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/5.0/sys/kern/kern_time.c 108086 2002-12-19 09:40:13Z alfred $
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/systm.h>
49 #include <sys/sysent.h>
50 #include <sys/proc.h>
51 #include <sys/time.h>
52 #include <sys/timetc.h>
53 #include <sys/vnode.h>
54
55 #include <vm/vm.h>
56 #include <vm/vm_extern.h>
57
58 struct timezone tz;
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 return (EINVAL);
164 mtx_lock(&Giant);
165 nanotime(&ats);
166 mtx_unlock(&Giant);
167 return (copyout(&ats, uap->tp, sizeof(ats)));
168 }
169
170 #ifndef _SYS_SYSPROTO_H_
171 struct clock_settime_args {
172 clockid_t clock_id;
173 const struct timespec *tp;
174 };
175 #endif
176
177 /*
178 * MPSAFE
179 */
180 /* ARGSUSED */
181 int
182 clock_settime(struct thread *td, struct clock_settime_args *uap)
183 {
184 struct timeval atv;
185 struct timespec ats;
186 int error;
187
188 #ifdef MAC
189 error = mac_check_system_settime(td->td_ucred);
190 if (error)
191 return (error);
192 #endif
193 if ((error = suser(td)) != 0)
194 return (error);
195 if (uap->clock_id != CLOCK_REALTIME)
196 return (EINVAL);
197 if ((error = copyin(uap->tp, &ats, sizeof(ats))) != 0)
198 return (error);
199 if (ats.tv_nsec < 0 || ats.tv_nsec >= 1000000000)
200 return (EINVAL);
201 /* XXX Don't convert nsec->usec and back */
202 TIMESPEC_TO_TIMEVAL(&atv, &ats);
203 error = settime(td, &atv);
204 return (error);
205 }
206
207 #ifndef _SYS_SYSPROTO_H_
208 struct clock_getres_args {
209 clockid_t clock_id;
210 struct timespec *tp;
211 };
212 #endif
213
214 int
215 clock_getres(struct thread *td, struct clock_getres_args *uap)
216 {
217 struct timespec ts;
218 int error;
219
220 if (uap->clock_id != CLOCK_REALTIME)
221 return (EINVAL);
222 error = 0;
223 if (uap->tp) {
224 ts.tv_sec = 0;
225 /*
226 * Round up the result of the division cheaply by adding 1.
227 * Rounding up is especially important if rounding down
228 * would give 0. Perfect rounding is unimportant.
229 */
230 ts.tv_nsec = 1000000000 / tc_getfrequency() + 1;
231 error = copyout(&ts, uap->tp, sizeof(ts));
232 }
233 return (error);
234 }
235
236 static int nanowait;
237
238 static int
239 nanosleep1(struct thread *td, struct timespec *rqt, struct timespec *rmt)
240 {
241 struct timespec ts, ts2, ts3;
242 struct timeval tv;
243 int error;
244
245 if (rqt->tv_nsec < 0 || rqt->tv_nsec >= 1000000000)
246 return (EINVAL);
247 if (rqt->tv_sec < 0 || (rqt->tv_sec == 0 && rqt->tv_nsec == 0))
248 return (0);
249 getnanouptime(&ts);
250 timespecadd(&ts, rqt);
251 TIMESPEC_TO_TIMEVAL(&tv, rqt);
252 for (;;) {
253 error = tsleep(&nanowait, PWAIT | PCATCH, "nanslp",
254 tvtohz(&tv));
255 getnanouptime(&ts2);
256 if (error != EWOULDBLOCK) {
257 if (error == ERESTART)
258 error = EINTR;
259 if (rmt != NULL) {
260 timespecsub(&ts, &ts2);
261 if (ts.tv_sec < 0)
262 timespecclear(&ts);
263 *rmt = ts;
264 }
265 return (error);
266 }
267 if (timespeccmp(&ts2, &ts, >=))
268 return (0);
269 ts3 = ts;
270 timespecsub(&ts3, &ts2);
271 TIMESPEC_TO_TIMEVAL(&tv, &ts3);
272 }
273 }
274
275 #ifndef _SYS_SYSPROTO_H_
276 struct nanosleep_args {
277 struct timespec *rqtp;
278 struct timespec *rmtp;
279 };
280 #endif
281
282 /*
283 * MPSAFE
284 */
285 /* ARGSUSED */
286 int
287 nanosleep(struct thread *td, struct nanosleep_args *uap)
288 {
289 struct timespec rmt, rqt;
290 int error;
291
292 error = copyin(uap->rqtp, &rqt, sizeof(rqt));
293 if (error)
294 return (error);
295
296 mtx_lock(&Giant);
297 if (uap->rmtp) {
298 if (!useracc((caddr_t)uap->rmtp, sizeof(rmt),
299 VM_PROT_WRITE)) {
300 error = EFAULT;
301 goto done2;
302 }
303 }
304 error = nanosleep1(td, &rqt, &rmt);
305 if (error && uap->rmtp) {
306 int error2;
307
308 error2 = copyout(&rmt, uap->rmtp, sizeof(rmt));
309 if (error2) /* XXX shouldn't happen, did useracc() above */
310 error = error2;
311 }
312 done2:
313 mtx_unlock(&Giant);
314 return (error);
315 }
316
317 #ifndef _SYS_SYSPROTO_H_
318 struct gettimeofday_args {
319 struct timeval *tp;
320 struct timezone *tzp;
321 };
322 #endif
323 /*
324 * MPSAFE
325 */
326 /* ARGSUSED */
327 int
328 gettimeofday(struct thread *td, struct gettimeofday_args *uap)
329 {
330 struct timeval atv;
331 int error = 0;
332
333 if (uap->tp) {
334 microtime(&atv);
335 error = copyout(&atv, uap->tp, sizeof (atv));
336 }
337 if (error == 0 && uap->tzp != NULL) {
338 mtx_lock(&Giant);
339 error = copyout(&tz, uap->tzp, sizeof (tz));
340 mtx_unlock(&Giant);
341 }
342 return (error);
343 }
344
345 #ifndef _SYS_SYSPROTO_H_
346 struct settimeofday_args {
347 struct timeval *tv;
348 struct timezone *tzp;
349 };
350 #endif
351 /*
352 * MPSAFE
353 */
354 /* ARGSUSED */
355 int
356 settimeofday(struct thread *td, struct settimeofday_args *uap)
357 {
358 struct timeval atv;
359 struct timezone atz;
360 int error = 0;
361
362 #ifdef MAC
363 error = mac_check_system_settime(td->td_ucred);
364 if (error)
365 return (error);
366 #endif
367 if ((error = suser(td)))
368 return (error);
369 /* Verify all parameters before changing time. */
370 if (uap->tv) {
371 if ((error = copyin(uap->tv, &atv, sizeof(atv))))
372 return (error);
373 if (atv.tv_usec < 0 || atv.tv_usec >= 1000000)
374 return (EINVAL);
375 }
376 if (uap->tzp &&
377 (error = copyin(uap->tzp, &atz, sizeof(atz))))
378 return (error);
379
380 if (uap->tv && (error = settime(td, &atv)))
381 return (error);
382 if (uap->tzp) {
383 mtx_lock(&Giant);
384 tz = atz;
385 mtx_unlock(&Giant);
386 }
387 return (error);
388 }
389 /*
390 * Get value of an interval timer. The process virtual and
391 * profiling virtual time timers are kept in the p_stats area, since
392 * they can be swapped out. These are kept internally in the
393 * way they are specified externally: in time until they expire.
394 *
395 * The real time interval timer is kept in the process table slot
396 * for the process, and its value (it_value) is kept as an
397 * absolute time rather than as a delta, so that it is easy to keep
398 * periodic real-time signals from drifting.
399 *
400 * Virtual time timers are processed in the hardclock() routine of
401 * kern_clock.c. The real time timer is processed by a timeout
402 * routine, called from the softclock() routine. Since a callout
403 * may be delayed in real time due to interrupt processing in the system,
404 * it is possible for the real time timeout routine (realitexpire, given below),
405 * to be delayed in real time past when it is supposed to occur. It
406 * does not suffice, therefore, to reload the real timer .it_value from the
407 * real time timers .it_interval. Rather, we compute the next time in
408 * absolute time the timer should go off.
409 */
410 #ifndef _SYS_SYSPROTO_H_
411 struct getitimer_args {
412 u_int which;
413 struct itimerval *itv;
414 };
415 #endif
416 /*
417 * MPSAFE
418 */
419 /* ARGSUSED */
420 int
421 getitimer(struct thread *td, struct getitimer_args *uap)
422 {
423 struct proc *p = td->td_proc;
424 struct timeval ctv;
425 struct itimerval aitv;
426 int s;
427 int error;
428
429 if (uap->which > ITIMER_PROF)
430 return (EINVAL);
431
432 mtx_lock(&Giant);
433
434 s = splclock(); /* XXX still needed ? */
435 if (uap->which == ITIMER_REAL) {
436 /*
437 * Convert from absolute to relative time in .it_value
438 * part of real time timer. If time for real time timer
439 * has passed return 0, else return difference between
440 * current time and time for the timer to go off.
441 */
442 aitv = p->p_realtimer;
443 if (timevalisset(&aitv.it_value)) {
444 getmicrouptime(&ctv);
445 if (timevalcmp(&aitv.it_value, &ctv, <))
446 timevalclear(&aitv.it_value);
447 else
448 timevalsub(&aitv.it_value, &ctv);
449 }
450 } else {
451 aitv = p->p_stats->p_timer[uap->which];
452 }
453 splx(s);
454 error = copyout(&aitv, uap->itv, sizeof (struct itimerval));
455 mtx_unlock(&Giant);
456 return(error);
457 }
458
459 #ifndef _SYS_SYSPROTO_H_
460 struct setitimer_args {
461 u_int which;
462 struct itimerval *itv, *oitv;
463 };
464 #endif
465 /*
466 * MPSAFE
467 */
468 /* ARGSUSED */
469 int
470 setitimer(struct thread *td, struct setitimer_args *uap)
471 {
472 struct proc *p = td->td_proc;
473 struct itimerval aitv;
474 struct timeval ctv;
475 struct itimerval *itvp;
476 int s, error = 0;
477
478 if (uap->which > ITIMER_PROF)
479 return (EINVAL);
480 itvp = uap->itv;
481 if (itvp && (error = copyin(itvp, &aitv, sizeof(struct itimerval))))
482 return (error);
483
484 mtx_lock(&Giant);
485
486 if ((uap->itv = uap->oitv) &&
487 (error = getitimer(td, (struct getitimer_args *)uap))) {
488 goto done2;
489 }
490 if (itvp == 0) {
491 error = 0;
492 goto done2;
493 }
494 if (itimerfix(&aitv.it_value)) {
495 error = EINVAL;
496 goto done2;
497 }
498 if (!timevalisset(&aitv.it_value)) {
499 timevalclear(&aitv.it_interval);
500 } else if (itimerfix(&aitv.it_interval)) {
501 error = EINVAL;
502 goto done2;
503 }
504 s = splclock(); /* XXX: still needed ? */
505 if (uap->which == ITIMER_REAL) {
506 if (timevalisset(&p->p_realtimer.it_value))
507 callout_stop(&p->p_itcallout);
508 if (timevalisset(&aitv.it_value))
509 callout_reset(&p->p_itcallout, tvtohz(&aitv.it_value),
510 realitexpire, p);
511 getmicrouptime(&ctv);
512 timevaladd(&aitv.it_value, &ctv);
513 p->p_realtimer = aitv;
514 } else {
515 p->p_stats->p_timer[uap->which] = aitv;
516 }
517 splx(s);
518 done2:
519 mtx_unlock(&Giant);
520 return (error);
521 }
522
523 /*
524 * Real interval timer expired:
525 * send process whose timer expired an alarm signal.
526 * If time is not set up to reload, then just return.
527 * Else compute next time timer should go off which is > current time.
528 * This is where delay in processing this timeout causes multiple
529 * SIGALRM calls to be compressed into one.
530 * tvtohz() always adds 1 to allow for the time until the next clock
531 * interrupt being strictly less than 1 clock tick, but we don't want
532 * that here since we want to appear to be in sync with the clock
533 * interrupt even when we're delayed.
534 */
535 void
536 realitexpire(void *arg)
537 {
538 struct proc *p;
539 struct timeval ctv, ntv;
540 int s;
541
542 p = (struct proc *)arg;
543 PROC_LOCK(p);
544 psignal(p, SIGALRM);
545 if (!timevalisset(&p->p_realtimer.it_interval)) {
546 timevalclear(&p->p_realtimer.it_value);
547 PROC_UNLOCK(p);
548 return;
549 }
550 for (;;) {
551 s = splclock(); /* XXX: still neeeded ? */
552 timevaladd(&p->p_realtimer.it_value,
553 &p->p_realtimer.it_interval);
554 getmicrouptime(&ctv);
555 if (timevalcmp(&p->p_realtimer.it_value, &ctv, >)) {
556 ntv = p->p_realtimer.it_value;
557 timevalsub(&ntv, &ctv);
558 callout_reset(&p->p_itcallout, tvtohz(&ntv) - 1,
559 realitexpire, p);
560 splx(s);
561 PROC_UNLOCK(p);
562 return;
563 }
564 splx(s);
565 }
566 /*NOTREACHED*/
567 }
568
569 /*
570 * Check that a proposed value to load into the .it_value or
571 * .it_interval part of an interval timer is acceptable, and
572 * fix it to have at least minimal value (i.e. if it is less
573 * than the resolution of the clock, round it up.)
574 */
575 int
576 itimerfix(struct timeval *tv)
577 {
578
579 if (tv->tv_sec < 0 || tv->tv_sec > 100000000 ||
580 tv->tv_usec < 0 || tv->tv_usec >= 1000000)
581 return (EINVAL);
582 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
583 tv->tv_usec = tick;
584 return (0);
585 }
586
587 /*
588 * Decrement an interval timer by a specified number
589 * of microseconds, which must be less than a second,
590 * i.e. < 1000000. If the timer expires, then reload
591 * it. In this case, carry over (usec - old value) to
592 * reduce the value reloaded into the timer so that
593 * the timer does not drift. This routine assumes
594 * that it is called in a context where the timers
595 * on which it is operating cannot change in value.
596 */
597 int
598 itimerdecr(struct itimerval *itp, int usec)
599 {
600
601 if (itp->it_value.tv_usec < usec) {
602 if (itp->it_value.tv_sec == 0) {
603 /* expired, and already in next interval */
604 usec -= itp->it_value.tv_usec;
605 goto expire;
606 }
607 itp->it_value.tv_usec += 1000000;
608 itp->it_value.tv_sec--;
609 }
610 itp->it_value.tv_usec -= usec;
611 usec = 0;
612 if (timevalisset(&itp->it_value))
613 return (1);
614 /* expired, exactly at end of interval */
615 expire:
616 if (timevalisset(&itp->it_interval)) {
617 itp->it_value = itp->it_interval;
618 itp->it_value.tv_usec -= usec;
619 if (itp->it_value.tv_usec < 0) {
620 itp->it_value.tv_usec += 1000000;
621 itp->it_value.tv_sec--;
622 }
623 } else
624 itp->it_value.tv_usec = 0; /* sec is already 0 */
625 return (0);
626 }
627
628 /*
629 * Add and subtract routines for timevals.
630 * N.B.: subtract routine doesn't deal with
631 * results which are before the beginning,
632 * it just gets very confused in this case.
633 * Caveat emptor.
634 */
635 void
636 timevaladd(struct timeval *t1, struct timeval *t2)
637 {
638
639 t1->tv_sec += t2->tv_sec;
640 t1->tv_usec += t2->tv_usec;
641 timevalfix(t1);
642 }
643
644 void
645 timevalsub(struct timeval *t1, struct timeval *t2)
646 {
647
648 t1->tv_sec -= t2->tv_sec;
649 t1->tv_usec -= t2->tv_usec;
650 timevalfix(t1);
651 }
652
653 static void
654 timevalfix(struct timeval *t1)
655 {
656
657 if (t1->tv_usec < 0) {
658 t1->tv_sec--;
659 t1->tv_usec += 1000000;
660 }
661 if (t1->tv_usec >= 1000000) {
662 t1->tv_sec++;
663 t1->tv_usec -= 1000000;
664 }
665 }
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