projects/linux·blob v4.18 · refs

961 lines · 23.8 KiB

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/kernel.h>
32#include <linux/timex.h>
33#include <linux/capability.h>
34#include <linux/timekeeper_internal.h>
35#include <linux/errno.h>
36#include <linux/syscalls.h>
37#include <linux/security.h>
38#include <linux/fs.h>
39#include <linux/math64.h>
40#include <linux/ptrace.h>
41
42#include <linux/uaccess.h>
43#include <linux/compat.h>
44#include <asm/unistd.h>
45
46#include <generated/timeconst.h>
47#include "timekeeping.h"
48
49/*
50 * The timezone where the local system is located. Used as a default by some
51 * programs who obtain this value by using gettimeofday.
52 */
53struct timezone sys_tz;
54
55EXPORT_SYMBOL(sys_tz);
56
57#ifdef __ARCH_WANT_SYS_TIME
58
59/*
60 * sys_time() can be implemented in user-level using
61 * sys_gettimeofday(). Is this for backwards compatibility? If so,
62 * why not move it into the appropriate arch directory (for those
63 * architectures that need it).
64 */
65SYSCALL_DEFINE1(time, time_t __user *, tloc)
66{
67 time_t i = get_seconds();
68
69 if (tloc) {
70 if (put_user(i,tloc))
71 return -EFAULT;
72 }
73 force_successful_syscall_return();
74 return i;
75}
76
77/*
78 * sys_stime() can be implemented in user-level using
79 * sys_settimeofday(). Is this for backwards compatibility? If so,
80 * why not move it into the appropriate arch directory (for those
81 * architectures that need it).
82 */
83
84SYSCALL_DEFINE1(stime, time_t __user *, tptr)
85{
86 struct timespec64 tv;
87 int err;
88
89 if (get_user(tv.tv_sec, tptr))
90 return -EFAULT;
91
92 tv.tv_nsec = 0;
93
94 err = security_settime64(&tv, NULL);
95 if (err)
96 return err;
97
98 do_settimeofday64(&tv);
99 return 0;
100}
101
102#endif /* __ARCH_WANT_SYS_TIME */
103
104#ifdef CONFIG_COMPAT
105#ifdef __ARCH_WANT_COMPAT_SYS_TIME
106
107/* compat_time_t is a 32 bit "long" and needs to get converted. */
108COMPAT_SYSCALL_DEFINE1(time, compat_time_t __user *, tloc)
109{
110 struct timeval tv;
111 compat_time_t i;
112
113 do_gettimeofday(&tv);
114 i = tv.tv_sec;
115
116 if (tloc) {
117 if (put_user(i,tloc))
118 return -EFAULT;
119 }
120 force_successful_syscall_return();
121 return i;
122}
123
124COMPAT_SYSCALL_DEFINE1(stime, compat_time_t __user *, tptr)
125{
126 struct timespec64 tv;
127 int err;
128
129 if (get_user(tv.tv_sec, tptr))
130 return -EFAULT;
131
132 tv.tv_nsec = 0;
133
134 err = security_settime64(&tv, NULL);
135 if (err)
136 return err;
137
138 do_settimeofday64(&tv);
139 return 0;
140}
141
142#endif /* __ARCH_WANT_COMPAT_SYS_TIME */
143#endif
144
145SYSCALL_DEFINE2(gettimeofday, struct timeval __user *, tv,
146 struct timezone __user *, tz)
147{
148 if (likely(tv != NULL)) {
149 struct timeval ktv;
150 do_gettimeofday(&ktv);
151 if (copy_to_user(tv, &ktv, sizeof(ktv)))
152 return -EFAULT;
153 }
154 if (unlikely(tz != NULL)) {
155 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
156 return -EFAULT;
157 }
158 return 0;
159}
160
161/*
162 * In case for some reason the CMOS clock has not already been running
163 * in UTC, but in some local time: The first time we set the timezone,
164 * we will warp the clock so that it is ticking UTC time instead of
165 * local time. Presumably, if someone is setting the timezone then we
166 * are running in an environment where the programs understand about
167 * timezones. This should be done at boot time in the /etc/rc script,
168 * as soon as possible, so that the clock can be set right. Otherwise,
169 * various programs will get confused when the clock gets warped.
170 */
171
172int do_sys_settimeofday64(const struct timespec64 *tv, const struct timezone *tz)
173{
174 static int firsttime = 1;
175 int error = 0;
176
177 if (tv && !timespec64_valid(tv))
178 return -EINVAL;
179
180 error = security_settime64(tv, tz);
181 if (error)
182 return error;
183
184 if (tz) {
185 /* Verify we're witin the +-15 hrs range */
186 if (tz->tz_minuteswest > 15*60 || tz->tz_minuteswest < -15*60)
187 return -EINVAL;
188
189 sys_tz = *tz;
190 update_vsyscall_tz();
191 if (firsttime) {
192 firsttime = 0;
193 if (!tv)
194 timekeeping_warp_clock();
195 }
196 }
197 if (tv)
198 return do_settimeofday64(tv);
199 return 0;
200}
201
202SYSCALL_DEFINE2(settimeofday, struct timeval __user *, tv,
203 struct timezone __user *, tz)
204{
205 struct timespec64 new_ts;
206 struct timeval user_tv;
207 struct timezone new_tz;
208
209 if (tv) {
210 if (copy_from_user(&user_tv, tv, sizeof(*tv)))
211 return -EFAULT;
212
213 if (!timeval_valid(&user_tv))
214 return -EINVAL;
215
216 new_ts.tv_sec = user_tv.tv_sec;
217 new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
218 }
219 if (tz) {
220 if (copy_from_user(&new_tz, tz, sizeof(*tz)))
221 return -EFAULT;
222 }
223
224 return do_sys_settimeofday64(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
225}
226
227#ifdef CONFIG_COMPAT
228COMPAT_SYSCALL_DEFINE2(gettimeofday, struct compat_timeval __user *, tv,
229 struct timezone __user *, tz)
230{
231 if (tv) {
232 struct timeval ktv;
233
234 do_gettimeofday(&ktv);
235 if (compat_put_timeval(&ktv, tv))
236 return -EFAULT;
237 }
238 if (tz) {
239 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
240 return -EFAULT;
241 }
242
243 return 0;
244}
245
246COMPAT_SYSCALL_DEFINE2(settimeofday, struct compat_timeval __user *, tv,
247 struct timezone __user *, tz)
248{
249 struct timespec64 new_ts;
250 struct timeval user_tv;
251 struct timezone new_tz;
252
253 if (tv) {
254 if (compat_get_timeval(&user_tv, tv))
255 return -EFAULT;
256 new_ts.tv_sec = user_tv.tv_sec;
257 new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
258 }
259 if (tz) {
260 if (copy_from_user(&new_tz, tz, sizeof(*tz)))
261 return -EFAULT;
262 }
263
264 return do_sys_settimeofday64(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
265}
266#endif
267
268SYSCALL_DEFINE1(adjtimex, struct timex __user *, txc_p)
269{
270 struct timex txc; /* Local copy of parameter */
271 int ret;
272
273 /* Copy the user data space into the kernel copy
274 * structure. But bear in mind that the structures
275 * may change
276 */
277 if (copy_from_user(&txc, txc_p, sizeof(struct timex)))
278 return -EFAULT;
279 ret = do_adjtimex(&txc);
280 return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
281}
282
283#ifdef CONFIG_COMPAT
284
285COMPAT_SYSCALL_DEFINE1(adjtimex, struct compat_timex __user *, utp)
286{
287 struct timex txc;
288 int err, ret;
289
290 err = compat_get_timex(&txc, utp);
291 if (err)
292 return err;
293
294 ret = do_adjtimex(&txc);
295
296 err = compat_put_timex(utp, &txc);
297 if (err)
298 return err;
299
300 return ret;
301}
302#endif
303
304/*
305 * Convert jiffies to milliseconds and back.
306 *
307 * Avoid unnecessary multiplications/divisions in the
308 * two most common HZ cases:
309 */
310unsigned int jiffies_to_msecs(const unsigned long j)
311{
312#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
313 return (MSEC_PER_SEC / HZ) * j;
314#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
315 return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
316#else
317# if BITS_PER_LONG == 32
318 return (HZ_TO_MSEC_MUL32 * j + (1ULL << HZ_TO_MSEC_SHR32) - 1) >>
319 HZ_TO_MSEC_SHR32;
320# else
321 return DIV_ROUND_UP(j * HZ_TO_MSEC_NUM, HZ_TO_MSEC_DEN);
322# endif
323#endif
324}
325EXPORT_SYMBOL(jiffies_to_msecs);
326
327unsigned int jiffies_to_usecs(const unsigned long j)
328{
329 /*
330 * Hz usually doesn't go much further MSEC_PER_SEC.
331 * jiffies_to_usecs() and usecs_to_jiffies() depend on that.
332 */
333 BUILD_BUG_ON(HZ > USEC_PER_SEC);
334
335#if !(USEC_PER_SEC % HZ)
336 return (USEC_PER_SEC / HZ) * j;
337#else
338# if BITS_PER_LONG == 32
339 return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32;
340# else
341 return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN;
342# endif
343#endif
344}
345EXPORT_SYMBOL(jiffies_to_usecs);
346
347/**
348 * timespec_trunc - Truncate timespec to a granularity
349 * @t: Timespec
350 * @gran: Granularity in ns.
351 *
352 * Truncate a timespec to a granularity. Always rounds down. gran must
353 * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns).
354 */
355struct timespec timespec_trunc(struct timespec t, unsigned gran)
356{
357 /* Avoid division in the common cases 1 ns and 1 s. */
358 if (gran == 1) {
359 /* nothing */
360 } else if (gran == NSEC_PER_SEC) {
361 t.tv_nsec = 0;
362 } else if (gran > 1 && gran < NSEC_PER_SEC) {
363 t.tv_nsec -= t.tv_nsec % gran;
364 } else {
365 WARN(1, "illegal file time granularity: %u", gran);
366 }
367 return t;
368}
369EXPORT_SYMBOL(timespec_trunc);
370
371/*
372 * mktime64 - Converts date to seconds.
373 * Converts Gregorian date to seconds since 1970-01-01 00:00:00.
374 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
375 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
376 *
377 * [For the Julian calendar (which was used in Russia before 1917,
378 * Britain & colonies before 1752, anywhere else before 1582,
379 * and is still in use by some communities) leave out the
380 * -year/100+year/400 terms, and add 10.]
381 *
382 * This algorithm was first published by Gauss (I think).
383 *
384 * A leap second can be indicated by calling this function with sec as
385 * 60 (allowable under ISO 8601). The leap second is treated the same
386 * as the following second since they don't exist in UNIX time.
387 *
388 * An encoding of midnight at the end of the day as 24:00:00 - ie. midnight
389 * tomorrow - (allowable under ISO 8601) is supported.
390 */
391time64_t mktime64(const unsigned int year0, const unsigned int mon0,
392 const unsigned int day, const unsigned int hour,
393 const unsigned int min, const unsigned int sec)
394{
395 unsigned int mon = mon0, year = year0;
396
397 /* 1..12 -> 11,12,1..10 */
398 if (0 >= (int) (mon -= 2)) {
399 mon += 12; /* Puts Feb last since it has leap day */
400 year -= 1;
401 }
402
403 return ((((time64_t)
404 (year/4 - year/100 + year/400 + 367*mon/12 + day) +
405 year*365 - 719499
406 )*24 + hour /* now have hours - midnight tomorrow handled here */
407 )*60 + min /* now have minutes */
408 )*60 + sec; /* finally seconds */
409}
410EXPORT_SYMBOL(mktime64);
411
412/**
413 * set_normalized_timespec - set timespec sec and nsec parts and normalize
414 *
415 * @ts: pointer to timespec variable to be set
416 * @sec: seconds to set
417 * @nsec: nanoseconds to set
418 *
419 * Set seconds and nanoseconds field of a timespec variable and
420 * normalize to the timespec storage format
421 *
422 * Note: The tv_nsec part is always in the range of
423 * 0 <= tv_nsec < NSEC_PER_SEC
424 * For negative values only the tv_sec field is negative !
425 */
426void set_normalized_timespec(struct timespec *ts, time_t sec, s64 nsec)
427{
428 while (nsec >= NSEC_PER_SEC) {
429 /*
430 * The following asm() prevents the compiler from
431 * optimising this loop into a modulo operation. See
432 * also __iter_div_u64_rem() in include/linux/time.h
433 */
434 asm("" : "+rm"(nsec));
435 nsec -= NSEC_PER_SEC;
436 ++sec;
437 }
438 while (nsec < 0) {
439 asm("" : "+rm"(nsec));
440 nsec += NSEC_PER_SEC;
441 --sec;
442 }
443 ts->tv_sec = sec;
444 ts->tv_nsec = nsec;
445}
446EXPORT_SYMBOL(set_normalized_timespec);
447
448/**
449 * ns_to_timespec - Convert nanoseconds to timespec
450 * @nsec: the nanoseconds value to be converted
451 *
452 * Returns the timespec representation of the nsec parameter.
453 */
454struct timespec ns_to_timespec(const s64 nsec)
455{
456 struct timespec ts;
457 s32 rem;
458
459 if (!nsec)
460 return (struct timespec) {0, 0};
461
462 ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
463 if (unlikely(rem < 0)) {
464 ts.tv_sec--;
465 rem += NSEC_PER_SEC;
466 }
467 ts.tv_nsec = rem;
468
469 return ts;
470}
471EXPORT_SYMBOL(ns_to_timespec);
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
491struct __kernel_old_timeval ns_to_kernel_old_timeval(const s64 nsec)
492{
493 struct timespec64 ts = ns_to_timespec64(nsec);
494 struct __kernel_old_timeval tv;
495
496 tv.tv_sec = ts.tv_sec;
497 tv.tv_usec = (suseconds_t)ts.tv_nsec / 1000;
498
499 return tv;
500}
501EXPORT_SYMBOL(ns_to_kernel_old_timeval);
502
503/**
504 * set_normalized_timespec - set timespec sec and nsec parts and normalize
505 *
506 * @ts: pointer to timespec variable to be set
507 * @sec: seconds to set
508 * @nsec: nanoseconds to set
509 *
510 * Set seconds and nanoseconds field of a timespec variable and
511 * normalize to the timespec storage format
512 *
513 * Note: The tv_nsec part is always in the range of
514 * 0 <= tv_nsec < NSEC_PER_SEC
515 * For negative values only the tv_sec field is negative !
516 */
517void set_normalized_timespec64(struct timespec64 *ts, time64_t sec, s64 nsec)
518{
519 while (nsec >= NSEC_PER_SEC) {
520 /*
521 * The following asm() prevents the compiler from
522 * optimising this loop into a modulo operation. See
523 * also __iter_div_u64_rem() in include/linux/time.h
524 */
525 asm("" : "+rm"(nsec));
526 nsec -= NSEC_PER_SEC;
527 ++sec;
528 }
529 while (nsec < 0) {
530 asm("" : "+rm"(nsec));
531 nsec += NSEC_PER_SEC;
532 --sec;
533 }
534 ts->tv_sec = sec;
535 ts->tv_nsec = nsec;
536}
537EXPORT_SYMBOL(set_normalized_timespec64);
538
539/**
540 * ns_to_timespec64 - Convert nanoseconds to timespec64
541 * @nsec: the nanoseconds value to be converted
542 *
543 * Returns the timespec64 representation of the nsec parameter.
544 */
545struct timespec64 ns_to_timespec64(const s64 nsec)
546{
547 struct timespec64 ts;
548 s32 rem;
549
550 if (!nsec)
551 return (struct timespec64) {0, 0};
552
553 ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
554 if (unlikely(rem < 0)) {
555 ts.tv_sec--;
556 rem += NSEC_PER_SEC;
557 }
558 ts.tv_nsec = rem;
559
560 return ts;
561}
562EXPORT_SYMBOL(ns_to_timespec64);
563
564/**
565 * msecs_to_jiffies: - convert milliseconds to jiffies
566 * @m: time in milliseconds
567 *
568 * conversion is done as follows:
569 *
570 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
571 *
572 * - 'too large' values [that would result in larger than
573 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
574 *
575 * - all other values are converted to jiffies by either multiplying
576 * the input value by a factor or dividing it with a factor and
577 * handling any 32-bit overflows.
578 * for the details see __msecs_to_jiffies()
579 *
580 * msecs_to_jiffies() checks for the passed in value being a constant
581 * via __builtin_constant_p() allowing gcc to eliminate most of the
582 * code, __msecs_to_jiffies() is called if the value passed does not
583 * allow constant folding and the actual conversion must be done at
584 * runtime.
585 * the _msecs_to_jiffies helpers are the HZ dependent conversion
586 * routines found in include/linux/jiffies.h
587 */
588unsigned long __msecs_to_jiffies(const unsigned int m)
589{
590 /*
591 * Negative value, means infinite timeout:
592 */
593 if ((int)m < 0)
594 return MAX_JIFFY_OFFSET;
595 return _msecs_to_jiffies(m);
596}
597EXPORT_SYMBOL(__msecs_to_jiffies);
598
599unsigned long __usecs_to_jiffies(const unsigned int u)
600{
601 if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
602 return MAX_JIFFY_OFFSET;
603 return _usecs_to_jiffies(u);
604}
605EXPORT_SYMBOL(__usecs_to_jiffies);
606
607/*
608 * The TICK_NSEC - 1 rounds up the value to the next resolution. Note
609 * that a remainder subtract here would not do the right thing as the
610 * resolution values don't fall on second boundries. I.e. the line:
611 * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding.
612 * Note that due to the small error in the multiplier here, this
613 * rounding is incorrect for sufficiently large values of tv_nsec, but
614 * well formed timespecs should have tv_nsec < NSEC_PER_SEC, so we're
615 * OK.
616 *
617 * Rather, we just shift the bits off the right.
618 *
619 * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
620 * value to a scaled second value.
621 */
622static unsigned long
623__timespec64_to_jiffies(u64 sec, long nsec)
624{
625 nsec = nsec + TICK_NSEC - 1;
626
627 if (sec >= MAX_SEC_IN_JIFFIES){
628 sec = MAX_SEC_IN_JIFFIES;
629 nsec = 0;
630 }
631 return ((sec * SEC_CONVERSION) +
632 (((u64)nsec * NSEC_CONVERSION) >>
633 (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
634
635}
636
637static unsigned long
638__timespec_to_jiffies(unsigned long sec, long nsec)
639{
640 return __timespec64_to_jiffies((u64)sec, nsec);
641}
642
643unsigned long
644timespec64_to_jiffies(const struct timespec64 *value)
645{
646 return __timespec64_to_jiffies(value->tv_sec, value->tv_nsec);
647}
648EXPORT_SYMBOL(timespec64_to_jiffies);
649
650void
651jiffies_to_timespec64(const unsigned long jiffies, struct timespec64 *value)
652{
653 /*
654 * Convert jiffies to nanoseconds and separate with
655 * one divide.
656 */
657 u32 rem;
658 value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
659 NSEC_PER_SEC, &rem);
660 value->tv_nsec = rem;
661}
662EXPORT_SYMBOL(jiffies_to_timespec64);
663
664/*
665 * We could use a similar algorithm to timespec_to_jiffies (with a
666 * different multiplier for usec instead of nsec). But this has a
667 * problem with rounding: we can't exactly add TICK_NSEC - 1 to the
668 * usec value, since it's not necessarily integral.
669 *
670 * We could instead round in the intermediate scaled representation
671 * (i.e. in units of 1/2^(large scale) jiffies) but that's also
672 * perilous: the scaling introduces a small positive error, which
673 * combined with a division-rounding-upward (i.e. adding 2^(scale) - 1
674 * units to the intermediate before shifting) leads to accidental
675 * overflow and overestimates.
676 *
677 * At the cost of one additional multiplication by a constant, just
678 * use the timespec implementation.
679 */
680unsigned long
681timeval_to_jiffies(const struct timeval *value)
682{
683 return __timespec_to_jiffies(value->tv_sec,
684 value->tv_usec * NSEC_PER_USEC);
685}
686EXPORT_SYMBOL(timeval_to_jiffies);
687
688void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value)
689{
690 /*
691 * Convert jiffies to nanoseconds and separate with
692 * one divide.
693 */
694 u32 rem;
695
696 value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
697 NSEC_PER_SEC, &rem);
698 value->tv_usec = rem / NSEC_PER_USEC;
699}
700EXPORT_SYMBOL(jiffies_to_timeval);
701
702/*
703 * Convert jiffies/jiffies_64 to clock_t and back.
704 */
705clock_t jiffies_to_clock_t(unsigned long x)
706{
707#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
708# if HZ < USER_HZ
709 return x * (USER_HZ / HZ);
710# else
711 return x / (HZ / USER_HZ);
712# endif
713#else
714 return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
715#endif
716}
717EXPORT_SYMBOL(jiffies_to_clock_t);
718
719unsigned long clock_t_to_jiffies(unsigned long x)
720{
721#if (HZ % USER_HZ)==0
722 if (x >= ~0UL / (HZ / USER_HZ))
723 return ~0UL;
724 return x * (HZ / USER_HZ);
725#else
726 /* Don't worry about loss of precision here .. */
727 if (x >= ~0UL / HZ * USER_HZ)
728 return ~0UL;
729
730 /* .. but do try to contain it here */
731 return div_u64((u64)x * HZ, USER_HZ);
732#endif
733}
734EXPORT_SYMBOL(clock_t_to_jiffies);
735
736u64 jiffies_64_to_clock_t(u64 x)
737{
738#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
739# if HZ < USER_HZ
740 x = div_u64(x * USER_HZ, HZ);
741# elif HZ > USER_HZ
742 x = div_u64(x, HZ / USER_HZ);
743# else
744 /* Nothing to do */
745# endif
746#else
747 /*
748 * There are better ways that don't overflow early,
749 * but even this doesn't overflow in hundreds of years
750 * in 64 bits, so..
751 */
752 x = div_u64(x * TICK_NSEC, (NSEC_PER_SEC / USER_HZ));
753#endif
754 return x;
755}
756EXPORT_SYMBOL(jiffies_64_to_clock_t);
757
758u64 nsec_to_clock_t(u64 x)
759{
760#if (NSEC_PER_SEC % USER_HZ) == 0
761 return div_u64(x, NSEC_PER_SEC / USER_HZ);
762#elif (USER_HZ % 512) == 0
763 return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512);
764#else
765 /*
766 * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
767 * overflow after 64.99 years.
768 * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
769 */
770 return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ);
771#endif
772}
773
774u64 jiffies64_to_nsecs(u64 j)
775{
776#if !(NSEC_PER_SEC % HZ)
777 return (NSEC_PER_SEC / HZ) * j;
778# else
779 return div_u64(j * HZ_TO_NSEC_NUM, HZ_TO_NSEC_DEN);
780#endif
781}
782EXPORT_SYMBOL(jiffies64_to_nsecs);
783
784/**
785 * nsecs_to_jiffies64 - Convert nsecs in u64 to jiffies64
786 *
787 * @n: nsecs in u64
788 *
789 * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
790 * And this doesn't return MAX_JIFFY_OFFSET since this function is designed
791 * for scheduler, not for use in device drivers to calculate timeout value.
792 *
793 * note:
794 * NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
795 * ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
796 */
797u64 nsecs_to_jiffies64(u64 n)
798{
799#if (NSEC_PER_SEC % HZ) == 0
800 /* Common case, HZ = 100, 128, 200, 250, 256, 500, 512, 1000 etc. */
801 return div_u64(n, NSEC_PER_SEC / HZ);
802#elif (HZ % 512) == 0
803 /* overflow after 292 years if HZ = 1024 */
804 return div_u64(n * HZ / 512, NSEC_PER_SEC / 512);
805#else
806 /*
807 * Generic case - optimized for cases where HZ is a multiple of 3.
808 * overflow after 64.99 years, exact for HZ = 60, 72, 90, 120 etc.
809 */
810 return div_u64(n * 9, (9ull * NSEC_PER_SEC + HZ / 2) / HZ);
811#endif
812}
813EXPORT_SYMBOL(nsecs_to_jiffies64);
814
815/**
816 * nsecs_to_jiffies - Convert nsecs in u64 to jiffies
817 *
818 * @n: nsecs in u64
819 *
820 * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
821 * And this doesn't return MAX_JIFFY_OFFSET since this function is designed
822 * for scheduler, not for use in device drivers to calculate timeout value.
823 *
824 * note:
825 * NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
826 * ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
827 */
828unsigned long nsecs_to_jiffies(u64 n)
829{
830 return (unsigned long)nsecs_to_jiffies64(n);
831}
832EXPORT_SYMBOL_GPL(nsecs_to_jiffies);
833
834/*
835 * Add two timespec64 values and do a safety check for overflow.
836 * It's assumed that both values are valid (>= 0).
837 * And, each timespec64 is in normalized form.
838 */
839struct timespec64 timespec64_add_safe(const struct timespec64 lhs,
840 const struct timespec64 rhs)
841{
842 struct timespec64 res;
843
844 set_normalized_timespec64(&res, (timeu64_t) lhs.tv_sec + rhs.tv_sec,
845 lhs.tv_nsec + rhs.tv_nsec);
846
847 if (unlikely(res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec)) {
848 res.tv_sec = TIME64_MAX;
849 res.tv_nsec = 0;
850 }
851
852 return res;
853}
854
855int get_timespec64(struct timespec64 *ts,
856 const struct __kernel_timespec __user *uts)
857{
858 struct __kernel_timespec kts;
859 int ret;
860
861 ret = copy_from_user(&kts, uts, sizeof(kts));
862 if (ret)
863 return -EFAULT;
864
865 ts->tv_sec = kts.tv_sec;
866
867 /* Zero out the padding for 32 bit systems or in compat mode */
868 if (IS_ENABLED(CONFIG_64BIT_TIME) && (!IS_ENABLED(CONFIG_64BIT) || in_compat_syscall()))
869 kts.tv_nsec &= 0xFFFFFFFFUL;
870
871 ts->tv_nsec = kts.tv_nsec;
872
873 return 0;
874}
875EXPORT_SYMBOL_GPL(get_timespec64);
876
877int put_timespec64(const struct timespec64 *ts,
878 struct __kernel_timespec __user *uts)
879{
880 struct __kernel_timespec kts = {
881 .tv_sec = ts->tv_sec,
882 .tv_nsec = ts->tv_nsec
883 };
884
885 return copy_to_user(uts, &kts, sizeof(kts)) ? -EFAULT : 0;
886}
887EXPORT_SYMBOL_GPL(put_timespec64);
888
889int __compat_get_timespec64(struct timespec64 *ts64,
890 const struct compat_timespec __user *cts)
891{
892 struct compat_timespec ts;
893 int ret;
894
895 ret = copy_from_user(&ts, cts, sizeof(ts));
896 if (ret)
897 return -EFAULT;
898
899 ts64->tv_sec = ts.tv_sec;
900 ts64->tv_nsec = ts.tv_nsec;
901
902 return 0;
903}
904
905int __compat_put_timespec64(const struct timespec64 *ts64,
906 struct compat_timespec __user *cts)
907{
908 struct compat_timespec ts = {
909 .tv_sec = ts64->tv_sec,
910 .tv_nsec = ts64->tv_nsec
911 };
912 return copy_to_user(cts, &ts, sizeof(ts)) ? -EFAULT : 0;
913}
914
915int compat_get_timespec64(struct timespec64 *ts, const void __user *uts)
916{
917 if (COMPAT_USE_64BIT_TIME)
918 return copy_from_user(ts, uts, sizeof(*ts)) ? -EFAULT : 0;
919 else
920 return __compat_get_timespec64(ts, uts);
921}
922EXPORT_SYMBOL_GPL(compat_get_timespec64);
923
924int compat_put_timespec64(const struct timespec64 *ts, void __user *uts)
925{
926 if (COMPAT_USE_64BIT_TIME)
927 return copy_to_user(uts, ts, sizeof(*ts)) ? -EFAULT : 0;
928 else
929 return __compat_put_timespec64(ts, uts);
930}
931EXPORT_SYMBOL_GPL(compat_put_timespec64);
932
933int get_itimerspec64(struct itimerspec64 *it,
934 const struct itimerspec __user *uit)
935{
936 int ret;
937
938 ret = get_timespec64(&it->it_interval, &uit->it_interval);
939 if (ret)
940 return ret;
941
942 ret = get_timespec64(&it->it_value, &uit->it_value);
943
944 return ret;
945}
946EXPORT_SYMBOL_GPL(get_itimerspec64);
947
948int put_itimerspec64(const struct itimerspec64 *it,
949 struct itimerspec __user *uit)
950{
951 int ret;
952
953 ret = put_timespec64(&it->it_interval, &uit->it_interval);
954 if (ret)
955 return ret;
956
957 ret = put_timespec64(&it->it_value, &uit->it_value);
958
959 return ret;
960}
961EXPORT_SYMBOL_GPL(put_itimerspec64);