projects/linux·blob v4.16 · 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/core.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/export.h>
31#include <linux/timex.h>
32#include <linux/capability.h>
33#include <linux/timekeeper_internal.h>
34#include <linux/errno.h>
35#include <linux/syscalls.h>
36#include <linux/security.h>
37#include <linux/fs.h>
38#include <linux/math64.h>
39#include <linux/ptrace.h>
40
41#include <linux/uaccess.h>
42#include <linux/compat.h>
43#include <asm/unistd.h>
44
45#include <generated/timeconst.h>
46#include "timekeeping.h"
47
48/*
49 * The timezone where the local system is located. Used as a default by some
50 * programs who obtain this value by using gettimeofday.
51 */
52struct timezone sys_tz;
53
54EXPORT_SYMBOL(sys_tz);
55
56#ifdef __ARCH_WANT_SYS_TIME
57
58/*
59 * sys_time() can be implemented in user-level using
60 * sys_gettimeofday(). Is this for backwards compatibility? If so,
61 * why not move it into the appropriate arch directory (for those
62 * architectures that need it).
63 */
64SYSCALL_DEFINE1(time, time_t __user *, tloc)
65{
66 time_t i = get_seconds();
67
68 if (tloc) {
69 if (put_user(i,tloc))
70 return -EFAULT;
71 }
72 force_successful_syscall_return();
73 return i;
74}
75
76/*
77 * sys_stime() can be implemented in user-level using
78 * sys_settimeofday(). Is this for backwards compatibility? If so,
79 * why not move it into the appropriate arch directory (for those
80 * architectures that need it).
81 */
82
83SYSCALL_DEFINE1(stime, time_t __user *, tptr)
84{
85 struct timespec64 tv;
86 int err;
87
88 if (get_user(tv.tv_sec, tptr))
89 return -EFAULT;
90
91 tv.tv_nsec = 0;
92
93 err = security_settime64(&tv, NULL);
94 if (err)
95 return err;
96
97 do_settimeofday64(&tv);
98 return 0;
99}
100
101#endif /* __ARCH_WANT_SYS_TIME */
102
103#ifdef CONFIG_COMPAT
104#ifdef __ARCH_WANT_COMPAT_SYS_TIME
105
106/* compat_time_t is a 32 bit "long" and needs to get converted. */
107COMPAT_SYSCALL_DEFINE1(time, compat_time_t __user *, tloc)
108{
109 struct timeval tv;
110 compat_time_t i;
111
112 do_gettimeofday(&tv);
113 i = tv.tv_sec;
114
115 if (tloc) {
116 if (put_user(i,tloc))
117 return -EFAULT;
118 }
119 force_successful_syscall_return();
120 return i;
121}
122
123COMPAT_SYSCALL_DEFINE1(stime, compat_time_t __user *, tptr)
124{
125 struct timespec64 tv;
126 int err;
127
128 if (get_user(tv.tv_sec, tptr))
129 return -EFAULT;
130
131 tv.tv_nsec = 0;
132
133 err = security_settime64(&tv, NULL);
134 if (err)
135 return err;
136
137 do_settimeofday64(&tv);
138 return 0;
139}
140
141#endif /* __ARCH_WANT_COMPAT_SYS_TIME */
142#endif
143
144SYSCALL_DEFINE2(gettimeofday, struct timeval __user *, tv,
145 struct timezone __user *, tz)
146{
147 if (likely(tv != NULL)) {
148 struct timeval ktv;
149 do_gettimeofday(&ktv);
150 if (copy_to_user(tv, &ktv, sizeof(ktv)))
151 return -EFAULT;
152 }
153 if (unlikely(tz != NULL)) {
154 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
155 return -EFAULT;
156 }
157 return 0;
158}
159
160/*
161 * In case for some reason the CMOS clock has not already been running
162 * in UTC, but in some local time: The first time we set the timezone,
163 * we will warp the clock so that it is ticking UTC time instead of
164 * local time. Presumably, if someone is setting the timezone then we
165 * are running in an environment where the programs understand about
166 * timezones. This should be done at boot time in the /etc/rc script,
167 * as soon as possible, so that the clock can be set right. Otherwise,
168 * various programs will get confused when the clock gets warped.
169 */
170
171int do_sys_settimeofday64(const struct timespec64 *tv, const struct timezone *tz)
172{
173 static int firsttime = 1;
174 int error = 0;
175
176 if (tv && !timespec64_valid(tv))
177 return -EINVAL;
178
179 error = security_settime64(tv, tz);
180 if (error)
181 return error;
182
183 if (tz) {
184 /* Verify we're witin the +-15 hrs range */
185 if (tz->tz_minuteswest > 15*60 || tz->tz_minuteswest < -15*60)
186 return -EINVAL;
187
188 sys_tz = *tz;
189 update_vsyscall_tz();
190 if (firsttime) {
191 firsttime = 0;
192 if (!tv)
193 timekeeping_warp_clock();
194 }
195 }
196 if (tv)
197 return do_settimeofday64(tv);
198 return 0;
199}
200
201SYSCALL_DEFINE2(settimeofday, struct timeval __user *, tv,
202 struct timezone __user *, tz)
203{
204 struct timespec64 new_ts;
205 struct timeval user_tv;
206 struct timezone new_tz;
207
208 if (tv) {
209 if (copy_from_user(&user_tv, tv, sizeof(*tv)))
210 return -EFAULT;
211
212 if (!timeval_valid(&user_tv))
213 return -EINVAL;
214
215 new_ts.tv_sec = user_tv.tv_sec;
216 new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
217 }
218 if (tz) {
219 if (copy_from_user(&new_tz, tz, sizeof(*tz)))
220 return -EFAULT;
221 }
222
223 return do_sys_settimeofday64(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
224}
225
226#ifdef CONFIG_COMPAT
227COMPAT_SYSCALL_DEFINE2(gettimeofday, struct compat_timeval __user *, tv,
228 struct timezone __user *, tz)
229{
230 if (tv) {
231 struct timeval ktv;
232
233 do_gettimeofday(&ktv);
234 if (compat_put_timeval(&ktv, tv))
235 return -EFAULT;
236 }
237 if (tz) {
238 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
239 return -EFAULT;
240 }
241
242 return 0;
243}
244
245COMPAT_SYSCALL_DEFINE2(settimeofday, struct compat_timeval __user *, tv,
246 struct timezone __user *, tz)
247{
248 struct timespec64 new_ts;
249 struct timeval user_tv;
250 struct timezone new_tz;
251
252 if (tv) {
253 if (compat_get_timeval(&user_tv, tv))
254 return -EFAULT;
255 new_ts.tv_sec = user_tv.tv_sec;
256 new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
257 }
258 if (tz) {
259 if (copy_from_user(&new_tz, tz, sizeof(*tz)))
260 return -EFAULT;
261 }
262
263 return do_sys_settimeofday64(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
264}
265#endif
266
267SYSCALL_DEFINE1(adjtimex, struct timex __user *, txc_p)
268{
269 struct timex txc; /* Local copy of parameter */
270 int ret;
271
272 /* Copy the user data space into the kernel copy
273 * structure. But bear in mind that the structures
274 * may change
275 */
276 if (copy_from_user(&txc, txc_p, sizeof(struct timex)))
277 return -EFAULT;
278 ret = do_adjtimex(&txc);
279 return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
280}
281
282#ifdef CONFIG_COMPAT
283
284COMPAT_SYSCALL_DEFINE1(adjtimex, struct compat_timex __user *, utp)
285{
286 struct timex txc;
287 int err, ret;
288
289 err = compat_get_timex(&txc, utp);
290 if (err)
291 return err;
292
293 ret = do_adjtimex(&txc);
294
295 err = compat_put_timex(utp, &txc);
296 if (err)
297 return err;
298
299 return ret;
300}
301#endif
302
303/*
304 * Convert jiffies to milliseconds and back.
305 *
306 * Avoid unnecessary multiplications/divisions in the
307 * two most common HZ cases:
308 */
309unsigned int jiffies_to_msecs(const unsigned long j)
310{
311#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
312 return (MSEC_PER_SEC / HZ) * j;
313#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
314 return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
315#else
316# if BITS_PER_LONG == 32
317 return (HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32;
318# else
319 return (j * HZ_TO_MSEC_NUM) / HZ_TO_MSEC_DEN;
320# endif
321#endif
322}
323EXPORT_SYMBOL(jiffies_to_msecs);
324
325unsigned int jiffies_to_usecs(const unsigned long j)
326{
327 /*
328 * Hz usually doesn't go much further MSEC_PER_SEC.
329 * jiffies_to_usecs() and usecs_to_jiffies() depend on that.
330 */
331 BUILD_BUG_ON(HZ > USEC_PER_SEC);
332
333#if !(USEC_PER_SEC % HZ)
334 return (USEC_PER_SEC / HZ) * j;
335#else
336# if BITS_PER_LONG == 32
337 return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32;
338# else
339 return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN;
340# endif
341#endif
342}
343EXPORT_SYMBOL(jiffies_to_usecs);
344
345/**
346 * timespec_trunc - Truncate timespec to a granularity
347 * @t: Timespec
348 * @gran: Granularity in ns.
349 *
350 * Truncate a timespec to a granularity. Always rounds down. gran must
351 * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns).
352 */
353struct timespec timespec_trunc(struct timespec t, unsigned gran)
354{
355 /* Avoid division in the common cases 1 ns and 1 s. */
356 if (gran == 1) {
357 /* nothing */
358 } else if (gran == NSEC_PER_SEC) {
359 t.tv_nsec = 0;
360 } else if (gran > 1 && gran < NSEC_PER_SEC) {
361 t.tv_nsec -= t.tv_nsec % gran;
362 } else {
363 WARN(1, "illegal file time granularity: %u", gran);
364 }
365 return t;
366}
367EXPORT_SYMBOL(timespec_trunc);
368
369/*
370 * mktime64 - Converts date to seconds.
371 * Converts Gregorian date to seconds since 1970-01-01 00:00:00.
372 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
373 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
374 *
375 * [For the Julian calendar (which was used in Russia before 1917,
376 * Britain & colonies before 1752, anywhere else before 1582,
377 * and is still in use by some communities) leave out the
378 * -year/100+year/400 terms, and add 10.]
379 *
380 * This algorithm was first published by Gauss (I think).
381 *
382 * A leap second can be indicated by calling this function with sec as
383 * 60 (allowable under ISO 8601). The leap second is treated the same
384 * as the following second since they don't exist in UNIX time.
385 *
386 * An encoding of midnight at the end of the day as 24:00:00 - ie. midnight
387 * tomorrow - (allowable under ISO 8601) is supported.
388 */
389time64_t mktime64(const unsigned int year0, const unsigned int mon0,
390 const unsigned int day, const unsigned int hour,
391 const unsigned int min, const unsigned int sec)
392{
393 unsigned int mon = mon0, year = year0;
394
395 /* 1..12 -> 11,12,1..10 */
396 if (0 >= (int) (mon -= 2)) {
397 mon += 12; /* Puts Feb last since it has leap day */
398 year -= 1;
399 }
400
401 return ((((time64_t)
402 (year/4 - year/100 + year/400 + 367*mon/12 + day) +
403 year*365 - 719499
404 )*24 + hour /* now have hours - midnight tomorrow handled here */
405 )*60 + min /* now have minutes */
406 )*60 + sec; /* finally seconds */
407}
408EXPORT_SYMBOL(mktime64);
409
410#if __BITS_PER_LONG == 32
411/**
412 * set_normalized_timespec - set timespec sec and nsec parts and normalize
413 *
414 * @ts: pointer to timespec variable to be set
415 * @sec: seconds to set
416 * @nsec: nanoseconds to set
417 *
418 * Set seconds and nanoseconds field of a timespec variable and
419 * normalize to the timespec storage format
420 *
421 * Note: The tv_nsec part is always in the range of
422 * 0 <= tv_nsec < NSEC_PER_SEC
423 * For negative values only the tv_sec field is negative !
424 */
425void set_normalized_timespec(struct timespec *ts, time_t sec, s64 nsec)
426{
427 while (nsec >= NSEC_PER_SEC) {
428 /*
429 * The following asm() prevents the compiler from
430 * optimising this loop into a modulo operation. See
431 * also __iter_div_u64_rem() in include/linux/time.h
432 */
433 asm("" : "+rm"(nsec));
434 nsec -= NSEC_PER_SEC;
435 ++sec;
436 }
437 while (nsec < 0) {
438 asm("" : "+rm"(nsec));
439 nsec += NSEC_PER_SEC;
440 --sec;
441 }
442 ts->tv_sec = sec;
443 ts->tv_nsec = nsec;
444}
445EXPORT_SYMBOL(set_normalized_timespec);
446
447/**
448 * ns_to_timespec - Convert nanoseconds to timespec
449 * @nsec: the nanoseconds value to be converted
450 *
451 * Returns the timespec representation of the nsec parameter.
452 */
453struct timespec ns_to_timespec(const s64 nsec)
454{
455 struct timespec ts;
456 s32 rem;
457
458 if (!nsec)
459 return (struct timespec) {0, 0};
460
461 ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
462 if (unlikely(rem < 0)) {
463 ts.tv_sec--;
464 rem += NSEC_PER_SEC;
465 }
466 ts.tv_nsec = rem;
467
468 return ts;
469}
470EXPORT_SYMBOL(ns_to_timespec);
471#endif
472
473/**
474 * ns_to_timeval - Convert nanoseconds to timeval
475 * @nsec: the nanoseconds value to be converted
476 *
477 * Returns the timeval representation of the nsec parameter.
478 */
479struct timeval ns_to_timeval(const s64 nsec)
480{
481 struct timespec ts = ns_to_timespec(nsec);
482 struct timeval tv;
483
484 tv.tv_sec = ts.tv_sec;
485 tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000;
486
487 return tv;
488}
489EXPORT_SYMBOL(ns_to_timeval);
490
491/**
492 * set_normalized_timespec - set timespec sec and nsec parts and normalize
493 *
494 * @ts: pointer to timespec variable to be set
495 * @sec: seconds to set
496 * @nsec: nanoseconds to set
497 *
498 * Set seconds and nanoseconds field of a timespec variable and
499 * normalize to the timespec storage format
500 *
501 * Note: The tv_nsec part is always in the range of
502 * 0 <= tv_nsec < NSEC_PER_SEC
503 * For negative values only the tv_sec field is negative !
504 */
505void set_normalized_timespec64(struct timespec64 *ts, time64_t sec, s64 nsec)
506{
507 while (nsec >= NSEC_PER_SEC) {
508 /*
509 * The following asm() prevents the compiler from
510 * optimising this loop into a modulo operation. See
511 * also __iter_div_u64_rem() in include/linux/time.h
512 */
513 asm("" : "+rm"(nsec));
514 nsec -= NSEC_PER_SEC;
515 ++sec;
516 }
517 while (nsec < 0) {
518 asm("" : "+rm"(nsec));
519 nsec += NSEC_PER_SEC;
520 --sec;
521 }
522 ts->tv_sec = sec;
523 ts->tv_nsec = nsec;
524}
525EXPORT_SYMBOL(set_normalized_timespec64);
526
527/**
528 * ns_to_timespec64 - Convert nanoseconds to timespec64
529 * @nsec: the nanoseconds value to be converted
530 *
531 * Returns the timespec64 representation of the nsec parameter.
532 */
533struct timespec64 ns_to_timespec64(const s64 nsec)
534{
535 struct timespec64 ts;
536 s32 rem;
537
538 if (!nsec)
539 return (struct timespec64) {0, 0};
540
541 ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
542 if (unlikely(rem < 0)) {
543 ts.tv_sec--;
544 rem += NSEC_PER_SEC;
545 }
546 ts.tv_nsec = rem;
547
548 return ts;
549}
550EXPORT_SYMBOL(ns_to_timespec64);
551
552/**
553 * msecs_to_jiffies: - convert milliseconds to jiffies
554 * @m: time in milliseconds
555 *
556 * conversion is done as follows:
557 *
558 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
559 *
560 * - 'too large' values [that would result in larger than
561 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
562 *
563 * - all other values are converted to jiffies by either multiplying
564 * the input value by a factor or dividing it with a factor and
565 * handling any 32-bit overflows.
566 * for the details see __msecs_to_jiffies()
567 *
568 * msecs_to_jiffies() checks for the passed in value being a constant
569 * via __builtin_constant_p() allowing gcc to eliminate most of the
570 * code, __msecs_to_jiffies() is called if the value passed does not
571 * allow constant folding and the actual conversion must be done at
572 * runtime.
573 * the _msecs_to_jiffies helpers are the HZ dependent conversion
574 * routines found in include/linux/jiffies.h
575 */
576unsigned long __msecs_to_jiffies(const unsigned int m)
577{
578 /*
579 * Negative value, means infinite timeout:
580 */
581 if ((int)m < 0)
582 return MAX_JIFFY_OFFSET;
583 return _msecs_to_jiffies(m);
584}
585EXPORT_SYMBOL(__msecs_to_jiffies);
586
587unsigned long __usecs_to_jiffies(const unsigned int u)
588{
589 if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
590 return MAX_JIFFY_OFFSET;
591 return _usecs_to_jiffies(u);
592}
593EXPORT_SYMBOL(__usecs_to_jiffies);
594
595/*
596 * The TICK_NSEC - 1 rounds up the value to the next resolution. Note
597 * that a remainder subtract here would not do the right thing as the
598 * resolution values don't fall on second boundries. I.e. the line:
599 * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding.
600 * Note that due to the small error in the multiplier here, this
601 * rounding is incorrect for sufficiently large values of tv_nsec, but
602 * well formed timespecs should have tv_nsec < NSEC_PER_SEC, so we're
603 * OK.
604 *
605 * Rather, we just shift the bits off the right.
606 *
607 * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
608 * value to a scaled second value.
609 */
610static unsigned long
611__timespec64_to_jiffies(u64 sec, long nsec)
612{
613 nsec = nsec + TICK_NSEC - 1;
614
615 if (sec >= MAX_SEC_IN_JIFFIES){
616 sec = MAX_SEC_IN_JIFFIES;
617 nsec = 0;
618 }
619 return ((sec * SEC_CONVERSION) +
620 (((u64)nsec * NSEC_CONVERSION) >>
621 (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
622
623}
624
625static unsigned long
626__timespec_to_jiffies(unsigned long sec, long nsec)
627{
628 return __timespec64_to_jiffies((u64)sec, nsec);
629}
630
631unsigned long
632timespec64_to_jiffies(const struct timespec64 *value)
633{
634 return __timespec64_to_jiffies(value->tv_sec, value->tv_nsec);
635}
636EXPORT_SYMBOL(timespec64_to_jiffies);
637
638void
639jiffies_to_timespec64(const unsigned long jiffies, struct timespec64 *value)
640{
641 /*
642 * Convert jiffies to nanoseconds and separate with
643 * one divide.
644 */
645 u32 rem;
646 value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
647 NSEC_PER_SEC, &rem);
648 value->tv_nsec = rem;
649}
650EXPORT_SYMBOL(jiffies_to_timespec64);
651
652/*
653 * We could use a similar algorithm to timespec_to_jiffies (with a
654 * different multiplier for usec instead of nsec). But this has a
655 * problem with rounding: we can't exactly add TICK_NSEC - 1 to the
656 * usec value, since it's not necessarily integral.
657 *
658 * We could instead round in the intermediate scaled representation
659 * (i.e. in units of 1/2^(large scale) jiffies) but that's also
660 * perilous: the scaling introduces a small positive error, which
661 * combined with a division-rounding-upward (i.e. adding 2^(scale) - 1
662 * units to the intermediate before shifting) leads to accidental
663 * overflow and overestimates.
664 *
665 * At the cost of one additional multiplication by a constant, just
666 * use the timespec implementation.
667 */
668unsigned long
669timeval_to_jiffies(const struct timeval *value)
670{
671 return __timespec_to_jiffies(value->tv_sec,
672 value->tv_usec * NSEC_PER_USEC);
673}
674EXPORT_SYMBOL(timeval_to_jiffies);
675
676void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value)
677{
678 /*
679 * Convert jiffies to nanoseconds and separate with
680 * one divide.
681 */
682 u32 rem;
683
684 value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
685 NSEC_PER_SEC, &rem);
686 value->tv_usec = rem / NSEC_PER_USEC;
687}
688EXPORT_SYMBOL(jiffies_to_timeval);
689
690/*
691 * Convert jiffies/jiffies_64 to clock_t and back.
692 */
693clock_t jiffies_to_clock_t(unsigned long x)
694{
695#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
696# if HZ < USER_HZ
697 return x * (USER_HZ / HZ);
698# else
699 return x / (HZ / USER_HZ);
700# endif
701#else
702 return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
703#endif
704}
705EXPORT_SYMBOL(jiffies_to_clock_t);
706
707unsigned long clock_t_to_jiffies(unsigned long x)
708{
709#if (HZ % USER_HZ)==0
710 if (x >= ~0UL / (HZ / USER_HZ))
711 return ~0UL;
712 return x * (HZ / USER_HZ);
713#else
714 /* Don't worry about loss of precision here .. */
715 if (x >= ~0UL / HZ * USER_HZ)
716 return ~0UL;
717
718 /* .. but do try to contain it here */
719 return div_u64((u64)x * HZ, USER_HZ);
720#endif
721}
722EXPORT_SYMBOL(clock_t_to_jiffies);
723
724u64 jiffies_64_to_clock_t(u64 x)
725{
726#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
727# if HZ < USER_HZ
728 x = div_u64(x * USER_HZ, HZ);
729# elif HZ > USER_HZ
730 x = div_u64(x, HZ / USER_HZ);
731# else
732 /* Nothing to do */
733# endif
734#else
735 /*
736 * There are better ways that don't overflow early,
737 * but even this doesn't overflow in hundreds of years
738 * in 64 bits, so..
739 */
740 x = div_u64(x * TICK_NSEC, (NSEC_PER_SEC / USER_HZ));
741#endif
742 return x;
743}
744EXPORT_SYMBOL(jiffies_64_to_clock_t);
745
746u64 nsec_to_clock_t(u64 x)
747{
748#if (NSEC_PER_SEC % USER_HZ) == 0
749 return div_u64(x, NSEC_PER_SEC / USER_HZ);
750#elif (USER_HZ % 512) == 0
751 return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512);
752#else
753 /*
754 * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
755 * overflow after 64.99 years.
756 * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
757 */
758 return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ);
759#endif
760}
761
762u64 jiffies64_to_nsecs(u64 j)
763{
764#if !(NSEC_PER_SEC % HZ)
765 return (NSEC_PER_SEC / HZ) * j;
766# else
767 return div_u64(j * HZ_TO_NSEC_NUM, HZ_TO_NSEC_DEN);
768#endif
769}
770EXPORT_SYMBOL(jiffies64_to_nsecs);
771
772/**
773 * nsecs_to_jiffies64 - Convert nsecs in u64 to jiffies64
774 *
775 * @n: nsecs in u64
776 *
777 * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
778 * And this doesn't return MAX_JIFFY_OFFSET since this function is designed
779 * for scheduler, not for use in device drivers to calculate timeout value.
780 *
781 * note:
782 * NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
783 * ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
784 */
785u64 nsecs_to_jiffies64(u64 n)
786{
787#if (NSEC_PER_SEC % HZ) == 0
788 /* Common case, HZ = 100, 128, 200, 250, 256, 500, 512, 1000 etc. */
789 return div_u64(n, NSEC_PER_SEC / HZ);
790#elif (HZ % 512) == 0
791 /* overflow after 292 years if HZ = 1024 */
792 return div_u64(n * HZ / 512, NSEC_PER_SEC / 512);
793#else
794 /*
795 * Generic case - optimized for cases where HZ is a multiple of 3.
796 * overflow after 64.99 years, exact for HZ = 60, 72, 90, 120 etc.
797 */
798 return div_u64(n * 9, (9ull * NSEC_PER_SEC + HZ / 2) / HZ);
799#endif
800}
801EXPORT_SYMBOL(nsecs_to_jiffies64);
802
803/**
804 * nsecs_to_jiffies - Convert nsecs in u64 to jiffies
805 *
806 * @n: nsecs in u64
807 *
808 * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
809 * And this doesn't return MAX_JIFFY_OFFSET since this function is designed
810 * for scheduler, not for use in device drivers to calculate timeout value.
811 *
812 * note:
813 * NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
814 * ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
815 */
816unsigned long nsecs_to_jiffies(u64 n)
817{
818 return (unsigned long)nsecs_to_jiffies64(n);
819}
820EXPORT_SYMBOL_GPL(nsecs_to_jiffies);
821
822/*
823 * Add two timespec64 values and do a safety check for overflow.
824 * It's assumed that both values are valid (>= 0).
825 * And, each timespec64 is in normalized form.
826 */
827struct timespec64 timespec64_add_safe(const struct timespec64 lhs,
828 const struct timespec64 rhs)
829{
830 struct timespec64 res;
831
832 set_normalized_timespec64(&res, (timeu64_t) lhs.tv_sec + rhs.tv_sec,
833 lhs.tv_nsec + rhs.tv_nsec);
834
835 if (unlikely(res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec)) {
836 res.tv_sec = TIME64_MAX;
837 res.tv_nsec = 0;
838 }
839
840 return res;
841}
842
843int get_timespec64(struct timespec64 *ts,
844 const struct timespec __user *uts)
845{
846 struct timespec kts;
847 int ret;
848
849 ret = copy_from_user(&kts, uts, sizeof(kts));
850 if (ret)
851 return -EFAULT;
852
853 ts->tv_sec = kts.tv_sec;
854 ts->tv_nsec = kts.tv_nsec;
855
856 return 0;
857}
858EXPORT_SYMBOL_GPL(get_timespec64);
859
860int put_timespec64(const struct timespec64 *ts,
861 struct timespec __user *uts)
862{
863 struct timespec kts = {
864 .tv_sec = ts->tv_sec,
865 .tv_nsec = ts->tv_nsec
866 };
867 return copy_to_user(uts, &kts, sizeof(kts)) ? -EFAULT : 0;
868}
869EXPORT_SYMBOL_GPL(put_timespec64);
870
871int get_itimerspec64(struct itimerspec64 *it,
872 const struct itimerspec __user *uit)
873{
874 int ret;
875
876 ret = get_timespec64(&it->it_interval, &uit->it_interval);
877 if (ret)
878 return ret;
879
880 ret = get_timespec64(&it->it_value, &uit->it_value);
881
882 return ret;
883}
884EXPORT_SYMBOL_GPL(get_itimerspec64);
885
886int put_itimerspec64(const struct itimerspec64 *it,
887 struct itimerspec __user *uit)
888{
889 int ret;
890
891 ret = put_timespec64(&it->it_interval, &uit->it_interval);
892 if (ret)
893 return ret;
894
895 ret = put_timespec64(&it->it_value, &uit->it_value);
896
897 return ret;
898}
899EXPORT_SYMBOL_GPL(put_itimerspec64);