xref: /freebsd/lib/libthr/thread/thr_sig.c (revision 8aac90f18aef7c9eea906c3ff9a001ca7b94f375)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2005, David Xu <davidxu@freebsd.org>
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice unmodified, this list of conditions, and the following
12  *    disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 #include "namespace.h"
30 #include <sys/param.h>
31 #include <sys/auxv.h>
32 #include <sys/elf.h>
33 #include <sys/signalvar.h>
34 #include <sys/syscall.h>
35 #include <signal.h>
36 #include <errno.h>
37 #include <stdlib.h>
38 #include <string.h>
39 #include <pthread.h>
40 #include "un-namespace.h"
41 #include "libc_private.h"
42 
43 #include "libc_private.h"
44 #include "thr_private.h"
45 
46 /* #define DEBUG_SIGNAL */
47 #ifdef DEBUG_SIGNAL
48 #define DBG_MSG		stdout_debug
49 #else
50 #define DBG_MSG(x...)
51 #endif
52 
53 struct usigaction {
54 	struct sigaction sigact;
55 	struct urwlock   lock;
56 };
57 
58 static struct usigaction _thr_sigact[_SIG_MAXSIG];
59 
60 static inline struct usigaction *
61 __libc_sigaction_slot(int signo)
62 {
63 
64 	return (&_thr_sigact[signo - 1]);
65 }
66 
67 static void thr_sighandler(int, siginfo_t *, void *);
68 static void handle_signal(struct sigaction *, int, siginfo_t *, ucontext_t *);
69 static void check_deferred_signal(struct pthread *);
70 static void check_suspend(struct pthread *);
71 static void check_cancel(struct pthread *curthread, ucontext_t *ucp);
72 
73 int	_sigtimedwait(const sigset_t *set, siginfo_t *info,
74 	const struct timespec * timeout);
75 int	_sigwaitinfo(const sigset_t *set, siginfo_t *info);
76 int	_sigwait(const sigset_t *set, int *sig);
77 int	_setcontext(const ucontext_t *);
78 int	_swapcontext(ucontext_t *, const ucontext_t *);
79 
80 static const sigset_t _thr_deferset={{
81 	0xffffffff & ~(_SIG_BIT(SIGBUS)|_SIG_BIT(SIGILL)|_SIG_BIT(SIGFPE)|
82 	_SIG_BIT(SIGSEGV)|_SIG_BIT(SIGTRAP)|_SIG_BIT(SIGSYS)),
83 	0xffffffff,
84 	0xffffffff,
85 	0xffffffff}};
86 
87 static const sigset_t _thr_maskset={{
88 	0xffffffff,
89 	0xffffffff,
90 	0xffffffff,
91 	0xffffffff}};
92 
93 static void
94 thr_signal_block_slow(struct pthread *curthread)
95 {
96 	if (curthread->sigblock > 0) {
97 		curthread->sigblock++;
98 		return;
99 	}
100 	__sys_sigprocmask(SIG_BLOCK, &_thr_maskset, &curthread->sigmask);
101 	curthread->sigblock++;
102 }
103 
104 static void
105 thr_signal_unblock_slow(struct pthread *curthread)
106 {
107 	if (--curthread->sigblock == 0)
108 		__sys_sigprocmask(SIG_SETMASK, &curthread->sigmask, NULL);
109 }
110 
111 static void
112 thr_signal_block_fast(struct pthread *curthread)
113 {
114 	atomic_add_32(&curthread->fsigblock, SIGFASTBLOCK_INC);
115 }
116 
117 static void
118 thr_signal_unblock_fast(struct pthread *curthread)
119 {
120 	uint32_t oldval;
121 
122 	oldval = atomic_fetchadd_32(&curthread->fsigblock, -SIGFASTBLOCK_INC);
123 	if (oldval == (SIGFASTBLOCK_PEND | SIGFASTBLOCK_INC))
124 		__sys_sigfastblock(SIGFASTBLOCK_UNBLOCK, NULL);
125 }
126 
127 static bool fast_sigblock;
128 
129 void
130 _thr_signal_block(struct pthread *curthread)
131 {
132 	if (fast_sigblock)
133 		thr_signal_block_fast(curthread);
134 	else
135 		thr_signal_block_slow(curthread);
136 }
137 
138 void
139 _thr_signal_unblock(struct pthread *curthread)
140 {
141 	if (fast_sigblock)
142 		thr_signal_unblock_fast(curthread);
143 	else
144 		thr_signal_unblock_slow(curthread);
145 }
146 
147 void
148 _thr_signal_block_check_fast(void)
149 {
150 	int bsdflags, error;
151 
152 	error = elf_aux_info(AT_BSDFLAGS, &bsdflags, sizeof(bsdflags));
153 	if (error != 0)
154 		return;
155 	fast_sigblock = (bsdflags & ELF_BSDF_SIGFASTBLK) != 0;
156 }
157 
158 void
159 _thr_signal_block_setup(struct pthread *curthread)
160 {
161 	if (!fast_sigblock)
162 		return;
163 	__sys_sigfastblock(SIGFASTBLOCK_SETPTR, &curthread->fsigblock);
164 }
165 
166 int
167 _thr_send_sig(struct pthread *thread, int sig)
168 {
169 	return thr_kill(thread->tid, sig);
170 }
171 
172 static inline void
173 remove_thr_signals(sigset_t *set)
174 {
175 	if (SIGISMEMBER(*set, SIGCANCEL))
176 		SIGDELSET(*set, SIGCANCEL);
177 }
178 
179 static const sigset_t *
180 thr_remove_thr_signals(const sigset_t *set, sigset_t *newset)
181 {
182 	*newset = *set;
183 	remove_thr_signals(newset);
184 	return (newset);
185 }
186 
187 static void
188 sigcancel_handler(int sig __unused,
189 	siginfo_t *info __unused, ucontext_t *ucp)
190 {
191 	struct pthread *curthread = _get_curthread();
192 	int err;
193 
194 	if (THR_IN_CRITICAL(curthread))
195 		return;
196 	err = errno;
197 	check_suspend(curthread);
198 	check_cancel(curthread, ucp);
199 	errno = err;
200 }
201 
202 typedef void (*ohandler)(int sig, int code, struct sigcontext *scp,
203     char *addr, __sighandler_t *catcher);
204 
205 /*
206  * The signal handler wrapper is entered with all signal masked.
207  */
208 static void
209 thr_sighandler(int sig, siginfo_t *info, void *_ucp)
210 {
211 	struct pthread *curthread;
212 	ucontext_t *ucp;
213 	struct sigaction act;
214 	struct usigaction *usa;
215 	int err;
216 
217 	err = errno;
218 	curthread = _get_curthread();
219 	ucp = _ucp;
220 	usa = __libc_sigaction_slot(sig);
221 	_thr_rwl_rdlock(&usa->lock);
222 	act = usa->sigact;
223 	_thr_rwl_unlock(&usa->lock);
224 	errno = err;
225 	curthread->deferred_run = 0;
226 
227 	/*
228 	 * if a thread is in critical region, for example it holds low level locks,
229 	 * try to defer the signal processing, however if the signal is synchronous
230 	 * signal, it means a bad thing has happened, this is a programming error,
231 	 * resuming fault point can not help anything (normally causes deadloop),
232 	 * so here we let user code handle it immediately.
233 	 */
234 	if (THR_IN_CRITICAL(curthread) && SIGISMEMBER(_thr_deferset, sig)) {
235 		memcpy(&curthread->deferred_sigact, &act, sizeof(struct sigaction));
236 		memcpy(&curthread->deferred_siginfo, info, sizeof(siginfo_t));
237 		curthread->deferred_sigmask = ucp->uc_sigmask;
238 		/* mask all signals, we will restore it later. */
239 		ucp->uc_sigmask = _thr_deferset;
240 		return;
241 	}
242 
243 	handle_signal(&act, sig, info, ucp);
244 }
245 
246 static void
247 handle_signal(struct sigaction *actp, int sig, siginfo_t *info, ucontext_t *ucp)
248 {
249 	struct pthread *curthread = _get_curthread();
250 	ucontext_t uc2;
251 	__siginfohandler_t *sigfunc;
252 	int cancel_point;
253 	int cancel_async;
254 	int cancel_enable;
255 	int in_sigsuspend;
256 	int err;
257 
258 	/* add previous level mask */
259 	SIGSETOR(actp->sa_mask, ucp->uc_sigmask);
260 
261 	/* add this signal's mask */
262 	if (!(actp->sa_flags & SA_NODEFER))
263 		SIGADDSET(actp->sa_mask, sig);
264 
265 	in_sigsuspend = curthread->in_sigsuspend;
266 	curthread->in_sigsuspend = 0;
267 
268 	/*
269 	 * If thread is in deferred cancellation mode, disable cancellation
270 	 * in signal handler.
271 	 * If user signal handler calls a cancellation point function, e.g,
272 	 * it calls write() to write data to file, because write() is a
273 	 * cancellation point, the thread is immediately cancelled if
274 	 * cancellation is pending, to avoid this problem while thread is in
275 	 * deferring mode, cancellation is temporarily disabled.
276 	 */
277 	cancel_point = curthread->cancel_point;
278 	cancel_async = curthread->cancel_async;
279 	cancel_enable = curthread->cancel_enable;
280 	curthread->cancel_point = 0;
281 	if (!cancel_async)
282 		curthread->cancel_enable = 0;
283 
284 	/* restore correct mask before calling user handler */
285 	__sys_sigprocmask(SIG_SETMASK, &actp->sa_mask, NULL);
286 
287 	sigfunc = actp->sa_sigaction;
288 
289 	/*
290 	 * We have already reset cancellation point flags, so if user's code
291 	 * longjmp()s out of its signal handler, wish its jmpbuf was set
292 	 * outside of a cancellation point, in most cases, this would be
293 	 * true.  However, there is no way to save cancel_enable in jmpbuf,
294 	 * so after setjmps() returns once more, the user code may need to
295 	 * re-set cancel_enable flag by calling pthread_setcancelstate().
296 	 */
297 	if ((actp->sa_flags & SA_SIGINFO) != 0) {
298 		sigfunc(sig, info, ucp);
299 	} else {
300 		((ohandler)sigfunc)(sig, info->si_code,
301 		    (struct sigcontext *)ucp, info->si_addr,
302 		    (__sighandler_t *)sigfunc);
303 	}
304 	err = errno;
305 
306 	curthread->in_sigsuspend = in_sigsuspend;
307 	curthread->cancel_point = cancel_point;
308 	curthread->cancel_enable = cancel_enable;
309 
310 	memcpy(&uc2, ucp, sizeof(uc2));
311 	SIGDELSET(uc2.uc_sigmask, SIGCANCEL);
312 
313 	/* reschedule cancellation */
314 	check_cancel(curthread, &uc2);
315 	errno = err;
316 	syscall(SYS_sigreturn, &uc2);
317 }
318 
319 void
320 _thr_ast(struct pthread *curthread)
321 {
322 
323 	if (!THR_IN_CRITICAL(curthread)) {
324 		check_deferred_signal(curthread);
325 		check_suspend(curthread);
326 		check_cancel(curthread, NULL);
327 	}
328 }
329 
330 /* reschedule cancellation */
331 static void
332 check_cancel(struct pthread *curthread, ucontext_t *ucp)
333 {
334 
335 	if (__predict_true(!curthread->cancel_pending ||
336 	    !curthread->cancel_enable || curthread->no_cancel))
337 		return;
338 
339 	/*
340  	 * Otherwise, we are in defer mode, and we are at
341 	 * cancel point, tell kernel to not block the current
342 	 * thread on next cancelable system call.
343 	 *
344 	 * There are three cases we should call thr_wake() to
345 	 * turn on TDP_WAKEUP or send SIGCANCEL in kernel:
346 	 * 1) we are going to call a cancelable system call,
347 	 *    non-zero cancel_point means we are already in
348 	 *    cancelable state, next system call is cancelable.
349 	 * 2) because _thr_ast() may be called by
350 	 *    THR_CRITICAL_LEAVE() which is used by rtld rwlock
351 	 *    and any libthr internal locks, when rtld rwlock
352 	 *    is used, it is mostly caused by an unresolved PLT.
353 	 *    Those routines may clear the TDP_WAKEUP flag by
354 	 *    invoking some system calls, in those cases, we
355 	 *    also should reenable the flag.
356 	 * 3) thread is in sigsuspend(), and the syscall insists
357 	 *    on getting a signal before it agrees to return.
358  	 */
359 	if (curthread->cancel_point) {
360 		if (curthread->in_sigsuspend && ucp) {
361 			SIGADDSET(ucp->uc_sigmask, SIGCANCEL);
362 			curthread->unblock_sigcancel = 1;
363 			_thr_send_sig(curthread, SIGCANCEL);
364 		} else
365 			thr_wake(curthread->tid);
366 	} else if (curthread->cancel_async) {
367 		/*
368 		 * asynchronous cancellation mode, act upon
369 		 * immediately.
370 		 */
371 		_pthread_exit_mask(PTHREAD_CANCELED,
372 		    ucp? &ucp->uc_sigmask : NULL);
373 	}
374 }
375 
376 static void
377 check_deferred_signal(struct pthread *curthread)
378 {
379 	ucontext_t *uc;
380 	struct sigaction act;
381 	siginfo_t info;
382 	int uc_len;
383 
384 	if (__predict_true(curthread->deferred_siginfo.si_signo == 0 ||
385 	    curthread->deferred_run))
386 		return;
387 
388 	curthread->deferred_run = 1;
389 	uc_len = __getcontextx_size();
390 	uc = alloca(uc_len);
391 	getcontext(uc);
392 	if (curthread->deferred_siginfo.si_signo == 0) {
393 		curthread->deferred_run = 0;
394 		return;
395 	}
396 	__fillcontextx2((char *)uc);
397 	act = curthread->deferred_sigact;
398 	uc->uc_sigmask = curthread->deferred_sigmask;
399 	memcpy(&info, &curthread->deferred_siginfo, sizeof(siginfo_t));
400 	/* remove signal */
401 	curthread->deferred_siginfo.si_signo = 0;
402 	handle_signal(&act, info.si_signo, &info, uc);
403 }
404 
405 static void
406 check_suspend(struct pthread *curthread)
407 {
408 	uint32_t cycle;
409 
410 	if (__predict_true((curthread->flags &
411 		(THR_FLAGS_NEED_SUSPEND | THR_FLAGS_SUSPENDED))
412 		!= THR_FLAGS_NEED_SUSPEND))
413 		return;
414 	if (curthread == _single_thread)
415 		return;
416 	if (curthread->force_exit)
417 		return;
418 
419 	/*
420 	 * Blocks SIGCANCEL which other threads must send.
421 	 */
422 	_thr_signal_block(curthread);
423 
424 	/*
425 	 * Increase critical_count, here we don't use THR_LOCK/UNLOCK
426 	 * because we are leaf code, we don't want to recursively call
427 	 * ourself.
428 	 */
429 	curthread->critical_count++;
430 	THR_UMUTEX_LOCK(curthread, &(curthread)->lock);
431 	while ((curthread->flags & THR_FLAGS_NEED_SUSPEND) != 0) {
432 		curthread->cycle++;
433 		cycle = curthread->cycle;
434 
435 		/* Wake the thread suspending us. */
436 		_thr_umtx_wake(&curthread->cycle, INT_MAX, 0);
437 
438 		/*
439 		 * if we are from pthread_exit, we don't want to
440 		 * suspend, just go and die.
441 		 */
442 		if (curthread->state == PS_DEAD)
443 			break;
444 		curthread->flags |= THR_FLAGS_SUSPENDED;
445 		THR_UMUTEX_UNLOCK(curthread, &(curthread)->lock);
446 		_thr_umtx_wait_uint(&curthread->cycle, cycle, NULL, 0);
447 		THR_UMUTEX_LOCK(curthread, &(curthread)->lock);
448 	}
449 	THR_UMUTEX_UNLOCK(curthread, &(curthread)->lock);
450 	curthread->critical_count--;
451 
452 	_thr_signal_unblock(curthread);
453 }
454 
455 void
456 _thr_signal_init(int dlopened)
457 {
458 	struct sigaction act, nact, oact;
459 	struct usigaction *usa;
460 	sigset_t oldset;
461 	int sig, error;
462 
463 	if (dlopened) {
464 		__sys_sigprocmask(SIG_SETMASK, &_thr_maskset, &oldset);
465 		for (sig = 1; sig <= _SIG_MAXSIG; sig++) {
466 			if (sig == SIGCANCEL)
467 				continue;
468 			error = __sys_sigaction(sig, NULL, &oact);
469 			if (error == -1 || oact.sa_handler == SIG_DFL ||
470 			    oact.sa_handler == SIG_IGN)
471 				continue;
472 			usa = __libc_sigaction_slot(sig);
473 			usa->sigact = oact;
474 			nact = oact;
475 			remove_thr_signals(&usa->sigact.sa_mask);
476 			nact.sa_flags &= ~SA_NODEFER;
477 			nact.sa_flags |= SA_SIGINFO;
478 			nact.sa_sigaction = thr_sighandler;
479 			nact.sa_mask = _thr_maskset;
480 			(void)__sys_sigaction(sig, &nact, NULL);
481 		}
482 		__sys_sigprocmask(SIG_SETMASK, &oldset, NULL);
483 	}
484 
485 	/* Install SIGCANCEL handler. */
486 	SIGFILLSET(act.sa_mask);
487 	act.sa_flags = SA_SIGINFO;
488 	act.sa_sigaction = (__siginfohandler_t *)&sigcancel_handler;
489 	__sys_sigaction(SIGCANCEL, &act, NULL);
490 
491 	/* Unblock SIGCANCEL */
492 	SIGEMPTYSET(act.sa_mask);
493 	SIGADDSET(act.sa_mask, SIGCANCEL);
494 	__sys_sigprocmask(SIG_UNBLOCK, &act.sa_mask, NULL);
495 }
496 
497 void
498 _thr_sigact_unload(struct dl_phdr_info *phdr_info __unused)
499 {
500 #if 0
501 	struct pthread *curthread = _get_curthread();
502 	struct urwlock *rwlp;
503 	struct sigaction *actp;
504 	struct usigaction *usa;
505 	struct sigaction kact;
506 	void (*handler)(int);
507 	int sig;
508 
509 	_thr_signal_block(curthread);
510 	for (sig = 1; sig <= _SIG_MAXSIG; sig++) {
511 		usa = __libc_sigaction_slot(sig);
512 		actp = &usa->sigact;
513 retry:
514 		handler = actp->sa_handler;
515 		if (handler != SIG_DFL && handler != SIG_IGN &&
516 		    __elf_phdr_match_addr(phdr_info, handler)) {
517 			rwlp = &usa->lock;
518 			_thr_rwl_wrlock(rwlp);
519 			if (handler != actp->sa_handler) {
520 				_thr_rwl_unlock(rwlp);
521 				goto retry;
522 			}
523 			actp->sa_handler = SIG_DFL;
524 			actp->sa_flags = SA_SIGINFO;
525 			SIGEMPTYSET(actp->sa_mask);
526 			if (__sys_sigaction(sig, NULL, &kact) == 0 &&
527 				kact.sa_handler != SIG_DFL &&
528 				kact.sa_handler != SIG_IGN)
529 				__sys_sigaction(sig, actp, NULL);
530 			_thr_rwl_unlock(rwlp);
531 		}
532 	}
533 	_thr_signal_unblock(curthread);
534 #endif
535 }
536 
537 void
538 _thr_signal_prefork(void)
539 {
540 	int i;
541 
542 	for (i = 1; i <= _SIG_MAXSIG; ++i)
543 		_thr_rwl_rdlock(&__libc_sigaction_slot(i)->lock);
544 }
545 
546 void
547 _thr_signal_postfork(void)
548 {
549 	int i;
550 
551 	for (i = 1; i <= _SIG_MAXSIG; ++i)
552 		_thr_rwl_unlock(&__libc_sigaction_slot(i)->lock);
553 }
554 
555 void
556 _thr_signal_postfork_child(void)
557 {
558 	int i;
559 
560 	for (i = 1; i <= _SIG_MAXSIG; ++i) {
561 		bzero(&__libc_sigaction_slot(i) -> lock,
562 		    sizeof(struct urwlock));
563 	}
564 }
565 
566 void
567 _thr_signal_deinit(void)
568 {
569 }
570 
571 int
572 __thr_sigaction(int sig, const struct sigaction *act, struct sigaction *oact)
573 {
574 	struct sigaction newact, oldact, oldact2;
575 	sigset_t oldset;
576 	struct usigaction *usa;
577 	int ret, err;
578 
579 	if (!_SIG_VALID(sig) || sig == SIGCANCEL) {
580 		errno = EINVAL;
581 		return (-1);
582 	}
583 
584 	ret = 0;
585 	err = 0;
586 	usa = __libc_sigaction_slot(sig);
587 
588 	__sys_sigprocmask(SIG_SETMASK, &_thr_maskset, &oldset);
589 	_thr_rwl_wrlock(&usa->lock);
590 
591 	if (act != NULL) {
592 		oldact2 = usa->sigact;
593 		newact = *act;
594 
595  		/*
596 		 * if a new sig handler is SIG_DFL or SIG_IGN,
597 		 * don't remove old handler from __libc_sigact[],
598 		 * so deferred signals still can use the handlers,
599 		 * multiple threads invoking sigaction itself is
600 		 * a race condition, so it is not a problem.
601 		 */
602 		if (newact.sa_handler != SIG_DFL &&
603 		    newact.sa_handler != SIG_IGN) {
604 			usa->sigact = newact;
605 			remove_thr_signals(&usa->sigact.sa_mask);
606 			newact.sa_flags &= ~SA_NODEFER;
607 			newact.sa_flags |= SA_SIGINFO;
608 			newact.sa_sigaction = thr_sighandler;
609 			newact.sa_mask = _thr_maskset; /* mask all signals */
610 		}
611 		ret = __sys_sigaction(sig, &newact, &oldact);
612 		if (ret == -1) {
613 			err = errno;
614 			usa->sigact = oldact2;
615 		}
616 	} else if (oact != NULL) {
617 		ret = __sys_sigaction(sig, NULL, &oldact);
618 		err = errno;
619 	}
620 
621 	if (oldact.sa_handler != SIG_DFL && oldact.sa_handler != SIG_IGN) {
622 		if (act != NULL)
623 			oldact = oldact2;
624 		else if (oact != NULL)
625 			oldact = usa->sigact;
626 	}
627 
628 	_thr_rwl_unlock(&usa->lock);
629 	__sys_sigprocmask(SIG_SETMASK, &oldset, NULL);
630 
631 	if (ret == 0) {
632 		if (oact != NULL)
633 			*oact = oldact;
634 	} else {
635 		errno = err;
636 	}
637 	return (ret);
638 }
639 
640 int
641 __thr_sigprocmask(int how, const sigset_t *set, sigset_t *oset)
642 {
643 	const sigset_t *p = set;
644 	sigset_t newset;
645 
646 	if (how != SIG_UNBLOCK) {
647 		if (set != NULL) {
648 			newset = *set;
649 			SIGDELSET(newset, SIGCANCEL);
650 			p = &newset;
651 		}
652 	}
653 	return (__sys_sigprocmask(how, p, oset));
654 }
655 
656 __weak_reference(_thr_sigmask, pthread_sigmask);
657 __weak_reference(_thr_sigmask, _pthread_sigmask);
658 
659 int
660 _thr_sigmask(int how, const sigset_t *set, sigset_t *oset)
661 {
662 
663 	if (__thr_sigprocmask(how, set, oset))
664 		return (errno);
665 	return (0);
666 }
667 
668 int
669 _sigsuspend(const sigset_t * set)
670 {
671 	sigset_t newset;
672 
673 	return (__sys_sigsuspend(thr_remove_thr_signals(set, &newset)));
674 }
675 
676 int
677 __thr_sigsuspend(const sigset_t * set)
678 {
679 	struct pthread *curthread;
680 	sigset_t newset;
681 	int ret, old;
682 
683 	curthread = _get_curthread();
684 
685 	old = curthread->in_sigsuspend;
686 	curthread->in_sigsuspend = 1;
687 	_thr_cancel_enter(curthread);
688 	ret = __sys_sigsuspend(thr_remove_thr_signals(set, &newset));
689 	_thr_cancel_leave(curthread, 1);
690 	curthread->in_sigsuspend = old;
691 	if (curthread->unblock_sigcancel) {
692 		curthread->unblock_sigcancel = 0;
693 		SIGEMPTYSET(newset);
694 		SIGADDSET(newset, SIGCANCEL);
695 		__sys_sigprocmask(SIG_UNBLOCK, &newset, NULL);
696 	}
697 
698 	return (ret);
699 }
700 
701 int
702 _sigtimedwait(const sigset_t *set, siginfo_t *info,
703 	const struct timespec * timeout)
704 {
705 	sigset_t newset;
706 
707 	return (__sys_sigtimedwait(thr_remove_thr_signals(set, &newset), info,
708 	    timeout));
709 }
710 
711 /*
712  * Cancellation behavior:
713  *   Thread may be canceled at start, if thread got signal,
714  *   it is not canceled.
715  */
716 int
717 __thr_sigtimedwait(const sigset_t *set, siginfo_t *info,
718     const struct timespec * timeout)
719 {
720 	struct pthread	*curthread = _get_curthread();
721 	sigset_t newset;
722 	int ret;
723 
724 	_thr_cancel_enter(curthread);
725 	ret = __sys_sigtimedwait(thr_remove_thr_signals(set, &newset), info,
726 	    timeout);
727 	_thr_cancel_leave(curthread, (ret == -1));
728 	return (ret);
729 }
730 
731 int
732 _sigwaitinfo(const sigset_t *set, siginfo_t *info)
733 {
734 	sigset_t newset;
735 
736 	return (__sys_sigwaitinfo(thr_remove_thr_signals(set, &newset), info));
737 }
738 
739 /*
740  * Cancellation behavior:
741  *   Thread may be canceled at start, if thread got signal,
742  *   it is not canceled.
743  */
744 int
745 __thr_sigwaitinfo(const sigset_t *set, siginfo_t *info)
746 {
747 	struct pthread	*curthread = _get_curthread();
748 	sigset_t newset;
749 	int ret;
750 
751 	_thr_cancel_enter(curthread);
752 	ret = __sys_sigwaitinfo(thr_remove_thr_signals(set, &newset), info);
753 	_thr_cancel_leave(curthread, ret == -1);
754 	return (ret);
755 }
756 
757 int
758 _sigwait(const sigset_t *set, int *sig)
759 {
760 	sigset_t newset;
761 
762 	return (__sys_sigwait(thr_remove_thr_signals(set, &newset), sig));
763 }
764 
765 /*
766  * Cancellation behavior:
767  *   Thread may be canceled at start, if thread got signal,
768  *   it is not canceled.
769  */
770 int
771 __thr_sigwait(const sigset_t *set, int *sig)
772 {
773 	struct pthread	*curthread = _get_curthread();
774 	sigset_t newset;
775 	int ret;
776 
777 	do {
778 		_thr_cancel_enter(curthread);
779 		ret = __sys_sigwait(thr_remove_thr_signals(set, &newset), sig);
780 		_thr_cancel_leave(curthread, (ret != 0));
781 	} while (ret == EINTR);
782 	return (ret);
783 }
784 
785 int
786 __thr_setcontext(const ucontext_t *ucp)
787 {
788 	ucontext_t uc;
789 
790 	if (ucp == NULL) {
791 		errno = EINVAL;
792 		return (-1);
793 	}
794 	if (!SIGISMEMBER(ucp->uc_sigmask, SIGCANCEL))
795 		return (__sys_setcontext(ucp));
796 	(void) memcpy(&uc, ucp, sizeof(uc));
797 	SIGDELSET(uc.uc_sigmask, SIGCANCEL);
798 	return (__sys_setcontext(&uc));
799 }
800 
801 int
802 __thr_swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
803 {
804 	ucontext_t uc;
805 
806 	if (oucp == NULL || ucp == NULL) {
807 		errno = EINVAL;
808 		return (-1);
809 	}
810 	if (SIGISMEMBER(ucp->uc_sigmask, SIGCANCEL)) {
811 		(void) memcpy(&uc, ucp, sizeof(uc));
812 		SIGDELSET(uc.uc_sigmask, SIGCANCEL);
813 		ucp = &uc;
814 	}
815 	return (__sys_swapcontext(oucp, ucp));
816 }
817