/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 * Copyright (c) 2014, Joyent, Inc.  All rights reserved.
 */

/*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All Rights Reserved   */

#include <sys/param.h>
#include <sys/types.h>
#include <sys/bitmap.h>
#include <sys/sysmacros.h>
#include <sys/systm.h>
#include <sys/cred.h>
#include <sys/user.h>
#include <sys/errno.h>
#include <sys/proc.h>
#include <sys/poll_impl.h> /* only needed for kludge in sigwaiting_send() */
#include <sys/signal.h>
#include <sys/siginfo.h>
#include <sys/fault.h>
#include <sys/ucontext.h>
#include <sys/procfs.h>
#include <sys/wait.h>
#include <sys/class.h>
#include <sys/mman.h>
#include <sys/procset.h>
#include <sys/kmem.h>
#include <sys/cpuvar.h>
#include <sys/prsystm.h>
#include <sys/debug.h>
#include <vm/as.h>
#include <sys/bitmap.h>
#include <c2/audit.h>
#include <sys/core.h>
#include <sys/schedctl.h>
#include <sys/contract/process_impl.h>
#include <sys/cyclic.h>
#include <sys/dtrace.h>
#include <sys/sdt.h>
#include <sys/signalfd.h>

const k_sigset_t nullsmask = {0, 0, 0};

const k_sigset_t fillset =      /* MUST be contiguous */
        {FILLSET0, FILLSET1, FILLSET2};

const k_sigset_t cantmask =
        {CANTMASK0, CANTMASK1, CANTMASK2};

const k_sigset_t cantreset =
        {(sigmask(SIGILL)|sigmask(SIGTRAP)|sigmask(SIGPWR)), 0, 0};

const k_sigset_t ignoredefault =
        {(sigmask(SIGCONT)|sigmask(SIGCLD)|sigmask(SIGPWR)
        |sigmask(SIGWINCH)|sigmask(SIGURG)|sigmask(SIGWAITING)),
        (sigmask(SIGLWP)|sigmask(SIGCANCEL)|sigmask(SIGFREEZE)
        |sigmask(SIGTHAW)|sigmask(SIGXRES)|sigmask(SIGJVM1)
        |sigmask(SIGJVM2)|sigmask(SIGINFO)), 0};

const k_sigset_t stopdefault =
        {(sigmask(SIGSTOP)|sigmask(SIGTSTP)|sigmask(SIGTTOU)|sigmask(SIGTTIN)),
        0, 0};

const k_sigset_t coredefault =
        {(sigmask(SIGQUIT)|sigmask(SIGILL)|sigmask(SIGTRAP)|sigmask(SIGIOT)
        |sigmask(SIGEMT)|sigmask(SIGFPE)|sigmask(SIGBUS)|sigmask(SIGSEGV)
        |sigmask(SIGSYS)|sigmask(SIGXCPU)|sigmask(SIGXFSZ)), 0, 0};

const k_sigset_t holdvfork =
        {(sigmask(SIGTTOU)|sigmask(SIGTTIN)|sigmask(SIGTSTP)), 0, 0};

static  int     isjobstop(int);
static  void    post_sigcld(proc_t *, sigqueue_t *);


/*
 * signalfd helper function which is set when the signalfd driver loads.
 */
void (*sigfd_exit_helper)();

/*
 * Internal variables for counting number of user thread stop requests posted.
 * They may not be accurate at some special situation such as that a virtually
 * stopped thread starts to run.
 */
static int num_utstop;
/*
 * Internal variables for broadcasting an event when all thread stop requests
 * are processed.
 */
static kcondvar_t utstop_cv;

static kmutex_t thread_stop_lock;
void del_one_utstop(void);

/*
 * Send the specified signal to the specified process.
 */
void
psignal(proc_t *p, int sig)
{
        mutex_enter(&p->p_lock);
        sigtoproc(p, NULL, sig);
        mutex_exit(&p->p_lock);
}

/*
 * Send the specified signal to the specified thread.
 */
void
tsignal(kthread_t *t, int sig)
{
        proc_t *p = ttoproc(t);

        mutex_enter(&p->p_lock);
        sigtoproc(p, t, sig);
        mutex_exit(&p->p_lock);
}

int
signal_is_blocked(kthread_t *t, int sig)
{
        return (sigismember(&t->t_hold, sig) ||
            (schedctl_sigblock(t) && !sigismember(&cantmask, sig)));
}

/*
 * Return true if the signal can safely be discarded on generation.
 * That is, if there is no need for the signal on the receiving end.
 * The answer is true if the process is a zombie or
 * if all of these conditions are true:
 *      the signal is being ignored
 *      the process is single-threaded
 *      the signal is not being traced by /proc
 *      the signal is not blocked by the process
 *      the signal is not being accepted via sigwait()
 */
static int
sig_discardable(proc_t *p, int sig)
{
        kthread_t *t = p->p_tlist;

        return (t == NULL ||            /* if zombie or ... */
            (sigismember(&p->p_ignore, sig) &&  /* signal is ignored */
            t->t_forw == t &&                   /* and single-threaded */
            !tracing(p, sig) &&                 /* and no /proc tracing */
            !signal_is_blocked(t, sig) &&       /* and signal not blocked */
            !sigismember(&t->t_sigwait, sig))); /* and not being accepted */
}

/*
 * Return true if this thread is going to eat this signal soon.
 * Note that, if the signal is SIGKILL, we force stopped threads to be
 * set running (to make SIGKILL be a sure kill), but only if the process
 * is not currently locked by /proc (the P_PR_LOCK flag).  Code in /proc
 * relies on the fact that a process will not change shape while P_PR_LOCK
 * is set (it drops and reacquires p->p_lock while leaving P_PR_LOCK set).
 * We wish that we could simply call prbarrier() below, in sigtoproc(), to
 * ensure that the process is not locked by /proc, but prbarrier() drops
 * and reacquires p->p_lock and dropping p->p_lock here would be damaging.
 */
int
eat_signal(kthread_t *t, int sig)
{
        int rval = 0;
        ASSERT(THREAD_LOCK_HELD(t));

        /*
         * Do not do anything if the target thread has the signal blocked.
         */
        if (!signal_is_blocked(t, sig)) {
                t->t_sig_check = 1;     /* have thread do an issig */
                if (ISWAKEABLE(t) || ISWAITING(t)) {
                        setrun_locked(t);
                        rval = 1;
                } else if (t->t_state == TS_STOPPED && sig == SIGKILL &&
                    !(ttoproc(t)->p_proc_flag & P_PR_LOCK)) {
                        ttoproc(t)->p_stopsig = 0;
                        t->t_dtrace_stop = 0;
                        t->t_schedflag |= TS_XSTART | TS_PSTART;
                        setrun_locked(t);
                } else if (t != curthread && t->t_state == TS_ONPROC) {
                        aston(t);       /* make it do issig promptly */
                        if (t->t_cpu != CPU)
                                poke_cpu(t->t_cpu->cpu_id);
                        rval = 1;
                } else if (t->t_state == TS_RUN) {
                        rval = 1;
                }
        }

        return (rval);
}

/*
 * Post a signal.
 * If a non-null thread pointer is passed, then post the signal
 * to the thread/lwp, otherwise post the signal to the process.
 */
void
sigtoproc(proc_t *p, kthread_t *t, int sig)
{
        kthread_t *tt;
        int ext = !(curproc->p_flag & SSYS) &&
            (curproc->p_ct_process != p->p_ct_process);

        ASSERT(MUTEX_HELD(&p->p_lock));

        /* System processes don't get signals */
        if (sig <= 0 || sig >= NSIG || (p->p_flag & SSYS))
                return;

        /*
         * Regardless of origin or directedness,
         * SIGKILL kills all lwps in the process immediately
         * and jobcontrol signals affect all lwps in the process.
         */
        if (sig == SIGKILL) {
                p->p_flag |= SKILLED | (ext ? SEXTKILLED : 0);
                t = NULL;
        } else if (sig == SIGCONT) {
                /*
                 * The SSCONT flag will remain set until a stopping
                 * signal comes in (below).  This is harmless.
                 */
                p->p_flag |= SSCONT;
                sigdelq(p, NULL, SIGSTOP);
                sigdelq(p, NULL, SIGTSTP);
                sigdelq(p, NULL, SIGTTOU);
                sigdelq(p, NULL, SIGTTIN);
                sigdiffset(&p->p_sig, &stopdefault);
                sigdiffset(&p->p_extsig, &stopdefault);
                p->p_stopsig = 0;
                if ((tt = p->p_tlist) != NULL) {
                        do {
                                sigdelq(p, tt, SIGSTOP);
                                sigdelq(p, tt, SIGTSTP);
                                sigdelq(p, tt, SIGTTOU);
                                sigdelq(p, tt, SIGTTIN);
                                sigdiffset(&tt->t_sig, &stopdefault);
                                sigdiffset(&tt->t_extsig, &stopdefault);
                        } while ((tt = tt->t_forw) != p->p_tlist);
                }
                if ((tt = p->p_tlist) != NULL) {
                        do {
                                thread_lock(tt);
                                if (tt->t_state == TS_STOPPED &&
                                    tt->t_whystop == PR_JOBCONTROL) {
                                        tt->t_schedflag |= TS_XSTART;
                                        setrun_locked(tt);
                                }
                                thread_unlock(tt);
                        } while ((tt = tt->t_forw) != p->p_tlist);
                }
        } else if (sigismember(&stopdefault, sig)) {
                /*
                 * This test has a race condition which we can't fix:
                 * By the time the stopping signal is received by
                 * the target process/thread, the signal handler
                 * and/or the detached state might have changed.
                 */
                if (PTOU(p)->u_signal[sig-1] == SIG_DFL &&
                    (sig == SIGSTOP || !p->p_pgidp->pid_pgorphaned))
                        p->p_flag &= ~SSCONT;
                sigdelq(p, NULL, SIGCONT);
                sigdelset(&p->p_sig, SIGCONT);
                sigdelset(&p->p_extsig, SIGCONT);
                if ((tt = p->p_tlist) != NULL) {
                        do {
                                sigdelq(p, tt, SIGCONT);
                                sigdelset(&tt->t_sig, SIGCONT);
                                sigdelset(&tt->t_extsig, SIGCONT);
                        } while ((tt = tt->t_forw) != p->p_tlist);
                }
        }

        if (sig_discardable(p, sig)) {
                DTRACE_PROC3(signal__discard, kthread_t *, p->p_tlist,
                    proc_t *, p, int, sig);
                return;
        }

        if (t != NULL) {
                /*
                 * This is a directed signal, wake up the lwp.
                 */
                sigaddset(&t->t_sig, sig);
                if (ext)
                        sigaddset(&t->t_extsig, sig);
                thread_lock(t);
                (void) eat_signal(t, sig);
                thread_unlock(t);
                DTRACE_PROC2(signal__send, kthread_t *, t, int, sig);
                if (p->p_sigfd != NULL && ((sigfd_proc_state_t *)
                    (p->p_sigfd))->sigfd_pollwake_cb != NULL)
                        (*((sigfd_proc_state_t *)(p->p_sigfd))->
                            sigfd_pollwake_cb)(p, sig);

        } else if ((tt = p->p_tlist) != NULL) {
                /*
                 * Make sure that some lwp that already exists
                 * in the process fields the signal soon.
                 * Wake up an interruptibly sleeping lwp if necessary.
                 * For SIGKILL make all of the lwps see the signal;
                 * This is needed to guarantee a sure kill for processes
                 * with a mix of realtime and non-realtime threads.
                 */
                int su = 0;

                sigaddset(&p->p_sig, sig);
                if (ext)
                        sigaddset(&p->p_extsig, sig);
                do {
                        thread_lock(tt);
                        if (eat_signal(tt, sig) && sig != SIGKILL) {
                                thread_unlock(tt);
                                break;
                        }
                        if (SUSPENDED(tt))
                                su++;
                        thread_unlock(tt);
                } while ((tt = tt->t_forw) != p->p_tlist);
                /*
                 * If the process is deadlocked, make somebody run and die.
                 */
                if (sig == SIGKILL && p->p_stat != SIDL &&
                    p->p_lwprcnt == 0 && p->p_lwpcnt == su &&
                    !(p->p_proc_flag & P_PR_LOCK)) {
                        thread_lock(tt);
                        p->p_lwprcnt++;
                        tt->t_schedflag |= TS_CSTART;
                        setrun_locked(tt);
                        thread_unlock(tt);
                }

                DTRACE_PROC2(signal__send, kthread_t *, tt, int, sig);
                if (p->p_sigfd != NULL && ((sigfd_proc_state_t *)
                    (p->p_sigfd))->sigfd_pollwake_cb != NULL)
                        (*((sigfd_proc_state_t *)(p->p_sigfd))->
                            sigfd_pollwake_cb)(p, sig);
        }
}

static int
isjobstop(int sig)
{
        proc_t *p = ttoproc(curthread);

        ASSERT(MUTEX_HELD(&p->p_lock));

        if (PTOU(curproc)->u_signal[sig-1] == SIG_DFL &&
            sigismember(&stopdefault, sig)) {
                /*
                 * If SIGCONT has been posted since we promoted this signal
                 * from pending to current, then don't do a jobcontrol stop.
                 */
                if (!(p->p_flag & SSCONT) &&
                    (sig == SIGSTOP || !p->p_pgidp->pid_pgorphaned) &&
                    curthread != p->p_agenttp) {
                        sigqueue_t *sqp;

                        stop(PR_JOBCONTROL, sig);
                        mutex_exit(&p->p_lock);
                        sqp = kmem_zalloc(sizeof (sigqueue_t), KM_SLEEP);
                        mutex_enter(&pidlock);
                        /*
                         * Only the first lwp to continue notifies the parent.
                         */
                        if (p->p_pidflag & CLDCONT)
                                siginfofree(sqp);
                        else {
                                p->p_pidflag |= CLDCONT;
                                p->p_wcode = CLD_CONTINUED;
                                p->p_wdata = SIGCONT;
                                sigcld(p, sqp);
                        }
                        mutex_exit(&pidlock);
                        mutex_enter(&p->p_lock);
                }
                return (1);
        }
        return (0);
}

/*
 * Returns true if the current process has a signal to process, and
 * the signal is not held.  The signal to process is put in p_cursig.
 * This is asked at least once each time a process enters the system
 * (though this can usually be done without actually calling issig by
 * checking the pending signal masks).  A signal does not do anything
 * directly to a process; it sets a flag that asks the process to do
 * something to itself.
 *
 * The "why" argument indicates the allowable side-effects of the call:
 *
 * FORREAL:  Extract the next pending signal from p_sig into p_cursig;
 * stop the process if a stop has been requested or if a traced signal
 * is pending.
 *
 * JUSTLOOKING:  Don't stop the process, just indicate whether or not
 * a signal might be pending (FORREAL is needed to tell for sure).
 *
 * XXX: Changes to the logic in these routines should be propagated
 * to lm_sigispending().  See bug 1201594.
 */

static int issig_forreal(void);
static int issig_justlooking(void);

int
issig(int why)
{
        ASSERT(why == FORREAL || why == JUSTLOOKING);

        return ((why == FORREAL)? issig_forreal() : issig_justlooking());
}


static int
issig_justlooking(void)
{
        kthread_t *t = curthread;
        klwp_t *lwp = ttolwp(t);
        proc_t *p = ttoproc(t);
        k_sigset_t set;

        /*
         * This function answers the question:
         * "Is there any reason to call issig_forreal()?"
         *
         * We have to answer the question w/o grabbing any locks
         * because we are (most likely) being called after we
         * put ourselves on the sleep queue.
         */

        if (t->t_dtrace_stop | t->t_dtrace_sig)
                return (1);

        /*
         * Another piece of complexity in this process.  When single-stepping a
         * process, we don't want an intervening signal or TP_PAUSE request to
         * suspend the current thread.  Otherwise, the controlling process will
         * hang beacuse we will be stopped with TS_PSTART set in t_schedflag.
         * We will trigger any remaining signals when we re-enter the kernel on
         * the single step trap.
         */
        if (lwp->lwp_pcb.pcb_flags & NORMAL_STEP)
                return (0);

        if ((lwp->lwp_asleep && MUSTRETURN(p, t)) ||
            (p->p_flag & (SEXITLWPS|SKILLED)) ||
            (lwp->lwp_nostop == 0 &&
            (p->p_stopsig | (p->p_flag & (SHOLDFORK1|SHOLDWATCH)) |
            (t->t_proc_flag &
            (TP_PRSTOP|TP_HOLDLWP|TP_CHKPT|TP_PAUSE)))) ||
            lwp->lwp_cursig)
                return (1);

        if (p->p_flag & SVFWAIT)
                return (0);
        set = p->p_sig;
        sigorset(&set, &t->t_sig);
        if (schedctl_sigblock(t))       /* all blockable signals blocked */
                sigandset(&set, &cantmask);
        else
                sigdiffset(&set, &t->t_hold);
        if (p->p_flag & SVFORK)
                sigdiffset(&set, &holdvfork);

        if (!sigisempty(&set)) {
                int sig;

                for (sig = 1; sig < NSIG; sig++) {
                        if (sigismember(&set, sig) &&
                            (tracing(p, sig) ||
                            sigismember(&t->t_sigwait, sig) ||
                            !sigismember(&p->p_ignore, sig))) {
                                /*
                                 * Don't promote a signal that will stop
                                 * the process when lwp_nostop is set.
                                 */
                                if (!lwp->lwp_nostop ||
                                    PTOU(p)->u_signal[sig-1] != SIG_DFL ||
                                    !sigismember(&stopdefault, sig))
                                        return (1);
                        }
                }
        }

        return (0);
}

static int
issig_forreal(void)
{
        int sig = 0, ext = 0;
        kthread_t *t = curthread;
        klwp_t *lwp = ttolwp(t);
        proc_t *p = ttoproc(t);
        int toproc = 0;
        int sigcld_found = 0;
        int nostop_break = 0;

        ASSERT(t->t_state == TS_ONPROC);

        mutex_enter(&p->p_lock);
        schedctl_finish_sigblock(t);

        if (t->t_dtrace_stop | t->t_dtrace_sig) {
                if (t->t_dtrace_stop) {
                        /*
                         * If DTrace's "stop" action has been invoked on us,
                         * set TP_PRSTOP.
                         */
                        t->t_proc_flag |= TP_PRSTOP;
                }

                if (t->t_dtrace_sig != 0) {
                        k_siginfo_t info;

                        /*
                         * Post the signal generated as the result of
                         * DTrace's "raise" action as a normal signal before
                         * the full-fledged signal checking begins.
                         */
                        bzero(&info, sizeof (info));
                        info.si_signo = t->t_dtrace_sig;
                        info.si_code = SI_DTRACE;

                        sigaddq(p, NULL, &info, KM_NOSLEEP);

                        t->t_dtrace_sig = 0;
                }
        }

        for (;;) {
                if (p->p_flag & (SEXITLWPS|SKILLED)) {
                        lwp->lwp_cursig = sig = SIGKILL;
                        lwp->lwp_extsig = ext = (p->p_flag & SEXTKILLED) != 0;
                        t->t_sig_check = 1;
                        break;
                }

                /*
                 * Another piece of complexity in this process.  When
                 * single-stepping a process, we don't want an intervening
                 * signal or TP_PAUSE request to suspend the current thread.
                 * Otherwise, the controlling process will hang beacuse we will
                 * be stopped with TS_PSTART set in t_schedflag.  We will
                 * trigger any remaining signals when we re-enter the kernel on
                 * the single step trap.
                 */
                if (lwp->lwp_pcb.pcb_flags & NORMAL_STEP) {
                        sig = 0;
                        break;
                }

                /*
                 * Hold the lwp here for watchpoint manipulation.
                 */
                if ((t->t_proc_flag & TP_PAUSE) && !lwp->lwp_nostop) {
                        stop(PR_SUSPENDED, SUSPEND_PAUSE);
                        continue;
                }

                if (lwp->lwp_asleep && MUSTRETURN(p, t)) {
                        if ((sig = lwp->lwp_cursig) != 0) {
                                /*
                                 * Make sure we call ISSIG() in post_syscall()
                                 * to re-validate this current signal.
                                 */
                                t->t_sig_check = 1;
                        }
                        break;
                }

                /*
                 * If the request is PR_CHECKPOINT, ignore the rest of signals
                 * or requests.  Honor other stop requests or signals later.
                 * Go back to top of loop here to check if an exit or hold
                 * event has occurred while stopped.
                 */
                if ((t->t_proc_flag & TP_CHKPT) && !lwp->lwp_nostop) {
                        stop(PR_CHECKPOINT, 0);
                        continue;
                }

                /*
                 * Honor SHOLDFORK1, SHOLDWATCH, and TP_HOLDLWP before dealing
                 * with signals or /proc.  Another lwp is executing fork1(),
                 * or is undergoing watchpoint activity (remapping a page),
                 * or is executing lwp_suspend() on this lwp.
                 * Again, go back to top of loop to check if an exit
                 * or hold event has occurred while stopped.
                 */
                if (((p->p_flag & (SHOLDFORK1|SHOLDWATCH)) ||
                    (t->t_proc_flag & TP_HOLDLWP)) && !lwp->lwp_nostop) {
                        stop(PR_SUSPENDED, SUSPEND_NORMAL);
                        continue;
                }

                /*
                 * Honor requested stop before dealing with the
                 * current signal; a debugger may change it.
                 * Do not want to go back to loop here since this is a special
                 * stop that means: make incremental progress before the next
                 * stop. The danger is that returning to top of loop would most
                 * likely drop the thread right back here to stop soon after it
                 * was continued, violating the incremental progress request.
                 */
                if ((t->t_proc_flag & TP_PRSTOP) && !lwp->lwp_nostop)
                        stop(PR_REQUESTED, 0);

                /*
                 * If a debugger wants us to take a signal it will have
                 * left it in lwp->lwp_cursig.  If lwp_cursig has been cleared
                 * or if it's being ignored, we continue on looking for another
                 * signal.  Otherwise we return the specified signal, provided
                 * it's not a signal that causes a job control stop.
                 *
                 * When stopped on PR_JOBCONTROL, there is no current
                 * signal; we cancel lwp->lwp_cursig temporarily before
                 * calling isjobstop().  The current signal may be reset
                 * by a debugger while we are stopped in isjobstop().
                 *
                 * If the current thread is accepting the signal
                 * (via sigwait(), sigwaitinfo(), or sigtimedwait()),
                 * we allow the signal to be accepted, even if it is
                 * being ignored, and without causing a job control stop.
                 */
                if ((sig = lwp->lwp_cursig) != 0) {
                        ext = lwp->lwp_extsig;
                        lwp->lwp_cursig = 0;
                        lwp->lwp_extsig = 0;
                        if (sigismember(&t->t_sigwait, sig) ||
                            (!sigismember(&p->p_ignore, sig) &&
                            !isjobstop(sig))) {
                                if (p->p_flag & (SEXITLWPS|SKILLED)) {
                                        sig = SIGKILL;
                                        ext = (p->p_flag & SEXTKILLED) != 0;
                                }
                                lwp->lwp_cursig = (uchar_t)sig;
                                lwp->lwp_extsig = (uchar_t)ext;
                                break;
                        }
                        /*
                         * The signal is being ignored or it caused a
                         * job-control stop.  If another current signal
                         * has not been established, return the current
                         * siginfo, if any, to the memory manager.
                         */
                        if (lwp->lwp_cursig == 0 && lwp->lwp_curinfo != NULL) {
                                siginfofree(lwp->lwp_curinfo);
                                lwp->lwp_curinfo = NULL;
                        }
                        /*
                         * Loop around again in case we were stopped
                         * on a job control signal and a /proc stop
                         * request was posted or another current signal
                         * was established while we were stopped.
                         */
                        continue;
                }

                if (p->p_stopsig && !lwp->lwp_nostop &&
                    curthread != p->p_agenttp) {
                        /*
                         * Some lwp in the process has already stopped
                         * showing PR_JOBCONTROL.  This is a stop in
                         * sympathy with the other lwp, even if this
                         * lwp is blocking the stopping signal.
                         */
                        stop(PR_JOBCONTROL, p->p_stopsig);
                        continue;
                }

                /*
                 * Loop on the pending signals until we find a
                 * non-held signal that is traced or not ignored.
                 * First check the signals pending for the lwp,
                 * then the signals pending for the process as a whole.
                 */
                for (;;) {
                        if ((sig = fsig(&t->t_sig, t)) != 0) {
                                toproc = 0;
                                if (tracing(p, sig) ||
                                    sigismember(&t->t_sigwait, sig) ||
                                    !sigismember(&p->p_ignore, sig)) {
                                        if (sigismember(&t->t_extsig, sig))
                                                ext = 1;
                                        break;
                                }
                                sigdelset(&t->t_sig, sig);
                                sigdelset(&t->t_extsig, sig);
                                sigdelq(p, t, sig);
                        } else if ((sig = fsig(&p->p_sig, t)) != 0) {
                                if (sig == SIGCLD)
                                        sigcld_found = 1;
                                toproc = 1;
                                if (tracing(p, sig) ||
                                    sigismember(&t->t_sigwait, sig) ||
                                    !sigismember(&p->p_ignore, sig)) {
                                        if (sigismember(&p->p_extsig, sig))
                                                ext = 1;
                                        break;
                                }
                                sigdelset(&p->p_sig, sig);
                                sigdelset(&p->p_extsig, sig);
                                sigdelq(p, NULL, sig);
                        } else {
                                /* no signal was found */
                                break;
                        }
                }

                if (sig == 0) { /* no signal was found */
                        if (p->p_flag & (SEXITLWPS|SKILLED)) {
                                lwp->lwp_cursig = SIGKILL;
                                sig = SIGKILL;
                                ext = (p->p_flag & SEXTKILLED) != 0;
                        }
                        break;
                }

                /*
                 * If we have been informed not to stop (i.e., we are being
                 * called from within a network operation), then don't promote
                 * the signal at this time, just return the signal number.
                 * We will call issig() again later when it is safe.
                 *
                 * fsig() does not return a jobcontrol stopping signal
                 * with a default action of stopping the process if
                 * lwp_nostop is set, so we won't be causing a bogus
                 * EINTR by this action.  (Such a signal is eaten by
                 * isjobstop() when we loop around to do final checks.)
                 */
                if (lwp->lwp_nostop) {
                        nostop_break = 1;
                        break;
                }

                /*
                 * Promote the signal from pending to current.
                 *
                 * Note that sigdeq() will set lwp->lwp_curinfo to NULL
                 * if no siginfo_t exists for this signal.
                 */
                lwp->lwp_cursig = (uchar_t)sig;
                lwp->lwp_extsig = (uchar_t)ext;
                t->t_sig_check = 1;     /* so post_syscall will see signal */
                ASSERT(lwp->lwp_curinfo == NULL);
                sigdeq(p, toproc ? NULL : t, sig, &lwp->lwp_curinfo);

                if (tracing(p, sig))
                        stop(PR_SIGNALLED, sig);

                /*
                 * Loop around to check for requested stop before
                 * performing the usual current-signal actions.
                 */
        }

        mutex_exit(&p->p_lock);

        /*
         * If SIGCLD was dequeued from the process's signal queue,
         * search for other pending SIGCLD's from the list of children.
         */
        if (sigcld_found)
                sigcld_repost();

        if (sig != 0)
                (void) undo_watch_step(NULL);

        /*
         * If we have been blocked since the p_lock was dropped off
         * above, then this promoted signal might have been handled
         * already when we were on the way back from sleep queue, so
         * just ignore it.
         * If we have been informed not to stop, just return the signal
         * number. Also see comments above.
         */
        if (!nostop_break) {
                sig = lwp->lwp_cursig;
        }

        return (sig != 0);
}

/*
 * Return true if the process is currently stopped showing PR_JOBCONTROL.
 * This is true only if all of the process's lwp's are so stopped.
 * If this is asked by one of the lwps in the process, exclude that lwp.
 */
int
jobstopped(proc_t *p)
{
        kthread_t *t;

        ASSERT(MUTEX_HELD(&p->p_lock));

        if ((t = p->p_tlist) == NULL)
                return (0);

        do {
                thread_lock(t);
                /* ignore current, zombie and suspended lwps in the test */
                if (!(t == curthread || t->t_state == TS_ZOMB ||
                    SUSPENDED(t)) &&
                    (t->t_state != TS_STOPPED ||
                    t->t_whystop != PR_JOBCONTROL)) {
                        thread_unlock(t);
                        return (0);
                }
                thread_unlock(t);
        } while ((t = t->t_forw) != p->p_tlist);

        return (1);
}

/*
 * Put ourself (curthread) into the stopped state and notify tracers.
 */
void
stop(int why, int what)
{
        kthread_t       *t = curthread;
        proc_t          *p = ttoproc(t);
        klwp_t          *lwp = ttolwp(t);
        kthread_t       *tx;
        lwpent_t        *lep;
        int             procstop;
        int             flags = TS_ALLSTART;
        hrtime_t        stoptime;

        /*
         * Can't stop a system process.
         */
        if (p == NULL || lwp == NULL || (p->p_flag & SSYS) || p->p_as == &kas)
                return;

        ASSERT(MUTEX_HELD(&p->p_lock));

        if (why != PR_SUSPENDED && why != PR_CHECKPOINT) {
                /*
                 * Don't stop an lwp with SIGKILL pending.
                 * Don't stop if the process or lwp is exiting.
                 */
                if (lwp->lwp_cursig == SIGKILL ||
                    sigismember(&t->t_sig, SIGKILL) ||
                    sigismember(&p->p_sig, SIGKILL) ||
                    (t->t_proc_flag & TP_LWPEXIT) ||
                    (p->p_flag & (SEXITLWPS|SKILLED))) {
                        p->p_stopsig = 0;
                        t->t_proc_flag &= ~(TP_PRSTOP|TP_PRVSTOP);
                        return;
                }
        }

        /*
         * Make sure we don't deadlock on a recursive call to prstop().
         * prstop() sets the lwp_nostop flag.
         */
        if (lwp->lwp_nostop)
                return;

        /*
         * Make sure the lwp is in an orderly state for inspection
         * by a debugger through /proc or for dumping via core().
         */
        schedctl_finish_sigblock(t);
        t->t_proc_flag |= TP_STOPPING;  /* must set before dropping p_lock */
        mutex_exit(&p->p_lock);
        stoptime = gethrtime();
        prstop(why, what);
        (void) undo_watch_step(NULL);
        mutex_enter(&p->p_lock);
        ASSERT(t->t_state == TS_ONPROC);

        switch (why) {
        case PR_CHECKPOINT:
                /*
                 * The situation may have changed since we dropped
                 * and reacquired p->p_lock. Double-check now
                 * whether we should stop or not.
                 */
                if (!(t->t_proc_flag & TP_CHKPT)) {
                        t->t_proc_flag &= ~TP_STOPPING;
                        return;
                }
                t->t_proc_flag &= ~TP_CHKPT;
                flags &= ~TS_RESUME;
                break;

        case PR_JOBCONTROL:
                ASSERT(what == SIGSTOP || what == SIGTSTP ||
                    what == SIGTTIN || what == SIGTTOU);
                flags &= ~TS_XSTART;
                break;

        case PR_SUSPENDED:
                ASSERT(what == SUSPEND_NORMAL || what == SUSPEND_PAUSE);
                /*
                 * The situation may have changed since we dropped
                 * and reacquired p->p_lock.  Double-check now
                 * whether we should stop or not.
                 */
                if (what == SUSPEND_PAUSE) {
                        if (!(t->t_proc_flag & TP_PAUSE)) {
                                t->t_proc_flag &= ~TP_STOPPING;
                                return;
                        }
                        flags &= ~TS_UNPAUSE;
                } else {
                        if (!((t->t_proc_flag & TP_HOLDLWP) ||
                            (p->p_flag & (SHOLDFORK|SHOLDFORK1|SHOLDWATCH)))) {
                                t->t_proc_flag &= ~TP_STOPPING;
                                return;
                        }
                        /*
                         * If SHOLDFORK is in effect and we are stopping
                         * while asleep (not at the top of the stack),
                         * we return now to allow the hold to take effect
                         * when we reach the top of the kernel stack.
                         */
                        if (lwp->lwp_asleep && (p->p_flag & SHOLDFORK)) {
                                t->t_proc_flag &= ~TP_STOPPING;
                                return;
                        }
                        flags &= ~TS_CSTART;
                }
                break;

        default:        /* /proc stop */
                flags &= ~TS_PSTART;
                /*
                 * Do synchronous stop unless the async-stop flag is set.
                 * If why is PR_REQUESTED and t->t_dtrace_stop flag is set,
                 * then no debugger is present and we also do synchronous stop.
                 */
                if ((why != PR_REQUESTED || t->t_dtrace_stop) &&
                    !(p->p_proc_flag & P_PR_ASYNC)) {
                        int notify;

                        for (tx = t->t_forw; tx != t; tx = tx->t_forw) {
                                notify = 0;
                                thread_lock(tx);
                                if (ISTOPPED(tx) ||
                                    (tx->t_proc_flag & TP_PRSTOP)) {
                                        thread_unlock(tx);
                                        continue;
                                }
                                tx->t_proc_flag |= TP_PRSTOP;
                                tx->t_sig_check = 1;
                                if (tx->t_state == TS_SLEEP &&
                                    (tx->t_flag & T_WAKEABLE)) {
                                        /*
                                         * Don't actually wake it up if it's
                                         * in one of the lwp_*() syscalls.
                                         * Mark it virtually stopped and
                                         * notify /proc waiters (below).
                                         */
                                        if (tx->t_wchan0 == NULL)
                                                setrun_locked(tx);
                                        else {
                                                tx->t_proc_flag |= TP_PRVSTOP;
                                                tx->t_stoptime = stoptime;
                                                notify = 1;
                                        }
                                }

                                /* Move waiting thread to run queue */
                                if (ISWAITING(tx))
                                        setrun_locked(tx);

                                /*
                                 * force the thread into the kernel
                                 * if it is not already there.
                                 */
                                if (tx->t_state == TS_ONPROC &&
                                    tx->t_cpu != CPU)
                                        poke_cpu(tx->t_cpu->cpu_id);
                                thread_unlock(tx);
                                lep = p->p_lwpdir[tx->t_dslot].ld_entry;
                                if (notify && lep->le_trace)
                                        prnotify(lep->le_trace);
                        }
                        /*
                         * We do this just in case one of the threads we asked
                         * to stop is in holdlwps() (called from cfork()) or
                         * lwp_suspend().
                         */
                        cv_broadcast(&p->p_holdlwps);
                }
                break;
        }

        t->t_stoptime = stoptime;

        if (why == PR_JOBCONTROL || (why == PR_SUSPENDED && p->p_stopsig)) {
                /*
                 * Determine if the whole process is jobstopped.
                 */
                if (jobstopped(p)) {
                        sigqueue_t *sqp;
                        int sig;

                        if ((sig = p->p_stopsig) == 0)
                                p->p_stopsig = (uchar_t)(sig = what);
                        mutex_exit(&p->p_lock);
                        sqp = kmem_zalloc(sizeof (sigqueue_t), KM_SLEEP);
                        mutex_enter(&pidlock);
                        /*
                         * The last lwp to stop notifies the parent.
                         * Turn off the CLDCONT flag now so the first
                         * lwp to continue knows what to do.
                         */
                        p->p_pidflag &= ~CLDCONT;
                        p->p_wcode = CLD_STOPPED;
                        p->p_wdata = sig;
                        sigcld(p, sqp);
                        /*
                         * Grab p->p_lock before releasing pidlock so the
                         * parent and the child don't have a race condition.
                         */
                        mutex_enter(&p->p_lock);
                        mutex_exit(&pidlock);
                        p->p_stopsig = 0;
                } else if (why == PR_JOBCONTROL && p->p_stopsig == 0) {
                        /*
                         * Set p->p_stopsig and wake up sleeping lwps
                         * so they will stop in sympathy with this lwp.
                         */
                        p->p_stopsig = (uchar_t)what;
                        pokelwps(p);
                        /*
                         * We do this just in case one of the threads we asked
                         * to stop is in holdlwps() (called from cfork()) or
                         * lwp_suspend().
                         */
                        cv_broadcast(&p->p_holdlwps);
                }
        }

        if (why != PR_JOBCONTROL && why != PR_CHECKPOINT) {
                /*
                 * Do process-level notification when all lwps are
                 * either stopped on events of interest to /proc
                 * or are stopped showing PR_SUSPENDED or are zombies.
                 */
                procstop = 1;
                for (tx = t->t_forw; procstop && tx != t; tx = tx->t_forw) {
                        if (VSTOPPED(tx))
                                continue;
                        thread_lock(tx);
                        switch (tx->t_state) {
                        case TS_ZOMB:
                                break;
                        case TS_STOPPED:
                                /* neither ISTOPPED nor SUSPENDED? */
                                if ((tx->t_schedflag &
                                    (TS_CSTART | TS_UNPAUSE | TS_PSTART)) ==
                                    (TS_CSTART | TS_UNPAUSE | TS_PSTART))
                                        procstop = 0;
                                break;
                        case TS_SLEEP:
                                /* not paused for watchpoints? */
                                if (!(tx->t_flag & T_WAKEABLE) ||
                                    tx->t_wchan0 == NULL ||
                                    !(tx->t_proc_flag & TP_PAUSE))
                                        procstop = 0;
                                break;
                        default:
                                procstop = 0;
                                break;
                        }
                        thread_unlock(tx);
                }
                if (procstop) {
                        /* there must not be any remapped watched pages now */
                        ASSERT(p->p_mapcnt == 0);
                        if (p->p_proc_flag & P_PR_PTRACE) {
                                /* ptrace() compatibility */
                                mutex_exit(&p->p_lock);
                                mutex_enter(&pidlock);
                                p->p_wcode = CLD_TRAPPED;
                                p->p_wdata = (why == PR_SIGNALLED)?
                                    what : SIGTRAP;
                                cv_broadcast(&p->p_parent->p_cv);
                                /*
                                 * Grab p->p_lock before releasing pidlock so
                                 * parent and child don't have a race condition.
                                 */
                                mutex_enter(&p->p_lock);
                                mutex_exit(&pidlock);
                        }
                        if (p->p_trace)                 /* /proc */
                                prnotify(p->p_trace);
                        cv_broadcast(&pr_pid_cv[p->p_slot]); /* pauselwps() */
                        cv_broadcast(&p->p_holdlwps);   /* holdwatch() */
                }
                if (why != PR_SUSPENDED) {
                        lep = p->p_lwpdir[t->t_dslot].ld_entry;
                        if (lep->le_trace)              /* /proc */
                                prnotify(lep->le_trace);
                        /*
                         * Special notification for creation of the agent lwp.
                         */
                        if (t == p->p_agenttp &&
                            (t->t_proc_flag & TP_PRSTOP) &&
                            p->p_trace)
                                prnotify(p->p_trace);
                        /*
                         * The situation may have changed since we dropped
                         * and reacquired p->p_lock. Double-check now
                         * whether we should stop or not.
                         */
                        if (!(t->t_proc_flag & TP_STOPPING)) {
                                if (t->t_proc_flag & TP_PRSTOP)
                                        t->t_proc_flag |= TP_STOPPING;
                        }
                        t->t_proc_flag &= ~(TP_PRSTOP|TP_PRVSTOP);
                        prnostep(lwp);
                }
        }

        if (why == PR_SUSPENDED) {

                /*
                 * We always broadcast in the case of SUSPEND_PAUSE.  This is
                 * because checks for TP_PAUSE take precedence over checks for
                 * SHOLDWATCH.  If a thread is trying to stop because of
                 * SUSPEND_PAUSE and tries to do a holdwatch(), it will be
                 * waiting for the rest of the threads to enter a stopped state.
                 * If we are stopping for a SUSPEND_PAUSE, we may be the last
                 * lwp and not know it, so broadcast just in case.
                 */
                if (what == SUSPEND_PAUSE ||
                    --p->p_lwprcnt == 0 || (t->t_proc_flag & TP_HOLDLWP))
                        cv_broadcast(&p->p_holdlwps);

        }

        /*
         * Need to do this here (rather than after the thread is officially
         * stopped) because we can't call mutex_enter from a stopped thread.
         */
        if (why == PR_CHECKPOINT)
                del_one_utstop();

        thread_lock(t);
        ASSERT((t->t_schedflag & TS_ALLSTART) == 0);
        t->t_schedflag |= flags;
        t->t_whystop = (short)why;
        t->t_whatstop = (short)what;
        CL_STOP(t, why, what);
        (void) new_mstate(t, LMS_STOPPED);
        thread_stop(t);                 /* set stop state and drop lock */

        if (why != PR_SUSPENDED && why != PR_CHECKPOINT) {
                /*
                 * We may have gotten a SIGKILL or a SIGCONT when
                 * we released p->p_lock; make one last check.
                 * Also check for a /proc run-on-last-close.
                 */
                if (sigismember(&t->t_sig, SIGKILL) ||
                    sigismember(&p->p_sig, SIGKILL) ||
                    (t->t_proc_flag & TP_LWPEXIT) ||
                    (p->p_flag & (SEXITLWPS|SKILLED))) {
                        p->p_stopsig = 0;
                        thread_lock(t);
                        t->t_schedflag |= TS_XSTART | TS_PSTART;
                        setrun_locked(t);
                        thread_unlock_nopreempt(t);
                } else if (why == PR_JOBCONTROL) {
                        if (p->p_flag & SSCONT) {
                                /*
                                 * This resulted from a SIGCONT posted
                                 * while we were not holding p->p_lock.
                                 */
                                p->p_stopsig = 0;
                                thread_lock(t);
                                t->t_schedflag |= TS_XSTART;
                                setrun_locked(t);
                                thread_unlock_nopreempt(t);
                        }
                } else if (!(t->t_proc_flag & TP_STOPPING)) {
                        /*
                         * This resulted from a /proc run-on-last-close.
                         */
                        thread_lock(t);
                        t->t_schedflag |= TS_PSTART;
                        setrun_locked(t);
                        thread_unlock_nopreempt(t);
                }
        }

        t->t_proc_flag &= ~TP_STOPPING;
        mutex_exit(&p->p_lock);

        swtch();
        setallwatch();  /* reestablish any watchpoints set while stopped */
        mutex_enter(&p->p_lock);
        prbarrier(p);   /* barrier against /proc locking */
}

/* Interface for resetting user thread stop count. */
void
utstop_init(void)
{
        mutex_enter(&thread_stop_lock);
        num_utstop = 0;
        mutex_exit(&thread_stop_lock);
}

/* Interface for registering a user thread stop request. */
void
add_one_utstop(void)
{
        mutex_enter(&thread_stop_lock);
        num_utstop++;
        mutex_exit(&thread_stop_lock);
}

/* Interface for cancelling a user thread stop request */
void
del_one_utstop(void)
{
        mutex_enter(&thread_stop_lock);
        num_utstop--;
        if (num_utstop == 0)
                cv_broadcast(&utstop_cv);
        mutex_exit(&thread_stop_lock);
}

/* Interface to wait for all user threads to be stopped */
void
utstop_timedwait(clock_t ticks)
{
        mutex_enter(&thread_stop_lock);
        if (num_utstop > 0)
                (void) cv_reltimedwait(&utstop_cv, &thread_stop_lock, ticks,
                    TR_CLOCK_TICK);
        mutex_exit(&thread_stop_lock);
}

/*
 * Perform the action specified by the current signal.
 * The usual sequence is:
 *      if (issig())
 *              psig();
 * The signal bit has already been cleared by issig(),
 * the current signal number has been stored in lwp_cursig,
 * and the current siginfo is now referenced by lwp_curinfo.
 */
void
psig(void)
{
        kthread_t *t = curthread;
        proc_t *p = ttoproc(t);
        klwp_t *lwp = ttolwp(t);
        void (*func)();
        int sig, rc, code, ext;
        pid_t pid = -1;
        id_t ctid = 0;
        zoneid_t zoneid = -1;
        sigqueue_t *sqp = NULL;
        uint32_t auditing = AU_AUDITING();

        mutex_enter(&p->p_lock);
        schedctl_finish_sigblock(t);
        code = CLD_KILLED;

        if (p->p_flag & SEXITLWPS) {
                lwp_exit();
                return;                 /* not reached */
        }
        sig = lwp->lwp_cursig;
        ext = lwp->lwp_extsig;

        ASSERT(sig < NSIG);

        /*
         * Re-check lwp_cursig after we acquire p_lock.  Since p_lock was
         * dropped between issig() and psig(), a debugger may have cleared
         * lwp_cursig via /proc in the intervening window.
         */
        if (sig == 0) {
                if (lwp->lwp_curinfo) {
                        siginfofree(lwp->lwp_curinfo);
                        lwp->lwp_curinfo = NULL;
                }
                if (t->t_flag & T_TOMASK) {     /* sigsuspend or pollsys */
                        t->t_flag &= ~T_TOMASK;
                        t->t_hold = lwp->lwp_sigoldmask;
                }
                mutex_exit(&p->p_lock);
                return;
        }
        func = PTOU(curproc)->u_signal[sig-1];

        /*
         * The signal disposition could have changed since we promoted
         * this signal from pending to current (we dropped p->p_lock).
         * This can happen only in a multi-threaded process.
         */
        if (sigismember(&p->p_ignore, sig) ||
            (func == SIG_DFL && sigismember(&stopdefault, sig))) {
                lwp->lwp_cursig = 0;
                lwp->lwp_extsig = 0;
                if (lwp->lwp_curinfo) {
                        siginfofree(lwp->lwp_curinfo);
                        lwp->lwp_curinfo = NULL;
                }
                if (t->t_flag & T_TOMASK) {     /* sigsuspend or pollsys */
                        t->t_flag &= ~T_TOMASK;
                        t->t_hold = lwp->lwp_sigoldmask;
                }
                mutex_exit(&p->p_lock);
                return;
        }

        /*
         * We check lwp_curinfo first since pr_setsig can actually
         * stuff a sigqueue_t there for SIGKILL.
         */
        if (lwp->lwp_curinfo) {
                sqp = lwp->lwp_curinfo;
        } else if (sig == SIGKILL && p->p_killsqp) {
                sqp = p->p_killsqp;
        }

        if (sqp != NULL) {
                if (SI_FROMUSER(&sqp->sq_info)) {
                        pid = sqp->sq_info.si_pid;
                        ctid = sqp->sq_info.si_ctid;
                        zoneid = sqp->sq_info.si_zoneid;
                }
                /*
                 * If we have a sigqueue_t, its sq_external value
                 * trumps the lwp_extsig value.  It is theoretically
                 * possible to make lwp_extsig reflect reality, but it
                 * would unnecessarily complicate things elsewhere.
                 */
                ext = sqp->sq_external;
        }

        if (func == SIG_DFL) {
                mutex_exit(&p->p_lock);
                DTRACE_PROC3(signal__handle, int, sig, k_siginfo_t *,
                    NULL, void (*)(void), func);
        } else {
                k_siginfo_t *sip = NULL;

                /*
                 * If DTrace user-land tracing is active, give DTrace a
                 * chance to defer the signal until after tracing is
                 * complete.
                 */
                if (t->t_dtrace_on && dtrace_safe_defer_signal()) {
                        mutex_exit(&p->p_lock);
                        return;
                }

                /*
                 * save siginfo pointer here, in case the
                 * the signal's reset bit is on
                 *
                 * The presence of a current signal prevents paging
                 * from succeeding over a network.  We copy the current
                 * signal information to the side and cancel the current
                 * signal so that sendsig() will succeed.
                 */
                if (sigismember(&p->p_siginfo, sig)) {
                        sip = &lwp->lwp_siginfo;
                        if (sqp) {
                                bcopy(&sqp->sq_info, sip, sizeof (*sip));
                                /*
                                 * If we were interrupted out of a system call
                                 * due to pthread_cancel(), inform libc.
                                 */
                                if (sig == SIGCANCEL &&
                                    sip->si_code == SI_LWP &&
                                    t->t_sysnum != 0)
                                        schedctl_cancel_eintr();
                        } else if (sig == SIGPROF && sip->si_signo == SIGPROF &&
                            t->t_rprof != NULL && t->t_rprof->rp_anystate) {
                                /* EMPTY */;
                        } else {
                                bzero(sip, sizeof (*sip));
                                sip->si_signo = sig;
                                sip->si_code = SI_NOINFO;
                        }
                }

                if (t->t_flag & T_TOMASK)
                        t->t_flag &= ~T_TOMASK;
                else
                        lwp->lwp_sigoldmask = t->t_hold;
                sigorset(&t->t_hold, &PTOU(curproc)->u_sigmask[sig-1]);
                if (!sigismember(&PTOU(curproc)->u_signodefer, sig))
                        sigaddset(&t->t_hold, sig);
                if (sigismember(&PTOU(curproc)->u_sigresethand, sig))
                        setsigact(sig, SIG_DFL, &nullsmask, 0);

                DTRACE_PROC3(signal__handle, int, sig, k_siginfo_t *,
                    sip, void (*)(void), func);

                lwp->lwp_cursig = 0;
                lwp->lwp_extsig = 0;
                if (lwp->lwp_curinfo) {
                        /* p->p_killsqp is freed by freeproc */
                        siginfofree(lwp->lwp_curinfo);
                        lwp->lwp_curinfo = NULL;
                }
                mutex_exit(&p->p_lock);
                lwp->lwp_ru.nsignals++;

                if (p->p_model == DATAMODEL_NATIVE)
                        rc = sendsig(sig, sip, func);
#ifdef _SYSCALL32_IMPL
                else
                        rc = sendsig32(sig, sip, func);
#endif  /* _SYSCALL32_IMPL */
                if (rc)
                        return;
                sig = lwp->lwp_cursig = SIGSEGV;
                ext = 0;        /* lwp_extsig was set above */
                pid = -1;
                ctid = 0;
        }

        if (sigismember(&coredefault, sig)) {
                /*
                 * Terminate all LWPs but don't discard them.
                 * If another lwp beat us to the punch by calling exit(),
                 * evaporate now.
                 */
                proc_is_exiting(p);
                if (exitlwps(1) != 0) {
                        mutex_enter(&p->p_lock);
                        lwp_exit();
                }
                /* if we got a SIGKILL from anywhere, no core dump */
                if (p->p_flag & SKILLED) {
                        sig = SIGKILL;
                        ext = (p->p_flag & SEXTKILLED) != 0;
                } else {
                        if (auditing)           /* audit core dump */
                                audit_core_start(sig);
                        if (core(sig, ext) == 0)
                                code = CLD_DUMPED;
                        if (auditing)           /* audit core dump */
                                audit_core_finish(code);
                }
        }

        /*
         * Generate a contract event once if the process is killed
         * by a signal.
         */
        if (ext) {
                proc_is_exiting(p);
                if (exitlwps(0) != 0) {
                        mutex_enter(&p->p_lock);
                        lwp_exit();
                }
                contract_process_sig(p->p_ct_process, p, sig, pid, ctid,
                    zoneid);
        }

        exit(code, sig);
}

/*
 * Find next unheld signal in ssp for thread t.
 */
int
fsig(k_sigset_t *ssp, kthread_t *t)
{
        proc_t *p = ttoproc(t);
        user_t *up = PTOU(p);
        int i;
        k_sigset_t temp;

        ASSERT(MUTEX_HELD(&p->p_lock));

        /*
         * Don't promote any signals for the parent of a vfork()d
         * child that hasn't yet released the parent's memory.
         */
        if (p->p_flag & SVFWAIT)
                return (0);

        temp = *ssp;
        sigdiffset(&temp, &t->t_hold);

        /*
         * Don't promote stopping signals (except SIGSTOP) for a child
         * of vfork() that hasn't yet released the parent's memory.
         */
        if (p->p_flag & SVFORK)
                sigdiffset(&temp, &holdvfork);

        /*
         * Don't promote a signal that will stop
         * the process when lwp_nostop is set.
         */
        if (ttolwp(t)->lwp_nostop) {
                sigdelset(&temp, SIGSTOP);
                if (!p->p_pgidp->pid_pgorphaned) {
                        if (up->u_signal[SIGTSTP-1] == SIG_DFL)
                                sigdelset(&temp, SIGTSTP);
                        if (up->u_signal[SIGTTIN-1] == SIG_DFL)
                                sigdelset(&temp, SIGTTIN);
                        if (up->u_signal[SIGTTOU-1] == SIG_DFL)
                                sigdelset(&temp, SIGTTOU);
                }
        }

        /*
         * Choose SIGKILL and SIGPROF before all other pending signals.
         * The rest are promoted in signal number order.
         */
        if (sigismember(&temp, SIGKILL))
                return (SIGKILL);
        if (sigismember(&temp, SIGPROF))
                return (SIGPROF);

        for (i = 0; i < sizeof (temp) / sizeof (temp.__sigbits[0]); i++) {
                if (temp.__sigbits[i])
                        return ((i * NBBY * sizeof (temp.__sigbits[0])) +
                            lowbit(temp.__sigbits[i]));
        }

        return (0);
}

void
setsigact(int sig, void (*disp)(), const k_sigset_t *mask, int flags)
{
        proc_t *p = ttoproc(curthread);
        kthread_t *t;

        ASSERT(MUTEX_HELD(&p->p_lock));

        PTOU(curproc)->u_signal[sig - 1] = disp;

        /*
         * Honor the SA_SIGINFO flag if the signal is being caught.
         * Force the SA_SIGINFO flag if the signal is not being caught.
         * This is necessary to make sigqueue() and sigwaitinfo() work
         * properly together when the signal is set to default or is
         * being temporarily ignored.
         */
        if ((flags & SA_SIGINFO) || disp == SIG_DFL || disp == SIG_IGN)
                sigaddset(&p->p_siginfo, sig);
        else
                sigdelset(&p->p_siginfo, sig);

        if (disp != SIG_DFL && disp != SIG_IGN) {
                sigdelset(&p->p_ignore, sig);
                PTOU(curproc)->u_sigmask[sig - 1] = *mask;
                if (!sigismember(&cantreset, sig)) {
                        if (flags & SA_RESETHAND)
                                sigaddset(&PTOU(curproc)->u_sigresethand, sig);
                        else
                                sigdelset(&PTOU(curproc)->u_sigresethand, sig);
                }
                if (flags & SA_NODEFER)
                        sigaddset(&PTOU(curproc)->u_signodefer, sig);
                else
                        sigdelset(&PTOU(curproc)->u_signodefer, sig);
                if (flags & SA_RESTART)
                        sigaddset(&PTOU(curproc)->u_sigrestart, sig);
                else
                        sigdelset(&PTOU(curproc)->u_sigrestart, sig);
                if (flags & SA_ONSTACK)
                        sigaddset(&PTOU(curproc)->u_sigonstack, sig);
                else
                        sigdelset(&PTOU(curproc)->u_sigonstack, sig);
        } else if (disp == SIG_IGN ||
            (disp == SIG_DFL && sigismember(&ignoredefault, sig))) {
                /*
                 * Setting the signal action to SIG_IGN results in the
                 * discarding of all pending signals of that signal number.
                 * Setting the signal action to SIG_DFL does the same *only*
                 * if the signal's default behavior is to be ignored.
                 */
                sigaddset(&p->p_ignore, sig);
                sigdelset(&p->p_sig, sig);
                sigdelset(&p->p_extsig, sig);
                sigdelq(p, NULL, sig);
                t = p->p_tlist;
                do {
                        sigdelset(&t->t_sig, sig);
                        sigdelset(&t->t_extsig, sig);
                        sigdelq(p, t, sig);
                } while ((t = t->t_forw) != p->p_tlist);
        } else {
                /*
                 * The signal action is being set to SIG_DFL and the default
                 * behavior is to do something: make sure it is not ignored.
                 */
                sigdelset(&p->p_ignore, sig);
        }

        if (sig == SIGCLD) {
                if (flags & SA_NOCLDWAIT)
                        p->p_flag |= SNOWAIT;
                else
                        p->p_flag &= ~SNOWAIT;

                if (flags & SA_NOCLDSTOP)
                        p->p_flag &= ~SJCTL;
                else
                        p->p_flag |= SJCTL;

                if ((p->p_flag & SNOWAIT) || disp == SIG_IGN) {
                        proc_t *cp, *tp;

                        mutex_exit(&p->p_lock);
                        mutex_enter(&pidlock);
                        for (cp = p->p_child; cp != NULL; cp = tp) {
                                tp = cp->p_sibling;
                                if (cp->p_stat == SZOMB &&
                                    !(cp->p_pidflag & CLDWAITPID))
                                        freeproc(cp);
                        }
                        mutex_exit(&pidlock);
                        mutex_enter(&p->p_lock);
                }
        }
}

/*
 * Set all signal actions not already set to SIG_DFL or SIG_IGN to SIG_DFL.
 * Called from exec_common() for a process undergoing execve()
 * and from cfork() for a newly-created child of vfork().
 * In the vfork() case, 'p' is not the current process.
 * In both cases, there is only one thread in the process.
 */
void
sigdefault(proc_t *p)
{
        kthread_t *t = p->p_tlist;
        struct user *up = PTOU(p);
        int sig;

        ASSERT(MUTEX_HELD(&p->p_lock));

        for (sig = 1; sig < NSIG; sig++) {
                if (up->u_signal[sig - 1] != SIG_DFL &&
                    up->u_signal[sig - 1] != SIG_IGN) {
                        up->u_signal[sig - 1] = SIG_DFL;
                        sigemptyset(&up->u_sigmask[sig - 1]);
                        if (sigismember(&ignoredefault, sig)) {
                                sigdelq(p, NULL, sig);
                                sigdelq(p, t, sig);
                        }
                        if (sig == SIGCLD)
                                p->p_flag &= ~(SNOWAIT|SJCTL);
                }
        }
        sigorset(&p->p_ignore, &ignoredefault);
        sigfillset(&p->p_siginfo);
        sigdiffset(&p->p_siginfo, &cantmask);
        sigdiffset(&p->p_sig, &ignoredefault);
        sigdiffset(&p->p_extsig, &ignoredefault);
        sigdiffset(&t->t_sig, &ignoredefault);
        sigdiffset(&t->t_extsig, &ignoredefault);
}

void
sigcld(proc_t *cp, sigqueue_t *sqp)
{
        proc_t *pp = cp->p_parent;

        ASSERT(MUTEX_HELD(&pidlock));

        switch (cp->p_wcode) {
        case CLD_EXITED:
        case CLD_DUMPED:
        case CLD_KILLED:
                ASSERT(cp->p_stat == SZOMB);
                /*
                 * The broadcast on p_srwchan_cv is a kludge to
                 * wakeup a possible thread in uadmin(A_SHUTDOWN).
                 */
                cv_broadcast(&cp->p_srwchan_cv);

                /*
                 * Add to newstate list of the parent
                 */
                add_ns(pp, cp);

                cv_broadcast(&pp->p_cv);
                if ((pp->p_flag & SNOWAIT) ||
                    PTOU(pp)->u_signal[SIGCLD - 1] == SIG_IGN) {
                        if (!(cp->p_pidflag & CLDWAITPID))
                                freeproc(cp);
                } else if (!(cp->p_pidflag & CLDNOSIGCHLD)) {
                        post_sigcld(cp, sqp);
                        sqp = NULL;
                }
                break;

        case CLD_STOPPED:
        case CLD_CONTINUED:
                cv_broadcast(&pp->p_cv);
                if (pp->p_flag & SJCTL) {
                        post_sigcld(cp, sqp);
                        sqp = NULL;
                }
                break;
        }

        if (sqp)
                siginfofree(sqp);
}

/*
 * Common code called from sigcld() and from
 * waitid() and issig_forreal() via sigcld_repost().
 * Give the parent process a SIGCLD if it does not have one pending,
 * else mark the child process so a SIGCLD can be posted later.
 */
static void
post_sigcld(proc_t *cp, sigqueue_t *sqp)
{
        proc_t *pp = cp->p_parent;
        k_siginfo_t info;

        ASSERT(MUTEX_HELD(&pidlock));
        mutex_enter(&pp->p_lock);

        /*
         * If a SIGCLD is pending, then just mark the child process
         * so that its SIGCLD will be posted later, when the first
         * SIGCLD is taken off the queue or when the parent is ready
         * to receive it or accept it, if ever.
         */
        if (sigismember(&pp->p_sig, SIGCLD)) {
                cp->p_pidflag |= CLDPEND;
        } else {
                cp->p_pidflag &= ~CLDPEND;
                if (sqp == NULL) {
                        /*
                         * This can only happen when the parent is init.
                         * (See call to sigcld(q, NULL) in exit().)
                         * Use KM_NOSLEEP to avoid deadlock.
                         */
                        ASSERT(pp == proc_init);
                        winfo(cp, &info, 0);
                        sigaddq(pp, NULL, &info, KM_NOSLEEP);
                } else {
                        winfo(cp, &sqp->sq_info, 0);
                        sigaddqa(pp, NULL, sqp);
                        sqp = NULL;
                }
        }

        mutex_exit(&pp->p_lock);

        if (sqp)
                siginfofree(sqp);
}

/*
 * Search for a child that has a pending SIGCLD for us, the parent.
 * The queue of SIGCLD signals is implied by the list of children.
 * We post the SIGCLD signals one at a time so they don't get lost.
 * When one is dequeued, another is enqueued, until there are no more.
 */
void
sigcld_repost()
{
        proc_t *pp = curproc;
        proc_t *cp;
        sigqueue_t *sqp;

        sqp = kmem_zalloc(sizeof (sigqueue_t), KM_SLEEP);
        mutex_enter(&pidlock);
        for (cp = pp->p_child; cp; cp = cp->p_sibling) {
                if (cp->p_pidflag & CLDPEND) {
                        post_sigcld(cp, sqp);
                        mutex_exit(&pidlock);
                        return;
                }
        }
        mutex_exit(&pidlock);
        kmem_free(sqp, sizeof (sigqueue_t));
}

/*
 * count number of sigqueue send by sigaddqa()
 */
void
sigqsend(int cmd, proc_t *p, kthread_t *t, sigqueue_t *sigqp)
{
        sigqhdr_t *sqh;

        sqh = (sigqhdr_t *)sigqp->sq_backptr;
        ASSERT(sqh);

        mutex_enter(&sqh->sqb_lock);
        sqh->sqb_sent++;
        mutex_exit(&sqh->sqb_lock);

        if (cmd == SN_SEND)
                sigaddqa(p, t, sigqp);
        else
                siginfofree(sigqp);
}

int
sigsendproc(proc_t *p, sigsend_t *pv)
{
        struct cred *cr;
        proc_t *myprocp = curproc;

        ASSERT(MUTEX_HELD(&pidlock));

        if (p->p_pid == 1 && pv->sig && sigismember(&cantmask, pv->sig))
                return (EPERM);

        cr = CRED();

        if (pv->checkperm == 0 ||
            (pv->sig == SIGCONT && p->p_sessp == myprocp->p_sessp) ||
            prochasprocperm(p, myprocp, cr)) {
                pv->perm++;
                if (pv->sig) {
                        /* Make sure we should be setting si_pid and friends */
                        ASSERT(pv->sicode <= 0);
                        if (SI_CANQUEUE(pv->sicode)) {
                                sigqueue_t *sqp;

                                mutex_enter(&myprocp->p_lock);
                                sqp = sigqalloc(myprocp->p_sigqhdr);
                                mutex_exit(&myprocp->p_lock);
                                if (sqp == NULL)
                                        return (EAGAIN);
                                sqp->sq_info.si_signo = pv->sig;
                                sqp->sq_info.si_code = pv->sicode;
                                sqp->sq_info.si_pid = myprocp->p_pid;
                                sqp->sq_info.si_ctid = PRCTID(myprocp);
                                sqp->sq_info.si_zoneid = getzoneid();
                                sqp->sq_info.si_uid = crgetruid(cr);
                                sqp->sq_info.si_value = pv->value;
                                mutex_enter(&p->p_lock);
                                sigqsend(SN_SEND, p, NULL, sqp);
                                mutex_exit(&p->p_lock);
                        } else {
                                k_siginfo_t info;
                                bzero(&info, sizeof (info));
                                info.si_signo = pv->sig;
                                info.si_code = pv->sicode;
                                info.si_pid = myprocp->p_pid;
                                info.si_ctid = PRCTID(myprocp);
                                info.si_zoneid = getzoneid();
                                info.si_uid = crgetruid(cr);
                                mutex_enter(&p->p_lock);
                                /*
                                 * XXX: Should be KM_SLEEP but
                                 * we have to avoid deadlock.
                                 */
                                sigaddq(p, NULL, &info, KM_NOSLEEP);
                                mutex_exit(&p->p_lock);
                        }
                }
        }

        return (0);
}

int
sigsendset(procset_t *psp, sigsend_t *pv)
{
        int error;

        error = dotoprocs(psp, sigsendproc, (char *)pv);
        if (error == 0 && pv->perm == 0)
                return (EPERM);

        return (error);
}

/*
 * Dequeue a queued siginfo structure.
 * If a non-null thread pointer is passed then dequeue from
 * the thread queue, otherwise dequeue from the process queue.
 */
void
sigdeq(proc_t *p, kthread_t *t, int sig, sigqueue_t **qpp)
{
        sigqueue_t **psqp, *sqp;

        ASSERT(MUTEX_HELD(&p->p_lock));

        *qpp = NULL;

        if (t != NULL) {
                sigdelset(&t->t_sig, sig);
                sigdelset(&t->t_extsig, sig);
                psqp = &t->t_sigqueue;
        } else {
                sigdelset(&p->p_sig, sig);
                sigdelset(&p->p_extsig, sig);
                psqp = &p->p_sigqueue;
        }

        for (;;) {
                if ((sqp = *psqp) == NULL)
                        return;
                if (sqp->sq_info.si_signo == sig)
                        break;
                else
                        psqp = &sqp->sq_next;
        }
        *qpp = sqp;
        *psqp = sqp->sq_next;
        for (sqp = *psqp; sqp; sqp = sqp->sq_next) {
                if (sqp->sq_info.si_signo == sig) {
                        if (t != (kthread_t *)NULL) {
                                sigaddset(&t->t_sig, sig);
                                t->t_sig_check = 1;
                        } else {
                                sigaddset(&p->p_sig, sig);
                                set_proc_ast(p);
                        }
                        break;
                }
        }
}

/*
 * Delete a queued SIGCLD siginfo structure matching the k_siginfo_t argument.
 */
void
sigcld_delete(k_siginfo_t *ip)
{
        proc_t *p = curproc;
        int another_sigcld = 0;
        sigqueue_t **psqp, *sqp;

        ASSERT(ip->si_signo == SIGCLD);

        mutex_enter(&p->p_lock);

        if (!sigismember(&p->p_sig, SIGCLD)) {
                mutex_exit(&p->p_lock);
                return;
        }

        psqp = &p->p_sigqueue;
        for (;;) {
                if ((sqp = *psqp) == NULL) {
                        mutex_exit(&p->p_lock);
                        return;
                }
                if (sqp->sq_info.si_signo == SIGCLD) {
                        if (sqp->sq_info.si_pid == ip->si_pid &&
                            sqp->sq_info.si_code == ip->si_code &&
                            sqp->sq_info.si_status == ip->si_status)
                                break;
                        another_sigcld = 1;
                }
                psqp = &sqp->sq_next;
        }
        *psqp = sqp->sq_next;

        siginfofree(sqp);

        for (sqp = *psqp; !another_sigcld && sqp; sqp = sqp->sq_next) {
                if (sqp->sq_info.si_signo == SIGCLD)
                        another_sigcld = 1;
        }

        if (!another_sigcld) {
                sigdelset(&p->p_sig, SIGCLD);
                sigdelset(&p->p_extsig, SIGCLD);
        }

        mutex_exit(&p->p_lock);
}

/*
 * Delete queued siginfo structures.
 * If a non-null thread pointer is passed then delete from
 * the thread queue, otherwise delete from the process queue.
 */
void
sigdelq(proc_t *p, kthread_t *t, int sig)
{
        sigqueue_t **psqp, *sqp;

        /*
         * We must be holding p->p_lock unless the process is
         * being reaped or has failed to get started on fork.
         */
        ASSERT(MUTEX_HELD(&p->p_lock) ||
            p->p_stat == SIDL || p->p_stat == SZOMB);

        if (t != (kthread_t *)NULL)
                psqp = &t->t_sigqueue;
        else
                psqp = &p->p_sigqueue;

        while (*psqp) {
                sqp = *psqp;
                if (sig == 0 || sqp->sq_info.si_signo == sig) {
                        *psqp = sqp->sq_next;
                        siginfofree(sqp);
                } else
                        psqp = &sqp->sq_next;
        }
}

/*
 * Insert a siginfo structure into a queue.
 * If a non-null thread pointer is passed then add to the thread queue,
 * otherwise add to the process queue.
 *
 * The function sigaddqins() is called with sigqueue already allocated.
 * It is called from sigaddqa() and sigaddq() below.
 *
 * The value of si_code implicitly indicates whether sigp is to be
 * explicitly queued, or to be queued to depth one.
 */
static void
sigaddqins(proc_t *p, kthread_t *t, sigqueue_t *sigqp)
{
        sigqueue_t **psqp;
        int sig = sigqp->sq_info.si_signo;

        sigqp->sq_external = (curproc != &p0) &&
            (curproc->p_ct_process != p->p_ct_process);

        /*
         * issig_forreal() doesn't bother dequeueing signals if SKILLED
         * is set, and even if it did, we would want to avoid situation
         * (which would be unique to SIGKILL) where one thread dequeued
         * the sigqueue_t and another executed psig().  So we create a
         * separate stash for SIGKILL's sigqueue_t.  Because a second
         * SIGKILL can set SEXTKILLED, we overwrite the existing entry
         * if (and only if) it was non-extracontractual.
         */
        if (sig == SIGKILL) {
                if (p->p_killsqp == NULL || !p->p_killsqp->sq_external) {
                        if (p->p_killsqp != NULL)
                                siginfofree(p->p_killsqp);
                        p->p_killsqp = sigqp;
                        sigqp->sq_next = NULL;
                } else {
                        siginfofree(sigqp);
                }
                return;
        }

        ASSERT(sig >= 1 && sig < NSIG);
        if (t != NULL)  /* directed to a thread */
                psqp = &t->t_sigqueue;
        else            /* directed to a process */
                psqp = &p->p_sigqueue;
        if (SI_CANQUEUE(sigqp->sq_info.si_code) &&
            sigismember(&p->p_siginfo, sig)) {
                for (; *psqp != NULL; psqp = &(*psqp)->sq_next)
                                ;
        } else {
                for (; *psqp != NULL; psqp = &(*psqp)->sq_next) {
                        if ((*psqp)->sq_info.si_signo == sig) {
                                siginfofree(sigqp);
                                return;
                        }
                }
        }
        *psqp = sigqp;
        sigqp->sq_next = NULL;
}

/*
 * The function sigaddqa() is called with sigqueue already allocated.
 * If signal is ignored, discard but guarantee KILL and generation semantics.
 * It is called from sigqueue() and other places.
 */
void
sigaddqa(proc_t *p, kthread_t *t, sigqueue_t *sigqp)
{
        int sig = sigqp->sq_info.si_signo;

        ASSERT(MUTEX_HELD(&p->p_lock));
        ASSERT(sig >= 1 && sig < NSIG);

        if (sig_discardable(p, sig))
                siginfofree(sigqp);
        else
                sigaddqins(p, t, sigqp);

        sigtoproc(p, t, sig);
}

/*
 * Allocate the sigqueue_t structure and call sigaddqins().
 */
void
sigaddq(proc_t *p, kthread_t *t, k_siginfo_t *infop, int km_flags)
{
        sigqueue_t *sqp;
        int sig = infop->si_signo;

        ASSERT(MUTEX_HELD(&p->p_lock));
        ASSERT(sig >= 1 && sig < NSIG);

        /*
         * If the signal will be discarded by sigtoproc() or
         * if the process isn't requesting siginfo and it isn't
         * blocking the signal (it *could* change it's mind while
         * the signal is pending) then don't bother creating one.
         */
        if (!sig_discardable(p, sig) &&
            (sigismember(&p->p_siginfo, sig) ||
            (curproc->p_ct_process != p->p_ct_process) ||
            (sig == SIGCLD && SI_FROMKERNEL(infop))) &&
            ((sqp = kmem_alloc(sizeof (sigqueue_t), km_flags)) != NULL)) {
                bcopy(infop, &sqp->sq_info, sizeof (k_siginfo_t));
                sqp->sq_func = NULL;
                sqp->sq_next = NULL;
                sigaddqins(p, t, sqp);
        }
        sigtoproc(p, t, sig);
}

/*
 * Handle stop-on-fault processing for the debugger.  Returns 0
 * if the fault is cleared during the stop, nonzero if it isn't.
 */
int
stop_on_fault(uint_t fault, k_siginfo_t *sip)
{
        proc_t *p = ttoproc(curthread);
        klwp_t *lwp = ttolwp(curthread);

        ASSERT(prismember(&p->p_fltmask, fault));

        /*
         * Record current fault and siginfo structure so debugger can
         * find it.
         */
        mutex_enter(&p->p_lock);
        lwp->lwp_curflt = (uchar_t)fault;
        lwp->lwp_siginfo = *sip;

        stop(PR_FAULTED, fault);

        fault = lwp->lwp_curflt;
        lwp->lwp_curflt = 0;
        mutex_exit(&p->p_lock);
        return (fault);
}

void
sigorset(k_sigset_t *s1, const k_sigset_t *s2)
{
        s1->__sigbits[0] |= s2->__sigbits[0];
        s1->__sigbits[1] |= s2->__sigbits[1];
        s1->__sigbits[2] |= s2->__sigbits[2];
}

void
sigandset(k_sigset_t *s1, const k_sigset_t *s2)
{
        s1->__sigbits[0] &= s2->__sigbits[0];
        s1->__sigbits[1] &= s2->__sigbits[1];
        s1->__sigbits[2] &= s2->__sigbits[2];
}

void
sigdiffset(k_sigset_t *s1, const k_sigset_t *s2)
{
        s1->__sigbits[0] &= ~(s2->__sigbits[0]);
        s1->__sigbits[1] &= ~(s2->__sigbits[1]);
        s1->__sigbits[2] &= ~(s2->__sigbits[2]);
}

/*
 * Return non-zero if curthread->t_sig_check should be set to 1, that is,
 * if there are any signals the thread might take on return from the kernel.
 * If ksigset_t's were a single word, we would do:
 *      return (((p->p_sig | t->t_sig) & ~t->t_hold) & fillset);
 */
int
sigcheck(proc_t *p, kthread_t *t)
{
        sc_shared_t *tdp = t->t_schedctl;

        /*
         * If signals are blocked via the schedctl interface
         * then we only check for the unmaskable signals.
         * The unmaskable signal numbers should all be contained
         * in __sigbits[0] and we assume this for speed.
         */
#if (CANTMASK1 == 0 && CANTMASK2 == 0)
        if (tdp != NULL && tdp->sc_sigblock)
                return ((p->p_sig.__sigbits[0] | t->t_sig.__sigbits[0]) &
                    CANTMASK0);
#else
#error "fix me: CANTMASK1 and CANTMASK2 are not zero"
#endif

/* see uts/common/sys/signal.h for why this must be true */
#if ((MAXSIG > (2 * 32)) && (MAXSIG <= (3 * 32)))
        return (((p->p_sig.__sigbits[0] | t->t_sig.__sigbits[0]) &
            ~t->t_hold.__sigbits[0]) |
            ((p->p_sig.__sigbits[1] | t->t_sig.__sigbits[1]) &
            ~t->t_hold.__sigbits[1]) |
            (((p->p_sig.__sigbits[2] | t->t_sig.__sigbits[2]) &
            ~t->t_hold.__sigbits[2]) & FILLSET2));
#else
#error "fix me: MAXSIG out of bounds"
#endif
}

void
sigintr(k_sigset_t *smask, int intable)
{
        proc_t *p;
        int owned;
        k_sigset_t lmask;               /* local copy of cantmask */
        klwp_t *lwp = ttolwp(curthread);

        /*
         * Mask out all signals except SIGHUP, SIGINT, SIGQUIT
         *    and SIGTERM. (Preserving the existing masks).
         *    This function supports the -intr nfs and ufs mount option.
         */

        /*
         * don't do kernel threads
         */
        if (lwp == NULL)
                return;

        /*
         * get access to signal mask
         */
        p = ttoproc(curthread);
        owned = mutex_owned(&p->p_lock);        /* this is filthy */
        if (!owned)
                mutex_enter(&p->p_lock);

        /*
         * remember the current mask
         */
        schedctl_finish_sigblock(curthread);
        *smask = curthread->t_hold;

        /*
         * mask out all signals
         */
        sigfillset(&curthread->t_hold);

        /*
         * Unmask the non-maskable signals (e.g., KILL), as long as
         * they aren't already masked (which could happen at exit).
         * The first sigdiffset sets lmask to (cantmask & ~curhold).  The
         * second sets the current hold mask to (~0 & ~lmask), which reduces
         * to (~cantmask | curhold).
         */
        lmask = cantmask;
        sigdiffset(&lmask, smask);
        sigdiffset(&curthread->t_hold, &lmask);

        /*
         * Re-enable HUP, QUIT, and TERM iff they were originally enabled
         * Re-enable INT if it's originally enabled and the NFS mount option
         * nointr is not set.
         */
        if (!sigismember(smask, SIGHUP))
                sigdelset(&curthread->t_hold, SIGHUP);
        if (!sigismember(smask, SIGINT) && intable)
                sigdelset(&curthread->t_hold, SIGINT);
        if (!sigismember(smask, SIGQUIT))
                sigdelset(&curthread->t_hold, SIGQUIT);
        if (!sigismember(smask, SIGTERM))
                sigdelset(&curthread->t_hold, SIGTERM);

        /*
         * release access to signal mask
         */
        if (!owned)
                mutex_exit(&p->p_lock);

        /*
         * Indicate that this lwp is not to be stopped.
         */
        lwp->lwp_nostop++;

}

void
sigunintr(k_sigset_t *smask)
{
        proc_t *p;
        int owned;
        klwp_t *lwp = ttolwp(curthread);

        /*
         * Reset previous mask (See sigintr() above)
         */
        if (lwp != NULL) {
                lwp->lwp_nostop--;      /* restore lwp stoppability */
                p = ttoproc(curthread);
                owned = mutex_owned(&p->p_lock);        /* this is filthy */
                if (!owned)
                        mutex_enter(&p->p_lock);
                curthread->t_hold = *smask;
                /* so unmasked signals will be seen */
                curthread->t_sig_check = 1;
                if (!owned)
                        mutex_exit(&p->p_lock);
        }
}

void
sigreplace(k_sigset_t *newmask, k_sigset_t *oldmask)
{
        proc_t  *p;
        int owned;
        /*
         * Save current signal mask in oldmask, then
         * set it to newmask.
         */
        if (ttolwp(curthread) != NULL) {
                p = ttoproc(curthread);
                owned = mutex_owned(&p->p_lock);        /* this is filthy */
                if (!owned)
                        mutex_enter(&p->p_lock);
                schedctl_finish_sigblock(curthread);
                if (oldmask != NULL)
                        *oldmask = curthread->t_hold;
                curthread->t_hold = *newmask;
                curthread->t_sig_check = 1;
                if (!owned)
                        mutex_exit(&p->p_lock);
        }
}

/*
 * Return true if the signal number is in range
 * and the signal code specifies signal queueing.
 */
int
sigwillqueue(int sig, int code)
{
        if (sig >= 0 && sig < NSIG) {
                switch (code) {
                case SI_QUEUE:
                case SI_TIMER:
                case SI_ASYNCIO:
                case SI_MESGQ:
                        return (1);
                }
        }
        return (0);
}

/*
 * The pre-allocated pool (with _SIGQUEUE_PREALLOC entries) is
 * allocated at the first sigqueue/signotify call.
 */
sigqhdr_t *
sigqhdralloc(size_t size, uint_t maxcount)
{
        size_t i;
        sigqueue_t *sq, *next;
        sigqhdr_t *sqh;

        /*
         * Before the introduction of process.max-sigqueue-size
         * _SC_SIGQUEUE_MAX had this static value.
         */
#define _SIGQUEUE_PREALLOC      32

        i = (_SIGQUEUE_PREALLOC * size) + sizeof (sigqhdr_t);
        ASSERT(maxcount <= INT_MAX);
        sqh = kmem_alloc(i, KM_SLEEP);
        sqh->sqb_count = maxcount;
        sqh->sqb_maxcount = maxcount;
        sqh->sqb_size = i;
        sqh->sqb_pexited = 0;
        sqh->sqb_sent = 0;
        sqh->sqb_free = sq = (sigqueue_t *)(sqh + 1);
        for (i = _SIGQUEUE_PREALLOC - 1; i != 0; i--) {
                next = (sigqueue_t *)((uintptr_t)sq + size);
                sq->sq_next = next;
                sq = next;
        }
        sq->sq_next = NULL;
        cv_init(&sqh->sqb_cv, NULL, CV_DEFAULT, NULL);
        mutex_init(&sqh->sqb_lock, NULL, MUTEX_DEFAULT, NULL);
        return (sqh);
}

static void sigqrel(sigqueue_t *);

/*
 * Allocate a sigqueue/signotify structure from the per process
 * pre-allocated pool or allocate a new sigqueue/signotify structure
 * if the pre-allocated pool is exhausted.
 */
sigqueue_t *
sigqalloc(sigqhdr_t *sqh)
{
        sigqueue_t *sq = NULL;

        ASSERT(MUTEX_HELD(&curproc->p_lock));

        if (sqh != NULL) {
                mutex_enter(&sqh->sqb_lock);
                if (sqh->sqb_count > 0) {
                        sqh->sqb_count--;
                        if (sqh->sqb_free == NULL) {
                                /*
                                 * The pre-allocated pool is exhausted.
                                 */
                                sq = kmem_alloc(sizeof (sigqueue_t), KM_SLEEP);
                                sq->sq_func = NULL;
                        } else {
                                sq = sqh->sqb_free;
                                sq->sq_func = sigqrel;
                                sqh->sqb_free = sq->sq_next;
                        }
                        mutex_exit(&sqh->sqb_lock);
                        bzero(&sq->sq_info, sizeof (k_siginfo_t));
                        sq->sq_backptr = sqh;
                        sq->sq_next = NULL;
                        sq->sq_external = 0;
                } else {
                        mutex_exit(&sqh->sqb_lock);
                }
        }
        return (sq);
}

/*
 * Return a sigqueue structure back to the pre-allocated pool.
 */
static void
sigqrel(sigqueue_t *sq)
{
        sigqhdr_t *sqh;

        /* make sure that p_lock of the affected process is held */

        sqh = (sigqhdr_t *)sq->sq_backptr;
        mutex_enter(&sqh->sqb_lock);
        if (sqh->sqb_pexited && sqh->sqb_sent == 1) {
                mutex_exit(&sqh->sqb_lock);
                cv_destroy(&sqh->sqb_cv);
                mutex_destroy(&sqh->sqb_lock);
                kmem_free(sqh, sqh->sqb_size);
        } else {
                sqh->sqb_count++;
                sqh->sqb_sent--;
                sq->sq_next = sqh->sqb_free;
                sq->sq_backptr = NULL;
                sqh->sqb_free = sq;
                cv_signal(&sqh->sqb_cv);
                mutex_exit(&sqh->sqb_lock);
        }
}

/*
 * Free up the pre-allocated sigqueue headers of sigqueue pool
 * and signotify pool, if possible.
 * Called only by the owning process during exec() and exit().
 */
void
sigqfree(proc_t *p)
{
        ASSERT(MUTEX_HELD(&p->p_lock));

        if (p->p_sigqhdr != NULL) {     /* sigqueue pool */
                sigqhdrfree(p->p_sigqhdr);
                p->p_sigqhdr = NULL;
        }
        if (p->p_signhdr != NULL) {     /* signotify pool */
                sigqhdrfree(p->p_signhdr);
                p->p_signhdr = NULL;
        }
}

/*
 * Free up the pre-allocated header and sigq pool if possible.
 */
void
sigqhdrfree(sigqhdr_t *sqh)
{
        mutex_enter(&sqh->sqb_lock);
        if (sqh->sqb_sent == 0) {
                mutex_exit(&sqh->sqb_lock);
                cv_destroy(&sqh->sqb_cv);
                mutex_destroy(&sqh->sqb_lock);
                kmem_free(sqh, sqh->sqb_size);
        } else {
                sqh->sqb_pexited = 1;
                mutex_exit(&sqh->sqb_lock);
        }
}

/*
 * Free up a single sigqueue structure.
 * No other code should free a sigqueue directly.
 */
void
siginfofree(sigqueue_t *sqp)
{
        if (sqp != NULL) {
                if (sqp->sq_func != NULL)
                        (sqp->sq_func)(sqp);
                else
                        kmem_free(sqp, sizeof (sigqueue_t));
        }
}

/*
 * Generate a synchronous signal caused by a hardware
 * condition encountered by an lwp.  Called from trap().
 */
void
trapsig(k_siginfo_t *ip, int restartable)
{
        proc_t *p = ttoproc(curthread);
        int sig = ip->si_signo;
        sigqueue_t *sqp = kmem_zalloc(sizeof (sigqueue_t), KM_SLEEP);

        ASSERT(sig > 0 && sig < NSIG);

        if (curthread->t_dtrace_on)
                dtrace_safe_synchronous_signal();

        mutex_enter(&p->p_lock);
        schedctl_finish_sigblock(curthread);
        /*
         * Avoid a possible infinite loop if the lwp is holding the
         * signal generated by a trap of a restartable instruction or
         * if the signal so generated is being ignored by the process.
         */
        if (restartable &&
            (sigismember(&curthread->t_hold, sig) ||
            p->p_user.u_signal[sig-1] == SIG_IGN)) {
                sigdelset(&curthread->t_hold, sig);
                p->p_user.u_signal[sig-1] = SIG_DFL;
                sigdelset(&p->p_ignore, sig);
        }
        bcopy(ip, &sqp->sq_info, sizeof (k_siginfo_t));
        sigaddqa(p, curthread, sqp);
        mutex_exit(&p->p_lock);
}

/*
 * Dispatch the real time profiling signal in the traditional way,
 * honoring all of the /proc tracing mechanism built into issig().
 */
static void
realsigprof_slow(int sysnum, int nsysarg, int error)
{
        kthread_t *t = curthread;
        proc_t *p = ttoproc(t);
        klwp_t *lwp = ttolwp(t);
        k_siginfo_t *sip = &lwp->lwp_siginfo;
        void (*func)();

        mutex_enter(&p->p_lock);
        func = PTOU(p)->u_signal[SIGPROF - 1];
        if (p->p_rprof_cyclic == CYCLIC_NONE ||
            func == SIG_DFL || func == SIG_IGN) {
                bzero(t->t_rprof, sizeof (*t->t_rprof));
                mutex_exit(&p->p_lock);
                return;
        }
        if (sigismember(&t->t_hold, SIGPROF)) {
                mutex_exit(&p->p_lock);
                return;
        }
        sip->si_signo = SIGPROF;
        sip->si_code = PROF_SIG;
        sip->si_errno = error;
        hrt2ts(gethrtime(), &sip->si_tstamp);
        sip->si_syscall = sysnum;
        sip->si_nsysarg = nsysarg;
        sip->si_fault = lwp->lwp_lastfault;
        sip->si_faddr = lwp->lwp_lastfaddr;
        lwp->lwp_lastfault = 0;
        lwp->lwp_lastfaddr = NULL;
        sigtoproc(p, t, SIGPROF);
        mutex_exit(&p->p_lock);
        ASSERT(lwp->lwp_cursig == 0);
        if (issig(FORREAL))
                psig();
        sip->si_signo = 0;
        bzero(t->t_rprof, sizeof (*t->t_rprof));
}

/*
 * We are not tracing the SIGPROF signal, or doing any other unnatural
 * acts, like watchpoints, so dispatch the real time profiling signal
 * directly, bypassing all of the overhead built into issig().
 */
static void
realsigprof_fast(int sysnum, int nsysarg, int error)
{
        kthread_t *t = curthread;
        proc_t *p = ttoproc(t);
        klwp_t *lwp = ttolwp(t);
        k_siginfo_t *sip = &lwp->lwp_siginfo;
        void (*func)();
        int rc;
        int code;

        /*
         * We don't need to acquire p->p_lock here;
         * we are manipulating thread-private data.
         */
        func = PTOU(p)->u_signal[SIGPROF - 1];
        if (p->p_rprof_cyclic == CYCLIC_NONE ||
            func == SIG_DFL || func == SIG_IGN) {
                bzero(t->t_rprof, sizeof (*t->t_rprof));
                return;
        }
        if (lwp->lwp_cursig != 0 ||
            lwp->lwp_curinfo != NULL ||
            sigismember(&t->t_hold, SIGPROF)) {
                return;
        }
        sip->si_signo = SIGPROF;
        sip->si_code = PROF_SIG;
        sip->si_errno = error;
        hrt2ts(gethrtime(), &sip->si_tstamp);
        sip->si_syscall = sysnum;
        sip->si_nsysarg = nsysarg;
        sip->si_fault = lwp->lwp_lastfault;
        sip->si_faddr = lwp->lwp_lastfaddr;
        lwp->lwp_lastfault = 0;
        lwp->lwp_lastfaddr = NULL;
        if (t->t_flag & T_TOMASK)
                t->t_flag &= ~T_TOMASK;
        else
                lwp->lwp_sigoldmask = t->t_hold;
        sigorset(&t->t_hold, &PTOU(p)->u_sigmask[SIGPROF - 1]);
        if (!sigismember(&PTOU(p)->u_signodefer, SIGPROF))
                sigaddset(&t->t_hold, SIGPROF);
        lwp->lwp_extsig = 0;
        lwp->lwp_ru.nsignals++;
        if (p->p_model == DATAMODEL_NATIVE)
                rc = sendsig(SIGPROF, sip, func);
#ifdef _SYSCALL32_IMPL
        else
                rc = sendsig32(SIGPROF, sip, func);
#endif  /* _SYSCALL32_IMPL */
        sip->si_signo = 0;
        bzero(t->t_rprof, sizeof (*t->t_rprof));
        if (rc == 0) {
                /*
                 * sendsig() failed; we must dump core with a SIGSEGV.
                 * See psig().  This code is copied from there.
                 */
                lwp->lwp_cursig = SIGSEGV;
                code = CLD_KILLED;
                proc_is_exiting(p);
                if (exitlwps(1) != 0) {
                        mutex_enter(&p->p_lock);
                        lwp_exit();
                }
                if (audit_active == C2AUDIT_LOADED)
                        audit_core_start(SIGSEGV);
                if (core(SIGSEGV, 0) == 0)
                        code = CLD_DUMPED;
                if (audit_active == C2AUDIT_LOADED)
                        audit_core_finish(code);
                exit(code, SIGSEGV);
        }
}

/*
 * Arrange for the real time profiling signal to be dispatched.
 */
void
realsigprof(int sysnum, int nsysarg, int error)
{
        kthread_t *t = curthread;
        proc_t *p = ttoproc(t);

        if (t->t_rprof->rp_anystate == 0)
                return;

        schedctl_finish_sigblock(t);

        /* test for any activity that requires p->p_lock */
        if (tracing(p, SIGPROF) || pr_watch_active(p) ||
            sigismember(&PTOU(p)->u_sigresethand, SIGPROF)) {
                /* do it the classic slow way */
                realsigprof_slow(sysnum, nsysarg, error);
        } else {
                /* do it the cheating-a-little fast way */
                realsigprof_fast(sysnum, nsysarg, error);
        }
}

#ifdef _SYSCALL32_IMPL

/*
 * It's tricky to transmit a sigval between 32-bit and 64-bit
 * process, since in the 64-bit world, a pointer and an integer
 * are different sizes.  Since we're constrained by the standards
 * world not to change the types, and it's unclear how useful it is
 * to send pointers between address spaces this way, we preserve
 * the 'int' interpretation for 32-bit processes interoperating
 * with 64-bit processes.  The full semantics (pointers or integers)
 * are available for N-bit processes interoperating with N-bit
 * processes.
 */
void
siginfo_kto32(const k_siginfo_t *src, siginfo32_t *dest)
{
        bzero(dest, sizeof (*dest));

        /*
         * The absolute minimum content is si_signo and si_code.
         */
        dest->si_signo = src->si_signo;
        if ((dest->si_code = src->si_code) == SI_NOINFO)
                return;

        /*
         * A siginfo generated by user level is structured
         * differently from one generated by the kernel.
         */
        if (SI_FROMUSER(src)) {
                dest->si_pid = src->si_pid;
                dest->si_ctid = src->si_ctid;
                dest->si_zoneid = src->si_zoneid;
                dest->si_uid = src->si_uid;
                if (SI_CANQUEUE(src->si_code))
                        dest->si_value.sival_int =
                            (int32_t)src->si_value.sival_int;
                return;
        }

        dest->si_errno = src->si_errno;

        switch (src->si_signo) {
        default:
                dest->si_pid = src->si_pid;
                dest->si_ctid = src->si_ctid;
                dest->si_zoneid = src->si_zoneid;
                dest->si_uid = src->si_uid;
                dest->si_value.sival_int = (int32_t)src->si_value.sival_int;
                break;
        case SIGCLD:
                dest->si_pid = src->si_pid;
                dest->si_ctid = src->si_ctid;
                dest->si_zoneid = src->si_zoneid;
                dest->si_status = src->si_status;
                dest->si_stime = src->si_stime;
                dest->si_utime = src->si_utime;
                break;
        case SIGSEGV:
        case SIGBUS:
        case SIGILL:
        case SIGTRAP:
        case SIGFPE:
        case SIGEMT:
                dest->si_addr = (caddr32_t)(uintptr_t)src->si_addr;
                dest->si_trapno = src->si_trapno;
                dest->si_pc = (caddr32_t)(uintptr_t)src->si_pc;
                break;
        case SIGPOLL:
        case SIGXFSZ:
                dest->si_fd = src->si_fd;
                dest->si_band = src->si_band;
                break;
        case SIGPROF:
                dest->si_faddr = (caddr32_t)(uintptr_t)src->si_faddr;
                dest->si_tstamp.tv_sec = src->si_tstamp.tv_sec;
                dest->si_tstamp.tv_nsec = src->si_tstamp.tv_nsec;
                dest->si_syscall = src->si_syscall;
                dest->si_nsysarg = src->si_nsysarg;
                dest->si_fault = src->si_fault;
                break;
        }
}

void
siginfo_32tok(const siginfo32_t *src, k_siginfo_t *dest)
{
        bzero(dest, sizeof (*dest));

        /*
         * The absolute minimum content is si_signo and si_code.
         */
        dest->si_signo = src->si_signo;
        if ((dest->si_code = src->si_code) == SI_NOINFO)
                return;

        /*
         * A siginfo generated by user level is structured
         * differently from one generated by the kernel.
         */
        if (SI_FROMUSER(src)) {
                dest->si_pid = src->si_pid;
                dest->si_ctid = src->si_ctid;
                dest->si_zoneid = src->si_zoneid;
                dest->si_uid = src->si_uid;
                if (SI_CANQUEUE(src->si_code))
                        dest->si_value.sival_int =
                            (int)src->si_value.sival_int;
                return;
        }

        dest->si_errno = src->si_errno;

        switch (src->si_signo) {
        default:
                dest->si_pid = src->si_pid;
                dest->si_ctid = src->si_ctid;
                dest->si_zoneid = src->si_zoneid;
                dest->si_uid = src->si_uid;
                dest->si_value.sival_int = (int)src->si_value.sival_int;
                break;
        case SIGCLD:
                dest->si_pid = src->si_pid;
                dest->si_ctid = src->si_ctid;
                dest->si_zoneid = src->si_zoneid;
                dest->si_status = src->si_status;
                dest->si_stime = src->si_stime;
                dest->si_utime = src->si_utime;
                break;
        case SIGSEGV:
        case SIGBUS:
        case SIGILL:
        case SIGTRAP:
        case SIGFPE:
        case SIGEMT:
                dest->si_addr = (void *)(uintptr_t)src->si_addr;
                dest->si_trapno = src->si_trapno;
                dest->si_pc = (void *)(uintptr_t)src->si_pc;
                break;
        case SIGPOLL:
        case SIGXFSZ:
                dest->si_fd = src->si_fd;
                dest->si_band = src->si_band;
                break;
        case SIGPROF:
                dest->si_faddr = (void *)(uintptr_t)src->si_faddr;
                dest->si_tstamp.tv_sec = src->si_tstamp.tv_sec;
                dest->si_tstamp.tv_nsec = src->si_tstamp.tv_nsec;
                dest->si_syscall = src->si_syscall;
                dest->si_nsysarg = src->si_nsysarg;
                dest->si_fault = src->si_fault;
                break;
        }
}

#endif /* _SYSCALL32_IMPL */