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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>
56 #include <sys/msgport2.h>
57 #include <sys/thread2.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 nanosleep1(struct timespec *rqt, struct timespec *rmt);
72 static int settime(struct timeval *);
73 static void timevalfix(struct timeval *);
75 static int sleep_hard_us = 100;
76 SYSCTL_INT(_kern, OID_AUTO, sleep_hard_us, CTLFLAG_RW, &sleep_hard_us, 0, "")
79 settime(struct timeval *tv)
81 struct timeval delta, tv1, tv2;
82 static struct timeval maxtime, laststep;
86 if ((origcpu = mycpu->gd_cpuid) != 0)
87 lwkt_setcpu_self(globaldata_find(0));
92 timevalsub(&delta, &tv1);
95 * If the system is secure, we do not allow the time to be
96 * set to a value earlier than 1 second less than the highest
97 * time we have yet seen. The worst a miscreant can do in
98 * this circumstance is "freeze" time. He couldn't go
101 * We similarly do not allow the clock to be stepped more
102 * than one second, nor more than once per second. This allows
103 * a miscreant to make the clock march double-time, but no worse.
105 if (securelevel > 1) {
106 if (delta.tv_sec < 0 || delta.tv_usec < 0) {
108 * Update maxtime to latest time we've seen.
110 if (tv1.tv_sec > maxtime.tv_sec)
113 timevalsub(&tv2, &maxtime);
114 if (tv2.tv_sec < -1) {
115 tv->tv_sec = maxtime.tv_sec - 1;
116 kprintf("Time adjustment clamped to -1 second\n");
119 if (tv1.tv_sec == laststep.tv_sec) {
123 if (delta.tv_sec > 1) {
124 tv->tv_sec = tv1.tv_sec + 1;
125 kprintf("Time adjustment clamped to +1 second\n");
131 ts.tv_sec = tv->tv_sec;
132 ts.tv_nsec = tv->tv_usec * 1000;
137 lwkt_setcpu_self(globaldata_find(origcpu));
144 kern_clock_gettime(clockid_t clock_id, struct timespec *ats)
152 case CLOCK_MONOTONIC:
164 sys_clock_gettime(struct clock_gettime_args *uap)
169 error = kern_clock_gettime(uap->clock_id, &ats);
171 error = copyout(&ats, uap->tp, sizeof(ats));
177 kern_clock_settime(clockid_t clock_id, struct timespec *ats)
179 struct thread *td = curthread;
183 if ((error = priv_check(td, PRIV_ROOT)) != 0)
185 if (clock_id != CLOCK_REALTIME)
187 if (ats->tv_nsec < 0 || ats->tv_nsec >= 1000000000)
190 TIMESPEC_TO_TIMEVAL(&atv, ats);
191 error = settime(&atv);
197 sys_clock_settime(struct clock_settime_args *uap)
202 if ((error = copyin(uap->tp, &ats, sizeof(ats))) != 0)
205 return (kern_clock_settime(uap->clock_id, &ats));
209 kern_clock_getres(clockid_t clock_id, struct timespec *ts)
215 case CLOCK_MONOTONIC:
217 * Round up the result of the division cheaply
218 * by adding 1. Rounding up is especially important
219 * if rounding down would give 0. Perfect rounding
223 ts->tv_nsec = 1000000000 / sys_cputimer->freq + 1;
235 sys_clock_getres(struct clock_getres_args *uap)
240 error = kern_clock_getres(uap->clock_id, &ts);
242 error = copyout(&ts, uap->tp, sizeof(ts));
250 * This is a general helper function for nanosleep() (aka sleep() aka
253 * If there is less then one tick's worth of time left and
254 * we haven't done a yield, or the remaining microseconds is
255 * ridiculously low, do a yield. This avoids having
256 * to deal with systimer overheads when the system is under
257 * heavy loads. If we have done a yield already then use
258 * a systimer and an uninterruptable thread wait.
260 * If there is more then a tick's worth of time left,
261 * calculate the baseline ticks and use an interruptable
262 * tsleep, then handle the fine-grained delay on the next
263 * loop. This usually results in two sleeps occuring, a long one
267 ns1_systimer(systimer_t info)
269 lwkt_schedule(info->data);
273 nanosleep1(struct timespec *rqt, struct timespec *rmt)
276 struct timespec ts, ts2, ts3;
281 if (rqt->tv_nsec < 0 || rqt->tv_nsec >= 1000000000)
283 if (rqt->tv_sec < 0 || (rqt->tv_sec == 0 && rqt->tv_nsec == 0))
286 timespecadd(&ts, rqt); /* ts = target timestamp compare */
287 TIMESPEC_TO_TIMEVAL(&tv, rqt); /* tv = sleep interval */
292 struct systimer info;
294 ticks = tv.tv_usec / tick; /* approximate */
296 if (tv.tv_sec == 0 && ticks == 0) {
297 thread_t td = curthread;
298 if (tried_yield || tv.tv_usec < sleep_hard_us) {
302 crit_enter_quick(td);
303 systimer_init_oneshot(&info, ns1_systimer,
305 lwkt_deschedule_self(td);
308 systimer_del(&info); /* make sure it's gone */
310 error = iscaught(td->td_lwp);
311 } else if (tv.tv_sec == 0) {
312 error = tsleep(&nanowait, PCATCH, "nanslp", ticks);
314 ticks = tvtohz_low(&tv); /* also handles overflow */
315 error = tsleep(&nanowait, PCATCH, "nanslp", ticks);
318 if (error && error != EWOULDBLOCK) {
319 if (error == ERESTART)
322 timespecsub(&ts, &ts2);
329 if (timespeccmp(&ts2, &ts, >=))
332 timespecsub(&ts3, &ts2);
333 TIMESPEC_TO_TIMEVAL(&tv, &ts3);
339 sys_nanosleep(struct nanosleep_args *uap)
345 error = copyin(uap->rqtp, &rqt, sizeof(rqt));
349 error = nanosleep1(&rqt, &rmt);
352 * copyout the residual if nanosleep was interrupted.
354 if (error && uap->rmtp)
355 error = copyout(&rmt, uap->rmtp, sizeof(rmt));
361 sys_gettimeofday(struct gettimeofday_args *uap)
368 if ((error = copyout((caddr_t)&atv, (caddr_t)uap->tp,
373 error = copyout((caddr_t)&tz, (caddr_t)uap->tzp,
380 sys_settimeofday(struct settimeofday_args *uap)
382 struct thread *td = curthread;
387 if ((error = priv_check(td, PRIV_ROOT)))
389 /* Verify all parameters before changing time. */
391 if ((error = copyin((caddr_t)uap->tv, (caddr_t)&atv,
394 if (atv.tv_usec < 0 || atv.tv_usec >= 1000000)
398 (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz, sizeof(atz))))
400 if (uap->tv && (error = settime(&atv)))
408 kern_adjtime_common(void)
410 if ((ntp_delta >= 0 && ntp_delta < ntp_default_tick_delta) ||
411 (ntp_delta < 0 && ntp_delta > -ntp_default_tick_delta))
412 ntp_tick_delta = ntp_delta;
413 else if (ntp_delta > ntp_big_delta)
414 ntp_tick_delta = 10 * ntp_default_tick_delta;
415 else if (ntp_delta < -ntp_big_delta)
416 ntp_tick_delta = -10 * ntp_default_tick_delta;
417 else if (ntp_delta > 0)
418 ntp_tick_delta = ntp_default_tick_delta;
420 ntp_tick_delta = -ntp_default_tick_delta;
424 kern_adjtime(int64_t delta, int64_t *odelta)
428 if ((origcpu = mycpu->gd_cpuid) != 0)
429 lwkt_setcpu_self(globaldata_find(0));
434 kern_adjtime_common();
438 lwkt_setcpu_self(globaldata_find(origcpu));
442 kern_get_ntp_delta(int64_t *delta)
446 if ((origcpu = mycpu->gd_cpuid) != 0)
447 lwkt_setcpu_self(globaldata_find(0));
454 lwkt_setcpu_self(globaldata_find(origcpu));
458 kern_reladjtime(int64_t delta)
462 if ((origcpu = mycpu->gd_cpuid) != 0)
463 lwkt_setcpu_self(globaldata_find(0));
467 kern_adjtime_common();
471 lwkt_setcpu_self(globaldata_find(origcpu));
475 kern_adjfreq(int64_t rate)
479 if ((origcpu = mycpu->gd_cpuid) != 0)
480 lwkt_setcpu_self(globaldata_find(0));
483 ntp_tick_permanent = rate;
487 lwkt_setcpu_self(globaldata_find(origcpu));
492 sys_adjtime(struct adjtime_args *uap)
494 struct thread *td = curthread;
496 int64_t ndelta, odelta;
499 if ((error = priv_check(td, PRIV_ROOT)))
502 copyin((caddr_t)uap->delta, (caddr_t)&atv, sizeof(struct timeval))))
506 * Compute the total correction and the rate at which to apply it.
507 * Round the adjustment down to a whole multiple of the per-tick
508 * delta, so that after some number of incremental changes in
509 * hardclock(), tickdelta will become zero, lest the correction
510 * overshoot and start taking us away from the desired final time.
512 ndelta = (int64_t)atv.tv_sec * 1000000000 + atv.tv_usec * 1000;
513 kern_adjtime(ndelta, &odelta);
516 atv.tv_sec = odelta / 1000000000;
517 atv.tv_usec = odelta % 1000000000 / 1000;
518 (void) copyout((caddr_t)&atv, (caddr_t)uap->olddelta,
519 sizeof(struct timeval));
525 sysctl_adjtime(SYSCTL_HANDLER_ARGS)
530 if (req->newptr != NULL) {
531 if (priv_check(curthread, PRIV_ROOT))
533 error = SYSCTL_IN(req, &delta, sizeof(delta));
536 kern_reladjtime(delta);
540 kern_get_ntp_delta(&delta);
541 error = SYSCTL_OUT(req, &delta, sizeof(delta));
546 * delta is in nanoseconds.
549 sysctl_delta(SYSCTL_HANDLER_ARGS)
551 int64_t delta, old_delta;
554 if (req->newptr != NULL) {
555 if (priv_check(curthread, PRIV_ROOT))
557 error = SYSCTL_IN(req, &delta, sizeof(delta));
560 kern_adjtime(delta, &old_delta);
563 if (req->oldptr != NULL)
564 kern_get_ntp_delta(&old_delta);
565 error = SYSCTL_OUT(req, &old_delta, sizeof(old_delta));
570 * frequency is in nanoseconds per second shifted left 32.
571 * kern_adjfreq() needs it in nanoseconds per tick shifted left 32.
574 sysctl_adjfreq(SYSCTL_HANDLER_ARGS)
579 if (req->newptr != NULL) {
580 if (priv_check(curthread, PRIV_ROOT))
582 error = SYSCTL_IN(req, &freqdelta, sizeof(freqdelta));
587 kern_adjfreq(freqdelta);
590 if (req->oldptr != NULL)
591 freqdelta = ntp_tick_permanent * hz;
592 error = SYSCTL_OUT(req, &freqdelta, sizeof(freqdelta));
599 SYSCTL_NODE(_kern, OID_AUTO, ntp, CTLFLAG_RW, 0, "NTP related controls");
600 SYSCTL_PROC(_kern_ntp, OID_AUTO, permanent,
601 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
602 sysctl_adjfreq, "Q", "permanent correction per second");
603 SYSCTL_PROC(_kern_ntp, OID_AUTO, delta,
604 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
605 sysctl_delta, "Q", "one-time delta");
606 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, big_delta, CTLFLAG_RD,
607 &ntp_big_delta, sizeof(ntp_big_delta), "Q",
608 "threshold for fast adjustment");
609 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, tick_delta, CTLFLAG_RD,
610 &ntp_tick_delta, sizeof(ntp_tick_delta), "LU",
611 "per-tick adjustment");
612 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, default_tick_delta, CTLFLAG_RD,
613 &ntp_default_tick_delta, sizeof(ntp_default_tick_delta), "LU",
614 "default per-tick adjustment");
615 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, next_leap_second, CTLFLAG_RW,
616 &ntp_leap_second, sizeof(ntp_leap_second), "LU",
618 SYSCTL_INT(_kern_ntp, OID_AUTO, insert_leap_second, CTLFLAG_RW,
619 &ntp_leap_insert, 0, "insert or remove leap second");
620 SYSCTL_PROC(_kern_ntp, OID_AUTO, adjust,
621 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
622 sysctl_adjtime, "Q", "relative adjust for delta");
625 * Get value of an interval timer. The process virtual and
626 * profiling virtual time timers are kept in the p_stats area, since
627 * they can be swapped out. These are kept internally in the
628 * way they are specified externally: in time until they expire.
630 * The real time interval timer is kept in the process table slot
631 * for the process, and its value (it_value) is kept as an
632 * absolute time rather than as a delta, so that it is easy to keep
633 * periodic real-time signals from drifting.
635 * Virtual time timers are processed in the hardclock() routine of
636 * kern_clock.c. The real time timer is processed by a timeout
637 * routine, called from the softclock() routine. Since a callout
638 * may be delayed in real time due to interrupt processing in the system,
639 * it is possible for the real time timeout routine (realitexpire, given below),
640 * to be delayed in real time past when it is supposed to occur. It
641 * does not suffice, therefore, to reload the real timer .it_value from the
642 * real time timers .it_interval. Rather, we compute the next time in
643 * absolute time the timer should go off.
647 sys_getitimer(struct getitimer_args *uap)
649 struct proc *p = curproc;
651 struct itimerval aitv;
653 if (uap->which > ITIMER_PROF)
656 if (uap->which == ITIMER_REAL) {
658 * Convert from absolute to relative time in .it_value
659 * part of real time timer. If time for real time timer
660 * has passed return 0, else return difference between
661 * current time and time for the timer to go off.
663 aitv = p->p_realtimer;
664 if (timevalisset(&aitv.it_value)) {
665 getmicrouptime(&ctv);
666 if (timevalcmp(&aitv.it_value, &ctv, <))
667 timevalclear(&aitv.it_value);
669 timevalsub(&aitv.it_value, &ctv);
672 aitv = p->p_timer[uap->which];
675 return (copyout((caddr_t)&aitv, (caddr_t)uap->itv,
676 sizeof (struct itimerval)));
681 sys_setitimer(struct setitimer_args *uap)
683 struct itimerval aitv;
685 struct itimerval *itvp;
686 struct proc *p = curproc;
689 if (uap->which > ITIMER_PROF)
692 if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv,
693 sizeof(struct itimerval))))
695 if ((uap->itv = uap->oitv) &&
696 (error = sys_getitimer((struct getitimer_args *)uap)))
700 if (itimerfix(&aitv.it_value))
702 if (!timevalisset(&aitv.it_value))
703 timevalclear(&aitv.it_interval);
704 else if (itimerfix(&aitv.it_interval))
707 if (uap->which == ITIMER_REAL) {
708 if (timevalisset(&p->p_realtimer.it_value))
709 callout_stop(&p->p_ithandle);
710 if (timevalisset(&aitv.it_value))
711 callout_reset(&p->p_ithandle,
712 tvtohz_high(&aitv.it_value), realitexpire, p);
713 getmicrouptime(&ctv);
714 timevaladd(&aitv.it_value, &ctv);
715 p->p_realtimer = aitv;
717 p->p_timer[uap->which] = aitv;
724 * Real interval timer expired:
725 * send process whose timer expired an alarm signal.
726 * If time is not set up to reload, then just return.
727 * Else compute next time timer should go off which is > current time.
728 * This is where delay in processing this timeout causes multiple
729 * SIGALRM calls to be compressed into one.
730 * tvtohz_high() always adds 1 to allow for the time until the next clock
731 * interrupt being strictly less than 1 clock tick, but we don't want
732 * that here since we want to appear to be in sync with the clock
733 * interrupt even when we're delayed.
736 realitexpire(void *arg)
739 struct timeval ctv, ntv;
741 p = (struct proc *)arg;
743 if (!timevalisset(&p->p_realtimer.it_interval)) {
744 timevalclear(&p->p_realtimer.it_value);
749 timevaladd(&p->p_realtimer.it_value,
750 &p->p_realtimer.it_interval);
751 getmicrouptime(&ctv);
752 if (timevalcmp(&p->p_realtimer.it_value, &ctv, >)) {
753 ntv = p->p_realtimer.it_value;
754 timevalsub(&ntv, &ctv);
755 callout_reset(&p->p_ithandle, tvtohz_low(&ntv),
765 * Check that a proposed value to load into the .it_value or
766 * .it_interval part of an interval timer is acceptable, and
767 * fix it to have at least minimal value (i.e. if it is less
768 * than the resolution of the clock, round it up.)
771 itimerfix(struct timeval *tv)
774 if (tv->tv_sec < 0 || tv->tv_sec > 100000000 ||
775 tv->tv_usec < 0 || tv->tv_usec >= 1000000)
777 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
783 * Decrement an interval timer by a specified number
784 * of microseconds, which must be less than a second,
785 * i.e. < 1000000. If the timer expires, then reload
786 * it. In this case, carry over (usec - old value) to
787 * reduce the value reloaded into the timer so that
788 * the timer does not drift. This routine assumes
789 * that it is called in a context where the timers
790 * on which it is operating cannot change in value.
793 itimerdecr(struct itimerval *itp, int usec)
796 if (itp->it_value.tv_usec < usec) {
797 if (itp->it_value.tv_sec == 0) {
798 /* expired, and already in next interval */
799 usec -= itp->it_value.tv_usec;
802 itp->it_value.tv_usec += 1000000;
803 itp->it_value.tv_sec--;
805 itp->it_value.tv_usec -= usec;
807 if (timevalisset(&itp->it_value))
809 /* expired, exactly at end of interval */
811 if (timevalisset(&itp->it_interval)) {
812 itp->it_value = itp->it_interval;
813 itp->it_value.tv_usec -= usec;
814 if (itp->it_value.tv_usec < 0) {
815 itp->it_value.tv_usec += 1000000;
816 itp->it_value.tv_sec--;
819 itp->it_value.tv_usec = 0; /* sec is already 0 */
824 * Add and subtract routines for timevals.
825 * N.B.: subtract routine doesn't deal with
826 * results which are before the beginning,
827 * it just gets very confused in this case.
831 timevaladd(struct timeval *t1, const struct timeval *t2)
834 t1->tv_sec += t2->tv_sec;
835 t1->tv_usec += t2->tv_usec;
840 timevalsub(struct timeval *t1, const struct timeval *t2)
843 t1->tv_sec -= t2->tv_sec;
844 t1->tv_usec -= t2->tv_usec;
849 timevalfix(struct timeval *t1)
852 if (t1->tv_usec < 0) {
854 t1->tv_usec += 1000000;
856 if (t1->tv_usec >= 1000000) {
858 t1->tv_usec -= 1000000;
863 * ratecheck(): simple time-based rate-limit checking.
866 ratecheck(struct timeval *lasttime, const struct timeval *mininterval)
868 struct timeval tv, delta;
871 getmicrouptime(&tv); /* NB: 10ms precision */
873 timevalsub(&delta, lasttime);
876 * check for 0,0 is so that the message will be seen at least once,
877 * even if interval is huge.
879 if (timevalcmp(&delta, mininterval, >=) ||
880 (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
889 * ppsratecheck(): packets (or events) per second limitation.
891 * Return 0 if the limit is to be enforced (e.g. the caller
892 * should drop a packet because of the rate limitation).
894 * maxpps of 0 always causes zero to be returned. maxpps of -1
895 * always causes 1 to be returned; this effectively defeats rate
898 * Note that we maintain the struct timeval for compatibility
899 * with other bsd systems. We reuse the storage and just monitor
900 * clock ticks for minimal overhead.
903 ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
908 * Reset the last time and counter if this is the first call
909 * or more than a second has passed since the last update of
913 if (lasttime->tv_sec == 0 || (u_int)(now - lasttime->tv_sec) >= hz) {
914 lasttime->tv_sec = now;
916 return (maxpps != 0);
918 (*curpps)++; /* NB: ignore potential overflow */
919 return (maxpps < 0 || *curpps < maxpps);