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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 1.33 2006/03/27 16:18:34 dillon 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>
50 #include <sys/vnode.h>
51 #include <sys/sysctl.h>
53 #include <vm/vm_extern.h>
54 #include <sys/msgport2.h>
55 #include <sys/thread2.h>
60 * Time of day and interval timer support.
62 * These routines provide the kernel entry points to get and set
63 * the time-of-day and per-process interval timers. Subroutines
64 * here provide support for adding and subtracting timeval structures
65 * and decrementing interval timers, optionally reloading the interval
66 * timers when they expire.
69 static int nanosleep1 (struct timespec *rqt,
70 struct timespec *rmt);
71 static int settime (struct timeval *);
72 static void timevalfix (struct timeval *);
74 static int sleep_hard_us = 100;
75 SYSCTL_INT(_kern, OID_AUTO, sleep_hard_us, CTLFLAG_RW, &sleep_hard_us, 0, "")
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 printf("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 printf("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));
145 clock_gettime(struct clock_gettime_args *uap)
149 switch(uap->clock_id) {
152 return (copyout(&ats, uap->tp, sizeof(ats)));
153 case CLOCK_MONOTONIC:
155 return (copyout(&ats, uap->tp, sizeof(ats)));
163 clock_settime(struct clock_settime_args *uap)
165 struct thread *td = curthread;
170 if ((error = suser(td)) != 0)
172 switch(uap->clock_id) {
174 if ((error = copyin(uap->tp, &ats, sizeof(ats))) != 0)
176 if (ats.tv_nsec < 0 || ats.tv_nsec >= 1000000000)
178 /* XXX Don't convert nsec->usec and back */
179 TIMESPEC_TO_TIMEVAL(&atv, &ats);
180 error = settime(&atv);
188 clock_getres(struct clock_getres_args *uap)
192 switch(uap->clock_id) {
194 case CLOCK_MONOTONIC:
196 * Round up the result of the division cheaply
197 * by adding 1. Rounding up is especially important
198 * if rounding down would give 0. Perfect rounding
202 ts.tv_nsec = 1000000000 / sys_cputimer->freq + 1;
203 return(copyout(&ts, uap->tp, sizeof(ts)));
212 * This is a general helper function for nanosleep() (aka sleep() aka
215 * If there is less then one tick's worth of time left and
216 * we haven't done a yield, or the remaining microseconds is
217 * ridiculously low, do a yield. This avoids having
218 * to deal with systimer overheads when the system is under
219 * heavy loads. If we have done a yield already then use
220 * a systimer and an uninterruptable thread wait.
222 * If there is more then a tick's worth of time left,
223 * calculate the baseline ticks and use an interruptable
224 * tsleep, then handle the fine-grained delay on the next
225 * loop. This usually results in two sleeps occuring, a long one
229 ns1_systimer(systimer_t info)
231 lwkt_schedule(info->data);
235 nanosleep1(struct timespec *rqt, struct timespec *rmt)
238 struct timespec ts, ts2, ts3;
243 if (rqt->tv_nsec < 0 || rqt->tv_nsec >= 1000000000)
245 if (rqt->tv_sec < 0 || (rqt->tv_sec == 0 && rqt->tv_nsec == 0))
248 timespecadd(&ts, rqt); /* ts = target timestamp compare */
249 TIMESPEC_TO_TIMEVAL(&tv, rqt); /* tv = sleep interval */
254 struct systimer info;
256 ticks = tv.tv_usec / tick; /* approximate */
258 if (tv.tv_sec == 0 && ticks == 0) {
259 thread_t td = curthread;
260 if (tried_yield || tv.tv_usec < sleep_hard_us) {
264 crit_enter_quick(td);
265 systimer_init_oneshot(&info, ns1_systimer,
267 lwkt_deschedule_self(td);
270 systimer_del(&info); /* make sure it's gone */
272 error = iscaught(td->td_proc);
273 } else if (tv.tv_sec == 0) {
274 error = tsleep(&nanowait, PCATCH, "nanslp", ticks);
276 ticks = tvtohz_low(&tv); /* also handles overflow */
277 error = tsleep(&nanowait, PCATCH, "nanslp", ticks);
280 if (error && error != EWOULDBLOCK) {
281 if (error == ERESTART)
284 timespecsub(&ts, &ts2);
291 if (timespeccmp(&ts2, &ts, >=))
294 timespecsub(&ts3, &ts2);
295 TIMESPEC_TO_TIMEVAL(&tv, &ts3);
299 static void nanosleep_done(void *arg);
300 static void nanosleep_copyout(union sysunion *sysun);
304 nanosleep(struct nanosleep_args *uap)
307 struct sysmsg_sleep *smsleep = &uap->sysmsg.sm.sleep;
309 error = copyin(uap->rqtp, &smsleep->rqt, sizeof(smsleep->rqt));
313 * YYY clean this up to always use the callout, note that an abort
314 * implementation should record the residual in the async case.
316 if (uap->sysmsg.lmsg.ms_flags & MSGF_ASYNC) {
319 ticks = (quad_t)smsleep->rqt.tv_nsec * hz / 1000000000LL;
320 if (smsleep->rqt.tv_sec)
321 ticks += (quad_t)smsleep->rqt.tv_sec * hz;
328 uap->sysmsg.copyout = nanosleep_copyout;
329 uap->sysmsg.lmsg.ms_flags &= ~MSGF_DONE;
330 callout_init(&smsleep->timer);
331 callout_reset(&smsleep->timer, ticks, nanosleep_done, uap);
336 * Old synchronous sleep code, copyout the residual if
337 * nanosleep was interrupted.
339 error = nanosleep1(&smsleep->rqt, &smsleep->rmt);
340 if (error && uap->rmtp)
341 error = copyout(&smsleep->rmt, uap->rmtp, sizeof(smsleep->rmt));
347 * Asynch completion for the nanosleep() syscall. This function may be
348 * called from any context and cannot legally access the originating
349 * thread, proc, or its user space.
351 * YYY change the callout interface API so we can simply assign the replymsg
352 * function to it directly.
355 nanosleep_done(void *arg)
357 struct nanosleep_args *uap = arg;
358 lwkt_msg_t msg = &uap->sysmsg.lmsg;
360 lwkt_replymsg(msg, 0);
364 * Asynch return for the nanosleep() syscall, called in the context of the
365 * originating thread when it pulls the message off the reply port. This
366 * function is responsible for any copyouts to userland. Kernel threads
367 * which do their own internal system calls will not usually call the return
371 nanosleep_copyout(union sysunion *sysun)
373 struct nanosleep_args *uap = &sysun->nanosleep;
374 struct sysmsg_sleep *smsleep = &uap->sysmsg.sm.sleep;
376 if (sysun->lmsg.ms_error && uap->rmtp) {
377 sysun->lmsg.ms_error =
378 copyout(&smsleep->rmt, uap->rmtp, sizeof(smsleep->rmt));
384 gettimeofday(struct gettimeofday_args *uap)
391 if ((error = copyout((caddr_t)&atv, (caddr_t)uap->tp,
396 error = copyout((caddr_t)&tz, (caddr_t)uap->tzp,
403 settimeofday(struct settimeofday_args *uap)
405 struct thread *td = curthread;
410 if ((error = suser(td)))
412 /* Verify all parameters before changing time. */
414 if ((error = copyin((caddr_t)uap->tv, (caddr_t)&atv,
417 if (atv.tv_usec < 0 || atv.tv_usec >= 1000000)
421 (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz, sizeof(atz))))
423 if (uap->tv && (error = settime(&atv)))
431 kern_adjtime_common(void)
433 if ((ntp_delta >= 0 && ntp_delta < ntp_default_tick_delta) ||
434 (ntp_delta < 0 && ntp_delta > -ntp_default_tick_delta))
435 ntp_tick_delta = ntp_delta;
436 else if (ntp_delta > ntp_big_delta)
437 ntp_tick_delta = 10 * ntp_default_tick_delta;
438 else if (ntp_delta < -ntp_big_delta)
439 ntp_tick_delta = -10 * ntp_default_tick_delta;
440 else if (ntp_delta > 0)
441 ntp_tick_delta = ntp_default_tick_delta;
443 ntp_tick_delta = -ntp_default_tick_delta;
447 kern_adjtime(int64_t delta, int64_t *odelta)
451 if ((origcpu = mycpu->gd_cpuid) != 0)
452 lwkt_setcpu_self(globaldata_find(0));
457 kern_adjtime_common();
461 lwkt_setcpu_self(globaldata_find(origcpu));
465 kern_get_ntp_delta(int64_t *delta)
469 if ((origcpu = mycpu->gd_cpuid) != 0)
470 lwkt_setcpu_self(globaldata_find(0));
477 lwkt_setcpu_self(globaldata_find(origcpu));
481 kern_reladjtime(int64_t delta)
485 if ((origcpu = mycpu->gd_cpuid) != 0)
486 lwkt_setcpu_self(globaldata_find(0));
490 kern_adjtime_common();
494 lwkt_setcpu_self(globaldata_find(origcpu));
498 kern_adjfreq(int64_t rate)
502 if ((origcpu = mycpu->gd_cpuid) != 0)
503 lwkt_setcpu_self(globaldata_find(0));
506 ntp_tick_permanent = rate;
510 lwkt_setcpu_self(globaldata_find(origcpu));
515 adjtime(struct adjtime_args *uap)
517 struct thread *td = curthread;
519 int64_t ndelta, odelta;
522 if ((error = suser(td)))
525 copyin((caddr_t)uap->delta, (caddr_t)&atv, sizeof(struct timeval))))
529 * Compute the total correction and the rate at which to apply it.
530 * Round the adjustment down to a whole multiple of the per-tick
531 * delta, so that after some number of incremental changes in
532 * hardclock(), tickdelta will become zero, lest the correction
533 * overshoot and start taking us away from the desired final time.
535 ndelta = (int64_t)atv.tv_sec * 1000000000 + atv.tv_usec * 1000;
536 kern_adjtime(ndelta, &odelta);
539 atv.tv_sec = odelta / 1000000000;
540 atv.tv_usec = odelta % 1000000000 / 1000;
541 (void) copyout((caddr_t)&atv, (caddr_t)uap->olddelta,
542 sizeof(struct timeval));
548 sysctl_adjtime(SYSCTL_HANDLER_ARGS)
553 if (req->newptr != NULL) {
554 if (suser(curthread))
556 error = SYSCTL_IN(req, &delta, sizeof(delta));
559 kern_reladjtime(delta);
563 kern_get_ntp_delta(&delta);
564 error = SYSCTL_OUT(req, &delta, sizeof(delta));
569 * delta is in nanoseconds.
572 sysctl_delta(SYSCTL_HANDLER_ARGS)
574 int64_t delta, old_delta;
577 if (req->newptr != NULL) {
578 if (suser(curthread))
580 error = SYSCTL_IN(req, &delta, sizeof(delta));
583 kern_adjtime(delta, &old_delta);
586 if (req->oldptr != NULL)
587 kern_get_ntp_delta(&old_delta);
588 error = SYSCTL_OUT(req, &old_delta, sizeof(old_delta));
593 * frequency is in nanoseconds per second shifted left 32.
594 * kern_adjfreq() needs it in nanoseconds per tick shifted left 32.
597 sysctl_adjfreq(SYSCTL_HANDLER_ARGS)
602 if (req->newptr != NULL) {
603 if (suser(curthread))
605 error = SYSCTL_IN(req, &freqdelta, sizeof(freqdelta));
610 kern_adjfreq(freqdelta);
613 if (req->oldptr != NULL)
614 freqdelta = ntp_tick_permanent * hz;
615 error = SYSCTL_OUT(req, &freqdelta, sizeof(freqdelta));
622 SYSCTL_NODE(_kern, OID_AUTO, ntp, CTLFLAG_RW, 0, "NTP related controls");
623 SYSCTL_PROC(_kern_ntp, OID_AUTO, permanent,
624 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
625 sysctl_adjfreq, "Q", "permanent correction per second");
626 SYSCTL_PROC(_kern_ntp, OID_AUTO, delta,
627 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
628 sysctl_delta, "Q", "one-time delta");
629 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, big_delta, CTLFLAG_RD,
630 &ntp_big_delta, sizeof(ntp_big_delta), "Q",
631 "threshold for fast adjustment");
632 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, tick_delta, CTLFLAG_RD,
633 &ntp_tick_delta, sizeof(ntp_tick_delta), "LU",
634 "per-tick adjustment");
635 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, default_tick_delta, CTLFLAG_RD,
636 &ntp_default_tick_delta, sizeof(ntp_default_tick_delta), "LU",
637 "default per-tick adjustment");
638 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, next_leap_second, CTLFLAG_RW,
639 &ntp_leap_second, sizeof(ntp_leap_second), "LU",
641 SYSCTL_INT(_kern_ntp, OID_AUTO, insert_leap_second, CTLFLAG_RW,
642 &ntp_leap_insert, 0, "insert or remove leap second");
643 SYSCTL_PROC(_kern_ntp, OID_AUTO, adjust,
644 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
645 sysctl_adjtime, "Q", "relative adjust for delta");
648 * Get value of an interval timer. The process virtual and
649 * profiling virtual time timers are kept in the p_stats area, since
650 * they can be swapped out. These are kept internally in the
651 * way they are specified externally: in time until they expire.
653 * The real time interval timer is kept in the process table slot
654 * for the process, and its value (it_value) is kept as an
655 * absolute time rather than as a delta, so that it is easy to keep
656 * periodic real-time signals from drifting.
658 * Virtual time timers are processed in the hardclock() routine of
659 * kern_clock.c. The real time timer is processed by a timeout
660 * routine, called from the softclock() routine. Since a callout
661 * may be delayed in real time due to interrupt processing in the system,
662 * it is possible for the real time timeout routine (realitexpire, given below),
663 * to be delayed in real time past when it is supposed to occur. It
664 * does not suffice, therefore, to reload the real timer .it_value from the
665 * real time timers .it_interval. Rather, we compute the next time in
666 * absolute time the timer should go off.
670 getitimer(struct getitimer_args *uap)
672 struct proc *p = curproc;
674 struct itimerval aitv;
676 if (uap->which > ITIMER_PROF)
679 if (uap->which == ITIMER_REAL) {
681 * Convert from absolute to relative time in .it_value
682 * part of real time timer. If time for real time timer
683 * has passed return 0, else return difference between
684 * current time and time for the timer to go off.
686 aitv = p->p_realtimer;
687 if (timevalisset(&aitv.it_value)) {
688 getmicrouptime(&ctv);
689 if (timevalcmp(&aitv.it_value, &ctv, <))
690 timevalclear(&aitv.it_value);
692 timevalsub(&aitv.it_value, &ctv);
695 aitv = p->p_timer[uap->which];
698 return (copyout((caddr_t)&aitv, (caddr_t)uap->itv,
699 sizeof (struct itimerval)));
704 setitimer(struct setitimer_args *uap)
706 struct itimerval aitv;
708 struct itimerval *itvp;
709 struct proc *p = curproc;
712 if (uap->which > ITIMER_PROF)
715 if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv,
716 sizeof(struct itimerval))))
718 if ((uap->itv = uap->oitv) &&
719 (error = getitimer((struct getitimer_args *)uap)))
723 if (itimerfix(&aitv.it_value))
725 if (!timevalisset(&aitv.it_value))
726 timevalclear(&aitv.it_interval);
727 else if (itimerfix(&aitv.it_interval))
730 if (uap->which == ITIMER_REAL) {
731 if (timevalisset(&p->p_realtimer.it_value))
732 callout_stop(&p->p_ithandle);
733 if (timevalisset(&aitv.it_value))
734 callout_reset(&p->p_ithandle,
735 tvtohz_high(&aitv.it_value), realitexpire, p);
736 getmicrouptime(&ctv);
737 timevaladd(&aitv.it_value, &ctv);
738 p->p_realtimer = aitv;
740 p->p_timer[uap->which] = aitv;
747 * Real interval timer expired:
748 * send process whose timer expired an alarm signal.
749 * If time is not set up to reload, then just return.
750 * Else compute next time timer should go off which is > current time.
751 * This is where delay in processing this timeout causes multiple
752 * SIGALRM calls to be compressed into one.
753 * tvtohz_high() always adds 1 to allow for the time until the next clock
754 * interrupt being strictly less than 1 clock tick, but we don't want
755 * that here since we want to appear to be in sync with the clock
756 * interrupt even when we're delayed.
763 struct timeval ctv, ntv;
765 p = (struct proc *)arg;
767 if (!timevalisset(&p->p_realtimer.it_interval)) {
768 timevalclear(&p->p_realtimer.it_value);
773 timevaladd(&p->p_realtimer.it_value,
774 &p->p_realtimer.it_interval);
775 getmicrouptime(&ctv);
776 if (timevalcmp(&p->p_realtimer.it_value, &ctv, >)) {
777 ntv = p->p_realtimer.it_value;
778 timevalsub(&ntv, &ctv);
779 callout_reset(&p->p_ithandle, tvtohz_low(&ntv),
789 * Check that a proposed value to load into the .it_value or
790 * .it_interval part of an interval timer is acceptable, and
791 * fix it to have at least minimal value (i.e. if it is less
792 * than the resolution of the clock, round it up.)
799 if (tv->tv_sec < 0 || tv->tv_sec > 100000000 ||
800 tv->tv_usec < 0 || tv->tv_usec >= 1000000)
802 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
808 * Decrement an interval timer by a specified number
809 * of microseconds, which must be less than a second,
810 * i.e. < 1000000. If the timer expires, then reload
811 * it. In this case, carry over (usec - old value) to
812 * reduce the value reloaded into the timer so that
813 * the timer does not drift. This routine assumes
814 * that it is called in a context where the timers
815 * on which it is operating cannot change in value.
818 itimerdecr(itp, usec)
819 struct itimerval *itp;
823 if (itp->it_value.tv_usec < usec) {
824 if (itp->it_value.tv_sec == 0) {
825 /* expired, and already in next interval */
826 usec -= itp->it_value.tv_usec;
829 itp->it_value.tv_usec += 1000000;
830 itp->it_value.tv_sec--;
832 itp->it_value.tv_usec -= usec;
834 if (timevalisset(&itp->it_value))
836 /* expired, exactly at end of interval */
838 if (timevalisset(&itp->it_interval)) {
839 itp->it_value = itp->it_interval;
840 itp->it_value.tv_usec -= usec;
841 if (itp->it_value.tv_usec < 0) {
842 itp->it_value.tv_usec += 1000000;
843 itp->it_value.tv_sec--;
846 itp->it_value.tv_usec = 0; /* sec is already 0 */
851 * Add and subtract routines for timevals.
852 * N.B.: subtract routine doesn't deal with
853 * results which are before the beginning,
854 * it just gets very confused in this case.
859 struct timeval *t1, *t2;
862 t1->tv_sec += t2->tv_sec;
863 t1->tv_usec += t2->tv_usec;
869 struct timeval *t1, *t2;
872 t1->tv_sec -= t2->tv_sec;
873 t1->tv_usec -= t2->tv_usec;
882 if (t1->tv_usec < 0) {
884 t1->tv_usec += 1000000;
886 if (t1->tv_usec >= 1000000) {
888 t1->tv_usec -= 1000000;
893 * ratecheck(): simple time-based rate-limit checking.
896 ratecheck(struct timeval *lasttime, const struct timeval *mininterval)
898 struct timeval tv, delta;
901 getmicrouptime(&tv); /* NB: 10ms precision */
903 timevalsub(&delta, lasttime);
906 * check for 0,0 is so that the message will be seen at least once,
907 * even if interval is huge.
909 if (timevalcmp(&delta, mininterval, >=) ||
910 (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
919 * ppsratecheck(): packets (or events) per second limitation.
921 * Return 0 if the limit is to be enforced (e.g. the caller
922 * should drop a packet because of the rate limitation).
924 * maxpps of 0 always causes zero to be returned. maxpps of -1
925 * always causes 1 to be returned; this effectively defeats rate
928 * Note that we maintain the struct timeval for compatibility
929 * with other bsd systems. We reuse the storage and just monitor
930 * clock ticks for minimal overhead.
933 ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
938 * Reset the last time and counter if this is the first call
939 * or more than a second has passed since the last update of
943 if (lasttime->tv_sec == 0 || (u_int)(now - lasttime->tv_sec) >= hz) {
944 lasttime->tv_sec = now;
946 return (maxpps != 0);
948 (*curpps)++; /* NB: ignore potential overflow */
949 return (maxpps < 0 || *curpps < maxpps);