1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_X86_LOCAL_H 3 #define _ASM_X86_LOCAL_H 4 5 #include <linux/percpu.h> 6 7 #include <linux/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 bool local_sub_and_test(long i, local_t *l) 55 { 56 return GEN_BINARY_RMWcc(_ASM_SUB, l->a.counter, e, "er", i); 57 } 58 59 /** 60 * local_dec_and_test - decrement and test 61 * @l: pointer to type local_t 62 * 63 * Atomically decrements @l by 1 and 64 * returns true if the result is 0, or false for all other 65 * cases. 66 */ 67 static inline bool local_dec_and_test(local_t *l) 68 { 69 return GEN_UNARY_RMWcc(_ASM_DEC, l->a.counter, e); 70 } 71 72 /** 73 * local_inc_and_test - increment and test 74 * @l: pointer to type local_t 75 * 76 * Atomically increments @l by 1 77 * and returns true if the result is zero, or false for all 78 * other cases. 79 */ 80 static inline bool local_inc_and_test(local_t *l) 81 { 82 return GEN_UNARY_RMWcc(_ASM_INC, l->a.counter, e); 83 } 84 85 /** 86 * local_add_negative - add and test if negative 87 * @i: integer value to add 88 * @l: pointer to type local_t 89 * 90 * Atomically adds @i to @l and returns true 91 * if the result is negative, or false when 92 * result is greater than or equal to zero. 93 */ 94 static inline bool local_add_negative(long i, local_t *l) 95 { 96 return GEN_BINARY_RMWcc(_ASM_ADD, l->a.counter, s, "er", i); 97 } 98 99 /** 100 * local_add_return - add and return 101 * @i: integer value to add 102 * @l: pointer to type local_t 103 * 104 * Atomically adds @i to @l and returns @i + @l 105 */ 106 static inline long local_add_return(long i, local_t *l) 107 { 108 long __i = i; 109 asm volatile(_ASM_XADD "%0, %1;" 110 : "+r" (i), "+m" (l->a.counter) 111 : : "memory"); 112 return i + __i; 113 } 114 115 static inline long local_sub_return(long i, local_t *l) 116 { 117 return local_add_return(-i, l); 118 } 119 120 #define local_inc_return(l) (local_add_return(1, l)) 121 #define local_dec_return(l) (local_sub_return(1, l)) 122 123 static inline long local_cmpxchg(local_t *l, long old, long new) 124 { 125 return cmpxchg_local(&l->a.counter, old, new); 126 } 127 128 static inline bool local_try_cmpxchg(local_t *l, long *old, long new) 129 { 130 return try_cmpxchg_local(&l->a.counter, 131 (typeof(l->a.counter) *) old, new); 132 } 133 134 /* 135 * Implement local_xchg using CMPXCHG instruction without the LOCK prefix. 136 * XCHG is expensive due to the implied LOCK prefix. The processor 137 * cannot prefetch cachelines if XCHG is used. 138 */ 139 static __always_inline long 140 local_xchg(local_t *l, long n) 141 { 142 long c = local_read(l); 143 144 do { } while (!local_try_cmpxchg(l, &c, n)); 145 146 return c; 147 } 148 149 /** 150 * local_add_unless - add unless the number is already a given value 151 * @l: pointer of type local_t 152 * @a: the amount to add to l... 153 * @u: ...unless l is equal to u. 154 * 155 * Atomically adds @a to @l, if @v was not already @u. 156 * Returns true if the addition was done. 157 */ 158 static __always_inline bool 159 local_add_unless(local_t *l, long a, long u) 160 { 161 long c = local_read(l); 162 163 do { 164 if (unlikely(c == u)) 165 return false; 166 } while (!local_try_cmpxchg(l, &c, c + a)); 167 168 return true; 169 } 170 171 #define local_inc_not_zero(l) local_add_unless((l), 1, 0) 172 173 /* On x86_32, these are no better than the atomic variants. 174 * On x86-64 these are better than the atomic variants on SMP kernels 175 * because they dont use a lock prefix. 176 */ 177 #define __local_inc(l) local_inc(l) 178 #define __local_dec(l) local_dec(l) 179 #define __local_add(i, l) local_add((i), (l)) 180 #define __local_sub(i, l) local_sub((i), (l)) 181 182 #endif /* _ASM_X86_LOCAL_H */ 183