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[netbsd-mini2440.git] / sys / kern / kern_time.c

/*      $NetBSD: kern_time.c,v 1.162 2009/10/03 20:48:42 elad Exp $     */

/*-
 * Copyright (c) 2000, 2004, 2005, 2007, 2008, 2009 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christopher G. Demetriou, and by Andrew Doran.
 *
 * 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 1.162 2009/10/03 20:48:42 elad Exp $");

#include <sys/param.h>
#include <sys/resourcevar.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/signalvar.h>
#include <sys/syslog.h>
#include <sys/timetc.h>
#include <sys/timex.h>
#include <sys/kauth.h>
#include <sys/mount.h>
#include <sys/sa.h>
#include <sys/savar.h>
#include <sys/syscallargs.h>
#include <sys/cpu.h>

#include <uvm/uvm_extern.h>

#include "opt_sa.h"

static void     timer_intr(void *);
static void     itimerfire(struct ptimer *);
static void     itimerfree(struct ptimers *, int);

kmutex_t        timer_lock;

static void     *timer_sih;
static TAILQ_HEAD(, ptimer) timer_queue;

struct pool ptimer_pool, ptimers_pool;

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

        pool_init(&ptimer_pool, sizeof(struct ptimer), 0, 0, 0, "ptimerpl",
            &pool_allocator_nointr, IPL_NONE);
        pool_init(&ptimers_pool, sizeof(struct ptimers), 0, 0, 0, "ptimerspl",
            &pool_allocator_nointr, IPL_NONE);
}

void
time_init2(void)
{

        TAILQ_INIT(&timer_queue);
        mutex_init(&timer_lock, MUTEX_DEFAULT, IPL_SCHED);
        timer_sih = softint_establish(SOFTINT_CLOCK | SOFTINT_MPSAFE,
            timer_intr, NULL);
}

/* 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;
        int s;

        /* WHAT DO WE DO ABOUT PENDING REAL-TIME TIMEOUTS??? */
        s = splclock();
        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) {
                splx(s);
                return (EPERM);
        }

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

        tc_setclock(ts);

        timespecadd(&boottime, &delta, &boottime);

        resettodr();
        splx(s);

        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;
        } */
        clockid_t clock_id;
        struct timespec ats;

        clock_id = SCARG(uap, clock_id);
        switch (clock_id) {
        case CLOCK_REALTIME:
                nanotime(&ats);
                break;
        case CLOCK_MONOTONIC:
                nanouptime(&ats);
                break;
        default:
                return (EINVAL);
        }

        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;

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

        clock_id = SCARG(uap, clock_id);
        switch (clock_id) {
        case CLOCK_REALTIME:
        case CLOCK_MONOTONIC:
                ts.tv_sec = 0;
                if (tc_getfrequency() > 1000000000)
                        ts.tv_nsec = 1;
                else
                        ts.tv_nsec = 1000000000 / tc_getfrequency();
                break;
        default:
                return (EINVAL);
        }

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

        return error;
}

/* 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, &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;
}

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

        if ((error = itimespecfix(rqt)) != 0)
                return error;

        timo = tstohz(rqt);
        /*
         * Avoid inadvertantly sleeping forever
         */
        if (timo == 0)
                timo = 1;
        getnanouptime(&rmtstart);
again:
        error = kpause("nanoslp", true, timo, NULL);
        if (rmt != NULL || error == 0) {
                struct timespec rmtend;
                struct timespec t0;
                struct timespec *t;

                getnanouptime(&rmtend);
                t = (rmt != NULL) ? rmt : &t0;
                timespecsub(&rmtend, &rmtstart, t);
                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 = EINTR;
        if (error == EWOULDBLOCK)
                error = 0;

        return error;
}

/* 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)) {
                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;
        }

        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 = 0;
        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)
{
        extern int64_t time_adjtime;  /* in kern_ntptime.c */

        if (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);
                time_adjtime = delta->tv_sec * 1000000 + 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. 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 three elements in this array are reserved for the BSD timers:
 * element 0 is ITIMER_REAL, element 1 is ITIMER_VIRTUAL, and element
 * 2 is ITIMER_PROF. The rest may be allocated by the timer_create()
 * syscall.
 *
 * Realtime timers are kept in the ptimer structure as an absolute
 * time; virtual time timers are kept as a linked list of deltas.
 * Virtual time timers are processed in the hardclock() routine of
 * kern_clock.c.  The real time timer is processed by a callout
 * routine, called from the softclock() routine.  Since a callout may
 * be delayed in real time due to interrupt processing in the system,
 * it is possible for the real time timeout routine (realtimeexpire,
 * given below), to be delayed in real time past when it is supposed
 * to occur.  It does not suffice, therefore, to reload the real timer
 * .it_value from the real time timers .it_interval.  Rather, we
 * compute the next time in absolute time the timer should go off.  */

/* Allocate a POSIX realtime 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 ptimers *pts;
        struct ptimer *pt;
        struct proc *p;

        p = l->l_proc;

        if (id < CLOCK_REALTIME || id > CLOCK_PROF)
                return (EINVAL);

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

        pt = pool_get(&ptimer_pool, PR_WAITOK);
        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))) {
                        pool_put(&ptimer_pool, pt);
                        return (error ? error : EINVAL);
                }
        }

        /* Find a free timer slot, skipping those reserved for setitimer(). */
        mutex_spin_enter(&timer_lock);
        for (timerid = 3; timerid < TIMER_MAX; timerid++)
                if (pts->pts_timers[timerid] == NULL)
                        break;
        if (timerid == TIMER_MAX) {
                mutex_spin_exit(&timer_lock);
                pool_put(&ptimer_pool, pt);
                return EAGAIN;
        }
        if (evp == NULL) {
                pt->pt_ev.sigev_notify = SIGEV_SIGNAL;
                switch (id) {
                case CLOCK_REALTIME:
                        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;
        }
        pt->pt_info.ksi_signo = pt->pt_ev.sigev_signo;
        pt->pt_info.ksi_errno = 0;
        pt->pt_info.ksi_code = 0;
        pt->pt_info.ksi_pid = p->p_pid;
        pt->pt_info.ksi_uid = kauth_cred_getuid(l->l_cred);
        pt->pt_info.ksi_value = pt->pt_ev.sigev_value;
        pt->pt_type = id;
        pt->pt_proc = p;
        pt->pt_overruns = 0;
        pt->pt_poverruns = 0;
        pt->pt_entry = timerid;
        pt->pt_queued = false;
        timespecclear(&pt->pt_time.it_value);
        if (id == CLOCK_REALTIME)
                callout_init(&pt->pt_ch, 0);
        else
                pt->pt_active = 0;

        pts->pts_timers[timerid] = pt;
        mutex_spin_exit(&timer_lock);

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

/* Delete a POSIX realtime 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 ptimer *pt, *ptn;

        timerid = SCARG(uap, timerid);
        pts = p->p_timers;
        
        if (pts == NULL || timerid < 2 || timerid >= TIMER_MAX)
                return (EINVAL);

        mutex_spin_enter(&timer_lock);
        if ((pt = pts->pts_timers[timerid]) == NULL) {
                mutex_spin_exit(&timer_lock);
                return (EINVAL);
        }
        if (pt->pt_type != CLOCK_REALTIME) {
                if (pt->pt_active) {
                        ptn = LIST_NEXT(pt, pt_list);
                        LIST_REMOVE(pt, pt_list);
                        for ( ; ptn; ptn = LIST_NEXT(ptn, pt_list))
                                timespecadd(&pt->pt_time.it_value,
                                    &ptn->pt_time.it_value,
                                    &ptn->pt_time.it_value);
                        pt->pt_active = 0;
                }
        }
        itimerfree(pts, timerid);

        return (0);
}

/*
 * Set up the given timer. The value in pt->pt_time.it_value is taken
 * to be an absolute time for CLOCK_REALTIME timers and a relative
 * time for virtual timers.
 * Must be called at splclock().
 */
void
timer_settime(struct ptimer *pt)
{
        struct ptimer *ptn, *pptn;
        struct ptlist *ptl;

        KASSERT(mutex_owned(&timer_lock));

        if (pt->pt_type == CLOCK_REALTIME) {
                callout_stop(&pt->pt_ch);
                if (timespecisset(&pt->pt_time.it_value)) {
                        /*
                         * Don't need to check tshzto() return value, here.
                         * callout_reset() does it for us.
                         */
                        callout_reset(&pt->pt_ch, tshzto(&pt->pt_time.it_value),
                            realtimerexpire, pt);
                }
        } else {
                if (pt->pt_active) {
                        ptn = LIST_NEXT(pt, pt_list);
                        LIST_REMOVE(pt, pt_list);
                        for ( ; ptn; ptn = LIST_NEXT(ptn, pt_list))
                                timespecadd(&pt->pt_time.it_value,
                                    &ptn->pt_time.it_value,
                                    &ptn->pt_time.it_value);
                }
                if (timespecisset(&pt->pt_time.it_value)) {
                        if (pt->pt_type == CLOCK_VIRTUAL)
                                ptl = &pt->pt_proc->p_timers->pts_virtual;
                        else
                                ptl = &pt->pt_proc->p_timers->pts_prof;

                        for (ptn = LIST_FIRST(ptl), pptn = NULL;
                             ptn && timespeccmp(&pt->pt_time.it_value,
                                 &ptn->pt_time.it_value, >);
                             pptn = ptn, ptn = LIST_NEXT(ptn, pt_list))
                                timespecsub(&pt->pt_time.it_value,
                                    &ptn->pt_time.it_value,
                                    &pt->pt_time.it_value);

                        if (pptn)
                                LIST_INSERT_AFTER(pptn, pt, pt_list);
                        else
                                LIST_INSERT_HEAD(ptl, pt, pt_list);

                        for ( ; ptn ; ptn = LIST_NEXT(ptn, pt_list))
                                timespecsub(&ptn->pt_time.it_value,
                                    &pt->pt_time.it_value,
                                    &ptn->pt_time.it_value);

                        pt->pt_active = 1;
                } else
                        pt->pt_active = 0;
        }
}

void
timer_gettime(struct ptimer *pt, struct itimerspec *aits)
{
        struct timespec now;
        struct ptimer *ptn;

        KASSERT(mutex_owned(&timer_lock));

        *aits = pt->pt_time;
        if (pt->pt_type == CLOCK_REALTIME) {
                /*
                 * 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)) {
                        getnanotime(&now);
                        if (timespeccmp(&aits->it_value, &now, <))
                                timespecclear(&aits->it_value);
                        else
                                timespecsub(&aits->it_value, &now,
                                    &aits->it_value);
                }
        } else if (pt->pt_active) {
                if (pt->pt_type == CLOCK_VIRTUAL)
                        ptn = LIST_FIRST(&pt->pt_proc->p_timers->pts_virtual);
                else
                        ptn = LIST_FIRST(&pt->pt_proc->p_timers->pts_prof);
                for ( ; ptn && ptn != pt; ptn = LIST_NEXT(ptn, pt_list))
                        timespecadd(&aits->it_value,
                            &ptn->pt_time.it_value, &aits->it_value);
                KASSERT(ptn != NULL); /* pt should be findable on the list */
        } else
                timespecclear(&aits->it_value);
}



/* Set and arm a POSIX realtime 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, oval;
        struct ptimers *pts;
        struct ptimer *pt;
        int error;

        pts = p->p_timers;

        if (pts == NULL || timerid < 2 || timerid >= TIMER_MAX)
                return EINVAL;
        val = *value;
        if ((error = itimespecfix(&val.it_value)) != 0 ||
            (error = itimespecfix(&val.it_interval)) != 0)
                return error;

        mutex_spin_enter(&timer_lock);
        if ((pt = pts->pts_timers[timerid]) == NULL) {
                mutex_spin_exit(&timer_lock);
                return EINVAL;
        }

        oval = pt->pt_time;
        pt->pt_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(&pt->pt_time.it_value)) {
                if (pt->pt_type == CLOCK_REALTIME) {
                        if ((flags & TIMER_ABSTIME) == 0) {
                                getnanotime(&now);
                                timespecadd(&pt->pt_time.it_value, &now,
                                    &pt->pt_time.it_value);
                        }
                } else {
                        if ((flags & TIMER_ABSTIME) != 0) {
                                getnanotime(&now);
                                timespecsub(&pt->pt_time.it_value, &now,
                                    &pt->pt_time.it_value);
                                if (!timespecisset(&pt->pt_time.it_value) ||
                                    pt->pt_time.it_value.tv_sec < 0) {
                                        pt->pt_time.it_value.tv_sec = 0;
                                        pt->pt_time.it_value.tv_nsec = 1;
                                }
                        }
                }
        }

        timer_settime(pt);
        mutex_spin_exit(&timer_lock);

        if (ovalue)
                *ovalue = oval;

        return (0);
}

/* 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 ptimer *pt;
        struct ptimers *pts;

        pts = p->p_timers;
        if (pts == NULL || timerid < 2 || timerid >= TIMER_MAX)
                return (EINVAL);
        mutex_spin_enter(&timer_lock);
        if ((pt = pts->pts_timers[timerid]) == NULL) {
                mutex_spin_exit(&timer_lock);
                return (EINVAL);
        }
        timer_gettime(pt, its);
        mutex_spin_exit(&timer_lock);

        return 0;
}

/*
 * Return the count of the number of times a periodic timer 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 ptimer *pt;

        timerid = SCARG(uap, timerid);

        pts = p->p_timers;
        if (pts == NULL || timerid < 2 || timerid >= TIMER_MAX)
                return (EINVAL);
        mutex_spin_enter(&timer_lock);
        if ((pt = pts->pts_timers[timerid]) == NULL) {
                mutex_spin_exit(&timer_lock);
                return (EINVAL);
        }
        *retval = pt->pt_poverruns;
        mutex_spin_exit(&timer_lock);

        return (0);
}

#ifdef KERN_SA
/* Glue function that triggers an upcall; called from userret(). */
void
timerupcall(struct lwp *l)
{
        struct ptimers *pt = l->l_proc->p_timers;
        struct proc *p = l->l_proc;
        unsigned int i, fired, done;

        KDASSERT(l->l_proc->p_sa);
        /* Bail out if we do not own the virtual processor */
        if (l->l_savp->savp_lwp != l)
                return ;

        mutex_enter(p->p_lock);

        fired = pt->pts_fired;
        done = 0;
        while ((i = ffs(fired)) != 0) {
                siginfo_t *si;
                int mask = 1 << --i;
                int f;

                f = ~l->l_pflag & LP_SA_NOBLOCK;
                l->l_pflag |= LP_SA_NOBLOCK;
                si = siginfo_alloc(PR_WAITOK);
                si->_info = pt->pts_timers[i]->pt_info.ksi_info;
                if (sa_upcall(l, SA_UPCALL_SIGEV | SA_UPCALL_DEFER, NULL, l,
                    sizeof(*si), si, siginfo_free) != 0) {
                        siginfo_free(si);
                        /* XXX What do we do here?? */
                } else
                        done |= mask;
                fired &= ~mask;
                l->l_pflag ^= f;
        }
        pt->pts_fired &= ~done;
        if (pt->pts_fired == 0)
                l->l_proc->p_timerpend = 0;

        mutex_exit(p->p_lock);
}
#endif /* KERN_SA */

/*
 * Real interval timer expired:
 * send process whose timer expired an alarm signal.
 * If time is not set up to reload, then just return.
 * Else compute next time timer should go off which is > current time.
 * This is where delay in processing this timeout causes multiple
 * SIGALRM calls to be compressed into one.
 */
void
realtimerexpire(void *arg)
{
        uint64_t last_val, next_val, interval, now_ms;
        struct timespec now, next;
        struct ptimer *pt;
        int backwards;

        pt = arg;

        mutex_spin_enter(&timer_lock);
        itimerfire(pt);

        if (!timespecisset(&pt->pt_time.it_interval)) {
                timespecclear(&pt->pt_time.it_value);
                mutex_spin_exit(&timer_lock);
                return;
        }

        getnanotime(&now);
        backwards = (timespeccmp(&pt->pt_time.it_value, &now, >));
        timespecadd(&pt->pt_time.it_value, &pt->pt_time.it_interval, &next);
        /* Handle the easy case of non-overflown timers first. */
        if (!backwards && timespeccmp(&next, &now, >)) {
                pt->pt_time.it_value = next;
        } else {
                now_ms = timespec2ns(&now);
                last_val = timespec2ns(&pt->pt_time.it_value);
                interval = timespec2ns(&pt->pt_time.it_interval);

                next_val = now_ms +
                    (now_ms - last_val + interval - 1) % interval;

                if (backwards)
                        next_val += interval;
                else
                        pt->pt_overruns += (now_ms - last_val) / interval;

                pt->pt_time.it_value.tv_sec = next_val / 1000000000;
                pt->pt_time.it_value.tv_nsec = next_val % 1000000000;
        }

        /*
         * Don't need to check tshzto() return value, here.
         * callout_reset() does it for us.
         */
        callout_reset(&pt->pt_ch, tshzto(&pt->pt_time.it_value),
            realtimerexpire, pt);
        mutex_spin_exit(&timer_lock);
}

/* BSD routine to get the value of an interval timer. */
/* ARGSUSED */
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;

        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 ptimer *pt;
        struct itimerspec its;

        if ((u_int)which > ITIMER_PROF)
                return (EINVAL);

        mutex_spin_enter(&timer_lock);
        pts = p->p_timers;
        if (pts == NULL || (pt = pts->pts_timers[which]) == NULL) {
                timerclear(&itvp->it_value);
                timerclear(&itvp->it_interval);
        } else {
                timer_gettime(pt, &its);
                TIMESPEC_TO_TIMEVAL(&itvp->it_value, &its.it_value);
                TIMESPEC_TO_TIMEVAL(&itvp->it_interval, &its.it_interval);
        }
        mutex_spin_exit(&timer_lock);   

        return 0;
}

/* BSD routine to set/arm an interval timer. */
/* ARGSUSED */
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;

        if ((u_int)which > ITIMER_PROF)
                return (EINVAL);
        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 *pt, *spare;

        if (itimerfix(&itvp->it_value) || itimerfix(&itvp->it_interval))
                return (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 = timers_alloc(p);
        mutex_spin_enter(&timer_lock);
        pt = pts->pts_timers[which];
        if (pt == NULL) {
                if (spare == NULL) {
                        mutex_spin_exit(&timer_lock);
                        spare = pool_get(&ptimer_pool, PR_WAITOK);
                        goto retry;
                }
                pt = spare;
                spare = NULL;
                pt->pt_ev.sigev_notify = SIGEV_SIGNAL;
                pt->pt_ev.sigev_value.sival_int = which;
                pt->pt_overruns = 0;
                pt->pt_proc = p;
                pt->pt_type = which;
                pt->pt_entry = which;
                pt->pt_queued = false;
                if (pt->pt_type == CLOCK_REALTIME)
                        callout_init(&pt->pt_ch, CALLOUT_MPSAFE);
                else
                        pt->pt_active = 0;

                switch (which) {
                case ITIMER_REAL:
                        pt->pt_ev.sigev_signo = SIGALRM;
                        break;
                case ITIMER_VIRTUAL:
                        pt->pt_ev.sigev_signo = SIGVTALRM;
                        break;
                case ITIMER_PROF:
                        pt->pt_ev.sigev_signo = SIGPROF;
                        break;
                }
                pts->pts_timers[which] = pt;
        }

        TIMEVAL_TO_TIMESPEC(&itvp->it_value, &pt->pt_time.it_value);
        TIMEVAL_TO_TIMESPEC(&itvp->it_interval, &pt->pt_time.it_interval);

        if ((which == ITIMER_REAL) && timespecisset(&pt->pt_time.it_value)) {
                /* Convert to absolute time */
                /* XXX need to wrap in splclock for timecounters case? */
                getnanotime(&now);
                timespecadd(&pt->pt_time.it_value, &now, &pt->pt_time.it_value);
        }
        timer_settime(pt);
        mutex_spin_exit(&timer_lock);
        if (spare != NULL)
                pool_put(&ptimer_pool, spare);

        return (0);
}

/* Utility routines to manage the array of pointers to timers. */
struct ptimers *
timers_alloc(struct proc *p)
{
        struct ptimers *pts;
        int i;

        pts = pool_get(&ptimers_pool, PR_WAITOK);
        LIST_INIT(&pts->pts_virtual);
        LIST_INIT(&pts->pts_prof);
        for (i = 0; i < TIMER_MAX; i++)
                pts->pts_timers[i] = NULL;
        pts->pts_fired = 0;
        mutex_spin_enter(&timer_lock);
        if (p->p_timers == NULL) {
                p->p_timers = pts;
                mutex_spin_exit(&timer_lock);
                return pts;
        }
        mutex_spin_exit(&timer_lock);
        pool_put(&ptimers_pool, pts);
        return p->p_timers;
}

/*
 * 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.
 */
void
timers_free(struct proc *p, int which)
{
        struct ptimers *pts;
        struct ptimer *ptn;
        struct timespec ts;
        int i;

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

        pts = p->p_timers;
        mutex_spin_enter(&timer_lock);
        if (which == TIMERS_ALL) {
                p->p_timers = NULL;
                i = 0;
        } else {
                timespecclear(&ts);
                for (ptn = LIST_FIRST(&pts->pts_virtual);
                     ptn && ptn != pts->pts_timers[ITIMER_VIRTUAL];
                     ptn = LIST_NEXT(ptn, pt_list)) {
                        KASSERT(ptn->pt_type != CLOCK_REALTIME);
                        timespecadd(&ts, &ptn->pt_time.it_value, &ts);
                }
                LIST_FIRST(&pts->pts_virtual) = NULL;
                if (ptn) {
                        KASSERT(ptn->pt_type != CLOCK_REALTIME);
                        timespecadd(&ts, &ptn->pt_time.it_value,
                            &ptn->pt_time.it_value);
                        LIST_INSERT_HEAD(&pts->pts_virtual, ptn, pt_list);
                }
                timespecclear(&ts);
                for (ptn = LIST_FIRST(&pts->pts_prof);
                     ptn && ptn != pts->pts_timers[ITIMER_PROF];
                     ptn = LIST_NEXT(ptn, pt_list)) {
                        KASSERT(ptn->pt_type != CLOCK_REALTIME);
                        timespecadd(&ts, &ptn->pt_time.it_value, &ts);
                }
                LIST_FIRST(&pts->pts_prof) = NULL;
                if (ptn) {
                        KASSERT(ptn->pt_type != CLOCK_REALTIME);
                        timespecadd(&ts, &ptn->pt_time.it_value,
                            &ptn->pt_time.it_value);
                        LIST_INSERT_HEAD(&pts->pts_prof, ptn, pt_list);
                }
                i = 3;
        }
        for ( ; i < TIMER_MAX; i++) {
                if (pts->pts_timers[i] != NULL) {
                        itimerfree(pts, i);
                        mutex_spin_enter(&timer_lock);
                }
        }
        if (pts->pts_timers[0] == NULL && pts->pts_timers[1] == NULL &&
            pts->pts_timers[2] == NULL) {
                p->p_timers = NULL;
                mutex_spin_exit(&timer_lock);
                pool_put(&ptimers_pool, pts);
        } else
                mutex_spin_exit(&timer_lock);
}

static void
itimerfree(struct ptimers *pts, int index)
{
        struct ptimer *pt;

        KASSERT(mutex_owned(&timer_lock));

        pt = pts->pts_timers[index];
        pts->pts_timers[index] = NULL;
        if (pt->pt_type == CLOCK_REALTIME)
                callout_halt(&pt->pt_ch, &timer_lock);
        else if (pt->pt_queued)
                TAILQ_REMOVE(&timer_queue, pt, pt_chain);
        mutex_spin_exit(&timer_lock);
        if (pt->pt_type == CLOCK_REALTIME)
                callout_destroy(&pt->pt_ch);
        pool_put(&ptimer_pool, pt);
}

/*
 * 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.
 */
static int
itimerdecr(struct ptimer *pt, int nsec)
{
        struct itimerspec *itp;

        KASSERT(mutex_owned(&timer_lock));

        itp = &pt->pt_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 (1);
        /* 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--;
                }
                timer_settime(pt);
        } else
                itp->it_value.tv_nsec = 0;              /* sec is already 0 */
        return (0);
}

static void
itimerfire(struct ptimer *pt)
{

        KASSERT(mutex_owned(&timer_lock));

        /*
         * 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_SA && pt->pt_proc->p_sa == NULL) ||
            (pt->pt_ev.sigev_notify != SIGEV_SIGNAL &&
            pt->pt_ev.sigev_notify != SIGEV_SA) || pt->pt_queued)
                return;
        TAILQ_INSERT_TAIL(&timer_queue, pt, pt_chain);
        pt->pt_queued = true;
        softint_schedule(timer_sih);
}

void
timer_tick(lwp_t *l, bool user)
{
        struct ptimers *pts;
        struct ptimer *pt;
        proc_t *p;

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

        mutex_spin_enter(&timer_lock);
        if ((pts = l->l_proc->p_timers) != NULL) {
                /*
                 * Run current process's virtual and profile time, as needed.
                 */
                if (user && (pt = LIST_FIRST(&pts->pts_virtual)) != NULL)
                        if (itimerdecr(pt, tick * 1000) == 0)
                                itimerfire(pt);
                if ((pt = LIST_FIRST(&pts->pts_prof)) != NULL)
                        if (itimerdecr(pt, tick * 1000) == 0)
                                itimerfire(pt);
        }
        mutex_spin_exit(&timer_lock);
}

#ifdef KERN_SA
/*
 * timer_sa_intr:
 *
 *      SIGEV_SA handling for timer_intr(). We are called (and return)
 * with the timer lock held. We know that the process had SA enabled
 * when this timer was enqueued. As timer_intr() is a soft interrupt
 * handler, SA should still be enabled by the time we get here.
 */
static void
timer_sa_intr(struct ptimer *pt, proc_t *p)
{
        unsigned int            i;
        struct sadata           *sa;
        struct sadata_vp        *vp;

        /* Cause the process to generate an upcall when it returns. */
        if (!p->p_timerpend) {
                /*
                 * XXX stop signals can be processed inside tsleep,
                 * which can be inside sa_yield's inner loop, which
                 * makes testing for sa_idle alone insuffucent to
                 * determine if we really should call setrunnable.
                 */
                pt->pt_poverruns = pt->pt_overruns;
                pt->pt_overruns = 0;
                i = 1 << pt->pt_entry;
                p->p_timers->pts_fired = i;
                p->p_timerpend = 1;

                sa = p->p_sa;
                mutex_enter(&sa->sa_mutex);
                SLIST_FOREACH(vp, &sa->sa_vps, savp_next) {
                        struct lwp *vp_lwp = vp->savp_lwp;
                        lwp_lock(vp_lwp);
                        lwp_need_userret(vp_lwp);
                        if (vp_lwp->l_flag & LW_SA_IDLE) {
                                vp_lwp->l_flag &= ~LW_SA_IDLE;
                                lwp_unsleep(vp_lwp, true);
                                break;
                        }
                        lwp_unlock(vp_lwp);
                }
                mutex_exit(&sa->sa_mutex);
        } else {
                i = 1 << pt->pt_entry;
                if ((p->p_timers->pts_fired & i) == 0) {
                        pt->pt_poverruns = pt->pt_overruns;
                        pt->pt_overruns = 0;
                        p->p_timers->pts_fired |= i;
                } else
                        pt->pt_overruns++;
        }
}
#endif /* KERN_SA */

static void
timer_intr(void *cookie)
{
        ksiginfo_t ksi;
        struct ptimer *pt;
        proc_t *p;
        
        mutex_enter(proc_lock);
        mutex_spin_enter(&timer_lock);
        while ((pt = TAILQ_FIRST(&timer_queue)) != NULL) {
                TAILQ_REMOVE(&timer_queue, pt, pt_chain);
                KASSERT(pt->pt_queued);
                pt->pt_queued = false;

                if (pt->pt_proc->p_timers == NULL) {
                        /* Process is dying. */
                        continue;
                }
                p = pt->pt_proc;
#ifdef KERN_SA
                if (pt->pt_ev.sigev_notify == SIGEV_SA) {
                        timer_sa_intr(pt, p);
                        continue;
                }
#endif /* KERN_SA */
                if (pt->pt_ev.sigev_notify != SIGEV_SIGNAL)
                        continue;
                if (sigismember(&p->p_sigpend.sp_set, pt->pt_ev.sigev_signo)) {
                        pt->pt_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 = pt->pt_overruns;
                pt->pt_overruns = 0;
                mutex_spin_exit(&timer_lock);
                kpsignal(p, &ksi, NULL);
                mutex_spin_enter(&timer_lock);
        }
        mutex_spin_exit(&timer_lock);
        mutex_exit(proc_lock);
}

/*
 * 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;
}