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1/*
2 * linux/kernel/time/timekeeping.c
3 *
4 * Kernel timekeeping code and accessor functions
5 *
6 * This code was moved from linux/kernel/timer.c.
7 * Please see that file for copyright and history logs.
8 *
9 */
10
11#include <linux/module.h>
12#include <linux/interrupt.h>
13#include <linux/percpu.h>
14#include <linux/init.h>
15#include <linux/mm.h>
16#include <linux/sched.h>
17#include <linux/syscore_ops.h>
18#include <linux/clocksource.h>
19#include <linux/jiffies.h>
20#include <linux/time.h>
21#include <linux/tick.h>
22#include <linux/stop_machine.h>
23
24/* Structure holding internal timekeeping values. */
25struct timekeeper {
26 /* Current clocksource used for timekeeping. */
27 struct clocksource *clock;
28 /* The shift value of the current clocksource. */
29 int shift;
30
31 /* Number of clock cycles in one NTP interval. */
32 cycle_t cycle_interval;
33 /* Number of clock shifted nano seconds in one NTP interval. */
34 u64 xtime_interval;
35 /* shifted nano seconds left over when rounding cycle_interval */
36 s64 xtime_remainder;
37 /* Raw nano seconds accumulated per NTP interval. */
38 u32 raw_interval;
39
40 /* Clock shifted nano seconds remainder not stored in xtime.tv_nsec. */
41 u64 xtime_nsec;
42 /* Difference between accumulated time and NTP time in ntp
43 * shifted nano seconds. */
44 s64 ntp_error;
45 /* Shift conversion between clock shifted nano seconds and
46 * ntp shifted nano seconds. */
47 int ntp_error_shift;
48 /* NTP adjusted clock multiplier */
49 u32 mult;
50};
51
52static struct timekeeper timekeeper;
53
54/**
55 * timekeeper_setup_internals - Set up internals to use clocksource clock.
56 *
57 * @clock: Pointer to clocksource.
58 *
59 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
60 * pair and interval request.
61 *
62 * Unless you're the timekeeping code, you should not be using this!
63 */
64static void timekeeper_setup_internals(struct clocksource *clock)
65{
66 cycle_t interval;
67 u64 tmp, ntpinterval;
68
69 timekeeper.clock = clock;
70 clock->cycle_last = clock->read(clock);
71
72 /* Do the ns -> cycle conversion first, using original mult */
73 tmp = NTP_INTERVAL_LENGTH;
74 tmp <<= clock->shift;
75 ntpinterval = tmp;
76 tmp += clock->mult/2;
77 do_div(tmp, clock->mult);
78 if (tmp == 0)
79 tmp = 1;
80
81 interval = (cycle_t) tmp;
82 timekeeper.cycle_interval = interval;
83
84 /* Go back from cycles -> shifted ns */
85 timekeeper.xtime_interval = (u64) interval * clock->mult;
86 timekeeper.xtime_remainder = ntpinterval - timekeeper.xtime_interval;
87 timekeeper.raw_interval =
88 ((u64) interval * clock->mult) >> clock->shift;
89
90 timekeeper.xtime_nsec = 0;
91 timekeeper.shift = clock->shift;
92
93 timekeeper.ntp_error = 0;
94 timekeeper.ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
95
96 /*
97 * The timekeeper keeps its own mult values for the currently
98 * active clocksource. These value will be adjusted via NTP
99 * to counteract clock drifting.
100 */
101 timekeeper.mult = clock->mult;
102}
103
104/* Timekeeper helper functions. */
105static inline s64 timekeeping_get_ns(void)
106{
107 cycle_t cycle_now, cycle_delta;
108 struct clocksource *clock;
109
110 /* read clocksource: */
111 clock = timekeeper.clock;
112 cycle_now = clock->read(clock);
113
114 /* calculate the delta since the last update_wall_time: */
115 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
116
117 /* return delta convert to nanoseconds using ntp adjusted mult. */
118 return clocksource_cyc2ns(cycle_delta, timekeeper.mult,
119 timekeeper.shift);
120}
121
122static inline s64 timekeeping_get_ns_raw(void)
123{
124 cycle_t cycle_now, cycle_delta;
125 struct clocksource *clock;
126
127 /* read clocksource: */
128 clock = timekeeper.clock;
129 cycle_now = clock->read(clock);
130
131 /* calculate the delta since the last update_wall_time: */
132 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
133
134 /* return delta convert to nanoseconds using ntp adjusted mult. */
135 return clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
136}
137
138/*
139 * This read-write spinlock protects us from races in SMP while
140 * playing with xtime.
141 */
142__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
143
144
145/*
146 * The current time
147 * wall_to_monotonic is what we need to add to xtime (or xtime corrected
148 * for sub jiffie times) to get to monotonic time. Monotonic is pegged
149 * at zero at system boot time, so wall_to_monotonic will be negative,
150 * however, we will ALWAYS keep the tv_nsec part positive so we can use
151 * the usual normalization.
152 *
153 * wall_to_monotonic is moved after resume from suspend for the monotonic
154 * time not to jump. We need to add total_sleep_time to wall_to_monotonic
155 * to get the real boot based time offset.
156 *
157 * - wall_to_monotonic is no longer the boot time, getboottime must be
158 * used instead.
159 */
160static struct timespec xtime __attribute__ ((aligned (16)));
161static struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
162static struct timespec total_sleep_time;
163
164/*
165 * The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock.
166 */
167static struct timespec raw_time;
168
169/* flag for if timekeeping is suspended */
170int __read_mostly timekeeping_suspended;
171
172/* must hold xtime_lock */
173void timekeeping_leap_insert(int leapsecond)
174{
175 xtime.tv_sec += leapsecond;
176 wall_to_monotonic.tv_sec -= leapsecond;
177 update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
178 timekeeper.mult);
179}
180
181/**
182 * timekeeping_forward_now - update clock to the current time
183 *
184 * Forward the current clock to update its state since the last call to
185 * update_wall_time(). This is useful before significant clock changes,
186 * as it avoids having to deal with this time offset explicitly.
187 */
188static void timekeeping_forward_now(void)
189{
190 cycle_t cycle_now, cycle_delta;
191 struct clocksource *clock;
192 s64 nsec;
193
194 clock = timekeeper.clock;
195 cycle_now = clock->read(clock);
196 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
197 clock->cycle_last = cycle_now;
198
199 nsec = clocksource_cyc2ns(cycle_delta, timekeeper.mult,
200 timekeeper.shift);
201
202 /* If arch requires, add in gettimeoffset() */
203 nsec += arch_gettimeoffset();
204
205 timespec_add_ns(&xtime, nsec);
206
207 nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
208 timespec_add_ns(&raw_time, nsec);
209}
210
211/**
212 * getnstimeofday - Returns the time of day in a timespec
213 * @ts: pointer to the timespec to be set
214 *
215 * Returns the time of day in a timespec.
216 */
217void getnstimeofday(struct timespec *ts)
218{
219 unsigned long seq;
220 s64 nsecs;
221
222 WARN_ON(timekeeping_suspended);
223
224 do {
225 seq = read_seqbegin(&xtime_lock);
226
227 *ts = xtime;
228 nsecs = timekeeping_get_ns();
229
230 /* If arch requires, add in gettimeoffset() */
231 nsecs += arch_gettimeoffset();
232
233 } while (read_seqretry(&xtime_lock, seq));
234
235 timespec_add_ns(ts, nsecs);
236}
237
238EXPORT_SYMBOL(getnstimeofday);
239
240ktime_t ktime_get(void)
241{
242 unsigned int seq;
243 s64 secs, nsecs;
244
245 WARN_ON(timekeeping_suspended);
246
247 do {
248 seq = read_seqbegin(&xtime_lock);
249 secs = xtime.tv_sec + wall_to_monotonic.tv_sec;
250 nsecs = xtime.tv_nsec + wall_to_monotonic.tv_nsec;
251 nsecs += timekeeping_get_ns();
252
253 } while (read_seqretry(&xtime_lock, seq));
254 /*
255 * Use ktime_set/ktime_add_ns to create a proper ktime on
256 * 32-bit architectures without CONFIG_KTIME_SCALAR.
257 */
258 return ktime_add_ns(ktime_set(secs, 0), nsecs);
259}
260EXPORT_SYMBOL_GPL(ktime_get);
261
262/**
263 * ktime_get_ts - get the monotonic clock in timespec format
264 * @ts: pointer to timespec variable
265 *
266 * The function calculates the monotonic clock from the realtime
267 * clock and the wall_to_monotonic offset and stores the result
268 * in normalized timespec format in the variable pointed to by @ts.
269 */
270void ktime_get_ts(struct timespec *ts)
271{
272 struct timespec tomono;
273 unsigned int seq;
274 s64 nsecs;
275
276 WARN_ON(timekeeping_suspended);
277
278 do {
279 seq = read_seqbegin(&xtime_lock);
280 *ts = xtime;
281 tomono = wall_to_monotonic;
282 nsecs = timekeeping_get_ns();
283
284 } while (read_seqretry(&xtime_lock, seq));
285
286 set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec,
287 ts->tv_nsec + tomono.tv_nsec + nsecs);
288}
289EXPORT_SYMBOL_GPL(ktime_get_ts);
290
291#ifdef CONFIG_NTP_PPS
292
293/**
294 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
295 * @ts_raw: pointer to the timespec to be set to raw monotonic time
296 * @ts_real: pointer to the timespec to be set to the time of day
297 *
298 * This function reads both the time of day and raw monotonic time at the
299 * same time atomically and stores the resulting timestamps in timespec
300 * format.
301 */
302void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
303{
304 unsigned long seq;
305 s64 nsecs_raw, nsecs_real;
306
307 WARN_ON_ONCE(timekeeping_suspended);
308
309 do {
310 u32 arch_offset;
311
312 seq = read_seqbegin(&xtime_lock);
313
314 *ts_raw = raw_time;
315 *ts_real = xtime;
316
317 nsecs_raw = timekeeping_get_ns_raw();
318 nsecs_real = timekeeping_get_ns();
319
320 /* If arch requires, add in gettimeoffset() */
321 arch_offset = arch_gettimeoffset();
322 nsecs_raw += arch_offset;
323 nsecs_real += arch_offset;
324
325 } while (read_seqretry(&xtime_lock, seq));
326
327 timespec_add_ns(ts_raw, nsecs_raw);
328 timespec_add_ns(ts_real, nsecs_real);
329}
330EXPORT_SYMBOL(getnstime_raw_and_real);
331
332#endif /* CONFIG_NTP_PPS */
333
334/**
335 * do_gettimeofday - Returns the time of day in a timeval
336 * @tv: pointer to the timeval to be set
337 *
338 * NOTE: Users should be converted to using getnstimeofday()
339 */
340void do_gettimeofday(struct timeval *tv)
341{
342 struct timespec now;
343
344 getnstimeofday(&now);
345 tv->tv_sec = now.tv_sec;
346 tv->tv_usec = now.tv_nsec/1000;
347}
348
349EXPORT_SYMBOL(do_gettimeofday);
350/**
351 * do_settimeofday - Sets the time of day
352 * @tv: pointer to the timespec variable containing the new time
353 *
354 * Sets the time of day to the new time and update NTP and notify hrtimers
355 */
356int do_settimeofday(const struct timespec *tv)
357{
358 struct timespec ts_delta;
359 unsigned long flags;
360
361 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
362 return -EINVAL;
363
364 write_seqlock_irqsave(&xtime_lock, flags);
365
366 timekeeping_forward_now();
367
368 ts_delta.tv_sec = tv->tv_sec - xtime.tv_sec;
369 ts_delta.tv_nsec = tv->tv_nsec - xtime.tv_nsec;
370 wall_to_monotonic = timespec_sub(wall_to_monotonic, ts_delta);
371
372 xtime = *tv;
373
374 timekeeper.ntp_error = 0;
375 ntp_clear();
376
377 update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
378 timekeeper.mult);
379
380 write_sequnlock_irqrestore(&xtime_lock, flags);
381
382 /* signal hrtimers about time change */
383 clock_was_set();
384
385 return 0;
386}
387
388EXPORT_SYMBOL(do_settimeofday);
389
390
391/**
392 * timekeeping_inject_offset - Adds or subtracts from the current time.
393 * @tv: pointer to the timespec variable containing the offset
394 *
395 * Adds or subtracts an offset value from the current time.
396 */
397int timekeeping_inject_offset(struct timespec *ts)
398{
399 unsigned long flags;
400
401 if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
402 return -EINVAL;
403
404 write_seqlock_irqsave(&xtime_lock, flags);
405
406 timekeeping_forward_now();
407
408 xtime = timespec_add(xtime, *ts);
409 wall_to_monotonic = timespec_sub(wall_to_monotonic, *ts);
410
411 timekeeper.ntp_error = 0;
412 ntp_clear();
413
414 update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
415 timekeeper.mult);
416
417 write_sequnlock_irqrestore(&xtime_lock, flags);
418
419 /* signal hrtimers about time change */
420 clock_was_set();
421
422 return 0;
423}
424EXPORT_SYMBOL(timekeeping_inject_offset);
425
426/**
427 * change_clocksource - Swaps clocksources if a new one is available
428 *
429 * Accumulates current time interval and initializes new clocksource
430 */
431static int change_clocksource(void *data)
432{
433 struct clocksource *new, *old;
434
435 new = (struct clocksource *) data;
436
437 timekeeping_forward_now();
438 if (!new->enable || new->enable(new) == 0) {
439 old = timekeeper.clock;
440 timekeeper_setup_internals(new);
441 if (old->disable)
442 old->disable(old);
443 }
444 return 0;
445}
446
447/**
448 * timekeeping_notify - Install a new clock source
449 * @clock: pointer to the clock source
450 *
451 * This function is called from clocksource.c after a new, better clock
452 * source has been registered. The caller holds the clocksource_mutex.
453 */
454void timekeeping_notify(struct clocksource *clock)
455{
456 if (timekeeper.clock == clock)
457 return;
458 stop_machine(change_clocksource, clock, NULL);
459 tick_clock_notify();
460}
461
462/**
463 * ktime_get_real - get the real (wall-) time in ktime_t format
464 *
465 * returns the time in ktime_t format
466 */
467ktime_t ktime_get_real(void)
468{
469 struct timespec now;
470
471 getnstimeofday(&now);
472
473 return timespec_to_ktime(now);
474}
475EXPORT_SYMBOL_GPL(ktime_get_real);
476
477/**
478 * getrawmonotonic - Returns the raw monotonic time in a timespec
479 * @ts: pointer to the timespec to be set
480 *
481 * Returns the raw monotonic time (completely un-modified by ntp)
482 */
483void getrawmonotonic(struct timespec *ts)
484{
485 unsigned long seq;
486 s64 nsecs;
487
488 do {
489 seq = read_seqbegin(&xtime_lock);
490 nsecs = timekeeping_get_ns_raw();
491 *ts = raw_time;
492
493 } while (read_seqretry(&xtime_lock, seq));
494
495 timespec_add_ns(ts, nsecs);
496}
497EXPORT_SYMBOL(getrawmonotonic);
498
499
500/**
501 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
502 */
503int timekeeping_valid_for_hres(void)
504{
505 unsigned long seq;
506 int ret;
507
508 do {
509 seq = read_seqbegin(&xtime_lock);
510
511 ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
512
513 } while (read_seqretry(&xtime_lock, seq));
514
515 return ret;
516}
517
518/**
519 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
520 *
521 * Caller must observe xtime_lock via read_seqbegin/read_seqretry to
522 * ensure that the clocksource does not change!
523 */
524u64 timekeeping_max_deferment(void)
525{
526 return timekeeper.clock->max_idle_ns;
527}
528
529/**
530 * read_persistent_clock - Return time from the persistent clock.
531 *
532 * Weak dummy function for arches that do not yet support it.
533 * Reads the time from the battery backed persistent clock.
534 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
535 *
536 * XXX - Do be sure to remove it once all arches implement it.
537 */
538void __attribute__((weak)) read_persistent_clock(struct timespec *ts)
539{
540 ts->tv_sec = 0;
541 ts->tv_nsec = 0;
542}
543
544/**
545 * read_boot_clock - Return time of the system start.
546 *
547 * Weak dummy function for arches that do not yet support it.
548 * Function to read the exact time the system has been started.
549 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
550 *
551 * XXX - Do be sure to remove it once all arches implement it.
552 */
553void __attribute__((weak)) read_boot_clock(struct timespec *ts)
554{
555 ts->tv_sec = 0;
556 ts->tv_nsec = 0;
557}
558
559/*
560 * timekeeping_init - Initializes the clocksource and common timekeeping values
561 */
562void __init timekeeping_init(void)
563{
564 struct clocksource *clock;
565 unsigned long flags;
566 struct timespec now, boot;
567
568 read_persistent_clock(&now);
569 read_boot_clock(&boot);
570
571 write_seqlock_irqsave(&xtime_lock, flags);
572
573 ntp_init();
574
575 clock = clocksource_default_clock();
576 if (clock->enable)
577 clock->enable(clock);
578 timekeeper_setup_internals(clock);
579
580 xtime.tv_sec = now.tv_sec;
581 xtime.tv_nsec = now.tv_nsec;
582 raw_time.tv_sec = 0;
583 raw_time.tv_nsec = 0;
584 if (boot.tv_sec == 0 && boot.tv_nsec == 0) {
585 boot.tv_sec = xtime.tv_sec;
586 boot.tv_nsec = xtime.tv_nsec;
587 }
588 set_normalized_timespec(&wall_to_monotonic,
589 -boot.tv_sec, -boot.tv_nsec);
590 total_sleep_time.tv_sec = 0;
591 total_sleep_time.tv_nsec = 0;
592 write_sequnlock_irqrestore(&xtime_lock, flags);
593}
594
595/* time in seconds when suspend began */
596static struct timespec timekeeping_suspend_time;
597
598/**
599 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
600 * @delta: pointer to a timespec delta value
601 *
602 * Takes a timespec offset measuring a suspend interval and properly
603 * adds the sleep offset to the timekeeping variables.
604 */
605static void __timekeeping_inject_sleeptime(struct timespec *delta)
606{
607 if (!timespec_valid(delta)) {
608 printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
609 "sleep delta value!\n");
610 return;
611 }
612
613 xtime = timespec_add(xtime, *delta);
614 wall_to_monotonic = timespec_sub(wall_to_monotonic, *delta);
615 total_sleep_time = timespec_add(total_sleep_time, *delta);
616}
617
618
619/**
620 * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
621 * @delta: pointer to a timespec delta value
622 *
623 * This hook is for architectures that cannot support read_persistent_clock
624 * because their RTC/persistent clock is only accessible when irqs are enabled.
625 *
626 * This function should only be called by rtc_resume(), and allows
627 * a suspend offset to be injected into the timekeeping values.
628 */
629void timekeeping_inject_sleeptime(struct timespec *delta)
630{
631 unsigned long flags;
632 struct timespec ts;
633
634 /* Make sure we don't set the clock twice */
635 read_persistent_clock(&ts);
636 if (!(ts.tv_sec == 0 && ts.tv_nsec == 0))
637 return;
638
639 write_seqlock_irqsave(&xtime_lock, flags);
640 timekeeping_forward_now();
641
642 __timekeeping_inject_sleeptime(delta);
643
644 timekeeper.ntp_error = 0;
645 ntp_clear();
646 update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
647 timekeeper.mult);
648
649 write_sequnlock_irqrestore(&xtime_lock, flags);
650
651 /* signal hrtimers about time change */
652 clock_was_set();
653}
654
655
656/**
657 * timekeeping_resume - Resumes the generic timekeeping subsystem.
658 *
659 * This is for the generic clocksource timekeeping.
660 * xtime/wall_to_monotonic/jiffies/etc are
661 * still managed by arch specific suspend/resume code.
662 */
663static void timekeeping_resume(void)
664{
665 unsigned long flags;
666 struct timespec ts;
667
668 read_persistent_clock(&ts);
669
670 clocksource_resume();
671
672 write_seqlock_irqsave(&xtime_lock, flags);
673
674 if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {
675 ts = timespec_sub(ts, timekeeping_suspend_time);
676 __timekeeping_inject_sleeptime(&ts);
677 }
678 /* re-base the last cycle value */
679 timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
680 timekeeper.ntp_error = 0;
681 timekeeping_suspended = 0;
682 write_sequnlock_irqrestore(&xtime_lock, flags);
683
684 touch_softlockup_watchdog();
685
686 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
687
688 /* Resume hrtimers */
689 hrtimers_resume();
690}
691
692static int timekeeping_suspend(void)
693{
694 unsigned long flags;
695 struct timespec delta, delta_delta;
696 static struct timespec old_delta;
697
698 read_persistent_clock(&timekeeping_suspend_time);
699
700 write_seqlock_irqsave(&xtime_lock, flags);
701 timekeeping_forward_now();
702 timekeeping_suspended = 1;
703
704 /*
705 * To avoid drift caused by repeated suspend/resumes,
706 * which each can add ~1 second drift error,
707 * try to compensate so the difference in system time
708 * and persistent_clock time stays close to constant.
709 */
710 delta = timespec_sub(xtime, timekeeping_suspend_time);
711 delta_delta = timespec_sub(delta, old_delta);
712 if (abs(delta_delta.tv_sec) >= 2) {
713 /*
714 * if delta_delta is too large, assume time correction
715 * has occured and set old_delta to the current delta.
716 */
717 old_delta = delta;
718 } else {
719 /* Otherwise try to adjust old_system to compensate */
720 timekeeping_suspend_time =
721 timespec_add(timekeeping_suspend_time, delta_delta);
722 }
723 write_sequnlock_irqrestore(&xtime_lock, flags);
724
725 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
726 clocksource_suspend();
727
728 return 0;
729}
730
731/* sysfs resume/suspend bits for timekeeping */
732static struct syscore_ops timekeeping_syscore_ops = {
733 .resume = timekeeping_resume,
734 .suspend = timekeeping_suspend,
735};
736
737static int __init timekeeping_init_ops(void)
738{
739 register_syscore_ops(&timekeeping_syscore_ops);
740 return 0;
741}
742
743device_initcall(timekeeping_init_ops);
744
745/*
746 * If the error is already larger, we look ahead even further
747 * to compensate for late or lost adjustments.
748 */
749static __always_inline int timekeeping_bigadjust(s64 error, s64 *interval,
750 s64 *offset)
751{
752 s64 tick_error, i;
753 u32 look_ahead, adj;
754 s32 error2, mult;
755
756 /*
757 * Use the current error value to determine how much to look ahead.
758 * The larger the error the slower we adjust for it to avoid problems
759 * with losing too many ticks, otherwise we would overadjust and
760 * produce an even larger error. The smaller the adjustment the
761 * faster we try to adjust for it, as lost ticks can do less harm
762 * here. This is tuned so that an error of about 1 msec is adjusted
763 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
764 */
765 error2 = timekeeper.ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
766 error2 = abs(error2);
767 for (look_ahead = 0; error2 > 0; look_ahead++)
768 error2 >>= 2;
769
770 /*
771 * Now calculate the error in (1 << look_ahead) ticks, but first
772 * remove the single look ahead already included in the error.
773 */
774 tick_error = tick_length >> (timekeeper.ntp_error_shift + 1);
775 tick_error -= timekeeper.xtime_interval >> 1;
776 error = ((error - tick_error) >> look_ahead) + tick_error;
777
778 /* Finally calculate the adjustment shift value. */
779 i = *interval;
780 mult = 1;
781 if (error < 0) {
782 error = -error;
783 *interval = -*interval;
784 *offset = -*offset;
785 mult = -1;
786 }
787 for (adj = 0; error > i; adj++)
788 error >>= 1;
789
790 *interval <<= adj;
791 *offset <<= adj;
792 return mult << adj;
793}
794
795/*
796 * Adjust the multiplier to reduce the error value,
797 * this is optimized for the most common adjustments of -1,0,1,
798 * for other values we can do a bit more work.
799 */
800static void timekeeping_adjust(s64 offset)
801{
802 s64 error, interval = timekeeper.cycle_interval;
803 int adj;
804
805 error = timekeeper.ntp_error >> (timekeeper.ntp_error_shift - 1);
806 if (error > interval) {
807 error >>= 2;
808 if (likely(error <= interval))
809 adj = 1;
810 else
811 adj = timekeeping_bigadjust(error, &interval, &offset);
812 } else if (error < -interval) {
813 error >>= 2;
814 if (likely(error >= -interval)) {
815 adj = -1;
816 interval = -interval;
817 offset = -offset;
818 } else
819 adj = timekeeping_bigadjust(error, &interval, &offset);
820 } else
821 return;
822
823 timekeeper.mult += adj;
824 timekeeper.xtime_interval += interval;
825 timekeeper.xtime_nsec -= offset;
826 timekeeper.ntp_error -= (interval - offset) <<
827 timekeeper.ntp_error_shift;
828}
829
830
831/**
832 * logarithmic_accumulation - shifted accumulation of cycles
833 *
834 * This functions accumulates a shifted interval of cycles into
835 * into a shifted interval nanoseconds. Allows for O(log) accumulation
836 * loop.
837 *
838 * Returns the unconsumed cycles.
839 */
840static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
841{
842 u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift;
843 u64 raw_nsecs;
844
845 /* If the offset is smaller then a shifted interval, do nothing */
846 if (offset < timekeeper.cycle_interval<<shift)
847 return offset;
848
849 /* Accumulate one shifted interval */
850 offset -= timekeeper.cycle_interval << shift;
851 timekeeper.clock->cycle_last += timekeeper.cycle_interval << shift;
852
853 timekeeper.xtime_nsec += timekeeper.xtime_interval << shift;
854 while (timekeeper.xtime_nsec >= nsecps) {
855 timekeeper.xtime_nsec -= nsecps;
856 xtime.tv_sec++;
857 second_overflow();
858 }
859
860 /* Accumulate raw time */
861 raw_nsecs = timekeeper.raw_interval << shift;
862 raw_nsecs += raw_time.tv_nsec;
863 if (raw_nsecs >= NSEC_PER_SEC) {
864 u64 raw_secs = raw_nsecs;
865 raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
866 raw_time.tv_sec += raw_secs;
867 }
868 raw_time.tv_nsec = raw_nsecs;
869
870 /* Accumulate error between NTP and clock interval */
871 timekeeper.ntp_error += tick_length << shift;
872 timekeeper.ntp_error -=
873 (timekeeper.xtime_interval + timekeeper.xtime_remainder) <<
874 (timekeeper.ntp_error_shift + shift);
875
876 return offset;
877}
878
879
880/**
881 * update_wall_time - Uses the current clocksource to increment the wall time
882 *
883 * Called from the timer interrupt, must hold a write on xtime_lock.
884 */
885static void update_wall_time(void)
886{
887 struct clocksource *clock;
888 cycle_t offset;
889 int shift = 0, maxshift;
890
891 /* Make sure we're fully resumed: */
892 if (unlikely(timekeeping_suspended))
893 return;
894
895 clock = timekeeper.clock;
896
897#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
898 offset = timekeeper.cycle_interval;
899#else
900 offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
901#endif
902 timekeeper.xtime_nsec = (s64)xtime.tv_nsec << timekeeper.shift;
903
904 /*
905 * With NO_HZ we may have to accumulate many cycle_intervals
906 * (think "ticks") worth of time at once. To do this efficiently,
907 * we calculate the largest doubling multiple of cycle_intervals
908 * that is smaller then the offset. We then accumulate that
909 * chunk in one go, and then try to consume the next smaller
910 * doubled multiple.
911 */
912 shift = ilog2(offset) - ilog2(timekeeper.cycle_interval);
913 shift = max(0, shift);
914 /* Bound shift to one less then what overflows tick_length */
915 maxshift = (8*sizeof(tick_length) - (ilog2(tick_length)+1)) - 1;
916 shift = min(shift, maxshift);
917 while (offset >= timekeeper.cycle_interval) {
918 offset = logarithmic_accumulation(offset, shift);
919 if(offset < timekeeper.cycle_interval<<shift)
920 shift--;
921 }
922
923 /* correct the clock when NTP error is too big */
924 timekeeping_adjust(offset);
925
926 /*
927 * Since in the loop above, we accumulate any amount of time
928 * in xtime_nsec over a second into xtime.tv_sec, its possible for
929 * xtime_nsec to be fairly small after the loop. Further, if we're
930 * slightly speeding the clocksource up in timekeeping_adjust(),
931 * its possible the required corrective factor to xtime_nsec could
932 * cause it to underflow.
933 *
934 * Now, we cannot simply roll the accumulated second back, since
935 * the NTP subsystem has been notified via second_overflow. So
936 * instead we push xtime_nsec forward by the amount we underflowed,
937 * and add that amount into the error.
938 *
939 * We'll correct this error next time through this function, when
940 * xtime_nsec is not as small.
941 */
942 if (unlikely((s64)timekeeper.xtime_nsec < 0)) {
943 s64 neg = -(s64)timekeeper.xtime_nsec;
944 timekeeper.xtime_nsec = 0;
945 timekeeper.ntp_error += neg << timekeeper.ntp_error_shift;
946 }
947
948
949 /*
950 * Store full nanoseconds into xtime after rounding it up and
951 * add the remainder to the error difference.
952 */
953 xtime.tv_nsec = ((s64) timekeeper.xtime_nsec >> timekeeper.shift) + 1;
954 timekeeper.xtime_nsec -= (s64) xtime.tv_nsec << timekeeper.shift;
955 timekeeper.ntp_error += timekeeper.xtime_nsec <<
956 timekeeper.ntp_error_shift;
957
958 /*
959 * Finally, make sure that after the rounding
960 * xtime.tv_nsec isn't larger then NSEC_PER_SEC
961 */
962 if (unlikely(xtime.tv_nsec >= NSEC_PER_SEC)) {
963 xtime.tv_nsec -= NSEC_PER_SEC;
964 xtime.tv_sec++;
965 second_overflow();
966 }
967
968 /* check to see if there is a new clocksource to use */
969 update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
970 timekeeper.mult);
971}
972
973/**
974 * getboottime - Return the real time of system boot.
975 * @ts: pointer to the timespec to be set
976 *
977 * Returns the wall-time of boot in a timespec.
978 *
979 * This is based on the wall_to_monotonic offset and the total suspend
980 * time. Calls to settimeofday will affect the value returned (which
981 * basically means that however wrong your real time clock is at boot time,
982 * you get the right time here).
983 */
984void getboottime(struct timespec *ts)
985{
986 struct timespec boottime = {
987 .tv_sec = wall_to_monotonic.tv_sec + total_sleep_time.tv_sec,
988 .tv_nsec = wall_to_monotonic.tv_nsec + total_sleep_time.tv_nsec
989 };
990
991 set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
992}
993EXPORT_SYMBOL_GPL(getboottime);
994
995
996/**
997 * get_monotonic_boottime - Returns monotonic time since boot
998 * @ts: pointer to the timespec to be set
999 *
1000 * Returns the monotonic time since boot in a timespec.
1001 *
1002 * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
1003 * includes the time spent in suspend.
1004 */
1005void get_monotonic_boottime(struct timespec *ts)
1006{
1007 struct timespec tomono, sleep;
1008 unsigned int seq;
1009 s64 nsecs;
1010
1011 WARN_ON(timekeeping_suspended);
1012
1013 do {
1014 seq = read_seqbegin(&xtime_lock);
1015 *ts = xtime;
1016 tomono = wall_to_monotonic;
1017 sleep = total_sleep_time;
1018 nsecs = timekeeping_get_ns();
1019
1020 } while (read_seqretry(&xtime_lock, seq));
1021
1022 set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec + sleep.tv_sec,
1023 ts->tv_nsec + tomono.tv_nsec + sleep.tv_nsec + nsecs);
1024}
1025EXPORT_SYMBOL_GPL(get_monotonic_boottime);
1026
1027/**
1028 * ktime_get_boottime - Returns monotonic time since boot in a ktime
1029 *
1030 * Returns the monotonic time since boot in a ktime
1031 *
1032 * This is similar to CLOCK_MONTONIC/ktime_get, but also
1033 * includes the time spent in suspend.
1034 */
1035ktime_t ktime_get_boottime(void)
1036{
1037 struct timespec ts;
1038
1039 get_monotonic_boottime(&ts);
1040 return timespec_to_ktime(ts);
1041}
1042EXPORT_SYMBOL_GPL(ktime_get_boottime);
1043
1044/**
1045 * monotonic_to_bootbased - Convert the monotonic time to boot based.
1046 * @ts: pointer to the timespec to be converted
1047 */
1048void monotonic_to_bootbased(struct timespec *ts)
1049{
1050 *ts = timespec_add(*ts, total_sleep_time);
1051}
1052EXPORT_SYMBOL_GPL(monotonic_to_bootbased);
1053
1054unsigned long get_seconds(void)
1055{
1056 return xtime.tv_sec;
1057}
1058EXPORT_SYMBOL(get_seconds);
1059
1060struct timespec __current_kernel_time(void)
1061{
1062 return xtime;
1063}
1064
1065struct timespec current_kernel_time(void)
1066{
1067 struct timespec now;
1068 unsigned long seq;
1069
1070 do {
1071 seq = read_seqbegin(&xtime_lock);
1072
1073 now = xtime;
1074 } while (read_seqretry(&xtime_lock, seq));
1075
1076 return now;
1077}
1078EXPORT_SYMBOL(current_kernel_time);
1079
1080struct timespec get_monotonic_coarse(void)
1081{
1082 struct timespec now, mono;
1083 unsigned long seq;
1084
1085 do {
1086 seq = read_seqbegin(&xtime_lock);
1087
1088 now = xtime;
1089 mono = wall_to_monotonic;
1090 } while (read_seqretry(&xtime_lock, seq));
1091
1092 set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
1093 now.tv_nsec + mono.tv_nsec);
1094 return now;
1095}
1096
1097/*
1098 * The 64-bit jiffies value is not atomic - you MUST NOT read it
1099 * without sampling the sequence number in xtime_lock.
1100 * jiffies is defined in the linker script...
1101 */
1102void do_timer(unsigned long ticks)
1103{
1104 jiffies_64 += ticks;
1105 update_wall_time();
1106 calc_global_load(ticks);
1107}
1108
1109/**
1110 * get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic,
1111 * and sleep offsets.
1112 * @xtim: pointer to timespec to be set with xtime
1113 * @wtom: pointer to timespec to be set with wall_to_monotonic
1114 * @sleep: pointer to timespec to be set with time in suspend
1115 */
1116void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
1117 struct timespec *wtom, struct timespec *sleep)
1118{
1119 unsigned long seq;
1120
1121 do {
1122 seq = read_seqbegin(&xtime_lock);
1123 *xtim = xtime;
1124 *wtom = wall_to_monotonic;
1125 *sleep = total_sleep_time;
1126 } while (read_seqretry(&xtime_lock, seq));
1127}
1128
1129/**
1130 * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
1131 */
1132ktime_t ktime_get_monotonic_offset(void)
1133{
1134 unsigned long seq;
1135 struct timespec wtom;
1136
1137 do {
1138 seq = read_seqbegin(&xtime_lock);
1139 wtom = wall_to_monotonic;
1140 } while (read_seqretry(&xtime_lock, seq));
1141 return timespec_to_ktime(wtom);
1142}
1143
1144/**
1145 * xtime_update() - advances the timekeeping infrastructure
1146 * @ticks: number of ticks, that have elapsed since the last call.
1147 *
1148 * Must be called with interrupts disabled.
1149 */
1150void xtime_update(unsigned long ticks)
1151{
1152 write_seqlock(&xtime_lock);
1153 do_timer(ticks);
1154 write_sequnlock(&xtime_lock);
1155}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Kernel timekeeping code and accessor functions. Based on code from
4 * timer.c, moved in commit 8524070b7982.
5 */
6#include <linux/timekeeper_internal.h>
7#include <linux/module.h>
8#include <linux/interrupt.h>
9#include <linux/percpu.h>
10#include <linux/init.h>
11#include <linux/mm.h>
12#include <linux/nmi.h>
13#include <linux/sched.h>
14#include <linux/sched/loadavg.h>
15#include <linux/sched/clock.h>
16#include <linux/syscore_ops.h>
17#include <linux/clocksource.h>
18#include <linux/jiffies.h>
19#include <linux/time.h>
20#include <linux/tick.h>
21#include <linux/stop_machine.h>
22#include <linux/pvclock_gtod.h>
23#include <linux/compiler.h>
24#include <linux/audit.h>
25
26#include "tick-internal.h"
27#include "ntp_internal.h"
28#include "timekeeping_internal.h"
29
30#define TK_CLEAR_NTP (1 << 0)
31#define TK_MIRROR (1 << 1)
32#define TK_CLOCK_WAS_SET (1 << 2)
33
34enum timekeeping_adv_mode {
35 /* Update timekeeper when a tick has passed */
36 TK_ADV_TICK,
37
38 /* Update timekeeper on a direct frequency change */
39 TK_ADV_FREQ
40};
41
42DEFINE_RAW_SPINLOCK(timekeeper_lock);
43
44/*
45 * The most important data for readout fits into a single 64 byte
46 * cache line.
47 */
48static struct {
49 seqcount_raw_spinlock_t seq;
50 struct timekeeper timekeeper;
51} tk_core ____cacheline_aligned = {
52 .seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_core.seq, &timekeeper_lock),
53};
54
55static struct timekeeper shadow_timekeeper;
56
57/**
58 * struct tk_fast - NMI safe timekeeper
59 * @seq: Sequence counter for protecting updates. The lowest bit
60 * is the index for the tk_read_base array
61 * @base: tk_read_base array. Access is indexed by the lowest bit of
62 * @seq.
63 *
64 * See @update_fast_timekeeper() below.
65 */
66struct tk_fast {
67 seqcount_raw_spinlock_t seq;
68 struct tk_read_base base[2];
69};
70
71/* Suspend-time cycles value for halted fast timekeeper. */
72static u64 cycles_at_suspend;
73
74static u64 dummy_clock_read(struct clocksource *cs)
75{
76 return cycles_at_suspend;
77}
78
79static struct clocksource dummy_clock = {
80 .read = dummy_clock_read,
81};
82
83static struct tk_fast tk_fast_mono ____cacheline_aligned = {
84 .seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_fast_mono.seq, &timekeeper_lock),
85 .base[0] = { .clock = &dummy_clock, },
86 .base[1] = { .clock = &dummy_clock, },
87};
88
89static struct tk_fast tk_fast_raw ____cacheline_aligned = {
90 .seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_fast_raw.seq, &timekeeper_lock),
91 .base[0] = { .clock = &dummy_clock, },
92 .base[1] = { .clock = &dummy_clock, },
93};
94
95/* flag for if timekeeping is suspended */
96int __read_mostly timekeeping_suspended;
97
98static inline void tk_normalize_xtime(struct timekeeper *tk)
99{
100 while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
101 tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
102 tk->xtime_sec++;
103 }
104 while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) {
105 tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
106 tk->raw_sec++;
107 }
108}
109
110static inline struct timespec64 tk_xtime(const struct timekeeper *tk)
111{
112 struct timespec64 ts;
113
114 ts.tv_sec = tk->xtime_sec;
115 ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
116 return ts;
117}
118
119static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
120{
121 tk->xtime_sec = ts->tv_sec;
122 tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
123}
124
125static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts)
126{
127 tk->xtime_sec += ts->tv_sec;
128 tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift;
129 tk_normalize_xtime(tk);
130}
131
132static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
133{
134 struct timespec64 tmp;
135
136 /*
137 * Verify consistency of: offset_real = -wall_to_monotonic
138 * before modifying anything
139 */
140 set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
141 -tk->wall_to_monotonic.tv_nsec);
142 WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp));
143 tk->wall_to_monotonic = wtm;
144 set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
145 tk->offs_real = timespec64_to_ktime(tmp);
146 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
147}
148
149static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
150{
151 tk->offs_boot = ktime_add(tk->offs_boot, delta);
152 /*
153 * Timespec representation for VDSO update to avoid 64bit division
154 * on every update.
155 */
156 tk->monotonic_to_boot = ktime_to_timespec64(tk->offs_boot);
157}
158
159/*
160 * tk_clock_read - atomic clocksource read() helper
161 *
162 * This helper is necessary to use in the read paths because, while the
163 * seqcount ensures we don't return a bad value while structures are updated,
164 * it doesn't protect from potential crashes. There is the possibility that
165 * the tkr's clocksource may change between the read reference, and the
166 * clock reference passed to the read function. This can cause crashes if
167 * the wrong clocksource is passed to the wrong read function.
168 * This isn't necessary to use when holding the timekeeper_lock or doing
169 * a read of the fast-timekeeper tkrs (which is protected by its own locking
170 * and update logic).
171 */
172static inline u64 tk_clock_read(const struct tk_read_base *tkr)
173{
174 struct clocksource *clock = READ_ONCE(tkr->clock);
175
176 return clock->read(clock);
177}
178
179#ifdef CONFIG_DEBUG_TIMEKEEPING
180#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
181
182static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
183{
184
185 u64 max_cycles = tk->tkr_mono.clock->max_cycles;
186 const char *name = tk->tkr_mono.clock->name;
187
188 if (offset > max_cycles) {
189 printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
190 offset, name, max_cycles);
191 printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
192 } else {
193 if (offset > (max_cycles >> 1)) {
194 printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
195 offset, name, max_cycles >> 1);
196 printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
197 }
198 }
199
200 if (tk->underflow_seen) {
201 if (jiffies - tk->last_warning > WARNING_FREQ) {
202 printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
203 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
204 printk_deferred(" Your kernel is probably still fine.\n");
205 tk->last_warning = jiffies;
206 }
207 tk->underflow_seen = 0;
208 }
209
210 if (tk->overflow_seen) {
211 if (jiffies - tk->last_warning > WARNING_FREQ) {
212 printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
213 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
214 printk_deferred(" Your kernel is probably still fine.\n");
215 tk->last_warning = jiffies;
216 }
217 tk->overflow_seen = 0;
218 }
219}
220
221static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
222{
223 struct timekeeper *tk = &tk_core.timekeeper;
224 u64 now, last, mask, max, delta;
225 unsigned int seq;
226
227 /*
228 * Since we're called holding a seqcount, the data may shift
229 * under us while we're doing the calculation. This can cause
230 * false positives, since we'd note a problem but throw the
231 * results away. So nest another seqcount here to atomically
232 * grab the points we are checking with.
233 */
234 do {
235 seq = read_seqcount_begin(&tk_core.seq);
236 now = tk_clock_read(tkr);
237 last = tkr->cycle_last;
238 mask = tkr->mask;
239 max = tkr->clock->max_cycles;
240 } while (read_seqcount_retry(&tk_core.seq, seq));
241
242 delta = clocksource_delta(now, last, mask);
243
244 /*
245 * Try to catch underflows by checking if we are seeing small
246 * mask-relative negative values.
247 */
248 if (unlikely((~delta & mask) < (mask >> 3))) {
249 tk->underflow_seen = 1;
250 delta = 0;
251 }
252
253 /* Cap delta value to the max_cycles values to avoid mult overflows */
254 if (unlikely(delta > max)) {
255 tk->overflow_seen = 1;
256 delta = tkr->clock->max_cycles;
257 }
258
259 return delta;
260}
261#else
262static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
263{
264}
265static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
266{
267 u64 cycle_now, delta;
268
269 /* read clocksource */
270 cycle_now = tk_clock_read(tkr);
271
272 /* calculate the delta since the last update_wall_time */
273 delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
274
275 return delta;
276}
277#endif
278
279/**
280 * tk_setup_internals - Set up internals to use clocksource clock.
281 *
282 * @tk: The target timekeeper to setup.
283 * @clock: Pointer to clocksource.
284 *
285 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
286 * pair and interval request.
287 *
288 * Unless you're the timekeeping code, you should not be using this!
289 */
290static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
291{
292 u64 interval;
293 u64 tmp, ntpinterval;
294 struct clocksource *old_clock;
295
296 ++tk->cs_was_changed_seq;
297 old_clock = tk->tkr_mono.clock;
298 tk->tkr_mono.clock = clock;
299 tk->tkr_mono.mask = clock->mask;
300 tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono);
301
302 tk->tkr_raw.clock = clock;
303 tk->tkr_raw.mask = clock->mask;
304 tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
305
306 /* Do the ns -> cycle conversion first, using original mult */
307 tmp = NTP_INTERVAL_LENGTH;
308 tmp <<= clock->shift;
309 ntpinterval = tmp;
310 tmp += clock->mult/2;
311 do_div(tmp, clock->mult);
312 if (tmp == 0)
313 tmp = 1;
314
315 interval = (u64) tmp;
316 tk->cycle_interval = interval;
317
318 /* Go back from cycles -> shifted ns */
319 tk->xtime_interval = interval * clock->mult;
320 tk->xtime_remainder = ntpinterval - tk->xtime_interval;
321 tk->raw_interval = interval * clock->mult;
322
323 /* if changing clocks, convert xtime_nsec shift units */
324 if (old_clock) {
325 int shift_change = clock->shift - old_clock->shift;
326 if (shift_change < 0) {
327 tk->tkr_mono.xtime_nsec >>= -shift_change;
328 tk->tkr_raw.xtime_nsec >>= -shift_change;
329 } else {
330 tk->tkr_mono.xtime_nsec <<= shift_change;
331 tk->tkr_raw.xtime_nsec <<= shift_change;
332 }
333 }
334
335 tk->tkr_mono.shift = clock->shift;
336 tk->tkr_raw.shift = clock->shift;
337
338 tk->ntp_error = 0;
339 tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
340 tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
341
342 /*
343 * The timekeeper keeps its own mult values for the currently
344 * active clocksource. These value will be adjusted via NTP
345 * to counteract clock drifting.
346 */
347 tk->tkr_mono.mult = clock->mult;
348 tk->tkr_raw.mult = clock->mult;
349 tk->ntp_err_mult = 0;
350 tk->skip_second_overflow = 0;
351}
352
353/* Timekeeper helper functions. */
354
355#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
356static u32 default_arch_gettimeoffset(void) { return 0; }
357u32 (*arch_gettimeoffset)(void) = default_arch_gettimeoffset;
358#else
359static inline u32 arch_gettimeoffset(void) { return 0; }
360#endif
361
362static inline u64 timekeeping_delta_to_ns(const struct tk_read_base *tkr, u64 delta)
363{
364 u64 nsec;
365
366 nsec = delta * tkr->mult + tkr->xtime_nsec;
367 nsec >>= tkr->shift;
368
369 /* If arch requires, add in get_arch_timeoffset() */
370 return nsec + arch_gettimeoffset();
371}
372
373static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr)
374{
375 u64 delta;
376
377 delta = timekeeping_get_delta(tkr);
378 return timekeeping_delta_to_ns(tkr, delta);
379}
380
381static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles)
382{
383 u64 delta;
384
385 /* calculate the delta since the last update_wall_time */
386 delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
387 return timekeeping_delta_to_ns(tkr, delta);
388}
389
390/**
391 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
392 * @tkr: Timekeeping readout base from which we take the update
393 *
394 * We want to use this from any context including NMI and tracing /
395 * instrumenting the timekeeping code itself.
396 *
397 * Employ the latch technique; see @raw_write_seqcount_latch.
398 *
399 * So if a NMI hits the update of base[0] then it will use base[1]
400 * which is still consistent. In the worst case this can result is a
401 * slightly wrong timestamp (a few nanoseconds). See
402 * @ktime_get_mono_fast_ns.
403 */
404static void update_fast_timekeeper(const struct tk_read_base *tkr,
405 struct tk_fast *tkf)
406{
407 struct tk_read_base *base = tkf->base;
408
409 /* Force readers off to base[1] */
410 raw_write_seqcount_latch(&tkf->seq);
411
412 /* Update base[0] */
413 memcpy(base, tkr, sizeof(*base));
414
415 /* Force readers back to base[0] */
416 raw_write_seqcount_latch(&tkf->seq);
417
418 /* Update base[1] */
419 memcpy(base + 1, base, sizeof(*base));
420}
421
422/**
423 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
424 *
425 * This timestamp is not guaranteed to be monotonic across an update.
426 * The timestamp is calculated by:
427 *
428 * now = base_mono + clock_delta * slope
429 *
430 * So if the update lowers the slope, readers who are forced to the
431 * not yet updated second array are still using the old steeper slope.
432 *
433 * tmono
434 * ^
435 * | o n
436 * | o n
437 * | u
438 * | o
439 * |o
440 * |12345678---> reader order
441 *
442 * o = old slope
443 * u = update
444 * n = new slope
445 *
446 * So reader 6 will observe time going backwards versus reader 5.
447 *
448 * While other CPUs are likely to be able observe that, the only way
449 * for a CPU local observation is when an NMI hits in the middle of
450 * the update. Timestamps taken from that NMI context might be ahead
451 * of the following timestamps. Callers need to be aware of that and
452 * deal with it.
453 */
454static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
455{
456 struct tk_read_base *tkr;
457 unsigned int seq;
458 u64 now;
459
460 do {
461 seq = raw_read_seqcount_latch(&tkf->seq);
462 tkr = tkf->base + (seq & 0x01);
463 now = ktime_to_ns(tkr->base);
464
465 now += timekeeping_delta_to_ns(tkr,
466 clocksource_delta(
467 tk_clock_read(tkr),
468 tkr->cycle_last,
469 tkr->mask));
470 } while (read_seqcount_retry(&tkf->seq, seq));
471
472 return now;
473}
474
475u64 ktime_get_mono_fast_ns(void)
476{
477 return __ktime_get_fast_ns(&tk_fast_mono);
478}
479EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
480
481u64 ktime_get_raw_fast_ns(void)
482{
483 return __ktime_get_fast_ns(&tk_fast_raw);
484}
485EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
486
487/**
488 * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
489 *
490 * To keep it NMI safe since we're accessing from tracing, we're not using a
491 * separate timekeeper with updates to monotonic clock and boot offset
492 * protected with seqcounts. This has the following minor side effects:
493 *
494 * (1) Its possible that a timestamp be taken after the boot offset is updated
495 * but before the timekeeper is updated. If this happens, the new boot offset
496 * is added to the old timekeeping making the clock appear to update slightly
497 * earlier:
498 * CPU 0 CPU 1
499 * timekeeping_inject_sleeptime64()
500 * __timekeeping_inject_sleeptime(tk, delta);
501 * timestamp();
502 * timekeeping_update(tk, TK_CLEAR_NTP...);
503 *
504 * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
505 * partially updated. Since the tk->offs_boot update is a rare event, this
506 * should be a rare occurrence which postprocessing should be able to handle.
507 */
508u64 notrace ktime_get_boot_fast_ns(void)
509{
510 struct timekeeper *tk = &tk_core.timekeeper;
511
512 return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot));
513}
514EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
515
516
517/*
518 * See comment for __ktime_get_fast_ns() vs. timestamp ordering
519 */
520static __always_inline u64 __ktime_get_real_fast_ns(struct tk_fast *tkf)
521{
522 struct tk_read_base *tkr;
523 unsigned int seq;
524 u64 now;
525
526 do {
527 seq = raw_read_seqcount_latch(&tkf->seq);
528 tkr = tkf->base + (seq & 0x01);
529 now = ktime_to_ns(tkr->base_real);
530
531 now += timekeeping_delta_to_ns(tkr,
532 clocksource_delta(
533 tk_clock_read(tkr),
534 tkr->cycle_last,
535 tkr->mask));
536 } while (read_seqcount_retry(&tkf->seq, seq));
537
538 return now;
539}
540
541/**
542 * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime.
543 */
544u64 ktime_get_real_fast_ns(void)
545{
546 return __ktime_get_real_fast_ns(&tk_fast_mono);
547}
548EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns);
549
550/**
551 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
552 * @tk: Timekeeper to snapshot.
553 *
554 * It generally is unsafe to access the clocksource after timekeeping has been
555 * suspended, so take a snapshot of the readout base of @tk and use it as the
556 * fast timekeeper's readout base while suspended. It will return the same
557 * number of cycles every time until timekeeping is resumed at which time the
558 * proper readout base for the fast timekeeper will be restored automatically.
559 */
560static void halt_fast_timekeeper(const struct timekeeper *tk)
561{
562 static struct tk_read_base tkr_dummy;
563 const struct tk_read_base *tkr = &tk->tkr_mono;
564
565 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
566 cycles_at_suspend = tk_clock_read(tkr);
567 tkr_dummy.clock = &dummy_clock;
568 tkr_dummy.base_real = tkr->base + tk->offs_real;
569 update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
570
571 tkr = &tk->tkr_raw;
572 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
573 tkr_dummy.clock = &dummy_clock;
574 update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
575}
576
577static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
578
579static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
580{
581 raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
582}
583
584/**
585 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
586 */
587int pvclock_gtod_register_notifier(struct notifier_block *nb)
588{
589 struct timekeeper *tk = &tk_core.timekeeper;
590 unsigned long flags;
591 int ret;
592
593 raw_spin_lock_irqsave(&timekeeper_lock, flags);
594 ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
595 update_pvclock_gtod(tk, true);
596 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
597
598 return ret;
599}
600EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
601
602/**
603 * pvclock_gtod_unregister_notifier - unregister a pvclock
604 * timedata update listener
605 */
606int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
607{
608 unsigned long flags;
609 int ret;
610
611 raw_spin_lock_irqsave(&timekeeper_lock, flags);
612 ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
613 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
614
615 return ret;
616}
617EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
618
619/*
620 * tk_update_leap_state - helper to update the next_leap_ktime
621 */
622static inline void tk_update_leap_state(struct timekeeper *tk)
623{
624 tk->next_leap_ktime = ntp_get_next_leap();
625 if (tk->next_leap_ktime != KTIME_MAX)
626 /* Convert to monotonic time */
627 tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
628}
629
630/*
631 * Update the ktime_t based scalar nsec members of the timekeeper
632 */
633static inline void tk_update_ktime_data(struct timekeeper *tk)
634{
635 u64 seconds;
636 u32 nsec;
637
638 /*
639 * The xtime based monotonic readout is:
640 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
641 * The ktime based monotonic readout is:
642 * nsec = base_mono + now();
643 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
644 */
645 seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
646 nsec = (u32) tk->wall_to_monotonic.tv_nsec;
647 tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
648
649 /*
650 * The sum of the nanoseconds portions of xtime and
651 * wall_to_monotonic can be greater/equal one second. Take
652 * this into account before updating tk->ktime_sec.
653 */
654 nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
655 if (nsec >= NSEC_PER_SEC)
656 seconds++;
657 tk->ktime_sec = seconds;
658
659 /* Update the monotonic raw base */
660 tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
661}
662
663/* must hold timekeeper_lock */
664static void timekeeping_update(struct timekeeper *tk, unsigned int action)
665{
666 if (action & TK_CLEAR_NTP) {
667 tk->ntp_error = 0;
668 ntp_clear();
669 }
670
671 tk_update_leap_state(tk);
672 tk_update_ktime_data(tk);
673
674 update_vsyscall(tk);
675 update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
676
677 tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
678 update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
679 update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
680
681 if (action & TK_CLOCK_WAS_SET)
682 tk->clock_was_set_seq++;
683 /*
684 * The mirroring of the data to the shadow-timekeeper needs
685 * to happen last here to ensure we don't over-write the
686 * timekeeper structure on the next update with stale data
687 */
688 if (action & TK_MIRROR)
689 memcpy(&shadow_timekeeper, &tk_core.timekeeper,
690 sizeof(tk_core.timekeeper));
691}
692
693/**
694 * timekeeping_forward_now - update clock to the current time
695 *
696 * Forward the current clock to update its state since the last call to
697 * update_wall_time(). This is useful before significant clock changes,
698 * as it avoids having to deal with this time offset explicitly.
699 */
700static void timekeeping_forward_now(struct timekeeper *tk)
701{
702 u64 cycle_now, delta;
703
704 cycle_now = tk_clock_read(&tk->tkr_mono);
705 delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
706 tk->tkr_mono.cycle_last = cycle_now;
707 tk->tkr_raw.cycle_last = cycle_now;
708
709 tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
710
711 /* If arch requires, add in get_arch_timeoffset() */
712 tk->tkr_mono.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_mono.shift;
713
714
715 tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
716
717 /* If arch requires, add in get_arch_timeoffset() */
718 tk->tkr_raw.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_raw.shift;
719
720 tk_normalize_xtime(tk);
721}
722
723/**
724 * ktime_get_real_ts64 - Returns the time of day in a timespec64.
725 * @ts: pointer to the timespec to be set
726 *
727 * Returns the time of day in a timespec64 (WARN if suspended).
728 */
729void ktime_get_real_ts64(struct timespec64 *ts)
730{
731 struct timekeeper *tk = &tk_core.timekeeper;
732 unsigned int seq;
733 u64 nsecs;
734
735 WARN_ON(timekeeping_suspended);
736
737 do {
738 seq = read_seqcount_begin(&tk_core.seq);
739
740 ts->tv_sec = tk->xtime_sec;
741 nsecs = timekeeping_get_ns(&tk->tkr_mono);
742
743 } while (read_seqcount_retry(&tk_core.seq, seq));
744
745 ts->tv_nsec = 0;
746 timespec64_add_ns(ts, nsecs);
747}
748EXPORT_SYMBOL(ktime_get_real_ts64);
749
750ktime_t ktime_get(void)
751{
752 struct timekeeper *tk = &tk_core.timekeeper;
753 unsigned int seq;
754 ktime_t base;
755 u64 nsecs;
756
757 WARN_ON(timekeeping_suspended);
758
759 do {
760 seq = read_seqcount_begin(&tk_core.seq);
761 base = tk->tkr_mono.base;
762 nsecs = timekeeping_get_ns(&tk->tkr_mono);
763
764 } while (read_seqcount_retry(&tk_core.seq, seq));
765
766 return ktime_add_ns(base, nsecs);
767}
768EXPORT_SYMBOL_GPL(ktime_get);
769
770u32 ktime_get_resolution_ns(void)
771{
772 struct timekeeper *tk = &tk_core.timekeeper;
773 unsigned int seq;
774 u32 nsecs;
775
776 WARN_ON(timekeeping_suspended);
777
778 do {
779 seq = read_seqcount_begin(&tk_core.seq);
780 nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
781 } while (read_seqcount_retry(&tk_core.seq, seq));
782
783 return nsecs;
784}
785EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
786
787static ktime_t *offsets[TK_OFFS_MAX] = {
788 [TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
789 [TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
790 [TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai,
791};
792
793ktime_t ktime_get_with_offset(enum tk_offsets offs)
794{
795 struct timekeeper *tk = &tk_core.timekeeper;
796 unsigned int seq;
797 ktime_t base, *offset = offsets[offs];
798 u64 nsecs;
799
800 WARN_ON(timekeeping_suspended);
801
802 do {
803 seq = read_seqcount_begin(&tk_core.seq);
804 base = ktime_add(tk->tkr_mono.base, *offset);
805 nsecs = timekeeping_get_ns(&tk->tkr_mono);
806
807 } while (read_seqcount_retry(&tk_core.seq, seq));
808
809 return ktime_add_ns(base, nsecs);
810
811}
812EXPORT_SYMBOL_GPL(ktime_get_with_offset);
813
814ktime_t ktime_get_coarse_with_offset(enum tk_offsets offs)
815{
816 struct timekeeper *tk = &tk_core.timekeeper;
817 unsigned int seq;
818 ktime_t base, *offset = offsets[offs];
819 u64 nsecs;
820
821 WARN_ON(timekeeping_suspended);
822
823 do {
824 seq = read_seqcount_begin(&tk_core.seq);
825 base = ktime_add(tk->tkr_mono.base, *offset);
826 nsecs = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
827
828 } while (read_seqcount_retry(&tk_core.seq, seq));
829
830 return ktime_add_ns(base, nsecs);
831}
832EXPORT_SYMBOL_GPL(ktime_get_coarse_with_offset);
833
834/**
835 * ktime_mono_to_any() - convert mononotic time to any other time
836 * @tmono: time to convert.
837 * @offs: which offset to use
838 */
839ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
840{
841 ktime_t *offset = offsets[offs];
842 unsigned int seq;
843 ktime_t tconv;
844
845 do {
846 seq = read_seqcount_begin(&tk_core.seq);
847 tconv = ktime_add(tmono, *offset);
848 } while (read_seqcount_retry(&tk_core.seq, seq));
849
850 return tconv;
851}
852EXPORT_SYMBOL_GPL(ktime_mono_to_any);
853
854/**
855 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
856 */
857ktime_t ktime_get_raw(void)
858{
859 struct timekeeper *tk = &tk_core.timekeeper;
860 unsigned int seq;
861 ktime_t base;
862 u64 nsecs;
863
864 do {
865 seq = read_seqcount_begin(&tk_core.seq);
866 base = tk->tkr_raw.base;
867 nsecs = timekeeping_get_ns(&tk->tkr_raw);
868
869 } while (read_seqcount_retry(&tk_core.seq, seq));
870
871 return ktime_add_ns(base, nsecs);
872}
873EXPORT_SYMBOL_GPL(ktime_get_raw);
874
875/**
876 * ktime_get_ts64 - get the monotonic clock in timespec64 format
877 * @ts: pointer to timespec variable
878 *
879 * The function calculates the monotonic clock from the realtime
880 * clock and the wall_to_monotonic offset and stores the result
881 * in normalized timespec64 format in the variable pointed to by @ts.
882 */
883void ktime_get_ts64(struct timespec64 *ts)
884{
885 struct timekeeper *tk = &tk_core.timekeeper;
886 struct timespec64 tomono;
887 unsigned int seq;
888 u64 nsec;
889
890 WARN_ON(timekeeping_suspended);
891
892 do {
893 seq = read_seqcount_begin(&tk_core.seq);
894 ts->tv_sec = tk->xtime_sec;
895 nsec = timekeeping_get_ns(&tk->tkr_mono);
896 tomono = tk->wall_to_monotonic;
897
898 } while (read_seqcount_retry(&tk_core.seq, seq));
899
900 ts->tv_sec += tomono.tv_sec;
901 ts->tv_nsec = 0;
902 timespec64_add_ns(ts, nsec + tomono.tv_nsec);
903}
904EXPORT_SYMBOL_GPL(ktime_get_ts64);
905
906/**
907 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
908 *
909 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
910 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
911 * works on both 32 and 64 bit systems. On 32 bit systems the readout
912 * covers ~136 years of uptime which should be enough to prevent
913 * premature wrap arounds.
914 */
915time64_t ktime_get_seconds(void)
916{
917 struct timekeeper *tk = &tk_core.timekeeper;
918
919 WARN_ON(timekeeping_suspended);
920 return tk->ktime_sec;
921}
922EXPORT_SYMBOL_GPL(ktime_get_seconds);
923
924/**
925 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
926 *
927 * Returns the wall clock seconds since 1970. This replaces the
928 * get_seconds() interface which is not y2038 safe on 32bit systems.
929 *
930 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
931 * 32bit systems the access must be protected with the sequence
932 * counter to provide "atomic" access to the 64bit tk->xtime_sec
933 * value.
934 */
935time64_t ktime_get_real_seconds(void)
936{
937 struct timekeeper *tk = &tk_core.timekeeper;
938 time64_t seconds;
939 unsigned int seq;
940
941 if (IS_ENABLED(CONFIG_64BIT))
942 return tk->xtime_sec;
943
944 do {
945 seq = read_seqcount_begin(&tk_core.seq);
946 seconds = tk->xtime_sec;
947
948 } while (read_seqcount_retry(&tk_core.seq, seq));
949
950 return seconds;
951}
952EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
953
954/**
955 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
956 * but without the sequence counter protect. This internal function
957 * is called just when timekeeping lock is already held.
958 */
959noinstr time64_t __ktime_get_real_seconds(void)
960{
961 struct timekeeper *tk = &tk_core.timekeeper;
962
963 return tk->xtime_sec;
964}
965
966/**
967 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
968 * @systime_snapshot: pointer to struct receiving the system time snapshot
969 */
970void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
971{
972 struct timekeeper *tk = &tk_core.timekeeper;
973 unsigned int seq;
974 ktime_t base_raw;
975 ktime_t base_real;
976 u64 nsec_raw;
977 u64 nsec_real;
978 u64 now;
979
980 WARN_ON_ONCE(timekeeping_suspended);
981
982 do {
983 seq = read_seqcount_begin(&tk_core.seq);
984 now = tk_clock_read(&tk->tkr_mono);
985 systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
986 systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
987 base_real = ktime_add(tk->tkr_mono.base,
988 tk_core.timekeeper.offs_real);
989 base_raw = tk->tkr_raw.base;
990 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
991 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
992 } while (read_seqcount_retry(&tk_core.seq, seq));
993
994 systime_snapshot->cycles = now;
995 systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
996 systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
997}
998EXPORT_SYMBOL_GPL(ktime_get_snapshot);
999
1000/* Scale base by mult/div checking for overflow */
1001static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
1002{
1003 u64 tmp, rem;
1004
1005 tmp = div64_u64_rem(*base, div, &rem);
1006
1007 if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
1008 ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
1009 return -EOVERFLOW;
1010 tmp *= mult;
1011
1012 rem = div64_u64(rem * mult, div);
1013 *base = tmp + rem;
1014 return 0;
1015}
1016
1017/**
1018 * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
1019 * @history: Snapshot representing start of history
1020 * @partial_history_cycles: Cycle offset into history (fractional part)
1021 * @total_history_cycles: Total history length in cycles
1022 * @discontinuity: True indicates clock was set on history period
1023 * @ts: Cross timestamp that should be adjusted using
1024 * partial/total ratio
1025 *
1026 * Helper function used by get_device_system_crosststamp() to correct the
1027 * crosstimestamp corresponding to the start of the current interval to the
1028 * system counter value (timestamp point) provided by the driver. The
1029 * total_history_* quantities are the total history starting at the provided
1030 * reference point and ending at the start of the current interval. The cycle
1031 * count between the driver timestamp point and the start of the current
1032 * interval is partial_history_cycles.
1033 */
1034static int adjust_historical_crosststamp(struct system_time_snapshot *history,
1035 u64 partial_history_cycles,
1036 u64 total_history_cycles,
1037 bool discontinuity,
1038 struct system_device_crosststamp *ts)
1039{
1040 struct timekeeper *tk = &tk_core.timekeeper;
1041 u64 corr_raw, corr_real;
1042 bool interp_forward;
1043 int ret;
1044
1045 if (total_history_cycles == 0 || partial_history_cycles == 0)
1046 return 0;
1047
1048 /* Interpolate shortest distance from beginning or end of history */
1049 interp_forward = partial_history_cycles > total_history_cycles / 2;
1050 partial_history_cycles = interp_forward ?
1051 total_history_cycles - partial_history_cycles :
1052 partial_history_cycles;
1053
1054 /*
1055 * Scale the monotonic raw time delta by:
1056 * partial_history_cycles / total_history_cycles
1057 */
1058 corr_raw = (u64)ktime_to_ns(
1059 ktime_sub(ts->sys_monoraw, history->raw));
1060 ret = scale64_check_overflow(partial_history_cycles,
1061 total_history_cycles, &corr_raw);
1062 if (ret)
1063 return ret;
1064
1065 /*
1066 * If there is a discontinuity in the history, scale monotonic raw
1067 * correction by:
1068 * mult(real)/mult(raw) yielding the realtime correction
1069 * Otherwise, calculate the realtime correction similar to monotonic
1070 * raw calculation
1071 */
1072 if (discontinuity) {
1073 corr_real = mul_u64_u32_div
1074 (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1075 } else {
1076 corr_real = (u64)ktime_to_ns(
1077 ktime_sub(ts->sys_realtime, history->real));
1078 ret = scale64_check_overflow(partial_history_cycles,
1079 total_history_cycles, &corr_real);
1080 if (ret)
1081 return ret;
1082 }
1083
1084 /* Fixup monotonic raw and real time time values */
1085 if (interp_forward) {
1086 ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1087 ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1088 } else {
1089 ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1090 ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1091 }
1092
1093 return 0;
1094}
1095
1096/*
1097 * cycle_between - true if test occurs chronologically between before and after
1098 */
1099static bool cycle_between(u64 before, u64 test, u64 after)
1100{
1101 if (test > before && test < after)
1102 return true;
1103 if (test < before && before > after)
1104 return true;
1105 return false;
1106}
1107
1108/**
1109 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1110 * @get_time_fn: Callback to get simultaneous device time and
1111 * system counter from the device driver
1112 * @ctx: Context passed to get_time_fn()
1113 * @history_begin: Historical reference point used to interpolate system
1114 * time when counter provided by the driver is before the current interval
1115 * @xtstamp: Receives simultaneously captured system and device time
1116 *
1117 * Reads a timestamp from a device and correlates it to system time
1118 */
1119int get_device_system_crosststamp(int (*get_time_fn)
1120 (ktime_t *device_time,
1121 struct system_counterval_t *sys_counterval,
1122 void *ctx),
1123 void *ctx,
1124 struct system_time_snapshot *history_begin,
1125 struct system_device_crosststamp *xtstamp)
1126{
1127 struct system_counterval_t system_counterval;
1128 struct timekeeper *tk = &tk_core.timekeeper;
1129 u64 cycles, now, interval_start;
1130 unsigned int clock_was_set_seq = 0;
1131 ktime_t base_real, base_raw;
1132 u64 nsec_real, nsec_raw;
1133 u8 cs_was_changed_seq;
1134 unsigned int seq;
1135 bool do_interp;
1136 int ret;
1137
1138 do {
1139 seq = read_seqcount_begin(&tk_core.seq);
1140 /*
1141 * Try to synchronously capture device time and a system
1142 * counter value calling back into the device driver
1143 */
1144 ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1145 if (ret)
1146 return ret;
1147
1148 /*
1149 * Verify that the clocksource associated with the captured
1150 * system counter value is the same as the currently installed
1151 * timekeeper clocksource
1152 */
1153 if (tk->tkr_mono.clock != system_counterval.cs)
1154 return -ENODEV;
1155 cycles = system_counterval.cycles;
1156
1157 /*
1158 * Check whether the system counter value provided by the
1159 * device driver is on the current timekeeping interval.
1160 */
1161 now = tk_clock_read(&tk->tkr_mono);
1162 interval_start = tk->tkr_mono.cycle_last;
1163 if (!cycle_between(interval_start, cycles, now)) {
1164 clock_was_set_seq = tk->clock_was_set_seq;
1165 cs_was_changed_seq = tk->cs_was_changed_seq;
1166 cycles = interval_start;
1167 do_interp = true;
1168 } else {
1169 do_interp = false;
1170 }
1171
1172 base_real = ktime_add(tk->tkr_mono.base,
1173 tk_core.timekeeper.offs_real);
1174 base_raw = tk->tkr_raw.base;
1175
1176 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1177 system_counterval.cycles);
1178 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1179 system_counterval.cycles);
1180 } while (read_seqcount_retry(&tk_core.seq, seq));
1181
1182 xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1183 xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1184
1185 /*
1186 * Interpolate if necessary, adjusting back from the start of the
1187 * current interval
1188 */
1189 if (do_interp) {
1190 u64 partial_history_cycles, total_history_cycles;
1191 bool discontinuity;
1192
1193 /*
1194 * Check that the counter value occurs after the provided
1195 * history reference and that the history doesn't cross a
1196 * clocksource change
1197 */
1198 if (!history_begin ||
1199 !cycle_between(history_begin->cycles,
1200 system_counterval.cycles, cycles) ||
1201 history_begin->cs_was_changed_seq != cs_was_changed_seq)
1202 return -EINVAL;
1203 partial_history_cycles = cycles - system_counterval.cycles;
1204 total_history_cycles = cycles - history_begin->cycles;
1205 discontinuity =
1206 history_begin->clock_was_set_seq != clock_was_set_seq;
1207
1208 ret = adjust_historical_crosststamp(history_begin,
1209 partial_history_cycles,
1210 total_history_cycles,
1211 discontinuity, xtstamp);
1212 if (ret)
1213 return ret;
1214 }
1215
1216 return 0;
1217}
1218EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1219
1220/**
1221 * do_settimeofday64 - Sets the time of day.
1222 * @ts: pointer to the timespec64 variable containing the new time
1223 *
1224 * Sets the time of day to the new time and update NTP and notify hrtimers
1225 */
1226int do_settimeofday64(const struct timespec64 *ts)
1227{
1228 struct timekeeper *tk = &tk_core.timekeeper;
1229 struct timespec64 ts_delta, xt;
1230 unsigned long flags;
1231 int ret = 0;
1232
1233 if (!timespec64_valid_settod(ts))
1234 return -EINVAL;
1235
1236 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1237 write_seqcount_begin(&tk_core.seq);
1238
1239 timekeeping_forward_now(tk);
1240
1241 xt = tk_xtime(tk);
1242 ts_delta.tv_sec = ts->tv_sec - xt.tv_sec;
1243 ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec;
1244
1245 if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1246 ret = -EINVAL;
1247 goto out;
1248 }
1249
1250 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1251
1252 tk_set_xtime(tk, ts);
1253out:
1254 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1255
1256 write_seqcount_end(&tk_core.seq);
1257 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1258
1259 /* signal hrtimers about time change */
1260 clock_was_set();
1261
1262 if (!ret)
1263 audit_tk_injoffset(ts_delta);
1264
1265 return ret;
1266}
1267EXPORT_SYMBOL(do_settimeofday64);
1268
1269/**
1270 * timekeeping_inject_offset - Adds or subtracts from the current time.
1271 * @tv: pointer to the timespec variable containing the offset
1272 *
1273 * Adds or subtracts an offset value from the current time.
1274 */
1275static int timekeeping_inject_offset(const struct timespec64 *ts)
1276{
1277 struct timekeeper *tk = &tk_core.timekeeper;
1278 unsigned long flags;
1279 struct timespec64 tmp;
1280 int ret = 0;
1281
1282 if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
1283 return -EINVAL;
1284
1285 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1286 write_seqcount_begin(&tk_core.seq);
1287
1288 timekeeping_forward_now(tk);
1289
1290 /* Make sure the proposed value is valid */
1291 tmp = timespec64_add(tk_xtime(tk), *ts);
1292 if (timespec64_compare(&tk->wall_to_monotonic, ts) > 0 ||
1293 !timespec64_valid_settod(&tmp)) {
1294 ret = -EINVAL;
1295 goto error;
1296 }
1297
1298 tk_xtime_add(tk, ts);
1299 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *ts));
1300
1301error: /* even if we error out, we forwarded the time, so call update */
1302 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1303
1304 write_seqcount_end(&tk_core.seq);
1305 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1306
1307 /* signal hrtimers about time change */
1308 clock_was_set();
1309
1310 return ret;
1311}
1312
1313/*
1314 * Indicates if there is an offset between the system clock and the hardware
1315 * clock/persistent clock/rtc.
1316 */
1317int persistent_clock_is_local;
1318
1319/*
1320 * Adjust the time obtained from the CMOS to be UTC time instead of
1321 * local time.
1322 *
1323 * This is ugly, but preferable to the alternatives. Otherwise we
1324 * would either need to write a program to do it in /etc/rc (and risk
1325 * confusion if the program gets run more than once; it would also be
1326 * hard to make the program warp the clock precisely n hours) or
1327 * compile in the timezone information into the kernel. Bad, bad....
1328 *
1329 * - TYT, 1992-01-01
1330 *
1331 * The best thing to do is to keep the CMOS clock in universal time (UTC)
1332 * as real UNIX machines always do it. This avoids all headaches about
1333 * daylight saving times and warping kernel clocks.
1334 */
1335void timekeeping_warp_clock(void)
1336{
1337 if (sys_tz.tz_minuteswest != 0) {
1338 struct timespec64 adjust;
1339
1340 persistent_clock_is_local = 1;
1341 adjust.tv_sec = sys_tz.tz_minuteswest * 60;
1342 adjust.tv_nsec = 0;
1343 timekeeping_inject_offset(&adjust);
1344 }
1345}
1346
1347/**
1348 * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1349 *
1350 */
1351static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1352{
1353 tk->tai_offset = tai_offset;
1354 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1355}
1356
1357/**
1358 * change_clocksource - Swaps clocksources if a new one is available
1359 *
1360 * Accumulates current time interval and initializes new clocksource
1361 */
1362static int change_clocksource(void *data)
1363{
1364 struct timekeeper *tk = &tk_core.timekeeper;
1365 struct clocksource *new, *old;
1366 unsigned long flags;
1367
1368 new = (struct clocksource *) data;
1369
1370 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1371 write_seqcount_begin(&tk_core.seq);
1372
1373 timekeeping_forward_now(tk);
1374 /*
1375 * If the cs is in module, get a module reference. Succeeds
1376 * for built-in code (owner == NULL) as well.
1377 */
1378 if (try_module_get(new->owner)) {
1379 if (!new->enable || new->enable(new) == 0) {
1380 old = tk->tkr_mono.clock;
1381 tk_setup_internals(tk, new);
1382 if (old->disable)
1383 old->disable(old);
1384 module_put(old->owner);
1385 } else {
1386 module_put(new->owner);
1387 }
1388 }
1389 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1390
1391 write_seqcount_end(&tk_core.seq);
1392 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1393
1394 return 0;
1395}
1396
1397/**
1398 * timekeeping_notify - Install a new clock source
1399 * @clock: pointer to the clock source
1400 *
1401 * This function is called from clocksource.c after a new, better clock
1402 * source has been registered. The caller holds the clocksource_mutex.
1403 */
1404int timekeeping_notify(struct clocksource *clock)
1405{
1406 struct timekeeper *tk = &tk_core.timekeeper;
1407
1408 if (tk->tkr_mono.clock == clock)
1409 return 0;
1410 stop_machine(change_clocksource, clock, NULL);
1411 tick_clock_notify();
1412 return tk->tkr_mono.clock == clock ? 0 : -1;
1413}
1414
1415/**
1416 * ktime_get_raw_ts64 - Returns the raw monotonic time in a timespec
1417 * @ts: pointer to the timespec64 to be set
1418 *
1419 * Returns the raw monotonic time (completely un-modified by ntp)
1420 */
1421void ktime_get_raw_ts64(struct timespec64 *ts)
1422{
1423 struct timekeeper *tk = &tk_core.timekeeper;
1424 unsigned int seq;
1425 u64 nsecs;
1426
1427 do {
1428 seq = read_seqcount_begin(&tk_core.seq);
1429 ts->tv_sec = tk->raw_sec;
1430 nsecs = timekeeping_get_ns(&tk->tkr_raw);
1431
1432 } while (read_seqcount_retry(&tk_core.seq, seq));
1433
1434 ts->tv_nsec = 0;
1435 timespec64_add_ns(ts, nsecs);
1436}
1437EXPORT_SYMBOL(ktime_get_raw_ts64);
1438
1439
1440/**
1441 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1442 */
1443int timekeeping_valid_for_hres(void)
1444{
1445 struct timekeeper *tk = &tk_core.timekeeper;
1446 unsigned int seq;
1447 int ret;
1448
1449 do {
1450 seq = read_seqcount_begin(&tk_core.seq);
1451
1452 ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1453
1454 } while (read_seqcount_retry(&tk_core.seq, seq));
1455
1456 return ret;
1457}
1458
1459/**
1460 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1461 */
1462u64 timekeeping_max_deferment(void)
1463{
1464 struct timekeeper *tk = &tk_core.timekeeper;
1465 unsigned int seq;
1466 u64 ret;
1467
1468 do {
1469 seq = read_seqcount_begin(&tk_core.seq);
1470
1471 ret = tk->tkr_mono.clock->max_idle_ns;
1472
1473 } while (read_seqcount_retry(&tk_core.seq, seq));
1474
1475 return ret;
1476}
1477
1478/**
1479 * read_persistent_clock64 - Return time from the persistent clock.
1480 *
1481 * Weak dummy function for arches that do not yet support it.
1482 * Reads the time from the battery backed persistent clock.
1483 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1484 *
1485 * XXX - Do be sure to remove it once all arches implement it.
1486 */
1487void __weak read_persistent_clock64(struct timespec64 *ts)
1488{
1489 ts->tv_sec = 0;
1490 ts->tv_nsec = 0;
1491}
1492
1493/**
1494 * read_persistent_wall_and_boot_offset - Read persistent clock, and also offset
1495 * from the boot.
1496 *
1497 * Weak dummy function for arches that do not yet support it.
1498 * wall_time - current time as returned by persistent clock
1499 * boot_offset - offset that is defined as wall_time - boot_time
1500 * The default function calculates offset based on the current value of
1501 * local_clock(). This way architectures that support sched_clock() but don't
1502 * support dedicated boot time clock will provide the best estimate of the
1503 * boot time.
1504 */
1505void __weak __init
1506read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
1507 struct timespec64 *boot_offset)
1508{
1509 read_persistent_clock64(wall_time);
1510 *boot_offset = ns_to_timespec64(local_clock());
1511}
1512
1513/*
1514 * Flag reflecting whether timekeeping_resume() has injected sleeptime.
1515 *
1516 * The flag starts of false and is only set when a suspend reaches
1517 * timekeeping_suspend(), timekeeping_resume() sets it to false when the
1518 * timekeeper clocksource is not stopping across suspend and has been
1519 * used to update sleep time. If the timekeeper clocksource has stopped
1520 * then the flag stays true and is used by the RTC resume code to decide
1521 * whether sleeptime must be injected and if so the flag gets false then.
1522 *
1523 * If a suspend fails before reaching timekeeping_resume() then the flag
1524 * stays false and prevents erroneous sleeptime injection.
1525 */
1526static bool suspend_timing_needed;
1527
1528/* Flag for if there is a persistent clock on this platform */
1529static bool persistent_clock_exists;
1530
1531/*
1532 * timekeeping_init - Initializes the clocksource and common timekeeping values
1533 */
1534void __init timekeeping_init(void)
1535{
1536 struct timespec64 wall_time, boot_offset, wall_to_mono;
1537 struct timekeeper *tk = &tk_core.timekeeper;
1538 struct clocksource *clock;
1539 unsigned long flags;
1540
1541 read_persistent_wall_and_boot_offset(&wall_time, &boot_offset);
1542 if (timespec64_valid_settod(&wall_time) &&
1543 timespec64_to_ns(&wall_time) > 0) {
1544 persistent_clock_exists = true;
1545 } else if (timespec64_to_ns(&wall_time) != 0) {
1546 pr_warn("Persistent clock returned invalid value");
1547 wall_time = (struct timespec64){0};
1548 }
1549
1550 if (timespec64_compare(&wall_time, &boot_offset) < 0)
1551 boot_offset = (struct timespec64){0};
1552
1553 /*
1554 * We want set wall_to_mono, so the following is true:
1555 * wall time + wall_to_mono = boot time
1556 */
1557 wall_to_mono = timespec64_sub(boot_offset, wall_time);
1558
1559 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1560 write_seqcount_begin(&tk_core.seq);
1561 ntp_init();
1562
1563 clock = clocksource_default_clock();
1564 if (clock->enable)
1565 clock->enable(clock);
1566 tk_setup_internals(tk, clock);
1567
1568 tk_set_xtime(tk, &wall_time);
1569 tk->raw_sec = 0;
1570
1571 tk_set_wall_to_mono(tk, wall_to_mono);
1572
1573 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1574
1575 write_seqcount_end(&tk_core.seq);
1576 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1577}
1578
1579/* time in seconds when suspend began for persistent clock */
1580static struct timespec64 timekeeping_suspend_time;
1581
1582/**
1583 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1584 * @delta: pointer to a timespec delta value
1585 *
1586 * Takes a timespec offset measuring a suspend interval and properly
1587 * adds the sleep offset to the timekeeping variables.
1588 */
1589static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1590 const struct timespec64 *delta)
1591{
1592 if (!timespec64_valid_strict(delta)) {
1593 printk_deferred(KERN_WARNING
1594 "__timekeeping_inject_sleeptime: Invalid "
1595 "sleep delta value!\n");
1596 return;
1597 }
1598 tk_xtime_add(tk, delta);
1599 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1600 tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1601 tk_debug_account_sleep_time(delta);
1602}
1603
1604#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1605/**
1606 * We have three kinds of time sources to use for sleep time
1607 * injection, the preference order is:
1608 * 1) non-stop clocksource
1609 * 2) persistent clock (ie: RTC accessible when irqs are off)
1610 * 3) RTC
1611 *
1612 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1613 * If system has neither 1) nor 2), 3) will be used finally.
1614 *
1615 *
1616 * If timekeeping has injected sleeptime via either 1) or 2),
1617 * 3) becomes needless, so in this case we don't need to call
1618 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1619 * means.
1620 */
1621bool timekeeping_rtc_skipresume(void)
1622{
1623 return !suspend_timing_needed;
1624}
1625
1626/**
1627 * 1) can be determined whether to use or not only when doing
1628 * timekeeping_resume() which is invoked after rtc_suspend(),
1629 * so we can't skip rtc_suspend() surely if system has 1).
1630 *
1631 * But if system has 2), 2) will definitely be used, so in this
1632 * case we don't need to call rtc_suspend(), and this is what
1633 * timekeeping_rtc_skipsuspend() means.
1634 */
1635bool timekeeping_rtc_skipsuspend(void)
1636{
1637 return persistent_clock_exists;
1638}
1639
1640/**
1641 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1642 * @delta: pointer to a timespec64 delta value
1643 *
1644 * This hook is for architectures that cannot support read_persistent_clock64
1645 * because their RTC/persistent clock is only accessible when irqs are enabled.
1646 * and also don't have an effective nonstop clocksource.
1647 *
1648 * This function should only be called by rtc_resume(), and allows
1649 * a suspend offset to be injected into the timekeeping values.
1650 */
1651void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
1652{
1653 struct timekeeper *tk = &tk_core.timekeeper;
1654 unsigned long flags;
1655
1656 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1657 write_seqcount_begin(&tk_core.seq);
1658
1659 suspend_timing_needed = false;
1660
1661 timekeeping_forward_now(tk);
1662
1663 __timekeeping_inject_sleeptime(tk, delta);
1664
1665 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1666
1667 write_seqcount_end(&tk_core.seq);
1668 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1669
1670 /* signal hrtimers about time change */
1671 clock_was_set();
1672}
1673#endif
1674
1675/**
1676 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1677 */
1678void timekeeping_resume(void)
1679{
1680 struct timekeeper *tk = &tk_core.timekeeper;
1681 struct clocksource *clock = tk->tkr_mono.clock;
1682 unsigned long flags;
1683 struct timespec64 ts_new, ts_delta;
1684 u64 cycle_now, nsec;
1685 bool inject_sleeptime = false;
1686
1687 read_persistent_clock64(&ts_new);
1688
1689 clockevents_resume();
1690 clocksource_resume();
1691
1692 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1693 write_seqcount_begin(&tk_core.seq);
1694
1695 /*
1696 * After system resumes, we need to calculate the suspended time and
1697 * compensate it for the OS time. There are 3 sources that could be
1698 * used: Nonstop clocksource during suspend, persistent clock and rtc
1699 * device.
1700 *
1701 * One specific platform may have 1 or 2 or all of them, and the
1702 * preference will be:
1703 * suspend-nonstop clocksource -> persistent clock -> rtc
1704 * The less preferred source will only be tried if there is no better
1705 * usable source. The rtc part is handled separately in rtc core code.
1706 */
1707 cycle_now = tk_clock_read(&tk->tkr_mono);
1708 nsec = clocksource_stop_suspend_timing(clock, cycle_now);
1709 if (nsec > 0) {
1710 ts_delta = ns_to_timespec64(nsec);
1711 inject_sleeptime = true;
1712 } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1713 ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1714 inject_sleeptime = true;
1715 }
1716
1717 if (inject_sleeptime) {
1718 suspend_timing_needed = false;
1719 __timekeeping_inject_sleeptime(tk, &ts_delta);
1720 }
1721
1722 /* Re-base the last cycle value */
1723 tk->tkr_mono.cycle_last = cycle_now;
1724 tk->tkr_raw.cycle_last = cycle_now;
1725
1726 tk->ntp_error = 0;
1727 timekeeping_suspended = 0;
1728 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1729 write_seqcount_end(&tk_core.seq);
1730 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1731
1732 touch_softlockup_watchdog();
1733
1734 tick_resume();
1735 hrtimers_resume();
1736}
1737
1738int timekeeping_suspend(void)
1739{
1740 struct timekeeper *tk = &tk_core.timekeeper;
1741 unsigned long flags;
1742 struct timespec64 delta, delta_delta;
1743 static struct timespec64 old_delta;
1744 struct clocksource *curr_clock;
1745 u64 cycle_now;
1746
1747 read_persistent_clock64(&timekeeping_suspend_time);
1748
1749 /*
1750 * On some systems the persistent_clock can not be detected at
1751 * timekeeping_init by its return value, so if we see a valid
1752 * value returned, update the persistent_clock_exists flag.
1753 */
1754 if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1755 persistent_clock_exists = true;
1756
1757 suspend_timing_needed = true;
1758
1759 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1760 write_seqcount_begin(&tk_core.seq);
1761 timekeeping_forward_now(tk);
1762 timekeeping_suspended = 1;
1763
1764 /*
1765 * Since we've called forward_now, cycle_last stores the value
1766 * just read from the current clocksource. Save this to potentially
1767 * use in suspend timing.
1768 */
1769 curr_clock = tk->tkr_mono.clock;
1770 cycle_now = tk->tkr_mono.cycle_last;
1771 clocksource_start_suspend_timing(curr_clock, cycle_now);
1772
1773 if (persistent_clock_exists) {
1774 /*
1775 * To avoid drift caused by repeated suspend/resumes,
1776 * which each can add ~1 second drift error,
1777 * try to compensate so the difference in system time
1778 * and persistent_clock time stays close to constant.
1779 */
1780 delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1781 delta_delta = timespec64_sub(delta, old_delta);
1782 if (abs(delta_delta.tv_sec) >= 2) {
1783 /*
1784 * if delta_delta is too large, assume time correction
1785 * has occurred and set old_delta to the current delta.
1786 */
1787 old_delta = delta;
1788 } else {
1789 /* Otherwise try to adjust old_system to compensate */
1790 timekeeping_suspend_time =
1791 timespec64_add(timekeeping_suspend_time, delta_delta);
1792 }
1793 }
1794
1795 timekeeping_update(tk, TK_MIRROR);
1796 halt_fast_timekeeper(tk);
1797 write_seqcount_end(&tk_core.seq);
1798 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1799
1800 tick_suspend();
1801 clocksource_suspend();
1802 clockevents_suspend();
1803
1804 return 0;
1805}
1806
1807/* sysfs resume/suspend bits for timekeeping */
1808static struct syscore_ops timekeeping_syscore_ops = {
1809 .resume = timekeeping_resume,
1810 .suspend = timekeeping_suspend,
1811};
1812
1813static int __init timekeeping_init_ops(void)
1814{
1815 register_syscore_ops(&timekeeping_syscore_ops);
1816 return 0;
1817}
1818device_initcall(timekeeping_init_ops);
1819
1820/*
1821 * Apply a multiplier adjustment to the timekeeper
1822 */
1823static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1824 s64 offset,
1825 s32 mult_adj)
1826{
1827 s64 interval = tk->cycle_interval;
1828
1829 if (mult_adj == 0) {
1830 return;
1831 } else if (mult_adj == -1) {
1832 interval = -interval;
1833 offset = -offset;
1834 } else if (mult_adj != 1) {
1835 interval *= mult_adj;
1836 offset *= mult_adj;
1837 }
1838
1839 /*
1840 * So the following can be confusing.
1841 *
1842 * To keep things simple, lets assume mult_adj == 1 for now.
1843 *
1844 * When mult_adj != 1, remember that the interval and offset values
1845 * have been appropriately scaled so the math is the same.
1846 *
1847 * The basic idea here is that we're increasing the multiplier
1848 * by one, this causes the xtime_interval to be incremented by
1849 * one cycle_interval. This is because:
1850 * xtime_interval = cycle_interval * mult
1851 * So if mult is being incremented by one:
1852 * xtime_interval = cycle_interval * (mult + 1)
1853 * Its the same as:
1854 * xtime_interval = (cycle_interval * mult) + cycle_interval
1855 * Which can be shortened to:
1856 * xtime_interval += cycle_interval
1857 *
1858 * So offset stores the non-accumulated cycles. Thus the current
1859 * time (in shifted nanoseconds) is:
1860 * now = (offset * adj) + xtime_nsec
1861 * Now, even though we're adjusting the clock frequency, we have
1862 * to keep time consistent. In other words, we can't jump back
1863 * in time, and we also want to avoid jumping forward in time.
1864 *
1865 * So given the same offset value, we need the time to be the same
1866 * both before and after the freq adjustment.
1867 * now = (offset * adj_1) + xtime_nsec_1
1868 * now = (offset * adj_2) + xtime_nsec_2
1869 * So:
1870 * (offset * adj_1) + xtime_nsec_1 =
1871 * (offset * adj_2) + xtime_nsec_2
1872 * And we know:
1873 * adj_2 = adj_1 + 1
1874 * So:
1875 * (offset * adj_1) + xtime_nsec_1 =
1876 * (offset * (adj_1+1)) + xtime_nsec_2
1877 * (offset * adj_1) + xtime_nsec_1 =
1878 * (offset * adj_1) + offset + xtime_nsec_2
1879 * Canceling the sides:
1880 * xtime_nsec_1 = offset + xtime_nsec_2
1881 * Which gives us:
1882 * xtime_nsec_2 = xtime_nsec_1 - offset
1883 * Which simplfies to:
1884 * xtime_nsec -= offset
1885 */
1886 if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1887 /* NTP adjustment caused clocksource mult overflow */
1888 WARN_ON_ONCE(1);
1889 return;
1890 }
1891
1892 tk->tkr_mono.mult += mult_adj;
1893 tk->xtime_interval += interval;
1894 tk->tkr_mono.xtime_nsec -= offset;
1895}
1896
1897/*
1898 * Adjust the timekeeper's multiplier to the correct frequency
1899 * and also to reduce the accumulated error value.
1900 */
1901static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1902{
1903 u32 mult;
1904
1905 /*
1906 * Determine the multiplier from the current NTP tick length.
1907 * Avoid expensive division when the tick length doesn't change.
1908 */
1909 if (likely(tk->ntp_tick == ntp_tick_length())) {
1910 mult = tk->tkr_mono.mult - tk->ntp_err_mult;
1911 } else {
1912 tk->ntp_tick = ntp_tick_length();
1913 mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) -
1914 tk->xtime_remainder, tk->cycle_interval);
1915 }
1916
1917 /*
1918 * If the clock is behind the NTP time, increase the multiplier by 1
1919 * to catch up with it. If it's ahead and there was a remainder in the
1920 * tick division, the clock will slow down. Otherwise it will stay
1921 * ahead until the tick length changes to a non-divisible value.
1922 */
1923 tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0;
1924 mult += tk->ntp_err_mult;
1925
1926 timekeeping_apply_adjustment(tk, offset, mult - tk->tkr_mono.mult);
1927
1928 if (unlikely(tk->tkr_mono.clock->maxadj &&
1929 (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
1930 > tk->tkr_mono.clock->maxadj))) {
1931 printk_once(KERN_WARNING
1932 "Adjusting %s more than 11%% (%ld vs %ld)\n",
1933 tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
1934 (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
1935 }
1936
1937 /*
1938 * It may be possible that when we entered this function, xtime_nsec
1939 * was very small. Further, if we're slightly speeding the clocksource
1940 * in the code above, its possible the required corrective factor to
1941 * xtime_nsec could cause it to underflow.
1942 *
1943 * Now, since we have already accumulated the second and the NTP
1944 * subsystem has been notified via second_overflow(), we need to skip
1945 * the next update.
1946 */
1947 if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
1948 tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC <<
1949 tk->tkr_mono.shift;
1950 tk->xtime_sec--;
1951 tk->skip_second_overflow = 1;
1952 }
1953}
1954
1955/**
1956 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1957 *
1958 * Helper function that accumulates the nsecs greater than a second
1959 * from the xtime_nsec field to the xtime_secs field.
1960 * It also calls into the NTP code to handle leapsecond processing.
1961 *
1962 */
1963static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
1964{
1965 u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
1966 unsigned int clock_set = 0;
1967
1968 while (tk->tkr_mono.xtime_nsec >= nsecps) {
1969 int leap;
1970
1971 tk->tkr_mono.xtime_nsec -= nsecps;
1972 tk->xtime_sec++;
1973
1974 /*
1975 * Skip NTP update if this second was accumulated before,
1976 * i.e. xtime_nsec underflowed in timekeeping_adjust()
1977 */
1978 if (unlikely(tk->skip_second_overflow)) {
1979 tk->skip_second_overflow = 0;
1980 continue;
1981 }
1982
1983 /* Figure out if its a leap sec and apply if needed */
1984 leap = second_overflow(tk->xtime_sec);
1985 if (unlikely(leap)) {
1986 struct timespec64 ts;
1987
1988 tk->xtime_sec += leap;
1989
1990 ts.tv_sec = leap;
1991 ts.tv_nsec = 0;
1992 tk_set_wall_to_mono(tk,
1993 timespec64_sub(tk->wall_to_monotonic, ts));
1994
1995 __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
1996
1997 clock_set = TK_CLOCK_WAS_SET;
1998 }
1999 }
2000 return clock_set;
2001}
2002
2003/**
2004 * logarithmic_accumulation - shifted accumulation of cycles
2005 *
2006 * This functions accumulates a shifted interval of cycles into
2007 * a shifted interval nanoseconds. Allows for O(log) accumulation
2008 * loop.
2009 *
2010 * Returns the unconsumed cycles.
2011 */
2012static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2013 u32 shift, unsigned int *clock_set)
2014{
2015 u64 interval = tk->cycle_interval << shift;
2016 u64 snsec_per_sec;
2017
2018 /* If the offset is smaller than a shifted interval, do nothing */
2019 if (offset < interval)
2020 return offset;
2021
2022 /* Accumulate one shifted interval */
2023 offset -= interval;
2024 tk->tkr_mono.cycle_last += interval;
2025 tk->tkr_raw.cycle_last += interval;
2026
2027 tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2028 *clock_set |= accumulate_nsecs_to_secs(tk);
2029
2030 /* Accumulate raw time */
2031 tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2032 snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2033 while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2034 tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2035 tk->raw_sec++;
2036 }
2037
2038 /* Accumulate error between NTP and clock interval */
2039 tk->ntp_error += tk->ntp_tick << shift;
2040 tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2041 (tk->ntp_error_shift + shift);
2042
2043 return offset;
2044}
2045
2046/*
2047 * timekeeping_advance - Updates the timekeeper to the current time and
2048 * current NTP tick length
2049 */
2050static void timekeeping_advance(enum timekeeping_adv_mode mode)
2051{
2052 struct timekeeper *real_tk = &tk_core.timekeeper;
2053 struct timekeeper *tk = &shadow_timekeeper;
2054 u64 offset;
2055 int shift = 0, maxshift;
2056 unsigned int clock_set = 0;
2057 unsigned long flags;
2058
2059 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2060
2061 /* Make sure we're fully resumed: */
2062 if (unlikely(timekeeping_suspended))
2063 goto out;
2064
2065#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
2066 offset = real_tk->cycle_interval;
2067
2068 if (mode != TK_ADV_TICK)
2069 goto out;
2070#else
2071 offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
2072 tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2073
2074 /* Check if there's really nothing to do */
2075 if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK)
2076 goto out;
2077#endif
2078
2079 /* Do some additional sanity checking */
2080 timekeeping_check_update(tk, offset);
2081
2082 /*
2083 * With NO_HZ we may have to accumulate many cycle_intervals
2084 * (think "ticks") worth of time at once. To do this efficiently,
2085 * we calculate the largest doubling multiple of cycle_intervals
2086 * that is smaller than the offset. We then accumulate that
2087 * chunk in one go, and then try to consume the next smaller
2088 * doubled multiple.
2089 */
2090 shift = ilog2(offset) - ilog2(tk->cycle_interval);
2091 shift = max(0, shift);
2092 /* Bound shift to one less than what overflows tick_length */
2093 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2094 shift = min(shift, maxshift);
2095 while (offset >= tk->cycle_interval) {
2096 offset = logarithmic_accumulation(tk, offset, shift,
2097 &clock_set);
2098 if (offset < tk->cycle_interval<<shift)
2099 shift--;
2100 }
2101
2102 /* Adjust the multiplier to correct NTP error */
2103 timekeeping_adjust(tk, offset);
2104
2105 /*
2106 * Finally, make sure that after the rounding
2107 * xtime_nsec isn't larger than NSEC_PER_SEC
2108 */
2109 clock_set |= accumulate_nsecs_to_secs(tk);
2110
2111 write_seqcount_begin(&tk_core.seq);
2112 /*
2113 * Update the real timekeeper.
2114 *
2115 * We could avoid this memcpy by switching pointers, but that
2116 * requires changes to all other timekeeper usage sites as
2117 * well, i.e. move the timekeeper pointer getter into the
2118 * spinlocked/seqcount protected sections. And we trade this
2119 * memcpy under the tk_core.seq against one before we start
2120 * updating.
2121 */
2122 timekeeping_update(tk, clock_set);
2123 memcpy(real_tk, tk, sizeof(*tk));
2124 /* The memcpy must come last. Do not put anything here! */
2125 write_seqcount_end(&tk_core.seq);
2126out:
2127 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2128 if (clock_set)
2129 /* Have to call _delayed version, since in irq context*/
2130 clock_was_set_delayed();
2131}
2132
2133/**
2134 * update_wall_time - Uses the current clocksource to increment the wall time
2135 *
2136 */
2137void update_wall_time(void)
2138{
2139 timekeeping_advance(TK_ADV_TICK);
2140}
2141
2142/**
2143 * getboottime64 - Return the real time of system boot.
2144 * @ts: pointer to the timespec64 to be set
2145 *
2146 * Returns the wall-time of boot in a timespec64.
2147 *
2148 * This is based on the wall_to_monotonic offset and the total suspend
2149 * time. Calls to settimeofday will affect the value returned (which
2150 * basically means that however wrong your real time clock is at boot time,
2151 * you get the right time here).
2152 */
2153void getboottime64(struct timespec64 *ts)
2154{
2155 struct timekeeper *tk = &tk_core.timekeeper;
2156 ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2157
2158 *ts = ktime_to_timespec64(t);
2159}
2160EXPORT_SYMBOL_GPL(getboottime64);
2161
2162void ktime_get_coarse_real_ts64(struct timespec64 *ts)
2163{
2164 struct timekeeper *tk = &tk_core.timekeeper;
2165 unsigned int seq;
2166
2167 do {
2168 seq = read_seqcount_begin(&tk_core.seq);
2169
2170 *ts = tk_xtime(tk);
2171 } while (read_seqcount_retry(&tk_core.seq, seq));
2172}
2173EXPORT_SYMBOL(ktime_get_coarse_real_ts64);
2174
2175void ktime_get_coarse_ts64(struct timespec64 *ts)
2176{
2177 struct timekeeper *tk = &tk_core.timekeeper;
2178 struct timespec64 now, mono;
2179 unsigned int seq;
2180
2181 do {
2182 seq = read_seqcount_begin(&tk_core.seq);
2183
2184 now = tk_xtime(tk);
2185 mono = tk->wall_to_monotonic;
2186 } while (read_seqcount_retry(&tk_core.seq, seq));
2187
2188 set_normalized_timespec64(ts, now.tv_sec + mono.tv_sec,
2189 now.tv_nsec + mono.tv_nsec);
2190}
2191EXPORT_SYMBOL(ktime_get_coarse_ts64);
2192
2193/*
2194 * Must hold jiffies_lock
2195 */
2196void do_timer(unsigned long ticks)
2197{
2198 jiffies_64 += ticks;
2199 calc_global_load();
2200}
2201
2202/**
2203 * ktime_get_update_offsets_now - hrtimer helper
2204 * @cwsseq: pointer to check and store the clock was set sequence number
2205 * @offs_real: pointer to storage for monotonic -> realtime offset
2206 * @offs_boot: pointer to storage for monotonic -> boottime offset
2207 * @offs_tai: pointer to storage for monotonic -> clock tai offset
2208 *
2209 * Returns current monotonic time and updates the offsets if the
2210 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2211 * different.
2212 *
2213 * Called from hrtimer_interrupt() or retrigger_next_event()
2214 */
2215ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2216 ktime_t *offs_boot, ktime_t *offs_tai)
2217{
2218 struct timekeeper *tk = &tk_core.timekeeper;
2219 unsigned int seq;
2220 ktime_t base;
2221 u64 nsecs;
2222
2223 do {
2224 seq = read_seqcount_begin(&tk_core.seq);
2225
2226 base = tk->tkr_mono.base;
2227 nsecs = timekeeping_get_ns(&tk->tkr_mono);
2228 base = ktime_add_ns(base, nsecs);
2229
2230 if (*cwsseq != tk->clock_was_set_seq) {
2231 *cwsseq = tk->clock_was_set_seq;
2232 *offs_real = tk->offs_real;
2233 *offs_boot = tk->offs_boot;
2234 *offs_tai = tk->offs_tai;
2235 }
2236
2237 /* Handle leapsecond insertion adjustments */
2238 if (unlikely(base >= tk->next_leap_ktime))
2239 *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2240
2241 } while (read_seqcount_retry(&tk_core.seq, seq));
2242
2243 return base;
2244}
2245
2246/**
2247 * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2248 */
2249static int timekeeping_validate_timex(const struct __kernel_timex *txc)
2250{
2251 if (txc->modes & ADJ_ADJTIME) {
2252 /* singleshot must not be used with any other mode bits */
2253 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2254 return -EINVAL;
2255 if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2256 !capable(CAP_SYS_TIME))
2257 return -EPERM;
2258 } else {
2259 /* In order to modify anything, you gotta be super-user! */
2260 if (txc->modes && !capable(CAP_SYS_TIME))
2261 return -EPERM;
2262 /*
2263 * if the quartz is off by more than 10% then
2264 * something is VERY wrong!
2265 */
2266 if (txc->modes & ADJ_TICK &&
2267 (txc->tick < 900000/USER_HZ ||
2268 txc->tick > 1100000/USER_HZ))
2269 return -EINVAL;
2270 }
2271
2272 if (txc->modes & ADJ_SETOFFSET) {
2273 /* In order to inject time, you gotta be super-user! */
2274 if (!capable(CAP_SYS_TIME))
2275 return -EPERM;
2276
2277 /*
2278 * Validate if a timespec/timeval used to inject a time
2279 * offset is valid. Offsets can be postive or negative, so
2280 * we don't check tv_sec. The value of the timeval/timespec
2281 * is the sum of its fields,but *NOTE*:
2282 * The field tv_usec/tv_nsec must always be non-negative and
2283 * we can't have more nanoseconds/microseconds than a second.
2284 */
2285 if (txc->time.tv_usec < 0)
2286 return -EINVAL;
2287
2288 if (txc->modes & ADJ_NANO) {
2289 if (txc->time.tv_usec >= NSEC_PER_SEC)
2290 return -EINVAL;
2291 } else {
2292 if (txc->time.tv_usec >= USEC_PER_SEC)
2293 return -EINVAL;
2294 }
2295 }
2296
2297 /*
2298 * Check for potential multiplication overflows that can
2299 * only happen on 64-bit systems:
2300 */
2301 if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2302 if (LLONG_MIN / PPM_SCALE > txc->freq)
2303 return -EINVAL;
2304 if (LLONG_MAX / PPM_SCALE < txc->freq)
2305 return -EINVAL;
2306 }
2307
2308 return 0;
2309}
2310
2311
2312/**
2313 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2314 */
2315int do_adjtimex(struct __kernel_timex *txc)
2316{
2317 struct timekeeper *tk = &tk_core.timekeeper;
2318 struct audit_ntp_data ad;
2319 unsigned long flags;
2320 struct timespec64 ts;
2321 s32 orig_tai, tai;
2322 int ret;
2323
2324 /* Validate the data before disabling interrupts */
2325 ret = timekeeping_validate_timex(txc);
2326 if (ret)
2327 return ret;
2328
2329 if (txc->modes & ADJ_SETOFFSET) {
2330 struct timespec64 delta;
2331 delta.tv_sec = txc->time.tv_sec;
2332 delta.tv_nsec = txc->time.tv_usec;
2333 if (!(txc->modes & ADJ_NANO))
2334 delta.tv_nsec *= 1000;
2335 ret = timekeeping_inject_offset(&delta);
2336 if (ret)
2337 return ret;
2338
2339 audit_tk_injoffset(delta);
2340 }
2341
2342 audit_ntp_init(&ad);
2343
2344 ktime_get_real_ts64(&ts);
2345
2346 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2347 write_seqcount_begin(&tk_core.seq);
2348
2349 orig_tai = tai = tk->tai_offset;
2350 ret = __do_adjtimex(txc, &ts, &tai, &ad);
2351
2352 if (tai != orig_tai) {
2353 __timekeeping_set_tai_offset(tk, tai);
2354 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2355 }
2356 tk_update_leap_state(tk);
2357
2358 write_seqcount_end(&tk_core.seq);
2359 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2360
2361 audit_ntp_log(&ad);
2362
2363 /* Update the multiplier immediately if frequency was set directly */
2364 if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
2365 timekeeping_advance(TK_ADV_FREQ);
2366
2367 if (tai != orig_tai)
2368 clock_was_set();
2369
2370 ntp_notify_cmos_timer();
2371
2372 return ret;
2373}
2374
2375#ifdef CONFIG_NTP_PPS
2376/**
2377 * hardpps() - Accessor function to NTP __hardpps function
2378 */
2379void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2380{
2381 unsigned long flags;
2382
2383 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2384 write_seqcount_begin(&tk_core.seq);
2385
2386 __hardpps(phase_ts, raw_ts);
2387
2388 write_seqcount_end(&tk_core.seq);
2389 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2390}
2391EXPORT_SYMBOL(hardpps);
2392#endif /* CONFIG_NTP_PPS */
2393
2394/**
2395 * xtime_update() - advances the timekeeping infrastructure
2396 * @ticks: number of ticks, that have elapsed since the last call.
2397 *
2398 * Must be called with interrupts disabled.
2399 */
2400void xtime_update(unsigned long ticks)
2401{
2402 raw_spin_lock(&jiffies_lock);
2403 write_seqcount_begin(&jiffies_seq);
2404 do_timer(ticks);
2405 write_seqcount_end(&jiffies_seq);
2406 raw_spin_unlock(&jiffies_lock);
2407 update_wall_time();
2408}