Commit | Line | Data |
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b76e5200 MD |
1 | /* |
2 | * rseq.c | |
3 | * | |
4 | * Copyright (C) 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
5 | * | |
6 | * This library is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU Lesser General Public | |
8 | * License as published by the Free Software Foundation; only | |
9 | * version 2.1 of the License. | |
10 | * | |
11 | * This library is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | * Lesser General Public License for more details. | |
15 | */ | |
16 | ||
17 | #define _GNU_SOURCE | |
18 | #include <errno.h> | |
19 | #include <sched.h> | |
20 | #include <stdio.h> | |
21 | #include <stdlib.h> | |
22 | #include <string.h> | |
23 | #include <unistd.h> | |
24 | #include <syscall.h> | |
25 | #include <assert.h> | |
26 | #include <signal.h> | |
b76e5200 MD |
27 | |
28 | #include <rseq.h> | |
29 | ||
b76e5200 MD |
30 | __attribute__((weak)) __thread volatile struct rseq __rseq_abi = { |
31 | .u.e.cpu_id = -1, | |
32 | }; | |
33 | ||
26cc635c MD |
34 | /* Own state, not shared with other libs. */ |
35 | static __thread int rseq_registered; | |
36 | ||
37 | static pthread_key_t rseq_key; | |
38 | ||
39 | ||
40 | #ifdef __NR_rseq | |
b76e5200 MD |
41 | static int sys_rseq(volatile struct rseq *rseq_abi, int flags) |
42 | { | |
43 | return syscall(__NR_rseq, rseq_abi, flags); | |
44 | } | |
26cc635c MD |
45 | #else |
46 | static int sys_rseq(volatile struct rseq *rseq_abi, int flags) | |
47 | { | |
48 | errno = ENOSYS; | |
49 | return -1; | |
50 | } | |
51 | #endif | |
b76e5200 | 52 | |
b76e5200 MD |
53 | static void signal_off_save(sigset_t *oldset) |
54 | { | |
55 | sigset_t set; | |
56 | int ret; | |
57 | ||
58 | sigfillset(&set); | |
59 | ret = pthread_sigmask(SIG_BLOCK, &set, oldset); | |
60 | if (ret) | |
61 | abort(); | |
62 | } | |
63 | ||
64 | static void signal_restore(sigset_t oldset) | |
65 | { | |
66 | int ret; | |
67 | ||
68 | ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL); | |
69 | if (ret) | |
70 | abort(); | |
71 | } | |
72 | ||
26cc635c MD |
73 | int rseq_unregister_current_thread(void) |
74 | { | |
75 | sigset_t oldset; | |
76 | int rc, ret = 0; | |
77 | ||
78 | signal_off_save(&oldset); | |
79 | if (rseq_registered) { | |
80 | rc = sys_rseq(NULL, 0); | |
81 | if (rc) { | |
82 | fprintf(stderr, "Error: sys_rseq(...) failed(%d): %s\n", | |
83 | errno, strerror(errno)); | |
84 | ret = -1; | |
85 | goto end; | |
86 | } | |
87 | rseq_registered = 0; | |
88 | } | |
89 | end: | |
90 | signal_restore(oldset); | |
91 | return ret; | |
92 | } | |
93 | ||
94 | static void destroy_rseq_key(void *key) | |
95 | { | |
96 | if (rseq_unregister_current_thread()) | |
97 | abort(); | |
98 | } | |
99 | ||
38bfb073 | 100 | int rseq_register_current_thread(void) |
b76e5200 | 101 | { |
26cc635c MD |
102 | sigset_t oldset; |
103 | int rc, ret = 0; | |
b76e5200 | 104 | |
26cc635c MD |
105 | signal_off_save(&oldset); |
106 | if (caa_likely(!rseq_registered)) { | |
107 | rc = sys_rseq(&__rseq_abi, 0); | |
108 | if (rc) { | |
109 | fprintf(stderr, "Error: sys_rseq(...) failed(%d): %s\n", | |
110 | errno, strerror(errno)); | |
111 | __rseq_abi.u.e.cpu_id = -2; | |
112 | ret = -1; | |
113 | goto end; | |
114 | } | |
115 | rseq_registered = 1; | |
116 | assert(rseq_current_cpu_raw() >= 0); | |
117 | /* | |
118 | * Register destroy notifier. Pointer needs to | |
119 | * be non-NULL. | |
120 | */ | |
121 | if (pthread_setspecific(rseq_key, (void *)0x1)) | |
122 | abort(); | |
b76e5200 | 123 | } |
26cc635c MD |
124 | end: |
125 | signal_restore(oldset); | |
126 | return ret; | |
b76e5200 MD |
127 | } |
128 | ||
26cc635c | 129 | void rseq_init(void) |
b76e5200 | 130 | { |
26cc635c | 131 | int ret; |
b76e5200 | 132 | |
26cc635c MD |
133 | ret = pthread_key_create(&rseq_key, destroy_rseq_key); |
134 | if (ret) { | |
135 | errno = -ret; | |
136 | perror("pthread_key_create"); | |
137 | abort(); | |
138 | } | |
139 | } | |
140 | ||
141 | void rseq_destroy(void) | |
142 | { | |
143 | int ret; | |
144 | ||
145 | ret = pthread_key_delete(rseq_key); | |
146 | if (ret) { | |
147 | errno = -ret; | |
148 | perror("pthread_key_delete"); | |
149 | abort(); | |
b76e5200 | 150 | } |
b76e5200 | 151 | } |