diff options
Diffstat (limited to 'lib/libthr/thread/thr_sig.c')
| -rw-r--r-- | lib/libthr/thread/thr_sig.c | 748 |
1 files changed, 748 insertions, 0 deletions
diff --git a/lib/libthr/thread/thr_sig.c b/lib/libthr/thread/thr_sig.c new file mode 100644 index 0000000..3dee8b7 --- /dev/null +++ b/lib/libthr/thread/thr_sig.c @@ -0,0 +1,748 @@ +/* + * Copyright (c) 2005, David Xu <davidxu@freebsd.org> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice unmodified, this list of conditions, and the following + * disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#include "namespace.h" +#include <sys/param.h> +#include <sys/types.h> +#include <sys/signalvar.h> +#include <signal.h> +#include <errno.h> +#include <stdlib.h> +#include <string.h> +#include <pthread.h> +#include "un-namespace.h" +#include "libc_private.h" + +#include "thr_private.h" + +/* #define DEBUG_SIGNAL */ +#ifdef DEBUG_SIGNAL +#define DBG_MSG stdout_debug +#else +#define DBG_MSG(x...) +#endif + +struct usigaction { + struct sigaction sigact; + struct urwlock lock; +}; + +static struct usigaction _thr_sigact[_SIG_MAXSIG]; + +static void thr_sighandler(int, siginfo_t *, void *); +static void handle_signal(struct sigaction *, int, siginfo_t *, ucontext_t *); +static void check_deferred_signal(struct pthread *); +static void check_suspend(struct pthread *); +static void check_cancel(struct pthread *curthread, ucontext_t *ucp); + +int ___pause(void); +int _raise(int); +int __sigtimedwait(const sigset_t *set, siginfo_t *info, + const struct timespec * timeout); +int _sigtimedwait(const sigset_t *set, siginfo_t *info, + const struct timespec * timeout); +int __sigwaitinfo(const sigset_t *set, siginfo_t *info); +int _sigwaitinfo(const sigset_t *set, siginfo_t *info); +int ___sigwait(const sigset_t *set, int *sig); +int _sigwait(const sigset_t *set, int *sig); +int __sigsuspend(const sigset_t *sigmask); +int _sigaction(int, const struct sigaction *, struct sigaction *); +int _setcontext(const ucontext_t *); +int _swapcontext(ucontext_t *, const ucontext_t *); + +static const sigset_t _thr_deferset={{ + 0xffffffff & ~(_SIG_BIT(SIGBUS)|_SIG_BIT(SIGILL)|_SIG_BIT(SIGFPE)| + _SIG_BIT(SIGSEGV)|_SIG_BIT(SIGTRAP)|_SIG_BIT(SIGSYS)), + 0xffffffff, + 0xffffffff, + 0xffffffff}}; + +static const sigset_t _thr_maskset={{ + 0xffffffff, + 0xffffffff, + 0xffffffff, + 0xffffffff}}; + +void +_thr_signal_block(struct pthread *curthread) +{ + + if (curthread->sigblock > 0) { + curthread->sigblock++; + return; + } + __sys_sigprocmask(SIG_BLOCK, &_thr_maskset, &curthread->sigmask); + curthread->sigblock++; +} + +void +_thr_signal_unblock(struct pthread *curthread) +{ + if (--curthread->sigblock == 0) + __sys_sigprocmask(SIG_SETMASK, &curthread->sigmask, NULL); +} + +int +_thr_send_sig(struct pthread *thread, int sig) +{ + return thr_kill(thread->tid, sig); +} + +static inline void +remove_thr_signals(sigset_t *set) +{ + if (SIGISMEMBER(*set, SIGCANCEL)) + SIGDELSET(*set, SIGCANCEL); +} + +static const sigset_t * +thr_remove_thr_signals(const sigset_t *set, sigset_t *newset) +{ + *newset = *set; + remove_thr_signals(newset); + return (newset); +} + +static void +sigcancel_handler(int sig __unused, + siginfo_t *info __unused, ucontext_t *ucp) +{ + struct pthread *curthread = _get_curthread(); + int err; + + if (THR_IN_CRITICAL(curthread)) + return; + err = errno; + check_suspend(curthread); + check_cancel(curthread, ucp); + errno = err; +} + +typedef void (*ohandler)(int sig, int code, + struct sigcontext *scp, char *addr, __sighandler_t *catcher); + +/* + * The signal handler wrapper is entered with all signal masked. + */ +static void +thr_sighandler(int sig, siginfo_t *info, void *_ucp) +{ + struct pthread *curthread = _get_curthread(); + ucontext_t *ucp = _ucp; + struct sigaction act; + int err; + + err = errno; + _thr_rwl_rdlock(&_thr_sigact[sig-1].lock); + act = _thr_sigact[sig-1].sigact; + _thr_rwl_unlock(&_thr_sigact[sig-1].lock); + errno = err; + + /* + * if a thread is in critical region, for example it holds low level locks, + * try to defer the signal processing, however if the signal is synchronous + * signal, it means a bad thing has happened, this is a programming error, + * resuming fault point can not help anything (normally causes deadloop), + * so here we let user code handle it immediately. + */ + if (THR_IN_CRITICAL(curthread) && SIGISMEMBER(_thr_deferset, sig)) { + memcpy(&curthread->deferred_sigact, &act, sizeof(struct sigaction)); + memcpy(&curthread->deferred_siginfo, info, sizeof(siginfo_t)); + curthread->deferred_sigmask = ucp->uc_sigmask; + /* mask all signals, we will restore it later. */ + ucp->uc_sigmask = _thr_deferset; + return; + } + + handle_signal(&act, sig, info, ucp); +} + +static void +handle_signal(struct sigaction *actp, int sig, siginfo_t *info, ucontext_t *ucp) +{ + struct pthread *curthread = _get_curthread(); + ucontext_t uc2; + __siginfohandler_t *sigfunc; + int cancel_point; + int cancel_async; + int cancel_enable; + int in_sigsuspend; + int err; + + /* add previous level mask */ + SIGSETOR(actp->sa_mask, ucp->uc_sigmask); + + /* add this signal's mask */ + if (!(actp->sa_flags & SA_NODEFER)) + SIGADDSET(actp->sa_mask, sig); + + in_sigsuspend = curthread->in_sigsuspend; + curthread->in_sigsuspend = 0; + + /* + * if thread is in deferred cancellation mode, disable cancellation + * in signal handler. + * if user signal handler calls a cancellation point function, e.g, + * it calls write() to write data to file, because write() is a + * cancellation point, the thread is immediately cancelled if + * cancellation is pending, to avoid this problem while thread is in + * deferring mode, cancellation is temporarily disabled. + */ + cancel_point = curthread->cancel_point; + cancel_async = curthread->cancel_async; + cancel_enable = curthread->cancel_enable; + curthread->cancel_point = 0; + if (!cancel_async) + curthread->cancel_enable = 0; + + /* restore correct mask before calling user handler */ + __sys_sigprocmask(SIG_SETMASK, &actp->sa_mask, NULL); + + sigfunc = actp->sa_sigaction; + + /* + * We have already reset cancellation point flags, so if user's code + * longjmp()s out of its signal handler, wish its jmpbuf was set + * outside of a cancellation point, in most cases, this would be + * true. however, ther is no way to save cancel_enable in jmpbuf, + * so after setjmps() returns once more, the user code may need to + * re-set cancel_enable flag by calling pthread_setcancelstate(). + */ + if ((actp->sa_flags & SA_SIGINFO) != 0) + (*(sigfunc))(sig, info, ucp); + else { + ((ohandler)(*sigfunc))( + sig, info->si_code, (struct sigcontext *)ucp, + info->si_addr, (__sighandler_t *)sigfunc); + } + err = errno; + + curthread->in_sigsuspend = in_sigsuspend; + curthread->cancel_point = cancel_point; + curthread->cancel_enable = cancel_enable; + + memcpy(&uc2, ucp, sizeof(uc2)); + SIGDELSET(uc2.uc_sigmask, SIGCANCEL); + + /* reschedule cancellation */ + check_cancel(curthread, &uc2); + errno = err; + __sys_sigreturn(&uc2); +} + +void +_thr_ast(struct pthread *curthread) +{ + + if (!THR_IN_CRITICAL(curthread)) { + check_deferred_signal(curthread); + check_suspend(curthread); + check_cancel(curthread, NULL); + } +} + +/* reschedule cancellation */ +static void +check_cancel(struct pthread *curthread, ucontext_t *ucp) +{ + + if (__predict_true(!curthread->cancel_pending || + !curthread->cancel_enable || curthread->no_cancel)) + return; + + /* + * Otherwise, we are in defer mode, and we are at + * cancel point, tell kernel to not block the current + * thread on next cancelable system call. + * + * There are three cases we should call thr_wake() to + * turn on TDP_WAKEUP or send SIGCANCEL in kernel: + * 1) we are going to call a cancelable system call, + * non-zero cancel_point means we are already in + * cancelable state, next system call is cancelable. + * 2) because _thr_ast() may be called by + * THR_CRITICAL_LEAVE() which is used by rtld rwlock + * and any libthr internal locks, when rtld rwlock + * is used, it is mostly caused my an unresolved PLT. + * those routines may clear the TDP_WAKEUP flag by + * invoking some system calls, in those cases, we + * also should reenable the flag. + * 3) thread is in sigsuspend(), and the syscall insists + * on getting a signal before it agrees to return. + */ + if (curthread->cancel_point) { + if (curthread->in_sigsuspend && ucp) { + SIGADDSET(ucp->uc_sigmask, SIGCANCEL); + curthread->unblock_sigcancel = 1; + _thr_send_sig(curthread, SIGCANCEL); + } else + thr_wake(curthread->tid); + } else if (curthread->cancel_async) { + /* + * asynchronous cancellation mode, act upon + * immediately. + */ + _pthread_exit_mask(PTHREAD_CANCELED, + ucp? &ucp->uc_sigmask : NULL); + } +} + +static void +check_deferred_signal(struct pthread *curthread) +{ + ucontext_t *uc; + struct sigaction act; + siginfo_t info; + + if (__predict_true(curthread->deferred_siginfo.si_signo == 0)) + return; + +#if defined(__amd64__) || defined(__i386__) + uc = alloca(__getcontextx_size()); + __fillcontextx((char *)uc); +#else + ucontext_t ucv; + uc = &ucv; + getcontext(uc); +#endif + if (curthread->deferred_siginfo.si_signo != 0) { + act = curthread->deferred_sigact; + uc->uc_sigmask = curthread->deferred_sigmask; + memcpy(&info, &curthread->deferred_siginfo, sizeof(siginfo_t)); + /* remove signal */ + curthread->deferred_siginfo.si_signo = 0; + if (act.sa_flags & SA_RESETHAND) { + struct sigaction tact; + + tact = act; + tact.sa_handler = SIG_DFL; + _sigaction(info.si_signo, &tact, NULL); + } + handle_signal(&act, info.si_signo, &info, uc); + } +} + +static void +check_suspend(struct pthread *curthread) +{ + uint32_t cycle; + + if (__predict_true((curthread->flags & + (THR_FLAGS_NEED_SUSPEND | THR_FLAGS_SUSPENDED)) + != THR_FLAGS_NEED_SUSPEND)) + return; + + if (curthread->force_exit) + return; + + /* + * Blocks SIGCANCEL which other threads must send. + */ + _thr_signal_block(curthread); + + /* + * Increase critical_count, here we don't use THR_LOCK/UNLOCK + * because we are leaf code, we don't want to recursively call + * ourself. + */ + curthread->critical_count++; + THR_UMUTEX_LOCK(curthread, &(curthread)->lock); + while ((curthread->flags & (THR_FLAGS_NEED_SUSPEND | + THR_FLAGS_SUSPENDED)) == THR_FLAGS_NEED_SUSPEND) { + curthread->cycle++; + cycle = curthread->cycle; + + /* Wake the thread suspending us. */ + _thr_umtx_wake(&curthread->cycle, INT_MAX, 0); + + /* + * if we are from pthread_exit, we don't want to + * suspend, just go and die. + */ + if (curthread->state == PS_DEAD) + break; + curthread->flags |= THR_FLAGS_SUSPENDED; + THR_UMUTEX_UNLOCK(curthread, &(curthread)->lock); + _thr_umtx_wait_uint(&curthread->cycle, cycle, NULL, 0); + THR_UMUTEX_LOCK(curthread, &(curthread)->lock); + curthread->flags &= ~THR_FLAGS_SUSPENDED; + } + THR_UMUTEX_UNLOCK(curthread, &(curthread)->lock); + curthread->critical_count--; + + _thr_signal_unblock(curthread); +} + +void +_thr_signal_init(void) +{ + struct sigaction act; + + /* Install SIGCANCEL handler. */ + SIGFILLSET(act.sa_mask); + act.sa_flags = SA_SIGINFO; + act.sa_sigaction = (__siginfohandler_t *)&sigcancel_handler; + __sys_sigaction(SIGCANCEL, &act, NULL); + + /* Unblock SIGCANCEL */ + SIGEMPTYSET(act.sa_mask); + SIGADDSET(act.sa_mask, SIGCANCEL); + __sys_sigprocmask(SIG_UNBLOCK, &act.sa_mask, NULL); +} + +void +_thr_sigact_unload(struct dl_phdr_info *phdr_info) +{ +#if 0 + struct pthread *curthread = _get_curthread(); + struct urwlock *rwlp; + struct sigaction *actp; + struct sigaction kact; + void (*handler)(int); + int sig; + + _thr_signal_block(curthread); + for (sig = 1; sig <= _SIG_MAXSIG; sig++) { + actp = &_thr_sigact[sig-1].sigact; +retry: + handler = actp->sa_handler; + if (handler != SIG_DFL && handler != SIG_IGN && + __elf_phdr_match_addr(phdr_info, handler)) { + rwlp = &_thr_sigact[sig-1].lock; + _thr_rwl_wrlock(rwlp); + if (handler != actp->sa_handler) { + _thr_rwl_unlock(rwlp); + goto retry; + } + actp->sa_handler = SIG_DFL; + actp->sa_flags = SA_SIGINFO; + SIGEMPTYSET(actp->sa_mask); + if (__sys_sigaction(sig, NULL, &kact) == 0 && + kact.sa_handler != SIG_DFL && + kact.sa_handler != SIG_IGN) + __sys_sigaction(sig, actp, NULL); + _thr_rwl_unlock(rwlp); + } + } + _thr_signal_unblock(curthread); +#endif +} + +void +_thr_signal_prefork(void) +{ + int i; + + for (i = 1; i <= _SIG_MAXSIG; ++i) + _thr_rwl_rdlock(&_thr_sigact[i-1].lock); +} + +void +_thr_signal_postfork(void) +{ + int i; + + for (i = 1; i <= _SIG_MAXSIG; ++i) + _thr_rwl_unlock(&_thr_sigact[i-1].lock); +} + +void +_thr_signal_postfork_child(void) +{ + int i; + + for (i = 1; i <= _SIG_MAXSIG; ++i) + bzero(&_thr_sigact[i-1].lock, sizeof(struct urwlock)); +} + +void +_thr_signal_deinit(void) +{ +} + +__weak_reference(___pause, pause); + +int +___pause(void) +{ + sigset_t oset; + + if (_sigprocmask(SIG_BLOCK, NULL, &oset) == -1) + return (-1); + return (__sigsuspend(&oset)); +} + +__weak_reference(_raise, raise); + +int +_raise(int sig) +{ + return _thr_send_sig(_get_curthread(), sig); +} + +__weak_reference(_sigaction, sigaction); + +int +_sigaction(int sig, const struct sigaction * act, struct sigaction * oact) +{ + struct sigaction newact, oldact, oldact2; + sigset_t oldset; + int ret = 0, err = 0; + + if (!_SIG_VALID(sig) || sig == SIGCANCEL) { + errno = EINVAL; + return (-1); + } + + if (act) + newact = *act; + + __sys_sigprocmask(SIG_SETMASK, &_thr_maskset, &oldset); + _thr_rwl_wrlock(&_thr_sigact[sig-1].lock); + + if (act != NULL) { + oldact2 = _thr_sigact[sig-1].sigact; + + /* + * if a new sig handler is SIG_DFL or SIG_IGN, + * don't remove old handler from _thr_sigact[], + * so deferred signals still can use the handlers, + * multiple threads invoking sigaction itself is + * a race condition, so it is not a problem. + */ + if (newact.sa_handler != SIG_DFL && + newact.sa_handler != SIG_IGN) { + _thr_sigact[sig-1].sigact = newact; + remove_thr_signals( + &_thr_sigact[sig-1].sigact.sa_mask); + newact.sa_flags &= ~SA_NODEFER; + newact.sa_flags |= SA_SIGINFO; + newact.sa_sigaction = thr_sighandler; + newact.sa_mask = _thr_maskset; /* mask all signals */ + } + if ((ret = __sys_sigaction(sig, &newact, &oldact))) { + err = errno; + _thr_sigact[sig-1].sigact = oldact2; + } + } else if (oact != NULL) { + ret = __sys_sigaction(sig, NULL, &oldact); + err = errno; + } + + if (oldact.sa_handler != SIG_DFL && + oldact.sa_handler != SIG_IGN) { + if (act != NULL) + oldact = oldact2; + else if (oact != NULL) + oldact = _thr_sigact[sig-1].sigact; + } + + _thr_rwl_unlock(&_thr_sigact[sig-1].lock); + __sys_sigprocmask(SIG_SETMASK, &oldset, NULL); + + if (ret == 0) { + if (oact != NULL) + *oact = oldact; + } else { + errno = err; + } + return (ret); +} + +__weak_reference(_sigprocmask, sigprocmask); + +int +_sigprocmask(int how, const sigset_t *set, sigset_t *oset) +{ + const sigset_t *p = set; + sigset_t newset; + + if (how != SIG_UNBLOCK) { + if (set != NULL) { + newset = *set; + SIGDELSET(newset, SIGCANCEL); + p = &newset; + } + } + return (__sys_sigprocmask(how, p, oset)); +} + +__weak_reference(_pthread_sigmask, pthread_sigmask); + +int +_pthread_sigmask(int how, const sigset_t *set, sigset_t *oset) +{ + if (_sigprocmask(how, set, oset)) + return (errno); + return (0); +} + +__weak_reference(__sigsuspend, sigsuspend); + +int +_sigsuspend(const sigset_t * set) +{ + sigset_t newset; + + return (__sys_sigsuspend(thr_remove_thr_signals(set, &newset))); +} + +int +__sigsuspend(const sigset_t * set) +{ + struct pthread *curthread; + sigset_t newset; + int ret, old; + + curthread = _get_curthread(); + + old = curthread->in_sigsuspend; + curthread->in_sigsuspend = 1; + _thr_cancel_enter(curthread); + ret = __sys_sigsuspend(thr_remove_thr_signals(set, &newset)); + _thr_cancel_leave(curthread, 1); + curthread->in_sigsuspend = old; + if (curthread->unblock_sigcancel) { + curthread->unblock_sigcancel = 0; + SIGEMPTYSET(newset); + SIGADDSET(newset, SIGCANCEL); + __sys_sigprocmask(SIG_UNBLOCK, &newset, NULL); + } + + return (ret); +} + +__weak_reference(___sigwait, sigwait); +__weak_reference(__sigtimedwait, sigtimedwait); +__weak_reference(__sigwaitinfo, sigwaitinfo); + +int +_sigtimedwait(const sigset_t *set, siginfo_t *info, + const struct timespec * timeout) +{ + sigset_t newset; + + return (__sys_sigtimedwait(thr_remove_thr_signals(set, &newset), info, + timeout)); +} + +/* + * Cancellation behavior: + * Thread may be canceled at start, if thread got signal, + * it is not canceled. + */ +int +__sigtimedwait(const sigset_t *set, siginfo_t *info, + const struct timespec * timeout) +{ + struct pthread *curthread = _get_curthread(); + sigset_t newset; + int ret; + + _thr_cancel_enter(curthread); + ret = __sys_sigtimedwait(thr_remove_thr_signals(set, &newset), info, + timeout); + _thr_cancel_leave(curthread, (ret == -1)); + return (ret); +} + +int +_sigwaitinfo(const sigset_t *set, siginfo_t *info) +{ + sigset_t newset; + + return (__sys_sigwaitinfo(thr_remove_thr_signals(set, &newset), info)); +} + +/* + * Cancellation behavior: + * Thread may be canceled at start, if thread got signal, + * it is not canceled. + */ +int +__sigwaitinfo(const sigset_t *set, siginfo_t *info) +{ + struct pthread *curthread = _get_curthread(); + sigset_t newset; + int ret; + + _thr_cancel_enter(curthread); + ret = __sys_sigwaitinfo(thr_remove_thr_signals(set, &newset), info); + _thr_cancel_leave(curthread, ret == -1); + return (ret); +} + +int +_sigwait(const sigset_t *set, int *sig) +{ + sigset_t newset; + + return (__sys_sigwait(thr_remove_thr_signals(set, &newset), sig)); +} + +/* + * Cancellation behavior: + * Thread may be canceled at start, if thread got signal, + * it is not canceled. + */ +int +___sigwait(const sigset_t *set, int *sig) +{ + struct pthread *curthread = _get_curthread(); + sigset_t newset; + int ret; + + do { + _thr_cancel_enter(curthread); + ret = __sys_sigwait(thr_remove_thr_signals(set, &newset), sig); + _thr_cancel_leave(curthread, (ret != 0)); + } while (ret == EINTR); + return (ret); +} + +__weak_reference(_setcontext, setcontext); +int +_setcontext(const ucontext_t *ucp) +{ + ucontext_t uc; + + (void) memcpy(&uc, ucp, sizeof(uc)); + remove_thr_signals(&uc.uc_sigmask); + return __sys_setcontext(&uc); +} + +__weak_reference(_swapcontext, swapcontext); +int +_swapcontext(ucontext_t *oucp, const ucontext_t *ucp) +{ + ucontext_t uc; + + (void) memcpy(&uc, ucp, sizeof(uc)); + remove_thr_signals(&uc.uc_sigmask); + return __sys_swapcontext(oucp, &uc); +} |
