xref: /linux/kernel/time/time.c (revision fcb3ad4366b9c810cbb9da34c076a9a52d8aa1e0)
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, __kernel_old_time_t __user *, tloc)
63 {
64 	__kernel_old_time_t i = (__kernel_old_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, __kernel_old_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_32BIT_TIME
102 #ifdef __ARCH_WANT_SYS_TIME32
103 
104 /* old_time32_t is a 32 bit "long" and needs to get converted. */
105 SYSCALL_DEFINE1(time32, 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 SYSCALL_DEFINE1(stime32, 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_SYS_TIME32 */
138 #endif
139 
140 SYSCALL_DEFINE2(gettimeofday, struct __kernel_old_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_settod(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 within 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 __kernel_old_timeval __user *, tv,
200 		struct timezone __user *, tz)
201 {
202 	struct timespec64 new_ts;
203 	struct timezone new_tz;
204 
205 	if (tv) {
206 		if (get_user(new_ts.tv_sec, &tv->tv_sec) ||
207 		    get_user(new_ts.tv_nsec, &tv->tv_usec))
208 			return -EFAULT;
209 
210 		if (new_ts.tv_nsec > USEC_PER_SEC || new_ts.tv_nsec < 0)
211 			return -EINVAL;
212 
213 		new_ts.tv_nsec *= NSEC_PER_USEC;
214 	}
215 	if (tz) {
216 		if (copy_from_user(&new_tz, tz, sizeof(*tz)))
217 			return -EFAULT;
218 	}
219 
220 	return do_sys_settimeofday64(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
221 }
222 
223 #ifdef CONFIG_COMPAT
224 COMPAT_SYSCALL_DEFINE2(gettimeofday, struct old_timeval32 __user *, tv,
225 		       struct timezone __user *, tz)
226 {
227 	if (tv) {
228 		struct timespec64 ts;
229 
230 		ktime_get_real_ts64(&ts);
231 		if (put_user(ts.tv_sec, &tv->tv_sec) ||
232 		    put_user(ts.tv_nsec / 1000, &tv->tv_usec))
233 			return -EFAULT;
234 	}
235 	if (tz) {
236 		if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
237 			return -EFAULT;
238 	}
239 
240 	return 0;
241 }
242 
243 COMPAT_SYSCALL_DEFINE2(settimeofday, struct old_timeval32 __user *, tv,
244 		       struct timezone __user *, tz)
245 {
246 	struct timespec64 new_ts;
247 	struct timezone new_tz;
248 
249 	if (tv) {
250 		if (get_user(new_ts.tv_sec, &tv->tv_sec) ||
251 		    get_user(new_ts.tv_nsec, &tv->tv_usec))
252 			return -EFAULT;
253 
254 		if (new_ts.tv_nsec > USEC_PER_SEC || new_ts.tv_nsec < 0)
255 			return -EINVAL;
256 
257 		new_ts.tv_nsec *= 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 
268 #ifdef CONFIG_64BIT
269 SYSCALL_DEFINE1(adjtimex, struct __kernel_timex __user *, txc_p)
270 {
271 	struct __kernel_timex txc;		/* Local copy of parameter */
272 	int ret;
273 
274 	/* Copy the user data space into the kernel copy
275 	 * structure. But bear in mind that the structures
276 	 * may change
277 	 */
278 	if (copy_from_user(&txc, txc_p, sizeof(struct __kernel_timex)))
279 		return -EFAULT;
280 	ret = do_adjtimex(&txc);
281 	return copy_to_user(txc_p, &txc, sizeof(struct __kernel_timex)) ? -EFAULT : ret;
282 }
283 #endif
284 
285 #ifdef CONFIG_COMPAT_32BIT_TIME
286 int get_old_timex32(struct __kernel_timex *txc, const struct old_timex32 __user *utp)
287 {
288 	struct old_timex32 tx32;
289 
290 	memset(txc, 0, sizeof(struct __kernel_timex));
291 	if (copy_from_user(&tx32, utp, sizeof(struct old_timex32)))
292 		return -EFAULT;
293 
294 	txc->modes = tx32.modes;
295 	txc->offset = tx32.offset;
296 	txc->freq = tx32.freq;
297 	txc->maxerror = tx32.maxerror;
298 	txc->esterror = tx32.esterror;
299 	txc->status = tx32.status;
300 	txc->constant = tx32.constant;
301 	txc->precision = tx32.precision;
302 	txc->tolerance = tx32.tolerance;
303 	txc->time.tv_sec = tx32.time.tv_sec;
304 	txc->time.tv_usec = tx32.time.tv_usec;
305 	txc->tick = tx32.tick;
306 	txc->ppsfreq = tx32.ppsfreq;
307 	txc->jitter = tx32.jitter;
308 	txc->shift = tx32.shift;
309 	txc->stabil = tx32.stabil;
310 	txc->jitcnt = tx32.jitcnt;
311 	txc->calcnt = tx32.calcnt;
312 	txc->errcnt = tx32.errcnt;
313 	txc->stbcnt = tx32.stbcnt;
314 
315 	return 0;
316 }
317 
318 int put_old_timex32(struct old_timex32 __user *utp, const struct __kernel_timex *txc)
319 {
320 	struct old_timex32 tx32;
321 
322 	memset(&tx32, 0, sizeof(struct old_timex32));
323 	tx32.modes = txc->modes;
324 	tx32.offset = txc->offset;
325 	tx32.freq = txc->freq;
326 	tx32.maxerror = txc->maxerror;
327 	tx32.esterror = txc->esterror;
328 	tx32.status = txc->status;
329 	tx32.constant = txc->constant;
330 	tx32.precision = txc->precision;
331 	tx32.tolerance = txc->tolerance;
332 	tx32.time.tv_sec = txc->time.tv_sec;
333 	tx32.time.tv_usec = txc->time.tv_usec;
334 	tx32.tick = txc->tick;
335 	tx32.ppsfreq = txc->ppsfreq;
336 	tx32.jitter = txc->jitter;
337 	tx32.shift = txc->shift;
338 	tx32.stabil = txc->stabil;
339 	tx32.jitcnt = txc->jitcnt;
340 	tx32.calcnt = txc->calcnt;
341 	tx32.errcnt = txc->errcnt;
342 	tx32.stbcnt = txc->stbcnt;
343 	tx32.tai = txc->tai;
344 	if (copy_to_user(utp, &tx32, sizeof(struct old_timex32)))
345 		return -EFAULT;
346 	return 0;
347 }
348 
349 SYSCALL_DEFINE1(adjtimex_time32, struct old_timex32 __user *, utp)
350 {
351 	struct __kernel_timex txc;
352 	int err, ret;
353 
354 	err = get_old_timex32(&txc, utp);
355 	if (err)
356 		return err;
357 
358 	ret = do_adjtimex(&txc);
359 
360 	err = put_old_timex32(utp, &txc);
361 	if (err)
362 		return err;
363 
364 	return ret;
365 }
366 #endif
367 
368 /**
369  * jiffies_to_msecs - Convert jiffies to milliseconds
370  * @j: jiffies value
371  *
372  * Avoid unnecessary multiplications/divisions in the
373  * two most common HZ cases.
374  *
375  * Return: milliseconds value
376  */
377 unsigned int jiffies_to_msecs(const unsigned long j)
378 {
379 #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
380 	return (MSEC_PER_SEC / HZ) * j;
381 #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
382 	return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
383 #else
384 # if BITS_PER_LONG == 32
385 	return (HZ_TO_MSEC_MUL32 * j + (1ULL << HZ_TO_MSEC_SHR32) - 1) >>
386 	       HZ_TO_MSEC_SHR32;
387 # else
388 	return DIV_ROUND_UP(j * HZ_TO_MSEC_NUM, HZ_TO_MSEC_DEN);
389 # endif
390 #endif
391 }
392 EXPORT_SYMBOL(jiffies_to_msecs);
393 
394 /**
395  * jiffies_to_usecs - Convert jiffies to microseconds
396  * @j: jiffies value
397  *
398  * Return: microseconds value
399  */
400 unsigned int jiffies_to_usecs(const unsigned long j)
401 {
402 	/*
403 	 * Hz usually doesn't go much further MSEC_PER_SEC.
404 	 * jiffies_to_usecs() and usecs_to_jiffies() depend on that.
405 	 */
406 	BUILD_BUG_ON(HZ > USEC_PER_SEC);
407 
408 #if !(USEC_PER_SEC % HZ)
409 	return (USEC_PER_SEC / HZ) * j;
410 #else
411 # if BITS_PER_LONG == 32
412 	return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32;
413 # else
414 	return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN;
415 # endif
416 #endif
417 }
418 EXPORT_SYMBOL(jiffies_to_usecs);
419 
420 /**
421  * mktime64 - Converts date to seconds.
422  * @year0: year to convert
423  * @mon0: month to convert
424  * @day: day to convert
425  * @hour: hour to convert
426  * @min: minute to convert
427  * @sec: second to convert
428  *
429  * Converts Gregorian date to seconds since 1970-01-01 00:00:00.
430  * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
431  * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
432  *
433  * [For the Julian calendar (which was used in Russia before 1917,
434  * Britain & colonies before 1752, anywhere else before 1582,
435  * and is still in use by some communities) leave out the
436  * -year/100+year/400 terms, and add 10.]
437  *
438  * This algorithm was first published by Gauss (I think).
439  *
440  * A leap second can be indicated by calling this function with sec as
441  * 60 (allowable under ISO 8601).  The leap second is treated the same
442  * as the following second since they don't exist in UNIX time.
443  *
444  * An encoding of midnight at the end of the day as 24:00:00 - ie. midnight
445  * tomorrow - (allowable under ISO 8601) is supported.
446  *
447  * Return: seconds since the epoch time for the given input date
448  */
449 time64_t mktime64(const unsigned int year0, const unsigned int mon0,
450 		const unsigned int day, const unsigned int hour,
451 		const unsigned int min, const unsigned int sec)
452 {
453 	unsigned int mon = mon0, year = year0;
454 
455 	/* 1..12 -> 11,12,1..10 */
456 	if (0 >= (int) (mon -= 2)) {
457 		mon += 12;	/* Puts Feb last since it has leap day */
458 		year -= 1;
459 	}
460 
461 	return ((((time64_t)
462 		  (year/4 - year/100 + year/400 + 367*mon/12 + day) +
463 		  year*365 - 719499
464 	    )*24 + hour /* now have hours - midnight tomorrow handled here */
465 	  )*60 + min /* now have minutes */
466 	)*60 + sec; /* finally seconds */
467 }
468 EXPORT_SYMBOL(mktime64);
469 
470 struct __kernel_old_timeval ns_to_kernel_old_timeval(s64 nsec)
471 {
472 	struct timespec64 ts = ns_to_timespec64(nsec);
473 	struct __kernel_old_timeval tv;
474 
475 	tv.tv_sec = ts.tv_sec;
476 	tv.tv_usec = (suseconds_t)ts.tv_nsec / 1000;
477 
478 	return tv;
479 }
480 EXPORT_SYMBOL(ns_to_kernel_old_timeval);
481 
482 /**
483  * set_normalized_timespec64 - set timespec sec and nsec parts and normalize
484  *
485  * @ts:		pointer to timespec variable to be set
486  * @sec:	seconds to set
487  * @nsec:	nanoseconds to set
488  *
489  * Set seconds and nanoseconds field of a timespec variable and
490  * normalize to the timespec storage format
491  *
492  * Note: The tv_nsec part is always in the range of 0 <= tv_nsec < NSEC_PER_SEC.
493  * For negative values only the tv_sec field is negative !
494  */
495 void set_normalized_timespec64(struct timespec64 *ts, time64_t sec, s64 nsec)
496 {
497 	while (nsec >= NSEC_PER_SEC) {
498 		/*
499 		 * The following asm() prevents the compiler from
500 		 * optimising this loop into a modulo operation. See
501 		 * also __iter_div_u64_rem() in include/linux/time.h
502 		 */
503 		asm("" : "+rm"(nsec));
504 		nsec -= NSEC_PER_SEC;
505 		++sec;
506 	}
507 	while (nsec < 0) {
508 		asm("" : "+rm"(nsec));
509 		nsec += NSEC_PER_SEC;
510 		--sec;
511 	}
512 	ts->tv_sec = sec;
513 	ts->tv_nsec = nsec;
514 }
515 EXPORT_SYMBOL(set_normalized_timespec64);
516 
517 /**
518  * ns_to_timespec64 - Convert nanoseconds to timespec64
519  * @nsec:       the nanoseconds value to be converted
520  *
521  * Return: the timespec64 representation of the nsec parameter.
522  */
523 struct timespec64 ns_to_timespec64(s64 nsec)
524 {
525 	struct timespec64 ts = { 0, 0 };
526 	s32 rem;
527 
528 	if (likely(nsec > 0)) {
529 		ts.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
530 		ts.tv_nsec = rem;
531 	} else if (nsec < 0) {
532 		/*
533 		 * With negative times, tv_sec points to the earlier
534 		 * second, and tv_nsec counts the nanoseconds since
535 		 * then, so tv_nsec is always a positive number.
536 		 */
537 		ts.tv_sec = -div_u64_rem(-nsec - 1, NSEC_PER_SEC, &rem) - 1;
538 		ts.tv_nsec = NSEC_PER_SEC - rem - 1;
539 	}
540 
541 	return ts;
542 }
543 EXPORT_SYMBOL(ns_to_timespec64);
544 
545 /**
546  * __msecs_to_jiffies: - convert milliseconds to jiffies
547  * @m:	time in milliseconds
548  *
549  * conversion is done as follows:
550  *
551  * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
552  *
553  * - 'too large' values [that would result in larger than
554  *   MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
555  *
556  * - all other values are converted to jiffies by either multiplying
557  *   the input value by a factor or dividing it with a factor and
558  *   handling any 32-bit overflows.
559  *   for the details see _msecs_to_jiffies()
560  *
561  * msecs_to_jiffies() checks for the passed in value being a constant
562  * via __builtin_constant_p() allowing gcc to eliminate most of the
563  * code, __msecs_to_jiffies() is called if the value passed does not
564  * allow constant folding and the actual conversion must be done at
565  * runtime.
566  * The _msecs_to_jiffies helpers are the HZ dependent conversion
567  * routines found in include/linux/jiffies.h
568  *
569  * Return: jiffies value
570  */
571 unsigned long __msecs_to_jiffies(const unsigned int m)
572 {
573 	/*
574 	 * Negative value, means infinite timeout:
575 	 */
576 	if ((int)m < 0)
577 		return MAX_JIFFY_OFFSET;
578 	return _msecs_to_jiffies(m);
579 }
580 EXPORT_SYMBOL(__msecs_to_jiffies);
581 
582 /**
583  * __usecs_to_jiffies: - convert microseconds to jiffies
584  * @u:	time in milliseconds
585  *
586  * Return: jiffies value
587  */
588 unsigned long __usecs_to_jiffies(const unsigned int u)
589 {
590 	if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
591 		return MAX_JIFFY_OFFSET;
592 	return _usecs_to_jiffies(u);
593 }
594 EXPORT_SYMBOL(__usecs_to_jiffies);
595 
596 /**
597  * timespec64_to_jiffies - convert a timespec64 value to jiffies
598  * @value: pointer to &struct timespec64
599  *
600  * The TICK_NSEC - 1 rounds up the value to the next resolution.  Note
601  * that a remainder subtract here would not do the right thing as the
602  * resolution values don't fall on second boundaries.  I.e. the line:
603  * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding.
604  * Note that due to the small error in the multiplier here, this
605  * rounding is incorrect for sufficiently large values of tv_nsec, but
606  * well formed timespecs should have tv_nsec < NSEC_PER_SEC, so we're
607  * OK.
608  *
609  * Rather, we just shift the bits off the right.
610  *
611  * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
612  * value to a scaled second value.
613  *
614  * Return: jiffies value
615  */
616 unsigned long
617 timespec64_to_jiffies(const struct timespec64 *value)
618 {
619 	u64 sec = value->tv_sec;
620 	long nsec = value->tv_nsec + TICK_NSEC - 1;
621 
622 	if (sec >= MAX_SEC_IN_JIFFIES){
623 		sec = MAX_SEC_IN_JIFFIES;
624 		nsec = 0;
625 	}
626 	return ((sec * SEC_CONVERSION) +
627 		(((u64)nsec * NSEC_CONVERSION) >>
628 		 (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
629 
630 }
631 EXPORT_SYMBOL(timespec64_to_jiffies);
632 
633 /**
634  * jiffies_to_timespec64 - convert jiffies value to &struct timespec64
635  * @jiffies: jiffies value
636  * @value: pointer to &struct timespec64
637  */
638 void
639 jiffies_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 }
650 EXPORT_SYMBOL(jiffies_to_timespec64);
651 
652 /*
653  * Convert jiffies/jiffies_64 to clock_t and back.
654  */
655 
656 /**
657  * jiffies_to_clock_t - Convert jiffies to clock_t
658  * @x: jiffies value
659  *
660  * Return: jiffies converted to clock_t (CLOCKS_PER_SEC)
661  */
662 clock_t jiffies_to_clock_t(unsigned long x)
663 {
664 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
665 # if HZ < USER_HZ
666 	return x * (USER_HZ / HZ);
667 # else
668 	return x / (HZ / USER_HZ);
669 # endif
670 #else
671 	return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
672 #endif
673 }
674 EXPORT_SYMBOL(jiffies_to_clock_t);
675 
676 /**
677  * clock_t_to_jiffies - Convert clock_t to jiffies
678  * @x: clock_t value
679  *
680  * Return: clock_t value converted to jiffies
681  */
682 unsigned long clock_t_to_jiffies(unsigned long x)
683 {
684 #if (HZ % USER_HZ)==0
685 	if (x >= ~0UL / (HZ / USER_HZ))
686 		return ~0UL;
687 	return x * (HZ / USER_HZ);
688 #else
689 	/* Don't worry about loss of precision here .. */
690 	if (x >= ~0UL / HZ * USER_HZ)
691 		return ~0UL;
692 
693 	/* .. but do try to contain it here */
694 	return div_u64((u64)x * HZ, USER_HZ);
695 #endif
696 }
697 EXPORT_SYMBOL(clock_t_to_jiffies);
698 
699 /**
700  * jiffies_64_to_clock_t - Convert jiffies_64 to clock_t
701  * @x: jiffies_64 value
702  *
703  * Return: jiffies_64 value converted to 64-bit "clock_t" (CLOCKS_PER_SEC)
704  */
705 u64 jiffies_64_to_clock_t(u64 x)
706 {
707 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
708 # if HZ < USER_HZ
709 	x = div_u64(x * USER_HZ, HZ);
710 # elif HZ > USER_HZ
711 	x = div_u64(x, HZ / USER_HZ);
712 # else
713 	/* Nothing to do */
714 # endif
715 #else
716 	/*
717 	 * There are better ways that don't overflow early,
718 	 * but even this doesn't overflow in hundreds of years
719 	 * in 64 bits, so..
720 	 */
721 	x = div_u64(x * TICK_NSEC, (NSEC_PER_SEC / USER_HZ));
722 #endif
723 	return x;
724 }
725 EXPORT_SYMBOL(jiffies_64_to_clock_t);
726 
727 /**
728  * nsec_to_clock_t - Convert nsec value to clock_t
729  * @x: nsec value
730  *
731  * Return: nsec value converted to 64-bit "clock_t" (CLOCKS_PER_SEC)
732  */
733 u64 nsec_to_clock_t(u64 x)
734 {
735 #if (NSEC_PER_SEC % USER_HZ) == 0
736 	return div_u64(x, NSEC_PER_SEC / USER_HZ);
737 #elif (USER_HZ % 512) == 0
738 	return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512);
739 #else
740 	/*
741          * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
742          * overflow after 64.99 years.
743          * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
744          */
745 	return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ);
746 #endif
747 }
748 
749 /**
750  * jiffies64_to_nsecs - Convert jiffies64 to nanoseconds
751  * @j: jiffies64 value
752  *
753  * Return: nanoseconds value
754  */
755 u64 jiffies64_to_nsecs(u64 j)
756 {
757 #if !(NSEC_PER_SEC % HZ)
758 	return (NSEC_PER_SEC / HZ) * j;
759 # else
760 	return div_u64(j * HZ_TO_NSEC_NUM, HZ_TO_NSEC_DEN);
761 #endif
762 }
763 EXPORT_SYMBOL(jiffies64_to_nsecs);
764 
765 /**
766  * jiffies64_to_msecs - Convert jiffies64 to milliseconds
767  * @j: jiffies64 value
768  *
769  * Return: milliseconds value
770  */
771 u64 jiffies64_to_msecs(const u64 j)
772 {
773 #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
774 	return (MSEC_PER_SEC / HZ) * j;
775 #else
776 	return div_u64(j * HZ_TO_MSEC_NUM, HZ_TO_MSEC_DEN);
777 #endif
778 }
779 EXPORT_SYMBOL(jiffies64_to_msecs);
780 
781 /**
782  * nsecs_to_jiffies64 - Convert nsecs in u64 to jiffies64
783  *
784  * @n:	nsecs in u64
785  *
786  * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
787  * And this doesn't return MAX_JIFFY_OFFSET since this function is designed
788  * for scheduler, not for use in device drivers to calculate timeout value.
789  *
790  * note:
791  *   NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
792  *   ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
793  *
794  * Return: nsecs converted to jiffies64 value
795  */
796 u64 nsecs_to_jiffies64(u64 n)
797 {
798 #if (NSEC_PER_SEC % HZ) == 0
799 	/* Common case, HZ = 100, 128, 200, 250, 256, 500, 512, 1000 etc. */
800 	return div_u64(n, NSEC_PER_SEC / HZ);
801 #elif (HZ % 512) == 0
802 	/* overflow after 292 years if HZ = 1024 */
803 	return div_u64(n * HZ / 512, NSEC_PER_SEC / 512);
804 #else
805 	/*
806 	 * Generic case - optimized for cases where HZ is a multiple of 3.
807 	 * overflow after 64.99 years, exact for HZ = 60, 72, 90, 120 etc.
808 	 */
809 	return div_u64(n * 9, (9ull * NSEC_PER_SEC + HZ / 2) / HZ);
810 #endif
811 }
812 EXPORT_SYMBOL(nsecs_to_jiffies64);
813 
814 /**
815  * nsecs_to_jiffies - Convert nsecs in u64 to jiffies
816  *
817  * @n:	nsecs in u64
818  *
819  * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
820  * And this doesn't return MAX_JIFFY_OFFSET since this function is designed
821  * for scheduler, not for use in device drivers to calculate timeout value.
822  *
823  * note:
824  *   NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
825  *   ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
826  *
827  * Return: nsecs converted to jiffies value
828  */
829 unsigned long nsecs_to_jiffies(u64 n)
830 {
831 	return (unsigned long)nsecs_to_jiffies64(n);
832 }
833 EXPORT_SYMBOL_GPL(nsecs_to_jiffies);
834 
835 /**
836  * timespec64_add_safe - Add two timespec64 values and do a safety check
837  * for overflow.
838  * @lhs: first (left) timespec64 to add
839  * @rhs: second (right) timespec64 to add
840  *
841  * It's assumed that both values are valid (>= 0).
842  * And, each timespec64 is in normalized form.
843  *
844  * Return: sum of @lhs + @rhs
845  */
846 struct timespec64 timespec64_add_safe(const struct timespec64 lhs,
847 				const struct timespec64 rhs)
848 {
849 	struct timespec64 res;
850 
851 	set_normalized_timespec64(&res, (timeu64_t) lhs.tv_sec + rhs.tv_sec,
852 			lhs.tv_nsec + rhs.tv_nsec);
853 
854 	if (unlikely(res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec)) {
855 		res.tv_sec = TIME64_MAX;
856 		res.tv_nsec = 0;
857 	}
858 
859 	return res;
860 }
861 
862 /**
863  * get_timespec64 - get user's time value into kernel space
864  * @ts: destination &struct timespec64
865  * @uts: user's time value as &struct __kernel_timespec
866  *
867  * Handles compat or 32-bit modes.
868  *
869  * Return: 0 on success or negative errno on error
870  */
871 int get_timespec64(struct timespec64 *ts,
872 		   const struct __kernel_timespec __user *uts)
873 {
874 	struct __kernel_timespec kts;
875 	int ret;
876 
877 	ret = copy_from_user(&kts, uts, sizeof(kts));
878 	if (ret)
879 		return -EFAULT;
880 
881 	ts->tv_sec = kts.tv_sec;
882 
883 	/* Zero out the padding in compat mode */
884 	if (in_compat_syscall())
885 		kts.tv_nsec &= 0xFFFFFFFFUL;
886 
887 	/* In 32-bit mode, this drops the padding */
888 	ts->tv_nsec = kts.tv_nsec;
889 
890 	return 0;
891 }
892 EXPORT_SYMBOL_GPL(get_timespec64);
893 
894 /**
895  * put_timespec64 - convert timespec64 value to __kernel_timespec format and
896  * 		    copy the latter to userspace
897  * @ts: input &struct timespec64
898  * @uts: user's &struct __kernel_timespec
899  *
900  * Return: 0 on success or negative errno on error
901  */
902 int put_timespec64(const struct timespec64 *ts,
903 		   struct __kernel_timespec __user *uts)
904 {
905 	struct __kernel_timespec kts = {
906 		.tv_sec = ts->tv_sec,
907 		.tv_nsec = ts->tv_nsec
908 	};
909 
910 	return copy_to_user(uts, &kts, sizeof(kts)) ? -EFAULT : 0;
911 }
912 EXPORT_SYMBOL_GPL(put_timespec64);
913 
914 static int __get_old_timespec32(struct timespec64 *ts64,
915 				   const struct old_timespec32 __user *cts)
916 {
917 	struct old_timespec32 ts;
918 	int ret;
919 
920 	ret = copy_from_user(&ts, cts, sizeof(ts));
921 	if (ret)
922 		return -EFAULT;
923 
924 	ts64->tv_sec = ts.tv_sec;
925 	ts64->tv_nsec = ts.tv_nsec;
926 
927 	return 0;
928 }
929 
930 static int __put_old_timespec32(const struct timespec64 *ts64,
931 				   struct old_timespec32 __user *cts)
932 {
933 	struct old_timespec32 ts = {
934 		.tv_sec = ts64->tv_sec,
935 		.tv_nsec = ts64->tv_nsec
936 	};
937 	return copy_to_user(cts, &ts, sizeof(ts)) ? -EFAULT : 0;
938 }
939 
940 /**
941  * get_old_timespec32 - get user's old-format time value into kernel space
942  * @ts: destination &struct timespec64
943  * @uts: user's old-format time value (&struct old_timespec32)
944  *
945  * Handles X86_X32_ABI compatibility conversion.
946  *
947  * Return: 0 on success or negative errno on error
948  */
949 int get_old_timespec32(struct timespec64 *ts, const void __user *uts)
950 {
951 	if (COMPAT_USE_64BIT_TIME)
952 		return copy_from_user(ts, uts, sizeof(*ts)) ? -EFAULT : 0;
953 	else
954 		return __get_old_timespec32(ts, uts);
955 }
956 EXPORT_SYMBOL_GPL(get_old_timespec32);
957 
958 /**
959  * put_old_timespec32 - convert timespec64 value to &struct old_timespec32 and
960  * 			copy the latter to userspace
961  * @ts: input &struct timespec64
962  * @uts: user's &struct old_timespec32
963  *
964  * Handles X86_X32_ABI compatibility conversion.
965  *
966  * Return: 0 on success or negative errno on error
967  */
968 int put_old_timespec32(const struct timespec64 *ts, void __user *uts)
969 {
970 	if (COMPAT_USE_64BIT_TIME)
971 		return copy_to_user(uts, ts, sizeof(*ts)) ? -EFAULT : 0;
972 	else
973 		return __put_old_timespec32(ts, uts);
974 }
975 EXPORT_SYMBOL_GPL(put_old_timespec32);
976 
977 /**
978  * get_itimerspec64 - get user's &struct __kernel_itimerspec into kernel space
979  * @it: destination &struct itimerspec64
980  * @uit: user's &struct __kernel_itimerspec
981  *
982  * Return: 0 on success or negative errno on error
983  */
984 int get_itimerspec64(struct itimerspec64 *it,
985 			const struct __kernel_itimerspec __user *uit)
986 {
987 	int ret;
988 
989 	ret = get_timespec64(&it->it_interval, &uit->it_interval);
990 	if (ret)
991 		return ret;
992 
993 	ret = get_timespec64(&it->it_value, &uit->it_value);
994 
995 	return ret;
996 }
997 EXPORT_SYMBOL_GPL(get_itimerspec64);
998 
999 /**
1000  * put_itimerspec64 - convert &struct itimerspec64 to __kernel_itimerspec format
1001  * 		      and copy the latter to userspace
1002  * @it: input &struct itimerspec64
1003  * @uit: user's &struct __kernel_itimerspec
1004  *
1005  * Return: 0 on success or negative errno on error
1006  */
1007 int put_itimerspec64(const struct itimerspec64 *it,
1008 			struct __kernel_itimerspec __user *uit)
1009 {
1010 	int ret;
1011 
1012 	ret = put_timespec64(&it->it_interval, &uit->it_interval);
1013 	if (ret)
1014 		return ret;
1015 
1016 	ret = put_timespec64(&it->it_value, &uit->it_value);
1017 
1018 	return ret;
1019 }
1020 EXPORT_SYMBOL_GPL(put_itimerspec64);
1021 
1022 /**
1023  * get_old_itimerspec32 - get user's &struct old_itimerspec32 into kernel space
1024  * @its: destination &struct itimerspec64
1025  * @uits: user's &struct old_itimerspec32
1026  *
1027  * Return: 0 on success or negative errno on error
1028  */
1029 int get_old_itimerspec32(struct itimerspec64 *its,
1030 			const struct old_itimerspec32 __user *uits)
1031 {
1032 
1033 	if (__get_old_timespec32(&its->it_interval, &uits->it_interval) ||
1034 	    __get_old_timespec32(&its->it_value, &uits->it_value))
1035 		return -EFAULT;
1036 	return 0;
1037 }
1038 EXPORT_SYMBOL_GPL(get_old_itimerspec32);
1039 
1040 /**
1041  * put_old_itimerspec32 - convert &struct itimerspec64 to &struct
1042  *			  old_itimerspec32 and copy the latter to userspace
1043  * @its: input &struct itimerspec64
1044  * @uits: user's &struct old_itimerspec32
1045  *
1046  * Return: 0 on success or negative errno on error
1047  */
1048 int put_old_itimerspec32(const struct itimerspec64 *its,
1049 			struct old_itimerspec32 __user *uits)
1050 {
1051 	if (__put_old_timespec32(&its->it_interval, &uits->it_interval) ||
1052 	    __put_old_timespec32(&its->it_value, &uits->it_value))
1053 		return -EFAULT;
1054 	return 0;
1055 }
1056 EXPORT_SYMBOL_GPL(put_old_itimerspec32);
1057