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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
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 timespec __user *uts)
857{
858 struct 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 ts->tv_nsec = kts.tv_nsec;
867
868 return 0;
869}
870EXPORT_SYMBOL_GPL(get_timespec64);
871
872int put_timespec64(const struct timespec64 *ts,
873 struct timespec __user *uts)
874{
875 struct timespec kts = {
876 .tv_sec = ts->tv_sec,
877 .tv_nsec = ts->tv_nsec
878 };
879 return copy_to_user(uts, &kts, sizeof(kts)) ? -EFAULT : 0;
880}
881EXPORT_SYMBOL_GPL(put_timespec64);
882
883int get_itimerspec64(struct itimerspec64 *it,
884 const struct itimerspec __user *uit)
885{
886 int ret;
887
888 ret = get_timespec64(&it->it_interval, &uit->it_interval);
889 if (ret)
890 return ret;
891
892 ret = get_timespec64(&it->it_value, &uit->it_value);
893
894 return ret;
895}
896EXPORT_SYMBOL_GPL(get_itimerspec64);
897
898int put_itimerspec64(const struct itimerspec64 *it,
899 struct itimerspec __user *uit)
900{
901 int ret;
902
903 ret = put_timespec64(&it->it_interval, &uit->it_interval);
904 if (ret)
905 return ret;
906
907 ret = put_timespec64(&it->it_value, &uit->it_value);
908
909 return ret;
910}
911EXPORT_SYMBOL_GPL(put_itimerspec64);