1 #ifndef _ARCH_LOCAL_H
2 #define _ARCH_LOCAL_H
3
4 #include <linux/percpu.h>
5
6 #include <asm/system.h>
7 #include <asm/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__(
22 _ASM_INC "%0"
23 :"+m" (l->a.counter));
24 }
25
26 static inline void local_dec(local_t *l)
27 {
28 __asm__ __volatile__(
29 _ASM_DEC "%0"
30 :"+m" (l->a.counter));
31 }
32
33 static inline void local_add(long i, local_t *l)
34 {
35 __asm__ __volatile__(
36 _ASM_ADD "%1,%0"
37 :"+m" (l->a.counter)
38 :"ir" (i));
39 }
40
41 static inline void local_sub(long i, local_t *l)
42 {
43 __asm__ __volatile__(
44 _ASM_SUB "%1,%0"
45 :"+m" (l->a.counter)
46 :"ir" (i));
47 }
48
49 /**
50 * local_sub_and_test - subtract value from variable and test result
51 * @i: integer value to subtract
52 * @l: pointer to type local_t
53 *
54 * Atomically subtracts @i from @l and returns
55 * true if the result is zero, or false for all
56 * other cases.
57 */
58 static inline int local_sub_and_test(long i, local_t *l)
59 {
60 unsigned char c;
61
62 __asm__ __volatile__(
63 _ASM_SUB "%2,%0; sete %1"
64 :"+m" (l->a.counter), "=qm" (c)
65 :"ir" (i) : "memory");
66 return c;
67 }
68
69 /**
70 * local_dec_and_test - decrement and test
71 * @l: pointer to type local_t
72 *
73 * Atomically decrements @l by 1 and
74 * returns true if the result is 0, or false for all other
75 * cases.
76 */
77 static inline int local_dec_and_test(local_t *l)
78 {
79 unsigned char c;
80
81 __asm__ __volatile__(
82 _ASM_DEC "%0; sete %1"
83 :"+m" (l->a.counter), "=qm" (c)
84 : : "memory");
85 return c != 0;
86 }
87
88 /**
89 * local_inc_and_test - increment and test
90 * @l: pointer to type local_t
91 *
92 * Atomically increments @l by 1
93 * and returns true if the result is zero, or false for all
94 * other cases.
95 */
96 static inline int local_inc_and_test(local_t *l)
97 {
98 unsigned char c;
99
100 __asm__ __volatile__(
101 _ASM_INC "%0; sete %1"
102 :"+m" (l->a.counter), "=qm" (c)
103 : : "memory");
104 return c != 0;
105 }
106
107 /**
108 * local_add_negative - add and test if negative
109 * @i: integer value to add
110 * @l: pointer to type local_t
111 *
112 * Atomically adds @i to @l and returns true
113 * if the result is negative, or false when
114 * result is greater than or equal to zero.
115 */
116 static inline int local_add_negative(long i, local_t *l)
117 {
118 unsigned char c;
119
120 __asm__ __volatile__(
121 _ASM_ADD "%2,%0; sets %1"
122 :"+m" (l->a.counter), "=qm" (c)
123 :"ir" (i) : "memory");
124 return c;
125 }
126
127 /**
128 * local_add_return - add and return
129 * @i: integer value to add
130 * @l: pointer to type local_t
131 *
132 * Atomically adds @i to @l and returns @i + @l
133 */
134 static inline long local_add_return(long i, local_t *l)
135 {
136 long __i;
137 #ifdef CONFIG_M386
138 unsigned long flags;
139 if (unlikely(boot_cpu_data.x86 <= 3))
140 goto no_xadd;
141 #endif
142 /* Modern 486+ processor */
143 __i = i;
144 __asm__ __volatile__(
145 _ASM_XADD "%0, %1;"
146 :"+r" (i), "+m" (l->a.counter)
147 : : "memory");
148 return i + __i;
149
150 #ifdef CONFIG_M386
151 no_xadd: /* Legacy 386 processor */
152 local_irq_save(flags);
153 __i = local_read(l);
154 local_set(l, i + __i);
155 local_irq_restore(flags);
156 return i + __i;
157 #endif
158 }
159
160 static inline long local_sub_return(long i, local_t *l)
161 {
162 return local_add_return(-i, l);
163 }
164
165 #define local_inc_return(l) (local_add_return(1, l))
166 #define local_dec_return(l) (local_sub_return(1, l))
167
168 #define local_cmpxchg(l, o, n) \
169 (cmpxchg_local(&((l)->a.counter), (o), (n)))
170 /* Always has a lock prefix */
171 #define local_xchg(l, n) (xchg(&((l)->a.counter), (n)))
172
173 /**
174 * local_add_unless - add unless the number is a given value
175 * @l: pointer of type local_t
176 * @a: the amount to add to l...
177 * @u: ...unless l is equal to u.
178 *
179 * Atomically adds @a to @l, so long as it was not @u.
180 * Returns non-zero if @l was not @u, and zero otherwise.
181 */
182 #define local_add_unless(l, a, u) \
183 ({ \
184 long c, old; \
185 c = local_read(l); \
186 for (;;) { \
187 if (unlikely(c == (u))) \
188 break; \
189 old = local_cmpxchg((l), c, c + (a)); \
190 if (likely(old == c)) \
191 break; \
192 c = old; \
193 } \
194 c != (u); \
195 })
196 #define local_inc_not_zero(l) local_add_unless((l), 1, 0)
197
198 /* On x86_32, these are no better than the atomic variants.
199 * On x86-64 these are better than the atomic variants on SMP kernels
200 * because they dont use a lock prefix.
201 */
202 #define __local_inc(l) local_inc(l)
203 #define __local_dec(l) local_dec(l)
204 #define __local_add(i, l) local_add((i), (l))
205 #define __local_sub(i, l) local_sub((i), (l))
206
207 /* Use these for per-cpu local_t variables: on some archs they are
208 * much more efficient than these naive implementations. Note they take
209 * a variable, not an address.
210 *
211 * X86_64: This could be done better if we moved the per cpu data directly
212 * after GS.
213 */
214
215 /* Need to disable preemption for the cpu local counters otherwise we could
216 still access a variable of a previous CPU in a non atomic way. */
217 #define cpu_local_wrap_v(l) \
218 ({ local_t res__; \
219 preempt_disable(); \
220 res__ = (l); \
221 preempt_enable(); \
222 res__; })
223 #define cpu_local_wrap(l) \
224 ({ preempt_disable(); \
225 l; \
226 preempt_enable(); }) \
227
228 #define cpu_local_read(l) cpu_local_wrap_v(local_read(&__get_cpu_var(l)))
229 #define cpu_local_set(l, i) cpu_local_wrap(local_set(&__get_cpu_var(l), (i)))
230 #define cpu_local_inc(l) cpu_local_wrap(local_inc(&__get_cpu_var(l)))
231 #define cpu_local_dec(l) cpu_local_wrap(local_dec(&__get_cpu_var(l)))
232 #define cpu_local_add(i, l) cpu_local_wrap(local_add((i), &__get_cpu_var(l)))
233 #define cpu_local_sub(i, l) cpu_local_wrap(local_sub((i), &__get_cpu_var(l)))
234
235 #define __cpu_local_inc(l) cpu_local_inc(l)
236 #define __cpu_local_dec(l) cpu_local_dec(l)
237 #define __cpu_local_add(i, l) cpu_local_add((i), (l))
238 #define __cpu_local_sub(i, l) cpu_local_sub((i), (l))
239
240 #endif /* _ARCH_LOCAL_H */
241
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