xref: /openbmc/linux/kernel/time/time.c (revision ff4a7481c3898ffc3cc271d6aca431d190c37247)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  Copyright (C) 1991, 1992  Linus Torvalds
4  *
5  *  This file contains the interface functions for the various time related
6  *  system calls: time, stime, gettimeofday, settimeofday, adjtime
7  *
8  * Modification history:
9  *
10  * 1993-09-02    Philip Gladstone
11  *      Created file with time related functions from sched/core.c and adjtimex()
12  * 1993-10-08    Torsten Duwe
13  *      adjtime interface update and CMOS clock write code
14  * 1995-08-13    Torsten Duwe
15  *      kernel PLL updated to 1994-12-13 specs (rfc-1589)
16  * 1999-01-16    Ulrich Windl
17  *	Introduced error checking for many cases in adjtimex().
18  *	Updated NTP code according to technical memorandum Jan '96
19  *	"A Kernel Model for Precision Timekeeping" by Dave Mills
20  *	Allow time_constant larger than MAXTC(6) for NTP v4 (MAXTC == 10)
21  *	(Even though the technical memorandum forbids it)
22  * 2004-07-14	 Christoph Lameter
23  *	Added getnstimeofday to allow the posix timer functions to return
24  *	with nanosecond accuracy
25  */
26 
27 #include <linux/export.h>
28 #include <linux/kernel.h>
29 #include <linux/timex.h>
30 #include <linux/capability.h>
31 #include <linux/timekeeper_internal.h>
32 #include <linux/errno.h>
33 #include <linux/syscalls.h>
34 #include <linux/security.h>
35 #include <linux/fs.h>
36 #include <linux/math64.h>
37 #include <linux/ptrace.h>
38 
39 #include <linux/uaccess.h>
40 #include <linux/compat.h>
41 #include <asm/unistd.h>
42 
43 #include <generated/timeconst.h>
44 #include "timekeeping.h"
45 
46 /*
47  * The timezone where the local system is located.  Used as a default by some
48  * programs who obtain this value by using gettimeofday.
49  */
50 struct timezone sys_tz;
51 
52 EXPORT_SYMBOL(sys_tz);
53 
54 #ifdef __ARCH_WANT_SYS_TIME
55 
56 /*
57  * sys_time() can be implemented in user-level using
58  * sys_gettimeofday().  Is this for backwards compatibility?  If so,
59  * why not move it into the appropriate arch directory (for those
60  * architectures that need it).
61  */
62 SYSCALL_DEFINE1(time, time_t __user *, tloc)
63 {
64 	time_t i = (time_t)ktime_get_real_seconds();
65 
66 	if (tloc) {
67 		if (put_user(i,tloc))
68 			return -EFAULT;
69 	}
70 	force_successful_syscall_return();
71 	return i;
72 }
73 
74 /*
75  * sys_stime() can be implemented in user-level using
76  * sys_settimeofday().  Is this for backwards compatibility?  If so,
77  * why not move it into the appropriate arch directory (for those
78  * architectures that need it).
79  */
80 
81 SYSCALL_DEFINE1(stime, time_t __user *, tptr)
82 {
83 	struct timespec64 tv;
84 	int err;
85 
86 	if (get_user(tv.tv_sec, tptr))
87 		return -EFAULT;
88 
89 	tv.tv_nsec = 0;
90 
91 	err = security_settime64(&tv, NULL);
92 	if (err)
93 		return err;
94 
95 	do_settimeofday64(&tv);
96 	return 0;
97 }
98 
99 #endif /* __ARCH_WANT_SYS_TIME */
100 
101 #ifdef CONFIG_COMPAT
102 #ifdef __ARCH_WANT_COMPAT_SYS_TIME
103 
104 /* old_time32_t is a 32 bit "long" and needs to get converted. */
105 COMPAT_SYSCALL_DEFINE1(time, old_time32_t __user *, tloc)
106 {
107 	old_time32_t i;
108 
109 	i = (old_time32_t)ktime_get_real_seconds();
110 
111 	if (tloc) {
112 		if (put_user(i,tloc))
113 			return -EFAULT;
114 	}
115 	force_successful_syscall_return();
116 	return i;
117 }
118 
119 COMPAT_SYSCALL_DEFINE1(stime, old_time32_t __user *, tptr)
120 {
121 	struct timespec64 tv;
122 	int err;
123 
124 	if (get_user(tv.tv_sec, tptr))
125 		return -EFAULT;
126 
127 	tv.tv_nsec = 0;
128 
129 	err = security_settime64(&tv, NULL);
130 	if (err)
131 		return err;
132 
133 	do_settimeofday64(&tv);
134 	return 0;
135 }
136 
137 #endif /* __ARCH_WANT_COMPAT_SYS_TIME */
138 #endif
139 
140 SYSCALL_DEFINE2(gettimeofday, struct timeval __user *, tv,
141 		struct timezone __user *, tz)
142 {
143 	if (likely(tv != NULL)) {
144 		struct timespec64 ts;
145 
146 		ktime_get_real_ts64(&ts);
147 		if (put_user(ts.tv_sec, &tv->tv_sec) ||
148 		    put_user(ts.tv_nsec / 1000, &tv->tv_usec))
149 			return -EFAULT;
150 	}
151 	if (unlikely(tz != NULL)) {
152 		if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
153 			return -EFAULT;
154 	}
155 	return 0;
156 }
157 
158 /*
159  * In case for some reason the CMOS clock has not already been running
160  * in UTC, but in some local time: The first time we set the timezone,
161  * we will warp the clock so that it is ticking UTC time instead of
162  * local time. Presumably, if someone is setting the timezone then we
163  * are running in an environment where the programs understand about
164  * timezones. This should be done at boot time in the /etc/rc script,
165  * as soon as possible, so that the clock can be set right. Otherwise,
166  * various programs will get confused when the clock gets warped.
167  */
168 
169 int do_sys_settimeofday64(const struct timespec64 *tv, const struct timezone *tz)
170 {
171 	static int firsttime = 1;
172 	int error = 0;
173 
174 	if (tv && !timespec64_valid(tv))
175 		return -EINVAL;
176 
177 	error = security_settime64(tv, tz);
178 	if (error)
179 		return error;
180 
181 	if (tz) {
182 		/* Verify we're witin the +-15 hrs range */
183 		if (tz->tz_minuteswest > 15*60 || tz->tz_minuteswest < -15*60)
184 			return -EINVAL;
185 
186 		sys_tz = *tz;
187 		update_vsyscall_tz();
188 		if (firsttime) {
189 			firsttime = 0;
190 			if (!tv)
191 				timekeeping_warp_clock();
192 		}
193 	}
194 	if (tv)
195 		return do_settimeofday64(tv);
196 	return 0;
197 }
198 
199 SYSCALL_DEFINE2(settimeofday, struct timeval __user *, tv,
200 		struct timezone __user *, tz)
201 {
202 	struct timespec64 new_ts;
203 	struct timeval user_tv;
204 	struct timezone new_tz;
205 
206 	if (tv) {
207 		if (copy_from_user(&user_tv, tv, sizeof(*tv)))
208 			return -EFAULT;
209 
210 		if (!timeval_valid(&user_tv))
211 			return -EINVAL;
212 
213 		new_ts.tv_sec = user_tv.tv_sec;
214 		new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
215 	}
216 	if (tz) {
217 		if (copy_from_user(&new_tz, tz, sizeof(*tz)))
218 			return -EFAULT;
219 	}
220 
221 	return do_sys_settimeofday64(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
222 }
223 
224 #ifdef CONFIG_COMPAT
225 COMPAT_SYSCALL_DEFINE2(gettimeofday, struct old_timeval32 __user *, tv,
226 		       struct timezone __user *, tz)
227 {
228 	if (tv) {
229 		struct timespec64 ts;
230 
231 		ktime_get_real_ts64(&ts);
232 		if (put_user(ts.tv_sec, &tv->tv_sec) ||
233 		    put_user(ts.tv_nsec / 1000, &tv->tv_usec))
234 			return -EFAULT;
235 	}
236 	if (tz) {
237 		if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
238 			return -EFAULT;
239 	}
240 
241 	return 0;
242 }
243 
244 COMPAT_SYSCALL_DEFINE2(settimeofday, struct old_timeval32 __user *, tv,
245 		       struct timezone __user *, tz)
246 {
247 	struct timespec64 new_ts;
248 	struct timeval user_tv;
249 	struct timezone new_tz;
250 
251 	if (tv) {
252 		if (compat_get_timeval(&user_tv, tv))
253 			return -EFAULT;
254 		new_ts.tv_sec = user_tv.tv_sec;
255 		new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
256 	}
257 	if (tz) {
258 		if (copy_from_user(&new_tz, tz, sizeof(*tz)))
259 			return -EFAULT;
260 	}
261 
262 	return do_sys_settimeofday64(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
263 }
264 #endif
265 
266 SYSCALL_DEFINE1(adjtimex, struct timex __user *, txc_p)
267 {
268 	struct timex txc;		/* Local copy of parameter */
269 	int ret;
270 
271 	/* Copy the user data space into the kernel copy
272 	 * structure. But bear in mind that the structures
273 	 * may change
274 	 */
275 	if (copy_from_user(&txc, txc_p, sizeof(struct timex)))
276 		return -EFAULT;
277 	ret = do_adjtimex(&txc);
278 	return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
279 }
280 
281 #ifdef CONFIG_COMPAT
282 
283 COMPAT_SYSCALL_DEFINE1(adjtimex, struct compat_timex __user *, utp)
284 {
285 	struct timex txc;
286 	int err, ret;
287 
288 	err = compat_get_timex(&txc, utp);
289 	if (err)
290 		return err;
291 
292 	ret = do_adjtimex(&txc);
293 
294 	err = compat_put_timex(utp, &txc);
295 	if (err)
296 		return err;
297 
298 	return ret;
299 }
300 #endif
301 
302 /*
303  * Convert jiffies to milliseconds and back.
304  *
305  * Avoid unnecessary multiplications/divisions in the
306  * two most common HZ cases:
307  */
308 unsigned int jiffies_to_msecs(const unsigned long j)
309 {
310 #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
311 	return (MSEC_PER_SEC / HZ) * j;
312 #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
313 	return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
314 #else
315 # if BITS_PER_LONG == 32
316 	return (HZ_TO_MSEC_MUL32 * j + (1ULL << HZ_TO_MSEC_SHR32) - 1) >>
317 	       HZ_TO_MSEC_SHR32;
318 # else
319 	return DIV_ROUND_UP(j * HZ_TO_MSEC_NUM, HZ_TO_MSEC_DEN);
320 # endif
321 #endif
322 }
323 EXPORT_SYMBOL(jiffies_to_msecs);
324 
325 unsigned 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 }
343 EXPORT_SYMBOL(jiffies_to_usecs);
344 
345 /*
346  * mktime64 - Converts date to seconds.
347  * Converts Gregorian date to seconds since 1970-01-01 00:00:00.
348  * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
349  * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
350  *
351  * [For the Julian calendar (which was used in Russia before 1917,
352  * Britain & colonies before 1752, anywhere else before 1582,
353  * and is still in use by some communities) leave out the
354  * -year/100+year/400 terms, and add 10.]
355  *
356  * This algorithm was first published by Gauss (I think).
357  *
358  * A leap second can be indicated by calling this function with sec as
359  * 60 (allowable under ISO 8601).  The leap second is treated the same
360  * as the following second since they don't exist in UNIX time.
361  *
362  * An encoding of midnight at the end of the day as 24:00:00 - ie. midnight
363  * tomorrow - (allowable under ISO 8601) is supported.
364  */
365 time64_t mktime64(const unsigned int year0, const unsigned int mon0,
366 		const unsigned int day, const unsigned int hour,
367 		const unsigned int min, const unsigned int sec)
368 {
369 	unsigned int mon = mon0, year = year0;
370 
371 	/* 1..12 -> 11,12,1..10 */
372 	if (0 >= (int) (mon -= 2)) {
373 		mon += 12;	/* Puts Feb last since it has leap day */
374 		year -= 1;
375 	}
376 
377 	return ((((time64_t)
378 		  (year/4 - year/100 + year/400 + 367*mon/12 + day) +
379 		  year*365 - 719499
380 	    )*24 + hour /* now have hours - midnight tomorrow handled here */
381 	  )*60 + min /* now have minutes */
382 	)*60 + sec; /* finally seconds */
383 }
384 EXPORT_SYMBOL(mktime64);
385 
386 /**
387  * set_normalized_timespec - set timespec sec and nsec parts and normalize
388  *
389  * @ts:		pointer to timespec variable to be set
390  * @sec:	seconds to set
391  * @nsec:	nanoseconds to set
392  *
393  * Set seconds and nanoseconds field of a timespec variable and
394  * normalize to the timespec storage format
395  *
396  * Note: The tv_nsec part is always in the range of
397  *	0 <= tv_nsec < NSEC_PER_SEC
398  * For negative values only the tv_sec field is negative !
399  */
400 void set_normalized_timespec(struct timespec *ts, time_t sec, s64 nsec)
401 {
402 	while (nsec >= NSEC_PER_SEC) {
403 		/*
404 		 * The following asm() prevents the compiler from
405 		 * optimising this loop into a modulo operation. See
406 		 * also __iter_div_u64_rem() in include/linux/time.h
407 		 */
408 		asm("" : "+rm"(nsec));
409 		nsec -= NSEC_PER_SEC;
410 		++sec;
411 	}
412 	while (nsec < 0) {
413 		asm("" : "+rm"(nsec));
414 		nsec += NSEC_PER_SEC;
415 		--sec;
416 	}
417 	ts->tv_sec = sec;
418 	ts->tv_nsec = nsec;
419 }
420 EXPORT_SYMBOL(set_normalized_timespec);
421 
422 /**
423  * ns_to_timespec - Convert nanoseconds to timespec
424  * @nsec:       the nanoseconds value to be converted
425  *
426  * Returns the timespec representation of the nsec parameter.
427  */
428 struct timespec ns_to_timespec(const s64 nsec)
429 {
430 	struct timespec ts;
431 	s32 rem;
432 
433 	if (!nsec)
434 		return (struct timespec) {0, 0};
435 
436 	ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
437 	if (unlikely(rem < 0)) {
438 		ts.tv_sec--;
439 		rem += NSEC_PER_SEC;
440 	}
441 	ts.tv_nsec = rem;
442 
443 	return ts;
444 }
445 EXPORT_SYMBOL(ns_to_timespec);
446 
447 /**
448  * ns_to_timeval - Convert nanoseconds to timeval
449  * @nsec:       the nanoseconds value to be converted
450  *
451  * Returns the timeval representation of the nsec parameter.
452  */
453 struct timeval ns_to_timeval(const s64 nsec)
454 {
455 	struct timespec ts = ns_to_timespec(nsec);
456 	struct timeval tv;
457 
458 	tv.tv_sec = ts.tv_sec;
459 	tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000;
460 
461 	return tv;
462 }
463 EXPORT_SYMBOL(ns_to_timeval);
464 
465 struct __kernel_old_timeval ns_to_kernel_old_timeval(const s64 nsec)
466 {
467 	struct timespec64 ts = ns_to_timespec64(nsec);
468 	struct __kernel_old_timeval tv;
469 
470 	tv.tv_sec = ts.tv_sec;
471 	tv.tv_usec = (suseconds_t)ts.tv_nsec / 1000;
472 
473 	return tv;
474 }
475 EXPORT_SYMBOL(ns_to_kernel_old_timeval);
476 
477 /**
478  * set_normalized_timespec - set timespec sec and nsec parts and normalize
479  *
480  * @ts:		pointer to timespec variable to be set
481  * @sec:	seconds to set
482  * @nsec:	nanoseconds to set
483  *
484  * Set seconds and nanoseconds field of a timespec variable and
485  * normalize to the timespec storage format
486  *
487  * Note: The tv_nsec part is always in the range of
488  *	0 <= tv_nsec < NSEC_PER_SEC
489  * For negative values only the tv_sec field is negative !
490  */
491 void set_normalized_timespec64(struct timespec64 *ts, time64_t sec, s64 nsec)
492 {
493 	while (nsec >= NSEC_PER_SEC) {
494 		/*
495 		 * The following asm() prevents the compiler from
496 		 * optimising this loop into a modulo operation. See
497 		 * also __iter_div_u64_rem() in include/linux/time.h
498 		 */
499 		asm("" : "+rm"(nsec));
500 		nsec -= NSEC_PER_SEC;
501 		++sec;
502 	}
503 	while (nsec < 0) {
504 		asm("" : "+rm"(nsec));
505 		nsec += NSEC_PER_SEC;
506 		--sec;
507 	}
508 	ts->tv_sec = sec;
509 	ts->tv_nsec = nsec;
510 }
511 EXPORT_SYMBOL(set_normalized_timespec64);
512 
513 /**
514  * ns_to_timespec64 - Convert nanoseconds to timespec64
515  * @nsec:       the nanoseconds value to be converted
516  *
517  * Returns the timespec64 representation of the nsec parameter.
518  */
519 struct timespec64 ns_to_timespec64(const s64 nsec)
520 {
521 	struct timespec64 ts;
522 	s32 rem;
523 
524 	if (!nsec)
525 		return (struct timespec64) {0, 0};
526 
527 	ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
528 	if (unlikely(rem < 0)) {
529 		ts.tv_sec--;
530 		rem += NSEC_PER_SEC;
531 	}
532 	ts.tv_nsec = rem;
533 
534 	return ts;
535 }
536 EXPORT_SYMBOL(ns_to_timespec64);
537 
538 /**
539  * msecs_to_jiffies: - convert milliseconds to jiffies
540  * @m:	time in milliseconds
541  *
542  * conversion is done as follows:
543  *
544  * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
545  *
546  * - 'too large' values [that would result in larger than
547  *   MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
548  *
549  * - all other values are converted to jiffies by either multiplying
550  *   the input value by a factor or dividing it with a factor and
551  *   handling any 32-bit overflows.
552  *   for the details see __msecs_to_jiffies()
553  *
554  * msecs_to_jiffies() checks for the passed in value being a constant
555  * via __builtin_constant_p() allowing gcc to eliminate most of the
556  * code, __msecs_to_jiffies() is called if the value passed does not
557  * allow constant folding and the actual conversion must be done at
558  * runtime.
559  * the _msecs_to_jiffies helpers are the HZ dependent conversion
560  * routines found in include/linux/jiffies.h
561  */
562 unsigned long __msecs_to_jiffies(const unsigned int m)
563 {
564 	/*
565 	 * Negative value, means infinite timeout:
566 	 */
567 	if ((int)m < 0)
568 		return MAX_JIFFY_OFFSET;
569 	return _msecs_to_jiffies(m);
570 }
571 EXPORT_SYMBOL(__msecs_to_jiffies);
572 
573 unsigned long __usecs_to_jiffies(const unsigned int u)
574 {
575 	if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
576 		return MAX_JIFFY_OFFSET;
577 	return _usecs_to_jiffies(u);
578 }
579 EXPORT_SYMBOL(__usecs_to_jiffies);
580 
581 /*
582  * The TICK_NSEC - 1 rounds up the value to the next resolution.  Note
583  * that a remainder subtract here would not do the right thing as the
584  * resolution values don't fall on second boundries.  I.e. the line:
585  * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding.
586  * Note that due to the small error in the multiplier here, this
587  * rounding is incorrect for sufficiently large values of tv_nsec, but
588  * well formed timespecs should have tv_nsec < NSEC_PER_SEC, so we're
589  * OK.
590  *
591  * Rather, we just shift the bits off the right.
592  *
593  * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
594  * value to a scaled second value.
595  */
596 static unsigned long
597 __timespec64_to_jiffies(u64 sec, long nsec)
598 {
599 	nsec = nsec + TICK_NSEC - 1;
600 
601 	if (sec >= MAX_SEC_IN_JIFFIES){
602 		sec = MAX_SEC_IN_JIFFIES;
603 		nsec = 0;
604 	}
605 	return ((sec * SEC_CONVERSION) +
606 		(((u64)nsec * NSEC_CONVERSION) >>
607 		 (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
608 
609 }
610 
611 static unsigned long
612 __timespec_to_jiffies(unsigned long sec, long nsec)
613 {
614 	return __timespec64_to_jiffies((u64)sec, nsec);
615 }
616 
617 unsigned long
618 timespec64_to_jiffies(const struct timespec64 *value)
619 {
620 	return __timespec64_to_jiffies(value->tv_sec, value->tv_nsec);
621 }
622 EXPORT_SYMBOL(timespec64_to_jiffies);
623 
624 void
625 jiffies_to_timespec64(const unsigned long jiffies, struct timespec64 *value)
626 {
627 	/*
628 	 * Convert jiffies to nanoseconds and separate with
629 	 * one divide.
630 	 */
631 	u32 rem;
632 	value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
633 				    NSEC_PER_SEC, &rem);
634 	value->tv_nsec = rem;
635 }
636 EXPORT_SYMBOL(jiffies_to_timespec64);
637 
638 /*
639  * We could use a similar algorithm to timespec_to_jiffies (with a
640  * different multiplier for usec instead of nsec). But this has a
641  * problem with rounding: we can't exactly add TICK_NSEC - 1 to the
642  * usec value, since it's not necessarily integral.
643  *
644  * We could instead round in the intermediate scaled representation
645  * (i.e. in units of 1/2^(large scale) jiffies) but that's also
646  * perilous: the scaling introduces a small positive error, which
647  * combined with a division-rounding-upward (i.e. adding 2^(scale) - 1
648  * units to the intermediate before shifting) leads to accidental
649  * overflow and overestimates.
650  *
651  * At the cost of one additional multiplication by a constant, just
652  * use the timespec implementation.
653  */
654 unsigned long
655 timeval_to_jiffies(const struct timeval *value)
656 {
657 	return __timespec_to_jiffies(value->tv_sec,
658 				     value->tv_usec * NSEC_PER_USEC);
659 }
660 EXPORT_SYMBOL(timeval_to_jiffies);
661 
662 void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value)
663 {
664 	/*
665 	 * Convert jiffies to nanoseconds and separate with
666 	 * one divide.
667 	 */
668 	u32 rem;
669 
670 	value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
671 				    NSEC_PER_SEC, &rem);
672 	value->tv_usec = rem / NSEC_PER_USEC;
673 }
674 EXPORT_SYMBOL(jiffies_to_timeval);
675 
676 /*
677  * Convert jiffies/jiffies_64 to clock_t and back.
678  */
679 clock_t jiffies_to_clock_t(unsigned long x)
680 {
681 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
682 # if HZ < USER_HZ
683 	return x * (USER_HZ / HZ);
684 # else
685 	return x / (HZ / USER_HZ);
686 # endif
687 #else
688 	return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
689 #endif
690 }
691 EXPORT_SYMBOL(jiffies_to_clock_t);
692 
693 unsigned long clock_t_to_jiffies(unsigned long x)
694 {
695 #if (HZ % USER_HZ)==0
696 	if (x >= ~0UL / (HZ / USER_HZ))
697 		return ~0UL;
698 	return x * (HZ / USER_HZ);
699 #else
700 	/* Don't worry about loss of precision here .. */
701 	if (x >= ~0UL / HZ * USER_HZ)
702 		return ~0UL;
703 
704 	/* .. but do try to contain it here */
705 	return div_u64((u64)x * HZ, USER_HZ);
706 #endif
707 }
708 EXPORT_SYMBOL(clock_t_to_jiffies);
709 
710 u64 jiffies_64_to_clock_t(u64 x)
711 {
712 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
713 # if HZ < USER_HZ
714 	x = div_u64(x * USER_HZ, HZ);
715 # elif HZ > USER_HZ
716 	x = div_u64(x, HZ / USER_HZ);
717 # else
718 	/* Nothing to do */
719 # endif
720 #else
721 	/*
722 	 * There are better ways that don't overflow early,
723 	 * but even this doesn't overflow in hundreds of years
724 	 * in 64 bits, so..
725 	 */
726 	x = div_u64(x * TICK_NSEC, (NSEC_PER_SEC / USER_HZ));
727 #endif
728 	return x;
729 }
730 EXPORT_SYMBOL(jiffies_64_to_clock_t);
731 
732 u64 nsec_to_clock_t(u64 x)
733 {
734 #if (NSEC_PER_SEC % USER_HZ) == 0
735 	return div_u64(x, NSEC_PER_SEC / USER_HZ);
736 #elif (USER_HZ % 512) == 0
737 	return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512);
738 #else
739 	/*
740          * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
741          * overflow after 64.99 years.
742          * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
743          */
744 	return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ);
745 #endif
746 }
747 
748 u64 jiffies64_to_nsecs(u64 j)
749 {
750 #if !(NSEC_PER_SEC % HZ)
751 	return (NSEC_PER_SEC / HZ) * j;
752 # else
753 	return div_u64(j * HZ_TO_NSEC_NUM, HZ_TO_NSEC_DEN);
754 #endif
755 }
756 EXPORT_SYMBOL(jiffies64_to_nsecs);
757 
758 /**
759  * nsecs_to_jiffies64 - Convert nsecs in u64 to jiffies64
760  *
761  * @n:	nsecs in u64
762  *
763  * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
764  * And this doesn't return MAX_JIFFY_OFFSET since this function is designed
765  * for scheduler, not for use in device drivers to calculate timeout value.
766  *
767  * note:
768  *   NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
769  *   ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
770  */
771 u64 nsecs_to_jiffies64(u64 n)
772 {
773 #if (NSEC_PER_SEC % HZ) == 0
774 	/* Common case, HZ = 100, 128, 200, 250, 256, 500, 512, 1000 etc. */
775 	return div_u64(n, NSEC_PER_SEC / HZ);
776 #elif (HZ % 512) == 0
777 	/* overflow after 292 years if HZ = 1024 */
778 	return div_u64(n * HZ / 512, NSEC_PER_SEC / 512);
779 #else
780 	/*
781 	 * Generic case - optimized for cases where HZ is a multiple of 3.
782 	 * overflow after 64.99 years, exact for HZ = 60, 72, 90, 120 etc.
783 	 */
784 	return div_u64(n * 9, (9ull * NSEC_PER_SEC + HZ / 2) / HZ);
785 #endif
786 }
787 EXPORT_SYMBOL(nsecs_to_jiffies64);
788 
789 /**
790  * nsecs_to_jiffies - Convert nsecs in u64 to jiffies
791  *
792  * @n:	nsecs in u64
793  *
794  * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
795  * And this doesn't return MAX_JIFFY_OFFSET since this function is designed
796  * for scheduler, not for use in device drivers to calculate timeout value.
797  *
798  * note:
799  *   NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
800  *   ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
801  */
802 unsigned long nsecs_to_jiffies(u64 n)
803 {
804 	return (unsigned long)nsecs_to_jiffies64(n);
805 }
806 EXPORT_SYMBOL_GPL(nsecs_to_jiffies);
807 
808 /*
809  * Add two timespec64 values and do a safety check for overflow.
810  * It's assumed that both values are valid (>= 0).
811  * And, each timespec64 is in normalized form.
812  */
813 struct timespec64 timespec64_add_safe(const struct timespec64 lhs,
814 				const struct timespec64 rhs)
815 {
816 	struct timespec64 res;
817 
818 	set_normalized_timespec64(&res, (timeu64_t) lhs.tv_sec + rhs.tv_sec,
819 			lhs.tv_nsec + rhs.tv_nsec);
820 
821 	if (unlikely(res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec)) {
822 		res.tv_sec = TIME64_MAX;
823 		res.tv_nsec = 0;
824 	}
825 
826 	return res;
827 }
828 
829 int get_timespec64(struct timespec64 *ts,
830 		   const struct __kernel_timespec __user *uts)
831 {
832 	struct __kernel_timespec kts;
833 	int ret;
834 
835 	ret = copy_from_user(&kts, uts, sizeof(kts));
836 	if (ret)
837 		return -EFAULT;
838 
839 	ts->tv_sec = kts.tv_sec;
840 
841 	/* Zero out the padding for 32 bit systems or in compat mode */
842 	if (IS_ENABLED(CONFIG_64BIT_TIME) && in_compat_syscall())
843 		kts.tv_nsec &= 0xFFFFFFFFUL;
844 
845 	ts->tv_nsec = kts.tv_nsec;
846 
847 	return 0;
848 }
849 EXPORT_SYMBOL_GPL(get_timespec64);
850 
851 int put_timespec64(const struct timespec64 *ts,
852 		   struct __kernel_timespec __user *uts)
853 {
854 	struct __kernel_timespec kts = {
855 		.tv_sec = ts->tv_sec,
856 		.tv_nsec = ts->tv_nsec
857 	};
858 
859 	return copy_to_user(uts, &kts, sizeof(kts)) ? -EFAULT : 0;
860 }
861 EXPORT_SYMBOL_GPL(put_timespec64);
862 
863 static int __get_old_timespec32(struct timespec64 *ts64,
864 				   const struct old_timespec32 __user *cts)
865 {
866 	struct old_timespec32 ts;
867 	int ret;
868 
869 	ret = copy_from_user(&ts, cts, sizeof(ts));
870 	if (ret)
871 		return -EFAULT;
872 
873 	ts64->tv_sec = ts.tv_sec;
874 	ts64->tv_nsec = ts.tv_nsec;
875 
876 	return 0;
877 }
878 
879 static int __put_old_timespec32(const struct timespec64 *ts64,
880 				   struct old_timespec32 __user *cts)
881 {
882 	struct old_timespec32 ts = {
883 		.tv_sec = ts64->tv_sec,
884 		.tv_nsec = ts64->tv_nsec
885 	};
886 	return copy_to_user(cts, &ts, sizeof(ts)) ? -EFAULT : 0;
887 }
888 
889 int get_old_timespec32(struct timespec64 *ts, const void __user *uts)
890 {
891 	if (COMPAT_USE_64BIT_TIME)
892 		return copy_from_user(ts, uts, sizeof(*ts)) ? -EFAULT : 0;
893 	else
894 		return __get_old_timespec32(ts, uts);
895 }
896 EXPORT_SYMBOL_GPL(get_old_timespec32);
897 
898 int put_old_timespec32(const struct timespec64 *ts, void __user *uts)
899 {
900 	if (COMPAT_USE_64BIT_TIME)
901 		return copy_to_user(uts, ts, sizeof(*ts)) ? -EFAULT : 0;
902 	else
903 		return __put_old_timespec32(ts, uts);
904 }
905 EXPORT_SYMBOL_GPL(put_old_timespec32);
906 
907 int get_itimerspec64(struct itimerspec64 *it,
908 			const struct __kernel_itimerspec __user *uit)
909 {
910 	int ret;
911 
912 	ret = get_timespec64(&it->it_interval, &uit->it_interval);
913 	if (ret)
914 		return ret;
915 
916 	ret = get_timespec64(&it->it_value, &uit->it_value);
917 
918 	return ret;
919 }
920 EXPORT_SYMBOL_GPL(get_itimerspec64);
921 
922 int put_itimerspec64(const struct itimerspec64 *it,
923 			struct __kernel_itimerspec __user *uit)
924 {
925 	int ret;
926 
927 	ret = put_timespec64(&it->it_interval, &uit->it_interval);
928 	if (ret)
929 		return ret;
930 
931 	ret = put_timespec64(&it->it_value, &uit->it_value);
932 
933 	return ret;
934 }
935 EXPORT_SYMBOL_GPL(put_itimerspec64);
936 
937 int get_old_itimerspec32(struct itimerspec64 *its,
938 			const struct old_itimerspec32 __user *uits)
939 {
940 
941 	if (__get_old_timespec32(&its->it_interval, &uits->it_interval) ||
942 	    __get_old_timespec32(&its->it_value, &uits->it_value))
943 		return -EFAULT;
944 	return 0;
945 }
946 EXPORT_SYMBOL_GPL(get_old_itimerspec32);
947 
948 int put_old_itimerspec32(const struct itimerspec64 *its,
949 			struct old_itimerspec32 __user *uits)
950 {
951 	if (__put_old_timespec32(&its->it_interval, &uits->it_interval) ||
952 	    __put_old_timespec32(&its->it_value, &uits->it_value))
953 		return -EFAULT;
954 	return 0;
955 }
956 EXPORT_SYMBOL_GPL(put_old_itimerspec32);
957