/*
 * Copyright (c) 1982, 1986, 1989, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)kern_sig.c  8.7 (Berkeley) 4/18/94
 * $FreeBSD: src/sys/kern/kern_sig.c,v 1.72.2.17 2003/05/16 16:34:34 obrien Exp $
 */

#include "opt_ktrace.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysmsg.h>
#include <sys/signalvar.h>
#include <sys/resourcevar.h>
#include <sys/vnode.h>
#include <sys/event.h>
#include <sys/proc.h>
#include <sys/nlookup.h>
#include <sys/pioctl.h>
#include <sys/acct.h>
#include <sys/fcntl.h>
#include <sys/lock.h>
#include <sys/wait.h>
#include <sys/ktrace.h>
#include <sys/syslog.h>
#include <sys/stat.h>
#include <sys/sysent.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <sys/interrupt.h>
#include <sys/unistd.h>
#include <sys/kern_syscall.h>
#include <sys/vkernel.h>

#include <sys/signal2.h>
#include <sys/thread2.h>
#include <sys/spinlock2.h>

#include <machine/cpu.h>
#include <machine/smp.h>

static int      coredump(struct lwp *, int);
static char     *expand_name(const char *, uid_t, pid_t);
static int      dokillpg(int sig, int pgid, int all);
static int      sig_ffs(sigset_t *set);
static int      sigprop(int sig);
static void     lwp_signotify(struct lwp *lp);
static void     lwp_signotify_remote(void *arg);
static int      kern_sigtimedwait(sigset_t set, siginfo_t *info,
                    struct timespec *timeout);
static void     proc_stopwait(struct proc *p);

static int      filt_sigattach(struct knote *kn);
static void     filt_sigdetach(struct knote *kn);
static int      filt_signal(struct knote *kn, long hint);

struct filterops sig_filtops =
        { FILTEROP_MPSAFE, filt_sigattach, filt_sigdetach, filt_signal };

static int      kern_logsigexit = 1;
SYSCTL_INT(_kern, KERN_LOGSIGEXIT, logsigexit, CTLFLAG_RW,
    &kern_logsigexit, 0,
    "Log processes quitting on abnormal signals to syslog(3)");

/*
 * Policy -- Can real uid ruid with ucred uc send a signal to process q?
 */
#define CANSIGIO(ruid, uc, q) \
        ((uc)->cr_uid == 0 || \
            (ruid) == (q)->p_ucred->cr_ruid || \
            (uc)->cr_uid == (q)->p_ucred->cr_ruid || \
            (ruid) == (q)->p_ucred->cr_uid || \
            (uc)->cr_uid == (q)->p_ucred->cr_uid)

int sugid_coredump;
SYSCTL_INT(_kern, OID_AUTO, sugid_coredump, CTLFLAG_RW,
        &sugid_coredump, 0, "Enable coredumping set user/group ID processes");

static int      do_coredump = 1;
SYSCTL_INT(_kern, OID_AUTO, coredump, CTLFLAG_RW,
        &do_coredump, 0, "Enable/Disable coredumps");

/*
 * Signal properties and actions.
 * The array below categorizes the signals and their default actions
 * according to the following properties:
 */
#define SA_KILL         0x01            /* terminates process by default */
#define SA_CORE         0x02            /* ditto and coredumps */
#define SA_STOP         0x04            /* suspend process */
#define SA_TTYSTOP      0x08            /* ditto, from tty */
#define SA_IGNORE       0x10            /* ignore by default */
#define SA_CONT         0x20            /* continue if suspended */
#define SA_CANTMASK     0x40            /* non-maskable, catchable */
#define SA_CKPT         0x80            /* checkpoint process */


static int sigproptbl[NSIG] = {
        SA_KILL,                /* SIGHUP */
        SA_KILL,                /* SIGINT */
        SA_KILL|SA_CORE,        /* SIGQUIT */
        SA_KILL|SA_CORE,        /* SIGILL */
        SA_KILL|SA_CORE,        /* SIGTRAP */
        SA_KILL|SA_CORE,        /* SIGABRT */
        SA_KILL|SA_CORE,        /* SIGEMT */
        SA_KILL|SA_CORE,        /* SIGFPE */
        SA_KILL,                /* SIGKILL */
        SA_KILL|SA_CORE,        /* SIGBUS */
        SA_KILL|SA_CORE,        /* SIGSEGV */
        SA_KILL|SA_CORE,        /* SIGSYS */
        SA_KILL,                /* SIGPIPE */
        SA_KILL,                /* SIGALRM */
        SA_KILL,                /* SIGTERM */
        SA_IGNORE,              /* SIGURG */
        SA_STOP,                /* SIGSTOP */
        SA_STOP|SA_TTYSTOP,     /* SIGTSTP */
        SA_IGNORE|SA_CONT,      /* SIGCONT */
        SA_IGNORE,              /* SIGCHLD */
        SA_STOP|SA_TTYSTOP,     /* SIGTTIN */
        SA_STOP|SA_TTYSTOP,     /* SIGTTOU */
        SA_IGNORE,              /* SIGIO */
        SA_KILL,                /* SIGXCPU */
        SA_KILL,                /* SIGXFSZ */
        SA_KILL,                /* SIGVTALRM */
        SA_KILL,                /* SIGPROF */
        SA_IGNORE,              /* SIGWINCH  */
        SA_IGNORE,              /* SIGINFO */
        SA_KILL,                /* SIGUSR1 */
        SA_KILL,                /* SIGUSR2 */
        SA_IGNORE,              /* SIGTHR */
        SA_CKPT,                /* SIGCKPT */
        SA_KILL|SA_CKPT,        /* SIGCKPTEXIT */
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
        SA_IGNORE,
};

__read_mostly sigset_t sigcantmask_mask;

static __inline int
sigprop(int sig)
{

        if (sig > 0 && sig < NSIG)
                return (sigproptbl[_SIG_IDX(sig)]);

        return (0);
}

static __inline int
sig_ffs(sigset_t *set)
{
        int i;

        for (i = 0; i < _SIG_WORDS; i++)
                if (set->__bits[i])
                        return (ffs(set->__bits[i]) + (i * 32));
        return (0);
}

/*
 * Allows us to populate siginfo->si_pid and si_uid in the target process
 * (p) from the originating thread (td).  This function must work properly
 * even if a kernel thread is sending the signal.
 *
 * NOTE: Signals are not queued, so if multiple signals are received the
 *       signal handler will only see the most recent pid and uid for any
 *       given signal number.
 */
static __inline void
sigsetfrompid(thread_t td, struct proc *p, int sig)
{
        struct sigacts *sap;

        if ((sap = p->p_sigacts) == NULL)
                return;
        if (td->td_proc) {
                sap->ps_frominfo[sig].pid = td->td_proc->p_pid;
                sap->ps_frominfo[sig].uid = td->td_ucred->cr_uid;
        } else {
                sap->ps_frominfo[sig].pid = 0;
                sap->ps_frominfo[sig].uid = 0;
        }
}

/*
 * No requirements.
 */
int
kern_sigaction(int sig, struct sigaction *act, struct sigaction *oact)
{
        struct thread *td = curthread;
        struct proc *p = td->td_proc;
        struct lwp *lp;
        struct sigacts *ps = p->p_sigacts;

        if (!_SIG_VALID(sig))
                return (EINVAL);

        lwkt_gettoken(&p->p_token);

        if (oact) {
                oact->sa_handler = ps->ps_sigact[_SIG_IDX(sig)];
                oact->sa_mask = ps->ps_catchmask[_SIG_IDX(sig)];
                oact->sa_flags = 0;
                if (SIGISMEMBER(ps->ps_sigonstack, sig))
                        oact->sa_flags |= SA_ONSTACK;
                if (!SIGISMEMBER(ps->ps_sigintr, sig))
                        oact->sa_flags |= SA_RESTART;
                if (SIGISMEMBER(ps->ps_sigreset, sig))
                        oact->sa_flags |= SA_RESETHAND;
                if (SIGISMEMBER(ps->ps_signodefer, sig))
                        oact->sa_flags |= SA_NODEFER;
                if (SIGISMEMBER(ps->ps_siginfo, sig))
                        oact->sa_flags |= SA_SIGINFO;
                if (sig == SIGCHLD) {
                        if (p->p_sigacts->ps_flag & PS_NOCLDSTOP)
                                oact->sa_flags |= SA_NOCLDSTOP;
                        if (p->p_sigacts->ps_flag & PS_NOCLDWAIT)
                                oact->sa_flags |= SA_NOCLDWAIT;
                }
        }
        if (act) {
                /*
                 * Check for invalid requests.  KILL and STOP cannot be
                 * caught.
                 */
                if (sig == SIGKILL || sig == SIGSTOP) {
                        if (act->sa_handler != SIG_DFL) {
                                lwkt_reltoken(&p->p_token);
                                return (EINVAL);
                        }
                }

                /*
                 * Change setting atomically.
                 */
                ps->ps_catchmask[_SIG_IDX(sig)] = act->sa_mask;
                SIG_CANTMASK(ps->ps_catchmask[_SIG_IDX(sig)]);
                if (act->sa_flags & SA_SIGINFO) {
                        ps->ps_sigact[_SIG_IDX(sig)] =
                            (__sighandler_t *)act->sa_sigaction;
                        SIGADDSET(ps->ps_siginfo, sig);
                } else {
                        ps->ps_sigact[_SIG_IDX(sig)] = act->sa_handler;
                        SIGDELSET(ps->ps_siginfo, sig);
                }
                if (!(act->sa_flags & SA_RESTART))
                        SIGADDSET(ps->ps_sigintr, sig);
                else
                        SIGDELSET(ps->ps_sigintr, sig);
                if (act->sa_flags & SA_ONSTACK)
                        SIGADDSET(ps->ps_sigonstack, sig);
                else
                        SIGDELSET(ps->ps_sigonstack, sig);
                if (act->sa_flags & SA_RESETHAND)
                        SIGADDSET(ps->ps_sigreset, sig);
                else
                        SIGDELSET(ps->ps_sigreset, sig);
                if (act->sa_flags & SA_NODEFER)
                        SIGADDSET(ps->ps_signodefer, sig);
                else
                        SIGDELSET(ps->ps_signodefer, sig);
                if (sig == SIGCHLD) {
                        if (act->sa_flags & SA_NOCLDSTOP)
                                p->p_sigacts->ps_flag |= PS_NOCLDSTOP;
                        else
                                p->p_sigacts->ps_flag &= ~PS_NOCLDSTOP;
                        if (act->sa_flags & SA_NOCLDWAIT) {
                                /*
                                 * Paranoia: since SA_NOCLDWAIT is implemented
                                 * by reparenting the dying child to PID 1 (and
                                 * trust it to reap the zombie), PID 1 itself
                                 * is forbidden to set SA_NOCLDWAIT.
                                 */
                                if (p->p_pid == 1)
                                        p->p_sigacts->ps_flag &= ~PS_NOCLDWAIT;
                                else
                                        p->p_sigacts->ps_flag |= PS_NOCLDWAIT;
                        } else {
                                p->p_sigacts->ps_flag &= ~PS_NOCLDWAIT;
                        }
                        if (ps->ps_sigact[_SIG_IDX(SIGCHLD)] == SIG_IGN)
                                ps->ps_flag |= PS_CLDSIGIGN;
                        else
                                ps->ps_flag &= ~PS_CLDSIGIGN;
                }
                /*
                 * Set bit in p_sigignore for signals that are set to SIG_IGN,
                 * and for signals set to SIG_DFL where the default is to
                 * ignore. However, don't put SIGCONT in p_sigignore, as we
                 * have to restart the process.
                 *
                 * Also remove the signal from the process and lwp signal
                 * list.
                 */
                if (ps->ps_sigact[_SIG_IDX(sig)] == SIG_IGN ||
                    (sigprop(sig) & SA_IGNORE &&
                     ps->ps_sigact[_SIG_IDX(sig)] == SIG_DFL)) {
                        SIGDELSET_ATOMIC(p->p_siglist, sig);
                        FOREACH_LWP_IN_PROC(lp, p) {
                                spin_lock(&lp->lwp_spin);
                                SIGDELSET(lp->lwp_siglist, sig);
                                spin_unlock(&lp->lwp_spin);
                        }
                        if (sig != SIGCONT) {
                                /* easier in ksignal */
                                SIGADDSET(p->p_sigignore, sig);
                        }
                        SIGDELSET(p->p_sigcatch, sig);
                } else {
                        SIGDELSET(p->p_sigignore, sig);
                        if (ps->ps_sigact[_SIG_IDX(sig)] == SIG_DFL)
                                SIGDELSET(p->p_sigcatch, sig);
                        else
                                SIGADDSET(p->p_sigcatch, sig);
                }
        }
        lwkt_reltoken(&p->p_token);
        return (0);
}

int
sys_sigaction(struct sysmsg *sysmsg, const struct sigaction_args *uap)
{
        struct sigaction act, oact;
        struct sigaction *actp, *oactp;
        int error;

        actp = (uap->act != NULL) ? &act : NULL;
        oactp = (uap->oact != NULL) ? &oact : NULL;
        if (actp) {
                error = copyin(uap->act, actp, sizeof(act));
                if (error)
                        return (error);
        }
        error = kern_sigaction(uap->sig, actp, oactp);
        if (oactp && !error) {
                error = copyout(oactp, uap->oact, sizeof(oact));
        }
        return (error);
}

/*
 * Initialize signal state for process 0;
 * set to ignore signals that are ignored by default.
 */
void
siginit(struct proc *p)
{
        int i;

        for (i = 1; i <= NSIG; i++) {
                if ((sigprop(i) & SA_IGNORE) && i != SIGCONT)
                        SIGADDSET(p->p_sigignore, i);
        }

        /*
         * Also initialize signal-related global state.
         */
        SIGSETOR_CANTMASK(sigcantmask_mask);
}

/*
 * Reset signals for an exec of the specified process.
 */
void
execsigs(struct proc *p)
{
        struct sigacts *ps = p->p_sigacts;
        struct lwp *lp;
        int sig;

        lp = ONLY_LWP_IN_PROC(p);

        /*
         * Reset caught signals.  Held signals remain held
         * through p_sigmask (unless they were caught,
         * and are now ignored by default).
         */
        while (SIGNOTEMPTY(p->p_sigcatch)) {
                sig = sig_ffs(&p->p_sigcatch);
                SIGDELSET(p->p_sigcatch, sig);
                if (sigprop(sig) & SA_IGNORE) {
                        if (sig != SIGCONT)
                                SIGADDSET(p->p_sigignore, sig);
                        SIGDELSET_ATOMIC(p->p_siglist, sig);
                        /* don't need spinlock */
                        SIGDELSET(lp->lwp_siglist, sig);
                }
                ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL;
        }

        /*
         * Reset stack state to the user stack.
         * Clear set of signals caught on the signal stack.
         */
        lp->lwp_sigstk.ss_flags = SS_DISABLE;
        lp->lwp_sigstk.ss_size = 0;
        lp->lwp_sigstk.ss_sp = NULL;
        lp->lwp_flags &= ~LWP_ALTSTACK;
        /*
         * Reset no zombies if child dies flag as Solaris does.
         */
        p->p_sigacts->ps_flag &= ~(PS_NOCLDWAIT | PS_CLDSIGIGN);
        if (ps->ps_sigact[_SIG_IDX(SIGCHLD)] == SIG_IGN)
                ps->ps_sigact[_SIG_IDX(SIGCHLD)] = SIG_DFL;
}

/*
 * kern_sigprocmask() - MP SAFE ONLY IF p == curproc
 *
 *      Manipulate signal mask.  This routine is MP SAFE *ONLY* if
 *      p == curproc.
 */
int
kern_sigprocmask(int how, sigset_t *set, sigset_t *oset)
{
        struct thread *td = curthread;
        struct lwp *lp = td->td_lwp;
        struct proc *p = td->td_proc;
        int error;

        lwkt_gettoken(&p->p_token);

        if (oset != NULL)
                *oset = lp->lwp_sigmask;

        error = 0;
        if (set != NULL) {
                switch (how) {
                case SIG_BLOCK:
                        SIG_CANTMASK(*set);
                        SIGSETOR(lp->lwp_sigmask, *set);
                        break;
                case SIG_UNBLOCK:
                        SIGSETNAND(lp->lwp_sigmask, *set);
                        break;
                case SIG_SETMASK:
                        SIG_CANTMASK(*set);
                        lp->lwp_sigmask = *set;
                        sigirefs_wait(p);
                        break;
                default:
                        error = EINVAL;
                        break;
                }
        }

        lwkt_reltoken(&p->p_token);

        return (error);
}

/*
 * sigprocmask()
 *
 * MPSAFE
 */
int
sys_sigprocmask(struct sysmsg *sysmsg, const struct sigprocmask_args *uap)
{
        sigset_t set, oset;
        sigset_t *setp, *osetp;
        int error;

        setp = (uap->set != NULL) ? &set : NULL;
        osetp = (uap->oset != NULL) ? &oset : NULL;
        if (setp) {
                error = copyin(uap->set, setp, sizeof(set));
                if (error)
                        return (error);
        }
        error = kern_sigprocmask(uap->how, setp, osetp);
        if (osetp && !error) {
                error = copyout(osetp, uap->oset, sizeof(oset));
        }
        return (error);
}

/*
 * MPSAFE
 */
int
kern_sigpending(sigset_t *set)
{
        struct lwp *lp = curthread->td_lwp;

        *set = lwp_sigpend(lp);

        return (0);
}

/*
 * MPSAFE
 */
int
sys_sigpending(struct sysmsg *sysmsg, const struct sigpending_args *uap)
{
        sigset_t set;
        int error;

        error = kern_sigpending(&set);

        if (error == 0)
                error = copyout(&set, uap->set, sizeof(set));
        return (error);
}

/*
 * Suspend process until signal, providing mask to be set
 * in the meantime.
 *
 * MPSAFE
 */
int
kern_sigsuspend(sigset_t *set)
{
        struct thread *td = curthread;
        struct lwp *lp = td->td_lwp;
        struct proc *p = td->td_proc;
        struct sigacts *ps = p->p_sigacts;

        /*
         * When returning from sigsuspend, we want the old mask to be
         * restored after the signal handler has finished.  Thus, we
         * save it here and mark the sigacts structure to indicate this.
         *
         * To interlock signal deliveries which may race this function, we
         * must hold the LWP token, otherwise the signal may be made pending
         * to the process rather than the lwp during execution of the tsleep()
         * (which does not hold the process token to interlock that) and be
         * missed by the tsleep().
         */
        lwkt_gettoken(&lp->lwp_token);
        lp->lwp_oldsigmask = lp->lwp_sigmask;
        lp->lwp_flags |= LWP_OLDMASK;
        SIG_CANTMASK(*set);
        lp->lwp_sigmask = *set;
        lwkt_reltoken(&lp->lwp_token);
        sigirefs_wait(p);

        while (tsleep(ps, PCATCH, "pause", 0) == 0)
                /* void */;
        /* always return EINTR rather than ERESTART... */
        return (EINTR);
}

/*
 * Note nonstandard calling convention: libc stub passes mask, not
 * pointer, to save a copyin.
 *
 * MPSAFE
 */
int
sys_sigsuspend(struct sysmsg *sysmsg, const struct sigsuspend_args *uap)
{
        sigset_t mask;
        int error;

        error = copyin(uap->sigmask, &mask, sizeof(mask));
        if (error)
                return (error);

        error = kern_sigsuspend(&mask);

        return (error);
}

/*
 * MPSAFE
 */
int
kern_sigaltstack(stack_t *ss, stack_t *oss)
{
        struct thread *td = curthread;
        struct lwp *lp = td->td_lwp;
        struct proc *p = td->td_proc;

        if ((lp->lwp_flags & LWP_ALTSTACK) == 0)
                lp->lwp_sigstk.ss_flags |= SS_DISABLE;

        if (oss)
                *oss = lp->lwp_sigstk;

        if (ss) {
                if (ss->ss_flags & ~SS_DISABLE)
                        return (EINVAL);
                if (ss->ss_flags & SS_DISABLE) {
                        if (lp->lwp_sigstk.ss_flags & SS_ONSTACK)
                                return (EPERM);
                        lp->lwp_flags &= ~LWP_ALTSTACK;
                        lp->lwp_sigstk.ss_flags = ss->ss_flags;
                } else {
                        if (ss->ss_size < p->p_sysent->sv_minsigstksz)
                                return (ENOMEM);
                        lp->lwp_flags |= LWP_ALTSTACK;
                        lp->lwp_sigstk = *ss;
                }
        }

        return (0);
}

/*
 * MPSAFE
 */
int
sys_sigaltstack(struct sysmsg *sysmsg, const struct sigaltstack_args *uap)
{
        stack_t ss, oss;
        int error;

        if (uap->ss) {
                error = copyin(uap->ss, &ss, sizeof(ss));
                if (error)
                        return (error);
        }

        error = kern_sigaltstack(uap->ss ? &ss : NULL, uap->oss ? &oss : NULL);

        if (error == 0 && uap->oss)
                error = copyout(&oss, uap->oss, sizeof(*uap->oss));
        return (error);
}

/*
 * Common code for kill process group/broadcast kill.
 * cp is calling process.
 */
struct killpg_info {
        int nfound;
        int sig;
};

static int killpg_all_callback(struct proc *p, void *data);

static int
dokillpg(int sig, int pgid, int all)
{
        struct killpg_info info;
        struct proc *cp = curproc;
        struct proc *p;
        struct pgrp *pgrp;

        info.nfound = 0;
        info.sig = sig;

        if (all) {
                /*
                 * broadcast
                 */
                allproc_scan(killpg_all_callback, &info, 0);
        } else {
                if (pgid == 0) {
                        /*
                         * zero pgid means send to my process group.
                         */
                        pgrp = cp->p_pgrp;
                        pgref(pgrp);
                } else {
                        pgrp = pgfind(pgid);
                        if (pgrp == NULL)
                                return (ESRCH);
                }

                /*
                 * Must interlock all signals against fork
                 */
                lockmgr(&pgrp->pg_lock, LK_EXCLUSIVE);
                LIST_FOREACH(p, &pgrp->pg_members, p_pglist) {
                        if (p->p_pid <= 1 ||
                            p->p_stat == SZOMB ||
                            (p->p_flags & P_SYSTEM) ||
                            !CANSIGNAL(p, sig, 0)) {
                                continue;
                        }
                        ++info.nfound;
                        if (sig)
                                ksignal(p, sig);
                }
                lockmgr(&pgrp->pg_lock, LK_RELEASE);
                pgrel(pgrp);
        }
        return (info.nfound ? 0 : ESRCH);
}

static int
killpg_all_callback(struct proc *p, void *data)
{
        struct killpg_info *info = data;

        if (p->p_pid <= 1 || (p->p_flags & P_SYSTEM) ||
            p == curproc || !CANSIGNAL(p, info->sig, 0)) {
                return (0);
        }
        ++info->nfound;
        if (info->sig)
                ksignal(p, info->sig);
        return(0);
}

/*
 * Send a general signal to a process or LWPs within that process.
 *
 * Note that new signals cannot be sent if a process is exiting or already
 * a zombie, but we return success anyway as userland is likely to not handle
 * the race properly.
 *
 * No requirements.
 */
int
kern_kill(int sig, pid_t pid, lwpid_t tid)
{
        int t;

        if ((u_int)sig >= _SIG_MAXSIG)
                return (EINVAL);

        if (pid > 0) {
                struct proc *p;
                struct lwp *lp = NULL;

                /*
                 * Sending a signal to pid 1 as root requires that we
                 * are not reboot-restricted.
                 */
                if (pid == 1 && caps_priv_check_self(SYSCAP_NOREBOOT | __SYSCAP_WHEELOK))
                        return EPERM;

                /*
                 * Send a signal to a single process.  If the kill() is
                 * racing an exiting process which has not yet been reaped
                 * act as though the signal was delivered successfully but
                 * don't actually try to deliver the signal.
                 */
                if ((p = pfind(pid)) == NULL) {
                        if ((p = zpfind(pid)) == NULL)
                                return (ESRCH);
                        PRELE(p);
                        return (0);
                }
                if (p != curproc) {
                        lwkt_gettoken_shared(&p->p_token);
                        if (!CANSIGNAL(p, sig, 1)) {
                                lwkt_reltoken(&p->p_token);
                                PRELE(p);
                                return (EPERM);
                        }
                        lwkt_reltoken(&p->p_token);
                }

                /*
                 * NOP if the process is exiting.  Note that lwpsignal() is
                 * called directly with P_WEXIT set to kill individual LWPs
                 * during exit, which is allowed.
                 */
                if (p->p_flags & P_WEXIT) {
                        PRELE(p);
                        return (0);
                }
                if (tid != -1) {
                        lwkt_gettoken_shared(&p->p_token);
                        lp = lwp_rb_tree_RB_LOOKUP(&p->p_lwp_tree, tid);
                        if (lp == NULL) {
                                lwkt_reltoken(&p->p_token);
                                PRELE(p);
                                return (ESRCH);
                        }
                        LWPHOLD(lp);
                        lwkt_reltoken(&p->p_token);
                }
                if (sig)
                        lwpsignal(p, lp, sig);
                if (lp)
                        LWPRELE(lp);
                PRELE(p);

                return (0);
        }

        /*
         * If we come here, pid is a special broadcast pid.
         * This doesn't mix with a tid.
         */
        if (tid != -1)
                return (EINVAL);

        switch (pid) {
        case -1:                /* broadcast signal */
                t = (dokillpg(sig, 0, 1));
                break;
        case 0:                 /* signal own process group */
                t = (dokillpg(sig, 0, 0));
                break;
        default:                /* negative explicit process group */
                t = (dokillpg(sig, -pid, 0));
                break;
        }
        return t;
}

int
sys_kill(struct sysmsg *sysmsg, const struct kill_args *uap)
{
        int error;

        error = kern_kill(uap->signum, uap->pid, -1);
        return (error);
}

int
sys_lwp_kill(struct sysmsg *sysmsg, const struct lwp_kill_args *uap)
{
        int error;
        pid_t pid = uap->pid;

        /*
         * A tid is mandatory for lwp_kill(), otherwise
         * you could simply use kill().
         */
        if (uap->tid == -1)
                return (EINVAL);

        /*
         * To save on a getpid() function call for intra-process
         * signals, pid == -1 means current process.
         */
        if (pid == -1)
                pid = curproc->p_pid;

        error = kern_kill(uap->signum, pid, uap->tid);
        return (error);
}

/*
 * Send a signal to a process group.
 */
void
gsignal(int pgid, int sig)
{
        struct pgrp *pgrp;

        if (pgid && (pgrp = pgfind(pgid)))
                pgsignal(pgrp, sig, 0);
}

/*
 * Send a signal to a process group.  If checktty is 1,
 * limit to members which have a controlling terminal.
 *
 * pg_lock interlocks against a fork that might be in progress, to
 * ensure that the new child process picks up the signal.
 */
void
pgsignal(struct pgrp *pgrp, int sig, int checkctty)
{
        struct proc *p;

        /*
         * Must interlock all signals against fork
         */
        if (pgrp) {
                pgref(pgrp);
                lockmgr(&pgrp->pg_lock, LK_EXCLUSIVE);
                LIST_FOREACH(p, &pgrp->pg_members, p_pglist) {
                        if (checkctty == 0 || p->p_flags & P_CONTROLT)
                                ksignal(p, sig);
                }
                lockmgr(&pgrp->pg_lock, LK_RELEASE);
                pgrel(pgrp);
        }
}

/*
 * Send a signal caused by a trap to the current lwp.  If it will be caught
 * immediately, deliver it with correct code.  Otherwise, post it normally.
 *
 * These signals may ONLY be delivered to the specified lwp and may never
 * be delivered to the process generically.
 *
 * lpmap->blockallsigs is ignored.
 */
void
trapsignal(struct lwp *lp, int sig, u_long code)
{
        struct proc *p = lp->lwp_proc;
        struct sigacts *ps = p->p_sigacts;

        /*
         * If we are a virtual kernel running an emulated user process
         * context, switch back to the virtual kernel context before
         * trying to post the signal.
         */
        if (lp->lwp_vkernel && lp->lwp_vkernel->ve) {
                struct trapframe *tf = lp->lwp_md.md_regs;
                tf->tf_trapno = 0;
                vkernel_trap(lp, tf);
        }

        if ((p->p_flags & P_TRACED) == 0 && SIGISMEMBER(p->p_sigcatch, sig) &&
            !SIGISMEMBER(lp->lwp_sigmask, sig)) {
                lp->lwp_ru.ru_nsignals++;
#ifdef KTRACE
                if (KTRPOINT(lp->lwp_thread, KTR_PSIG))
                        ktrpsig(lp, sig, ps->ps_sigact[_SIG_IDX(sig)],
                                &lp->lwp_sigmask, code);
#endif
                (*p->p_sysent->sv_sendsig)(ps->ps_sigact[_SIG_IDX(sig)], sig,
                                                &lp->lwp_sigmask, code);
                SIGSETOR(lp->lwp_sigmask, ps->ps_catchmask[_SIG_IDX(sig)]);
                if (!SIGISMEMBER(ps->ps_signodefer, sig))
                        SIGADDSET(lp->lwp_sigmask, sig);
                if (SIGISMEMBER(ps->ps_sigreset, sig)) {
                        /*
                         * See kern_sigaction() for origin of this code.
                         */
                        SIGDELSET(p->p_sigcatch, sig);
                        if (sig != SIGCONT &&
                            sigprop(sig) & SA_IGNORE)
                                SIGADDSET(p->p_sigignore, sig);
                        ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL;
                }
        } else {
                lp->lwp_code = code;    /* XXX for core dump/debugger */
                lp->lwp_sig = sig;      /* XXX to verify code */
                lwpsignal(p, lp, sig);
        }
}

/*
 * Find a suitable lwp to deliver the signal to.  Returns NULL if all
 * lwps hold the signal blocked.
 *
 * Caller must hold p->p_token.
 *
 * Returns a lp or NULL.  If non-NULL the lp is held and its token is
 * acquired.
 */
static struct lwp *
find_lwp_for_signal(struct proc *p, int sig)
{
        struct lwp *lp;
        struct lwp *run, *sleep, *stop;

        /*
         * If the running/preempted thread belongs to the proc to which
         * the signal is being delivered and this thread does not block
         * the signal, then we can avoid a context switch by delivering
         * the signal to this thread, because it will return to userland
         * soon anyways.
         */
        lp = lwkt_preempted_proc();
        if (lp != NULL && lp->lwp_proc == p) {
                LWPHOLD(lp);
                lwkt_gettoken(&lp->lwp_token);
                if (!SIGISMEMBER(lp->lwp_sigmask, sig)) {
                        /* return w/ token held */
                        return (lp);
                }
                lwkt_reltoken(&lp->lwp_token);
                LWPRELE(lp);
        }

        run = sleep = stop = NULL;
        FOREACH_LWP_IN_PROC(lp, p) {
                /*
                 * If the signal is being blocked by the lwp, then this
                 * lwp is not eligible for receiving the signal.
                 */
                LWPHOLD(lp);
                lwkt_gettoken(&lp->lwp_token);

                if (SIGISMEMBER(lp->lwp_sigmask, sig)) {
                        lwkt_reltoken(&lp->lwp_token);
                        LWPRELE(lp);
                        continue;
                }

                switch (lp->lwp_stat) {
                case LSRUN:
                        if (sleep) {
                                lwkt_token_swap();
                                lwkt_reltoken(&sleep->lwp_token);
                                LWPRELE(sleep);
                                sleep = NULL;
                                run = lp;
                        } else if (stop) {
                                lwkt_token_swap();
                                lwkt_reltoken(&stop->lwp_token);
                                LWPRELE(stop);
                                stop = NULL;
                                run = lp;
                        } else {
                                run = lp;
                        }
                        break;
                case LSSLEEP:
                        if (lp->lwp_flags & LWP_SINTR) {
                                if (sleep) {
                                        lwkt_reltoken(&lp->lwp_token);
                                        LWPRELE(lp);
                                } else if (stop) {
                                        lwkt_token_swap();
                                        lwkt_reltoken(&stop->lwp_token);
                                        LWPRELE(stop);
                                        stop = NULL;
                                        sleep = lp;
                                } else {
                                        sleep = lp;
                                }
                        } else {
                                lwkt_reltoken(&lp->lwp_token);
                                LWPRELE(lp);
                        }
                        break;
                case LSSTOP:
                        if (sleep) {
                                lwkt_reltoken(&lp->lwp_token);
                                LWPRELE(lp);
                        } else if (stop) {
                                lwkt_reltoken(&lp->lwp_token);
                                LWPRELE(lp);
                        } else {
                                stop = lp;
                        }
                        break;
                }
                if (run)
                        break;
        }

        if (run != NULL)
                return (run);
        else if (sleep != NULL)
                return (sleep);
        else
                return (stop);
}

/*
 * Send the signal to the process.  If the signal has an action, the action
 * is usually performed by the target process rather than the caller; we add
 * the signal to the set of pending signals for the process.
 *
 * Exceptions:
 *   o When a stop signal is sent to a sleeping process that takes the
 *     default action, the process is stopped without awakening it.
 *   o SIGCONT restarts stopped processes (or puts them back to sleep)
 *     regardless of the signal action (eg, blocked or ignored).
 *
 * Other ignored signals are discarded immediately.
 *
 * If the caller wishes to call this function from a hard code section the
 * caller must already hold p->p_token (see kern_clock.c).
 *
 * No requirements.
 */
void
ksignal(struct proc *p, int sig)
{
        lwpsignal(p, NULL, sig);
}

/*
 * The core for ksignal.  lp may be NULL, then a suitable thread
 * will be chosen.  If not, lp MUST be a member of p.
 *
 * If the caller wishes to call this function from a hard code section the
 * caller must already hold p->p_token.
 *
 * No requirements.
 */
void
lwpsignal(struct proc *p, struct lwp *lp, int sig)
{
        struct proc *q;
        sig_t action;
        int prop;

        KASSERT(_SIG_VALID(sig), ("%s: invalid signal %d", __func__, sig));
        KKASSERT(lp == NULL || lp->lwp_proc == p);

        /*
         * We don't want to race... well, all sorts of things.  Get appropriate
         * tokens.
         *
         * Don't try to deliver a generic signal to an exiting process,
         * the signal structures could be in flux.  We check the LWP later
         * on.
         */
        PHOLD(p);
        if (lp) {
                LWPHOLD(lp);
                lwkt_gettoken(&lp->lwp_token);
        } else {
                lwkt_gettoken(&p->p_token);
                if (p->p_flags & P_WEXIT)
                        goto out;
        }

        prop = sigprop(sig);

        /*
         * If proc is traced, always give parent a chance;
         * if signal event is tracked by procfs, give *that*
         * a chance, as well.
         */
        if ((p->p_flags & P_TRACED) || (p->p_stops & S_SIG)) {
                action = SIG_DFL;
        } else {
                /*
                 * Do not try to deliver signals to an exiting lwp other
                 * than SIGKILL.  Note that we must still deliver the signal
                 * if P_WEXIT is set in the process flags.
                 */
                if (lp && (lp->lwp_mpflags & LWP_MP_WEXIT) && sig != SIGKILL)
                        goto out;

                /*
                 * If the signal is being ignored, then we forget about
                 * it immediately.  NOTE: We don't set SIGCONT in p_sigignore,
                 * and if it is set to SIG_IGN, action will be SIG_DFL here.
                 */
                if (SIGISMEMBER(p->p_sigignore, sig)) {
                        /*
                         * Even if a signal is set SIG_IGN, it may still be
                         * lurking in a kqueue.
                         */
                        KNOTE(&p->p_klist, NOTE_SIGNAL | sig);
                        goto out;
                }

                if (SIGISMEMBER(p->p_sigcatch, sig))
                        action = SIG_CATCH;
                else
                        action = SIG_DFL;
        }

        /*
         * If continuing, clear any pending STOP signals for the whole
         * process.
         */
        if (prop & SA_CONT) {
                lwkt_gettoken(&p->p_token);
                SIG_STOPSIGMASK_ATOMIC(p->p_siglist);
                lwkt_reltoken(&p->p_token);
        }

        if (prop & SA_STOP) {
                /*
                 * If sending a tty stop signal to a member of an orphaned
                 * process group, discard the signal here if the action
                 * is default; don't stop the process below if sleeping,
                 * and don't clear any pending SIGCONT.
                 */
                if ((prop & SA_TTYSTOP) && p->p_pgrp->pg_jobc == 0 &&
                    action == SIG_DFL)
                        goto out;

                lwkt_gettoken(&p->p_token);
                SIG_CONTSIGMASK_ATOMIC(p->p_siglist);
                p->p_flags &= ~P_CONTINUED;
                lwkt_reltoken(&p->p_token);
        }

        if (p->p_stat == SSTOP) {
                /*
                 * Nobody can handle this signal, add it to the lwp or
                 * process pending list
                 */
                lwkt_gettoken(&p->p_token);
                if (p->p_stat != SSTOP) {
                        lwkt_reltoken(&p->p_token);
                        goto not_stopped;
                }

                sigsetfrompid(curthread, p, sig);
                if (lp) {
                        spin_lock(&lp->lwp_spin);
                        SIGADDSET(lp->lwp_siglist, sig);
                        spin_unlock(&lp->lwp_spin);
                } else {
                        SIGADDSET_ATOMIC(p->p_siglist, sig);
                }

                /*
                 * If the process is stopped and is being traced, then no
                 * further action is necessary.
                 */
                if (p->p_flags & P_TRACED) {
                        lwkt_reltoken(&p->p_token);
                        goto out;
                }

                /*
                 * If the process is stopped and receives a KILL signal,
                 * make the process runnable.
                 */
                if (sig == SIGKILL) {
                        proc_unstop(p, SSTOP);
                        lwkt_reltoken(&p->p_token);
                        goto active_process;
                }

                /*
                 * If the process is stopped and receives a CONT signal,
                 * then try to make the process runnable again.
                 */
                if (prop & SA_CONT) {
                        /*
                         * If SIGCONT is default (or ignored), we continue the
                         * process but don't leave the signal in p_siglist, as
                         * it has no further action.  If SIGCONT is held, we
                         * continue the process and leave the signal in
                         * p_siglist.  If the process catches SIGCONT, let it
                         * handle the signal itself.
                         *
                         * XXX what if the signal is being held blocked?
                         *
                         * Token required to interlock kern_wait().
                         * Reparenting can also cause a race so we have to
                         * hold (q).
                         */
                        q = p->p_pptr;
                        PHOLD(q);
                        lwkt_gettoken(&q->p_token);
                        p->p_flags |= P_CONTINUED;
                        wakeup(q);
                        if (action == SIG_DFL)
                                SIGDELSET_ATOMIC(p->p_siglist, sig);
                        proc_unstop(p, SSTOP);
                        lwkt_reltoken(&q->p_token);
                        PRELE(q);
                        lwkt_reltoken(&p->p_token);
                        if (action == SIG_CATCH)
                                goto active_process;
                        goto out;
                }

                /*
                 * If the process is stopped and receives another STOP
                 * signal, we do not need to stop it again.  If we did
                 * the shell could get confused.
                 *
                 * However, if the current/preempted lwp is part of the
                 * process receiving the signal, we need to keep it,
                 * so that this lwp can stop in issignal() later, as
                 * we don't want to wait until it reaches userret!
                 */
                if (prop & SA_STOP) {
                        if (lwkt_preempted_proc() == NULL ||
                            lwkt_preempted_proc()->lwp_proc != p) {
                                SIGDELSET_ATOMIC(p->p_siglist, sig);
                        }
                }

                /*
                 * Otherwise the process is stopped and it received some
                 * signal, which does not change its stopped state.  When
                 * the process is continued a wakeup(p) will be issued which
                 * will wakeup any threads sleeping in tstop().
                 */
                lwkt_reltoken(&p->p_token);
                goto out;
        }
        /* else not stopped */
not_stopped:
        ;
active_process:

        /*
         * Never deliver a lwp-specific signal to a random lwp.
         *
         * When delivering an untargetted signal, use p_sigirefs to
         * inform lwps of potential collisions.
         */
        if (lp == NULL) {
                /* NOTE: returns lp w/ token held */
                sigirefs_hold(p);
                lp = find_lwp_for_signal(p, sig);
                if (lp) {
                        if (SIGISMEMBER(lp->lwp_sigmask, sig)) {
                                lwkt_reltoken(&lp->lwp_token);
                                LWPRELE(lp);
                                lp = NULL;
                                /* maintain proc token */
                                /* maintain sigirefs */
                        } else {
                                lwkt_token_swap();
                                lwkt_reltoken(&p->p_token);
                                /* maintain lp token */
                                sigirefs_drop(p);
                        }
                }
        }

        /*
         * Deliver to the process generically if (1) the signal is being
         * sent to any thread or (2) we could not find a thread to deliver
         * it to.
         *
         * Drop p_sigirefs after the signal has been resolved to interlock
         * against sigsuspend/ppoll/pselect.
         */
        if (lp == NULL) {
                sigsetfrompid(curthread, p, sig);
                KNOTE(&p->p_klist, NOTE_SIGNAL | sig);
                SIGADDSET_ATOMIC(p->p_siglist, sig);
                sigirefs_drop(p);
                goto out;
        }

        /*
         * Deliver to a specific LWP whether it masks it or not.  It will
         * not be dispatched if masked but we must still deliver it.
         */
        if (p->p_nice > NZERO && action == SIG_DFL && (prop & SA_KILL) &&
            (p->p_flags & P_TRACED) == 0) {
                lwkt_gettoken(&p->p_token);
                p->p_nice = NZERO;
                lwkt_reltoken(&p->p_token);
        }

        /*
         * If the process receives a STOP signal which indeed needs to
         * stop the process, do so.  If the process chose to catch the
         * signal, it will be treated like any other signal.
         */
        if ((prop & SA_STOP) && action == SIG_DFL) {
                /*
                 * If a child holding parent blocked, stopping
                 * could cause deadlock.  Take no action at this
                 * time.
                 */
                lwkt_gettoken(&p->p_token);
                if (p->p_flags & P_PPWAIT) {
                        sigsetfrompid(curthread, p, sig);
                        SIGADDSET_ATOMIC(p->p_siglist, sig);
                        lwkt_reltoken(&p->p_token);
                        goto out;
                }

                /*
                 * Do not actually try to manipulate the process, but simply
                 * stop it.  Lwps will stop as soon as they safely can.
                 *
                 * Ignore stop if the process is exiting.
                 */
                if ((p->p_flags & P_WEXIT) == 0) {
                        p->p_xstat = sig;
                        proc_stop(p, SSTOP);
                }
                lwkt_reltoken(&p->p_token);
                goto out;
        }

        /*
         * If it is a CONT signal with default action, just ignore it.
         */
        if ((prop & SA_CONT) && action == SIG_DFL)
                goto out;

        /*
         * Mark signal pending at this specific thread.
         */
        sigsetfrompid(curthread, p, sig);
        spin_lock(&lp->lwp_spin);
        SIGADDSET(lp->lwp_siglist, sig);
        spin_unlock(&lp->lwp_spin);

        lwp_signotify(lp);

out:
        if (lp) {
                lwkt_reltoken(&lp->lwp_token);
                LWPRELE(lp);
        } else {
                lwkt_reltoken(&p->p_token);
        }
        PRELE(p);
}

/*
 * Notify the LWP that a signal has arrived.  The LWP does not have to be
 * sleeping on the current cpu.
 *
 * p->p_token and lp->lwp_token must be held on call.
 *
 * We can only safely schedule the thread on its current cpu and only if
 * one of the SINTR flags is set.  If an SINTR flag is set AND we are on
 * the correct cpu we are properly interlocked, otherwise we could be
 * racing other thread transition states (or the lwp is on the user scheduler
 * runq but not scheduled) and must not do anything.
 *
 * Since we hold the lwp token we know the lwp cannot be ripped out from
 * under us so we can safely hold it to prevent it from being ripped out
 * from under us if we are forced to IPI another cpu to make the local
 * checks there.
 *
 * Adjustment of lp->lwp_stat can only occur when we hold the lwp_token,
 * which we won't in an IPI so any fixups have to be done here, effectively
 * replicating part of what setrunnable() does.
 */
static void
lwp_signotify(struct lwp *lp)
{
        thread_t dtd;

        ASSERT_LWKT_TOKEN_HELD(&lp->lwp_token);
        dtd = lp->lwp_thread;

        crit_enter();
        if (lp == lwkt_preempted_proc()) {
                /*
                 * lwp is on the current cpu AND it is currently running
                 * (we preempted it).
                 */
                signotify();
        } else if (lp->lwp_flags & LWP_SINTR) {
                /*
                 * lwp is sitting in tsleep() with PCATCH set
                 */
                if (dtd->td_gd == mycpu) {
                        setrunnable(lp);
                } else {
                        /*
                         * We can only adjust lwp_stat while we hold the
                         * lwp_token, and we won't in the IPI function.
                         */
                        LWPHOLD(lp);
                        if (lp->lwp_stat == LSSTOP)
                                lp->lwp_stat = LSSLEEP;
                        lwkt_send_ipiq(dtd->td_gd, lwp_signotify_remote, lp);
                }
        } else if (dtd->td_flags & TDF_SINTR) {
                /*
                 * lwp is sitting in lwkt_sleep() with PCATCH set.
                 */
                if (dtd->td_gd == mycpu) {
                        setrunnable(lp);
                } else {
                        /*
                         * We can only adjust lwp_stat while we hold the
                         * lwp_token, and we won't in the IPI function.
                         */
                        LWPHOLD(lp);
                        if (lp->lwp_stat == LSSTOP)
                                lp->lwp_stat = LSSLEEP;
                        lwkt_send_ipiq(dtd->td_gd, lwp_signotify_remote, lp);
                }
        } else {
                /*
                 * Otherwise the lwp is either in some uninterruptible state
                 * or it is on the userland scheduler's runqueue waiting to
                 * be scheduled to a cpu, or it is running in userland.  We
                 * generally want to send an IPI so a running target gets the
                 * signal ASAP, otherwise a scheduler-tick worth of latency
                 * will occur.
                 *
                 * Issue an IPI to the remote cpu to knock it into the kernel,
                 * remote cpu will issue the cpu-local signotify() if the IPI
                 * preempts the desired thread.
                 */
                if (dtd->td_gd != mycpu) {
                        LWPHOLD(lp);
                        lwkt_send_ipiq(dtd->td_gd, lwp_signotify_remote, lp);
                }
        }
        crit_exit();
}

/*
 * This function is called via an IPI so we cannot call setrunnable() here
 * (because while we hold the lp we don't own its token, and can't get it
 * from an IPI).
 *
 * We are interlocked by virtue of being on the same cpu as the target.  If
 * we still are and LWP_SINTR or TDF_SINTR is set we can safely schedule
 * the target thread.
 */
static void
lwp_signotify_remote(void *arg)
{
        struct lwp *lp = arg;
        thread_t td = lp->lwp_thread;

        if (lp == lwkt_preempted_proc()) {
                signotify();
                LWPRELE(lp);
        } else if (td->td_gd == mycpu) {
                if ((lp->lwp_flags & LWP_SINTR) ||
                    (td->td_flags & TDF_SINTR)) {
                        lwkt_schedule(td);
                }
                LWPRELE(lp);
        } else {
                lwkt_send_ipiq(td->td_gd, lwp_signotify_remote, lp);
                /* LWPHOLD() is forwarded to the target cpu */
        }
}

/*
 * Caller must hold p->p_token
 */
void
proc_stop(struct proc *p, int stat)
{
        struct proc *q;
        struct lwp *lp;

        ASSERT_LWKT_TOKEN_HELD(&p->p_token);

        /*
         * If somebody raced us, be happy with it.  SCORE overrides SSTOP.
         */
        if (stat == SCORE) {
                if (p->p_stat == SCORE || p->p_stat == SZOMB)
                        return;
        } else {
                if (p->p_stat == SSTOP || p->p_stat == SCORE ||
                    p->p_stat == SZOMB) {
                        return;
                }
        }
        p->p_stat = stat;

        FOREACH_LWP_IN_PROC(lp, p) {
                LWPHOLD(lp);
                lwkt_gettoken(&lp->lwp_token);

                switch (lp->lwp_stat) {
                case LSSTOP:
                        /*
                         * Do nothing, we are already counted in
                         * p_nstopped.
                         */
                        break;

                case LSSLEEP:
                        /*
                         * We're sleeping, but we will stop before
                         * returning to userspace, so count us
                         * as stopped as well.  We set LWP_MP_WSTOP
                         * to signal the lwp that it should not
                         * increase p_nstopped when reaching tstop().
                         *
                         * LWP_MP_WSTOP is protected by lp->lwp_token.
                         */
                        if ((lp->lwp_mpflags & LWP_MP_WSTOP) == 0) {
                                atomic_set_int(&lp->lwp_mpflags, LWP_MP_WSTOP);
                                ++p->p_nstopped;
                        }
                        break;

                case LSRUN:
                        /*
                         * We might notify ourself, but that's not
                         * a problem.
                         */
                        lwp_signotify(lp);
                        break;
                }
                lwkt_reltoken(&lp->lwp_token);
                LWPRELE(lp);
        }

        if (p->p_nstopped == p->p_nthreads) {
                /*
                 * Token required to interlock kern_wait().  Reparenting can
                 * also cause a race so we have to hold (q).
                 */
                q = p->p_pptr;
                PHOLD(q);
                lwkt_gettoken(&q->p_token);
                p->p_flags &= ~P_WAITED;
                wakeup(q);
                if ((q->p_sigacts->ps_flag & PS_NOCLDSTOP) == 0)
                        ksignal(p->p_pptr, SIGCHLD);
                lwkt_reltoken(&q->p_token);
                PRELE(q);
        }
}

/*
 * Caller must hold p_token
 */
void
proc_unstop(struct proc *p, int stat)
{
        struct lwp *lp;

        ASSERT_LWKT_TOKEN_HELD(&p->p_token);

        if (p->p_stat != stat)
                return;

        p->p_stat = SACTIVE;

        FOREACH_LWP_IN_PROC(lp, p) {
                LWPHOLD(lp);
                lwkt_gettoken(&lp->lwp_token);

                switch (lp->lwp_stat) {
                case LSRUN:
                        /*
                         * Uh?  Not stopped?  Well, I guess that's okay.
                         */
                        if (bootverbose)
                                kprintf("proc_unstop: lwp %d/%d not sleeping\n",
                                        p->p_pid, lp->lwp_tid);
                        break;

                case LSSLEEP:
                        /*
                         * Still sleeping.  Don't bother waking it up.
                         * However, if this thread was counted as
                         * stopped, undo this.
                         *
                         * Nevertheless we call setrunnable() so that it
                         * will wake up in case a signal or timeout arrived
                         * in the meantime.
                         *
                         * LWP_MP_WSTOP is protected by lp->lwp_token.
                         */
                        if (lp->lwp_mpflags & LWP_MP_WSTOP) {
                                atomic_clear_int(&lp->lwp_mpflags,
                                                 LWP_MP_WSTOP);
                                --p->p_nstopped;
                        } else {
                                if (bootverbose)
                                        kprintf("proc_unstop: lwp %d/%d sleeping, not stopped\n",
                                                p->p_pid, lp->lwp_tid);
                        }
                        /* FALLTHROUGH */

                case LSSTOP:
                        /*
                         * This handles any lwp's waiting in a tsleep with
                         * SIGCATCH.
                         */
                        lwp_signotify(lp);
                        break;

                }
                lwkt_reltoken(&lp->lwp_token);
                LWPRELE(lp);
        }

        /*
         * This handles any lwp's waiting in tstop().  We have interlocked
         * the setting of p_stat by acquiring and releasing each lpw's
         * token.
         */
        wakeup(p);
}

/*
 * Wait for all threads except the current thread to stop.
 */
static void
proc_stopwait(struct proc *p)
{
        while ((p->p_stat == SSTOP || p->p_stat == SCORE) &&
               p->p_nstopped < p->p_nthreads - 1) {
                tsleep_interlock(&p->p_nstopped, 0);
                if (p->p_nstopped < p->p_nthreads - 1) {
                        tsleep(&p->p_nstopped, PINTERLOCKED, "stopwt", hz);
                }
        }
}

/*
 * No requirements.
 */
static int
kern_sigtimedwait(sigset_t waitset, siginfo_t *info, struct timespec *timeout)
{
        sigset_t savedmask, set;
        struct timespec rts, ets, ts;
        struct proc *p = curproc;
        struct lwp *lp = curthread->td_lwp;
        bool timevalid;
        int error, sig, hz;

        error = 0;
        sig = 0;
        SIG_CANTMASK(waitset);
        savedmask = lp->lwp_sigmask;

        timespecclear(&ets);
        timevalid = false;
        if (timeout != NULL) {
                if (timeout->tv_sec >= 0 && timeout->tv_nsec >= 0 &&
                    timeout->tv_nsec < 1000000000) {
                        timevalid = true;
                        getnanouptime(&rts);
                        timespecadd(&rts, timeout, &ets);
                }
        }

        for (;;) {
                set = lwp_sigpend(lp);
                SIGSETAND(set, waitset);
                if ((sig = sig_ffs(&set)) != 0) {
                        SIGFILLSET(lp->lwp_sigmask);
                        SIGDELSET(lp->lwp_sigmask, sig);
                        SIG_CANTMASK(lp->lwp_sigmask);
                        sig = issignal(lp, 1, NULL);
                        /*
                         * It may be a STOP signal, in the case, issignal
                         * returns 0, because we may stop there, and new
                         * signal can come in, we should restart if we got
                         * nothing.
                         */
                        if (sig == 0)
                                continue;
                        else
                                break;
                }

                /*
                 * Previous checking got nothing, and we retried but still
                 * got nothing, we should return the error status.
                 */
                if (error)
                        break;

                /*
                 * POSIX says this must be checked after looking for pending
                 * signals.
                 */
                if (timeout != NULL) {
                        if (!timevalid) {
                                error = EINVAL;
                                break;
                        }
                        getnanouptime(&rts);
                        if (timespeccmp(&rts, &ets, >=)) {
                                error = EAGAIN;
                                break;
                        }
                        timespecsub(&ets, &rts, &ts);
                        hz = tstohz_high(&ts);
                } else {
                        hz = 0;
                }

                lp->lwp_sigmask = savedmask;
                SIGSETNAND(lp->lwp_sigmask, waitset);
                sigirefs_wait(p);

                /*
                 * We won't ever be woken up.  Instead, our sleep will
                 * be broken in lwpsignal().
                 */
                error = tsleep(&p->p_sigacts, PCATCH, "sigwt", hz);
                if (timeout != NULL) {
                        if (error == ERESTART) {
                                /* can not restart a timeout wait. */
                                error = EINTR;
                        } else if (error == EAGAIN) {
                                /* will calculate timeout by ourself. */
                                error = 0;
                        }
                }
                /* Retry ... */
        }

        lp->lwp_sigmask = savedmask;
        sigirefs_wait(p);

        if (sig) {
                error = 0;
                bzero(info, sizeof(*info));
                info->si_signo = sig;
                spin_lock(&lp->lwp_spin);
                lwp_delsig(lp, sig, 1); /* take the signal! */
                spin_unlock(&lp->lwp_spin);

#ifdef KTRACE
                if (KTRPOINT(lp->lwp_thread, KTR_PSIG)) {
                        struct sigacts *ps = p->p_sigacts;
                        sig_t action = ps->ps_sigact[_SIG_IDX(sig)];
                        ktrpsig(lp, sig, action,
                                ((lp->lwp_flags & LWP_OLDMASK) ?
                                 &lp->lwp_oldsigmask : &lp->lwp_sigmask),
                                0);
                }
#endif

                if (sig == SIGKILL) {
                        sigexit(lp, sig);
                        /* NOT REACHED */
                }
        }

        return (error);
}

/*
 * MPALMOSTSAFE
 */
int
sys_sigtimedwait(struct sysmsg *sysmsg, const struct sigtimedwait_args *uap)
{
        struct timespec ts;
        struct timespec *timeout;
        sigset_t set;
        siginfo_t info;
        int error;

        if (uap->timeout) {
                error = copyin(uap->timeout, &ts, sizeof(ts));
                if (error)
                        return (error);
                timeout = &ts;
        } else {
                timeout = NULL;
        }
        error = copyin(uap->set, &set, sizeof(set));
        if (error)
                return (error);
        error = kern_sigtimedwait(set, &info, timeout);
        if (error)
                return (error);
        if (uap->info)
                error = copyout(&info, uap->info, sizeof(info));
        /* Repost if we got an error. */
        /*
         * XXX lwp
         *
         * This could transform a thread-specific signal to another
         * thread / process pending signal.
         */
        if (error) {
                ksignal(curproc, info.si_signo);
        } else {
                sysmsg->sysmsg_result = info.si_signo;
        }
        return (error);
}

/*
 * MPALMOSTSAFE
 */
int
sys_sigwaitinfo(struct sysmsg *sysmsg, const struct sigwaitinfo_args *uap)
{
        siginfo_t info;
        sigset_t set;
        int error;

        error = copyin(uap->set, &set, sizeof(set));
        if (error)
                return (error);
        error = kern_sigtimedwait(set, &info, NULL);
        if (error)
                return (error);
        if (uap->info)
                error = copyout(&info, uap->info, sizeof(info));
        /* Repost if we got an error. */
        /*
         * XXX lwp
         *
         * This could transform a thread-specific signal to another
         * thread / process pending signal.
         */
        if (error) {
                ksignal(curproc, info.si_signo);
        } else {
                sysmsg->sysmsg_result = info.si_signo;
        }
        return (error);
}

/*
 * If the current process has received a signal that would interrupt a
 * system call, return EINTR or ERESTART as appropriate.
 */
int
iscaught(struct lwp *lp)
{
        struct proc *p = lp->lwp_proc;
        int sig;

        if (p) {
                if ((sig = CURSIG(lp)) != 0) {
                        if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
                                return (EINTR);
                        return (ERESTART);
                }
        }
        return(EWOULDBLOCK);
}

/*
 * If the current lwp/proc has received a signal (should be caught or cause
 * termination, should interrupt current syscall), return the signal number.
 * Stop signals with default action are processed immediately, then cleared;
 * they aren't returned.  This is checked after each entry to the system for
 * a syscall or trap (though this can usually be done without calling issignal
 * by checking the pending signal masks in the CURSIG macro).
 *
 * This routine is called via CURSIG/__cursig.  We will acquire and release
 * p->p_token but if the caller needs to interlock the test the caller must
 * also hold p->p_token.
 *
 *      while (sig = CURSIG(curproc))
 *              postsig(sig);
 */
int
issignal(struct lwp *lp, int maytrace, int *ptokp)
{
        struct proc *p = lp->lwp_proc;
        sigset_t mask;
        int sig, prop;
        int haveptok;

        for (;;) {
                int traced = (p->p_flags & P_TRACED) || (p->p_stops & S_SIG);

                haveptok = 0;

                /*
                 * NOTE: Do not tstop here.  Issue the proc_stop()
                 *       so other parties see that we know we need
                 *       to stop, but don't block here.  Locks might
                 *       be held.
                 *
                 * XXX If this process is supposed to stop, stop this thread.
                 *     removed.
                 */
#if 0
                if (STOPLWP(p, lp)) {
                        lwkt_gettoken(&p->p_token);
                        tstop();
                        lwkt_reltoken(&p->p_token);
                }
#endif

                /*
                 * Quick check without token
                 */
                mask = lwp_sigpend(lp);
                SIGSETNAND(mask, lp->lwp_sigmask);
                if (p->p_flags & P_PPWAIT)
                        SIG_STOPSIGMASK(mask);
                SIG_CONDBLOCKALLSIGS(mask, lp);

                if (SIGISEMPTY(mask))           /* no signal to send */
                        return (0);

                /*
                 * If the signal is a member of the process signal set
                 * we need p_token (even if it is also a member of the
                 * lwp signal set).
                 */
                sig = sig_ffs(&mask);
                if (SIGISMEMBER(p->p_siglist, sig)) {
                        /*
                         * Recheck with token
                         */
                        haveptok = 1;
                        lwkt_gettoken(&p->p_token);

                        mask = lwp_sigpend(lp);
                        SIGSETNAND(mask, lp->lwp_sigmask);
                        if (p->p_flags & P_PPWAIT)
                                SIG_STOPSIGMASK(mask);
                        if (SIGISEMPTY(mask)) {         /* no signal to send */
                                /* haveptok is TRUE */
                                lwkt_reltoken(&p->p_token);
                                return (0);
                        }
                        sig = sig_ffs(&mask);
                }

                STOPEVENT(p, S_SIG, sig);

                /*
                 * We should see pending but ignored signals
                 * only if P_TRACED was on when they were posted.
                 */
                if (SIGISMEMBER(p->p_sigignore, sig) && (traced == 0)) {
                        spin_lock(&lp->lwp_spin);
                        lwp_delsig(lp, sig, haveptok);
                        spin_unlock(&lp->lwp_spin);
                        if (haveptok)
                                lwkt_reltoken(&p->p_token);
                        continue;
                }
                if (maytrace &&
                    (p->p_flags & P_TRACED) &&
                    (p->p_flags & P_PPWAIT) == 0) {
                        /*
                         * If traced, always stop, and stay stopped until
                         * released by the parent.
                         *
                         * NOTE: SSTOP may get cleared during the loop, but
                         *       we do not re-notify the parent if we have
                         *       to loop several times waiting for the parent
                         *       to let us continue.  XXX not sure if this is
                         *       still true.
                         *
                         * NOTE: Do not tstop here.  Issue the proc_stop()
                         *       so other parties see that we know we need
                         *       to stop, but don't block here.  Locks might
                         *       be held.
                         */
                        if (haveptok == 0) {
                                lwkt_gettoken(&p->p_token);
                                haveptok = 1;
                        }
                        p->p_xstat = sig;
                        proc_stop(p, SSTOP);

                        /*
                         * Normally we don't stop until we return to userland,
                         * but make an exception when tracing and 'maytrace'
                         * is asserted.
                         */
                        if (p->p_flags & P_TRACED)
                                tstop();

                        /*
                         * If parent wants us to take the signal,
                         * then it will leave it in p->p_xstat;
                         * otherwise we just look for signals again.
                         */
                        spin_lock(&lp->lwp_spin);
                        lwp_delsig(lp, sig, 1); /* clear old signal */
                        spin_unlock(&lp->lwp_spin);
                        sig = p->p_xstat;
                        if (sig == 0) {
                                /* haveptok is TRUE */
                                lwkt_reltoken(&p->p_token);
                                continue;
                        }

                        /*
                         * Put the new signal into p_siglist.  If the
                         * signal is being masked, look for other signals.
                         *
                         * XXX lwp might need a call to ksignal()
                         */
                        SIGADDSET_ATOMIC(p->p_siglist, sig);
                        if (SIGISMEMBER(lp->lwp_sigmask, sig)) {
                                /* haveptok is TRUE */
                                lwkt_reltoken(&p->p_token);
                                continue;
                        }

                        /*
                         * If the traced bit got turned off, go back up
                         * to the top to rescan signals.  This ensures
                         * that p_sig* and ps_sigact are consistent.
                         */
                        if ((p->p_flags & P_TRACED) == 0) {
                                /* haveptok is TRUE */
                                lwkt_reltoken(&p->p_token);
                                continue;
                        }
                }

                /*
                 * p_token may be held here
                 */
                prop = sigprop(sig);

                /*
                 * Decide whether the signal should be returned.
                 * Return the signal's number, or fall through
                 * to clear it from the pending mask.
                 */
                switch ((intptr_t)p->p_sigacts->ps_sigact[_SIG_IDX(sig)]) {
                case (intptr_t)SIG_DFL:
                        /*
                         * Don't take default actions on system processes.
                         */
                        if (p->p_pid <= 1) {
#ifdef DIAGNOSTIC
                                /*
                                 * Are you sure you want to ignore SIGSEGV
                                 * in init? XXX
                                 */
                                kprintf("Process (pid %lu) got signal %d\n",
                                        (u_long)p->p_pid, sig);
#endif
                                break;          /* == ignore */
                        }

                        /*
                         * Handle the in-kernel checkpoint action
                         */
                        if (prop & SA_CKPT) {
                                if (haveptok == 0) {
                                        lwkt_gettoken(&p->p_token);
                                        haveptok = 1;
                                }
                                checkpoint_signal_handler(lp);
                                break;
                        }

                        /*
                         * If there is a pending stop signal to process
                         * with default action, stop here,
                         * then clear the signal.  However,
                         * if process is member of an orphaned
                         * process group, ignore tty stop signals.
                         */
                        if (prop & SA_STOP) {
                                if (haveptok == 0) {
                                        lwkt_gettoken(&p->p_token);
                                        haveptok = 1;
                                }
                                if (p->p_flags & P_TRACED ||
                                    (p->p_pgrp->pg_jobc == 0 &&
                                    prop & SA_TTYSTOP))
                                        break;  /* == ignore */
                                if ((p->p_flags & P_WEXIT) == 0) {
                                        /*
                                         * NOTE: We do not block here.  Issue
                                         *       stopthe stop so other parties
                                         *       see that we know we need to
                                         *       stop.  Locks might be held.
                                         */
                                        p->p_xstat = sig;
                                        proc_stop(p, SSTOP);

#if 0
                                        tstop();
#endif
                                }
                                break;
                        } else if (prop & SA_IGNORE) {
                                /*
                                 * Except for SIGCONT, shouldn't get here.
                                 * Default action is to ignore; drop it.
                                 */
                                break;          /* == ignore */
                        } else {
                                if (ptokp)
                                        *ptokp = haveptok;
                                else if (haveptok)
                                        lwkt_reltoken(&p->p_token);
                                return (sig);
                        }

                        /*NOTREACHED*/

                case (intptr_t)SIG_IGN:
                        /*
                         * Masking above should prevent us ever trying
                         * to take action on an ignored signal other
                         * than SIGCONT, unless process is traced.
                         */
                        if ((prop & SA_CONT) == 0 &&
                            (p->p_flags & P_TRACED) == 0)
                                kprintf("%s: should not hit signal %d!\n",
                                        __func__, sig);
                        break;          /* == ignore */

                default:
                        /*
                         * This signal has an action, let
                         * postsig() process it.
                         */
                        if (ptokp)
                                *ptokp = haveptok;
                        else if (haveptok)
                                lwkt_reltoken(&p->p_token);
                        return (sig);
                }
                spin_lock(&lp->lwp_spin);
                lwp_delsig(lp, sig, haveptok);          /* take the signal! */
                spin_unlock(&lp->lwp_spin);

                if (haveptok)
                        lwkt_reltoken(&p->p_token);
        }
        /* NOTREACHED */
}

/*
 * Take the action for the specified signal from the current set of
 * pending signals.
 *
 * haveptok indicates whether the caller is holding p->p_token.  If the
 * caller is, we are responsible for releasing it.
 *
 * This routine can only be called from the top-level trap from usermode.
 * It is expecting to be able to modify the top-level stack frame.
 */
void
postsig(int sig, int haveptok)
{
        struct lwp *lp = curthread->td_lwp;
        struct proc *p = lp->lwp_proc;
        struct sigacts *ps = p->p_sigacts;
        sig_t action;
        sigset_t returnmask;
        int code;

        KASSERT(_SIG_VALID(sig), ("%s: invalid signal %d", __func__, sig));

        /*
         * If we are a virtual kernel running an emulated user process
         * context, switch back to the virtual kernel context before
         * trying to post the signal.
         */
        if (lp->lwp_vkernel && lp->lwp_vkernel->ve) {
                struct trapframe *tf = lp->lwp_md.md_regs;
                tf->tf_trapno = 0;
                vkernel_trap(lp, tf);
        }

        KNOTE(&p->p_klist, NOTE_SIGNAL | sig);

        spin_lock(&lp->lwp_spin);
        lwp_delsig(lp, sig, haveptok);
        spin_unlock(&lp->lwp_spin);
        action = ps->ps_sigact[_SIG_IDX(sig)];
#ifdef KTRACE
        if (KTRPOINT(lp->lwp_thread, KTR_PSIG)) {
                ktrpsig(lp, sig, action,
                        ((lp->lwp_flags & LWP_OLDMASK) ?
                         &lp->lwp_oldsigmask : &lp->lwp_sigmask),
                        0);
        }
#endif
        /*
         * We don't need p_token after this point.
         */
        if (haveptok)
                lwkt_reltoken(&p->p_token);

        STOPEVENT(p, S_SIG, sig);

        if (action == SIG_DFL) {
                /*
                 * Default action, where the default is to kill
                 * the process.  (Other cases were ignored above.)
                 */
                sigexit(lp, sig);
                /* NOTREACHED */
        } else {
                /*
                 * If we get here, the signal must be caught.
                 */
                KASSERT(action != SIG_IGN && !SIGISMEMBER(lp->lwp_sigmask, sig),
                    ("postsig action"));

                /*
                 * Reset the signal handler if asked to
                 */
                if (SIGISMEMBER(ps->ps_sigreset, sig)) {
                        /*
                         * See kern_sigaction() for origin of this code.
                         */
                        SIGDELSET(p->p_sigcatch, sig);
                        if (sig != SIGCONT &&
                            sigprop(sig) & SA_IGNORE)
                                SIGADDSET(p->p_sigignore, sig);
                        ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL;
                }

                /*
                 * Set the signal mask and calculate the mask to restore
                 * when the signal function returns.
                 *
                 * Special case: user has done a sigsuspend.  Here the
                 * current mask is not of interest, but rather the
                 * mask from before the sigsuspend is what we want
                 * restored after the signal processing is completed.
                 */
                if (lp->lwp_flags & LWP_OLDMASK) {
                        returnmask = lp->lwp_oldsigmask;
                        lp->lwp_flags &= ~LWP_OLDMASK;
                } else {
                        returnmask = lp->lwp_sigmask;
                }

                SIGSETOR(lp->lwp_sigmask, ps->ps_catchmask[_SIG_IDX(sig)]);
                if (!SIGISMEMBER(ps->ps_signodefer, sig))
                        SIGADDSET(lp->lwp_sigmask, sig);

                lp->lwp_ru.ru_nsignals++;
                if (lp->lwp_sig != sig) {
                        code = 0;
                } else {
                        code = lp->lwp_code;
                        lp->lwp_code = 0;
                        lp->lwp_sig = 0;
                }
                (*p->p_sysent->sv_sendsig)(action, sig, &returnmask, code);
        }
}

/*
 * Kill the current process for stated reason.
 */
void
killproc(struct proc *p, char *why)
{
        log(LOG_ERR, "pid %d (%s), uid %d, was killed: %s\n",
                p->p_pid, p->p_comm,
                p->p_ucred ? p->p_ucred->cr_uid : -1, why);
        ksignal(p, SIGKILL);
}

/*
 * Force the current process to exit with the specified signal, dumping core
 * if appropriate.  We bypass the normal tests for masked and caught signals,
 * allowing unrecoverable failures to terminate the process without changing
 * signal state.  Mark the accounting record with the signal termination.
 * If dumping core, save the signal number for the debugger.  Calls exit and
 * does not return.
 *
 * This routine does not return.
 */
void
sigexit(struct lwp *lp, int sig)
{
        struct proc *p = lp->lwp_proc;

        lwkt_gettoken(&p->p_token);
        p->p_acflag |= AXSIG;
        if (sigprop(sig) & SA_CORE) {
                lp->lwp_sig = sig;

                /*
                 * All threads must be stopped before we can safely coredump.
                 * Stop threads using SCORE, which cannot be overridden.
                 */
                if (p->p_stat != SCORE) {
                        proc_stop(p, SCORE);
                        proc_stopwait(p);

                        if (coredump(lp, sig) == 0)
                                sig |= WCOREFLAG;
                        p->p_stat = SSTOP;
                }

                /*
                 * Log signals which would cause core dumps
                 * (Log as LOG_INFO to appease those who don't want
                 * these messages.)
                 * XXX : Todo, as well as euid, write out ruid too
                 */
                if (kern_logsigexit) {
                        log(LOG_INFO,
                            "pid %d (%s), uid %d: exited on signal %d%s\n",
                            p->p_pid, p->p_comm,
                            p->p_ucred ? p->p_ucred->cr_uid : -1,
                            sig &~ WCOREFLAG,
                            sig & WCOREFLAG ? " (core dumped)" : "");
                        if (kern_logsigexit > 1)
                                kprintf("DEBUG - waiting on kern.logsigexit\n");
                        while (kern_logsigexit > 1) {
                                tsleep(&kern_logsigexit, 0, "DEBUG", hz);
                        }
                }
        }
        lwkt_reltoken(&p->p_token);
        exit1(W_EXITCODE(0, sig));
        /* NOTREACHED */
}

static char corefilename[MAXPATHLEN+1] = "%N.core";
SYSCTL_STRING(_kern, OID_AUTO, corefile, CTLFLAG_RW, corefilename,
              sizeof(corefilename), "process corefile name format string");

/*
 * expand_name(name, uid, pid)
 * Expand the name described in corefilename, using name, uid, and pid.
 * corefilename is a kprintf-like string, with three format specifiers:
 *      %N      name of process ("name")
 *      %P      process id (pid)
 *      %U      user id (uid)
 * For example, "%N.core" is the default; they can be disabled completely
 * by using "/dev/null", or all core files can be stored in "/cores/%U/%N-%P".
 * This is controlled by the sysctl variable kern.corefile (see above).
 */

static char *
expand_name(const char *name, uid_t uid, pid_t pid)
{
        char *temp;
        char buf[11];           /* Buffer for pid/uid -- max 4B */
        int i, l, n;
        char *format = corefilename;
        size_t namelen;

        temp = kmalloc(MAXPATHLEN + 1, M_TEMP, M_NOWAIT);
        if (temp == NULL)
                return NULL;

        namelen = strlen(name);
        for (i = 0, n = 0; n < MAXPATHLEN && format[i]; i++) {
                switch (format[i]) {
                case '%':       /* Format character */
                        i++;
                        switch (format[i]) {
                        case '%':
                                temp[n++] = '%';
                                break;
                        case 'N':       /* process name */
                                if ((n + namelen) > MAXPATHLEN) {
                                        log(LOG_ERR,
                                            "pid %d (%s), uid (%u): "
                                            "Path `%s%s' is too long\n",
                                            pid, name, uid, temp, name);
                                        kfree(temp, M_TEMP);
                                        return NULL;
                                }
                                memcpy(temp+n, name, namelen);
                                n += namelen;
                                break;
                        case 'P':       /* process id */
                                l = ksprintf(buf, "%u", pid);
                                if ((n + l) > MAXPATHLEN) {
                                        log(LOG_ERR,
                                            "pid %d (%s), uid (%u): "
                                            "Path `%s%s' is too long\n",
                                            pid, name, uid, temp, name);
                                        kfree(temp, M_TEMP);
                                        return NULL;
                                }
                                memcpy(temp+n, buf, l);
                                n += l;
                                break;
                        case 'U':       /* user id */
                                l = ksprintf(buf, "%u", uid);
                                if ((n + l) > MAXPATHLEN) {
                                        log(LOG_ERR,
                                            "pid %d (%s), uid (%u): "
                                            "Path `%s%s' is too long\n",
                                            pid, name, uid, temp, name);
                                        kfree(temp, M_TEMP);
                                        return NULL;
                                }
                                memcpy(temp+n, buf, l);
                                n += l;
                                break;
                        default:
                                log(LOG_ERR,
                                    "Unknown format character %c in `%s'\n",
                                    format[i], format);
                        }
                        break;
                default:
                        temp[n++] = format[i];
                }
        }
        temp[n] = '\0';
        return temp;
}

/*
 * Dump a process' core.  The main routine does some
 * policy checking, and creates the name of the coredump;
 * then it passes on a vnode and a size limit to the process-specific
 * coredump routine if there is one; if there _is not_ one, it returns
 * ENOSYS; otherwise it returns the error from the process-specific routine.
 *
 * The parameter `lp' is the lwp which triggered the coredump.
 */

static int
coredump(struct lwp *lp, int sig)
{
        struct proc *p = lp->lwp_proc;
        struct vnode *vp;
        struct ucred *cred = p->p_ucred;
        struct flock lf;
        struct nlookupdata nd;
        struct vattr vattr;
        int error, error1;
        char *name;                     /* name of corefile */
        off_t limit;

        STOPEVENT(p, S_CORE, 0);

        if (((sugid_coredump == 0) && (p->p_flags & P_SUGID)) ||
            do_coredump == 0)
        {
                return (EFAULT);
        }

        /*
         * Note that the bulk of limit checking is done after
         * the corefile is created.  The exception is if the limit
         * for corefiles is 0, in which case we don't bother
         * creating the corefile at all.  This layout means that
         * a corefile is truncated instead of not being created,
         * if it is larger than the limit.
         */
        limit = p->p_rlimit[RLIMIT_CORE].rlim_cur;
        if (limit == 0)
                return EFBIG;

        name = expand_name(p->p_comm, p->p_ucred->cr_uid, p->p_pid);
        if (name == NULL)
                return (EINVAL);
        error = nlookup_init(&nd, name, UIO_SYSSPACE, NLC_LOCKVP);
        if (error == 0)
                error = vn_open(&nd, NULL,
                                O_CREAT | FWRITE | O_NOFOLLOW,
                                S_IRUSR | S_IWUSR);
        kfree(name, M_TEMP);
        if (error) {
                nlookup_done(&nd);
                return (error);
        }
        vp = nd.nl_open_vp;
        nd.nl_open_vp = NULL;
        nlookup_done(&nd);

        vn_unlock(vp);
        lf.l_whence = SEEK_SET;
        lf.l_start = 0;
        lf.l_len = 0;
        lf.l_type = F_WRLCK;
        error = VOP_ADVLOCK(vp, (caddr_t)p, F_SETLK, &lf, 0);
        if (error)
                goto out2;

        /* Don't dump to non-regular files or files with links. */
        if (vp->v_type != VREG ||
            VOP_GETATTR(vp, &vattr) || vattr.va_nlink != 1) {
                error = EFAULT;
                goto out1;
        }

        /* Don't dump to files current user does not own */
        if (vattr.va_uid != p->p_ucred->cr_uid) {
                error = EFAULT;
                goto out1;
        }

        VATTR_NULL(&vattr);
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        vattr.va_size = 0;
        VOP_SETATTR(vp, &vattr, cred);
        p->p_acflag |= ACORE;
        vn_unlock(vp);

        error = p->p_sysent->sv_coredump ?
                p->p_sysent->sv_coredump(lp, sig, vp, limit) : ENOSYS;

out1:
        lf.l_type = F_UNLCK;
        VOP_ADVLOCK(vp, (caddr_t)p, F_UNLCK, &lf, 0);
out2:
        error1 = vn_close(vp, FWRITE, NULL);
        if (error == 0)
                error = error1;
        return (error);
}

/*
 * Nonexistent system call-- signal process (may want to handle it).
 * Flag error in case process won't see signal immediately (blocked or ignored).
 *
 * MPALMOSTSAFE
 */
/* ARGSUSED */
int
sys_nosys(struct sysmsg *sysmsg, const struct nosys_args *args)
{
        lwpsignal(curproc, curthread->td_lwp, SIGSYS);
        return (EINVAL);
}

/*
 * Send a SIGIO or SIGURG signal to a process or process group using
 * stored credentials rather than those of the current process.
 */
void
pgsigio(struct sigio *sigio, int sig, int checkctty)
{
        if (sigio == NULL)
                return;

        if (sigio->sio_pgid > 0) {
                if (CANSIGIO(sigio->sio_ruid, sigio->sio_ucred,
                             sigio->sio_proc))
                        ksignal(sigio->sio_proc, sig);
        } else if (sigio->sio_pgid < 0) {
                struct proc *p;
                struct pgrp *pg = sigio->sio_pgrp;

                /*
                 * Must interlock all signals against fork
                 */
                pgref(pg);
                lockmgr(&pg->pg_lock, LK_EXCLUSIVE);
                LIST_FOREACH(p, &pg->pg_members, p_pglist) {
                        if (CANSIGIO(sigio->sio_ruid, sigio->sio_ucred, p) &&
                            (checkctty == 0 || (p->p_flags & P_CONTROLT)))
                                ksignal(p, sig);
                }
                lockmgr(&pg->pg_lock, LK_RELEASE);
                pgrel(pg);
        }
}

static int
filt_sigattach(struct knote *kn)
{
        struct proc *p = curproc;

        kn->kn_ptr.p_proc = p;
        kn->kn_flags |= EV_CLEAR;               /* automatically set */

        /* XXX lock the proc here while adding to the list? */
        knote_insert(&p->p_klist, kn);

        return (0);
}

static void
filt_sigdetach(struct knote *kn)
{
        struct proc *p = kn->kn_ptr.p_proc;

        knote_remove(&p->p_klist, kn);
}

/*
 * signal knotes are shared with proc knotes, so we apply a mask to
 * the hint in order to differentiate them from process hints.  This
 * could be avoided by using a signal-specific knote list, but probably
 * isn't worth the trouble.
 */
static int
filt_signal(struct knote *kn, long hint)
{
        if (hint & NOTE_SIGNAL) {
                hint &= ~NOTE_SIGNAL;

                if (kn->kn_id == hint)
                        kn->kn_data++;
        }
        return (kn->kn_data != 0);
}