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33 * @(#)kern_time.c 8.1 (Berkeley) 6/10/93
34 * $FreeBSD: src/sys/kern/kern_time.c,v 1.68.2.1 2002/10/01 08:00:41 bde Exp $
37 #include <sys/param.h>
38 #include <sys/systm.h>
40 #include <sys/sysproto.h>
41 #include <sys/resourcevar.h>
42 #include <sys/signalvar.h>
43 #include <sys/kernel.h>
44 #include <sys/sysent.h>
45 #include <sys/sysunion.h>
49 #include <sys/vnode.h>
50 #include <sys/sysctl.h>
51 #include <sys/kern_syscall.h>
53 #include <vm/vm_extern.h>
55 #include <sys/msgport2.h>
56 #include <sys/thread2.h>
57 #include <sys/mplock2.h>
62 * Time of day and interval timer support.
64 * These routines provide the kernel entry points to get and set
65 * the time-of-day and per-process interval timers. Subroutines
66 * here provide support for adding and subtracting timeval structures
67 * and decrementing interval timers, optionally reloading the interval
68 * timers when they expire.
71 static int settime(struct timeval *);
72 static void timevalfix(struct timeval *);
75 * Nanosleep tries very hard to sleep for a precisely requested time
76 * interval, down to 1uS. The administrator can impose a minimum delay
77 * and a delay below which we hard-loop instead of initiate a timer
78 * interrupt and sleep.
80 * For machines under high loads it might be beneficial to increase min_us
81 * to e.g. 1000uS (1ms) so spining processes sleep meaningfully.
83 static int nanosleep_min_us = 10;
84 static int nanosleep_hard_us = 100;
85 SYSCTL_INT(_kern, OID_AUTO, nanosleep_min_us, CTLFLAG_RW,
86 &nanosleep_min_us, 0, "")
87 SYSCTL_INT(_kern, OID_AUTO, nanosleep_hard_us, CTLFLAG_RW,
88 &nanosleep_hard_us, 0, "")
91 settime(struct timeval *tv)
93 struct timeval delta, tv1, tv2;
94 static struct timeval maxtime, laststep;
98 if ((origcpu = mycpu->gd_cpuid) != 0)
99 lwkt_setcpu_self(globaldata_find(0));
104 timevalsub(&delta, &tv1);
107 * If the system is secure, we do not allow the time to be
108 * set to a value earlier than 1 second less than the highest
109 * time we have yet seen. The worst a miscreant can do in
110 * this circumstance is "freeze" time. He couldn't go
113 * We similarly do not allow the clock to be stepped more
114 * than one second, nor more than once per second. This allows
115 * a miscreant to make the clock march double-time, but no worse.
117 if (securelevel > 1) {
118 if (delta.tv_sec < 0 || delta.tv_usec < 0) {
120 * Update maxtime to latest time we've seen.
122 if (tv1.tv_sec > maxtime.tv_sec)
125 timevalsub(&tv2, &maxtime);
126 if (tv2.tv_sec < -1) {
127 tv->tv_sec = maxtime.tv_sec - 1;
128 kprintf("Time adjustment clamped to -1 second\n");
131 if (tv1.tv_sec == laststep.tv_sec) {
135 if (delta.tv_sec > 1) {
136 tv->tv_sec = tv1.tv_sec + 1;
137 kprintf("Time adjustment clamped to +1 second\n");
143 ts.tv_sec = tv->tv_sec;
144 ts.tv_nsec = tv->tv_usec * 1000;
149 lwkt_setcpu_self(globaldata_find(origcpu));
159 kern_clock_gettime(clockid_t clock_id, struct timespec *ats)
167 case CLOCK_MONOTONIC:
181 sys_clock_gettime(struct clock_gettime_args *uap)
186 error = kern_clock_gettime(uap->clock_id, &ats);
188 error = copyout(&ats, uap->tp, sizeof(ats));
194 kern_clock_settime(clockid_t clock_id, struct timespec *ats)
196 struct thread *td = curthread;
200 if ((error = priv_check(td, PRIV_CLOCK_SETTIME)) != 0)
202 if (clock_id != CLOCK_REALTIME)
204 if (ats->tv_nsec < 0 || ats->tv_nsec >= 1000000000)
207 TIMESPEC_TO_TIMEVAL(&atv, ats);
208 error = settime(&atv);
216 sys_clock_settime(struct clock_settime_args *uap)
221 if ((error = copyin(uap->tp, &ats, sizeof(ats))) != 0)
225 error = kern_clock_settime(uap->clock_id, &ats);
234 kern_clock_getres(clockid_t clock_id, struct timespec *ts)
240 case CLOCK_MONOTONIC:
242 * Round up the result of the division cheaply
243 * by adding 1. Rounding up is especially important
244 * if rounding down would give 0. Perfect rounding
248 ts->tv_nsec = 1000000000 / sys_cputimer->freq + 1;
263 sys_clock_getres(struct clock_getres_args *uap)
268 error = kern_clock_getres(uap->clock_id, &ts);
270 error = copyout(&ts, uap->tp, sizeof(ts));
278 * This is a general helper function for nanosleep() (aka sleep() aka
281 * If there is less then one tick's worth of time left and
282 * we haven't done a yield, or the remaining microseconds is
283 * ridiculously low, do a yield. This avoids having
284 * to deal with systimer overheads when the system is under
285 * heavy loads. If we have done a yield already then use
286 * a systimer and an uninterruptable thread wait.
288 * If there is more then a tick's worth of time left,
289 * calculate the baseline ticks and use an interruptable
290 * tsleep, then handle the fine-grained delay on the next
291 * loop. This usually results in two sleeps occuring, a long one
297 ns1_systimer(systimer_t info, int in_ipi __unused,
298 struct intrframe *frame __unused)
300 lwkt_schedule(info->data);
304 nanosleep1(struct timespec *rqt, struct timespec *rmt)
307 struct timespec ts, ts2, ts3;
311 if (rqt->tv_nsec < 0 || rqt->tv_nsec >= 1000000000)
313 /* XXX: imho this should return EINVAL at least for tv_sec < 0 */
314 if (rqt->tv_sec < 0 || (rqt->tv_sec == 0 && rqt->tv_nsec == 0))
317 timespecadd(&ts, rqt); /* ts = target timestamp compare */
318 TIMESPEC_TO_TIMEVAL(&tv, rqt); /* tv = sleep interval */
322 struct systimer info;
324 ticks = tv.tv_usec / ustick; /* approximate */
326 if (tv.tv_sec == 0 && ticks == 0) {
327 thread_t td = curthread;
328 if (tv.tv_usec > 0 && tv.tv_usec < nanosleep_min_us)
329 tv.tv_usec = nanosleep_min_us;
330 if (tv.tv_usec < nanosleep_hard_us) {
334 crit_enter_quick(td);
335 systimer_init_oneshot(&info, ns1_systimer,
337 lwkt_deschedule_self(td);
340 systimer_del(&info); /* make sure it's gone */
342 error = iscaught(td->td_lwp);
343 } else if (tv.tv_sec == 0) {
344 error = tsleep(&nanowait, PCATCH, "nanslp", ticks);
346 ticks = tvtohz_low(&tv); /* also handles overflow */
347 error = tsleep(&nanowait, PCATCH, "nanslp", ticks);
350 if (error && error != EWOULDBLOCK) {
351 if (error == ERESTART)
354 timespecsub(&ts, &ts2);
361 if (timespeccmp(&ts2, &ts, >=))
364 timespecsub(&ts3, &ts2);
365 TIMESPEC_TO_TIMEVAL(&tv, &ts3);
373 sys_nanosleep(struct nanosleep_args *uap)
379 error = copyin(uap->rqtp, &rqt, sizeof(rqt));
383 error = nanosleep1(&rqt, &rmt);
386 * copyout the residual if nanosleep was interrupted.
388 if (error && uap->rmtp) {
391 error2 = copyout(&rmt, uap->rmtp, sizeof(rmt));
402 sys_gettimeofday(struct gettimeofday_args *uap)
409 if ((error = copyout((caddr_t)&atv, (caddr_t)uap->tp,
414 error = copyout((caddr_t)&tz, (caddr_t)uap->tzp,
423 sys_settimeofday(struct settimeofday_args *uap)
425 struct thread *td = curthread;
430 if ((error = priv_check(td, PRIV_SETTIMEOFDAY)))
432 /* Verify all parameters before changing time. */
434 if ((error = copyin((caddr_t)uap->tv, (caddr_t)&atv,
437 if (atv.tv_usec < 0 || atv.tv_usec >= 1000000)
441 (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz, sizeof(atz))))
445 if (uap->tv && (error = settime(&atv))) {
456 kern_adjtime_common(void)
458 if ((ntp_delta >= 0 && ntp_delta < ntp_default_tick_delta) ||
459 (ntp_delta < 0 && ntp_delta > -ntp_default_tick_delta))
460 ntp_tick_delta = ntp_delta;
461 else if (ntp_delta > ntp_big_delta)
462 ntp_tick_delta = 10 * ntp_default_tick_delta;
463 else if (ntp_delta < -ntp_big_delta)
464 ntp_tick_delta = -10 * ntp_default_tick_delta;
465 else if (ntp_delta > 0)
466 ntp_tick_delta = ntp_default_tick_delta;
468 ntp_tick_delta = -ntp_default_tick_delta;
472 kern_adjtime(int64_t delta, int64_t *odelta)
476 if ((origcpu = mycpu->gd_cpuid) != 0)
477 lwkt_setcpu_self(globaldata_find(0));
482 kern_adjtime_common();
486 lwkt_setcpu_self(globaldata_find(origcpu));
490 kern_get_ntp_delta(int64_t *delta)
494 if ((origcpu = mycpu->gd_cpuid) != 0)
495 lwkt_setcpu_self(globaldata_find(0));
502 lwkt_setcpu_self(globaldata_find(origcpu));
506 kern_reladjtime(int64_t delta)
510 if ((origcpu = mycpu->gd_cpuid) != 0)
511 lwkt_setcpu_self(globaldata_find(0));
515 kern_adjtime_common();
519 lwkt_setcpu_self(globaldata_find(origcpu));
523 kern_adjfreq(int64_t rate)
527 if ((origcpu = mycpu->gd_cpuid) != 0)
528 lwkt_setcpu_self(globaldata_find(0));
531 ntp_tick_permanent = rate;
535 lwkt_setcpu_self(globaldata_find(origcpu));
542 sys_adjtime(struct adjtime_args *uap)
544 struct thread *td = curthread;
546 int64_t ndelta, odelta;
549 if ((error = priv_check(td, PRIV_ADJTIME)))
551 error = copyin(uap->delta, &atv, sizeof(struct timeval));
556 * Compute the total correction and the rate at which to apply it.
557 * Round the adjustment down to a whole multiple of the per-tick
558 * delta, so that after some number of incremental changes in
559 * hardclock(), tickdelta will become zero, lest the correction
560 * overshoot and start taking us away from the desired final time.
562 ndelta = (int64_t)atv.tv_sec * 1000000000 + atv.tv_usec * 1000;
564 kern_adjtime(ndelta, &odelta);
568 atv.tv_sec = odelta / 1000000000;
569 atv.tv_usec = odelta % 1000000000 / 1000;
570 copyout(&atv, uap->olddelta, sizeof(struct timeval));
576 sysctl_adjtime(SYSCTL_HANDLER_ARGS)
581 if (req->newptr != NULL) {
582 if (priv_check(curthread, PRIV_ROOT))
584 error = SYSCTL_IN(req, &delta, sizeof(delta));
587 kern_reladjtime(delta);
591 kern_get_ntp_delta(&delta);
592 error = SYSCTL_OUT(req, &delta, sizeof(delta));
597 * delta is in nanoseconds.
600 sysctl_delta(SYSCTL_HANDLER_ARGS)
602 int64_t delta, old_delta;
605 if (req->newptr != NULL) {
606 if (priv_check(curthread, PRIV_ROOT))
608 error = SYSCTL_IN(req, &delta, sizeof(delta));
611 kern_adjtime(delta, &old_delta);
614 if (req->oldptr != NULL)
615 kern_get_ntp_delta(&old_delta);
616 error = SYSCTL_OUT(req, &old_delta, sizeof(old_delta));
621 * frequency is in nanoseconds per second shifted left 32.
622 * kern_adjfreq() needs it in nanoseconds per tick shifted left 32.
625 sysctl_adjfreq(SYSCTL_HANDLER_ARGS)
630 if (req->newptr != NULL) {
631 if (priv_check(curthread, PRIV_ROOT))
633 error = SYSCTL_IN(req, &freqdelta, sizeof(freqdelta));
638 kern_adjfreq(freqdelta);
641 if (req->oldptr != NULL)
642 freqdelta = ntp_tick_permanent * hz;
643 error = SYSCTL_OUT(req, &freqdelta, sizeof(freqdelta));
650 SYSCTL_NODE(_kern, OID_AUTO, ntp, CTLFLAG_RW, 0, "NTP related controls");
651 SYSCTL_PROC(_kern_ntp, OID_AUTO, permanent,
652 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
653 sysctl_adjfreq, "Q", "permanent correction per second");
654 SYSCTL_PROC(_kern_ntp, OID_AUTO, delta,
655 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
656 sysctl_delta, "Q", "one-time delta");
657 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, big_delta, CTLFLAG_RD,
658 &ntp_big_delta, sizeof(ntp_big_delta), "Q",
659 "threshold for fast adjustment");
660 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, tick_delta, CTLFLAG_RD,
661 &ntp_tick_delta, sizeof(ntp_tick_delta), "LU",
662 "per-tick adjustment");
663 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, default_tick_delta, CTLFLAG_RD,
664 &ntp_default_tick_delta, sizeof(ntp_default_tick_delta), "LU",
665 "default per-tick adjustment");
666 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, next_leap_second, CTLFLAG_RW,
667 &ntp_leap_second, sizeof(ntp_leap_second), "LU",
669 SYSCTL_INT(_kern_ntp, OID_AUTO, insert_leap_second, CTLFLAG_RW,
670 &ntp_leap_insert, 0, "insert or remove leap second");
671 SYSCTL_PROC(_kern_ntp, OID_AUTO, adjust,
672 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
673 sysctl_adjtime, "Q", "relative adjust for delta");
676 * Get value of an interval timer. The process virtual and
677 * profiling virtual time timers are kept in the p_stats area, since
678 * they can be swapped out. These are kept internally in the
679 * way they are specified externally: in time until they expire.
681 * The real time interval timer is kept in the process table slot
682 * for the process, and its value (it_value) is kept as an
683 * absolute time rather than as a delta, so that it is easy to keep
684 * periodic real-time signals from drifting.
686 * Virtual time timers are processed in the hardclock() routine of
687 * kern_clock.c. The real time timer is processed by a timeout
688 * routine, called from the softclock() routine. Since a callout
689 * may be delayed in real time due to interrupt processing in the system,
690 * it is possible for the real time timeout routine (realitexpire, given below),
691 * to be delayed in real time past when it is supposed to occur. It
692 * does not suffice, therefore, to reload the real timer .it_value from the
693 * real time timers .it_interval. Rather, we compute the next time in
694 * absolute time the timer should go off.
699 sys_getitimer(struct getitimer_args *uap)
701 struct proc *p = curproc;
703 struct itimerval aitv;
705 if (uap->which > ITIMER_PROF)
707 lwkt_gettoken(&p->p_token);
708 if (uap->which == ITIMER_REAL) {
710 * Convert from absolute to relative time in .it_value
711 * part of real time timer. If time for real time timer
712 * has passed return 0, else return difference between
713 * current time and time for the timer to go off.
715 aitv = p->p_realtimer;
716 if (timevalisset(&aitv.it_value)) {
717 getmicrouptime(&ctv);
718 if (timevalcmp(&aitv.it_value, &ctv, <))
719 timevalclear(&aitv.it_value);
721 timevalsub(&aitv.it_value, &ctv);
724 aitv = p->p_timer[uap->which];
726 lwkt_reltoken(&p->p_token);
727 return (copyout(&aitv, uap->itv, sizeof (struct itimerval)));
734 sys_setitimer(struct setitimer_args *uap)
736 struct itimerval aitv;
738 struct itimerval *itvp;
739 struct proc *p = curproc;
742 if (uap->which > ITIMER_PROF)
745 if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv,
746 sizeof(struct itimerval))))
748 if ((uap->itv = uap->oitv) &&
749 (error = sys_getitimer((struct getitimer_args *)uap)))
753 if (itimerfix(&aitv.it_value))
755 if (!timevalisset(&aitv.it_value))
756 timevalclear(&aitv.it_interval);
757 else if (itimerfix(&aitv.it_interval))
759 lwkt_gettoken(&p->p_token);
760 if (uap->which == ITIMER_REAL) {
761 if (timevalisset(&p->p_realtimer.it_value))
762 callout_stop_sync(&p->p_ithandle);
763 if (timevalisset(&aitv.it_value))
764 callout_reset(&p->p_ithandle,
765 tvtohz_high(&aitv.it_value), realitexpire, p);
766 getmicrouptime(&ctv);
767 timevaladd(&aitv.it_value, &ctv);
768 p->p_realtimer = aitv;
770 p->p_timer[uap->which] = aitv;
773 p->p_flags &= ~P_SIGVTALRM;
776 p->p_flags &= ~P_SIGPROF;
780 lwkt_reltoken(&p->p_token);
785 * Real interval timer expired:
786 * send process whose timer expired an alarm signal.
787 * If time is not set up to reload, then just return.
788 * Else compute next time timer should go off which is > current time.
789 * This is where delay in processing this timeout causes multiple
790 * SIGALRM calls to be compressed into one.
791 * tvtohz_high() always adds 1 to allow for the time until the next clock
792 * interrupt being strictly less than 1 clock tick, but we don't want
793 * that here since we want to appear to be in sync with the clock
794 * interrupt even when we're delayed.
797 realitexpire(void *arg)
800 struct timeval ctv, ntv;
802 p = (struct proc *)arg;
804 lwkt_gettoken(&p->p_token);
806 if (!timevalisset(&p->p_realtimer.it_interval)) {
807 timevalclear(&p->p_realtimer.it_value);
811 timevaladd(&p->p_realtimer.it_value,
812 &p->p_realtimer.it_interval);
813 getmicrouptime(&ctv);
814 if (timevalcmp(&p->p_realtimer.it_value, &ctv, >)) {
815 ntv = p->p_realtimer.it_value;
816 timevalsub(&ntv, &ctv);
817 callout_reset(&p->p_ithandle, tvtohz_low(&ntv),
823 lwkt_reltoken(&p->p_token);
828 * Check that a proposed value to load into the .it_value or
829 * .it_interval part of an interval timer is acceptable, and
830 * fix it to have at least minimal value (i.e. if it is less
831 * than the resolution of the clock, round it up.)
836 itimerfix(struct timeval *tv)
839 if (tv->tv_sec < 0 || tv->tv_sec > 100000000 ||
840 tv->tv_usec < 0 || tv->tv_usec >= 1000000)
842 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < ustick)
843 tv->tv_usec = ustick;
848 * Decrement an interval timer by a specified number
849 * of microseconds, which must be less than a second,
850 * i.e. < 1000000. If the timer expires, then reload
851 * it. In this case, carry over (usec - old value) to
852 * reduce the value reloaded into the timer so that
853 * the timer does not drift. This routine assumes
854 * that it is called in a context where the timers
855 * on which it is operating cannot change in value.
858 itimerdecr(struct itimerval *itp, int usec)
861 if (itp->it_value.tv_usec < usec) {
862 if (itp->it_value.tv_sec == 0) {
863 /* expired, and already in next interval */
864 usec -= itp->it_value.tv_usec;
867 itp->it_value.tv_usec += 1000000;
868 itp->it_value.tv_sec--;
870 itp->it_value.tv_usec -= usec;
872 if (timevalisset(&itp->it_value))
874 /* expired, exactly at end of interval */
876 if (timevalisset(&itp->it_interval)) {
877 itp->it_value = itp->it_interval;
878 itp->it_value.tv_usec -= usec;
879 if (itp->it_value.tv_usec < 0) {
880 itp->it_value.tv_usec += 1000000;
881 itp->it_value.tv_sec--;
884 itp->it_value.tv_usec = 0; /* sec is already 0 */
889 * Add and subtract routines for timevals.
890 * N.B.: subtract routine doesn't deal with
891 * results which are before the beginning,
892 * it just gets very confused in this case.
896 timevaladd(struct timeval *t1, const struct timeval *t2)
899 t1->tv_sec += t2->tv_sec;
900 t1->tv_usec += t2->tv_usec;
905 timevalsub(struct timeval *t1, const struct timeval *t2)
908 t1->tv_sec -= t2->tv_sec;
909 t1->tv_usec -= t2->tv_usec;
914 timevalfix(struct timeval *t1)
917 if (t1->tv_usec < 0) {
919 t1->tv_usec += 1000000;
921 if (t1->tv_usec >= 1000000) {
923 t1->tv_usec -= 1000000;
928 * ratecheck(): simple time-based rate-limit checking.
931 ratecheck(struct timeval *lasttime, const struct timeval *mininterval)
933 struct timeval tv, delta;
936 getmicrouptime(&tv); /* NB: 10ms precision */
938 timevalsub(&delta, lasttime);
941 * check for 0,0 is so that the message will be seen at least once,
942 * even if interval is huge.
944 if (timevalcmp(&delta, mininterval, >=) ||
945 (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
954 * ppsratecheck(): packets (or events) per second limitation.
956 * Return 0 if the limit is to be enforced (e.g. the caller
957 * should drop a packet because of the rate limitation).
959 * maxpps of 0 always causes zero to be returned. maxpps of -1
960 * always causes 1 to be returned; this effectively defeats rate
963 * Note that we maintain the struct timeval for compatibility
964 * with other bsd systems. We reuse the storage and just monitor
965 * clock ticks for minimal overhead.
968 ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
973 * Reset the last time and counter if this is the first call
974 * or more than a second has passed since the last update of
978 if (lasttime->tv_sec == 0 || (u_int)(now - lasttime->tv_sec) >= hz) {
979 lasttime->tv_sec = now;
981 return (maxpps != 0);
983 (*curpps)++; /* NB: ignore potential overflow */
984 return (maxpps < 0 || *curpps < maxpps);