1 // SPDX-License-Identifier: GPL-2.0
3 * Kernel timekeeping code and accessor functions. Based on code from
4 * timer.c, moved in commit 8524070b7982.
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>
12 #include <linux/nmi.h>
13 #include <linux/sched.h>
14 #include <linux/sched/loadavg.h>
15 #include <linux/sched/clock.h>
16 #include <linux/syscore_ops.h>
17 #include <linux/clocksource.h>
18 #include <linux/jiffies.h>
19 #include <linux/time.h>
20 #include <linux/tick.h>
21 #include <linux/stop_machine.h>
22 #include <linux/pvclock_gtod.h>
23 #include <linux/compiler.h>
24 #include <linux/audit.h>
26 #include "tick-internal.h"
27 #include "ntp_internal.h"
28 #include "timekeeping_internal.h"
30 #define TK_CLEAR_NTP (1 << 0)
31 #define TK_MIRROR (1 << 1)
32 #define TK_CLOCK_WAS_SET (1 << 2)
34 enum timekeeping_adv_mode {
35 /* Update timekeeper when a tick has passed */
38 /* Update timekeeper on a direct frequency change */
42 DEFINE_RAW_SPINLOCK(timekeeper_lock);
45 * The most important data for readout fits into a single 64 byte
49 seqcount_raw_spinlock_t seq;
50 struct timekeeper timekeeper;
51 } tk_core ____cacheline_aligned = {
52 .seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_core.seq, &timekeeper_lock),
55 static struct timekeeper shadow_timekeeper;
57 /* flag for if timekeeping is suspended */
58 int __read_mostly timekeeping_suspended;
61 * struct tk_fast - NMI safe timekeeper
62 * @seq: Sequence counter for protecting updates. The lowest bit
63 * is the index for the tk_read_base array
64 * @base: tk_read_base array. Access is indexed by the lowest bit of
67 * See @update_fast_timekeeper() below.
71 struct tk_read_base base[2];
74 /* Suspend-time cycles value for halted fast timekeeper. */
75 static u64 cycles_at_suspend;
77 static u64 dummy_clock_read(struct clocksource *cs)
79 if (timekeeping_suspended)
80 return cycles_at_suspend;
84 static struct clocksource dummy_clock = {
85 .read = dummy_clock_read,
89 * Boot time initialization which allows local_clock() to be utilized
90 * during early boot when clocksources are not available. local_clock()
91 * returns nanoseconds already so no conversion is required, hence mult=1
92 * and shift=0. When the first proper clocksource is installed then
93 * the fast time keepers are updated with the correct values.
95 #define FAST_TK_INIT \
97 .clock = &dummy_clock, \
98 .mask = CLOCKSOURCE_MASK(64), \
103 static struct tk_fast tk_fast_mono ____cacheline_aligned = {
104 .seq = SEQCNT_LATCH_ZERO(tk_fast_mono.seq),
105 .base[0] = FAST_TK_INIT,
106 .base[1] = FAST_TK_INIT,
109 static struct tk_fast tk_fast_raw ____cacheline_aligned = {
110 .seq = SEQCNT_LATCH_ZERO(tk_fast_raw.seq),
111 .base[0] = FAST_TK_INIT,
112 .base[1] = FAST_TK_INIT,
115 static inline void tk_normalize_xtime(struct timekeeper *tk)
117 while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
118 tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
121 while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) {
122 tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
127 static inline struct timespec64 tk_xtime(const struct timekeeper *tk)
129 struct timespec64 ts;
131 ts.tv_sec = tk->xtime_sec;
132 ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
136 static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
138 tk->xtime_sec = ts->tv_sec;
139 tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
142 static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts)
144 tk->xtime_sec += ts->tv_sec;
145 tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift;
146 tk_normalize_xtime(tk);
149 static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
151 struct timespec64 tmp;
154 * Verify consistency of: offset_real = -wall_to_monotonic
155 * before modifying anything
157 set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
158 -tk->wall_to_monotonic.tv_nsec);
159 WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp));
160 tk->wall_to_monotonic = wtm;
161 set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
162 tk->offs_real = timespec64_to_ktime(tmp);
163 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
166 static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
168 tk->offs_boot = ktime_add(tk->offs_boot, delta);
170 * Timespec representation for VDSO update to avoid 64bit division
173 tk->monotonic_to_boot = ktime_to_timespec64(tk->offs_boot);
177 * tk_clock_read - atomic clocksource read() helper
179 * This helper is necessary to use in the read paths because, while the
180 * seqcount ensures we don't return a bad value while structures are updated,
181 * it doesn't protect from potential crashes. There is the possibility that
182 * the tkr's clocksource may change between the read reference, and the
183 * clock reference passed to the read function. This can cause crashes if
184 * the wrong clocksource is passed to the wrong read function.
185 * This isn't necessary to use when holding the timekeeper_lock or doing
186 * a read of the fast-timekeeper tkrs (which is protected by its own locking
189 static inline u64 tk_clock_read(const struct tk_read_base *tkr)
191 struct clocksource *clock = READ_ONCE(tkr->clock);
193 return clock->read(clock);
196 #ifdef CONFIG_DEBUG_TIMEKEEPING
197 #define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
199 static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
202 u64 max_cycles = tk->tkr_mono.clock->max_cycles;
203 const char *name = tk->tkr_mono.clock->name;
205 if (offset > max_cycles) {
206 printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
207 offset, name, max_cycles);
208 printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
210 if (offset > (max_cycles >> 1)) {
211 printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
212 offset, name, max_cycles >> 1);
213 printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
217 if (tk->underflow_seen) {
218 if (jiffies - tk->last_warning > WARNING_FREQ) {
219 printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
220 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
221 printk_deferred(" Your kernel is probably still fine.\n");
222 tk->last_warning = jiffies;
224 tk->underflow_seen = 0;
227 if (tk->overflow_seen) {
228 if (jiffies - tk->last_warning > WARNING_FREQ) {
229 printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
230 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
231 printk_deferred(" Your kernel is probably still fine.\n");
232 tk->last_warning = jiffies;
234 tk->overflow_seen = 0;
238 static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
240 struct timekeeper *tk = &tk_core.timekeeper;
241 u64 now, last, mask, max, delta;
245 * Since we're called holding a seqcount, the data may shift
246 * under us while we're doing the calculation. This can cause
247 * false positives, since we'd note a problem but throw the
248 * results away. So nest another seqcount here to atomically
249 * grab the points we are checking with.
252 seq = read_seqcount_begin(&tk_core.seq);
253 now = tk_clock_read(tkr);
254 last = tkr->cycle_last;
256 max = tkr->clock->max_cycles;
257 } while (read_seqcount_retry(&tk_core.seq, seq));
259 delta = clocksource_delta(now, last, mask);
262 * Try to catch underflows by checking if we are seeing small
263 * mask-relative negative values.
265 if (unlikely((~delta & mask) < (mask >> 3))) {
266 tk->underflow_seen = 1;
270 /* Cap delta value to the max_cycles values to avoid mult overflows */
271 if (unlikely(delta > max)) {
272 tk->overflow_seen = 1;
273 delta = tkr->clock->max_cycles;
279 static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
282 static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
284 u64 cycle_now, delta;
286 /* read clocksource */
287 cycle_now = tk_clock_read(tkr);
289 /* calculate the delta since the last update_wall_time */
290 delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
297 * tk_setup_internals - Set up internals to use clocksource clock.
299 * @tk: The target timekeeper to setup.
300 * @clock: Pointer to clocksource.
302 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
303 * pair and interval request.
305 * Unless you're the timekeeping code, you should not be using this!
307 static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
310 u64 tmp, ntpinterval;
311 struct clocksource *old_clock;
313 ++tk->cs_was_changed_seq;
314 old_clock = tk->tkr_mono.clock;
315 tk->tkr_mono.clock = clock;
316 tk->tkr_mono.mask = clock->mask;
317 tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono);
319 tk->tkr_raw.clock = clock;
320 tk->tkr_raw.mask = clock->mask;
321 tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
323 /* Do the ns -> cycle conversion first, using original mult */
324 tmp = NTP_INTERVAL_LENGTH;
325 tmp <<= clock->shift;
327 tmp += clock->mult/2;
328 do_div(tmp, clock->mult);
332 interval = (u64) tmp;
333 tk->cycle_interval = interval;
335 /* Go back from cycles -> shifted ns */
336 tk->xtime_interval = interval * clock->mult;
337 tk->xtime_remainder = ntpinterval - tk->xtime_interval;
338 tk->raw_interval = interval * clock->mult;
340 /* if changing clocks, convert xtime_nsec shift units */
342 int shift_change = clock->shift - old_clock->shift;
343 if (shift_change < 0) {
344 tk->tkr_mono.xtime_nsec >>= -shift_change;
345 tk->tkr_raw.xtime_nsec >>= -shift_change;
347 tk->tkr_mono.xtime_nsec <<= shift_change;
348 tk->tkr_raw.xtime_nsec <<= shift_change;
352 tk->tkr_mono.shift = clock->shift;
353 tk->tkr_raw.shift = clock->shift;
356 tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
357 tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
360 * The timekeeper keeps its own mult values for the currently
361 * active clocksource. These value will be adjusted via NTP
362 * to counteract clock drifting.
364 tk->tkr_mono.mult = clock->mult;
365 tk->tkr_raw.mult = clock->mult;
366 tk->ntp_err_mult = 0;
367 tk->skip_second_overflow = 0;
370 /* Timekeeper helper functions. */
372 static inline u64 timekeeping_delta_to_ns(const struct tk_read_base *tkr, u64 delta)
376 nsec = delta * tkr->mult + tkr->xtime_nsec;
382 static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr)
386 delta = timekeeping_get_delta(tkr);
387 return timekeeping_delta_to_ns(tkr, delta);
390 static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles)
394 /* calculate the delta since the last update_wall_time */
395 delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
396 return timekeeping_delta_to_ns(tkr, delta);
400 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
401 * @tkr: Timekeeping readout base from which we take the update
402 * @tkf: Pointer to NMI safe timekeeper
404 * We want to use this from any context including NMI and tracing /
405 * instrumenting the timekeeping code itself.
407 * Employ the latch technique; see @raw_write_seqcount_latch.
409 * So if a NMI hits the update of base[0] then it will use base[1]
410 * which is still consistent. In the worst case this can result is a
411 * slightly wrong timestamp (a few nanoseconds). See
412 * @ktime_get_mono_fast_ns.
414 static void update_fast_timekeeper(const struct tk_read_base *tkr,
417 struct tk_read_base *base = tkf->base;
419 /* Force readers off to base[1] */
420 raw_write_seqcount_latch(&tkf->seq);
423 memcpy(base, tkr, sizeof(*base));
425 /* Force readers back to base[0] */
426 raw_write_seqcount_latch(&tkf->seq);
429 memcpy(base + 1, base, sizeof(*base));
432 static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
434 struct tk_read_base *tkr;
439 seq = raw_read_seqcount_latch(&tkf->seq);
440 tkr = tkf->base + (seq & 0x01);
441 now = ktime_to_ns(tkr->base);
443 now += timekeeping_delta_to_ns(tkr,
448 } while (read_seqcount_latch_retry(&tkf->seq, seq));
454 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
456 * This timestamp is not guaranteed to be monotonic across an update.
457 * The timestamp is calculated by:
459 * now = base_mono + clock_delta * slope
461 * So if the update lowers the slope, readers who are forced to the
462 * not yet updated second array are still using the old steeper slope.
471 * |12345678---> reader order
477 * So reader 6 will observe time going backwards versus reader 5.
479 * While other CPUs are likely to be able to observe that, the only way
480 * for a CPU local observation is when an NMI hits in the middle of
481 * the update. Timestamps taken from that NMI context might be ahead
482 * of the following timestamps. Callers need to be aware of that and
485 u64 ktime_get_mono_fast_ns(void)
487 return __ktime_get_fast_ns(&tk_fast_mono);
489 EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
492 * ktime_get_raw_fast_ns - Fast NMI safe access to clock monotonic raw
494 * Contrary to ktime_get_mono_fast_ns() this is always correct because the
495 * conversion factor is not affected by NTP/PTP correction.
497 u64 ktime_get_raw_fast_ns(void)
499 return __ktime_get_fast_ns(&tk_fast_raw);
501 EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
504 * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
506 * To keep it NMI safe since we're accessing from tracing, we're not using a
507 * separate timekeeper with updates to monotonic clock and boot offset
508 * protected with seqcounts. This has the following minor side effects:
510 * (1) Its possible that a timestamp be taken after the boot offset is updated
511 * but before the timekeeper is updated. If this happens, the new boot offset
512 * is added to the old timekeeping making the clock appear to update slightly
515 * timekeeping_inject_sleeptime64()
516 * __timekeeping_inject_sleeptime(tk, delta);
518 * timekeeping_update(tk, TK_CLEAR_NTP...);
520 * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
521 * partially updated. Since the tk->offs_boot update is a rare event, this
522 * should be a rare occurrence which postprocessing should be able to handle.
524 * The caveats vs. timestamp ordering as documented for ktime_get_fast_ns()
527 u64 notrace ktime_get_boot_fast_ns(void)
529 struct timekeeper *tk = &tk_core.timekeeper;
531 return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_boot)));
533 EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
536 * ktime_get_tai_fast_ns - NMI safe and fast access to tai clock.
538 * The same limitations as described for ktime_get_boot_fast_ns() apply. The
539 * mono time and the TAI offset are not read atomically which may yield wrong
540 * readouts. However, an update of the TAI offset is an rare event e.g., caused
541 * by settime or adjtimex with an offset. The user of this function has to deal
542 * with the possibility of wrong timestamps in post processing.
544 u64 notrace ktime_get_tai_fast_ns(void)
546 struct timekeeper *tk = &tk_core.timekeeper;
548 return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_tai)));
550 EXPORT_SYMBOL_GPL(ktime_get_tai_fast_ns);
552 static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono)
554 struct tk_read_base *tkr;
555 u64 basem, baser, delta;
559 seq = raw_read_seqcount_latch(&tkf->seq);
560 tkr = tkf->base + (seq & 0x01);
561 basem = ktime_to_ns(tkr->base);
562 baser = ktime_to_ns(tkr->base_real);
564 delta = timekeeping_delta_to_ns(tkr,
565 clocksource_delta(tk_clock_read(tkr),
566 tkr->cycle_last, tkr->mask));
567 } while (read_seqcount_latch_retry(&tkf->seq, seq));
570 *mono = basem + delta;
571 return baser + delta;
575 * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime.
577 * See ktime_get_fast_ns() for documentation of the time stamp ordering.
579 u64 ktime_get_real_fast_ns(void)
581 return __ktime_get_real_fast(&tk_fast_mono, NULL);
583 EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns);
586 * ktime_get_fast_timestamps: - NMI safe timestamps
587 * @snapshot: Pointer to timestamp storage
589 * Stores clock monotonic, boottime and realtime timestamps.
591 * Boot time is a racy access on 32bit systems if the sleep time injection
592 * happens late during resume and not in timekeeping_resume(). That could
593 * be avoided by expanding struct tk_read_base with boot offset for 32bit
594 * and adding more overhead to the update. As this is a hard to observe
595 * once per resume event which can be filtered with reasonable effort using
596 * the accurate mono/real timestamps, it's probably not worth the trouble.
598 * Aside of that it might be possible on 32 and 64 bit to observe the
599 * following when the sleep time injection happens late:
602 * timekeeping_resume()
603 * ktime_get_fast_timestamps()
604 * mono, real = __ktime_get_real_fast()
605 * inject_sleep_time()
607 * boot = mono + bootoffset;
609 * That means that boot time already has the sleep time adjustment, but
610 * real time does not. On the next readout both are in sync again.
612 * Preventing this for 64bit is not really feasible without destroying the
613 * careful cache layout of the timekeeper because the sequence count and
614 * struct tk_read_base would then need two cache lines instead of one.
616 * Access to the time keeper clock source is disabled across the innermost
617 * steps of suspend/resume. The accessors still work, but the timestamps
618 * are frozen until time keeping is resumed which happens very early.
620 * For regular suspend/resume there is no observable difference vs. sched
621 * clock, but it might affect some of the nasty low level debug printks.
623 * OTOH, access to sched clock is not guaranteed across suspend/resume on
624 * all systems either so it depends on the hardware in use.
626 * If that turns out to be a real problem then this could be mitigated by
627 * using sched clock in a similar way as during early boot. But it's not as
628 * trivial as on early boot because it needs some careful protection
629 * against the clock monotonic timestamp jumping backwards on resume.
631 void ktime_get_fast_timestamps(struct ktime_timestamps *snapshot)
633 struct timekeeper *tk = &tk_core.timekeeper;
635 snapshot->real = __ktime_get_real_fast(&tk_fast_mono, &snapshot->mono);
636 snapshot->boot = snapshot->mono + ktime_to_ns(data_race(tk->offs_boot));
640 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
641 * @tk: Timekeeper to snapshot.
643 * It generally is unsafe to access the clocksource after timekeeping has been
644 * suspended, so take a snapshot of the readout base of @tk and use it as the
645 * fast timekeeper's readout base while suspended. It will return the same
646 * number of cycles every time until timekeeping is resumed at which time the
647 * proper readout base for the fast timekeeper will be restored automatically.
649 static void halt_fast_timekeeper(const struct timekeeper *tk)
651 static struct tk_read_base tkr_dummy;
652 const struct tk_read_base *tkr = &tk->tkr_mono;
654 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
655 cycles_at_suspend = tk_clock_read(tkr);
656 tkr_dummy.clock = &dummy_clock;
657 tkr_dummy.base_real = tkr->base + tk->offs_real;
658 update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
661 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
662 tkr_dummy.clock = &dummy_clock;
663 update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
666 static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
668 static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
670 raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
674 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
675 * @nb: Pointer to the notifier block to register
677 int pvclock_gtod_register_notifier(struct notifier_block *nb)
679 struct timekeeper *tk = &tk_core.timekeeper;
683 raw_spin_lock_irqsave(&timekeeper_lock, flags);
684 ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
685 update_pvclock_gtod(tk, true);
686 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
690 EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
693 * pvclock_gtod_unregister_notifier - unregister a pvclock
694 * timedata update listener
695 * @nb: Pointer to the notifier block to unregister
697 int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
702 raw_spin_lock_irqsave(&timekeeper_lock, flags);
703 ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
704 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
708 EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
711 * tk_update_leap_state - helper to update the next_leap_ktime
713 static inline void tk_update_leap_state(struct timekeeper *tk)
715 tk->next_leap_ktime = ntp_get_next_leap();
716 if (tk->next_leap_ktime != KTIME_MAX)
717 /* Convert to monotonic time */
718 tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
722 * Update the ktime_t based scalar nsec members of the timekeeper
724 static inline void tk_update_ktime_data(struct timekeeper *tk)
730 * The xtime based monotonic readout is:
731 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
732 * The ktime based monotonic readout is:
733 * nsec = base_mono + now();
734 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
736 seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
737 nsec = (u32) tk->wall_to_monotonic.tv_nsec;
738 tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
741 * The sum of the nanoseconds portions of xtime and
742 * wall_to_monotonic can be greater/equal one second. Take
743 * this into account before updating tk->ktime_sec.
745 nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
746 if (nsec >= NSEC_PER_SEC)
748 tk->ktime_sec = seconds;
750 /* Update the monotonic raw base */
751 tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
754 /* must hold timekeeper_lock */
755 static void timekeeping_update(struct timekeeper *tk, unsigned int action)
757 if (action & TK_CLEAR_NTP) {
762 tk_update_leap_state(tk);
763 tk_update_ktime_data(tk);
766 update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
768 tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
769 update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
770 update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
772 if (action & TK_CLOCK_WAS_SET)
773 tk->clock_was_set_seq++;
775 * The mirroring of the data to the shadow-timekeeper needs
776 * to happen last here to ensure we don't over-write the
777 * timekeeper structure on the next update with stale data
779 if (action & TK_MIRROR)
780 memcpy(&shadow_timekeeper, &tk_core.timekeeper,
781 sizeof(tk_core.timekeeper));
785 * timekeeping_forward_now - update clock to the current time
786 * @tk: Pointer to the timekeeper to update
788 * Forward the current clock to update its state since the last call to
789 * update_wall_time(). This is useful before significant clock changes,
790 * as it avoids having to deal with this time offset explicitly.
792 static void timekeeping_forward_now(struct timekeeper *tk)
794 u64 cycle_now, delta;
796 cycle_now = tk_clock_read(&tk->tkr_mono);
797 delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
798 tk->tkr_mono.cycle_last = cycle_now;
799 tk->tkr_raw.cycle_last = cycle_now;
801 tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
802 tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
804 tk_normalize_xtime(tk);
808 * ktime_get_real_ts64 - Returns the time of day in a timespec64.
809 * @ts: pointer to the timespec to be set
811 * Returns the time of day in a timespec64 (WARN if suspended).
813 void ktime_get_real_ts64(struct timespec64 *ts)
815 struct timekeeper *tk = &tk_core.timekeeper;
819 WARN_ON(timekeeping_suspended);
822 seq = read_seqcount_begin(&tk_core.seq);
824 ts->tv_sec = tk->xtime_sec;
825 nsecs = timekeeping_get_ns(&tk->tkr_mono);
827 } while (read_seqcount_retry(&tk_core.seq, seq));
830 timespec64_add_ns(ts, nsecs);
832 EXPORT_SYMBOL(ktime_get_real_ts64);
834 ktime_t ktime_get(void)
836 struct timekeeper *tk = &tk_core.timekeeper;
841 WARN_ON(timekeeping_suspended);
844 seq = read_seqcount_begin(&tk_core.seq);
845 base = tk->tkr_mono.base;
846 nsecs = timekeeping_get_ns(&tk->tkr_mono);
848 } while (read_seqcount_retry(&tk_core.seq, seq));
850 return ktime_add_ns(base, nsecs);
852 EXPORT_SYMBOL_GPL(ktime_get);
854 u32 ktime_get_resolution_ns(void)
856 struct timekeeper *tk = &tk_core.timekeeper;
860 WARN_ON(timekeeping_suspended);
863 seq = read_seqcount_begin(&tk_core.seq);
864 nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
865 } while (read_seqcount_retry(&tk_core.seq, seq));
869 EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
871 static ktime_t *offsets[TK_OFFS_MAX] = {
872 [TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
873 [TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
874 [TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai,
877 ktime_t ktime_get_with_offset(enum tk_offsets offs)
879 struct timekeeper *tk = &tk_core.timekeeper;
881 ktime_t base, *offset = offsets[offs];
884 WARN_ON(timekeeping_suspended);
887 seq = read_seqcount_begin(&tk_core.seq);
888 base = ktime_add(tk->tkr_mono.base, *offset);
889 nsecs = timekeeping_get_ns(&tk->tkr_mono);
891 } while (read_seqcount_retry(&tk_core.seq, seq));
893 return ktime_add_ns(base, nsecs);
896 EXPORT_SYMBOL_GPL(ktime_get_with_offset);
898 ktime_t ktime_get_coarse_with_offset(enum tk_offsets offs)
900 struct timekeeper *tk = &tk_core.timekeeper;
902 ktime_t base, *offset = offsets[offs];
905 WARN_ON(timekeeping_suspended);
908 seq = read_seqcount_begin(&tk_core.seq);
909 base = ktime_add(tk->tkr_mono.base, *offset);
910 nsecs = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
912 } while (read_seqcount_retry(&tk_core.seq, seq));
914 return ktime_add_ns(base, nsecs);
916 EXPORT_SYMBOL_GPL(ktime_get_coarse_with_offset);
919 * ktime_mono_to_any() - convert monotonic time to any other time
920 * @tmono: time to convert.
921 * @offs: which offset to use
923 ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
925 ktime_t *offset = offsets[offs];
930 seq = read_seqcount_begin(&tk_core.seq);
931 tconv = ktime_add(tmono, *offset);
932 } while (read_seqcount_retry(&tk_core.seq, seq));
936 EXPORT_SYMBOL_GPL(ktime_mono_to_any);
939 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
941 ktime_t ktime_get_raw(void)
943 struct timekeeper *tk = &tk_core.timekeeper;
949 seq = read_seqcount_begin(&tk_core.seq);
950 base = tk->tkr_raw.base;
951 nsecs = timekeeping_get_ns(&tk->tkr_raw);
953 } while (read_seqcount_retry(&tk_core.seq, seq));
955 return ktime_add_ns(base, nsecs);
957 EXPORT_SYMBOL_GPL(ktime_get_raw);
960 * ktime_get_ts64 - get the monotonic clock in timespec64 format
961 * @ts: pointer to timespec variable
963 * The function calculates the monotonic clock from the realtime
964 * clock and the wall_to_monotonic offset and stores the result
965 * in normalized timespec64 format in the variable pointed to by @ts.
967 void ktime_get_ts64(struct timespec64 *ts)
969 struct timekeeper *tk = &tk_core.timekeeper;
970 struct timespec64 tomono;
974 WARN_ON(timekeeping_suspended);
977 seq = read_seqcount_begin(&tk_core.seq);
978 ts->tv_sec = tk->xtime_sec;
979 nsec = timekeeping_get_ns(&tk->tkr_mono);
980 tomono = tk->wall_to_monotonic;
982 } while (read_seqcount_retry(&tk_core.seq, seq));
984 ts->tv_sec += tomono.tv_sec;
986 timespec64_add_ns(ts, nsec + tomono.tv_nsec);
988 EXPORT_SYMBOL_GPL(ktime_get_ts64);
991 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
993 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
994 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
995 * works on both 32 and 64 bit systems. On 32 bit systems the readout
996 * covers ~136 years of uptime which should be enough to prevent
997 * premature wrap arounds.
999 time64_t ktime_get_seconds(void)
1001 struct timekeeper *tk = &tk_core.timekeeper;
1003 WARN_ON(timekeeping_suspended);
1004 return tk->ktime_sec;
1006 EXPORT_SYMBOL_GPL(ktime_get_seconds);
1009 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
1011 * Returns the wall clock seconds since 1970.
1013 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
1014 * 32bit systems the access must be protected with the sequence
1015 * counter to provide "atomic" access to the 64bit tk->xtime_sec
1018 time64_t ktime_get_real_seconds(void)
1020 struct timekeeper *tk = &tk_core.timekeeper;
1024 if (IS_ENABLED(CONFIG_64BIT))
1025 return tk->xtime_sec;
1028 seq = read_seqcount_begin(&tk_core.seq);
1029 seconds = tk->xtime_sec;
1031 } while (read_seqcount_retry(&tk_core.seq, seq));
1035 EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
1038 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
1039 * but without the sequence counter protect. This internal function
1040 * is called just when timekeeping lock is already held.
1042 noinstr time64_t __ktime_get_real_seconds(void)
1044 struct timekeeper *tk = &tk_core.timekeeper;
1046 return tk->xtime_sec;
1050 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
1051 * @systime_snapshot: pointer to struct receiving the system time snapshot
1053 void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
1055 struct timekeeper *tk = &tk_core.timekeeper;
1063 WARN_ON_ONCE(timekeeping_suspended);
1066 seq = read_seqcount_begin(&tk_core.seq);
1067 now = tk_clock_read(&tk->tkr_mono);
1068 systime_snapshot->cs_id = tk->tkr_mono.clock->id;
1069 systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
1070 systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
1071 base_real = ktime_add(tk->tkr_mono.base,
1072 tk_core.timekeeper.offs_real);
1073 base_raw = tk->tkr_raw.base;
1074 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
1075 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
1076 } while (read_seqcount_retry(&tk_core.seq, seq));
1078 systime_snapshot->cycles = now;
1079 systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
1080 systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
1082 EXPORT_SYMBOL_GPL(ktime_get_snapshot);
1084 /* Scale base by mult/div checking for overflow */
1085 static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
1089 tmp = div64_u64_rem(*base, div, &rem);
1091 if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
1092 ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
1096 rem = div64_u64(rem * mult, div);
1102 * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
1103 * @history: Snapshot representing start of history
1104 * @partial_history_cycles: Cycle offset into history (fractional part)
1105 * @total_history_cycles: Total history length in cycles
1106 * @discontinuity: True indicates clock was set on history period
1107 * @ts: Cross timestamp that should be adjusted using
1108 * partial/total ratio
1110 * Helper function used by get_device_system_crosststamp() to correct the
1111 * crosstimestamp corresponding to the start of the current interval to the
1112 * system counter value (timestamp point) provided by the driver. The
1113 * total_history_* quantities are the total history starting at the provided
1114 * reference point and ending at the start of the current interval. The cycle
1115 * count between the driver timestamp point and the start of the current
1116 * interval is partial_history_cycles.
1118 static int adjust_historical_crosststamp(struct system_time_snapshot *history,
1119 u64 partial_history_cycles,
1120 u64 total_history_cycles,
1122 struct system_device_crosststamp *ts)
1124 struct timekeeper *tk = &tk_core.timekeeper;
1125 u64 corr_raw, corr_real;
1126 bool interp_forward;
1129 if (total_history_cycles == 0 || partial_history_cycles == 0)
1132 /* Interpolate shortest distance from beginning or end of history */
1133 interp_forward = partial_history_cycles > total_history_cycles / 2;
1134 partial_history_cycles = interp_forward ?
1135 total_history_cycles - partial_history_cycles :
1136 partial_history_cycles;
1139 * Scale the monotonic raw time delta by:
1140 * partial_history_cycles / total_history_cycles
1142 corr_raw = (u64)ktime_to_ns(
1143 ktime_sub(ts->sys_monoraw, history->raw));
1144 ret = scale64_check_overflow(partial_history_cycles,
1145 total_history_cycles, &corr_raw);
1150 * If there is a discontinuity in the history, scale monotonic raw
1152 * mult(real)/mult(raw) yielding the realtime correction
1153 * Otherwise, calculate the realtime correction similar to monotonic
1156 if (discontinuity) {
1157 corr_real = mul_u64_u32_div
1158 (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1160 corr_real = (u64)ktime_to_ns(
1161 ktime_sub(ts->sys_realtime, history->real));
1162 ret = scale64_check_overflow(partial_history_cycles,
1163 total_history_cycles, &corr_real);
1168 /* Fixup monotonic raw and real time time values */
1169 if (interp_forward) {
1170 ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1171 ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1173 ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1174 ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1181 * cycle_between - true if test occurs chronologically between before and after
1183 static bool cycle_between(u64 before, u64 test, u64 after)
1185 if (test > before && test < after)
1187 if (test < before && before > after)
1193 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1194 * @get_time_fn: Callback to get simultaneous device time and
1195 * system counter from the device driver
1196 * @ctx: Context passed to get_time_fn()
1197 * @history_begin: Historical reference point used to interpolate system
1198 * time when counter provided by the driver is before the current interval
1199 * @xtstamp: Receives simultaneously captured system and device time
1201 * Reads a timestamp from a device and correlates it to system time
1203 int get_device_system_crosststamp(int (*get_time_fn)
1204 (ktime_t *device_time,
1205 struct system_counterval_t *sys_counterval,
1208 struct system_time_snapshot *history_begin,
1209 struct system_device_crosststamp *xtstamp)
1211 struct system_counterval_t system_counterval;
1212 struct timekeeper *tk = &tk_core.timekeeper;
1213 u64 cycles, now, interval_start;
1214 unsigned int clock_was_set_seq = 0;
1215 ktime_t base_real, base_raw;
1216 u64 nsec_real, nsec_raw;
1217 u8 cs_was_changed_seq;
1223 seq = read_seqcount_begin(&tk_core.seq);
1225 * Try to synchronously capture device time and a system
1226 * counter value calling back into the device driver
1228 ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1233 * Verify that the clocksource associated with the captured
1234 * system counter value is the same as the currently installed
1235 * timekeeper clocksource
1237 if (tk->tkr_mono.clock != system_counterval.cs)
1239 cycles = system_counterval.cycles;
1242 * Check whether the system counter value provided by the
1243 * device driver is on the current timekeeping interval.
1245 now = tk_clock_read(&tk->tkr_mono);
1246 interval_start = tk->tkr_mono.cycle_last;
1247 if (!cycle_between(interval_start, cycles, now)) {
1248 clock_was_set_seq = tk->clock_was_set_seq;
1249 cs_was_changed_seq = tk->cs_was_changed_seq;
1250 cycles = interval_start;
1256 base_real = ktime_add(tk->tkr_mono.base,
1257 tk_core.timekeeper.offs_real);
1258 base_raw = tk->tkr_raw.base;
1260 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1261 system_counterval.cycles);
1262 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1263 system_counterval.cycles);
1264 } while (read_seqcount_retry(&tk_core.seq, seq));
1266 xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1267 xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1270 * Interpolate if necessary, adjusting back from the start of the
1274 u64 partial_history_cycles, total_history_cycles;
1278 * Check that the counter value occurs after the provided
1279 * history reference and that the history doesn't cross a
1280 * clocksource change
1282 if (!history_begin ||
1283 !cycle_between(history_begin->cycles,
1284 system_counterval.cycles, cycles) ||
1285 history_begin->cs_was_changed_seq != cs_was_changed_seq)
1287 partial_history_cycles = cycles - system_counterval.cycles;
1288 total_history_cycles = cycles - history_begin->cycles;
1290 history_begin->clock_was_set_seq != clock_was_set_seq;
1292 ret = adjust_historical_crosststamp(history_begin,
1293 partial_history_cycles,
1294 total_history_cycles,
1295 discontinuity, xtstamp);
1302 EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1305 * do_settimeofday64 - Sets the time of day.
1306 * @ts: pointer to the timespec64 variable containing the new time
1308 * Sets the time of day to the new time and update NTP and notify hrtimers
1310 int do_settimeofday64(const struct timespec64 *ts)
1312 struct timekeeper *tk = &tk_core.timekeeper;
1313 struct timespec64 ts_delta, xt;
1314 unsigned long flags;
1317 if (!timespec64_valid_settod(ts))
1320 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1321 write_seqcount_begin(&tk_core.seq);
1323 timekeeping_forward_now(tk);
1326 ts_delta = timespec64_sub(*ts, xt);
1328 if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1333 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1335 tk_set_xtime(tk, ts);
1337 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1339 write_seqcount_end(&tk_core.seq);
1340 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1342 /* Signal hrtimers about time change */
1343 clock_was_set(CLOCK_SET_WALL);
1346 audit_tk_injoffset(ts_delta);
1350 EXPORT_SYMBOL(do_settimeofday64);
1353 * timekeeping_inject_offset - Adds or subtracts from the current time.
1354 * @ts: Pointer to the timespec variable containing the offset
1356 * Adds or subtracts an offset value from the current time.
1358 static int timekeeping_inject_offset(const struct timespec64 *ts)
1360 struct timekeeper *tk = &tk_core.timekeeper;
1361 unsigned long flags;
1362 struct timespec64 tmp;
1365 if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
1368 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1369 write_seqcount_begin(&tk_core.seq);
1371 timekeeping_forward_now(tk);
1373 /* Make sure the proposed value is valid */
1374 tmp = timespec64_add(tk_xtime(tk), *ts);
1375 if (timespec64_compare(&tk->wall_to_monotonic, ts) > 0 ||
1376 !timespec64_valid_settod(&tmp)) {
1381 tk_xtime_add(tk, ts);
1382 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *ts));
1384 error: /* even if we error out, we forwarded the time, so call update */
1385 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1387 write_seqcount_end(&tk_core.seq);
1388 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1390 /* Signal hrtimers about time change */
1391 clock_was_set(CLOCK_SET_WALL);
1397 * Indicates if there is an offset between the system clock and the hardware
1398 * clock/persistent clock/rtc.
1400 int persistent_clock_is_local;
1403 * Adjust the time obtained from the CMOS to be UTC time instead of
1406 * This is ugly, but preferable to the alternatives. Otherwise we
1407 * would either need to write a program to do it in /etc/rc (and risk
1408 * confusion if the program gets run more than once; it would also be
1409 * hard to make the program warp the clock precisely n hours) or
1410 * compile in the timezone information into the kernel. Bad, bad....
1414 * The best thing to do is to keep the CMOS clock in universal time (UTC)
1415 * as real UNIX machines always do it. This avoids all headaches about
1416 * daylight saving times and warping kernel clocks.
1418 void timekeeping_warp_clock(void)
1420 if (sys_tz.tz_minuteswest != 0) {
1421 struct timespec64 adjust;
1423 persistent_clock_is_local = 1;
1424 adjust.tv_sec = sys_tz.tz_minuteswest * 60;
1426 timekeeping_inject_offset(&adjust);
1431 * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1433 static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1435 tk->tai_offset = tai_offset;
1436 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1440 * change_clocksource - Swaps clocksources if a new one is available
1442 * Accumulates current time interval and initializes new clocksource
1444 static int change_clocksource(void *data)
1446 struct timekeeper *tk = &tk_core.timekeeper;
1447 struct clocksource *new, *old = NULL;
1448 unsigned long flags;
1449 bool change = false;
1451 new = (struct clocksource *) data;
1454 * If the cs is in module, get a module reference. Succeeds
1455 * for built-in code (owner == NULL) as well.
1457 if (try_module_get(new->owner)) {
1458 if (!new->enable || new->enable(new) == 0)
1461 module_put(new->owner);
1464 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1465 write_seqcount_begin(&tk_core.seq);
1467 timekeeping_forward_now(tk);
1470 old = tk->tkr_mono.clock;
1471 tk_setup_internals(tk, new);
1474 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1476 write_seqcount_end(&tk_core.seq);
1477 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1483 module_put(old->owner);
1490 * timekeeping_notify - Install a new clock source
1491 * @clock: pointer to the clock source
1493 * This function is called from clocksource.c after a new, better clock
1494 * source has been registered. The caller holds the clocksource_mutex.
1496 int timekeeping_notify(struct clocksource *clock)
1498 struct timekeeper *tk = &tk_core.timekeeper;
1500 if (tk->tkr_mono.clock == clock)
1502 stop_machine(change_clocksource, clock, NULL);
1503 tick_clock_notify();
1504 return tk->tkr_mono.clock == clock ? 0 : -1;
1508 * ktime_get_raw_ts64 - Returns the raw monotonic time in a timespec
1509 * @ts: pointer to the timespec64 to be set
1511 * Returns the raw monotonic time (completely un-modified by ntp)
1513 void ktime_get_raw_ts64(struct timespec64 *ts)
1515 struct timekeeper *tk = &tk_core.timekeeper;
1520 seq = read_seqcount_begin(&tk_core.seq);
1521 ts->tv_sec = tk->raw_sec;
1522 nsecs = timekeeping_get_ns(&tk->tkr_raw);
1524 } while (read_seqcount_retry(&tk_core.seq, seq));
1527 timespec64_add_ns(ts, nsecs);
1529 EXPORT_SYMBOL(ktime_get_raw_ts64);
1533 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1535 int timekeeping_valid_for_hres(void)
1537 struct timekeeper *tk = &tk_core.timekeeper;
1542 seq = read_seqcount_begin(&tk_core.seq);
1544 ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1546 } while (read_seqcount_retry(&tk_core.seq, seq));
1552 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1554 u64 timekeeping_max_deferment(void)
1556 struct timekeeper *tk = &tk_core.timekeeper;
1561 seq = read_seqcount_begin(&tk_core.seq);
1563 ret = tk->tkr_mono.clock->max_idle_ns;
1565 } while (read_seqcount_retry(&tk_core.seq, seq));
1571 * read_persistent_clock64 - Return time from the persistent clock.
1572 * @ts: Pointer to the storage for the readout value
1574 * Weak dummy function for arches that do not yet support it.
1575 * Reads the time from the battery backed persistent clock.
1576 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1578 * XXX - Do be sure to remove it once all arches implement it.
1580 void __weak read_persistent_clock64(struct timespec64 *ts)
1587 * read_persistent_wall_and_boot_offset - Read persistent clock, and also offset
1590 * Weak dummy function for arches that do not yet support it.
1591 * @wall_time: - current time as returned by persistent clock
1592 * @boot_offset: - offset that is defined as wall_time - boot_time
1594 * The default function calculates offset based on the current value of
1595 * local_clock(). This way architectures that support sched_clock() but don't
1596 * support dedicated boot time clock will provide the best estimate of the
1600 read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
1601 struct timespec64 *boot_offset)
1603 read_persistent_clock64(wall_time);
1604 *boot_offset = ns_to_timespec64(local_clock());
1608 * Flag reflecting whether timekeeping_resume() has injected sleeptime.
1610 * The flag starts of false and is only set when a suspend reaches
1611 * timekeeping_suspend(), timekeeping_resume() sets it to false when the
1612 * timekeeper clocksource is not stopping across suspend and has been
1613 * used to update sleep time. If the timekeeper clocksource has stopped
1614 * then the flag stays true and is used by the RTC resume code to decide
1615 * whether sleeptime must be injected and if so the flag gets false then.
1617 * If a suspend fails before reaching timekeeping_resume() then the flag
1618 * stays false and prevents erroneous sleeptime injection.
1620 static bool suspend_timing_needed;
1622 /* Flag for if there is a persistent clock on this platform */
1623 static bool persistent_clock_exists;
1626 * timekeeping_init - Initializes the clocksource and common timekeeping values
1628 void __init timekeeping_init(void)
1630 struct timespec64 wall_time, boot_offset, wall_to_mono;
1631 struct timekeeper *tk = &tk_core.timekeeper;
1632 struct clocksource *clock;
1633 unsigned long flags;
1635 read_persistent_wall_and_boot_offset(&wall_time, &boot_offset);
1636 if (timespec64_valid_settod(&wall_time) &&
1637 timespec64_to_ns(&wall_time) > 0) {
1638 persistent_clock_exists = true;
1639 } else if (timespec64_to_ns(&wall_time) != 0) {
1640 pr_warn("Persistent clock returned invalid value");
1641 wall_time = (struct timespec64){0};
1644 if (timespec64_compare(&wall_time, &boot_offset) < 0)
1645 boot_offset = (struct timespec64){0};
1648 * We want set wall_to_mono, so the following is true:
1649 * wall time + wall_to_mono = boot time
1651 wall_to_mono = timespec64_sub(boot_offset, wall_time);
1653 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1654 write_seqcount_begin(&tk_core.seq);
1657 clock = clocksource_default_clock();
1659 clock->enable(clock);
1660 tk_setup_internals(tk, clock);
1662 tk_set_xtime(tk, &wall_time);
1665 tk_set_wall_to_mono(tk, wall_to_mono);
1667 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1669 write_seqcount_end(&tk_core.seq);
1670 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1673 /* time in seconds when suspend began for persistent clock */
1674 static struct timespec64 timekeeping_suspend_time;
1677 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1678 * @tk: Pointer to the timekeeper to be updated
1679 * @delta: Pointer to the delta value in timespec64 format
1681 * Takes a timespec offset measuring a suspend interval and properly
1682 * adds the sleep offset to the timekeeping variables.
1684 static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1685 const struct timespec64 *delta)
1687 if (!timespec64_valid_strict(delta)) {
1688 printk_deferred(KERN_WARNING
1689 "__timekeeping_inject_sleeptime: Invalid "
1690 "sleep delta value!\n");
1693 tk_xtime_add(tk, delta);
1694 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1695 tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1696 tk_debug_account_sleep_time(delta);
1699 #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1701 * We have three kinds of time sources to use for sleep time
1702 * injection, the preference order is:
1703 * 1) non-stop clocksource
1704 * 2) persistent clock (ie: RTC accessible when irqs are off)
1707 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1708 * If system has neither 1) nor 2), 3) will be used finally.
1711 * If timekeeping has injected sleeptime via either 1) or 2),
1712 * 3) becomes needless, so in this case we don't need to call
1713 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1716 bool timekeeping_rtc_skipresume(void)
1718 return !suspend_timing_needed;
1722 * 1) can be determined whether to use or not only when doing
1723 * timekeeping_resume() which is invoked after rtc_suspend(),
1724 * so we can't skip rtc_suspend() surely if system has 1).
1726 * But if system has 2), 2) will definitely be used, so in this
1727 * case we don't need to call rtc_suspend(), and this is what
1728 * timekeeping_rtc_skipsuspend() means.
1730 bool timekeeping_rtc_skipsuspend(void)
1732 return persistent_clock_exists;
1736 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1737 * @delta: pointer to a timespec64 delta value
1739 * This hook is for architectures that cannot support read_persistent_clock64
1740 * because their RTC/persistent clock is only accessible when irqs are enabled.
1741 * and also don't have an effective nonstop clocksource.
1743 * This function should only be called by rtc_resume(), and allows
1744 * a suspend offset to be injected into the timekeeping values.
1746 void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
1748 struct timekeeper *tk = &tk_core.timekeeper;
1749 unsigned long flags;
1751 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1752 write_seqcount_begin(&tk_core.seq);
1754 suspend_timing_needed = false;
1756 timekeeping_forward_now(tk);
1758 __timekeeping_inject_sleeptime(tk, delta);
1760 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1762 write_seqcount_end(&tk_core.seq);
1763 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1765 /* Signal hrtimers about time change */
1766 clock_was_set(CLOCK_SET_WALL | CLOCK_SET_BOOT);
1771 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1773 void timekeeping_resume(void)
1775 struct timekeeper *tk = &tk_core.timekeeper;
1776 struct clocksource *clock = tk->tkr_mono.clock;
1777 unsigned long flags;
1778 struct timespec64 ts_new, ts_delta;
1779 u64 cycle_now, nsec;
1780 bool inject_sleeptime = false;
1782 read_persistent_clock64(&ts_new);
1784 clockevents_resume();
1785 clocksource_resume();
1787 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1788 write_seqcount_begin(&tk_core.seq);
1791 * After system resumes, we need to calculate the suspended time and
1792 * compensate it for the OS time. There are 3 sources that could be
1793 * used: Nonstop clocksource during suspend, persistent clock and rtc
1796 * One specific platform may have 1 or 2 or all of them, and the
1797 * preference will be:
1798 * suspend-nonstop clocksource -> persistent clock -> rtc
1799 * The less preferred source will only be tried if there is no better
1800 * usable source. The rtc part is handled separately in rtc core code.
1802 cycle_now = tk_clock_read(&tk->tkr_mono);
1803 nsec = clocksource_stop_suspend_timing(clock, cycle_now);
1805 ts_delta = ns_to_timespec64(nsec);
1806 inject_sleeptime = true;
1807 } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1808 ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1809 inject_sleeptime = true;
1812 if (inject_sleeptime) {
1813 suspend_timing_needed = false;
1814 __timekeeping_inject_sleeptime(tk, &ts_delta);
1817 /* Re-base the last cycle value */
1818 tk->tkr_mono.cycle_last = cycle_now;
1819 tk->tkr_raw.cycle_last = cycle_now;
1822 timekeeping_suspended = 0;
1823 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1824 write_seqcount_end(&tk_core.seq);
1825 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1827 touch_softlockup_watchdog();
1829 /* Resume the clockevent device(s) and hrtimers */
1831 /* Notify timerfd as resume is equivalent to clock_was_set() */
1835 int timekeeping_suspend(void)
1837 struct timekeeper *tk = &tk_core.timekeeper;
1838 unsigned long flags;
1839 struct timespec64 delta, delta_delta;
1840 static struct timespec64 old_delta;
1841 struct clocksource *curr_clock;
1844 read_persistent_clock64(&timekeeping_suspend_time);
1847 * On some systems the persistent_clock can not be detected at
1848 * timekeeping_init by its return value, so if we see a valid
1849 * value returned, update the persistent_clock_exists flag.
1851 if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1852 persistent_clock_exists = true;
1854 suspend_timing_needed = true;
1856 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1857 write_seqcount_begin(&tk_core.seq);
1858 timekeeping_forward_now(tk);
1859 timekeeping_suspended = 1;
1862 * Since we've called forward_now, cycle_last stores the value
1863 * just read from the current clocksource. Save this to potentially
1864 * use in suspend timing.
1866 curr_clock = tk->tkr_mono.clock;
1867 cycle_now = tk->tkr_mono.cycle_last;
1868 clocksource_start_suspend_timing(curr_clock, cycle_now);
1870 if (persistent_clock_exists) {
1872 * To avoid drift caused by repeated suspend/resumes,
1873 * which each can add ~1 second drift error,
1874 * try to compensate so the difference in system time
1875 * and persistent_clock time stays close to constant.
1877 delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1878 delta_delta = timespec64_sub(delta, old_delta);
1879 if (abs(delta_delta.tv_sec) >= 2) {
1881 * if delta_delta is too large, assume time correction
1882 * has occurred and set old_delta to the current delta.
1886 /* Otherwise try to adjust old_system to compensate */
1887 timekeeping_suspend_time =
1888 timespec64_add(timekeeping_suspend_time, delta_delta);
1892 timekeeping_update(tk, TK_MIRROR);
1893 halt_fast_timekeeper(tk);
1894 write_seqcount_end(&tk_core.seq);
1895 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1898 clocksource_suspend();
1899 clockevents_suspend();
1904 /* sysfs resume/suspend bits for timekeeping */
1905 static struct syscore_ops timekeeping_syscore_ops = {
1906 .resume = timekeeping_resume,
1907 .suspend = timekeeping_suspend,
1910 static int __init timekeeping_init_ops(void)
1912 register_syscore_ops(&timekeeping_syscore_ops);
1915 device_initcall(timekeeping_init_ops);
1918 * Apply a multiplier adjustment to the timekeeper
1920 static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1924 s64 interval = tk->cycle_interval;
1926 if (mult_adj == 0) {
1928 } else if (mult_adj == -1) {
1929 interval = -interval;
1931 } else if (mult_adj != 1) {
1932 interval *= mult_adj;
1937 * So the following can be confusing.
1939 * To keep things simple, lets assume mult_adj == 1 for now.
1941 * When mult_adj != 1, remember that the interval and offset values
1942 * have been appropriately scaled so the math is the same.
1944 * The basic idea here is that we're increasing the multiplier
1945 * by one, this causes the xtime_interval to be incremented by
1946 * one cycle_interval. This is because:
1947 * xtime_interval = cycle_interval * mult
1948 * So if mult is being incremented by one:
1949 * xtime_interval = cycle_interval * (mult + 1)
1951 * xtime_interval = (cycle_interval * mult) + cycle_interval
1952 * Which can be shortened to:
1953 * xtime_interval += cycle_interval
1955 * So offset stores the non-accumulated cycles. Thus the current
1956 * time (in shifted nanoseconds) is:
1957 * now = (offset * adj) + xtime_nsec
1958 * Now, even though we're adjusting the clock frequency, we have
1959 * to keep time consistent. In other words, we can't jump back
1960 * in time, and we also want to avoid jumping forward in time.
1962 * So given the same offset value, we need the time to be the same
1963 * both before and after the freq adjustment.
1964 * now = (offset * adj_1) + xtime_nsec_1
1965 * now = (offset * adj_2) + xtime_nsec_2
1967 * (offset * adj_1) + xtime_nsec_1 =
1968 * (offset * adj_2) + xtime_nsec_2
1972 * (offset * adj_1) + xtime_nsec_1 =
1973 * (offset * (adj_1+1)) + xtime_nsec_2
1974 * (offset * adj_1) + xtime_nsec_1 =
1975 * (offset * adj_1) + offset + xtime_nsec_2
1976 * Canceling the sides:
1977 * xtime_nsec_1 = offset + xtime_nsec_2
1979 * xtime_nsec_2 = xtime_nsec_1 - offset
1980 * Which simplifies to:
1981 * xtime_nsec -= offset
1983 if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1984 /* NTP adjustment caused clocksource mult overflow */
1989 tk->tkr_mono.mult += mult_adj;
1990 tk->xtime_interval += interval;
1991 tk->tkr_mono.xtime_nsec -= offset;
1995 * Adjust the timekeeper's multiplier to the correct frequency
1996 * and also to reduce the accumulated error value.
1998 static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
2003 * Determine the multiplier from the current NTP tick length.
2004 * Avoid expensive division when the tick length doesn't change.
2006 if (likely(tk->ntp_tick == ntp_tick_length())) {
2007 mult = tk->tkr_mono.mult - tk->ntp_err_mult;
2009 tk->ntp_tick = ntp_tick_length();
2010 mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) -
2011 tk->xtime_remainder, tk->cycle_interval);
2015 * If the clock is behind the NTP time, increase the multiplier by 1
2016 * to catch up with it. If it's ahead and there was a remainder in the
2017 * tick division, the clock will slow down. Otherwise it will stay
2018 * ahead until the tick length changes to a non-divisible value.
2020 tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0;
2021 mult += tk->ntp_err_mult;
2023 timekeeping_apply_adjustment(tk, offset, mult - tk->tkr_mono.mult);
2025 if (unlikely(tk->tkr_mono.clock->maxadj &&
2026 (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
2027 > tk->tkr_mono.clock->maxadj))) {
2028 printk_once(KERN_WARNING
2029 "Adjusting %s more than 11%% (%ld vs %ld)\n",
2030 tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
2031 (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
2035 * It may be possible that when we entered this function, xtime_nsec
2036 * was very small. Further, if we're slightly speeding the clocksource
2037 * in the code above, its possible the required corrective factor to
2038 * xtime_nsec could cause it to underflow.
2040 * Now, since we have already accumulated the second and the NTP
2041 * subsystem has been notified via second_overflow(), we need to skip
2044 if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
2045 tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC <<
2048 tk->skip_second_overflow = 1;
2053 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
2055 * Helper function that accumulates the nsecs greater than a second
2056 * from the xtime_nsec field to the xtime_secs field.
2057 * It also calls into the NTP code to handle leapsecond processing.
2059 static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
2061 u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
2062 unsigned int clock_set = 0;
2064 while (tk->tkr_mono.xtime_nsec >= nsecps) {
2067 tk->tkr_mono.xtime_nsec -= nsecps;
2071 * Skip NTP update if this second was accumulated before,
2072 * i.e. xtime_nsec underflowed in timekeeping_adjust()
2074 if (unlikely(tk->skip_second_overflow)) {
2075 tk->skip_second_overflow = 0;
2079 /* Figure out if its a leap sec and apply if needed */
2080 leap = second_overflow(tk->xtime_sec);
2081 if (unlikely(leap)) {
2082 struct timespec64 ts;
2084 tk->xtime_sec += leap;
2088 tk_set_wall_to_mono(tk,
2089 timespec64_sub(tk->wall_to_monotonic, ts));
2091 __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
2093 clock_set = TK_CLOCK_WAS_SET;
2100 * logarithmic_accumulation - shifted accumulation of cycles
2102 * This functions accumulates a shifted interval of cycles into
2103 * a shifted interval nanoseconds. Allows for O(log) accumulation
2106 * Returns the unconsumed cycles.
2108 static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2109 u32 shift, unsigned int *clock_set)
2111 u64 interval = tk->cycle_interval << shift;
2114 /* If the offset is smaller than a shifted interval, do nothing */
2115 if (offset < interval)
2118 /* Accumulate one shifted interval */
2120 tk->tkr_mono.cycle_last += interval;
2121 tk->tkr_raw.cycle_last += interval;
2123 tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2124 *clock_set |= accumulate_nsecs_to_secs(tk);
2126 /* Accumulate raw time */
2127 tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2128 snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2129 while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2130 tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2134 /* Accumulate error between NTP and clock interval */
2135 tk->ntp_error += tk->ntp_tick << shift;
2136 tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2137 (tk->ntp_error_shift + shift);
2143 * timekeeping_advance - Updates the timekeeper to the current time and
2144 * current NTP tick length
2146 static bool timekeeping_advance(enum timekeeping_adv_mode mode)
2148 struct timekeeper *real_tk = &tk_core.timekeeper;
2149 struct timekeeper *tk = &shadow_timekeeper;
2151 int shift = 0, maxshift;
2152 unsigned int clock_set = 0;
2153 unsigned long flags;
2155 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2157 /* Make sure we're fully resumed: */
2158 if (unlikely(timekeeping_suspended))
2161 offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
2162 tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2164 /* Check if there's really nothing to do */
2165 if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK)
2168 /* Do some additional sanity checking */
2169 timekeeping_check_update(tk, offset);
2172 * With NO_HZ we may have to accumulate many cycle_intervals
2173 * (think "ticks") worth of time at once. To do this efficiently,
2174 * we calculate the largest doubling multiple of cycle_intervals
2175 * that is smaller than the offset. We then accumulate that
2176 * chunk in one go, and then try to consume the next smaller
2179 shift = ilog2(offset) - ilog2(tk->cycle_interval);
2180 shift = max(0, shift);
2181 /* Bound shift to one less than what overflows tick_length */
2182 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2183 shift = min(shift, maxshift);
2184 while (offset >= tk->cycle_interval) {
2185 offset = logarithmic_accumulation(tk, offset, shift,
2187 if (offset < tk->cycle_interval<<shift)
2191 /* Adjust the multiplier to correct NTP error */
2192 timekeeping_adjust(tk, offset);
2195 * Finally, make sure that after the rounding
2196 * xtime_nsec isn't larger than NSEC_PER_SEC
2198 clock_set |= accumulate_nsecs_to_secs(tk);
2200 write_seqcount_begin(&tk_core.seq);
2202 * Update the real timekeeper.
2204 * We could avoid this memcpy by switching pointers, but that
2205 * requires changes to all other timekeeper usage sites as
2206 * well, i.e. move the timekeeper pointer getter into the
2207 * spinlocked/seqcount protected sections. And we trade this
2208 * memcpy under the tk_core.seq against one before we start
2211 timekeeping_update(tk, clock_set);
2212 memcpy(real_tk, tk, sizeof(*tk));
2213 /* The memcpy must come last. Do not put anything here! */
2214 write_seqcount_end(&tk_core.seq);
2216 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2222 * update_wall_time - Uses the current clocksource to increment the wall time
2225 void update_wall_time(void)
2227 if (timekeeping_advance(TK_ADV_TICK))
2228 clock_was_set_delayed();
2232 * getboottime64 - Return the real time of system boot.
2233 * @ts: pointer to the timespec64 to be set
2235 * Returns the wall-time of boot in a timespec64.
2237 * This is based on the wall_to_monotonic offset and the total suspend
2238 * time. Calls to settimeofday will affect the value returned (which
2239 * basically means that however wrong your real time clock is at boot time,
2240 * you get the right time here).
2242 void getboottime64(struct timespec64 *ts)
2244 struct timekeeper *tk = &tk_core.timekeeper;
2245 ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2247 *ts = ktime_to_timespec64(t);
2249 EXPORT_SYMBOL_GPL(getboottime64);
2251 void ktime_get_coarse_real_ts64(struct timespec64 *ts)
2253 struct timekeeper *tk = &tk_core.timekeeper;
2257 seq = read_seqcount_begin(&tk_core.seq);
2260 } while (read_seqcount_retry(&tk_core.seq, seq));
2262 EXPORT_SYMBOL(ktime_get_coarse_real_ts64);
2264 void ktime_get_coarse_ts64(struct timespec64 *ts)
2266 struct timekeeper *tk = &tk_core.timekeeper;
2267 struct timespec64 now, mono;
2271 seq = read_seqcount_begin(&tk_core.seq);
2274 mono = tk->wall_to_monotonic;
2275 } while (read_seqcount_retry(&tk_core.seq, seq));
2277 set_normalized_timespec64(ts, now.tv_sec + mono.tv_sec,
2278 now.tv_nsec + mono.tv_nsec);
2280 EXPORT_SYMBOL(ktime_get_coarse_ts64);
2283 * Must hold jiffies_lock
2285 void do_timer(unsigned long ticks)
2287 jiffies_64 += ticks;
2292 * ktime_get_update_offsets_now - hrtimer helper
2293 * @cwsseq: pointer to check and store the clock was set sequence number
2294 * @offs_real: pointer to storage for monotonic -> realtime offset
2295 * @offs_boot: pointer to storage for monotonic -> boottime offset
2296 * @offs_tai: pointer to storage for monotonic -> clock tai offset
2298 * Returns current monotonic time and updates the offsets if the
2299 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2302 * Called from hrtimer_interrupt() or retrigger_next_event()
2304 ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2305 ktime_t *offs_boot, ktime_t *offs_tai)
2307 struct timekeeper *tk = &tk_core.timekeeper;
2313 seq = read_seqcount_begin(&tk_core.seq);
2315 base = tk->tkr_mono.base;
2316 nsecs = timekeeping_get_ns(&tk->tkr_mono);
2317 base = ktime_add_ns(base, nsecs);
2319 if (*cwsseq != tk->clock_was_set_seq) {
2320 *cwsseq = tk->clock_was_set_seq;
2321 *offs_real = tk->offs_real;
2322 *offs_boot = tk->offs_boot;
2323 *offs_tai = tk->offs_tai;
2326 /* Handle leapsecond insertion adjustments */
2327 if (unlikely(base >= tk->next_leap_ktime))
2328 *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2330 } while (read_seqcount_retry(&tk_core.seq, seq));
2336 * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2338 static int timekeeping_validate_timex(const struct __kernel_timex *txc)
2340 if (txc->modes & ADJ_ADJTIME) {
2341 /* singleshot must not be used with any other mode bits */
2342 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2344 if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2345 !capable(CAP_SYS_TIME))
2348 /* In order to modify anything, you gotta be super-user! */
2349 if (txc->modes && !capable(CAP_SYS_TIME))
2352 * if the quartz is off by more than 10% then
2353 * something is VERY wrong!
2355 if (txc->modes & ADJ_TICK &&
2356 (txc->tick < 900000/USER_HZ ||
2357 txc->tick > 1100000/USER_HZ))
2361 if (txc->modes & ADJ_SETOFFSET) {
2362 /* In order to inject time, you gotta be super-user! */
2363 if (!capable(CAP_SYS_TIME))
2367 * Validate if a timespec/timeval used to inject a time
2368 * offset is valid. Offsets can be positive or negative, so
2369 * we don't check tv_sec. The value of the timeval/timespec
2370 * is the sum of its fields,but *NOTE*:
2371 * The field tv_usec/tv_nsec must always be non-negative and
2372 * we can't have more nanoseconds/microseconds than a second.
2374 if (txc->time.tv_usec < 0)
2377 if (txc->modes & ADJ_NANO) {
2378 if (txc->time.tv_usec >= NSEC_PER_SEC)
2381 if (txc->time.tv_usec >= USEC_PER_SEC)
2387 * Check for potential multiplication overflows that can
2388 * only happen on 64-bit systems:
2390 if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2391 if (LLONG_MIN / PPM_SCALE > txc->freq)
2393 if (LLONG_MAX / PPM_SCALE < txc->freq)
2402 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2404 int do_adjtimex(struct __kernel_timex *txc)
2406 struct timekeeper *tk = &tk_core.timekeeper;
2407 struct audit_ntp_data ad;
2408 bool clock_set = false;
2409 struct timespec64 ts;
2410 unsigned long flags;
2414 /* Validate the data before disabling interrupts */
2415 ret = timekeeping_validate_timex(txc);
2419 if (txc->modes & ADJ_SETOFFSET) {
2420 struct timespec64 delta;
2421 delta.tv_sec = txc->time.tv_sec;
2422 delta.tv_nsec = txc->time.tv_usec;
2423 if (!(txc->modes & ADJ_NANO))
2424 delta.tv_nsec *= 1000;
2425 ret = timekeeping_inject_offset(&delta);
2429 audit_tk_injoffset(delta);
2432 audit_ntp_init(&ad);
2434 ktime_get_real_ts64(&ts);
2436 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2437 write_seqcount_begin(&tk_core.seq);
2439 orig_tai = tai = tk->tai_offset;
2440 ret = __do_adjtimex(txc, &ts, &tai, &ad);
2442 if (tai != orig_tai) {
2443 __timekeeping_set_tai_offset(tk, tai);
2444 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2447 tk_update_leap_state(tk);
2449 write_seqcount_end(&tk_core.seq);
2450 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2454 /* Update the multiplier immediately if frequency was set directly */
2455 if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
2456 clock_set |= timekeeping_advance(TK_ADV_FREQ);
2459 clock_was_set(CLOCK_REALTIME);
2461 ntp_notify_cmos_timer();
2466 #ifdef CONFIG_NTP_PPS
2468 * hardpps() - Accessor function to NTP __hardpps function
2470 void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2472 unsigned long flags;
2474 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2475 write_seqcount_begin(&tk_core.seq);
2477 __hardpps(phase_ts, raw_ts);
2479 write_seqcount_end(&tk_core.seq);
2480 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2482 EXPORT_SYMBOL(hardpps);
2483 #endif /* CONFIG_NTP_PPS */