1 /* 2 * Copyright (c) 2005, David Xu <davidxu@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 */ 28 29 #include "namespace.h" 30 #include <sys/param.h> 31 #include <sys/types.h> 32 #include <sys/signalvar.h> 33 #include <signal.h> 34 #include <errno.h> 35 #include <fcntl.h> 36 #include <unistd.h> 37 #include <string.h> 38 #include <pthread.h> 39 #include "un-namespace.h" 40 41 #include "thr_private.h" 42 43 /* #define DEBUG_SIGNAL */ 44 #ifdef DEBUG_SIGNAL 45 #define DBG_MSG stdout_debug 46 #else 47 #define DBG_MSG(x...) 48 #endif 49 50 extern int __pause(void); 51 int ___pause(void); 52 int _raise(int); 53 int __sigtimedwait(const sigset_t *set, siginfo_t *info, 54 const struct timespec * timeout); 55 int _sigtimedwait(const sigset_t *set, siginfo_t *info, 56 const struct timespec * timeout); 57 int __sigwaitinfo(const sigset_t *set, siginfo_t *info); 58 int _sigwaitinfo(const sigset_t *set, siginfo_t *info); 59 int __sigwait(const sigset_t *set, int *sig); 60 int _sigwait(const sigset_t *set, int *sig); 61 int __sigsuspend(const sigset_t *sigmask); 62 63 64 static void 65 sigcancel_handler(int sig __unused, 66 siginfo_t *info __unused, ucontext_t *ucp __unused) 67 { 68 struct pthread *curthread = _get_curthread(); 69 70 curthread->in_sigcancel_handler++; 71 _thr_ast(curthread); 72 curthread->in_sigcancel_handler--; 73 } 74 75 void 76 _thr_ast(struct pthread *curthread) 77 { 78 79 if (THR_IN_CRITICAL(curthread)) 80 return; 81 82 if (curthread->cancel_pending && curthread->cancel_enable 83 && !curthread->cancelling) { 84 if (curthread->cancel_async) { 85 /* 86 * asynchronous cancellation mode, act upon 87 * immediately. 88 */ 89 _pthread_exit(PTHREAD_CANCELED); 90 } else { 91 /* 92 * Otherwise, we are in defer mode, and we are at 93 * cancel point, tell kernel to not block the current 94 * thread on next cancelable system call. 95 * 96 * There are two cases we should call thr_wake() to 97 * turn on TDP_WAKEUP in kernel: 98 * 1) we are going to call a cancelable system call, 99 * non-zero cancel_point means we are already in 100 * cancelable state, next system call is cancelable. 101 * 2) because _thr_ast() may be called by 102 * THR_CRITICAL_LEAVE() which is used by rtld rwlock 103 * and any libthr internal locks, when rtld rwlock 104 * is used, it is mostly caused my an unresolved PLT. 105 * those routines may clear the TDP_WAKEUP flag by 106 * invoking some system calls, in those cases, we 107 * also should reenable the flag. 108 */ 109 if (curthread->cancel_point) { 110 if (curthread->cancel_defer) 111 thr_wake(curthread->tid); 112 else 113 _pthread_exit(PTHREAD_CANCELED); 114 } 115 } 116 } 117 118 if (__predict_false((curthread->flags & 119 (THR_FLAGS_NEED_SUSPEND | THR_FLAGS_SUSPENDED)) 120 == THR_FLAGS_NEED_SUSPEND)) 121 _thr_suspend_check(curthread); 122 } 123 124 void 125 _thr_suspend_check(struct pthread *curthread) 126 { 127 uint32_t cycle; 128 int err; 129 130 if (curthread->force_exit) 131 return; 132 133 err = errno; 134 /* 135 * Blocks SIGCANCEL which other threads must send. 136 */ 137 _thr_signal_block(curthread); 138 139 /* 140 * Increase critical_count, here we don't use THR_LOCK/UNLOCK 141 * because we are leaf code, we don't want to recursively call 142 * ourself. 143 */ 144 curthread->critical_count++; 145 THR_UMUTEX_LOCK(curthread, &(curthread)->lock); 146 while ((curthread->flags & (THR_FLAGS_NEED_SUSPEND | 147 THR_FLAGS_SUSPENDED)) == THR_FLAGS_NEED_SUSPEND) { 148 curthread->cycle++; 149 cycle = curthread->cycle; 150 151 /* Wake the thread suspending us. */ 152 _thr_umtx_wake(&curthread->cycle, INT_MAX, 0); 153 154 /* 155 * if we are from pthread_exit, we don't want to 156 * suspend, just go and die. 157 */ 158 if (curthread->state == PS_DEAD) 159 break; 160 curthread->flags |= THR_FLAGS_SUSPENDED; 161 THR_UMUTEX_UNLOCK(curthread, &(curthread)->lock); 162 _thr_umtx_wait_uint(&curthread->cycle, cycle, NULL, 0); 163 THR_UMUTEX_LOCK(curthread, &(curthread)->lock); 164 curthread->flags &= ~THR_FLAGS_SUSPENDED; 165 } 166 THR_UMUTEX_UNLOCK(curthread, &(curthread)->lock); 167 curthread->critical_count--; 168 169 /* 170 * Unblocks SIGCANCEL, it is possible a new SIGCANCEL is ready and 171 * a new signal frame will nest us, this seems a problem because 172 * stack will grow and overflow, but because kernel will automatically 173 * mask the SIGCANCEL when delivering the signal, so we at most only 174 * have one nesting signal frame, this should be fine. 175 */ 176 _thr_signal_unblock(curthread); 177 errno = err; 178 } 179 180 void 181 _thr_signal_init(void) 182 { 183 struct sigaction act; 184 185 /* Install cancel handler. */ 186 SIGEMPTYSET(act.sa_mask); 187 act.sa_flags = SA_SIGINFO | SA_RESTART; 188 act.sa_sigaction = (__siginfohandler_t *)&sigcancel_handler; 189 __sys_sigaction(SIGCANCEL, &act, NULL); 190 } 191 192 void 193 _thr_signal_deinit(void) 194 { 195 } 196 197 __weak_reference(___pause, pause); 198 199 int 200 ___pause(void) 201 { 202 struct pthread *curthread = _get_curthread(); 203 int ret; 204 205 _thr_cancel_enter(curthread); 206 ret = __pause(); 207 _thr_cancel_leave(curthread); 208 209 return ret; 210 } 211 212 __weak_reference(_raise, raise); 213 214 int 215 _raise(int sig) 216 { 217 int ret; 218 219 if (!_thr_isthreaded()) 220 ret = kill(getpid(), sig); 221 else 222 ret = _thr_send_sig(_get_curthread(), sig); 223 return (ret); 224 } 225 226 __weak_reference(_sigaction, sigaction); 227 228 int 229 _sigaction(int sig, const struct sigaction * act, struct sigaction * oact) 230 { 231 /* Check if the signal number is out of range: */ 232 if (!_SIG_VALID(sig) || sig == SIGCANCEL) { 233 /* Return an invalid argument: */ 234 errno = EINVAL; 235 return (-1); 236 } 237 238 return __sys_sigaction(sig, act, oact); 239 } 240 241 __weak_reference(_sigprocmask, sigprocmask); 242 243 int 244 _sigprocmask(int how, const sigset_t *set, sigset_t *oset) 245 { 246 const sigset_t *p = set; 247 sigset_t newset; 248 249 if (how != SIG_UNBLOCK) { 250 if (set != NULL) { 251 newset = *set; 252 SIGDELSET(newset, SIGCANCEL); 253 p = &newset; 254 } 255 } 256 return (__sys_sigprocmask(how, p, oset)); 257 } 258 259 __weak_reference(_pthread_sigmask, pthread_sigmask); 260 261 int 262 _pthread_sigmask(int how, const sigset_t *set, sigset_t *oset) 263 { 264 if (_sigprocmask(how, set, oset)) 265 return (errno); 266 return (0); 267 } 268 269 __weak_reference(__sigsuspend, sigsuspend); 270 271 static const sigset_t * 272 thr_remove_thr_signals(const sigset_t *set, sigset_t *newset) 273 { 274 const sigset_t *pset; 275 276 if (SIGISMEMBER(*set, SIGCANCEL)) { 277 *newset = *set; 278 SIGDELSET(*newset, SIGCANCEL); 279 pset = newset; 280 } else 281 pset = set; 282 return (pset); 283 } 284 285 int 286 _sigsuspend(const sigset_t * set) 287 { 288 sigset_t newset; 289 290 return (__sys_sigsuspend(thr_remove_thr_signals(set, &newset))); 291 } 292 293 int 294 __sigsuspend(const sigset_t * set) 295 { 296 struct pthread *curthread = _get_curthread(); 297 sigset_t newset; 298 int ret; 299 300 _thr_cancel_enter(curthread); 301 ret = __sys_sigsuspend(thr_remove_thr_signals(set, &newset)); 302 _thr_cancel_leave(curthread); 303 304 return (ret); 305 } 306 307 __weak_reference(__sigwait, sigwait); 308 __weak_reference(__sigtimedwait, sigtimedwait); 309 __weak_reference(__sigwaitinfo, sigwaitinfo); 310 311 int 312 _sigtimedwait(const sigset_t *set, siginfo_t *info, 313 const struct timespec * timeout) 314 { 315 sigset_t newset; 316 317 return (__sys_sigtimedwait(thr_remove_thr_signals(set, &newset), info, 318 timeout)); 319 } 320 321 /* 322 * Cancellation behavior: 323 * Thread may be canceled at start, if thread got signal, 324 * it is not canceled. 325 */ 326 int 327 __sigtimedwait(const sigset_t *set, siginfo_t *info, 328 const struct timespec * timeout) 329 { 330 struct pthread *curthread = _get_curthread(); 331 sigset_t newset; 332 int ret; 333 334 _thr_cancel_enter_defer(curthread, 1); 335 ret = __sys_sigtimedwait(thr_remove_thr_signals(set, &newset), info, 336 timeout); 337 _thr_cancel_leave_defer(curthread, (ret == -1)); 338 return (ret); 339 } 340 341 int 342 _sigwaitinfo(const sigset_t *set, siginfo_t *info) 343 { 344 sigset_t newset; 345 346 return (__sys_sigwaitinfo(thr_remove_thr_signals(set, &newset), info)); 347 } 348 349 /* 350 * Cancellation behavior: 351 * Thread may be canceled at start, if thread got signal, 352 * it is not canceled. 353 */ 354 int 355 __sigwaitinfo(const sigset_t *set, siginfo_t *info) 356 { 357 struct pthread *curthread = _get_curthread(); 358 sigset_t newset; 359 int ret; 360 361 _thr_cancel_enter_defer(curthread, 1); 362 ret = __sys_sigwaitinfo(thr_remove_thr_signals(set, &newset), info); 363 _thr_cancel_leave_defer(curthread, ret == -1); 364 return (ret); 365 } 366 367 int 368 _sigwait(const sigset_t *set, int *sig) 369 { 370 sigset_t newset; 371 372 return (__sys_sigwait(thr_remove_thr_signals(set, &newset), sig)); 373 } 374 375 /* 376 * Cancellation behavior: 377 * Thread may be canceled at start, if thread got signal, 378 * it is not canceled. 379 */ 380 int 381 __sigwait(const sigset_t *set, int *sig) 382 { 383 struct pthread *curthread = _get_curthread(); 384 sigset_t newset; 385 int ret; 386 387 _thr_cancel_enter_defer(curthread, 1); 388 ret = __sys_sigwait(thr_remove_thr_signals(set, &newset), sig); 389 _thr_cancel_leave_defer(curthread, (ret != 0)); 390 return (ret); 391 } 392