FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_time.c
1 /*
2 * Copyright (c) 1982, 1986, 1989, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * @(#)kern_time.c 8.1 (Berkeley) 6/10/93
34 * $FreeBSD: releng/5.1/sys/kern/kern_time.c 114980 2003-05-13 19:21:46Z jhb $
35 */
36
37 #include "opt_mac.h"
38
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/lock.h>
42 #include <sys/mutex.h>
43 #include <sys/sysproto.h>
44 #include <sys/resourcevar.h>
45 #include <sys/signalvar.h>
46 #include <sys/kernel.h>
47 #include <sys/mac.h>
48 #include <sys/sysent.h>
49 #include <sys/proc.h>
50 #include <sys/time.h>
51 #include <sys/timetc.h>
52 #include <sys/vnode.h>
53
54 #include <vm/vm.h>
55 #include <vm/vm_extern.h>
56
57 int tz_minuteswest;
58 int tz_dsttime;
59
60 /*
61 * Time of day and interval timer support.
62 *
63 * These routines provide the kernel entry points to get and set
64 * the time-of-day and per-process interval timers. Subroutines
65 * here provide support for adding and subtracting timeval structures
66 * and decrementing interval timers, optionally reloading the interval
67 * timers when they expire.
68 */
69
70 static int nanosleep1(struct thread *td, struct timespec *rqt,
71 struct timespec *rmt);
72 static int settime(struct thread *, struct timeval *);
73 static void timevalfix(struct timeval *);
74 static void no_lease_updatetime(int);
75
76 static void
77 no_lease_updatetime(deltat)
78 int deltat;
79 {
80 }
81
82 void (*lease_updatetime)(int) = no_lease_updatetime;
83
84 static int
85 settime(struct thread *td, struct timeval *tv)
86 {
87 struct timeval delta, tv1, tv2;
88 static struct timeval maxtime, laststep;
89 struct timespec ts;
90 int s;
91
92 s = splclock();
93 microtime(&tv1);
94 delta = *tv;
95 timevalsub(&delta, &tv1);
96
97 /*
98 * If the system is secure, we do not allow the time to be
99 * set to a value earlier than 1 second less than the highest
100 * time we have yet seen. The worst a miscreant can do in
101 * this circumstance is "freeze" time. He couldn't go
102 * back to the past.
103 *
104 * We similarly do not allow the clock to be stepped more
105 * than one second, nor more than once per second. This allows
106 * a miscreant to make the clock march double-time, but no worse.
107 */
108 if (securelevel_gt(td->td_ucred, 1) != 0) {
109 if (delta.tv_sec < 0 || delta.tv_usec < 0) {
110 /*
111 * Update maxtime to latest time we've seen.
112 */
113 if (tv1.tv_sec > maxtime.tv_sec)
114 maxtime = tv1;
115 tv2 = *tv;
116 timevalsub(&tv2, &maxtime);
117 if (tv2.tv_sec < -1) {
118 tv->tv_sec = maxtime.tv_sec - 1;
119 printf("Time adjustment clamped to -1 second\n");
120 }
121 } else {
122 if (tv1.tv_sec == laststep.tv_sec) {
123 splx(s);
124 return (EPERM);
125 }
126 if (delta.tv_sec > 1) {
127 tv->tv_sec = tv1.tv_sec + 1;
128 printf("Time adjustment clamped to +1 second\n");
129 }
130 laststep = *tv;
131 }
132 }
133
134 ts.tv_sec = tv->tv_sec;
135 ts.tv_nsec = tv->tv_usec * 1000;
136 mtx_lock(&Giant);
137 tc_setclock(&ts);
138 (void) splsoftclock();
139 lease_updatetime(delta.tv_sec);
140 splx(s);
141 resettodr();
142 mtx_unlock(&Giant);
143 return (0);
144 }
145
146 #ifndef _SYS_SYSPROTO_H_
147 struct clock_gettime_args {
148 clockid_t clock_id;
149 struct timespec *tp;
150 };
151 #endif
152
153 /*
154 * MPSAFE
155 */
156 /* ARGSUSED */
157 int
158 clock_gettime(struct thread *td, struct clock_gettime_args *uap)
159 {
160 struct timespec ats;
161
162 if (uap->clock_id == CLOCK_REALTIME)
163 nanotime(&ats);
164 else if (uap->clock_id == CLOCK_MONOTONIC)
165 nanouptime(&ats);
166 else
167 return (EINVAL);
168 return (copyout(&ats, uap->tp, sizeof(ats)));
169 }
170
171 #ifndef _SYS_SYSPROTO_H_
172 struct clock_settime_args {
173 clockid_t clock_id;
174 const struct timespec *tp;
175 };
176 #endif
177
178 /*
179 * MPSAFE
180 */
181 /* ARGSUSED */
182 int
183 clock_settime(struct thread *td, struct clock_settime_args *uap)
184 {
185 struct timeval atv;
186 struct timespec ats;
187 int error;
188
189 #ifdef MAC
190 error = mac_check_system_settime(td->td_ucred);
191 if (error)
192 return (error);
193 #endif
194 if ((error = suser(td)) != 0)
195 return (error);
196 if (uap->clock_id != CLOCK_REALTIME)
197 return (EINVAL);
198 if ((error = copyin(uap->tp, &ats, sizeof(ats))) != 0)
199 return (error);
200 if (ats.tv_nsec < 0 || ats.tv_nsec >= 1000000000)
201 return (EINVAL);
202 /* XXX Don't convert nsec->usec and back */
203 TIMESPEC_TO_TIMEVAL(&atv, &ats);
204 error = settime(td, &atv);
205 return (error);
206 }
207
208 #ifndef _SYS_SYSPROTO_H_
209 struct clock_getres_args {
210 clockid_t clock_id;
211 struct timespec *tp;
212 };
213 #endif
214
215 int
216 clock_getres(struct thread *td, struct clock_getres_args *uap)
217 {
218 struct timespec ts;
219 int error;
220
221 if (uap->clock_id != CLOCK_REALTIME)
222 return (EINVAL);
223 error = 0;
224 if (uap->tp) {
225 ts.tv_sec = 0;
226 /*
227 * Round up the result of the division cheaply by adding 1.
228 * Rounding up is especially important if rounding down
229 * would give 0. Perfect rounding is unimportant.
230 */
231 ts.tv_nsec = 1000000000 / tc_getfrequency() + 1;
232 error = copyout(&ts, uap->tp, sizeof(ts));
233 }
234 return (error);
235 }
236
237 static int nanowait;
238
239 static int
240 nanosleep1(struct thread *td, struct timespec *rqt, struct timespec *rmt)
241 {
242 struct timespec ts, ts2, ts3;
243 struct timeval tv;
244 int error;
245
246 if (rqt->tv_nsec < 0 || rqt->tv_nsec >= 1000000000)
247 return (EINVAL);
248 if (rqt->tv_sec < 0 || (rqt->tv_sec == 0 && rqt->tv_nsec == 0))
249 return (0);
250 getnanouptime(&ts);
251 timespecadd(&ts, rqt);
252 TIMESPEC_TO_TIMEVAL(&tv, rqt);
253 for (;;) {
254 error = tsleep(&nanowait, PWAIT | PCATCH, "nanslp",
255 tvtohz(&tv));
256 getnanouptime(&ts2);
257 if (error != EWOULDBLOCK) {
258 if (error == ERESTART)
259 error = EINTR;
260 if (rmt != NULL) {
261 timespecsub(&ts, &ts2);
262 if (ts.tv_sec < 0)
263 timespecclear(&ts);
264 *rmt = ts;
265 }
266 return (error);
267 }
268 if (timespeccmp(&ts2, &ts, >=))
269 return (0);
270 ts3 = ts;
271 timespecsub(&ts3, &ts2);
272 TIMESPEC_TO_TIMEVAL(&tv, &ts3);
273 }
274 }
275
276 #ifndef _SYS_SYSPROTO_H_
277 struct nanosleep_args {
278 struct timespec *rqtp;
279 struct timespec *rmtp;
280 };
281 #endif
282
283 /*
284 * MPSAFE
285 */
286 /* ARGSUSED */
287 int
288 nanosleep(struct thread *td, struct nanosleep_args *uap)
289 {
290 struct timespec rmt, rqt;
291 int error;
292
293 error = copyin(uap->rqtp, &rqt, sizeof(rqt));
294 if (error)
295 return (error);
296
297 if (uap->rmtp &&
298 !useracc((caddr_t)uap->rmtp, sizeof(rmt), VM_PROT_WRITE))
299 return (EFAULT);
300 error = nanosleep1(td, &rqt, &rmt);
301 if (error && uap->rmtp) {
302 int error2;
303
304 error2 = copyout(&rmt, uap->rmtp, sizeof(rmt));
305 if (error2)
306 error = error2;
307 }
308 return (error);
309 }
310
311 #ifndef _SYS_SYSPROTO_H_
312 struct gettimeofday_args {
313 struct timeval *tp;
314 struct timezone *tzp;
315 };
316 #endif
317 /*
318 * MPSAFE
319 */
320 /* ARGSUSED */
321 int
322 gettimeofday(struct thread *td, struct gettimeofday_args *uap)
323 {
324 struct timeval atv;
325 struct timezone rtz;
326 int error = 0;
327
328 if (uap->tp) {
329 microtime(&atv);
330 error = copyout(&atv, uap->tp, sizeof (atv));
331 }
332 if (error == 0 && uap->tzp != NULL) {
333 rtz.tz_minuteswest = tz_minuteswest;
334 rtz.tz_dsttime = tz_dsttime;
335 error = copyout(&rtz, uap->tzp, sizeof (rtz));
336 }
337 return (error);
338 }
339
340 #ifndef _SYS_SYSPROTO_H_
341 struct settimeofday_args {
342 struct timeval *tv;
343 struct timezone *tzp;
344 };
345 #endif
346 /*
347 * MPSAFE
348 */
349 /* ARGSUSED */
350 int
351 settimeofday(struct thread *td, struct settimeofday_args *uap)
352 {
353 struct timeval atv;
354 struct timezone atz;
355 int error = 0;
356
357 #ifdef MAC
358 error = mac_check_system_settime(td->td_ucred);
359 if (error)
360 return (error);
361 #endif
362 if ((error = suser(td)))
363 return (error);
364 /* Verify all parameters before changing time. */
365 if (uap->tv) {
366 if ((error = copyin(uap->tv, &atv, sizeof(atv))))
367 return (error);
368 if (atv.tv_usec < 0 || atv.tv_usec >= 1000000)
369 return (EINVAL);
370 }
371 if (uap->tzp &&
372 (error = copyin(uap->tzp, &atz, sizeof(atz))))
373 return (error);
374
375 if (uap->tv && (error = settime(td, &atv)))
376 return (error);
377 if (uap->tzp) {
378 tz_minuteswest = atz.tz_minuteswest;
379 tz_dsttime = atz.tz_dsttime;
380 }
381 return (error);
382 }
383 /*
384 * Get value of an interval timer. The process virtual and
385 * profiling virtual time timers are kept in the p_stats area, since
386 * they can be swapped out. These are kept internally in the
387 * way they are specified externally: in time until they expire.
388 *
389 * The real time interval timer is kept in the process table slot
390 * for the process, and its value (it_value) is kept as an
391 * absolute time rather than as a delta, so that it is easy to keep
392 * periodic real-time signals from drifting.
393 *
394 * Virtual time timers are processed in the hardclock() routine of
395 * kern_clock.c. The real time timer is processed by a timeout
396 * routine, called from the softclock() routine. Since a callout
397 * may be delayed in real time due to interrupt processing in the system,
398 * it is possible for the real time timeout routine (realitexpire, given below),
399 * to be delayed in real time past when it is supposed to occur. It
400 * does not suffice, therefore, to reload the real timer .it_value from the
401 * real time timers .it_interval. Rather, we compute the next time in
402 * absolute time the timer should go off.
403 */
404 #ifndef _SYS_SYSPROTO_H_
405 struct getitimer_args {
406 u_int which;
407 struct itimerval *itv;
408 };
409 #endif
410 /*
411 * MPSAFE
412 */
413 int
414 getitimer(struct thread *td, struct getitimer_args *uap)
415 {
416 struct proc *p = td->td_proc;
417 struct timeval ctv;
418 struct itimerval aitv;
419
420 if (uap->which > ITIMER_PROF)
421 return (EINVAL);
422
423 if (uap->which == ITIMER_REAL) {
424 /*
425 * Convert from absolute to relative time in .it_value
426 * part of real time timer. If time for real time timer
427 * has passed return 0, else return difference between
428 * current time and time for the timer to go off.
429 */
430 PROC_LOCK(p);
431 aitv = p->p_realtimer;
432 PROC_UNLOCK(p);
433 if (timevalisset(&aitv.it_value)) {
434 getmicrouptime(&ctv);
435 if (timevalcmp(&aitv.it_value, &ctv, <))
436 timevalclear(&aitv.it_value);
437 else
438 timevalsub(&aitv.it_value, &ctv);
439 }
440 } else {
441 mtx_lock_spin(&sched_lock);
442 aitv = p->p_stats->p_timer[uap->which];
443 mtx_unlock_spin(&sched_lock);
444 }
445 return (copyout(&aitv, uap->itv, sizeof (struct itimerval)));
446 }
447
448 #ifndef _SYS_SYSPROTO_H_
449 struct setitimer_args {
450 u_int which;
451 struct itimerval *itv, *oitv;
452 };
453 #endif
454 /*
455 * MPSAFE
456 */
457 int
458 setitimer(struct thread *td, struct setitimer_args *uap)
459 {
460 struct proc *p = td->td_proc;
461 struct itimerval aitv, oitv;
462 struct timeval ctv;
463 int error;
464
465 if (uap->itv == NULL) {
466 uap->itv = uap->oitv;
467 return (getitimer(td, (struct getitimer_args *)uap));
468 }
469
470 if (uap->which > ITIMER_PROF)
471 return (EINVAL);
472 if ((error = copyin(uap->itv, &aitv, sizeof(struct itimerval))))
473 return (error);
474 if (itimerfix(&aitv.it_value))
475 return (EINVAL);
476 if (!timevalisset(&aitv.it_value))
477 timevalclear(&aitv.it_interval);
478 else if (itimerfix(&aitv.it_interval))
479 return (EINVAL);
480
481 if (uap->which == ITIMER_REAL) {
482 PROC_LOCK(p);
483 if (timevalisset(&p->p_realtimer.it_value))
484 callout_stop(&p->p_itcallout);
485 getmicrouptime(&ctv);
486 if (timevalisset(&aitv.it_value)) {
487 callout_reset(&p->p_itcallout, tvtohz(&aitv.it_value),
488 realitexpire, p);
489 timevaladd(&aitv.it_value, &ctv);
490 }
491 oitv = p->p_realtimer;
492 p->p_realtimer = aitv;
493 PROC_UNLOCK(p);
494 if (timevalisset(&oitv.it_value)) {
495 if (timevalcmp(&oitv.it_value, &ctv, <))
496 timevalclear(&oitv.it_value);
497 else
498 timevalsub(&oitv.it_value, &ctv);
499 }
500 } else {
501 mtx_lock_spin(&sched_lock);
502 oitv = p->p_stats->p_timer[uap->which];
503 p->p_stats->p_timer[uap->which] = aitv;
504 mtx_unlock_spin(&sched_lock);
505 }
506 if (uap->oitv == NULL)
507 return (0);
508 return (copyout(&oitv, uap->oitv, sizeof(struct itimerval)));
509 }
510
511 /*
512 * Real interval timer expired:
513 * send process whose timer expired an alarm signal.
514 * If time is not set up to reload, then just return.
515 * Else compute next time timer should go off which is > current time.
516 * This is where delay in processing this timeout causes multiple
517 * SIGALRM calls to be compressed into one.
518 * tvtohz() always adds 1 to allow for the time until the next clock
519 * interrupt being strictly less than 1 clock tick, but we don't want
520 * that here since we want to appear to be in sync with the clock
521 * interrupt even when we're delayed.
522 */
523 void
524 realitexpire(void *arg)
525 {
526 struct proc *p;
527 struct timeval ctv, ntv;
528
529 p = (struct proc *)arg;
530 PROC_LOCK(p);
531 psignal(p, SIGALRM);
532 if (!timevalisset(&p->p_realtimer.it_interval)) {
533 timevalclear(&p->p_realtimer.it_value);
534 PROC_UNLOCK(p);
535 return;
536 }
537 for (;;) {
538 timevaladd(&p->p_realtimer.it_value,
539 &p->p_realtimer.it_interval);
540 getmicrouptime(&ctv);
541 if (timevalcmp(&p->p_realtimer.it_value, &ctv, >)) {
542 ntv = p->p_realtimer.it_value;
543 timevalsub(&ntv, &ctv);
544 callout_reset(&p->p_itcallout, tvtohz(&ntv) - 1,
545 realitexpire, p);
546 PROC_UNLOCK(p);
547 return;
548 }
549 }
550 /*NOTREACHED*/
551 }
552
553 /*
554 * Check that a proposed value to load into the .it_value or
555 * .it_interval part of an interval timer is acceptable, and
556 * fix it to have at least minimal value (i.e. if it is less
557 * than the resolution of the clock, round it up.)
558 */
559 int
560 itimerfix(struct timeval *tv)
561 {
562
563 if (tv->tv_sec < 0 || tv->tv_sec > 100000000 ||
564 tv->tv_usec < 0 || tv->tv_usec >= 1000000)
565 return (EINVAL);
566 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
567 tv->tv_usec = tick;
568 return (0);
569 }
570
571 /*
572 * Decrement an interval timer by a specified number
573 * of microseconds, which must be less than a second,
574 * i.e. < 1000000. If the timer expires, then reload
575 * it. In this case, carry over (usec - old value) to
576 * reduce the value reloaded into the timer so that
577 * the timer does not drift. This routine assumes
578 * that it is called in a context where the timers
579 * on which it is operating cannot change in value.
580 */
581 int
582 itimerdecr(struct itimerval *itp, int usec)
583 {
584
585 if (itp->it_value.tv_usec < usec) {
586 if (itp->it_value.tv_sec == 0) {
587 /* expired, and already in next interval */
588 usec -= itp->it_value.tv_usec;
589 goto expire;
590 }
591 itp->it_value.tv_usec += 1000000;
592 itp->it_value.tv_sec--;
593 }
594 itp->it_value.tv_usec -= usec;
595 usec = 0;
596 if (timevalisset(&itp->it_value))
597 return (1);
598 /* expired, exactly at end of interval */
599 expire:
600 if (timevalisset(&itp->it_interval)) {
601 itp->it_value = itp->it_interval;
602 itp->it_value.tv_usec -= usec;
603 if (itp->it_value.tv_usec < 0) {
604 itp->it_value.tv_usec += 1000000;
605 itp->it_value.tv_sec--;
606 }
607 } else
608 itp->it_value.tv_usec = 0; /* sec is already 0 */
609 return (0);
610 }
611
612 /*
613 * Add and subtract routines for timevals.
614 * N.B.: subtract routine doesn't deal with
615 * results which are before the beginning,
616 * it just gets very confused in this case.
617 * Caveat emptor.
618 */
619 void
620 timevaladd(struct timeval *t1, struct timeval *t2)
621 {
622
623 t1->tv_sec += t2->tv_sec;
624 t1->tv_usec += t2->tv_usec;
625 timevalfix(t1);
626 }
627
628 void
629 timevalsub(struct timeval *t1, struct timeval *t2)
630 {
631
632 t1->tv_sec -= t2->tv_sec;
633 t1->tv_usec -= t2->tv_usec;
634 timevalfix(t1);
635 }
636
637 static void
638 timevalfix(struct timeval *t1)
639 {
640
641 if (t1->tv_usec < 0) {
642 t1->tv_sec--;
643 t1->tv_usec += 1000000;
644 }
645 if (t1->tv_usec >= 1000000) {
646 t1->tv_sec++;
647 t1->tv_usec -= 1000000;
648 }
649 }
650
651 /*
652 * ratecheck(): simple time-based rate-limit checking.
653 */
654 int
655 ratecheck(struct timeval *lasttime, const struct timeval *mininterval)
656 {
657 struct timeval tv, delta;
658 int rv = 0;
659
660 getmicrouptime(&tv); /* NB: 10ms precision */
661 delta = tv;
662 timevalsub(&delta, lasttime);
663
664 /*
665 * check for 0,0 is so that the message will be seen at least once,
666 * even if interval is huge.
667 */
668 if (timevalcmp(&delta, mininterval, >=) ||
669 (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
670 *lasttime = tv;
671 rv = 1;
672 }
673
674 return (rv);
675 }
676
677 /*
678 * ppsratecheck(): packets (or events) per second limitation.
679 *
680 * Return 0 if the limit is to be enforced (e.g. the caller
681 * should drop a packet because of the rate limitation).
682 *
683 * maxpps of 0 always causes zero to be returned. maxpps of -1
684 * always causes 1 to be returned; this effectively defeats rate
685 * limiting.
686 *
687 * Note that we maintain the struct timeval for compatibility
688 * with other bsd systems. We reuse the storage and just monitor
689 * clock ticks for minimal overhead.
690 */
691 int
692 ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
693 {
694 int now;
695
696 /*
697 * Reset the last time and counter if this is the first call
698 * or more than a second has passed since the last update of
699 * lasttime.
700 */
701 now = ticks;
702 if (lasttime->tv_sec == 0 || (u_int)(now - lasttime->tv_sec) >= hz) {
703 lasttime->tv_sec = now;
704 *curpps = 1;
705 return (maxpps != 0);
706 } else {
707 (*curpps)++; /* NB: ignore potential overflow */
708 return (maxpps < 0 || *curpps < maxpps);
709 }
710 }
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