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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 | ||
864a1eda | 17 | #include "ust-helper.h" |
9f47aac8 | 18 | |
10544ee8 MD |
19 | #ifdef __cplusplus |
20 | extern "C" { | |
21 | #endif | |
22 | ||
23 | #define FUTEX_WAIT 0 | |
24 | #define FUTEX_WAKE 1 | |
25 | ||
26 | /* | |
27 | * sys_futex compatibility header. | |
28 | * Use *only* *either of* futex_noasync OR futex_async on a given address. | |
29 | * | |
30 | * futex_noasync cannot be executed in signal handlers, but ensures that | |
31 | * it will be put in a wait queue even in compatibility mode. | |
32 | * | |
33 | * futex_async is signal-handler safe for the wakeup. It uses polling | |
34 | * on the wait-side in compatibility mode. | |
35 | * | |
36 | * BEWARE: sys_futex() FUTEX_WAIT may return early if interrupted | |
37 | * (returns EINTR). | |
38 | */ | |
39 | ||
9f47aac8 | 40 | LTTNG_HIDDEN |
10544ee8 MD |
41 | extern int lttng_ust_compat_futex_noasync(int32_t *uaddr, int op, int32_t val, |
42 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3); | |
9f47aac8 | 43 | LTTNG_HIDDEN |
10544ee8 MD |
44 | extern int lttng_ust_compat_futex_async(int32_t *uaddr, int op, int32_t val, |
45 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3); | |
46 | ||
47 | #if (defined(__linux__) && defined(__NR_futex)) | |
48 | ||
49 | #include <unistd.h> | |
50 | #include <errno.h> | |
51 | #include <urcu/compiler.h> | |
52 | #include <urcu/arch.h> | |
53 | ||
54 | static inline int lttng_ust_futex(int32_t *uaddr, int op, int32_t val, | |
55 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
56 | { | |
57 | return syscall(__NR_futex, uaddr, op, val, timeout, | |
58 | uaddr2, val3); | |
59 | } | |
60 | ||
61 | static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val, | |
62 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
63 | { | |
64 | int ret; | |
65 | ||
66 | ret = lttng_ust_futex(uaddr, op, val, timeout, uaddr2, val3); | |
67 | if (caa_unlikely(ret < 0 && errno == ENOSYS)) { | |
68 | /* | |
69 | * The fallback on ENOSYS is the async-safe version of | |
70 | * the compat futex implementation, because the | |
71 | * async-safe compat implementation allows being used | |
72 | * concurrently with calls to futex(). Indeed, sys_futex | |
73 | * FUTEX_WAIT, on some architectures (mips and parisc), | |
74 | * within a given process, spuriously return ENOSYS due | |
75 | * to signal restart bugs on some kernel versions. | |
76 | */ | |
77 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, | |
78 | uaddr2, val3); | |
79 | } | |
80 | return ret; | |
81 | ||
82 | } | |
83 | ||
84 | static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val, | |
85 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
86 | { | |
87 | int ret; | |
88 | ||
89 | ret = lttng_ust_futex(uaddr, op, val, timeout, uaddr2, val3); | |
90 | if (caa_unlikely(ret < 0 && errno == ENOSYS)) { | |
91 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, | |
92 | uaddr2, val3); | |
93 | } | |
94 | return ret; | |
95 | } | |
96 | ||
97 | #elif defined(__FreeBSD__) | |
98 | ||
99 | #include <sys/types.h> | |
100 | #include <sys/umtx.h> | |
101 | ||
102 | static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val, | |
103 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
104 | { | |
105 | int umtx_op; | |
106 | void *umtx_uaddr = NULL, *umtx_uaddr2 = NULL; | |
107 | struct _umtx_time umtx_timeout = { | |
108 | ._flags = UMTX_ABSTIME, | |
109 | ._clockid = CLOCK_MONOTONIC, | |
110 | }; | |
111 | ||
112 | switch (op) { | |
113 | case FUTEX_WAIT: | |
114 | /* On FreeBSD, a "u_int" is a 32-bit integer. */ | |
115 | umtx_op = UMTX_OP_WAIT_UINT; | |
116 | if (timeout != NULL) { | |
117 | umtx_timeout._timeout = *timeout; | |
118 | umtx_uaddr = (void *) sizeof(umtx_timeout); | |
119 | umtx_uaddr2 = (void *) &umtx_timeout; | |
120 | } | |
121 | break; | |
122 | case FUTEX_WAKE: | |
123 | umtx_op = UMTX_OP_WAKE; | |
124 | break; | |
125 | default: | |
126 | errno = EINVAL; | |
127 | return -1; | |
128 | } | |
129 | ||
130 | return _umtx_op(uaddr, umtx_op, (uint32_t) val, umtx_uaddr, | |
131 | umtx_uaddr2); | |
132 | } | |
133 | ||
134 | static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val, | |
135 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
136 | { | |
a3bdb11c | 137 | return lttng_ust_futex_async(uaddr, op, val, timeout, uaddr2, val3); |
10544ee8 MD |
138 | } |
139 | ||
140 | #elif defined(__CYGWIN__) | |
141 | ||
142 | /* | |
143 | * The futex_noasync compat code uses a weak symbol to share state across | |
144 | * different shared object which is not possible on Windows with the | |
145 | * Portable Executable format. Use the async compat code for both cases. | |
146 | */ | |
147 | static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val, | |
148 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
149 | { | |
150 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, uaddr2, val3); | |
151 | } | |
152 | ||
153 | static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val, | |
154 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
155 | { | |
156 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, uaddr2, val3); | |
157 | } | |
158 | ||
159 | #else | |
160 | ||
161 | static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val, | |
162 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
163 | { | |
164 | return lttng_ust_compat_futex_noasync(uaddr, op, val, timeout, uaddr2, val3); | |
165 | } | |
166 | ||
167 | static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val, | |
168 | const struct timespec *timeout, int32_t *uaddr2, int32_t val3) | |
169 | { | |
170 | return lttng_ust_compat_futex_async(uaddr, op, val, timeout, uaddr2, val3); | |
171 | } | |
172 | ||
173 | #endif | |
174 | ||
175 | #ifdef __cplusplus | |
176 | } | |
177 | #endif | |
178 | ||
179 | #endif /* _LTTNG_UST_FUTEX_H */ |