projects/linux·blob v2.6.16 · refs

687 lines · 18.2 KiB

1/*
2 * linux/kernel/time.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * This file contains the interface functions for the various
7 * time related system calls: time, stime, gettimeofday, settimeofday,
8 * adjtime
9 */
10/*
11 * Modification history kernel/time.c
12 *
13 * 1993-09-02 Philip Gladstone
14 * Created file with time related functions from sched.c and adjtimex()
15 * 1993-10-08 Torsten Duwe
16 * adjtime interface update and CMOS clock write code
17 * 1995-08-13 Torsten Duwe
18 * kernel PLL updated to 1994-12-13 specs (rfc-1589)
19 * 1999-01-16 Ulrich Windl
20 * Introduced error checking for many cases in adjtimex().
21 * Updated NTP code according to technical memorandum Jan '96
22 * "A Kernel Model for Precision Timekeeping" by Dave Mills
23 * Allow time_constant larger than MAXTC(6) for NTP v4 (MAXTC == 10)
24 * (Even though the technical memorandum forbids it)
25 * 2004-07-14 Christoph Lameter
26 * Added getnstimeofday to allow the posix timer functions to return
27 * with nanosecond accuracy
28 */
29
30#include <linux/module.h>
31#include <linux/timex.h>
32#include <linux/capability.h>
33#include <linux/errno.h>
34#include <linux/smp_lock.h>
35#include <linux/syscalls.h>
36#include <linux/security.h>
37#include <linux/fs.h>
38#include <linux/module.h>
39
40#include <asm/uaccess.h>
41#include <asm/unistd.h>
42
43/*
44 * The timezone where the local system is located. Used as a default by some
45 * programs who obtain this value by using gettimeofday.
46 */
47struct timezone sys_tz;
48
49EXPORT_SYMBOL(sys_tz);
50
51#ifdef __ARCH_WANT_SYS_TIME
52
53/*
54 * sys_time() can be implemented in user-level using
55 * sys_gettimeofday(). Is this for backwards compatibility? If so,
56 * why not move it into the appropriate arch directory (for those
57 * architectures that need it).
58 */
59asmlinkage long sys_time(time_t __user * tloc)
60{
61 time_t i;
62 struct timeval tv;
63
64 do_gettimeofday(&tv);
65 i = tv.tv_sec;
66
67 if (tloc) {
68 if (put_user(i,tloc))
69 i = -EFAULT;
70 }
71 return i;
72}
73
74/*
75 * sys_stime() can be implemented in user-level using
76 * sys_settimeofday(). Is this for backwards compatibility? If so,
77 * why not move it into the appropriate arch directory (for those
78 * architectures that need it).
79 */
80
81asmlinkage long sys_stime(time_t __user *tptr)
82{
83 struct timespec tv;
84 int err;
85
86 if (get_user(tv.tv_sec, tptr))
87 return -EFAULT;
88
89 tv.tv_nsec = 0;
90
91 err = security_settime(&tv, NULL);
92 if (err)
93 return err;
94
95 do_settimeofday(&tv);
96 return 0;
97}
98
99#endif /* __ARCH_WANT_SYS_TIME */
100
101asmlinkage long sys_gettimeofday(struct timeval __user *tv, struct timezone __user *tz)
102{
103 if (likely(tv != NULL)) {
104 struct timeval ktv;
105 do_gettimeofday(&ktv);
106 if (copy_to_user(tv, &ktv, sizeof(ktv)))
107 return -EFAULT;
108 }
109 if (unlikely(tz != NULL)) {
110 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
111 return -EFAULT;
112 }
113 return 0;
114}
115
116/*
117 * Adjust the time obtained from the CMOS to be UTC time instead of
118 * local time.
119 *
120 * This is ugly, but preferable to the alternatives. Otherwise we
121 * would either need to write a program to do it in /etc/rc (and risk
122 * confusion if the program gets run more than once; it would also be
123 * hard to make the program warp the clock precisely n hours) or
124 * compile in the timezone information into the kernel. Bad, bad....
125 *
126 * - TYT, 1992-01-01
127 *
128 * The best thing to do is to keep the CMOS clock in universal time (UTC)
129 * as real UNIX machines always do it. This avoids all headaches about
130 * daylight saving times and warping kernel clocks.
131 */
132static inline void warp_clock(void)
133{
134 write_seqlock_irq(&xtime_lock);
135 wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60;
136 xtime.tv_sec += sys_tz.tz_minuteswest * 60;
137 time_interpolator_reset();
138 write_sequnlock_irq(&xtime_lock);
139 clock_was_set();
140}
141
142/*
143 * In case for some reason the CMOS clock has not already been running
144 * in UTC, but in some local time: The first time we set the timezone,
145 * we will warp the clock so that it is ticking UTC time instead of
146 * local time. Presumably, if someone is setting the timezone then we
147 * are running in an environment where the programs understand about
148 * timezones. This should be done at boot time in the /etc/rc script,
149 * as soon as possible, so that the clock can be set right. Otherwise,
150 * various programs will get confused when the clock gets warped.
151 */
152
153int do_sys_settimeofday(struct timespec *tv, struct timezone *tz)
154{
155 static int firsttime = 1;
156 int error = 0;
157
158 if (tv && !timespec_valid(tv))
159 return -EINVAL;
160
161 error = security_settime(tv, tz);
162 if (error)
163 return error;
164
165 if (tz) {
166 /* SMP safe, global irq locking makes it work. */
167 sys_tz = *tz;
168 if (firsttime) {
169 firsttime = 0;
170 if (!tv)
171 warp_clock();
172 }
173 }
174 if (tv)
175 {
176 /* SMP safe, again the code in arch/foo/time.c should
177 * globally block out interrupts when it runs.
178 */
179 return do_settimeofday(tv);
180 }
181 return 0;
182}
183
184asmlinkage long sys_settimeofday(struct timeval __user *tv,
185 struct timezone __user *tz)
186{
187 struct timeval user_tv;
188 struct timespec new_ts;
189 struct timezone new_tz;
190
191 if (tv) {
192 if (copy_from_user(&user_tv, tv, sizeof(*tv)))
193 return -EFAULT;
194 new_ts.tv_sec = user_tv.tv_sec;
195 new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
196 }
197 if (tz) {
198 if (copy_from_user(&new_tz, tz, sizeof(*tz)))
199 return -EFAULT;
200 }
201
202 return do_sys_settimeofday(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
203}
204
205long pps_offset; /* pps time offset (us) */
206long pps_jitter = MAXTIME; /* time dispersion (jitter) (us) */
207
208long pps_freq; /* frequency offset (scaled ppm) */
209long pps_stabil = MAXFREQ; /* frequency dispersion (scaled ppm) */
210
211long pps_valid = PPS_VALID; /* pps signal watchdog counter */
212
213int pps_shift = PPS_SHIFT; /* interval duration (s) (shift) */
214
215long pps_jitcnt; /* jitter limit exceeded */
216long pps_calcnt; /* calibration intervals */
217long pps_errcnt; /* calibration errors */
218long pps_stbcnt; /* stability limit exceeded */
219
220/* hook for a loadable hardpps kernel module */
221void (*hardpps_ptr)(struct timeval *);
222
223/* we call this to notify the arch when the clock is being
224 * controlled. If no such arch routine, do nothing.
225 */
226void __attribute__ ((weak)) notify_arch_cmos_timer(void)
227{
228 return;
229}
230
231/* adjtimex mainly allows reading (and writing, if superuser) of
232 * kernel time-keeping variables. used by xntpd.
233 */
234int do_adjtimex(struct timex *txc)
235{
236 long ltemp, mtemp, save_adjust;
237 int result;
238
239 /* In order to modify anything, you gotta be super-user! */
240 if (txc->modes && !capable(CAP_SYS_TIME))
241 return -EPERM;
242
243 /* Now we validate the data before disabling interrupts */
244
245 if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
246 /* singleshot must not be used with any other mode bits */
247 if (txc->modes != ADJ_OFFSET_SINGLESHOT)
248 return -EINVAL;
249
250 if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
251 /* adjustment Offset limited to +- .512 seconds */
252 if (txc->offset <= - MAXPHASE || txc->offset >= MAXPHASE )
253 return -EINVAL;
254
255 /* if the quartz is off by more than 10% something is VERY wrong ! */
256 if (txc->modes & ADJ_TICK)
257 if (txc->tick < 900000/USER_HZ ||
258 txc->tick > 1100000/USER_HZ)
259 return -EINVAL;
260
261 write_seqlock_irq(&xtime_lock);
262 result = time_state; /* mostly `TIME_OK' */
263
264 /* Save for later - semantics of adjtime is to return old value */
265 save_adjust = time_next_adjust ? time_next_adjust : time_adjust;
266
267#if 0 /* STA_CLOCKERR is never set yet */
268 time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */
269#endif
270 /* If there are input parameters, then process them */
271 if (txc->modes)
272 {
273 if (txc->modes & ADJ_STATUS) /* only set allowed bits */
274 time_status = (txc->status & ~STA_RONLY) |
275 (time_status & STA_RONLY);
276
277 if (txc->modes & ADJ_FREQUENCY) { /* p. 22 */
278 if (txc->freq > MAXFREQ || txc->freq < -MAXFREQ) {
279 result = -EINVAL;
280 goto leave;
281 }
282 time_freq = txc->freq - pps_freq;
283 }
284
285 if (txc->modes & ADJ_MAXERROR) {
286 if (txc->maxerror < 0 || txc->maxerror >= NTP_PHASE_LIMIT) {
287 result = -EINVAL;
288 goto leave;
289 }
290 time_maxerror = txc->maxerror;
291 }
292
293 if (txc->modes & ADJ_ESTERROR) {
294 if (txc->esterror < 0 || txc->esterror >= NTP_PHASE_LIMIT) {
295 result = -EINVAL;
296 goto leave;
297 }
298 time_esterror = txc->esterror;
299 }
300
301 if (txc->modes & ADJ_TIMECONST) { /* p. 24 */
302 if (txc->constant < 0) { /* NTP v4 uses values > 6 */
303 result = -EINVAL;
304 goto leave;
305 }
306 time_constant = txc->constant;
307 }
308
309 if (txc->modes & ADJ_OFFSET) { /* values checked earlier */
310 if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
311 /* adjtime() is independent from ntp_adjtime() */
312 if ((time_next_adjust = txc->offset) == 0)
313 time_adjust = 0;
314 }
315 else if ( time_status & (STA_PLL | STA_PPSTIME) ) {
316 ltemp = (time_status & (STA_PPSTIME | STA_PPSSIGNAL)) ==
317 (STA_PPSTIME | STA_PPSSIGNAL) ?
318 pps_offset : txc->offset;
319
320 /*
321 * Scale the phase adjustment and
322 * clamp to the operating range.
323 */
324 if (ltemp > MAXPHASE)
325 time_offset = MAXPHASE << SHIFT_UPDATE;
326 else if (ltemp < -MAXPHASE)
327 time_offset = -(MAXPHASE << SHIFT_UPDATE);
328 else
329 time_offset = ltemp << SHIFT_UPDATE;
330
331 /*
332 * Select whether the frequency is to be controlled
333 * and in which mode (PLL or FLL). Clamp to the operating
334 * range. Ugly multiply/divide should be replaced someday.
335 */
336
337 if (time_status & STA_FREQHOLD || time_reftime == 0)
338 time_reftime = xtime.tv_sec;
339 mtemp = xtime.tv_sec - time_reftime;
340 time_reftime = xtime.tv_sec;
341 if (time_status & STA_FLL) {
342 if (mtemp >= MINSEC) {
343 ltemp = (time_offset / mtemp) << (SHIFT_USEC -
344 SHIFT_UPDATE);
345 time_freq += shift_right(ltemp, SHIFT_KH);
346 } else /* calibration interval too short (p. 12) */
347 result = TIME_ERROR;
348 } else { /* PLL mode */
349 if (mtemp < MAXSEC) {
350 ltemp *= mtemp;
351 time_freq += shift_right(ltemp,(time_constant +
352 time_constant +
353 SHIFT_KF - SHIFT_USEC));
354 } else /* calibration interval too long (p. 12) */
355 result = TIME_ERROR;
356 }
357 time_freq = min(time_freq, time_tolerance);
358 time_freq = max(time_freq, -time_tolerance);
359 } /* STA_PLL || STA_PPSTIME */
360 } /* txc->modes & ADJ_OFFSET */
361 if (txc->modes & ADJ_TICK) {
362 tick_usec = txc->tick;
363 tick_nsec = TICK_USEC_TO_NSEC(tick_usec);
364 }
365 } /* txc->modes */
366leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0
367 || ((time_status & (STA_PPSFREQ|STA_PPSTIME)) != 0
368 && (time_status & STA_PPSSIGNAL) == 0)
369 /* p. 24, (b) */
370 || ((time_status & (STA_PPSTIME|STA_PPSJITTER))
371 == (STA_PPSTIME|STA_PPSJITTER))
372 /* p. 24, (c) */
373 || ((time_status & STA_PPSFREQ) != 0
374 && (time_status & (STA_PPSWANDER|STA_PPSERROR)) != 0))
375 /* p. 24, (d) */
376 result = TIME_ERROR;
377
378 if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
379 txc->offset = save_adjust;
380 else {
381 txc->offset = shift_right(time_offset, SHIFT_UPDATE);
382 }
383 txc->freq = time_freq + pps_freq;
384 txc->maxerror = time_maxerror;
385 txc->esterror = time_esterror;
386 txc->status = time_status;
387 txc->constant = time_constant;
388 txc->precision = time_precision;
389 txc->tolerance = time_tolerance;
390 txc->tick = tick_usec;
391 txc->ppsfreq = pps_freq;
392 txc->jitter = pps_jitter >> PPS_AVG;
393 txc->shift = pps_shift;
394 txc->stabil = pps_stabil;
395 txc->jitcnt = pps_jitcnt;
396 txc->calcnt = pps_calcnt;
397 txc->errcnt = pps_errcnt;
398 txc->stbcnt = pps_stbcnt;
399 write_sequnlock_irq(&xtime_lock);
400 do_gettimeofday(&txc->time);
401 notify_arch_cmos_timer();
402 return(result);
403}
404
405asmlinkage long sys_adjtimex(struct timex __user *txc_p)
406{
407 struct timex txc; /* Local copy of parameter */
408 int ret;
409
410 /* Copy the user data space into the kernel copy
411 * structure. But bear in mind that the structures
412 * may change
413 */
414 if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
415 return -EFAULT;
416 ret = do_adjtimex(&txc);
417 return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
418}
419
420inline struct timespec current_kernel_time(void)
421{
422 struct timespec now;
423 unsigned long seq;
424
425 do {
426 seq = read_seqbegin(&xtime_lock);
427
428 now = xtime;
429 } while (read_seqretry(&xtime_lock, seq));
430
431 return now;
432}
433
434EXPORT_SYMBOL(current_kernel_time);
435
436/**
437 * current_fs_time - Return FS time
438 * @sb: Superblock.
439 *
440 * Return the current time truncated to the time granuality supported by
441 * the fs.
442 */
443struct timespec current_fs_time(struct super_block *sb)
444{
445 struct timespec now = current_kernel_time();
446 return timespec_trunc(now, sb->s_time_gran);
447}
448EXPORT_SYMBOL(current_fs_time);
449
450/**
451 * timespec_trunc - Truncate timespec to a granuality
452 * @t: Timespec
453 * @gran: Granuality in ns.
454 *
455 * Truncate a timespec to a granuality. gran must be smaller than a second.
456 * Always rounds down.
457 *
458 * This function should be only used for timestamps returned by
459 * current_kernel_time() or CURRENT_TIME, not with do_gettimeofday() because
460 * it doesn't handle the better resolution of the later.
461 */
462struct timespec timespec_trunc(struct timespec t, unsigned gran)
463{
464 /*
465 * Division is pretty slow so avoid it for common cases.
466 * Currently current_kernel_time() never returns better than
467 * jiffies resolution. Exploit that.
468 */
469 if (gran <= jiffies_to_usecs(1) * 1000) {
470 /* nothing */
471 } else if (gran == 1000000000) {
472 t.tv_nsec = 0;
473 } else {
474 t.tv_nsec -= t.tv_nsec % gran;
475 }
476 return t;
477}
478EXPORT_SYMBOL(timespec_trunc);
479
480#ifdef CONFIG_TIME_INTERPOLATION
481void getnstimeofday (struct timespec *tv)
482{
483 unsigned long seq,sec,nsec;
484
485 do {
486 seq = read_seqbegin(&xtime_lock);
487 sec = xtime.tv_sec;
488 nsec = xtime.tv_nsec+time_interpolator_get_offset();
489 } while (unlikely(read_seqretry(&xtime_lock, seq)));
490
491 while (unlikely(nsec >= NSEC_PER_SEC)) {
492 nsec -= NSEC_PER_SEC;
493 ++sec;
494 }
495 tv->tv_sec = sec;
496 tv->tv_nsec = nsec;
497}
498EXPORT_SYMBOL_GPL(getnstimeofday);
499
500int do_settimeofday (struct timespec *tv)
501{
502 time_t wtm_sec, sec = tv->tv_sec;
503 long wtm_nsec, nsec = tv->tv_nsec;
504
505 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
506 return -EINVAL;
507
508 write_seqlock_irq(&xtime_lock);
509 {
510 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
511 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
512
513 set_normalized_timespec(&xtime, sec, nsec);
514 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
515
516 time_adjust = 0; /* stop active adjtime() */
517 time_status |= STA_UNSYNC;
518 time_maxerror = NTP_PHASE_LIMIT;
519 time_esterror = NTP_PHASE_LIMIT;
520 time_interpolator_reset();
521 }
522 write_sequnlock_irq(&xtime_lock);
523 clock_was_set();
524 return 0;
525}
526EXPORT_SYMBOL(do_settimeofday);
527
528void do_gettimeofday (struct timeval *tv)
529{
530 unsigned long seq, nsec, usec, sec, offset;
531 do {
532 seq = read_seqbegin(&xtime_lock);
533 offset = time_interpolator_get_offset();
534 sec = xtime.tv_sec;
535 nsec = xtime.tv_nsec;
536 } while (unlikely(read_seqretry(&xtime_lock, seq)));
537
538 usec = (nsec + offset) / 1000;
539
540 while (unlikely(usec >= USEC_PER_SEC)) {
541 usec -= USEC_PER_SEC;
542 ++sec;
543 }
544
545 tv->tv_sec = sec;
546 tv->tv_usec = usec;
547}
548
549EXPORT_SYMBOL(do_gettimeofday);
550
551
552#else
553/*
554 * Simulate gettimeofday using do_gettimeofday which only allows a timeval
555 * and therefore only yields usec accuracy
556 */
557void getnstimeofday(struct timespec *tv)
558{
559 struct timeval x;
560
561 do_gettimeofday(&x);
562 tv->tv_sec = x.tv_sec;
563 tv->tv_nsec = x.tv_usec * NSEC_PER_USEC;
564}
565EXPORT_SYMBOL_GPL(getnstimeofday);
566#endif
567
568/* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
569 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
570 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
571 *
572 * [For the Julian calendar (which was used in Russia before 1917,
573 * Britain & colonies before 1752, anywhere else before 1582,
574 * and is still in use by some communities) leave out the
575 * -year/100+year/400 terms, and add 10.]
576 *
577 * This algorithm was first published by Gauss (I think).
578 *
579 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
580 * machines were long is 32-bit! (However, as time_t is signed, we
581 * will already get problems at other places on 2038-01-19 03:14:08)
582 */
583unsigned long
584mktime(const unsigned int year0, const unsigned int mon0,
585 const unsigned int day, const unsigned int hour,
586 const unsigned int min, const unsigned int sec)
587{
588 unsigned int mon = mon0, year = year0;
589
590 /* 1..12 -> 11,12,1..10 */
591 if (0 >= (int) (mon -= 2)) {
592 mon += 12; /* Puts Feb last since it has leap day */
593 year -= 1;
594 }
595
596 return ((((unsigned long)
597 (year/4 - year/100 + year/400 + 367*mon/12 + day) +
598 year*365 - 719499
599 )*24 + hour /* now have hours */
600 )*60 + min /* now have minutes */
601 )*60 + sec; /* finally seconds */
602}
603
604EXPORT_SYMBOL(mktime);
605
606/**
607 * set_normalized_timespec - set timespec sec and nsec parts and normalize
608 *
609 * @ts: pointer to timespec variable to be set
610 * @sec: seconds to set
611 * @nsec: nanoseconds to set
612 *
613 * Set seconds and nanoseconds field of a timespec variable and
614 * normalize to the timespec storage format
615 *
616 * Note: The tv_nsec part is always in the range of
617 * 0 <= tv_nsec < NSEC_PER_SEC
618 * For negative values only the tv_sec field is negative !
619 */
620void set_normalized_timespec(struct timespec *ts, time_t sec, long nsec)
621{
622 while (nsec >= NSEC_PER_SEC) {
623 nsec -= NSEC_PER_SEC;
624 ++sec;
625 }
626 while (nsec < 0) {
627 nsec += NSEC_PER_SEC;
628 --sec;
629 }
630 ts->tv_sec = sec;
631 ts->tv_nsec = nsec;
632}
633
634/**
635 * ns_to_timespec - Convert nanoseconds to timespec
636 * @nsec: the nanoseconds value to be converted
637 *
638 * Returns the timespec representation of the nsec parameter.
639 */
640struct timespec ns_to_timespec(const nsec_t nsec)
641{
642 struct timespec ts;
643
644 if (!nsec)
645 return (struct timespec) {0, 0};
646
647 ts.tv_sec = div_long_long_rem_signed(nsec, NSEC_PER_SEC, &ts.tv_nsec);
648 if (unlikely(nsec < 0))
649 set_normalized_timespec(&ts, ts.tv_sec, ts.tv_nsec);
650
651 return ts;
652}
653
654/**
655 * ns_to_timeval - Convert nanoseconds to timeval
656 * @nsec: the nanoseconds value to be converted
657 *
658 * Returns the timeval representation of the nsec parameter.
659 */
660struct timeval ns_to_timeval(const nsec_t nsec)
661{
662 struct timespec ts = ns_to_timespec(nsec);
663 struct timeval tv;
664
665 tv.tv_sec = ts.tv_sec;
666 tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000;
667
668 return tv;
669}
670
671#if (BITS_PER_LONG < 64)
672u64 get_jiffies_64(void)
673{
674 unsigned long seq;
675 u64 ret;
676
677 do {
678 seq = read_seqbegin(&xtime_lock);
679 ret = jiffies_64;
680 } while (read_seqretry(&xtime_lock, seq));
681 return ret;
682}
683
684EXPORT_SYMBOL(get_jiffies_64);
685#endif
686
687EXPORT_SYMBOL(jiffies);