[PATCH] WorkStruct: Use direct assignment rather than cmpxchg()
[linux-block.git] / kernel / time.c
CommitLineData
1da177e4
LT
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>
c59ede7b 32#include <linux/capability.h>
1da177e4
LT
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 */
77933d72 132static inline void warp_clock(void)
1da177e4
LT
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
951069e3 158 if (tv && !timespec_valid(tv))
718bcceb
TG
159 return -EINVAL;
160
1da177e4
LT
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
1da177e4
LT
205asmlinkage long sys_adjtimex(struct timex __user *txc_p)
206{
207 struct timex txc; /* Local copy of parameter */
208 int ret;
209
210 /* Copy the user data space into the kernel copy
211 * structure. But bear in mind that the structures
212 * may change
213 */
214 if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
215 return -EFAULT;
216 ret = do_adjtimex(&txc);
217 return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
218}
219
220inline struct timespec current_kernel_time(void)
221{
222 struct timespec now;
223 unsigned long seq;
224
225 do {
226 seq = read_seqbegin(&xtime_lock);
227
228 now = xtime;
229 } while (read_seqretry(&xtime_lock, seq));
230
231 return now;
232}
233
234EXPORT_SYMBOL(current_kernel_time);
235
236/**
237 * current_fs_time - Return FS time
238 * @sb: Superblock.
239 *
8ba8e95e 240 * Return the current time truncated to the time granularity supported by
1da177e4
LT
241 * the fs.
242 */
243struct timespec current_fs_time(struct super_block *sb)
244{
245 struct timespec now = current_kernel_time();
246 return timespec_trunc(now, sb->s_time_gran);
247}
248EXPORT_SYMBOL(current_fs_time);
249
250/**
8ba8e95e 251 * timespec_trunc - Truncate timespec to a granularity
1da177e4 252 * @t: Timespec
8ba8e95e 253 * @gran: Granularity in ns.
1da177e4 254 *
8ba8e95e 255 * Truncate a timespec to a granularity. gran must be smaller than a second.
1da177e4
LT
256 * Always rounds down.
257 *
258 * This function should be only used for timestamps returned by
259 * current_kernel_time() or CURRENT_TIME, not with do_gettimeofday() because
260 * it doesn't handle the better resolution of the later.
261 */
262struct timespec timespec_trunc(struct timespec t, unsigned gran)
263{
264 /*
265 * Division is pretty slow so avoid it for common cases.
266 * Currently current_kernel_time() never returns better than
267 * jiffies resolution. Exploit that.
268 */
269 if (gran <= jiffies_to_usecs(1) * 1000) {
270 /* nothing */
271 } else if (gran == 1000000000) {
272 t.tv_nsec = 0;
273 } else {
274 t.tv_nsec -= t.tv_nsec % gran;
275 }
276 return t;
277}
278EXPORT_SYMBOL(timespec_trunc);
279
280#ifdef CONFIG_TIME_INTERPOLATION
281void getnstimeofday (struct timespec *tv)
282{
283 unsigned long seq,sec,nsec;
284
285 do {
286 seq = read_seqbegin(&xtime_lock);
287 sec = xtime.tv_sec;
288 nsec = xtime.tv_nsec+time_interpolator_get_offset();
289 } while (unlikely(read_seqretry(&xtime_lock, seq)));
290
291 while (unlikely(nsec >= NSEC_PER_SEC)) {
292 nsec -= NSEC_PER_SEC;
293 ++sec;
294 }
295 tv->tv_sec = sec;
296 tv->tv_nsec = nsec;
297}
298EXPORT_SYMBOL_GPL(getnstimeofday);
299
300int do_settimeofday (struct timespec *tv)
301{
302 time_t wtm_sec, sec = tv->tv_sec;
303 long wtm_nsec, nsec = tv->tv_nsec;
304
305 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
306 return -EINVAL;
307
308 write_seqlock_irq(&xtime_lock);
309 {
1da177e4
LT
310 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
311 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
312
313 set_normalized_timespec(&xtime, sec, nsec);
314 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
315
316 time_adjust = 0; /* stop active adjtime() */
317 time_status |= STA_UNSYNC;
318 time_maxerror = NTP_PHASE_LIMIT;
319 time_esterror = NTP_PHASE_LIMIT;
320 time_interpolator_reset();
321 }
322 write_sequnlock_irq(&xtime_lock);
323 clock_was_set();
324 return 0;
325}
943eae03 326EXPORT_SYMBOL(do_settimeofday);
1da177e4
LT
327
328void do_gettimeofday (struct timeval *tv)
329{
330 unsigned long seq, nsec, usec, sec, offset;
331 do {
332 seq = read_seqbegin(&xtime_lock);
333 offset = time_interpolator_get_offset();
334 sec = xtime.tv_sec;
335 nsec = xtime.tv_nsec;
336 } while (unlikely(read_seqretry(&xtime_lock, seq)));
337
338 usec = (nsec + offset) / 1000;
339
340 while (unlikely(usec >= USEC_PER_SEC)) {
341 usec -= USEC_PER_SEC;
342 ++sec;
343 }
344
345 tv->tv_sec = sec;
346 tv->tv_usec = usec;
347}
348
349EXPORT_SYMBOL(do_gettimeofday);
350
351
352#else
cf3c769b 353#ifndef CONFIG_GENERIC_TIME
1da177e4
LT
354/*
355 * Simulate gettimeofday using do_gettimeofday which only allows a timeval
356 * and therefore only yields usec accuracy
357 */
358void getnstimeofday(struct timespec *tv)
359{
360 struct timeval x;
361
362 do_gettimeofday(&x);
363 tv->tv_sec = x.tv_sec;
364 tv->tv_nsec = x.tv_usec * NSEC_PER_USEC;
365}
c6ecf7ed 366EXPORT_SYMBOL_GPL(getnstimeofday);
1da177e4 367#endif
cf3c769b 368#endif
1da177e4 369
753be622
TG
370/* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
371 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
372 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
373 *
374 * [For the Julian calendar (which was used in Russia before 1917,
375 * Britain & colonies before 1752, anywhere else before 1582,
376 * and is still in use by some communities) leave out the
377 * -year/100+year/400 terms, and add 10.]
378 *
379 * This algorithm was first published by Gauss (I think).
380 *
381 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
382 * machines were long is 32-bit! (However, as time_t is signed, we
383 * will already get problems at other places on 2038-01-19 03:14:08)
384 */
385unsigned long
f4818900
IM
386mktime(const unsigned int year0, const unsigned int mon0,
387 const unsigned int day, const unsigned int hour,
388 const unsigned int min, const unsigned int sec)
753be622 389{
f4818900
IM
390 unsigned int mon = mon0, year = year0;
391
392 /* 1..12 -> 11,12,1..10 */
393 if (0 >= (int) (mon -= 2)) {
394 mon += 12; /* Puts Feb last since it has leap day */
753be622
TG
395 year -= 1;
396 }
397
398 return ((((unsigned long)
399 (year/4 - year/100 + year/400 + 367*mon/12 + day) +
400 year*365 - 719499
401 )*24 + hour /* now have hours */
402 )*60 + min /* now have minutes */
403 )*60 + sec; /* finally seconds */
404}
405
199e7056
AM
406EXPORT_SYMBOL(mktime);
407
753be622
TG
408/**
409 * set_normalized_timespec - set timespec sec and nsec parts and normalize
410 *
411 * @ts: pointer to timespec variable to be set
412 * @sec: seconds to set
413 * @nsec: nanoseconds to set
414 *
415 * Set seconds and nanoseconds field of a timespec variable and
416 * normalize to the timespec storage format
417 *
418 * Note: The tv_nsec part is always in the range of
419 * 0 <= tv_nsec < NSEC_PER_SEC
420 * For negative values only the tv_sec field is negative !
421 */
f4818900 422void set_normalized_timespec(struct timespec *ts, time_t sec, long nsec)
753be622
TG
423{
424 while (nsec >= NSEC_PER_SEC) {
425 nsec -= NSEC_PER_SEC;
426 ++sec;
427 }
428 while (nsec < 0) {
429 nsec += NSEC_PER_SEC;
430 --sec;
431 }
432 ts->tv_sec = sec;
433 ts->tv_nsec = nsec;
434}
435
f8f46da3
TG
436/**
437 * ns_to_timespec - Convert nanoseconds to timespec
438 * @nsec: the nanoseconds value to be converted
439 *
440 * Returns the timespec representation of the nsec parameter.
441 */
df869b63 442struct timespec ns_to_timespec(const s64 nsec)
f8f46da3
TG
443{
444 struct timespec ts;
445
88fc3897
GA
446 if (!nsec)
447 return (struct timespec) {0, 0};
448
449 ts.tv_sec = div_long_long_rem_signed(nsec, NSEC_PER_SEC, &ts.tv_nsec);
450 if (unlikely(nsec < 0))
451 set_normalized_timespec(&ts, ts.tv_sec, ts.tv_nsec);
f8f46da3
TG
452
453 return ts;
454}
455
456/**
457 * ns_to_timeval - Convert nanoseconds to timeval
458 * @nsec: the nanoseconds value to be converted
459 *
460 * Returns the timeval representation of the nsec parameter.
461 */
df869b63 462struct timeval ns_to_timeval(const s64 nsec)
f8f46da3
TG
463{
464 struct timespec ts = ns_to_timespec(nsec);
465 struct timeval tv;
466
467 tv.tv_sec = ts.tv_sec;
468 tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000;
469
470 return tv;
471}
472
1da177e4
LT
473#if (BITS_PER_LONG < 64)
474u64 get_jiffies_64(void)
475{
476 unsigned long seq;
477 u64 ret;
478
479 do {
480 seq = read_seqbegin(&xtime_lock);
481 ret = jiffies_64;
482 } while (read_seqretry(&xtime_lock, seq));
483 return ret;
484}
485
486EXPORT_SYMBOL(get_jiffies_64);
487#endif
488
489EXPORT_SYMBOL(jiffies);