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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 1.6 2003/07/24 01:41:25 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>
49 #include <sys/vnode.h>
51 #include <vm/vm_extern.h>
56 * Time of day and interval timer support.
58 * These routines provide the kernel entry points to get and set
59 * the time-of-day and per-process interval timers. Subroutines
60 * here provide support for adding and subtracting timeval structures
61 * and decrementing interval timers, optionally reloading the interval
62 * timers when they expire.
65 static int nanosleep1 __P((struct timespec *rqt,
66 struct timespec *rmt));
67 static int settime __P((struct timeval *));
68 static void timevalfix __P((struct timeval *));
69 static void no_lease_updatetime __P((int));
72 no_lease_updatetime(deltat)
77 void (*lease_updatetime) __P((int)) = no_lease_updatetime;
83 struct timeval delta, tv1, tv2;
84 static struct timeval maxtime, laststep;
91 timevalsub(&delta, &tv1);
94 * If the system is secure, we do not allow the time to be
95 * set to a value earlier than 1 second less than the highest
96 * time we have yet seen. The worst a miscreant can do in
97 * this circumstance is "freeze" time. He couldn't go
100 * We similarly do not allow the clock to be stepped more
101 * than one second, nor more than once per second. This allows
102 * a miscreant to make the clock march double-time, but no worse.
104 if (securelevel > 1) {
105 if (delta.tv_sec < 0 || delta.tv_usec < 0) {
107 * Update maxtime to latest time we've seen.
109 if (tv1.tv_sec > maxtime.tv_sec)
112 timevalsub(&tv2, &maxtime);
113 if (tv2.tv_sec < -1) {
114 tv->tv_sec = maxtime.tv_sec - 1;
115 printf("Time adjustment clamped to -1 second\n");
118 if (tv1.tv_sec == laststep.tv_sec) {
122 if (delta.tv_sec > 1) {
123 tv->tv_sec = tv1.tv_sec + 1;
124 printf("Time adjustment clamped to +1 second\n");
130 ts.tv_sec = tv->tv_sec;
131 ts.tv_nsec = tv->tv_usec * 1000;
132 set_timecounter(&ts);
133 (void) splsoftclock();
134 lease_updatetime(delta.tv_sec);
142 clock_gettime(struct clock_gettime_args *uap)
146 if (SCARG(uap, clock_id) != CLOCK_REALTIME)
149 return (copyout(&ats, SCARG(uap, tp), sizeof(ats)));
154 clock_settime(struct clock_settime_args *uap)
156 struct thread *td = curthread;
161 if ((error = suser(td)) != 0)
163 if (SCARG(uap, clock_id) != CLOCK_REALTIME)
165 if ((error = copyin(SCARG(uap, tp), &ats, sizeof(ats))) != 0)
167 if (ats.tv_nsec < 0 || ats.tv_nsec >= 1000000000)
169 /* XXX Don't convert nsec->usec and back */
170 TIMESPEC_TO_TIMEVAL(&atv, &ats);
171 if ((error = settime(&atv)))
177 clock_getres(struct clock_getres_args *uap)
182 if (SCARG(uap, clock_id) != CLOCK_REALTIME)
185 if (SCARG(uap, tp)) {
188 * Round up the result of the division cheaply by adding 1.
189 * Rounding up is especially important if rounding down
190 * would give 0. Perfect rounding is unimportant.
192 ts.tv_nsec = 1000000000 / timecounter->tc_frequency + 1;
193 error = copyout(&ts, SCARG(uap, tp), sizeof(ts));
201 nanosleep1(struct timespec *rqt, struct timespec *rmt)
203 struct timespec ts, ts2, ts3;
207 if (rqt->tv_nsec < 0 || rqt->tv_nsec >= 1000000000)
209 if (rqt->tv_sec < 0 || (rqt->tv_sec == 0 && rqt->tv_nsec == 0))
212 timespecadd(&ts, rqt);
213 TIMESPEC_TO_TIMEVAL(&tv, rqt);
215 error = tsleep(&nanowait, PCATCH, "nanslp",
218 if (error != EWOULDBLOCK) {
219 if (error == ERESTART)
222 timespecsub(&ts, &ts2);
229 if (timespeccmp(&ts2, &ts, >=))
232 timespecsub(&ts3, &ts2);
233 TIMESPEC_TO_TIMEVAL(&tv, &ts3);
239 nanosleep(struct nanosleep_args *uap)
241 struct timespec rmt, rqt;
244 error = copyin(SCARG(uap, rqtp), &rqt, sizeof(rqt));
247 if (SCARG(uap, rmtp))
248 if (!useracc((caddr_t)SCARG(uap, rmtp), sizeof(rmt),
251 error = nanosleep1(&rqt, &rmt);
252 if (error && SCARG(uap, rmtp)) {
253 error2 = copyout(&rmt, SCARG(uap, rmtp), sizeof(rmt));
254 if (error2) /* XXX shouldn't happen, did useracc() above */
262 gettimeofday(struct gettimeofday_args *uap)
269 if ((error = copyout((caddr_t)&atv, (caddr_t)uap->tp,
274 error = copyout((caddr_t)&tz, (caddr_t)uap->tzp,
281 settimeofday(struct settimeofday_args *uap)
283 struct thread *td = curthread;
288 if ((error = suser(td)))
290 /* Verify all parameters before changing time. */
292 if ((error = copyin((caddr_t)uap->tv, (caddr_t)&atv,
295 if (atv.tv_usec < 0 || atv.tv_usec >= 1000000)
299 (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz, sizeof(atz))))
301 if (uap->tv && (error = settime(&atv)))
308 int tickdelta; /* current clock skew, us. per tick */
309 long timedelta; /* unapplied time correction, us. */
310 static long bigadj = 1000000; /* use 10x skew above bigadj us. */
314 adjtime(struct adjtime_args *uap)
316 struct thread *td = curthread;
318 long ndelta, ntickdelta, odelta;
321 if ((error = suser(td)))
324 copyin((caddr_t)uap->delta, (caddr_t)&atv, sizeof(struct timeval))))
328 * Compute the total correction and the rate at which to apply it.
329 * Round the adjustment down to a whole multiple of the per-tick
330 * delta, so that after some number of incremental changes in
331 * hardclock(), tickdelta will become zero, lest the correction
332 * overshoot and start taking us away from the desired final time.
334 ndelta = atv.tv_sec * 1000000 + atv.tv_usec;
335 if (ndelta > bigadj || ndelta < -bigadj)
336 ntickdelta = 10 * tickadj;
338 ntickdelta = tickadj;
339 if (ndelta % ntickdelta)
340 ndelta = ndelta / ntickdelta * ntickdelta;
343 * To make hardclock()'s job easier, make the per-tick delta negative
344 * if we want time to run slower; then hardclock can simply compute
345 * tick + tickdelta, and subtract tickdelta from timedelta.
348 ntickdelta = -ntickdelta;
352 tickdelta = ntickdelta;
356 atv.tv_sec = odelta / 1000000;
357 atv.tv_usec = odelta % 1000000;
358 (void) copyout((caddr_t)&atv, (caddr_t)uap->olddelta,
359 sizeof(struct timeval));
365 * Get value of an interval timer. The process virtual and
366 * profiling virtual time timers are kept in the p_stats area, since
367 * they can be swapped out. These are kept internally in the
368 * way they are specified externally: in time until they expire.
370 * The real time interval timer is kept in the process table slot
371 * for the process, and its value (it_value) is kept as an
372 * absolute time rather than as a delta, so that it is easy to keep
373 * periodic real-time signals from drifting.
375 * Virtual time timers are processed in the hardclock() routine of
376 * kern_clock.c. The real time timer is processed by a timeout
377 * routine, called from the softclock() routine. Since a callout
378 * may be delayed in real time due to interrupt processing in the system,
379 * it is possible for the real time timeout routine (realitexpire, given below),
380 * to be delayed in real time past when it is supposed to occur. It
381 * does not suffice, therefore, to reload the real timer .it_value from the
382 * real time timers .it_interval. Rather, we compute the next time in
383 * absolute time the timer should go off.
387 getitimer(struct getitimer_args *uap)
389 struct proc *p = curproc;
391 struct itimerval aitv;
394 if (uap->which > ITIMER_PROF)
396 s = splclock(); /* XXX still needed ? */
397 if (uap->which == ITIMER_REAL) {
399 * Convert from absolute to relative time in .it_value
400 * part of real time timer. If time for real time timer
401 * has passed return 0, else return difference between
402 * current time and time for the timer to go off.
404 aitv = p->p_realtimer;
405 if (timevalisset(&aitv.it_value)) {
406 getmicrouptime(&ctv);
407 if (timevalcmp(&aitv.it_value, &ctv, <))
408 timevalclear(&aitv.it_value);
410 timevalsub(&aitv.it_value, &ctv);
413 aitv = p->p_stats->p_timer[uap->which];
415 return (copyout((caddr_t)&aitv, (caddr_t)uap->itv,
416 sizeof (struct itimerval)));
421 setitimer(struct setitimer_args *uap)
423 struct itimerval aitv;
425 struct itimerval *itvp;
426 struct proc *p = curproc;
429 if (uap->which > ITIMER_PROF)
432 if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv,
433 sizeof(struct itimerval))))
435 if ((uap->itv = uap->oitv) &&
436 (error = getitimer((struct getitimer_args *)uap)))
440 if (itimerfix(&aitv.it_value))
442 if (!timevalisset(&aitv.it_value))
443 timevalclear(&aitv.it_interval);
444 else if (itimerfix(&aitv.it_interval))
446 s = splclock(); /* XXX: still needed ? */
447 if (uap->which == ITIMER_REAL) {
448 if (timevalisset(&p->p_realtimer.it_value))
449 untimeout(realitexpire, (caddr_t)p, p->p_ithandle);
450 if (timevalisset(&aitv.it_value))
451 p->p_ithandle = timeout(realitexpire, (caddr_t)p,
452 tvtohz(&aitv.it_value));
453 getmicrouptime(&ctv);
454 timevaladd(&aitv.it_value, &ctv);
455 p->p_realtimer = aitv;
457 p->p_stats->p_timer[uap->which] = aitv;
463 * Real interval timer expired:
464 * send process whose timer expired an alarm signal.
465 * If time is not set up to reload, then just return.
466 * Else compute next time timer should go off which is > current time.
467 * This is where delay in processing this timeout causes multiple
468 * SIGALRM calls to be compressed into one.
469 * tvtohz() always adds 1 to allow for the time until the next clock
470 * interrupt being strictly less than 1 clock tick, but we don't want
471 * that here since we want to appear to be in sync with the clock
472 * interrupt even when we're delayed.
478 register struct proc *p;
479 struct timeval ctv, ntv;
482 p = (struct proc *)arg;
484 if (!timevalisset(&p->p_realtimer.it_interval)) {
485 timevalclear(&p->p_realtimer.it_value);
489 s = splclock(); /* XXX: still neeeded ? */
490 timevaladd(&p->p_realtimer.it_value,
491 &p->p_realtimer.it_interval);
492 getmicrouptime(&ctv);
493 if (timevalcmp(&p->p_realtimer.it_value, &ctv, >)) {
494 ntv = p->p_realtimer.it_value;
495 timevalsub(&ntv, &ctv);
496 p->p_ithandle = timeout(realitexpire, (caddr_t)p,
506 * Check that a proposed value to load into the .it_value or
507 * .it_interval part of an interval timer is acceptable, and
508 * fix it to have at least minimal value (i.e. if it is less
509 * than the resolution of the clock, round it up.)
516 if (tv->tv_sec < 0 || tv->tv_sec > 100000000 ||
517 tv->tv_usec < 0 || tv->tv_usec >= 1000000)
519 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
525 * Decrement an interval timer by a specified number
526 * of microseconds, which must be less than a second,
527 * i.e. < 1000000. If the timer expires, then reload
528 * it. In this case, carry over (usec - old value) to
529 * reduce the value reloaded into the timer so that
530 * the timer does not drift. This routine assumes
531 * that it is called in a context where the timers
532 * on which it is operating cannot change in value.
535 itimerdecr(itp, usec)
536 register struct itimerval *itp;
540 if (itp->it_value.tv_usec < usec) {
541 if (itp->it_value.tv_sec == 0) {
542 /* expired, and already in next interval */
543 usec -= itp->it_value.tv_usec;
546 itp->it_value.tv_usec += 1000000;
547 itp->it_value.tv_sec--;
549 itp->it_value.tv_usec -= usec;
551 if (timevalisset(&itp->it_value))
553 /* expired, exactly at end of interval */
555 if (timevalisset(&itp->it_interval)) {
556 itp->it_value = itp->it_interval;
557 itp->it_value.tv_usec -= usec;
558 if (itp->it_value.tv_usec < 0) {
559 itp->it_value.tv_usec += 1000000;
560 itp->it_value.tv_sec--;
563 itp->it_value.tv_usec = 0; /* sec is already 0 */
568 * Add and subtract routines for timevals.
569 * N.B.: subtract routine doesn't deal with
570 * results which are before the beginning,
571 * it just gets very confused in this case.
576 struct timeval *t1, *t2;
579 t1->tv_sec += t2->tv_sec;
580 t1->tv_usec += t2->tv_usec;
586 struct timeval *t1, *t2;
589 t1->tv_sec -= t2->tv_sec;
590 t1->tv_usec -= t2->tv_usec;
599 if (t1->tv_usec < 0) {
601 t1->tv_usec += 1000000;
603 if (t1->tv_usec >= 1000000) {
605 t1->tv_usec -= 1000000;