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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 $
35 * $DragonFly: src/sys/kern/kern_time.c,v 1.40 2008/04/02 14:16:16 sephe Exp $
38 #include <sys/param.h>
39 #include <sys/systm.h>
41 #include <sys/sysproto.h>
42 #include <sys/resourcevar.h>
43 #include <sys/signalvar.h>
44 #include <sys/kernel.h>
45 #include <sys/systm.h>
46 #include <sys/sysent.h>
47 #include <sys/sysunion.h>
51 #include <sys/vnode.h>
52 #include <sys/sysctl.h>
53 #include <sys/kern_syscall.h>
55 #include <vm/vm_extern.h>
57 #include <sys/msgport2.h>
58 #include <sys/thread2.h>
59 #include <sys/mplock2.h>
64 * Time of day and interval timer support.
66 * These routines provide the kernel entry points to get and set
67 * the time-of-day and per-process interval timers. Subroutines
68 * here provide support for adding and subtracting timeval structures
69 * and decrementing interval timers, optionally reloading the interval
70 * timers when they expire.
73 int nanosleep1(struct timespec *rqt, struct timespec *rmt);
74 static int settime(struct timeval *);
75 static void timevalfix(struct timeval *);
77 static int sleep_hard_us = 100;
78 SYSCTL_INT(_kern, OID_AUTO, sleep_hard_us, CTLFLAG_RW, &sleep_hard_us, 0, "")
81 settime(struct timeval *tv)
83 struct timeval delta, tv1, tv2;
84 static struct timeval maxtime, laststep;
88 if ((origcpu = mycpu->gd_cpuid) != 0)
89 lwkt_setcpu_self(globaldata_find(0));
94 timevalsub(&delta, &tv1);
97 * If the system is secure, we do not allow the time to be
98 * set to a value earlier than 1 second less than the highest
99 * time we have yet seen. The worst a miscreant can do in
100 * this circumstance is "freeze" time. He couldn't go
103 * We similarly do not allow the clock to be stepped more
104 * than one second, nor more than once per second. This allows
105 * a miscreant to make the clock march double-time, but no worse.
107 if (securelevel > 1) {
108 if (delta.tv_sec < 0 || delta.tv_usec < 0) {
110 * Update maxtime to latest time we've seen.
112 if (tv1.tv_sec > maxtime.tv_sec)
115 timevalsub(&tv2, &maxtime);
116 if (tv2.tv_sec < -1) {
117 tv->tv_sec = maxtime.tv_sec - 1;
118 kprintf("Time adjustment clamped to -1 second\n");
121 if (tv1.tv_sec == laststep.tv_sec) {
125 if (delta.tv_sec > 1) {
126 tv->tv_sec = tv1.tv_sec + 1;
127 kprintf("Time adjustment clamped to +1 second\n");
133 ts.tv_sec = tv->tv_sec;
134 ts.tv_nsec = tv->tv_usec * 1000;
139 lwkt_setcpu_self(globaldata_find(origcpu));
149 kern_clock_gettime(clockid_t clock_id, struct timespec *ats)
157 case CLOCK_MONOTONIC:
171 sys_clock_gettime(struct clock_gettime_args *uap)
176 error = kern_clock_gettime(uap->clock_id, &ats);
178 error = copyout(&ats, uap->tp, sizeof(ats));
184 kern_clock_settime(clockid_t clock_id, struct timespec *ats)
186 struct thread *td = curthread;
190 if ((error = priv_check(td, PRIV_CLOCK_SETTIME)) != 0)
192 if (clock_id != CLOCK_REALTIME)
194 if (ats->tv_nsec < 0 || ats->tv_nsec >= 1000000000)
197 TIMESPEC_TO_TIMEVAL(&atv, ats);
198 error = settime(&atv);
206 sys_clock_settime(struct clock_settime_args *uap)
211 if ((error = copyin(uap->tp, &ats, sizeof(ats))) != 0)
215 error = kern_clock_settime(uap->clock_id, &ats);
224 kern_clock_getres(clockid_t clock_id, struct timespec *ts)
230 case CLOCK_MONOTONIC:
232 * Round up the result of the division cheaply
233 * by adding 1. Rounding up is especially important
234 * if rounding down would give 0. Perfect rounding
238 ts->tv_nsec = 1000000000 / sys_cputimer->freq + 1;
253 sys_clock_getres(struct clock_getres_args *uap)
258 error = kern_clock_getres(uap->clock_id, &ts);
260 error = copyout(&ts, uap->tp, sizeof(ts));
268 * This is a general helper function for nanosleep() (aka sleep() aka
271 * If there is less then one tick's worth of time left and
272 * we haven't done a yield, or the remaining microseconds is
273 * ridiculously low, do a yield. This avoids having
274 * to deal with systimer overheads when the system is under
275 * heavy loads. If we have done a yield already then use
276 * a systimer and an uninterruptable thread wait.
278 * If there is more then a tick's worth of time left,
279 * calculate the baseline ticks and use an interruptable
280 * tsleep, then handle the fine-grained delay on the next
281 * loop. This usually results in two sleeps occuring, a long one
287 ns1_systimer(systimer_t info)
289 lwkt_schedule(info->data);
293 nanosleep1(struct timespec *rqt, struct timespec *rmt)
296 struct timespec ts, ts2, ts3;
300 if (rqt->tv_nsec < 0 || rqt->tv_nsec >= 1000000000)
302 /* XXX: imho this should return EINVAL at least for tv_sec < 0 */
303 if (rqt->tv_sec < 0 || (rqt->tv_sec == 0 && rqt->tv_nsec == 0))
306 timespecadd(&ts, rqt); /* ts = target timestamp compare */
307 TIMESPEC_TO_TIMEVAL(&tv, rqt); /* tv = sleep interval */
311 struct systimer info;
313 ticks = tv.tv_usec / ustick; /* approximate */
315 if (tv.tv_sec == 0 && ticks == 0) {
316 thread_t td = curthread;
317 if (tv.tv_usec < sleep_hard_us) {
320 crit_enter_quick(td);
321 systimer_init_oneshot(&info, ns1_systimer,
323 lwkt_deschedule_self(td);
326 systimer_del(&info); /* make sure it's gone */
328 error = iscaught(td->td_lwp);
329 } else if (tv.tv_sec == 0) {
330 error = tsleep(&nanowait, PCATCH, "nanslp", ticks);
332 ticks = tvtohz_low(&tv); /* also handles overflow */
333 error = tsleep(&nanowait, PCATCH, "nanslp", ticks);
336 if (error && error != EWOULDBLOCK) {
337 if (error == ERESTART)
340 timespecsub(&ts, &ts2);
347 if (timespeccmp(&ts2, &ts, >=))
350 timespecsub(&ts3, &ts2);
351 TIMESPEC_TO_TIMEVAL(&tv, &ts3);
359 sys_nanosleep(struct nanosleep_args *uap)
365 error = copyin(uap->rqtp, &rqt, sizeof(rqt));
369 error = nanosleep1(&rqt, &rmt);
372 * copyout the residual if nanosleep was interrupted.
374 if (error && uap->rmtp) {
377 error2 = copyout(&rmt, uap->rmtp, sizeof(rmt));
388 sys_gettimeofday(struct gettimeofday_args *uap)
395 if ((error = copyout((caddr_t)&atv, (caddr_t)uap->tp,
400 error = copyout((caddr_t)&tz, (caddr_t)uap->tzp,
409 sys_settimeofday(struct settimeofday_args *uap)
411 struct thread *td = curthread;
416 if ((error = priv_check(td, PRIV_SETTIMEOFDAY)))
418 /* Verify all parameters before changing time. */
420 if ((error = copyin((caddr_t)uap->tv, (caddr_t)&atv,
423 if (atv.tv_usec < 0 || atv.tv_usec >= 1000000)
427 (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz, sizeof(atz))))
431 if (uap->tv && (error = settime(&atv))) {
442 kern_adjtime_common(void)
444 if ((ntp_delta >= 0 && ntp_delta < ntp_default_tick_delta) ||
445 (ntp_delta < 0 && ntp_delta > -ntp_default_tick_delta))
446 ntp_tick_delta = ntp_delta;
447 else if (ntp_delta > ntp_big_delta)
448 ntp_tick_delta = 10 * ntp_default_tick_delta;
449 else if (ntp_delta < -ntp_big_delta)
450 ntp_tick_delta = -10 * ntp_default_tick_delta;
451 else if (ntp_delta > 0)
452 ntp_tick_delta = ntp_default_tick_delta;
454 ntp_tick_delta = -ntp_default_tick_delta;
458 kern_adjtime(int64_t delta, int64_t *odelta)
462 if ((origcpu = mycpu->gd_cpuid) != 0)
463 lwkt_setcpu_self(globaldata_find(0));
468 kern_adjtime_common();
472 lwkt_setcpu_self(globaldata_find(origcpu));
476 kern_get_ntp_delta(int64_t *delta)
480 if ((origcpu = mycpu->gd_cpuid) != 0)
481 lwkt_setcpu_self(globaldata_find(0));
488 lwkt_setcpu_self(globaldata_find(origcpu));
492 kern_reladjtime(int64_t delta)
496 if ((origcpu = mycpu->gd_cpuid) != 0)
497 lwkt_setcpu_self(globaldata_find(0));
501 kern_adjtime_common();
505 lwkt_setcpu_self(globaldata_find(origcpu));
509 kern_adjfreq(int64_t rate)
513 if ((origcpu = mycpu->gd_cpuid) != 0)
514 lwkt_setcpu_self(globaldata_find(0));
517 ntp_tick_permanent = rate;
521 lwkt_setcpu_self(globaldata_find(origcpu));
528 sys_adjtime(struct adjtime_args *uap)
530 struct thread *td = curthread;
532 int64_t ndelta, odelta;
535 if ((error = priv_check(td, PRIV_ADJTIME)))
537 error = copyin(uap->delta, &atv, sizeof(struct timeval));
542 * Compute the total correction and the rate at which to apply it.
543 * Round the adjustment down to a whole multiple of the per-tick
544 * delta, so that after some number of incremental changes in
545 * hardclock(), tickdelta will become zero, lest the correction
546 * overshoot and start taking us away from the desired final time.
548 ndelta = (int64_t)atv.tv_sec * 1000000000 + atv.tv_usec * 1000;
550 kern_adjtime(ndelta, &odelta);
554 atv.tv_sec = odelta / 1000000000;
555 atv.tv_usec = odelta % 1000000000 / 1000;
556 copyout(&atv, uap->olddelta, sizeof(struct timeval));
562 sysctl_adjtime(SYSCTL_HANDLER_ARGS)
567 if (req->newptr != NULL) {
568 if (priv_check(curthread, PRIV_ROOT))
570 error = SYSCTL_IN(req, &delta, sizeof(delta));
573 kern_reladjtime(delta);
577 kern_get_ntp_delta(&delta);
578 error = SYSCTL_OUT(req, &delta, sizeof(delta));
583 * delta is in nanoseconds.
586 sysctl_delta(SYSCTL_HANDLER_ARGS)
588 int64_t delta, old_delta;
591 if (req->newptr != NULL) {
592 if (priv_check(curthread, PRIV_ROOT))
594 error = SYSCTL_IN(req, &delta, sizeof(delta));
597 kern_adjtime(delta, &old_delta);
600 if (req->oldptr != NULL)
601 kern_get_ntp_delta(&old_delta);
602 error = SYSCTL_OUT(req, &old_delta, sizeof(old_delta));
607 * frequency is in nanoseconds per second shifted left 32.
608 * kern_adjfreq() needs it in nanoseconds per tick shifted left 32.
611 sysctl_adjfreq(SYSCTL_HANDLER_ARGS)
616 if (req->newptr != NULL) {
617 if (priv_check(curthread, PRIV_ROOT))
619 error = SYSCTL_IN(req, &freqdelta, sizeof(freqdelta));
624 kern_adjfreq(freqdelta);
627 if (req->oldptr != NULL)
628 freqdelta = ntp_tick_permanent * hz;
629 error = SYSCTL_OUT(req, &freqdelta, sizeof(freqdelta));
636 SYSCTL_NODE(_kern, OID_AUTO, ntp, CTLFLAG_RW, 0, "NTP related controls");
637 SYSCTL_PROC(_kern_ntp, OID_AUTO, permanent,
638 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
639 sysctl_adjfreq, "Q", "permanent correction per second");
640 SYSCTL_PROC(_kern_ntp, OID_AUTO, delta,
641 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
642 sysctl_delta, "Q", "one-time delta");
643 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, big_delta, CTLFLAG_RD,
644 &ntp_big_delta, sizeof(ntp_big_delta), "Q",
645 "threshold for fast adjustment");
646 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, tick_delta, CTLFLAG_RD,
647 &ntp_tick_delta, sizeof(ntp_tick_delta), "LU",
648 "per-tick adjustment");
649 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, default_tick_delta, CTLFLAG_RD,
650 &ntp_default_tick_delta, sizeof(ntp_default_tick_delta), "LU",
651 "default per-tick adjustment");
652 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, next_leap_second, CTLFLAG_RW,
653 &ntp_leap_second, sizeof(ntp_leap_second), "LU",
655 SYSCTL_INT(_kern_ntp, OID_AUTO, insert_leap_second, CTLFLAG_RW,
656 &ntp_leap_insert, 0, "insert or remove leap second");
657 SYSCTL_PROC(_kern_ntp, OID_AUTO, adjust,
658 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
659 sysctl_adjtime, "Q", "relative adjust for delta");
662 * Get value of an interval timer. The process virtual and
663 * profiling virtual time timers are kept in the p_stats area, since
664 * they can be swapped out. These are kept internally in the
665 * way they are specified externally: in time until they expire.
667 * The real time interval timer is kept in the process table slot
668 * for the process, and its value (it_value) is kept as an
669 * absolute time rather than as a delta, so that it is easy to keep
670 * periodic real-time signals from drifting.
672 * Virtual time timers are processed in the hardclock() routine of
673 * kern_clock.c. The real time timer is processed by a timeout
674 * routine, called from the softclock() routine. Since a callout
675 * may be delayed in real time due to interrupt processing in the system,
676 * it is possible for the real time timeout routine (realitexpire, given below),
677 * to be delayed in real time past when it is supposed to occur. It
678 * does not suffice, therefore, to reload the real timer .it_value from the
679 * real time timers .it_interval. Rather, we compute the next time in
680 * absolute time the timer should go off.
685 sys_getitimer(struct getitimer_args *uap)
687 struct proc *p = curproc;
689 struct itimerval aitv;
691 if (uap->which > ITIMER_PROF)
695 if (uap->which == ITIMER_REAL) {
697 * Convert from absolute to relative time in .it_value
698 * part of real time timer. If time for real time timer
699 * has passed return 0, else return difference between
700 * current time and time for the timer to go off.
702 aitv = p->p_realtimer;
703 if (timevalisset(&aitv.it_value)) {
704 getmicrouptime(&ctv);
705 if (timevalcmp(&aitv.it_value, &ctv, <))
706 timevalclear(&aitv.it_value);
708 timevalsub(&aitv.it_value, &ctv);
711 aitv = p->p_timer[uap->which];
715 return (copyout(&aitv, uap->itv, sizeof (struct itimerval)));
722 sys_setitimer(struct setitimer_args *uap)
724 struct itimerval aitv;
726 struct itimerval *itvp;
727 struct proc *p = curproc;
730 if (uap->which > ITIMER_PROF)
733 if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv,
734 sizeof(struct itimerval))))
736 if ((uap->itv = uap->oitv) &&
737 (error = sys_getitimer((struct getitimer_args *)uap)))
741 if (itimerfix(&aitv.it_value))
743 if (!timevalisset(&aitv.it_value))
744 timevalclear(&aitv.it_interval);
745 else if (itimerfix(&aitv.it_interval))
749 if (uap->which == ITIMER_REAL) {
750 if (timevalisset(&p->p_realtimer.it_value))
751 callout_stop(&p->p_ithandle);
752 if (timevalisset(&aitv.it_value))
753 callout_reset(&p->p_ithandle,
754 tvtohz_high(&aitv.it_value), realitexpire, p);
755 getmicrouptime(&ctv);
756 timevaladd(&aitv.it_value, &ctv);
757 p->p_realtimer = aitv;
759 p->p_timer[uap->which] = aitv;
767 * Real interval timer expired:
768 * send process whose timer expired an alarm signal.
769 * If time is not set up to reload, then just return.
770 * Else compute next time timer should go off which is > current time.
771 * This is where delay in processing this timeout causes multiple
772 * SIGALRM calls to be compressed into one.
773 * tvtohz_high() always adds 1 to allow for the time until the next clock
774 * interrupt being strictly less than 1 clock tick, but we don't want
775 * that here since we want to appear to be in sync with the clock
776 * interrupt even when we're delayed.
779 realitexpire(void *arg)
782 struct timeval ctv, ntv;
784 p = (struct proc *)arg;
786 if (!timevalisset(&p->p_realtimer.it_interval)) {
787 timevalclear(&p->p_realtimer.it_value);
792 timevaladd(&p->p_realtimer.it_value,
793 &p->p_realtimer.it_interval);
794 getmicrouptime(&ctv);
795 if (timevalcmp(&p->p_realtimer.it_value, &ctv, >)) {
796 ntv = p->p_realtimer.it_value;
797 timevalsub(&ntv, &ctv);
798 callout_reset(&p->p_ithandle, tvtohz_low(&ntv),
808 * Check that a proposed value to load into the .it_value or
809 * .it_interval part of an interval timer is acceptable, and
810 * fix it to have at least minimal value (i.e. if it is less
811 * than the resolution of the clock, round it up.)
816 itimerfix(struct timeval *tv)
819 if (tv->tv_sec < 0 || tv->tv_sec > 100000000 ||
820 tv->tv_usec < 0 || tv->tv_usec >= 1000000)
822 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < ustick)
823 tv->tv_usec = ustick;
828 * Decrement an interval timer by a specified number
829 * of microseconds, which must be less than a second,
830 * i.e. < 1000000. If the timer expires, then reload
831 * it. In this case, carry over (usec - old value) to
832 * reduce the value reloaded into the timer so that
833 * the timer does not drift. This routine assumes
834 * that it is called in a context where the timers
835 * on which it is operating cannot change in value.
838 itimerdecr(struct itimerval *itp, int usec)
841 if (itp->it_value.tv_usec < usec) {
842 if (itp->it_value.tv_sec == 0) {
843 /* expired, and already in next interval */
844 usec -= itp->it_value.tv_usec;
847 itp->it_value.tv_usec += 1000000;
848 itp->it_value.tv_sec--;
850 itp->it_value.tv_usec -= usec;
852 if (timevalisset(&itp->it_value))
854 /* expired, exactly at end of interval */
856 if (timevalisset(&itp->it_interval)) {
857 itp->it_value = itp->it_interval;
858 itp->it_value.tv_usec -= usec;
859 if (itp->it_value.tv_usec < 0) {
860 itp->it_value.tv_usec += 1000000;
861 itp->it_value.tv_sec--;
864 itp->it_value.tv_usec = 0; /* sec is already 0 */
869 * Add and subtract routines for timevals.
870 * N.B.: subtract routine doesn't deal with
871 * results which are before the beginning,
872 * it just gets very confused in this case.
876 timevaladd(struct timeval *t1, const struct timeval *t2)
879 t1->tv_sec += t2->tv_sec;
880 t1->tv_usec += t2->tv_usec;
885 timevalsub(struct timeval *t1, const struct timeval *t2)
888 t1->tv_sec -= t2->tv_sec;
889 t1->tv_usec -= t2->tv_usec;
894 timevalfix(struct timeval *t1)
897 if (t1->tv_usec < 0) {
899 t1->tv_usec += 1000000;
901 if (t1->tv_usec >= 1000000) {
903 t1->tv_usec -= 1000000;
908 * ratecheck(): simple time-based rate-limit checking.
911 ratecheck(struct timeval *lasttime, const struct timeval *mininterval)
913 struct timeval tv, delta;
916 getmicrouptime(&tv); /* NB: 10ms precision */
918 timevalsub(&delta, lasttime);
921 * check for 0,0 is so that the message will be seen at least once,
922 * even if interval is huge.
924 if (timevalcmp(&delta, mininterval, >=) ||
925 (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
934 * ppsratecheck(): packets (or events) per second limitation.
936 * Return 0 if the limit is to be enforced (e.g. the caller
937 * should drop a packet because of the rate limitation).
939 * maxpps of 0 always causes zero to be returned. maxpps of -1
940 * always causes 1 to be returned; this effectively defeats rate
943 * Note that we maintain the struct timeval for compatibility
944 * with other bsd systems. We reuse the storage and just monitor
945 * clock ticks for minimal overhead.
948 ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
953 * Reset the last time and counter if this is the first call
954 * or more than a second has passed since the last update of
958 if (lasttime->tv_sec == 0 || (u_int)(now - lasttime->tv_sec) >= hz) {
959 lasttime->tv_sec = now;
961 return (maxpps != 0);
963 (*curpps)++; /* NB: ignore potential overflow */
964 return (maxpps < 0 || *curpps < maxpps);