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1/*
2 * Atomic operations that C can't guarantee us. Useful for
3 * resource counting etc..
4 *
5 * But use these as seldom as possible since they are much more slower
6 * than regular operations.
7 *
8 * This file is subject to the terms and conditions of the GNU General Public
9 * License. See the file "COPYING" in the main directory of this archive
10 * for more details.
11 *
12 * Copyright (C) 1996, 97, 99, 2000, 03, 04, 06 by Ralf Baechle
13 */
14#ifndef _ASM_ATOMIC_H
15#define _ASM_ATOMIC_H
16
17#include <linux/irqflags.h>
18#include <linux/types.h>
19#include <asm/asm.h>
20#include <asm/barrier.h>
21#include <asm/compiler.h>
22#include <asm/cpu-features.h>
23#include <asm/cmpxchg.h>
24#include <asm/sync.h>
25
26#define ATOMIC_OPS(pfx, type) \
27static __always_inline type arch_##pfx##_read(const pfx##_t *v) \
28{ \
29 return READ_ONCE(v->counter); \
30} \
31 \
32static __always_inline void arch_##pfx##_set(pfx##_t *v, type i) \
33{ \
34 WRITE_ONCE(v->counter, i); \
35} \
36
37ATOMIC_OPS(atomic, int)
38
39#ifdef CONFIG_64BIT
40# define ATOMIC64_INIT(i) { (i) }
41ATOMIC_OPS(atomic64, s64)
42#endif
43
44#define ATOMIC_OP(pfx, op, type, c_op, asm_op, ll, sc) \
45static __inline__ void arch_##pfx##_##op(type i, pfx##_t * v) \
46{ \
47 type temp; \
48 \
49 if (!kernel_uses_llsc) { \
50 unsigned long flags; \
51 \
52 raw_local_irq_save(flags); \
53 v->counter c_op i; \
54 raw_local_irq_restore(flags); \
55 return; \
56 } \
57 \
58 __asm__ __volatile__( \
59 " .set push \n" \
60 " .set " MIPS_ISA_LEVEL " \n" \
61 " " __SYNC(full, loongson3_war) " \n" \
62 "1: " #ll " %0, %1 # " #pfx "_" #op " \n" \
63 " " #asm_op " %0, %2 \n" \
64 " " #sc " %0, %1 \n" \
65 "\t" __stringify(SC_BEQZ) " %0, 1b \n" \
66 " .set pop \n" \
67 : "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (v->counter) \
68 : "Ir" (i) : __LLSC_CLOBBER); \
69}
70
71#define ATOMIC_OP_RETURN(pfx, op, type, c_op, asm_op, ll, sc) \
72static __inline__ type \
73arch_##pfx##_##op##_return_relaxed(type i, pfx##_t * v) \
74{ \
75 type temp, result; \
76 \
77 if (!kernel_uses_llsc) { \
78 unsigned long flags; \
79 \
80 raw_local_irq_save(flags); \
81 result = v->counter; \
82 result c_op i; \
83 v->counter = result; \
84 raw_local_irq_restore(flags); \
85 return result; \
86 } \
87 \
88 __asm__ __volatile__( \
89 " .set push \n" \
90 " .set " MIPS_ISA_LEVEL " \n" \
91 " " __SYNC(full, loongson3_war) " \n" \
92 "1: " #ll " %1, %2 # " #pfx "_" #op "_return\n" \
93 " " #asm_op " %0, %1, %3 \n" \
94 " " #sc " %0, %2 \n" \
95 "\t" __stringify(SC_BEQZ) " %0, 1b \n" \
96 " " #asm_op " %0, %1, %3 \n" \
97 " .set pop \n" \
98 : "=&r" (result), "=&r" (temp), \
99 "+" GCC_OFF_SMALL_ASM() (v->counter) \
100 : "Ir" (i) : __LLSC_CLOBBER); \
101 \
102 return result; \
103}
104
105#define ATOMIC_FETCH_OP(pfx, op, type, c_op, asm_op, ll, sc) \
106static __inline__ type \
107arch_##pfx##_fetch_##op##_relaxed(type i, pfx##_t * v) \
108{ \
109 int temp, result; \
110 \
111 if (!kernel_uses_llsc) { \
112 unsigned long flags; \
113 \
114 raw_local_irq_save(flags); \
115 result = v->counter; \
116 v->counter c_op i; \
117 raw_local_irq_restore(flags); \
118 return result; \
119 } \
120 \
121 __asm__ __volatile__( \
122 " .set push \n" \
123 " .set " MIPS_ISA_LEVEL " \n" \
124 " " __SYNC(full, loongson3_war) " \n" \
125 "1: " #ll " %1, %2 # " #pfx "_fetch_" #op "\n" \
126 " " #asm_op " %0, %1, %3 \n" \
127 " " #sc " %0, %2 \n" \
128 "\t" __stringify(SC_BEQZ) " %0, 1b \n" \
129 " .set pop \n" \
130 " move %0, %1 \n" \
131 : "=&r" (result), "=&r" (temp), \
132 "+" GCC_OFF_SMALL_ASM() (v->counter) \
133 : "Ir" (i) : __LLSC_CLOBBER); \
134 \
135 return result; \
136}
137
138#undef ATOMIC_OPS
139#define ATOMIC_OPS(pfx, op, type, c_op, asm_op, ll, sc) \
140 ATOMIC_OP(pfx, op, type, c_op, asm_op, ll, sc) \
141 ATOMIC_OP_RETURN(pfx, op, type, c_op, asm_op, ll, sc) \
142 ATOMIC_FETCH_OP(pfx, op, type, c_op, asm_op, ll, sc)
143
144ATOMIC_OPS(atomic, add, int, +=, addu, ll, sc)
145ATOMIC_OPS(atomic, sub, int, -=, subu, ll, sc)
146
147#define arch_atomic_add_return_relaxed arch_atomic_add_return_relaxed
148#define arch_atomic_sub_return_relaxed arch_atomic_sub_return_relaxed
149#define arch_atomic_fetch_add_relaxed arch_atomic_fetch_add_relaxed
150#define arch_atomic_fetch_sub_relaxed arch_atomic_fetch_sub_relaxed
151
152#ifdef CONFIG_64BIT
153ATOMIC_OPS(atomic64, add, s64, +=, daddu, lld, scd)
154ATOMIC_OPS(atomic64, sub, s64, -=, dsubu, lld, scd)
155# define arch_atomic64_add_return_relaxed arch_atomic64_add_return_relaxed
156# define arch_atomic64_sub_return_relaxed arch_atomic64_sub_return_relaxed
157# define arch_atomic64_fetch_add_relaxed arch_atomic64_fetch_add_relaxed
158# define arch_atomic64_fetch_sub_relaxed arch_atomic64_fetch_sub_relaxed
159#endif /* CONFIG_64BIT */
160
161#undef ATOMIC_OPS
162#define ATOMIC_OPS(pfx, op, type, c_op, asm_op, ll, sc) \
163 ATOMIC_OP(pfx, op, type, c_op, asm_op, ll, sc) \
164 ATOMIC_FETCH_OP(pfx, op, type, c_op, asm_op, ll, sc)
165
166ATOMIC_OPS(atomic, and, int, &=, and, ll, sc)
167ATOMIC_OPS(atomic, or, int, |=, or, ll, sc)
168ATOMIC_OPS(atomic, xor, int, ^=, xor, ll, sc)
169
170#define arch_atomic_fetch_and_relaxed arch_atomic_fetch_and_relaxed
171#define arch_atomic_fetch_or_relaxed arch_atomic_fetch_or_relaxed
172#define arch_atomic_fetch_xor_relaxed arch_atomic_fetch_xor_relaxed
173
174#ifdef CONFIG_64BIT
175ATOMIC_OPS(atomic64, and, s64, &=, and, lld, scd)
176ATOMIC_OPS(atomic64, or, s64, |=, or, lld, scd)
177ATOMIC_OPS(atomic64, xor, s64, ^=, xor, lld, scd)
178# define arch_atomic64_fetch_and_relaxed arch_atomic64_fetch_and_relaxed
179# define arch_atomic64_fetch_or_relaxed arch_atomic64_fetch_or_relaxed
180# define arch_atomic64_fetch_xor_relaxed arch_atomic64_fetch_xor_relaxed
181#endif
182
183#undef ATOMIC_OPS
184#undef ATOMIC_FETCH_OP
185#undef ATOMIC_OP_RETURN
186#undef ATOMIC_OP
187
188/*
189 * atomic_sub_if_positive - conditionally subtract integer from atomic variable
190 * @i: integer value to subtract
191 * @v: pointer of type atomic_t
192 *
193 * Atomically test @v and subtract @i if @v is greater or equal than @i.
194 * The function returns the old value of @v minus @i.
195 */
196#define ATOMIC_SIP_OP(pfx, type, op, ll, sc) \
197static __inline__ type arch_##pfx##_sub_if_positive(type i, pfx##_t * v) \
198{ \
199 type temp, result; \
200 \
201 smp_mb__before_atomic(); \
202 \
203 if (!kernel_uses_llsc) { \
204 unsigned long flags; \
205 \
206 raw_local_irq_save(flags); \
207 result = v->counter; \
208 result -= i; \
209 if (result >= 0) \
210 v->counter = result; \
211 raw_local_irq_restore(flags); \
212 smp_mb__after_atomic(); \
213 return result; \
214 } \
215 \
216 __asm__ __volatile__( \
217 " .set push \n" \
218 " .set " MIPS_ISA_LEVEL " \n" \
219 " " __SYNC(full, loongson3_war) " \n" \
220 "1: " #ll " %1, %2 # atomic_sub_if_positive\n" \
221 " .set pop \n" \
222 " " #op " %0, %1, %3 \n" \
223 " move %1, %0 \n" \
224 " bltz %0, 2f \n" \
225 " .set push \n" \
226 " .set " MIPS_ISA_LEVEL " \n" \
227 " " #sc " %1, %2 \n" \
228 " " __stringify(SC_BEQZ) " %1, 1b \n" \
229 "2: " __SYNC(full, loongson3_war) " \n" \
230 " .set pop \n" \
231 : "=&r" (result), "=&r" (temp), \
232 "+" GCC_OFF_SMALL_ASM() (v->counter) \
233 : "Ir" (i) \
234 : __LLSC_CLOBBER); \
235 \
236 /* \
237 * In the Loongson3 workaround case we already have a \
238 * completion barrier at 2: above, which is needed due to the \
239 * bltz that can branch to code outside of the LL/SC loop. As \
240 * such, we don't need to emit another barrier here. \
241 */ \
242 if (__SYNC_loongson3_war == 0) \
243 smp_mb__after_atomic(); \
244 \
245 return result; \
246}
247
248ATOMIC_SIP_OP(atomic, int, subu, ll, sc)
249#define arch_atomic_dec_if_positive(v) arch_atomic_sub_if_positive(1, v)
250
251#ifdef CONFIG_64BIT
252ATOMIC_SIP_OP(atomic64, s64, dsubu, lld, scd)
253#define arch_atomic64_dec_if_positive(v) arch_atomic64_sub_if_positive(1, v)
254#endif
255
256#undef ATOMIC_SIP_OP
257
258#endif /* _ASM_ATOMIC_H */
259

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source code of linux/arch/mips/include/asm/atomic.h