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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Daniel Walker6fa6c3b2007-10-18 03:06:03 -070012 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070013 * 1993-09-02 Philip Gladstone
Daniel Walker6fa6c3b2007-10-18 03:06:03 -070014 * Created file with time related functions from sched.c and adjtimex()
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 * 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>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080032#include <linux/capability.h>
Tony Breeds2c622142007-10-18 03:04:57 -070033#include <linux/clocksource.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070034#include <linux/errno.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <linux/syscalls.h>
36#include <linux/security.h>
37#include <linux/fs.h>
Robert P. J. Day1aeb2722008-04-29 00:59:25 -070038#include <linux/slab.h>
Roman Zippel71abb3a2008-05-01 04:34:26 -070039#include <linux/math64.h>
Paul Mackerrase3d5a272009-01-06 14:41:02 -080040#include <linux/ptrace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070041
42#include <asm/uaccess.h>
43#include <asm/unistd.h>
44
H. Peter Anvinbdc80782008-02-08 04:21:26 -080045#include "timeconst.h"
46
Daniel Walker6fa6c3b2007-10-18 03:06:03 -070047/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 * The timezone where the local system is located. Used as a default by some
49 * programs who obtain this value by using gettimeofday.
50 */
51struct timezone sys_tz;
52
53EXPORT_SYMBOL(sys_tz);
54
55#ifdef __ARCH_WANT_SYS_TIME
56
57/*
58 * sys_time() can be implemented in user-level using
59 * sys_gettimeofday(). Is this for backwards compatibility? If so,
60 * why not move it into the appropriate arch directory (for those
61 * architectures that need it).
62 */
Heiko Carstens58fd3aa2009-01-14 14:14:03 +010063SYSCALL_DEFINE1(time, time_t __user *, tloc)
Linus Torvalds1da177e2005-04-16 15:20:36 -070064{
Ingo Molnarf20bf612007-10-16 16:09:20 +020065 time_t i = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -070066
67 if (tloc) {
Linus Torvalds20082202007-07-20 13:28:54 -070068 if (put_user(i,tloc))
Paul Mackerrase3d5a272009-01-06 14:41:02 -080069 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070070 }
Paul Mackerrase3d5a272009-01-06 14:41:02 -080071 force_successful_syscall_return();
Linus Torvalds1da177e2005-04-16 15:20:36 -070072 return i;
73}
74
75/*
76 * sys_stime() can be implemented in user-level using
77 * sys_settimeofday(). Is this for backwards compatibility? If so,
78 * why not move it into the appropriate arch directory (for those
79 * architectures that need it).
80 */
Daniel Walker6fa6c3b2007-10-18 03:06:03 -070081
Heiko Carstens58fd3aa2009-01-14 14:14:03 +010082SYSCALL_DEFINE1(stime, time_t __user *, tptr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070083{
84 struct timespec tv;
85 int err;
86
87 if (get_user(tv.tv_sec, tptr))
88 return -EFAULT;
89
90 tv.tv_nsec = 0;
91
92 err = security_settime(&tv, NULL);
93 if (err)
94 return err;
95
96 do_settimeofday(&tv);
97 return 0;
98}
99
100#endif /* __ARCH_WANT_SYS_TIME */
101
Heiko Carstens58fd3aa2009-01-14 14:14:03 +0100102SYSCALL_DEFINE2(gettimeofday, struct timeval __user *, tv,
103 struct timezone __user *, tz)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104{
105 if (likely(tv != NULL)) {
106 struct timeval ktv;
107 do_gettimeofday(&ktv);
108 if (copy_to_user(tv, &ktv, sizeof(ktv)))
109 return -EFAULT;
110 }
111 if (unlikely(tz != NULL)) {
112 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
113 return -EFAULT;
114 }
115 return 0;
116}
117
118/*
119 * Adjust the time obtained from the CMOS to be UTC time instead of
120 * local time.
Daniel Walker6fa6c3b2007-10-18 03:06:03 -0700121 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 * This is ugly, but preferable to the alternatives. Otherwise we
123 * would either need to write a program to do it in /etc/rc (and risk
Daniel Walker6fa6c3b2007-10-18 03:06:03 -0700124 * confusion if the program gets run more than once; it would also be
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 * hard to make the program warp the clock precisely n hours) or
126 * compile in the timezone information into the kernel. Bad, bad....
127 *
H. Peter Anvinbdc80782008-02-08 04:21:26 -0800128 * - TYT, 1992-01-01
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 *
130 * The best thing to do is to keep the CMOS clock in universal time (UTC)
131 * as real UNIX machines always do it. This avoids all headaches about
132 * daylight saving times and warping kernel clocks.
133 */
Jesper Juhl77933d72005-07-27 11:46:09 -0700134static inline void warp_clock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135{
136 write_seqlock_irq(&xtime_lock);
137 wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60;
138 xtime.tv_sec += sys_tz.tz_minuteswest * 60;
Thomas Gleixner1001d0a2008-02-01 17:45:13 +0100139 update_xtime_cache(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140 write_sequnlock_irq(&xtime_lock);
141 clock_was_set();
142}
143
144/*
145 * In case for some reason the CMOS clock has not already been running
146 * in UTC, but in some local time: The first time we set the timezone,
147 * we will warp the clock so that it is ticking UTC time instead of
148 * local time. Presumably, if someone is setting the timezone then we
149 * are running in an environment where the programs understand about
150 * timezones. This should be done at boot time in the /etc/rc script,
151 * as soon as possible, so that the clock can be set right. Otherwise,
152 * various programs will get confused when the clock gets warped.
153 */
154
155int do_sys_settimeofday(struct timespec *tv, struct timezone *tz)
156{
157 static int firsttime = 1;
158 int error = 0;
159
Linus Torvalds951069e2006-01-31 10:16:55 -0800160 if (tv && !timespec_valid(tv))
Thomas Gleixner718bcce2006-01-09 20:52:29 -0800161 return -EINVAL;
162
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 error = security_settime(tv, tz);
164 if (error)
165 return error;
166
167 if (tz) {
168 /* SMP safe, global irq locking makes it work. */
169 sys_tz = *tz;
Tony Breeds2c622142007-10-18 03:04:57 -0700170 update_vsyscall_tz();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 if (firsttime) {
172 firsttime = 0;
173 if (!tv)
174 warp_clock();
175 }
176 }
177 if (tv)
178 {
179 /* SMP safe, again the code in arch/foo/time.c should
180 * globally block out interrupts when it runs.
181 */
182 return do_settimeofday(tv);
183 }
184 return 0;
185}
186
Heiko Carstens58fd3aa2009-01-14 14:14:03 +0100187SYSCALL_DEFINE2(settimeofday, struct timeval __user *, tv,
188 struct timezone __user *, tz)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189{
190 struct timeval user_tv;
191 struct timespec new_ts;
192 struct timezone new_tz;
193
194 if (tv) {
195 if (copy_from_user(&user_tv, tv, sizeof(*tv)))
196 return -EFAULT;
197 new_ts.tv_sec = user_tv.tv_sec;
198 new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
199 }
200 if (tz) {
201 if (copy_from_user(&new_tz, tz, sizeof(*tz)))
202 return -EFAULT;
203 }
204
205 return do_sys_settimeofday(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
206}
207
Heiko Carstens58fd3aa2009-01-14 14:14:03 +0100208SYSCALL_DEFINE1(adjtimex, struct timex __user *, txc_p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209{
210 struct timex txc; /* Local copy of parameter */
211 int ret;
212
213 /* Copy the user data space into the kernel copy
214 * structure. But bear in mind that the structures
215 * may change
216 */
217 if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
218 return -EFAULT;
219 ret = do_adjtimex(&txc);
220 return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
221}
222
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223/**
224 * current_fs_time - Return FS time
225 * @sb: Superblock.
226 *
Kalin KOZHUHAROV8ba8e952006-04-01 01:41:22 +0200227 * Return the current time truncated to the time granularity supported by
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 * the fs.
229 */
230struct timespec current_fs_time(struct super_block *sb)
231{
232 struct timespec now = current_kernel_time();
233 return timespec_trunc(now, sb->s_time_gran);
234}
235EXPORT_SYMBOL(current_fs_time);
236
Eric Dumazet753e9c52007-05-08 00:25:32 -0700237/*
238 * Convert jiffies to milliseconds and back.
239 *
240 * Avoid unnecessary multiplications/divisions in the
241 * two most common HZ cases:
242 */
243unsigned int inline jiffies_to_msecs(const unsigned long j)
244{
245#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
246 return (MSEC_PER_SEC / HZ) * j;
247#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
248 return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
249#else
H. Peter Anvinbdc80782008-02-08 04:21:26 -0800250# if BITS_PER_LONG == 32
H. Peter Anvinb9095fd2008-05-02 16:18:42 -0700251 return (HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32;
H. Peter Anvinbdc80782008-02-08 04:21:26 -0800252# else
253 return (j * HZ_TO_MSEC_NUM) / HZ_TO_MSEC_DEN;
254# endif
Eric Dumazet753e9c52007-05-08 00:25:32 -0700255#endif
256}
257EXPORT_SYMBOL(jiffies_to_msecs);
258
259unsigned int inline jiffies_to_usecs(const unsigned long j)
260{
261#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
262 return (USEC_PER_SEC / HZ) * j;
263#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
264 return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC);
265#else
H. Peter Anvinbdc80782008-02-08 04:21:26 -0800266# if BITS_PER_LONG == 32
H. Peter Anvinb9095fd2008-05-02 16:18:42 -0700267 return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32;
H. Peter Anvinbdc80782008-02-08 04:21:26 -0800268# else
269 return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN;
270# endif
Eric Dumazet753e9c52007-05-08 00:25:32 -0700271#endif
272}
273EXPORT_SYMBOL(jiffies_to_usecs);
274
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275/**
Kalin KOZHUHAROV8ba8e952006-04-01 01:41:22 +0200276 * timespec_trunc - Truncate timespec to a granularity
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277 * @t: Timespec
Kalin KOZHUHAROV8ba8e952006-04-01 01:41:22 +0200278 * @gran: Granularity in ns.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 *
Kalin KOZHUHAROV8ba8e952006-04-01 01:41:22 +0200280 * Truncate a timespec to a granularity. gran must be smaller than a second.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 * Always rounds down.
282 *
283 * This function should be only used for timestamps returned by
284 * current_kernel_time() or CURRENT_TIME, not with do_gettimeofday() because
Li Zefan3eb05672008-02-08 04:19:25 -0800285 * it doesn't handle the better resolution of the latter.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 */
287struct timespec timespec_trunc(struct timespec t, unsigned gran)
288{
289 /*
290 * Division is pretty slow so avoid it for common cases.
291 * Currently current_kernel_time() never returns better than
292 * jiffies resolution. Exploit that.
293 */
294 if (gran <= jiffies_to_usecs(1) * 1000) {
295 /* nothing */
296 } else if (gran == 1000000000) {
297 t.tv_nsec = 0;
298 } else {
299 t.tv_nsec -= t.tv_nsec % gran;
300 }
301 return t;
302}
303EXPORT_SYMBOL(timespec_trunc);
304
john stultzcf3c7692006-06-26 00:25:08 -0700305#ifndef CONFIG_GENERIC_TIME
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306/*
307 * Simulate gettimeofday using do_gettimeofday which only allows a timeval
308 * and therefore only yields usec accuracy
309 */
310void getnstimeofday(struct timespec *tv)
311{
312 struct timeval x;
313
314 do_gettimeofday(&x);
315 tv->tv_sec = x.tv_sec;
316 tv->tv_nsec = x.tv_usec * NSEC_PER_USEC;
317}
Takashi Iwaic6ecf7e2005-10-14 15:59:03 -0700318EXPORT_SYMBOL_GPL(getnstimeofday);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319#endif
320
Thomas Gleixner753be622006-01-09 20:52:22 -0800321/* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
322 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
323 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
324 *
325 * [For the Julian calendar (which was used in Russia before 1917,
326 * Britain & colonies before 1752, anywhere else before 1582,
327 * and is still in use by some communities) leave out the
328 * -year/100+year/400 terms, and add 10.]
329 *
330 * This algorithm was first published by Gauss (I think).
331 *
332 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
Li Zefan3eb05672008-02-08 04:19:25 -0800333 * machines where long is 32-bit! (However, as time_t is signed, we
Thomas Gleixner753be622006-01-09 20:52:22 -0800334 * will already get problems at other places on 2038-01-19 03:14:08)
335 */
336unsigned long
Ingo Molnarf4818902006-01-09 20:52:23 -0800337mktime(const unsigned int year0, const unsigned int mon0,
338 const unsigned int day, const unsigned int hour,
339 const unsigned int min, const unsigned int sec)
Thomas Gleixner753be622006-01-09 20:52:22 -0800340{
Ingo Molnarf4818902006-01-09 20:52:23 -0800341 unsigned int mon = mon0, year = year0;
342
343 /* 1..12 -> 11,12,1..10 */
344 if (0 >= (int) (mon -= 2)) {
345 mon += 12; /* Puts Feb last since it has leap day */
Thomas Gleixner753be622006-01-09 20:52:22 -0800346 year -= 1;
347 }
348
349 return ((((unsigned long)
350 (year/4 - year/100 + year/400 + 367*mon/12 + day) +
351 year*365 - 719499
352 )*24 + hour /* now have hours */
353 )*60 + min /* now have minutes */
354 )*60 + sec; /* finally seconds */
355}
356
Andrew Morton199e7052006-01-09 20:52:24 -0800357EXPORT_SYMBOL(mktime);
358
Thomas Gleixner753be622006-01-09 20:52:22 -0800359/**
360 * set_normalized_timespec - set timespec sec and nsec parts and normalize
361 *
362 * @ts: pointer to timespec variable to be set
363 * @sec: seconds to set
364 * @nsec: nanoseconds to set
365 *
366 * Set seconds and nanoseconds field of a timespec variable and
367 * normalize to the timespec storage format
368 *
369 * Note: The tv_nsec part is always in the range of
H. Peter Anvinbdc80782008-02-08 04:21:26 -0800370 * 0 <= tv_nsec < NSEC_PER_SEC
Thomas Gleixner753be622006-01-09 20:52:22 -0800371 * For negative values only the tv_sec field is negative !
372 */
Ingo Molnarf4818902006-01-09 20:52:23 -0800373void set_normalized_timespec(struct timespec *ts, time_t sec, long nsec)
Thomas Gleixner753be622006-01-09 20:52:22 -0800374{
375 while (nsec >= NSEC_PER_SEC) {
376 nsec -= NSEC_PER_SEC;
377 ++sec;
378 }
379 while (nsec < 0) {
380 nsec += NSEC_PER_SEC;
381 --sec;
382 }
383 ts->tv_sec = sec;
384 ts->tv_nsec = nsec;
385}
YOSHIFUJI Hideaki7c3f9442008-04-21 19:45:12 -0700386EXPORT_SYMBOL(set_normalized_timespec);
Thomas Gleixner753be622006-01-09 20:52:22 -0800387
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800388/**
389 * ns_to_timespec - Convert nanoseconds to timespec
390 * @nsec: the nanoseconds value to be converted
391 *
392 * Returns the timespec representation of the nsec parameter.
393 */
Roman Zippeldf869b62006-03-26 01:38:11 -0800394struct timespec ns_to_timespec(const s64 nsec)
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800395{
396 struct timespec ts;
Roman Zippelf8bd2252008-05-01 04:34:31 -0700397 s32 rem;
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800398
George Anzinger88fc3892006-02-03 03:04:20 -0800399 if (!nsec)
400 return (struct timespec) {0, 0};
401
Roman Zippelf8bd2252008-05-01 04:34:31 -0700402 ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
403 if (unlikely(rem < 0)) {
404 ts.tv_sec--;
405 rem += NSEC_PER_SEC;
406 }
407 ts.tv_nsec = rem;
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800408
409 return ts;
410}
Stephen Hemminger85795d62007-03-24 21:35:33 -0700411EXPORT_SYMBOL(ns_to_timespec);
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800412
413/**
414 * ns_to_timeval - Convert nanoseconds to timeval
415 * @nsec: the nanoseconds value to be converted
416 *
417 * Returns the timeval representation of the nsec parameter.
418 */
Roman Zippeldf869b62006-03-26 01:38:11 -0800419struct timeval ns_to_timeval(const s64 nsec)
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800420{
421 struct timespec ts = ns_to_timespec(nsec);
422 struct timeval tv;
423
424 tv.tv_sec = ts.tv_sec;
425 tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000;
426
427 return tv;
428}
Eric Dumazetb7aa0bf2007-04-19 16:16:32 -0700429EXPORT_SYMBOL(ns_to_timeval);
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800430
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800431/*
Ingo Molnar41cf5442007-02-16 01:27:28 -0800432 * When we convert to jiffies then we interpret incoming values
433 * the following way:
434 *
435 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
436 *
437 * - 'too large' values [that would result in larger than
438 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
439 *
440 * - all other values are converted to jiffies by either multiplying
441 * the input value by a factor or dividing it with a factor
442 *
443 * We must also be careful about 32-bit overflows.
444 */
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800445unsigned long msecs_to_jiffies(const unsigned int m)
446{
Ingo Molnar41cf5442007-02-16 01:27:28 -0800447 /*
448 * Negative value, means infinite timeout:
449 */
450 if ((int)m < 0)
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800451 return MAX_JIFFY_OFFSET;
Ingo Molnar41cf5442007-02-16 01:27:28 -0800452
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800453#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
Ingo Molnar41cf5442007-02-16 01:27:28 -0800454 /*
455 * HZ is equal to or smaller than 1000, and 1000 is a nice
456 * round multiple of HZ, divide with the factor between them,
457 * but round upwards:
458 */
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800459 return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);
460#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
Ingo Molnar41cf5442007-02-16 01:27:28 -0800461 /*
462 * HZ is larger than 1000, and HZ is a nice round multiple of
463 * 1000 - simply multiply with the factor between them.
464 *
465 * But first make sure the multiplication result cannot
466 * overflow:
467 */
468 if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
469 return MAX_JIFFY_OFFSET;
470
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800471 return m * (HZ / MSEC_PER_SEC);
472#else
Ingo Molnar41cf5442007-02-16 01:27:28 -0800473 /*
474 * Generic case - multiply, round and divide. But first
475 * check that if we are doing a net multiplication, that
H. Peter Anvinbdc80782008-02-08 04:21:26 -0800476 * we wouldn't overflow:
Ingo Molnar41cf5442007-02-16 01:27:28 -0800477 */
478 if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
479 return MAX_JIFFY_OFFSET;
480
H. Peter Anvinb9095fd2008-05-02 16:18:42 -0700481 return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32)
H. Peter Anvinbdc80782008-02-08 04:21:26 -0800482 >> MSEC_TO_HZ_SHR32;
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800483#endif
484}
485EXPORT_SYMBOL(msecs_to_jiffies);
486
487unsigned long usecs_to_jiffies(const unsigned int u)
488{
489 if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
490 return MAX_JIFFY_OFFSET;
491#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
492 return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ);
493#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
494 return u * (HZ / USEC_PER_SEC);
495#else
H. Peter Anvinb9095fd2008-05-02 16:18:42 -0700496 return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32)
H. Peter Anvinbdc80782008-02-08 04:21:26 -0800497 >> USEC_TO_HZ_SHR32;
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800498#endif
499}
500EXPORT_SYMBOL(usecs_to_jiffies);
501
502/*
503 * The TICK_NSEC - 1 rounds up the value to the next resolution. Note
504 * that a remainder subtract here would not do the right thing as the
505 * resolution values don't fall on second boundries. I.e. the line:
506 * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding.
507 *
508 * Rather, we just shift the bits off the right.
509 *
510 * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
511 * value to a scaled second value.
512 */
513unsigned long
514timespec_to_jiffies(const struct timespec *value)
515{
516 unsigned long sec = value->tv_sec;
517 long nsec = value->tv_nsec + TICK_NSEC - 1;
518
519 if (sec >= MAX_SEC_IN_JIFFIES){
520 sec = MAX_SEC_IN_JIFFIES;
521 nsec = 0;
522 }
523 return (((u64)sec * SEC_CONVERSION) +
524 (((u64)nsec * NSEC_CONVERSION) >>
525 (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
526
527}
528EXPORT_SYMBOL(timespec_to_jiffies);
529
530void
531jiffies_to_timespec(const unsigned long jiffies, struct timespec *value)
532{
533 /*
534 * Convert jiffies to nanoseconds and separate with
535 * one divide.
536 */
Roman Zippelf8bd2252008-05-01 04:34:31 -0700537 u32 rem;
538 value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
539 NSEC_PER_SEC, &rem);
540 value->tv_nsec = rem;
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800541}
542EXPORT_SYMBOL(jiffies_to_timespec);
543
544/* Same for "timeval"
545 *
546 * Well, almost. The problem here is that the real system resolution is
547 * in nanoseconds and the value being converted is in micro seconds.
548 * Also for some machines (those that use HZ = 1024, in-particular),
549 * there is a LARGE error in the tick size in microseconds.
550
551 * The solution we use is to do the rounding AFTER we convert the
552 * microsecond part. Thus the USEC_ROUND, the bits to be shifted off.
553 * Instruction wise, this should cost only an additional add with carry
554 * instruction above the way it was done above.
555 */
556unsigned long
557timeval_to_jiffies(const struct timeval *value)
558{
559 unsigned long sec = value->tv_sec;
560 long usec = value->tv_usec;
561
562 if (sec >= MAX_SEC_IN_JIFFIES){
563 sec = MAX_SEC_IN_JIFFIES;
564 usec = 0;
565 }
566 return (((u64)sec * SEC_CONVERSION) +
567 (((u64)usec * USEC_CONVERSION + USEC_ROUND) >>
568 (USEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
569}
Thomas Bittermann456a09d2007-04-04 22:20:54 +0200570EXPORT_SYMBOL(timeval_to_jiffies);
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800571
572void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value)
573{
574 /*
575 * Convert jiffies to nanoseconds and separate with
576 * one divide.
577 */
Roman Zippelf8bd2252008-05-01 04:34:31 -0700578 u32 rem;
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800579
Roman Zippelf8bd2252008-05-01 04:34:31 -0700580 value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
581 NSEC_PER_SEC, &rem);
582 value->tv_usec = rem / NSEC_PER_USEC;
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800583}
Thomas Bittermann456a09d2007-04-04 22:20:54 +0200584EXPORT_SYMBOL(jiffies_to_timeval);
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800585
586/*
587 * Convert jiffies/jiffies_64 to clock_t and back.
588 */
589clock_t jiffies_to_clock_t(long x)
590{
591#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
David Fries6ffc7872008-02-06 01:38:04 -0800592# if HZ < USER_HZ
593 return x * (USER_HZ / HZ);
594# else
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800595 return x / (HZ / USER_HZ);
David Fries6ffc7872008-02-06 01:38:04 -0800596# endif
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800597#else
Roman Zippel71abb3a2008-05-01 04:34:26 -0700598 return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800599#endif
600}
601EXPORT_SYMBOL(jiffies_to_clock_t);
602
603unsigned long clock_t_to_jiffies(unsigned long x)
604{
605#if (HZ % USER_HZ)==0
606 if (x >= ~0UL / (HZ / USER_HZ))
607 return ~0UL;
608 return x * (HZ / USER_HZ);
609#else
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800610 /* Don't worry about loss of precision here .. */
611 if (x >= ~0UL / HZ * USER_HZ)
612 return ~0UL;
613
614 /* .. but do try to contain it here */
Roman Zippel71abb3a2008-05-01 04:34:26 -0700615 return div_u64((u64)x * HZ, USER_HZ);
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800616#endif
617}
618EXPORT_SYMBOL(clock_t_to_jiffies);
619
620u64 jiffies_64_to_clock_t(u64 x)
621{
622#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
David Fries6ffc7872008-02-06 01:38:04 -0800623# if HZ < USER_HZ
Roman Zippel71abb3a2008-05-01 04:34:26 -0700624 x = div_u64(x * USER_HZ, HZ);
Andrew Mortonec03d702008-02-06 01:38:06 -0800625# elif HZ > USER_HZ
Roman Zippel71abb3a2008-05-01 04:34:26 -0700626 x = div_u64(x, HZ / USER_HZ);
Andrew Mortonec03d702008-02-06 01:38:06 -0800627# else
628 /* Nothing to do */
David Fries6ffc7872008-02-06 01:38:04 -0800629# endif
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800630#else
631 /*
632 * There are better ways that don't overflow early,
633 * but even this doesn't overflow in hundreds of years
634 * in 64 bits, so..
635 */
Roman Zippel71abb3a2008-05-01 04:34:26 -0700636 x = div_u64(x * TICK_NSEC, (NSEC_PER_SEC / USER_HZ));
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800637#endif
638 return x;
639}
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800640EXPORT_SYMBOL(jiffies_64_to_clock_t);
641
642u64 nsec_to_clock_t(u64 x)
643{
644#if (NSEC_PER_SEC % USER_HZ) == 0
Roman Zippel71abb3a2008-05-01 04:34:26 -0700645 return div_u64(x, NSEC_PER_SEC / USER_HZ);
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800646#elif (USER_HZ % 512) == 0
Roman Zippel71abb3a2008-05-01 04:34:26 -0700647 return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512);
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800648#else
649 /*
650 * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
651 * overflow after 64.99 years.
652 * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
653 */
Roman Zippel71abb3a2008-05-01 04:34:26 -0700654 return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ);
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800655#endif
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800656}
657
Linus Torvalds1da177e2005-04-16 15:20:36 -0700658#if (BITS_PER_LONG < 64)
659u64 get_jiffies_64(void)
660{
661 unsigned long seq;
662 u64 ret;
663
664 do {
665 seq = read_seqbegin(&xtime_lock);
666 ret = jiffies_64;
667 } while (read_seqretry(&xtime_lock, seq));
668 return ret;
669}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670EXPORT_SYMBOL(get_jiffies_64);
671#endif
672
673EXPORT_SYMBOL(jiffies);
Thomas Gleixnerdf0cc052008-08-31 08:09:53 -0700674
675/*
676 * Add two timespec values and do a safety check for overflow.
677 * It's assumed that both values are valid (>= 0)
678 */
679struct timespec timespec_add_safe(const struct timespec lhs,
680 const struct timespec rhs)
681{
682 struct timespec res;
683
684 set_normalized_timespec(&res, lhs.tv_sec + rhs.tv_sec,
685 lhs.tv_nsec + rhs.tv_nsec);
686
687 if (res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec)
688 res.tv_sec = TIME_T_MAX;
689
690 return res;
691}