| Current Path : /usr/src/lib/libthr/thread/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //usr/src/lib/libthr/thread/thr_sig.c |
/*
* 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: release/9.1.0/lib/libthr/thread/thr_sig.c 234073 2012-04-09 22:01:43Z jilles $
*/
#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);
}