projects/linux·blob v2.6.12-rc5 · 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/errno.h>
33#include <linux/smp_lock.h>
34#include <linux/syscalls.h>
35#include <linux/security.h>
36#include <linux/fs.h>
37#include <linux/module.h>
38
39#include <asm/uaccess.h>
40#include <asm/unistd.h>
41
42/*
43 * The timezone where the local system is located. Used as a default by some
44 * programs who obtain this value by using gettimeofday.
45 */
46struct timezone sys_tz;
47
48EXPORT_SYMBOL(sys_tz);
49
50#ifdef __ARCH_WANT_SYS_TIME
51
52/*
53 * sys_time() can be implemented in user-level using
54 * sys_gettimeofday(). Is this for backwards compatibility? If so,
55 * why not move it into the appropriate arch directory (for those
56 * architectures that need it).
57 */
58asmlinkage long sys_time(time_t __user * tloc)
59{
60 time_t i;
61 struct timeval tv;
62
63 do_gettimeofday(&tv);
64 i = tv.tv_sec;
65
66 if (tloc) {
67 if (put_user(i,tloc))
68 i = -EFAULT;
69 }
70 return i;
71}
72
73/*
74 * sys_stime() can be implemented in user-level using
75 * sys_settimeofday(). Is this for backwards compatibility? If so,
76 * why not move it into the appropriate arch directory (for those
77 * architectures that need it).
78 */
79
80asmlinkage long sys_stime(time_t __user *tptr)
81{
82 struct timespec tv;
83 int err;
84
85 if (get_user(tv.tv_sec, tptr))
86 return -EFAULT;
87
88 tv.tv_nsec = 0;
89
90 err = security_settime(&tv, NULL);
91 if (err)
92 return err;
93
94 do_settimeofday(&tv);
95 return 0;
96}
97
98#endif /* __ARCH_WANT_SYS_TIME */
99
100asmlinkage long sys_gettimeofday(struct timeval __user *tv, struct timezone __user *tz)
101{
102 if (likely(tv != NULL)) {
103 struct timeval ktv;
104 do_gettimeofday(&ktv);
105 if (copy_to_user(tv, &ktv, sizeof(ktv)))
106 return -EFAULT;
107 }
108 if (unlikely(tz != NULL)) {
109 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
110 return -EFAULT;
111 }
112 return 0;
113}
114
115/*
116 * Adjust the time obtained from the CMOS to be UTC time instead of
117 * local time.
118 *
119 * This is ugly, but preferable to the alternatives. Otherwise we
120 * would either need to write a program to do it in /etc/rc (and risk
121 * confusion if the program gets run more than once; it would also be
122 * hard to make the program warp the clock precisely n hours) or
123 * compile in the timezone information into the kernel. Bad, bad....
124 *
125 * - TYT, 1992-01-01
126 *
127 * The best thing to do is to keep the CMOS clock in universal time (UTC)
128 * as real UNIX machines always do it. This avoids all headaches about
129 * daylight saving times and warping kernel clocks.
130 */
131inline static void warp_clock(void)
132{
133 write_seqlock_irq(&xtime_lock);
134 wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60;
135 xtime.tv_sec += sys_tz.tz_minuteswest * 60;
136 time_interpolator_reset();
137 write_sequnlock_irq(&xtime_lock);
138 clock_was_set();
139}
140
141/*
142 * In case for some reason the CMOS clock has not already been running
143 * in UTC, but in some local time: The first time we set the timezone,
144 * we will warp the clock so that it is ticking UTC time instead of
145 * local time. Presumably, if someone is setting the timezone then we
146 * are running in an environment where the programs understand about
147 * timezones. This should be done at boot time in the /etc/rc script,
148 * as soon as possible, so that the clock can be set right. Otherwise,
149 * various programs will get confused when the clock gets warped.
150 */
151
152int do_sys_settimeofday(struct timespec *tv, struct timezone *tz)
153{
154 static int firsttime = 1;
155 int error = 0;
156
157 error = security_settime(tv, tz);
158 if (error)
159 return error;
160
161 if (tz) {
162 /* SMP safe, global irq locking makes it work. */
163 sys_tz = *tz;
164 if (firsttime) {
165 firsttime = 0;
166 if (!tv)
167 warp_clock();
168 }
169 }
170 if (tv)
171 {
172 /* SMP safe, again the code in arch/foo/time.c should
173 * globally block out interrupts when it runs.
174 */
175 return do_settimeofday(tv);
176 }
177 return 0;
178}
179
180asmlinkage long sys_settimeofday(struct timeval __user *tv,
181 struct timezone __user *tz)
182{
183 struct timeval user_tv;
184 struct timespec new_ts;
185 struct timezone new_tz;
186
187 if (tv) {
188 if (copy_from_user(&user_tv, tv, sizeof(*tv)))
189 return -EFAULT;
190 new_ts.tv_sec = user_tv.tv_sec;
191 new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
192 }
193 if (tz) {
194 if (copy_from_user(&new_tz, tz, sizeof(*tz)))
195 return -EFAULT;
196 }
197
198 return do_sys_settimeofday(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
199}
200
201long pps_offset; /* pps time offset (us) */
202long pps_jitter = MAXTIME; /* time dispersion (jitter) (us) */
203
204long pps_freq; /* frequency offset (scaled ppm) */
205long pps_stabil = MAXFREQ; /* frequency dispersion (scaled ppm) */
206
207long pps_valid = PPS_VALID; /* pps signal watchdog counter */
208
209int pps_shift = PPS_SHIFT; /* interval duration (s) (shift) */
210
211long pps_jitcnt; /* jitter limit exceeded */
212long pps_calcnt; /* calibration intervals */
213long pps_errcnt; /* calibration errors */
214long pps_stbcnt; /* stability limit exceeded */
215
216/* hook for a loadable hardpps kernel module */
217void (*hardpps_ptr)(struct timeval *);
218
219/* we call this to notify the arch when the clock is being
220 * controlled. If no such arch routine, do nothing.
221 */
222void __attribute__ ((weak)) notify_arch_cmos_timer(void)
223{
224 return;
225}
226
227/* adjtimex mainly allows reading (and writing, if superuser) of
228 * kernel time-keeping variables. used by xntpd.
229 */
230int do_adjtimex(struct timex *txc)
231{
232 long ltemp, mtemp, save_adjust;
233 int result;
234
235 /* In order to modify anything, you gotta be super-user! */
236 if (txc->modes && !capable(CAP_SYS_TIME))
237 return -EPERM;
238
239 /* Now we validate the data before disabling interrupts */
240
241 if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
242 /* singleshot must not be used with any other mode bits */
243 if (txc->modes != ADJ_OFFSET_SINGLESHOT)
244 return -EINVAL;
245
246 if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
247 /* adjustment Offset limited to +- .512 seconds */
248 if (txc->offset <= - MAXPHASE || txc->offset >= MAXPHASE )
249 return -EINVAL;
250
251 /* if the quartz is off by more than 10% something is VERY wrong ! */
252 if (txc->modes & ADJ_TICK)
253 if (txc->tick < 900000/USER_HZ ||
254 txc->tick > 1100000/USER_HZ)
255 return -EINVAL;
256
257 write_seqlock_irq(&xtime_lock);
258 result = time_state; /* mostly `TIME_OK' */
259
260 /* Save for later - semantics of adjtime is to return old value */
261 save_adjust = time_next_adjust ? time_next_adjust : time_adjust;
262
263#if 0 /* STA_CLOCKERR is never set yet */
264 time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */
265#endif
266 /* If there are input parameters, then process them */
267 if (txc->modes)
268 {
269 if (txc->modes & ADJ_STATUS) /* only set allowed bits */
270 time_status = (txc->status & ~STA_RONLY) |
271 (time_status & STA_RONLY);
272
273 if (txc->modes & ADJ_FREQUENCY) { /* p. 22 */
274 if (txc->freq > MAXFREQ || txc->freq < -MAXFREQ) {
275 result = -EINVAL;
276 goto leave;
277 }
278 time_freq = txc->freq - pps_freq;
279 }
280
281 if (txc->modes & ADJ_MAXERROR) {
282 if (txc->maxerror < 0 || txc->maxerror >= NTP_PHASE_LIMIT) {
283 result = -EINVAL;
284 goto leave;
285 }
286 time_maxerror = txc->maxerror;
287 }
288
289 if (txc->modes & ADJ_ESTERROR) {
290 if (txc->esterror < 0 || txc->esterror >= NTP_PHASE_LIMIT) {
291 result = -EINVAL;
292 goto leave;
293 }
294 time_esterror = txc->esterror;
295 }
296
297 if (txc->modes & ADJ_TIMECONST) { /* p. 24 */
298 if (txc->constant < 0) { /* NTP v4 uses values > 6 */
299 result = -EINVAL;
300 goto leave;
301 }
302 time_constant = txc->constant;
303 }
304
305 if (txc->modes & ADJ_OFFSET) { /* values checked earlier */
306 if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
307 /* adjtime() is independent from ntp_adjtime() */
308 if ((time_next_adjust = txc->offset) == 0)
309 time_adjust = 0;
310 }
311 else if ( time_status & (STA_PLL | STA_PPSTIME) ) {
312 ltemp = (time_status & (STA_PPSTIME | STA_PPSSIGNAL)) ==
313 (STA_PPSTIME | STA_PPSSIGNAL) ?
314 pps_offset : txc->offset;
315
316 /*
317 * Scale the phase adjustment and
318 * clamp to the operating range.
319 */
320 if (ltemp > MAXPHASE)
321 time_offset = MAXPHASE << SHIFT_UPDATE;
322 else if (ltemp < -MAXPHASE)
323 time_offset = -(MAXPHASE << SHIFT_UPDATE);
324 else
325 time_offset = ltemp << SHIFT_UPDATE;
326
327 /*
328 * Select whether the frequency is to be controlled
329 * and in which mode (PLL or FLL). Clamp to the operating
330 * range. Ugly multiply/divide should be replaced someday.
331 */
332
333 if (time_status & STA_FREQHOLD || time_reftime == 0)
334 time_reftime = xtime.tv_sec;
335 mtemp = xtime.tv_sec - time_reftime;
336 time_reftime = xtime.tv_sec;
337 if (time_status & STA_FLL) {
338 if (mtemp >= MINSEC) {
339 ltemp = (time_offset / mtemp) << (SHIFT_USEC -
340 SHIFT_UPDATE);
341 if (ltemp < 0)
342 time_freq -= -ltemp >> SHIFT_KH;
343 else
344 time_freq += ltemp >> SHIFT_KH;
345 } else /* calibration interval too short (p. 12) */
346 result = TIME_ERROR;
347 } else { /* PLL mode */
348 if (mtemp < MAXSEC) {
349 ltemp *= mtemp;
350 if (ltemp < 0)
351 time_freq -= -ltemp >> (time_constant +
352 time_constant +
353 SHIFT_KF - SHIFT_USEC);
354 else
355 time_freq += ltemp >> (time_constant +
356 time_constant +
357 SHIFT_KF - SHIFT_USEC);
358 } else /* calibration interval too long (p. 12) */
359 result = TIME_ERROR;
360 }
361 if (time_freq > time_tolerance)
362 time_freq = time_tolerance;
363 else if (time_freq < -time_tolerance)
364 time_freq = -time_tolerance;
365 } /* STA_PLL || STA_PPSTIME */
366 } /* txc->modes & ADJ_OFFSET */
367 if (txc->modes & ADJ_TICK) {
368 tick_usec = txc->tick;
369 tick_nsec = TICK_USEC_TO_NSEC(tick_usec);
370 }
371 } /* txc->modes */
372leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0
373 || ((time_status & (STA_PPSFREQ|STA_PPSTIME)) != 0
374 && (time_status & STA_PPSSIGNAL) == 0)
375 /* p. 24, (b) */
376 || ((time_status & (STA_PPSTIME|STA_PPSJITTER))
377 == (STA_PPSTIME|STA_PPSJITTER))
378 /* p. 24, (c) */
379 || ((time_status & STA_PPSFREQ) != 0
380 && (time_status & (STA_PPSWANDER|STA_PPSERROR)) != 0))
381 /* p. 24, (d) */
382 result = TIME_ERROR;
383
384 if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
385 txc->offset = save_adjust;
386 else {
387 if (time_offset < 0)
388 txc->offset = -(-time_offset >> SHIFT_UPDATE);
389 else
390 txc->offset = time_offset >> SHIFT_UPDATE;
391 }
392 txc->freq = time_freq + pps_freq;
393 txc->maxerror = time_maxerror;
394 txc->esterror = time_esterror;
395 txc->status = time_status;
396 txc->constant = time_constant;
397 txc->precision = time_precision;
398 txc->tolerance = time_tolerance;
399 txc->tick = tick_usec;
400 txc->ppsfreq = pps_freq;
401 txc->jitter = pps_jitter >> PPS_AVG;
402 txc->shift = pps_shift;
403 txc->stabil = pps_stabil;
404 txc->jitcnt = pps_jitcnt;
405 txc->calcnt = pps_calcnt;
406 txc->errcnt = pps_errcnt;
407 txc->stbcnt = pps_stbcnt;
408 write_sequnlock_irq(&xtime_lock);
409 do_gettimeofday(&txc->time);
410 notify_arch_cmos_timer();
411 return(result);
412}
413
414asmlinkage long sys_adjtimex(struct timex __user *txc_p)
415{
416 struct timex txc; /* Local copy of parameter */
417 int ret;
418
419 /* Copy the user data space into the kernel copy
420 * structure. But bear in mind that the structures
421 * may change
422 */
423 if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
424 return -EFAULT;
425 ret = do_adjtimex(&txc);
426 return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
427}
428
429inline struct timespec current_kernel_time(void)
430{
431 struct timespec now;
432 unsigned long seq;
433
434 do {
435 seq = read_seqbegin(&xtime_lock);
436
437 now = xtime;
438 } while (read_seqretry(&xtime_lock, seq));
439
440 return now;
441}
442
443EXPORT_SYMBOL(current_kernel_time);
444
445/**
446 * current_fs_time - Return FS time
447 * @sb: Superblock.
448 *
449 * Return the current time truncated to the time granuality supported by
450 * the fs.
451 */
452struct timespec current_fs_time(struct super_block *sb)
453{
454 struct timespec now = current_kernel_time();
455 return timespec_trunc(now, sb->s_time_gran);
456}
457EXPORT_SYMBOL(current_fs_time);
458
459/**
460 * timespec_trunc - Truncate timespec to a granuality
461 * @t: Timespec
462 * @gran: Granuality in ns.
463 *
464 * Truncate a timespec to a granuality. gran must be smaller than a second.
465 * Always rounds down.
466 *
467 * This function should be only used for timestamps returned by
468 * current_kernel_time() or CURRENT_TIME, not with do_gettimeofday() because
469 * it doesn't handle the better resolution of the later.
470 */
471struct timespec timespec_trunc(struct timespec t, unsigned gran)
472{
473 /*
474 * Division is pretty slow so avoid it for common cases.
475 * Currently current_kernel_time() never returns better than
476 * jiffies resolution. Exploit that.
477 */
478 if (gran <= jiffies_to_usecs(1) * 1000) {
479 /* nothing */
480 } else if (gran == 1000000000) {
481 t.tv_nsec = 0;
482 } else {
483 t.tv_nsec -= t.tv_nsec % gran;
484 }
485 return t;
486}
487EXPORT_SYMBOL(timespec_trunc);
488
489#ifdef CONFIG_TIME_INTERPOLATION
490void getnstimeofday (struct timespec *tv)
491{
492 unsigned long seq,sec,nsec;
493
494 do {
495 seq = read_seqbegin(&xtime_lock);
496 sec = xtime.tv_sec;
497 nsec = xtime.tv_nsec+time_interpolator_get_offset();
498 } while (unlikely(read_seqretry(&xtime_lock, seq)));
499
500 while (unlikely(nsec >= NSEC_PER_SEC)) {
501 nsec -= NSEC_PER_SEC;
502 ++sec;
503 }
504 tv->tv_sec = sec;
505 tv->tv_nsec = nsec;
506}
507EXPORT_SYMBOL_GPL(getnstimeofday);
508
509int do_settimeofday (struct timespec *tv)
510{
511 time_t wtm_sec, sec = tv->tv_sec;
512 long wtm_nsec, nsec = tv->tv_nsec;
513
514 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
515 return -EINVAL;
516
517 write_seqlock_irq(&xtime_lock);
518 {
519 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
520 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
521
522 set_normalized_timespec(&xtime, sec, nsec);
523 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
524
525 time_adjust = 0; /* stop active adjtime() */
526 time_status |= STA_UNSYNC;
527 time_maxerror = NTP_PHASE_LIMIT;
528 time_esterror = NTP_PHASE_LIMIT;
529 time_interpolator_reset();
530 }
531 write_sequnlock_irq(&xtime_lock);
532 clock_was_set();
533 return 0;
534}
535
536void do_gettimeofday (struct timeval *tv)
537{
538 unsigned long seq, nsec, usec, sec, offset;
539 do {
540 seq = read_seqbegin(&xtime_lock);
541 offset = time_interpolator_get_offset();
542 sec = xtime.tv_sec;
543 nsec = xtime.tv_nsec;
544 } while (unlikely(read_seqretry(&xtime_lock, seq)));
545
546 usec = (nsec + offset) / 1000;
547
548 while (unlikely(usec >= USEC_PER_SEC)) {
549 usec -= USEC_PER_SEC;
550 ++sec;
551 }
552
553 tv->tv_sec = sec;
554 tv->tv_usec = usec;
555}
556
557EXPORT_SYMBOL(do_gettimeofday);
558
559
560#else
561/*
562 * Simulate gettimeofday using do_gettimeofday which only allows a timeval
563 * and therefore only yields usec accuracy
564 */
565void getnstimeofday(struct timespec *tv)
566{
567 struct timeval x;
568
569 do_gettimeofday(&x);
570 tv->tv_sec = x.tv_sec;
571 tv->tv_nsec = x.tv_usec * NSEC_PER_USEC;
572}
573#endif
574
575#if (BITS_PER_LONG < 64)
576u64 get_jiffies_64(void)
577{
578 unsigned long seq;
579 u64 ret;
580
581 do {
582 seq = read_seqbegin(&xtime_lock);
583 ret = jiffies_64;
584 } while (read_seqretry(&xtime_lock, seq));
585 return ret;
586}
587
588EXPORT_SYMBOL(get_jiffies_64);
589#endif
590
591EXPORT_SYMBOL(jiffies);