projects/linux·blob v4.13 · refs

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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/nmi.h>
18#include <linux/sched.h>
19#include <linux/sched/loadavg.h>
20#include <linux/syscore_ops.h>
21#include <linux/clocksource.h>
22#include <linux/jiffies.h>
23#include <linux/time.h>
24#include <linux/tick.h>
25#include <linux/stop_machine.h>
26#include <linux/pvclock_gtod.h>
27#include <linux/compiler.h>
28
29#include "tick-internal.h"
30#include "ntp_internal.h"
31#include "timekeeping_internal.h"
32
33#define TK_CLEAR_NTP (1 << 0)
34#define TK_MIRROR (1 << 1)
35#define TK_CLOCK_WAS_SET (1 << 2)
36
37/*
38 * The most important data for readout fits into a single 64 byte
39 * cache line.
40 */
41static struct {
42 seqcount_t seq;
43 struct timekeeper timekeeper;
44} tk_core ____cacheline_aligned;
45
46static DEFINE_RAW_SPINLOCK(timekeeper_lock);
47static struct timekeeper shadow_timekeeper;
48
49/**
50 * struct tk_fast - NMI safe timekeeper
51 * @seq: Sequence counter for protecting updates. The lowest bit
52 * is the index for the tk_read_base array
53 * @base: tk_read_base array. Access is indexed by the lowest bit of
54 * @seq.
55 *
56 * See @update_fast_timekeeper() below.
57 */
58struct tk_fast {
59 seqcount_t seq;
60 struct tk_read_base base[2];
61};
62
63static struct tk_fast tk_fast_mono ____cacheline_aligned;
64static struct tk_fast tk_fast_raw ____cacheline_aligned;
65
66/* flag for if timekeeping is suspended */
67int __read_mostly timekeeping_suspended;
68
69static inline void tk_normalize_xtime(struct timekeeper *tk)
70{
71 while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
72 tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
73 tk->xtime_sec++;
74 }
75 while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) {
76 tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
77 tk->raw_sec++;
78 }
79}
80
81static inline struct timespec64 tk_xtime(struct timekeeper *tk)
82{
83 struct timespec64 ts;
84
85 ts.tv_sec = tk->xtime_sec;
86 ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
87 return ts;
88}
89
90static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
91{
92 tk->xtime_sec = ts->tv_sec;
93 tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
94}
95
96static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts)
97{
98 tk->xtime_sec += ts->tv_sec;
99 tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift;
100 tk_normalize_xtime(tk);
101}
102
103static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
104{
105 struct timespec64 tmp;
106
107 /*
108 * Verify consistency of: offset_real = -wall_to_monotonic
109 * before modifying anything
110 */
111 set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
112 -tk->wall_to_monotonic.tv_nsec);
113 WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp));
114 tk->wall_to_monotonic = wtm;
115 set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
116 tk->offs_real = timespec64_to_ktime(tmp);
117 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
118}
119
120static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
121{
122 tk->offs_boot = ktime_add(tk->offs_boot, delta);
123}
124
125/*
126 * tk_clock_read - atomic clocksource read() helper
127 *
128 * This helper is necessary to use in the read paths because, while the
129 * seqlock ensures we don't return a bad value while structures are updated,
130 * it doesn't protect from potential crashes. There is the possibility that
131 * the tkr's clocksource may change between the read reference, and the
132 * clock reference passed to the read function. This can cause crashes if
133 * the wrong clocksource is passed to the wrong read function.
134 * This isn't necessary to use when holding the timekeeper_lock or doing
135 * a read of the fast-timekeeper tkrs (which is protected by its own locking
136 * and update logic).
137 */
138static inline u64 tk_clock_read(struct tk_read_base *tkr)
139{
140 struct clocksource *clock = READ_ONCE(tkr->clock);
141
142 return clock->read(clock);
143}
144
145#ifdef CONFIG_DEBUG_TIMEKEEPING
146#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
147
148static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
149{
150
151 u64 max_cycles = tk->tkr_mono.clock->max_cycles;
152 const char *name = tk->tkr_mono.clock->name;
153
154 if (offset > max_cycles) {
155 printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
156 offset, name, max_cycles);
157 printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
158 } else {
159 if (offset > (max_cycles >> 1)) {
160 printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
161 offset, name, max_cycles >> 1);
162 printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
163 }
164 }
165
166 if (tk->underflow_seen) {
167 if (jiffies - tk->last_warning > WARNING_FREQ) {
168 printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
169 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
170 printk_deferred(" Your kernel is probably still fine.\n");
171 tk->last_warning = jiffies;
172 }
173 tk->underflow_seen = 0;
174 }
175
176 if (tk->overflow_seen) {
177 if (jiffies - tk->last_warning > WARNING_FREQ) {
178 printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
179 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
180 printk_deferred(" Your kernel is probably still fine.\n");
181 tk->last_warning = jiffies;
182 }
183 tk->overflow_seen = 0;
184 }
185}
186
187static inline u64 timekeeping_get_delta(struct tk_read_base *tkr)
188{
189 struct timekeeper *tk = &tk_core.timekeeper;
190 u64 now, last, mask, max, delta;
191 unsigned int seq;
192
193 /*
194 * Since we're called holding a seqlock, the data may shift
195 * under us while we're doing the calculation. This can cause
196 * false positives, since we'd note a problem but throw the
197 * results away. So nest another seqlock here to atomically
198 * grab the points we are checking with.
199 */
200 do {
201 seq = read_seqcount_begin(&tk_core.seq);
202 now = tk_clock_read(tkr);
203 last = tkr->cycle_last;
204 mask = tkr->mask;
205 max = tkr->clock->max_cycles;
206 } while (read_seqcount_retry(&tk_core.seq, seq));
207
208 delta = clocksource_delta(now, last, mask);
209
210 /*
211 * Try to catch underflows by checking if we are seeing small
212 * mask-relative negative values.
213 */
214 if (unlikely((~delta & mask) < (mask >> 3))) {
215 tk->underflow_seen = 1;
216 delta = 0;
217 }
218
219 /* Cap delta value to the max_cycles values to avoid mult overflows */
220 if (unlikely(delta > max)) {
221 tk->overflow_seen = 1;
222 delta = tkr->clock->max_cycles;
223 }
224
225 return delta;
226}
227#else
228static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
229{
230}
231static inline u64 timekeeping_get_delta(struct tk_read_base *tkr)
232{
233 u64 cycle_now, delta;
234
235 /* read clocksource */
236 cycle_now = tk_clock_read(tkr);
237
238 /* calculate the delta since the last update_wall_time */
239 delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
240
241 return delta;
242}
243#endif
244
245/**
246 * tk_setup_internals - Set up internals to use clocksource clock.
247 *
248 * @tk: The target timekeeper to setup.
249 * @clock: Pointer to clocksource.
250 *
251 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
252 * pair and interval request.
253 *
254 * Unless you're the timekeeping code, you should not be using this!
255 */
256static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
257{
258 u64 interval;
259 u64 tmp, ntpinterval;
260 struct clocksource *old_clock;
261
262 ++tk->cs_was_changed_seq;
263 old_clock = tk->tkr_mono.clock;
264 tk->tkr_mono.clock = clock;
265 tk->tkr_mono.mask = clock->mask;
266 tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono);
267
268 tk->tkr_raw.clock = clock;
269 tk->tkr_raw.mask = clock->mask;
270 tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
271
272 /* Do the ns -> cycle conversion first, using original mult */
273 tmp = NTP_INTERVAL_LENGTH;
274 tmp <<= clock->shift;
275 ntpinterval = tmp;
276 tmp += clock->mult/2;
277 do_div(tmp, clock->mult);
278 if (tmp == 0)
279 tmp = 1;
280
281 interval = (u64) tmp;
282 tk->cycle_interval = interval;
283
284 /* Go back from cycles -> shifted ns */
285 tk->xtime_interval = interval * clock->mult;
286 tk->xtime_remainder = ntpinterval - tk->xtime_interval;
287 tk->raw_interval = interval * clock->mult;
288
289 /* if changing clocks, convert xtime_nsec shift units */
290 if (old_clock) {
291 int shift_change = clock->shift - old_clock->shift;
292 if (shift_change < 0) {
293 tk->tkr_mono.xtime_nsec >>= -shift_change;
294 tk->tkr_raw.xtime_nsec >>= -shift_change;
295 } else {
296 tk->tkr_mono.xtime_nsec <<= shift_change;
297 tk->tkr_raw.xtime_nsec <<= shift_change;
298 }
299 }
300
301 tk->tkr_mono.shift = clock->shift;
302 tk->tkr_raw.shift = clock->shift;
303
304 tk->ntp_error = 0;
305 tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
306 tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
307
308 /*
309 * The timekeeper keeps its own mult values for the currently
310 * active clocksource. These value will be adjusted via NTP
311 * to counteract clock drifting.
312 */
313 tk->tkr_mono.mult = clock->mult;
314 tk->tkr_raw.mult = clock->mult;
315 tk->ntp_err_mult = 0;
316}
317
318/* Timekeeper helper functions. */
319
320#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
321static u32 default_arch_gettimeoffset(void) { return 0; }
322u32 (*arch_gettimeoffset)(void) = default_arch_gettimeoffset;
323#else
324static inline u32 arch_gettimeoffset(void) { return 0; }
325#endif
326
327static inline u64 timekeeping_delta_to_ns(struct tk_read_base *tkr, u64 delta)
328{
329 u64 nsec;
330
331 nsec = delta * tkr->mult + tkr->xtime_nsec;
332 nsec >>= tkr->shift;
333
334 /* If arch requires, add in get_arch_timeoffset() */
335 return nsec + arch_gettimeoffset();
336}
337
338static inline u64 timekeeping_get_ns(struct tk_read_base *tkr)
339{
340 u64 delta;
341
342 delta = timekeeping_get_delta(tkr);
343 return timekeeping_delta_to_ns(tkr, delta);
344}
345
346static inline u64 timekeeping_cycles_to_ns(struct tk_read_base *tkr, u64 cycles)
347{
348 u64 delta;
349
350 /* calculate the delta since the last update_wall_time */
351 delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
352 return timekeeping_delta_to_ns(tkr, delta);
353}
354
355/**
356 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
357 * @tkr: Timekeeping readout base from which we take the update
358 *
359 * We want to use this from any context including NMI and tracing /
360 * instrumenting the timekeeping code itself.
361 *
362 * Employ the latch technique; see @raw_write_seqcount_latch.
363 *
364 * So if a NMI hits the update of base[0] then it will use base[1]
365 * which is still consistent. In the worst case this can result is a
366 * slightly wrong timestamp (a few nanoseconds). See
367 * @ktime_get_mono_fast_ns.
368 */
369static void update_fast_timekeeper(struct tk_read_base *tkr, struct tk_fast *tkf)
370{
371 struct tk_read_base *base = tkf->base;
372
373 /* Force readers off to base[1] */
374 raw_write_seqcount_latch(&tkf->seq);
375
376 /* Update base[0] */
377 memcpy(base, tkr, sizeof(*base));
378
379 /* Force readers back to base[0] */
380 raw_write_seqcount_latch(&tkf->seq);
381
382 /* Update base[1] */
383 memcpy(base + 1, base, sizeof(*base));
384}
385
386/**
387 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
388 *
389 * This timestamp is not guaranteed to be monotonic across an update.
390 * The timestamp is calculated by:
391 *
392 * now = base_mono + clock_delta * slope
393 *
394 * So if the update lowers the slope, readers who are forced to the
395 * not yet updated second array are still using the old steeper slope.
396 *
397 * tmono
398 * ^
399 * | o n
400 * | o n
401 * | u
402 * | o
403 * |o
404 * |12345678---> reader order
405 *
406 * o = old slope
407 * u = update
408 * n = new slope
409 *
410 * So reader 6 will observe time going backwards versus reader 5.
411 *
412 * While other CPUs are likely to be able observe that, the only way
413 * for a CPU local observation is when an NMI hits in the middle of
414 * the update. Timestamps taken from that NMI context might be ahead
415 * of the following timestamps. Callers need to be aware of that and
416 * deal with it.
417 */
418static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
419{
420 struct tk_read_base *tkr;
421 unsigned int seq;
422 u64 now;
423
424 do {
425 seq = raw_read_seqcount_latch(&tkf->seq);
426 tkr = tkf->base + (seq & 0x01);
427 now = ktime_to_ns(tkr->base);
428
429 now += timekeeping_delta_to_ns(tkr,
430 clocksource_delta(
431 tk_clock_read(tkr),
432 tkr->cycle_last,
433 tkr->mask));
434 } while (read_seqcount_retry(&tkf->seq, seq));
435
436 return now;
437}
438
439u64 ktime_get_mono_fast_ns(void)
440{
441 return __ktime_get_fast_ns(&tk_fast_mono);
442}
443EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
444
445u64 ktime_get_raw_fast_ns(void)
446{
447 return __ktime_get_fast_ns(&tk_fast_raw);
448}
449EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
450
451/**
452 * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
453 *
454 * To keep it NMI safe since we're accessing from tracing, we're not using a
455 * separate timekeeper with updates to monotonic clock and boot offset
456 * protected with seqlocks. This has the following minor side effects:
457 *
458 * (1) Its possible that a timestamp be taken after the boot offset is updated
459 * but before the timekeeper is updated. If this happens, the new boot offset
460 * is added to the old timekeeping making the clock appear to update slightly
461 * earlier:
462 * CPU 0 CPU 1
463 * timekeeping_inject_sleeptime64()
464 * __timekeeping_inject_sleeptime(tk, delta);
465 * timestamp();
466 * timekeeping_update(tk, TK_CLEAR_NTP...);
467 *
468 * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
469 * partially updated. Since the tk->offs_boot update is a rare event, this
470 * should be a rare occurrence which postprocessing should be able to handle.
471 */
472u64 notrace ktime_get_boot_fast_ns(void)
473{
474 struct timekeeper *tk = &tk_core.timekeeper;
475
476 return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot));
477}
478EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
479
480/* Suspend-time cycles value for halted fast timekeeper. */
481static u64 cycles_at_suspend;
482
483static u64 dummy_clock_read(struct clocksource *cs)
484{
485 return cycles_at_suspend;
486}
487
488static struct clocksource dummy_clock = {
489 .read = dummy_clock_read,
490};
491
492/**
493 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
494 * @tk: Timekeeper to snapshot.
495 *
496 * It generally is unsafe to access the clocksource after timekeeping has been
497 * suspended, so take a snapshot of the readout base of @tk and use it as the
498 * fast timekeeper's readout base while suspended. It will return the same
499 * number of cycles every time until timekeeping is resumed at which time the
500 * proper readout base for the fast timekeeper will be restored automatically.
501 */
502static void halt_fast_timekeeper(struct timekeeper *tk)
503{
504 static struct tk_read_base tkr_dummy;
505 struct tk_read_base *tkr = &tk->tkr_mono;
506
507 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
508 cycles_at_suspend = tk_clock_read(tkr);
509 tkr_dummy.clock = &dummy_clock;
510 update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
511
512 tkr = &tk->tkr_raw;
513 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
514 tkr_dummy.clock = &dummy_clock;
515 update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
516}
517
518#ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
519#warning Please contact your maintainers, as GENERIC_TIME_VSYSCALL_OLD compatibity will disappear soon.
520
521static inline void update_vsyscall(struct timekeeper *tk)
522{
523 struct timespec xt, wm;
524
525 xt = timespec64_to_timespec(tk_xtime(tk));
526 wm = timespec64_to_timespec(tk->wall_to_monotonic);
527 update_vsyscall_old(&xt, &wm, tk->tkr_mono.clock, tk->tkr_mono.mult,
528 tk->tkr_mono.cycle_last);
529}
530
531static inline void old_vsyscall_fixup(struct timekeeper *tk)
532{
533 s64 remainder;
534
535 /*
536 * Store only full nanoseconds into xtime_nsec after rounding
537 * it up and add the remainder to the error difference.
538 * XXX - This is necessary to avoid small 1ns inconsistnecies caused
539 * by truncating the remainder in vsyscalls. However, it causes
540 * additional work to be done in timekeeping_adjust(). Once
541 * the vsyscall implementations are converted to use xtime_nsec
542 * (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
543 * users are removed, this can be killed.
544 */
545 remainder = tk->tkr_mono.xtime_nsec & ((1ULL << tk->tkr_mono.shift) - 1);
546 if (remainder != 0) {
547 tk->tkr_mono.xtime_nsec -= remainder;
548 tk->tkr_mono.xtime_nsec += 1ULL << tk->tkr_mono.shift;
549 tk->ntp_error += remainder << tk->ntp_error_shift;
550 tk->ntp_error -= (1ULL << tk->tkr_mono.shift) << tk->ntp_error_shift;
551 }
552}
553#else
554#define old_vsyscall_fixup(tk)
555#endif
556
557static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
558
559static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
560{
561 raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
562}
563
564/**
565 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
566 */
567int pvclock_gtod_register_notifier(struct notifier_block *nb)
568{
569 struct timekeeper *tk = &tk_core.timekeeper;
570 unsigned long flags;
571 int ret;
572
573 raw_spin_lock_irqsave(&timekeeper_lock, flags);
574 ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
575 update_pvclock_gtod(tk, true);
576 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
577
578 return ret;
579}
580EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
581
582/**
583 * pvclock_gtod_unregister_notifier - unregister a pvclock
584 * timedata update listener
585 */
586int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
587{
588 unsigned long flags;
589 int ret;
590
591 raw_spin_lock_irqsave(&timekeeper_lock, flags);
592 ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
593 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
594
595 return ret;
596}
597EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
598
599/*
600 * tk_update_leap_state - helper to update the next_leap_ktime
601 */
602static inline void tk_update_leap_state(struct timekeeper *tk)
603{
604 tk->next_leap_ktime = ntp_get_next_leap();
605 if (tk->next_leap_ktime != KTIME_MAX)
606 /* Convert to monotonic time */
607 tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
608}
609
610/*
611 * Update the ktime_t based scalar nsec members of the timekeeper
612 */
613static inline void tk_update_ktime_data(struct timekeeper *tk)
614{
615 u64 seconds;
616 u32 nsec;
617
618 /*
619 * The xtime based monotonic readout is:
620 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
621 * The ktime based monotonic readout is:
622 * nsec = base_mono + now();
623 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
624 */
625 seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
626 nsec = (u32) tk->wall_to_monotonic.tv_nsec;
627 tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
628
629 /*
630 * The sum of the nanoseconds portions of xtime and
631 * wall_to_monotonic can be greater/equal one second. Take
632 * this into account before updating tk->ktime_sec.
633 */
634 nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
635 if (nsec >= NSEC_PER_SEC)
636 seconds++;
637 tk->ktime_sec = seconds;
638
639 /* Update the monotonic raw base */
640 tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
641}
642
643/* must hold timekeeper_lock */
644static void timekeeping_update(struct timekeeper *tk, unsigned int action)
645{
646 if (action & TK_CLEAR_NTP) {
647 tk->ntp_error = 0;
648 ntp_clear();
649 }
650
651 tk_update_leap_state(tk);
652 tk_update_ktime_data(tk);
653
654 update_vsyscall(tk);
655 update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
656
657 update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
658 update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
659
660 if (action & TK_CLOCK_WAS_SET)
661 tk->clock_was_set_seq++;
662 /*
663 * The mirroring of the data to the shadow-timekeeper needs
664 * to happen last here to ensure we don't over-write the
665 * timekeeper structure on the next update with stale data
666 */
667 if (action & TK_MIRROR)
668 memcpy(&shadow_timekeeper, &tk_core.timekeeper,
669 sizeof(tk_core.timekeeper));
670}
671
672/**
673 * timekeeping_forward_now - update clock to the current time
674 *
675 * Forward the current clock to update its state since the last call to
676 * update_wall_time(). This is useful before significant clock changes,
677 * as it avoids having to deal with this time offset explicitly.
678 */
679static void timekeeping_forward_now(struct timekeeper *tk)
680{
681 u64 cycle_now, delta;
682
683 cycle_now = tk_clock_read(&tk->tkr_mono);
684 delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
685 tk->tkr_mono.cycle_last = cycle_now;
686 tk->tkr_raw.cycle_last = cycle_now;
687
688 tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
689
690 /* If arch requires, add in get_arch_timeoffset() */
691 tk->tkr_mono.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_mono.shift;
692
693
694 tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
695
696 /* If arch requires, add in get_arch_timeoffset() */
697 tk->tkr_raw.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_raw.shift;
698
699 tk_normalize_xtime(tk);
700}
701
702/**
703 * __getnstimeofday64 - Returns the time of day in a timespec64.
704 * @ts: pointer to the timespec to be set
705 *
706 * Updates the time of day in the timespec.
707 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
708 */
709int __getnstimeofday64(struct timespec64 *ts)
710{
711 struct timekeeper *tk = &tk_core.timekeeper;
712 unsigned long seq;
713 u64 nsecs;
714
715 do {
716 seq = read_seqcount_begin(&tk_core.seq);
717
718 ts->tv_sec = tk->xtime_sec;
719 nsecs = timekeeping_get_ns(&tk->tkr_mono);
720
721 } while (read_seqcount_retry(&tk_core.seq, seq));
722
723 ts->tv_nsec = 0;
724 timespec64_add_ns(ts, nsecs);
725
726 /*
727 * Do not bail out early, in case there were callers still using
728 * the value, even in the face of the WARN_ON.
729 */
730 if (unlikely(timekeeping_suspended))
731 return -EAGAIN;
732 return 0;
733}
734EXPORT_SYMBOL(__getnstimeofday64);
735
736/**
737 * getnstimeofday64 - Returns the time of day in a timespec64.
738 * @ts: pointer to the timespec64 to be set
739 *
740 * Returns the time of day in a timespec64 (WARN if suspended).
741 */
742void getnstimeofday64(struct timespec64 *ts)
743{
744 WARN_ON(__getnstimeofday64(ts));
745}
746EXPORT_SYMBOL(getnstimeofday64);
747
748ktime_t ktime_get(void)
749{
750 struct timekeeper *tk = &tk_core.timekeeper;
751 unsigned int seq;
752 ktime_t base;
753 u64 nsecs;
754
755 WARN_ON(timekeeping_suspended);
756
757 do {
758 seq = read_seqcount_begin(&tk_core.seq);
759 base = tk->tkr_mono.base;
760 nsecs = timekeeping_get_ns(&tk->tkr_mono);
761
762 } while (read_seqcount_retry(&tk_core.seq, seq));
763
764 return ktime_add_ns(base, nsecs);
765}
766EXPORT_SYMBOL_GPL(ktime_get);
767
768u32 ktime_get_resolution_ns(void)
769{
770 struct timekeeper *tk = &tk_core.timekeeper;
771 unsigned int seq;
772 u32 nsecs;
773
774 WARN_ON(timekeeping_suspended);
775
776 do {
777 seq = read_seqcount_begin(&tk_core.seq);
778 nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
779 } while (read_seqcount_retry(&tk_core.seq, seq));
780
781 return nsecs;
782}
783EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
784
785static ktime_t *offsets[TK_OFFS_MAX] = {
786 [TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
787 [TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
788 [TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai,
789};
790
791ktime_t ktime_get_with_offset(enum tk_offsets offs)
792{
793 struct timekeeper *tk = &tk_core.timekeeper;
794 unsigned int seq;
795 ktime_t base, *offset = offsets[offs];
796 u64 nsecs;
797
798 WARN_ON(timekeeping_suspended);
799
800 do {
801 seq = read_seqcount_begin(&tk_core.seq);
802 base = ktime_add(tk->tkr_mono.base, *offset);
803 nsecs = timekeeping_get_ns(&tk->tkr_mono);
804
805 } while (read_seqcount_retry(&tk_core.seq, seq));
806
807 return ktime_add_ns(base, nsecs);
808
809}
810EXPORT_SYMBOL_GPL(ktime_get_with_offset);
811
812/**
813 * ktime_mono_to_any() - convert mononotic time to any other time
814 * @tmono: time to convert.
815 * @offs: which offset to use
816 */
817ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
818{
819 ktime_t *offset = offsets[offs];
820 unsigned long seq;
821 ktime_t tconv;
822
823 do {
824 seq = read_seqcount_begin(&tk_core.seq);
825 tconv = ktime_add(tmono, *offset);
826 } while (read_seqcount_retry(&tk_core.seq, seq));
827
828 return tconv;
829}
830EXPORT_SYMBOL_GPL(ktime_mono_to_any);
831
832/**
833 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
834 */
835ktime_t ktime_get_raw(void)
836{
837 struct timekeeper *tk = &tk_core.timekeeper;
838 unsigned int seq;
839 ktime_t base;
840 u64 nsecs;
841
842 do {
843 seq = read_seqcount_begin(&tk_core.seq);
844 base = tk->tkr_raw.base;
845 nsecs = timekeeping_get_ns(&tk->tkr_raw);
846
847 } while (read_seqcount_retry(&tk_core.seq, seq));
848
849 return ktime_add_ns(base, nsecs);
850}
851EXPORT_SYMBOL_GPL(ktime_get_raw);
852
853/**
854 * ktime_get_ts64 - get the monotonic clock in timespec64 format
855 * @ts: pointer to timespec variable
856 *
857 * The function calculates the monotonic clock from the realtime
858 * clock and the wall_to_monotonic offset and stores the result
859 * in normalized timespec64 format in the variable pointed to by @ts.
860 */
861void ktime_get_ts64(struct timespec64 *ts)
862{
863 struct timekeeper *tk = &tk_core.timekeeper;
864 struct timespec64 tomono;
865 unsigned int seq;
866 u64 nsec;
867
868 WARN_ON(timekeeping_suspended);
869
870 do {
871 seq = read_seqcount_begin(&tk_core.seq);
872 ts->tv_sec = tk->xtime_sec;
873 nsec = timekeeping_get_ns(&tk->tkr_mono);
874 tomono = tk->wall_to_monotonic;
875
876 } while (read_seqcount_retry(&tk_core.seq, seq));
877
878 ts->tv_sec += tomono.tv_sec;
879 ts->tv_nsec = 0;
880 timespec64_add_ns(ts, nsec + tomono.tv_nsec);
881}
882EXPORT_SYMBOL_GPL(ktime_get_ts64);
883
884/**
885 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
886 *
887 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
888 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
889 * works on both 32 and 64 bit systems. On 32 bit systems the readout
890 * covers ~136 years of uptime which should be enough to prevent
891 * premature wrap arounds.
892 */
893time64_t ktime_get_seconds(void)
894{
895 struct timekeeper *tk = &tk_core.timekeeper;
896
897 WARN_ON(timekeeping_suspended);
898 return tk->ktime_sec;
899}
900EXPORT_SYMBOL_GPL(ktime_get_seconds);
901
902/**
903 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
904 *
905 * Returns the wall clock seconds since 1970. This replaces the
906 * get_seconds() interface which is not y2038 safe on 32bit systems.
907 *
908 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
909 * 32bit systems the access must be protected with the sequence
910 * counter to provide "atomic" access to the 64bit tk->xtime_sec
911 * value.
912 */
913time64_t ktime_get_real_seconds(void)
914{
915 struct timekeeper *tk = &tk_core.timekeeper;
916 time64_t seconds;
917 unsigned int seq;
918
919 if (IS_ENABLED(CONFIG_64BIT))
920 return tk->xtime_sec;
921
922 do {
923 seq = read_seqcount_begin(&tk_core.seq);
924 seconds = tk->xtime_sec;
925
926 } while (read_seqcount_retry(&tk_core.seq, seq));
927
928 return seconds;
929}
930EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
931
932/**
933 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
934 * but without the sequence counter protect. This internal function
935 * is called just when timekeeping lock is already held.
936 */
937time64_t __ktime_get_real_seconds(void)
938{
939 struct timekeeper *tk = &tk_core.timekeeper;
940
941 return tk->xtime_sec;
942}
943
944/**
945 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
946 * @systime_snapshot: pointer to struct receiving the system time snapshot
947 */
948void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
949{
950 struct timekeeper *tk = &tk_core.timekeeper;
951 unsigned long seq;
952 ktime_t base_raw;
953 ktime_t base_real;
954 u64 nsec_raw;
955 u64 nsec_real;
956 u64 now;
957
958 WARN_ON_ONCE(timekeeping_suspended);
959
960 do {
961 seq = read_seqcount_begin(&tk_core.seq);
962 now = tk_clock_read(&tk->tkr_mono);
963 systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
964 systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
965 base_real = ktime_add(tk->tkr_mono.base,
966 tk_core.timekeeper.offs_real);
967 base_raw = tk->tkr_raw.base;
968 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
969 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
970 } while (read_seqcount_retry(&tk_core.seq, seq));
971
972 systime_snapshot->cycles = now;
973 systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
974 systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
975}
976EXPORT_SYMBOL_GPL(ktime_get_snapshot);
977
978/* Scale base by mult/div checking for overflow */
979static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
980{
981 u64 tmp, rem;
982
983 tmp = div64_u64_rem(*base, div, &rem);
984
985 if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
986 ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
987 return -EOVERFLOW;
988 tmp *= mult;
989 rem *= mult;
990
991 do_div(rem, div);
992 *base = tmp + rem;
993 return 0;
994}
995
996/**
997 * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
998 * @history: Snapshot representing start of history
999 * @partial_history_cycles: Cycle offset into history (fractional part)
1000 * @total_history_cycles: Total history length in cycles
1001 * @discontinuity: True indicates clock was set on history period
1002 * @ts: Cross timestamp that should be adjusted using
1003 * partial/total ratio
1004 *
1005 * Helper function used by get_device_system_crosststamp() to correct the
1006 * crosstimestamp corresponding to the start of the current interval to the
1007 * system counter value (timestamp point) provided by the driver. The
1008 * total_history_* quantities are the total history starting at the provided
1009 * reference point and ending at the start of the current interval. The cycle
1010 * count between the driver timestamp point and the start of the current
1011 * interval is partial_history_cycles.
1012 */
1013static int adjust_historical_crosststamp(struct system_time_snapshot *history,
1014 u64 partial_history_cycles,
1015 u64 total_history_cycles,
1016 bool discontinuity,
1017 struct system_device_crosststamp *ts)
1018{
1019 struct timekeeper *tk = &tk_core.timekeeper;
1020 u64 corr_raw, corr_real;
1021 bool interp_forward;
1022 int ret;
1023
1024 if (total_history_cycles == 0 || partial_history_cycles == 0)
1025 return 0;
1026
1027 /* Interpolate shortest distance from beginning or end of history */
1028 interp_forward = partial_history_cycles > total_history_cycles / 2;
1029 partial_history_cycles = interp_forward ?
1030 total_history_cycles - partial_history_cycles :
1031 partial_history_cycles;
1032
1033 /*
1034 * Scale the monotonic raw time delta by:
1035 * partial_history_cycles / total_history_cycles
1036 */
1037 corr_raw = (u64)ktime_to_ns(
1038 ktime_sub(ts->sys_monoraw, history->raw));
1039 ret = scale64_check_overflow(partial_history_cycles,
1040 total_history_cycles, &corr_raw);
1041 if (ret)
1042 return ret;
1043
1044 /*
1045 * If there is a discontinuity in the history, scale monotonic raw
1046 * correction by:
1047 * mult(real)/mult(raw) yielding the realtime correction
1048 * Otherwise, calculate the realtime correction similar to monotonic
1049 * raw calculation
1050 */
1051 if (discontinuity) {
1052 corr_real = mul_u64_u32_div
1053 (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1054 } else {
1055 corr_real = (u64)ktime_to_ns(
1056 ktime_sub(ts->sys_realtime, history->real));
1057 ret = scale64_check_overflow(partial_history_cycles,
1058 total_history_cycles, &corr_real);
1059 if (ret)
1060 return ret;
1061 }
1062
1063 /* Fixup monotonic raw and real time time values */
1064 if (interp_forward) {
1065 ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1066 ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1067 } else {
1068 ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1069 ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1070 }
1071
1072 return 0;
1073}
1074
1075/*
1076 * cycle_between - true if test occurs chronologically between before and after
1077 */
1078static bool cycle_between(u64 before, u64 test, u64 after)
1079{
1080 if (test > before && test < after)
1081 return true;
1082 if (test < before && before > after)
1083 return true;
1084 return false;
1085}
1086
1087/**
1088 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1089 * @get_time_fn: Callback to get simultaneous device time and
1090 * system counter from the device driver
1091 * @ctx: Context passed to get_time_fn()
1092 * @history_begin: Historical reference point used to interpolate system
1093 * time when counter provided by the driver is before the current interval
1094 * @xtstamp: Receives simultaneously captured system and device time
1095 *
1096 * Reads a timestamp from a device and correlates it to system time
1097 */
1098int get_device_system_crosststamp(int (*get_time_fn)
1099 (ktime_t *device_time,
1100 struct system_counterval_t *sys_counterval,
1101 void *ctx),
1102 void *ctx,
1103 struct system_time_snapshot *history_begin,
1104 struct system_device_crosststamp *xtstamp)
1105{
1106 struct system_counterval_t system_counterval;
1107 struct timekeeper *tk = &tk_core.timekeeper;
1108 u64 cycles, now, interval_start;
1109 unsigned int clock_was_set_seq = 0;
1110 ktime_t base_real, base_raw;
1111 u64 nsec_real, nsec_raw;
1112 u8 cs_was_changed_seq;
1113 unsigned long seq;
1114 bool do_interp;
1115 int ret;
1116
1117 do {
1118 seq = read_seqcount_begin(&tk_core.seq);
1119 /*
1120 * Try to synchronously capture device time and a system
1121 * counter value calling back into the device driver
1122 */
1123 ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1124 if (ret)
1125 return ret;
1126
1127 /*
1128 * Verify that the clocksource associated with the captured
1129 * system counter value is the same as the currently installed
1130 * timekeeper clocksource
1131 */
1132 if (tk->tkr_mono.clock != system_counterval.cs)
1133 return -ENODEV;
1134 cycles = system_counterval.cycles;
1135
1136 /*
1137 * Check whether the system counter value provided by the
1138 * device driver is on the current timekeeping interval.
1139 */
1140 now = tk_clock_read(&tk->tkr_mono);
1141 interval_start = tk->tkr_mono.cycle_last;
1142 if (!cycle_between(interval_start, cycles, now)) {
1143 clock_was_set_seq = tk->clock_was_set_seq;
1144 cs_was_changed_seq = tk->cs_was_changed_seq;
1145 cycles = interval_start;
1146 do_interp = true;
1147 } else {
1148 do_interp = false;
1149 }
1150
1151 base_real = ktime_add(tk->tkr_mono.base,
1152 tk_core.timekeeper.offs_real);
1153 base_raw = tk->tkr_raw.base;
1154
1155 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1156 system_counterval.cycles);
1157 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1158 system_counterval.cycles);
1159 } while (read_seqcount_retry(&tk_core.seq, seq));
1160
1161 xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1162 xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1163
1164 /*
1165 * Interpolate if necessary, adjusting back from the start of the
1166 * current interval
1167 */
1168 if (do_interp) {
1169 u64 partial_history_cycles, total_history_cycles;
1170 bool discontinuity;
1171
1172 /*
1173 * Check that the counter value occurs after the provided
1174 * history reference and that the history doesn't cross a
1175 * clocksource change
1176 */
1177 if (!history_begin ||
1178 !cycle_between(history_begin->cycles,
1179 system_counterval.cycles, cycles) ||
1180 history_begin->cs_was_changed_seq != cs_was_changed_seq)
1181 return -EINVAL;
1182 partial_history_cycles = cycles - system_counterval.cycles;
1183 total_history_cycles = cycles - history_begin->cycles;
1184 discontinuity =
1185 history_begin->clock_was_set_seq != clock_was_set_seq;
1186
1187 ret = adjust_historical_crosststamp(history_begin,
1188 partial_history_cycles,
1189 total_history_cycles,
1190 discontinuity, xtstamp);
1191 if (ret)
1192 return ret;
1193 }
1194
1195 return 0;
1196}
1197EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1198
1199/**
1200 * do_gettimeofday - Returns the time of day in a timeval
1201 * @tv: pointer to the timeval to be set
1202 *
1203 * NOTE: Users should be converted to using getnstimeofday()
1204 */
1205void do_gettimeofday(struct timeval *tv)
1206{
1207 struct timespec64 now;
1208
1209 getnstimeofday64(&now);
1210 tv->tv_sec = now.tv_sec;
1211 tv->tv_usec = now.tv_nsec/1000;
1212}
1213EXPORT_SYMBOL(do_gettimeofday);
1214
1215/**
1216 * do_settimeofday64 - Sets the time of day.
1217 * @ts: pointer to the timespec64 variable containing the new time
1218 *
1219 * Sets the time of day to the new time and update NTP and notify hrtimers
1220 */
1221int do_settimeofday64(const struct timespec64 *ts)
1222{
1223 struct timekeeper *tk = &tk_core.timekeeper;
1224 struct timespec64 ts_delta, xt;
1225 unsigned long flags;
1226 int ret = 0;
1227
1228 if (!timespec64_valid_strict(ts))
1229 return -EINVAL;
1230
1231 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1232 write_seqcount_begin(&tk_core.seq);
1233
1234 timekeeping_forward_now(tk);
1235
1236 xt = tk_xtime(tk);
1237 ts_delta.tv_sec = ts->tv_sec - xt.tv_sec;
1238 ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec;
1239
1240 if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1241 ret = -EINVAL;
1242 goto out;
1243 }
1244
1245 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1246
1247 tk_set_xtime(tk, ts);
1248out:
1249 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1250
1251 write_seqcount_end(&tk_core.seq);
1252 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1253
1254 /* signal hrtimers about time change */
1255 clock_was_set();
1256
1257 return ret;
1258}
1259EXPORT_SYMBOL(do_settimeofday64);
1260
1261/**
1262 * timekeeping_inject_offset - Adds or subtracts from the current time.
1263 * @tv: pointer to the timespec variable containing the offset
1264 *
1265 * Adds or subtracts an offset value from the current time.
1266 */
1267int timekeeping_inject_offset(struct timespec *ts)
1268{
1269 struct timekeeper *tk = &tk_core.timekeeper;
1270 unsigned long flags;
1271 struct timespec64 ts64, tmp;
1272 int ret = 0;
1273
1274 if (!timespec_inject_offset_valid(ts))
1275 return -EINVAL;
1276
1277 ts64 = timespec_to_timespec64(*ts);
1278
1279 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1280 write_seqcount_begin(&tk_core.seq);
1281
1282 timekeeping_forward_now(tk);
1283
1284 /* Make sure the proposed value is valid */
1285 tmp = timespec64_add(tk_xtime(tk), ts64);
1286 if (timespec64_compare(&tk->wall_to_monotonic, &ts64) > 0 ||
1287 !timespec64_valid_strict(&tmp)) {
1288 ret = -EINVAL;
1289 goto error;
1290 }
1291
1292 tk_xtime_add(tk, &ts64);
1293 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts64));
1294
1295error: /* even if we error out, we forwarded the time, so call update */
1296 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1297
1298 write_seqcount_end(&tk_core.seq);
1299 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1300
1301 /* signal hrtimers about time change */
1302 clock_was_set();
1303
1304 return ret;
1305}
1306EXPORT_SYMBOL(timekeeping_inject_offset);
1307
1308/**
1309 * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1310 *
1311 */
1312static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1313{
1314 tk->tai_offset = tai_offset;
1315 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1316}
1317
1318/**
1319 * change_clocksource - Swaps clocksources if a new one is available
1320 *
1321 * Accumulates current time interval and initializes new clocksource
1322 */
1323static int change_clocksource(void *data)
1324{
1325 struct timekeeper *tk = &tk_core.timekeeper;
1326 struct clocksource *new, *old;
1327 unsigned long flags;
1328
1329 new = (struct clocksource *) data;
1330
1331 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1332 write_seqcount_begin(&tk_core.seq);
1333
1334 timekeeping_forward_now(tk);
1335 /*
1336 * If the cs is in module, get a module reference. Succeeds
1337 * for built-in code (owner == NULL) as well.
1338 */
1339 if (try_module_get(new->owner)) {
1340 if (!new->enable || new->enable(new) == 0) {
1341 old = tk->tkr_mono.clock;
1342 tk_setup_internals(tk, new);
1343 if (old->disable)
1344 old->disable(old);
1345 module_put(old->owner);
1346 } else {
1347 module_put(new->owner);
1348 }
1349 }
1350 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1351
1352 write_seqcount_end(&tk_core.seq);
1353 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1354
1355 return 0;
1356}
1357
1358/**
1359 * timekeeping_notify - Install a new clock source
1360 * @clock: pointer to the clock source
1361 *
1362 * This function is called from clocksource.c after a new, better clock
1363 * source has been registered. The caller holds the clocksource_mutex.
1364 */
1365int timekeeping_notify(struct clocksource *clock)
1366{
1367 struct timekeeper *tk = &tk_core.timekeeper;
1368
1369 if (tk->tkr_mono.clock == clock)
1370 return 0;
1371 stop_machine(change_clocksource, clock, NULL);
1372 tick_clock_notify();
1373 return tk->tkr_mono.clock == clock ? 0 : -1;
1374}
1375
1376/**
1377 * getrawmonotonic64 - Returns the raw monotonic time in a timespec
1378 * @ts: pointer to the timespec64 to be set
1379 *
1380 * Returns the raw monotonic time (completely un-modified by ntp)
1381 */
1382void getrawmonotonic64(struct timespec64 *ts)
1383{
1384 struct timekeeper *tk = &tk_core.timekeeper;
1385 unsigned long seq;
1386 u64 nsecs;
1387
1388 do {
1389 seq = read_seqcount_begin(&tk_core.seq);
1390 ts->tv_sec = tk->raw_sec;
1391 nsecs = timekeeping_get_ns(&tk->tkr_raw);
1392
1393 } while (read_seqcount_retry(&tk_core.seq, seq));
1394
1395 ts->tv_nsec = 0;
1396 timespec64_add_ns(ts, nsecs);
1397}
1398EXPORT_SYMBOL(getrawmonotonic64);
1399
1400
1401/**
1402 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1403 */
1404int timekeeping_valid_for_hres(void)
1405{
1406 struct timekeeper *tk = &tk_core.timekeeper;
1407 unsigned long seq;
1408 int ret;
1409
1410 do {
1411 seq = read_seqcount_begin(&tk_core.seq);
1412
1413 ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1414
1415 } while (read_seqcount_retry(&tk_core.seq, seq));
1416
1417 return ret;
1418}
1419
1420/**
1421 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1422 */
1423u64 timekeeping_max_deferment(void)
1424{
1425 struct timekeeper *tk = &tk_core.timekeeper;
1426 unsigned long seq;
1427 u64 ret;
1428
1429 do {
1430 seq = read_seqcount_begin(&tk_core.seq);
1431
1432 ret = tk->tkr_mono.clock->max_idle_ns;
1433
1434 } while (read_seqcount_retry(&tk_core.seq, seq));
1435
1436 return ret;
1437}
1438
1439/**
1440 * read_persistent_clock - Return time from the persistent clock.
1441 *
1442 * Weak dummy function for arches that do not yet support it.
1443 * Reads the time from the battery backed persistent clock.
1444 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1445 *
1446 * XXX - Do be sure to remove it once all arches implement it.
1447 */
1448void __weak read_persistent_clock(struct timespec *ts)
1449{
1450 ts->tv_sec = 0;
1451 ts->tv_nsec = 0;
1452}
1453
1454void __weak read_persistent_clock64(struct timespec64 *ts64)
1455{
1456 struct timespec ts;
1457
1458 read_persistent_clock(&ts);
1459 *ts64 = timespec_to_timespec64(ts);
1460}
1461
1462/**
1463 * read_boot_clock64 - Return time of the system start.
1464 *
1465 * Weak dummy function for arches that do not yet support it.
1466 * Function to read the exact time the system has been started.
1467 * Returns a timespec64 with tv_sec=0 and tv_nsec=0 if unsupported.
1468 *
1469 * XXX - Do be sure to remove it once all arches implement it.
1470 */
1471void __weak read_boot_clock64(struct timespec64 *ts)
1472{
1473 ts->tv_sec = 0;
1474 ts->tv_nsec = 0;
1475}
1476
1477/* Flag for if timekeeping_resume() has injected sleeptime */
1478static bool sleeptime_injected;
1479
1480/* Flag for if there is a persistent clock on this platform */
1481static bool persistent_clock_exists;
1482
1483/*
1484 * timekeeping_init - Initializes the clocksource and common timekeeping values
1485 */
1486void __init timekeeping_init(void)
1487{
1488 struct timekeeper *tk = &tk_core.timekeeper;
1489 struct clocksource *clock;
1490 unsigned long flags;
1491 struct timespec64 now, boot, tmp;
1492
1493 read_persistent_clock64(&now);
1494 if (!timespec64_valid_strict(&now)) {
1495 pr_warn("WARNING: Persistent clock returned invalid value!\n"
1496 " Check your CMOS/BIOS settings.\n");
1497 now.tv_sec = 0;
1498 now.tv_nsec = 0;
1499 } else if (now.tv_sec || now.tv_nsec)
1500 persistent_clock_exists = true;
1501
1502 read_boot_clock64(&boot);
1503 if (!timespec64_valid_strict(&boot)) {
1504 pr_warn("WARNING: Boot clock returned invalid value!\n"
1505 " Check your CMOS/BIOS settings.\n");
1506 boot.tv_sec = 0;
1507 boot.tv_nsec = 0;
1508 }
1509
1510 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1511 write_seqcount_begin(&tk_core.seq);
1512 ntp_init();
1513
1514 clock = clocksource_default_clock();
1515 if (clock->enable)
1516 clock->enable(clock);
1517 tk_setup_internals(tk, clock);
1518
1519 tk_set_xtime(tk, &now);
1520 tk->raw_sec = 0;
1521 if (boot.tv_sec == 0 && boot.tv_nsec == 0)
1522 boot = tk_xtime(tk);
1523
1524 set_normalized_timespec64(&tmp, -boot.tv_sec, -boot.tv_nsec);
1525 tk_set_wall_to_mono(tk, tmp);
1526
1527 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1528
1529 write_seqcount_end(&tk_core.seq);
1530 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1531}
1532
1533/* time in seconds when suspend began for persistent clock */
1534static struct timespec64 timekeeping_suspend_time;
1535
1536/**
1537 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1538 * @delta: pointer to a timespec delta value
1539 *
1540 * Takes a timespec offset measuring a suspend interval and properly
1541 * adds the sleep offset to the timekeeping variables.
1542 */
1543static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1544 struct timespec64 *delta)
1545{
1546 if (!timespec64_valid_strict(delta)) {
1547 printk_deferred(KERN_WARNING
1548 "__timekeeping_inject_sleeptime: Invalid "
1549 "sleep delta value!\n");
1550 return;
1551 }
1552 tk_xtime_add(tk, delta);
1553 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1554 tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1555 tk_debug_account_sleep_time(delta);
1556}
1557
1558#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1559/**
1560 * We have three kinds of time sources to use for sleep time
1561 * injection, the preference order is:
1562 * 1) non-stop clocksource
1563 * 2) persistent clock (ie: RTC accessible when irqs are off)
1564 * 3) RTC
1565 *
1566 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1567 * If system has neither 1) nor 2), 3) will be used finally.
1568 *
1569 *
1570 * If timekeeping has injected sleeptime via either 1) or 2),
1571 * 3) becomes needless, so in this case we don't need to call
1572 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1573 * means.
1574 */
1575bool timekeeping_rtc_skipresume(void)
1576{
1577 return sleeptime_injected;
1578}
1579
1580/**
1581 * 1) can be determined whether to use or not only when doing
1582 * timekeeping_resume() which is invoked after rtc_suspend(),
1583 * so we can't skip rtc_suspend() surely if system has 1).
1584 *
1585 * But if system has 2), 2) will definitely be used, so in this
1586 * case we don't need to call rtc_suspend(), and this is what
1587 * timekeeping_rtc_skipsuspend() means.
1588 */
1589bool timekeeping_rtc_skipsuspend(void)
1590{
1591 return persistent_clock_exists;
1592}
1593
1594/**
1595 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1596 * @delta: pointer to a timespec64 delta value
1597 *
1598 * This hook is for architectures that cannot support read_persistent_clock64
1599 * because their RTC/persistent clock is only accessible when irqs are enabled.
1600 * and also don't have an effective nonstop clocksource.
1601 *
1602 * This function should only be called by rtc_resume(), and allows
1603 * a suspend offset to be injected into the timekeeping values.
1604 */
1605void timekeeping_inject_sleeptime64(struct timespec64 *delta)
1606{
1607 struct timekeeper *tk = &tk_core.timekeeper;
1608 unsigned long flags;
1609
1610 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1611 write_seqcount_begin(&tk_core.seq);
1612
1613 timekeeping_forward_now(tk);
1614
1615 __timekeeping_inject_sleeptime(tk, delta);
1616
1617 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1618
1619 write_seqcount_end(&tk_core.seq);
1620 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1621
1622 /* signal hrtimers about time change */
1623 clock_was_set();
1624}
1625#endif
1626
1627/**
1628 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1629 */
1630void timekeeping_resume(void)
1631{
1632 struct timekeeper *tk = &tk_core.timekeeper;
1633 struct clocksource *clock = tk->tkr_mono.clock;
1634 unsigned long flags;
1635 struct timespec64 ts_new, ts_delta;
1636 u64 cycle_now;
1637
1638 sleeptime_injected = false;
1639 read_persistent_clock64(&ts_new);
1640
1641 clockevents_resume();
1642 clocksource_resume();
1643
1644 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1645 write_seqcount_begin(&tk_core.seq);
1646
1647 /*
1648 * After system resumes, we need to calculate the suspended time and
1649 * compensate it for the OS time. There are 3 sources that could be
1650 * used: Nonstop clocksource during suspend, persistent clock and rtc
1651 * device.
1652 *
1653 * One specific platform may have 1 or 2 or all of them, and the
1654 * preference will be:
1655 * suspend-nonstop clocksource -> persistent clock -> rtc
1656 * The less preferred source will only be tried if there is no better
1657 * usable source. The rtc part is handled separately in rtc core code.
1658 */
1659 cycle_now = tk_clock_read(&tk->tkr_mono);
1660 if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) &&
1661 cycle_now > tk->tkr_mono.cycle_last) {
1662 u64 nsec, cyc_delta;
1663
1664 cyc_delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last,
1665 tk->tkr_mono.mask);
1666 nsec = mul_u64_u32_shr(cyc_delta, clock->mult, clock->shift);
1667 ts_delta = ns_to_timespec64(nsec);
1668 sleeptime_injected = true;
1669 } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1670 ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1671 sleeptime_injected = true;
1672 }
1673
1674 if (sleeptime_injected)
1675 __timekeeping_inject_sleeptime(tk, &ts_delta);
1676
1677 /* Re-base the last cycle value */
1678 tk->tkr_mono.cycle_last = cycle_now;
1679 tk->tkr_raw.cycle_last = cycle_now;
1680
1681 tk->ntp_error = 0;
1682 timekeeping_suspended = 0;
1683 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1684 write_seqcount_end(&tk_core.seq);
1685 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1686
1687 touch_softlockup_watchdog();
1688
1689 tick_resume();
1690 hrtimers_resume();
1691}
1692
1693int timekeeping_suspend(void)
1694{
1695 struct timekeeper *tk = &tk_core.timekeeper;
1696 unsigned long flags;
1697 struct timespec64 delta, delta_delta;
1698 static struct timespec64 old_delta;
1699
1700 read_persistent_clock64(&timekeeping_suspend_time);
1701
1702 /*
1703 * On some systems the persistent_clock can not be detected at
1704 * timekeeping_init by its return value, so if we see a valid
1705 * value returned, update the persistent_clock_exists flag.
1706 */
1707 if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1708 persistent_clock_exists = true;
1709
1710 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1711 write_seqcount_begin(&tk_core.seq);
1712 timekeeping_forward_now(tk);
1713 timekeeping_suspended = 1;
1714
1715 if (persistent_clock_exists) {
1716 /*
1717 * To avoid drift caused by repeated suspend/resumes,
1718 * which each can add ~1 second drift error,
1719 * try to compensate so the difference in system time
1720 * and persistent_clock time stays close to constant.
1721 */
1722 delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1723 delta_delta = timespec64_sub(delta, old_delta);
1724 if (abs(delta_delta.tv_sec) >= 2) {
1725 /*
1726 * if delta_delta is too large, assume time correction
1727 * has occurred and set old_delta to the current delta.
1728 */
1729 old_delta = delta;
1730 } else {
1731 /* Otherwise try to adjust old_system to compensate */
1732 timekeeping_suspend_time =
1733 timespec64_add(timekeeping_suspend_time, delta_delta);
1734 }
1735 }
1736
1737 timekeeping_update(tk, TK_MIRROR);
1738 halt_fast_timekeeper(tk);
1739 write_seqcount_end(&tk_core.seq);
1740 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1741
1742 tick_suspend();
1743 clocksource_suspend();
1744 clockevents_suspend();
1745
1746 return 0;
1747}
1748
1749/* sysfs resume/suspend bits for timekeeping */
1750static struct syscore_ops timekeeping_syscore_ops = {
1751 .resume = timekeeping_resume,
1752 .suspend = timekeeping_suspend,
1753};
1754
1755static int __init timekeeping_init_ops(void)
1756{
1757 register_syscore_ops(&timekeeping_syscore_ops);
1758 return 0;
1759}
1760device_initcall(timekeeping_init_ops);
1761
1762/*
1763 * Apply a multiplier adjustment to the timekeeper
1764 */
1765static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1766 s64 offset,
1767 bool negative,
1768 int adj_scale)
1769{
1770 s64 interval = tk->cycle_interval;
1771 s32 mult_adj = 1;
1772
1773 if (negative) {
1774 mult_adj = -mult_adj;
1775 interval = -interval;
1776 offset = -offset;
1777 }
1778 mult_adj <<= adj_scale;
1779 interval <<= adj_scale;
1780 offset <<= adj_scale;
1781
1782 /*
1783 * So the following can be confusing.
1784 *
1785 * To keep things simple, lets assume mult_adj == 1 for now.
1786 *
1787 * When mult_adj != 1, remember that the interval and offset values
1788 * have been appropriately scaled so the math is the same.
1789 *
1790 * The basic idea here is that we're increasing the multiplier
1791 * by one, this causes the xtime_interval to be incremented by
1792 * one cycle_interval. This is because:
1793 * xtime_interval = cycle_interval * mult
1794 * So if mult is being incremented by one:
1795 * xtime_interval = cycle_interval * (mult + 1)
1796 * Its the same as:
1797 * xtime_interval = (cycle_interval * mult) + cycle_interval
1798 * Which can be shortened to:
1799 * xtime_interval += cycle_interval
1800 *
1801 * So offset stores the non-accumulated cycles. Thus the current
1802 * time (in shifted nanoseconds) is:
1803 * now = (offset * adj) + xtime_nsec
1804 * Now, even though we're adjusting the clock frequency, we have
1805 * to keep time consistent. In other words, we can't jump back
1806 * in time, and we also want to avoid jumping forward in time.
1807 *
1808 * So given the same offset value, we need the time to be the same
1809 * both before and after the freq adjustment.
1810 * now = (offset * adj_1) + xtime_nsec_1
1811 * now = (offset * adj_2) + xtime_nsec_2
1812 * So:
1813 * (offset * adj_1) + xtime_nsec_1 =
1814 * (offset * adj_2) + xtime_nsec_2
1815 * And we know:
1816 * adj_2 = adj_1 + 1
1817 * So:
1818 * (offset * adj_1) + xtime_nsec_1 =
1819 * (offset * (adj_1+1)) + xtime_nsec_2
1820 * (offset * adj_1) + xtime_nsec_1 =
1821 * (offset * adj_1) + offset + xtime_nsec_2
1822 * Canceling the sides:
1823 * xtime_nsec_1 = offset + xtime_nsec_2
1824 * Which gives us:
1825 * xtime_nsec_2 = xtime_nsec_1 - offset
1826 * Which simplfies to:
1827 * xtime_nsec -= offset
1828 *
1829 * XXX - TODO: Doc ntp_error calculation.
1830 */
1831 if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1832 /* NTP adjustment caused clocksource mult overflow */
1833 WARN_ON_ONCE(1);
1834 return;
1835 }
1836
1837 tk->tkr_mono.mult += mult_adj;
1838 tk->xtime_interval += interval;
1839 tk->tkr_mono.xtime_nsec -= offset;
1840 tk->ntp_error -= (interval - offset) << tk->ntp_error_shift;
1841}
1842
1843/*
1844 * Calculate the multiplier adjustment needed to match the frequency
1845 * specified by NTP
1846 */
1847static __always_inline void timekeeping_freqadjust(struct timekeeper *tk,
1848 s64 offset)
1849{
1850 s64 interval = tk->cycle_interval;
1851 s64 xinterval = tk->xtime_interval;
1852 u32 base = tk->tkr_mono.clock->mult;
1853 u32 max = tk->tkr_mono.clock->maxadj;
1854 u32 cur_adj = tk->tkr_mono.mult;
1855 s64 tick_error;
1856 bool negative;
1857 u32 adj_scale;
1858
1859 /* Remove any current error adj from freq calculation */
1860 if (tk->ntp_err_mult)
1861 xinterval -= tk->cycle_interval;
1862
1863 tk->ntp_tick = ntp_tick_length();
1864
1865 /* Calculate current error per tick */
1866 tick_error = ntp_tick_length() >> tk->ntp_error_shift;
1867 tick_error -= (xinterval + tk->xtime_remainder);
1868
1869 /* Don't worry about correcting it if its small */
1870 if (likely((tick_error >= 0) && (tick_error <= interval)))
1871 return;
1872
1873 /* preserve the direction of correction */
1874 negative = (tick_error < 0);
1875
1876 /* If any adjustment would pass the max, just return */
1877 if (negative && (cur_adj - 1) <= (base - max))
1878 return;
1879 if (!negative && (cur_adj + 1) >= (base + max))
1880 return;
1881 /*
1882 * Sort out the magnitude of the correction, but
1883 * avoid making so large a correction that we go
1884 * over the max adjustment.
1885 */
1886 adj_scale = 0;
1887 tick_error = abs(tick_error);
1888 while (tick_error > interval) {
1889 u32 adj = 1 << (adj_scale + 1);
1890
1891 /* Check if adjustment gets us within 1 unit from the max */
1892 if (negative && (cur_adj - adj) <= (base - max))
1893 break;
1894 if (!negative && (cur_adj + adj) >= (base + max))
1895 break;
1896
1897 adj_scale++;
1898 tick_error >>= 1;
1899 }
1900
1901 /* scale the corrections */
1902 timekeeping_apply_adjustment(tk, offset, negative, adj_scale);
1903}
1904
1905/*
1906 * Adjust the timekeeper's multiplier to the correct frequency
1907 * and also to reduce the accumulated error value.
1908 */
1909static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1910{
1911 /* Correct for the current frequency error */
1912 timekeeping_freqadjust(tk, offset);
1913
1914 /* Next make a small adjustment to fix any cumulative error */
1915 if (!tk->ntp_err_mult && (tk->ntp_error > 0)) {
1916 tk->ntp_err_mult = 1;
1917 timekeeping_apply_adjustment(tk, offset, 0, 0);
1918 } else if (tk->ntp_err_mult && (tk->ntp_error <= 0)) {
1919 /* Undo any existing error adjustment */
1920 timekeeping_apply_adjustment(tk, offset, 1, 0);
1921 tk->ntp_err_mult = 0;
1922 }
1923
1924 if (unlikely(tk->tkr_mono.clock->maxadj &&
1925 (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
1926 > tk->tkr_mono.clock->maxadj))) {
1927 printk_once(KERN_WARNING
1928 "Adjusting %s more than 11%% (%ld vs %ld)\n",
1929 tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
1930 (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
1931 }
1932
1933 /*
1934 * It may be possible that when we entered this function, xtime_nsec
1935 * was very small. Further, if we're slightly speeding the clocksource
1936 * in the code above, its possible the required corrective factor to
1937 * xtime_nsec could cause it to underflow.
1938 *
1939 * Now, since we already accumulated the second, cannot simply roll
1940 * the accumulated second back, since the NTP subsystem has been
1941 * notified via second_overflow. So instead we push xtime_nsec forward
1942 * by the amount we underflowed, and add that amount into the error.
1943 *
1944 * We'll correct this error next time through this function, when
1945 * xtime_nsec is not as small.
1946 */
1947 if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
1948 s64 neg = -(s64)tk->tkr_mono.xtime_nsec;
1949 tk->tkr_mono.xtime_nsec = 0;
1950 tk->ntp_error += neg << tk->ntp_error_shift;
1951 }
1952}
1953
1954/**
1955 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1956 *
1957 * Helper function that accumulates the nsecs greater than a second
1958 * from the xtime_nsec field to the xtime_secs field.
1959 * It also calls into the NTP code to handle leapsecond processing.
1960 *
1961 */
1962static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
1963{
1964 u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
1965 unsigned int clock_set = 0;
1966
1967 while (tk->tkr_mono.xtime_nsec >= nsecps) {
1968 int leap;
1969
1970 tk->tkr_mono.xtime_nsec -= nsecps;
1971 tk->xtime_sec++;
1972
1973 /* Figure out if its a leap sec and apply if needed */
1974 leap = second_overflow(tk->xtime_sec);
1975 if (unlikely(leap)) {
1976 struct timespec64 ts;
1977
1978 tk->xtime_sec += leap;
1979
1980 ts.tv_sec = leap;
1981 ts.tv_nsec = 0;
1982 tk_set_wall_to_mono(tk,
1983 timespec64_sub(tk->wall_to_monotonic, ts));
1984
1985 __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
1986
1987 clock_set = TK_CLOCK_WAS_SET;
1988 }
1989 }
1990 return clock_set;
1991}
1992
1993/**
1994 * logarithmic_accumulation - shifted accumulation of cycles
1995 *
1996 * This functions accumulates a shifted interval of cycles into
1997 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1998 * loop.
1999 *
2000 * Returns the unconsumed cycles.
2001 */
2002static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2003 u32 shift, unsigned int *clock_set)
2004{
2005 u64 interval = tk->cycle_interval << shift;
2006 u64 snsec_per_sec;
2007
2008 /* If the offset is smaller than a shifted interval, do nothing */
2009 if (offset < interval)
2010 return offset;
2011
2012 /* Accumulate one shifted interval */
2013 offset -= interval;
2014 tk->tkr_mono.cycle_last += interval;
2015 tk->tkr_raw.cycle_last += interval;
2016
2017 tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2018 *clock_set |= accumulate_nsecs_to_secs(tk);
2019
2020 /* Accumulate raw time */
2021 tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2022 snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2023 while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2024 tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2025 tk->raw_sec++;
2026 }
2027
2028 /* Accumulate error between NTP and clock interval */
2029 tk->ntp_error += tk->ntp_tick << shift;
2030 tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2031 (tk->ntp_error_shift + shift);
2032
2033 return offset;
2034}
2035
2036/**
2037 * update_wall_time - Uses the current clocksource to increment the wall time
2038 *
2039 */
2040void update_wall_time(void)
2041{
2042 struct timekeeper *real_tk = &tk_core.timekeeper;
2043 struct timekeeper *tk = &shadow_timekeeper;
2044 u64 offset;
2045 int shift = 0, maxshift;
2046 unsigned int clock_set = 0;
2047 unsigned long flags;
2048
2049 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2050
2051 /* Make sure we're fully resumed: */
2052 if (unlikely(timekeeping_suspended))
2053 goto out;
2054
2055#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
2056 offset = real_tk->cycle_interval;
2057#else
2058 offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
2059 tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2060#endif
2061
2062 /* Check if there's really nothing to do */
2063 if (offset < real_tk->cycle_interval)
2064 goto out;
2065
2066 /* Do some additional sanity checking */
2067 timekeeping_check_update(real_tk, offset);
2068
2069 /*
2070 * With NO_HZ we may have to accumulate many cycle_intervals
2071 * (think "ticks") worth of time at once. To do this efficiently,
2072 * we calculate the largest doubling multiple of cycle_intervals
2073 * that is smaller than the offset. We then accumulate that
2074 * chunk in one go, and then try to consume the next smaller
2075 * doubled multiple.
2076 */
2077 shift = ilog2(offset) - ilog2(tk->cycle_interval);
2078 shift = max(0, shift);
2079 /* Bound shift to one less than what overflows tick_length */
2080 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2081 shift = min(shift, maxshift);
2082 while (offset >= tk->cycle_interval) {
2083 offset = logarithmic_accumulation(tk, offset, shift,
2084 &clock_set);
2085 if (offset < tk->cycle_interval<<shift)
2086 shift--;
2087 }
2088
2089 /* correct the clock when NTP error is too big */
2090 timekeeping_adjust(tk, offset);
2091
2092 /*
2093 * XXX This can be killed once everyone converts
2094 * to the new update_vsyscall.
2095 */
2096 old_vsyscall_fixup(tk);
2097
2098 /*
2099 * Finally, make sure that after the rounding
2100 * xtime_nsec isn't larger than NSEC_PER_SEC
2101 */
2102 clock_set |= accumulate_nsecs_to_secs(tk);
2103
2104 write_seqcount_begin(&tk_core.seq);
2105 /*
2106 * Update the real timekeeper.
2107 *
2108 * We could avoid this memcpy by switching pointers, but that
2109 * requires changes to all other timekeeper usage sites as
2110 * well, i.e. move the timekeeper pointer getter into the
2111 * spinlocked/seqcount protected sections. And we trade this
2112 * memcpy under the tk_core.seq against one before we start
2113 * updating.
2114 */
2115 timekeeping_update(tk, clock_set);
2116 memcpy(real_tk, tk, sizeof(*tk));
2117 /* The memcpy must come last. Do not put anything here! */
2118 write_seqcount_end(&tk_core.seq);
2119out:
2120 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2121 if (clock_set)
2122 /* Have to call _delayed version, since in irq context*/
2123 clock_was_set_delayed();
2124}
2125
2126/**
2127 * getboottime64 - Return the real time of system boot.
2128 * @ts: pointer to the timespec64 to be set
2129 *
2130 * Returns the wall-time of boot in a timespec64.
2131 *
2132 * This is based on the wall_to_monotonic offset and the total suspend
2133 * time. Calls to settimeofday will affect the value returned (which
2134 * basically means that however wrong your real time clock is at boot time,
2135 * you get the right time here).
2136 */
2137void getboottime64(struct timespec64 *ts)
2138{
2139 struct timekeeper *tk = &tk_core.timekeeper;
2140 ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2141
2142 *ts = ktime_to_timespec64(t);
2143}
2144EXPORT_SYMBOL_GPL(getboottime64);
2145
2146unsigned long get_seconds(void)
2147{
2148 struct timekeeper *tk = &tk_core.timekeeper;
2149
2150 return tk->xtime_sec;
2151}
2152EXPORT_SYMBOL(get_seconds);
2153
2154struct timespec __current_kernel_time(void)
2155{
2156 struct timekeeper *tk = &tk_core.timekeeper;
2157
2158 return timespec64_to_timespec(tk_xtime(tk));
2159}
2160
2161struct timespec64 current_kernel_time64(void)
2162{
2163 struct timekeeper *tk = &tk_core.timekeeper;
2164 struct timespec64 now;
2165 unsigned long seq;
2166
2167 do {
2168 seq = read_seqcount_begin(&tk_core.seq);
2169
2170 now = tk_xtime(tk);
2171 } while (read_seqcount_retry(&tk_core.seq, seq));
2172
2173 return now;
2174}
2175EXPORT_SYMBOL(current_kernel_time64);
2176
2177struct timespec64 get_monotonic_coarse64(void)
2178{
2179 struct timekeeper *tk = &tk_core.timekeeper;
2180 struct timespec64 now, mono;
2181 unsigned long seq;
2182
2183 do {
2184 seq = read_seqcount_begin(&tk_core.seq);
2185
2186 now = tk_xtime(tk);
2187 mono = tk->wall_to_monotonic;
2188 } while (read_seqcount_retry(&tk_core.seq, seq));
2189
2190 set_normalized_timespec64(&now, now.tv_sec + mono.tv_sec,
2191 now.tv_nsec + mono.tv_nsec);
2192
2193 return now;
2194}
2195EXPORT_SYMBOL(get_monotonic_coarse64);
2196
2197/*
2198 * Must hold jiffies_lock
2199 */
2200void do_timer(unsigned long ticks)
2201{
2202 jiffies_64 += ticks;
2203 calc_global_load(ticks);
2204}
2205
2206/**
2207 * ktime_get_update_offsets_now - hrtimer helper
2208 * @cwsseq: pointer to check and store the clock was set sequence number
2209 * @offs_real: pointer to storage for monotonic -> realtime offset
2210 * @offs_boot: pointer to storage for monotonic -> boottime offset
2211 * @offs_tai: pointer to storage for monotonic -> clock tai offset
2212 *
2213 * Returns current monotonic time and updates the offsets if the
2214 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2215 * different.
2216 *
2217 * Called from hrtimer_interrupt() or retrigger_next_event()
2218 */
2219ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2220 ktime_t *offs_boot, ktime_t *offs_tai)
2221{
2222 struct timekeeper *tk = &tk_core.timekeeper;
2223 unsigned int seq;
2224 ktime_t base;
2225 u64 nsecs;
2226
2227 do {
2228 seq = read_seqcount_begin(&tk_core.seq);
2229
2230 base = tk->tkr_mono.base;
2231 nsecs = timekeeping_get_ns(&tk->tkr_mono);
2232 base = ktime_add_ns(base, nsecs);
2233
2234 if (*cwsseq != tk->clock_was_set_seq) {
2235 *cwsseq = tk->clock_was_set_seq;
2236 *offs_real = tk->offs_real;
2237 *offs_boot = tk->offs_boot;
2238 *offs_tai = tk->offs_tai;
2239 }
2240
2241 /* Handle leapsecond insertion adjustments */
2242 if (unlikely(base >= tk->next_leap_ktime))
2243 *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2244
2245 } while (read_seqcount_retry(&tk_core.seq, seq));
2246
2247 return base;
2248}
2249
2250/**
2251 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2252 */
2253int do_adjtimex(struct timex *txc)
2254{
2255 struct timekeeper *tk = &tk_core.timekeeper;
2256 unsigned long flags;
2257 struct timespec64 ts;
2258 s32 orig_tai, tai;
2259 int ret;
2260
2261 /* Validate the data before disabling interrupts */
2262 ret = ntp_validate_timex(txc);
2263 if (ret)
2264 return ret;
2265
2266 if (txc->modes & ADJ_SETOFFSET) {
2267 struct timespec delta;
2268 delta.tv_sec = txc->time.tv_sec;
2269 delta.tv_nsec = txc->time.tv_usec;
2270 if (!(txc->modes & ADJ_NANO))
2271 delta.tv_nsec *= 1000;
2272 ret = timekeeping_inject_offset(&delta);
2273 if (ret)
2274 return ret;
2275 }
2276
2277 getnstimeofday64(&ts);
2278
2279 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2280 write_seqcount_begin(&tk_core.seq);
2281
2282 orig_tai = tai = tk->tai_offset;
2283 ret = __do_adjtimex(txc, &ts, &tai);
2284
2285 if (tai != orig_tai) {
2286 __timekeeping_set_tai_offset(tk, tai);
2287 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2288 }
2289 tk_update_leap_state(tk);
2290
2291 write_seqcount_end(&tk_core.seq);
2292 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2293
2294 if (tai != orig_tai)
2295 clock_was_set();
2296
2297 ntp_notify_cmos_timer();
2298
2299 return ret;
2300}
2301
2302#ifdef CONFIG_NTP_PPS
2303/**
2304 * hardpps() - Accessor function to NTP __hardpps function
2305 */
2306void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2307{
2308 unsigned long flags;
2309
2310 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2311 write_seqcount_begin(&tk_core.seq);
2312
2313 __hardpps(phase_ts, raw_ts);
2314
2315 write_seqcount_end(&tk_core.seq);
2316 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2317}
2318EXPORT_SYMBOL(hardpps);
2319#endif
2320
2321/**
2322 * xtime_update() - advances the timekeeping infrastructure
2323 * @ticks: number of ticks, that have elapsed since the last call.
2324 *
2325 * Must be called with interrupts disabled.
2326 */
2327void xtime_update(unsigned long ticks)
2328{
2329 write_seqlock(&jiffies_lock);
2330 do_timer(ticks);
2331 write_sequnlock(&jiffies_lock);
2332 update_wall_time();
2333}