2 * Copyright (c) 2005, David Xu <davidxu@freebsd.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice unmodified, this list of conditions, and the following
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.
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.
29 #include "namespace.h"
30 #include <sys/param.h>
31 #include <sys/types.h>
32 #include <sys/signalvar.h>
38 #include "un-namespace.h"
39 #include "libc_private.h"
41 #include "thr_private.h"
43 /* #define DEBUG_SIGNAL */
45 #define DBG_MSG stdout_debug
51 struct sigaction sigact;
55 static struct usigaction _thr_sigact[_SIG_MAXSIG];
57 static void thr_sighandler(int, siginfo_t *, void *);
58 static void handle_signal(struct sigaction *, int, siginfo_t *, ucontext_t *);
59 static void check_deferred_signal(struct pthread *);
60 static void check_suspend(struct pthread *);
61 static void check_cancel(struct pthread *curthread, ucontext_t *ucp);
65 int __sigtimedwait(const sigset_t *set, siginfo_t *info,
66 const struct timespec * timeout);
67 int _sigtimedwait(const sigset_t *set, siginfo_t *info,
68 const struct timespec * timeout);
69 int __sigwaitinfo(const sigset_t *set, siginfo_t *info);
70 int _sigwaitinfo(const sigset_t *set, siginfo_t *info);
71 int ___sigwait(const sigset_t *set, int *sig);
72 int _sigwait(const sigset_t *set, int *sig);
73 int __sigsuspend(const sigset_t *sigmask);
74 int _sigaction(int, const struct sigaction *, struct sigaction *);
75 int _setcontext(const ucontext_t *);
76 int _swapcontext(ucontext_t *, const ucontext_t *);
78 static const sigset_t _thr_deferset={{
79 0xffffffff & ~(_SIG_BIT(SIGBUS)|_SIG_BIT(SIGILL)|_SIG_BIT(SIGFPE)|
80 _SIG_BIT(SIGSEGV)|_SIG_BIT(SIGTRAP)|_SIG_BIT(SIGSYS)),
85 static const sigset_t _thr_maskset={{
92 _thr_signal_block(struct pthread *curthread)
95 if (curthread->sigblock > 0) {
96 curthread->sigblock++;
99 __sys_sigprocmask(SIG_BLOCK, &_thr_maskset, &curthread->sigmask);
100 curthread->sigblock++;
104 _thr_signal_unblock(struct pthread *curthread)
106 if (--curthread->sigblock == 0)
107 __sys_sigprocmask(SIG_SETMASK, &curthread->sigmask, NULL);
111 _thr_send_sig(struct pthread *thread, int sig)
113 return thr_kill(thread->tid, sig);
117 remove_thr_signals(sigset_t *set)
119 if (SIGISMEMBER(*set, SIGCANCEL))
120 SIGDELSET(*set, SIGCANCEL);
123 static const sigset_t *
124 thr_remove_thr_signals(const sigset_t *set, sigset_t *newset)
127 remove_thr_signals(newset);
132 sigcancel_handler(int sig __unused,
133 siginfo_t *info __unused, ucontext_t *ucp)
135 struct pthread *curthread = _get_curthread();
138 if (THR_IN_CRITICAL(curthread))
141 check_suspend(curthread);
142 check_cancel(curthread, ucp);
146 typedef void (*ohandler)(int sig, int code,
147 struct sigcontext *scp, char *addr, __sighandler_t *catcher);
150 * The signal handler wrapper is entered with all signal masked.
153 thr_sighandler(int sig, siginfo_t *info, void *_ucp)
155 struct pthread *curthread = _get_curthread();
156 ucontext_t *ucp = _ucp;
157 struct sigaction act;
161 _thr_rwl_rdlock(&_thr_sigact[sig-1].lock);
162 act = _thr_sigact[sig-1].sigact;
163 _thr_rwl_unlock(&_thr_sigact[sig-1].lock);
165 curthread->deferred_run = 0;
168 * if a thread is in critical region, for example it holds low level locks,
169 * try to defer the signal processing, however if the signal is synchronous
170 * signal, it means a bad thing has happened, this is a programming error,
171 * resuming fault point can not help anything (normally causes deadloop),
172 * so here we let user code handle it immediately.
174 if (THR_IN_CRITICAL(curthread) && SIGISMEMBER(_thr_deferset, sig)) {
175 memcpy(&curthread->deferred_sigact, &act, sizeof(struct sigaction));
176 memcpy(&curthread->deferred_siginfo, info, sizeof(siginfo_t));
177 curthread->deferred_sigmask = ucp->uc_sigmask;
178 /* mask all signals, we will restore it later. */
179 ucp->uc_sigmask = _thr_deferset;
183 handle_signal(&act, sig, info, ucp);
187 handle_signal(struct sigaction *actp, int sig, siginfo_t *info, ucontext_t *ucp)
189 struct pthread *curthread = _get_curthread();
191 __siginfohandler_t *sigfunc;
198 /* add previous level mask */
199 SIGSETOR(actp->sa_mask, ucp->uc_sigmask);
201 /* add this signal's mask */
202 if (!(actp->sa_flags & SA_NODEFER))
203 SIGADDSET(actp->sa_mask, sig);
205 in_sigsuspend = curthread->in_sigsuspend;
206 curthread->in_sigsuspend = 0;
209 * If thread is in deferred cancellation mode, disable cancellation
211 * If user signal handler calls a cancellation point function, e.g,
212 * it calls write() to write data to file, because write() is a
213 * cancellation point, the thread is immediately cancelled if
214 * cancellation is pending, to avoid this problem while thread is in
215 * deferring mode, cancellation is temporarily disabled.
217 cancel_point = curthread->cancel_point;
218 cancel_async = curthread->cancel_async;
219 cancel_enable = curthread->cancel_enable;
220 curthread->cancel_point = 0;
222 curthread->cancel_enable = 0;
224 /* restore correct mask before calling user handler */
225 __sys_sigprocmask(SIG_SETMASK, &actp->sa_mask, NULL);
227 sigfunc = actp->sa_sigaction;
230 * We have already reset cancellation point flags, so if user's code
231 * longjmp()s out of its signal handler, wish its jmpbuf was set
232 * outside of a cancellation point, in most cases, this would be
233 * true. However, there is no way to save cancel_enable in jmpbuf,
234 * so after setjmps() returns once more, the user code may need to
235 * re-set cancel_enable flag by calling pthread_setcancelstate().
237 if ((actp->sa_flags & SA_SIGINFO) != 0)
238 (*(sigfunc))(sig, info, ucp);
240 ((ohandler)(*sigfunc))(
241 sig, info->si_code, (struct sigcontext *)ucp,
242 info->si_addr, (__sighandler_t *)sigfunc);
246 curthread->in_sigsuspend = in_sigsuspend;
247 curthread->cancel_point = cancel_point;
248 curthread->cancel_enable = cancel_enable;
250 memcpy(&uc2, ucp, sizeof(uc2));
251 SIGDELSET(uc2.uc_sigmask, SIGCANCEL);
253 /* reschedule cancellation */
254 check_cancel(curthread, &uc2);
256 __sys_sigreturn(&uc2);
260 _thr_ast(struct pthread *curthread)
263 if (!THR_IN_CRITICAL(curthread)) {
264 check_deferred_signal(curthread);
265 check_suspend(curthread);
266 check_cancel(curthread, NULL);
270 /* reschedule cancellation */
272 check_cancel(struct pthread *curthread, ucontext_t *ucp)
275 if (__predict_true(!curthread->cancel_pending ||
276 !curthread->cancel_enable || curthread->no_cancel))
280 * Otherwise, we are in defer mode, and we are at
281 * cancel point, tell kernel to not block the current
282 * thread on next cancelable system call.
284 * There are three cases we should call thr_wake() to
285 * turn on TDP_WAKEUP or send SIGCANCEL in kernel:
286 * 1) we are going to call a cancelable system call,
287 * non-zero cancel_point means we are already in
288 * cancelable state, next system call is cancelable.
289 * 2) because _thr_ast() may be called by
290 * THR_CRITICAL_LEAVE() which is used by rtld rwlock
291 * and any libthr internal locks, when rtld rwlock
292 * is used, it is mostly caused my an unresolved PLT.
293 * those routines may clear the TDP_WAKEUP flag by
294 * invoking some system calls, in those cases, we
295 * also should reenable the flag.
296 * 3) thread is in sigsuspend(), and the syscall insists
297 * on getting a signal before it agrees to return.
299 if (curthread->cancel_point) {
300 if (curthread->in_sigsuspend && ucp) {
301 SIGADDSET(ucp->uc_sigmask, SIGCANCEL);
302 curthread->unblock_sigcancel = 1;
303 _thr_send_sig(curthread, SIGCANCEL);
305 thr_wake(curthread->tid);
306 } else if (curthread->cancel_async) {
308 * asynchronous cancellation mode, act upon
311 _pthread_exit_mask(PTHREAD_CANCELED,
312 ucp? &ucp->uc_sigmask : NULL);
317 check_deferred_signal(struct pthread *curthread)
320 struct sigaction act;
324 if (__predict_true(curthread->deferred_siginfo.si_signo == 0 ||
325 curthread->deferred_run))
328 curthread->deferred_run = 1;
329 uc_len = __getcontextx_size();
332 if (curthread->deferred_siginfo.si_signo == 0) {
333 curthread->deferred_run = 0;
336 __fillcontextx2((char *)uc);
337 act = curthread->deferred_sigact;
338 uc->uc_sigmask = curthread->deferred_sigmask;
339 memcpy(&info, &curthread->deferred_siginfo, sizeof(siginfo_t));
341 curthread->deferred_siginfo.si_signo = 0;
342 handle_signal(&act, info.si_signo, &info, uc);
346 check_suspend(struct pthread *curthread)
350 if (__predict_true((curthread->flags &
351 (THR_FLAGS_NEED_SUSPEND | THR_FLAGS_SUSPENDED))
352 != THR_FLAGS_NEED_SUSPEND))
354 if (curthread == _single_thread)
356 if (curthread->force_exit)
360 * Blocks SIGCANCEL which other threads must send.
362 _thr_signal_block(curthread);
365 * Increase critical_count, here we don't use THR_LOCK/UNLOCK
366 * because we are leaf code, we don't want to recursively call
369 curthread->critical_count++;
370 THR_UMUTEX_LOCK(curthread, &(curthread)->lock);
371 while ((curthread->flags & (THR_FLAGS_NEED_SUSPEND |
372 THR_FLAGS_SUSPENDED)) == THR_FLAGS_NEED_SUSPEND) {
374 cycle = curthread->cycle;
376 /* Wake the thread suspending us. */
377 _thr_umtx_wake(&curthread->cycle, INT_MAX, 0);
380 * if we are from pthread_exit, we don't want to
381 * suspend, just go and die.
383 if (curthread->state == PS_DEAD)
385 curthread->flags |= THR_FLAGS_SUSPENDED;
386 THR_UMUTEX_UNLOCK(curthread, &(curthread)->lock);
387 _thr_umtx_wait_uint(&curthread->cycle, cycle, NULL, 0);
388 THR_UMUTEX_LOCK(curthread, &(curthread)->lock);
389 curthread->flags &= ~THR_FLAGS_SUSPENDED;
391 THR_UMUTEX_UNLOCK(curthread, &(curthread)->lock);
392 curthread->critical_count--;
394 _thr_signal_unblock(curthread);
398 _thr_signal_init(void)
400 struct sigaction act;
402 /* Install SIGCANCEL handler. */
403 SIGFILLSET(act.sa_mask);
404 act.sa_flags = SA_SIGINFO;
405 act.sa_sigaction = (__siginfohandler_t *)&sigcancel_handler;
406 __sys_sigaction(SIGCANCEL, &act, NULL);
408 /* Unblock SIGCANCEL */
409 SIGEMPTYSET(act.sa_mask);
410 SIGADDSET(act.sa_mask, SIGCANCEL);
411 __sys_sigprocmask(SIG_UNBLOCK, &act.sa_mask, NULL);
415 _thr_sigact_unload(struct dl_phdr_info *phdr_info)
418 struct pthread *curthread = _get_curthread();
419 struct urwlock *rwlp;
420 struct sigaction *actp;
421 struct sigaction kact;
422 void (*handler)(int);
425 _thr_signal_block(curthread);
426 for (sig = 1; sig <= _SIG_MAXSIG; sig++) {
427 actp = &_thr_sigact[sig-1].sigact;
429 handler = actp->sa_handler;
430 if (handler != SIG_DFL && handler != SIG_IGN &&
431 __elf_phdr_match_addr(phdr_info, handler)) {
432 rwlp = &_thr_sigact[sig-1].lock;
433 _thr_rwl_wrlock(rwlp);
434 if (handler != actp->sa_handler) {
435 _thr_rwl_unlock(rwlp);
438 actp->sa_handler = SIG_DFL;
439 actp->sa_flags = SA_SIGINFO;
440 SIGEMPTYSET(actp->sa_mask);
441 if (__sys_sigaction(sig, NULL, &kact) == 0 &&
442 kact.sa_handler != SIG_DFL &&
443 kact.sa_handler != SIG_IGN)
444 __sys_sigaction(sig, actp, NULL);
445 _thr_rwl_unlock(rwlp);
448 _thr_signal_unblock(curthread);
453 _thr_signal_prefork(void)
457 for (i = 1; i <= _SIG_MAXSIG; ++i)
458 _thr_rwl_rdlock(&_thr_sigact[i-1].lock);
462 _thr_signal_postfork(void)
466 for (i = 1; i <= _SIG_MAXSIG; ++i)
467 _thr_rwl_unlock(&_thr_sigact[i-1].lock);
471 _thr_signal_postfork_child(void)
475 for (i = 1; i <= _SIG_MAXSIG; ++i)
476 bzero(&_thr_sigact[i-1].lock, sizeof(struct urwlock));
480 _thr_signal_deinit(void)
484 __weak_reference(___pause, pause);
491 if (_sigprocmask(SIG_BLOCK, NULL, &oset) == -1)
493 return (__sigsuspend(&oset));
496 __weak_reference(_raise, raise);
501 return _thr_send_sig(_get_curthread(), sig);
504 __weak_reference(_sigaction, sigaction);
507 _sigaction(int sig, const struct sigaction * act, struct sigaction * oact)
509 struct sigaction newact, oldact, oldact2;
511 int ret = 0, err = 0;
513 if (!_SIG_VALID(sig) || sig == SIGCANCEL) {
521 __sys_sigprocmask(SIG_SETMASK, &_thr_maskset, &oldset);
522 _thr_rwl_wrlock(&_thr_sigact[sig-1].lock);
525 oldact2 = _thr_sigact[sig-1].sigact;
528 * if a new sig handler is SIG_DFL or SIG_IGN,
529 * don't remove old handler from _thr_sigact[],
530 * so deferred signals still can use the handlers,
531 * multiple threads invoking sigaction itself is
532 * a race condition, so it is not a problem.
534 if (newact.sa_handler != SIG_DFL &&
535 newact.sa_handler != SIG_IGN) {
536 _thr_sigact[sig-1].sigact = newact;
538 &_thr_sigact[sig-1].sigact.sa_mask);
539 newact.sa_flags &= ~SA_NODEFER;
540 newact.sa_flags |= SA_SIGINFO;
541 newact.sa_sigaction = thr_sighandler;
542 newact.sa_mask = _thr_maskset; /* mask all signals */
544 if ((ret = __sys_sigaction(sig, &newact, &oldact))) {
546 _thr_sigact[sig-1].sigact = oldact2;
548 } else if (oact != NULL) {
549 ret = __sys_sigaction(sig, NULL, &oldact);
553 if (oldact.sa_handler != SIG_DFL &&
554 oldact.sa_handler != SIG_IGN) {
557 else if (oact != NULL)
558 oldact = _thr_sigact[sig-1].sigact;
561 _thr_rwl_unlock(&_thr_sigact[sig-1].lock);
562 __sys_sigprocmask(SIG_SETMASK, &oldset, NULL);
573 __weak_reference(_sigprocmask, sigprocmask);
576 _sigprocmask(int how, const sigset_t *set, sigset_t *oset)
578 const sigset_t *p = set;
581 if (how != SIG_UNBLOCK) {
584 SIGDELSET(newset, SIGCANCEL);
588 return (__sys_sigprocmask(how, p, oset));
591 __weak_reference(_pthread_sigmask, pthread_sigmask);
594 _pthread_sigmask(int how, const sigset_t *set, sigset_t *oset)
596 if (_sigprocmask(how, set, oset))
601 __weak_reference(__sigsuspend, sigsuspend);
604 _sigsuspend(const sigset_t * set)
608 return (__sys_sigsuspend(thr_remove_thr_signals(set, &newset)));
612 __sigsuspend(const sigset_t * set)
614 struct pthread *curthread;
618 curthread = _get_curthread();
620 old = curthread->in_sigsuspend;
621 curthread->in_sigsuspend = 1;
622 _thr_cancel_enter(curthread);
623 ret = __sys_sigsuspend(thr_remove_thr_signals(set, &newset));
624 _thr_cancel_leave(curthread, 1);
625 curthread->in_sigsuspend = old;
626 if (curthread->unblock_sigcancel) {
627 curthread->unblock_sigcancel = 0;
629 SIGADDSET(newset, SIGCANCEL);
630 __sys_sigprocmask(SIG_UNBLOCK, &newset, NULL);
636 __weak_reference(___sigwait, sigwait);
637 __weak_reference(__sigtimedwait, sigtimedwait);
638 __weak_reference(__sigwaitinfo, sigwaitinfo);
641 _sigtimedwait(const sigset_t *set, siginfo_t *info,
642 const struct timespec * timeout)
646 return (__sys_sigtimedwait(thr_remove_thr_signals(set, &newset), info,
651 * Cancellation behavior:
652 * Thread may be canceled at start, if thread got signal,
653 * it is not canceled.
656 __sigtimedwait(const sigset_t *set, siginfo_t *info,
657 const struct timespec * timeout)
659 struct pthread *curthread = _get_curthread();
663 _thr_cancel_enter(curthread);
664 ret = __sys_sigtimedwait(thr_remove_thr_signals(set, &newset), info,
666 _thr_cancel_leave(curthread, (ret == -1));
671 _sigwaitinfo(const sigset_t *set, siginfo_t *info)
675 return (__sys_sigwaitinfo(thr_remove_thr_signals(set, &newset), info));
679 * Cancellation behavior:
680 * Thread may be canceled at start, if thread got signal,
681 * it is not canceled.
684 __sigwaitinfo(const sigset_t *set, siginfo_t *info)
686 struct pthread *curthread = _get_curthread();
690 _thr_cancel_enter(curthread);
691 ret = __sys_sigwaitinfo(thr_remove_thr_signals(set, &newset), info);
692 _thr_cancel_leave(curthread, ret == -1);
697 _sigwait(const sigset_t *set, int *sig)
701 return (__sys_sigwait(thr_remove_thr_signals(set, &newset), sig));
705 * Cancellation behavior:
706 * Thread may be canceled at start, if thread got signal,
707 * it is not canceled.
710 ___sigwait(const sigset_t *set, int *sig)
712 struct pthread *curthread = _get_curthread();
717 _thr_cancel_enter(curthread);
718 ret = __sys_sigwait(thr_remove_thr_signals(set, &newset), sig);
719 _thr_cancel_leave(curthread, (ret != 0));
720 } while (ret == EINTR);
724 __weak_reference(_setcontext, setcontext);
726 _setcontext(const ucontext_t *ucp)
734 if (!SIGISMEMBER(uc.uc_sigmask, SIGCANCEL))
735 return __sys_setcontext(ucp);
736 (void) memcpy(&uc, ucp, sizeof(uc));
737 SIGDELSET(uc.uc_sigmask, SIGCANCEL);
738 return __sys_setcontext(&uc);
741 __weak_reference(_swapcontext, swapcontext);
743 _swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
747 if (oucp == NULL || ucp == NULL) {
751 if (SIGISMEMBER(ucp->uc_sigmask, SIGCANCEL)) {
752 (void) memcpy(&uc, ucp, sizeof(uc));
753 SIGDELSET(uc.uc_sigmask, SIGCANCEL);
756 return __sys_swapcontext(oucp, ucp);