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