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10544ee8 | 1 | /* |
c0c0989a | 2 | * SPDX-License-Identifier: LGPL-2.1-or-later |
10544ee8 | 3 | * |
c0c0989a | 4 | * Copyright 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
10544ee8 | 5 | * |
c0c0989a | 6 | * Userspace RCU - sys_futex/compat_futex header. |
10544ee8 MD |
7 | */ |
8 | ||
c0c0989a MJ |
9 | #ifndef _LTTNG_UST_FUTEX_H |
10 | #define _LTTNG_UST_FUTEX_H | |
11 | ||
10544ee8 MD |
12 | #include <errno.h> |
13 | #include <stdint.h> | |
14 | #include <time.h> | |
15 | #include <sys/syscall.h> | |
16 | ||
17 | #ifdef __cplusplus | |
18 | extern "C" { | |
19 | #endif | |
20 | ||
21 | #define FUTEX_WAIT 0 | |
22 | #define FUTEX_WAKE 1 | |
23 | ||
24 | /* | |
25 | * sys_futex compatibility header. | |
26 | * Use *only* *either of* futex_noasync OR futex_async on a given address. | |
27 | * | |
28 | * futex_noasync cannot be executed in signal handlers, but ensures that | |
29 | * it will be put in a wait queue even in compatibility mode. | |
30 | * | |
31 | * futex_async is signal-handler safe for the wakeup. It uses polling | |
32 | * on the wait-side in compatibility mode. | |
33 | * | |
34 | * BEWARE: sys_futex() FUTEX_WAIT may return early if interrupted | |
35 | * (returns EINTR). | |
36 | */ | |
37 | ||
38 | extern int lttng_ust_compat_futex_noasync(int32_t *uaddr, int op, int32_t val, | |
1d18d519 MJ |
39 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) |
40 | __attribute__((visibility("hidden"))); | |
ddabe860 | 41 | |
10544ee8 | 42 | extern int lttng_ust_compat_futex_async(int32_t *uaddr, int op, int32_t val, |
1d18d519 MJ |
43 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) |
44 | __attribute__((visibility("hidden"))); | |
10544ee8 MD |
45 | |
46 | #if (defined(__linux__) && defined(__NR_futex)) | |
47 | ||
48 | #include <unistd.h> | |
49 | #include <errno.h> | |
50 | #include <urcu/compiler.h> | |
51 | #include <urcu/arch.h> | |
52 | ||
53 | static inline int lttng_ust_futex(int32_t *uaddr, int op, int32_t val, | |
54 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
55 | { | |
56 | return syscall(__NR_futex, uaddr, op, val, timeout, | |
57 | uaddr2, val3); | |
58 | } | |
59 | ||
60 | static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val, | |
61 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
62 | { | |
63 | int ret; | |
64 | ||
65 | ret = lttng_ust_futex(uaddr, op, val, timeout, uaddr2, val3); | |
66 | if (caa_unlikely(ret < 0 && errno == ENOSYS)) { | |
67 | /* | |
68 | * The fallback on ENOSYS is the async-safe version of | |
69 | * the compat futex implementation, because the | |
70 | * async-safe compat implementation allows being used | |
71 | * concurrently with calls to futex(). Indeed, sys_futex | |
72 | * FUTEX_WAIT, on some architectures (mips and parisc), | |
73 | * within a given process, spuriously return ENOSYS due | |
74 | * to signal restart bugs on some kernel versions. | |
75 | */ | |
76 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, | |
77 | uaddr2, val3); | |
78 | } | |
79 | return ret; | |
80 | ||
81 | } | |
82 | ||
83 | static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val, | |
84 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
85 | { | |
86 | int ret; | |
87 | ||
88 | ret = lttng_ust_futex(uaddr, op, val, timeout, uaddr2, val3); | |
89 | if (caa_unlikely(ret < 0 && errno == ENOSYS)) { | |
90 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, | |
91 | uaddr2, val3); | |
92 | } | |
93 | return ret; | |
94 | } | |
95 | ||
96 | #elif defined(__FreeBSD__) | |
97 | ||
98 | #include <sys/types.h> | |
99 | #include <sys/umtx.h> | |
100 | ||
101 | static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val, | |
102 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
103 | { | |
104 | int umtx_op; | |
105 | void *umtx_uaddr = NULL, *umtx_uaddr2 = NULL; | |
106 | struct _umtx_time umtx_timeout = { | |
107 | ._flags = UMTX_ABSTIME, | |
108 | ._clockid = CLOCK_MONOTONIC, | |
109 | }; | |
110 | ||
111 | switch (op) { | |
112 | case FUTEX_WAIT: | |
113 | /* On FreeBSD, a "u_int" is a 32-bit integer. */ | |
114 | umtx_op = UMTX_OP_WAIT_UINT; | |
115 | if (timeout != NULL) { | |
116 | umtx_timeout._timeout = *timeout; | |
117 | umtx_uaddr = (void *) sizeof(umtx_timeout); | |
118 | umtx_uaddr2 = (void *) &umtx_timeout; | |
119 | } | |
120 | break; | |
121 | case FUTEX_WAKE: | |
122 | umtx_op = UMTX_OP_WAKE; | |
123 | break; | |
124 | default: | |
125 | errno = EINVAL; | |
126 | return -1; | |
127 | } | |
128 | ||
129 | return _umtx_op(uaddr, umtx_op, (uint32_t) val, umtx_uaddr, | |
130 | umtx_uaddr2); | |
131 | } | |
132 | ||
133 | static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val, | |
134 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
135 | { | |
a3bdb11c | 136 | return lttng_ust_futex_async(uaddr, op, val, timeout, uaddr2, val3); |
10544ee8 MD |
137 | } |
138 | ||
139 | #elif defined(__CYGWIN__) | |
140 | ||
141 | /* | |
142 | * The futex_noasync compat code uses a weak symbol to share state across | |
143 | * different shared object which is not possible on Windows with the | |
144 | * Portable Executable format. Use the async compat code for both cases. | |
145 | */ | |
146 | static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val, | |
147 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
148 | { | |
149 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, uaddr2, val3); | |
150 | } | |
151 | ||
152 | static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val, | |
153 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
154 | { | |
155 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, uaddr2, val3); | |
156 | } | |
157 | ||
158 | #else | |
159 | ||
160 | static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val, | |
161 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
162 | { | |
163 | return lttng_ust_compat_futex_noasync(uaddr, op, val, timeout, uaddr2, val3); | |
164 | } | |
165 | ||
166 | static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val, | |
167 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
168 | { | |
169 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, uaddr2, val3); | |
170 | } | |
171 | ||
172 | #endif | |
173 | ||
174 | #ifdef __cplusplus | |
175 | } | |
176 | #endif | |
177 | ||
178 | #endif /* _LTTNG_UST_FUTEX_H */ |