projects/linux·blob v2.6.18 · refs

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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
205/* we call this to notify the arch when the clock is being
206 * controlled. If no such arch routine, do nothing.
207 */
208void __attribute__ ((weak)) notify_arch_cmos_timer(void)
209{
210 return;
211}
212
213/* adjtimex mainly allows reading (and writing, if superuser) of
214 * kernel time-keeping variables. used by xntpd.
215 */
216int do_adjtimex(struct timex *txc)
217{
218 long ltemp, mtemp, save_adjust;
219 int result;
220
221 /* In order to modify anything, you gotta be super-user! */
222 if (txc->modes && !capable(CAP_SYS_TIME))
223 return -EPERM;
224
225 /* Now we validate the data before disabling interrupts */
226
227 if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
228 /* singleshot must not be used with any other mode bits */
229 if (txc->modes != ADJ_OFFSET_SINGLESHOT)
230 return -EINVAL;
231
232 if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
233 /* adjustment Offset limited to +- .512 seconds */
234 if (txc->offset <= - MAXPHASE || txc->offset >= MAXPHASE )
235 return -EINVAL;
236
237 /* if the quartz is off by more than 10% something is VERY wrong ! */
238 if (txc->modes & ADJ_TICK)
239 if (txc->tick < 900000/USER_HZ ||
240 txc->tick > 1100000/USER_HZ)
241 return -EINVAL;
242
243 write_seqlock_irq(&xtime_lock);
244 result = time_state; /* mostly `TIME_OK' */
245
246 /* Save for later - semantics of adjtime is to return old value */
247 save_adjust = time_next_adjust ? time_next_adjust : time_adjust;
248
249#if 0 /* STA_CLOCKERR is never set yet */
250 time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */
251#endif
252 /* If there are input parameters, then process them */
253 if (txc->modes)
254 {
255 if (txc->modes & ADJ_STATUS) /* only set allowed bits */
256 time_status = (txc->status & ~STA_RONLY) |
257 (time_status & STA_RONLY);
258
259 if (txc->modes & ADJ_FREQUENCY) { /* p. 22 */
260 if (txc->freq > MAXFREQ || txc->freq < -MAXFREQ) {
261 result = -EINVAL;
262 goto leave;
263 }
264 time_freq = txc->freq;
265 }
266
267 if (txc->modes & ADJ_MAXERROR) {
268 if (txc->maxerror < 0 || txc->maxerror >= NTP_PHASE_LIMIT) {
269 result = -EINVAL;
270 goto leave;
271 }
272 time_maxerror = txc->maxerror;
273 }
274
275 if (txc->modes & ADJ_ESTERROR) {
276 if (txc->esterror < 0 || txc->esterror >= NTP_PHASE_LIMIT) {
277 result = -EINVAL;
278 goto leave;
279 }
280 time_esterror = txc->esterror;
281 }
282
283 if (txc->modes & ADJ_TIMECONST) { /* p. 24 */
284 if (txc->constant < 0) { /* NTP v4 uses values > 6 */
285 result = -EINVAL;
286 goto leave;
287 }
288 time_constant = txc->constant;
289 }
290
291 if (txc->modes & ADJ_OFFSET) { /* values checked earlier */
292 if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
293 /* adjtime() is independent from ntp_adjtime() */
294 if ((time_next_adjust = txc->offset) == 0)
295 time_adjust = 0;
296 }
297 else if (time_status & STA_PLL) {
298 ltemp = txc->offset;
299
300 /*
301 * Scale the phase adjustment and
302 * clamp to the operating range.
303 */
304 if (ltemp > MAXPHASE)
305 time_offset = MAXPHASE << SHIFT_UPDATE;
306 else if (ltemp < -MAXPHASE)
307 time_offset = -(MAXPHASE << SHIFT_UPDATE);
308 else
309 time_offset = ltemp << SHIFT_UPDATE;
310
311 /*
312 * Select whether the frequency is to be controlled
313 * and in which mode (PLL or FLL). Clamp to the operating
314 * range. Ugly multiply/divide should be replaced someday.
315 */
316
317 if (time_status & STA_FREQHOLD || time_reftime == 0)
318 time_reftime = xtime.tv_sec;
319 mtemp = xtime.tv_sec - time_reftime;
320 time_reftime = xtime.tv_sec;
321 if (time_status & STA_FLL) {
322 if (mtemp >= MINSEC) {
323 ltemp = (time_offset / mtemp) << (SHIFT_USEC -
324 SHIFT_UPDATE);
325 time_freq += shift_right(ltemp, SHIFT_KH);
326 } else /* calibration interval too short (p. 12) */
327 result = TIME_ERROR;
328 } else { /* PLL mode */
329 if (mtemp < MAXSEC) {
330 ltemp *= mtemp;
331 time_freq += shift_right(ltemp,(time_constant +
332 time_constant +
333 SHIFT_KF - SHIFT_USEC));
334 } else /* calibration interval too long (p. 12) */
335 result = TIME_ERROR;
336 }
337 time_freq = min(time_freq, time_tolerance);
338 time_freq = max(time_freq, -time_tolerance);
339 } /* STA_PLL */
340 } /* txc->modes & ADJ_OFFSET */
341 if (txc->modes & ADJ_TICK) {
342 tick_usec = txc->tick;
343 tick_nsec = TICK_USEC_TO_NSEC(tick_usec);
344 }
345 } /* txc->modes */
346leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0)
347 result = TIME_ERROR;
348
349 if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
350 txc->offset = save_adjust;
351 else {
352 txc->offset = shift_right(time_offset, SHIFT_UPDATE);
353 }
354 txc->freq = time_freq;
355 txc->maxerror = time_maxerror;
356 txc->esterror = time_esterror;
357 txc->status = time_status;
358 txc->constant = time_constant;
359 txc->precision = time_precision;
360 txc->tolerance = time_tolerance;
361 txc->tick = tick_usec;
362
363 /* PPS is not implemented, so these are zero */
364 txc->ppsfreq = 0;
365 txc->jitter = 0;
366 txc->shift = 0;
367 txc->stabil = 0;
368 txc->jitcnt = 0;
369 txc->calcnt = 0;
370 txc->errcnt = 0;
371 txc->stbcnt = 0;
372 write_sequnlock_irq(&xtime_lock);
373 do_gettimeofday(&txc->time);
374 notify_arch_cmos_timer();
375 return(result);
376}
377
378asmlinkage long sys_adjtimex(struct timex __user *txc_p)
379{
380 struct timex txc; /* Local copy of parameter */
381 int ret;
382
383 /* Copy the user data space into the kernel copy
384 * structure. But bear in mind that the structures
385 * may change
386 */
387 if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
388 return -EFAULT;
389 ret = do_adjtimex(&txc);
390 return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
391}
392
393inline struct timespec current_kernel_time(void)
394{
395 struct timespec now;
396 unsigned long seq;
397
398 do {
399 seq = read_seqbegin(&xtime_lock);
400
401 now = xtime;
402 } while (read_seqretry(&xtime_lock, seq));
403
404 return now;
405}
406
407EXPORT_SYMBOL(current_kernel_time);
408
409/**
410 * current_fs_time - Return FS time
411 * @sb: Superblock.
412 *
413 * Return the current time truncated to the time granularity supported by
414 * the fs.
415 */
416struct timespec current_fs_time(struct super_block *sb)
417{
418 struct timespec now = current_kernel_time();
419 return timespec_trunc(now, sb->s_time_gran);
420}
421EXPORT_SYMBOL(current_fs_time);
422
423/**
424 * timespec_trunc - Truncate timespec to a granularity
425 * @t: Timespec
426 * @gran: Granularity in ns.
427 *
428 * Truncate a timespec to a granularity. gran must be smaller than a second.
429 * Always rounds down.
430 *
431 * This function should be only used for timestamps returned by
432 * current_kernel_time() or CURRENT_TIME, not with do_gettimeofday() because
433 * it doesn't handle the better resolution of the later.
434 */
435struct timespec timespec_trunc(struct timespec t, unsigned gran)
436{
437 /*
438 * Division is pretty slow so avoid it for common cases.
439 * Currently current_kernel_time() never returns better than
440 * jiffies resolution. Exploit that.
441 */
442 if (gran <= jiffies_to_usecs(1) * 1000) {
443 /* nothing */
444 } else if (gran == 1000000000) {
445 t.tv_nsec = 0;
446 } else {
447 t.tv_nsec -= t.tv_nsec % gran;
448 }
449 return t;
450}
451EXPORT_SYMBOL(timespec_trunc);
452
453#ifdef CONFIG_TIME_INTERPOLATION
454void getnstimeofday (struct timespec *tv)
455{
456 unsigned long seq,sec,nsec;
457
458 do {
459 seq = read_seqbegin(&xtime_lock);
460 sec = xtime.tv_sec;
461 nsec = xtime.tv_nsec+time_interpolator_get_offset();
462 } while (unlikely(read_seqretry(&xtime_lock, seq)));
463
464 while (unlikely(nsec >= NSEC_PER_SEC)) {
465 nsec -= NSEC_PER_SEC;
466 ++sec;
467 }
468 tv->tv_sec = sec;
469 tv->tv_nsec = nsec;
470}
471EXPORT_SYMBOL_GPL(getnstimeofday);
472
473int do_settimeofday (struct timespec *tv)
474{
475 time_t wtm_sec, sec = tv->tv_sec;
476 long wtm_nsec, nsec = tv->tv_nsec;
477
478 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
479 return -EINVAL;
480
481 write_seqlock_irq(&xtime_lock);
482 {
483 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
484 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
485
486 set_normalized_timespec(&xtime, sec, nsec);
487 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
488
489 time_adjust = 0; /* stop active adjtime() */
490 time_status |= STA_UNSYNC;
491 time_maxerror = NTP_PHASE_LIMIT;
492 time_esterror = NTP_PHASE_LIMIT;
493 time_interpolator_reset();
494 }
495 write_sequnlock_irq(&xtime_lock);
496 clock_was_set();
497 return 0;
498}
499EXPORT_SYMBOL(do_settimeofday);
500
501void do_gettimeofday (struct timeval *tv)
502{
503 unsigned long seq, nsec, usec, sec, offset;
504 do {
505 seq = read_seqbegin(&xtime_lock);
506 offset = time_interpolator_get_offset();
507 sec = xtime.tv_sec;
508 nsec = xtime.tv_nsec;
509 } while (unlikely(read_seqretry(&xtime_lock, seq)));
510
511 usec = (nsec + offset) / 1000;
512
513 while (unlikely(usec >= USEC_PER_SEC)) {
514 usec -= USEC_PER_SEC;
515 ++sec;
516 }
517
518 tv->tv_sec = sec;
519 tv->tv_usec = usec;
520}
521
522EXPORT_SYMBOL(do_gettimeofday);
523
524
525#else
526#ifndef CONFIG_GENERIC_TIME
527/*
528 * Simulate gettimeofday using do_gettimeofday which only allows a timeval
529 * and therefore only yields usec accuracy
530 */
531void getnstimeofday(struct timespec *tv)
532{
533 struct timeval x;
534
535 do_gettimeofday(&x);
536 tv->tv_sec = x.tv_sec;
537 tv->tv_nsec = x.tv_usec * NSEC_PER_USEC;
538}
539EXPORT_SYMBOL_GPL(getnstimeofday);
540#endif
541#endif
542
543/* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
544 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
545 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
546 *
547 * [For the Julian calendar (which was used in Russia before 1917,
548 * Britain & colonies before 1752, anywhere else before 1582,
549 * and is still in use by some communities) leave out the
550 * -year/100+year/400 terms, and add 10.]
551 *
552 * This algorithm was first published by Gauss (I think).
553 *
554 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
555 * machines were long is 32-bit! (However, as time_t is signed, we
556 * will already get problems at other places on 2038-01-19 03:14:08)
557 */
558unsigned long
559mktime(const unsigned int year0, const unsigned int mon0,
560 const unsigned int day, const unsigned int hour,
561 const unsigned int min, const unsigned int sec)
562{
563 unsigned int mon = mon0, year = year0;
564
565 /* 1..12 -> 11,12,1..10 */
566 if (0 >= (int) (mon -= 2)) {
567 mon += 12; /* Puts Feb last since it has leap day */
568 year -= 1;
569 }
570
571 return ((((unsigned long)
572 (year/4 - year/100 + year/400 + 367*mon/12 + day) +
573 year*365 - 719499
574 )*24 + hour /* now have hours */
575 )*60 + min /* now have minutes */
576 )*60 + sec; /* finally seconds */
577}
578
579EXPORT_SYMBOL(mktime);
580
581/**
582 * set_normalized_timespec - set timespec sec and nsec parts and normalize
583 *
584 * @ts: pointer to timespec variable to be set
585 * @sec: seconds to set
586 * @nsec: nanoseconds to set
587 *
588 * Set seconds and nanoseconds field of a timespec variable and
589 * normalize to the timespec storage format
590 *
591 * Note: The tv_nsec part is always in the range of
592 * 0 <= tv_nsec < NSEC_PER_SEC
593 * For negative values only the tv_sec field is negative !
594 */
595void set_normalized_timespec(struct timespec *ts, time_t sec, long nsec)
596{
597 while (nsec >= NSEC_PER_SEC) {
598 nsec -= NSEC_PER_SEC;
599 ++sec;
600 }
601 while (nsec < 0) {
602 nsec += NSEC_PER_SEC;
603 --sec;
604 }
605 ts->tv_sec = sec;
606 ts->tv_nsec = nsec;
607}
608
609/**
610 * ns_to_timespec - Convert nanoseconds to timespec
611 * @nsec: the nanoseconds value to be converted
612 *
613 * Returns the timespec representation of the nsec parameter.
614 */
615struct timespec ns_to_timespec(const s64 nsec)
616{
617 struct timespec ts;
618
619 if (!nsec)
620 return (struct timespec) {0, 0};
621
622 ts.tv_sec = div_long_long_rem_signed(nsec, NSEC_PER_SEC, &ts.tv_nsec);
623 if (unlikely(nsec < 0))
624 set_normalized_timespec(&ts, ts.tv_sec, ts.tv_nsec);
625
626 return ts;
627}
628
629/**
630 * ns_to_timeval - Convert nanoseconds to timeval
631 * @nsec: the nanoseconds value to be converted
632 *
633 * Returns the timeval representation of the nsec parameter.
634 */
635struct timeval ns_to_timeval(const s64 nsec)
636{
637 struct timespec ts = ns_to_timespec(nsec);
638 struct timeval tv;
639
640 tv.tv_sec = ts.tv_sec;
641 tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000;
642
643 return tv;
644}
645
646#if (BITS_PER_LONG < 64)
647u64 get_jiffies_64(void)
648{
649 unsigned long seq;
650 u64 ret;
651
652 do {
653 seq = read_seqbegin(&xtime_lock);
654 ret = jiffies_64;
655 } while (read_seqretry(&xtime_lock, seq));
656 return ret;
657}
658
659EXPORT_SYMBOL(get_jiffies_64);
660#endif
661
662EXPORT_SYMBOL(jiffies);