/atomic64_32.h>
 238 #else
 239 # include <asm/atomic64_64.h>
 240 #endif
 241
 242 #endif /* _ASM_X86_ATOMIC_H */