Loading...
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 /* NTP adjusted clock multiplier */
29 u32 mult;
30 /* The shift value of the current clocksource. */
31 int shift;
32
33 /* Number of clock cycles in one NTP interval. */
34 cycle_t cycle_interval;
35 /* Number of clock shifted nano seconds in one NTP interval. */
36 u64 xtime_interval;
37 /* shifted nano seconds left over when rounding cycle_interval */
38 s64 xtime_remainder;
39 /* Raw nano seconds accumulated per NTP interval. */
40 u32 raw_interval;
41
42 /* Clock shifted nano seconds remainder not stored in xtime.tv_nsec. */
43 u64 xtime_nsec;
44 /* Difference between accumulated time and NTP time in ntp
45 * shifted nano seconds. */
46 s64 ntp_error;
47 /* Shift conversion between clock shifted nano seconds and
48 * ntp shifted nano seconds. */
49 int ntp_error_shift;
50
51 /* The current time */
52 struct timespec xtime;
53 /*
54 * wall_to_monotonic is what we need to add to xtime (or xtime corrected
55 * for sub jiffie times) to get to monotonic time. Monotonic is pegged
56 * at zero at system boot time, so wall_to_monotonic will be negative,
57 * however, we will ALWAYS keep the tv_nsec part positive so we can use
58 * the usual normalization.
59 *
60 * wall_to_monotonic is moved after resume from suspend for the
61 * monotonic time not to jump. We need to add total_sleep_time to
62 * wall_to_monotonic to get the real boot based time offset.
63 *
64 * - wall_to_monotonic is no longer the boot time, getboottime must be
65 * used instead.
66 */
67 struct timespec wall_to_monotonic;
68 /* time spent in suspend */
69 struct timespec total_sleep_time;
70 /* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */
71 struct timespec raw_time;
72
73 /* Offset clock monotonic -> clock realtime */
74 ktime_t offs_real;
75
76 /* Offset clock monotonic -> clock boottime */
77 ktime_t offs_boot;
78
79 /* Seqlock for all timekeeper values */
80 seqlock_t lock;
81};
82
83static struct timekeeper timekeeper;
84
85/*
86 * This read-write spinlock protects us from races in SMP while
87 * playing with xtime.
88 */
89__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
90
91
92/* flag for if timekeeping is suspended */
93int __read_mostly timekeeping_suspended;
94
95
96
97/**
98 * timekeeper_setup_internals - Set up internals to use clocksource clock.
99 *
100 * @clock: Pointer to clocksource.
101 *
102 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
103 * pair and interval request.
104 *
105 * Unless you're the timekeeping code, you should not be using this!
106 */
107static void timekeeper_setup_internals(struct clocksource *clock)
108{
109 cycle_t interval;
110 u64 tmp, ntpinterval;
111
112 timekeeper.clock = clock;
113 clock->cycle_last = clock->read(clock);
114
115 /* Do the ns -> cycle conversion first, using original mult */
116 tmp = NTP_INTERVAL_LENGTH;
117 tmp <<= clock->shift;
118 ntpinterval = tmp;
119 tmp += clock->mult/2;
120 do_div(tmp, clock->mult);
121 if (tmp == 0)
122 tmp = 1;
123
124 interval = (cycle_t) tmp;
125 timekeeper.cycle_interval = interval;
126
127 /* Go back from cycles -> shifted ns */
128 timekeeper.xtime_interval = (u64) interval * clock->mult;
129 timekeeper.xtime_remainder = ntpinterval - timekeeper.xtime_interval;
130 timekeeper.raw_interval =
131 ((u64) interval * clock->mult) >> clock->shift;
132
133 timekeeper.xtime_nsec = 0;
134 timekeeper.shift = clock->shift;
135
136 timekeeper.ntp_error = 0;
137 timekeeper.ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
138
139 /*
140 * The timekeeper keeps its own mult values for the currently
141 * active clocksource. These value will be adjusted via NTP
142 * to counteract clock drifting.
143 */
144 timekeeper.mult = clock->mult;
145}
146
147/* Timekeeper helper functions. */
148static inline s64 timekeeping_get_ns(void)
149{
150 cycle_t cycle_now, cycle_delta;
151 struct clocksource *clock;
152
153 /* read clocksource: */
154 clock = timekeeper.clock;
155 cycle_now = clock->read(clock);
156
157 /* calculate the delta since the last update_wall_time: */
158 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
159
160 /* return delta convert to nanoseconds using ntp adjusted mult. */
161 return clocksource_cyc2ns(cycle_delta, timekeeper.mult,
162 timekeeper.shift);
163}
164
165static inline s64 timekeeping_get_ns_raw(void)
166{
167 cycle_t cycle_now, cycle_delta;
168 struct clocksource *clock;
169
170 /* read clocksource: */
171 clock = timekeeper.clock;
172 cycle_now = clock->read(clock);
173
174 /* calculate the delta since the last update_wall_time: */
175 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
176
177 /* return delta convert to nanoseconds. */
178 return clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
179}
180
181static void update_rt_offset(void)
182{
183 struct timespec tmp, *wtm = &timekeeper.wall_to_monotonic;
184
185 set_normalized_timespec(&tmp, -wtm->tv_sec, -wtm->tv_nsec);
186 timekeeper.offs_real = timespec_to_ktime(tmp);
187}
188
189/* must hold write on timekeeper.lock */
190static void timekeeping_update(bool clearntp)
191{
192 if (clearntp) {
193 timekeeper.ntp_error = 0;
194 ntp_clear();
195 }
196 update_rt_offset();
197 update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,
198 timekeeper.clock, timekeeper.mult);
199}
200
201
202/**
203 * timekeeping_forward_now - update clock to the current time
204 *
205 * Forward the current clock to update its state since the last call to
206 * update_wall_time(). This is useful before significant clock changes,
207 * as it avoids having to deal with this time offset explicitly.
208 */
209static void timekeeping_forward_now(void)
210{
211 cycle_t cycle_now, cycle_delta;
212 struct clocksource *clock;
213 s64 nsec;
214
215 clock = timekeeper.clock;
216 cycle_now = clock->read(clock);
217 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
218 clock->cycle_last = cycle_now;
219
220 nsec = clocksource_cyc2ns(cycle_delta, timekeeper.mult,
221 timekeeper.shift);
222
223 /* If arch requires, add in gettimeoffset() */
224 nsec += arch_gettimeoffset();
225
226 timespec_add_ns(&timekeeper.xtime, nsec);
227
228 nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
229 timespec_add_ns(&timekeeper.raw_time, nsec);
230}
231
232/**
233 * getnstimeofday - Returns the time of day in a timespec
234 * @ts: pointer to the timespec to be set
235 *
236 * Returns the time of day in a timespec.
237 */
238void getnstimeofday(struct timespec *ts)
239{
240 unsigned long seq;
241 s64 nsecs;
242
243 WARN_ON(timekeeping_suspended);
244
245 do {
246 seq = read_seqbegin(&timekeeper.lock);
247
248 *ts = timekeeper.xtime;
249 nsecs = timekeeping_get_ns();
250
251 /* If arch requires, add in gettimeoffset() */
252 nsecs += arch_gettimeoffset();
253
254 } while (read_seqretry(&timekeeper.lock, seq));
255
256 timespec_add_ns(ts, nsecs);
257}
258EXPORT_SYMBOL(getnstimeofday);
259
260ktime_t ktime_get(void)
261{
262 unsigned int seq;
263 s64 secs, nsecs;
264
265 WARN_ON(timekeeping_suspended);
266
267 do {
268 seq = read_seqbegin(&timekeeper.lock);
269 secs = timekeeper.xtime.tv_sec +
270 timekeeper.wall_to_monotonic.tv_sec;
271 nsecs = timekeeper.xtime.tv_nsec +
272 timekeeper.wall_to_monotonic.tv_nsec;
273 nsecs += timekeeping_get_ns();
274 /* If arch requires, add in gettimeoffset() */
275 nsecs += arch_gettimeoffset();
276
277 } while (read_seqretry(&timekeeper.lock, seq));
278 /*
279 * Use ktime_set/ktime_add_ns to create a proper ktime on
280 * 32-bit architectures without CONFIG_KTIME_SCALAR.
281 */
282 return ktime_add_ns(ktime_set(secs, 0), nsecs);
283}
284EXPORT_SYMBOL_GPL(ktime_get);
285
286/**
287 * ktime_get_ts - get the monotonic clock in timespec format
288 * @ts: pointer to timespec variable
289 *
290 * The function calculates the monotonic clock from the realtime
291 * clock and the wall_to_monotonic offset and stores the result
292 * in normalized timespec format in the variable pointed to by @ts.
293 */
294void ktime_get_ts(struct timespec *ts)
295{
296 struct timespec tomono;
297 unsigned int seq;
298 s64 nsecs;
299
300 WARN_ON(timekeeping_suspended);
301
302 do {
303 seq = read_seqbegin(&timekeeper.lock);
304 *ts = timekeeper.xtime;
305 tomono = timekeeper.wall_to_monotonic;
306 nsecs = timekeeping_get_ns();
307 /* If arch requires, add in gettimeoffset() */
308 nsecs += arch_gettimeoffset();
309
310 } while (read_seqretry(&timekeeper.lock, seq));
311
312 set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec,
313 ts->tv_nsec + tomono.tv_nsec + nsecs);
314}
315EXPORT_SYMBOL_GPL(ktime_get_ts);
316
317#ifdef CONFIG_NTP_PPS
318
319/**
320 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
321 * @ts_raw: pointer to the timespec to be set to raw monotonic time
322 * @ts_real: pointer to the timespec to be set to the time of day
323 *
324 * This function reads both the time of day and raw monotonic time at the
325 * same time atomically and stores the resulting timestamps in timespec
326 * format.
327 */
328void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
329{
330 unsigned long seq;
331 s64 nsecs_raw, nsecs_real;
332
333 WARN_ON_ONCE(timekeeping_suspended);
334
335 do {
336 u32 arch_offset;
337
338 seq = read_seqbegin(&timekeeper.lock);
339
340 *ts_raw = timekeeper.raw_time;
341 *ts_real = timekeeper.xtime;
342
343 nsecs_raw = timekeeping_get_ns_raw();
344 nsecs_real = timekeeping_get_ns();
345
346 /* If arch requires, add in gettimeoffset() */
347 arch_offset = arch_gettimeoffset();
348 nsecs_raw += arch_offset;
349 nsecs_real += arch_offset;
350
351 } while (read_seqretry(&timekeeper.lock, seq));
352
353 timespec_add_ns(ts_raw, nsecs_raw);
354 timespec_add_ns(ts_real, nsecs_real);
355}
356EXPORT_SYMBOL(getnstime_raw_and_real);
357
358#endif /* CONFIG_NTP_PPS */
359
360/**
361 * do_gettimeofday - Returns the time of day in a timeval
362 * @tv: pointer to the timeval to be set
363 *
364 * NOTE: Users should be converted to using getnstimeofday()
365 */
366void do_gettimeofday(struct timeval *tv)
367{
368 struct timespec now;
369
370 getnstimeofday(&now);
371 tv->tv_sec = now.tv_sec;
372 tv->tv_usec = now.tv_nsec/1000;
373}
374EXPORT_SYMBOL(do_gettimeofday);
375
376/**
377 * do_settimeofday - Sets the time of day
378 * @tv: pointer to the timespec variable containing the new time
379 *
380 * Sets the time of day to the new time and update NTP and notify hrtimers
381 */
382int do_settimeofday(const struct timespec *tv)
383{
384 struct timespec ts_delta;
385 unsigned long flags;
386
387 if (!timespec_valid_strict(tv))
388 return -EINVAL;
389
390 write_seqlock_irqsave(&timekeeper.lock, flags);
391
392 timekeeping_forward_now();
393
394 ts_delta.tv_sec = tv->tv_sec - timekeeper.xtime.tv_sec;
395 ts_delta.tv_nsec = tv->tv_nsec - timekeeper.xtime.tv_nsec;
396 timekeeper.wall_to_monotonic =
397 timespec_sub(timekeeper.wall_to_monotonic, ts_delta);
398
399 timekeeper.xtime = *tv;
400 timekeeping_update(true);
401
402 write_sequnlock_irqrestore(&timekeeper.lock, flags);
403
404 /* signal hrtimers about time change */
405 clock_was_set();
406
407 return 0;
408}
409EXPORT_SYMBOL(do_settimeofday);
410
411
412/**
413 * timekeeping_inject_offset - Adds or subtracts from the current time.
414 * @tv: pointer to the timespec variable containing the offset
415 *
416 * Adds or subtracts an offset value from the current time.
417 */
418int timekeeping_inject_offset(struct timespec *ts)
419{
420 unsigned long flags;
421 struct timespec tmp;
422 int ret = 0;
423
424 if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
425 return -EINVAL;
426
427 write_seqlock_irqsave(&timekeeper.lock, flags);
428
429 timekeeping_forward_now();
430
431 tmp = timespec_add(timekeeper.xtime, *ts);
432 if (!timespec_valid_strict(&tmp)) {
433 ret = -EINVAL;
434 goto error;
435 }
436
437 timekeeper.xtime = timespec_add(timekeeper.xtime, *ts);
438 timekeeper.wall_to_monotonic =
439 timespec_sub(timekeeper.wall_to_monotonic, *ts);
440
441error: /* even if we error out, we forwarded the time, so call update */
442 timekeeping_update(true);
443
444 write_sequnlock_irqrestore(&timekeeper.lock, flags);
445
446 /* signal hrtimers about time change */
447 clock_was_set();
448
449 return ret;
450}
451EXPORT_SYMBOL(timekeeping_inject_offset);
452
453/**
454 * change_clocksource - Swaps clocksources if a new one is available
455 *
456 * Accumulates current time interval and initializes new clocksource
457 */
458static int change_clocksource(void *data)
459{
460 struct clocksource *new, *old;
461 unsigned long flags;
462
463 new = (struct clocksource *) data;
464
465 write_seqlock_irqsave(&timekeeper.lock, flags);
466
467 timekeeping_forward_now();
468 if (!new->enable || new->enable(new) == 0) {
469 old = timekeeper.clock;
470 timekeeper_setup_internals(new);
471 if (old->disable)
472 old->disable(old);
473 }
474 timekeeping_update(true);
475
476 write_sequnlock_irqrestore(&timekeeper.lock, flags);
477
478 return 0;
479}
480
481/**
482 * timekeeping_notify - Install a new clock source
483 * @clock: pointer to the clock source
484 *
485 * This function is called from clocksource.c after a new, better clock
486 * source has been registered. The caller holds the clocksource_mutex.
487 */
488void timekeeping_notify(struct clocksource *clock)
489{
490 if (timekeeper.clock == clock)
491 return;
492 stop_machine(change_clocksource, clock, NULL);
493 tick_clock_notify();
494}
495
496/**
497 * ktime_get_real - get the real (wall-) time in ktime_t format
498 *
499 * returns the time in ktime_t format
500 */
501ktime_t ktime_get_real(void)
502{
503 struct timespec now;
504
505 getnstimeofday(&now);
506
507 return timespec_to_ktime(now);
508}
509EXPORT_SYMBOL_GPL(ktime_get_real);
510
511/**
512 * getrawmonotonic - Returns the raw monotonic time in a timespec
513 * @ts: pointer to the timespec to be set
514 *
515 * Returns the raw monotonic time (completely un-modified by ntp)
516 */
517void getrawmonotonic(struct timespec *ts)
518{
519 unsigned long seq;
520 s64 nsecs;
521
522 do {
523 seq = read_seqbegin(&timekeeper.lock);
524 nsecs = timekeeping_get_ns_raw();
525 *ts = timekeeper.raw_time;
526
527 } while (read_seqretry(&timekeeper.lock, seq));
528
529 timespec_add_ns(ts, nsecs);
530}
531EXPORT_SYMBOL(getrawmonotonic);
532
533
534/**
535 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
536 */
537int timekeeping_valid_for_hres(void)
538{
539 unsigned long seq;
540 int ret;
541
542 do {
543 seq = read_seqbegin(&timekeeper.lock);
544
545 ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
546
547 } while (read_seqretry(&timekeeper.lock, seq));
548
549 return ret;
550}
551
552/**
553 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
554 */
555u64 timekeeping_max_deferment(void)
556{
557 unsigned long seq;
558 u64 ret;
559 do {
560 seq = read_seqbegin(&timekeeper.lock);
561
562 ret = timekeeper.clock->max_idle_ns;
563
564 } while (read_seqretry(&timekeeper.lock, seq));
565
566 return ret;
567}
568
569/**
570 * read_persistent_clock - Return time from the persistent clock.
571 *
572 * Weak dummy function for arches that do not yet support it.
573 * Reads the time from the battery backed persistent clock.
574 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
575 *
576 * XXX - Do be sure to remove it once all arches implement it.
577 */
578void __attribute__((weak)) read_persistent_clock(struct timespec *ts)
579{
580 ts->tv_sec = 0;
581 ts->tv_nsec = 0;
582}
583
584/**
585 * read_boot_clock - Return time of the system start.
586 *
587 * Weak dummy function for arches that do not yet support it.
588 * Function to read the exact time the system has been started.
589 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
590 *
591 * XXX - Do be sure to remove it once all arches implement it.
592 */
593void __attribute__((weak)) read_boot_clock(struct timespec *ts)
594{
595 ts->tv_sec = 0;
596 ts->tv_nsec = 0;
597}
598
599/*
600 * timekeeping_init - Initializes the clocksource and common timekeeping values
601 */
602void __init timekeeping_init(void)
603{
604 struct clocksource *clock;
605 unsigned long flags;
606 struct timespec now, boot;
607
608 read_persistent_clock(&now);
609 if (!timespec_valid_strict(&now)) {
610 pr_warn("WARNING: Persistent clock returned invalid value!\n"
611 " Check your CMOS/BIOS settings.\n");
612 now.tv_sec = 0;
613 now.tv_nsec = 0;
614 }
615
616 read_boot_clock(&boot);
617 if (!timespec_valid_strict(&boot)) {
618 pr_warn("WARNING: Boot clock returned invalid value!\n"
619 " Check your CMOS/BIOS settings.\n");
620 boot.tv_sec = 0;
621 boot.tv_nsec = 0;
622 }
623
624 seqlock_init(&timekeeper.lock);
625
626 ntp_init();
627
628 write_seqlock_irqsave(&timekeeper.lock, flags);
629 clock = clocksource_default_clock();
630 if (clock->enable)
631 clock->enable(clock);
632 timekeeper_setup_internals(clock);
633
634 timekeeper.xtime.tv_sec = now.tv_sec;
635 timekeeper.xtime.tv_nsec = now.tv_nsec;
636 timekeeper.raw_time.tv_sec = 0;
637 timekeeper.raw_time.tv_nsec = 0;
638 if (boot.tv_sec == 0 && boot.tv_nsec == 0) {
639 boot.tv_sec = timekeeper.xtime.tv_sec;
640 boot.tv_nsec = timekeeper.xtime.tv_nsec;
641 }
642 set_normalized_timespec(&timekeeper.wall_to_monotonic,
643 -boot.tv_sec, -boot.tv_nsec);
644 update_rt_offset();
645 timekeeper.total_sleep_time.tv_sec = 0;
646 timekeeper.total_sleep_time.tv_nsec = 0;
647 write_sequnlock_irqrestore(&timekeeper.lock, flags);
648}
649
650/* time in seconds when suspend began */
651static struct timespec timekeeping_suspend_time;
652
653static void update_sleep_time(struct timespec t)
654{
655 timekeeper.total_sleep_time = t;
656 timekeeper.offs_boot = timespec_to_ktime(t);
657}
658
659/**
660 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
661 * @delta: pointer to a timespec delta value
662 *
663 * Takes a timespec offset measuring a suspend interval and properly
664 * adds the sleep offset to the timekeeping variables.
665 */
666static void __timekeeping_inject_sleeptime(struct timespec *delta)
667{
668 if (!timespec_valid_strict(delta)) {
669 printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
670 "sleep delta value!\n");
671 return;
672 }
673
674 timekeeper.xtime = timespec_add(timekeeper.xtime, *delta);
675 timekeeper.wall_to_monotonic =
676 timespec_sub(timekeeper.wall_to_monotonic, *delta);
677 update_sleep_time(timespec_add(timekeeper.total_sleep_time, *delta));
678}
679
680
681/**
682 * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
683 * @delta: pointer to a timespec delta value
684 *
685 * This hook is for architectures that cannot support read_persistent_clock
686 * because their RTC/persistent clock is only accessible when irqs are enabled.
687 *
688 * This function should only be called by rtc_resume(), and allows
689 * a suspend offset to be injected into the timekeeping values.
690 */
691void timekeeping_inject_sleeptime(struct timespec *delta)
692{
693 unsigned long flags;
694 struct timespec ts;
695
696 /* Make sure we don't set the clock twice */
697 read_persistent_clock(&ts);
698 if (!(ts.tv_sec == 0 && ts.tv_nsec == 0))
699 return;
700
701 write_seqlock_irqsave(&timekeeper.lock, flags);
702
703 timekeeping_forward_now();
704
705 __timekeeping_inject_sleeptime(delta);
706
707 timekeeping_update(true);
708
709 write_sequnlock_irqrestore(&timekeeper.lock, flags);
710
711 /* signal hrtimers about time change */
712 clock_was_set();
713}
714
715
716/**
717 * timekeeping_resume - Resumes the generic timekeeping subsystem.
718 *
719 * This is for the generic clocksource timekeeping.
720 * xtime/wall_to_monotonic/jiffies/etc are
721 * still managed by arch specific suspend/resume code.
722 */
723static void timekeeping_resume(void)
724{
725 unsigned long flags;
726 struct timespec ts;
727
728 read_persistent_clock(&ts);
729
730 clocksource_resume();
731
732 write_seqlock_irqsave(&timekeeper.lock, flags);
733
734 if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {
735 ts = timespec_sub(ts, timekeeping_suspend_time);
736 __timekeeping_inject_sleeptime(&ts);
737 }
738 /* re-base the last cycle value */
739 timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
740 timekeeper.ntp_error = 0;
741 timekeeping_suspended = 0;
742 timekeeping_update(false);
743 write_sequnlock_irqrestore(&timekeeper.lock, flags);
744
745 touch_softlockup_watchdog();
746
747 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
748
749 /* Resume hrtimers */
750 hrtimers_resume();
751}
752
753static int timekeeping_suspend(void)
754{
755 unsigned long flags;
756 struct timespec delta, delta_delta;
757 static struct timespec old_delta;
758
759 read_persistent_clock(&timekeeping_suspend_time);
760
761 write_seqlock_irqsave(&timekeeper.lock, flags);
762 timekeeping_forward_now();
763 timekeeping_suspended = 1;
764
765 /*
766 * To avoid drift caused by repeated suspend/resumes,
767 * which each can add ~1 second drift error,
768 * try to compensate so the difference in system time
769 * and persistent_clock time stays close to constant.
770 */
771 delta = timespec_sub(timekeeper.xtime, timekeeping_suspend_time);
772 delta_delta = timespec_sub(delta, old_delta);
773 if (abs(delta_delta.tv_sec) >= 2) {
774 /*
775 * if delta_delta is too large, assume time correction
776 * has occured and set old_delta to the current delta.
777 */
778 old_delta = delta;
779 } else {
780 /* Otherwise try to adjust old_system to compensate */
781 timekeeping_suspend_time =
782 timespec_add(timekeeping_suspend_time, delta_delta);
783 }
784 write_sequnlock_irqrestore(&timekeeper.lock, flags);
785
786 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
787 clocksource_suspend();
788
789 return 0;
790}
791
792/* sysfs resume/suspend bits for timekeeping */
793static struct syscore_ops timekeeping_syscore_ops = {
794 .resume = timekeeping_resume,
795 .suspend = timekeeping_suspend,
796};
797
798static int __init timekeeping_init_ops(void)
799{
800 register_syscore_ops(&timekeeping_syscore_ops);
801 return 0;
802}
803
804device_initcall(timekeeping_init_ops);
805
806/*
807 * If the error is already larger, we look ahead even further
808 * to compensate for late or lost adjustments.
809 */
810static __always_inline int timekeeping_bigadjust(s64 error, s64 *interval,
811 s64 *offset)
812{
813 s64 tick_error, i;
814 u32 look_ahead, adj;
815 s32 error2, mult;
816
817 /*
818 * Use the current error value to determine how much to look ahead.
819 * The larger the error the slower we adjust for it to avoid problems
820 * with losing too many ticks, otherwise we would overadjust and
821 * produce an even larger error. The smaller the adjustment the
822 * faster we try to adjust for it, as lost ticks can do less harm
823 * here. This is tuned so that an error of about 1 msec is adjusted
824 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
825 */
826 error2 = timekeeper.ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
827 error2 = abs(error2);
828 for (look_ahead = 0; error2 > 0; look_ahead++)
829 error2 >>= 2;
830
831 /*
832 * Now calculate the error in (1 << look_ahead) ticks, but first
833 * remove the single look ahead already included in the error.
834 */
835 tick_error = ntp_tick_length() >> (timekeeper.ntp_error_shift + 1);
836 tick_error -= timekeeper.xtime_interval >> 1;
837 error = ((error - tick_error) >> look_ahead) + tick_error;
838
839 /* Finally calculate the adjustment shift value. */
840 i = *interval;
841 mult = 1;
842 if (error < 0) {
843 error = -error;
844 *interval = -*interval;
845 *offset = -*offset;
846 mult = -1;
847 }
848 for (adj = 0; error > i; adj++)
849 error >>= 1;
850
851 *interval <<= adj;
852 *offset <<= adj;
853 return mult << adj;
854}
855
856/*
857 * Adjust the multiplier to reduce the error value,
858 * this is optimized for the most common adjustments of -1,0,1,
859 * for other values we can do a bit more work.
860 */
861static void timekeeping_adjust(s64 offset)
862{
863 s64 error, interval = timekeeper.cycle_interval;
864 int adj;
865
866 /*
867 * The point of this is to check if the error is greater than half
868 * an interval.
869 *
870 * First we shift it down from NTP_SHIFT to clocksource->shifted nsecs.
871 *
872 * Note we subtract one in the shift, so that error is really error*2.
873 * This "saves" dividing(shifting) interval twice, but keeps the
874 * (error > interval) comparison as still measuring if error is
875 * larger than half an interval.
876 *
877 * Note: It does not "save" on aggravation when reading the code.
878 */
879 error = timekeeper.ntp_error >> (timekeeper.ntp_error_shift - 1);
880 if (error > interval) {
881 /*
882 * We now divide error by 4(via shift), which checks if
883 * the error is greater than twice the interval.
884 * If it is greater, we need a bigadjust, if its smaller,
885 * we can adjust by 1.
886 */
887 error >>= 2;
888 /*
889 * XXX - In update_wall_time, we round up to the next
890 * nanosecond, and store the amount rounded up into
891 * the error. This causes the likely below to be unlikely.
892 *
893 * The proper fix is to avoid rounding up by using
894 * the high precision timekeeper.xtime_nsec instead of
895 * xtime.tv_nsec everywhere. Fixing this will take some
896 * time.
897 */
898 if (likely(error <= interval))
899 adj = 1;
900 else
901 adj = timekeeping_bigadjust(error, &interval, &offset);
902 } else if (error < -interval) {
903 /* See comment above, this is just switched for the negative */
904 error >>= 2;
905 if (likely(error >= -interval)) {
906 adj = -1;
907 interval = -interval;
908 offset = -offset;
909 } else
910 adj = timekeeping_bigadjust(error, &interval, &offset);
911 } else /* No adjustment needed */
912 return;
913
914 if (unlikely(timekeeper.clock->maxadj &&
915 (timekeeper.mult + adj >
916 timekeeper.clock->mult + timekeeper.clock->maxadj))) {
917 printk_once(KERN_WARNING
918 "Adjusting %s more than 11%% (%ld vs %ld)\n",
919 timekeeper.clock->name, (long)timekeeper.mult + adj,
920 (long)timekeeper.clock->mult +
921 timekeeper.clock->maxadj);
922 }
923 /*
924 * So the following can be confusing.
925 *
926 * To keep things simple, lets assume adj == 1 for now.
927 *
928 * When adj != 1, remember that the interval and offset values
929 * have been appropriately scaled so the math is the same.
930 *
931 * The basic idea here is that we're increasing the multiplier
932 * by one, this causes the xtime_interval to be incremented by
933 * one cycle_interval. This is because:
934 * xtime_interval = cycle_interval * mult
935 * So if mult is being incremented by one:
936 * xtime_interval = cycle_interval * (mult + 1)
937 * Its the same as:
938 * xtime_interval = (cycle_interval * mult) + cycle_interval
939 * Which can be shortened to:
940 * xtime_interval += cycle_interval
941 *
942 * So offset stores the non-accumulated cycles. Thus the current
943 * time (in shifted nanoseconds) is:
944 * now = (offset * adj) + xtime_nsec
945 * Now, even though we're adjusting the clock frequency, we have
946 * to keep time consistent. In other words, we can't jump back
947 * in time, and we also want to avoid jumping forward in time.
948 *
949 * So given the same offset value, we need the time to be the same
950 * both before and after the freq adjustment.
951 * now = (offset * adj_1) + xtime_nsec_1
952 * now = (offset * adj_2) + xtime_nsec_2
953 * So:
954 * (offset * adj_1) + xtime_nsec_1 =
955 * (offset * adj_2) + xtime_nsec_2
956 * And we know:
957 * adj_2 = adj_1 + 1
958 * So:
959 * (offset * adj_1) + xtime_nsec_1 =
960 * (offset * (adj_1+1)) + xtime_nsec_2
961 * (offset * adj_1) + xtime_nsec_1 =
962 * (offset * adj_1) + offset + xtime_nsec_2
963 * Canceling the sides:
964 * xtime_nsec_1 = offset + xtime_nsec_2
965 * Which gives us:
966 * xtime_nsec_2 = xtime_nsec_1 - offset
967 * Which simplfies to:
968 * xtime_nsec -= offset
969 *
970 * XXX - TODO: Doc ntp_error calculation.
971 */
972 timekeeper.mult += adj;
973 timekeeper.xtime_interval += interval;
974 timekeeper.xtime_nsec -= offset;
975 timekeeper.ntp_error -= (interval - offset) <<
976 timekeeper.ntp_error_shift;
977}
978
979
980/**
981 * logarithmic_accumulation - shifted accumulation of cycles
982 *
983 * This functions accumulates a shifted interval of cycles into
984 * into a shifted interval nanoseconds. Allows for O(log) accumulation
985 * loop.
986 *
987 * Returns the unconsumed cycles.
988 */
989static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
990{
991 u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift;
992 u64 raw_nsecs;
993
994 /* If the offset is smaller than a shifted interval, do nothing */
995 if (offset < timekeeper.cycle_interval<<shift)
996 return offset;
997
998 /* Accumulate one shifted interval */
999 offset -= timekeeper.cycle_interval << shift;
1000 timekeeper.clock->cycle_last += timekeeper.cycle_interval << shift;
1001
1002 timekeeper.xtime_nsec += timekeeper.xtime_interval << shift;
1003 while (timekeeper.xtime_nsec >= nsecps) {
1004 int leap;
1005 timekeeper.xtime_nsec -= nsecps;
1006 timekeeper.xtime.tv_sec++;
1007 leap = second_overflow(timekeeper.xtime.tv_sec);
1008 timekeeper.xtime.tv_sec += leap;
1009 timekeeper.wall_to_monotonic.tv_sec -= leap;
1010 if (leap)
1011 clock_was_set_delayed();
1012 }
1013
1014 /* Accumulate raw time */
1015 raw_nsecs = timekeeper.raw_interval << shift;
1016 raw_nsecs += timekeeper.raw_time.tv_nsec;
1017 if (raw_nsecs >= NSEC_PER_SEC) {
1018 u64 raw_secs = raw_nsecs;
1019 raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
1020 timekeeper.raw_time.tv_sec += raw_secs;
1021 }
1022 timekeeper.raw_time.tv_nsec = raw_nsecs;
1023
1024 /* Accumulate error between NTP and clock interval */
1025 timekeeper.ntp_error += ntp_tick_length() << shift;
1026 timekeeper.ntp_error -=
1027 (timekeeper.xtime_interval + timekeeper.xtime_remainder) <<
1028 (timekeeper.ntp_error_shift + shift);
1029
1030 return offset;
1031}
1032
1033
1034/**
1035 * update_wall_time - Uses the current clocksource to increment the wall time
1036 *
1037 */
1038static void update_wall_time(void)
1039{
1040 struct clocksource *clock;
1041 cycle_t offset;
1042 int shift = 0, maxshift;
1043 unsigned long flags;
1044
1045 write_seqlock_irqsave(&timekeeper.lock, flags);
1046
1047 /* Make sure we're fully resumed: */
1048 if (unlikely(timekeeping_suspended))
1049 goto out;
1050
1051 clock = timekeeper.clock;
1052
1053#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1054 offset = timekeeper.cycle_interval;
1055#else
1056 offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
1057#endif
1058 /* Check if there's really nothing to do */
1059 if (offset < timekeeper.cycle_interval)
1060 goto out;
1061
1062 timekeeper.xtime_nsec = (s64)timekeeper.xtime.tv_nsec <<
1063 timekeeper.shift;
1064
1065 /*
1066 * With NO_HZ we may have to accumulate many cycle_intervals
1067 * (think "ticks") worth of time at once. To do this efficiently,
1068 * we calculate the largest doubling multiple of cycle_intervals
1069 * that is smaller than the offset. We then accumulate that
1070 * chunk in one go, and then try to consume the next smaller
1071 * doubled multiple.
1072 */
1073 shift = ilog2(offset) - ilog2(timekeeper.cycle_interval);
1074 shift = max(0, shift);
1075 /* Bound shift to one less than what overflows tick_length */
1076 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
1077 shift = min(shift, maxshift);
1078 while (offset >= timekeeper.cycle_interval) {
1079 offset = logarithmic_accumulation(offset, shift);
1080 if(offset < timekeeper.cycle_interval<<shift)
1081 shift--;
1082 }
1083
1084 /* correct the clock when NTP error is too big */
1085 timekeeping_adjust(offset);
1086
1087 /*
1088 * Since in the loop above, we accumulate any amount of time
1089 * in xtime_nsec over a second into xtime.tv_sec, its possible for
1090 * xtime_nsec to be fairly small after the loop. Further, if we're
1091 * slightly speeding the clocksource up in timekeeping_adjust(),
1092 * its possible the required corrective factor to xtime_nsec could
1093 * cause it to underflow.
1094 *
1095 * Now, we cannot simply roll the accumulated second back, since
1096 * the NTP subsystem has been notified via second_overflow. So
1097 * instead we push xtime_nsec forward by the amount we underflowed,
1098 * and add that amount into the error.
1099 *
1100 * We'll correct this error next time through this function, when
1101 * xtime_nsec is not as small.
1102 */
1103 if (unlikely((s64)timekeeper.xtime_nsec < 0)) {
1104 s64 neg = -(s64)timekeeper.xtime_nsec;
1105 timekeeper.xtime_nsec = 0;
1106 timekeeper.ntp_error += neg << timekeeper.ntp_error_shift;
1107 }
1108
1109
1110 /*
1111 * Store full nanoseconds into xtime after rounding it up and
1112 * add the remainder to the error difference.
1113 */
1114 timekeeper.xtime.tv_nsec = ((s64)timekeeper.xtime_nsec >>
1115 timekeeper.shift) + 1;
1116 timekeeper.xtime_nsec -= (s64)timekeeper.xtime.tv_nsec <<
1117 timekeeper.shift;
1118 timekeeper.ntp_error += timekeeper.xtime_nsec <<
1119 timekeeper.ntp_error_shift;
1120
1121 /*
1122 * Finally, make sure that after the rounding
1123 * xtime.tv_nsec isn't larger than NSEC_PER_SEC
1124 */
1125 if (unlikely(timekeeper.xtime.tv_nsec >= NSEC_PER_SEC)) {
1126 int leap;
1127 timekeeper.xtime.tv_nsec -= NSEC_PER_SEC;
1128 timekeeper.xtime.tv_sec++;
1129 leap = second_overflow(timekeeper.xtime.tv_sec);
1130 timekeeper.xtime.tv_sec += leap;
1131 timekeeper.wall_to_monotonic.tv_sec -= leap;
1132 if (leap)
1133 clock_was_set_delayed();
1134 }
1135
1136 timekeeping_update(false);
1137
1138out:
1139 write_sequnlock_irqrestore(&timekeeper.lock, flags);
1140
1141}
1142
1143/**
1144 * getboottime - Return the real time of system boot.
1145 * @ts: pointer to the timespec to be set
1146 *
1147 * Returns the wall-time of boot in a timespec.
1148 *
1149 * This is based on the wall_to_monotonic offset and the total suspend
1150 * time. Calls to settimeofday will affect the value returned (which
1151 * basically means that however wrong your real time clock is at boot time,
1152 * you get the right time here).
1153 */
1154void getboottime(struct timespec *ts)
1155{
1156 struct timespec boottime = {
1157 .tv_sec = timekeeper.wall_to_monotonic.tv_sec +
1158 timekeeper.total_sleep_time.tv_sec,
1159 .tv_nsec = timekeeper.wall_to_monotonic.tv_nsec +
1160 timekeeper.total_sleep_time.tv_nsec
1161 };
1162
1163 set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
1164}
1165EXPORT_SYMBOL_GPL(getboottime);
1166
1167
1168/**
1169 * get_monotonic_boottime - Returns monotonic time since boot
1170 * @ts: pointer to the timespec to be set
1171 *
1172 * Returns the monotonic time since boot in a timespec.
1173 *
1174 * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
1175 * includes the time spent in suspend.
1176 */
1177void get_monotonic_boottime(struct timespec *ts)
1178{
1179 struct timespec tomono, sleep;
1180 unsigned int seq;
1181 s64 nsecs;
1182
1183 WARN_ON(timekeeping_suspended);
1184
1185 do {
1186 seq = read_seqbegin(&timekeeper.lock);
1187 *ts = timekeeper.xtime;
1188 tomono = timekeeper.wall_to_monotonic;
1189 sleep = timekeeper.total_sleep_time;
1190 nsecs = timekeeping_get_ns();
1191
1192 } while (read_seqretry(&timekeeper.lock, seq));
1193
1194 set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec + sleep.tv_sec,
1195 ts->tv_nsec + tomono.tv_nsec + sleep.tv_nsec + nsecs);
1196}
1197EXPORT_SYMBOL_GPL(get_monotonic_boottime);
1198
1199/**
1200 * ktime_get_boottime - Returns monotonic time since boot in a ktime
1201 *
1202 * Returns the monotonic time since boot in a ktime
1203 *
1204 * This is similar to CLOCK_MONTONIC/ktime_get, but also
1205 * includes the time spent in suspend.
1206 */
1207ktime_t ktime_get_boottime(void)
1208{
1209 struct timespec ts;
1210
1211 get_monotonic_boottime(&ts);
1212 return timespec_to_ktime(ts);
1213}
1214EXPORT_SYMBOL_GPL(ktime_get_boottime);
1215
1216/**
1217 * monotonic_to_bootbased - Convert the monotonic time to boot based.
1218 * @ts: pointer to the timespec to be converted
1219 */
1220void monotonic_to_bootbased(struct timespec *ts)
1221{
1222 *ts = timespec_add(*ts, timekeeper.total_sleep_time);
1223}
1224EXPORT_SYMBOL_GPL(monotonic_to_bootbased);
1225
1226unsigned long get_seconds(void)
1227{
1228 return timekeeper.xtime.tv_sec;
1229}
1230EXPORT_SYMBOL(get_seconds);
1231
1232struct timespec __current_kernel_time(void)
1233{
1234 return timekeeper.xtime;
1235}
1236
1237struct timespec current_kernel_time(void)
1238{
1239 struct timespec now;
1240 unsigned long seq;
1241
1242 do {
1243 seq = read_seqbegin(&timekeeper.lock);
1244
1245 now = timekeeper.xtime;
1246 } while (read_seqretry(&timekeeper.lock, seq));
1247
1248 return now;
1249}
1250EXPORT_SYMBOL(current_kernel_time);
1251
1252struct timespec get_monotonic_coarse(void)
1253{
1254 struct timespec now, mono;
1255 unsigned long seq;
1256
1257 do {
1258 seq = read_seqbegin(&timekeeper.lock);
1259
1260 now = timekeeper.xtime;
1261 mono = timekeeper.wall_to_monotonic;
1262 } while (read_seqretry(&timekeeper.lock, seq));
1263
1264 set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
1265 now.tv_nsec + mono.tv_nsec);
1266 return now;
1267}
1268
1269/*
1270 * The 64-bit jiffies value is not atomic - you MUST NOT read it
1271 * without sampling the sequence number in xtime_lock.
1272 * jiffies is defined in the linker script...
1273 */
1274void do_timer(unsigned long ticks)
1275{
1276 jiffies_64 += ticks;
1277 update_wall_time();
1278 calc_global_load(ticks);
1279}
1280
1281/**
1282 * get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic,
1283 * and sleep offsets.
1284 * @xtim: pointer to timespec to be set with xtime
1285 * @wtom: pointer to timespec to be set with wall_to_monotonic
1286 * @sleep: pointer to timespec to be set with time in suspend
1287 */
1288void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
1289 struct timespec *wtom, struct timespec *sleep)
1290{
1291 unsigned long seq;
1292
1293 do {
1294 seq = read_seqbegin(&timekeeper.lock);
1295 *xtim = timekeeper.xtime;
1296 *wtom = timekeeper.wall_to_monotonic;
1297 *sleep = timekeeper.total_sleep_time;
1298 } while (read_seqretry(&timekeeper.lock, seq));
1299}
1300
1301#ifdef CONFIG_HIGH_RES_TIMERS
1302/**
1303 * ktime_get_update_offsets - hrtimer helper
1304 * @offs_real: pointer to storage for monotonic -> realtime offset
1305 * @offs_boot: pointer to storage for monotonic -> boottime offset
1306 *
1307 * Returns current monotonic time and updates the offsets
1308 * Called from hrtimer_interupt() or retrigger_next_event()
1309 */
1310ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot)
1311{
1312 ktime_t now;
1313 unsigned int seq;
1314 u64 secs, nsecs;
1315
1316 do {
1317 seq = read_seqbegin(&timekeeper.lock);
1318
1319 secs = timekeeper.xtime.tv_sec;
1320 nsecs = timekeeper.xtime.tv_nsec;
1321 nsecs += timekeeping_get_ns();
1322 /* If arch requires, add in gettimeoffset() */
1323 nsecs += arch_gettimeoffset();
1324
1325 *offs_real = timekeeper.offs_real;
1326 *offs_boot = timekeeper.offs_boot;
1327 } while (read_seqretry(&timekeeper.lock, seq));
1328
1329 now = ktime_add_ns(ktime_set(secs, 0), nsecs);
1330 now = ktime_sub(now, *offs_real);
1331 return now;
1332}
1333#endif
1334
1335/**
1336 * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
1337 */
1338ktime_t ktime_get_monotonic_offset(void)
1339{
1340 unsigned long seq;
1341 struct timespec wtom;
1342
1343 do {
1344 seq = read_seqbegin(&timekeeper.lock);
1345 wtom = timekeeper.wall_to_monotonic;
1346 } while (read_seqretry(&timekeeper.lock, seq));
1347
1348 return timespec_to_ktime(wtom);
1349}
1350EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset);
1351
1352
1353/**
1354 * xtime_update() - advances the timekeeping infrastructure
1355 * @ticks: number of ticks, that have elapsed since the last call.
1356 *
1357 * Must be called with interrupts disabled.
1358 */
1359void xtime_update(unsigned long ticks)
1360{
1361 write_seqlock(&xtime_lock);
1362 do_timer(ticks);
1363 write_sequnlock(&xtime_lock);
1364}
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/* flag for if timekeeping is suspended */
58int __read_mostly timekeeping_suspended;
59
60/**
61 * struct tk_fast - NMI safe timekeeper
62 * @seq: Sequence counter for protecting updates. The lowest bit
63 * is the index for the tk_read_base array
64 * @base: tk_read_base array. Access is indexed by the lowest bit of
65 * @seq.
66 *
67 * See @update_fast_timekeeper() below.
68 */
69struct tk_fast {
70 seqcount_latch_t seq;
71 struct tk_read_base base[2];
72};
73
74/* Suspend-time cycles value for halted fast timekeeper. */
75static u64 cycles_at_suspend;
76
77static u64 dummy_clock_read(struct clocksource *cs)
78{
79 if (timekeeping_suspended)
80 return cycles_at_suspend;
81 return local_clock();
82}
83
84static struct clocksource dummy_clock = {
85 .read = dummy_clock_read,
86};
87
88/*
89 * Boot time initialization which allows local_clock() to be utilized
90 * during early boot when clocksources are not available. local_clock()
91 * returns nanoseconds already so no conversion is required, hence mult=1
92 * and shift=0. When the first proper clocksource is installed then
93 * the fast time keepers are updated with the correct values.
94 */
95#define FAST_TK_INIT \
96 { \
97 .clock = &dummy_clock, \
98 .mask = CLOCKSOURCE_MASK(64), \
99 .mult = 1, \
100 .shift = 0, \
101 }
102
103static struct tk_fast tk_fast_mono ____cacheline_aligned = {
104 .seq = SEQCNT_LATCH_ZERO(tk_fast_mono.seq),
105 .base[0] = FAST_TK_INIT,
106 .base[1] = FAST_TK_INIT,
107};
108
109static struct tk_fast tk_fast_raw ____cacheline_aligned = {
110 .seq = SEQCNT_LATCH_ZERO(tk_fast_raw.seq),
111 .base[0] = FAST_TK_INIT,
112 .base[1] = FAST_TK_INIT,
113};
114
115static inline void tk_normalize_xtime(struct timekeeper *tk)
116{
117 while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
118 tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
119 tk->xtime_sec++;
120 }
121 while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) {
122 tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
123 tk->raw_sec++;
124 }
125}
126
127static inline struct timespec64 tk_xtime(const struct timekeeper *tk)
128{
129 struct timespec64 ts;
130
131 ts.tv_sec = tk->xtime_sec;
132 ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
133 return ts;
134}
135
136static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
137{
138 tk->xtime_sec = ts->tv_sec;
139 tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
140}
141
142static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts)
143{
144 tk->xtime_sec += ts->tv_sec;
145 tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift;
146 tk_normalize_xtime(tk);
147}
148
149static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
150{
151 struct timespec64 tmp;
152
153 /*
154 * Verify consistency of: offset_real = -wall_to_monotonic
155 * before modifying anything
156 */
157 set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
158 -tk->wall_to_monotonic.tv_nsec);
159 WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp));
160 tk->wall_to_monotonic = wtm;
161 set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
162 tk->offs_real = timespec64_to_ktime(tmp);
163 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
164}
165
166static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
167{
168 tk->offs_boot = ktime_add(tk->offs_boot, delta);
169 /*
170 * Timespec representation for VDSO update to avoid 64bit division
171 * on every update.
172 */
173 tk->monotonic_to_boot = ktime_to_timespec64(tk->offs_boot);
174}
175
176/*
177 * tk_clock_read - atomic clocksource read() helper
178 *
179 * This helper is necessary to use in the read paths because, while the
180 * seqcount ensures we don't return a bad value while structures are updated,
181 * it doesn't protect from potential crashes. There is the possibility that
182 * the tkr's clocksource may change between the read reference, and the
183 * clock reference passed to the read function. This can cause crashes if
184 * the wrong clocksource is passed to the wrong read function.
185 * This isn't necessary to use when holding the timekeeper_lock or doing
186 * a read of the fast-timekeeper tkrs (which is protected by its own locking
187 * and update logic).
188 */
189static inline u64 tk_clock_read(const struct tk_read_base *tkr)
190{
191 struct clocksource *clock = READ_ONCE(tkr->clock);
192
193 return clock->read(clock);
194}
195
196#ifdef CONFIG_DEBUG_TIMEKEEPING
197#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
198
199static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
200{
201
202 u64 max_cycles = tk->tkr_mono.clock->max_cycles;
203 const char *name = tk->tkr_mono.clock->name;
204
205 if (offset > max_cycles) {
206 printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
207 offset, name, max_cycles);
208 printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
209 } else {
210 if (offset > (max_cycles >> 1)) {
211 printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
212 offset, name, max_cycles >> 1);
213 printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
214 }
215 }
216
217 if (tk->underflow_seen) {
218 if (jiffies - tk->last_warning > WARNING_FREQ) {
219 printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
220 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
221 printk_deferred(" Your kernel is probably still fine.\n");
222 tk->last_warning = jiffies;
223 }
224 tk->underflow_seen = 0;
225 }
226
227 if (tk->overflow_seen) {
228 if (jiffies - tk->last_warning > WARNING_FREQ) {
229 printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
230 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
231 printk_deferred(" Your kernel is probably still fine.\n");
232 tk->last_warning = jiffies;
233 }
234 tk->overflow_seen = 0;
235 }
236}
237
238static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
239{
240 struct timekeeper *tk = &tk_core.timekeeper;
241 u64 now, last, mask, max, delta;
242 unsigned int seq;
243
244 /*
245 * Since we're called holding a seqcount, the data may shift
246 * under us while we're doing the calculation. This can cause
247 * false positives, since we'd note a problem but throw the
248 * results away. So nest another seqcount here to atomically
249 * grab the points we are checking with.
250 */
251 do {
252 seq = read_seqcount_begin(&tk_core.seq);
253 now = tk_clock_read(tkr);
254 last = tkr->cycle_last;
255 mask = tkr->mask;
256 max = tkr->clock->max_cycles;
257 } while (read_seqcount_retry(&tk_core.seq, seq));
258
259 delta = clocksource_delta(now, last, mask);
260
261 /*
262 * Try to catch underflows by checking if we are seeing small
263 * mask-relative negative values.
264 */
265 if (unlikely((~delta & mask) < (mask >> 3))) {
266 tk->underflow_seen = 1;
267 delta = 0;
268 }
269
270 /* Cap delta value to the max_cycles values to avoid mult overflows */
271 if (unlikely(delta > max)) {
272 tk->overflow_seen = 1;
273 delta = tkr->clock->max_cycles;
274 }
275
276 return delta;
277}
278#else
279static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
280{
281}
282static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
283{
284 u64 cycle_now, delta;
285
286 /* read clocksource */
287 cycle_now = tk_clock_read(tkr);
288
289 /* calculate the delta since the last update_wall_time */
290 delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
291
292 return delta;
293}
294#endif
295
296/**
297 * tk_setup_internals - Set up internals to use clocksource clock.
298 *
299 * @tk: The target timekeeper to setup.
300 * @clock: Pointer to clocksource.
301 *
302 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
303 * pair and interval request.
304 *
305 * Unless you're the timekeeping code, you should not be using this!
306 */
307static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
308{
309 u64 interval;
310 u64 tmp, ntpinterval;
311 struct clocksource *old_clock;
312
313 ++tk->cs_was_changed_seq;
314 old_clock = tk->tkr_mono.clock;
315 tk->tkr_mono.clock = clock;
316 tk->tkr_mono.mask = clock->mask;
317 tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono);
318
319 tk->tkr_raw.clock = clock;
320 tk->tkr_raw.mask = clock->mask;
321 tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
322
323 /* Do the ns -> cycle conversion first, using original mult */
324 tmp = NTP_INTERVAL_LENGTH;
325 tmp <<= clock->shift;
326 ntpinterval = tmp;
327 tmp += clock->mult/2;
328 do_div(tmp, clock->mult);
329 if (tmp == 0)
330 tmp = 1;
331
332 interval = (u64) tmp;
333 tk->cycle_interval = interval;
334
335 /* Go back from cycles -> shifted ns */
336 tk->xtime_interval = interval * clock->mult;
337 tk->xtime_remainder = ntpinterval - tk->xtime_interval;
338 tk->raw_interval = interval * clock->mult;
339
340 /* if changing clocks, convert xtime_nsec shift units */
341 if (old_clock) {
342 int shift_change = clock->shift - old_clock->shift;
343 if (shift_change < 0) {
344 tk->tkr_mono.xtime_nsec >>= -shift_change;
345 tk->tkr_raw.xtime_nsec >>= -shift_change;
346 } else {
347 tk->tkr_mono.xtime_nsec <<= shift_change;
348 tk->tkr_raw.xtime_nsec <<= shift_change;
349 }
350 }
351
352 tk->tkr_mono.shift = clock->shift;
353 tk->tkr_raw.shift = clock->shift;
354
355 tk->ntp_error = 0;
356 tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
357 tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
358
359 /*
360 * The timekeeper keeps its own mult values for the currently
361 * active clocksource. These value will be adjusted via NTP
362 * to counteract clock drifting.
363 */
364 tk->tkr_mono.mult = clock->mult;
365 tk->tkr_raw.mult = clock->mult;
366 tk->ntp_err_mult = 0;
367 tk->skip_second_overflow = 0;
368}
369
370/* Timekeeper helper functions. */
371
372static inline u64 timekeeping_delta_to_ns(const struct tk_read_base *tkr, u64 delta)
373{
374 u64 nsec;
375
376 nsec = delta * tkr->mult + tkr->xtime_nsec;
377 nsec >>= tkr->shift;
378
379 return nsec;
380}
381
382static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr)
383{
384 u64 delta;
385
386 delta = timekeeping_get_delta(tkr);
387 return timekeeping_delta_to_ns(tkr, delta);
388}
389
390static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles)
391{
392 u64 delta;
393
394 /* calculate the delta since the last update_wall_time */
395 delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
396 return timekeeping_delta_to_ns(tkr, delta);
397}
398
399/**
400 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
401 * @tkr: Timekeeping readout base from which we take the update
402 * @tkf: Pointer to NMI safe timekeeper
403 *
404 * We want to use this from any context including NMI and tracing /
405 * instrumenting the timekeeping code itself.
406 *
407 * Employ the latch technique; see @raw_write_seqcount_latch.
408 *
409 * So if a NMI hits the update of base[0] then it will use base[1]
410 * which is still consistent. In the worst case this can result is a
411 * slightly wrong timestamp (a few nanoseconds). See
412 * @ktime_get_mono_fast_ns.
413 */
414static void update_fast_timekeeper(const struct tk_read_base *tkr,
415 struct tk_fast *tkf)
416{
417 struct tk_read_base *base = tkf->base;
418
419 /* Force readers off to base[1] */
420 raw_write_seqcount_latch(&tkf->seq);
421
422 /* Update base[0] */
423 memcpy(base, tkr, sizeof(*base));
424
425 /* Force readers back to base[0] */
426 raw_write_seqcount_latch(&tkf->seq);
427
428 /* Update base[1] */
429 memcpy(base + 1, base, sizeof(*base));
430}
431
432static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
433{
434 struct tk_read_base *tkr;
435 unsigned int seq;
436 u64 now;
437
438 do {
439 seq = raw_read_seqcount_latch(&tkf->seq);
440 tkr = tkf->base + (seq & 0x01);
441 now = ktime_to_ns(tkr->base);
442
443 now += timekeeping_delta_to_ns(tkr,
444 clocksource_delta(
445 tk_clock_read(tkr),
446 tkr->cycle_last,
447 tkr->mask));
448 } while (read_seqcount_latch_retry(&tkf->seq, seq));
449
450 return now;
451}
452
453/**
454 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
455 *
456 * This timestamp is not guaranteed to be monotonic across an update.
457 * The timestamp is calculated by:
458 *
459 * now = base_mono + clock_delta * slope
460 *
461 * So if the update lowers the slope, readers who are forced to the
462 * not yet updated second array are still using the old steeper slope.
463 *
464 * tmono
465 * ^
466 * | o n
467 * | o n
468 * | u
469 * | o
470 * |o
471 * |12345678---> reader order
472 *
473 * o = old slope
474 * u = update
475 * n = new slope
476 *
477 * So reader 6 will observe time going backwards versus reader 5.
478 *
479 * While other CPUs are likely to be able to observe that, the only way
480 * for a CPU local observation is when an NMI hits in the middle of
481 * the update. Timestamps taken from that NMI context might be ahead
482 * of the following timestamps. Callers need to be aware of that and
483 * deal with it.
484 */
485u64 ktime_get_mono_fast_ns(void)
486{
487 return __ktime_get_fast_ns(&tk_fast_mono);
488}
489EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
490
491/**
492 * ktime_get_raw_fast_ns - Fast NMI safe access to clock monotonic raw
493 *
494 * Contrary to ktime_get_mono_fast_ns() this is always correct because the
495 * conversion factor is not affected by NTP/PTP correction.
496 */
497u64 ktime_get_raw_fast_ns(void)
498{
499 return __ktime_get_fast_ns(&tk_fast_raw);
500}
501EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
502
503/**
504 * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
505 *
506 * To keep it NMI safe since we're accessing from tracing, we're not using a
507 * separate timekeeper with updates to monotonic clock and boot offset
508 * protected with seqcounts. This has the following minor side effects:
509 *
510 * (1) Its possible that a timestamp be taken after the boot offset is updated
511 * but before the timekeeper is updated. If this happens, the new boot offset
512 * is added to the old timekeeping making the clock appear to update slightly
513 * earlier:
514 * CPU 0 CPU 1
515 * timekeeping_inject_sleeptime64()
516 * __timekeeping_inject_sleeptime(tk, delta);
517 * timestamp();
518 * timekeeping_update(tk, TK_CLEAR_NTP...);
519 *
520 * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
521 * partially updated. Since the tk->offs_boot update is a rare event, this
522 * should be a rare occurrence which postprocessing should be able to handle.
523 *
524 * The caveats vs. timestamp ordering as documented for ktime_get_fast_ns()
525 * apply as well.
526 */
527u64 notrace ktime_get_boot_fast_ns(void)
528{
529 struct timekeeper *tk = &tk_core.timekeeper;
530
531 return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot));
532}
533EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
534
535static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono)
536{
537 struct tk_read_base *tkr;
538 u64 basem, baser, delta;
539 unsigned int seq;
540
541 do {
542 seq = raw_read_seqcount_latch(&tkf->seq);
543 tkr = tkf->base + (seq & 0x01);
544 basem = ktime_to_ns(tkr->base);
545 baser = ktime_to_ns(tkr->base_real);
546
547 delta = timekeeping_delta_to_ns(tkr,
548 clocksource_delta(tk_clock_read(tkr),
549 tkr->cycle_last, tkr->mask));
550 } while (read_seqcount_latch_retry(&tkf->seq, seq));
551
552 if (mono)
553 *mono = basem + delta;
554 return baser + delta;
555}
556
557/**
558 * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime.
559 *
560 * See ktime_get_fast_ns() for documentation of the time stamp ordering.
561 */
562u64 ktime_get_real_fast_ns(void)
563{
564 return __ktime_get_real_fast(&tk_fast_mono, NULL);
565}
566EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns);
567
568/**
569 * ktime_get_fast_timestamps: - NMI safe timestamps
570 * @snapshot: Pointer to timestamp storage
571 *
572 * Stores clock monotonic, boottime and realtime timestamps.
573 *
574 * Boot time is a racy access on 32bit systems if the sleep time injection
575 * happens late during resume and not in timekeeping_resume(). That could
576 * be avoided by expanding struct tk_read_base with boot offset for 32bit
577 * and adding more overhead to the update. As this is a hard to observe
578 * once per resume event which can be filtered with reasonable effort using
579 * the accurate mono/real timestamps, it's probably not worth the trouble.
580 *
581 * Aside of that it might be possible on 32 and 64 bit to observe the
582 * following when the sleep time injection happens late:
583 *
584 * CPU 0 CPU 1
585 * timekeeping_resume()
586 * ktime_get_fast_timestamps()
587 * mono, real = __ktime_get_real_fast()
588 * inject_sleep_time()
589 * update boot offset
590 * boot = mono + bootoffset;
591 *
592 * That means that boot time already has the sleep time adjustment, but
593 * real time does not. On the next readout both are in sync again.
594 *
595 * Preventing this for 64bit is not really feasible without destroying the
596 * careful cache layout of the timekeeper because the sequence count and
597 * struct tk_read_base would then need two cache lines instead of one.
598 *
599 * Access to the time keeper clock source is disabled across the innermost
600 * steps of suspend/resume. The accessors still work, but the timestamps
601 * are frozen until time keeping is resumed which happens very early.
602 *
603 * For regular suspend/resume there is no observable difference vs. sched
604 * clock, but it might affect some of the nasty low level debug printks.
605 *
606 * OTOH, access to sched clock is not guaranteed across suspend/resume on
607 * all systems either so it depends on the hardware in use.
608 *
609 * If that turns out to be a real problem then this could be mitigated by
610 * using sched clock in a similar way as during early boot. But it's not as
611 * trivial as on early boot because it needs some careful protection
612 * against the clock monotonic timestamp jumping backwards on resume.
613 */
614void ktime_get_fast_timestamps(struct ktime_timestamps *snapshot)
615{
616 struct timekeeper *tk = &tk_core.timekeeper;
617
618 snapshot->real = __ktime_get_real_fast(&tk_fast_mono, &snapshot->mono);
619 snapshot->boot = snapshot->mono + ktime_to_ns(data_race(tk->offs_boot));
620}
621
622/**
623 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
624 * @tk: Timekeeper to snapshot.
625 *
626 * It generally is unsafe to access the clocksource after timekeeping has been
627 * suspended, so take a snapshot of the readout base of @tk and use it as the
628 * fast timekeeper's readout base while suspended. It will return the same
629 * number of cycles every time until timekeeping is resumed at which time the
630 * proper readout base for the fast timekeeper will be restored automatically.
631 */
632static void halt_fast_timekeeper(const struct timekeeper *tk)
633{
634 static struct tk_read_base tkr_dummy;
635 const struct tk_read_base *tkr = &tk->tkr_mono;
636
637 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
638 cycles_at_suspend = tk_clock_read(tkr);
639 tkr_dummy.clock = &dummy_clock;
640 tkr_dummy.base_real = tkr->base + tk->offs_real;
641 update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
642
643 tkr = &tk->tkr_raw;
644 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
645 tkr_dummy.clock = &dummy_clock;
646 update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
647}
648
649static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
650
651static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
652{
653 raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
654}
655
656/**
657 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
658 * @nb: Pointer to the notifier block to register
659 */
660int pvclock_gtod_register_notifier(struct notifier_block *nb)
661{
662 struct timekeeper *tk = &tk_core.timekeeper;
663 unsigned long flags;
664 int ret;
665
666 raw_spin_lock_irqsave(&timekeeper_lock, flags);
667 ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
668 update_pvclock_gtod(tk, true);
669 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
670
671 return ret;
672}
673EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
674
675/**
676 * pvclock_gtod_unregister_notifier - unregister a pvclock
677 * timedata update listener
678 * @nb: Pointer to the notifier block to unregister
679 */
680int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
681{
682 unsigned long flags;
683 int ret;
684
685 raw_spin_lock_irqsave(&timekeeper_lock, flags);
686 ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
687 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
688
689 return ret;
690}
691EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
692
693/*
694 * tk_update_leap_state - helper to update the next_leap_ktime
695 */
696static inline void tk_update_leap_state(struct timekeeper *tk)
697{
698 tk->next_leap_ktime = ntp_get_next_leap();
699 if (tk->next_leap_ktime != KTIME_MAX)
700 /* Convert to monotonic time */
701 tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
702}
703
704/*
705 * Update the ktime_t based scalar nsec members of the timekeeper
706 */
707static inline void tk_update_ktime_data(struct timekeeper *tk)
708{
709 u64 seconds;
710 u32 nsec;
711
712 /*
713 * The xtime based monotonic readout is:
714 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
715 * The ktime based monotonic readout is:
716 * nsec = base_mono + now();
717 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
718 */
719 seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
720 nsec = (u32) tk->wall_to_monotonic.tv_nsec;
721 tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
722
723 /*
724 * The sum of the nanoseconds portions of xtime and
725 * wall_to_monotonic can be greater/equal one second. Take
726 * this into account before updating tk->ktime_sec.
727 */
728 nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
729 if (nsec >= NSEC_PER_SEC)
730 seconds++;
731 tk->ktime_sec = seconds;
732
733 /* Update the monotonic raw base */
734 tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
735}
736
737/* must hold timekeeper_lock */
738static void timekeeping_update(struct timekeeper *tk, unsigned int action)
739{
740 if (action & TK_CLEAR_NTP) {
741 tk->ntp_error = 0;
742 ntp_clear();
743 }
744
745 tk_update_leap_state(tk);
746 tk_update_ktime_data(tk);
747
748 update_vsyscall(tk);
749 update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
750
751 tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
752 update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
753 update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
754
755 if (action & TK_CLOCK_WAS_SET)
756 tk->clock_was_set_seq++;
757 /*
758 * The mirroring of the data to the shadow-timekeeper needs
759 * to happen last here to ensure we don't over-write the
760 * timekeeper structure on the next update with stale data
761 */
762 if (action & TK_MIRROR)
763 memcpy(&shadow_timekeeper, &tk_core.timekeeper,
764 sizeof(tk_core.timekeeper));
765}
766
767/**
768 * timekeeping_forward_now - update clock to the current time
769 * @tk: Pointer to the timekeeper to update
770 *
771 * Forward the current clock to update its state since the last call to
772 * update_wall_time(). This is useful before significant clock changes,
773 * as it avoids having to deal with this time offset explicitly.
774 */
775static void timekeeping_forward_now(struct timekeeper *tk)
776{
777 u64 cycle_now, delta;
778
779 cycle_now = tk_clock_read(&tk->tkr_mono);
780 delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
781 tk->tkr_mono.cycle_last = cycle_now;
782 tk->tkr_raw.cycle_last = cycle_now;
783
784 tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
785 tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
786
787 tk_normalize_xtime(tk);
788}
789
790/**
791 * ktime_get_real_ts64 - Returns the time of day in a timespec64.
792 * @ts: pointer to the timespec to be set
793 *
794 * Returns the time of day in a timespec64 (WARN if suspended).
795 */
796void ktime_get_real_ts64(struct timespec64 *ts)
797{
798 struct timekeeper *tk = &tk_core.timekeeper;
799 unsigned int seq;
800 u64 nsecs;
801
802 WARN_ON(timekeeping_suspended);
803
804 do {
805 seq = read_seqcount_begin(&tk_core.seq);
806
807 ts->tv_sec = tk->xtime_sec;
808 nsecs = timekeeping_get_ns(&tk->tkr_mono);
809
810 } while (read_seqcount_retry(&tk_core.seq, seq));
811
812 ts->tv_nsec = 0;
813 timespec64_add_ns(ts, nsecs);
814}
815EXPORT_SYMBOL(ktime_get_real_ts64);
816
817ktime_t ktime_get(void)
818{
819 struct timekeeper *tk = &tk_core.timekeeper;
820 unsigned int seq;
821 ktime_t base;
822 u64 nsecs;
823
824 WARN_ON(timekeeping_suspended);
825
826 do {
827 seq = read_seqcount_begin(&tk_core.seq);
828 base = tk->tkr_mono.base;
829 nsecs = timekeeping_get_ns(&tk->tkr_mono);
830
831 } while (read_seqcount_retry(&tk_core.seq, seq));
832
833 return ktime_add_ns(base, nsecs);
834}
835EXPORT_SYMBOL_GPL(ktime_get);
836
837u32 ktime_get_resolution_ns(void)
838{
839 struct timekeeper *tk = &tk_core.timekeeper;
840 unsigned int seq;
841 u32 nsecs;
842
843 WARN_ON(timekeeping_suspended);
844
845 do {
846 seq = read_seqcount_begin(&tk_core.seq);
847 nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
848 } while (read_seqcount_retry(&tk_core.seq, seq));
849
850 return nsecs;
851}
852EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
853
854static ktime_t *offsets[TK_OFFS_MAX] = {
855 [TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
856 [TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
857 [TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai,
858};
859
860ktime_t ktime_get_with_offset(enum tk_offsets offs)
861{
862 struct timekeeper *tk = &tk_core.timekeeper;
863 unsigned int seq;
864 ktime_t base, *offset = offsets[offs];
865 u64 nsecs;
866
867 WARN_ON(timekeeping_suspended);
868
869 do {
870 seq = read_seqcount_begin(&tk_core.seq);
871 base = ktime_add(tk->tkr_mono.base, *offset);
872 nsecs = timekeeping_get_ns(&tk->tkr_mono);
873
874 } while (read_seqcount_retry(&tk_core.seq, seq));
875
876 return ktime_add_ns(base, nsecs);
877
878}
879EXPORT_SYMBOL_GPL(ktime_get_with_offset);
880
881ktime_t ktime_get_coarse_with_offset(enum tk_offsets offs)
882{
883 struct timekeeper *tk = &tk_core.timekeeper;
884 unsigned int seq;
885 ktime_t base, *offset = offsets[offs];
886 u64 nsecs;
887
888 WARN_ON(timekeeping_suspended);
889
890 do {
891 seq = read_seqcount_begin(&tk_core.seq);
892 base = ktime_add(tk->tkr_mono.base, *offset);
893 nsecs = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
894
895 } while (read_seqcount_retry(&tk_core.seq, seq));
896
897 return ktime_add_ns(base, nsecs);
898}
899EXPORT_SYMBOL_GPL(ktime_get_coarse_with_offset);
900
901/**
902 * ktime_mono_to_any() - convert monotonic time to any other time
903 * @tmono: time to convert.
904 * @offs: which offset to use
905 */
906ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
907{
908 ktime_t *offset = offsets[offs];
909 unsigned int seq;
910 ktime_t tconv;
911
912 do {
913 seq = read_seqcount_begin(&tk_core.seq);
914 tconv = ktime_add(tmono, *offset);
915 } while (read_seqcount_retry(&tk_core.seq, seq));
916
917 return tconv;
918}
919EXPORT_SYMBOL_GPL(ktime_mono_to_any);
920
921/**
922 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
923 */
924ktime_t ktime_get_raw(void)
925{
926 struct timekeeper *tk = &tk_core.timekeeper;
927 unsigned int seq;
928 ktime_t base;
929 u64 nsecs;
930
931 do {
932 seq = read_seqcount_begin(&tk_core.seq);
933 base = tk->tkr_raw.base;
934 nsecs = timekeeping_get_ns(&tk->tkr_raw);
935
936 } while (read_seqcount_retry(&tk_core.seq, seq));
937
938 return ktime_add_ns(base, nsecs);
939}
940EXPORT_SYMBOL_GPL(ktime_get_raw);
941
942/**
943 * ktime_get_ts64 - get the monotonic clock in timespec64 format
944 * @ts: pointer to timespec variable
945 *
946 * The function calculates the monotonic clock from the realtime
947 * clock and the wall_to_monotonic offset and stores the result
948 * in normalized timespec64 format in the variable pointed to by @ts.
949 */
950void ktime_get_ts64(struct timespec64 *ts)
951{
952 struct timekeeper *tk = &tk_core.timekeeper;
953 struct timespec64 tomono;
954 unsigned int seq;
955 u64 nsec;
956
957 WARN_ON(timekeeping_suspended);
958
959 do {
960 seq = read_seqcount_begin(&tk_core.seq);
961 ts->tv_sec = tk->xtime_sec;
962 nsec = timekeeping_get_ns(&tk->tkr_mono);
963 tomono = tk->wall_to_monotonic;
964
965 } while (read_seqcount_retry(&tk_core.seq, seq));
966
967 ts->tv_sec += tomono.tv_sec;
968 ts->tv_nsec = 0;
969 timespec64_add_ns(ts, nsec + tomono.tv_nsec);
970}
971EXPORT_SYMBOL_GPL(ktime_get_ts64);
972
973/**
974 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
975 *
976 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
977 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
978 * works on both 32 and 64 bit systems. On 32 bit systems the readout
979 * covers ~136 years of uptime which should be enough to prevent
980 * premature wrap arounds.
981 */
982time64_t ktime_get_seconds(void)
983{
984 struct timekeeper *tk = &tk_core.timekeeper;
985
986 WARN_ON(timekeeping_suspended);
987 return tk->ktime_sec;
988}
989EXPORT_SYMBOL_GPL(ktime_get_seconds);
990
991/**
992 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
993 *
994 * Returns the wall clock seconds since 1970.
995 *
996 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
997 * 32bit systems the access must be protected with the sequence
998 * counter to provide "atomic" access to the 64bit tk->xtime_sec
999 * value.
1000 */
1001time64_t ktime_get_real_seconds(void)
1002{
1003 struct timekeeper *tk = &tk_core.timekeeper;
1004 time64_t seconds;
1005 unsigned int seq;
1006
1007 if (IS_ENABLED(CONFIG_64BIT))
1008 return tk->xtime_sec;
1009
1010 do {
1011 seq = read_seqcount_begin(&tk_core.seq);
1012 seconds = tk->xtime_sec;
1013
1014 } while (read_seqcount_retry(&tk_core.seq, seq));
1015
1016 return seconds;
1017}
1018EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
1019
1020/**
1021 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
1022 * but without the sequence counter protect. This internal function
1023 * is called just when timekeeping lock is already held.
1024 */
1025noinstr time64_t __ktime_get_real_seconds(void)
1026{
1027 struct timekeeper *tk = &tk_core.timekeeper;
1028
1029 return tk->xtime_sec;
1030}
1031
1032/**
1033 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
1034 * @systime_snapshot: pointer to struct receiving the system time snapshot
1035 */
1036void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
1037{
1038 struct timekeeper *tk = &tk_core.timekeeper;
1039 unsigned int seq;
1040 ktime_t base_raw;
1041 ktime_t base_real;
1042 u64 nsec_raw;
1043 u64 nsec_real;
1044 u64 now;
1045
1046 WARN_ON_ONCE(timekeeping_suspended);
1047
1048 do {
1049 seq = read_seqcount_begin(&tk_core.seq);
1050 now = tk_clock_read(&tk->tkr_mono);
1051 systime_snapshot->cs_id = tk->tkr_mono.clock->id;
1052 systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
1053 systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
1054 base_real = ktime_add(tk->tkr_mono.base,
1055 tk_core.timekeeper.offs_real);
1056 base_raw = tk->tkr_raw.base;
1057 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
1058 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
1059 } while (read_seqcount_retry(&tk_core.seq, seq));
1060
1061 systime_snapshot->cycles = now;
1062 systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
1063 systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
1064}
1065EXPORT_SYMBOL_GPL(ktime_get_snapshot);
1066
1067/* Scale base by mult/div checking for overflow */
1068static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
1069{
1070 u64 tmp, rem;
1071
1072 tmp = div64_u64_rem(*base, div, &rem);
1073
1074 if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
1075 ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
1076 return -EOVERFLOW;
1077 tmp *= mult;
1078
1079 rem = div64_u64(rem * mult, div);
1080 *base = tmp + rem;
1081 return 0;
1082}
1083
1084/**
1085 * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
1086 * @history: Snapshot representing start of history
1087 * @partial_history_cycles: Cycle offset into history (fractional part)
1088 * @total_history_cycles: Total history length in cycles
1089 * @discontinuity: True indicates clock was set on history period
1090 * @ts: Cross timestamp that should be adjusted using
1091 * partial/total ratio
1092 *
1093 * Helper function used by get_device_system_crosststamp() to correct the
1094 * crosstimestamp corresponding to the start of the current interval to the
1095 * system counter value (timestamp point) provided by the driver. The
1096 * total_history_* quantities are the total history starting at the provided
1097 * reference point and ending at the start of the current interval. The cycle
1098 * count between the driver timestamp point and the start of the current
1099 * interval is partial_history_cycles.
1100 */
1101static int adjust_historical_crosststamp(struct system_time_snapshot *history,
1102 u64 partial_history_cycles,
1103 u64 total_history_cycles,
1104 bool discontinuity,
1105 struct system_device_crosststamp *ts)
1106{
1107 struct timekeeper *tk = &tk_core.timekeeper;
1108 u64 corr_raw, corr_real;
1109 bool interp_forward;
1110 int ret;
1111
1112 if (total_history_cycles == 0 || partial_history_cycles == 0)
1113 return 0;
1114
1115 /* Interpolate shortest distance from beginning or end of history */
1116 interp_forward = partial_history_cycles > total_history_cycles / 2;
1117 partial_history_cycles = interp_forward ?
1118 total_history_cycles - partial_history_cycles :
1119 partial_history_cycles;
1120
1121 /*
1122 * Scale the monotonic raw time delta by:
1123 * partial_history_cycles / total_history_cycles
1124 */
1125 corr_raw = (u64)ktime_to_ns(
1126 ktime_sub(ts->sys_monoraw, history->raw));
1127 ret = scale64_check_overflow(partial_history_cycles,
1128 total_history_cycles, &corr_raw);
1129 if (ret)
1130 return ret;
1131
1132 /*
1133 * If there is a discontinuity in the history, scale monotonic raw
1134 * correction by:
1135 * mult(real)/mult(raw) yielding the realtime correction
1136 * Otherwise, calculate the realtime correction similar to monotonic
1137 * raw calculation
1138 */
1139 if (discontinuity) {
1140 corr_real = mul_u64_u32_div
1141 (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1142 } else {
1143 corr_real = (u64)ktime_to_ns(
1144 ktime_sub(ts->sys_realtime, history->real));
1145 ret = scale64_check_overflow(partial_history_cycles,
1146 total_history_cycles, &corr_real);
1147 if (ret)
1148 return ret;
1149 }
1150
1151 /* Fixup monotonic raw and real time time values */
1152 if (interp_forward) {
1153 ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1154 ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1155 } else {
1156 ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1157 ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1158 }
1159
1160 return 0;
1161}
1162
1163/*
1164 * cycle_between - true if test occurs chronologically between before and after
1165 */
1166static bool cycle_between(u64 before, u64 test, u64 after)
1167{
1168 if (test > before && test < after)
1169 return true;
1170 if (test < before && before > after)
1171 return true;
1172 return false;
1173}
1174
1175/**
1176 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1177 * @get_time_fn: Callback to get simultaneous device time and
1178 * system counter from the device driver
1179 * @ctx: Context passed to get_time_fn()
1180 * @history_begin: Historical reference point used to interpolate system
1181 * time when counter provided by the driver is before the current interval
1182 * @xtstamp: Receives simultaneously captured system and device time
1183 *
1184 * Reads a timestamp from a device and correlates it to system time
1185 */
1186int get_device_system_crosststamp(int (*get_time_fn)
1187 (ktime_t *device_time,
1188 struct system_counterval_t *sys_counterval,
1189 void *ctx),
1190 void *ctx,
1191 struct system_time_snapshot *history_begin,
1192 struct system_device_crosststamp *xtstamp)
1193{
1194 struct system_counterval_t system_counterval;
1195 struct timekeeper *tk = &tk_core.timekeeper;
1196 u64 cycles, now, interval_start;
1197 unsigned int clock_was_set_seq = 0;
1198 ktime_t base_real, base_raw;
1199 u64 nsec_real, nsec_raw;
1200 u8 cs_was_changed_seq;
1201 unsigned int seq;
1202 bool do_interp;
1203 int ret;
1204
1205 do {
1206 seq = read_seqcount_begin(&tk_core.seq);
1207 /*
1208 * Try to synchronously capture device time and a system
1209 * counter value calling back into the device driver
1210 */
1211 ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1212 if (ret)
1213 return ret;
1214
1215 /*
1216 * Verify that the clocksource associated with the captured
1217 * system counter value is the same as the currently installed
1218 * timekeeper clocksource
1219 */
1220 if (tk->tkr_mono.clock != system_counterval.cs)
1221 return -ENODEV;
1222 cycles = system_counterval.cycles;
1223
1224 /*
1225 * Check whether the system counter value provided by the
1226 * device driver is on the current timekeeping interval.
1227 */
1228 now = tk_clock_read(&tk->tkr_mono);
1229 interval_start = tk->tkr_mono.cycle_last;
1230 if (!cycle_between(interval_start, cycles, now)) {
1231 clock_was_set_seq = tk->clock_was_set_seq;
1232 cs_was_changed_seq = tk->cs_was_changed_seq;
1233 cycles = interval_start;
1234 do_interp = true;
1235 } else {
1236 do_interp = false;
1237 }
1238
1239 base_real = ktime_add(tk->tkr_mono.base,
1240 tk_core.timekeeper.offs_real);
1241 base_raw = tk->tkr_raw.base;
1242
1243 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1244 system_counterval.cycles);
1245 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1246 system_counterval.cycles);
1247 } while (read_seqcount_retry(&tk_core.seq, seq));
1248
1249 xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1250 xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1251
1252 /*
1253 * Interpolate if necessary, adjusting back from the start of the
1254 * current interval
1255 */
1256 if (do_interp) {
1257 u64 partial_history_cycles, total_history_cycles;
1258 bool discontinuity;
1259
1260 /*
1261 * Check that the counter value occurs after the provided
1262 * history reference and that the history doesn't cross a
1263 * clocksource change
1264 */
1265 if (!history_begin ||
1266 !cycle_between(history_begin->cycles,
1267 system_counterval.cycles, cycles) ||
1268 history_begin->cs_was_changed_seq != cs_was_changed_seq)
1269 return -EINVAL;
1270 partial_history_cycles = cycles - system_counterval.cycles;
1271 total_history_cycles = cycles - history_begin->cycles;
1272 discontinuity =
1273 history_begin->clock_was_set_seq != clock_was_set_seq;
1274
1275 ret = adjust_historical_crosststamp(history_begin,
1276 partial_history_cycles,
1277 total_history_cycles,
1278 discontinuity, xtstamp);
1279 if (ret)
1280 return ret;
1281 }
1282
1283 return 0;
1284}
1285EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1286
1287/**
1288 * do_settimeofday64 - Sets the time of day.
1289 * @ts: pointer to the timespec64 variable containing the new time
1290 *
1291 * Sets the time of day to the new time and update NTP and notify hrtimers
1292 */
1293int do_settimeofday64(const struct timespec64 *ts)
1294{
1295 struct timekeeper *tk = &tk_core.timekeeper;
1296 struct timespec64 ts_delta, xt;
1297 unsigned long flags;
1298 int ret = 0;
1299
1300 if (!timespec64_valid_settod(ts))
1301 return -EINVAL;
1302
1303 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1304 write_seqcount_begin(&tk_core.seq);
1305
1306 timekeeping_forward_now(tk);
1307
1308 xt = tk_xtime(tk);
1309 ts_delta.tv_sec = ts->tv_sec - xt.tv_sec;
1310 ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec;
1311
1312 if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1313 ret = -EINVAL;
1314 goto out;
1315 }
1316
1317 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1318
1319 tk_set_xtime(tk, ts);
1320out:
1321 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1322
1323 write_seqcount_end(&tk_core.seq);
1324 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1325
1326 /* signal hrtimers about time change */
1327 clock_was_set();
1328
1329 if (!ret)
1330 audit_tk_injoffset(ts_delta);
1331
1332 return ret;
1333}
1334EXPORT_SYMBOL(do_settimeofday64);
1335
1336/**
1337 * timekeeping_inject_offset - Adds or subtracts from the current time.
1338 * @ts: Pointer to the timespec variable containing the offset
1339 *
1340 * Adds or subtracts an offset value from the current time.
1341 */
1342static int timekeeping_inject_offset(const struct timespec64 *ts)
1343{
1344 struct timekeeper *tk = &tk_core.timekeeper;
1345 unsigned long flags;
1346 struct timespec64 tmp;
1347 int ret = 0;
1348
1349 if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
1350 return -EINVAL;
1351
1352 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1353 write_seqcount_begin(&tk_core.seq);
1354
1355 timekeeping_forward_now(tk);
1356
1357 /* Make sure the proposed value is valid */
1358 tmp = timespec64_add(tk_xtime(tk), *ts);
1359 if (timespec64_compare(&tk->wall_to_monotonic, ts) > 0 ||
1360 !timespec64_valid_settod(&tmp)) {
1361 ret = -EINVAL;
1362 goto error;
1363 }
1364
1365 tk_xtime_add(tk, ts);
1366 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *ts));
1367
1368error: /* even if we error out, we forwarded the time, so call update */
1369 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1370
1371 write_seqcount_end(&tk_core.seq);
1372 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1373
1374 /* signal hrtimers about time change */
1375 clock_was_set();
1376
1377 return ret;
1378}
1379
1380/*
1381 * Indicates if there is an offset between the system clock and the hardware
1382 * clock/persistent clock/rtc.
1383 */
1384int persistent_clock_is_local;
1385
1386/*
1387 * Adjust the time obtained from the CMOS to be UTC time instead of
1388 * local time.
1389 *
1390 * This is ugly, but preferable to the alternatives. Otherwise we
1391 * would either need to write a program to do it in /etc/rc (and risk
1392 * confusion if the program gets run more than once; it would also be
1393 * hard to make the program warp the clock precisely n hours) or
1394 * compile in the timezone information into the kernel. Bad, bad....
1395 *
1396 * - TYT, 1992-01-01
1397 *
1398 * The best thing to do is to keep the CMOS clock in universal time (UTC)
1399 * as real UNIX machines always do it. This avoids all headaches about
1400 * daylight saving times and warping kernel clocks.
1401 */
1402void timekeeping_warp_clock(void)
1403{
1404 if (sys_tz.tz_minuteswest != 0) {
1405 struct timespec64 adjust;
1406
1407 persistent_clock_is_local = 1;
1408 adjust.tv_sec = sys_tz.tz_minuteswest * 60;
1409 adjust.tv_nsec = 0;
1410 timekeeping_inject_offset(&adjust);
1411 }
1412}
1413
1414/*
1415 * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1416 */
1417static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1418{
1419 tk->tai_offset = tai_offset;
1420 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1421}
1422
1423/*
1424 * change_clocksource - Swaps clocksources if a new one is available
1425 *
1426 * Accumulates current time interval and initializes new clocksource
1427 */
1428static int change_clocksource(void *data)
1429{
1430 struct timekeeper *tk = &tk_core.timekeeper;
1431 struct clocksource *new, *old = NULL;
1432 unsigned long flags;
1433 bool change = false;
1434
1435 new = (struct clocksource *) data;
1436
1437 /*
1438 * If the cs is in module, get a module reference. Succeeds
1439 * for built-in code (owner == NULL) as well.
1440 */
1441 if (try_module_get(new->owner)) {
1442 if (!new->enable || new->enable(new) == 0)
1443 change = true;
1444 else
1445 module_put(new->owner);
1446 }
1447
1448 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1449 write_seqcount_begin(&tk_core.seq);
1450
1451 timekeeping_forward_now(tk);
1452
1453 if (change) {
1454 old = tk->tkr_mono.clock;
1455 tk_setup_internals(tk, new);
1456 }
1457
1458 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1459
1460 write_seqcount_end(&tk_core.seq);
1461 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1462
1463 if (old) {
1464 if (old->disable)
1465 old->disable(old);
1466
1467 module_put(old->owner);
1468 }
1469
1470 return 0;
1471}
1472
1473/**
1474 * timekeeping_notify - Install a new clock source
1475 * @clock: pointer to the clock source
1476 *
1477 * This function is called from clocksource.c after a new, better clock
1478 * source has been registered. The caller holds the clocksource_mutex.
1479 */
1480int timekeeping_notify(struct clocksource *clock)
1481{
1482 struct timekeeper *tk = &tk_core.timekeeper;
1483
1484 if (tk->tkr_mono.clock == clock)
1485 return 0;
1486 stop_machine(change_clocksource, clock, NULL);
1487 tick_clock_notify();
1488 return tk->tkr_mono.clock == clock ? 0 : -1;
1489}
1490
1491/**
1492 * ktime_get_raw_ts64 - Returns the raw monotonic time in a timespec
1493 * @ts: pointer to the timespec64 to be set
1494 *
1495 * Returns the raw monotonic time (completely un-modified by ntp)
1496 */
1497void ktime_get_raw_ts64(struct timespec64 *ts)
1498{
1499 struct timekeeper *tk = &tk_core.timekeeper;
1500 unsigned int seq;
1501 u64 nsecs;
1502
1503 do {
1504 seq = read_seqcount_begin(&tk_core.seq);
1505 ts->tv_sec = tk->raw_sec;
1506 nsecs = timekeeping_get_ns(&tk->tkr_raw);
1507
1508 } while (read_seqcount_retry(&tk_core.seq, seq));
1509
1510 ts->tv_nsec = 0;
1511 timespec64_add_ns(ts, nsecs);
1512}
1513EXPORT_SYMBOL(ktime_get_raw_ts64);
1514
1515
1516/**
1517 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1518 */
1519int timekeeping_valid_for_hres(void)
1520{
1521 struct timekeeper *tk = &tk_core.timekeeper;
1522 unsigned int seq;
1523 int ret;
1524
1525 do {
1526 seq = read_seqcount_begin(&tk_core.seq);
1527
1528 ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1529
1530 } while (read_seqcount_retry(&tk_core.seq, seq));
1531
1532 return ret;
1533}
1534
1535/**
1536 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1537 */
1538u64 timekeeping_max_deferment(void)
1539{
1540 struct timekeeper *tk = &tk_core.timekeeper;
1541 unsigned int seq;
1542 u64 ret;
1543
1544 do {
1545 seq = read_seqcount_begin(&tk_core.seq);
1546
1547 ret = tk->tkr_mono.clock->max_idle_ns;
1548
1549 } while (read_seqcount_retry(&tk_core.seq, seq));
1550
1551 return ret;
1552}
1553
1554/**
1555 * read_persistent_clock64 - Return time from the persistent clock.
1556 * @ts: Pointer to the storage for the readout value
1557 *
1558 * Weak dummy function for arches that do not yet support it.
1559 * Reads the time from the battery backed persistent clock.
1560 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1561 *
1562 * XXX - Do be sure to remove it once all arches implement it.
1563 */
1564void __weak read_persistent_clock64(struct timespec64 *ts)
1565{
1566 ts->tv_sec = 0;
1567 ts->tv_nsec = 0;
1568}
1569
1570/**
1571 * read_persistent_wall_and_boot_offset - Read persistent clock, and also offset
1572 * from the boot.
1573 *
1574 * Weak dummy function for arches that do not yet support it.
1575 * @wall_time: - current time as returned by persistent clock
1576 * @boot_offset: - offset that is defined as wall_time - boot_time
1577 *
1578 * The default function calculates offset based on the current value of
1579 * local_clock(). This way architectures that support sched_clock() but don't
1580 * support dedicated boot time clock will provide the best estimate of the
1581 * boot time.
1582 */
1583void __weak __init
1584read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
1585 struct timespec64 *boot_offset)
1586{
1587 read_persistent_clock64(wall_time);
1588 *boot_offset = ns_to_timespec64(local_clock());
1589}
1590
1591/*
1592 * Flag reflecting whether timekeeping_resume() has injected sleeptime.
1593 *
1594 * The flag starts of false and is only set when a suspend reaches
1595 * timekeeping_suspend(), timekeeping_resume() sets it to false when the
1596 * timekeeper clocksource is not stopping across suspend and has been
1597 * used to update sleep time. If the timekeeper clocksource has stopped
1598 * then the flag stays true and is used by the RTC resume code to decide
1599 * whether sleeptime must be injected and if so the flag gets false then.
1600 *
1601 * If a suspend fails before reaching timekeeping_resume() then the flag
1602 * stays false and prevents erroneous sleeptime injection.
1603 */
1604static bool suspend_timing_needed;
1605
1606/* Flag for if there is a persistent clock on this platform */
1607static bool persistent_clock_exists;
1608
1609/*
1610 * timekeeping_init - Initializes the clocksource and common timekeeping values
1611 */
1612void __init timekeeping_init(void)
1613{
1614 struct timespec64 wall_time, boot_offset, wall_to_mono;
1615 struct timekeeper *tk = &tk_core.timekeeper;
1616 struct clocksource *clock;
1617 unsigned long flags;
1618
1619 read_persistent_wall_and_boot_offset(&wall_time, &boot_offset);
1620 if (timespec64_valid_settod(&wall_time) &&
1621 timespec64_to_ns(&wall_time) > 0) {
1622 persistent_clock_exists = true;
1623 } else if (timespec64_to_ns(&wall_time) != 0) {
1624 pr_warn("Persistent clock returned invalid value");
1625 wall_time = (struct timespec64){0};
1626 }
1627
1628 if (timespec64_compare(&wall_time, &boot_offset) < 0)
1629 boot_offset = (struct timespec64){0};
1630
1631 /*
1632 * We want set wall_to_mono, so the following is true:
1633 * wall time + wall_to_mono = boot time
1634 */
1635 wall_to_mono = timespec64_sub(boot_offset, wall_time);
1636
1637 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1638 write_seqcount_begin(&tk_core.seq);
1639 ntp_init();
1640
1641 clock = clocksource_default_clock();
1642 if (clock->enable)
1643 clock->enable(clock);
1644 tk_setup_internals(tk, clock);
1645
1646 tk_set_xtime(tk, &wall_time);
1647 tk->raw_sec = 0;
1648
1649 tk_set_wall_to_mono(tk, wall_to_mono);
1650
1651 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1652
1653 write_seqcount_end(&tk_core.seq);
1654 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1655}
1656
1657/* time in seconds when suspend began for persistent clock */
1658static struct timespec64 timekeeping_suspend_time;
1659
1660/**
1661 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1662 * @tk: Pointer to the timekeeper to be updated
1663 * @delta: Pointer to the delta value in timespec64 format
1664 *
1665 * Takes a timespec offset measuring a suspend interval and properly
1666 * adds the sleep offset to the timekeeping variables.
1667 */
1668static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1669 const struct timespec64 *delta)
1670{
1671 if (!timespec64_valid_strict(delta)) {
1672 printk_deferred(KERN_WARNING
1673 "__timekeeping_inject_sleeptime: Invalid "
1674 "sleep delta value!\n");
1675 return;
1676 }
1677 tk_xtime_add(tk, delta);
1678 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1679 tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1680 tk_debug_account_sleep_time(delta);
1681}
1682
1683#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1684/**
1685 * We have three kinds of time sources to use for sleep time
1686 * injection, the preference order is:
1687 * 1) non-stop clocksource
1688 * 2) persistent clock (ie: RTC accessible when irqs are off)
1689 * 3) RTC
1690 *
1691 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1692 * If system has neither 1) nor 2), 3) will be used finally.
1693 *
1694 *
1695 * If timekeeping has injected sleeptime via either 1) or 2),
1696 * 3) becomes needless, so in this case we don't need to call
1697 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1698 * means.
1699 */
1700bool timekeeping_rtc_skipresume(void)
1701{
1702 return !suspend_timing_needed;
1703}
1704
1705/**
1706 * 1) can be determined whether to use or not only when doing
1707 * timekeeping_resume() which is invoked after rtc_suspend(),
1708 * so we can't skip rtc_suspend() surely if system has 1).
1709 *
1710 * But if system has 2), 2) will definitely be used, so in this
1711 * case we don't need to call rtc_suspend(), and this is what
1712 * timekeeping_rtc_skipsuspend() means.
1713 */
1714bool timekeeping_rtc_skipsuspend(void)
1715{
1716 return persistent_clock_exists;
1717}
1718
1719/**
1720 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1721 * @delta: pointer to a timespec64 delta value
1722 *
1723 * This hook is for architectures that cannot support read_persistent_clock64
1724 * because their RTC/persistent clock is only accessible when irqs are enabled.
1725 * and also don't have an effective nonstop clocksource.
1726 *
1727 * This function should only be called by rtc_resume(), and allows
1728 * a suspend offset to be injected into the timekeeping values.
1729 */
1730void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
1731{
1732 struct timekeeper *tk = &tk_core.timekeeper;
1733 unsigned long flags;
1734
1735 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1736 write_seqcount_begin(&tk_core.seq);
1737
1738 suspend_timing_needed = false;
1739
1740 timekeeping_forward_now(tk);
1741
1742 __timekeeping_inject_sleeptime(tk, delta);
1743
1744 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1745
1746 write_seqcount_end(&tk_core.seq);
1747 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1748
1749 /* signal hrtimers about time change */
1750 clock_was_set();
1751}
1752#endif
1753
1754/**
1755 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1756 */
1757void timekeeping_resume(void)
1758{
1759 struct timekeeper *tk = &tk_core.timekeeper;
1760 struct clocksource *clock = tk->tkr_mono.clock;
1761 unsigned long flags;
1762 struct timespec64 ts_new, ts_delta;
1763 u64 cycle_now, nsec;
1764 bool inject_sleeptime = false;
1765
1766 read_persistent_clock64(&ts_new);
1767
1768 clockevents_resume();
1769 clocksource_resume();
1770
1771 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1772 write_seqcount_begin(&tk_core.seq);
1773
1774 /*
1775 * After system resumes, we need to calculate the suspended time and
1776 * compensate it for the OS time. There are 3 sources that could be
1777 * used: Nonstop clocksource during suspend, persistent clock and rtc
1778 * device.
1779 *
1780 * One specific platform may have 1 or 2 or all of them, and the
1781 * preference will be:
1782 * suspend-nonstop clocksource -> persistent clock -> rtc
1783 * The less preferred source will only be tried if there is no better
1784 * usable source. The rtc part is handled separately in rtc core code.
1785 */
1786 cycle_now = tk_clock_read(&tk->tkr_mono);
1787 nsec = clocksource_stop_suspend_timing(clock, cycle_now);
1788 if (nsec > 0) {
1789 ts_delta = ns_to_timespec64(nsec);
1790 inject_sleeptime = true;
1791 } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1792 ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1793 inject_sleeptime = true;
1794 }
1795
1796 if (inject_sleeptime) {
1797 suspend_timing_needed = false;
1798 __timekeeping_inject_sleeptime(tk, &ts_delta);
1799 }
1800
1801 /* Re-base the last cycle value */
1802 tk->tkr_mono.cycle_last = cycle_now;
1803 tk->tkr_raw.cycle_last = cycle_now;
1804
1805 tk->ntp_error = 0;
1806 timekeeping_suspended = 0;
1807 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1808 write_seqcount_end(&tk_core.seq);
1809 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1810
1811 touch_softlockup_watchdog();
1812
1813 tick_resume();
1814 hrtimers_resume();
1815}
1816
1817int timekeeping_suspend(void)
1818{
1819 struct timekeeper *tk = &tk_core.timekeeper;
1820 unsigned long flags;
1821 struct timespec64 delta, delta_delta;
1822 static struct timespec64 old_delta;
1823 struct clocksource *curr_clock;
1824 u64 cycle_now;
1825
1826 read_persistent_clock64(&timekeeping_suspend_time);
1827
1828 /*
1829 * On some systems the persistent_clock can not be detected at
1830 * timekeeping_init by its return value, so if we see a valid
1831 * value returned, update the persistent_clock_exists flag.
1832 */
1833 if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1834 persistent_clock_exists = true;
1835
1836 suspend_timing_needed = true;
1837
1838 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1839 write_seqcount_begin(&tk_core.seq);
1840 timekeeping_forward_now(tk);
1841 timekeeping_suspended = 1;
1842
1843 /*
1844 * Since we've called forward_now, cycle_last stores the value
1845 * just read from the current clocksource. Save this to potentially
1846 * use in suspend timing.
1847 */
1848 curr_clock = tk->tkr_mono.clock;
1849 cycle_now = tk->tkr_mono.cycle_last;
1850 clocksource_start_suspend_timing(curr_clock, cycle_now);
1851
1852 if (persistent_clock_exists) {
1853 /*
1854 * To avoid drift caused by repeated suspend/resumes,
1855 * which each can add ~1 second drift error,
1856 * try to compensate so the difference in system time
1857 * and persistent_clock time stays close to constant.
1858 */
1859 delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1860 delta_delta = timespec64_sub(delta, old_delta);
1861 if (abs(delta_delta.tv_sec) >= 2) {
1862 /*
1863 * if delta_delta is too large, assume time correction
1864 * has occurred and set old_delta to the current delta.
1865 */
1866 old_delta = delta;
1867 } else {
1868 /* Otherwise try to adjust old_system to compensate */
1869 timekeeping_suspend_time =
1870 timespec64_add(timekeeping_suspend_time, delta_delta);
1871 }
1872 }
1873
1874 timekeeping_update(tk, TK_MIRROR);
1875 halt_fast_timekeeper(tk);
1876 write_seqcount_end(&tk_core.seq);
1877 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1878
1879 tick_suspend();
1880 clocksource_suspend();
1881 clockevents_suspend();
1882
1883 return 0;
1884}
1885
1886/* sysfs resume/suspend bits for timekeeping */
1887static struct syscore_ops timekeeping_syscore_ops = {
1888 .resume = timekeeping_resume,
1889 .suspend = timekeeping_suspend,
1890};
1891
1892static int __init timekeeping_init_ops(void)
1893{
1894 register_syscore_ops(&timekeeping_syscore_ops);
1895 return 0;
1896}
1897device_initcall(timekeeping_init_ops);
1898
1899/*
1900 * Apply a multiplier adjustment to the timekeeper
1901 */
1902static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1903 s64 offset,
1904 s32 mult_adj)
1905{
1906 s64 interval = tk->cycle_interval;
1907
1908 if (mult_adj == 0) {
1909 return;
1910 } else if (mult_adj == -1) {
1911 interval = -interval;
1912 offset = -offset;
1913 } else if (mult_adj != 1) {
1914 interval *= mult_adj;
1915 offset *= mult_adj;
1916 }
1917
1918 /*
1919 * So the following can be confusing.
1920 *
1921 * To keep things simple, lets assume mult_adj == 1 for now.
1922 *
1923 * When mult_adj != 1, remember that the interval and offset values
1924 * have been appropriately scaled so the math is the same.
1925 *
1926 * The basic idea here is that we're increasing the multiplier
1927 * by one, this causes the xtime_interval to be incremented by
1928 * one cycle_interval. This is because:
1929 * xtime_interval = cycle_interval * mult
1930 * So if mult is being incremented by one:
1931 * xtime_interval = cycle_interval * (mult + 1)
1932 * Its the same as:
1933 * xtime_interval = (cycle_interval * mult) + cycle_interval
1934 * Which can be shortened to:
1935 * xtime_interval += cycle_interval
1936 *
1937 * So offset stores the non-accumulated cycles. Thus the current
1938 * time (in shifted nanoseconds) is:
1939 * now = (offset * adj) + xtime_nsec
1940 * Now, even though we're adjusting the clock frequency, we have
1941 * to keep time consistent. In other words, we can't jump back
1942 * in time, and we also want to avoid jumping forward in time.
1943 *
1944 * So given the same offset value, we need the time to be the same
1945 * both before and after the freq adjustment.
1946 * now = (offset * adj_1) + xtime_nsec_1
1947 * now = (offset * adj_2) + xtime_nsec_2
1948 * So:
1949 * (offset * adj_1) + xtime_nsec_1 =
1950 * (offset * adj_2) + xtime_nsec_2
1951 * And we know:
1952 * adj_2 = adj_1 + 1
1953 * So:
1954 * (offset * adj_1) + xtime_nsec_1 =
1955 * (offset * (adj_1+1)) + xtime_nsec_2
1956 * (offset * adj_1) + xtime_nsec_1 =
1957 * (offset * adj_1) + offset + xtime_nsec_2
1958 * Canceling the sides:
1959 * xtime_nsec_1 = offset + xtime_nsec_2
1960 * Which gives us:
1961 * xtime_nsec_2 = xtime_nsec_1 - offset
1962 * Which simplifies to:
1963 * xtime_nsec -= offset
1964 */
1965 if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1966 /* NTP adjustment caused clocksource mult overflow */
1967 WARN_ON_ONCE(1);
1968 return;
1969 }
1970
1971 tk->tkr_mono.mult += mult_adj;
1972 tk->xtime_interval += interval;
1973 tk->tkr_mono.xtime_nsec -= offset;
1974}
1975
1976/*
1977 * Adjust the timekeeper's multiplier to the correct frequency
1978 * and also to reduce the accumulated error value.
1979 */
1980static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1981{
1982 u32 mult;
1983
1984 /*
1985 * Determine the multiplier from the current NTP tick length.
1986 * Avoid expensive division when the tick length doesn't change.
1987 */
1988 if (likely(tk->ntp_tick == ntp_tick_length())) {
1989 mult = tk->tkr_mono.mult - tk->ntp_err_mult;
1990 } else {
1991 tk->ntp_tick = ntp_tick_length();
1992 mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) -
1993 tk->xtime_remainder, tk->cycle_interval);
1994 }
1995
1996 /*
1997 * If the clock is behind the NTP time, increase the multiplier by 1
1998 * to catch up with it. If it's ahead and there was a remainder in the
1999 * tick division, the clock will slow down. Otherwise it will stay
2000 * ahead until the tick length changes to a non-divisible value.
2001 */
2002 tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0;
2003 mult += tk->ntp_err_mult;
2004
2005 timekeeping_apply_adjustment(tk, offset, mult - tk->tkr_mono.mult);
2006
2007 if (unlikely(tk->tkr_mono.clock->maxadj &&
2008 (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
2009 > tk->tkr_mono.clock->maxadj))) {
2010 printk_once(KERN_WARNING
2011 "Adjusting %s more than 11%% (%ld vs %ld)\n",
2012 tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
2013 (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
2014 }
2015
2016 /*
2017 * It may be possible that when we entered this function, xtime_nsec
2018 * was very small. Further, if we're slightly speeding the clocksource
2019 * in the code above, its possible the required corrective factor to
2020 * xtime_nsec could cause it to underflow.
2021 *
2022 * Now, since we have already accumulated the second and the NTP
2023 * subsystem has been notified via second_overflow(), we need to skip
2024 * the next update.
2025 */
2026 if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
2027 tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC <<
2028 tk->tkr_mono.shift;
2029 tk->xtime_sec--;
2030 tk->skip_second_overflow = 1;
2031 }
2032}
2033
2034/*
2035 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
2036 *
2037 * Helper function that accumulates the nsecs greater than a second
2038 * from the xtime_nsec field to the xtime_secs field.
2039 * It also calls into the NTP code to handle leapsecond processing.
2040 */
2041static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
2042{
2043 u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
2044 unsigned int clock_set = 0;
2045
2046 while (tk->tkr_mono.xtime_nsec >= nsecps) {
2047 int leap;
2048
2049 tk->tkr_mono.xtime_nsec -= nsecps;
2050 tk->xtime_sec++;
2051
2052 /*
2053 * Skip NTP update if this second was accumulated before,
2054 * i.e. xtime_nsec underflowed in timekeeping_adjust()
2055 */
2056 if (unlikely(tk->skip_second_overflow)) {
2057 tk->skip_second_overflow = 0;
2058 continue;
2059 }
2060
2061 /* Figure out if its a leap sec and apply if needed */
2062 leap = second_overflow(tk->xtime_sec);
2063 if (unlikely(leap)) {
2064 struct timespec64 ts;
2065
2066 tk->xtime_sec += leap;
2067
2068 ts.tv_sec = leap;
2069 ts.tv_nsec = 0;
2070 tk_set_wall_to_mono(tk,
2071 timespec64_sub(tk->wall_to_monotonic, ts));
2072
2073 __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
2074
2075 clock_set = TK_CLOCK_WAS_SET;
2076 }
2077 }
2078 return clock_set;
2079}
2080
2081/*
2082 * logarithmic_accumulation - shifted accumulation of cycles
2083 *
2084 * This functions accumulates a shifted interval of cycles into
2085 * a shifted interval nanoseconds. Allows for O(log) accumulation
2086 * loop.
2087 *
2088 * Returns the unconsumed cycles.
2089 */
2090static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2091 u32 shift, unsigned int *clock_set)
2092{
2093 u64 interval = tk->cycle_interval << shift;
2094 u64 snsec_per_sec;
2095
2096 /* If the offset is smaller than a shifted interval, do nothing */
2097 if (offset < interval)
2098 return offset;
2099
2100 /* Accumulate one shifted interval */
2101 offset -= interval;
2102 tk->tkr_mono.cycle_last += interval;
2103 tk->tkr_raw.cycle_last += interval;
2104
2105 tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2106 *clock_set |= accumulate_nsecs_to_secs(tk);
2107
2108 /* Accumulate raw time */
2109 tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2110 snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2111 while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2112 tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2113 tk->raw_sec++;
2114 }
2115
2116 /* Accumulate error between NTP and clock interval */
2117 tk->ntp_error += tk->ntp_tick << shift;
2118 tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2119 (tk->ntp_error_shift + shift);
2120
2121 return offset;
2122}
2123
2124/*
2125 * timekeeping_advance - Updates the timekeeper to the current time and
2126 * current NTP tick length
2127 */
2128static void timekeeping_advance(enum timekeeping_adv_mode mode)
2129{
2130 struct timekeeper *real_tk = &tk_core.timekeeper;
2131 struct timekeeper *tk = &shadow_timekeeper;
2132 u64 offset;
2133 int shift = 0, maxshift;
2134 unsigned int clock_set = 0;
2135 unsigned long flags;
2136
2137 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2138
2139 /* Make sure we're fully resumed: */
2140 if (unlikely(timekeeping_suspended))
2141 goto out;
2142
2143 offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
2144 tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2145
2146 /* Check if there's really nothing to do */
2147 if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK)
2148 goto out;
2149
2150 /* Do some additional sanity checking */
2151 timekeeping_check_update(tk, offset);
2152
2153 /*
2154 * With NO_HZ we may have to accumulate many cycle_intervals
2155 * (think "ticks") worth of time at once. To do this efficiently,
2156 * we calculate the largest doubling multiple of cycle_intervals
2157 * that is smaller than the offset. We then accumulate that
2158 * chunk in one go, and then try to consume the next smaller
2159 * doubled multiple.
2160 */
2161 shift = ilog2(offset) - ilog2(tk->cycle_interval);
2162 shift = max(0, shift);
2163 /* Bound shift to one less than what overflows tick_length */
2164 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2165 shift = min(shift, maxshift);
2166 while (offset >= tk->cycle_interval) {
2167 offset = logarithmic_accumulation(tk, offset, shift,
2168 &clock_set);
2169 if (offset < tk->cycle_interval<<shift)
2170 shift--;
2171 }
2172
2173 /* Adjust the multiplier to correct NTP error */
2174 timekeeping_adjust(tk, offset);
2175
2176 /*
2177 * Finally, make sure that after the rounding
2178 * xtime_nsec isn't larger than NSEC_PER_SEC
2179 */
2180 clock_set |= accumulate_nsecs_to_secs(tk);
2181
2182 write_seqcount_begin(&tk_core.seq);
2183 /*
2184 * Update the real timekeeper.
2185 *
2186 * We could avoid this memcpy by switching pointers, but that
2187 * requires changes to all other timekeeper usage sites as
2188 * well, i.e. move the timekeeper pointer getter into the
2189 * spinlocked/seqcount protected sections. And we trade this
2190 * memcpy under the tk_core.seq against one before we start
2191 * updating.
2192 */
2193 timekeeping_update(tk, clock_set);
2194 memcpy(real_tk, tk, sizeof(*tk));
2195 /* The memcpy must come last. Do not put anything here! */
2196 write_seqcount_end(&tk_core.seq);
2197out:
2198 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2199 if (clock_set)
2200 /* Have to call _delayed version, since in irq context*/
2201 clock_was_set_delayed();
2202}
2203
2204/**
2205 * update_wall_time - Uses the current clocksource to increment the wall time
2206 *
2207 */
2208void update_wall_time(void)
2209{
2210 timekeeping_advance(TK_ADV_TICK);
2211}
2212
2213/**
2214 * getboottime64 - Return the real time of system boot.
2215 * @ts: pointer to the timespec64 to be set
2216 *
2217 * Returns the wall-time of boot in a timespec64.
2218 *
2219 * This is based on the wall_to_monotonic offset and the total suspend
2220 * time. Calls to settimeofday will affect the value returned (which
2221 * basically means that however wrong your real time clock is at boot time,
2222 * you get the right time here).
2223 */
2224void getboottime64(struct timespec64 *ts)
2225{
2226 struct timekeeper *tk = &tk_core.timekeeper;
2227 ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2228
2229 *ts = ktime_to_timespec64(t);
2230}
2231EXPORT_SYMBOL_GPL(getboottime64);
2232
2233void ktime_get_coarse_real_ts64(struct timespec64 *ts)
2234{
2235 struct timekeeper *tk = &tk_core.timekeeper;
2236 unsigned int seq;
2237
2238 do {
2239 seq = read_seqcount_begin(&tk_core.seq);
2240
2241 *ts = tk_xtime(tk);
2242 } while (read_seqcount_retry(&tk_core.seq, seq));
2243}
2244EXPORT_SYMBOL(ktime_get_coarse_real_ts64);
2245
2246void ktime_get_coarse_ts64(struct timespec64 *ts)
2247{
2248 struct timekeeper *tk = &tk_core.timekeeper;
2249 struct timespec64 now, mono;
2250 unsigned int seq;
2251
2252 do {
2253 seq = read_seqcount_begin(&tk_core.seq);
2254
2255 now = tk_xtime(tk);
2256 mono = tk->wall_to_monotonic;
2257 } while (read_seqcount_retry(&tk_core.seq, seq));
2258
2259 set_normalized_timespec64(ts, now.tv_sec + mono.tv_sec,
2260 now.tv_nsec + mono.tv_nsec);
2261}
2262EXPORT_SYMBOL(ktime_get_coarse_ts64);
2263
2264/*
2265 * Must hold jiffies_lock
2266 */
2267void do_timer(unsigned long ticks)
2268{
2269 jiffies_64 += ticks;
2270 calc_global_load();
2271}
2272
2273/**
2274 * ktime_get_update_offsets_now - hrtimer helper
2275 * @cwsseq: pointer to check and store the clock was set sequence number
2276 * @offs_real: pointer to storage for monotonic -> realtime offset
2277 * @offs_boot: pointer to storage for monotonic -> boottime offset
2278 * @offs_tai: pointer to storage for monotonic -> clock tai offset
2279 *
2280 * Returns current monotonic time and updates the offsets if the
2281 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2282 * different.
2283 *
2284 * Called from hrtimer_interrupt() or retrigger_next_event()
2285 */
2286ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2287 ktime_t *offs_boot, ktime_t *offs_tai)
2288{
2289 struct timekeeper *tk = &tk_core.timekeeper;
2290 unsigned int seq;
2291 ktime_t base;
2292 u64 nsecs;
2293
2294 do {
2295 seq = read_seqcount_begin(&tk_core.seq);
2296
2297 base = tk->tkr_mono.base;
2298 nsecs = timekeeping_get_ns(&tk->tkr_mono);
2299 base = ktime_add_ns(base, nsecs);
2300
2301 if (*cwsseq != tk->clock_was_set_seq) {
2302 *cwsseq = tk->clock_was_set_seq;
2303 *offs_real = tk->offs_real;
2304 *offs_boot = tk->offs_boot;
2305 *offs_tai = tk->offs_tai;
2306 }
2307
2308 /* Handle leapsecond insertion adjustments */
2309 if (unlikely(base >= tk->next_leap_ktime))
2310 *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2311
2312 } while (read_seqcount_retry(&tk_core.seq, seq));
2313
2314 return base;
2315}
2316
2317/*
2318 * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2319 */
2320static int timekeeping_validate_timex(const struct __kernel_timex *txc)
2321{
2322 if (txc->modes & ADJ_ADJTIME) {
2323 /* singleshot must not be used with any other mode bits */
2324 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2325 return -EINVAL;
2326 if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2327 !capable(CAP_SYS_TIME))
2328 return -EPERM;
2329 } else {
2330 /* In order to modify anything, you gotta be super-user! */
2331 if (txc->modes && !capable(CAP_SYS_TIME))
2332 return -EPERM;
2333 /*
2334 * if the quartz is off by more than 10% then
2335 * something is VERY wrong!
2336 */
2337 if (txc->modes & ADJ_TICK &&
2338 (txc->tick < 900000/USER_HZ ||
2339 txc->tick > 1100000/USER_HZ))
2340 return -EINVAL;
2341 }
2342
2343 if (txc->modes & ADJ_SETOFFSET) {
2344 /* In order to inject time, you gotta be super-user! */
2345 if (!capable(CAP_SYS_TIME))
2346 return -EPERM;
2347
2348 /*
2349 * Validate if a timespec/timeval used to inject a time
2350 * offset is valid. Offsets can be positive or negative, so
2351 * we don't check tv_sec. The value of the timeval/timespec
2352 * is the sum of its fields,but *NOTE*:
2353 * The field tv_usec/tv_nsec must always be non-negative and
2354 * we can't have more nanoseconds/microseconds than a second.
2355 */
2356 if (txc->time.tv_usec < 0)
2357 return -EINVAL;
2358
2359 if (txc->modes & ADJ_NANO) {
2360 if (txc->time.tv_usec >= NSEC_PER_SEC)
2361 return -EINVAL;
2362 } else {
2363 if (txc->time.tv_usec >= USEC_PER_SEC)
2364 return -EINVAL;
2365 }
2366 }
2367
2368 /*
2369 * Check for potential multiplication overflows that can
2370 * only happen on 64-bit systems:
2371 */
2372 if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2373 if (LLONG_MIN / PPM_SCALE > txc->freq)
2374 return -EINVAL;
2375 if (LLONG_MAX / PPM_SCALE < txc->freq)
2376 return -EINVAL;
2377 }
2378
2379 return 0;
2380}
2381
2382
2383/**
2384 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2385 */
2386int do_adjtimex(struct __kernel_timex *txc)
2387{
2388 struct timekeeper *tk = &tk_core.timekeeper;
2389 struct audit_ntp_data ad;
2390 unsigned long flags;
2391 struct timespec64 ts;
2392 s32 orig_tai, tai;
2393 int ret;
2394
2395 /* Validate the data before disabling interrupts */
2396 ret = timekeeping_validate_timex(txc);
2397 if (ret)
2398 return ret;
2399
2400 if (txc->modes & ADJ_SETOFFSET) {
2401 struct timespec64 delta;
2402 delta.tv_sec = txc->time.tv_sec;
2403 delta.tv_nsec = txc->time.tv_usec;
2404 if (!(txc->modes & ADJ_NANO))
2405 delta.tv_nsec *= 1000;
2406 ret = timekeeping_inject_offset(&delta);
2407 if (ret)
2408 return ret;
2409
2410 audit_tk_injoffset(delta);
2411 }
2412
2413 audit_ntp_init(&ad);
2414
2415 ktime_get_real_ts64(&ts);
2416
2417 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2418 write_seqcount_begin(&tk_core.seq);
2419
2420 orig_tai = tai = tk->tai_offset;
2421 ret = __do_adjtimex(txc, &ts, &tai, &ad);
2422
2423 if (tai != orig_tai) {
2424 __timekeeping_set_tai_offset(tk, tai);
2425 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2426 }
2427 tk_update_leap_state(tk);
2428
2429 write_seqcount_end(&tk_core.seq);
2430 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2431
2432 audit_ntp_log(&ad);
2433
2434 /* Update the multiplier immediately if frequency was set directly */
2435 if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
2436 timekeeping_advance(TK_ADV_FREQ);
2437
2438 if (tai != orig_tai)
2439 clock_was_set();
2440
2441 ntp_notify_cmos_timer();
2442
2443 return ret;
2444}
2445
2446#ifdef CONFIG_NTP_PPS
2447/**
2448 * hardpps() - Accessor function to NTP __hardpps function
2449 */
2450void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2451{
2452 unsigned long flags;
2453
2454 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2455 write_seqcount_begin(&tk_core.seq);
2456
2457 __hardpps(phase_ts, raw_ts);
2458
2459 write_seqcount_end(&tk_core.seq);
2460 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2461}
2462EXPORT_SYMBOL(hardpps);
2463#endif /* CONFIG_NTP_PPS */