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(tk->offs_boot));
533 EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
535 static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono)
537 struct tk_read_base *tkr;
538 u64 basem, baser, delta;
542 seq = raw_read_seqcount_latch(&tkf->seq);
543 tkr = tkf->base + (seq & 0x01);
544 basem = ktime_to_ns(tkr->base);
545 baser = ktime_to_ns(tkr->base_real);
547 delta = timekeeping_delta_to_ns(tkr,
548 clocksource_delta(tk_clock_read(tkr),
549 tkr->cycle_last, tkr->mask));
550 } while (read_seqcount_latch_retry(&tkf->seq, seq));
553 *mono = basem + delta;
554 return baser + delta;
558 * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime.
560 * See ktime_get_fast_ns() for documentation of the time stamp ordering.
562 u64 ktime_get_real_fast_ns(void)
564 return __ktime_get_real_fast(&tk_fast_mono, NULL);
566 EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns);
569 * ktime_get_fast_timestamps: - NMI safe timestamps
570 * @snapshot: Pointer to timestamp storage
572 * Stores clock monotonic, boottime and realtime timestamps.
574 * Boot time is a racy access on 32bit systems if the sleep time injection
575 * happens late during resume and not in timekeeping_resume(). That could
576 * be avoided by expanding struct tk_read_base with boot offset for 32bit
577 * and adding more overhead to the update. As this is a hard to observe
578 * once per resume event which can be filtered with reasonable effort using
579 * the accurate mono/real timestamps, it's probably not worth the trouble.
581 * Aside of that it might be possible on 32 and 64 bit to observe the
582 * following when the sleep time injection happens late:
585 * timekeeping_resume()
586 * ktime_get_fast_timestamps()
587 * mono, real = __ktime_get_real_fast()
588 * inject_sleep_time()
590 * boot = mono + bootoffset;
592 * That means that boot time already has the sleep time adjustment, but
593 * real time does not. On the next readout both are in sync again.
595 * Preventing this for 64bit is not really feasible without destroying the
596 * careful cache layout of the timekeeper because the sequence count and
597 * struct tk_read_base would then need two cache lines instead of one.
599 * Access to the time keeper clock source is disabled across the innermost
600 * steps of suspend/resume. The accessors still work, but the timestamps
601 * are frozen until time keeping is resumed which happens very early.
603 * For regular suspend/resume there is no observable difference vs. sched
604 * clock, but it might affect some of the nasty low level debug printks.
606 * OTOH, access to sched clock is not guaranteed across suspend/resume on
607 * all systems either so it depends on the hardware in use.
609 * If that turns out to be a real problem then this could be mitigated by
610 * using sched clock in a similar way as during early boot. But it's not as
611 * trivial as on early boot because it needs some careful protection
612 * against the clock monotonic timestamp jumping backwards on resume.
614 void ktime_get_fast_timestamps(struct ktime_timestamps *snapshot)
616 struct timekeeper *tk = &tk_core.timekeeper;
618 snapshot->real = __ktime_get_real_fast(&tk_fast_mono, &snapshot->mono);
619 snapshot->boot = snapshot->mono + ktime_to_ns(data_race(tk->offs_boot));
623 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
624 * @tk: Timekeeper to snapshot.
626 * It generally is unsafe to access the clocksource after timekeeping has been
627 * suspended, so take a snapshot of the readout base of @tk and use it as the
628 * fast timekeeper's readout base while suspended. It will return the same
629 * number of cycles every time until timekeeping is resumed at which time the
630 * proper readout base for the fast timekeeper will be restored automatically.
632 static void halt_fast_timekeeper(const struct timekeeper *tk)
634 static struct tk_read_base tkr_dummy;
635 const struct tk_read_base *tkr = &tk->tkr_mono;
637 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
638 cycles_at_suspend = tk_clock_read(tkr);
639 tkr_dummy.clock = &dummy_clock;
640 tkr_dummy.base_real = tkr->base + tk->offs_real;
641 update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
644 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
645 tkr_dummy.clock = &dummy_clock;
646 update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
649 static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
651 static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
653 raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
657 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
658 * @nb: Pointer to the notifier block to register
660 int pvclock_gtod_register_notifier(struct notifier_block *nb)
662 struct timekeeper *tk = &tk_core.timekeeper;
666 raw_spin_lock_irqsave(&timekeeper_lock, flags);
667 ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
668 update_pvclock_gtod(tk, true);
669 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
673 EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
676 * pvclock_gtod_unregister_notifier - unregister a pvclock
677 * timedata update listener
678 * @nb: Pointer to the notifier block to unregister
680 int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
685 raw_spin_lock_irqsave(&timekeeper_lock, flags);
686 ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
687 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
691 EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
694 * tk_update_leap_state - helper to update the next_leap_ktime
696 static inline void tk_update_leap_state(struct timekeeper *tk)
698 tk->next_leap_ktime = ntp_get_next_leap();
699 if (tk->next_leap_ktime != KTIME_MAX)
700 /* Convert to monotonic time */
701 tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
705 * Update the ktime_t based scalar nsec members of the timekeeper
707 static inline void tk_update_ktime_data(struct timekeeper *tk)
713 * The xtime based monotonic readout is:
714 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
715 * The ktime based monotonic readout is:
716 * nsec = base_mono + now();
717 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
719 seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
720 nsec = (u32) tk->wall_to_monotonic.tv_nsec;
721 tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
724 * The sum of the nanoseconds portions of xtime and
725 * wall_to_monotonic can be greater/equal one second. Take
726 * this into account before updating tk->ktime_sec.
728 nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
729 if (nsec >= NSEC_PER_SEC)
731 tk->ktime_sec = seconds;
733 /* Update the monotonic raw base */
734 tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
737 /* must hold timekeeper_lock */
738 static void timekeeping_update(struct timekeeper *tk, unsigned int action)
740 if (action & TK_CLEAR_NTP) {
745 tk_update_leap_state(tk);
746 tk_update_ktime_data(tk);
749 update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
751 tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
752 update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
753 update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
755 if (action & TK_CLOCK_WAS_SET)
756 tk->clock_was_set_seq++;
758 * The mirroring of the data to the shadow-timekeeper needs
759 * to happen last here to ensure we don't over-write the
760 * timekeeper structure on the next update with stale data
762 if (action & TK_MIRROR)
763 memcpy(&shadow_timekeeper, &tk_core.timekeeper,
764 sizeof(tk_core.timekeeper));
768 * timekeeping_forward_now - update clock to the current time
769 * @tk: Pointer to the timekeeper to update
771 * Forward the current clock to update its state since the last call to
772 * update_wall_time(). This is useful before significant clock changes,
773 * as it avoids having to deal with this time offset explicitly.
775 static void timekeeping_forward_now(struct timekeeper *tk)
777 u64 cycle_now, delta;
779 cycle_now = tk_clock_read(&tk->tkr_mono);
780 delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
781 tk->tkr_mono.cycle_last = cycle_now;
782 tk->tkr_raw.cycle_last = cycle_now;
784 tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
785 tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
787 tk_normalize_xtime(tk);
791 * ktime_get_real_ts64 - Returns the time of day in a timespec64.
792 * @ts: pointer to the timespec to be set
794 * Returns the time of day in a timespec64 (WARN if suspended).
796 void ktime_get_real_ts64(struct timespec64 *ts)
798 struct timekeeper *tk = &tk_core.timekeeper;
802 WARN_ON(timekeeping_suspended);
805 seq = read_seqcount_begin(&tk_core.seq);
807 ts->tv_sec = tk->xtime_sec;
808 nsecs = timekeeping_get_ns(&tk->tkr_mono);
810 } while (read_seqcount_retry(&tk_core.seq, seq));
813 timespec64_add_ns(ts, nsecs);
815 EXPORT_SYMBOL(ktime_get_real_ts64);
817 ktime_t ktime_get(void)
819 struct timekeeper *tk = &tk_core.timekeeper;
824 WARN_ON(timekeeping_suspended);
827 seq = read_seqcount_begin(&tk_core.seq);
828 base = tk->tkr_mono.base;
829 nsecs = timekeeping_get_ns(&tk->tkr_mono);
831 } while (read_seqcount_retry(&tk_core.seq, seq));
833 return ktime_add_ns(base, nsecs);
835 EXPORT_SYMBOL_GPL(ktime_get);
837 u32 ktime_get_resolution_ns(void)
839 struct timekeeper *tk = &tk_core.timekeeper;
843 WARN_ON(timekeeping_suspended);
846 seq = read_seqcount_begin(&tk_core.seq);
847 nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
848 } while (read_seqcount_retry(&tk_core.seq, seq));
852 EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
854 static ktime_t *offsets[TK_OFFS_MAX] = {
855 [TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
856 [TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
857 [TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai,
860 ktime_t ktime_get_with_offset(enum tk_offsets offs)
862 struct timekeeper *tk = &tk_core.timekeeper;
864 ktime_t base, *offset = offsets[offs];
867 WARN_ON(timekeeping_suspended);
870 seq = read_seqcount_begin(&tk_core.seq);
871 base = ktime_add(tk->tkr_mono.base, *offset);
872 nsecs = timekeeping_get_ns(&tk->tkr_mono);
874 } while (read_seqcount_retry(&tk_core.seq, seq));
876 return ktime_add_ns(base, nsecs);
879 EXPORT_SYMBOL_GPL(ktime_get_with_offset);
881 ktime_t ktime_get_coarse_with_offset(enum tk_offsets offs)
883 struct timekeeper *tk = &tk_core.timekeeper;
885 ktime_t base, *offset = offsets[offs];
888 WARN_ON(timekeeping_suspended);
891 seq = read_seqcount_begin(&tk_core.seq);
892 base = ktime_add(tk->tkr_mono.base, *offset);
893 nsecs = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
895 } while (read_seqcount_retry(&tk_core.seq, seq));
897 return ktime_add_ns(base, nsecs);
899 EXPORT_SYMBOL_GPL(ktime_get_coarse_with_offset);
902 * ktime_mono_to_any() - convert monotonic time to any other time
903 * @tmono: time to convert.
904 * @offs: which offset to use
906 ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
908 ktime_t *offset = offsets[offs];
913 seq = read_seqcount_begin(&tk_core.seq);
914 tconv = ktime_add(tmono, *offset);
915 } while (read_seqcount_retry(&tk_core.seq, seq));
919 EXPORT_SYMBOL_GPL(ktime_mono_to_any);
922 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
924 ktime_t ktime_get_raw(void)
926 struct timekeeper *tk = &tk_core.timekeeper;
932 seq = read_seqcount_begin(&tk_core.seq);
933 base = tk->tkr_raw.base;
934 nsecs = timekeeping_get_ns(&tk->tkr_raw);
936 } while (read_seqcount_retry(&tk_core.seq, seq));
938 return ktime_add_ns(base, nsecs);
940 EXPORT_SYMBOL_GPL(ktime_get_raw);
943 * ktime_get_ts64 - get the monotonic clock in timespec64 format
944 * @ts: pointer to timespec variable
946 * The function calculates the monotonic clock from the realtime
947 * clock and the wall_to_monotonic offset and stores the result
948 * in normalized timespec64 format in the variable pointed to by @ts.
950 void ktime_get_ts64(struct timespec64 *ts)
952 struct timekeeper *tk = &tk_core.timekeeper;
953 struct timespec64 tomono;
957 WARN_ON(timekeeping_suspended);
960 seq = read_seqcount_begin(&tk_core.seq);
961 ts->tv_sec = tk->xtime_sec;
962 nsec = timekeeping_get_ns(&tk->tkr_mono);
963 tomono = tk->wall_to_monotonic;
965 } while (read_seqcount_retry(&tk_core.seq, seq));
967 ts->tv_sec += tomono.tv_sec;
969 timespec64_add_ns(ts, nsec + tomono.tv_nsec);
971 EXPORT_SYMBOL_GPL(ktime_get_ts64);
974 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
976 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
977 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
978 * works on both 32 and 64 bit systems. On 32 bit systems the readout
979 * covers ~136 years of uptime which should be enough to prevent
980 * premature wrap arounds.
982 time64_t ktime_get_seconds(void)
984 struct timekeeper *tk = &tk_core.timekeeper;
986 WARN_ON(timekeeping_suspended);
987 return tk->ktime_sec;
989 EXPORT_SYMBOL_GPL(ktime_get_seconds);
992 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
994 * Returns the wall clock seconds since 1970.
996 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
997 * 32bit systems the access must be protected with the sequence
998 * counter to provide "atomic" access to the 64bit tk->xtime_sec
1001 time64_t ktime_get_real_seconds(void)
1003 struct timekeeper *tk = &tk_core.timekeeper;
1007 if (IS_ENABLED(CONFIG_64BIT))
1008 return tk->xtime_sec;
1011 seq = read_seqcount_begin(&tk_core.seq);
1012 seconds = tk->xtime_sec;
1014 } while (read_seqcount_retry(&tk_core.seq, seq));
1018 EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
1021 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
1022 * but without the sequence counter protect. This internal function
1023 * is called just when timekeeping lock is already held.
1025 noinstr time64_t __ktime_get_real_seconds(void)
1027 struct timekeeper *tk = &tk_core.timekeeper;
1029 return tk->xtime_sec;
1033 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
1034 * @systime_snapshot: pointer to struct receiving the system time snapshot
1036 void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
1038 struct timekeeper *tk = &tk_core.timekeeper;
1046 WARN_ON_ONCE(timekeeping_suspended);
1049 seq = read_seqcount_begin(&tk_core.seq);
1050 now = tk_clock_read(&tk->tkr_mono);
1051 systime_snapshot->cs_id = tk->tkr_mono.clock->id;
1052 systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
1053 systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
1054 base_real = ktime_add(tk->tkr_mono.base,
1055 tk_core.timekeeper.offs_real);
1056 base_raw = tk->tkr_raw.base;
1057 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
1058 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
1059 } while (read_seqcount_retry(&tk_core.seq, seq));
1061 systime_snapshot->cycles = now;
1062 systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
1063 systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
1065 EXPORT_SYMBOL_GPL(ktime_get_snapshot);
1067 /* Scale base by mult/div checking for overflow */
1068 static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
1072 tmp = div64_u64_rem(*base, div, &rem);
1074 if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
1075 ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
1079 rem = div64_u64(rem * mult, div);
1085 * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
1086 * @history: Snapshot representing start of history
1087 * @partial_history_cycles: Cycle offset into history (fractional part)
1088 * @total_history_cycles: Total history length in cycles
1089 * @discontinuity: True indicates clock was set on history period
1090 * @ts: Cross timestamp that should be adjusted using
1091 * partial/total ratio
1093 * Helper function used by get_device_system_crosststamp() to correct the
1094 * crosstimestamp corresponding to the start of the current interval to the
1095 * system counter value (timestamp point) provided by the driver. The
1096 * total_history_* quantities are the total history starting at the provided
1097 * reference point and ending at the start of the current interval. The cycle
1098 * count between the driver timestamp point and the start of the current
1099 * interval is partial_history_cycles.
1101 static int adjust_historical_crosststamp(struct system_time_snapshot *history,
1102 u64 partial_history_cycles,
1103 u64 total_history_cycles,
1105 struct system_device_crosststamp *ts)
1107 struct timekeeper *tk = &tk_core.timekeeper;
1108 u64 corr_raw, corr_real;
1109 bool interp_forward;
1112 if (total_history_cycles == 0 || partial_history_cycles == 0)
1115 /* Interpolate shortest distance from beginning or end of history */
1116 interp_forward = partial_history_cycles > total_history_cycles / 2;
1117 partial_history_cycles = interp_forward ?
1118 total_history_cycles - partial_history_cycles :
1119 partial_history_cycles;
1122 * Scale the monotonic raw time delta by:
1123 * partial_history_cycles / total_history_cycles
1125 corr_raw = (u64)ktime_to_ns(
1126 ktime_sub(ts->sys_monoraw, history->raw));
1127 ret = scale64_check_overflow(partial_history_cycles,
1128 total_history_cycles, &corr_raw);
1133 * If there is a discontinuity in the history, scale monotonic raw
1135 * mult(real)/mult(raw) yielding the realtime correction
1136 * Otherwise, calculate the realtime correction similar to monotonic
1139 if (discontinuity) {
1140 corr_real = mul_u64_u32_div
1141 (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1143 corr_real = (u64)ktime_to_ns(
1144 ktime_sub(ts->sys_realtime, history->real));
1145 ret = scale64_check_overflow(partial_history_cycles,
1146 total_history_cycles, &corr_real);
1151 /* Fixup monotonic raw and real time time values */
1152 if (interp_forward) {
1153 ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1154 ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1156 ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1157 ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1164 * cycle_between - true if test occurs chronologically between before and after
1166 static bool cycle_between(u64 before, u64 test, u64 after)
1168 if (test > before && test < after)
1170 if (test < before && before > after)
1176 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1177 * @get_time_fn: Callback to get simultaneous device time and
1178 * system counter from the device driver
1179 * @ctx: Context passed to get_time_fn()
1180 * @history_begin: Historical reference point used to interpolate system
1181 * time when counter provided by the driver is before the current interval
1182 * @xtstamp: Receives simultaneously captured system and device time
1184 * Reads a timestamp from a device and correlates it to system time
1186 int get_device_system_crosststamp(int (*get_time_fn)
1187 (ktime_t *device_time,
1188 struct system_counterval_t *sys_counterval,
1191 struct system_time_snapshot *history_begin,
1192 struct system_device_crosststamp *xtstamp)
1194 struct system_counterval_t system_counterval;
1195 struct timekeeper *tk = &tk_core.timekeeper;
1196 u64 cycles, now, interval_start;
1197 unsigned int clock_was_set_seq = 0;
1198 ktime_t base_real, base_raw;
1199 u64 nsec_real, nsec_raw;
1200 u8 cs_was_changed_seq;
1206 seq = read_seqcount_begin(&tk_core.seq);
1208 * Try to synchronously capture device time and a system
1209 * counter value calling back into the device driver
1211 ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1216 * Verify that the clocksource associated with the captured
1217 * system counter value is the same as the currently installed
1218 * timekeeper clocksource
1220 if (tk->tkr_mono.clock != system_counterval.cs)
1222 cycles = system_counterval.cycles;
1225 * Check whether the system counter value provided by the
1226 * device driver is on the current timekeeping interval.
1228 now = tk_clock_read(&tk->tkr_mono);
1229 interval_start = tk->tkr_mono.cycle_last;
1230 if (!cycle_between(interval_start, cycles, now)) {
1231 clock_was_set_seq = tk->clock_was_set_seq;
1232 cs_was_changed_seq = tk->cs_was_changed_seq;
1233 cycles = interval_start;
1239 base_real = ktime_add(tk->tkr_mono.base,
1240 tk_core.timekeeper.offs_real);
1241 base_raw = tk->tkr_raw.base;
1243 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1244 system_counterval.cycles);
1245 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1246 system_counterval.cycles);
1247 } while (read_seqcount_retry(&tk_core.seq, seq));
1249 xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1250 xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1253 * Interpolate if necessary, adjusting back from the start of the
1257 u64 partial_history_cycles, total_history_cycles;
1261 * Check that the counter value occurs after the provided
1262 * history reference and that the history doesn't cross a
1263 * clocksource change
1265 if (!history_begin ||
1266 !cycle_between(history_begin->cycles,
1267 system_counterval.cycles, cycles) ||
1268 history_begin->cs_was_changed_seq != cs_was_changed_seq)
1270 partial_history_cycles = cycles - system_counterval.cycles;
1271 total_history_cycles = cycles - history_begin->cycles;
1273 history_begin->clock_was_set_seq != clock_was_set_seq;
1275 ret = adjust_historical_crosststamp(history_begin,
1276 partial_history_cycles,
1277 total_history_cycles,
1278 discontinuity, xtstamp);
1285 EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1288 * do_settimeofday64 - Sets the time of day.
1289 * @ts: pointer to the timespec64 variable containing the new time
1291 * Sets the time of day to the new time and update NTP and notify hrtimers
1293 int do_settimeofday64(const struct timespec64 *ts)
1295 struct timekeeper *tk = &tk_core.timekeeper;
1296 struct timespec64 ts_delta, xt;
1297 unsigned long flags;
1300 if (!timespec64_valid_settod(ts))
1303 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1304 write_seqcount_begin(&tk_core.seq);
1306 timekeeping_forward_now(tk);
1309 ts_delta.tv_sec = ts->tv_sec - xt.tv_sec;
1310 ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec;
1312 if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1317 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1319 tk_set_xtime(tk, ts);
1321 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1323 write_seqcount_end(&tk_core.seq);
1324 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1326 /* signal hrtimers about time change */
1330 audit_tk_injoffset(ts_delta);
1334 EXPORT_SYMBOL(do_settimeofday64);
1337 * timekeeping_inject_offset - Adds or subtracts from the current time.
1338 * @ts: Pointer to the timespec variable containing the offset
1340 * Adds or subtracts an offset value from the current time.
1342 static int timekeeping_inject_offset(const struct timespec64 *ts)
1344 struct timekeeper *tk = &tk_core.timekeeper;
1345 unsigned long flags;
1346 struct timespec64 tmp;
1349 if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
1352 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1353 write_seqcount_begin(&tk_core.seq);
1355 timekeeping_forward_now(tk);
1357 /* Make sure the proposed value is valid */
1358 tmp = timespec64_add(tk_xtime(tk), *ts);
1359 if (timespec64_compare(&tk->wall_to_monotonic, ts) > 0 ||
1360 !timespec64_valid_settod(&tmp)) {
1365 tk_xtime_add(tk, ts);
1366 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *ts));
1368 error: /* even if we error out, we forwarded the time, so call update */
1369 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1371 write_seqcount_end(&tk_core.seq);
1372 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1374 /* signal hrtimers about time change */
1381 * Indicates if there is an offset between the system clock and the hardware
1382 * clock/persistent clock/rtc.
1384 int persistent_clock_is_local;
1387 * Adjust the time obtained from the CMOS to be UTC time instead of
1390 * This is ugly, but preferable to the alternatives. Otherwise we
1391 * would either need to write a program to do it in /etc/rc (and risk
1392 * confusion if the program gets run more than once; it would also be
1393 * hard to make the program warp the clock precisely n hours) or
1394 * compile in the timezone information into the kernel. Bad, bad....
1398 * The best thing to do is to keep the CMOS clock in universal time (UTC)
1399 * as real UNIX machines always do it. This avoids all headaches about
1400 * daylight saving times and warping kernel clocks.
1402 void timekeeping_warp_clock(void)
1404 if (sys_tz.tz_minuteswest != 0) {
1405 struct timespec64 adjust;
1407 persistent_clock_is_local = 1;
1408 adjust.tv_sec = sys_tz.tz_minuteswest * 60;
1410 timekeeping_inject_offset(&adjust);
1415 * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1417 static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1419 tk->tai_offset = tai_offset;
1420 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1424 * change_clocksource - Swaps clocksources if a new one is available
1426 * Accumulates current time interval and initializes new clocksource
1428 static int change_clocksource(void *data)
1430 struct timekeeper *tk = &tk_core.timekeeper;
1431 struct clocksource *new, *old = NULL;
1432 unsigned long flags;
1433 bool change = false;
1435 new = (struct clocksource *) data;
1438 * If the cs is in module, get a module reference. Succeeds
1439 * for built-in code (owner == NULL) as well.
1441 if (try_module_get(new->owner)) {
1442 if (!new->enable || new->enable(new) == 0)
1445 module_put(new->owner);
1448 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1449 write_seqcount_begin(&tk_core.seq);
1451 timekeeping_forward_now(tk);
1454 old = tk->tkr_mono.clock;
1455 tk_setup_internals(tk, new);
1458 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1460 write_seqcount_end(&tk_core.seq);
1461 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1467 module_put(old->owner);
1474 * timekeeping_notify - Install a new clock source
1475 * @clock: pointer to the clock source
1477 * This function is called from clocksource.c after a new, better clock
1478 * source has been registered. The caller holds the clocksource_mutex.
1480 int timekeeping_notify(struct clocksource *clock)
1482 struct timekeeper *tk = &tk_core.timekeeper;
1484 if (tk->tkr_mono.clock == clock)
1486 stop_machine(change_clocksource, clock, NULL);
1487 tick_clock_notify();
1488 return tk->tkr_mono.clock == clock ? 0 : -1;
1492 * ktime_get_raw_ts64 - Returns the raw monotonic time in a timespec
1493 * @ts: pointer to the timespec64 to be set
1495 * Returns the raw monotonic time (completely un-modified by ntp)
1497 void ktime_get_raw_ts64(struct timespec64 *ts)
1499 struct timekeeper *tk = &tk_core.timekeeper;
1504 seq = read_seqcount_begin(&tk_core.seq);
1505 ts->tv_sec = tk->raw_sec;
1506 nsecs = timekeeping_get_ns(&tk->tkr_raw);
1508 } while (read_seqcount_retry(&tk_core.seq, seq));
1511 timespec64_add_ns(ts, nsecs);
1513 EXPORT_SYMBOL(ktime_get_raw_ts64);
1517 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1519 int timekeeping_valid_for_hres(void)
1521 struct timekeeper *tk = &tk_core.timekeeper;
1526 seq = read_seqcount_begin(&tk_core.seq);
1528 ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1530 } while (read_seqcount_retry(&tk_core.seq, seq));
1536 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1538 u64 timekeeping_max_deferment(void)
1540 struct timekeeper *tk = &tk_core.timekeeper;
1545 seq = read_seqcount_begin(&tk_core.seq);
1547 ret = tk->tkr_mono.clock->max_idle_ns;
1549 } while (read_seqcount_retry(&tk_core.seq, seq));
1555 * read_persistent_clock64 - Return time from the persistent clock.
1556 * @ts: Pointer to the storage for the readout value
1558 * Weak dummy function for arches that do not yet support it.
1559 * Reads the time from the battery backed persistent clock.
1560 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1562 * XXX - Do be sure to remove it once all arches implement it.
1564 void __weak read_persistent_clock64(struct timespec64 *ts)
1571 * read_persistent_wall_and_boot_offset - Read persistent clock, and also offset
1574 * Weak dummy function for arches that do not yet support it.
1575 * @wall_time: - current time as returned by persistent clock
1576 * @boot_offset: - offset that is defined as wall_time - boot_time
1578 * The default function calculates offset based on the current value of
1579 * local_clock(). This way architectures that support sched_clock() but don't
1580 * support dedicated boot time clock will provide the best estimate of the
1584 read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
1585 struct timespec64 *boot_offset)
1587 read_persistent_clock64(wall_time);
1588 *boot_offset = ns_to_timespec64(local_clock());
1592 * Flag reflecting whether timekeeping_resume() has injected sleeptime.
1594 * The flag starts of false and is only set when a suspend reaches
1595 * timekeeping_suspend(), timekeeping_resume() sets it to false when the
1596 * timekeeper clocksource is not stopping across suspend and has been
1597 * used to update sleep time. If the timekeeper clocksource has stopped
1598 * then the flag stays true and is used by the RTC resume code to decide
1599 * whether sleeptime must be injected and if so the flag gets false then.
1601 * If a suspend fails before reaching timekeeping_resume() then the flag
1602 * stays false and prevents erroneous sleeptime injection.
1604 static bool suspend_timing_needed;
1606 /* Flag for if there is a persistent clock on this platform */
1607 static bool persistent_clock_exists;
1610 * timekeeping_init - Initializes the clocksource and common timekeeping values
1612 void __init timekeeping_init(void)
1614 struct timespec64 wall_time, boot_offset, wall_to_mono;
1615 struct timekeeper *tk = &tk_core.timekeeper;
1616 struct clocksource *clock;
1617 unsigned long flags;
1619 read_persistent_wall_and_boot_offset(&wall_time, &boot_offset);
1620 if (timespec64_valid_settod(&wall_time) &&
1621 timespec64_to_ns(&wall_time) > 0) {
1622 persistent_clock_exists = true;
1623 } else if (timespec64_to_ns(&wall_time) != 0) {
1624 pr_warn("Persistent clock returned invalid value");
1625 wall_time = (struct timespec64){0};
1628 if (timespec64_compare(&wall_time, &boot_offset) < 0)
1629 boot_offset = (struct timespec64){0};
1632 * We want set wall_to_mono, so the following is true:
1633 * wall time + wall_to_mono = boot time
1635 wall_to_mono = timespec64_sub(boot_offset, wall_time);
1637 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1638 write_seqcount_begin(&tk_core.seq);
1641 clock = clocksource_default_clock();
1643 clock->enable(clock);
1644 tk_setup_internals(tk, clock);
1646 tk_set_xtime(tk, &wall_time);
1649 tk_set_wall_to_mono(tk, wall_to_mono);
1651 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1653 write_seqcount_end(&tk_core.seq);
1654 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1657 /* time in seconds when suspend began for persistent clock */
1658 static struct timespec64 timekeeping_suspend_time;
1661 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1662 * @tk: Pointer to the timekeeper to be updated
1663 * @delta: Pointer to the delta value in timespec64 format
1665 * Takes a timespec offset measuring a suspend interval and properly
1666 * adds the sleep offset to the timekeeping variables.
1668 static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1669 const struct timespec64 *delta)
1671 if (!timespec64_valid_strict(delta)) {
1672 printk_deferred(KERN_WARNING
1673 "__timekeeping_inject_sleeptime: Invalid "
1674 "sleep delta value!\n");
1677 tk_xtime_add(tk, delta);
1678 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1679 tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1680 tk_debug_account_sleep_time(delta);
1683 #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1685 * We have three kinds of time sources to use for sleep time
1686 * injection, the preference order is:
1687 * 1) non-stop clocksource
1688 * 2) persistent clock (ie: RTC accessible when irqs are off)
1691 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1692 * If system has neither 1) nor 2), 3) will be used finally.
1695 * If timekeeping has injected sleeptime via either 1) or 2),
1696 * 3) becomes needless, so in this case we don't need to call
1697 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1700 bool timekeeping_rtc_skipresume(void)
1702 return !suspend_timing_needed;
1706 * 1) can be determined whether to use or not only when doing
1707 * timekeeping_resume() which is invoked after rtc_suspend(),
1708 * so we can't skip rtc_suspend() surely if system has 1).
1710 * But if system has 2), 2) will definitely be used, so in this
1711 * case we don't need to call rtc_suspend(), and this is what
1712 * timekeeping_rtc_skipsuspend() means.
1714 bool timekeeping_rtc_skipsuspend(void)
1716 return persistent_clock_exists;
1720 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1721 * @delta: pointer to a timespec64 delta value
1723 * This hook is for architectures that cannot support read_persistent_clock64
1724 * because their RTC/persistent clock is only accessible when irqs are enabled.
1725 * and also don't have an effective nonstop clocksource.
1727 * This function should only be called by rtc_resume(), and allows
1728 * a suspend offset to be injected into the timekeeping values.
1730 void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
1732 struct timekeeper *tk = &tk_core.timekeeper;
1733 unsigned long flags;
1735 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1736 write_seqcount_begin(&tk_core.seq);
1738 suspend_timing_needed = false;
1740 timekeeping_forward_now(tk);
1742 __timekeeping_inject_sleeptime(tk, delta);
1744 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1746 write_seqcount_end(&tk_core.seq);
1747 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1749 /* signal hrtimers about time change */
1755 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1757 void timekeeping_resume(void)
1759 struct timekeeper *tk = &tk_core.timekeeper;
1760 struct clocksource *clock = tk->tkr_mono.clock;
1761 unsigned long flags;
1762 struct timespec64 ts_new, ts_delta;
1763 u64 cycle_now, nsec;
1764 bool inject_sleeptime = false;
1766 read_persistent_clock64(&ts_new);
1768 clockevents_resume();
1769 clocksource_resume();
1771 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1772 write_seqcount_begin(&tk_core.seq);
1775 * After system resumes, we need to calculate the suspended time and
1776 * compensate it for the OS time. There are 3 sources that could be
1777 * used: Nonstop clocksource during suspend, persistent clock and rtc
1780 * One specific platform may have 1 or 2 or all of them, and the
1781 * preference will be:
1782 * suspend-nonstop clocksource -> persistent clock -> rtc
1783 * The less preferred source will only be tried if there is no better
1784 * usable source. The rtc part is handled separately in rtc core code.
1786 cycle_now = tk_clock_read(&tk->tkr_mono);
1787 nsec = clocksource_stop_suspend_timing(clock, cycle_now);
1789 ts_delta = ns_to_timespec64(nsec);
1790 inject_sleeptime = true;
1791 } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1792 ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1793 inject_sleeptime = true;
1796 if (inject_sleeptime) {
1797 suspend_timing_needed = false;
1798 __timekeeping_inject_sleeptime(tk, &ts_delta);
1801 /* Re-base the last cycle value */
1802 tk->tkr_mono.cycle_last = cycle_now;
1803 tk->tkr_raw.cycle_last = cycle_now;
1806 timekeeping_suspended = 0;
1807 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1808 write_seqcount_end(&tk_core.seq);
1809 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1811 touch_softlockup_watchdog();
1813 /* Resume the clockevent device(s) and hrtimers */
1815 /* Notify timerfd as resume is equivalent to clock_was_set() */
1819 int timekeeping_suspend(void)
1821 struct timekeeper *tk = &tk_core.timekeeper;
1822 unsigned long flags;
1823 struct timespec64 delta, delta_delta;
1824 static struct timespec64 old_delta;
1825 struct clocksource *curr_clock;
1828 read_persistent_clock64(&timekeeping_suspend_time);
1831 * On some systems the persistent_clock can not be detected at
1832 * timekeeping_init by its return value, so if we see a valid
1833 * value returned, update the persistent_clock_exists flag.
1835 if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1836 persistent_clock_exists = true;
1838 suspend_timing_needed = true;
1840 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1841 write_seqcount_begin(&tk_core.seq);
1842 timekeeping_forward_now(tk);
1843 timekeeping_suspended = 1;
1846 * Since we've called forward_now, cycle_last stores the value
1847 * just read from the current clocksource. Save this to potentially
1848 * use in suspend timing.
1850 curr_clock = tk->tkr_mono.clock;
1851 cycle_now = tk->tkr_mono.cycle_last;
1852 clocksource_start_suspend_timing(curr_clock, cycle_now);
1854 if (persistent_clock_exists) {
1856 * To avoid drift caused by repeated suspend/resumes,
1857 * which each can add ~1 second drift error,
1858 * try to compensate so the difference in system time
1859 * and persistent_clock time stays close to constant.
1861 delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1862 delta_delta = timespec64_sub(delta, old_delta);
1863 if (abs(delta_delta.tv_sec) >= 2) {
1865 * if delta_delta is too large, assume time correction
1866 * has occurred and set old_delta to the current delta.
1870 /* Otherwise try to adjust old_system to compensate */
1871 timekeeping_suspend_time =
1872 timespec64_add(timekeeping_suspend_time, delta_delta);
1876 timekeeping_update(tk, TK_MIRROR);
1877 halt_fast_timekeeper(tk);
1878 write_seqcount_end(&tk_core.seq);
1879 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1882 clocksource_suspend();
1883 clockevents_suspend();
1888 /* sysfs resume/suspend bits for timekeeping */
1889 static struct syscore_ops timekeeping_syscore_ops = {
1890 .resume = timekeeping_resume,
1891 .suspend = timekeeping_suspend,
1894 static int __init timekeeping_init_ops(void)
1896 register_syscore_ops(&timekeeping_syscore_ops);
1899 device_initcall(timekeeping_init_ops);
1902 * Apply a multiplier adjustment to the timekeeper
1904 static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1908 s64 interval = tk->cycle_interval;
1910 if (mult_adj == 0) {
1912 } else if (mult_adj == -1) {
1913 interval = -interval;
1915 } else if (mult_adj != 1) {
1916 interval *= mult_adj;
1921 * So the following can be confusing.
1923 * To keep things simple, lets assume mult_adj == 1 for now.
1925 * When mult_adj != 1, remember that the interval and offset values
1926 * have been appropriately scaled so the math is the same.
1928 * The basic idea here is that we're increasing the multiplier
1929 * by one, this causes the xtime_interval to be incremented by
1930 * one cycle_interval. This is because:
1931 * xtime_interval = cycle_interval * mult
1932 * So if mult is being incremented by one:
1933 * xtime_interval = cycle_interval * (mult + 1)
1935 * xtime_interval = (cycle_interval * mult) + cycle_interval
1936 * Which can be shortened to:
1937 * xtime_interval += cycle_interval
1939 * So offset stores the non-accumulated cycles. Thus the current
1940 * time (in shifted nanoseconds) is:
1941 * now = (offset * adj) + xtime_nsec
1942 * Now, even though we're adjusting the clock frequency, we have
1943 * to keep time consistent. In other words, we can't jump back
1944 * in time, and we also want to avoid jumping forward in time.
1946 * So given the same offset value, we need the time to be the same
1947 * both before and after the freq adjustment.
1948 * now = (offset * adj_1) + xtime_nsec_1
1949 * now = (offset * adj_2) + xtime_nsec_2
1951 * (offset * adj_1) + xtime_nsec_1 =
1952 * (offset * adj_2) + xtime_nsec_2
1956 * (offset * adj_1) + xtime_nsec_1 =
1957 * (offset * (adj_1+1)) + xtime_nsec_2
1958 * (offset * adj_1) + xtime_nsec_1 =
1959 * (offset * adj_1) + offset + xtime_nsec_2
1960 * Canceling the sides:
1961 * xtime_nsec_1 = offset + xtime_nsec_2
1963 * xtime_nsec_2 = xtime_nsec_1 - offset
1964 * Which simplifies to:
1965 * xtime_nsec -= offset
1967 if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1968 /* NTP adjustment caused clocksource mult overflow */
1973 tk->tkr_mono.mult += mult_adj;
1974 tk->xtime_interval += interval;
1975 tk->tkr_mono.xtime_nsec -= offset;
1979 * Adjust the timekeeper's multiplier to the correct frequency
1980 * and also to reduce the accumulated error value.
1982 static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1987 * Determine the multiplier from the current NTP tick length.
1988 * Avoid expensive division when the tick length doesn't change.
1990 if (likely(tk->ntp_tick == ntp_tick_length())) {
1991 mult = tk->tkr_mono.mult - tk->ntp_err_mult;
1993 tk->ntp_tick = ntp_tick_length();
1994 mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) -
1995 tk->xtime_remainder, tk->cycle_interval);
1999 * If the clock is behind the NTP time, increase the multiplier by 1
2000 * to catch up with it. If it's ahead and there was a remainder in the
2001 * tick division, the clock will slow down. Otherwise it will stay
2002 * ahead until the tick length changes to a non-divisible value.
2004 tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0;
2005 mult += tk->ntp_err_mult;
2007 timekeeping_apply_adjustment(tk, offset, mult - tk->tkr_mono.mult);
2009 if (unlikely(tk->tkr_mono.clock->maxadj &&
2010 (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
2011 > tk->tkr_mono.clock->maxadj))) {
2012 printk_once(KERN_WARNING
2013 "Adjusting %s more than 11%% (%ld vs %ld)\n",
2014 tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
2015 (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
2019 * It may be possible that when we entered this function, xtime_nsec
2020 * was very small. Further, if we're slightly speeding the clocksource
2021 * in the code above, its possible the required corrective factor to
2022 * xtime_nsec could cause it to underflow.
2024 * Now, since we have already accumulated the second and the NTP
2025 * subsystem has been notified via second_overflow(), we need to skip
2028 if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
2029 tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC <<
2032 tk->skip_second_overflow = 1;
2037 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
2039 * Helper function that accumulates the nsecs greater than a second
2040 * from the xtime_nsec field to the xtime_secs field.
2041 * It also calls into the NTP code to handle leapsecond processing.
2043 static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
2045 u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
2046 unsigned int clock_set = 0;
2048 while (tk->tkr_mono.xtime_nsec >= nsecps) {
2051 tk->tkr_mono.xtime_nsec -= nsecps;
2055 * Skip NTP update if this second was accumulated before,
2056 * i.e. xtime_nsec underflowed in timekeeping_adjust()
2058 if (unlikely(tk->skip_second_overflow)) {
2059 tk->skip_second_overflow = 0;
2063 /* Figure out if its a leap sec and apply if needed */
2064 leap = second_overflow(tk->xtime_sec);
2065 if (unlikely(leap)) {
2066 struct timespec64 ts;
2068 tk->xtime_sec += leap;
2072 tk_set_wall_to_mono(tk,
2073 timespec64_sub(tk->wall_to_monotonic, ts));
2075 __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
2077 clock_set = TK_CLOCK_WAS_SET;
2084 * logarithmic_accumulation - shifted accumulation of cycles
2086 * This functions accumulates a shifted interval of cycles into
2087 * a shifted interval nanoseconds. Allows for O(log) accumulation
2090 * Returns the unconsumed cycles.
2092 static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2093 u32 shift, unsigned int *clock_set)
2095 u64 interval = tk->cycle_interval << shift;
2098 /* If the offset is smaller than a shifted interval, do nothing */
2099 if (offset < interval)
2102 /* Accumulate one shifted interval */
2104 tk->tkr_mono.cycle_last += interval;
2105 tk->tkr_raw.cycle_last += interval;
2107 tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2108 *clock_set |= accumulate_nsecs_to_secs(tk);
2110 /* Accumulate raw time */
2111 tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2112 snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2113 while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2114 tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2118 /* Accumulate error between NTP and clock interval */
2119 tk->ntp_error += tk->ntp_tick << shift;
2120 tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2121 (tk->ntp_error_shift + shift);
2127 * timekeeping_advance - Updates the timekeeper to the current time and
2128 * current NTP tick length
2130 static void timekeeping_advance(enum timekeeping_adv_mode mode)
2132 struct timekeeper *real_tk = &tk_core.timekeeper;
2133 struct timekeeper *tk = &shadow_timekeeper;
2135 int shift = 0, maxshift;
2136 unsigned int clock_set = 0;
2137 unsigned long flags;
2139 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2141 /* Make sure we're fully resumed: */
2142 if (unlikely(timekeeping_suspended))
2145 offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
2146 tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2148 /* Check if there's really nothing to do */
2149 if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK)
2152 /* Do some additional sanity checking */
2153 timekeeping_check_update(tk, offset);
2156 * With NO_HZ we may have to accumulate many cycle_intervals
2157 * (think "ticks") worth of time at once. To do this efficiently,
2158 * we calculate the largest doubling multiple of cycle_intervals
2159 * that is smaller than the offset. We then accumulate that
2160 * chunk in one go, and then try to consume the next smaller
2163 shift = ilog2(offset) - ilog2(tk->cycle_interval);
2164 shift = max(0, shift);
2165 /* Bound shift to one less than what overflows tick_length */
2166 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2167 shift = min(shift, maxshift);
2168 while (offset >= tk->cycle_interval) {
2169 offset = logarithmic_accumulation(tk, offset, shift,
2171 if (offset < tk->cycle_interval<<shift)
2175 /* Adjust the multiplier to correct NTP error */
2176 timekeeping_adjust(tk, offset);
2179 * Finally, make sure that after the rounding
2180 * xtime_nsec isn't larger than NSEC_PER_SEC
2182 clock_set |= accumulate_nsecs_to_secs(tk);
2184 write_seqcount_begin(&tk_core.seq);
2186 * Update the real timekeeper.
2188 * We could avoid this memcpy by switching pointers, but that
2189 * requires changes to all other timekeeper usage sites as
2190 * well, i.e. move the timekeeper pointer getter into the
2191 * spinlocked/seqcount protected sections. And we trade this
2192 * memcpy under the tk_core.seq against one before we start
2195 timekeeping_update(tk, clock_set);
2196 memcpy(real_tk, tk, sizeof(*tk));
2197 /* The memcpy must come last. Do not put anything here! */
2198 write_seqcount_end(&tk_core.seq);
2200 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2202 /* Have to call _delayed version, since in irq context*/
2203 clock_was_set_delayed();
2207 * update_wall_time - Uses the current clocksource to increment the wall time
2210 void update_wall_time(void)
2212 timekeeping_advance(TK_ADV_TICK);
2216 * getboottime64 - Return the real time of system boot.
2217 * @ts: pointer to the timespec64 to be set
2219 * Returns the wall-time of boot in a timespec64.
2221 * This is based on the wall_to_monotonic offset and the total suspend
2222 * time. Calls to settimeofday will affect the value returned (which
2223 * basically means that however wrong your real time clock is at boot time,
2224 * you get the right time here).
2226 void getboottime64(struct timespec64 *ts)
2228 struct timekeeper *tk = &tk_core.timekeeper;
2229 ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2231 *ts = ktime_to_timespec64(t);
2233 EXPORT_SYMBOL_GPL(getboottime64);
2235 void ktime_get_coarse_real_ts64(struct timespec64 *ts)
2237 struct timekeeper *tk = &tk_core.timekeeper;
2241 seq = read_seqcount_begin(&tk_core.seq);
2244 } while (read_seqcount_retry(&tk_core.seq, seq));
2246 EXPORT_SYMBOL(ktime_get_coarse_real_ts64);
2248 void ktime_get_coarse_ts64(struct timespec64 *ts)
2250 struct timekeeper *tk = &tk_core.timekeeper;
2251 struct timespec64 now, mono;
2255 seq = read_seqcount_begin(&tk_core.seq);
2258 mono = tk->wall_to_monotonic;
2259 } while (read_seqcount_retry(&tk_core.seq, seq));
2261 set_normalized_timespec64(ts, now.tv_sec + mono.tv_sec,
2262 now.tv_nsec + mono.tv_nsec);
2264 EXPORT_SYMBOL(ktime_get_coarse_ts64);
2267 * Must hold jiffies_lock
2269 void do_timer(unsigned long ticks)
2271 jiffies_64 += ticks;
2276 * ktime_get_update_offsets_now - hrtimer helper
2277 * @cwsseq: pointer to check and store the clock was set sequence number
2278 * @offs_real: pointer to storage for monotonic -> realtime offset
2279 * @offs_boot: pointer to storage for monotonic -> boottime offset
2280 * @offs_tai: pointer to storage for monotonic -> clock tai offset
2282 * Returns current monotonic time and updates the offsets if the
2283 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2286 * Called from hrtimer_interrupt() or retrigger_next_event()
2288 ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2289 ktime_t *offs_boot, ktime_t *offs_tai)
2291 struct timekeeper *tk = &tk_core.timekeeper;
2297 seq = read_seqcount_begin(&tk_core.seq);
2299 base = tk->tkr_mono.base;
2300 nsecs = timekeeping_get_ns(&tk->tkr_mono);
2301 base = ktime_add_ns(base, nsecs);
2303 if (*cwsseq != tk->clock_was_set_seq) {
2304 *cwsseq = tk->clock_was_set_seq;
2305 *offs_real = tk->offs_real;
2306 *offs_boot = tk->offs_boot;
2307 *offs_tai = tk->offs_tai;
2310 /* Handle leapsecond insertion adjustments */
2311 if (unlikely(base >= tk->next_leap_ktime))
2312 *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2314 } while (read_seqcount_retry(&tk_core.seq, seq));
2320 * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2322 static int timekeeping_validate_timex(const struct __kernel_timex *txc)
2324 if (txc->modes & ADJ_ADJTIME) {
2325 /* singleshot must not be used with any other mode bits */
2326 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2328 if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2329 !capable(CAP_SYS_TIME))
2332 /* In order to modify anything, you gotta be super-user! */
2333 if (txc->modes && !capable(CAP_SYS_TIME))
2336 * if the quartz is off by more than 10% then
2337 * something is VERY wrong!
2339 if (txc->modes & ADJ_TICK &&
2340 (txc->tick < 900000/USER_HZ ||
2341 txc->tick > 1100000/USER_HZ))
2345 if (txc->modes & ADJ_SETOFFSET) {
2346 /* In order to inject time, you gotta be super-user! */
2347 if (!capable(CAP_SYS_TIME))
2351 * Validate if a timespec/timeval used to inject a time
2352 * offset is valid. Offsets can be positive or negative, so
2353 * we don't check tv_sec. The value of the timeval/timespec
2354 * is the sum of its fields,but *NOTE*:
2355 * The field tv_usec/tv_nsec must always be non-negative and
2356 * we can't have more nanoseconds/microseconds than a second.
2358 if (txc->time.tv_usec < 0)
2361 if (txc->modes & ADJ_NANO) {
2362 if (txc->time.tv_usec >= NSEC_PER_SEC)
2365 if (txc->time.tv_usec >= USEC_PER_SEC)
2371 * Check for potential multiplication overflows that can
2372 * only happen on 64-bit systems:
2374 if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2375 if (LLONG_MIN / PPM_SCALE > txc->freq)
2377 if (LLONG_MAX / PPM_SCALE < txc->freq)
2386 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2388 int do_adjtimex(struct __kernel_timex *txc)
2390 struct timekeeper *tk = &tk_core.timekeeper;
2391 struct audit_ntp_data ad;
2392 unsigned long flags;
2393 struct timespec64 ts;
2397 /* Validate the data before disabling interrupts */
2398 ret = timekeeping_validate_timex(txc);
2402 if (txc->modes & ADJ_SETOFFSET) {
2403 struct timespec64 delta;
2404 delta.tv_sec = txc->time.tv_sec;
2405 delta.tv_nsec = txc->time.tv_usec;
2406 if (!(txc->modes & ADJ_NANO))
2407 delta.tv_nsec *= 1000;
2408 ret = timekeeping_inject_offset(&delta);
2412 audit_tk_injoffset(delta);
2415 audit_ntp_init(&ad);
2417 ktime_get_real_ts64(&ts);
2419 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2420 write_seqcount_begin(&tk_core.seq);
2422 orig_tai = tai = tk->tai_offset;
2423 ret = __do_adjtimex(txc, &ts, &tai, &ad);
2425 if (tai != orig_tai) {
2426 __timekeeping_set_tai_offset(tk, tai);
2427 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2429 tk_update_leap_state(tk);
2431 write_seqcount_end(&tk_core.seq);
2432 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2436 /* Update the multiplier immediately if frequency was set directly */
2437 if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
2438 timekeeping_advance(TK_ADV_FREQ);
2440 if (tai != orig_tai)
2443 ntp_notify_cmos_timer();
2448 #ifdef CONFIG_NTP_PPS
2450 * hardpps() - Accessor function to NTP __hardpps function
2452 void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2454 unsigned long flags;
2456 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2457 write_seqcount_begin(&tk_core.seq);
2459 __hardpps(phase_ts, raw_ts);
2461 write_seqcount_end(&tk_core.seq);
2462 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2464 EXPORT_SYMBOL(hardpps);
2465 #endif /* CONFIG_NTP_PPS */