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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/timex.h>
21#include <linux/tick.h>
22#include <linux/stop_machine.h>
23#include <linux/pvclock_gtod.h>
24#include <linux/compiler.h>
25#include <linux/audit.h>
26#include <linux/random.h>
27
28#include "tick-internal.h"
29#include "ntp_internal.h"
30#include "timekeeping_internal.h"
31
32#define TK_CLEAR_NTP (1 << 0)
33#define TK_MIRROR (1 << 1)
34#define TK_CLOCK_WAS_SET (1 << 2)
35
36enum timekeeping_adv_mode {
37 /* Update timekeeper when a tick has passed */
38 TK_ADV_TICK,
39
40 /* Update timekeeper on a direct frequency change */
41 TK_ADV_FREQ
42};
43
44DEFINE_RAW_SPINLOCK(timekeeper_lock);
45
46/*
47 * The most important data for readout fits into a single 64 byte
48 * cache line.
49 */
50static struct {
51 seqcount_raw_spinlock_t seq;
52 struct timekeeper timekeeper;
53} tk_core ____cacheline_aligned = {
54 .seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_core.seq, &timekeeper_lock),
55};
56
57static struct timekeeper shadow_timekeeper;
58
59/* flag for if timekeeping is suspended */
60int __read_mostly timekeeping_suspended;
61
62/**
63 * struct tk_fast - NMI safe timekeeper
64 * @seq: Sequence counter for protecting updates. The lowest bit
65 * is the index for the tk_read_base array
66 * @base: tk_read_base array. Access is indexed by the lowest bit of
67 * @seq.
68 *
69 * See @update_fast_timekeeper() below.
70 */
71struct tk_fast {
72 seqcount_latch_t seq;
73 struct tk_read_base base[2];
74};
75
76/* Suspend-time cycles value for halted fast timekeeper. */
77static u64 cycles_at_suspend;
78
79static u64 dummy_clock_read(struct clocksource *cs)
80{
81 if (timekeeping_suspended)
82 return cycles_at_suspend;
83 return local_clock();
84}
85
86static struct clocksource dummy_clock = {
87 .read = dummy_clock_read,
88};
89
90/*
91 * Boot time initialization which allows local_clock() to be utilized
92 * during early boot when clocksources are not available. local_clock()
93 * returns nanoseconds already so no conversion is required, hence mult=1
94 * and shift=0. When the first proper clocksource is installed then
95 * the fast time keepers are updated with the correct values.
96 */
97#define FAST_TK_INIT \
98 { \
99 .clock = &dummy_clock, \
100 .mask = CLOCKSOURCE_MASK(64), \
101 .mult = 1, \
102 .shift = 0, \
103 }
104
105static struct tk_fast tk_fast_mono ____cacheline_aligned = {
106 .seq = SEQCNT_LATCH_ZERO(tk_fast_mono.seq),
107 .base[0] = FAST_TK_INIT,
108 .base[1] = FAST_TK_INIT,
109};
110
111static struct tk_fast tk_fast_raw ____cacheline_aligned = {
112 .seq = SEQCNT_LATCH_ZERO(tk_fast_raw.seq),
113 .base[0] = FAST_TK_INIT,
114 .base[1] = FAST_TK_INIT,
115};
116
117static inline void tk_normalize_xtime(struct timekeeper *tk)
118{
119 while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
120 tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
121 tk->xtime_sec++;
122 }
123 while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) {
124 tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
125 tk->raw_sec++;
126 }
127}
128
129static inline struct timespec64 tk_xtime(const struct timekeeper *tk)
130{
131 struct timespec64 ts;
132
133 ts.tv_sec = tk->xtime_sec;
134 ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
135 return ts;
136}
137
138static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
139{
140 tk->xtime_sec = ts->tv_sec;
141 tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
142}
143
144static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts)
145{
146 tk->xtime_sec += ts->tv_sec;
147 tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift;
148 tk_normalize_xtime(tk);
149}
150
151static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
152{
153 struct timespec64 tmp;
154
155 /*
156 * Verify consistency of: offset_real = -wall_to_monotonic
157 * before modifying anything
158 */
159 set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
160 -tk->wall_to_monotonic.tv_nsec);
161 WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp));
162 tk->wall_to_monotonic = wtm;
163 set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
164 tk->offs_real = timespec64_to_ktime(tmp);
165 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
166}
167
168static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
169{
170 tk->offs_boot = ktime_add(tk->offs_boot, delta);
171 /*
172 * Timespec representation for VDSO update to avoid 64bit division
173 * on every update.
174 */
175 tk->monotonic_to_boot = ktime_to_timespec64(tk->offs_boot);
176}
177
178/*
179 * tk_clock_read - atomic clocksource read() helper
180 *
181 * This helper is necessary to use in the read paths because, while the
182 * seqcount ensures we don't return a bad value while structures are updated,
183 * it doesn't protect from potential crashes. There is the possibility that
184 * the tkr's clocksource may change between the read reference, and the
185 * clock reference passed to the read function. This can cause crashes if
186 * the wrong clocksource is passed to the wrong read function.
187 * This isn't necessary to use when holding the timekeeper_lock or doing
188 * a read of the fast-timekeeper tkrs (which is protected by its own locking
189 * and update logic).
190 */
191static inline u64 tk_clock_read(const struct tk_read_base *tkr)
192{
193 struct clocksource *clock = READ_ONCE(tkr->clock);
194
195 return clock->read(clock);
196}
197
198#ifdef CONFIG_DEBUG_TIMEKEEPING
199#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
200
201static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
202{
203
204 u64 max_cycles = tk->tkr_mono.clock->max_cycles;
205 const char *name = tk->tkr_mono.clock->name;
206
207 if (offset > max_cycles) {
208 printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
209 offset, name, max_cycles);
210 printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
211 } else {
212 if (offset > (max_cycles >> 1)) {
213 printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
214 offset, name, max_cycles >> 1);
215 printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
216 }
217 }
218
219 if (tk->underflow_seen) {
220 if (jiffies - tk->last_warning > WARNING_FREQ) {
221 printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
222 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
223 printk_deferred(" Your kernel is probably still fine.\n");
224 tk->last_warning = jiffies;
225 }
226 tk->underflow_seen = 0;
227 }
228
229 if (tk->overflow_seen) {
230 if (jiffies - tk->last_warning > WARNING_FREQ) {
231 printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
232 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
233 printk_deferred(" Your kernel is probably still fine.\n");
234 tk->last_warning = jiffies;
235 }
236 tk->overflow_seen = 0;
237 }
238}
239
240static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
241{
242 struct timekeeper *tk = &tk_core.timekeeper;
243 u64 now, last, mask, max, delta;
244 unsigned int seq;
245
246 /*
247 * Since we're called holding a seqcount, the data may shift
248 * under us while we're doing the calculation. This can cause
249 * false positives, since we'd note a problem but throw the
250 * results away. So nest another seqcount here to atomically
251 * grab the points we are checking with.
252 */
253 do {
254 seq = read_seqcount_begin(&tk_core.seq);
255 now = tk_clock_read(tkr);
256 last = tkr->cycle_last;
257 mask = tkr->mask;
258 max = tkr->clock->max_cycles;
259 } while (read_seqcount_retry(&tk_core.seq, seq));
260
261 delta = clocksource_delta(now, last, mask);
262
263 /*
264 * Try to catch underflows by checking if we are seeing small
265 * mask-relative negative values.
266 */
267 if (unlikely((~delta & mask) < (mask >> 3))) {
268 tk->underflow_seen = 1;
269 delta = 0;
270 }
271
272 /* Cap delta value to the max_cycles values to avoid mult overflows */
273 if (unlikely(delta > max)) {
274 tk->overflow_seen = 1;
275 delta = tkr->clock->max_cycles;
276 }
277
278 return delta;
279}
280#else
281static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
282{
283}
284static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
285{
286 u64 cycle_now, delta;
287
288 /* read clocksource */
289 cycle_now = tk_clock_read(tkr);
290
291 /* calculate the delta since the last update_wall_time */
292 delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
293
294 return delta;
295}
296#endif
297
298/**
299 * tk_setup_internals - Set up internals to use clocksource clock.
300 *
301 * @tk: The target timekeeper to setup.
302 * @clock: Pointer to clocksource.
303 *
304 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
305 * pair and interval request.
306 *
307 * Unless you're the timekeeping code, you should not be using this!
308 */
309static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
310{
311 u64 interval;
312 u64 tmp, ntpinterval;
313 struct clocksource *old_clock;
314
315 ++tk->cs_was_changed_seq;
316 old_clock = tk->tkr_mono.clock;
317 tk->tkr_mono.clock = clock;
318 tk->tkr_mono.mask = clock->mask;
319 tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono);
320
321 tk->tkr_raw.clock = clock;
322 tk->tkr_raw.mask = clock->mask;
323 tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
324
325 /* Do the ns -> cycle conversion first, using original mult */
326 tmp = NTP_INTERVAL_LENGTH;
327 tmp <<= clock->shift;
328 ntpinterval = tmp;
329 tmp += clock->mult/2;
330 do_div(tmp, clock->mult);
331 if (tmp == 0)
332 tmp = 1;
333
334 interval = (u64) tmp;
335 tk->cycle_interval = interval;
336
337 /* Go back from cycles -> shifted ns */
338 tk->xtime_interval = interval * clock->mult;
339 tk->xtime_remainder = ntpinterval - tk->xtime_interval;
340 tk->raw_interval = interval * clock->mult;
341
342 /* if changing clocks, convert xtime_nsec shift units */
343 if (old_clock) {
344 int shift_change = clock->shift - old_clock->shift;
345 if (shift_change < 0) {
346 tk->tkr_mono.xtime_nsec >>= -shift_change;
347 tk->tkr_raw.xtime_nsec >>= -shift_change;
348 } else {
349 tk->tkr_mono.xtime_nsec <<= shift_change;
350 tk->tkr_raw.xtime_nsec <<= shift_change;
351 }
352 }
353
354 tk->tkr_mono.shift = clock->shift;
355 tk->tkr_raw.shift = clock->shift;
356
357 tk->ntp_error = 0;
358 tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
359 tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
360
361 /*
362 * The timekeeper keeps its own mult values for the currently
363 * active clocksource. These value will be adjusted via NTP
364 * to counteract clock drifting.
365 */
366 tk->tkr_mono.mult = clock->mult;
367 tk->tkr_raw.mult = clock->mult;
368 tk->ntp_err_mult = 0;
369 tk->skip_second_overflow = 0;
370}
371
372/* Timekeeper helper functions. */
373
374static inline u64 timekeeping_delta_to_ns(const struct tk_read_base *tkr, u64 delta)
375{
376 u64 nsec;
377
378 nsec = delta * tkr->mult + tkr->xtime_nsec;
379 nsec >>= tkr->shift;
380
381 return nsec;
382}
383
384static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr)
385{
386 u64 delta;
387
388 delta = timekeeping_get_delta(tkr);
389 return timekeeping_delta_to_ns(tkr, delta);
390}
391
392static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles)
393{
394 u64 delta;
395
396 /* calculate the delta since the last update_wall_time */
397 delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
398 return timekeeping_delta_to_ns(tkr, delta);
399}
400
401/**
402 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
403 * @tkr: Timekeeping readout base from which we take the update
404 * @tkf: Pointer to NMI safe timekeeper
405 *
406 * We want to use this from any context including NMI and tracing /
407 * instrumenting the timekeeping code itself.
408 *
409 * Employ the latch technique; see @raw_write_seqcount_latch.
410 *
411 * So if a NMI hits the update of base[0] then it will use base[1]
412 * which is still consistent. In the worst case this can result is a
413 * slightly wrong timestamp (a few nanoseconds). See
414 * @ktime_get_mono_fast_ns.
415 */
416static void update_fast_timekeeper(const struct tk_read_base *tkr,
417 struct tk_fast *tkf)
418{
419 struct tk_read_base *base = tkf->base;
420
421 /* Force readers off to base[1] */
422 raw_write_seqcount_latch(&tkf->seq);
423
424 /* Update base[0] */
425 memcpy(base, tkr, sizeof(*base));
426
427 /* Force readers back to base[0] */
428 raw_write_seqcount_latch(&tkf->seq);
429
430 /* Update base[1] */
431 memcpy(base + 1, base, sizeof(*base));
432}
433
434static __always_inline u64 fast_tk_get_delta_ns(struct tk_read_base *tkr)
435{
436 u64 delta, cycles = tk_clock_read(tkr);
437
438 delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
439 return timekeeping_delta_to_ns(tkr, delta);
440}
441
442static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
443{
444 struct tk_read_base *tkr;
445 unsigned int seq;
446 u64 now;
447
448 do {
449 seq = raw_read_seqcount_latch(&tkf->seq);
450 tkr = tkf->base + (seq & 0x01);
451 now = ktime_to_ns(tkr->base);
452 now += fast_tk_get_delta_ns(tkr);
453 } while (read_seqcount_latch_retry(&tkf->seq, seq));
454
455 return now;
456}
457
458/**
459 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
460 *
461 * This timestamp is not guaranteed to be monotonic across an update.
462 * The timestamp is calculated by:
463 *
464 * now = base_mono + clock_delta * slope
465 *
466 * So if the update lowers the slope, readers who are forced to the
467 * not yet updated second array are still using the old steeper slope.
468 *
469 * tmono
470 * ^
471 * | o n
472 * | o n
473 * | u
474 * | o
475 * |o
476 * |12345678---> reader order
477 *
478 * o = old slope
479 * u = update
480 * n = new slope
481 *
482 * So reader 6 will observe time going backwards versus reader 5.
483 *
484 * While other CPUs are likely to be able to observe that, the only way
485 * for a CPU local observation is when an NMI hits in the middle of
486 * the update. Timestamps taken from that NMI context might be ahead
487 * of the following timestamps. Callers need to be aware of that and
488 * deal with it.
489 */
490u64 notrace ktime_get_mono_fast_ns(void)
491{
492 return __ktime_get_fast_ns(&tk_fast_mono);
493}
494EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
495
496/**
497 * ktime_get_raw_fast_ns - Fast NMI safe access to clock monotonic raw
498 *
499 * Contrary to ktime_get_mono_fast_ns() this is always correct because the
500 * conversion factor is not affected by NTP/PTP correction.
501 */
502u64 notrace ktime_get_raw_fast_ns(void)
503{
504 return __ktime_get_fast_ns(&tk_fast_raw);
505}
506EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
507
508/**
509 * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
510 *
511 * To keep it NMI safe since we're accessing from tracing, we're not using a
512 * separate timekeeper with updates to monotonic clock and boot offset
513 * protected with seqcounts. This has the following minor side effects:
514 *
515 * (1) Its possible that a timestamp be taken after the boot offset is updated
516 * but before the timekeeper is updated. If this happens, the new boot offset
517 * is added to the old timekeeping making the clock appear to update slightly
518 * earlier:
519 * CPU 0 CPU 1
520 * timekeeping_inject_sleeptime64()
521 * __timekeeping_inject_sleeptime(tk, delta);
522 * timestamp();
523 * timekeeping_update(tk, TK_CLEAR_NTP...);
524 *
525 * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
526 * partially updated. Since the tk->offs_boot update is a rare event, this
527 * should be a rare occurrence which postprocessing should be able to handle.
528 *
529 * The caveats vs. timestamp ordering as documented for ktime_get_fast_ns()
530 * apply as well.
531 */
532u64 notrace ktime_get_boot_fast_ns(void)
533{
534 struct timekeeper *tk = &tk_core.timekeeper;
535
536 return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_boot)));
537}
538EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
539
540/**
541 * ktime_get_tai_fast_ns - NMI safe and fast access to tai clock.
542 *
543 * The same limitations as described for ktime_get_boot_fast_ns() apply. The
544 * mono time and the TAI offset are not read atomically which may yield wrong
545 * readouts. However, an update of the TAI offset is an rare event e.g., caused
546 * by settime or adjtimex with an offset. The user of this function has to deal
547 * with the possibility of wrong timestamps in post processing.
548 */
549u64 notrace ktime_get_tai_fast_ns(void)
550{
551 struct timekeeper *tk = &tk_core.timekeeper;
552
553 return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_tai)));
554}
555EXPORT_SYMBOL_GPL(ktime_get_tai_fast_ns);
556
557static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono)
558{
559 struct tk_read_base *tkr;
560 u64 basem, baser, delta;
561 unsigned int seq;
562
563 do {
564 seq = raw_read_seqcount_latch(&tkf->seq);
565 tkr = tkf->base + (seq & 0x01);
566 basem = ktime_to_ns(tkr->base);
567 baser = ktime_to_ns(tkr->base_real);
568 delta = fast_tk_get_delta_ns(tkr);
569 } while (read_seqcount_latch_retry(&tkf->seq, seq));
570
571 if (mono)
572 *mono = basem + delta;
573 return baser + delta;
574}
575
576/**
577 * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime.
578 *
579 * See ktime_get_fast_ns() for documentation of the time stamp ordering.
580 */
581u64 ktime_get_real_fast_ns(void)
582{
583 return __ktime_get_real_fast(&tk_fast_mono, NULL);
584}
585EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns);
586
587/**
588 * ktime_get_fast_timestamps: - NMI safe timestamps
589 * @snapshot: Pointer to timestamp storage
590 *
591 * Stores clock monotonic, boottime and realtime timestamps.
592 *
593 * Boot time is a racy access on 32bit systems if the sleep time injection
594 * happens late during resume and not in timekeeping_resume(). That could
595 * be avoided by expanding struct tk_read_base with boot offset for 32bit
596 * and adding more overhead to the update. As this is a hard to observe
597 * once per resume event which can be filtered with reasonable effort using
598 * the accurate mono/real timestamps, it's probably not worth the trouble.
599 *
600 * Aside of that it might be possible on 32 and 64 bit to observe the
601 * following when the sleep time injection happens late:
602 *
603 * CPU 0 CPU 1
604 * timekeeping_resume()
605 * ktime_get_fast_timestamps()
606 * mono, real = __ktime_get_real_fast()
607 * inject_sleep_time()
608 * update boot offset
609 * boot = mono + bootoffset;
610 *
611 * That means that boot time already has the sleep time adjustment, but
612 * real time does not. On the next readout both are in sync again.
613 *
614 * Preventing this for 64bit is not really feasible without destroying the
615 * careful cache layout of the timekeeper because the sequence count and
616 * struct tk_read_base would then need two cache lines instead of one.
617 *
618 * Access to the time keeper clock source is disabled across the innermost
619 * steps of suspend/resume. The accessors still work, but the timestamps
620 * are frozen until time keeping is resumed which happens very early.
621 *
622 * For regular suspend/resume there is no observable difference vs. sched
623 * clock, but it might affect some of the nasty low level debug printks.
624 *
625 * OTOH, access to sched clock is not guaranteed across suspend/resume on
626 * all systems either so it depends on the hardware in use.
627 *
628 * If that turns out to be a real problem then this could be mitigated by
629 * using sched clock in a similar way as during early boot. But it's not as
630 * trivial as on early boot because it needs some careful protection
631 * against the clock monotonic timestamp jumping backwards on resume.
632 */
633void ktime_get_fast_timestamps(struct ktime_timestamps *snapshot)
634{
635 struct timekeeper *tk = &tk_core.timekeeper;
636
637 snapshot->real = __ktime_get_real_fast(&tk_fast_mono, &snapshot->mono);
638 snapshot->boot = snapshot->mono + ktime_to_ns(data_race(tk->offs_boot));
639}
640
641/**
642 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
643 * @tk: Timekeeper to snapshot.
644 *
645 * It generally is unsafe to access the clocksource after timekeeping has been
646 * suspended, so take a snapshot of the readout base of @tk and use it as the
647 * fast timekeeper's readout base while suspended. It will return the same
648 * number of cycles every time until timekeeping is resumed at which time the
649 * proper readout base for the fast timekeeper will be restored automatically.
650 */
651static void halt_fast_timekeeper(const struct timekeeper *tk)
652{
653 static struct tk_read_base tkr_dummy;
654 const struct tk_read_base *tkr = &tk->tkr_mono;
655
656 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
657 cycles_at_suspend = tk_clock_read(tkr);
658 tkr_dummy.clock = &dummy_clock;
659 tkr_dummy.base_real = tkr->base + tk->offs_real;
660 update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
661
662 tkr = &tk->tkr_raw;
663 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
664 tkr_dummy.clock = &dummy_clock;
665 update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
666}
667
668static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
669
670static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
671{
672 raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
673}
674
675/**
676 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
677 * @nb: Pointer to the notifier block to register
678 */
679int pvclock_gtod_register_notifier(struct notifier_block *nb)
680{
681 struct timekeeper *tk = &tk_core.timekeeper;
682 unsigned long flags;
683 int ret;
684
685 raw_spin_lock_irqsave(&timekeeper_lock, flags);
686 ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
687 update_pvclock_gtod(tk, true);
688 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
689
690 return ret;
691}
692EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
693
694/**
695 * pvclock_gtod_unregister_notifier - unregister a pvclock
696 * timedata update listener
697 * @nb: Pointer to the notifier block to unregister
698 */
699int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
700{
701 unsigned long flags;
702 int ret;
703
704 raw_spin_lock_irqsave(&timekeeper_lock, flags);
705 ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
706 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
707
708 return ret;
709}
710EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
711
712/*
713 * tk_update_leap_state - helper to update the next_leap_ktime
714 */
715static inline void tk_update_leap_state(struct timekeeper *tk)
716{
717 tk->next_leap_ktime = ntp_get_next_leap();
718 if (tk->next_leap_ktime != KTIME_MAX)
719 /* Convert to monotonic time */
720 tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
721}
722
723/*
724 * Update the ktime_t based scalar nsec members of the timekeeper
725 */
726static inline void tk_update_ktime_data(struct timekeeper *tk)
727{
728 u64 seconds;
729 u32 nsec;
730
731 /*
732 * The xtime based monotonic readout is:
733 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
734 * The ktime based monotonic readout is:
735 * nsec = base_mono + now();
736 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
737 */
738 seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
739 nsec = (u32) tk->wall_to_monotonic.tv_nsec;
740 tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
741
742 /*
743 * The sum of the nanoseconds portions of xtime and
744 * wall_to_monotonic can be greater/equal one second. Take
745 * this into account before updating tk->ktime_sec.
746 */
747 nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
748 if (nsec >= NSEC_PER_SEC)
749 seconds++;
750 tk->ktime_sec = seconds;
751
752 /* Update the monotonic raw base */
753 tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
754}
755
756/* must hold timekeeper_lock */
757static void timekeeping_update(struct timekeeper *tk, unsigned int action)
758{
759 if (action & TK_CLEAR_NTP) {
760 tk->ntp_error = 0;
761 ntp_clear();
762 }
763
764 tk_update_leap_state(tk);
765 tk_update_ktime_data(tk);
766
767 update_vsyscall(tk);
768 update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
769
770 tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
771 update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
772 update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
773
774 if (action & TK_CLOCK_WAS_SET)
775 tk->clock_was_set_seq++;
776 /*
777 * The mirroring of the data to the shadow-timekeeper needs
778 * to happen last here to ensure we don't over-write the
779 * timekeeper structure on the next update with stale data
780 */
781 if (action & TK_MIRROR)
782 memcpy(&shadow_timekeeper, &tk_core.timekeeper,
783 sizeof(tk_core.timekeeper));
784}
785
786/**
787 * timekeeping_forward_now - update clock to the current time
788 * @tk: Pointer to the timekeeper to update
789 *
790 * Forward the current clock to update its state since the last call to
791 * update_wall_time(). This is useful before significant clock changes,
792 * as it avoids having to deal with this time offset explicitly.
793 */
794static void timekeeping_forward_now(struct timekeeper *tk)
795{
796 u64 cycle_now, delta;
797
798 cycle_now = tk_clock_read(&tk->tkr_mono);
799 delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
800 tk->tkr_mono.cycle_last = cycle_now;
801 tk->tkr_raw.cycle_last = cycle_now;
802
803 tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
804 tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
805
806 tk_normalize_xtime(tk);
807}
808
809/**
810 * ktime_get_real_ts64 - Returns the time of day in a timespec64.
811 * @ts: pointer to the timespec to be set
812 *
813 * Returns the time of day in a timespec64 (WARN if suspended).
814 */
815void ktime_get_real_ts64(struct timespec64 *ts)
816{
817 struct timekeeper *tk = &tk_core.timekeeper;
818 unsigned int seq;
819 u64 nsecs;
820
821 WARN_ON(timekeeping_suspended);
822
823 do {
824 seq = read_seqcount_begin(&tk_core.seq);
825
826 ts->tv_sec = tk->xtime_sec;
827 nsecs = timekeeping_get_ns(&tk->tkr_mono);
828
829 } while (read_seqcount_retry(&tk_core.seq, seq));
830
831 ts->tv_nsec = 0;
832 timespec64_add_ns(ts, nsecs);
833}
834EXPORT_SYMBOL(ktime_get_real_ts64);
835
836ktime_t ktime_get(void)
837{
838 struct timekeeper *tk = &tk_core.timekeeper;
839 unsigned int seq;
840 ktime_t base;
841 u64 nsecs;
842
843 WARN_ON(timekeeping_suspended);
844
845 do {
846 seq = read_seqcount_begin(&tk_core.seq);
847 base = tk->tkr_mono.base;
848 nsecs = timekeeping_get_ns(&tk->tkr_mono);
849
850 } while (read_seqcount_retry(&tk_core.seq, seq));
851
852 return ktime_add_ns(base, nsecs);
853}
854EXPORT_SYMBOL_GPL(ktime_get);
855
856u32 ktime_get_resolution_ns(void)
857{
858 struct timekeeper *tk = &tk_core.timekeeper;
859 unsigned int seq;
860 u32 nsecs;
861
862 WARN_ON(timekeeping_suspended);
863
864 do {
865 seq = read_seqcount_begin(&tk_core.seq);
866 nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
867 } while (read_seqcount_retry(&tk_core.seq, seq));
868
869 return nsecs;
870}
871EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
872
873static ktime_t *offsets[TK_OFFS_MAX] = {
874 [TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
875 [TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
876 [TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai,
877};
878
879ktime_t ktime_get_with_offset(enum tk_offsets offs)
880{
881 struct timekeeper *tk = &tk_core.timekeeper;
882 unsigned int seq;
883 ktime_t base, *offset = offsets[offs];
884 u64 nsecs;
885
886 WARN_ON(timekeeping_suspended);
887
888 do {
889 seq = read_seqcount_begin(&tk_core.seq);
890 base = ktime_add(tk->tkr_mono.base, *offset);
891 nsecs = timekeeping_get_ns(&tk->tkr_mono);
892
893 } while (read_seqcount_retry(&tk_core.seq, seq));
894
895 return ktime_add_ns(base, nsecs);
896
897}
898EXPORT_SYMBOL_GPL(ktime_get_with_offset);
899
900ktime_t ktime_get_coarse_with_offset(enum tk_offsets offs)
901{
902 struct timekeeper *tk = &tk_core.timekeeper;
903 unsigned int seq;
904 ktime_t base, *offset = offsets[offs];
905 u64 nsecs;
906
907 WARN_ON(timekeeping_suspended);
908
909 do {
910 seq = read_seqcount_begin(&tk_core.seq);
911 base = ktime_add(tk->tkr_mono.base, *offset);
912 nsecs = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
913
914 } while (read_seqcount_retry(&tk_core.seq, seq));
915
916 return ktime_add_ns(base, nsecs);
917}
918EXPORT_SYMBOL_GPL(ktime_get_coarse_with_offset);
919
920/**
921 * ktime_mono_to_any() - convert monotonic time to any other time
922 * @tmono: time to convert.
923 * @offs: which offset to use
924 */
925ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
926{
927 ktime_t *offset = offsets[offs];
928 unsigned int seq;
929 ktime_t tconv;
930
931 do {
932 seq = read_seqcount_begin(&tk_core.seq);
933 tconv = ktime_add(tmono, *offset);
934 } while (read_seqcount_retry(&tk_core.seq, seq));
935
936 return tconv;
937}
938EXPORT_SYMBOL_GPL(ktime_mono_to_any);
939
940/**
941 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
942 */
943ktime_t ktime_get_raw(void)
944{
945 struct timekeeper *tk = &tk_core.timekeeper;
946 unsigned int seq;
947 ktime_t base;
948 u64 nsecs;
949
950 do {
951 seq = read_seqcount_begin(&tk_core.seq);
952 base = tk->tkr_raw.base;
953 nsecs = timekeeping_get_ns(&tk->tkr_raw);
954
955 } while (read_seqcount_retry(&tk_core.seq, seq));
956
957 return ktime_add_ns(base, nsecs);
958}
959EXPORT_SYMBOL_GPL(ktime_get_raw);
960
961/**
962 * ktime_get_ts64 - get the monotonic clock in timespec64 format
963 * @ts: pointer to timespec variable
964 *
965 * The function calculates the monotonic clock from the realtime
966 * clock and the wall_to_monotonic offset and stores the result
967 * in normalized timespec64 format in the variable pointed to by @ts.
968 */
969void ktime_get_ts64(struct timespec64 *ts)
970{
971 struct timekeeper *tk = &tk_core.timekeeper;
972 struct timespec64 tomono;
973 unsigned int seq;
974 u64 nsec;
975
976 WARN_ON(timekeeping_suspended);
977
978 do {
979 seq = read_seqcount_begin(&tk_core.seq);
980 ts->tv_sec = tk->xtime_sec;
981 nsec = timekeeping_get_ns(&tk->tkr_mono);
982 tomono = tk->wall_to_monotonic;
983
984 } while (read_seqcount_retry(&tk_core.seq, seq));
985
986 ts->tv_sec += tomono.tv_sec;
987 ts->tv_nsec = 0;
988 timespec64_add_ns(ts, nsec + tomono.tv_nsec);
989}
990EXPORT_SYMBOL_GPL(ktime_get_ts64);
991
992/**
993 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
994 *
995 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
996 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
997 * works on both 32 and 64 bit systems. On 32 bit systems the readout
998 * covers ~136 years of uptime which should be enough to prevent
999 * premature wrap arounds.
1000 */
1001time64_t ktime_get_seconds(void)
1002{
1003 struct timekeeper *tk = &tk_core.timekeeper;
1004
1005 WARN_ON(timekeeping_suspended);
1006 return tk->ktime_sec;
1007}
1008EXPORT_SYMBOL_GPL(ktime_get_seconds);
1009
1010/**
1011 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
1012 *
1013 * Returns the wall clock seconds since 1970.
1014 *
1015 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
1016 * 32bit systems the access must be protected with the sequence
1017 * counter to provide "atomic" access to the 64bit tk->xtime_sec
1018 * value.
1019 */
1020time64_t ktime_get_real_seconds(void)
1021{
1022 struct timekeeper *tk = &tk_core.timekeeper;
1023 time64_t seconds;
1024 unsigned int seq;
1025
1026 if (IS_ENABLED(CONFIG_64BIT))
1027 return tk->xtime_sec;
1028
1029 do {
1030 seq = read_seqcount_begin(&tk_core.seq);
1031 seconds = tk->xtime_sec;
1032
1033 } while (read_seqcount_retry(&tk_core.seq, seq));
1034
1035 return seconds;
1036}
1037EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
1038
1039/**
1040 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
1041 * but without the sequence counter protect. This internal function
1042 * is called just when timekeeping lock is already held.
1043 */
1044noinstr time64_t __ktime_get_real_seconds(void)
1045{
1046 struct timekeeper *tk = &tk_core.timekeeper;
1047
1048 return tk->xtime_sec;
1049}
1050
1051/**
1052 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
1053 * @systime_snapshot: pointer to struct receiving the system time snapshot
1054 */
1055void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
1056{
1057 struct timekeeper *tk = &tk_core.timekeeper;
1058 unsigned int seq;
1059 ktime_t base_raw;
1060 ktime_t base_real;
1061 u64 nsec_raw;
1062 u64 nsec_real;
1063 u64 now;
1064
1065 WARN_ON_ONCE(timekeeping_suspended);
1066
1067 do {
1068 seq = read_seqcount_begin(&tk_core.seq);
1069 now = tk_clock_read(&tk->tkr_mono);
1070 systime_snapshot->cs_id = tk->tkr_mono.clock->id;
1071 systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
1072 systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
1073 base_real = ktime_add(tk->tkr_mono.base,
1074 tk_core.timekeeper.offs_real);
1075 base_raw = tk->tkr_raw.base;
1076 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
1077 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
1078 } while (read_seqcount_retry(&tk_core.seq, seq));
1079
1080 systime_snapshot->cycles = now;
1081 systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
1082 systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
1083}
1084EXPORT_SYMBOL_GPL(ktime_get_snapshot);
1085
1086/* Scale base by mult/div checking for overflow */
1087static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
1088{
1089 u64 tmp, rem;
1090
1091 tmp = div64_u64_rem(*base, div, &rem);
1092
1093 if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
1094 ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
1095 return -EOVERFLOW;
1096 tmp *= mult;
1097
1098 rem = div64_u64(rem * mult, div);
1099 *base = tmp + rem;
1100 return 0;
1101}
1102
1103/**
1104 * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
1105 * @history: Snapshot representing start of history
1106 * @partial_history_cycles: Cycle offset into history (fractional part)
1107 * @total_history_cycles: Total history length in cycles
1108 * @discontinuity: True indicates clock was set on history period
1109 * @ts: Cross timestamp that should be adjusted using
1110 * partial/total ratio
1111 *
1112 * Helper function used by get_device_system_crosststamp() to correct the
1113 * crosstimestamp corresponding to the start of the current interval to the
1114 * system counter value (timestamp point) provided by the driver. The
1115 * total_history_* quantities are the total history starting at the provided
1116 * reference point and ending at the start of the current interval. The cycle
1117 * count between the driver timestamp point and the start of the current
1118 * interval is partial_history_cycles.
1119 */
1120static int adjust_historical_crosststamp(struct system_time_snapshot *history,
1121 u64 partial_history_cycles,
1122 u64 total_history_cycles,
1123 bool discontinuity,
1124 struct system_device_crosststamp *ts)
1125{
1126 struct timekeeper *tk = &tk_core.timekeeper;
1127 u64 corr_raw, corr_real;
1128 bool interp_forward;
1129 int ret;
1130
1131 if (total_history_cycles == 0 || partial_history_cycles == 0)
1132 return 0;
1133
1134 /* Interpolate shortest distance from beginning or end of history */
1135 interp_forward = partial_history_cycles > total_history_cycles / 2;
1136 partial_history_cycles = interp_forward ?
1137 total_history_cycles - partial_history_cycles :
1138 partial_history_cycles;
1139
1140 /*
1141 * Scale the monotonic raw time delta by:
1142 * partial_history_cycles / total_history_cycles
1143 */
1144 corr_raw = (u64)ktime_to_ns(
1145 ktime_sub(ts->sys_monoraw, history->raw));
1146 ret = scale64_check_overflow(partial_history_cycles,
1147 total_history_cycles, &corr_raw);
1148 if (ret)
1149 return ret;
1150
1151 /*
1152 * If there is a discontinuity in the history, scale monotonic raw
1153 * correction by:
1154 * mult(real)/mult(raw) yielding the realtime correction
1155 * Otherwise, calculate the realtime correction similar to monotonic
1156 * raw calculation
1157 */
1158 if (discontinuity) {
1159 corr_real = mul_u64_u32_div
1160 (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1161 } else {
1162 corr_real = (u64)ktime_to_ns(
1163 ktime_sub(ts->sys_realtime, history->real));
1164 ret = scale64_check_overflow(partial_history_cycles,
1165 total_history_cycles, &corr_real);
1166 if (ret)
1167 return ret;
1168 }
1169
1170 /* Fixup monotonic raw and real time time values */
1171 if (interp_forward) {
1172 ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1173 ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1174 } else {
1175 ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1176 ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1177 }
1178
1179 return 0;
1180}
1181
1182/*
1183 * cycle_between - true if test occurs chronologically between before and after
1184 */
1185static bool cycle_between(u64 before, u64 test, u64 after)
1186{
1187 if (test > before && test < after)
1188 return true;
1189 if (test < before && before > after)
1190 return true;
1191 return false;
1192}
1193
1194/**
1195 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1196 * @get_time_fn: Callback to get simultaneous device time and
1197 * system counter from the device driver
1198 * @ctx: Context passed to get_time_fn()
1199 * @history_begin: Historical reference point used to interpolate system
1200 * time when counter provided by the driver is before the current interval
1201 * @xtstamp: Receives simultaneously captured system and device time
1202 *
1203 * Reads a timestamp from a device and correlates it to system time
1204 */
1205int get_device_system_crosststamp(int (*get_time_fn)
1206 (ktime_t *device_time,
1207 struct system_counterval_t *sys_counterval,
1208 void *ctx),
1209 void *ctx,
1210 struct system_time_snapshot *history_begin,
1211 struct system_device_crosststamp *xtstamp)
1212{
1213 struct system_counterval_t system_counterval;
1214 struct timekeeper *tk = &tk_core.timekeeper;
1215 u64 cycles, now, interval_start;
1216 unsigned int clock_was_set_seq = 0;
1217 ktime_t base_real, base_raw;
1218 u64 nsec_real, nsec_raw;
1219 u8 cs_was_changed_seq;
1220 unsigned int seq;
1221 bool do_interp;
1222 int ret;
1223
1224 do {
1225 seq = read_seqcount_begin(&tk_core.seq);
1226 /*
1227 * Try to synchronously capture device time and a system
1228 * counter value calling back into the device driver
1229 */
1230 ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1231 if (ret)
1232 return ret;
1233
1234 /*
1235 * Verify that the clocksource associated with the captured
1236 * system counter value is the same as the currently installed
1237 * timekeeper clocksource
1238 */
1239 if (tk->tkr_mono.clock != system_counterval.cs)
1240 return -ENODEV;
1241 cycles = system_counterval.cycles;
1242
1243 /*
1244 * Check whether the system counter value provided by the
1245 * device driver is on the current timekeeping interval.
1246 */
1247 now = tk_clock_read(&tk->tkr_mono);
1248 interval_start = tk->tkr_mono.cycle_last;
1249 if (!cycle_between(interval_start, cycles, now)) {
1250 clock_was_set_seq = tk->clock_was_set_seq;
1251 cs_was_changed_seq = tk->cs_was_changed_seq;
1252 cycles = interval_start;
1253 do_interp = true;
1254 } else {
1255 do_interp = false;
1256 }
1257
1258 base_real = ktime_add(tk->tkr_mono.base,
1259 tk_core.timekeeper.offs_real);
1260 base_raw = tk->tkr_raw.base;
1261
1262 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1263 system_counterval.cycles);
1264 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1265 system_counterval.cycles);
1266 } while (read_seqcount_retry(&tk_core.seq, seq));
1267
1268 xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1269 xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1270
1271 /*
1272 * Interpolate if necessary, adjusting back from the start of the
1273 * current interval
1274 */
1275 if (do_interp) {
1276 u64 partial_history_cycles, total_history_cycles;
1277 bool discontinuity;
1278
1279 /*
1280 * Check that the counter value occurs after the provided
1281 * history reference and that the history doesn't cross a
1282 * clocksource change
1283 */
1284 if (!history_begin ||
1285 !cycle_between(history_begin->cycles,
1286 system_counterval.cycles, cycles) ||
1287 history_begin->cs_was_changed_seq != cs_was_changed_seq)
1288 return -EINVAL;
1289 partial_history_cycles = cycles - system_counterval.cycles;
1290 total_history_cycles = cycles - history_begin->cycles;
1291 discontinuity =
1292 history_begin->clock_was_set_seq != clock_was_set_seq;
1293
1294 ret = adjust_historical_crosststamp(history_begin,
1295 partial_history_cycles,
1296 total_history_cycles,
1297 discontinuity, xtstamp);
1298 if (ret)
1299 return ret;
1300 }
1301
1302 return 0;
1303}
1304EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1305
1306/**
1307 * do_settimeofday64 - Sets the time of day.
1308 * @ts: pointer to the timespec64 variable containing the new time
1309 *
1310 * Sets the time of day to the new time and update NTP and notify hrtimers
1311 */
1312int do_settimeofday64(const struct timespec64 *ts)
1313{
1314 struct timekeeper *tk = &tk_core.timekeeper;
1315 struct timespec64 ts_delta, xt;
1316 unsigned long flags;
1317 int ret = 0;
1318
1319 if (!timespec64_valid_settod(ts))
1320 return -EINVAL;
1321
1322 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1323 write_seqcount_begin(&tk_core.seq);
1324
1325 timekeeping_forward_now(tk);
1326
1327 xt = tk_xtime(tk);
1328 ts_delta = timespec64_sub(*ts, xt);
1329
1330 if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1331 ret = -EINVAL;
1332 goto out;
1333 }
1334
1335 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1336
1337 tk_set_xtime(tk, ts);
1338out:
1339 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1340
1341 write_seqcount_end(&tk_core.seq);
1342 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1343
1344 /* Signal hrtimers about time change */
1345 clock_was_set(CLOCK_SET_WALL);
1346
1347 if (!ret) {
1348 audit_tk_injoffset(ts_delta);
1349 add_device_randomness(ts, sizeof(*ts));
1350 }
1351
1352 return ret;
1353}
1354EXPORT_SYMBOL(do_settimeofday64);
1355
1356/**
1357 * timekeeping_inject_offset - Adds or subtracts from the current time.
1358 * @ts: Pointer to the timespec variable containing the offset
1359 *
1360 * Adds or subtracts an offset value from the current time.
1361 */
1362static int timekeeping_inject_offset(const struct timespec64 *ts)
1363{
1364 struct timekeeper *tk = &tk_core.timekeeper;
1365 unsigned long flags;
1366 struct timespec64 tmp;
1367 int ret = 0;
1368
1369 if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
1370 return -EINVAL;
1371
1372 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1373 write_seqcount_begin(&tk_core.seq);
1374
1375 timekeeping_forward_now(tk);
1376
1377 /* Make sure the proposed value is valid */
1378 tmp = timespec64_add(tk_xtime(tk), *ts);
1379 if (timespec64_compare(&tk->wall_to_monotonic, ts) > 0 ||
1380 !timespec64_valid_settod(&tmp)) {
1381 ret = -EINVAL;
1382 goto error;
1383 }
1384
1385 tk_xtime_add(tk, ts);
1386 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *ts));
1387
1388error: /* even if we error out, we forwarded the time, so call update */
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 /* Signal hrtimers about time change */
1395 clock_was_set(CLOCK_SET_WALL);
1396
1397 return ret;
1398}
1399
1400/*
1401 * Indicates if there is an offset between the system clock and the hardware
1402 * clock/persistent clock/rtc.
1403 */
1404int persistent_clock_is_local;
1405
1406/*
1407 * Adjust the time obtained from the CMOS to be UTC time instead of
1408 * local time.
1409 *
1410 * This is ugly, but preferable to the alternatives. Otherwise we
1411 * would either need to write a program to do it in /etc/rc (and risk
1412 * confusion if the program gets run more than once; it would also be
1413 * hard to make the program warp the clock precisely n hours) or
1414 * compile in the timezone information into the kernel. Bad, bad....
1415 *
1416 * - TYT, 1992-01-01
1417 *
1418 * The best thing to do is to keep the CMOS clock in universal time (UTC)
1419 * as real UNIX machines always do it. This avoids all headaches about
1420 * daylight saving times and warping kernel clocks.
1421 */
1422void timekeeping_warp_clock(void)
1423{
1424 if (sys_tz.tz_minuteswest != 0) {
1425 struct timespec64 adjust;
1426
1427 persistent_clock_is_local = 1;
1428 adjust.tv_sec = sys_tz.tz_minuteswest * 60;
1429 adjust.tv_nsec = 0;
1430 timekeeping_inject_offset(&adjust);
1431 }
1432}
1433
1434/*
1435 * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1436 */
1437static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1438{
1439 tk->tai_offset = tai_offset;
1440 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1441}
1442
1443/*
1444 * change_clocksource - Swaps clocksources if a new one is available
1445 *
1446 * Accumulates current time interval and initializes new clocksource
1447 */
1448static int change_clocksource(void *data)
1449{
1450 struct timekeeper *tk = &tk_core.timekeeper;
1451 struct clocksource *new, *old = NULL;
1452 unsigned long flags;
1453 bool change = false;
1454
1455 new = (struct clocksource *) data;
1456
1457 /*
1458 * If the cs is in module, get a module reference. Succeeds
1459 * for built-in code (owner == NULL) as well.
1460 */
1461 if (try_module_get(new->owner)) {
1462 if (!new->enable || new->enable(new) == 0)
1463 change = true;
1464 else
1465 module_put(new->owner);
1466 }
1467
1468 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1469 write_seqcount_begin(&tk_core.seq);
1470
1471 timekeeping_forward_now(tk);
1472
1473 if (change) {
1474 old = tk->tkr_mono.clock;
1475 tk_setup_internals(tk, new);
1476 }
1477
1478 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1479
1480 write_seqcount_end(&tk_core.seq);
1481 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1482
1483 if (old) {
1484 if (old->disable)
1485 old->disable(old);
1486
1487 module_put(old->owner);
1488 }
1489
1490 return 0;
1491}
1492
1493/**
1494 * timekeeping_notify - Install a new clock source
1495 * @clock: pointer to the clock source
1496 *
1497 * This function is called from clocksource.c after a new, better clock
1498 * source has been registered. The caller holds the clocksource_mutex.
1499 */
1500int timekeeping_notify(struct clocksource *clock)
1501{
1502 struct timekeeper *tk = &tk_core.timekeeper;
1503
1504 if (tk->tkr_mono.clock == clock)
1505 return 0;
1506 stop_machine(change_clocksource, clock, NULL);
1507 tick_clock_notify();
1508 return tk->tkr_mono.clock == clock ? 0 : -1;
1509}
1510
1511/**
1512 * ktime_get_raw_ts64 - Returns the raw monotonic time in a timespec
1513 * @ts: pointer to the timespec64 to be set
1514 *
1515 * Returns the raw monotonic time (completely un-modified by ntp)
1516 */
1517void ktime_get_raw_ts64(struct timespec64 *ts)
1518{
1519 struct timekeeper *tk = &tk_core.timekeeper;
1520 unsigned int seq;
1521 u64 nsecs;
1522
1523 do {
1524 seq = read_seqcount_begin(&tk_core.seq);
1525 ts->tv_sec = tk->raw_sec;
1526 nsecs = timekeeping_get_ns(&tk->tkr_raw);
1527
1528 } while (read_seqcount_retry(&tk_core.seq, seq));
1529
1530 ts->tv_nsec = 0;
1531 timespec64_add_ns(ts, nsecs);
1532}
1533EXPORT_SYMBOL(ktime_get_raw_ts64);
1534
1535
1536/**
1537 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1538 */
1539int timekeeping_valid_for_hres(void)
1540{
1541 struct timekeeper *tk = &tk_core.timekeeper;
1542 unsigned int seq;
1543 int ret;
1544
1545 do {
1546 seq = read_seqcount_begin(&tk_core.seq);
1547
1548 ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1549
1550 } while (read_seqcount_retry(&tk_core.seq, seq));
1551
1552 return ret;
1553}
1554
1555/**
1556 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1557 */
1558u64 timekeeping_max_deferment(void)
1559{
1560 struct timekeeper *tk = &tk_core.timekeeper;
1561 unsigned int seq;
1562 u64 ret;
1563
1564 do {
1565 seq = read_seqcount_begin(&tk_core.seq);
1566
1567 ret = tk->tkr_mono.clock->max_idle_ns;
1568
1569 } while (read_seqcount_retry(&tk_core.seq, seq));
1570
1571 return ret;
1572}
1573
1574/**
1575 * read_persistent_clock64 - Return time from the persistent clock.
1576 * @ts: Pointer to the storage for the readout value
1577 *
1578 * Weak dummy function for arches that do not yet support it.
1579 * Reads the time from the battery backed persistent clock.
1580 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1581 *
1582 * XXX - Do be sure to remove it once all arches implement it.
1583 */
1584void __weak read_persistent_clock64(struct timespec64 *ts)
1585{
1586 ts->tv_sec = 0;
1587 ts->tv_nsec = 0;
1588}
1589
1590/**
1591 * read_persistent_wall_and_boot_offset - Read persistent clock, and also offset
1592 * from the boot.
1593 * @wall_time: current time as returned by persistent clock
1594 * @boot_offset: offset that is defined as wall_time - boot_time
1595 *
1596 * Weak dummy function for arches that do not yet support it.
1597 *
1598 * The default function calculates offset based on the current value of
1599 * local_clock(). This way architectures that support sched_clock() but don't
1600 * support dedicated boot time clock will provide the best estimate of the
1601 * boot time.
1602 */
1603void __weak __init
1604read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
1605 struct timespec64 *boot_offset)
1606{
1607 read_persistent_clock64(wall_time);
1608 *boot_offset = ns_to_timespec64(local_clock());
1609}
1610
1611/*
1612 * Flag reflecting whether timekeeping_resume() has injected sleeptime.
1613 *
1614 * The flag starts of false and is only set when a suspend reaches
1615 * timekeeping_suspend(), timekeeping_resume() sets it to false when the
1616 * timekeeper clocksource is not stopping across suspend and has been
1617 * used to update sleep time. If the timekeeper clocksource has stopped
1618 * then the flag stays true and is used by the RTC resume code to decide
1619 * whether sleeptime must be injected and if so the flag gets false then.
1620 *
1621 * If a suspend fails before reaching timekeeping_resume() then the flag
1622 * stays false and prevents erroneous sleeptime injection.
1623 */
1624static bool suspend_timing_needed;
1625
1626/* Flag for if there is a persistent clock on this platform */
1627static bool persistent_clock_exists;
1628
1629/*
1630 * timekeeping_init - Initializes the clocksource and common timekeeping values
1631 */
1632void __init timekeeping_init(void)
1633{
1634 struct timespec64 wall_time, boot_offset, wall_to_mono;
1635 struct timekeeper *tk = &tk_core.timekeeper;
1636 struct clocksource *clock;
1637 unsigned long flags;
1638
1639 read_persistent_wall_and_boot_offset(&wall_time, &boot_offset);
1640 if (timespec64_valid_settod(&wall_time) &&
1641 timespec64_to_ns(&wall_time) > 0) {
1642 persistent_clock_exists = true;
1643 } else if (timespec64_to_ns(&wall_time) != 0) {
1644 pr_warn("Persistent clock returned invalid value");
1645 wall_time = (struct timespec64){0};
1646 }
1647
1648 if (timespec64_compare(&wall_time, &boot_offset) < 0)
1649 boot_offset = (struct timespec64){0};
1650
1651 /*
1652 * We want set wall_to_mono, so the following is true:
1653 * wall time + wall_to_mono = boot time
1654 */
1655 wall_to_mono = timespec64_sub(boot_offset, wall_time);
1656
1657 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1658 write_seqcount_begin(&tk_core.seq);
1659 ntp_init();
1660
1661 clock = clocksource_default_clock();
1662 if (clock->enable)
1663 clock->enable(clock);
1664 tk_setup_internals(tk, clock);
1665
1666 tk_set_xtime(tk, &wall_time);
1667 tk->raw_sec = 0;
1668
1669 tk_set_wall_to_mono(tk, wall_to_mono);
1670
1671 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1672
1673 write_seqcount_end(&tk_core.seq);
1674 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1675}
1676
1677/* time in seconds when suspend began for persistent clock */
1678static struct timespec64 timekeeping_suspend_time;
1679
1680/**
1681 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1682 * @tk: Pointer to the timekeeper to be updated
1683 * @delta: Pointer to the delta value in timespec64 format
1684 *
1685 * Takes a timespec offset measuring a suspend interval and properly
1686 * adds the sleep offset to the timekeeping variables.
1687 */
1688static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1689 const struct timespec64 *delta)
1690{
1691 if (!timespec64_valid_strict(delta)) {
1692 printk_deferred(KERN_WARNING
1693 "__timekeeping_inject_sleeptime: Invalid "
1694 "sleep delta value!\n");
1695 return;
1696 }
1697 tk_xtime_add(tk, delta);
1698 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1699 tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1700 tk_debug_account_sleep_time(delta);
1701}
1702
1703#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1704/*
1705 * We have three kinds of time sources to use for sleep time
1706 * injection, the preference order is:
1707 * 1) non-stop clocksource
1708 * 2) persistent clock (ie: RTC accessible when irqs are off)
1709 * 3) RTC
1710 *
1711 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1712 * If system has neither 1) nor 2), 3) will be used finally.
1713 *
1714 *
1715 * If timekeeping has injected sleeptime via either 1) or 2),
1716 * 3) becomes needless, so in this case we don't need to call
1717 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1718 * means.
1719 */
1720bool timekeeping_rtc_skipresume(void)
1721{
1722 return !suspend_timing_needed;
1723}
1724
1725/*
1726 * 1) can be determined whether to use or not only when doing
1727 * timekeeping_resume() which is invoked after rtc_suspend(),
1728 * so we can't skip rtc_suspend() surely if system has 1).
1729 *
1730 * But if system has 2), 2) will definitely be used, so in this
1731 * case we don't need to call rtc_suspend(), and this is what
1732 * timekeeping_rtc_skipsuspend() means.
1733 */
1734bool timekeeping_rtc_skipsuspend(void)
1735{
1736 return persistent_clock_exists;
1737}
1738
1739/**
1740 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1741 * @delta: pointer to a timespec64 delta value
1742 *
1743 * This hook is for architectures that cannot support read_persistent_clock64
1744 * because their RTC/persistent clock is only accessible when irqs are enabled.
1745 * and also don't have an effective nonstop clocksource.
1746 *
1747 * This function should only be called by rtc_resume(), and allows
1748 * a suspend offset to be injected into the timekeeping values.
1749 */
1750void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
1751{
1752 struct timekeeper *tk = &tk_core.timekeeper;
1753 unsigned long flags;
1754
1755 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1756 write_seqcount_begin(&tk_core.seq);
1757
1758 suspend_timing_needed = false;
1759
1760 timekeeping_forward_now(tk);
1761
1762 __timekeeping_inject_sleeptime(tk, delta);
1763
1764 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1765
1766 write_seqcount_end(&tk_core.seq);
1767 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1768
1769 /* Signal hrtimers about time change */
1770 clock_was_set(CLOCK_SET_WALL | CLOCK_SET_BOOT);
1771}
1772#endif
1773
1774/**
1775 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1776 */
1777void timekeeping_resume(void)
1778{
1779 struct timekeeper *tk = &tk_core.timekeeper;
1780 struct clocksource *clock = tk->tkr_mono.clock;
1781 unsigned long flags;
1782 struct timespec64 ts_new, ts_delta;
1783 u64 cycle_now, nsec;
1784 bool inject_sleeptime = false;
1785
1786 read_persistent_clock64(&ts_new);
1787
1788 clockevents_resume();
1789 clocksource_resume();
1790
1791 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1792 write_seqcount_begin(&tk_core.seq);
1793
1794 /*
1795 * After system resumes, we need to calculate the suspended time and
1796 * compensate it for the OS time. There are 3 sources that could be
1797 * used: Nonstop clocksource during suspend, persistent clock and rtc
1798 * device.
1799 *
1800 * One specific platform may have 1 or 2 or all of them, and the
1801 * preference will be:
1802 * suspend-nonstop clocksource -> persistent clock -> rtc
1803 * The less preferred source will only be tried if there is no better
1804 * usable source. The rtc part is handled separately in rtc core code.
1805 */
1806 cycle_now = tk_clock_read(&tk->tkr_mono);
1807 nsec = clocksource_stop_suspend_timing(clock, cycle_now);
1808 if (nsec > 0) {
1809 ts_delta = ns_to_timespec64(nsec);
1810 inject_sleeptime = true;
1811 } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1812 ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1813 inject_sleeptime = true;
1814 }
1815
1816 if (inject_sleeptime) {
1817 suspend_timing_needed = false;
1818 __timekeeping_inject_sleeptime(tk, &ts_delta);
1819 }
1820
1821 /* Re-base the last cycle value */
1822 tk->tkr_mono.cycle_last = cycle_now;
1823 tk->tkr_raw.cycle_last = cycle_now;
1824
1825 tk->ntp_error = 0;
1826 timekeeping_suspended = 0;
1827 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1828 write_seqcount_end(&tk_core.seq);
1829 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1830
1831 touch_softlockup_watchdog();
1832
1833 /* Resume the clockevent device(s) and hrtimers */
1834 tick_resume();
1835 /* Notify timerfd as resume is equivalent to clock_was_set() */
1836 timerfd_resume();
1837}
1838
1839int timekeeping_suspend(void)
1840{
1841 struct timekeeper *tk = &tk_core.timekeeper;
1842 unsigned long flags;
1843 struct timespec64 delta, delta_delta;
1844 static struct timespec64 old_delta;
1845 struct clocksource *curr_clock;
1846 u64 cycle_now;
1847
1848 read_persistent_clock64(&timekeeping_suspend_time);
1849
1850 /*
1851 * On some systems the persistent_clock can not be detected at
1852 * timekeeping_init by its return value, so if we see a valid
1853 * value returned, update the persistent_clock_exists flag.
1854 */
1855 if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1856 persistent_clock_exists = true;
1857
1858 suspend_timing_needed = true;
1859
1860 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1861 write_seqcount_begin(&tk_core.seq);
1862 timekeeping_forward_now(tk);
1863 timekeeping_suspended = 1;
1864
1865 /*
1866 * Since we've called forward_now, cycle_last stores the value
1867 * just read from the current clocksource. Save this to potentially
1868 * use in suspend timing.
1869 */
1870 curr_clock = tk->tkr_mono.clock;
1871 cycle_now = tk->tkr_mono.cycle_last;
1872 clocksource_start_suspend_timing(curr_clock, cycle_now);
1873
1874 if (persistent_clock_exists) {
1875 /*
1876 * To avoid drift caused by repeated suspend/resumes,
1877 * which each can add ~1 second drift error,
1878 * try to compensate so the difference in system time
1879 * and persistent_clock time stays close to constant.
1880 */
1881 delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1882 delta_delta = timespec64_sub(delta, old_delta);
1883 if (abs(delta_delta.tv_sec) >= 2) {
1884 /*
1885 * if delta_delta is too large, assume time correction
1886 * has occurred and set old_delta to the current delta.
1887 */
1888 old_delta = delta;
1889 } else {
1890 /* Otherwise try to adjust old_system to compensate */
1891 timekeeping_suspend_time =
1892 timespec64_add(timekeeping_suspend_time, delta_delta);
1893 }
1894 }
1895
1896 timekeeping_update(tk, TK_MIRROR);
1897 halt_fast_timekeeper(tk);
1898 write_seqcount_end(&tk_core.seq);
1899 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1900
1901 tick_suspend();
1902 clocksource_suspend();
1903 clockevents_suspend();
1904
1905 return 0;
1906}
1907
1908/* sysfs resume/suspend bits for timekeeping */
1909static struct syscore_ops timekeeping_syscore_ops = {
1910 .resume = timekeeping_resume,
1911 .suspend = timekeeping_suspend,
1912};
1913
1914static int __init timekeeping_init_ops(void)
1915{
1916 register_syscore_ops(&timekeeping_syscore_ops);
1917 return 0;
1918}
1919device_initcall(timekeeping_init_ops);
1920
1921/*
1922 * Apply a multiplier adjustment to the timekeeper
1923 */
1924static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1925 s64 offset,
1926 s32 mult_adj)
1927{
1928 s64 interval = tk->cycle_interval;
1929
1930 if (mult_adj == 0) {
1931 return;
1932 } else if (mult_adj == -1) {
1933 interval = -interval;
1934 offset = -offset;
1935 } else if (mult_adj != 1) {
1936 interval *= mult_adj;
1937 offset *= mult_adj;
1938 }
1939
1940 /*
1941 * So the following can be confusing.
1942 *
1943 * To keep things simple, lets assume mult_adj == 1 for now.
1944 *
1945 * When mult_adj != 1, remember that the interval and offset values
1946 * have been appropriately scaled so the math is the same.
1947 *
1948 * The basic idea here is that we're increasing the multiplier
1949 * by one, this causes the xtime_interval to be incremented by
1950 * one cycle_interval. This is because:
1951 * xtime_interval = cycle_interval * mult
1952 * So if mult is being incremented by one:
1953 * xtime_interval = cycle_interval * (mult + 1)
1954 * Its the same as:
1955 * xtime_interval = (cycle_interval * mult) + cycle_interval
1956 * Which can be shortened to:
1957 * xtime_interval += cycle_interval
1958 *
1959 * So offset stores the non-accumulated cycles. Thus the current
1960 * time (in shifted nanoseconds) is:
1961 * now = (offset * adj) + xtime_nsec
1962 * Now, even though we're adjusting the clock frequency, we have
1963 * to keep time consistent. In other words, we can't jump back
1964 * in time, and we also want to avoid jumping forward in time.
1965 *
1966 * So given the same offset value, we need the time to be the same
1967 * both before and after the freq adjustment.
1968 * now = (offset * adj_1) + xtime_nsec_1
1969 * now = (offset * adj_2) + xtime_nsec_2
1970 * So:
1971 * (offset * adj_1) + xtime_nsec_1 =
1972 * (offset * adj_2) + xtime_nsec_2
1973 * And we know:
1974 * adj_2 = adj_1 + 1
1975 * So:
1976 * (offset * adj_1) + xtime_nsec_1 =
1977 * (offset * (adj_1+1)) + xtime_nsec_2
1978 * (offset * adj_1) + xtime_nsec_1 =
1979 * (offset * adj_1) + offset + xtime_nsec_2
1980 * Canceling the sides:
1981 * xtime_nsec_1 = offset + xtime_nsec_2
1982 * Which gives us:
1983 * xtime_nsec_2 = xtime_nsec_1 - offset
1984 * Which simplifies to:
1985 * xtime_nsec -= offset
1986 */
1987 if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1988 /* NTP adjustment caused clocksource mult overflow */
1989 WARN_ON_ONCE(1);
1990 return;
1991 }
1992
1993 tk->tkr_mono.mult += mult_adj;
1994 tk->xtime_interval += interval;
1995 tk->tkr_mono.xtime_nsec -= offset;
1996}
1997
1998/*
1999 * Adjust the timekeeper's multiplier to the correct frequency
2000 * and also to reduce the accumulated error value.
2001 */
2002static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
2003{
2004 u32 mult;
2005
2006 /*
2007 * Determine the multiplier from the current NTP tick length.
2008 * Avoid expensive division when the tick length doesn't change.
2009 */
2010 if (likely(tk->ntp_tick == ntp_tick_length())) {
2011 mult = tk->tkr_mono.mult - tk->ntp_err_mult;
2012 } else {
2013 tk->ntp_tick = ntp_tick_length();
2014 mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) -
2015 tk->xtime_remainder, tk->cycle_interval);
2016 }
2017
2018 /*
2019 * If the clock is behind the NTP time, increase the multiplier by 1
2020 * to catch up with it. If it's ahead and there was a remainder in the
2021 * tick division, the clock will slow down. Otherwise it will stay
2022 * ahead until the tick length changes to a non-divisible value.
2023 */
2024 tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0;
2025 mult += tk->ntp_err_mult;
2026
2027 timekeeping_apply_adjustment(tk, offset, mult - tk->tkr_mono.mult);
2028
2029 if (unlikely(tk->tkr_mono.clock->maxadj &&
2030 (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
2031 > tk->tkr_mono.clock->maxadj))) {
2032 printk_once(KERN_WARNING
2033 "Adjusting %s more than 11%% (%ld vs %ld)\n",
2034 tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
2035 (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
2036 }
2037
2038 /*
2039 * It may be possible that when we entered this function, xtime_nsec
2040 * was very small. Further, if we're slightly speeding the clocksource
2041 * in the code above, its possible the required corrective factor to
2042 * xtime_nsec could cause it to underflow.
2043 *
2044 * Now, since we have already accumulated the second and the NTP
2045 * subsystem has been notified via second_overflow(), we need to skip
2046 * the next update.
2047 */
2048 if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
2049 tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC <<
2050 tk->tkr_mono.shift;
2051 tk->xtime_sec--;
2052 tk->skip_second_overflow = 1;
2053 }
2054}
2055
2056/*
2057 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
2058 *
2059 * Helper function that accumulates the nsecs greater than a second
2060 * from the xtime_nsec field to the xtime_secs field.
2061 * It also calls into the NTP code to handle leapsecond processing.
2062 */
2063static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
2064{
2065 u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
2066 unsigned int clock_set = 0;
2067
2068 while (tk->tkr_mono.xtime_nsec >= nsecps) {
2069 int leap;
2070
2071 tk->tkr_mono.xtime_nsec -= nsecps;
2072 tk->xtime_sec++;
2073
2074 /*
2075 * Skip NTP update if this second was accumulated before,
2076 * i.e. xtime_nsec underflowed in timekeeping_adjust()
2077 */
2078 if (unlikely(tk->skip_second_overflow)) {
2079 tk->skip_second_overflow = 0;
2080 continue;
2081 }
2082
2083 /* Figure out if its a leap sec and apply if needed */
2084 leap = second_overflow(tk->xtime_sec);
2085 if (unlikely(leap)) {
2086 struct timespec64 ts;
2087
2088 tk->xtime_sec += leap;
2089
2090 ts.tv_sec = leap;
2091 ts.tv_nsec = 0;
2092 tk_set_wall_to_mono(tk,
2093 timespec64_sub(tk->wall_to_monotonic, ts));
2094
2095 __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
2096
2097 clock_set = TK_CLOCK_WAS_SET;
2098 }
2099 }
2100 return clock_set;
2101}
2102
2103/*
2104 * logarithmic_accumulation - shifted accumulation of cycles
2105 *
2106 * This functions accumulates a shifted interval of cycles into
2107 * a shifted interval nanoseconds. Allows for O(log) accumulation
2108 * loop.
2109 *
2110 * Returns the unconsumed cycles.
2111 */
2112static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2113 u32 shift, unsigned int *clock_set)
2114{
2115 u64 interval = tk->cycle_interval << shift;
2116 u64 snsec_per_sec;
2117
2118 /* If the offset is smaller than a shifted interval, do nothing */
2119 if (offset < interval)
2120 return offset;
2121
2122 /* Accumulate one shifted interval */
2123 offset -= interval;
2124 tk->tkr_mono.cycle_last += interval;
2125 tk->tkr_raw.cycle_last += interval;
2126
2127 tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2128 *clock_set |= accumulate_nsecs_to_secs(tk);
2129
2130 /* Accumulate raw time */
2131 tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2132 snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2133 while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2134 tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2135 tk->raw_sec++;
2136 }
2137
2138 /* Accumulate error between NTP and clock interval */
2139 tk->ntp_error += tk->ntp_tick << shift;
2140 tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2141 (tk->ntp_error_shift + shift);
2142
2143 return offset;
2144}
2145
2146/*
2147 * timekeeping_advance - Updates the timekeeper to the current time and
2148 * current NTP tick length
2149 */
2150static bool timekeeping_advance(enum timekeeping_adv_mode mode)
2151{
2152 struct timekeeper *real_tk = &tk_core.timekeeper;
2153 struct timekeeper *tk = &shadow_timekeeper;
2154 u64 offset;
2155 int shift = 0, maxshift;
2156 unsigned int clock_set = 0;
2157 unsigned long flags;
2158
2159 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2160
2161 /* Make sure we're fully resumed: */
2162 if (unlikely(timekeeping_suspended))
2163 goto out;
2164
2165 offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
2166 tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2167
2168 /* Check if there's really nothing to do */
2169 if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK)
2170 goto out;
2171
2172 /* Do some additional sanity checking */
2173 timekeeping_check_update(tk, offset);
2174
2175 /*
2176 * With NO_HZ we may have to accumulate many cycle_intervals
2177 * (think "ticks") worth of time at once. To do this efficiently,
2178 * we calculate the largest doubling multiple of cycle_intervals
2179 * that is smaller than the offset. We then accumulate that
2180 * chunk in one go, and then try to consume the next smaller
2181 * doubled multiple.
2182 */
2183 shift = ilog2(offset) - ilog2(tk->cycle_interval);
2184 shift = max(0, shift);
2185 /* Bound shift to one less than what overflows tick_length */
2186 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2187 shift = min(shift, maxshift);
2188 while (offset >= tk->cycle_interval) {
2189 offset = logarithmic_accumulation(tk, offset, shift,
2190 &clock_set);
2191 if (offset < tk->cycle_interval<<shift)
2192 shift--;
2193 }
2194
2195 /* Adjust the multiplier to correct NTP error */
2196 timekeeping_adjust(tk, offset);
2197
2198 /*
2199 * Finally, make sure that after the rounding
2200 * xtime_nsec isn't larger than NSEC_PER_SEC
2201 */
2202 clock_set |= accumulate_nsecs_to_secs(tk);
2203
2204 write_seqcount_begin(&tk_core.seq);
2205 /*
2206 * Update the real timekeeper.
2207 *
2208 * We could avoid this memcpy by switching pointers, but that
2209 * requires changes to all other timekeeper usage sites as
2210 * well, i.e. move the timekeeper pointer getter into the
2211 * spinlocked/seqcount protected sections. And we trade this
2212 * memcpy under the tk_core.seq against one before we start
2213 * updating.
2214 */
2215 timekeeping_update(tk, clock_set);
2216 memcpy(real_tk, tk, sizeof(*tk));
2217 /* The memcpy must come last. Do not put anything here! */
2218 write_seqcount_end(&tk_core.seq);
2219out:
2220 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2221
2222 return !!clock_set;
2223}
2224
2225/**
2226 * update_wall_time - Uses the current clocksource to increment the wall time
2227 *
2228 */
2229void update_wall_time(void)
2230{
2231 if (timekeeping_advance(TK_ADV_TICK))
2232 clock_was_set_delayed();
2233}
2234
2235/**
2236 * getboottime64 - Return the real time of system boot.
2237 * @ts: pointer to the timespec64 to be set
2238 *
2239 * Returns the wall-time of boot in a timespec64.
2240 *
2241 * This is based on the wall_to_monotonic offset and the total suspend
2242 * time. Calls to settimeofday will affect the value returned (which
2243 * basically means that however wrong your real time clock is at boot time,
2244 * you get the right time here).
2245 */
2246void getboottime64(struct timespec64 *ts)
2247{
2248 struct timekeeper *tk = &tk_core.timekeeper;
2249 ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2250
2251 *ts = ktime_to_timespec64(t);
2252}
2253EXPORT_SYMBOL_GPL(getboottime64);
2254
2255void ktime_get_coarse_real_ts64(struct timespec64 *ts)
2256{
2257 struct timekeeper *tk = &tk_core.timekeeper;
2258 unsigned int seq;
2259
2260 do {
2261 seq = read_seqcount_begin(&tk_core.seq);
2262
2263 *ts = tk_xtime(tk);
2264 } while (read_seqcount_retry(&tk_core.seq, seq));
2265}
2266EXPORT_SYMBOL(ktime_get_coarse_real_ts64);
2267
2268void ktime_get_coarse_ts64(struct timespec64 *ts)
2269{
2270 struct timekeeper *tk = &tk_core.timekeeper;
2271 struct timespec64 now, mono;
2272 unsigned int seq;
2273
2274 do {
2275 seq = read_seqcount_begin(&tk_core.seq);
2276
2277 now = tk_xtime(tk);
2278 mono = tk->wall_to_monotonic;
2279 } while (read_seqcount_retry(&tk_core.seq, seq));
2280
2281 set_normalized_timespec64(ts, now.tv_sec + mono.tv_sec,
2282 now.tv_nsec + mono.tv_nsec);
2283}
2284EXPORT_SYMBOL(ktime_get_coarse_ts64);
2285
2286/*
2287 * Must hold jiffies_lock
2288 */
2289void do_timer(unsigned long ticks)
2290{
2291 jiffies_64 += ticks;
2292 calc_global_load();
2293}
2294
2295/**
2296 * ktime_get_update_offsets_now - hrtimer helper
2297 * @cwsseq: pointer to check and store the clock was set sequence number
2298 * @offs_real: pointer to storage for monotonic -> realtime offset
2299 * @offs_boot: pointer to storage for monotonic -> boottime offset
2300 * @offs_tai: pointer to storage for monotonic -> clock tai offset
2301 *
2302 * Returns current monotonic time and updates the offsets if the
2303 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2304 * different.
2305 *
2306 * Called from hrtimer_interrupt() or retrigger_next_event()
2307 */
2308ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2309 ktime_t *offs_boot, ktime_t *offs_tai)
2310{
2311 struct timekeeper *tk = &tk_core.timekeeper;
2312 unsigned int seq;
2313 ktime_t base;
2314 u64 nsecs;
2315
2316 do {
2317 seq = read_seqcount_begin(&tk_core.seq);
2318
2319 base = tk->tkr_mono.base;
2320 nsecs = timekeeping_get_ns(&tk->tkr_mono);
2321 base = ktime_add_ns(base, nsecs);
2322
2323 if (*cwsseq != tk->clock_was_set_seq) {
2324 *cwsseq = tk->clock_was_set_seq;
2325 *offs_real = tk->offs_real;
2326 *offs_boot = tk->offs_boot;
2327 *offs_tai = tk->offs_tai;
2328 }
2329
2330 /* Handle leapsecond insertion adjustments */
2331 if (unlikely(base >= tk->next_leap_ktime))
2332 *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2333
2334 } while (read_seqcount_retry(&tk_core.seq, seq));
2335
2336 return base;
2337}
2338
2339/*
2340 * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2341 */
2342static int timekeeping_validate_timex(const struct __kernel_timex *txc)
2343{
2344 if (txc->modes & ADJ_ADJTIME) {
2345 /* singleshot must not be used with any other mode bits */
2346 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2347 return -EINVAL;
2348 if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2349 !capable(CAP_SYS_TIME))
2350 return -EPERM;
2351 } else {
2352 /* In order to modify anything, you gotta be super-user! */
2353 if (txc->modes && !capable(CAP_SYS_TIME))
2354 return -EPERM;
2355 /*
2356 * if the quartz is off by more than 10% then
2357 * something is VERY wrong!
2358 */
2359 if (txc->modes & ADJ_TICK &&
2360 (txc->tick < 900000/USER_HZ ||
2361 txc->tick > 1100000/USER_HZ))
2362 return -EINVAL;
2363 }
2364
2365 if (txc->modes & ADJ_SETOFFSET) {
2366 /* In order to inject time, you gotta be super-user! */
2367 if (!capable(CAP_SYS_TIME))
2368 return -EPERM;
2369
2370 /*
2371 * Validate if a timespec/timeval used to inject a time
2372 * offset is valid. Offsets can be positive or negative, so
2373 * we don't check tv_sec. The value of the timeval/timespec
2374 * is the sum of its fields,but *NOTE*:
2375 * The field tv_usec/tv_nsec must always be non-negative and
2376 * we can't have more nanoseconds/microseconds than a second.
2377 */
2378 if (txc->time.tv_usec < 0)
2379 return -EINVAL;
2380
2381 if (txc->modes & ADJ_NANO) {
2382 if (txc->time.tv_usec >= NSEC_PER_SEC)
2383 return -EINVAL;
2384 } else {
2385 if (txc->time.tv_usec >= USEC_PER_SEC)
2386 return -EINVAL;
2387 }
2388 }
2389
2390 /*
2391 * Check for potential multiplication overflows that can
2392 * only happen on 64-bit systems:
2393 */
2394 if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2395 if (LLONG_MIN / PPM_SCALE > txc->freq)
2396 return -EINVAL;
2397 if (LLONG_MAX / PPM_SCALE < txc->freq)
2398 return -EINVAL;
2399 }
2400
2401 return 0;
2402}
2403
2404/**
2405 * random_get_entropy_fallback - Returns the raw clock source value,
2406 * used by random.c for platforms with no valid random_get_entropy().
2407 */
2408unsigned long random_get_entropy_fallback(void)
2409{
2410 struct tk_read_base *tkr = &tk_core.timekeeper.tkr_mono;
2411 struct clocksource *clock = READ_ONCE(tkr->clock);
2412
2413 if (unlikely(timekeeping_suspended || !clock))
2414 return 0;
2415 return clock->read(clock);
2416}
2417EXPORT_SYMBOL_GPL(random_get_entropy_fallback);
2418
2419/**
2420 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2421 */
2422int do_adjtimex(struct __kernel_timex *txc)
2423{
2424 struct timekeeper *tk = &tk_core.timekeeper;
2425 struct audit_ntp_data ad;
2426 bool clock_set = false;
2427 struct timespec64 ts;
2428 unsigned long flags;
2429 s32 orig_tai, tai;
2430 int ret;
2431
2432 /* Validate the data before disabling interrupts */
2433 ret = timekeeping_validate_timex(txc);
2434 if (ret)
2435 return ret;
2436 add_device_randomness(txc, sizeof(*txc));
2437
2438 if (txc->modes & ADJ_SETOFFSET) {
2439 struct timespec64 delta;
2440 delta.tv_sec = txc->time.tv_sec;
2441 delta.tv_nsec = txc->time.tv_usec;
2442 if (!(txc->modes & ADJ_NANO))
2443 delta.tv_nsec *= 1000;
2444 ret = timekeeping_inject_offset(&delta);
2445 if (ret)
2446 return ret;
2447
2448 audit_tk_injoffset(delta);
2449 }
2450
2451 audit_ntp_init(&ad);
2452
2453 ktime_get_real_ts64(&ts);
2454 add_device_randomness(&ts, sizeof(ts));
2455
2456 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2457 write_seqcount_begin(&tk_core.seq);
2458
2459 orig_tai = tai = tk->tai_offset;
2460 ret = __do_adjtimex(txc, &ts, &tai, &ad);
2461
2462 if (tai != orig_tai) {
2463 __timekeeping_set_tai_offset(tk, tai);
2464 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2465 clock_set = true;
2466 }
2467 tk_update_leap_state(tk);
2468
2469 write_seqcount_end(&tk_core.seq);
2470 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2471
2472 audit_ntp_log(&ad);
2473
2474 /* Update the multiplier immediately if frequency was set directly */
2475 if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
2476 clock_set |= timekeeping_advance(TK_ADV_FREQ);
2477
2478 if (clock_set)
2479 clock_was_set(CLOCK_REALTIME);
2480
2481 ntp_notify_cmos_timer();
2482
2483 return ret;
2484}
2485
2486#ifdef CONFIG_NTP_PPS
2487/**
2488 * hardpps() - Accessor function to NTP __hardpps function
2489 */
2490void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2491{
2492 unsigned long flags;
2493
2494 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2495 write_seqcount_begin(&tk_core.seq);
2496
2497 __hardpps(phase_ts, raw_ts);
2498
2499 write_seqcount_end(&tk_core.seq);
2500 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2501}
2502EXPORT_SYMBOL(hardpps);
2503#endif /* CONFIG_NTP_PPS */
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
35/*
36 * The most important data for readout fits into a single 64 byte
37 * cache line.
38 */
39static struct {
40 seqcount_t seq;
41 struct timekeeper timekeeper;
42} tk_core ____cacheline_aligned;
43
44static DEFINE_RAW_SPINLOCK(timekeeper_lock);
45static struct timekeeper shadow_timekeeper;
46
47/**
48 * struct tk_fast - NMI safe timekeeper
49 * @seq: Sequence counter for protecting updates. The lowest bit
50 * is the index for the tk_read_base array
51 * @base: tk_read_base array. Access is indexed by the lowest bit of
52 * @seq.
53 *
54 * See @update_fast_timekeeper() below.
55 */
56struct tk_fast {
57 seqcount_t seq;
58 struct tk_read_base base[2];
59};
60
61static struct tk_fast tk_fast_mono ____cacheline_aligned;
62static struct tk_fast tk_fast_raw ____cacheline_aligned;
63
64/* flag for if timekeeping is suspended */
65int __read_mostly timekeeping_suspended;
66
67static inline void tk_normalize_xtime(struct timekeeper *tk)
68{
69 while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
70 tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
71 tk->xtime_sec++;
72 }
73}
74
75static inline struct timespec64 tk_xtime(struct timekeeper *tk)
76{
77 struct timespec64 ts;
78
79 ts.tv_sec = tk->xtime_sec;
80 ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
81 return ts;
82}
83
84static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
85{
86 tk->xtime_sec = ts->tv_sec;
87 tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
88}
89
90static void tk_xtime_add(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 tk_normalize_xtime(tk);
95}
96
97static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
98{
99 struct timespec64 tmp;
100
101 /*
102 * Verify consistency of: offset_real = -wall_to_monotonic
103 * before modifying anything
104 */
105 set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
106 -tk->wall_to_monotonic.tv_nsec);
107 WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp));
108 tk->wall_to_monotonic = wtm;
109 set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
110 tk->offs_real = timespec64_to_ktime(tmp);
111 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
112}
113
114static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
115{
116 tk->offs_boot = ktime_add(tk->offs_boot, delta);
117}
118
119#ifdef CONFIG_DEBUG_TIMEKEEPING
120#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
121
122static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
123{
124
125 u64 max_cycles = tk->tkr_mono.clock->max_cycles;
126 const char *name = tk->tkr_mono.clock->name;
127
128 if (offset > max_cycles) {
129 printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
130 offset, name, max_cycles);
131 printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
132 } else {
133 if (offset > (max_cycles >> 1)) {
134 printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
135 offset, name, max_cycles >> 1);
136 printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
137 }
138 }
139
140 if (tk->underflow_seen) {
141 if (jiffies - tk->last_warning > WARNING_FREQ) {
142 printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
143 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
144 printk_deferred(" Your kernel is probably still fine.\n");
145 tk->last_warning = jiffies;
146 }
147 tk->underflow_seen = 0;
148 }
149
150 if (tk->overflow_seen) {
151 if (jiffies - tk->last_warning > WARNING_FREQ) {
152 printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
153 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
154 printk_deferred(" Your kernel is probably still fine.\n");
155 tk->last_warning = jiffies;
156 }
157 tk->overflow_seen = 0;
158 }
159}
160
161static inline u64 timekeeping_get_delta(struct tk_read_base *tkr)
162{
163 struct timekeeper *tk = &tk_core.timekeeper;
164 u64 now, last, mask, max, delta;
165 unsigned int seq;
166
167 /*
168 * Since we're called holding a seqlock, the data may shift
169 * under us while we're doing the calculation. This can cause
170 * false positives, since we'd note a problem but throw the
171 * results away. So nest another seqlock here to atomically
172 * grab the points we are checking with.
173 */
174 do {
175 seq = read_seqcount_begin(&tk_core.seq);
176 now = tkr->read(tkr->clock);
177 last = tkr->cycle_last;
178 mask = tkr->mask;
179 max = tkr->clock->max_cycles;
180 } while (read_seqcount_retry(&tk_core.seq, seq));
181
182 delta = clocksource_delta(now, last, mask);
183
184 /*
185 * Try to catch underflows by checking if we are seeing small
186 * mask-relative negative values.
187 */
188 if (unlikely((~delta & mask) < (mask >> 3))) {
189 tk->underflow_seen = 1;
190 delta = 0;
191 }
192
193 /* Cap delta value to the max_cycles values to avoid mult overflows */
194 if (unlikely(delta > max)) {
195 tk->overflow_seen = 1;
196 delta = tkr->clock->max_cycles;
197 }
198
199 return delta;
200}
201#else
202static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
203{
204}
205static inline u64 timekeeping_get_delta(struct tk_read_base *tkr)
206{
207 u64 cycle_now, delta;
208
209 /* read clocksource */
210 cycle_now = tkr->read(tkr->clock);
211
212 /* calculate the delta since the last update_wall_time */
213 delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
214
215 return delta;
216}
217#endif
218
219/**
220 * tk_setup_internals - Set up internals to use clocksource clock.
221 *
222 * @tk: The target timekeeper to setup.
223 * @clock: Pointer to clocksource.
224 *
225 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
226 * pair and interval request.
227 *
228 * Unless you're the timekeeping code, you should not be using this!
229 */
230static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
231{
232 u64 interval;
233 u64 tmp, ntpinterval;
234 struct clocksource *old_clock;
235
236 ++tk->cs_was_changed_seq;
237 old_clock = tk->tkr_mono.clock;
238 tk->tkr_mono.clock = clock;
239 tk->tkr_mono.read = clock->read;
240 tk->tkr_mono.mask = clock->mask;
241 tk->tkr_mono.cycle_last = tk->tkr_mono.read(clock);
242
243 tk->tkr_raw.clock = clock;
244 tk->tkr_raw.read = clock->read;
245 tk->tkr_raw.mask = clock->mask;
246 tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
247
248 /* Do the ns -> cycle conversion first, using original mult */
249 tmp = NTP_INTERVAL_LENGTH;
250 tmp <<= clock->shift;
251 ntpinterval = tmp;
252 tmp += clock->mult/2;
253 do_div(tmp, clock->mult);
254 if (tmp == 0)
255 tmp = 1;
256
257 interval = (u64) tmp;
258 tk->cycle_interval = interval;
259
260 /* Go back from cycles -> shifted ns */
261 tk->xtime_interval = interval * clock->mult;
262 tk->xtime_remainder = ntpinterval - tk->xtime_interval;
263 tk->raw_interval = (interval * clock->mult) >> clock->shift;
264
265 /* if changing clocks, convert xtime_nsec shift units */
266 if (old_clock) {
267 int shift_change = clock->shift - old_clock->shift;
268 if (shift_change < 0)
269 tk->tkr_mono.xtime_nsec >>= -shift_change;
270 else
271 tk->tkr_mono.xtime_nsec <<= shift_change;
272 }
273 tk->tkr_raw.xtime_nsec = 0;
274
275 tk->tkr_mono.shift = clock->shift;
276 tk->tkr_raw.shift = clock->shift;
277
278 tk->ntp_error = 0;
279 tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
280 tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
281
282 /*
283 * The timekeeper keeps its own mult values for the currently
284 * active clocksource. These value will be adjusted via NTP
285 * to counteract clock drifting.
286 */
287 tk->tkr_mono.mult = clock->mult;
288 tk->tkr_raw.mult = clock->mult;
289 tk->ntp_err_mult = 0;
290}
291
292/* Timekeeper helper functions. */
293
294#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
295static u32 default_arch_gettimeoffset(void) { return 0; }
296u32 (*arch_gettimeoffset)(void) = default_arch_gettimeoffset;
297#else
298static inline u32 arch_gettimeoffset(void) { return 0; }
299#endif
300
301static inline u64 timekeeping_delta_to_ns(struct tk_read_base *tkr, u64 delta)
302{
303 u64 nsec;
304
305 nsec = delta * tkr->mult + tkr->xtime_nsec;
306 nsec >>= tkr->shift;
307
308 /* If arch requires, add in get_arch_timeoffset() */
309 return nsec + arch_gettimeoffset();
310}
311
312static inline u64 timekeeping_get_ns(struct tk_read_base *tkr)
313{
314 u64 delta;
315
316 delta = timekeeping_get_delta(tkr);
317 return timekeeping_delta_to_ns(tkr, delta);
318}
319
320static inline u64 timekeeping_cycles_to_ns(struct tk_read_base *tkr, u64 cycles)
321{
322 u64 delta;
323
324 /* calculate the delta since the last update_wall_time */
325 delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
326 return timekeeping_delta_to_ns(tkr, delta);
327}
328
329/**
330 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
331 * @tkr: Timekeeping readout base from which we take the update
332 *
333 * We want to use this from any context including NMI and tracing /
334 * instrumenting the timekeeping code itself.
335 *
336 * Employ the latch technique; see @raw_write_seqcount_latch.
337 *
338 * So if a NMI hits the update of base[0] then it will use base[1]
339 * which is still consistent. In the worst case this can result is a
340 * slightly wrong timestamp (a few nanoseconds). See
341 * @ktime_get_mono_fast_ns.
342 */
343static void update_fast_timekeeper(struct tk_read_base *tkr, struct tk_fast *tkf)
344{
345 struct tk_read_base *base = tkf->base;
346
347 /* Force readers off to base[1] */
348 raw_write_seqcount_latch(&tkf->seq);
349
350 /* Update base[0] */
351 memcpy(base, tkr, sizeof(*base));
352
353 /* Force readers back to base[0] */
354 raw_write_seqcount_latch(&tkf->seq);
355
356 /* Update base[1] */
357 memcpy(base + 1, base, sizeof(*base));
358}
359
360/**
361 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
362 *
363 * This timestamp is not guaranteed to be monotonic across an update.
364 * The timestamp is calculated by:
365 *
366 * now = base_mono + clock_delta * slope
367 *
368 * So if the update lowers the slope, readers who are forced to the
369 * not yet updated second array are still using the old steeper slope.
370 *
371 * tmono
372 * ^
373 * | o n
374 * | o n
375 * | u
376 * | o
377 * |o
378 * |12345678---> reader order
379 *
380 * o = old slope
381 * u = update
382 * n = new slope
383 *
384 * So reader 6 will observe time going backwards versus reader 5.
385 *
386 * While other CPUs are likely to be able observe that, the only way
387 * for a CPU local observation is when an NMI hits in the middle of
388 * the update. Timestamps taken from that NMI context might be ahead
389 * of the following timestamps. Callers need to be aware of that and
390 * deal with it.
391 */
392static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
393{
394 struct tk_read_base *tkr;
395 unsigned int seq;
396 u64 now;
397
398 do {
399 seq = raw_read_seqcount_latch(&tkf->seq);
400 tkr = tkf->base + (seq & 0x01);
401 now = ktime_to_ns(tkr->base);
402
403 now += timekeeping_delta_to_ns(tkr,
404 clocksource_delta(
405 tkr->read(tkr->clock),
406 tkr->cycle_last,
407 tkr->mask));
408 } while (read_seqcount_retry(&tkf->seq, seq));
409
410 return now;
411}
412
413u64 ktime_get_mono_fast_ns(void)
414{
415 return __ktime_get_fast_ns(&tk_fast_mono);
416}
417EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
418
419u64 ktime_get_raw_fast_ns(void)
420{
421 return __ktime_get_fast_ns(&tk_fast_raw);
422}
423EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
424
425/**
426 * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
427 *
428 * To keep it NMI safe since we're accessing from tracing, we're not using a
429 * separate timekeeper with updates to monotonic clock and boot offset
430 * protected with seqlocks. This has the following minor side effects:
431 *
432 * (1) Its possible that a timestamp be taken after the boot offset is updated
433 * but before the timekeeper is updated. If this happens, the new boot offset
434 * is added to the old timekeeping making the clock appear to update slightly
435 * earlier:
436 * CPU 0 CPU 1
437 * timekeeping_inject_sleeptime64()
438 * __timekeeping_inject_sleeptime(tk, delta);
439 * timestamp();
440 * timekeeping_update(tk, TK_CLEAR_NTP...);
441 *
442 * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
443 * partially updated. Since the tk->offs_boot update is a rare event, this
444 * should be a rare occurrence which postprocessing should be able to handle.
445 */
446u64 notrace ktime_get_boot_fast_ns(void)
447{
448 struct timekeeper *tk = &tk_core.timekeeper;
449
450 return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot));
451}
452EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
453
454/* Suspend-time cycles value for halted fast timekeeper. */
455static u64 cycles_at_suspend;
456
457static u64 dummy_clock_read(struct clocksource *cs)
458{
459 return cycles_at_suspend;
460}
461
462/**
463 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
464 * @tk: Timekeeper to snapshot.
465 *
466 * It generally is unsafe to access the clocksource after timekeeping has been
467 * suspended, so take a snapshot of the readout base of @tk and use it as the
468 * fast timekeeper's readout base while suspended. It will return the same
469 * number of cycles every time until timekeeping is resumed at which time the
470 * proper readout base for the fast timekeeper will be restored automatically.
471 */
472static void halt_fast_timekeeper(struct timekeeper *tk)
473{
474 static struct tk_read_base tkr_dummy;
475 struct tk_read_base *tkr = &tk->tkr_mono;
476
477 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
478 cycles_at_suspend = tkr->read(tkr->clock);
479 tkr_dummy.read = dummy_clock_read;
480 update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
481
482 tkr = &tk->tkr_raw;
483 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
484 tkr_dummy.read = dummy_clock_read;
485 update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
486}
487
488#ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
489
490static inline void update_vsyscall(struct timekeeper *tk)
491{
492 struct timespec xt, wm;
493
494 xt = timespec64_to_timespec(tk_xtime(tk));
495 wm = timespec64_to_timespec(tk->wall_to_monotonic);
496 update_vsyscall_old(&xt, &wm, tk->tkr_mono.clock, tk->tkr_mono.mult,
497 tk->tkr_mono.cycle_last);
498}
499
500static inline void old_vsyscall_fixup(struct timekeeper *tk)
501{
502 s64 remainder;
503
504 /*
505 * Store only full nanoseconds into xtime_nsec after rounding
506 * it up and add the remainder to the error difference.
507 * XXX - This is necessary to avoid small 1ns inconsistnecies caused
508 * by truncating the remainder in vsyscalls. However, it causes
509 * additional work to be done in timekeeping_adjust(). Once
510 * the vsyscall implementations are converted to use xtime_nsec
511 * (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
512 * users are removed, this can be killed.
513 */
514 remainder = tk->tkr_mono.xtime_nsec & ((1ULL << tk->tkr_mono.shift) - 1);
515 if (remainder != 0) {
516 tk->tkr_mono.xtime_nsec -= remainder;
517 tk->tkr_mono.xtime_nsec += 1ULL << tk->tkr_mono.shift;
518 tk->ntp_error += remainder << tk->ntp_error_shift;
519 tk->ntp_error -= (1ULL << tk->tkr_mono.shift) << tk->ntp_error_shift;
520 }
521}
522#else
523#define old_vsyscall_fixup(tk)
524#endif
525
526static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
527
528static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
529{
530 raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
531}
532
533/**
534 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
535 */
536int pvclock_gtod_register_notifier(struct notifier_block *nb)
537{
538 struct timekeeper *tk = &tk_core.timekeeper;
539 unsigned long flags;
540 int ret;
541
542 raw_spin_lock_irqsave(&timekeeper_lock, flags);
543 ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
544 update_pvclock_gtod(tk, true);
545 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
546
547 return ret;
548}
549EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
550
551/**
552 * pvclock_gtod_unregister_notifier - unregister a pvclock
553 * timedata update listener
554 */
555int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
556{
557 unsigned long flags;
558 int ret;
559
560 raw_spin_lock_irqsave(&timekeeper_lock, flags);
561 ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
562 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
563
564 return ret;
565}
566EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
567
568/*
569 * tk_update_leap_state - helper to update the next_leap_ktime
570 */
571static inline void tk_update_leap_state(struct timekeeper *tk)
572{
573 tk->next_leap_ktime = ntp_get_next_leap();
574 if (tk->next_leap_ktime != KTIME_MAX)
575 /* Convert to monotonic time */
576 tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
577}
578
579/*
580 * Update the ktime_t based scalar nsec members of the timekeeper
581 */
582static inline void tk_update_ktime_data(struct timekeeper *tk)
583{
584 u64 seconds;
585 u32 nsec;
586
587 /*
588 * The xtime based monotonic readout is:
589 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
590 * The ktime based monotonic readout is:
591 * nsec = base_mono + now();
592 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
593 */
594 seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
595 nsec = (u32) tk->wall_to_monotonic.tv_nsec;
596 tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
597
598 /* Update the monotonic raw base */
599 tk->tkr_raw.base = timespec64_to_ktime(tk->raw_time);
600
601 /*
602 * The sum of the nanoseconds portions of xtime and
603 * wall_to_monotonic can be greater/equal one second. Take
604 * this into account before updating tk->ktime_sec.
605 */
606 nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
607 if (nsec >= NSEC_PER_SEC)
608 seconds++;
609 tk->ktime_sec = seconds;
610}
611
612/* must hold timekeeper_lock */
613static void timekeeping_update(struct timekeeper *tk, unsigned int action)
614{
615 if (action & TK_CLEAR_NTP) {
616 tk->ntp_error = 0;
617 ntp_clear();
618 }
619
620 tk_update_leap_state(tk);
621 tk_update_ktime_data(tk);
622
623 update_vsyscall(tk);
624 update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
625
626 update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
627 update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
628
629 if (action & TK_CLOCK_WAS_SET)
630 tk->clock_was_set_seq++;
631 /*
632 * The mirroring of the data to the shadow-timekeeper needs
633 * to happen last here to ensure we don't over-write the
634 * timekeeper structure on the next update with stale data
635 */
636 if (action & TK_MIRROR)
637 memcpy(&shadow_timekeeper, &tk_core.timekeeper,
638 sizeof(tk_core.timekeeper));
639}
640
641/**
642 * timekeeping_forward_now - update clock to the current time
643 *
644 * Forward the current clock to update its state since the last call to
645 * update_wall_time(). This is useful before significant clock changes,
646 * as it avoids having to deal with this time offset explicitly.
647 */
648static void timekeeping_forward_now(struct timekeeper *tk)
649{
650 struct clocksource *clock = tk->tkr_mono.clock;
651 u64 cycle_now, delta;
652 u64 nsec;
653
654 cycle_now = tk->tkr_mono.read(clock);
655 delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
656 tk->tkr_mono.cycle_last = cycle_now;
657 tk->tkr_raw.cycle_last = cycle_now;
658
659 tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
660
661 /* If arch requires, add in get_arch_timeoffset() */
662 tk->tkr_mono.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_mono.shift;
663
664 tk_normalize_xtime(tk);
665
666 nsec = clocksource_cyc2ns(delta, tk->tkr_raw.mult, tk->tkr_raw.shift);
667 timespec64_add_ns(&tk->raw_time, nsec);
668}
669
670/**
671 * __getnstimeofday64 - Returns the time of day in a timespec64.
672 * @ts: pointer to the timespec to be set
673 *
674 * Updates the time of day in the timespec.
675 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
676 */
677int __getnstimeofday64(struct timespec64 *ts)
678{
679 struct timekeeper *tk = &tk_core.timekeeper;
680 unsigned long seq;
681 u64 nsecs;
682
683 do {
684 seq = read_seqcount_begin(&tk_core.seq);
685
686 ts->tv_sec = tk->xtime_sec;
687 nsecs = timekeeping_get_ns(&tk->tkr_mono);
688
689 } while (read_seqcount_retry(&tk_core.seq, seq));
690
691 ts->tv_nsec = 0;
692 timespec64_add_ns(ts, nsecs);
693
694 /*
695 * Do not bail out early, in case there were callers still using
696 * the value, even in the face of the WARN_ON.
697 */
698 if (unlikely(timekeeping_suspended))
699 return -EAGAIN;
700 return 0;
701}
702EXPORT_SYMBOL(__getnstimeofday64);
703
704/**
705 * getnstimeofday64 - Returns the time of day in a timespec64.
706 * @ts: pointer to the timespec64 to be set
707 *
708 * Returns the time of day in a timespec64 (WARN if suspended).
709 */
710void getnstimeofday64(struct timespec64 *ts)
711{
712 WARN_ON(__getnstimeofday64(ts));
713}
714EXPORT_SYMBOL(getnstimeofday64);
715
716ktime_t ktime_get(void)
717{
718 struct timekeeper *tk = &tk_core.timekeeper;
719 unsigned int seq;
720 ktime_t base;
721 u64 nsecs;
722
723 WARN_ON(timekeeping_suspended);
724
725 do {
726 seq = read_seqcount_begin(&tk_core.seq);
727 base = tk->tkr_mono.base;
728 nsecs = timekeeping_get_ns(&tk->tkr_mono);
729
730 } while (read_seqcount_retry(&tk_core.seq, seq));
731
732 return ktime_add_ns(base, nsecs);
733}
734EXPORT_SYMBOL_GPL(ktime_get);
735
736u32 ktime_get_resolution_ns(void)
737{
738 struct timekeeper *tk = &tk_core.timekeeper;
739 unsigned int seq;
740 u32 nsecs;
741
742 WARN_ON(timekeeping_suspended);
743
744 do {
745 seq = read_seqcount_begin(&tk_core.seq);
746 nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
747 } while (read_seqcount_retry(&tk_core.seq, seq));
748
749 return nsecs;
750}
751EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
752
753static ktime_t *offsets[TK_OFFS_MAX] = {
754 [TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
755 [TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
756 [TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai,
757};
758
759ktime_t ktime_get_with_offset(enum tk_offsets offs)
760{
761 struct timekeeper *tk = &tk_core.timekeeper;
762 unsigned int seq;
763 ktime_t base, *offset = offsets[offs];
764 u64 nsecs;
765
766 WARN_ON(timekeeping_suspended);
767
768 do {
769 seq = read_seqcount_begin(&tk_core.seq);
770 base = ktime_add(tk->tkr_mono.base, *offset);
771 nsecs = timekeeping_get_ns(&tk->tkr_mono);
772
773 } while (read_seqcount_retry(&tk_core.seq, seq));
774
775 return ktime_add_ns(base, nsecs);
776
777}
778EXPORT_SYMBOL_GPL(ktime_get_with_offset);
779
780/**
781 * ktime_mono_to_any() - convert mononotic time to any other time
782 * @tmono: time to convert.
783 * @offs: which offset to use
784 */
785ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
786{
787 ktime_t *offset = offsets[offs];
788 unsigned long seq;
789 ktime_t tconv;
790
791 do {
792 seq = read_seqcount_begin(&tk_core.seq);
793 tconv = ktime_add(tmono, *offset);
794 } while (read_seqcount_retry(&tk_core.seq, seq));
795
796 return tconv;
797}
798EXPORT_SYMBOL_GPL(ktime_mono_to_any);
799
800/**
801 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
802 */
803ktime_t ktime_get_raw(void)
804{
805 struct timekeeper *tk = &tk_core.timekeeper;
806 unsigned int seq;
807 ktime_t base;
808 u64 nsecs;
809
810 do {
811 seq = read_seqcount_begin(&tk_core.seq);
812 base = tk->tkr_raw.base;
813 nsecs = timekeeping_get_ns(&tk->tkr_raw);
814
815 } while (read_seqcount_retry(&tk_core.seq, seq));
816
817 return ktime_add_ns(base, nsecs);
818}
819EXPORT_SYMBOL_GPL(ktime_get_raw);
820
821/**
822 * ktime_get_ts64 - get the monotonic clock in timespec64 format
823 * @ts: pointer to timespec variable
824 *
825 * The function calculates the monotonic clock from the realtime
826 * clock and the wall_to_monotonic offset and stores the result
827 * in normalized timespec64 format in the variable pointed to by @ts.
828 */
829void ktime_get_ts64(struct timespec64 *ts)
830{
831 struct timekeeper *tk = &tk_core.timekeeper;
832 struct timespec64 tomono;
833 unsigned int seq;
834 u64 nsec;
835
836 WARN_ON(timekeeping_suspended);
837
838 do {
839 seq = read_seqcount_begin(&tk_core.seq);
840 ts->tv_sec = tk->xtime_sec;
841 nsec = timekeeping_get_ns(&tk->tkr_mono);
842 tomono = tk->wall_to_monotonic;
843
844 } while (read_seqcount_retry(&tk_core.seq, seq));
845
846 ts->tv_sec += tomono.tv_sec;
847 ts->tv_nsec = 0;
848 timespec64_add_ns(ts, nsec + tomono.tv_nsec);
849}
850EXPORT_SYMBOL_GPL(ktime_get_ts64);
851
852/**
853 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
854 *
855 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
856 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
857 * works on both 32 and 64 bit systems. On 32 bit systems the readout
858 * covers ~136 years of uptime which should be enough to prevent
859 * premature wrap arounds.
860 */
861time64_t ktime_get_seconds(void)
862{
863 struct timekeeper *tk = &tk_core.timekeeper;
864
865 WARN_ON(timekeeping_suspended);
866 return tk->ktime_sec;
867}
868EXPORT_SYMBOL_GPL(ktime_get_seconds);
869
870/**
871 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
872 *
873 * Returns the wall clock seconds since 1970. This replaces the
874 * get_seconds() interface which is not y2038 safe on 32bit systems.
875 *
876 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
877 * 32bit systems the access must be protected with the sequence
878 * counter to provide "atomic" access to the 64bit tk->xtime_sec
879 * value.
880 */
881time64_t ktime_get_real_seconds(void)
882{
883 struct timekeeper *tk = &tk_core.timekeeper;
884 time64_t seconds;
885 unsigned int seq;
886
887 if (IS_ENABLED(CONFIG_64BIT))
888 return tk->xtime_sec;
889
890 do {
891 seq = read_seqcount_begin(&tk_core.seq);
892 seconds = tk->xtime_sec;
893
894 } while (read_seqcount_retry(&tk_core.seq, seq));
895
896 return seconds;
897}
898EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
899
900/**
901 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
902 * but without the sequence counter protect. This internal function
903 * is called just when timekeeping lock is already held.
904 */
905time64_t __ktime_get_real_seconds(void)
906{
907 struct timekeeper *tk = &tk_core.timekeeper;
908
909 return tk->xtime_sec;
910}
911
912/**
913 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
914 * @systime_snapshot: pointer to struct receiving the system time snapshot
915 */
916void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
917{
918 struct timekeeper *tk = &tk_core.timekeeper;
919 unsigned long seq;
920 ktime_t base_raw;
921 ktime_t base_real;
922 u64 nsec_raw;
923 u64 nsec_real;
924 u64 now;
925
926 WARN_ON_ONCE(timekeeping_suspended);
927
928 do {
929 seq = read_seqcount_begin(&tk_core.seq);
930
931 now = tk->tkr_mono.read(tk->tkr_mono.clock);
932 systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
933 systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
934 base_real = ktime_add(tk->tkr_mono.base,
935 tk_core.timekeeper.offs_real);
936 base_raw = tk->tkr_raw.base;
937 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
938 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
939 } while (read_seqcount_retry(&tk_core.seq, seq));
940
941 systime_snapshot->cycles = now;
942 systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
943 systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
944}
945EXPORT_SYMBOL_GPL(ktime_get_snapshot);
946
947/* Scale base by mult/div checking for overflow */
948static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
949{
950 u64 tmp, rem;
951
952 tmp = div64_u64_rem(*base, div, &rem);
953
954 if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
955 ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
956 return -EOVERFLOW;
957 tmp *= mult;
958 rem *= mult;
959
960 do_div(rem, div);
961 *base = tmp + rem;
962 return 0;
963}
964
965/**
966 * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
967 * @history: Snapshot representing start of history
968 * @partial_history_cycles: Cycle offset into history (fractional part)
969 * @total_history_cycles: Total history length in cycles
970 * @discontinuity: True indicates clock was set on history period
971 * @ts: Cross timestamp that should be adjusted using
972 * partial/total ratio
973 *
974 * Helper function used by get_device_system_crosststamp() to correct the
975 * crosstimestamp corresponding to the start of the current interval to the
976 * system counter value (timestamp point) provided by the driver. The
977 * total_history_* quantities are the total history starting at the provided
978 * reference point and ending at the start of the current interval. The cycle
979 * count between the driver timestamp point and the start of the current
980 * interval is partial_history_cycles.
981 */
982static int adjust_historical_crosststamp(struct system_time_snapshot *history,
983 u64 partial_history_cycles,
984 u64 total_history_cycles,
985 bool discontinuity,
986 struct system_device_crosststamp *ts)
987{
988 struct timekeeper *tk = &tk_core.timekeeper;
989 u64 corr_raw, corr_real;
990 bool interp_forward;
991 int ret;
992
993 if (total_history_cycles == 0 || partial_history_cycles == 0)
994 return 0;
995
996 /* Interpolate shortest distance from beginning or end of history */
997 interp_forward = partial_history_cycles > total_history_cycles/2 ?
998 true : false;
999 partial_history_cycles = interp_forward ?
1000 total_history_cycles - partial_history_cycles :
1001 partial_history_cycles;
1002
1003 /*
1004 * Scale the monotonic raw time delta by:
1005 * partial_history_cycles / total_history_cycles
1006 */
1007 corr_raw = (u64)ktime_to_ns(
1008 ktime_sub(ts->sys_monoraw, history->raw));
1009 ret = scale64_check_overflow(partial_history_cycles,
1010 total_history_cycles, &corr_raw);
1011 if (ret)
1012 return ret;
1013
1014 /*
1015 * If there is a discontinuity in the history, scale monotonic raw
1016 * correction by:
1017 * mult(real)/mult(raw) yielding the realtime correction
1018 * Otherwise, calculate the realtime correction similar to monotonic
1019 * raw calculation
1020 */
1021 if (discontinuity) {
1022 corr_real = mul_u64_u32_div
1023 (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1024 } else {
1025 corr_real = (u64)ktime_to_ns(
1026 ktime_sub(ts->sys_realtime, history->real));
1027 ret = scale64_check_overflow(partial_history_cycles,
1028 total_history_cycles, &corr_real);
1029 if (ret)
1030 return ret;
1031 }
1032
1033 /* Fixup monotonic raw and real time time values */
1034 if (interp_forward) {
1035 ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1036 ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1037 } else {
1038 ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1039 ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1040 }
1041
1042 return 0;
1043}
1044
1045/*
1046 * cycle_between - true if test occurs chronologically between before and after
1047 */
1048static bool cycle_between(u64 before, u64 test, u64 after)
1049{
1050 if (test > before && test < after)
1051 return true;
1052 if (test < before && before > after)
1053 return true;
1054 return false;
1055}
1056
1057/**
1058 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1059 * @get_time_fn: Callback to get simultaneous device time and
1060 * system counter from the device driver
1061 * @ctx: Context passed to get_time_fn()
1062 * @history_begin: Historical reference point used to interpolate system
1063 * time when counter provided by the driver is before the current interval
1064 * @xtstamp: Receives simultaneously captured system and device time
1065 *
1066 * Reads a timestamp from a device and correlates it to system time
1067 */
1068int get_device_system_crosststamp(int (*get_time_fn)
1069 (ktime_t *device_time,
1070 struct system_counterval_t *sys_counterval,
1071 void *ctx),
1072 void *ctx,
1073 struct system_time_snapshot *history_begin,
1074 struct system_device_crosststamp *xtstamp)
1075{
1076 struct system_counterval_t system_counterval;
1077 struct timekeeper *tk = &tk_core.timekeeper;
1078 u64 cycles, now, interval_start;
1079 unsigned int clock_was_set_seq = 0;
1080 ktime_t base_real, base_raw;
1081 u64 nsec_real, nsec_raw;
1082 u8 cs_was_changed_seq;
1083 unsigned long seq;
1084 bool do_interp;
1085 int ret;
1086
1087 do {
1088 seq = read_seqcount_begin(&tk_core.seq);
1089 /*
1090 * Try to synchronously capture device time and a system
1091 * counter value calling back into the device driver
1092 */
1093 ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1094 if (ret)
1095 return ret;
1096
1097 /*
1098 * Verify that the clocksource associated with the captured
1099 * system counter value is the same as the currently installed
1100 * timekeeper clocksource
1101 */
1102 if (tk->tkr_mono.clock != system_counterval.cs)
1103 return -ENODEV;
1104 cycles = system_counterval.cycles;
1105
1106 /*
1107 * Check whether the system counter value provided by the
1108 * device driver is on the current timekeeping interval.
1109 */
1110 now = tk->tkr_mono.read(tk->tkr_mono.clock);
1111 interval_start = tk->tkr_mono.cycle_last;
1112 if (!cycle_between(interval_start, cycles, now)) {
1113 clock_was_set_seq = tk->clock_was_set_seq;
1114 cs_was_changed_seq = tk->cs_was_changed_seq;
1115 cycles = interval_start;
1116 do_interp = true;
1117 } else {
1118 do_interp = false;
1119 }
1120
1121 base_real = ktime_add(tk->tkr_mono.base,
1122 tk_core.timekeeper.offs_real);
1123 base_raw = tk->tkr_raw.base;
1124
1125 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1126 system_counterval.cycles);
1127 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1128 system_counterval.cycles);
1129 } while (read_seqcount_retry(&tk_core.seq, seq));
1130
1131 xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1132 xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1133
1134 /*
1135 * Interpolate if necessary, adjusting back from the start of the
1136 * current interval
1137 */
1138 if (do_interp) {
1139 u64 partial_history_cycles, total_history_cycles;
1140 bool discontinuity;
1141
1142 /*
1143 * Check that the counter value occurs after the provided
1144 * history reference and that the history doesn't cross a
1145 * clocksource change
1146 */
1147 if (!history_begin ||
1148 !cycle_between(history_begin->cycles,
1149 system_counterval.cycles, cycles) ||
1150 history_begin->cs_was_changed_seq != cs_was_changed_seq)
1151 return -EINVAL;
1152 partial_history_cycles = cycles - system_counterval.cycles;
1153 total_history_cycles = cycles - history_begin->cycles;
1154 discontinuity =
1155 history_begin->clock_was_set_seq != clock_was_set_seq;
1156
1157 ret = adjust_historical_crosststamp(history_begin,
1158 partial_history_cycles,
1159 total_history_cycles,
1160 discontinuity, xtstamp);
1161 if (ret)
1162 return ret;
1163 }
1164
1165 return 0;
1166}
1167EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1168
1169/**
1170 * do_gettimeofday - Returns the time of day in a timeval
1171 * @tv: pointer to the timeval to be set
1172 *
1173 * NOTE: Users should be converted to using getnstimeofday()
1174 */
1175void do_gettimeofday(struct timeval *tv)
1176{
1177 struct timespec64 now;
1178
1179 getnstimeofday64(&now);
1180 tv->tv_sec = now.tv_sec;
1181 tv->tv_usec = now.tv_nsec/1000;
1182}
1183EXPORT_SYMBOL(do_gettimeofday);
1184
1185/**
1186 * do_settimeofday64 - Sets the time of day.
1187 * @ts: pointer to the timespec64 variable containing the new time
1188 *
1189 * Sets the time of day to the new time and update NTP and notify hrtimers
1190 */
1191int do_settimeofday64(const struct timespec64 *ts)
1192{
1193 struct timekeeper *tk = &tk_core.timekeeper;
1194 struct timespec64 ts_delta, xt;
1195 unsigned long flags;
1196 int ret = 0;
1197
1198 if (!timespec64_valid_strict(ts))
1199 return -EINVAL;
1200
1201 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1202 write_seqcount_begin(&tk_core.seq);
1203
1204 timekeeping_forward_now(tk);
1205
1206 xt = tk_xtime(tk);
1207 ts_delta.tv_sec = ts->tv_sec - xt.tv_sec;
1208 ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec;
1209
1210 if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1211 ret = -EINVAL;
1212 goto out;
1213 }
1214
1215 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1216
1217 tk_set_xtime(tk, ts);
1218out:
1219 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1220
1221 write_seqcount_end(&tk_core.seq);
1222 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1223
1224 /* signal hrtimers about time change */
1225 clock_was_set();
1226
1227 return ret;
1228}
1229EXPORT_SYMBOL(do_settimeofday64);
1230
1231/**
1232 * timekeeping_inject_offset - Adds or subtracts from the current time.
1233 * @tv: pointer to the timespec variable containing the offset
1234 *
1235 * Adds or subtracts an offset value from the current time.
1236 */
1237int timekeeping_inject_offset(struct timespec *ts)
1238{
1239 struct timekeeper *tk = &tk_core.timekeeper;
1240 unsigned long flags;
1241 struct timespec64 ts64, tmp;
1242 int ret = 0;
1243
1244 if (!timespec_inject_offset_valid(ts))
1245 return -EINVAL;
1246
1247 ts64 = timespec_to_timespec64(*ts);
1248
1249 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1250 write_seqcount_begin(&tk_core.seq);
1251
1252 timekeeping_forward_now(tk);
1253
1254 /* Make sure the proposed value is valid */
1255 tmp = timespec64_add(tk_xtime(tk), ts64);
1256 if (timespec64_compare(&tk->wall_to_monotonic, &ts64) > 0 ||
1257 !timespec64_valid_strict(&tmp)) {
1258 ret = -EINVAL;
1259 goto error;
1260 }
1261
1262 tk_xtime_add(tk, &ts64);
1263 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts64));
1264
1265error: /* even if we error out, we forwarded the time, so call update */
1266 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1267
1268 write_seqcount_end(&tk_core.seq);
1269 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1270
1271 /* signal hrtimers about time change */
1272 clock_was_set();
1273
1274 return ret;
1275}
1276EXPORT_SYMBOL(timekeeping_inject_offset);
1277
1278
1279/**
1280 * timekeeping_get_tai_offset - Returns current TAI offset from UTC
1281 *
1282 */
1283s32 timekeeping_get_tai_offset(void)
1284{
1285 struct timekeeper *tk = &tk_core.timekeeper;
1286 unsigned int seq;
1287 s32 ret;
1288
1289 do {
1290 seq = read_seqcount_begin(&tk_core.seq);
1291 ret = tk->tai_offset;
1292 } while (read_seqcount_retry(&tk_core.seq, seq));
1293
1294 return ret;
1295}
1296
1297/**
1298 * __timekeeping_set_tai_offset - Lock free worker function
1299 *
1300 */
1301static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1302{
1303 tk->tai_offset = tai_offset;
1304 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1305}
1306
1307/**
1308 * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
1309 *
1310 */
1311void timekeeping_set_tai_offset(s32 tai_offset)
1312{
1313 struct timekeeper *tk = &tk_core.timekeeper;
1314 unsigned long flags;
1315
1316 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1317 write_seqcount_begin(&tk_core.seq);
1318 __timekeeping_set_tai_offset(tk, tai_offset);
1319 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1320 write_seqcount_end(&tk_core.seq);
1321 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1322 clock_was_set();
1323}
1324
1325/**
1326 * change_clocksource - Swaps clocksources if a new one is available
1327 *
1328 * Accumulates current time interval and initializes new clocksource
1329 */
1330static int change_clocksource(void *data)
1331{
1332 struct timekeeper *tk = &tk_core.timekeeper;
1333 struct clocksource *new, *old;
1334 unsigned long flags;
1335
1336 new = (struct clocksource *) data;
1337
1338 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1339 write_seqcount_begin(&tk_core.seq);
1340
1341 timekeeping_forward_now(tk);
1342 /*
1343 * If the cs is in module, get a module reference. Succeeds
1344 * for built-in code (owner == NULL) as well.
1345 */
1346 if (try_module_get(new->owner)) {
1347 if (!new->enable || new->enable(new) == 0) {
1348 old = tk->tkr_mono.clock;
1349 tk_setup_internals(tk, new);
1350 if (old->disable)
1351 old->disable(old);
1352 module_put(old->owner);
1353 } else {
1354 module_put(new->owner);
1355 }
1356 }
1357 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1358
1359 write_seqcount_end(&tk_core.seq);
1360 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1361
1362 return 0;
1363}
1364
1365/**
1366 * timekeeping_notify - Install a new clock source
1367 * @clock: pointer to the clock source
1368 *
1369 * This function is called from clocksource.c after a new, better clock
1370 * source has been registered. The caller holds the clocksource_mutex.
1371 */
1372int timekeeping_notify(struct clocksource *clock)
1373{
1374 struct timekeeper *tk = &tk_core.timekeeper;
1375
1376 if (tk->tkr_mono.clock == clock)
1377 return 0;
1378 stop_machine(change_clocksource, clock, NULL);
1379 tick_clock_notify();
1380 return tk->tkr_mono.clock == clock ? 0 : -1;
1381}
1382
1383/**
1384 * getrawmonotonic64 - Returns the raw monotonic time in a timespec
1385 * @ts: pointer to the timespec64 to be set
1386 *
1387 * Returns the raw monotonic time (completely un-modified by ntp)
1388 */
1389void getrawmonotonic64(struct timespec64 *ts)
1390{
1391 struct timekeeper *tk = &tk_core.timekeeper;
1392 struct timespec64 ts64;
1393 unsigned long seq;
1394 u64 nsecs;
1395
1396 do {
1397 seq = read_seqcount_begin(&tk_core.seq);
1398 nsecs = timekeeping_get_ns(&tk->tkr_raw);
1399 ts64 = tk->raw_time;
1400
1401 } while (read_seqcount_retry(&tk_core.seq, seq));
1402
1403 timespec64_add_ns(&ts64, nsecs);
1404 *ts = ts64;
1405}
1406EXPORT_SYMBOL(getrawmonotonic64);
1407
1408
1409/**
1410 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1411 */
1412int timekeeping_valid_for_hres(void)
1413{
1414 struct timekeeper *tk = &tk_core.timekeeper;
1415 unsigned long seq;
1416 int ret;
1417
1418 do {
1419 seq = read_seqcount_begin(&tk_core.seq);
1420
1421 ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1422
1423 } while (read_seqcount_retry(&tk_core.seq, seq));
1424
1425 return ret;
1426}
1427
1428/**
1429 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1430 */
1431u64 timekeeping_max_deferment(void)
1432{
1433 struct timekeeper *tk = &tk_core.timekeeper;
1434 unsigned long seq;
1435 u64 ret;
1436
1437 do {
1438 seq = read_seqcount_begin(&tk_core.seq);
1439
1440 ret = tk->tkr_mono.clock->max_idle_ns;
1441
1442 } while (read_seqcount_retry(&tk_core.seq, seq));
1443
1444 return ret;
1445}
1446
1447/**
1448 * read_persistent_clock - Return time from the persistent clock.
1449 *
1450 * Weak dummy function for arches that do not yet support it.
1451 * Reads the time from the battery backed persistent clock.
1452 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1453 *
1454 * XXX - Do be sure to remove it once all arches implement it.
1455 */
1456void __weak read_persistent_clock(struct timespec *ts)
1457{
1458 ts->tv_sec = 0;
1459 ts->tv_nsec = 0;
1460}
1461
1462void __weak read_persistent_clock64(struct timespec64 *ts64)
1463{
1464 struct timespec ts;
1465
1466 read_persistent_clock(&ts);
1467 *ts64 = timespec_to_timespec64(ts);
1468}
1469
1470/**
1471 * read_boot_clock64 - Return time of the system start.
1472 *
1473 * Weak dummy function for arches that do not yet support it.
1474 * Function to read the exact time the system has been started.
1475 * Returns a timespec64 with tv_sec=0 and tv_nsec=0 if unsupported.
1476 *
1477 * XXX - Do be sure to remove it once all arches implement it.
1478 */
1479void __weak read_boot_clock64(struct timespec64 *ts)
1480{
1481 ts->tv_sec = 0;
1482 ts->tv_nsec = 0;
1483}
1484
1485/* Flag for if timekeeping_resume() has injected sleeptime */
1486static bool sleeptime_injected;
1487
1488/* Flag for if there is a persistent clock on this platform */
1489static bool persistent_clock_exists;
1490
1491/*
1492 * timekeeping_init - Initializes the clocksource and common timekeeping values
1493 */
1494void __init timekeeping_init(void)
1495{
1496 struct timekeeper *tk = &tk_core.timekeeper;
1497 struct clocksource *clock;
1498 unsigned long flags;
1499 struct timespec64 now, boot, tmp;
1500
1501 read_persistent_clock64(&now);
1502 if (!timespec64_valid_strict(&now)) {
1503 pr_warn("WARNING: Persistent clock returned invalid value!\n"
1504 " Check your CMOS/BIOS settings.\n");
1505 now.tv_sec = 0;
1506 now.tv_nsec = 0;
1507 } else if (now.tv_sec || now.tv_nsec)
1508 persistent_clock_exists = true;
1509
1510 read_boot_clock64(&boot);
1511 if (!timespec64_valid_strict(&boot)) {
1512 pr_warn("WARNING: Boot clock returned invalid value!\n"
1513 " Check your CMOS/BIOS settings.\n");
1514 boot.tv_sec = 0;
1515 boot.tv_nsec = 0;
1516 }
1517
1518 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1519 write_seqcount_begin(&tk_core.seq);
1520 ntp_init();
1521
1522 clock = clocksource_default_clock();
1523 if (clock->enable)
1524 clock->enable(clock);
1525 tk_setup_internals(tk, clock);
1526
1527 tk_set_xtime(tk, &now);
1528 tk->raw_time.tv_sec = 0;
1529 tk->raw_time.tv_nsec = 0;
1530 if (boot.tv_sec == 0 && boot.tv_nsec == 0)
1531 boot = tk_xtime(tk);
1532
1533 set_normalized_timespec64(&tmp, -boot.tv_sec, -boot.tv_nsec);
1534 tk_set_wall_to_mono(tk, tmp);
1535
1536 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1537
1538 write_seqcount_end(&tk_core.seq);
1539 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1540}
1541
1542/* time in seconds when suspend began for persistent clock */
1543static struct timespec64 timekeeping_suspend_time;
1544
1545/**
1546 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1547 * @delta: pointer to a timespec delta value
1548 *
1549 * Takes a timespec offset measuring a suspend interval and properly
1550 * adds the sleep offset to the timekeeping variables.
1551 */
1552static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1553 struct timespec64 *delta)
1554{
1555 if (!timespec64_valid_strict(delta)) {
1556 printk_deferred(KERN_WARNING
1557 "__timekeeping_inject_sleeptime: Invalid "
1558 "sleep delta value!\n");
1559 return;
1560 }
1561 tk_xtime_add(tk, delta);
1562 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1563 tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1564 tk_debug_account_sleep_time(delta);
1565}
1566
1567#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1568/**
1569 * We have three kinds of time sources to use for sleep time
1570 * injection, the preference order is:
1571 * 1) non-stop clocksource
1572 * 2) persistent clock (ie: RTC accessible when irqs are off)
1573 * 3) RTC
1574 *
1575 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1576 * If system has neither 1) nor 2), 3) will be used finally.
1577 *
1578 *
1579 * If timekeeping has injected sleeptime via either 1) or 2),
1580 * 3) becomes needless, so in this case we don't need to call
1581 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1582 * means.
1583 */
1584bool timekeeping_rtc_skipresume(void)
1585{
1586 return sleeptime_injected;
1587}
1588
1589/**
1590 * 1) can be determined whether to use or not only when doing
1591 * timekeeping_resume() which is invoked after rtc_suspend(),
1592 * so we can't skip rtc_suspend() surely if system has 1).
1593 *
1594 * But if system has 2), 2) will definitely be used, so in this
1595 * case we don't need to call rtc_suspend(), and this is what
1596 * timekeeping_rtc_skipsuspend() means.
1597 */
1598bool timekeeping_rtc_skipsuspend(void)
1599{
1600 return persistent_clock_exists;
1601}
1602
1603/**
1604 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1605 * @delta: pointer to a timespec64 delta value
1606 *
1607 * This hook is for architectures that cannot support read_persistent_clock64
1608 * because their RTC/persistent clock is only accessible when irqs are enabled.
1609 * and also don't have an effective nonstop clocksource.
1610 *
1611 * This function should only be called by rtc_resume(), and allows
1612 * a suspend offset to be injected into the timekeeping values.
1613 */
1614void timekeeping_inject_sleeptime64(struct timespec64 *delta)
1615{
1616 struct timekeeper *tk = &tk_core.timekeeper;
1617 unsigned long flags;
1618
1619 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1620 write_seqcount_begin(&tk_core.seq);
1621
1622 timekeeping_forward_now(tk);
1623
1624 __timekeeping_inject_sleeptime(tk, delta);
1625
1626 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1627
1628 write_seqcount_end(&tk_core.seq);
1629 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1630
1631 /* signal hrtimers about time change */
1632 clock_was_set();
1633}
1634#endif
1635
1636/**
1637 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1638 */
1639void timekeeping_resume(void)
1640{
1641 struct timekeeper *tk = &tk_core.timekeeper;
1642 struct clocksource *clock = tk->tkr_mono.clock;
1643 unsigned long flags;
1644 struct timespec64 ts_new, ts_delta;
1645 u64 cycle_now;
1646
1647 sleeptime_injected = false;
1648 read_persistent_clock64(&ts_new);
1649
1650 clockevents_resume();
1651 clocksource_resume();
1652
1653 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1654 write_seqcount_begin(&tk_core.seq);
1655
1656 /*
1657 * After system resumes, we need to calculate the suspended time and
1658 * compensate it for the OS time. There are 3 sources that could be
1659 * used: Nonstop clocksource during suspend, persistent clock and rtc
1660 * device.
1661 *
1662 * One specific platform may have 1 or 2 or all of them, and the
1663 * preference will be:
1664 * suspend-nonstop clocksource -> persistent clock -> rtc
1665 * The less preferred source will only be tried if there is no better
1666 * usable source. The rtc part is handled separately in rtc core code.
1667 */
1668 cycle_now = tk->tkr_mono.read(clock);
1669 if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) &&
1670 cycle_now > tk->tkr_mono.cycle_last) {
1671 u64 nsec, cyc_delta;
1672
1673 cyc_delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last,
1674 tk->tkr_mono.mask);
1675 nsec = mul_u64_u32_shr(cyc_delta, clock->mult, clock->shift);
1676 ts_delta = ns_to_timespec64(nsec);
1677 sleeptime_injected = true;
1678 } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1679 ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1680 sleeptime_injected = true;
1681 }
1682
1683 if (sleeptime_injected)
1684 __timekeeping_inject_sleeptime(tk, &ts_delta);
1685
1686 /* Re-base the last cycle value */
1687 tk->tkr_mono.cycle_last = cycle_now;
1688 tk->tkr_raw.cycle_last = cycle_now;
1689
1690 tk->ntp_error = 0;
1691 timekeeping_suspended = 0;
1692 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1693 write_seqcount_end(&tk_core.seq);
1694 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1695
1696 touch_softlockup_watchdog();
1697
1698 tick_resume();
1699 hrtimers_resume();
1700}
1701
1702int timekeeping_suspend(void)
1703{
1704 struct timekeeper *tk = &tk_core.timekeeper;
1705 unsigned long flags;
1706 struct timespec64 delta, delta_delta;
1707 static struct timespec64 old_delta;
1708
1709 read_persistent_clock64(&timekeeping_suspend_time);
1710
1711 /*
1712 * On some systems the persistent_clock can not be detected at
1713 * timekeeping_init by its return value, so if we see a valid
1714 * value returned, update the persistent_clock_exists flag.
1715 */
1716 if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1717 persistent_clock_exists = true;
1718
1719 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1720 write_seqcount_begin(&tk_core.seq);
1721 timekeeping_forward_now(tk);
1722 timekeeping_suspended = 1;
1723
1724 if (persistent_clock_exists) {
1725 /*
1726 * To avoid drift caused by repeated suspend/resumes,
1727 * which each can add ~1 second drift error,
1728 * try to compensate so the difference in system time
1729 * and persistent_clock time stays close to constant.
1730 */
1731 delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1732 delta_delta = timespec64_sub(delta, old_delta);
1733 if (abs(delta_delta.tv_sec) >= 2) {
1734 /*
1735 * if delta_delta is too large, assume time correction
1736 * has occurred and set old_delta to the current delta.
1737 */
1738 old_delta = delta;
1739 } else {
1740 /* Otherwise try to adjust old_system to compensate */
1741 timekeeping_suspend_time =
1742 timespec64_add(timekeeping_suspend_time, delta_delta);
1743 }
1744 }
1745
1746 timekeeping_update(tk, TK_MIRROR);
1747 halt_fast_timekeeper(tk);
1748 write_seqcount_end(&tk_core.seq);
1749 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1750
1751 tick_suspend();
1752 clocksource_suspend();
1753 clockevents_suspend();
1754
1755 return 0;
1756}
1757
1758/* sysfs resume/suspend bits for timekeeping */
1759static struct syscore_ops timekeeping_syscore_ops = {
1760 .resume = timekeeping_resume,
1761 .suspend = timekeeping_suspend,
1762};
1763
1764static int __init timekeeping_init_ops(void)
1765{
1766 register_syscore_ops(&timekeeping_syscore_ops);
1767 return 0;
1768}
1769device_initcall(timekeeping_init_ops);
1770
1771/*
1772 * Apply a multiplier adjustment to the timekeeper
1773 */
1774static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1775 s64 offset,
1776 bool negative,
1777 int adj_scale)
1778{
1779 s64 interval = tk->cycle_interval;
1780 s32 mult_adj = 1;
1781
1782 if (negative) {
1783 mult_adj = -mult_adj;
1784 interval = -interval;
1785 offset = -offset;
1786 }
1787 mult_adj <<= adj_scale;
1788 interval <<= adj_scale;
1789 offset <<= adj_scale;
1790
1791 /*
1792 * So the following can be confusing.
1793 *
1794 * To keep things simple, lets assume mult_adj == 1 for now.
1795 *
1796 * When mult_adj != 1, remember that the interval and offset values
1797 * have been appropriately scaled so the math is the same.
1798 *
1799 * The basic idea here is that we're increasing the multiplier
1800 * by one, this causes the xtime_interval to be incremented by
1801 * one cycle_interval. This is because:
1802 * xtime_interval = cycle_interval * mult
1803 * So if mult is being incremented by one:
1804 * xtime_interval = cycle_interval * (mult + 1)
1805 * Its the same as:
1806 * xtime_interval = (cycle_interval * mult) + cycle_interval
1807 * Which can be shortened to:
1808 * xtime_interval += cycle_interval
1809 *
1810 * So offset stores the non-accumulated cycles. Thus the current
1811 * time (in shifted nanoseconds) is:
1812 * now = (offset * adj) + xtime_nsec
1813 * Now, even though we're adjusting the clock frequency, we have
1814 * to keep time consistent. In other words, we can't jump back
1815 * in time, and we also want to avoid jumping forward in time.
1816 *
1817 * So given the same offset value, we need the time to be the same
1818 * both before and after the freq adjustment.
1819 * now = (offset * adj_1) + xtime_nsec_1
1820 * now = (offset * adj_2) + xtime_nsec_2
1821 * So:
1822 * (offset * adj_1) + xtime_nsec_1 =
1823 * (offset * adj_2) + xtime_nsec_2
1824 * And we know:
1825 * adj_2 = adj_1 + 1
1826 * So:
1827 * (offset * adj_1) + xtime_nsec_1 =
1828 * (offset * (adj_1+1)) + xtime_nsec_2
1829 * (offset * adj_1) + xtime_nsec_1 =
1830 * (offset * adj_1) + offset + xtime_nsec_2
1831 * Canceling the sides:
1832 * xtime_nsec_1 = offset + xtime_nsec_2
1833 * Which gives us:
1834 * xtime_nsec_2 = xtime_nsec_1 - offset
1835 * Which simplfies to:
1836 * xtime_nsec -= offset
1837 *
1838 * XXX - TODO: Doc ntp_error calculation.
1839 */
1840 if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1841 /* NTP adjustment caused clocksource mult overflow */
1842 WARN_ON_ONCE(1);
1843 return;
1844 }
1845
1846 tk->tkr_mono.mult += mult_adj;
1847 tk->xtime_interval += interval;
1848 tk->tkr_mono.xtime_nsec -= offset;
1849 tk->ntp_error -= (interval - offset) << tk->ntp_error_shift;
1850}
1851
1852/*
1853 * Calculate the multiplier adjustment needed to match the frequency
1854 * specified by NTP
1855 */
1856static __always_inline void timekeeping_freqadjust(struct timekeeper *tk,
1857 s64 offset)
1858{
1859 s64 interval = tk->cycle_interval;
1860 s64 xinterval = tk->xtime_interval;
1861 u32 base = tk->tkr_mono.clock->mult;
1862 u32 max = tk->tkr_mono.clock->maxadj;
1863 u32 cur_adj = tk->tkr_mono.mult;
1864 s64 tick_error;
1865 bool negative;
1866 u32 adj_scale;
1867
1868 /* Remove any current error adj from freq calculation */
1869 if (tk->ntp_err_mult)
1870 xinterval -= tk->cycle_interval;
1871
1872 tk->ntp_tick = ntp_tick_length();
1873
1874 /* Calculate current error per tick */
1875 tick_error = ntp_tick_length() >> tk->ntp_error_shift;
1876 tick_error -= (xinterval + tk->xtime_remainder);
1877
1878 /* Don't worry about correcting it if its small */
1879 if (likely((tick_error >= 0) && (tick_error <= interval)))
1880 return;
1881
1882 /* preserve the direction of correction */
1883 negative = (tick_error < 0);
1884
1885 /* If any adjustment would pass the max, just return */
1886 if (negative && (cur_adj - 1) <= (base - max))
1887 return;
1888 if (!negative && (cur_adj + 1) >= (base + max))
1889 return;
1890 /*
1891 * Sort out the magnitude of the correction, but
1892 * avoid making so large a correction that we go
1893 * over the max adjustment.
1894 */
1895 adj_scale = 0;
1896 tick_error = abs(tick_error);
1897 while (tick_error > interval) {
1898 u32 adj = 1 << (adj_scale + 1);
1899
1900 /* Check if adjustment gets us within 1 unit from the max */
1901 if (negative && (cur_adj - adj) <= (base - max))
1902 break;
1903 if (!negative && (cur_adj + adj) >= (base + max))
1904 break;
1905
1906 adj_scale++;
1907 tick_error >>= 1;
1908 }
1909
1910 /* scale the corrections */
1911 timekeeping_apply_adjustment(tk, offset, negative, adj_scale);
1912}
1913
1914/*
1915 * Adjust the timekeeper's multiplier to the correct frequency
1916 * and also to reduce the accumulated error value.
1917 */
1918static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1919{
1920 /* Correct for the current frequency error */
1921 timekeeping_freqadjust(tk, offset);
1922
1923 /* Next make a small adjustment to fix any cumulative error */
1924 if (!tk->ntp_err_mult && (tk->ntp_error > 0)) {
1925 tk->ntp_err_mult = 1;
1926 timekeeping_apply_adjustment(tk, offset, 0, 0);
1927 } else if (tk->ntp_err_mult && (tk->ntp_error <= 0)) {
1928 /* Undo any existing error adjustment */
1929 timekeeping_apply_adjustment(tk, offset, 1, 0);
1930 tk->ntp_err_mult = 0;
1931 }
1932
1933 if (unlikely(tk->tkr_mono.clock->maxadj &&
1934 (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
1935 > tk->tkr_mono.clock->maxadj))) {
1936 printk_once(KERN_WARNING
1937 "Adjusting %s more than 11%% (%ld vs %ld)\n",
1938 tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
1939 (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
1940 }
1941
1942 /*
1943 * It may be possible that when we entered this function, xtime_nsec
1944 * was very small. Further, if we're slightly speeding the clocksource
1945 * in the code above, its possible the required corrective factor to
1946 * xtime_nsec could cause it to underflow.
1947 *
1948 * Now, since we already accumulated the second, cannot simply roll
1949 * the accumulated second back, since the NTP subsystem has been
1950 * notified via second_overflow. So instead we push xtime_nsec forward
1951 * by the amount we underflowed, and add that amount into the error.
1952 *
1953 * We'll correct this error next time through this function, when
1954 * xtime_nsec is not as small.
1955 */
1956 if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
1957 s64 neg = -(s64)tk->tkr_mono.xtime_nsec;
1958 tk->tkr_mono.xtime_nsec = 0;
1959 tk->ntp_error += neg << tk->ntp_error_shift;
1960 }
1961}
1962
1963/**
1964 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1965 *
1966 * Helper function that accumulates the nsecs greater than a second
1967 * from the xtime_nsec field to the xtime_secs field.
1968 * It also calls into the NTP code to handle leapsecond processing.
1969 *
1970 */
1971static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
1972{
1973 u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
1974 unsigned int clock_set = 0;
1975
1976 while (tk->tkr_mono.xtime_nsec >= nsecps) {
1977 int leap;
1978
1979 tk->tkr_mono.xtime_nsec -= nsecps;
1980 tk->xtime_sec++;
1981
1982 /* Figure out if its a leap sec and apply if needed */
1983 leap = second_overflow(tk->xtime_sec);
1984 if (unlikely(leap)) {
1985 struct timespec64 ts;
1986
1987 tk->xtime_sec += leap;
1988
1989 ts.tv_sec = leap;
1990 ts.tv_nsec = 0;
1991 tk_set_wall_to_mono(tk,
1992 timespec64_sub(tk->wall_to_monotonic, ts));
1993
1994 __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
1995
1996 clock_set = TK_CLOCK_WAS_SET;
1997 }
1998 }
1999 return clock_set;
2000}
2001
2002/**
2003 * logarithmic_accumulation - shifted accumulation of cycles
2004 *
2005 * This functions accumulates a shifted interval of cycles into
2006 * into a shifted interval nanoseconds. Allows for O(log) accumulation
2007 * loop.
2008 *
2009 * Returns the unconsumed cycles.
2010 */
2011static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2012 u32 shift, unsigned int *clock_set)
2013{
2014 u64 interval = tk->cycle_interval << shift;
2015 u64 raw_nsecs;
2016
2017 /* If the offset is smaller than a shifted interval, do nothing */
2018 if (offset < interval)
2019 return offset;
2020
2021 /* Accumulate one shifted interval */
2022 offset -= interval;
2023 tk->tkr_mono.cycle_last += interval;
2024 tk->tkr_raw.cycle_last += interval;
2025
2026 tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2027 *clock_set |= accumulate_nsecs_to_secs(tk);
2028
2029 /* Accumulate raw time */
2030 raw_nsecs = (u64)tk->raw_interval << shift;
2031 raw_nsecs += tk->raw_time.tv_nsec;
2032 if (raw_nsecs >= NSEC_PER_SEC) {
2033 u64 raw_secs = raw_nsecs;
2034 raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
2035 tk->raw_time.tv_sec += raw_secs;
2036 }
2037 tk->raw_time.tv_nsec = raw_nsecs;
2038
2039 /* Accumulate error between NTP and clock interval */
2040 tk->ntp_error += tk->ntp_tick << shift;
2041 tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2042 (tk->ntp_error_shift + shift);
2043
2044 return offset;
2045}
2046
2047/**
2048 * update_wall_time - Uses the current clocksource to increment the wall time
2049 *
2050 */
2051void update_wall_time(void)
2052{
2053 struct timekeeper *real_tk = &tk_core.timekeeper;
2054 struct timekeeper *tk = &shadow_timekeeper;
2055 u64 offset;
2056 int shift = 0, maxshift;
2057 unsigned int clock_set = 0;
2058 unsigned long flags;
2059
2060 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2061
2062 /* Make sure we're fully resumed: */
2063 if (unlikely(timekeeping_suspended))
2064 goto out;
2065
2066#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
2067 offset = real_tk->cycle_interval;
2068#else
2069 offset = clocksource_delta(tk->tkr_mono.read(tk->tkr_mono.clock),
2070 tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2071#endif
2072
2073 /* Check if there's really nothing to do */
2074 if (offset < real_tk->cycle_interval)
2075 goto out;
2076
2077 /* Do some additional sanity checking */
2078 timekeeping_check_update(real_tk, offset);
2079
2080 /*
2081 * With NO_HZ we may have to accumulate many cycle_intervals
2082 * (think "ticks") worth of time at once. To do this efficiently,
2083 * we calculate the largest doubling multiple of cycle_intervals
2084 * that is smaller than the offset. We then accumulate that
2085 * chunk in one go, and then try to consume the next smaller
2086 * doubled multiple.
2087 */
2088 shift = ilog2(offset) - ilog2(tk->cycle_interval);
2089 shift = max(0, shift);
2090 /* Bound shift to one less than what overflows tick_length */
2091 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2092 shift = min(shift, maxshift);
2093 while (offset >= tk->cycle_interval) {
2094 offset = logarithmic_accumulation(tk, offset, shift,
2095 &clock_set);
2096 if (offset < tk->cycle_interval<<shift)
2097 shift--;
2098 }
2099
2100 /* correct the clock when NTP error is too big */
2101 timekeeping_adjust(tk, offset);
2102
2103 /*
2104 * XXX This can be killed once everyone converts
2105 * to the new update_vsyscall.
2106 */
2107 old_vsyscall_fixup(tk);
2108
2109 /*
2110 * Finally, make sure that after the rounding
2111 * xtime_nsec isn't larger than NSEC_PER_SEC
2112 */
2113 clock_set |= accumulate_nsecs_to_secs(tk);
2114
2115 write_seqcount_begin(&tk_core.seq);
2116 /*
2117 * Update the real timekeeper.
2118 *
2119 * We could avoid this memcpy by switching pointers, but that
2120 * requires changes to all other timekeeper usage sites as
2121 * well, i.e. move the timekeeper pointer getter into the
2122 * spinlocked/seqcount protected sections. And we trade this
2123 * memcpy under the tk_core.seq against one before we start
2124 * updating.
2125 */
2126 timekeeping_update(tk, clock_set);
2127 memcpy(real_tk, tk, sizeof(*tk));
2128 /* The memcpy must come last. Do not put anything here! */
2129 write_seqcount_end(&tk_core.seq);
2130out:
2131 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2132 if (clock_set)
2133 /* Have to call _delayed version, since in irq context*/
2134 clock_was_set_delayed();
2135}
2136
2137/**
2138 * getboottime64 - Return the real time of system boot.
2139 * @ts: pointer to the timespec64 to be set
2140 *
2141 * Returns the wall-time of boot in a timespec64.
2142 *
2143 * This is based on the wall_to_monotonic offset and the total suspend
2144 * time. Calls to settimeofday will affect the value returned (which
2145 * basically means that however wrong your real time clock is at boot time,
2146 * you get the right time here).
2147 */
2148void getboottime64(struct timespec64 *ts)
2149{
2150 struct timekeeper *tk = &tk_core.timekeeper;
2151 ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2152
2153 *ts = ktime_to_timespec64(t);
2154}
2155EXPORT_SYMBOL_GPL(getboottime64);
2156
2157unsigned long get_seconds(void)
2158{
2159 struct timekeeper *tk = &tk_core.timekeeper;
2160
2161 return tk->xtime_sec;
2162}
2163EXPORT_SYMBOL(get_seconds);
2164
2165struct timespec __current_kernel_time(void)
2166{
2167 struct timekeeper *tk = &tk_core.timekeeper;
2168
2169 return timespec64_to_timespec(tk_xtime(tk));
2170}
2171
2172struct timespec64 current_kernel_time64(void)
2173{
2174 struct timekeeper *tk = &tk_core.timekeeper;
2175 struct timespec64 now;
2176 unsigned long seq;
2177
2178 do {
2179 seq = read_seqcount_begin(&tk_core.seq);
2180
2181 now = tk_xtime(tk);
2182 } while (read_seqcount_retry(&tk_core.seq, seq));
2183
2184 return now;
2185}
2186EXPORT_SYMBOL(current_kernel_time64);
2187
2188struct timespec64 get_monotonic_coarse64(void)
2189{
2190 struct timekeeper *tk = &tk_core.timekeeper;
2191 struct timespec64 now, mono;
2192 unsigned long seq;
2193
2194 do {
2195 seq = read_seqcount_begin(&tk_core.seq);
2196
2197 now = tk_xtime(tk);
2198 mono = tk->wall_to_monotonic;
2199 } while (read_seqcount_retry(&tk_core.seq, seq));
2200
2201 set_normalized_timespec64(&now, now.tv_sec + mono.tv_sec,
2202 now.tv_nsec + mono.tv_nsec);
2203
2204 return now;
2205}
2206EXPORT_SYMBOL(get_monotonic_coarse64);
2207
2208/*
2209 * Must hold jiffies_lock
2210 */
2211void do_timer(unsigned long ticks)
2212{
2213 jiffies_64 += ticks;
2214 calc_global_load(ticks);
2215}
2216
2217/**
2218 * ktime_get_update_offsets_now - hrtimer helper
2219 * @cwsseq: pointer to check and store the clock was set sequence number
2220 * @offs_real: pointer to storage for monotonic -> realtime offset
2221 * @offs_boot: pointer to storage for monotonic -> boottime offset
2222 * @offs_tai: pointer to storage for monotonic -> clock tai offset
2223 *
2224 * Returns current monotonic time and updates the offsets if the
2225 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2226 * different.
2227 *
2228 * Called from hrtimer_interrupt() or retrigger_next_event()
2229 */
2230ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2231 ktime_t *offs_boot, ktime_t *offs_tai)
2232{
2233 struct timekeeper *tk = &tk_core.timekeeper;
2234 unsigned int seq;
2235 ktime_t base;
2236 u64 nsecs;
2237
2238 do {
2239 seq = read_seqcount_begin(&tk_core.seq);
2240
2241 base = tk->tkr_mono.base;
2242 nsecs = timekeeping_get_ns(&tk->tkr_mono);
2243 base = ktime_add_ns(base, nsecs);
2244
2245 if (*cwsseq != tk->clock_was_set_seq) {
2246 *cwsseq = tk->clock_was_set_seq;
2247 *offs_real = tk->offs_real;
2248 *offs_boot = tk->offs_boot;
2249 *offs_tai = tk->offs_tai;
2250 }
2251
2252 /* Handle leapsecond insertion adjustments */
2253 if (unlikely(base >= tk->next_leap_ktime))
2254 *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2255
2256 } while (read_seqcount_retry(&tk_core.seq, seq));
2257
2258 return base;
2259}
2260
2261/**
2262 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2263 */
2264int do_adjtimex(struct timex *txc)
2265{
2266 struct timekeeper *tk = &tk_core.timekeeper;
2267 unsigned long flags;
2268 struct timespec64 ts;
2269 s32 orig_tai, tai;
2270 int ret;
2271
2272 /* Validate the data before disabling interrupts */
2273 ret = ntp_validate_timex(txc);
2274 if (ret)
2275 return ret;
2276
2277 if (txc->modes & ADJ_SETOFFSET) {
2278 struct timespec delta;
2279 delta.tv_sec = txc->time.tv_sec;
2280 delta.tv_nsec = txc->time.tv_usec;
2281 if (!(txc->modes & ADJ_NANO))
2282 delta.tv_nsec *= 1000;
2283 ret = timekeeping_inject_offset(&delta);
2284 if (ret)
2285 return ret;
2286 }
2287
2288 getnstimeofday64(&ts);
2289
2290 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2291 write_seqcount_begin(&tk_core.seq);
2292
2293 orig_tai = tai = tk->tai_offset;
2294 ret = __do_adjtimex(txc, &ts, &tai);
2295
2296 if (tai != orig_tai) {
2297 __timekeeping_set_tai_offset(tk, tai);
2298 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2299 }
2300 tk_update_leap_state(tk);
2301
2302 write_seqcount_end(&tk_core.seq);
2303 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2304
2305 if (tai != orig_tai)
2306 clock_was_set();
2307
2308 ntp_notify_cmos_timer();
2309
2310 return ret;
2311}
2312
2313#ifdef CONFIG_NTP_PPS
2314/**
2315 * hardpps() - Accessor function to NTP __hardpps function
2316 */
2317void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2318{
2319 unsigned long flags;
2320
2321 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2322 write_seqcount_begin(&tk_core.seq);
2323
2324 __hardpps(phase_ts, raw_ts);
2325
2326 write_seqcount_end(&tk_core.seq);
2327 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2328}
2329EXPORT_SYMBOL(hardpps);
2330#endif
2331
2332/**
2333 * xtime_update() - advances the timekeeping infrastructure
2334 * @ticks: number of ticks, that have elapsed since the last call.
2335 *
2336 * Must be called with interrupts disabled.
2337 */
2338void xtime_update(unsigned long ticks)
2339{
2340 write_seqlock(&jiffies_lock);
2341 do_timer(ticks);
2342 write_sequnlock(&jiffies_lock);
2343 update_wall_time();
2344}