]>
Commit | Line | Data |
---|---|---|
b4d0d230 | 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
93ea02bb | 2 | /* |
739d875d | 3 | * Generic barrier definitions. |
885df91c DH |
4 | * |
5 | * It should be possible to use these on really simple architectures, | |
6 | * but it serves more as a starting point for new ports. | |
7 | * | |
8 | * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. | |
9 | * Written by David Howells (dhowells@redhat.com) | |
885df91c DH |
10 | */ |
11 | #ifndef __ASM_GENERIC_BARRIER_H | |
12 | #define __ASM_GENERIC_BARRIER_H | |
13 | ||
14 | #ifndef __ASSEMBLY__ | |
15 | ||
e506ea45 | 16 | #include <asm/rwonce.h> |
93ea02bb PZ |
17 | |
18 | #ifndef nop | |
19 | #define nop() asm volatile ("nop") | |
20 | #endif | |
885df91c DH |
21 | |
22 | /* | |
93ea02bb PZ |
23 | * Force strict CPU ordering. And yes, this is required on UP too when we're |
24 | * talking to devices. | |
885df91c | 25 | * |
93ea02bb | 26 | * Fall back to compiler barriers if nothing better is provided. |
885df91c DH |
27 | */ |
28 | ||
93ea02bb PZ |
29 | #ifndef mb |
30 | #define mb() barrier() | |
31 | #endif | |
32 | ||
33 | #ifndef rmb | |
885df91c | 34 | #define rmb() mb() |
93ea02bb PZ |
35 | #endif |
36 | ||
37 | #ifndef wmb | |
38 | #define wmb() mb() | |
39 | #endif | |
40 | ||
1077fa36 AD |
41 | #ifndef dma_rmb |
42 | #define dma_rmb() rmb() | |
43 | #endif | |
44 | ||
45 | #ifndef dma_wmb | |
46 | #define dma_wmb() wmb() | |
47 | #endif | |
48 | ||
a9e4252a MT |
49 | #ifndef __smp_mb |
50 | #define __smp_mb() mb() | |
51 | #endif | |
52 | ||
53 | #ifndef __smp_rmb | |
54 | #define __smp_rmb() rmb() | |
55 | #endif | |
56 | ||
57 | #ifndef __smp_wmb | |
58 | #define __smp_wmb() wmb() | |
59 | #endif | |
60 | ||
885df91c | 61 | #ifdef CONFIG_SMP |
470c27e4 VG |
62 | |
63 | #ifndef smp_mb | |
a9e4252a | 64 | #define smp_mb() __smp_mb() |
470c27e4 VG |
65 | #endif |
66 | ||
67 | #ifndef smp_rmb | |
a9e4252a | 68 | #define smp_rmb() __smp_rmb() |
470c27e4 VG |
69 | #endif |
70 | ||
71 | #ifndef smp_wmb | |
a9e4252a | 72 | #define smp_wmb() __smp_wmb() |
470c27e4 VG |
73 | #endif |
74 | ||
0890a264 LT |
75 | #else /* !CONFIG_SMP */ |
76 | ||
470c27e4 | 77 | #ifndef smp_mb |
885df91c | 78 | #define smp_mb() barrier() |
470c27e4 VG |
79 | #endif |
80 | ||
81 | #ifndef smp_rmb | |
885df91c | 82 | #define smp_rmb() barrier() |
470c27e4 VG |
83 | #endif |
84 | ||
85 | #ifndef smp_wmb | |
885df91c | 86 | #define smp_wmb() barrier() |
470c27e4 VG |
87 | #endif |
88 | ||
0890a264 | 89 | #endif /* CONFIG_SMP */ |
470c27e4 | 90 | |
a9e4252a MT |
91 | #ifndef __smp_store_mb |
92 | #define __smp_store_mb(var, value) do { WRITE_ONCE(var, value); __smp_mb(); } while (0) | |
93 | #endif | |
94 | ||
95 | #ifndef __smp_mb__before_atomic | |
96 | #define __smp_mb__before_atomic() __smp_mb() | |
97 | #endif | |
98 | ||
99 | #ifndef __smp_mb__after_atomic | |
100 | #define __smp_mb__after_atomic() __smp_mb() | |
101 | #endif | |
102 | ||
103 | #ifndef __smp_store_release | |
104 | #define __smp_store_release(p, v) \ | |
105 | do { \ | |
106 | compiletime_assert_atomic_type(*p); \ | |
107 | __smp_mb(); \ | |
108 | WRITE_ONCE(*p, v); \ | |
109 | } while (0) | |
110 | #endif | |
111 | ||
112 | #ifndef __smp_load_acquire | |
113 | #define __smp_load_acquire(p) \ | |
114 | ({ \ | |
54988727 | 115 | __unqual_scalar_typeof(*p) ___p1 = READ_ONCE(*p); \ |
a9e4252a MT |
116 | compiletime_assert_atomic_type(*p); \ |
117 | __smp_mb(); \ | |
54988727 | 118 | (typeof(*p))___p1; \ |
a9e4252a MT |
119 | }) |
120 | #endif | |
121 | ||
122 | #ifdef CONFIG_SMP | |
123 | ||
124 | #ifndef smp_store_mb | |
125 | #define smp_store_mb(var, value) __smp_store_mb(var, value) | |
126 | #endif | |
127 | ||
128 | #ifndef smp_mb__before_atomic | |
129 | #define smp_mb__before_atomic() __smp_mb__before_atomic() | |
130 | #endif | |
131 | ||
132 | #ifndef smp_mb__after_atomic | |
133 | #define smp_mb__after_atomic() __smp_mb__after_atomic() | |
134 | #endif | |
135 | ||
136 | #ifndef smp_store_release | |
137 | #define smp_store_release(p, v) __smp_store_release(p, v) | |
138 | #endif | |
139 | ||
140 | #ifndef smp_load_acquire | |
141 | #define smp_load_acquire(p) __smp_load_acquire(p) | |
142 | #endif | |
143 | ||
144 | #else /* !CONFIG_SMP */ | |
145 | ||
b92b8b35 | 146 | #ifndef smp_store_mb |
a9e4252a | 147 | #define smp_store_mb(var, value) do { WRITE_ONCE(var, value); barrier(); } while (0) |
93ea02bb | 148 | #endif |
885df91c | 149 | |
febdbfe8 | 150 | #ifndef smp_mb__before_atomic |
a9e4252a | 151 | #define smp_mb__before_atomic() barrier() |
febdbfe8 PZ |
152 | #endif |
153 | ||
154 | #ifndef smp_mb__after_atomic | |
a9e4252a | 155 | #define smp_mb__after_atomic() barrier() |
febdbfe8 PZ |
156 | #endif |
157 | ||
57f7c037 | 158 | #ifndef smp_store_release |
47933ad4 PZ |
159 | #define smp_store_release(p, v) \ |
160 | do { \ | |
161 | compiletime_assert_atomic_type(*p); \ | |
a9e4252a | 162 | barrier(); \ |
76695af2 | 163 | WRITE_ONCE(*p, v); \ |
47933ad4 | 164 | } while (0) |
57f7c037 | 165 | #endif |
47933ad4 | 166 | |
57f7c037 | 167 | #ifndef smp_load_acquire |
47933ad4 PZ |
168 | #define smp_load_acquire(p) \ |
169 | ({ \ | |
54988727 | 170 | __unqual_scalar_typeof(*p) ___p1 = READ_ONCE(*p); \ |
47933ad4 | 171 | compiletime_assert_atomic_type(*p); \ |
a9e4252a | 172 | barrier(); \ |
54988727 | 173 | (typeof(*p))___p1; \ |
47933ad4 | 174 | }) |
57f7c037 | 175 | #endif |
47933ad4 | 176 | |
726328d9 | 177 | #endif /* CONFIG_SMP */ |
a9e4252a | 178 | |
6a65d263 MT |
179 | /* Barriers for virtual machine guests when talking to an SMP host */ |
180 | #define virt_mb() __smp_mb() | |
181 | #define virt_rmb() __smp_rmb() | |
182 | #define virt_wmb() __smp_wmb() | |
6a65d263 MT |
183 | #define virt_store_mb(var, value) __smp_store_mb(var, value) |
184 | #define virt_mb__before_atomic() __smp_mb__before_atomic() | |
185 | #define virt_mb__after_atomic() __smp_mb__after_atomic() | |
186 | #define virt_store_release(p, v) __smp_store_release(p, v) | |
187 | #define virt_load_acquire(p) __smp_load_acquire(p) | |
188 | ||
7cb45c0f PZ |
189 | /** |
190 | * smp_acquire__after_ctrl_dep() - Provide ACQUIRE ordering after a control dependency | |
191 | * | |
192 | * A control dependency provides a LOAD->STORE order, the additional RMB | |
193 | * provides LOAD->LOAD order, together they provide LOAD->{LOAD,STORE} order, | |
194 | * aka. (load)-ACQUIRE. | |
195 | * | |
196 | * Architectures that do not do load speculation can have this be barrier(). | |
197 | */ | |
198 | #ifndef smp_acquire__after_ctrl_dep | |
199 | #define smp_acquire__after_ctrl_dep() smp_rmb() | |
200 | #endif | |
201 | ||
202 | /** | |
fcfdfe30 | 203 | * smp_cond_load_relaxed() - (Spin) wait for cond with no ordering guarantees |
7cb45c0f PZ |
204 | * @ptr: pointer to the variable to wait on |
205 | * @cond: boolean expression to wait for | |
206 | * | |
fcfdfe30 | 207 | * Equivalent to using READ_ONCE() on the condition variable. |
7cb45c0f PZ |
208 | * |
209 | * Due to C lacking lambda expressions we load the value of *ptr into a | |
210 | * pre-named variable @VAL to be used in @cond. | |
211 | */ | |
fcfdfe30 WD |
212 | #ifndef smp_cond_load_relaxed |
213 | #define smp_cond_load_relaxed(ptr, cond_expr) ({ \ | |
7cb45c0f | 214 | typeof(ptr) __PTR = (ptr); \ |
54988727 | 215 | __unqual_scalar_typeof(*ptr) VAL; \ |
7cb45c0f PZ |
216 | for (;;) { \ |
217 | VAL = READ_ONCE(*__PTR); \ | |
218 | if (cond_expr) \ | |
219 | break; \ | |
220 | cpu_relax(); \ | |
221 | } \ | |
54988727 | 222 | (typeof(*ptr))VAL; \ |
7cb45c0f PZ |
223 | }) |
224 | #endif | |
225 | ||
fcfdfe30 WD |
226 | /** |
227 | * smp_cond_load_acquire() - (Spin) wait for cond with ACQUIRE ordering | |
228 | * @ptr: pointer to the variable to wait on | |
229 | * @cond: boolean expression to wait for | |
230 | * | |
231 | * Equivalent to using smp_load_acquire() on the condition variable but employs | |
232 | * the control dependency of the wait to reduce the barrier on many platforms. | |
233 | */ | |
234 | #ifndef smp_cond_load_acquire | |
235 | #define smp_cond_load_acquire(ptr, cond_expr) ({ \ | |
54988727 | 236 | __unqual_scalar_typeof(*ptr) _val; \ |
fcfdfe30 WD |
237 | _val = smp_cond_load_relaxed(ptr, cond_expr); \ |
238 | smp_acquire__after_ctrl_dep(); \ | |
54988727 | 239 | (typeof(*ptr))_val; \ |
fcfdfe30 WD |
240 | }) |
241 | #endif | |
242 | ||
3e79f082 AK |
243 | /* |
244 | * pmem_wmb() ensures that all stores for which the modification | |
245 | * are written to persistent storage by preceding instructions have | |
246 | * updated persistent storage before any data access or data transfer | |
247 | * caused by subsequent instructions is initiated. | |
248 | */ | |
249 | #ifndef pmem_wmb | |
250 | #define pmem_wmb() wmb() | |
251 | #endif | |
252 | ||
885df91c DH |
253 | #endif /* !__ASSEMBLY__ */ |
254 | #endif /* __ASM_GENERIC_BARRIER_H */ |