/*      $NetBSD: kern_time.c,v 1.232 2026/03/15 12:00:58 yamt Exp $     */

/*-
 * Copyright (c) 2000, 2004, 2005, 2007, 2008, 2009, 2020
 *     The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christopher G. Demetriou, by Andrew Doran, and by Jason R. Thorpe.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * Copyright (c) 1982, 1986, 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, 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_time.c 8.4 (Berkeley) 5/26/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_time.c,v 1.232 2026/03/15 12:00:58 yamt Exp $");

#include <sys/param.h>
#include <sys/types.h>

#include <sys/callout.h>
#include <sys/cpu.h>
#include <sys/errno.h>
#include <sys/intr.h>
#include <sys/kauth.h>
#include <sys/kernel.h>
#include <sys/kmem.h>
#include <sys/lwp.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/resourcevar.h>
#include <sys/sdt.h>
#include <sys/signal.h>
#include <sys/signalvar.h>
#include <sys/syscallargs.h>
#include <sys/syslog.h>
#include <sys/systm.h>
#include <sys/timetc.h>
#include <sys/timevar.h>
#include <sys/timex.h>
#include <sys/vnode.h>

#include <machine/limits.h>

kmutex_t        itimer_mutex __cacheline_aligned;       /* XXX static */
static struct itlist itimer_realtime_changed_notify;

static void     itimer_callout(void *);
static void     ptimer_intr(void *);
static void     *ptimer_sih __read_mostly;
static TAILQ_HEAD(, ptimer) ptimer_queue;

#define CLOCK_VIRTUAL_P(clockid)        \
        ((clockid) == CLOCK_VIRTUAL || (clockid) == CLOCK_PROF)

#define IS_ITIMER(id) (0 <= (id) && (id) < TIMER_MIN)
#define IS_POSIX_TIMER(id)  (TIMER_MIN <= (id) && (id) < TIMER_MAX)

CTASSERT(ITIMER_REAL == CLOCK_REALTIME);
CTASSERT(ITIMER_VIRTUAL == CLOCK_VIRTUAL);
CTASSERT(ITIMER_PROF == CLOCK_PROF);
CTASSERT(ITIMER_MONOTONIC == CLOCK_MONOTONIC);

CTASSERT(IS_ITIMER(ITIMER_REAL));
CTASSERT(IS_ITIMER(ITIMER_VIRTUAL));
CTASSERT(IS_ITIMER(ITIMER_PROF));
CTASSERT(IS_ITIMER(ITIMER_MONOTONIC));

CTASSERT(!IS_POSIX_TIMER(ITIMER_REAL));
CTASSERT(!IS_POSIX_TIMER(ITIMER_VIRTUAL));
CTASSERT(!IS_POSIX_TIMER(ITIMER_PROF));
CTASSERT(!IS_POSIX_TIMER(ITIMER_MONOTONIC));

/*
 * Initialize timekeeping.
 */
void
time_init(void)
{

        mutex_init(&itimer_mutex, MUTEX_DEFAULT, IPL_SCHED);
        LIST_INIT(&itimer_realtime_changed_notify);

        TAILQ_INIT(&ptimer_queue);
        ptimer_sih = softint_establish(SOFTINT_CLOCK | SOFTINT_MPSAFE,
            ptimer_intr, NULL);
}

/*
 * Check if the time will wrap if set to ts.
 *
 * ts - timespec describing the new time
 * delta - the delta between the current time and ts
 */
bool
time_wraps(struct timespec *ts, struct timespec *delta)
{

        /*
         * Don't allow the time to be set forward so far it
         * will wrap and become negative, thus allowing an
         * attacker to bypass the next check below.  The
         * cutoff is 1 year before rollover occurs, so even
         * if the attacker uses adjtime(2) to move the time
         * past the cutoff, it will take a very long time
         * to get to the wrap point.
         */
        if ((ts->tv_sec > LLONG_MAX - 365*24*60*60) ||
            (delta->tv_sec < 0 || delta->tv_nsec < 0))
                return true;

        return false;
}

/*
 * itimer_lock:
 *
 *      Acquire the interval timer data lock.
 */
void
itimer_lock(void)
{
        mutex_spin_enter(&itimer_mutex);
}

/*
 * itimer_unlock:
 *
 *      Release the interval timer data lock.
 */
void
itimer_unlock(void)
{
        mutex_spin_exit(&itimer_mutex);
}

/*
 * itimer_lock_held:
 *
 *      Check that the interval timer lock is held for diagnostic
 *      assertions.
 */
inline bool __diagused
itimer_lock_held(void)
{
        return mutex_owned(&itimer_mutex);
}

/*
 * Time of day and interval timer support.
 *
 * These routines provide the kernel entry points to get and set
 * the time-of-day and per-process interval timers.  Subroutines
 * here provide support for adding and subtracting timeval structures
 * and decrementing interval timers, optionally reloading the interval
 * timers when they expire.
 */

/* This function is used by clock_settime and settimeofday */
static int
settime1(struct proc *p, const struct timespec *ts, bool check_kauth)
{
        struct timespec delta, now;

        /*
         * The time being set to an unreasonable value will cause
         * unreasonable system behaviour.
         */
        if (ts->tv_sec < 0 || ts->tv_sec > (1LL << 36))
                return SET_ERROR(EINVAL);

        nanotime(&now);
        timespecsub(ts, &now, &delta);

        if (check_kauth && kauth_authorize_system(kauth_cred_get(),
            KAUTH_SYSTEM_TIME, KAUTH_REQ_SYSTEM_TIME_SYSTEM, __UNCONST(ts),
            &delta, KAUTH_ARG(check_kauth ? false : true)) != 0) {
                return SET_ERROR(EPERM);
        }

#ifdef notyet
        if ((delta.tv_sec < 86400) && securelevel > 0) { /* XXX elad - notyet */
                return SET_ERROR(EPERM);
        }
#endif

        tc_setclock(ts);

        resettodr();

        /*
         * Notify pending CLOCK_REALTIME timers about the real time change.
         * There may be inactive timers on this list, but this happens
         * comparatively less often than timers firing, and so it's better
         * to put the extra checks here than to complicate the other code
         * path.
         */
        struct itimer *it;
        itimer_lock();
        LIST_FOREACH(it, &itimer_realtime_changed_notify, it_rtchgq) {
                KASSERT(it->it_ops->ito_realtime_changed != NULL);
                if (timespecisset(&it->it_time.it_value)) {
                        (*it->it_ops->ito_realtime_changed)(it);
                }
        }
        itimer_unlock();

        return 0;
}

int
settime(struct proc *p, struct timespec *ts)
{
        return settime1(p, ts, true);
}

/* ARGSUSED */
int
sys___clock_gettime50(struct lwp *l,
    const struct sys___clock_gettime50_args *uap, register_t *retval)
{
        /* {
                syscallarg(clockid_t) clock_id;
                syscallarg(struct timespec *) tp;
        } */
        int error;
        struct timespec ats;

        error = clock_gettime1(SCARG(uap, clock_id), &ats);
        if (error != 0)
                return error;

        return copyout(&ats, SCARG(uap, tp), sizeof(ats));
}

/* ARGSUSED */
int
sys___clock_settime50(struct lwp *l,
    const struct sys___clock_settime50_args *uap, register_t *retval)
{
        /* {
                syscallarg(clockid_t) clock_id;
                syscallarg(const struct timespec *) tp;
        } */
        int error;
        struct timespec ats;

        if ((error = copyin(SCARG(uap, tp), &ats, sizeof(ats))) != 0)
                return error;

        return clock_settime1(l->l_proc, SCARG(uap, clock_id), &ats, true);
}


int
clock_settime1(struct proc *p, clockid_t clock_id, const struct timespec *tp,
    bool check_kauth)
{
        int error;

        if (tp->tv_nsec < 0 || tp->tv_nsec >= 1000000000L)
                return SET_ERROR(EINVAL);

        switch (clock_id) {
        case CLOCK_REALTIME:
                if ((error = settime1(p, tp, check_kauth)) != 0)
                        return error;
                break;
        case CLOCK_MONOTONIC:
                return SET_ERROR(EINVAL);       /* read-only clock */
        default:
                return SET_ERROR(EINVAL);
        }

        return 0;
}

int
sys___clock_getres50(struct lwp *l, const struct sys___clock_getres50_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(clockid_t) clock_id;
                syscallarg(struct timespec *) tp;
        } */
        struct timespec ts;
        int error;

        if ((error = clock_getres1(SCARG(uap, clock_id), &ts)) != 0)
                return error;

        if (SCARG(uap, tp))
                error = copyout(&ts, SCARG(uap, tp), sizeof(ts));

        return error;
}

int
clock_getres1(clockid_t clock_id, struct timespec *ts)
{

        switch (clock_id) {
        case CLOCK_REALTIME:
        case CLOCK_MONOTONIC:
        case CLOCK_PROCESS_CPUTIME_ID:
        case CLOCK_THREAD_CPUTIME_ID:
                ts->tv_sec = 0;
                if (tc_getfrequency() > 1000000000)
                        ts->tv_nsec = 1;
                else
                        ts->tv_nsec = 1000000000 / tc_getfrequency();
                break;
        default:
                return SET_ERROR(EINVAL);
        }

        return 0;
}

/* ARGSUSED */
int
sys___nanosleep50(struct lwp *l, const struct sys___nanosleep50_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(struct timespec *) rqtp;
                syscallarg(struct timespec *) rmtp;
        } */
        struct timespec rmt, rqt;
        int error, error1;

        error = copyin(SCARG(uap, rqtp), &rqt, sizeof(struct timespec));
        if (error)
                return error;

        error = nanosleep1(l, CLOCK_MONOTONIC, 0, &rqt,
            SCARG(uap, rmtp) ? &rmt : NULL);
        if (SCARG(uap, rmtp) == NULL || (error != 0 && error != EINTR))
                return error;

        error1 = copyout(&rmt, SCARG(uap, rmtp), sizeof(rmt));
        return error1 ? error1 : error;
}

/* ARGSUSED */
int
sys_clock_nanosleep(struct lwp *l, const struct sys_clock_nanosleep_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(clockid_t) clock_id;
                syscallarg(int) flags;
                syscallarg(struct timespec *) rqtp;
                syscallarg(struct timespec *) rmtp;
        } */
        struct timespec rmt, rqt;
        int error, error1;

        error = copyin(SCARG(uap, rqtp), &rqt, sizeof(struct timespec));
        if (error)
                goto out;

        error = nanosleep1(l, SCARG(uap, clock_id), SCARG(uap, flags), &rqt,
            SCARG(uap, rmtp) ? &rmt : NULL);
        if (SCARG(uap, rmtp) == NULL || (error != 0 && error != EINTR))
                goto out;

        if ((SCARG(uap, flags) & TIMER_ABSTIME) == 0 &&
            (error1 = copyout(&rmt, SCARG(uap, rmtp), sizeof(rmt))) != 0)
                error = error1;
out:
        *retval = error;
        return 0;
}

int
nanosleep1(struct lwp *l, clockid_t clock_id, int flags, struct timespec *rqt,
    struct timespec *rmt)
{
        struct timespec rmtstart;
        int error, timo;

        if ((error = ts2timo(clock_id, flags, rqt, &timo, &rmtstart)) != 0) {
                if (error == ETIMEDOUT) {
                        error = 0;
                        if (rmt != NULL)
                                rmt->tv_sec = rmt->tv_nsec = 0;
                }
                return error;
        }

        /*
         * Avoid inadvertently sleeping forever
         */
        if (timo == 0)
                timo = 1;
again:
        error = kpause("nanoslp", true, timo, NULL);
        if (error == EWOULDBLOCK)
                error = 0;
        if (rmt != NULL || error == 0) {
                struct timespec rmtend;
                struct timespec t0;
                struct timespec *t;
                int err;

                err = clock_gettime1(clock_id, &rmtend);
                if (err != 0)
                        return err;

                t = (rmt != NULL) ? rmt : &t0;
                if (flags & TIMER_ABSTIME) {
                        timespecsub(rqt, &rmtend, t);
                } else {
                        if (timespeccmp(&rmtend, &rmtstart, <))
                                timespecclear(t); /* clock wound back */
                        else
                                timespecsub(&rmtend, &rmtstart, t);
                        if (timespeccmp(rqt, t, <))
                                timespecclear(t);
                        else
                                timespecsub(rqt, t, t);
                }
                if (t->tv_sec < 0)
                        timespecclear(t);
                if (error == 0) {
                        timo = tstohz(t);
                        if (timo > 0)
                                goto again;
                }
        }

        if (error == ERESTART)
                error = SET_ERROR(EINTR);

        return error;
}

int
sys_clock_getcpuclockid2(struct lwp *l,
    const struct sys_clock_getcpuclockid2_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(idtype_t idtype;
                syscallarg(id_t id);
                syscallarg(clockid_t *)clock_id;
        } */
        pid_t pid;
        lwpid_t lid;
        clockid_t clock_id;
        id_t id = SCARG(uap, id);

        switch (SCARG(uap, idtype)) {
        case P_PID:
                pid = id == 0 ? l->l_proc->p_pid : id;
                clock_id = CLOCK_PROCESS_CPUTIME_ID | pid;
                break;
        case P_LWPID:
                lid = id == 0 ? l->l_lid : id;
                clock_id = CLOCK_THREAD_CPUTIME_ID | lid;
                break;
        default:
                return SET_ERROR(EINVAL);
        }
        return copyout(&clock_id, SCARG(uap, clock_id), sizeof(clock_id));
}

/* ARGSUSED */
int
sys___gettimeofday50(struct lwp *l, const struct sys___gettimeofday50_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(struct timeval *) tp;
                syscallarg(void *) tzp;         really "struct timezone *";
        } */
        struct timeval atv;
        int error = 0;
        struct timezone tzfake;

        if (SCARG(uap, tp)) {
                memset(&atv, 0, sizeof(atv));
                microtime(&atv);
                error = copyout(&atv, SCARG(uap, tp), sizeof(atv));
                if (error)
                        return error;
        }
        if (SCARG(uap, tzp)) {
                /*
                 * NetBSD has no kernel notion of time zone, so we just
                 * fake up a timezone struct and return it if demanded.
                 */
                tzfake.tz_minuteswest = 0;
                tzfake.tz_dsttime = 0;
                error = copyout(&tzfake, SCARG(uap, tzp), sizeof(tzfake));
        }
        return error;
}

/* ARGSUSED */
int
sys___settimeofday50(struct lwp *l, const struct sys___settimeofday50_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(const struct timeval *) tv;
                syscallarg(const void *) tzp; really "const struct timezone *";
        } */

        return settimeofday1(SCARG(uap, tv), true, SCARG(uap, tzp), l, true);
}

int
settimeofday1(const struct timeval *utv, bool userspace,
    const void *utzp, struct lwp *l, bool check_kauth)
{
        struct timeval atv;
        struct timespec ts;
        int error;

        /* Verify all parameters before changing time. */

        /*
         * NetBSD has no kernel notion of time zone, and only an
         * obsolete program would try to set it, so we log a warning.
         */
        if (utzp)
                log(LOG_WARNING, "pid %d attempted to set the "
                    "(obsolete) kernel time zone\n", l->l_proc->p_pid);

        if (utv == NULL)
                return 0;

        if (userspace) {
                if ((error = copyin(utv, &atv, sizeof(atv))) != 0)
                        return error;
                utv = &atv;
        }

        if (utv->tv_usec < 0 || utv->tv_usec >= 1000000)
                return SET_ERROR(EINVAL);

        TIMEVAL_TO_TIMESPEC(utv, &ts);
        return settime1(l->l_proc, &ts, check_kauth);
}

int     time_adjusted;                  /* set if an adjustment is made */

/* ARGSUSED */
int
sys___adjtime50(struct lwp *l, const struct sys___adjtime50_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(const struct timeval *) delta;
                syscallarg(struct timeval *) olddelta;
        } */
        int error;
        struct timeval atv, oldatv;

        if ((error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_TIME,
            KAUTH_REQ_SYSTEM_TIME_ADJTIME, NULL, NULL, NULL)) != 0)
                return error;

        if (SCARG(uap, delta)) {
                error = copyin(SCARG(uap, delta), &atv,
                    sizeof(*SCARG(uap, delta)));
                if (error)
                        return error;
        }
        adjtime1(SCARG(uap, delta) ? &atv : NULL,
            SCARG(uap, olddelta) ? &oldatv : NULL, l->l_proc);
        if (SCARG(uap, olddelta))
                error = copyout(&oldatv, SCARG(uap, olddelta),
                    sizeof(*SCARG(uap, olddelta)));
        return error;
}

void
adjtime1(const struct timeval *delta, struct timeval *olddelta, struct proc *p)
{

        if (olddelta) {
                memset(olddelta, 0, sizeof(*olddelta));
                mutex_spin_enter(&timecounter_lock);
                olddelta->tv_sec = time_adjtime / 1000000;
                olddelta->tv_usec = time_adjtime % 1000000;
                if (olddelta->tv_usec < 0) {
                        olddelta->tv_usec += 1000000;
                        olddelta->tv_sec--;
                }
                mutex_spin_exit(&timecounter_lock);
        }

        if (delta) {
                mutex_spin_enter(&timecounter_lock);
                /*
                 * XXX This should maybe just report failure to
                 * userland for nonsense deltas.
                 */
                if (delta->tv_sec > INT64_MAX/1000000 - 1) {
                        time_adjtime = INT64_MAX;
                } else if (delta->tv_sec < INT64_MIN/1000000 + 1) {
                        time_adjtime = INT64_MIN;
                } else {
                        time_adjtime = delta->tv_sec * 1000000
                            + MAX(-999999, MIN(999999, delta->tv_usec));
                }

                if (time_adjtime) {
                        /* We need to save the system time during shutdown */
                        time_adjusted |= 1;
                }
                mutex_spin_exit(&timecounter_lock);
        }
}

/*
 * Interval timer support.
 *
 * The itimer_*() routines provide generic support for interval timers,
 * both real (CLOCK_REALTIME, CLOCK_MONOTIME), and virtual (CLOCK_VIRTUAL,
 * CLOCK_PROF).
 *
 * Real timers keep their deadline as an absolute time, and are fired
 * by a callout.  Virtual timers are kept as a linked-list of deltas,
 * and are processed by hardclock().
 *
 * Because the real time timer callout may be delayed in real time due
 * to interrupt processing on the system, it is possible for the real
 * time timeout routine (itimer_callout()) run past after its deadline.
 * It does not suffice, therefore, to reload the real timer .it_value
 * from the timer's .it_interval.  Rather, we compute the next deadline
 * in absolute time based on the current time and the .it_interval value,
 * and report any overruns.
 *
 * Note that while the virtual timers are supported in a generic fashion
 * here, they only (currently) make sense as per-process timers, and thus
 * only really work for that case.
 */

/*
 * itimer_init:
 *
 *      Initialize the common data for an interval timer.
 */
void
itimer_init(struct itimer * const it, const struct itimer_ops * const ops,
    clockid_t const id, struct itlist * const itl)
{

        KASSERT(itimer_lock_held());
        KASSERT(ops != NULL);

        timespecclear(&it->it_time.it_value);
        it->it_ops = ops;
        it->it_clockid = id;
        it->it_overruns = 0;
        it->it_dying = false;
        if (!CLOCK_VIRTUAL_P(id)) {
                KASSERT(itl == NULL);
                callout_init(&it->it_ch, CALLOUT_MPSAFE);
                callout_setfunc(&it->it_ch, itimer_callout, it);
                if (id == CLOCK_REALTIME && ops->ito_realtime_changed != NULL) {
                        LIST_INSERT_HEAD(&itimer_realtime_changed_notify,
                            it, it_rtchgq);
                }
        } else {
                KASSERT(itl != NULL);
                it->it_vlist = itl;
                it->it_active = false;
        }
}

/*
 * itimer_poison:
 *
 *      Poison an interval timer, preventing it from being scheduled
 *      or processed, in preparation for freeing the timer.
 */
void
itimer_poison(struct itimer * const it)
{

        KASSERT(itimer_lock_held());

        it->it_dying = true;

        /*
         * For non-virtual timers, stop the callout, or wait for it to
         * run if it has already fired.  It cannot restart again after
         * this point: the callout won't restart itself when dying, no
         * other users holding the lock can restart it, and any other
         * users waiting for callout_halt concurrently (itimer_settime)
         * will restart from the top.
         */
        if (!CLOCK_VIRTUAL_P(it->it_clockid)) {
                callout_halt(&it->it_ch, &itimer_mutex);
                if (it->it_clockid == CLOCK_REALTIME &&
                    it->it_ops->ito_realtime_changed != NULL) {
                        LIST_REMOVE(it, it_rtchgq);
                }
        }
}

/*
 * itimer_fini:
 *
 *      Release resources used by an interval timer.
 *
 *      N.B. itimer_lock must be held on entry, and is released on exit.
 */
void
itimer_fini(struct itimer * const it)
{

        KASSERT(itimer_lock_held());

        /* All done with the global state. */
        itimer_unlock();

        /* Destroy the callout, if needed. */
        if (!CLOCK_VIRTUAL_P(it->it_clockid))
                callout_destroy(&it->it_ch);
}

/*
 * itimer_decr:
 *
 *      Decrement an interval timer by a specified number of nanoseconds,
 *      which must be less than a second, i.e. < 1000000000.  If the timer
 *      expires, then reload it.  In this case, carry over (nsec - old value)
 *      to reduce the value reloaded into the timer so that the timer does
 *      not drift.  This routine assumes that it is called in a context where
 *      the timers on which it is operating cannot change in value.
 *
 *      Returns true if the timer has expired.
 */
static bool
itimer_decr(struct itimer *it, int nsec)
{
        struct itimerspec *itp;
        int error __diagused;

        KASSERT(itimer_lock_held());
        KASSERT(CLOCK_VIRTUAL_P(it->it_clockid));

        itp = &it->it_time;
        if (itp->it_value.tv_nsec < nsec) {
                if (itp->it_value.tv_sec == 0) {
                        /* expired, and already in next interval */
                        nsec -= itp->it_value.tv_nsec;
                        goto expire;
                }
                itp->it_value.tv_nsec += 1000000000;
                itp->it_value.tv_sec--;
        }
        itp->it_value.tv_nsec -= nsec;
        nsec = 0;
        if (timespecisset(&itp->it_value))
                return false;
        /* expired, exactly at end of interval */
 expire:
        if (timespecisset(&itp->it_interval)) {
                itp->it_value = itp->it_interval;
                itp->it_value.tv_nsec -= nsec;
                if (itp->it_value.tv_nsec < 0) {
                        itp->it_value.tv_nsec += 1000000000;
                        itp->it_value.tv_sec--;
                }
                error = itimer_settime(it);
                KASSERT(error == 0); /* virtual, never fails */
        } else
                itp->it_value.tv_nsec = 0;              /* sec is already 0 */
        return true;
}

/*
 * itimer_arm_real:
 *
 *      Arm a non-virtual timer.
 */
static void
itimer_arm_real(struct itimer * const it)
{

        KASSERT(!it->it_dying);
        KASSERT(!CLOCK_VIRTUAL_P(it->it_clockid));
        KASSERT(!callout_pending(&it->it_ch));

        /*
         * Don't need to check tshzto() return value, here.
         * callout_schedule() does it for us.
         */
        callout_schedule(&it->it_ch,
            (it->it_clockid == CLOCK_MONOTONIC
                ? tshztoup(&it->it_time.it_value)
                : tshzto(&it->it_time.it_value)));
}

/*
 * itimer_callout:
 *
 *      Callout to expire a non-virtual timer.  Queue it up for processing,
 *      and then reload, if it is configured to do so.
 *
 *      N.B. A delay in processing this callout causes multiple
 *      SIGALRM calls to be compressed into one.
 */
static void
itimer_callout(void *arg)
{
        struct timespec now, next;
        struct itimer * const it = arg;
        int overruns;

        itimer_lock();
        (*it->it_ops->ito_fire)(it);

        if (!timespecisset(&it->it_time.it_interval)) {
                timespecclear(&it->it_time.it_value);
                itimer_unlock();
                return;
        }

        if (it->it_clockid == CLOCK_MONOTONIC) {
                getnanouptime(&now);
        } else {
                getnanotime(&now);
        }

        /*
         * Given the current itimer value and interval and the time
         * now, compute the next itimer value and count overruns.
         */
        itimer_transition(&it->it_time, &now, &next, &overruns);
        it->it_time.it_value = next;
        it->it_overruns += MIN(INT_MAX - overruns, overruns);

        /*
         * Reset the callout, if it's not going away.
         */
        if (!it->it_dying)
                itimer_arm_real(it);
        itimer_unlock();
}

/*
 * itimer_settime:
 *
 *      Set up the given interval timer. The value in it->it_time.it_value
 *      is taken to be an absolute time for CLOCK_REALTIME/CLOCK_MONOTONIC
 *      timers and a relative time for CLOCK_VIRTUAL/CLOCK_PROF timers.
 *
 *      If the callout had already fired but not yet run, fails with
 *      ERESTART -- caller must restart from the top to look up a timer.
 *
 *      Caller is responsible for validating it->it_value and
 *      it->it_interval, e.g. with itimerfix or itimespecfix.
 */
int
itimer_settime(struct itimer *it)
{
        struct itimer *itn, *pitn;
        struct itlist *itl;

        KASSERT(itimer_lock_held());
        KASSERT(!it->it_dying);
        KASSERT(it->it_time.it_value.tv_sec >= 0);
        KASSERT(it->it_time.it_value.tv_nsec >= 0);
        KASSERT(it->it_time.it_value.tv_nsec < 1000000000);
        KASSERT(it->it_time.it_interval.tv_sec >= 0);
        KASSERT(it->it_time.it_interval.tv_nsec >= 0);
        KASSERT(it->it_time.it_interval.tv_nsec < 1000000000);

        if (!CLOCK_VIRTUAL_P(it->it_clockid)) {
                /*
                 * Try to stop the callout.  However, if it had already
                 * fired, we have to drop the lock to wait for it, so
                 * the world may have changed and pt may not be there
                 * any more.  In that case, tell the caller to start
                 * over from the top.
                 */
                if (callout_halt(&it->it_ch, &itimer_mutex))
                        return SET_ERROR(ERESTART);
                KASSERT(!it->it_dying);

                /* Now we can touch it and start it up again. */
                if (timespecisset(&it->it_time.it_value))
                        itimer_arm_real(it);
        } else {
                if (it->it_active) {
                        itn = LIST_NEXT(it, it_list);
                        LIST_REMOVE(it, it_list);
                        for ( ; itn; itn = LIST_NEXT(itn, it_list))
                                timespecadd(&it->it_time.it_value,
                                    &itn->it_time.it_value,
                                    &itn->it_time.it_value);
                }
                if (timespecisset(&it->it_time.it_value)) {
                        itl = it->it_vlist;
                        for (itn = LIST_FIRST(itl), pitn = NULL;
                             itn && timespeccmp(&it->it_time.it_value,
                                 &itn->it_time.it_value, >);
                             pitn = itn, itn = LIST_NEXT(itn, it_list))
                                timespecsub(&it->it_time.it_value,
                                    &itn->it_time.it_value,
                                    &it->it_time.it_value);

                        if (pitn)
                                LIST_INSERT_AFTER(pitn, it, it_list);
                        else
                                LIST_INSERT_HEAD(itl, it, it_list);

                        for ( ; itn ; itn = LIST_NEXT(itn, it_list))
                                timespecsub(&itn->it_time.it_value,
                                    &it->it_time.it_value,
                                    &itn->it_time.it_value);

                        it->it_active = true;
                } else {
                        it->it_active = false;
                }
        }

        /* Success!  */
        return 0;
}

/*
 * itimer_gettime:
 *
 *      Return the remaining time of an interval timer.
 */
void
itimer_gettime(const struct itimer *it, struct itimerspec *aits)
{
        struct timespec now;
        struct itimer *itn;

        KASSERT(itimer_lock_held());
        KASSERT(!it->it_dying);

        *aits = it->it_time;
        if (!CLOCK_VIRTUAL_P(it->it_clockid)) {
                /*
                 * Convert from absolute to relative time in .it_value
                 * part of real time timer.  If time for real time
                 * timer has passed return 0, else return difference
                 * between current time and time for the timer to go
                 * off.
                 */
                if (timespecisset(&aits->it_value)) {
                        if (it->it_clockid == CLOCK_REALTIME) {
                                getnanotime(&now);
                        } else { /* CLOCK_MONOTONIC */
                                getnanouptime(&now);
                        }
                        if (timespeccmp(&aits->it_value, &now, <))
                                timespecclear(&aits->it_value);
                        else
                                timespecsub(&aits->it_value, &now,
                                    &aits->it_value);
                }
        } else if (it->it_active) {
                for (itn = LIST_FIRST(it->it_vlist); itn && itn != it;
                     itn = LIST_NEXT(itn, it_list))
                        timespecadd(&aits->it_value,
                            &itn->it_time.it_value, &aits->it_value);
                KASSERT(itn != NULL); /* it should be findable on the list */
        } else
                timespecclear(&aits->it_value);
}

/*
 * Per-process timer support.
 *
 * Both the BSD getitimer() family and the POSIX timer_*() family of
 * routines are supported.
 *
 * All timers are kept in an array pointed to by p_timers, which is
 * allocated on demand - many processes don't use timers at all. The
 * first four elements in this array are reserved for the BSD timers:
 * element 0 is ITIMER_REAL, element 1 is ITIMER_VIRTUAL, element
 * 2 is ITIMER_PROF, and element 3 is ITIMER_MONOTONIC. The rest may be
 * allocated by the timer_create() syscall.
 *
 * These timers are a "sub-class" of interval timer.
 */

/*
 * ptimer_free:
 *
 *      Free the per-process timer at the specified index.
 */
static void
ptimer_free(struct ptimers *pts, int index)
{
        struct itimer *it;
        struct ptimer *pt;

        KASSERT(itimer_lock_held());

        it = pts->pts_timers[index];
        pt = container_of(it, struct ptimer, pt_itimer);
        pts->pts_timers[index] = NULL;
        itimer_poison(it);

        /*
         * Remove it from the queue to be signalled.  Must be done
         * after itimer is poisoned, because we may have had to wait
         * for the callout to complete.
         */
        if (pt->pt_queued) {
                TAILQ_REMOVE(&ptimer_queue, pt, pt_chain);
                pt->pt_queued = false;
        }

        itimer_fini(it);        /* releases itimer_lock */
        kmem_free(pt, sizeof(*pt));
}

/*
 * ptimers_alloc:
 *
 *      Allocate a ptimers for the specified process.
 */
static struct ptimers *
ptimers_alloc(struct proc *p)
{
        struct ptimers *pts;
        int i;

        pts = kmem_alloc(sizeof(*pts), KM_SLEEP);
        LIST_INIT(&pts->pts_virtual);
        LIST_INIT(&pts->pts_prof);
        for (i = 0; i < TIMER_MAX; i++)
                pts->pts_timers[i] = NULL;
        itimer_lock();
        if (p->p_timers == NULL) {
                p->p_timers = pts;
                itimer_unlock();
                return pts;
        }
        itimer_unlock();
        kmem_free(pts, sizeof(*pts));
        return p->p_timers;
}

/*
 * ptimers_free:
 *
 *      Clean up the per-process timers. If "which" is set to TIMERS_ALL,
 *      then clean up all timers and free all the data structures. If
 *      "which" is set to TIMERS_POSIX, only clean up the timers allocated
 *      by timer_create(), not the BSD setitimer() timers, and only free the
 *      structure if none of those remain.
 *
 *      This function is exported because it is needed in the exec and
 *      exit code paths.
 */
void
ptimers_free(struct proc *p, int which)
{
        struct ptimers *pts;
        struct itimer *itn;
        struct timespec ts;
        int i;

        if (p->p_timers == NULL)
                return;

        pts = p->p_timers;
        itimer_lock();
        if (which == TIMERS_ALL) {
                p->p_timers = NULL;
                i = 0;
        } else {
                timespecclear(&ts);
                for (itn = LIST_FIRST(&pts->pts_virtual);
                     itn && itn != pts->pts_timers[ITIMER_VIRTUAL];
                     itn = LIST_NEXT(itn, it_list)) {
                        KASSERT(itn->it_clockid == CLOCK_VIRTUAL);
                        timespecadd(&ts, &itn->it_time.it_value, &ts);
                }
                LIST_FIRST(&pts->pts_virtual) = NULL;
                if (itn) {
                        KASSERT(itn->it_clockid == CLOCK_VIRTUAL);
                        timespecadd(&ts, &itn->it_time.it_value,
                            &itn->it_time.it_value);
                        LIST_INSERT_HEAD(&pts->pts_virtual, itn, it_list);
                }
                timespecclear(&ts);
                for (itn = LIST_FIRST(&pts->pts_prof);
                     itn && itn != pts->pts_timers[ITIMER_PROF];
                     itn = LIST_NEXT(itn, it_list)) {
                        KASSERT(itn->it_clockid == CLOCK_PROF);
                        timespecadd(&ts, &itn->it_time.it_value, &ts);
                }
                LIST_FIRST(&pts->pts_prof) = NULL;
                if (itn) {
                        KASSERT(itn->it_clockid == CLOCK_PROF);
                        timespecadd(&ts, &itn->it_time.it_value,
                            &itn->it_time.it_value);
                        LIST_INSERT_HEAD(&pts->pts_prof, itn, it_list);
                }
                i = TIMER_MIN;
        }
        for ( ; i < TIMER_MAX; i++) {
                if (pts->pts_timers[i] != NULL) {
                        /* Free the timer and release the lock.  */
                        ptimer_free(pts, i);
                        /* Reacquire the lock for the next one.  */
                        itimer_lock();
                }
        }
        if (pts->pts_timers[0] == NULL && pts->pts_timers[1] == NULL &&
            pts->pts_timers[2] == NULL && pts->pts_timers[3] == NULL) {
                p->p_timers = NULL;
                itimer_unlock();
                kmem_free(pts, sizeof(*pts));
        } else
                itimer_unlock();
}

/*
 * ptimer_fire:
 *
 *      Fire a per-process timer.
 */
static void
ptimer_fire(struct itimer *it)
{
        struct ptimer *pt = container_of(it, struct ptimer, pt_itimer);

        KASSERT(itimer_lock_held());

        /*
         * XXX Can overrun, but we don't do signal queueing yet, anyway.
         * XXX Relying on the clock interrupt is stupid.
         */
        if (pt->pt_ev.sigev_notify != SIGEV_SIGNAL) {
                return;
        }

        if (!pt->pt_queued) {
                TAILQ_INSERT_TAIL(&ptimer_queue, pt, pt_chain);
                pt->pt_queued = true;
                softint_schedule(ptimer_sih);
        }
}

/*
 * Operations vector for per-process timers (BSD and POSIX).
 */
static const struct itimer_ops ptimer_itimer_ops = {
        .ito_fire = ptimer_fire,
};

/*
 * sys_timer_create:
 *
 *      System call to create a POSIX timer.
 */
int
sys_timer_create(struct lwp *l, const struct sys_timer_create_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(clockid_t) clock_id;
                syscallarg(struct sigevent *) evp;
                syscallarg(timer_t *) timerid;
        } */

        return timer_create1(SCARG(uap, timerid), SCARG(uap, clock_id),
            SCARG(uap, evp), copyin, l);
}

int
timer_create1(timer_t *tid, clockid_t id, struct sigevent *evp,
    copyin_t fetch_event, struct lwp *l)
{
        int error;
        timer_t timerid;
        struct itlist *itl;
        struct ptimers *pts;
        struct ptimer *pt;
        struct proc *p;

        p = l->l_proc;

        if ((u_int)id > CLOCK_MONOTONIC)
                return SET_ERROR(EINVAL);

        if ((pts = p->p_timers) == NULL)
                pts = ptimers_alloc(p);

        pt = kmem_zalloc(sizeof(*pt), KM_SLEEP);
        if (evp != NULL) {
                if (((error =
                    (*fetch_event)(evp, &pt->pt_ev, sizeof(pt->pt_ev))) != 0) ||
                    ((pt->pt_ev.sigev_notify < SIGEV_NONE) ||
                        (pt->pt_ev.sigev_notify > SIGEV_SA)) ||
                        (pt->pt_ev.sigev_notify == SIGEV_SIGNAL &&
                         (pt->pt_ev.sigev_signo <= 0 ||
                          pt->pt_ev.sigev_signo >= NSIG))) {
                        kmem_free(pt, sizeof(*pt));
                        return (error ? error : SET_ERROR(EINVAL));
                }
        }

        /* Find a free timer slot, skipping those reserved for setitimer(). */
        itimer_lock();
        for (timerid = TIMER_MIN; timerid < TIMER_MAX; timerid++)
                if (pts->pts_timers[timerid] == NULL)
                        break;
        if (timerid == TIMER_MAX) {
                itimer_unlock();
                kmem_free(pt, sizeof(*pt));
                return SET_ERROR(EAGAIN);
        }
        if (evp == NULL) {
                pt->pt_ev.sigev_notify = SIGEV_SIGNAL;
                switch (id) {
                case CLOCK_REALTIME:
                case CLOCK_MONOTONIC:
                        pt->pt_ev.sigev_signo = SIGALRM;
                        break;
                case CLOCK_VIRTUAL:
                        pt->pt_ev.sigev_signo = SIGVTALRM;
                        break;
                case CLOCK_PROF:
                        pt->pt_ev.sigev_signo = SIGPROF;
                        break;
                }
                pt->pt_ev.sigev_value.sival_int = timerid;
        }

        switch (id) {
        case CLOCK_VIRTUAL:
                itl = &pts->pts_virtual;
                break;
        case CLOCK_PROF:
                itl = &pts->pts_prof;
                break;
        default:
                itl = NULL;
        }

        itimer_init(&pt->pt_itimer, &ptimer_itimer_ops, id, itl);
        pt->pt_proc = p;
        pt->pt_poverruns = 0;
        pt->pt_entry = timerid;
        pt->pt_queued = false;

        pts->pts_timers[timerid] = &pt->pt_itimer;
        itimer_unlock();

        return copyout(&timerid, tid, sizeof(timerid));
}

/*
 * sys_timer_delete:
 *
 *      System call to delete a POSIX timer.
 */
int
sys_timer_delete(struct lwp *l, const struct sys_timer_delete_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(timer_t) timerid;
        } */
        struct proc *p = l->l_proc;
        timer_t timerid;
        struct ptimers *pts;
        struct itimer *it, *itn;

        timerid = SCARG(uap, timerid);
        pts = p->p_timers;

        if (pts == NULL || !IS_POSIX_TIMER(timerid))
                return SET_ERROR(EINVAL);

        itimer_lock();
        if ((it = pts->pts_timers[timerid]) == NULL) {
                itimer_unlock();
                return SET_ERROR(EINVAL);
        }

        if (CLOCK_VIRTUAL_P(it->it_clockid)) {
                if (it->it_active) {
                        itn = LIST_NEXT(it, it_list);
                        LIST_REMOVE(it, it_list);
                        for ( ; itn; itn = LIST_NEXT(itn, it_list))
                                timespecadd(&it->it_time.it_value,
                                    &itn->it_time.it_value,
                                    &itn->it_time.it_value);
                        it->it_active = false;
                }
        }

        /* Free the timer and release the lock.  */
        ptimer_free(pts, timerid);

        return 0;
}

/*
 * sys___timer_settime50:
 *
 *      System call to set/arm a POSIX timer.
 */
int
sys___timer_settime50(struct lwp *l,
    const struct sys___timer_settime50_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(timer_t) timerid;
                syscallarg(int) flags;
                syscallarg(const struct itimerspec *) value;
                syscallarg(struct itimerspec *) ovalue;
        } */
        int error;
        struct itimerspec value, ovalue, *ovp = NULL;

        if ((error = copyin(SCARG(uap, value), &value,
            sizeof(struct itimerspec))) != 0)
                return error;

        if (SCARG(uap, ovalue))
                ovp = &ovalue;

        if ((error = dotimer_settime(SCARG(uap, timerid), &value, ovp,
            SCARG(uap, flags), l->l_proc)) != 0)
                return error;

        if (ovp)
                return copyout(&ovalue, SCARG(uap, ovalue),
                    sizeof(struct itimerspec));
        return 0;
}

int
dotimer_settime(int timerid, struct itimerspec *value,
    struct itimerspec *ovalue, int flags, struct proc *p)
{
        struct timespec now;
        struct itimerspec val;
        struct ptimers *pts;
        struct itimer *it;
        int error;

        pts = p->p_timers;

        if (pts == NULL || !IS_POSIX_TIMER(timerid))
                return SET_ERROR(EINVAL);
        val = *value;
        if (itimespecfix(&val.it_value) != 0 ||
            itimespecfix(&val.it_interval) != 0)
                return SET_ERROR(EINVAL);

        itimer_lock();
 restart:
        if ((it = pts->pts_timers[timerid]) == NULL) {
                error = SET_ERROR(EINVAL);
                goto out;
        }

        if (ovalue)
                itimer_gettime(it, ovalue);
        it->it_time = val;

        /*
         * If we've been passed a relative time for a realtime timer,
         * convert it to absolute; if an absolute time for a virtual
         * timer, convert it to relative and make sure we don't set it
         * to zero, which would cancel the timer, or let it go
         * negative, which would confuse the comparison tests.
         */
        if (timespecisset(&it->it_time.it_value)) {
                if (!CLOCK_VIRTUAL_P(it->it_clockid)) {
                        if ((flags & TIMER_ABSTIME) == 0) {
                                if (it->it_clockid == CLOCK_REALTIME) {
                                        getnanotime(&now);
                                } else { /* CLOCK_MONOTONIC */
                                        getnanouptime(&now);
                                }
                                if (!timespecaddok(&it->it_time.it_value,
                                        &now)) {
                                        error = SET_ERROR(EINVAL);
                                        goto out;
                                }
                                timespecadd(&it->it_time.it_value, &now,
                                    &it->it_time.it_value);
                        }
                } else {
                        if ((flags & TIMER_ABSTIME) != 0) {
                                getnanotime(&now);
                                if (!timespecsubok(&it->it_time.it_value,
                                        &now)) {
                                        error = SET_ERROR(EINVAL);
                                        goto out;
                                }
                                timespecsub(&it->it_time.it_value, &now,
                                    &it->it_time.it_value);
                                if (!timespecisset(&it->it_time.it_value) ||
                                    it->it_time.it_value.tv_sec < 0) {
                                        it->it_time.it_value.tv_sec = 0;
                                        it->it_time.it_value.tv_nsec = 1;
                                }
                        }
                }
        }

        error = itimer_settime(it);
        if (error == ERESTART) {
                KASSERT(!CLOCK_VIRTUAL_P(it->it_clockid));
                goto restart;
        }
        KASSERT(error == 0);
 out:
        itimer_unlock();

        return error;
}

/*
 * sys___timer_gettime50:
 *
 *      System call to return the time remaining until a POSIX timer fires.
 */
int
sys___timer_gettime50(struct lwp *l,
    const struct sys___timer_gettime50_args *uap, register_t *retval)
{
        /* {
                syscallarg(timer_t) timerid;
                syscallarg(struct itimerspec *) value;
        } */
        struct itimerspec its;
        int error;

        if ((error = dotimer_gettime(SCARG(uap, timerid), l->l_proc,
            &its)) != 0)
                return error;

        return copyout(&its, SCARG(uap, value), sizeof(its));
}

int
dotimer_gettime(int timerid, struct proc *p, struct itimerspec *its)
{
        struct itimer *it;
        struct ptimers *pts;

        pts = p->p_timers;
        if (pts == NULL || !IS_POSIX_TIMER(timerid))
                return SET_ERROR(EINVAL);
        itimer_lock();
        if ((it = pts->pts_timers[timerid]) == NULL) {
                itimer_unlock();
                return SET_ERROR(EINVAL);
        }
        itimer_gettime(it, its);
        itimer_unlock();

        return 0;
}

/*
 * sys_timer_getoverrun:
 *
 *      System call to return the number of times a POSIX timer has
 *      expired while a notification was already pending.  The counter
 *      is reset when a timer expires and a notification can be posted.
 */
int
sys_timer_getoverrun(struct lwp *l, const struct sys_timer_getoverrun_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(timer_t) timerid;
        } */
        struct proc *p = l->l_proc;
        struct ptimers *pts;
        int timerid;
        struct itimer *it;
        struct ptimer *pt;

        timerid = SCARG(uap, timerid);

        pts = p->p_timers;
        if (pts == NULL || !IS_POSIX_TIMER(timerid))
                return SET_ERROR(EINVAL);
        itimer_lock();
        if ((it = pts->pts_timers[timerid]) == NULL) {
                itimer_unlock();
                return SET_ERROR(EINVAL);
        }
        pt = container_of(it, struct ptimer, pt_itimer);
        *retval = pt->pt_poverruns;
        if (*retval >= DELAYTIMER_MAX)
                *retval = DELAYTIMER_MAX;
        itimer_unlock();

        return 0;
}

/*
 * sys___getitimer50:
 *
 *      System call to get the time remaining before a BSD timer fires.
 */
int
sys___getitimer50(struct lwp *l, const struct sys___getitimer50_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(int) which;
                syscallarg(struct itimerval *) itv;
        } */
        struct proc *p = l->l_proc;
        struct itimerval aitv;
        int error;

        memset(&aitv, 0, sizeof(aitv));
        error = dogetitimer(p, SCARG(uap, which), &aitv);
        if (error)
                return error;
        return copyout(&aitv, SCARG(uap, itv), sizeof(struct itimerval));
}

int
dogetitimer(struct proc *p, int which, struct itimerval *itvp)
{
        struct ptimers *pts;
        struct itimer *it;
        struct itimerspec its;

        if (!IS_ITIMER(which))
                return SET_ERROR(EINVAL);

        itimer_lock();
        pts = p->p_timers;
        if (pts == NULL || (it = pts->pts_timers[which]) == NULL) {
                timerclear(&itvp->it_value);
                timerclear(&itvp->it_interval);
        } else {
                itimer_gettime(it, &its);
                TIMESPEC_TO_TIMEVAL(&itvp->it_value, &its.it_value);
                TIMESPEC_TO_TIMEVAL(&itvp->it_interval, &its.it_interval);
        }
        itimer_unlock();

        return 0;
}

/*
 * sys___setitimer50:
 *
 *      System call to set/arm a BSD timer.
 */
int
sys___setitimer50(struct lwp *l, const struct sys___setitimer50_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(int) which;
                syscallarg(const struct itimerval *) itv;
                syscallarg(struct itimerval *) oitv;
        } */
        struct proc *p = l->l_proc;
        int which = SCARG(uap, which);
        struct sys___getitimer50_args getargs;
        const struct itimerval *itvp;
        struct itimerval aitv;
        int error;

        itvp = SCARG(uap, itv);
        if (itvp &&
            (error = copyin(itvp, &aitv, sizeof(struct itimerval))) != 0)
                return error;
        if (SCARG(uap, oitv) != NULL) {
                SCARG(&getargs, which) = which;
                SCARG(&getargs, itv) = SCARG(uap, oitv);
                if ((error = sys___getitimer50(l, &getargs, retval)) != 0)
                        return error;
        }
        if (itvp == 0)
                return 0;

        return dosetitimer(p, which, &aitv);
}

int
dosetitimer(struct proc *p, int which, struct itimerval *itvp)
{
        struct timespec now;
        struct ptimers *pts;
        struct ptimer *spare;
        struct itimer *it;
        struct itlist *itl;
        int error;

        if (!IS_ITIMER(which))
                return SET_ERROR(EINVAL);
        if (itimerfix(&itvp->it_value) || itimerfix(&itvp->it_interval))
                return SET_ERROR(EINVAL);

        /*
         * Don't bother allocating data structures if the process just
         * wants to clear the timer.
         */
        spare = NULL;
        pts = p->p_timers;
 retry:
        if (!timerisset(&itvp->it_value) && (pts == NULL ||
            pts->pts_timers[which] == NULL))
                return 0;
        if (pts == NULL)
                pts = ptimers_alloc(p);
        itimer_lock();
 restart:
        it = pts->pts_timers[which];
        if (it == NULL) {
                struct ptimer *pt;

                if (spare == NULL) {
                        itimer_unlock();
                        spare = kmem_zalloc(sizeof(*spare), KM_SLEEP);
                        goto retry;
                }
                pt = spare;
                spare = NULL;

                it = &pt->pt_itimer;
                pt->pt_ev.sigev_notify = SIGEV_SIGNAL;
                pt->pt_ev.sigev_value.sival_int = which;

                switch (which) {
                case ITIMER_REAL:
                case ITIMER_MONOTONIC:
                        itl = NULL;
                        pt->pt_ev.sigev_signo = SIGALRM;
                        break;
                case ITIMER_VIRTUAL:
                        itl = &pts->pts_virtual;
                        pt->pt_ev.sigev_signo = SIGVTALRM;
                        break;
                case ITIMER_PROF:
                        itl = &pts->pts_prof;
                        pt->pt_ev.sigev_signo = SIGPROF;
                        break;
                default:
                        panic("%s: can't happen %d", __func__, which);
                }
                itimer_init(it, &ptimer_itimer_ops, which, itl);
                pt->pt_proc = p;
                pt->pt_entry = which;

                pts->pts_timers[which] = it;
        }

        TIMEVAL_TO_TIMESPEC(&itvp->it_value, &it->it_time.it_value);
        TIMEVAL_TO_TIMESPEC(&itvp->it_interval, &it->it_time.it_interval);

        error = 0;
        if (timespecisset(&it->it_time.it_value)) {
                /* Convert to absolute time */
                /* XXX need to wrap in splclock for timecounters case? */
                switch (which) {
                case ITIMER_REAL:
                        getnanotime(&now);
                        if (!timespecaddok(&it->it_time.it_value, &now)) {
                                error = SET_ERROR(EINVAL);
                                goto out;
                        }
                        timespecadd(&it->it_time.it_value, &now,
                            &it->it_time.it_value);
                        break;
                case ITIMER_MONOTONIC:
                        getnanouptime(&now);
                        if (!timespecaddok(&it->it_time.it_value, &now)) {
                                error = SET_ERROR(EINVAL);
                                goto out;
                        }
                        timespecadd(&it->it_time.it_value, &now,
                            &it->it_time.it_value);
                        break;
                default:
                        break;
                }
        }

        error = itimer_settime(it);
        if (error == ERESTART) {
                KASSERT(!CLOCK_VIRTUAL_P(it->it_clockid));
                goto restart;
        }
        KASSERT(error == 0);
out:
        itimer_unlock();
        if (spare != NULL)
                kmem_free(spare, sizeof(*spare));

        return error;
}

/*
 * ptimer_tick:
 *
 *      Called from hardclock() to decrement per-process virtual timers.
 */
void
ptimer_tick(lwp_t *l, bool user)
{
        struct ptimers *pts;
        struct itimer *it;
        proc_t *p;

        p = l->l_proc;
        if (p->p_timers == NULL)
                return;

        itimer_lock();
        if ((pts = l->l_proc->p_timers) != NULL) {
                /*
                 * Run current process's virtual and profile time, as needed.
                 */
                if (user && (it = LIST_FIRST(&pts->pts_virtual)) != NULL)
                        if (itimer_decr(it, tick * 1000))
                                (*it->it_ops->ito_fire)(it);
                if ((it = LIST_FIRST(&pts->pts_prof)) != NULL)
                        if (itimer_decr(it, tick * 1000))
                                (*it->it_ops->ito_fire)(it);
        }
        itimer_unlock();
}

/*
 * ptimer_intr:
 *
 *      Software interrupt handler for processing per-process
 *      timer expiration.
 */
static void
ptimer_intr(void *cookie)
{
        ksiginfo_t ksi;
        struct itimer *it;
        struct ptimer *pt;
        proc_t *p;

        mutex_enter(&proc_lock);
        itimer_lock();
        while ((pt = TAILQ_FIRST(&ptimer_queue)) != NULL) {
                it = &pt->pt_itimer;

                TAILQ_REMOVE(&ptimer_queue, pt, pt_chain);
                KASSERT(pt->pt_queued);
                pt->pt_queued = false;

                p = pt->pt_proc;
                if (p->p_timers == NULL) {
                        /* Process is dying. */
                        continue;
                }
                if (pt->pt_ev.sigev_notify != SIGEV_SIGNAL) {
                        continue;
                }
                if (sigismember(&p->p_sigpend.sp_set, pt->pt_ev.sigev_signo)) {
                        if (it->it_overruns < INT_MAX)
                                it->it_overruns++;
                        continue;
                }

                KSI_INIT(&ksi);
                ksi.ksi_signo = pt->pt_ev.sigev_signo;
                ksi.ksi_code = SI_TIMER;
                ksi.ksi_value = pt->pt_ev.sigev_value;
                pt->pt_poverruns = it->it_overruns;
                it->it_overruns = 0;
                itimer_unlock();
                kpsignal(p, &ksi, NULL);
                itimer_lock();
        }
        itimer_unlock();
        mutex_exit(&proc_lock);
}