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1/*
2 * linux/kernel/time/timekeeping.c
3 *
4 * Kernel timekeeping code and accessor functions
5 *
6 * This code was moved from linux/kernel/timer.c.
7 * Please see that file for copyright and history logs.
8 *
9 */
10
11#include <linux/module.h>
12#include <linux/interrupt.h>
13#include <linux/percpu.h>
14#include <linux/init.h>
15#include <linux/mm.h>
16#include <linux/sched.h>
17#include <linux/syscore_ops.h>
18#include <linux/clocksource.h>
19#include <linux/jiffies.h>
20#include <linux/time.h>
21#include <linux/tick.h>
22#include <linux/stop_machine.h>
23
24/* Structure holding internal timekeeping values. */
25struct timekeeper {
26 /* Current clocksource used for timekeeping. */
27 struct clocksource *clock;
28 /* 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/*
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/timekeeper_internal.h>
12#include <linux/module.h>
13#include <linux/interrupt.h>
14#include <linux/percpu.h>
15#include <linux/init.h>
16#include <linux/mm.h>
17#include <linux/nmi.h>
18#include <linux/sched.h>
19#include <linux/sched/loadavg.h>
20#include <linux/syscore_ops.h>
21#include <linux/clocksource.h>
22#include <linux/jiffies.h>
23#include <linux/time.h>
24#include <linux/tick.h>
25#include <linux/stop_machine.h>
26#include <linux/pvclock_gtod.h>
27#include <linux/compiler.h>
28
29#include "tick-internal.h"
30#include "ntp_internal.h"
31#include "timekeeping_internal.h"
32
33#define TK_CLEAR_NTP (1 << 0)
34#define TK_MIRROR (1 << 1)
35#define TK_CLOCK_WAS_SET (1 << 2)
36
37/*
38 * The most important data for readout fits into a single 64 byte
39 * cache line.
40 */
41static struct {
42 seqcount_t seq;
43 struct timekeeper timekeeper;
44} tk_core ____cacheline_aligned;
45
46static DEFINE_RAW_SPINLOCK(timekeeper_lock);
47static struct timekeeper shadow_timekeeper;
48
49/**
50 * struct tk_fast - NMI safe timekeeper
51 * @seq: Sequence counter for protecting updates. The lowest bit
52 * is the index for the tk_read_base array
53 * @base: tk_read_base array. Access is indexed by the lowest bit of
54 * @seq.
55 *
56 * See @update_fast_timekeeper() below.
57 */
58struct tk_fast {
59 seqcount_t seq;
60 struct tk_read_base base[2];
61};
62
63/* Suspend-time cycles value for halted fast timekeeper. */
64static u64 cycles_at_suspend;
65
66static u64 dummy_clock_read(struct clocksource *cs)
67{
68 return cycles_at_suspend;
69}
70
71static struct clocksource dummy_clock = {
72 .read = dummy_clock_read,
73};
74
75static struct tk_fast tk_fast_mono ____cacheline_aligned = {
76 .base[0] = { .clock = &dummy_clock, },
77 .base[1] = { .clock = &dummy_clock, },
78};
79
80static struct tk_fast tk_fast_raw ____cacheline_aligned = {
81 .base[0] = { .clock = &dummy_clock, },
82 .base[1] = { .clock = &dummy_clock, },
83};
84
85/* flag for if timekeeping is suspended */
86int __read_mostly timekeeping_suspended;
87
88static inline void tk_normalize_xtime(struct timekeeper *tk)
89{
90 while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
91 tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
92 tk->xtime_sec++;
93 }
94 while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) {
95 tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
96 tk->raw_sec++;
97 }
98}
99
100static inline struct timespec64 tk_xtime(struct timekeeper *tk)
101{
102 struct timespec64 ts;
103
104 ts.tv_sec = tk->xtime_sec;
105 ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
106 return ts;
107}
108
109static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
110{
111 tk->xtime_sec = ts->tv_sec;
112 tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
113}
114
115static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts)
116{
117 tk->xtime_sec += ts->tv_sec;
118 tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift;
119 tk_normalize_xtime(tk);
120}
121
122static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
123{
124 struct timespec64 tmp;
125
126 /*
127 * Verify consistency of: offset_real = -wall_to_monotonic
128 * before modifying anything
129 */
130 set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
131 -tk->wall_to_monotonic.tv_nsec);
132 WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp));
133 tk->wall_to_monotonic = wtm;
134 set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
135 tk->offs_real = timespec64_to_ktime(tmp);
136 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
137}
138
139static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
140{
141 tk->offs_boot = ktime_add(tk->offs_boot, delta);
142}
143
144/*
145 * tk_clock_read - atomic clocksource read() helper
146 *
147 * This helper is necessary to use in the read paths because, while the
148 * seqlock ensures we don't return a bad value while structures are updated,
149 * it doesn't protect from potential crashes. There is the possibility that
150 * the tkr's clocksource may change between the read reference, and the
151 * clock reference passed to the read function. This can cause crashes if
152 * the wrong clocksource is passed to the wrong read function.
153 * This isn't necessary to use when holding the timekeeper_lock or doing
154 * a read of the fast-timekeeper tkrs (which is protected by its own locking
155 * and update logic).
156 */
157static inline u64 tk_clock_read(struct tk_read_base *tkr)
158{
159 struct clocksource *clock = READ_ONCE(tkr->clock);
160
161 return clock->read(clock);
162}
163
164#ifdef CONFIG_DEBUG_TIMEKEEPING
165#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
166
167static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
168{
169
170 u64 max_cycles = tk->tkr_mono.clock->max_cycles;
171 const char *name = tk->tkr_mono.clock->name;
172
173 if (offset > max_cycles) {
174 printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
175 offset, name, max_cycles);
176 printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
177 } else {
178 if (offset > (max_cycles >> 1)) {
179 printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
180 offset, name, max_cycles >> 1);
181 printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
182 }
183 }
184
185 if (tk->underflow_seen) {
186 if (jiffies - tk->last_warning > WARNING_FREQ) {
187 printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
188 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
189 printk_deferred(" Your kernel is probably still fine.\n");
190 tk->last_warning = jiffies;
191 }
192 tk->underflow_seen = 0;
193 }
194
195 if (tk->overflow_seen) {
196 if (jiffies - tk->last_warning > WARNING_FREQ) {
197 printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
198 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
199 printk_deferred(" Your kernel is probably still fine.\n");
200 tk->last_warning = jiffies;
201 }
202 tk->overflow_seen = 0;
203 }
204}
205
206static inline u64 timekeeping_get_delta(struct tk_read_base *tkr)
207{
208 struct timekeeper *tk = &tk_core.timekeeper;
209 u64 now, last, mask, max, delta;
210 unsigned int seq;
211
212 /*
213 * Since we're called holding a seqlock, the data may shift
214 * under us while we're doing the calculation. This can cause
215 * false positives, since we'd note a problem but throw the
216 * results away. So nest another seqlock here to atomically
217 * grab the points we are checking with.
218 */
219 do {
220 seq = read_seqcount_begin(&tk_core.seq);
221 now = tk_clock_read(tkr);
222 last = tkr->cycle_last;
223 mask = tkr->mask;
224 max = tkr->clock->max_cycles;
225 } while (read_seqcount_retry(&tk_core.seq, seq));
226
227 delta = clocksource_delta(now, last, mask);
228
229 /*
230 * Try to catch underflows by checking if we are seeing small
231 * mask-relative negative values.
232 */
233 if (unlikely((~delta & mask) < (mask >> 3))) {
234 tk->underflow_seen = 1;
235 delta = 0;
236 }
237
238 /* Cap delta value to the max_cycles values to avoid mult overflows */
239 if (unlikely(delta > max)) {
240 tk->overflow_seen = 1;
241 delta = tkr->clock->max_cycles;
242 }
243
244 return delta;
245}
246#else
247static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
248{
249}
250static inline u64 timekeeping_get_delta(struct tk_read_base *tkr)
251{
252 u64 cycle_now, delta;
253
254 /* read clocksource */
255 cycle_now = tk_clock_read(tkr);
256
257 /* calculate the delta since the last update_wall_time */
258 delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
259
260 return delta;
261}
262#endif
263
264/**
265 * tk_setup_internals - Set up internals to use clocksource clock.
266 *
267 * @tk: The target timekeeper to setup.
268 * @clock: Pointer to clocksource.
269 *
270 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
271 * pair and interval request.
272 *
273 * Unless you're the timekeeping code, you should not be using this!
274 */
275static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
276{
277 u64 interval;
278 u64 tmp, ntpinterval;
279 struct clocksource *old_clock;
280
281 ++tk->cs_was_changed_seq;
282 old_clock = tk->tkr_mono.clock;
283 tk->tkr_mono.clock = clock;
284 tk->tkr_mono.mask = clock->mask;
285 tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono);
286
287 tk->tkr_raw.clock = clock;
288 tk->tkr_raw.mask = clock->mask;
289 tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
290
291 /* Do the ns -> cycle conversion first, using original mult */
292 tmp = NTP_INTERVAL_LENGTH;
293 tmp <<= clock->shift;
294 ntpinterval = tmp;
295 tmp += clock->mult/2;
296 do_div(tmp, clock->mult);
297 if (tmp == 0)
298 tmp = 1;
299
300 interval = (u64) tmp;
301 tk->cycle_interval = interval;
302
303 /* Go back from cycles -> shifted ns */
304 tk->xtime_interval = interval * clock->mult;
305 tk->xtime_remainder = ntpinterval - tk->xtime_interval;
306 tk->raw_interval = interval * clock->mult;
307
308 /* if changing clocks, convert xtime_nsec shift units */
309 if (old_clock) {
310 int shift_change = clock->shift - old_clock->shift;
311 if (shift_change < 0) {
312 tk->tkr_mono.xtime_nsec >>= -shift_change;
313 tk->tkr_raw.xtime_nsec >>= -shift_change;
314 } else {
315 tk->tkr_mono.xtime_nsec <<= shift_change;
316 tk->tkr_raw.xtime_nsec <<= shift_change;
317 }
318 }
319
320 tk->tkr_mono.shift = clock->shift;
321 tk->tkr_raw.shift = clock->shift;
322
323 tk->ntp_error = 0;
324 tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
325 tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
326
327 /*
328 * The timekeeper keeps its own mult values for the currently
329 * active clocksource. These value will be adjusted via NTP
330 * to counteract clock drifting.
331 */
332 tk->tkr_mono.mult = clock->mult;
333 tk->tkr_raw.mult = clock->mult;
334 tk->ntp_err_mult = 0;
335 tk->skip_second_overflow = 0;
336}
337
338/* Timekeeper helper functions. */
339
340#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
341static u32 default_arch_gettimeoffset(void) { return 0; }
342u32 (*arch_gettimeoffset)(void) = default_arch_gettimeoffset;
343#else
344static inline u32 arch_gettimeoffset(void) { return 0; }
345#endif
346
347static inline u64 timekeeping_delta_to_ns(struct tk_read_base *tkr, u64 delta)
348{
349 u64 nsec;
350
351 nsec = delta * tkr->mult + tkr->xtime_nsec;
352 nsec >>= tkr->shift;
353
354 /* If arch requires, add in get_arch_timeoffset() */
355 return nsec + arch_gettimeoffset();
356}
357
358static inline u64 timekeeping_get_ns(struct tk_read_base *tkr)
359{
360 u64 delta;
361
362 delta = timekeeping_get_delta(tkr);
363 return timekeeping_delta_to_ns(tkr, delta);
364}
365
366static inline u64 timekeeping_cycles_to_ns(struct tk_read_base *tkr, u64 cycles)
367{
368 u64 delta;
369
370 /* calculate the delta since the last update_wall_time */
371 delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
372 return timekeeping_delta_to_ns(tkr, delta);
373}
374
375/**
376 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
377 * @tkr: Timekeeping readout base from which we take the update
378 *
379 * We want to use this from any context including NMI and tracing /
380 * instrumenting the timekeeping code itself.
381 *
382 * Employ the latch technique; see @raw_write_seqcount_latch.
383 *
384 * So if a NMI hits the update of base[0] then it will use base[1]
385 * which is still consistent. In the worst case this can result is a
386 * slightly wrong timestamp (a few nanoseconds). See
387 * @ktime_get_mono_fast_ns.
388 */
389static void update_fast_timekeeper(struct tk_read_base *tkr, struct tk_fast *tkf)
390{
391 struct tk_read_base *base = tkf->base;
392
393 /* Force readers off to base[1] */
394 raw_write_seqcount_latch(&tkf->seq);
395
396 /* Update base[0] */
397 memcpy(base, tkr, sizeof(*base));
398
399 /* Force readers back to base[0] */
400 raw_write_seqcount_latch(&tkf->seq);
401
402 /* Update base[1] */
403 memcpy(base + 1, base, sizeof(*base));
404}
405
406/**
407 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
408 *
409 * This timestamp is not guaranteed to be monotonic across an update.
410 * The timestamp is calculated by:
411 *
412 * now = base_mono + clock_delta * slope
413 *
414 * So if the update lowers the slope, readers who are forced to the
415 * not yet updated second array are still using the old steeper slope.
416 *
417 * tmono
418 * ^
419 * | o n
420 * | o n
421 * | u
422 * | o
423 * |o
424 * |12345678---> reader order
425 *
426 * o = old slope
427 * u = update
428 * n = new slope
429 *
430 * So reader 6 will observe time going backwards versus reader 5.
431 *
432 * While other CPUs are likely to be able observe that, the only way
433 * for a CPU local observation is when an NMI hits in the middle of
434 * the update. Timestamps taken from that NMI context might be ahead
435 * of the following timestamps. Callers need to be aware of that and
436 * deal with it.
437 */
438static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
439{
440 struct tk_read_base *tkr;
441 unsigned int seq;
442 u64 now;
443
444 do {
445 seq = raw_read_seqcount_latch(&tkf->seq);
446 tkr = tkf->base + (seq & 0x01);
447 now = ktime_to_ns(tkr->base);
448
449 now += timekeeping_delta_to_ns(tkr,
450 clocksource_delta(
451 tk_clock_read(tkr),
452 tkr->cycle_last,
453 tkr->mask));
454 } while (read_seqcount_retry(&tkf->seq, seq));
455
456 return now;
457}
458
459u64 ktime_get_mono_fast_ns(void)
460{
461 return __ktime_get_fast_ns(&tk_fast_mono);
462}
463EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
464
465u64 ktime_get_raw_fast_ns(void)
466{
467 return __ktime_get_fast_ns(&tk_fast_raw);
468}
469EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
470
471/**
472 * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
473 *
474 * To keep it NMI safe since we're accessing from tracing, we're not using a
475 * separate timekeeper with updates to monotonic clock and boot offset
476 * protected with seqlocks. This has the following minor side effects:
477 *
478 * (1) Its possible that a timestamp be taken after the boot offset is updated
479 * but before the timekeeper is updated. If this happens, the new boot offset
480 * is added to the old timekeeping making the clock appear to update slightly
481 * earlier:
482 * CPU 0 CPU 1
483 * timekeeping_inject_sleeptime64()
484 * __timekeeping_inject_sleeptime(tk, delta);
485 * timestamp();
486 * timekeeping_update(tk, TK_CLEAR_NTP...);
487 *
488 * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
489 * partially updated. Since the tk->offs_boot update is a rare event, this
490 * should be a rare occurrence which postprocessing should be able to handle.
491 */
492u64 notrace ktime_get_boot_fast_ns(void)
493{
494 struct timekeeper *tk = &tk_core.timekeeper;
495
496 return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot));
497}
498EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
499
500
501/*
502 * See comment for __ktime_get_fast_ns() vs. timestamp ordering
503 */
504static __always_inline u64 __ktime_get_real_fast_ns(struct tk_fast *tkf)
505{
506 struct tk_read_base *tkr;
507 unsigned int seq;
508 u64 now;
509
510 do {
511 seq = raw_read_seqcount_latch(&tkf->seq);
512 tkr = tkf->base + (seq & 0x01);
513 now = ktime_to_ns(tkr->base_real);
514
515 now += timekeeping_delta_to_ns(tkr,
516 clocksource_delta(
517 tk_clock_read(tkr),
518 tkr->cycle_last,
519 tkr->mask));
520 } while (read_seqcount_retry(&tkf->seq, seq));
521
522 return now;
523}
524
525/**
526 * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime.
527 */
528u64 ktime_get_real_fast_ns(void)
529{
530 return __ktime_get_real_fast_ns(&tk_fast_mono);
531}
532EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns);
533
534/**
535 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
536 * @tk: Timekeeper to snapshot.
537 *
538 * It generally is unsafe to access the clocksource after timekeeping has been
539 * suspended, so take a snapshot of the readout base of @tk and use it as the
540 * fast timekeeper's readout base while suspended. It will return the same
541 * number of cycles every time until timekeeping is resumed at which time the
542 * proper readout base for the fast timekeeper will be restored automatically.
543 */
544static void halt_fast_timekeeper(struct timekeeper *tk)
545{
546 static struct tk_read_base tkr_dummy;
547 struct tk_read_base *tkr = &tk->tkr_mono;
548
549 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
550 cycles_at_suspend = tk_clock_read(tkr);
551 tkr_dummy.clock = &dummy_clock;
552 tkr_dummy.base_real = tkr->base + tk->offs_real;
553 update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
554
555 tkr = &tk->tkr_raw;
556 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
557 tkr_dummy.clock = &dummy_clock;
558 update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
559}
560
561static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
562
563static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
564{
565 raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
566}
567
568/**
569 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
570 */
571int pvclock_gtod_register_notifier(struct notifier_block *nb)
572{
573 struct timekeeper *tk = &tk_core.timekeeper;
574 unsigned long flags;
575 int ret;
576
577 raw_spin_lock_irqsave(&timekeeper_lock, flags);
578 ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
579 update_pvclock_gtod(tk, true);
580 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
581
582 return ret;
583}
584EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
585
586/**
587 * pvclock_gtod_unregister_notifier - unregister a pvclock
588 * timedata update listener
589 */
590int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
591{
592 unsigned long flags;
593 int ret;
594
595 raw_spin_lock_irqsave(&timekeeper_lock, flags);
596 ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
597 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
598
599 return ret;
600}
601EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
602
603/*
604 * tk_update_leap_state - helper to update the next_leap_ktime
605 */
606static inline void tk_update_leap_state(struct timekeeper *tk)
607{
608 tk->next_leap_ktime = ntp_get_next_leap();
609 if (tk->next_leap_ktime != KTIME_MAX)
610 /* Convert to monotonic time */
611 tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
612}
613
614/*
615 * Update the ktime_t based scalar nsec members of the timekeeper
616 */
617static inline void tk_update_ktime_data(struct timekeeper *tk)
618{
619 u64 seconds;
620 u32 nsec;
621
622 /*
623 * The xtime based monotonic readout is:
624 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
625 * The ktime based monotonic readout is:
626 * nsec = base_mono + now();
627 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
628 */
629 seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
630 nsec = (u32) tk->wall_to_monotonic.tv_nsec;
631 tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
632
633 /*
634 * The sum of the nanoseconds portions of xtime and
635 * wall_to_monotonic can be greater/equal one second. Take
636 * this into account before updating tk->ktime_sec.
637 */
638 nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
639 if (nsec >= NSEC_PER_SEC)
640 seconds++;
641 tk->ktime_sec = seconds;
642
643 /* Update the monotonic raw base */
644 tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
645}
646
647/* must hold timekeeper_lock */
648static void timekeeping_update(struct timekeeper *tk, unsigned int action)
649{
650 if (action & TK_CLEAR_NTP) {
651 tk->ntp_error = 0;
652 ntp_clear();
653 }
654
655 tk_update_leap_state(tk);
656 tk_update_ktime_data(tk);
657
658 update_vsyscall(tk);
659 update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
660
661 tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
662 update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
663 update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
664
665 if (action & TK_CLOCK_WAS_SET)
666 tk->clock_was_set_seq++;
667 /*
668 * The mirroring of the data to the shadow-timekeeper needs
669 * to happen last here to ensure we don't over-write the
670 * timekeeper structure on the next update with stale data
671 */
672 if (action & TK_MIRROR)
673 memcpy(&shadow_timekeeper, &tk_core.timekeeper,
674 sizeof(tk_core.timekeeper));
675}
676
677/**
678 * timekeeping_forward_now - update clock to the current time
679 *
680 * Forward the current clock to update its state since the last call to
681 * update_wall_time(). This is useful before significant clock changes,
682 * as it avoids having to deal with this time offset explicitly.
683 */
684static void timekeeping_forward_now(struct timekeeper *tk)
685{
686 u64 cycle_now, delta;
687
688 cycle_now = tk_clock_read(&tk->tkr_mono);
689 delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
690 tk->tkr_mono.cycle_last = cycle_now;
691 tk->tkr_raw.cycle_last = cycle_now;
692
693 tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
694
695 /* If arch requires, add in get_arch_timeoffset() */
696 tk->tkr_mono.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_mono.shift;
697
698
699 tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
700
701 /* If arch requires, add in get_arch_timeoffset() */
702 tk->tkr_raw.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_raw.shift;
703
704 tk_normalize_xtime(tk);
705}
706
707/**
708 * __getnstimeofday64 - Returns the time of day in a timespec64.
709 * @ts: pointer to the timespec to be set
710 *
711 * Updates the time of day in the timespec.
712 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
713 */
714int __getnstimeofday64(struct timespec64 *ts)
715{
716 struct timekeeper *tk = &tk_core.timekeeper;
717 unsigned long seq;
718 u64 nsecs;
719
720 do {
721 seq = read_seqcount_begin(&tk_core.seq);
722
723 ts->tv_sec = tk->xtime_sec;
724 nsecs = timekeeping_get_ns(&tk->tkr_mono);
725
726 } while (read_seqcount_retry(&tk_core.seq, seq));
727
728 ts->tv_nsec = 0;
729 timespec64_add_ns(ts, nsecs);
730
731 /*
732 * Do not bail out early, in case there were callers still using
733 * the value, even in the face of the WARN_ON.
734 */
735 if (unlikely(timekeeping_suspended))
736 return -EAGAIN;
737 return 0;
738}
739EXPORT_SYMBOL(__getnstimeofday64);
740
741/**
742 * getnstimeofday64 - Returns the time of day in a timespec64.
743 * @ts: pointer to the timespec64 to be set
744 *
745 * Returns the time of day in a timespec64 (WARN if suspended).
746 */
747void getnstimeofday64(struct timespec64 *ts)
748{
749 WARN_ON(__getnstimeofday64(ts));
750}
751EXPORT_SYMBOL(getnstimeofday64);
752
753ktime_t ktime_get(void)
754{
755 struct timekeeper *tk = &tk_core.timekeeper;
756 unsigned int seq;
757 ktime_t base;
758 u64 nsecs;
759
760 WARN_ON(timekeeping_suspended);
761
762 do {
763 seq = read_seqcount_begin(&tk_core.seq);
764 base = tk->tkr_mono.base;
765 nsecs = timekeeping_get_ns(&tk->tkr_mono);
766
767 } while (read_seqcount_retry(&tk_core.seq, seq));
768
769 return ktime_add_ns(base, nsecs);
770}
771EXPORT_SYMBOL_GPL(ktime_get);
772
773u32 ktime_get_resolution_ns(void)
774{
775 struct timekeeper *tk = &tk_core.timekeeper;
776 unsigned int seq;
777 u32 nsecs;
778
779 WARN_ON(timekeeping_suspended);
780
781 do {
782 seq = read_seqcount_begin(&tk_core.seq);
783 nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
784 } while (read_seqcount_retry(&tk_core.seq, seq));
785
786 return nsecs;
787}
788EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
789
790static ktime_t *offsets[TK_OFFS_MAX] = {
791 [TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
792 [TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
793 [TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai,
794};
795
796ktime_t ktime_get_with_offset(enum tk_offsets offs)
797{
798 struct timekeeper *tk = &tk_core.timekeeper;
799 unsigned int seq;
800 ktime_t base, *offset = offsets[offs];
801 u64 nsecs;
802
803 WARN_ON(timekeeping_suspended);
804
805 do {
806 seq = read_seqcount_begin(&tk_core.seq);
807 base = ktime_add(tk->tkr_mono.base, *offset);
808 nsecs = timekeeping_get_ns(&tk->tkr_mono);
809
810 } while (read_seqcount_retry(&tk_core.seq, seq));
811
812 return ktime_add_ns(base, nsecs);
813
814}
815EXPORT_SYMBOL_GPL(ktime_get_with_offset);
816
817/**
818 * ktime_mono_to_any() - convert mononotic time to any other time
819 * @tmono: time to convert.
820 * @offs: which offset to use
821 */
822ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
823{
824 ktime_t *offset = offsets[offs];
825 unsigned long seq;
826 ktime_t tconv;
827
828 do {
829 seq = read_seqcount_begin(&tk_core.seq);
830 tconv = ktime_add(tmono, *offset);
831 } while (read_seqcount_retry(&tk_core.seq, seq));
832
833 return tconv;
834}
835EXPORT_SYMBOL_GPL(ktime_mono_to_any);
836
837/**
838 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
839 */
840ktime_t ktime_get_raw(void)
841{
842 struct timekeeper *tk = &tk_core.timekeeper;
843 unsigned int seq;
844 ktime_t base;
845 u64 nsecs;
846
847 do {
848 seq = read_seqcount_begin(&tk_core.seq);
849 base = tk->tkr_raw.base;
850 nsecs = timekeeping_get_ns(&tk->tkr_raw);
851
852 } while (read_seqcount_retry(&tk_core.seq, seq));
853
854 return ktime_add_ns(base, nsecs);
855}
856EXPORT_SYMBOL_GPL(ktime_get_raw);
857
858/**
859 * ktime_get_ts64 - get the monotonic clock in timespec64 format
860 * @ts: pointer to timespec variable
861 *
862 * The function calculates the monotonic clock from the realtime
863 * clock and the wall_to_monotonic offset and stores the result
864 * in normalized timespec64 format in the variable pointed to by @ts.
865 */
866void ktime_get_ts64(struct timespec64 *ts)
867{
868 struct timekeeper *tk = &tk_core.timekeeper;
869 struct timespec64 tomono;
870 unsigned int seq;
871 u64 nsec;
872
873 WARN_ON(timekeeping_suspended);
874
875 do {
876 seq = read_seqcount_begin(&tk_core.seq);
877 ts->tv_sec = tk->xtime_sec;
878 nsec = timekeeping_get_ns(&tk->tkr_mono);
879 tomono = tk->wall_to_monotonic;
880
881 } while (read_seqcount_retry(&tk_core.seq, seq));
882
883 ts->tv_sec += tomono.tv_sec;
884 ts->tv_nsec = 0;
885 timespec64_add_ns(ts, nsec + tomono.tv_nsec);
886}
887EXPORT_SYMBOL_GPL(ktime_get_ts64);
888
889/**
890 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
891 *
892 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
893 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
894 * works on both 32 and 64 bit systems. On 32 bit systems the readout
895 * covers ~136 years of uptime which should be enough to prevent
896 * premature wrap arounds.
897 */
898time64_t ktime_get_seconds(void)
899{
900 struct timekeeper *tk = &tk_core.timekeeper;
901
902 WARN_ON(timekeeping_suspended);
903 return tk->ktime_sec;
904}
905EXPORT_SYMBOL_GPL(ktime_get_seconds);
906
907/**
908 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
909 *
910 * Returns the wall clock seconds since 1970. This replaces the
911 * get_seconds() interface which is not y2038 safe on 32bit systems.
912 *
913 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
914 * 32bit systems the access must be protected with the sequence
915 * counter to provide "atomic" access to the 64bit tk->xtime_sec
916 * value.
917 */
918time64_t ktime_get_real_seconds(void)
919{
920 struct timekeeper *tk = &tk_core.timekeeper;
921 time64_t seconds;
922 unsigned int seq;
923
924 if (IS_ENABLED(CONFIG_64BIT))
925 return tk->xtime_sec;
926
927 do {
928 seq = read_seqcount_begin(&tk_core.seq);
929 seconds = tk->xtime_sec;
930
931 } while (read_seqcount_retry(&tk_core.seq, seq));
932
933 return seconds;
934}
935EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
936
937/**
938 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
939 * but without the sequence counter protect. This internal function
940 * is called just when timekeeping lock is already held.
941 */
942time64_t __ktime_get_real_seconds(void)
943{
944 struct timekeeper *tk = &tk_core.timekeeper;
945
946 return tk->xtime_sec;
947}
948
949/**
950 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
951 * @systime_snapshot: pointer to struct receiving the system time snapshot
952 */
953void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
954{
955 struct timekeeper *tk = &tk_core.timekeeper;
956 unsigned long seq;
957 ktime_t base_raw;
958 ktime_t base_real;
959 u64 nsec_raw;
960 u64 nsec_real;
961 u64 now;
962
963 WARN_ON_ONCE(timekeeping_suspended);
964
965 do {
966 seq = read_seqcount_begin(&tk_core.seq);
967 now = tk_clock_read(&tk->tkr_mono);
968 systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
969 systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
970 base_real = ktime_add(tk->tkr_mono.base,
971 tk_core.timekeeper.offs_real);
972 base_raw = tk->tkr_raw.base;
973 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
974 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
975 } while (read_seqcount_retry(&tk_core.seq, seq));
976
977 systime_snapshot->cycles = now;
978 systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
979 systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
980}
981EXPORT_SYMBOL_GPL(ktime_get_snapshot);
982
983/* Scale base by mult/div checking for overflow */
984static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
985{
986 u64 tmp, rem;
987
988 tmp = div64_u64_rem(*base, div, &rem);
989
990 if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
991 ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
992 return -EOVERFLOW;
993 tmp *= mult;
994 rem *= mult;
995
996 do_div(rem, div);
997 *base = tmp + rem;
998 return 0;
999}
1000
1001/**
1002 * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
1003 * @history: Snapshot representing start of history
1004 * @partial_history_cycles: Cycle offset into history (fractional part)
1005 * @total_history_cycles: Total history length in cycles
1006 * @discontinuity: True indicates clock was set on history period
1007 * @ts: Cross timestamp that should be adjusted using
1008 * partial/total ratio
1009 *
1010 * Helper function used by get_device_system_crosststamp() to correct the
1011 * crosstimestamp corresponding to the start of the current interval to the
1012 * system counter value (timestamp point) provided by the driver. The
1013 * total_history_* quantities are the total history starting at the provided
1014 * reference point and ending at the start of the current interval. The cycle
1015 * count between the driver timestamp point and the start of the current
1016 * interval is partial_history_cycles.
1017 */
1018static int adjust_historical_crosststamp(struct system_time_snapshot *history,
1019 u64 partial_history_cycles,
1020 u64 total_history_cycles,
1021 bool discontinuity,
1022 struct system_device_crosststamp *ts)
1023{
1024 struct timekeeper *tk = &tk_core.timekeeper;
1025 u64 corr_raw, corr_real;
1026 bool interp_forward;
1027 int ret;
1028
1029 if (total_history_cycles == 0 || partial_history_cycles == 0)
1030 return 0;
1031
1032 /* Interpolate shortest distance from beginning or end of history */
1033 interp_forward = partial_history_cycles > total_history_cycles / 2;
1034 partial_history_cycles = interp_forward ?
1035 total_history_cycles - partial_history_cycles :
1036 partial_history_cycles;
1037
1038 /*
1039 * Scale the monotonic raw time delta by:
1040 * partial_history_cycles / total_history_cycles
1041 */
1042 corr_raw = (u64)ktime_to_ns(
1043 ktime_sub(ts->sys_monoraw, history->raw));
1044 ret = scale64_check_overflow(partial_history_cycles,
1045 total_history_cycles, &corr_raw);
1046 if (ret)
1047 return ret;
1048
1049 /*
1050 * If there is a discontinuity in the history, scale monotonic raw
1051 * correction by:
1052 * mult(real)/mult(raw) yielding the realtime correction
1053 * Otherwise, calculate the realtime correction similar to monotonic
1054 * raw calculation
1055 */
1056 if (discontinuity) {
1057 corr_real = mul_u64_u32_div
1058 (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1059 } else {
1060 corr_real = (u64)ktime_to_ns(
1061 ktime_sub(ts->sys_realtime, history->real));
1062 ret = scale64_check_overflow(partial_history_cycles,
1063 total_history_cycles, &corr_real);
1064 if (ret)
1065 return ret;
1066 }
1067
1068 /* Fixup monotonic raw and real time time values */
1069 if (interp_forward) {
1070 ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1071 ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1072 } else {
1073 ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1074 ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1075 }
1076
1077 return 0;
1078}
1079
1080/*
1081 * cycle_between - true if test occurs chronologically between before and after
1082 */
1083static bool cycle_between(u64 before, u64 test, u64 after)
1084{
1085 if (test > before && test < after)
1086 return true;
1087 if (test < before && before > after)
1088 return true;
1089 return false;
1090}
1091
1092/**
1093 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1094 * @get_time_fn: Callback to get simultaneous device time and
1095 * system counter from the device driver
1096 * @ctx: Context passed to get_time_fn()
1097 * @history_begin: Historical reference point used to interpolate system
1098 * time when counter provided by the driver is before the current interval
1099 * @xtstamp: Receives simultaneously captured system and device time
1100 *
1101 * Reads a timestamp from a device and correlates it to system time
1102 */
1103int get_device_system_crosststamp(int (*get_time_fn)
1104 (ktime_t *device_time,
1105 struct system_counterval_t *sys_counterval,
1106 void *ctx),
1107 void *ctx,
1108 struct system_time_snapshot *history_begin,
1109 struct system_device_crosststamp *xtstamp)
1110{
1111 struct system_counterval_t system_counterval;
1112 struct timekeeper *tk = &tk_core.timekeeper;
1113 u64 cycles, now, interval_start;
1114 unsigned int clock_was_set_seq = 0;
1115 ktime_t base_real, base_raw;
1116 u64 nsec_real, nsec_raw;
1117 u8 cs_was_changed_seq;
1118 unsigned long seq;
1119 bool do_interp;
1120 int ret;
1121
1122 do {
1123 seq = read_seqcount_begin(&tk_core.seq);
1124 /*
1125 * Try to synchronously capture device time and a system
1126 * counter value calling back into the device driver
1127 */
1128 ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1129 if (ret)
1130 return ret;
1131
1132 /*
1133 * Verify that the clocksource associated with the captured
1134 * system counter value is the same as the currently installed
1135 * timekeeper clocksource
1136 */
1137 if (tk->tkr_mono.clock != system_counterval.cs)
1138 return -ENODEV;
1139 cycles = system_counterval.cycles;
1140
1141 /*
1142 * Check whether the system counter value provided by the
1143 * device driver is on the current timekeeping interval.
1144 */
1145 now = tk_clock_read(&tk->tkr_mono);
1146 interval_start = tk->tkr_mono.cycle_last;
1147 if (!cycle_between(interval_start, cycles, now)) {
1148 clock_was_set_seq = tk->clock_was_set_seq;
1149 cs_was_changed_seq = tk->cs_was_changed_seq;
1150 cycles = interval_start;
1151 do_interp = true;
1152 } else {
1153 do_interp = false;
1154 }
1155
1156 base_real = ktime_add(tk->tkr_mono.base,
1157 tk_core.timekeeper.offs_real);
1158 base_raw = tk->tkr_raw.base;
1159
1160 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1161 system_counterval.cycles);
1162 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1163 system_counterval.cycles);
1164 } while (read_seqcount_retry(&tk_core.seq, seq));
1165
1166 xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1167 xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1168
1169 /*
1170 * Interpolate if necessary, adjusting back from the start of the
1171 * current interval
1172 */
1173 if (do_interp) {
1174 u64 partial_history_cycles, total_history_cycles;
1175 bool discontinuity;
1176
1177 /*
1178 * Check that the counter value occurs after the provided
1179 * history reference and that the history doesn't cross a
1180 * clocksource change
1181 */
1182 if (!history_begin ||
1183 !cycle_between(history_begin->cycles,
1184 system_counterval.cycles, cycles) ||
1185 history_begin->cs_was_changed_seq != cs_was_changed_seq)
1186 return -EINVAL;
1187 partial_history_cycles = cycles - system_counterval.cycles;
1188 total_history_cycles = cycles - history_begin->cycles;
1189 discontinuity =
1190 history_begin->clock_was_set_seq != clock_was_set_seq;
1191
1192 ret = adjust_historical_crosststamp(history_begin,
1193 partial_history_cycles,
1194 total_history_cycles,
1195 discontinuity, xtstamp);
1196 if (ret)
1197 return ret;
1198 }
1199
1200 return 0;
1201}
1202EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1203
1204/**
1205 * do_gettimeofday - Returns the time of day in a timeval
1206 * @tv: pointer to the timeval to be set
1207 *
1208 * NOTE: Users should be converted to using getnstimeofday()
1209 */
1210void do_gettimeofday(struct timeval *tv)
1211{
1212 struct timespec64 now;
1213
1214 getnstimeofday64(&now);
1215 tv->tv_sec = now.tv_sec;
1216 tv->tv_usec = now.tv_nsec/1000;
1217}
1218EXPORT_SYMBOL(do_gettimeofday);
1219
1220/**
1221 * do_settimeofday64 - Sets the time of day.
1222 * @ts: pointer to the timespec64 variable containing the new time
1223 *
1224 * Sets the time of day to the new time and update NTP and notify hrtimers
1225 */
1226int do_settimeofday64(const struct timespec64 *ts)
1227{
1228 struct timekeeper *tk = &tk_core.timekeeper;
1229 struct timespec64 ts_delta, xt;
1230 unsigned long flags;
1231 int ret = 0;
1232
1233 if (!timespec64_valid_strict(ts))
1234 return -EINVAL;
1235
1236 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1237 write_seqcount_begin(&tk_core.seq);
1238
1239 timekeeping_forward_now(tk);
1240
1241 xt = tk_xtime(tk);
1242 ts_delta.tv_sec = ts->tv_sec - xt.tv_sec;
1243 ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec;
1244
1245 if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1246 ret = -EINVAL;
1247 goto out;
1248 }
1249
1250 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1251
1252 tk_set_xtime(tk, ts);
1253out:
1254 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1255
1256 write_seqcount_end(&tk_core.seq);
1257 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1258
1259 /* signal hrtimers about time change */
1260 clock_was_set();
1261
1262 return ret;
1263}
1264EXPORT_SYMBOL(do_settimeofday64);
1265
1266/**
1267 * timekeeping_inject_offset - Adds or subtracts from the current time.
1268 * @tv: pointer to the timespec variable containing the offset
1269 *
1270 * Adds or subtracts an offset value from the current time.
1271 */
1272static int timekeeping_inject_offset(struct timespec64 *ts)
1273{
1274 struct timekeeper *tk = &tk_core.timekeeper;
1275 unsigned long flags;
1276 struct timespec64 tmp;
1277 int ret = 0;
1278
1279 if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
1280 return -EINVAL;
1281
1282 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1283 write_seqcount_begin(&tk_core.seq);
1284
1285 timekeeping_forward_now(tk);
1286
1287 /* Make sure the proposed value is valid */
1288 tmp = timespec64_add(tk_xtime(tk), *ts);
1289 if (timespec64_compare(&tk->wall_to_monotonic, ts) > 0 ||
1290 !timespec64_valid_strict(&tmp)) {
1291 ret = -EINVAL;
1292 goto error;
1293 }
1294
1295 tk_xtime_add(tk, ts);
1296 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *ts));
1297
1298error: /* even if we error out, we forwarded the time, so call update */
1299 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1300
1301 write_seqcount_end(&tk_core.seq);
1302 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1303
1304 /* signal hrtimers about time change */
1305 clock_was_set();
1306
1307 return ret;
1308}
1309
1310/*
1311 * Indicates if there is an offset between the system clock and the hardware
1312 * clock/persistent clock/rtc.
1313 */
1314int persistent_clock_is_local;
1315
1316/*
1317 * Adjust the time obtained from the CMOS to be UTC time instead of
1318 * local time.
1319 *
1320 * This is ugly, but preferable to the alternatives. Otherwise we
1321 * would either need to write a program to do it in /etc/rc (and risk
1322 * confusion if the program gets run more than once; it would also be
1323 * hard to make the program warp the clock precisely n hours) or
1324 * compile in the timezone information into the kernel. Bad, bad....
1325 *
1326 * - TYT, 1992-01-01
1327 *
1328 * The best thing to do is to keep the CMOS clock in universal time (UTC)
1329 * as real UNIX machines always do it. This avoids all headaches about
1330 * daylight saving times and warping kernel clocks.
1331 */
1332void timekeeping_warp_clock(void)
1333{
1334 if (sys_tz.tz_minuteswest != 0) {
1335 struct timespec64 adjust;
1336
1337 persistent_clock_is_local = 1;
1338 adjust.tv_sec = sys_tz.tz_minuteswest * 60;
1339 adjust.tv_nsec = 0;
1340 timekeeping_inject_offset(&adjust);
1341 }
1342}
1343
1344/**
1345 * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1346 *
1347 */
1348static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1349{
1350 tk->tai_offset = tai_offset;
1351 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1352}
1353
1354/**
1355 * change_clocksource - Swaps clocksources if a new one is available
1356 *
1357 * Accumulates current time interval and initializes new clocksource
1358 */
1359static int change_clocksource(void *data)
1360{
1361 struct timekeeper *tk = &tk_core.timekeeper;
1362 struct clocksource *new, *old;
1363 unsigned long flags;
1364
1365 new = (struct clocksource *) data;
1366
1367 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1368 write_seqcount_begin(&tk_core.seq);
1369
1370 timekeeping_forward_now(tk);
1371 /*
1372 * If the cs is in module, get a module reference. Succeeds
1373 * for built-in code (owner == NULL) as well.
1374 */
1375 if (try_module_get(new->owner)) {
1376 if (!new->enable || new->enable(new) == 0) {
1377 old = tk->tkr_mono.clock;
1378 tk_setup_internals(tk, new);
1379 if (old->disable)
1380 old->disable(old);
1381 module_put(old->owner);
1382 } else {
1383 module_put(new->owner);
1384 }
1385 }
1386 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1387
1388 write_seqcount_end(&tk_core.seq);
1389 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1390
1391 return 0;
1392}
1393
1394/**
1395 * timekeeping_notify - Install a new clock source
1396 * @clock: pointer to the clock source
1397 *
1398 * This function is called from clocksource.c after a new, better clock
1399 * source has been registered. The caller holds the clocksource_mutex.
1400 */
1401int timekeeping_notify(struct clocksource *clock)
1402{
1403 struct timekeeper *tk = &tk_core.timekeeper;
1404
1405 if (tk->tkr_mono.clock == clock)
1406 return 0;
1407 stop_machine(change_clocksource, clock, NULL);
1408 tick_clock_notify();
1409 return tk->tkr_mono.clock == clock ? 0 : -1;
1410}
1411
1412/**
1413 * getrawmonotonic64 - Returns the raw monotonic time in a timespec
1414 * @ts: pointer to the timespec64 to be set
1415 *
1416 * Returns the raw monotonic time (completely un-modified by ntp)
1417 */
1418void getrawmonotonic64(struct timespec64 *ts)
1419{
1420 struct timekeeper *tk = &tk_core.timekeeper;
1421 unsigned long seq;
1422 u64 nsecs;
1423
1424 do {
1425 seq = read_seqcount_begin(&tk_core.seq);
1426 ts->tv_sec = tk->raw_sec;
1427 nsecs = timekeeping_get_ns(&tk->tkr_raw);
1428
1429 } while (read_seqcount_retry(&tk_core.seq, seq));
1430
1431 ts->tv_nsec = 0;
1432 timespec64_add_ns(ts, nsecs);
1433}
1434EXPORT_SYMBOL(getrawmonotonic64);
1435
1436
1437/**
1438 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1439 */
1440int timekeeping_valid_for_hres(void)
1441{
1442 struct timekeeper *tk = &tk_core.timekeeper;
1443 unsigned long seq;
1444 int ret;
1445
1446 do {
1447 seq = read_seqcount_begin(&tk_core.seq);
1448
1449 ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1450
1451 } while (read_seqcount_retry(&tk_core.seq, seq));
1452
1453 return ret;
1454}
1455
1456/**
1457 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1458 */
1459u64 timekeeping_max_deferment(void)
1460{
1461 struct timekeeper *tk = &tk_core.timekeeper;
1462 unsigned long seq;
1463 u64 ret;
1464
1465 do {
1466 seq = read_seqcount_begin(&tk_core.seq);
1467
1468 ret = tk->tkr_mono.clock->max_idle_ns;
1469
1470 } while (read_seqcount_retry(&tk_core.seq, seq));
1471
1472 return ret;
1473}
1474
1475/**
1476 * read_persistent_clock - Return time from the persistent clock.
1477 *
1478 * Weak dummy function for arches that do not yet support it.
1479 * Reads the time from the battery backed persistent clock.
1480 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1481 *
1482 * XXX - Do be sure to remove it once all arches implement it.
1483 */
1484void __weak read_persistent_clock(struct timespec *ts)
1485{
1486 ts->tv_sec = 0;
1487 ts->tv_nsec = 0;
1488}
1489
1490void __weak read_persistent_clock64(struct timespec64 *ts64)
1491{
1492 struct timespec ts;
1493
1494 read_persistent_clock(&ts);
1495 *ts64 = timespec_to_timespec64(ts);
1496}
1497
1498/**
1499 * read_boot_clock64 - Return time of the system start.
1500 *
1501 * Weak dummy function for arches that do not yet support it.
1502 * Function to read the exact time the system has been started.
1503 * Returns a timespec64 with tv_sec=0 and tv_nsec=0 if unsupported.
1504 *
1505 * XXX - Do be sure to remove it once all arches implement it.
1506 */
1507void __weak read_boot_clock64(struct timespec64 *ts)
1508{
1509 ts->tv_sec = 0;
1510 ts->tv_nsec = 0;
1511}
1512
1513/* Flag for if timekeeping_resume() has injected sleeptime */
1514static bool sleeptime_injected;
1515
1516/* Flag for if there is a persistent clock on this platform */
1517static bool persistent_clock_exists;
1518
1519/*
1520 * timekeeping_init - Initializes the clocksource and common timekeeping values
1521 */
1522void __init timekeeping_init(void)
1523{
1524 struct timekeeper *tk = &tk_core.timekeeper;
1525 struct clocksource *clock;
1526 unsigned long flags;
1527 struct timespec64 now, boot, tmp;
1528
1529 read_persistent_clock64(&now);
1530 if (!timespec64_valid_strict(&now)) {
1531 pr_warn("WARNING: Persistent clock returned invalid value!\n"
1532 " Check your CMOS/BIOS settings.\n");
1533 now.tv_sec = 0;
1534 now.tv_nsec = 0;
1535 } else if (now.tv_sec || now.tv_nsec)
1536 persistent_clock_exists = true;
1537
1538 read_boot_clock64(&boot);
1539 if (!timespec64_valid_strict(&boot)) {
1540 pr_warn("WARNING: Boot clock returned invalid value!\n"
1541 " Check your CMOS/BIOS settings.\n");
1542 boot.tv_sec = 0;
1543 boot.tv_nsec = 0;
1544 }
1545
1546 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1547 write_seqcount_begin(&tk_core.seq);
1548 ntp_init();
1549
1550 clock = clocksource_default_clock();
1551 if (clock->enable)
1552 clock->enable(clock);
1553 tk_setup_internals(tk, clock);
1554
1555 tk_set_xtime(tk, &now);
1556 tk->raw_sec = 0;
1557 if (boot.tv_sec == 0 && boot.tv_nsec == 0)
1558 boot = tk_xtime(tk);
1559
1560 set_normalized_timespec64(&tmp, -boot.tv_sec, -boot.tv_nsec);
1561 tk_set_wall_to_mono(tk, tmp);
1562
1563 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1564
1565 write_seqcount_end(&tk_core.seq);
1566 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1567}
1568
1569/* time in seconds when suspend began for persistent clock */
1570static struct timespec64 timekeeping_suspend_time;
1571
1572/**
1573 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1574 * @delta: pointer to a timespec delta value
1575 *
1576 * Takes a timespec offset measuring a suspend interval and properly
1577 * adds the sleep offset to the timekeeping variables.
1578 */
1579static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1580 struct timespec64 *delta)
1581{
1582 if (!timespec64_valid_strict(delta)) {
1583 printk_deferred(KERN_WARNING
1584 "__timekeeping_inject_sleeptime: Invalid "
1585 "sleep delta value!\n");
1586 return;
1587 }
1588 tk_xtime_add(tk, delta);
1589 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1590 tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1591 tk_debug_account_sleep_time(delta);
1592}
1593
1594#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1595/**
1596 * We have three kinds of time sources to use for sleep time
1597 * injection, the preference order is:
1598 * 1) non-stop clocksource
1599 * 2) persistent clock (ie: RTC accessible when irqs are off)
1600 * 3) RTC
1601 *
1602 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1603 * If system has neither 1) nor 2), 3) will be used finally.
1604 *
1605 *
1606 * If timekeeping has injected sleeptime via either 1) or 2),
1607 * 3) becomes needless, so in this case we don't need to call
1608 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1609 * means.
1610 */
1611bool timekeeping_rtc_skipresume(void)
1612{
1613 return sleeptime_injected;
1614}
1615
1616/**
1617 * 1) can be determined whether to use or not only when doing
1618 * timekeeping_resume() which is invoked after rtc_suspend(),
1619 * so we can't skip rtc_suspend() surely if system has 1).
1620 *
1621 * But if system has 2), 2) will definitely be used, so in this
1622 * case we don't need to call rtc_suspend(), and this is what
1623 * timekeeping_rtc_skipsuspend() means.
1624 */
1625bool timekeeping_rtc_skipsuspend(void)
1626{
1627 return persistent_clock_exists;
1628}
1629
1630/**
1631 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1632 * @delta: pointer to a timespec64 delta value
1633 *
1634 * This hook is for architectures that cannot support read_persistent_clock64
1635 * because their RTC/persistent clock is only accessible when irqs are enabled.
1636 * and also don't have an effective nonstop clocksource.
1637 *
1638 * This function should only be called by rtc_resume(), and allows
1639 * a suspend offset to be injected into the timekeeping values.
1640 */
1641void timekeeping_inject_sleeptime64(struct timespec64 *delta)
1642{
1643 struct timekeeper *tk = &tk_core.timekeeper;
1644 unsigned long flags;
1645
1646 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1647 write_seqcount_begin(&tk_core.seq);
1648
1649 timekeeping_forward_now(tk);
1650
1651 __timekeeping_inject_sleeptime(tk, delta);
1652
1653 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1654
1655 write_seqcount_end(&tk_core.seq);
1656 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1657
1658 /* signal hrtimers about time change */
1659 clock_was_set();
1660}
1661#endif
1662
1663/**
1664 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1665 */
1666void timekeeping_resume(void)
1667{
1668 struct timekeeper *tk = &tk_core.timekeeper;
1669 struct clocksource *clock = tk->tkr_mono.clock;
1670 unsigned long flags;
1671 struct timespec64 ts_new, ts_delta;
1672 u64 cycle_now;
1673
1674 sleeptime_injected = false;
1675 read_persistent_clock64(&ts_new);
1676
1677 clockevents_resume();
1678 clocksource_resume();
1679
1680 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1681 write_seqcount_begin(&tk_core.seq);
1682
1683 /*
1684 * After system resumes, we need to calculate the suspended time and
1685 * compensate it for the OS time. There are 3 sources that could be
1686 * used: Nonstop clocksource during suspend, persistent clock and rtc
1687 * device.
1688 *
1689 * One specific platform may have 1 or 2 or all of them, and the
1690 * preference will be:
1691 * suspend-nonstop clocksource -> persistent clock -> rtc
1692 * The less preferred source will only be tried if there is no better
1693 * usable source. The rtc part is handled separately in rtc core code.
1694 */
1695 cycle_now = tk_clock_read(&tk->tkr_mono);
1696 if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) &&
1697 cycle_now > tk->tkr_mono.cycle_last) {
1698 u64 nsec, cyc_delta;
1699
1700 cyc_delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last,
1701 tk->tkr_mono.mask);
1702 nsec = mul_u64_u32_shr(cyc_delta, clock->mult, clock->shift);
1703 ts_delta = ns_to_timespec64(nsec);
1704 sleeptime_injected = true;
1705 } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1706 ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1707 sleeptime_injected = true;
1708 }
1709
1710 if (sleeptime_injected)
1711 __timekeeping_inject_sleeptime(tk, &ts_delta);
1712
1713 /* Re-base the last cycle value */
1714 tk->tkr_mono.cycle_last = cycle_now;
1715 tk->tkr_raw.cycle_last = cycle_now;
1716
1717 tk->ntp_error = 0;
1718 timekeeping_suspended = 0;
1719 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1720 write_seqcount_end(&tk_core.seq);
1721 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1722
1723 touch_softlockup_watchdog();
1724
1725 tick_resume();
1726 hrtimers_resume();
1727}
1728
1729int timekeeping_suspend(void)
1730{
1731 struct timekeeper *tk = &tk_core.timekeeper;
1732 unsigned long flags;
1733 struct timespec64 delta, delta_delta;
1734 static struct timespec64 old_delta;
1735
1736 read_persistent_clock64(&timekeeping_suspend_time);
1737
1738 /*
1739 * On some systems the persistent_clock can not be detected at
1740 * timekeeping_init by its return value, so if we see a valid
1741 * value returned, update the persistent_clock_exists flag.
1742 */
1743 if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1744 persistent_clock_exists = true;
1745
1746 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1747 write_seqcount_begin(&tk_core.seq);
1748 timekeeping_forward_now(tk);
1749 timekeeping_suspended = 1;
1750
1751 if (persistent_clock_exists) {
1752 /*
1753 * To avoid drift caused by repeated suspend/resumes,
1754 * which each can add ~1 second drift error,
1755 * try to compensate so the difference in system time
1756 * and persistent_clock time stays close to constant.
1757 */
1758 delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1759 delta_delta = timespec64_sub(delta, old_delta);
1760 if (abs(delta_delta.tv_sec) >= 2) {
1761 /*
1762 * if delta_delta is too large, assume time correction
1763 * has occurred and set old_delta to the current delta.
1764 */
1765 old_delta = delta;
1766 } else {
1767 /* Otherwise try to adjust old_system to compensate */
1768 timekeeping_suspend_time =
1769 timespec64_add(timekeeping_suspend_time, delta_delta);
1770 }
1771 }
1772
1773 timekeeping_update(tk, TK_MIRROR);
1774 halt_fast_timekeeper(tk);
1775 write_seqcount_end(&tk_core.seq);
1776 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1777
1778 tick_suspend();
1779 clocksource_suspend();
1780 clockevents_suspend();
1781
1782 return 0;
1783}
1784
1785/* sysfs resume/suspend bits for timekeeping */
1786static struct syscore_ops timekeeping_syscore_ops = {
1787 .resume = timekeeping_resume,
1788 .suspend = timekeeping_suspend,
1789};
1790
1791static int __init timekeeping_init_ops(void)
1792{
1793 register_syscore_ops(&timekeeping_syscore_ops);
1794 return 0;
1795}
1796device_initcall(timekeeping_init_ops);
1797
1798/*
1799 * Apply a multiplier adjustment to the timekeeper
1800 */
1801static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1802 s64 offset,
1803 s32 mult_adj)
1804{
1805 s64 interval = tk->cycle_interval;
1806
1807 if (mult_adj == 0) {
1808 return;
1809 } else if (mult_adj == -1) {
1810 interval = -interval;
1811 offset = -offset;
1812 } else if (mult_adj != 1) {
1813 interval *= mult_adj;
1814 offset *= mult_adj;
1815 }
1816
1817 /*
1818 * So the following can be confusing.
1819 *
1820 * To keep things simple, lets assume mult_adj == 1 for now.
1821 *
1822 * When mult_adj != 1, remember that the interval and offset values
1823 * have been appropriately scaled so the math is the same.
1824 *
1825 * The basic idea here is that we're increasing the multiplier
1826 * by one, this causes the xtime_interval to be incremented by
1827 * one cycle_interval. This is because:
1828 * xtime_interval = cycle_interval * mult
1829 * So if mult is being incremented by one:
1830 * xtime_interval = cycle_interval * (mult + 1)
1831 * Its the same as:
1832 * xtime_interval = (cycle_interval * mult) + cycle_interval
1833 * Which can be shortened to:
1834 * xtime_interval += cycle_interval
1835 *
1836 * So offset stores the non-accumulated cycles. Thus the current
1837 * time (in shifted nanoseconds) is:
1838 * now = (offset * adj) + xtime_nsec
1839 * Now, even though we're adjusting the clock frequency, we have
1840 * to keep time consistent. In other words, we can't jump back
1841 * in time, and we also want to avoid jumping forward in time.
1842 *
1843 * So given the same offset value, we need the time to be the same
1844 * both before and after the freq adjustment.
1845 * now = (offset * adj_1) + xtime_nsec_1
1846 * now = (offset * adj_2) + xtime_nsec_2
1847 * So:
1848 * (offset * adj_1) + xtime_nsec_1 =
1849 * (offset * adj_2) + xtime_nsec_2
1850 * And we know:
1851 * adj_2 = adj_1 + 1
1852 * So:
1853 * (offset * adj_1) + xtime_nsec_1 =
1854 * (offset * (adj_1+1)) + xtime_nsec_2
1855 * (offset * adj_1) + xtime_nsec_1 =
1856 * (offset * adj_1) + offset + xtime_nsec_2
1857 * Canceling the sides:
1858 * xtime_nsec_1 = offset + xtime_nsec_2
1859 * Which gives us:
1860 * xtime_nsec_2 = xtime_nsec_1 - offset
1861 * Which simplfies to:
1862 * xtime_nsec -= offset
1863 */
1864 if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1865 /* NTP adjustment caused clocksource mult overflow */
1866 WARN_ON_ONCE(1);
1867 return;
1868 }
1869
1870 tk->tkr_mono.mult += mult_adj;
1871 tk->xtime_interval += interval;
1872 tk->tkr_mono.xtime_nsec -= offset;
1873}
1874
1875/*
1876 * Adjust the timekeeper's multiplier to the correct frequency
1877 * and also to reduce the accumulated error value.
1878 */
1879static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1880{
1881 u32 mult;
1882
1883 /*
1884 * Determine the multiplier from the current NTP tick length.
1885 * Avoid expensive division when the tick length doesn't change.
1886 */
1887 if (likely(tk->ntp_tick == ntp_tick_length())) {
1888 mult = tk->tkr_mono.mult - tk->ntp_err_mult;
1889 } else {
1890 tk->ntp_tick = ntp_tick_length();
1891 mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) -
1892 tk->xtime_remainder, tk->cycle_interval);
1893 }
1894
1895 /*
1896 * If the clock is behind the NTP time, increase the multiplier by 1
1897 * to catch up with it. If it's ahead and there was a remainder in the
1898 * tick division, the clock will slow down. Otherwise it will stay
1899 * ahead until the tick length changes to a non-divisible value.
1900 */
1901 tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0;
1902 mult += tk->ntp_err_mult;
1903
1904 timekeeping_apply_adjustment(tk, offset, mult - tk->tkr_mono.mult);
1905
1906 if (unlikely(tk->tkr_mono.clock->maxadj &&
1907 (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
1908 > tk->tkr_mono.clock->maxadj))) {
1909 printk_once(KERN_WARNING
1910 "Adjusting %s more than 11%% (%ld vs %ld)\n",
1911 tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
1912 (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
1913 }
1914
1915 /*
1916 * It may be possible that when we entered this function, xtime_nsec
1917 * was very small. Further, if we're slightly speeding the clocksource
1918 * in the code above, its possible the required corrective factor to
1919 * xtime_nsec could cause it to underflow.
1920 *
1921 * Now, since we have already accumulated the second and the NTP
1922 * subsystem has been notified via second_overflow(), we need to skip
1923 * the next update.
1924 */
1925 if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
1926 tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC <<
1927 tk->tkr_mono.shift;
1928 tk->xtime_sec--;
1929 tk->skip_second_overflow = 1;
1930 }
1931}
1932
1933/**
1934 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1935 *
1936 * Helper function that accumulates the nsecs greater than a second
1937 * from the xtime_nsec field to the xtime_secs field.
1938 * It also calls into the NTP code to handle leapsecond processing.
1939 *
1940 */
1941static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
1942{
1943 u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
1944 unsigned int clock_set = 0;
1945
1946 while (tk->tkr_mono.xtime_nsec >= nsecps) {
1947 int leap;
1948
1949 tk->tkr_mono.xtime_nsec -= nsecps;
1950 tk->xtime_sec++;
1951
1952 /*
1953 * Skip NTP update if this second was accumulated before,
1954 * i.e. xtime_nsec underflowed in timekeeping_adjust()
1955 */
1956 if (unlikely(tk->skip_second_overflow)) {
1957 tk->skip_second_overflow = 0;
1958 continue;
1959 }
1960
1961 /* Figure out if its a leap sec and apply if needed */
1962 leap = second_overflow(tk->xtime_sec);
1963 if (unlikely(leap)) {
1964 struct timespec64 ts;
1965
1966 tk->xtime_sec += leap;
1967
1968 ts.tv_sec = leap;
1969 ts.tv_nsec = 0;
1970 tk_set_wall_to_mono(tk,
1971 timespec64_sub(tk->wall_to_monotonic, ts));
1972
1973 __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
1974
1975 clock_set = TK_CLOCK_WAS_SET;
1976 }
1977 }
1978 return clock_set;
1979}
1980
1981/**
1982 * logarithmic_accumulation - shifted accumulation of cycles
1983 *
1984 * This functions accumulates a shifted interval of cycles into
1985 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1986 * loop.
1987 *
1988 * Returns the unconsumed cycles.
1989 */
1990static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
1991 u32 shift, unsigned int *clock_set)
1992{
1993 u64 interval = tk->cycle_interval << shift;
1994 u64 snsec_per_sec;
1995
1996 /* If the offset is smaller than a shifted interval, do nothing */
1997 if (offset < interval)
1998 return offset;
1999
2000 /* Accumulate one shifted interval */
2001 offset -= interval;
2002 tk->tkr_mono.cycle_last += interval;
2003 tk->tkr_raw.cycle_last += interval;
2004
2005 tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2006 *clock_set |= accumulate_nsecs_to_secs(tk);
2007
2008 /* Accumulate raw time */
2009 tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2010 snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2011 while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2012 tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2013 tk->raw_sec++;
2014 }
2015
2016 /* Accumulate error between NTP and clock interval */
2017 tk->ntp_error += tk->ntp_tick << shift;
2018 tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2019 (tk->ntp_error_shift + shift);
2020
2021 return offset;
2022}
2023
2024/**
2025 * update_wall_time - Uses the current clocksource to increment the wall time
2026 *
2027 */
2028void update_wall_time(void)
2029{
2030 struct timekeeper *real_tk = &tk_core.timekeeper;
2031 struct timekeeper *tk = &shadow_timekeeper;
2032 u64 offset;
2033 int shift = 0, maxshift;
2034 unsigned int clock_set = 0;
2035 unsigned long flags;
2036
2037 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2038
2039 /* Make sure we're fully resumed: */
2040 if (unlikely(timekeeping_suspended))
2041 goto out;
2042
2043#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
2044 offset = real_tk->cycle_interval;
2045#else
2046 offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
2047 tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2048#endif
2049
2050 /* Check if there's really nothing to do */
2051 if (offset < real_tk->cycle_interval)
2052 goto out;
2053
2054 /* Do some additional sanity checking */
2055 timekeeping_check_update(tk, offset);
2056
2057 /*
2058 * With NO_HZ we may have to accumulate many cycle_intervals
2059 * (think "ticks") worth of time at once. To do this efficiently,
2060 * we calculate the largest doubling multiple of cycle_intervals
2061 * that is smaller than the offset. We then accumulate that
2062 * chunk in one go, and then try to consume the next smaller
2063 * doubled multiple.
2064 */
2065 shift = ilog2(offset) - ilog2(tk->cycle_interval);
2066 shift = max(0, shift);
2067 /* Bound shift to one less than what overflows tick_length */
2068 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2069 shift = min(shift, maxshift);
2070 while (offset >= tk->cycle_interval) {
2071 offset = logarithmic_accumulation(tk, offset, shift,
2072 &clock_set);
2073 if (offset < tk->cycle_interval<<shift)
2074 shift--;
2075 }
2076
2077 /* Adjust the multiplier to correct NTP error */
2078 timekeeping_adjust(tk, offset);
2079
2080 /*
2081 * Finally, make sure that after the rounding
2082 * xtime_nsec isn't larger than NSEC_PER_SEC
2083 */
2084 clock_set |= accumulate_nsecs_to_secs(tk);
2085
2086 write_seqcount_begin(&tk_core.seq);
2087 /*
2088 * Update the real timekeeper.
2089 *
2090 * We could avoid this memcpy by switching pointers, but that
2091 * requires changes to all other timekeeper usage sites as
2092 * well, i.e. move the timekeeper pointer getter into the
2093 * spinlocked/seqcount protected sections. And we trade this
2094 * memcpy under the tk_core.seq against one before we start
2095 * updating.
2096 */
2097 timekeeping_update(tk, clock_set);
2098 memcpy(real_tk, tk, sizeof(*tk));
2099 /* The memcpy must come last. Do not put anything here! */
2100 write_seqcount_end(&tk_core.seq);
2101out:
2102 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2103 if (clock_set)
2104 /* Have to call _delayed version, since in irq context*/
2105 clock_was_set_delayed();
2106}
2107
2108/**
2109 * getboottime64 - Return the real time of system boot.
2110 * @ts: pointer to the timespec64 to be set
2111 *
2112 * Returns the wall-time of boot in a timespec64.
2113 *
2114 * This is based on the wall_to_monotonic offset and the total suspend
2115 * time. Calls to settimeofday will affect the value returned (which
2116 * basically means that however wrong your real time clock is at boot time,
2117 * you get the right time here).
2118 */
2119void getboottime64(struct timespec64 *ts)
2120{
2121 struct timekeeper *tk = &tk_core.timekeeper;
2122 ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2123
2124 *ts = ktime_to_timespec64(t);
2125}
2126EXPORT_SYMBOL_GPL(getboottime64);
2127
2128unsigned long get_seconds(void)
2129{
2130 struct timekeeper *tk = &tk_core.timekeeper;
2131
2132 return tk->xtime_sec;
2133}
2134EXPORT_SYMBOL(get_seconds);
2135
2136struct timespec64 current_kernel_time64(void)
2137{
2138 struct timekeeper *tk = &tk_core.timekeeper;
2139 struct timespec64 now;
2140 unsigned long seq;
2141
2142 do {
2143 seq = read_seqcount_begin(&tk_core.seq);
2144
2145 now = tk_xtime(tk);
2146 } while (read_seqcount_retry(&tk_core.seq, seq));
2147
2148 return now;
2149}
2150EXPORT_SYMBOL(current_kernel_time64);
2151
2152struct timespec64 get_monotonic_coarse64(void)
2153{
2154 struct timekeeper *tk = &tk_core.timekeeper;
2155 struct timespec64 now, mono;
2156 unsigned long seq;
2157
2158 do {
2159 seq = read_seqcount_begin(&tk_core.seq);
2160
2161 now = tk_xtime(tk);
2162 mono = tk->wall_to_monotonic;
2163 } while (read_seqcount_retry(&tk_core.seq, seq));
2164
2165 set_normalized_timespec64(&now, now.tv_sec + mono.tv_sec,
2166 now.tv_nsec + mono.tv_nsec);
2167
2168 return now;
2169}
2170EXPORT_SYMBOL(get_monotonic_coarse64);
2171
2172/*
2173 * Must hold jiffies_lock
2174 */
2175void do_timer(unsigned long ticks)
2176{
2177 jiffies_64 += ticks;
2178 calc_global_load(ticks);
2179}
2180
2181/**
2182 * ktime_get_update_offsets_now - hrtimer helper
2183 * @cwsseq: pointer to check and store the clock was set sequence number
2184 * @offs_real: pointer to storage for monotonic -> realtime offset
2185 * @offs_boot: pointer to storage for monotonic -> boottime offset
2186 * @offs_tai: pointer to storage for monotonic -> clock tai offset
2187 *
2188 * Returns current monotonic time and updates the offsets if the
2189 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2190 * different.
2191 *
2192 * Called from hrtimer_interrupt() or retrigger_next_event()
2193 */
2194ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2195 ktime_t *offs_boot, ktime_t *offs_tai)
2196{
2197 struct timekeeper *tk = &tk_core.timekeeper;
2198 unsigned int seq;
2199 ktime_t base;
2200 u64 nsecs;
2201
2202 do {
2203 seq = read_seqcount_begin(&tk_core.seq);
2204
2205 base = tk->tkr_mono.base;
2206 nsecs = timekeeping_get_ns(&tk->tkr_mono);
2207 base = ktime_add_ns(base, nsecs);
2208
2209 if (*cwsseq != tk->clock_was_set_seq) {
2210 *cwsseq = tk->clock_was_set_seq;
2211 *offs_real = tk->offs_real;
2212 *offs_boot = tk->offs_boot;
2213 *offs_tai = tk->offs_tai;
2214 }
2215
2216 /* Handle leapsecond insertion adjustments */
2217 if (unlikely(base >= tk->next_leap_ktime))
2218 *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2219
2220 } while (read_seqcount_retry(&tk_core.seq, seq));
2221
2222 return base;
2223}
2224
2225/**
2226 * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2227 */
2228static int timekeeping_validate_timex(struct timex *txc)
2229{
2230 if (txc->modes & ADJ_ADJTIME) {
2231 /* singleshot must not be used with any other mode bits */
2232 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2233 return -EINVAL;
2234 if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2235 !capable(CAP_SYS_TIME))
2236 return -EPERM;
2237 } else {
2238 /* In order to modify anything, you gotta be super-user! */
2239 if (txc->modes && !capable(CAP_SYS_TIME))
2240 return -EPERM;
2241 /*
2242 * if the quartz is off by more than 10% then
2243 * something is VERY wrong!
2244 */
2245 if (txc->modes & ADJ_TICK &&
2246 (txc->tick < 900000/USER_HZ ||
2247 txc->tick > 1100000/USER_HZ))
2248 return -EINVAL;
2249 }
2250
2251 if (txc->modes & ADJ_SETOFFSET) {
2252 /* In order to inject time, you gotta be super-user! */
2253 if (!capable(CAP_SYS_TIME))
2254 return -EPERM;
2255
2256 /*
2257 * Validate if a timespec/timeval used to inject a time
2258 * offset is valid. Offsets can be postive or negative, so
2259 * we don't check tv_sec. The value of the timeval/timespec
2260 * is the sum of its fields,but *NOTE*:
2261 * The field tv_usec/tv_nsec must always be non-negative and
2262 * we can't have more nanoseconds/microseconds than a second.
2263 */
2264 if (txc->time.tv_usec < 0)
2265 return -EINVAL;
2266
2267 if (txc->modes & ADJ_NANO) {
2268 if (txc->time.tv_usec >= NSEC_PER_SEC)
2269 return -EINVAL;
2270 } else {
2271 if (txc->time.tv_usec >= USEC_PER_SEC)
2272 return -EINVAL;
2273 }
2274 }
2275
2276 /*
2277 * Check for potential multiplication overflows that can
2278 * only happen on 64-bit systems:
2279 */
2280 if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2281 if (LLONG_MIN / PPM_SCALE > txc->freq)
2282 return -EINVAL;
2283 if (LLONG_MAX / PPM_SCALE < txc->freq)
2284 return -EINVAL;
2285 }
2286
2287 return 0;
2288}
2289
2290
2291/**
2292 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2293 */
2294int do_adjtimex(struct timex *txc)
2295{
2296 struct timekeeper *tk = &tk_core.timekeeper;
2297 unsigned long flags;
2298 struct timespec64 ts;
2299 s32 orig_tai, tai;
2300 int ret;
2301
2302 /* Validate the data before disabling interrupts */
2303 ret = timekeeping_validate_timex(txc);
2304 if (ret)
2305 return ret;
2306
2307 if (txc->modes & ADJ_SETOFFSET) {
2308 struct timespec64 delta;
2309 delta.tv_sec = txc->time.tv_sec;
2310 delta.tv_nsec = txc->time.tv_usec;
2311 if (!(txc->modes & ADJ_NANO))
2312 delta.tv_nsec *= 1000;
2313 ret = timekeeping_inject_offset(&delta);
2314 if (ret)
2315 return ret;
2316 }
2317
2318 getnstimeofday64(&ts);
2319
2320 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2321 write_seqcount_begin(&tk_core.seq);
2322
2323 orig_tai = tai = tk->tai_offset;
2324 ret = __do_adjtimex(txc, &ts, &tai);
2325
2326 if (tai != orig_tai) {
2327 __timekeeping_set_tai_offset(tk, tai);
2328 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2329 }
2330 tk_update_leap_state(tk);
2331
2332 write_seqcount_end(&tk_core.seq);
2333 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2334
2335 if (tai != orig_tai)
2336 clock_was_set();
2337
2338 ntp_notify_cmos_timer();
2339
2340 return ret;
2341}
2342
2343#ifdef CONFIG_NTP_PPS
2344/**
2345 * hardpps() - Accessor function to NTP __hardpps function
2346 */
2347void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2348{
2349 unsigned long flags;
2350
2351 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2352 write_seqcount_begin(&tk_core.seq);
2353
2354 __hardpps(phase_ts, raw_ts);
2355
2356 write_seqcount_end(&tk_core.seq);
2357 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2358}
2359EXPORT_SYMBOL(hardpps);
2360#endif /* CONFIG_NTP_PPS */
2361
2362/**
2363 * xtime_update() - advances the timekeeping infrastructure
2364 * @ticks: number of ticks, that have elapsed since the last call.
2365 *
2366 * Must be called with interrupts disabled.
2367 */
2368void xtime_update(unsigned long ticks)
2369{
2370 write_seqlock(&jiffies_lock);
2371 do_timer(ticks);
2372 write_sequnlock(&jiffies_lock);
2373 update_wall_time();
2374}