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
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