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d3d3857f MJ |
1 | // SPDX-FileCopyrightText: 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
2 | // | |
3 | // SPDX-License-Identifier: LGPL-2.1-or-later | |
4 | ||
49617de1 MD |
5 | #ifndef _URCU_FUTEX_H |
6 | #define _URCU_FUTEX_H | |
7 | ||
8 | /* | |
49617de1 | 9 | * Userspace RCU - sys_futex/compat_futex header. |
49617de1 MD |
10 | */ |
11 | ||
12 | #include <urcu/config.h> | |
ca91060e MJ |
13 | #include <urcu/syscall-compat.h> |
14 | ||
32146086 | 15 | #include <errno.h> |
6d841bc2 | 16 | #include <stdint.h> |
6a29bfc1 | 17 | #include <time.h> |
49617de1 | 18 | |
d428afc4 MD |
19 | #if (defined(__linux__) && defined(__NR_futex)) |
20 | ||
21 | /* For backwards compat */ | |
22 | #define CONFIG_RCU_HAVE_FUTEX 1 | |
23 | ||
24 | #include <unistd.h> | |
25 | #include <errno.h> | |
26 | #include <urcu/compiler.h> | |
27 | #include <urcu/arch.h> | |
28 | ||
29 | #elif defined(__FreeBSD__) | |
30 | ||
31 | #include <sys/types.h> | |
32 | #include <sys/umtx.h> | |
33 | ||
34 | #endif | |
35 | ||
36bc70a8 MD |
36 | #ifdef __cplusplus |
37 | extern "C" { | |
67ecffc0 | 38 | #endif |
36bc70a8 | 39 | |
49617de1 MD |
40 | #define FUTEX_WAIT 0 |
41 | #define FUTEX_WAKE 1 | |
42 | ||
43 | /* | |
44 | * sys_futex compatibility header. | |
45 | * Use *only* *either of* futex_noasync OR futex_async on a given address. | |
46 | * | |
47 | * futex_noasync cannot be executed in signal handlers, but ensures that | |
48 | * it will be put in a wait queue even in compatibility mode. | |
49 | * | |
50 | * futex_async is signal-handler safe for the wakeup. It uses polling | |
51 | * on the wait-side in compatibility mode. | |
b0a841b4 MD |
52 | * |
53 | * BEWARE: sys_futex() FUTEX_WAIT may return early if interrupted | |
54 | * (returns EINTR). | |
49617de1 MD |
55 | */ |
56 | ||
42dfe454 MD |
57 | extern int compat_futex_noasync(int32_t *uaddr, int op, int32_t val, |
58 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3); | |
59 | extern int compat_futex_async(int32_t *uaddr, int op, int32_t val, | |
60 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3); | |
61 | ||
0afb29b2 | 62 | #if (defined(__linux__) && defined(__NR_futex)) |
ca91060e | 63 | |
42dfe454 MD |
64 | static inline int futex(int32_t *uaddr, int op, int32_t val, |
65 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
66 | { | |
67 | return syscall(__NR_futex, uaddr, op, val, timeout, | |
68 | uaddr2, val3); | |
69 | } | |
70 | ||
71 | static inline int futex_noasync(int32_t *uaddr, int op, int32_t val, | |
72 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
73 | { | |
74 | int ret; | |
75 | ||
76 | ret = futex(uaddr, op, val, timeout, uaddr2, val3); | |
77 | if (caa_unlikely(ret < 0 && errno == ENOSYS)) { | |
b2633d21 MD |
78 | /* |
79 | * The fallback on ENOSYS is the async-safe version of | |
80 | * the compat futex implementation, because the | |
81 | * async-safe compat implementation allows being used | |
82 | * concurrently with calls to futex(). Indeed, sys_futex | |
83 | * FUTEX_WAIT, on some architectures (mips and parisc), | |
84 | * within a given process, spuriously return ENOSYS due | |
85 | * to signal restart bugs on some kernel versions. | |
86 | */ | |
87 | return compat_futex_async(uaddr, op, val, timeout, | |
42dfe454 MD |
88 | uaddr2, val3); |
89 | } | |
90 | return ret; | |
91 | ||
92 | } | |
93 | ||
94 | static inline int futex_async(int32_t *uaddr, int op, int32_t val, | |
95 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
96 | { | |
97 | int ret; | |
98 | ||
99 | ret = futex(uaddr, op, val, timeout, uaddr2, val3); | |
100 | if (caa_unlikely(ret < 0 && errno == ENOSYS)) { | |
101 | return compat_futex_async(uaddr, op, val, timeout, | |
102 | uaddr2, val3); | |
103 | } | |
104 | return ret; | |
105 | } | |
106 | ||
32146086 AX |
107 | #elif defined(__FreeBSD__) |
108 | ||
32146086 | 109 | static inline int futex_async(int32_t *uaddr, int op, int32_t val, |
a142df4e MJ |
110 | const struct timespec *timeout, |
111 | int32_t *uaddr2 __attribute__((unused)), | |
112 | int32_t val3 __attribute__((unused))) | |
32146086 AX |
113 | { |
114 | int umtx_op; | |
115 | void *umtx_uaddr = NULL, *umtx_uaddr2 = NULL; | |
116 | struct _umtx_time umtx_timeout = { | |
117 | ._flags = UMTX_ABSTIME, | |
118 | ._clockid = CLOCK_MONOTONIC, | |
119 | }; | |
120 | ||
121 | switch (op) { | |
122 | case FUTEX_WAIT: | |
123 | /* On FreeBSD, a "u_int" is a 32-bit integer. */ | |
124 | umtx_op = UMTX_OP_WAIT_UINT; | |
125 | if (timeout != NULL) { | |
126 | umtx_timeout._timeout = *timeout; | |
127 | umtx_uaddr = (void *) sizeof(umtx_timeout); | |
128 | umtx_uaddr2 = (void *) &umtx_timeout; | |
129 | } | |
130 | break; | |
131 | case FUTEX_WAKE: | |
132 | umtx_op = UMTX_OP_WAKE; | |
133 | break; | |
134 | default: | |
135 | errno = EINVAL; | |
136 | return -1; | |
137 | } | |
138 | ||
139 | return _umtx_op(uaddr, umtx_op, (uint32_t) val, umtx_uaddr, | |
140 | umtx_uaddr2); | |
141 | } | |
142 | ||
143 | static inline int futex_noasync(int32_t *uaddr, int op, int32_t val, | |
144 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
145 | { | |
146 | return futex_async(uaddr, op, val, timeout, uaddr2, val3); | |
147 | } | |
148 | ||
bb109fb6 MJ |
149 | #elif defined(__CYGWIN__) |
150 | ||
151 | /* | |
152 | * The futex_noasync compat code uses a weak symbol to share state across | |
153 | * different shared object which is not possible on Windows with the | |
154 | * Portable Executable format. Use the async compat code for both cases. | |
155 | */ | |
156 | static inline int futex_noasync(int32_t *uaddr, int op, int32_t val, | |
157 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
158 | { | |
159 | return compat_futex_async(uaddr, op, val, timeout, uaddr2, val3); | |
160 | } | |
161 | ||
162 | static inline int futex_async(int32_t *uaddr, int op, int32_t val, | |
163 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
164 | { | |
165 | return compat_futex_async(uaddr, op, val, timeout, uaddr2, val3); | |
166 | } | |
167 | ||
49617de1 | 168 | #else |
42dfe454 MD |
169 | |
170 | static inline int futex_noasync(int32_t *uaddr, int op, int32_t val, | |
171 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
172 | { | |
173 | return compat_futex_noasync(uaddr, op, val, timeout, uaddr2, val3); | |
174 | } | |
175 | ||
176 | static inline int futex_async(int32_t *uaddr, int op, int32_t val, | |
177 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
178 | { | |
179 | return compat_futex_async(uaddr, op, val, timeout, uaddr2, val3); | |
180 | } | |
181 | ||
49617de1 MD |
182 | #endif |
183 | ||
67ecffc0 | 184 | #ifdef __cplusplus |
36bc70a8 MD |
185 | } |
186 | #endif | |
187 | ||
49617de1 | 188 | #endif /* _URCU_FUTEX_H */ |