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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/timekeeper_internal.h>
12#include <linux/module.h>
13#include <linux/interrupt.h>
14#include <linux/percpu.h>
15#include <linux/init.h>
16#include <linux/mm.h>
17#include <linux/sched.h>
18#include <linux/syscore_ops.h>
19#include <linux/clocksource.h>
20#include <linux/jiffies.h>
21#include <linux/time.h>
22#include <linux/tick.h>
23#include <linux/stop_machine.h>
24#include <linux/pvclock_gtod.h>
25#include <linux/compiler.h>
26
27#include "tick-internal.h"
28#include "ntp_internal.h"
29#include "timekeeping_internal.h"
30
31#define TK_CLEAR_NTP (1 << 0)
32#define TK_MIRROR (1 << 1)
33#define TK_CLOCK_WAS_SET (1 << 2)
34
35static struct timekeeper timekeeper;
36static DEFINE_RAW_SPINLOCK(timekeeper_lock);
37static seqcount_t timekeeper_seq;
38static struct timekeeper shadow_timekeeper;
39
40/* flag for if timekeeping is suspended */
41int __read_mostly timekeeping_suspended;
42
43/* Flag for if there is a persistent clock on this platform */
44bool __read_mostly persistent_clock_exist = false;
45
46static inline void tk_normalize_xtime(struct timekeeper *tk)
47{
48 while (tk->xtime_nsec >= ((u64)NSEC_PER_SEC << tk->shift)) {
49 tk->xtime_nsec -= (u64)NSEC_PER_SEC << tk->shift;
50 tk->xtime_sec++;
51 }
52}
53
54static void tk_set_xtime(struct timekeeper *tk, const struct timespec *ts)
55{
56 tk->xtime_sec = ts->tv_sec;
57 tk->xtime_nsec = (u64)ts->tv_nsec << tk->shift;
58}
59
60static void tk_xtime_add(struct timekeeper *tk, const struct timespec *ts)
61{
62 tk->xtime_sec += ts->tv_sec;
63 tk->xtime_nsec += (u64)ts->tv_nsec << tk->shift;
64 tk_normalize_xtime(tk);
65}
66
67static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec wtm)
68{
69 struct timespec tmp;
70
71 /*
72 * Verify consistency of: offset_real = -wall_to_monotonic
73 * before modifying anything
74 */
75 set_normalized_timespec(&tmp, -tk->wall_to_monotonic.tv_sec,
76 -tk->wall_to_monotonic.tv_nsec);
77 WARN_ON_ONCE(tk->offs_real.tv64 != timespec_to_ktime(tmp).tv64);
78 tk->wall_to_monotonic = wtm;
79 set_normalized_timespec(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
80 tk->offs_real = timespec_to_ktime(tmp);
81 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
82}
83
84static void tk_set_sleep_time(struct timekeeper *tk, struct timespec t)
85{
86 /* Verify consistency before modifying */
87 WARN_ON_ONCE(tk->offs_boot.tv64 != timespec_to_ktime(tk->total_sleep_time).tv64);
88
89 tk->total_sleep_time = t;
90 tk->offs_boot = timespec_to_ktime(t);
91}
92
93/**
94 * tk_setup_internals - Set up internals to use clocksource clock.
95 *
96 * @tk: The target timekeeper to setup.
97 * @clock: Pointer to clocksource.
98 *
99 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
100 * pair and interval request.
101 *
102 * Unless you're the timekeeping code, you should not be using this!
103 */
104static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
105{
106 cycle_t interval;
107 u64 tmp, ntpinterval;
108 struct clocksource *old_clock;
109
110 old_clock = tk->clock;
111 tk->clock = clock;
112 tk->cycle_last = clock->cycle_last = clock->read(clock);
113
114 /* Do the ns -> cycle conversion first, using original mult */
115 tmp = NTP_INTERVAL_LENGTH;
116 tmp <<= clock->shift;
117 ntpinterval = tmp;
118 tmp += clock->mult/2;
119 do_div(tmp, clock->mult);
120 if (tmp == 0)
121 tmp = 1;
122
123 interval = (cycle_t) tmp;
124 tk->cycle_interval = interval;
125
126 /* Go back from cycles -> shifted ns */
127 tk->xtime_interval = (u64) interval * clock->mult;
128 tk->xtime_remainder = ntpinterval - tk->xtime_interval;
129 tk->raw_interval =
130 ((u64) interval * clock->mult) >> clock->shift;
131
132 /* if changing clocks, convert xtime_nsec shift units */
133 if (old_clock) {
134 int shift_change = clock->shift - old_clock->shift;
135 if (shift_change < 0)
136 tk->xtime_nsec >>= -shift_change;
137 else
138 tk->xtime_nsec <<= shift_change;
139 }
140 tk->shift = clock->shift;
141
142 tk->ntp_error = 0;
143 tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
144
145 /*
146 * The timekeeper keeps its own mult values for the currently
147 * active clocksource. These value will be adjusted via NTP
148 * to counteract clock drifting.
149 */
150 tk->mult = clock->mult;
151}
152
153/* Timekeeper helper functions. */
154
155#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
156u32 (*arch_gettimeoffset)(void);
157
158u32 get_arch_timeoffset(void)
159{
160 if (likely(arch_gettimeoffset))
161 return arch_gettimeoffset();
162 return 0;
163}
164#else
165static inline u32 get_arch_timeoffset(void) { return 0; }
166#endif
167
168static inline s64 timekeeping_get_ns(struct timekeeper *tk)
169{
170 cycle_t cycle_now, cycle_delta;
171 struct clocksource *clock;
172 s64 nsec;
173
174 /* read clocksource: */
175 clock = tk->clock;
176 cycle_now = clock->read(clock);
177
178 /* calculate the delta since the last update_wall_time: */
179 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
180
181 nsec = cycle_delta * tk->mult + tk->xtime_nsec;
182 nsec >>= tk->shift;
183
184 /* If arch requires, add in get_arch_timeoffset() */
185 return nsec + get_arch_timeoffset();
186}
187
188static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk)
189{
190 cycle_t cycle_now, cycle_delta;
191 struct clocksource *clock;
192 s64 nsec;
193
194 /* read clocksource: */
195 clock = tk->clock;
196 cycle_now = clock->read(clock);
197
198 /* calculate the delta since the last update_wall_time: */
199 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
200
201 /* convert delta to nanoseconds. */
202 nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
203
204 /* If arch requires, add in get_arch_timeoffset() */
205 return nsec + get_arch_timeoffset();
206}
207
208static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
209
210static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
211{
212 raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
213}
214
215/**
216 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
217 */
218int pvclock_gtod_register_notifier(struct notifier_block *nb)
219{
220 struct timekeeper *tk = &timekeeper;
221 unsigned long flags;
222 int ret;
223
224 raw_spin_lock_irqsave(&timekeeper_lock, flags);
225 ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
226 update_pvclock_gtod(tk, true);
227 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
228
229 return ret;
230}
231EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
232
233/**
234 * pvclock_gtod_unregister_notifier - unregister a pvclock
235 * timedata update listener
236 */
237int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
238{
239 unsigned long flags;
240 int ret;
241
242 raw_spin_lock_irqsave(&timekeeper_lock, flags);
243 ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
244 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
245
246 return ret;
247}
248EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
249
250/* must hold timekeeper_lock */
251static void timekeeping_update(struct timekeeper *tk, unsigned int action)
252{
253 if (action & TK_CLEAR_NTP) {
254 tk->ntp_error = 0;
255 ntp_clear();
256 }
257 update_vsyscall(tk);
258 update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
259
260 if (action & TK_MIRROR)
261 memcpy(&shadow_timekeeper, &timekeeper, sizeof(timekeeper));
262}
263
264/**
265 * timekeeping_forward_now - update clock to the current time
266 *
267 * Forward the current clock to update its state since the last call to
268 * update_wall_time(). This is useful before significant clock changes,
269 * as it avoids having to deal with this time offset explicitly.
270 */
271static void timekeeping_forward_now(struct timekeeper *tk)
272{
273 cycle_t cycle_now, cycle_delta;
274 struct clocksource *clock;
275 s64 nsec;
276
277 clock = tk->clock;
278 cycle_now = clock->read(clock);
279 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
280 tk->cycle_last = clock->cycle_last = cycle_now;
281
282 tk->xtime_nsec += cycle_delta * tk->mult;
283
284 /* If arch requires, add in get_arch_timeoffset() */
285 tk->xtime_nsec += (u64)get_arch_timeoffset() << tk->shift;
286
287 tk_normalize_xtime(tk);
288
289 nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
290 timespec_add_ns(&tk->raw_time, nsec);
291}
292
293/**
294 * __getnstimeofday - Returns the time of day in a timespec.
295 * @ts: pointer to the timespec to be set
296 *
297 * Updates the time of day in the timespec.
298 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
299 */
300int __getnstimeofday(struct timespec *ts)
301{
302 struct timekeeper *tk = &timekeeper;
303 unsigned long seq;
304 s64 nsecs = 0;
305
306 do {
307 seq = read_seqcount_begin(&timekeeper_seq);
308
309 ts->tv_sec = tk->xtime_sec;
310 nsecs = timekeeping_get_ns(tk);
311
312 } while (read_seqcount_retry(&timekeeper_seq, seq));
313
314 ts->tv_nsec = 0;
315 timespec_add_ns(ts, nsecs);
316
317 /*
318 * Do not bail out early, in case there were callers still using
319 * the value, even in the face of the WARN_ON.
320 */
321 if (unlikely(timekeeping_suspended))
322 return -EAGAIN;
323 return 0;
324}
325EXPORT_SYMBOL(__getnstimeofday);
326
327/**
328 * getnstimeofday - Returns the time of day in a timespec.
329 * @ts: pointer to the timespec to be set
330 *
331 * Returns the time of day in a timespec (WARN if suspended).
332 */
333void getnstimeofday(struct timespec *ts)
334{
335 WARN_ON(__getnstimeofday(ts));
336}
337EXPORT_SYMBOL(getnstimeofday);
338
339ktime_t ktime_get(void)
340{
341 struct timekeeper *tk = &timekeeper;
342 unsigned int seq;
343 s64 secs, nsecs;
344
345 WARN_ON(timekeeping_suspended);
346
347 do {
348 seq = read_seqcount_begin(&timekeeper_seq);
349 secs = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
350 nsecs = timekeeping_get_ns(tk) + tk->wall_to_monotonic.tv_nsec;
351
352 } while (read_seqcount_retry(&timekeeper_seq, seq));
353 /*
354 * Use ktime_set/ktime_add_ns to create a proper ktime on
355 * 32-bit architectures without CONFIG_KTIME_SCALAR.
356 */
357 return ktime_add_ns(ktime_set(secs, 0), nsecs);
358}
359EXPORT_SYMBOL_GPL(ktime_get);
360
361/**
362 * ktime_get_ts - get the monotonic clock in timespec format
363 * @ts: pointer to timespec variable
364 *
365 * The function calculates the monotonic clock from the realtime
366 * clock and the wall_to_monotonic offset and stores the result
367 * in normalized timespec format in the variable pointed to by @ts.
368 */
369void ktime_get_ts(struct timespec *ts)
370{
371 struct timekeeper *tk = &timekeeper;
372 struct timespec tomono;
373 s64 nsec;
374 unsigned int seq;
375
376 WARN_ON(timekeeping_suspended);
377
378 do {
379 seq = read_seqcount_begin(&timekeeper_seq);
380 ts->tv_sec = tk->xtime_sec;
381 nsec = timekeeping_get_ns(tk);
382 tomono = tk->wall_to_monotonic;
383
384 } while (read_seqcount_retry(&timekeeper_seq, seq));
385
386 ts->tv_sec += tomono.tv_sec;
387 ts->tv_nsec = 0;
388 timespec_add_ns(ts, nsec + tomono.tv_nsec);
389}
390EXPORT_SYMBOL_GPL(ktime_get_ts);
391
392
393/**
394 * timekeeping_clocktai - Returns the TAI time of day in a timespec
395 * @ts: pointer to the timespec to be set
396 *
397 * Returns the time of day in a timespec.
398 */
399void timekeeping_clocktai(struct timespec *ts)
400{
401 struct timekeeper *tk = &timekeeper;
402 unsigned long seq;
403 u64 nsecs;
404
405 WARN_ON(timekeeping_suspended);
406
407 do {
408 seq = read_seqcount_begin(&timekeeper_seq);
409
410 ts->tv_sec = tk->xtime_sec + tk->tai_offset;
411 nsecs = timekeeping_get_ns(tk);
412
413 } while (read_seqcount_retry(&timekeeper_seq, seq));
414
415 ts->tv_nsec = 0;
416 timespec_add_ns(ts, nsecs);
417
418}
419EXPORT_SYMBOL(timekeeping_clocktai);
420
421
422/**
423 * ktime_get_clocktai - Returns the TAI time of day in a ktime
424 *
425 * Returns the time of day in a ktime.
426 */
427ktime_t ktime_get_clocktai(void)
428{
429 struct timespec ts;
430
431 timekeeping_clocktai(&ts);
432 return timespec_to_ktime(ts);
433}
434EXPORT_SYMBOL(ktime_get_clocktai);
435
436#ifdef CONFIG_NTP_PPS
437
438/**
439 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
440 * @ts_raw: pointer to the timespec to be set to raw monotonic time
441 * @ts_real: pointer to the timespec to be set to the time of day
442 *
443 * This function reads both the time of day and raw monotonic time at the
444 * same time atomically and stores the resulting timestamps in timespec
445 * format.
446 */
447void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
448{
449 struct timekeeper *tk = &timekeeper;
450 unsigned long seq;
451 s64 nsecs_raw, nsecs_real;
452
453 WARN_ON_ONCE(timekeeping_suspended);
454
455 do {
456 seq = read_seqcount_begin(&timekeeper_seq);
457
458 *ts_raw = tk->raw_time;
459 ts_real->tv_sec = tk->xtime_sec;
460 ts_real->tv_nsec = 0;
461
462 nsecs_raw = timekeeping_get_ns_raw(tk);
463 nsecs_real = timekeeping_get_ns(tk);
464
465 } while (read_seqcount_retry(&timekeeper_seq, seq));
466
467 timespec_add_ns(ts_raw, nsecs_raw);
468 timespec_add_ns(ts_real, nsecs_real);
469}
470EXPORT_SYMBOL(getnstime_raw_and_real);
471
472#endif /* CONFIG_NTP_PPS */
473
474/**
475 * do_gettimeofday - Returns the time of day in a timeval
476 * @tv: pointer to the timeval to be set
477 *
478 * NOTE: Users should be converted to using getnstimeofday()
479 */
480void do_gettimeofday(struct timeval *tv)
481{
482 struct timespec now;
483
484 getnstimeofday(&now);
485 tv->tv_sec = now.tv_sec;
486 tv->tv_usec = now.tv_nsec/1000;
487}
488EXPORT_SYMBOL(do_gettimeofday);
489
490/**
491 * do_settimeofday - Sets the time of day
492 * @tv: pointer to the timespec variable containing the new time
493 *
494 * Sets the time of day to the new time and update NTP and notify hrtimers
495 */
496int do_settimeofday(const struct timespec *tv)
497{
498 struct timekeeper *tk = &timekeeper;
499 struct timespec ts_delta, xt;
500 unsigned long flags;
501
502 if (!timespec_valid_strict(tv))
503 return -EINVAL;
504
505 raw_spin_lock_irqsave(&timekeeper_lock, flags);
506 write_seqcount_begin(&timekeeper_seq);
507
508 timekeeping_forward_now(tk);
509
510 xt = tk_xtime(tk);
511 ts_delta.tv_sec = tv->tv_sec - xt.tv_sec;
512 ts_delta.tv_nsec = tv->tv_nsec - xt.tv_nsec;
513
514 tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, ts_delta));
515
516 tk_set_xtime(tk, tv);
517
518 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
519
520 write_seqcount_end(&timekeeper_seq);
521 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
522
523 /* signal hrtimers about time change */
524 clock_was_set();
525
526 return 0;
527}
528EXPORT_SYMBOL(do_settimeofday);
529
530/**
531 * timekeeping_inject_offset - Adds or subtracts from the current time.
532 * @tv: pointer to the timespec variable containing the offset
533 *
534 * Adds or subtracts an offset value from the current time.
535 */
536int timekeeping_inject_offset(struct timespec *ts)
537{
538 struct timekeeper *tk = &timekeeper;
539 unsigned long flags;
540 struct timespec tmp;
541 int ret = 0;
542
543 if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
544 return -EINVAL;
545
546 raw_spin_lock_irqsave(&timekeeper_lock, flags);
547 write_seqcount_begin(&timekeeper_seq);
548
549 timekeeping_forward_now(tk);
550
551 /* Make sure the proposed value is valid */
552 tmp = timespec_add(tk_xtime(tk), *ts);
553 if (!timespec_valid_strict(&tmp)) {
554 ret = -EINVAL;
555 goto error;
556 }
557
558 tk_xtime_add(tk, ts);
559 tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *ts));
560
561error: /* even if we error out, we forwarded the time, so call update */
562 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
563
564 write_seqcount_end(&timekeeper_seq);
565 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
566
567 /* signal hrtimers about time change */
568 clock_was_set();
569
570 return ret;
571}
572EXPORT_SYMBOL(timekeeping_inject_offset);
573
574
575/**
576 * timekeeping_get_tai_offset - Returns current TAI offset from UTC
577 *
578 */
579s32 timekeeping_get_tai_offset(void)
580{
581 struct timekeeper *tk = &timekeeper;
582 unsigned int seq;
583 s32 ret;
584
585 do {
586 seq = read_seqcount_begin(&timekeeper_seq);
587 ret = tk->tai_offset;
588 } while (read_seqcount_retry(&timekeeper_seq, seq));
589
590 return ret;
591}
592
593/**
594 * __timekeeping_set_tai_offset - Lock free worker function
595 *
596 */
597static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
598{
599 tk->tai_offset = tai_offset;
600 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
601}
602
603/**
604 * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
605 *
606 */
607void timekeeping_set_tai_offset(s32 tai_offset)
608{
609 struct timekeeper *tk = &timekeeper;
610 unsigned long flags;
611
612 raw_spin_lock_irqsave(&timekeeper_lock, flags);
613 write_seqcount_begin(&timekeeper_seq);
614 __timekeeping_set_tai_offset(tk, tai_offset);
615 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
616 write_seqcount_end(&timekeeper_seq);
617 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
618 clock_was_set();
619}
620
621/**
622 * change_clocksource - Swaps clocksources if a new one is available
623 *
624 * Accumulates current time interval and initializes new clocksource
625 */
626static int change_clocksource(void *data)
627{
628 struct timekeeper *tk = &timekeeper;
629 struct clocksource *new, *old;
630 unsigned long flags;
631
632 new = (struct clocksource *) data;
633
634 raw_spin_lock_irqsave(&timekeeper_lock, flags);
635 write_seqcount_begin(&timekeeper_seq);
636
637 timekeeping_forward_now(tk);
638 /*
639 * If the cs is in module, get a module reference. Succeeds
640 * for built-in code (owner == NULL) as well.
641 */
642 if (try_module_get(new->owner)) {
643 if (!new->enable || new->enable(new) == 0) {
644 old = tk->clock;
645 tk_setup_internals(tk, new);
646 if (old->disable)
647 old->disable(old);
648 module_put(old->owner);
649 } else {
650 module_put(new->owner);
651 }
652 }
653 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
654
655 write_seqcount_end(&timekeeper_seq);
656 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
657
658 return 0;
659}
660
661/**
662 * timekeeping_notify - Install a new clock source
663 * @clock: pointer to the clock source
664 *
665 * This function is called from clocksource.c after a new, better clock
666 * source has been registered. The caller holds the clocksource_mutex.
667 */
668int timekeeping_notify(struct clocksource *clock)
669{
670 struct timekeeper *tk = &timekeeper;
671
672 if (tk->clock == clock)
673 return 0;
674 stop_machine(change_clocksource, clock, NULL);
675 tick_clock_notify();
676 return tk->clock == clock ? 0 : -1;
677}
678
679/**
680 * ktime_get_real - get the real (wall-) time in ktime_t format
681 *
682 * returns the time in ktime_t format
683 */
684ktime_t ktime_get_real(void)
685{
686 struct timespec now;
687
688 getnstimeofday(&now);
689
690 return timespec_to_ktime(now);
691}
692EXPORT_SYMBOL_GPL(ktime_get_real);
693
694/**
695 * getrawmonotonic - Returns the raw monotonic time in a timespec
696 * @ts: pointer to the timespec to be set
697 *
698 * Returns the raw monotonic time (completely un-modified by ntp)
699 */
700void getrawmonotonic(struct timespec *ts)
701{
702 struct timekeeper *tk = &timekeeper;
703 unsigned long seq;
704 s64 nsecs;
705
706 do {
707 seq = read_seqcount_begin(&timekeeper_seq);
708 nsecs = timekeeping_get_ns_raw(tk);
709 *ts = tk->raw_time;
710
711 } while (read_seqcount_retry(&timekeeper_seq, seq));
712
713 timespec_add_ns(ts, nsecs);
714}
715EXPORT_SYMBOL(getrawmonotonic);
716
717/**
718 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
719 */
720int timekeeping_valid_for_hres(void)
721{
722 struct timekeeper *tk = &timekeeper;
723 unsigned long seq;
724 int ret;
725
726 do {
727 seq = read_seqcount_begin(&timekeeper_seq);
728
729 ret = tk->clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
730
731 } while (read_seqcount_retry(&timekeeper_seq, seq));
732
733 return ret;
734}
735
736/**
737 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
738 */
739u64 timekeeping_max_deferment(void)
740{
741 struct timekeeper *tk = &timekeeper;
742 unsigned long seq;
743 u64 ret;
744
745 do {
746 seq = read_seqcount_begin(&timekeeper_seq);
747
748 ret = tk->clock->max_idle_ns;
749
750 } while (read_seqcount_retry(&timekeeper_seq, seq));
751
752 return ret;
753}
754
755/**
756 * read_persistent_clock - Return time from the persistent clock.
757 *
758 * Weak dummy function for arches that do not yet support it.
759 * Reads the time from the battery backed persistent clock.
760 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
761 *
762 * XXX - Do be sure to remove it once all arches implement it.
763 */
764void __weak read_persistent_clock(struct timespec *ts)
765{
766 ts->tv_sec = 0;
767 ts->tv_nsec = 0;
768}
769
770/**
771 * read_boot_clock - Return time of the system start.
772 *
773 * Weak dummy function for arches that do not yet support it.
774 * Function to read the exact time the system has been started.
775 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
776 *
777 * XXX - Do be sure to remove it once all arches implement it.
778 */
779void __weak read_boot_clock(struct timespec *ts)
780{
781 ts->tv_sec = 0;
782 ts->tv_nsec = 0;
783}
784
785/*
786 * timekeeping_init - Initializes the clocksource and common timekeeping values
787 */
788void __init timekeeping_init(void)
789{
790 struct timekeeper *tk = &timekeeper;
791 struct clocksource *clock;
792 unsigned long flags;
793 struct timespec now, boot, tmp;
794
795 read_persistent_clock(&now);
796
797 if (!timespec_valid_strict(&now)) {
798 pr_warn("WARNING: Persistent clock returned invalid value!\n"
799 " Check your CMOS/BIOS settings.\n");
800 now.tv_sec = 0;
801 now.tv_nsec = 0;
802 } else if (now.tv_sec || now.tv_nsec)
803 persistent_clock_exist = true;
804
805 read_boot_clock(&boot);
806 if (!timespec_valid_strict(&boot)) {
807 pr_warn("WARNING: Boot clock returned invalid value!\n"
808 " Check your CMOS/BIOS settings.\n");
809 boot.tv_sec = 0;
810 boot.tv_nsec = 0;
811 }
812
813 raw_spin_lock_irqsave(&timekeeper_lock, flags);
814 write_seqcount_begin(&timekeeper_seq);
815 ntp_init();
816
817 clock = clocksource_default_clock();
818 if (clock->enable)
819 clock->enable(clock);
820 tk_setup_internals(tk, clock);
821
822 tk_set_xtime(tk, &now);
823 tk->raw_time.tv_sec = 0;
824 tk->raw_time.tv_nsec = 0;
825 if (boot.tv_sec == 0 && boot.tv_nsec == 0)
826 boot = tk_xtime(tk);
827
828 set_normalized_timespec(&tmp, -boot.tv_sec, -boot.tv_nsec);
829 tk_set_wall_to_mono(tk, tmp);
830
831 tmp.tv_sec = 0;
832 tmp.tv_nsec = 0;
833 tk_set_sleep_time(tk, tmp);
834
835 memcpy(&shadow_timekeeper, &timekeeper, sizeof(timekeeper));
836
837 write_seqcount_end(&timekeeper_seq);
838 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
839}
840
841/* time in seconds when suspend began */
842static struct timespec timekeeping_suspend_time;
843
844/**
845 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
846 * @delta: pointer to a timespec delta value
847 *
848 * Takes a timespec offset measuring a suspend interval and properly
849 * adds the sleep offset to the timekeeping variables.
850 */
851static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
852 struct timespec *delta)
853{
854 if (!timespec_valid_strict(delta)) {
855 printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
856 "sleep delta value!\n");
857 return;
858 }
859 tk_xtime_add(tk, delta);
860 tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *delta));
861 tk_set_sleep_time(tk, timespec_add(tk->total_sleep_time, *delta));
862 tk_debug_account_sleep_time(delta);
863}
864
865/**
866 * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
867 * @delta: pointer to a timespec delta value
868 *
869 * This hook is for architectures that cannot support read_persistent_clock
870 * because their RTC/persistent clock is only accessible when irqs are enabled.
871 *
872 * This function should only be called by rtc_resume(), and allows
873 * a suspend offset to be injected into the timekeeping values.
874 */
875void timekeeping_inject_sleeptime(struct timespec *delta)
876{
877 struct timekeeper *tk = &timekeeper;
878 unsigned long flags;
879
880 /*
881 * Make sure we don't set the clock twice, as timekeeping_resume()
882 * already did it
883 */
884 if (has_persistent_clock())
885 return;
886
887 raw_spin_lock_irqsave(&timekeeper_lock, flags);
888 write_seqcount_begin(&timekeeper_seq);
889
890 timekeeping_forward_now(tk);
891
892 __timekeeping_inject_sleeptime(tk, delta);
893
894 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
895
896 write_seqcount_end(&timekeeper_seq);
897 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
898
899 /* signal hrtimers about time change */
900 clock_was_set();
901}
902
903/**
904 * timekeeping_resume - Resumes the generic timekeeping subsystem.
905 *
906 * This is for the generic clocksource timekeeping.
907 * xtime/wall_to_monotonic/jiffies/etc are
908 * still managed by arch specific suspend/resume code.
909 */
910static void timekeeping_resume(void)
911{
912 struct timekeeper *tk = &timekeeper;
913 struct clocksource *clock = tk->clock;
914 unsigned long flags;
915 struct timespec ts_new, ts_delta;
916 cycle_t cycle_now, cycle_delta;
917 bool suspendtime_found = false;
918
919 read_persistent_clock(&ts_new);
920
921 clockevents_resume();
922 clocksource_resume();
923
924 raw_spin_lock_irqsave(&timekeeper_lock, flags);
925 write_seqcount_begin(&timekeeper_seq);
926
927 /*
928 * After system resumes, we need to calculate the suspended time and
929 * compensate it for the OS time. There are 3 sources that could be
930 * used: Nonstop clocksource during suspend, persistent clock and rtc
931 * device.
932 *
933 * One specific platform may have 1 or 2 or all of them, and the
934 * preference will be:
935 * suspend-nonstop clocksource -> persistent clock -> rtc
936 * The less preferred source will only be tried if there is no better
937 * usable source. The rtc part is handled separately in rtc core code.
938 */
939 cycle_now = clock->read(clock);
940 if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) &&
941 cycle_now > clock->cycle_last) {
942 u64 num, max = ULLONG_MAX;
943 u32 mult = clock->mult;
944 u32 shift = clock->shift;
945 s64 nsec = 0;
946
947 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
948
949 /*
950 * "cycle_delta * mutl" may cause 64 bits overflow, if the
951 * suspended time is too long. In that case we need do the
952 * 64 bits math carefully
953 */
954 do_div(max, mult);
955 if (cycle_delta > max) {
956 num = div64_u64(cycle_delta, max);
957 nsec = (((u64) max * mult) >> shift) * num;
958 cycle_delta -= num * max;
959 }
960 nsec += ((u64) cycle_delta * mult) >> shift;
961
962 ts_delta = ns_to_timespec(nsec);
963 suspendtime_found = true;
964 } else if (timespec_compare(&ts_new, &timekeeping_suspend_time) > 0) {
965 ts_delta = timespec_sub(ts_new, timekeeping_suspend_time);
966 suspendtime_found = true;
967 }
968
969 if (suspendtime_found)
970 __timekeeping_inject_sleeptime(tk, &ts_delta);
971
972 /* Re-base the last cycle value */
973 tk->cycle_last = clock->cycle_last = cycle_now;
974 tk->ntp_error = 0;
975 timekeeping_suspended = 0;
976 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
977 write_seqcount_end(&timekeeper_seq);
978 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
979
980 touch_softlockup_watchdog();
981
982 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
983
984 /* Resume hrtimers */
985 hrtimers_resume();
986}
987
988static int timekeeping_suspend(void)
989{
990 struct timekeeper *tk = &timekeeper;
991 unsigned long flags;
992 struct timespec delta, delta_delta;
993 static struct timespec old_delta;
994
995 read_persistent_clock(&timekeeping_suspend_time);
996
997 /*
998 * On some systems the persistent_clock can not be detected at
999 * timekeeping_init by its return value, so if we see a valid
1000 * value returned, update the persistent_clock_exists flag.
1001 */
1002 if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1003 persistent_clock_exist = true;
1004
1005 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1006 write_seqcount_begin(&timekeeper_seq);
1007 timekeeping_forward_now(tk);
1008 timekeeping_suspended = 1;
1009
1010 /*
1011 * To avoid drift caused by repeated suspend/resumes,
1012 * which each can add ~1 second drift error,
1013 * try to compensate so the difference in system time
1014 * and persistent_clock time stays close to constant.
1015 */
1016 delta = timespec_sub(tk_xtime(tk), timekeeping_suspend_time);
1017 delta_delta = timespec_sub(delta, old_delta);
1018 if (abs(delta_delta.tv_sec) >= 2) {
1019 /*
1020 * if delta_delta is too large, assume time correction
1021 * has occured and set old_delta to the current delta.
1022 */
1023 old_delta = delta;
1024 } else {
1025 /* Otherwise try to adjust old_system to compensate */
1026 timekeeping_suspend_time =
1027 timespec_add(timekeeping_suspend_time, delta_delta);
1028 }
1029
1030 timekeeping_update(tk, TK_MIRROR);
1031 write_seqcount_end(&timekeeper_seq);
1032 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1033
1034 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
1035 clocksource_suspend();
1036 clockevents_suspend();
1037
1038 return 0;
1039}
1040
1041/* sysfs resume/suspend bits for timekeeping */
1042static struct syscore_ops timekeeping_syscore_ops = {
1043 .resume = timekeeping_resume,
1044 .suspend = timekeeping_suspend,
1045};
1046
1047static int __init timekeeping_init_ops(void)
1048{
1049 register_syscore_ops(&timekeeping_syscore_ops);
1050 return 0;
1051}
1052
1053device_initcall(timekeeping_init_ops);
1054
1055/*
1056 * If the error is already larger, we look ahead even further
1057 * to compensate for late or lost adjustments.
1058 */
1059static __always_inline int timekeeping_bigadjust(struct timekeeper *tk,
1060 s64 error, s64 *interval,
1061 s64 *offset)
1062{
1063 s64 tick_error, i;
1064 u32 look_ahead, adj;
1065 s32 error2, mult;
1066
1067 /*
1068 * Use the current error value to determine how much to look ahead.
1069 * The larger the error the slower we adjust for it to avoid problems
1070 * with losing too many ticks, otherwise we would overadjust and
1071 * produce an even larger error. The smaller the adjustment the
1072 * faster we try to adjust for it, as lost ticks can do less harm
1073 * here. This is tuned so that an error of about 1 msec is adjusted
1074 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
1075 */
1076 error2 = tk->ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
1077 error2 = abs(error2);
1078 for (look_ahead = 0; error2 > 0; look_ahead++)
1079 error2 >>= 2;
1080
1081 /*
1082 * Now calculate the error in (1 << look_ahead) ticks, but first
1083 * remove the single look ahead already included in the error.
1084 */
1085 tick_error = ntp_tick_length() >> (tk->ntp_error_shift + 1);
1086 tick_error -= tk->xtime_interval >> 1;
1087 error = ((error - tick_error) >> look_ahead) + tick_error;
1088
1089 /* Finally calculate the adjustment shift value. */
1090 i = *interval;
1091 mult = 1;
1092 if (error < 0) {
1093 error = -error;
1094 *interval = -*interval;
1095 *offset = -*offset;
1096 mult = -1;
1097 }
1098 for (adj = 0; error > i; adj++)
1099 error >>= 1;
1100
1101 *interval <<= adj;
1102 *offset <<= adj;
1103 return mult << adj;
1104}
1105
1106/*
1107 * Adjust the multiplier to reduce the error value,
1108 * this is optimized for the most common adjustments of -1,0,1,
1109 * for other values we can do a bit more work.
1110 */
1111static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1112{
1113 s64 error, interval = tk->cycle_interval;
1114 int adj;
1115
1116 /*
1117 * The point of this is to check if the error is greater than half
1118 * an interval.
1119 *
1120 * First we shift it down from NTP_SHIFT to clocksource->shifted nsecs.
1121 *
1122 * Note we subtract one in the shift, so that error is really error*2.
1123 * This "saves" dividing(shifting) interval twice, but keeps the
1124 * (error > interval) comparison as still measuring if error is
1125 * larger than half an interval.
1126 *
1127 * Note: It does not "save" on aggravation when reading the code.
1128 */
1129 error = tk->ntp_error >> (tk->ntp_error_shift - 1);
1130 if (error > interval) {
1131 /*
1132 * We now divide error by 4(via shift), which checks if
1133 * the error is greater than twice the interval.
1134 * If it is greater, we need a bigadjust, if its smaller,
1135 * we can adjust by 1.
1136 */
1137 error >>= 2;
1138 if (likely(error <= interval))
1139 adj = 1;
1140 else
1141 adj = timekeeping_bigadjust(tk, error, &interval, &offset);
1142 } else {
1143 if (error < -interval) {
1144 /* See comment above, this is just switched for the negative */
1145 error >>= 2;
1146 if (likely(error >= -interval)) {
1147 adj = -1;
1148 interval = -interval;
1149 offset = -offset;
1150 } else {
1151 adj = timekeeping_bigadjust(tk, error, &interval, &offset);
1152 }
1153 } else {
1154 goto out_adjust;
1155 }
1156 }
1157
1158 if (unlikely(tk->clock->maxadj &&
1159 (tk->mult + adj > tk->clock->mult + tk->clock->maxadj))) {
1160 printk_once(KERN_WARNING
1161 "Adjusting %s more than 11%% (%ld vs %ld)\n",
1162 tk->clock->name, (long)tk->mult + adj,
1163 (long)tk->clock->mult + tk->clock->maxadj);
1164 }
1165 /*
1166 * So the following can be confusing.
1167 *
1168 * To keep things simple, lets assume adj == 1 for now.
1169 *
1170 * When adj != 1, remember that the interval and offset values
1171 * have been appropriately scaled so the math is the same.
1172 *
1173 * The basic idea here is that we're increasing the multiplier
1174 * by one, this causes the xtime_interval to be incremented by
1175 * one cycle_interval. This is because:
1176 * xtime_interval = cycle_interval * mult
1177 * So if mult is being incremented by one:
1178 * xtime_interval = cycle_interval * (mult + 1)
1179 * Its the same as:
1180 * xtime_interval = (cycle_interval * mult) + cycle_interval
1181 * Which can be shortened to:
1182 * xtime_interval += cycle_interval
1183 *
1184 * So offset stores the non-accumulated cycles. Thus the current
1185 * time (in shifted nanoseconds) is:
1186 * now = (offset * adj) + xtime_nsec
1187 * Now, even though we're adjusting the clock frequency, we have
1188 * to keep time consistent. In other words, we can't jump back
1189 * in time, and we also want to avoid jumping forward in time.
1190 *
1191 * So given the same offset value, we need the time to be the same
1192 * both before and after the freq adjustment.
1193 * now = (offset * adj_1) + xtime_nsec_1
1194 * now = (offset * adj_2) + xtime_nsec_2
1195 * So:
1196 * (offset * adj_1) + xtime_nsec_1 =
1197 * (offset * adj_2) + xtime_nsec_2
1198 * And we know:
1199 * adj_2 = adj_1 + 1
1200 * So:
1201 * (offset * adj_1) + xtime_nsec_1 =
1202 * (offset * (adj_1+1)) + xtime_nsec_2
1203 * (offset * adj_1) + xtime_nsec_1 =
1204 * (offset * adj_1) + offset + xtime_nsec_2
1205 * Canceling the sides:
1206 * xtime_nsec_1 = offset + xtime_nsec_2
1207 * Which gives us:
1208 * xtime_nsec_2 = xtime_nsec_1 - offset
1209 * Which simplfies to:
1210 * xtime_nsec -= offset
1211 *
1212 * XXX - TODO: Doc ntp_error calculation.
1213 */
1214 tk->mult += adj;
1215 tk->xtime_interval += interval;
1216 tk->xtime_nsec -= offset;
1217 tk->ntp_error -= (interval - offset) << tk->ntp_error_shift;
1218
1219out_adjust:
1220 /*
1221 * It may be possible that when we entered this function, xtime_nsec
1222 * was very small. Further, if we're slightly speeding the clocksource
1223 * in the code above, its possible the required corrective factor to
1224 * xtime_nsec could cause it to underflow.
1225 *
1226 * Now, since we already accumulated the second, cannot simply roll
1227 * the accumulated second back, since the NTP subsystem has been
1228 * notified via second_overflow. So instead we push xtime_nsec forward
1229 * by the amount we underflowed, and add that amount into the error.
1230 *
1231 * We'll correct this error next time through this function, when
1232 * xtime_nsec is not as small.
1233 */
1234 if (unlikely((s64)tk->xtime_nsec < 0)) {
1235 s64 neg = -(s64)tk->xtime_nsec;
1236 tk->xtime_nsec = 0;
1237 tk->ntp_error += neg << tk->ntp_error_shift;
1238 }
1239
1240}
1241
1242/**
1243 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1244 *
1245 * Helper function that accumulates a the nsecs greater then a second
1246 * from the xtime_nsec field to the xtime_secs field.
1247 * It also calls into the NTP code to handle leapsecond processing.
1248 *
1249 */
1250static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
1251{
1252 u64 nsecps = (u64)NSEC_PER_SEC << tk->shift;
1253 unsigned int clock_set = 0;
1254
1255 while (tk->xtime_nsec >= nsecps) {
1256 int leap;
1257
1258 tk->xtime_nsec -= nsecps;
1259 tk->xtime_sec++;
1260
1261 /* Figure out if its a leap sec and apply if needed */
1262 leap = second_overflow(tk->xtime_sec);
1263 if (unlikely(leap)) {
1264 struct timespec ts;
1265
1266 tk->xtime_sec += leap;
1267
1268 ts.tv_sec = leap;
1269 ts.tv_nsec = 0;
1270 tk_set_wall_to_mono(tk,
1271 timespec_sub(tk->wall_to_monotonic, ts));
1272
1273 __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
1274
1275 clock_set = TK_CLOCK_WAS_SET;
1276 }
1277 }
1278 return clock_set;
1279}
1280
1281/**
1282 * logarithmic_accumulation - shifted accumulation of cycles
1283 *
1284 * This functions accumulates a shifted interval of cycles into
1285 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1286 * loop.
1287 *
1288 * Returns the unconsumed cycles.
1289 */
1290static cycle_t logarithmic_accumulation(struct timekeeper *tk, cycle_t offset,
1291 u32 shift,
1292 unsigned int *clock_set)
1293{
1294 cycle_t interval = tk->cycle_interval << shift;
1295 u64 raw_nsecs;
1296
1297 /* If the offset is smaller then a shifted interval, do nothing */
1298 if (offset < interval)
1299 return offset;
1300
1301 /* Accumulate one shifted interval */
1302 offset -= interval;
1303 tk->cycle_last += interval;
1304
1305 tk->xtime_nsec += tk->xtime_interval << shift;
1306 *clock_set |= accumulate_nsecs_to_secs(tk);
1307
1308 /* Accumulate raw time */
1309 raw_nsecs = (u64)tk->raw_interval << shift;
1310 raw_nsecs += tk->raw_time.tv_nsec;
1311 if (raw_nsecs >= NSEC_PER_SEC) {
1312 u64 raw_secs = raw_nsecs;
1313 raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
1314 tk->raw_time.tv_sec += raw_secs;
1315 }
1316 tk->raw_time.tv_nsec = raw_nsecs;
1317
1318 /* Accumulate error between NTP and clock interval */
1319 tk->ntp_error += ntp_tick_length() << shift;
1320 tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
1321 (tk->ntp_error_shift + shift);
1322
1323 return offset;
1324}
1325
1326#ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
1327static inline void old_vsyscall_fixup(struct timekeeper *tk)
1328{
1329 s64 remainder;
1330
1331 /*
1332 * Store only full nanoseconds into xtime_nsec after rounding
1333 * it up and add the remainder to the error difference.
1334 * XXX - This is necessary to avoid small 1ns inconsistnecies caused
1335 * by truncating the remainder in vsyscalls. However, it causes
1336 * additional work to be done in timekeeping_adjust(). Once
1337 * the vsyscall implementations are converted to use xtime_nsec
1338 * (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
1339 * users are removed, this can be killed.
1340 */
1341 remainder = tk->xtime_nsec & ((1ULL << tk->shift) - 1);
1342 tk->xtime_nsec -= remainder;
1343 tk->xtime_nsec += 1ULL << tk->shift;
1344 tk->ntp_error += remainder << tk->ntp_error_shift;
1345 tk->ntp_error -= (1ULL << tk->shift) << tk->ntp_error_shift;
1346}
1347#else
1348#define old_vsyscall_fixup(tk)
1349#endif
1350
1351
1352
1353/**
1354 * update_wall_time - Uses the current clocksource to increment the wall time
1355 *
1356 */
1357void update_wall_time(void)
1358{
1359 struct clocksource *clock;
1360 struct timekeeper *real_tk = &timekeeper;
1361 struct timekeeper *tk = &shadow_timekeeper;
1362 cycle_t offset;
1363 int shift = 0, maxshift;
1364 unsigned int clock_set = 0;
1365 unsigned long flags;
1366
1367 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1368
1369 /* Make sure we're fully resumed: */
1370 if (unlikely(timekeeping_suspended))
1371 goto out;
1372
1373 clock = real_tk->clock;
1374
1375#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1376 offset = real_tk->cycle_interval;
1377#else
1378 offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
1379#endif
1380
1381 /* Check if there's really nothing to do */
1382 if (offset < real_tk->cycle_interval)
1383 goto out;
1384
1385 /*
1386 * With NO_HZ we may have to accumulate many cycle_intervals
1387 * (think "ticks") worth of time at once. To do this efficiently,
1388 * we calculate the largest doubling multiple of cycle_intervals
1389 * that is smaller than the offset. We then accumulate that
1390 * chunk in one go, and then try to consume the next smaller
1391 * doubled multiple.
1392 */
1393 shift = ilog2(offset) - ilog2(tk->cycle_interval);
1394 shift = max(0, shift);
1395 /* Bound shift to one less than what overflows tick_length */
1396 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
1397 shift = min(shift, maxshift);
1398 while (offset >= tk->cycle_interval) {
1399 offset = logarithmic_accumulation(tk, offset, shift,
1400 &clock_set);
1401 if (offset < tk->cycle_interval<<shift)
1402 shift--;
1403 }
1404
1405 /* correct the clock when NTP error is too big */
1406 timekeeping_adjust(tk, offset);
1407
1408 /*
1409 * XXX This can be killed once everyone converts
1410 * to the new update_vsyscall.
1411 */
1412 old_vsyscall_fixup(tk);
1413
1414 /*
1415 * Finally, make sure that after the rounding
1416 * xtime_nsec isn't larger than NSEC_PER_SEC
1417 */
1418 clock_set |= accumulate_nsecs_to_secs(tk);
1419
1420 write_seqcount_begin(&timekeeper_seq);
1421 /* Update clock->cycle_last with the new value */
1422 clock->cycle_last = tk->cycle_last;
1423 /*
1424 * Update the real timekeeper.
1425 *
1426 * We could avoid this memcpy by switching pointers, but that
1427 * requires changes to all other timekeeper usage sites as
1428 * well, i.e. move the timekeeper pointer getter into the
1429 * spinlocked/seqcount protected sections. And we trade this
1430 * memcpy under the timekeeper_seq against one before we start
1431 * updating.
1432 */
1433 memcpy(real_tk, tk, sizeof(*tk));
1434 timekeeping_update(real_tk, clock_set);
1435 write_seqcount_end(&timekeeper_seq);
1436out:
1437 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1438 if (clock_set)
1439 /* Have to call _delayed version, since in irq context*/
1440 clock_was_set_delayed();
1441}
1442
1443/**
1444 * getboottime - Return the real time of system boot.
1445 * @ts: pointer to the timespec to be set
1446 *
1447 * Returns the wall-time of boot in a timespec.
1448 *
1449 * This is based on the wall_to_monotonic offset and the total suspend
1450 * time. Calls to settimeofday will affect the value returned (which
1451 * basically means that however wrong your real time clock is at boot time,
1452 * you get the right time here).
1453 */
1454void getboottime(struct timespec *ts)
1455{
1456 struct timekeeper *tk = &timekeeper;
1457 struct timespec boottime = {
1458 .tv_sec = tk->wall_to_monotonic.tv_sec +
1459 tk->total_sleep_time.tv_sec,
1460 .tv_nsec = tk->wall_to_monotonic.tv_nsec +
1461 tk->total_sleep_time.tv_nsec
1462 };
1463
1464 set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
1465}
1466EXPORT_SYMBOL_GPL(getboottime);
1467
1468/**
1469 * get_monotonic_boottime - Returns monotonic time since boot
1470 * @ts: pointer to the timespec to be set
1471 *
1472 * Returns the monotonic time since boot in a timespec.
1473 *
1474 * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
1475 * includes the time spent in suspend.
1476 */
1477void get_monotonic_boottime(struct timespec *ts)
1478{
1479 struct timekeeper *tk = &timekeeper;
1480 struct timespec tomono, sleep;
1481 s64 nsec;
1482 unsigned int seq;
1483
1484 WARN_ON(timekeeping_suspended);
1485
1486 do {
1487 seq = read_seqcount_begin(&timekeeper_seq);
1488 ts->tv_sec = tk->xtime_sec;
1489 nsec = timekeeping_get_ns(tk);
1490 tomono = tk->wall_to_monotonic;
1491 sleep = tk->total_sleep_time;
1492
1493 } while (read_seqcount_retry(&timekeeper_seq, seq));
1494
1495 ts->tv_sec += tomono.tv_sec + sleep.tv_sec;
1496 ts->tv_nsec = 0;
1497 timespec_add_ns(ts, nsec + tomono.tv_nsec + sleep.tv_nsec);
1498}
1499EXPORT_SYMBOL_GPL(get_monotonic_boottime);
1500
1501/**
1502 * ktime_get_boottime - Returns monotonic time since boot in a ktime
1503 *
1504 * Returns the monotonic time since boot in a ktime
1505 *
1506 * This is similar to CLOCK_MONTONIC/ktime_get, but also
1507 * includes the time spent in suspend.
1508 */
1509ktime_t ktime_get_boottime(void)
1510{
1511 struct timespec ts;
1512
1513 get_monotonic_boottime(&ts);
1514 return timespec_to_ktime(ts);
1515}
1516EXPORT_SYMBOL_GPL(ktime_get_boottime);
1517
1518/**
1519 * monotonic_to_bootbased - Convert the monotonic time to boot based.
1520 * @ts: pointer to the timespec to be converted
1521 */
1522void monotonic_to_bootbased(struct timespec *ts)
1523{
1524 struct timekeeper *tk = &timekeeper;
1525
1526 *ts = timespec_add(*ts, tk->total_sleep_time);
1527}
1528EXPORT_SYMBOL_GPL(monotonic_to_bootbased);
1529
1530unsigned long get_seconds(void)
1531{
1532 struct timekeeper *tk = &timekeeper;
1533
1534 return tk->xtime_sec;
1535}
1536EXPORT_SYMBOL(get_seconds);
1537
1538struct timespec __current_kernel_time(void)
1539{
1540 struct timekeeper *tk = &timekeeper;
1541
1542 return tk_xtime(tk);
1543}
1544
1545struct timespec current_kernel_time(void)
1546{
1547 struct timekeeper *tk = &timekeeper;
1548 struct timespec now;
1549 unsigned long seq;
1550
1551 do {
1552 seq = read_seqcount_begin(&timekeeper_seq);
1553
1554 now = tk_xtime(tk);
1555 } while (read_seqcount_retry(&timekeeper_seq, seq));
1556
1557 return now;
1558}
1559EXPORT_SYMBOL(current_kernel_time);
1560
1561struct timespec get_monotonic_coarse(void)
1562{
1563 struct timekeeper *tk = &timekeeper;
1564 struct timespec now, mono;
1565 unsigned long seq;
1566
1567 do {
1568 seq = read_seqcount_begin(&timekeeper_seq);
1569
1570 now = tk_xtime(tk);
1571 mono = tk->wall_to_monotonic;
1572 } while (read_seqcount_retry(&timekeeper_seq, seq));
1573
1574 set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
1575 now.tv_nsec + mono.tv_nsec);
1576 return now;
1577}
1578
1579/*
1580 * Must hold jiffies_lock
1581 */
1582void do_timer(unsigned long ticks)
1583{
1584 jiffies_64 += ticks;
1585 calc_global_load(ticks);
1586}
1587
1588/**
1589 * get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic,
1590 * and sleep offsets.
1591 * @xtim: pointer to timespec to be set with xtime
1592 * @wtom: pointer to timespec to be set with wall_to_monotonic
1593 * @sleep: pointer to timespec to be set with time in suspend
1594 */
1595void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
1596 struct timespec *wtom, struct timespec *sleep)
1597{
1598 struct timekeeper *tk = &timekeeper;
1599 unsigned long seq;
1600
1601 do {
1602 seq = read_seqcount_begin(&timekeeper_seq);
1603 *xtim = tk_xtime(tk);
1604 *wtom = tk->wall_to_monotonic;
1605 *sleep = tk->total_sleep_time;
1606 } while (read_seqcount_retry(&timekeeper_seq, seq));
1607}
1608
1609#ifdef CONFIG_HIGH_RES_TIMERS
1610/**
1611 * ktime_get_update_offsets - hrtimer helper
1612 * @offs_real: pointer to storage for monotonic -> realtime offset
1613 * @offs_boot: pointer to storage for monotonic -> boottime offset
1614 * @offs_tai: pointer to storage for monotonic -> clock tai offset
1615 *
1616 * Returns current monotonic time and updates the offsets
1617 * Called from hrtimer_interrupt() or retrigger_next_event()
1618 */
1619ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot,
1620 ktime_t *offs_tai)
1621{
1622 struct timekeeper *tk = &timekeeper;
1623 ktime_t now;
1624 unsigned int seq;
1625 u64 secs, nsecs;
1626
1627 do {
1628 seq = read_seqcount_begin(&timekeeper_seq);
1629
1630 secs = tk->xtime_sec;
1631 nsecs = timekeeping_get_ns(tk);
1632
1633 *offs_real = tk->offs_real;
1634 *offs_boot = tk->offs_boot;
1635 *offs_tai = tk->offs_tai;
1636 } while (read_seqcount_retry(&timekeeper_seq, seq));
1637
1638 now = ktime_add_ns(ktime_set(secs, 0), nsecs);
1639 now = ktime_sub(now, *offs_real);
1640 return now;
1641}
1642#endif
1643
1644/**
1645 * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
1646 */
1647ktime_t ktime_get_monotonic_offset(void)
1648{
1649 struct timekeeper *tk = &timekeeper;
1650 unsigned long seq;
1651 struct timespec wtom;
1652
1653 do {
1654 seq = read_seqcount_begin(&timekeeper_seq);
1655 wtom = tk->wall_to_monotonic;
1656 } while (read_seqcount_retry(&timekeeper_seq, seq));
1657
1658 return timespec_to_ktime(wtom);
1659}
1660EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset);
1661
1662/**
1663 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
1664 */
1665int do_adjtimex(struct timex *txc)
1666{
1667 struct timekeeper *tk = &timekeeper;
1668 unsigned long flags;
1669 struct timespec ts;
1670 s32 orig_tai, tai;
1671 int ret;
1672
1673 /* Validate the data before disabling interrupts */
1674 ret = ntp_validate_timex(txc);
1675 if (ret)
1676 return ret;
1677
1678 if (txc->modes & ADJ_SETOFFSET) {
1679 struct timespec delta;
1680 delta.tv_sec = txc->time.tv_sec;
1681 delta.tv_nsec = txc->time.tv_usec;
1682 if (!(txc->modes & ADJ_NANO))
1683 delta.tv_nsec *= 1000;
1684 ret = timekeeping_inject_offset(&delta);
1685 if (ret)
1686 return ret;
1687 }
1688
1689 getnstimeofday(&ts);
1690
1691 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1692 write_seqcount_begin(&timekeeper_seq);
1693
1694 orig_tai = tai = tk->tai_offset;
1695 ret = __do_adjtimex(txc, &ts, &tai);
1696
1697 if (tai != orig_tai) {
1698 __timekeeping_set_tai_offset(tk, tai);
1699 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1700 }
1701 write_seqcount_end(&timekeeper_seq);
1702 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1703
1704 if (tai != orig_tai)
1705 clock_was_set();
1706
1707 ntp_notify_cmos_timer();
1708
1709 return ret;
1710}
1711
1712#ifdef CONFIG_NTP_PPS
1713/**
1714 * hardpps() - Accessor function to NTP __hardpps function
1715 */
1716void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts)
1717{
1718 unsigned long flags;
1719
1720 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1721 write_seqcount_begin(&timekeeper_seq);
1722
1723 __hardpps(phase_ts, raw_ts);
1724
1725 write_seqcount_end(&timekeeper_seq);
1726 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1727}
1728EXPORT_SYMBOL(hardpps);
1729#endif
1730
1731/**
1732 * xtime_update() - advances the timekeeping infrastructure
1733 * @ticks: number of ticks, that have elapsed since the last call.
1734 *
1735 * Must be called with interrupts disabled.
1736 */
1737void xtime_update(unsigned long ticks)
1738{
1739 write_seqlock(&jiffies_lock);
1740 do_timer(ticks);
1741 write_sequnlock(&jiffies_lock);
1742 update_wall_time();
1743}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Kernel timekeeping code and accessor functions. Based on code from
4 * timer.c, moved in commit 8524070b7982.
5 */
6#include <linux/timekeeper_internal.h>
7#include <linux/module.h>
8#include <linux/interrupt.h>
9#include <linux/percpu.h>
10#include <linux/init.h>
11#include <linux/mm.h>
12#include <linux/nmi.h>
13#include <linux/sched.h>
14#include <linux/sched/loadavg.h>
15#include <linux/sched/clock.h>
16#include <linux/syscore_ops.h>
17#include <linux/clocksource.h>
18#include <linux/jiffies.h>
19#include <linux/time.h>
20#include <linux/tick.h>
21#include <linux/stop_machine.h>
22#include <linux/pvclock_gtod.h>
23#include <linux/compiler.h>
24#include <linux/audit.h>
25
26#include "tick-internal.h"
27#include "ntp_internal.h"
28#include "timekeeping_internal.h"
29
30#define TK_CLEAR_NTP (1 << 0)
31#define TK_MIRROR (1 << 1)
32#define TK_CLOCK_WAS_SET (1 << 2)
33
34enum timekeeping_adv_mode {
35 /* Update timekeeper when a tick has passed */
36 TK_ADV_TICK,
37
38 /* Update timekeeper on a direct frequency change */
39 TK_ADV_FREQ
40};
41
42DEFINE_RAW_SPINLOCK(timekeeper_lock);
43
44/*
45 * The most important data for readout fits into a single 64 byte
46 * cache line.
47 */
48static struct {
49 seqcount_raw_spinlock_t seq;
50 struct timekeeper timekeeper;
51} tk_core ____cacheline_aligned = {
52 .seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_core.seq, &timekeeper_lock),
53};
54
55static struct timekeeper shadow_timekeeper;
56
57/**
58 * struct tk_fast - NMI safe timekeeper
59 * @seq: Sequence counter for protecting updates. The lowest bit
60 * is the index for the tk_read_base array
61 * @base: tk_read_base array. Access is indexed by the lowest bit of
62 * @seq.
63 *
64 * See @update_fast_timekeeper() below.
65 */
66struct tk_fast {
67 seqcount_raw_spinlock_t seq;
68 struct tk_read_base base[2];
69};
70
71/* Suspend-time cycles value for halted fast timekeeper. */
72static u64 cycles_at_suspend;
73
74static u64 dummy_clock_read(struct clocksource *cs)
75{
76 return cycles_at_suspend;
77}
78
79static struct clocksource dummy_clock = {
80 .read = dummy_clock_read,
81};
82
83static struct tk_fast tk_fast_mono ____cacheline_aligned = {
84 .seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_fast_mono.seq, &timekeeper_lock),
85 .base[0] = { .clock = &dummy_clock, },
86 .base[1] = { .clock = &dummy_clock, },
87};
88
89static struct tk_fast tk_fast_raw ____cacheline_aligned = {
90 .seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_fast_raw.seq, &timekeeper_lock),
91 .base[0] = { .clock = &dummy_clock, },
92 .base[1] = { .clock = &dummy_clock, },
93};
94
95/* flag for if timekeeping is suspended */
96int __read_mostly timekeeping_suspended;
97
98static inline void tk_normalize_xtime(struct timekeeper *tk)
99{
100 while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
101 tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
102 tk->xtime_sec++;
103 }
104 while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) {
105 tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
106 tk->raw_sec++;
107 }
108}
109
110static inline struct timespec64 tk_xtime(const struct timekeeper *tk)
111{
112 struct timespec64 ts;
113
114 ts.tv_sec = tk->xtime_sec;
115 ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
116 return ts;
117}
118
119static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
120{
121 tk->xtime_sec = ts->tv_sec;
122 tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
123}
124
125static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts)
126{
127 tk->xtime_sec += ts->tv_sec;
128 tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift;
129 tk_normalize_xtime(tk);
130}
131
132static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
133{
134 struct timespec64 tmp;
135
136 /*
137 * Verify consistency of: offset_real = -wall_to_monotonic
138 * before modifying anything
139 */
140 set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
141 -tk->wall_to_monotonic.tv_nsec);
142 WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp));
143 tk->wall_to_monotonic = wtm;
144 set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
145 tk->offs_real = timespec64_to_ktime(tmp);
146 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
147}
148
149static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
150{
151 tk->offs_boot = ktime_add(tk->offs_boot, delta);
152 /*
153 * Timespec representation for VDSO update to avoid 64bit division
154 * on every update.
155 */
156 tk->monotonic_to_boot = ktime_to_timespec64(tk->offs_boot);
157}
158
159/*
160 * tk_clock_read - atomic clocksource read() helper
161 *
162 * This helper is necessary to use in the read paths because, while the
163 * seqcount ensures we don't return a bad value while structures are updated,
164 * it doesn't protect from potential crashes. There is the possibility that
165 * the tkr's clocksource may change between the read reference, and the
166 * clock reference passed to the read function. This can cause crashes if
167 * the wrong clocksource is passed to the wrong read function.
168 * This isn't necessary to use when holding the timekeeper_lock or doing
169 * a read of the fast-timekeeper tkrs (which is protected by its own locking
170 * and update logic).
171 */
172static inline u64 tk_clock_read(const struct tk_read_base *tkr)
173{
174 struct clocksource *clock = READ_ONCE(tkr->clock);
175
176 return clock->read(clock);
177}
178
179#ifdef CONFIG_DEBUG_TIMEKEEPING
180#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
181
182static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
183{
184
185 u64 max_cycles = tk->tkr_mono.clock->max_cycles;
186 const char *name = tk->tkr_mono.clock->name;
187
188 if (offset > max_cycles) {
189 printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
190 offset, name, max_cycles);
191 printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
192 } else {
193 if (offset > (max_cycles >> 1)) {
194 printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
195 offset, name, max_cycles >> 1);
196 printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
197 }
198 }
199
200 if (tk->underflow_seen) {
201 if (jiffies - tk->last_warning > WARNING_FREQ) {
202 printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
203 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
204 printk_deferred(" Your kernel is probably still fine.\n");
205 tk->last_warning = jiffies;
206 }
207 tk->underflow_seen = 0;
208 }
209
210 if (tk->overflow_seen) {
211 if (jiffies - tk->last_warning > WARNING_FREQ) {
212 printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
213 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
214 printk_deferred(" Your kernel is probably still fine.\n");
215 tk->last_warning = jiffies;
216 }
217 tk->overflow_seen = 0;
218 }
219}
220
221static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
222{
223 struct timekeeper *tk = &tk_core.timekeeper;
224 u64 now, last, mask, max, delta;
225 unsigned int seq;
226
227 /*
228 * Since we're called holding a seqcount, the data may shift
229 * under us while we're doing the calculation. This can cause
230 * false positives, since we'd note a problem but throw the
231 * results away. So nest another seqcount here to atomically
232 * grab the points we are checking with.
233 */
234 do {
235 seq = read_seqcount_begin(&tk_core.seq);
236 now = tk_clock_read(tkr);
237 last = tkr->cycle_last;
238 mask = tkr->mask;
239 max = tkr->clock->max_cycles;
240 } while (read_seqcount_retry(&tk_core.seq, seq));
241
242 delta = clocksource_delta(now, last, mask);
243
244 /*
245 * Try to catch underflows by checking if we are seeing small
246 * mask-relative negative values.
247 */
248 if (unlikely((~delta & mask) < (mask >> 3))) {
249 tk->underflow_seen = 1;
250 delta = 0;
251 }
252
253 /* Cap delta value to the max_cycles values to avoid mult overflows */
254 if (unlikely(delta > max)) {
255 tk->overflow_seen = 1;
256 delta = tkr->clock->max_cycles;
257 }
258
259 return delta;
260}
261#else
262static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
263{
264}
265static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
266{
267 u64 cycle_now, delta;
268
269 /* read clocksource */
270 cycle_now = tk_clock_read(tkr);
271
272 /* calculate the delta since the last update_wall_time */
273 delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
274
275 return delta;
276}
277#endif
278
279/**
280 * tk_setup_internals - Set up internals to use clocksource clock.
281 *
282 * @tk: The target timekeeper to setup.
283 * @clock: Pointer to clocksource.
284 *
285 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
286 * pair and interval request.
287 *
288 * Unless you're the timekeeping code, you should not be using this!
289 */
290static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
291{
292 u64 interval;
293 u64 tmp, ntpinterval;
294 struct clocksource *old_clock;
295
296 ++tk->cs_was_changed_seq;
297 old_clock = tk->tkr_mono.clock;
298 tk->tkr_mono.clock = clock;
299 tk->tkr_mono.mask = clock->mask;
300 tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono);
301
302 tk->tkr_raw.clock = clock;
303 tk->tkr_raw.mask = clock->mask;
304 tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
305
306 /* Do the ns -> cycle conversion first, using original mult */
307 tmp = NTP_INTERVAL_LENGTH;
308 tmp <<= clock->shift;
309 ntpinterval = tmp;
310 tmp += clock->mult/2;
311 do_div(tmp, clock->mult);
312 if (tmp == 0)
313 tmp = 1;
314
315 interval = (u64) tmp;
316 tk->cycle_interval = interval;
317
318 /* Go back from cycles -> shifted ns */
319 tk->xtime_interval = interval * clock->mult;
320 tk->xtime_remainder = ntpinterval - tk->xtime_interval;
321 tk->raw_interval = interval * clock->mult;
322
323 /* if changing clocks, convert xtime_nsec shift units */
324 if (old_clock) {
325 int shift_change = clock->shift - old_clock->shift;
326 if (shift_change < 0) {
327 tk->tkr_mono.xtime_nsec >>= -shift_change;
328 tk->tkr_raw.xtime_nsec >>= -shift_change;
329 } else {
330 tk->tkr_mono.xtime_nsec <<= shift_change;
331 tk->tkr_raw.xtime_nsec <<= shift_change;
332 }
333 }
334
335 tk->tkr_mono.shift = clock->shift;
336 tk->tkr_raw.shift = clock->shift;
337
338 tk->ntp_error = 0;
339 tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
340 tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
341
342 /*
343 * The timekeeper keeps its own mult values for the currently
344 * active clocksource. These value will be adjusted via NTP
345 * to counteract clock drifting.
346 */
347 tk->tkr_mono.mult = clock->mult;
348 tk->tkr_raw.mult = clock->mult;
349 tk->ntp_err_mult = 0;
350 tk->skip_second_overflow = 0;
351}
352
353/* Timekeeper helper functions. */
354
355#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
356static u32 default_arch_gettimeoffset(void) { return 0; }
357u32 (*arch_gettimeoffset)(void) = default_arch_gettimeoffset;
358#else
359static inline u32 arch_gettimeoffset(void) { return 0; }
360#endif
361
362static inline u64 timekeeping_delta_to_ns(const struct tk_read_base *tkr, u64 delta)
363{
364 u64 nsec;
365
366 nsec = delta * tkr->mult + tkr->xtime_nsec;
367 nsec >>= tkr->shift;
368
369 /* If arch requires, add in get_arch_timeoffset() */
370 return nsec + arch_gettimeoffset();
371}
372
373static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr)
374{
375 u64 delta;
376
377 delta = timekeeping_get_delta(tkr);
378 return timekeeping_delta_to_ns(tkr, delta);
379}
380
381static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles)
382{
383 u64 delta;
384
385 /* calculate the delta since the last update_wall_time */
386 delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
387 return timekeeping_delta_to_ns(tkr, delta);
388}
389
390/**
391 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
392 * @tkr: Timekeeping readout base from which we take the update
393 *
394 * We want to use this from any context including NMI and tracing /
395 * instrumenting the timekeeping code itself.
396 *
397 * Employ the latch technique; see @raw_write_seqcount_latch.
398 *
399 * So if a NMI hits the update of base[0] then it will use base[1]
400 * which is still consistent. In the worst case this can result is a
401 * slightly wrong timestamp (a few nanoseconds). See
402 * @ktime_get_mono_fast_ns.
403 */
404static void update_fast_timekeeper(const struct tk_read_base *tkr,
405 struct tk_fast *tkf)
406{
407 struct tk_read_base *base = tkf->base;
408
409 /* Force readers off to base[1] */
410 raw_write_seqcount_latch(&tkf->seq);
411
412 /* Update base[0] */
413 memcpy(base, tkr, sizeof(*base));
414
415 /* Force readers back to base[0] */
416 raw_write_seqcount_latch(&tkf->seq);
417
418 /* Update base[1] */
419 memcpy(base + 1, base, sizeof(*base));
420}
421
422/**
423 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
424 *
425 * This timestamp is not guaranteed to be monotonic across an update.
426 * The timestamp is calculated by:
427 *
428 * now = base_mono + clock_delta * slope
429 *
430 * So if the update lowers the slope, readers who are forced to the
431 * not yet updated second array are still using the old steeper slope.
432 *
433 * tmono
434 * ^
435 * | o n
436 * | o n
437 * | u
438 * | o
439 * |o
440 * |12345678---> reader order
441 *
442 * o = old slope
443 * u = update
444 * n = new slope
445 *
446 * So reader 6 will observe time going backwards versus reader 5.
447 *
448 * While other CPUs are likely to be able observe that, the only way
449 * for a CPU local observation is when an NMI hits in the middle of
450 * the update. Timestamps taken from that NMI context might be ahead
451 * of the following timestamps. Callers need to be aware of that and
452 * deal with it.
453 */
454static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
455{
456 struct tk_read_base *tkr;
457 unsigned int seq;
458 u64 now;
459
460 do {
461 seq = raw_read_seqcount_latch(&tkf->seq);
462 tkr = tkf->base + (seq & 0x01);
463 now = ktime_to_ns(tkr->base);
464
465 now += timekeeping_delta_to_ns(tkr,
466 clocksource_delta(
467 tk_clock_read(tkr),
468 tkr->cycle_last,
469 tkr->mask));
470 } while (read_seqcount_retry(&tkf->seq, seq));
471
472 return now;
473}
474
475u64 ktime_get_mono_fast_ns(void)
476{
477 return __ktime_get_fast_ns(&tk_fast_mono);
478}
479EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
480
481u64 ktime_get_raw_fast_ns(void)
482{
483 return __ktime_get_fast_ns(&tk_fast_raw);
484}
485EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
486
487/**
488 * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
489 *
490 * To keep it NMI safe since we're accessing from tracing, we're not using a
491 * separate timekeeper with updates to monotonic clock and boot offset
492 * protected with seqcounts. This has the following minor side effects:
493 *
494 * (1) Its possible that a timestamp be taken after the boot offset is updated
495 * but before the timekeeper is updated. If this happens, the new boot offset
496 * is added to the old timekeeping making the clock appear to update slightly
497 * earlier:
498 * CPU 0 CPU 1
499 * timekeeping_inject_sleeptime64()
500 * __timekeeping_inject_sleeptime(tk, delta);
501 * timestamp();
502 * timekeeping_update(tk, TK_CLEAR_NTP...);
503 *
504 * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
505 * partially updated. Since the tk->offs_boot update is a rare event, this
506 * should be a rare occurrence which postprocessing should be able to handle.
507 */
508u64 notrace ktime_get_boot_fast_ns(void)
509{
510 struct timekeeper *tk = &tk_core.timekeeper;
511
512 return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot));
513}
514EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
515
516
517/*
518 * See comment for __ktime_get_fast_ns() vs. timestamp ordering
519 */
520static __always_inline u64 __ktime_get_real_fast_ns(struct tk_fast *tkf)
521{
522 struct tk_read_base *tkr;
523 unsigned int seq;
524 u64 now;
525
526 do {
527 seq = raw_read_seqcount_latch(&tkf->seq);
528 tkr = tkf->base + (seq & 0x01);
529 now = ktime_to_ns(tkr->base_real);
530
531 now += timekeeping_delta_to_ns(tkr,
532 clocksource_delta(
533 tk_clock_read(tkr),
534 tkr->cycle_last,
535 tkr->mask));
536 } while (read_seqcount_retry(&tkf->seq, seq));
537
538 return now;
539}
540
541/**
542 * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime.
543 */
544u64 ktime_get_real_fast_ns(void)
545{
546 return __ktime_get_real_fast_ns(&tk_fast_mono);
547}
548EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns);
549
550/**
551 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
552 * @tk: Timekeeper to snapshot.
553 *
554 * It generally is unsafe to access the clocksource after timekeeping has been
555 * suspended, so take a snapshot of the readout base of @tk and use it as the
556 * fast timekeeper's readout base while suspended. It will return the same
557 * number of cycles every time until timekeeping is resumed at which time the
558 * proper readout base for the fast timekeeper will be restored automatically.
559 */
560static void halt_fast_timekeeper(const struct timekeeper *tk)
561{
562 static struct tk_read_base tkr_dummy;
563 const struct tk_read_base *tkr = &tk->tkr_mono;
564
565 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
566 cycles_at_suspend = tk_clock_read(tkr);
567 tkr_dummy.clock = &dummy_clock;
568 tkr_dummy.base_real = tkr->base + tk->offs_real;
569 update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
570
571 tkr = &tk->tkr_raw;
572 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
573 tkr_dummy.clock = &dummy_clock;
574 update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
575}
576
577static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
578
579static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
580{
581 raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
582}
583
584/**
585 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
586 */
587int pvclock_gtod_register_notifier(struct notifier_block *nb)
588{
589 struct timekeeper *tk = &tk_core.timekeeper;
590 unsigned long flags;
591 int ret;
592
593 raw_spin_lock_irqsave(&timekeeper_lock, flags);
594 ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
595 update_pvclock_gtod(tk, true);
596 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
597
598 return ret;
599}
600EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
601
602/**
603 * pvclock_gtod_unregister_notifier - unregister a pvclock
604 * timedata update listener
605 */
606int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
607{
608 unsigned long flags;
609 int ret;
610
611 raw_spin_lock_irqsave(&timekeeper_lock, flags);
612 ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
613 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
614
615 return ret;
616}
617EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
618
619/*
620 * tk_update_leap_state - helper to update the next_leap_ktime
621 */
622static inline void tk_update_leap_state(struct timekeeper *tk)
623{
624 tk->next_leap_ktime = ntp_get_next_leap();
625 if (tk->next_leap_ktime != KTIME_MAX)
626 /* Convert to monotonic time */
627 tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
628}
629
630/*
631 * Update the ktime_t based scalar nsec members of the timekeeper
632 */
633static inline void tk_update_ktime_data(struct timekeeper *tk)
634{
635 u64 seconds;
636 u32 nsec;
637
638 /*
639 * The xtime based monotonic readout is:
640 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
641 * The ktime based monotonic readout is:
642 * nsec = base_mono + now();
643 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
644 */
645 seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
646 nsec = (u32) tk->wall_to_monotonic.tv_nsec;
647 tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
648
649 /*
650 * The sum of the nanoseconds portions of xtime and
651 * wall_to_monotonic can be greater/equal one second. Take
652 * this into account before updating tk->ktime_sec.
653 */
654 nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
655 if (nsec >= NSEC_PER_SEC)
656 seconds++;
657 tk->ktime_sec = seconds;
658
659 /* Update the monotonic raw base */
660 tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
661}
662
663/* must hold timekeeper_lock */
664static void timekeeping_update(struct timekeeper *tk, unsigned int action)
665{
666 if (action & TK_CLEAR_NTP) {
667 tk->ntp_error = 0;
668 ntp_clear();
669 }
670
671 tk_update_leap_state(tk);
672 tk_update_ktime_data(tk);
673
674 update_vsyscall(tk);
675 update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
676
677 tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
678 update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
679 update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
680
681 if (action & TK_CLOCK_WAS_SET)
682 tk->clock_was_set_seq++;
683 /*
684 * The mirroring of the data to the shadow-timekeeper needs
685 * to happen last here to ensure we don't over-write the
686 * timekeeper structure on the next update with stale data
687 */
688 if (action & TK_MIRROR)
689 memcpy(&shadow_timekeeper, &tk_core.timekeeper,
690 sizeof(tk_core.timekeeper));
691}
692
693/**
694 * timekeeping_forward_now - update clock to the current time
695 *
696 * Forward the current clock to update its state since the last call to
697 * update_wall_time(). This is useful before significant clock changes,
698 * as it avoids having to deal with this time offset explicitly.
699 */
700static void timekeeping_forward_now(struct timekeeper *tk)
701{
702 u64 cycle_now, delta;
703
704 cycle_now = tk_clock_read(&tk->tkr_mono);
705 delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
706 tk->tkr_mono.cycle_last = cycle_now;
707 tk->tkr_raw.cycle_last = cycle_now;
708
709 tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
710
711 /* If arch requires, add in get_arch_timeoffset() */
712 tk->tkr_mono.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_mono.shift;
713
714
715 tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
716
717 /* If arch requires, add in get_arch_timeoffset() */
718 tk->tkr_raw.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_raw.shift;
719
720 tk_normalize_xtime(tk);
721}
722
723/**
724 * ktime_get_real_ts64 - Returns the time of day in a timespec64.
725 * @ts: pointer to the timespec to be set
726 *
727 * Returns the time of day in a timespec64 (WARN if suspended).
728 */
729void ktime_get_real_ts64(struct timespec64 *ts)
730{
731 struct timekeeper *tk = &tk_core.timekeeper;
732 unsigned int seq;
733 u64 nsecs;
734
735 WARN_ON(timekeeping_suspended);
736
737 do {
738 seq = read_seqcount_begin(&tk_core.seq);
739
740 ts->tv_sec = tk->xtime_sec;
741 nsecs = timekeeping_get_ns(&tk->tkr_mono);
742
743 } while (read_seqcount_retry(&tk_core.seq, seq));
744
745 ts->tv_nsec = 0;
746 timespec64_add_ns(ts, nsecs);
747}
748EXPORT_SYMBOL(ktime_get_real_ts64);
749
750ktime_t ktime_get(void)
751{
752 struct timekeeper *tk = &tk_core.timekeeper;
753 unsigned int seq;
754 ktime_t base;
755 u64 nsecs;
756
757 WARN_ON(timekeeping_suspended);
758
759 do {
760 seq = read_seqcount_begin(&tk_core.seq);
761 base = tk->tkr_mono.base;
762 nsecs = timekeeping_get_ns(&tk->tkr_mono);
763
764 } while (read_seqcount_retry(&tk_core.seq, seq));
765
766 return ktime_add_ns(base, nsecs);
767}
768EXPORT_SYMBOL_GPL(ktime_get);
769
770u32 ktime_get_resolution_ns(void)
771{
772 struct timekeeper *tk = &tk_core.timekeeper;
773 unsigned int seq;
774 u32 nsecs;
775
776 WARN_ON(timekeeping_suspended);
777
778 do {
779 seq = read_seqcount_begin(&tk_core.seq);
780 nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
781 } while (read_seqcount_retry(&tk_core.seq, seq));
782
783 return nsecs;
784}
785EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
786
787static ktime_t *offsets[TK_OFFS_MAX] = {
788 [TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
789 [TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
790 [TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai,
791};
792
793ktime_t ktime_get_with_offset(enum tk_offsets offs)
794{
795 struct timekeeper *tk = &tk_core.timekeeper;
796 unsigned int seq;
797 ktime_t base, *offset = offsets[offs];
798 u64 nsecs;
799
800 WARN_ON(timekeeping_suspended);
801
802 do {
803 seq = read_seqcount_begin(&tk_core.seq);
804 base = ktime_add(tk->tkr_mono.base, *offset);
805 nsecs = timekeeping_get_ns(&tk->tkr_mono);
806
807 } while (read_seqcount_retry(&tk_core.seq, seq));
808
809 return ktime_add_ns(base, nsecs);
810
811}
812EXPORT_SYMBOL_GPL(ktime_get_with_offset);
813
814ktime_t ktime_get_coarse_with_offset(enum tk_offsets offs)
815{
816 struct timekeeper *tk = &tk_core.timekeeper;
817 unsigned int seq;
818 ktime_t base, *offset = offsets[offs];
819 u64 nsecs;
820
821 WARN_ON(timekeeping_suspended);
822
823 do {
824 seq = read_seqcount_begin(&tk_core.seq);
825 base = ktime_add(tk->tkr_mono.base, *offset);
826 nsecs = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
827
828 } while (read_seqcount_retry(&tk_core.seq, seq));
829
830 return ktime_add_ns(base, nsecs);
831}
832EXPORT_SYMBOL_GPL(ktime_get_coarse_with_offset);
833
834/**
835 * ktime_mono_to_any() - convert mononotic time to any other time
836 * @tmono: time to convert.
837 * @offs: which offset to use
838 */
839ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
840{
841 ktime_t *offset = offsets[offs];
842 unsigned int seq;
843 ktime_t tconv;
844
845 do {
846 seq = read_seqcount_begin(&tk_core.seq);
847 tconv = ktime_add(tmono, *offset);
848 } while (read_seqcount_retry(&tk_core.seq, seq));
849
850 return tconv;
851}
852EXPORT_SYMBOL_GPL(ktime_mono_to_any);
853
854/**
855 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
856 */
857ktime_t ktime_get_raw(void)
858{
859 struct timekeeper *tk = &tk_core.timekeeper;
860 unsigned int seq;
861 ktime_t base;
862 u64 nsecs;
863
864 do {
865 seq = read_seqcount_begin(&tk_core.seq);
866 base = tk->tkr_raw.base;
867 nsecs = timekeeping_get_ns(&tk->tkr_raw);
868
869 } while (read_seqcount_retry(&tk_core.seq, seq));
870
871 return ktime_add_ns(base, nsecs);
872}
873EXPORT_SYMBOL_GPL(ktime_get_raw);
874
875/**
876 * ktime_get_ts64 - get the monotonic clock in timespec64 format
877 * @ts: pointer to timespec variable
878 *
879 * The function calculates the monotonic clock from the realtime
880 * clock and the wall_to_monotonic offset and stores the result
881 * in normalized timespec64 format in the variable pointed to by @ts.
882 */
883void ktime_get_ts64(struct timespec64 *ts)
884{
885 struct timekeeper *tk = &tk_core.timekeeper;
886 struct timespec64 tomono;
887 unsigned int seq;
888 u64 nsec;
889
890 WARN_ON(timekeeping_suspended);
891
892 do {
893 seq = read_seqcount_begin(&tk_core.seq);
894 ts->tv_sec = tk->xtime_sec;
895 nsec = timekeeping_get_ns(&tk->tkr_mono);
896 tomono = tk->wall_to_monotonic;
897
898 } while (read_seqcount_retry(&tk_core.seq, seq));
899
900 ts->tv_sec += tomono.tv_sec;
901 ts->tv_nsec = 0;
902 timespec64_add_ns(ts, nsec + tomono.tv_nsec);
903}
904EXPORT_SYMBOL_GPL(ktime_get_ts64);
905
906/**
907 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
908 *
909 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
910 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
911 * works on both 32 and 64 bit systems. On 32 bit systems the readout
912 * covers ~136 years of uptime which should be enough to prevent
913 * premature wrap arounds.
914 */
915time64_t ktime_get_seconds(void)
916{
917 struct timekeeper *tk = &tk_core.timekeeper;
918
919 WARN_ON(timekeeping_suspended);
920 return tk->ktime_sec;
921}
922EXPORT_SYMBOL_GPL(ktime_get_seconds);
923
924/**
925 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
926 *
927 * Returns the wall clock seconds since 1970. This replaces the
928 * get_seconds() interface which is not y2038 safe on 32bit systems.
929 *
930 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
931 * 32bit systems the access must be protected with the sequence
932 * counter to provide "atomic" access to the 64bit tk->xtime_sec
933 * value.
934 */
935time64_t ktime_get_real_seconds(void)
936{
937 struct timekeeper *tk = &tk_core.timekeeper;
938 time64_t seconds;
939 unsigned int seq;
940
941 if (IS_ENABLED(CONFIG_64BIT))
942 return tk->xtime_sec;
943
944 do {
945 seq = read_seqcount_begin(&tk_core.seq);
946 seconds = tk->xtime_sec;
947
948 } while (read_seqcount_retry(&tk_core.seq, seq));
949
950 return seconds;
951}
952EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
953
954/**
955 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
956 * but without the sequence counter protect. This internal function
957 * is called just when timekeeping lock is already held.
958 */
959noinstr time64_t __ktime_get_real_seconds(void)
960{
961 struct timekeeper *tk = &tk_core.timekeeper;
962
963 return tk->xtime_sec;
964}
965
966/**
967 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
968 * @systime_snapshot: pointer to struct receiving the system time snapshot
969 */
970void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
971{
972 struct timekeeper *tk = &tk_core.timekeeper;
973 unsigned int seq;
974 ktime_t base_raw;
975 ktime_t base_real;
976 u64 nsec_raw;
977 u64 nsec_real;
978 u64 now;
979
980 WARN_ON_ONCE(timekeeping_suspended);
981
982 do {
983 seq = read_seqcount_begin(&tk_core.seq);
984 now = tk_clock_read(&tk->tkr_mono);
985 systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
986 systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
987 base_real = ktime_add(tk->tkr_mono.base,
988 tk_core.timekeeper.offs_real);
989 base_raw = tk->tkr_raw.base;
990 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
991 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
992 } while (read_seqcount_retry(&tk_core.seq, seq));
993
994 systime_snapshot->cycles = now;
995 systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
996 systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
997}
998EXPORT_SYMBOL_GPL(ktime_get_snapshot);
999
1000/* Scale base by mult/div checking for overflow */
1001static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
1002{
1003 u64 tmp, rem;
1004
1005 tmp = div64_u64_rem(*base, div, &rem);
1006
1007 if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
1008 ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
1009 return -EOVERFLOW;
1010 tmp *= mult;
1011
1012 rem = div64_u64(rem * mult, div);
1013 *base = tmp + rem;
1014 return 0;
1015}
1016
1017/**
1018 * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
1019 * @history: Snapshot representing start of history
1020 * @partial_history_cycles: Cycle offset into history (fractional part)
1021 * @total_history_cycles: Total history length in cycles
1022 * @discontinuity: True indicates clock was set on history period
1023 * @ts: Cross timestamp that should be adjusted using
1024 * partial/total ratio
1025 *
1026 * Helper function used by get_device_system_crosststamp() to correct the
1027 * crosstimestamp corresponding to the start of the current interval to the
1028 * system counter value (timestamp point) provided by the driver. The
1029 * total_history_* quantities are the total history starting at the provided
1030 * reference point and ending at the start of the current interval. The cycle
1031 * count between the driver timestamp point and the start of the current
1032 * interval is partial_history_cycles.
1033 */
1034static int adjust_historical_crosststamp(struct system_time_snapshot *history,
1035 u64 partial_history_cycles,
1036 u64 total_history_cycles,
1037 bool discontinuity,
1038 struct system_device_crosststamp *ts)
1039{
1040 struct timekeeper *tk = &tk_core.timekeeper;
1041 u64 corr_raw, corr_real;
1042 bool interp_forward;
1043 int ret;
1044
1045 if (total_history_cycles == 0 || partial_history_cycles == 0)
1046 return 0;
1047
1048 /* Interpolate shortest distance from beginning or end of history */
1049 interp_forward = partial_history_cycles > total_history_cycles / 2;
1050 partial_history_cycles = interp_forward ?
1051 total_history_cycles - partial_history_cycles :
1052 partial_history_cycles;
1053
1054 /*
1055 * Scale the monotonic raw time delta by:
1056 * partial_history_cycles / total_history_cycles
1057 */
1058 corr_raw = (u64)ktime_to_ns(
1059 ktime_sub(ts->sys_monoraw, history->raw));
1060 ret = scale64_check_overflow(partial_history_cycles,
1061 total_history_cycles, &corr_raw);
1062 if (ret)
1063 return ret;
1064
1065 /*
1066 * If there is a discontinuity in the history, scale monotonic raw
1067 * correction by:
1068 * mult(real)/mult(raw) yielding the realtime correction
1069 * Otherwise, calculate the realtime correction similar to monotonic
1070 * raw calculation
1071 */
1072 if (discontinuity) {
1073 corr_real = mul_u64_u32_div
1074 (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1075 } else {
1076 corr_real = (u64)ktime_to_ns(
1077 ktime_sub(ts->sys_realtime, history->real));
1078 ret = scale64_check_overflow(partial_history_cycles,
1079 total_history_cycles, &corr_real);
1080 if (ret)
1081 return ret;
1082 }
1083
1084 /* Fixup monotonic raw and real time time values */
1085 if (interp_forward) {
1086 ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1087 ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1088 } else {
1089 ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1090 ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1091 }
1092
1093 return 0;
1094}
1095
1096/*
1097 * cycle_between - true if test occurs chronologically between before and after
1098 */
1099static bool cycle_between(u64 before, u64 test, u64 after)
1100{
1101 if (test > before && test < after)
1102 return true;
1103 if (test < before && before > after)
1104 return true;
1105 return false;
1106}
1107
1108/**
1109 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1110 * @get_time_fn: Callback to get simultaneous device time and
1111 * system counter from the device driver
1112 * @ctx: Context passed to get_time_fn()
1113 * @history_begin: Historical reference point used to interpolate system
1114 * time when counter provided by the driver is before the current interval
1115 * @xtstamp: Receives simultaneously captured system and device time
1116 *
1117 * Reads a timestamp from a device and correlates it to system time
1118 */
1119int get_device_system_crosststamp(int (*get_time_fn)
1120 (ktime_t *device_time,
1121 struct system_counterval_t *sys_counterval,
1122 void *ctx),
1123 void *ctx,
1124 struct system_time_snapshot *history_begin,
1125 struct system_device_crosststamp *xtstamp)
1126{
1127 struct system_counterval_t system_counterval;
1128 struct timekeeper *tk = &tk_core.timekeeper;
1129 u64 cycles, now, interval_start;
1130 unsigned int clock_was_set_seq = 0;
1131 ktime_t base_real, base_raw;
1132 u64 nsec_real, nsec_raw;
1133 u8 cs_was_changed_seq;
1134 unsigned int seq;
1135 bool do_interp;
1136 int ret;
1137
1138 do {
1139 seq = read_seqcount_begin(&tk_core.seq);
1140 /*
1141 * Try to synchronously capture device time and a system
1142 * counter value calling back into the device driver
1143 */
1144 ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1145 if (ret)
1146 return ret;
1147
1148 /*
1149 * Verify that the clocksource associated with the captured
1150 * system counter value is the same as the currently installed
1151 * timekeeper clocksource
1152 */
1153 if (tk->tkr_mono.clock != system_counterval.cs)
1154 return -ENODEV;
1155 cycles = system_counterval.cycles;
1156
1157 /*
1158 * Check whether the system counter value provided by the
1159 * device driver is on the current timekeeping interval.
1160 */
1161 now = tk_clock_read(&tk->tkr_mono);
1162 interval_start = tk->tkr_mono.cycle_last;
1163 if (!cycle_between(interval_start, cycles, now)) {
1164 clock_was_set_seq = tk->clock_was_set_seq;
1165 cs_was_changed_seq = tk->cs_was_changed_seq;
1166 cycles = interval_start;
1167 do_interp = true;
1168 } else {
1169 do_interp = false;
1170 }
1171
1172 base_real = ktime_add(tk->tkr_mono.base,
1173 tk_core.timekeeper.offs_real);
1174 base_raw = tk->tkr_raw.base;
1175
1176 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1177 system_counterval.cycles);
1178 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1179 system_counterval.cycles);
1180 } while (read_seqcount_retry(&tk_core.seq, seq));
1181
1182 xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1183 xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1184
1185 /*
1186 * Interpolate if necessary, adjusting back from the start of the
1187 * current interval
1188 */
1189 if (do_interp) {
1190 u64 partial_history_cycles, total_history_cycles;
1191 bool discontinuity;
1192
1193 /*
1194 * Check that the counter value occurs after the provided
1195 * history reference and that the history doesn't cross a
1196 * clocksource change
1197 */
1198 if (!history_begin ||
1199 !cycle_between(history_begin->cycles,
1200 system_counterval.cycles, cycles) ||
1201 history_begin->cs_was_changed_seq != cs_was_changed_seq)
1202 return -EINVAL;
1203 partial_history_cycles = cycles - system_counterval.cycles;
1204 total_history_cycles = cycles - history_begin->cycles;
1205 discontinuity =
1206 history_begin->clock_was_set_seq != clock_was_set_seq;
1207
1208 ret = adjust_historical_crosststamp(history_begin,
1209 partial_history_cycles,
1210 total_history_cycles,
1211 discontinuity, xtstamp);
1212 if (ret)
1213 return ret;
1214 }
1215
1216 return 0;
1217}
1218EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1219
1220/**
1221 * do_settimeofday64 - Sets the time of day.
1222 * @ts: pointer to the timespec64 variable containing the new time
1223 *
1224 * Sets the time of day to the new time and update NTP and notify hrtimers
1225 */
1226int do_settimeofday64(const struct timespec64 *ts)
1227{
1228 struct timekeeper *tk = &tk_core.timekeeper;
1229 struct timespec64 ts_delta, xt;
1230 unsigned long flags;
1231 int ret = 0;
1232
1233 if (!timespec64_valid_settod(ts))
1234 return -EINVAL;
1235
1236 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1237 write_seqcount_begin(&tk_core.seq);
1238
1239 timekeeping_forward_now(tk);
1240
1241 xt = tk_xtime(tk);
1242 ts_delta.tv_sec = ts->tv_sec - xt.tv_sec;
1243 ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec;
1244
1245 if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1246 ret = -EINVAL;
1247 goto out;
1248 }
1249
1250 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1251
1252 tk_set_xtime(tk, ts);
1253out:
1254 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1255
1256 write_seqcount_end(&tk_core.seq);
1257 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1258
1259 /* signal hrtimers about time change */
1260 clock_was_set();
1261
1262 if (!ret)
1263 audit_tk_injoffset(ts_delta);
1264
1265 return ret;
1266}
1267EXPORT_SYMBOL(do_settimeofday64);
1268
1269/**
1270 * timekeeping_inject_offset - Adds or subtracts from the current time.
1271 * @tv: pointer to the timespec variable containing the offset
1272 *
1273 * Adds or subtracts an offset value from the current time.
1274 */
1275static int timekeeping_inject_offset(const struct timespec64 *ts)
1276{
1277 struct timekeeper *tk = &tk_core.timekeeper;
1278 unsigned long flags;
1279 struct timespec64 tmp;
1280 int ret = 0;
1281
1282 if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
1283 return -EINVAL;
1284
1285 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1286 write_seqcount_begin(&tk_core.seq);
1287
1288 timekeeping_forward_now(tk);
1289
1290 /* Make sure the proposed value is valid */
1291 tmp = timespec64_add(tk_xtime(tk), *ts);
1292 if (timespec64_compare(&tk->wall_to_monotonic, ts) > 0 ||
1293 !timespec64_valid_settod(&tmp)) {
1294 ret = -EINVAL;
1295 goto error;
1296 }
1297
1298 tk_xtime_add(tk, ts);
1299 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *ts));
1300
1301error: /* even if we error out, we forwarded the time, so call update */
1302 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1303
1304 write_seqcount_end(&tk_core.seq);
1305 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1306
1307 /* signal hrtimers about time change */
1308 clock_was_set();
1309
1310 return ret;
1311}
1312
1313/*
1314 * Indicates if there is an offset between the system clock and the hardware
1315 * clock/persistent clock/rtc.
1316 */
1317int persistent_clock_is_local;
1318
1319/*
1320 * Adjust the time obtained from the CMOS to be UTC time instead of
1321 * local time.
1322 *
1323 * This is ugly, but preferable to the alternatives. Otherwise we
1324 * would either need to write a program to do it in /etc/rc (and risk
1325 * confusion if the program gets run more than once; it would also be
1326 * hard to make the program warp the clock precisely n hours) or
1327 * compile in the timezone information into the kernel. Bad, bad....
1328 *
1329 * - TYT, 1992-01-01
1330 *
1331 * The best thing to do is to keep the CMOS clock in universal time (UTC)
1332 * as real UNIX machines always do it. This avoids all headaches about
1333 * daylight saving times and warping kernel clocks.
1334 */
1335void timekeeping_warp_clock(void)
1336{
1337 if (sys_tz.tz_minuteswest != 0) {
1338 struct timespec64 adjust;
1339
1340 persistent_clock_is_local = 1;
1341 adjust.tv_sec = sys_tz.tz_minuteswest * 60;
1342 adjust.tv_nsec = 0;
1343 timekeeping_inject_offset(&adjust);
1344 }
1345}
1346
1347/**
1348 * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1349 *
1350 */
1351static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1352{
1353 tk->tai_offset = tai_offset;
1354 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1355}
1356
1357/**
1358 * change_clocksource - Swaps clocksources if a new one is available
1359 *
1360 * Accumulates current time interval and initializes new clocksource
1361 */
1362static int change_clocksource(void *data)
1363{
1364 struct timekeeper *tk = &tk_core.timekeeper;
1365 struct clocksource *new, *old;
1366 unsigned long flags;
1367
1368 new = (struct clocksource *) data;
1369
1370 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1371 write_seqcount_begin(&tk_core.seq);
1372
1373 timekeeping_forward_now(tk);
1374 /*
1375 * If the cs is in module, get a module reference. Succeeds
1376 * for built-in code (owner == NULL) as well.
1377 */
1378 if (try_module_get(new->owner)) {
1379 if (!new->enable || new->enable(new) == 0) {
1380 old = tk->tkr_mono.clock;
1381 tk_setup_internals(tk, new);
1382 if (old->disable)
1383 old->disable(old);
1384 module_put(old->owner);
1385 } else {
1386 module_put(new->owner);
1387 }
1388 }
1389 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1390
1391 write_seqcount_end(&tk_core.seq);
1392 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1393
1394 return 0;
1395}
1396
1397/**
1398 * timekeeping_notify - Install a new clock source
1399 * @clock: pointer to the clock source
1400 *
1401 * This function is called from clocksource.c after a new, better clock
1402 * source has been registered. The caller holds the clocksource_mutex.
1403 */
1404int timekeeping_notify(struct clocksource *clock)
1405{
1406 struct timekeeper *tk = &tk_core.timekeeper;
1407
1408 if (tk->tkr_mono.clock == clock)
1409 return 0;
1410 stop_machine(change_clocksource, clock, NULL);
1411 tick_clock_notify();
1412 return tk->tkr_mono.clock == clock ? 0 : -1;
1413}
1414
1415/**
1416 * ktime_get_raw_ts64 - Returns the raw monotonic time in a timespec
1417 * @ts: pointer to the timespec64 to be set
1418 *
1419 * Returns the raw monotonic time (completely un-modified by ntp)
1420 */
1421void ktime_get_raw_ts64(struct timespec64 *ts)
1422{
1423 struct timekeeper *tk = &tk_core.timekeeper;
1424 unsigned int seq;
1425 u64 nsecs;
1426
1427 do {
1428 seq = read_seqcount_begin(&tk_core.seq);
1429 ts->tv_sec = tk->raw_sec;
1430 nsecs = timekeeping_get_ns(&tk->tkr_raw);
1431
1432 } while (read_seqcount_retry(&tk_core.seq, seq));
1433
1434 ts->tv_nsec = 0;
1435 timespec64_add_ns(ts, nsecs);
1436}
1437EXPORT_SYMBOL(ktime_get_raw_ts64);
1438
1439
1440/**
1441 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1442 */
1443int timekeeping_valid_for_hres(void)
1444{
1445 struct timekeeper *tk = &tk_core.timekeeper;
1446 unsigned int seq;
1447 int ret;
1448
1449 do {
1450 seq = read_seqcount_begin(&tk_core.seq);
1451
1452 ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1453
1454 } while (read_seqcount_retry(&tk_core.seq, seq));
1455
1456 return ret;
1457}
1458
1459/**
1460 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1461 */
1462u64 timekeeping_max_deferment(void)
1463{
1464 struct timekeeper *tk = &tk_core.timekeeper;
1465 unsigned int seq;
1466 u64 ret;
1467
1468 do {
1469 seq = read_seqcount_begin(&tk_core.seq);
1470
1471 ret = tk->tkr_mono.clock->max_idle_ns;
1472
1473 } while (read_seqcount_retry(&tk_core.seq, seq));
1474
1475 return ret;
1476}
1477
1478/**
1479 * read_persistent_clock64 - Return time from the persistent clock.
1480 *
1481 * Weak dummy function for arches that do not yet support it.
1482 * Reads the time from the battery backed persistent clock.
1483 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1484 *
1485 * XXX - Do be sure to remove it once all arches implement it.
1486 */
1487void __weak read_persistent_clock64(struct timespec64 *ts)
1488{
1489 ts->tv_sec = 0;
1490 ts->tv_nsec = 0;
1491}
1492
1493/**
1494 * read_persistent_wall_and_boot_offset - Read persistent clock, and also offset
1495 * from the boot.
1496 *
1497 * Weak dummy function for arches that do not yet support it.
1498 * wall_time - current time as returned by persistent clock
1499 * boot_offset - offset that is defined as wall_time - boot_time
1500 * The default function calculates offset based on the current value of
1501 * local_clock(). This way architectures that support sched_clock() but don't
1502 * support dedicated boot time clock will provide the best estimate of the
1503 * boot time.
1504 */
1505void __weak __init
1506read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
1507 struct timespec64 *boot_offset)
1508{
1509 read_persistent_clock64(wall_time);
1510 *boot_offset = ns_to_timespec64(local_clock());
1511}
1512
1513/*
1514 * Flag reflecting whether timekeeping_resume() has injected sleeptime.
1515 *
1516 * The flag starts of false and is only set when a suspend reaches
1517 * timekeeping_suspend(), timekeeping_resume() sets it to false when the
1518 * timekeeper clocksource is not stopping across suspend and has been
1519 * used to update sleep time. If the timekeeper clocksource has stopped
1520 * then the flag stays true and is used by the RTC resume code to decide
1521 * whether sleeptime must be injected and if so the flag gets false then.
1522 *
1523 * If a suspend fails before reaching timekeeping_resume() then the flag
1524 * stays false and prevents erroneous sleeptime injection.
1525 */
1526static bool suspend_timing_needed;
1527
1528/* Flag for if there is a persistent clock on this platform */
1529static bool persistent_clock_exists;
1530
1531/*
1532 * timekeeping_init - Initializes the clocksource and common timekeeping values
1533 */
1534void __init timekeeping_init(void)
1535{
1536 struct timespec64 wall_time, boot_offset, wall_to_mono;
1537 struct timekeeper *tk = &tk_core.timekeeper;
1538 struct clocksource *clock;
1539 unsigned long flags;
1540
1541 read_persistent_wall_and_boot_offset(&wall_time, &boot_offset);
1542 if (timespec64_valid_settod(&wall_time) &&
1543 timespec64_to_ns(&wall_time) > 0) {
1544 persistent_clock_exists = true;
1545 } else if (timespec64_to_ns(&wall_time) != 0) {
1546 pr_warn("Persistent clock returned invalid value");
1547 wall_time = (struct timespec64){0};
1548 }
1549
1550 if (timespec64_compare(&wall_time, &boot_offset) < 0)
1551 boot_offset = (struct timespec64){0};
1552
1553 /*
1554 * We want set wall_to_mono, so the following is true:
1555 * wall time + wall_to_mono = boot time
1556 */
1557 wall_to_mono = timespec64_sub(boot_offset, wall_time);
1558
1559 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1560 write_seqcount_begin(&tk_core.seq);
1561 ntp_init();
1562
1563 clock = clocksource_default_clock();
1564 if (clock->enable)
1565 clock->enable(clock);
1566 tk_setup_internals(tk, clock);
1567
1568 tk_set_xtime(tk, &wall_time);
1569 tk->raw_sec = 0;
1570
1571 tk_set_wall_to_mono(tk, wall_to_mono);
1572
1573 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1574
1575 write_seqcount_end(&tk_core.seq);
1576 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1577}
1578
1579/* time in seconds when suspend began for persistent clock */
1580static struct timespec64 timekeeping_suspend_time;
1581
1582/**
1583 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1584 * @delta: pointer to a timespec delta value
1585 *
1586 * Takes a timespec offset measuring a suspend interval and properly
1587 * adds the sleep offset to the timekeeping variables.
1588 */
1589static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1590 const struct timespec64 *delta)
1591{
1592 if (!timespec64_valid_strict(delta)) {
1593 printk_deferred(KERN_WARNING
1594 "__timekeeping_inject_sleeptime: Invalid "
1595 "sleep delta value!\n");
1596 return;
1597 }
1598 tk_xtime_add(tk, delta);
1599 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1600 tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1601 tk_debug_account_sleep_time(delta);
1602}
1603
1604#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1605/**
1606 * We have three kinds of time sources to use for sleep time
1607 * injection, the preference order is:
1608 * 1) non-stop clocksource
1609 * 2) persistent clock (ie: RTC accessible when irqs are off)
1610 * 3) RTC
1611 *
1612 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1613 * If system has neither 1) nor 2), 3) will be used finally.
1614 *
1615 *
1616 * If timekeeping has injected sleeptime via either 1) or 2),
1617 * 3) becomes needless, so in this case we don't need to call
1618 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1619 * means.
1620 */
1621bool timekeeping_rtc_skipresume(void)
1622{
1623 return !suspend_timing_needed;
1624}
1625
1626/**
1627 * 1) can be determined whether to use or not only when doing
1628 * timekeeping_resume() which is invoked after rtc_suspend(),
1629 * so we can't skip rtc_suspend() surely if system has 1).
1630 *
1631 * But if system has 2), 2) will definitely be used, so in this
1632 * case we don't need to call rtc_suspend(), and this is what
1633 * timekeeping_rtc_skipsuspend() means.
1634 */
1635bool timekeeping_rtc_skipsuspend(void)
1636{
1637 return persistent_clock_exists;
1638}
1639
1640/**
1641 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1642 * @delta: pointer to a timespec64 delta value
1643 *
1644 * This hook is for architectures that cannot support read_persistent_clock64
1645 * because their RTC/persistent clock is only accessible when irqs are enabled.
1646 * and also don't have an effective nonstop clocksource.
1647 *
1648 * This function should only be called by rtc_resume(), and allows
1649 * a suspend offset to be injected into the timekeeping values.
1650 */
1651void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
1652{
1653 struct timekeeper *tk = &tk_core.timekeeper;
1654 unsigned long flags;
1655
1656 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1657 write_seqcount_begin(&tk_core.seq);
1658
1659 suspend_timing_needed = false;
1660
1661 timekeeping_forward_now(tk);
1662
1663 __timekeeping_inject_sleeptime(tk, delta);
1664
1665 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1666
1667 write_seqcount_end(&tk_core.seq);
1668 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1669
1670 /* signal hrtimers about time change */
1671 clock_was_set();
1672}
1673#endif
1674
1675/**
1676 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1677 */
1678void timekeeping_resume(void)
1679{
1680 struct timekeeper *tk = &tk_core.timekeeper;
1681 struct clocksource *clock = tk->tkr_mono.clock;
1682 unsigned long flags;
1683 struct timespec64 ts_new, ts_delta;
1684 u64 cycle_now, nsec;
1685 bool inject_sleeptime = false;
1686
1687 read_persistent_clock64(&ts_new);
1688
1689 clockevents_resume();
1690 clocksource_resume();
1691
1692 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1693 write_seqcount_begin(&tk_core.seq);
1694
1695 /*
1696 * After system resumes, we need to calculate the suspended time and
1697 * compensate it for the OS time. There are 3 sources that could be
1698 * used: Nonstop clocksource during suspend, persistent clock and rtc
1699 * device.
1700 *
1701 * One specific platform may have 1 or 2 or all of them, and the
1702 * preference will be:
1703 * suspend-nonstop clocksource -> persistent clock -> rtc
1704 * The less preferred source will only be tried if there is no better
1705 * usable source. The rtc part is handled separately in rtc core code.
1706 */
1707 cycle_now = tk_clock_read(&tk->tkr_mono);
1708 nsec = clocksource_stop_suspend_timing(clock, cycle_now);
1709 if (nsec > 0) {
1710 ts_delta = ns_to_timespec64(nsec);
1711 inject_sleeptime = true;
1712 } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1713 ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1714 inject_sleeptime = true;
1715 }
1716
1717 if (inject_sleeptime) {
1718 suspend_timing_needed = false;
1719 __timekeeping_inject_sleeptime(tk, &ts_delta);
1720 }
1721
1722 /* Re-base the last cycle value */
1723 tk->tkr_mono.cycle_last = cycle_now;
1724 tk->tkr_raw.cycle_last = cycle_now;
1725
1726 tk->ntp_error = 0;
1727 timekeeping_suspended = 0;
1728 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1729 write_seqcount_end(&tk_core.seq);
1730 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1731
1732 touch_softlockup_watchdog();
1733
1734 tick_resume();
1735 hrtimers_resume();
1736}
1737
1738int timekeeping_suspend(void)
1739{
1740 struct timekeeper *tk = &tk_core.timekeeper;
1741 unsigned long flags;
1742 struct timespec64 delta, delta_delta;
1743 static struct timespec64 old_delta;
1744 struct clocksource *curr_clock;
1745 u64 cycle_now;
1746
1747 read_persistent_clock64(&timekeeping_suspend_time);
1748
1749 /*
1750 * On some systems the persistent_clock can not be detected at
1751 * timekeeping_init by its return value, so if we see a valid
1752 * value returned, update the persistent_clock_exists flag.
1753 */
1754 if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1755 persistent_clock_exists = true;
1756
1757 suspend_timing_needed = true;
1758
1759 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1760 write_seqcount_begin(&tk_core.seq);
1761 timekeeping_forward_now(tk);
1762 timekeeping_suspended = 1;
1763
1764 /*
1765 * Since we've called forward_now, cycle_last stores the value
1766 * just read from the current clocksource. Save this to potentially
1767 * use in suspend timing.
1768 */
1769 curr_clock = tk->tkr_mono.clock;
1770 cycle_now = tk->tkr_mono.cycle_last;
1771 clocksource_start_suspend_timing(curr_clock, cycle_now);
1772
1773 if (persistent_clock_exists) {
1774 /*
1775 * To avoid drift caused by repeated suspend/resumes,
1776 * which each can add ~1 second drift error,
1777 * try to compensate so the difference in system time
1778 * and persistent_clock time stays close to constant.
1779 */
1780 delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1781 delta_delta = timespec64_sub(delta, old_delta);
1782 if (abs(delta_delta.tv_sec) >= 2) {
1783 /*
1784 * if delta_delta is too large, assume time correction
1785 * has occurred and set old_delta to the current delta.
1786 */
1787 old_delta = delta;
1788 } else {
1789 /* Otherwise try to adjust old_system to compensate */
1790 timekeeping_suspend_time =
1791 timespec64_add(timekeeping_suspend_time, delta_delta);
1792 }
1793 }
1794
1795 timekeeping_update(tk, TK_MIRROR);
1796 halt_fast_timekeeper(tk);
1797 write_seqcount_end(&tk_core.seq);
1798 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1799
1800 tick_suspend();
1801 clocksource_suspend();
1802 clockevents_suspend();
1803
1804 return 0;
1805}
1806
1807/* sysfs resume/suspend bits for timekeeping */
1808static struct syscore_ops timekeeping_syscore_ops = {
1809 .resume = timekeeping_resume,
1810 .suspend = timekeeping_suspend,
1811};
1812
1813static int __init timekeeping_init_ops(void)
1814{
1815 register_syscore_ops(&timekeeping_syscore_ops);
1816 return 0;
1817}
1818device_initcall(timekeeping_init_ops);
1819
1820/*
1821 * Apply a multiplier adjustment to the timekeeper
1822 */
1823static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1824 s64 offset,
1825 s32 mult_adj)
1826{
1827 s64 interval = tk->cycle_interval;
1828
1829 if (mult_adj == 0) {
1830 return;
1831 } else if (mult_adj == -1) {
1832 interval = -interval;
1833 offset = -offset;
1834 } else if (mult_adj != 1) {
1835 interval *= mult_adj;
1836 offset *= mult_adj;
1837 }
1838
1839 /*
1840 * So the following can be confusing.
1841 *
1842 * To keep things simple, lets assume mult_adj == 1 for now.
1843 *
1844 * When mult_adj != 1, remember that the interval and offset values
1845 * have been appropriately scaled so the math is the same.
1846 *
1847 * The basic idea here is that we're increasing the multiplier
1848 * by one, this causes the xtime_interval to be incremented by
1849 * one cycle_interval. This is because:
1850 * xtime_interval = cycle_interval * mult
1851 * So if mult is being incremented by one:
1852 * xtime_interval = cycle_interval * (mult + 1)
1853 * Its the same as:
1854 * xtime_interval = (cycle_interval * mult) + cycle_interval
1855 * Which can be shortened to:
1856 * xtime_interval += cycle_interval
1857 *
1858 * So offset stores the non-accumulated cycles. Thus the current
1859 * time (in shifted nanoseconds) is:
1860 * now = (offset * adj) + xtime_nsec
1861 * Now, even though we're adjusting the clock frequency, we have
1862 * to keep time consistent. In other words, we can't jump back
1863 * in time, and we also want to avoid jumping forward in time.
1864 *
1865 * So given the same offset value, we need the time to be the same
1866 * both before and after the freq adjustment.
1867 * now = (offset * adj_1) + xtime_nsec_1
1868 * now = (offset * adj_2) + xtime_nsec_2
1869 * So:
1870 * (offset * adj_1) + xtime_nsec_1 =
1871 * (offset * adj_2) + xtime_nsec_2
1872 * And we know:
1873 * adj_2 = adj_1 + 1
1874 * So:
1875 * (offset * adj_1) + xtime_nsec_1 =
1876 * (offset * (adj_1+1)) + xtime_nsec_2
1877 * (offset * adj_1) + xtime_nsec_1 =
1878 * (offset * adj_1) + offset + xtime_nsec_2
1879 * Canceling the sides:
1880 * xtime_nsec_1 = offset + xtime_nsec_2
1881 * Which gives us:
1882 * xtime_nsec_2 = xtime_nsec_1 - offset
1883 * Which simplfies to:
1884 * xtime_nsec -= offset
1885 */
1886 if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1887 /* NTP adjustment caused clocksource mult overflow */
1888 WARN_ON_ONCE(1);
1889 return;
1890 }
1891
1892 tk->tkr_mono.mult += mult_adj;
1893 tk->xtime_interval += interval;
1894 tk->tkr_mono.xtime_nsec -= offset;
1895}
1896
1897/*
1898 * Adjust the timekeeper's multiplier to the correct frequency
1899 * and also to reduce the accumulated error value.
1900 */
1901static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1902{
1903 u32 mult;
1904
1905 /*
1906 * Determine the multiplier from the current NTP tick length.
1907 * Avoid expensive division when the tick length doesn't change.
1908 */
1909 if (likely(tk->ntp_tick == ntp_tick_length())) {
1910 mult = tk->tkr_mono.mult - tk->ntp_err_mult;
1911 } else {
1912 tk->ntp_tick = ntp_tick_length();
1913 mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) -
1914 tk->xtime_remainder, tk->cycle_interval);
1915 }
1916
1917 /*
1918 * If the clock is behind the NTP time, increase the multiplier by 1
1919 * to catch up with it. If it's ahead and there was a remainder in the
1920 * tick division, the clock will slow down. Otherwise it will stay
1921 * ahead until the tick length changes to a non-divisible value.
1922 */
1923 tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0;
1924 mult += tk->ntp_err_mult;
1925
1926 timekeeping_apply_adjustment(tk, offset, mult - tk->tkr_mono.mult);
1927
1928 if (unlikely(tk->tkr_mono.clock->maxadj &&
1929 (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
1930 > tk->tkr_mono.clock->maxadj))) {
1931 printk_once(KERN_WARNING
1932 "Adjusting %s more than 11%% (%ld vs %ld)\n",
1933 tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
1934 (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
1935 }
1936
1937 /*
1938 * It may be possible that when we entered this function, xtime_nsec
1939 * was very small. Further, if we're slightly speeding the clocksource
1940 * in the code above, its possible the required corrective factor to
1941 * xtime_nsec could cause it to underflow.
1942 *
1943 * Now, since we have already accumulated the second and the NTP
1944 * subsystem has been notified via second_overflow(), we need to skip
1945 * the next update.
1946 */
1947 if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
1948 tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC <<
1949 tk->tkr_mono.shift;
1950 tk->xtime_sec--;
1951 tk->skip_second_overflow = 1;
1952 }
1953}
1954
1955/**
1956 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1957 *
1958 * Helper function that accumulates the nsecs greater than a second
1959 * from the xtime_nsec field to the xtime_secs field.
1960 * It also calls into the NTP code to handle leapsecond processing.
1961 *
1962 */
1963static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
1964{
1965 u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
1966 unsigned int clock_set = 0;
1967
1968 while (tk->tkr_mono.xtime_nsec >= nsecps) {
1969 int leap;
1970
1971 tk->tkr_mono.xtime_nsec -= nsecps;
1972 tk->xtime_sec++;
1973
1974 /*
1975 * Skip NTP update if this second was accumulated before,
1976 * i.e. xtime_nsec underflowed in timekeeping_adjust()
1977 */
1978 if (unlikely(tk->skip_second_overflow)) {
1979 tk->skip_second_overflow = 0;
1980 continue;
1981 }
1982
1983 /* Figure out if its a leap sec and apply if needed */
1984 leap = second_overflow(tk->xtime_sec);
1985 if (unlikely(leap)) {
1986 struct timespec64 ts;
1987
1988 tk->xtime_sec += leap;
1989
1990 ts.tv_sec = leap;
1991 ts.tv_nsec = 0;
1992 tk_set_wall_to_mono(tk,
1993 timespec64_sub(tk->wall_to_monotonic, ts));
1994
1995 __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
1996
1997 clock_set = TK_CLOCK_WAS_SET;
1998 }
1999 }
2000 return clock_set;
2001}
2002
2003/**
2004 * logarithmic_accumulation - shifted accumulation of cycles
2005 *
2006 * This functions accumulates a shifted interval of cycles into
2007 * a shifted interval nanoseconds. Allows for O(log) accumulation
2008 * loop.
2009 *
2010 * Returns the unconsumed cycles.
2011 */
2012static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2013 u32 shift, unsigned int *clock_set)
2014{
2015 u64 interval = tk->cycle_interval << shift;
2016 u64 snsec_per_sec;
2017
2018 /* If the offset is smaller than a shifted interval, do nothing */
2019 if (offset < interval)
2020 return offset;
2021
2022 /* Accumulate one shifted interval */
2023 offset -= interval;
2024 tk->tkr_mono.cycle_last += interval;
2025 tk->tkr_raw.cycle_last += interval;
2026
2027 tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2028 *clock_set |= accumulate_nsecs_to_secs(tk);
2029
2030 /* Accumulate raw time */
2031 tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2032 snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2033 while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2034 tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2035 tk->raw_sec++;
2036 }
2037
2038 /* Accumulate error between NTP and clock interval */
2039 tk->ntp_error += tk->ntp_tick << shift;
2040 tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2041 (tk->ntp_error_shift + shift);
2042
2043 return offset;
2044}
2045
2046/*
2047 * timekeeping_advance - Updates the timekeeper to the current time and
2048 * current NTP tick length
2049 */
2050static void timekeeping_advance(enum timekeeping_adv_mode mode)
2051{
2052 struct timekeeper *real_tk = &tk_core.timekeeper;
2053 struct timekeeper *tk = &shadow_timekeeper;
2054 u64 offset;
2055 int shift = 0, maxshift;
2056 unsigned int clock_set = 0;
2057 unsigned long flags;
2058
2059 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2060
2061 /* Make sure we're fully resumed: */
2062 if (unlikely(timekeeping_suspended))
2063 goto out;
2064
2065#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
2066 offset = real_tk->cycle_interval;
2067
2068 if (mode != TK_ADV_TICK)
2069 goto out;
2070#else
2071 offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
2072 tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2073
2074 /* Check if there's really nothing to do */
2075 if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK)
2076 goto out;
2077#endif
2078
2079 /* Do some additional sanity checking */
2080 timekeeping_check_update(tk, offset);
2081
2082 /*
2083 * With NO_HZ we may have to accumulate many cycle_intervals
2084 * (think "ticks") worth of time at once. To do this efficiently,
2085 * we calculate the largest doubling multiple of cycle_intervals
2086 * that is smaller than the offset. We then accumulate that
2087 * chunk in one go, and then try to consume the next smaller
2088 * doubled multiple.
2089 */
2090 shift = ilog2(offset) - ilog2(tk->cycle_interval);
2091 shift = max(0, shift);
2092 /* Bound shift to one less than what overflows tick_length */
2093 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2094 shift = min(shift, maxshift);
2095 while (offset >= tk->cycle_interval) {
2096 offset = logarithmic_accumulation(tk, offset, shift,
2097 &clock_set);
2098 if (offset < tk->cycle_interval<<shift)
2099 shift--;
2100 }
2101
2102 /* Adjust the multiplier to correct NTP error */
2103 timekeeping_adjust(tk, offset);
2104
2105 /*
2106 * Finally, make sure that after the rounding
2107 * xtime_nsec isn't larger than NSEC_PER_SEC
2108 */
2109 clock_set |= accumulate_nsecs_to_secs(tk);
2110
2111 write_seqcount_begin(&tk_core.seq);
2112 /*
2113 * Update the real timekeeper.
2114 *
2115 * We could avoid this memcpy by switching pointers, but that
2116 * requires changes to all other timekeeper usage sites as
2117 * well, i.e. move the timekeeper pointer getter into the
2118 * spinlocked/seqcount protected sections. And we trade this
2119 * memcpy under the tk_core.seq against one before we start
2120 * updating.
2121 */
2122 timekeeping_update(tk, clock_set);
2123 memcpy(real_tk, tk, sizeof(*tk));
2124 /* The memcpy must come last. Do not put anything here! */
2125 write_seqcount_end(&tk_core.seq);
2126out:
2127 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2128 if (clock_set)
2129 /* Have to call _delayed version, since in irq context*/
2130 clock_was_set_delayed();
2131}
2132
2133/**
2134 * update_wall_time - Uses the current clocksource to increment the wall time
2135 *
2136 */
2137void update_wall_time(void)
2138{
2139 timekeeping_advance(TK_ADV_TICK);
2140}
2141
2142/**
2143 * getboottime64 - Return the real time of system boot.
2144 * @ts: pointer to the timespec64 to be set
2145 *
2146 * Returns the wall-time of boot in a timespec64.
2147 *
2148 * This is based on the wall_to_monotonic offset and the total suspend
2149 * time. Calls to settimeofday will affect the value returned (which
2150 * basically means that however wrong your real time clock is at boot time,
2151 * you get the right time here).
2152 */
2153void getboottime64(struct timespec64 *ts)
2154{
2155 struct timekeeper *tk = &tk_core.timekeeper;
2156 ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2157
2158 *ts = ktime_to_timespec64(t);
2159}
2160EXPORT_SYMBOL_GPL(getboottime64);
2161
2162void ktime_get_coarse_real_ts64(struct timespec64 *ts)
2163{
2164 struct timekeeper *tk = &tk_core.timekeeper;
2165 unsigned int seq;
2166
2167 do {
2168 seq = read_seqcount_begin(&tk_core.seq);
2169
2170 *ts = tk_xtime(tk);
2171 } while (read_seqcount_retry(&tk_core.seq, seq));
2172}
2173EXPORT_SYMBOL(ktime_get_coarse_real_ts64);
2174
2175void ktime_get_coarse_ts64(struct timespec64 *ts)
2176{
2177 struct timekeeper *tk = &tk_core.timekeeper;
2178 struct timespec64 now, mono;
2179 unsigned int seq;
2180
2181 do {
2182 seq = read_seqcount_begin(&tk_core.seq);
2183
2184 now = tk_xtime(tk);
2185 mono = tk->wall_to_monotonic;
2186 } while (read_seqcount_retry(&tk_core.seq, seq));
2187
2188 set_normalized_timespec64(ts, now.tv_sec + mono.tv_sec,
2189 now.tv_nsec + mono.tv_nsec);
2190}
2191EXPORT_SYMBOL(ktime_get_coarse_ts64);
2192
2193/*
2194 * Must hold jiffies_lock
2195 */
2196void do_timer(unsigned long ticks)
2197{
2198 jiffies_64 += ticks;
2199 calc_global_load();
2200}
2201
2202/**
2203 * ktime_get_update_offsets_now - hrtimer helper
2204 * @cwsseq: pointer to check and store the clock was set sequence number
2205 * @offs_real: pointer to storage for monotonic -> realtime offset
2206 * @offs_boot: pointer to storage for monotonic -> boottime offset
2207 * @offs_tai: pointer to storage for monotonic -> clock tai offset
2208 *
2209 * Returns current monotonic time and updates the offsets if the
2210 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2211 * different.
2212 *
2213 * Called from hrtimer_interrupt() or retrigger_next_event()
2214 */
2215ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2216 ktime_t *offs_boot, ktime_t *offs_tai)
2217{
2218 struct timekeeper *tk = &tk_core.timekeeper;
2219 unsigned int seq;
2220 ktime_t base;
2221 u64 nsecs;
2222
2223 do {
2224 seq = read_seqcount_begin(&tk_core.seq);
2225
2226 base = tk->tkr_mono.base;
2227 nsecs = timekeeping_get_ns(&tk->tkr_mono);
2228 base = ktime_add_ns(base, nsecs);
2229
2230 if (*cwsseq != tk->clock_was_set_seq) {
2231 *cwsseq = tk->clock_was_set_seq;
2232 *offs_real = tk->offs_real;
2233 *offs_boot = tk->offs_boot;
2234 *offs_tai = tk->offs_tai;
2235 }
2236
2237 /* Handle leapsecond insertion adjustments */
2238 if (unlikely(base >= tk->next_leap_ktime))
2239 *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2240
2241 } while (read_seqcount_retry(&tk_core.seq, seq));
2242
2243 return base;
2244}
2245
2246/**
2247 * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2248 */
2249static int timekeeping_validate_timex(const struct __kernel_timex *txc)
2250{
2251 if (txc->modes & ADJ_ADJTIME) {
2252 /* singleshot must not be used with any other mode bits */
2253 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2254 return -EINVAL;
2255 if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2256 !capable(CAP_SYS_TIME))
2257 return -EPERM;
2258 } else {
2259 /* In order to modify anything, you gotta be super-user! */
2260 if (txc->modes && !capable(CAP_SYS_TIME))
2261 return -EPERM;
2262 /*
2263 * if the quartz is off by more than 10% then
2264 * something is VERY wrong!
2265 */
2266 if (txc->modes & ADJ_TICK &&
2267 (txc->tick < 900000/USER_HZ ||
2268 txc->tick > 1100000/USER_HZ))
2269 return -EINVAL;
2270 }
2271
2272 if (txc->modes & ADJ_SETOFFSET) {
2273 /* In order to inject time, you gotta be super-user! */
2274 if (!capable(CAP_SYS_TIME))
2275 return -EPERM;
2276
2277 /*
2278 * Validate if a timespec/timeval used to inject a time
2279 * offset is valid. Offsets can be postive or negative, so
2280 * we don't check tv_sec. The value of the timeval/timespec
2281 * is the sum of its fields,but *NOTE*:
2282 * The field tv_usec/tv_nsec must always be non-negative and
2283 * we can't have more nanoseconds/microseconds than a second.
2284 */
2285 if (txc->time.tv_usec < 0)
2286 return -EINVAL;
2287
2288 if (txc->modes & ADJ_NANO) {
2289 if (txc->time.tv_usec >= NSEC_PER_SEC)
2290 return -EINVAL;
2291 } else {
2292 if (txc->time.tv_usec >= USEC_PER_SEC)
2293 return -EINVAL;
2294 }
2295 }
2296
2297 /*
2298 * Check for potential multiplication overflows that can
2299 * only happen on 64-bit systems:
2300 */
2301 if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2302 if (LLONG_MIN / PPM_SCALE > txc->freq)
2303 return -EINVAL;
2304 if (LLONG_MAX / PPM_SCALE < txc->freq)
2305 return -EINVAL;
2306 }
2307
2308 return 0;
2309}
2310
2311
2312/**
2313 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2314 */
2315int do_adjtimex(struct __kernel_timex *txc)
2316{
2317 struct timekeeper *tk = &tk_core.timekeeper;
2318 struct audit_ntp_data ad;
2319 unsigned long flags;
2320 struct timespec64 ts;
2321 s32 orig_tai, tai;
2322 int ret;
2323
2324 /* Validate the data before disabling interrupts */
2325 ret = timekeeping_validate_timex(txc);
2326 if (ret)
2327 return ret;
2328
2329 if (txc->modes & ADJ_SETOFFSET) {
2330 struct timespec64 delta;
2331 delta.tv_sec = txc->time.tv_sec;
2332 delta.tv_nsec = txc->time.tv_usec;
2333 if (!(txc->modes & ADJ_NANO))
2334 delta.tv_nsec *= 1000;
2335 ret = timekeeping_inject_offset(&delta);
2336 if (ret)
2337 return ret;
2338
2339 audit_tk_injoffset(delta);
2340 }
2341
2342 audit_ntp_init(&ad);
2343
2344 ktime_get_real_ts64(&ts);
2345
2346 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2347 write_seqcount_begin(&tk_core.seq);
2348
2349 orig_tai = tai = tk->tai_offset;
2350 ret = __do_adjtimex(txc, &ts, &tai, &ad);
2351
2352 if (tai != orig_tai) {
2353 __timekeeping_set_tai_offset(tk, tai);
2354 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2355 }
2356 tk_update_leap_state(tk);
2357
2358 write_seqcount_end(&tk_core.seq);
2359 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2360
2361 audit_ntp_log(&ad);
2362
2363 /* Update the multiplier immediately if frequency was set directly */
2364 if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
2365 timekeeping_advance(TK_ADV_FREQ);
2366
2367 if (tai != orig_tai)
2368 clock_was_set();
2369
2370 ntp_notify_cmos_timer();
2371
2372 return ret;
2373}
2374
2375#ifdef CONFIG_NTP_PPS
2376/**
2377 * hardpps() - Accessor function to NTP __hardpps function
2378 */
2379void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2380{
2381 unsigned long flags;
2382
2383 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2384 write_seqcount_begin(&tk_core.seq);
2385
2386 __hardpps(phase_ts, raw_ts);
2387
2388 write_seqcount_end(&tk_core.seq);
2389 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2390}
2391EXPORT_SYMBOL(hardpps);
2392#endif /* CONFIG_NTP_PPS */
2393
2394/**
2395 * xtime_update() - advances the timekeeping infrastructure
2396 * @ticks: number of ticks, that have elapsed since the last call.
2397 *
2398 * Must be called with interrupts disabled.
2399 */
2400void xtime_update(unsigned long ticks)
2401{
2402 raw_spin_lock(&jiffies_lock);
2403 write_seqcount_begin(&jiffies_seq);
2404 do_timer(ticks);
2405 write_seqcount_end(&jiffies_seq);
2406 raw_spin_unlock(&jiffies_lock);
2407 update_wall_time();
2408}