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 accross 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 accross 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 mononotic 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. This replaces the
995 * get_seconds() interface which is not y2038 safe on 32bit systems.
997 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
998 * 32bit systems the access must be protected with the sequence
999 * counter to provide "atomic" access to the 64bit tk->xtime_sec
1002 time64_t
ktime_get_real_seconds(void)
1004 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1008 if (IS_ENABLED(CONFIG_64BIT
))
1009 return tk
->xtime_sec
;
1012 seq
= read_seqcount_begin(&tk_core
.seq
);
1013 seconds
= tk
->xtime_sec
;
1015 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1019 EXPORT_SYMBOL_GPL(ktime_get_real_seconds
);
1022 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
1023 * but without the sequence counter protect. This internal function
1024 * is called just when timekeeping lock is already held.
1026 noinstr time64_t
__ktime_get_real_seconds(void)
1028 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1030 return tk
->xtime_sec
;
1034 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
1035 * @systime_snapshot: pointer to struct receiving the system time snapshot
1037 void ktime_get_snapshot(struct system_time_snapshot
*systime_snapshot
)
1039 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1047 WARN_ON_ONCE(timekeeping_suspended
);
1050 seq
= read_seqcount_begin(&tk_core
.seq
);
1051 now
= tk_clock_read(&tk
->tkr_mono
);
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
;
1432 unsigned long flags
;
1434 new = (struct clocksource
*) data
;
1436 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1437 write_seqcount_begin(&tk_core
.seq
);
1439 timekeeping_forward_now(tk
);
1441 * If the cs is in module, get a module reference. Succeeds
1442 * for built-in code (owner == NULL) as well.
1444 if (try_module_get(new->owner
)) {
1445 if (!new->enable
|| new->enable(new) == 0) {
1446 old
= tk
->tkr_mono
.clock
;
1447 tk_setup_internals(tk
, new);
1450 module_put(old
->owner
);
1452 module_put(new->owner
);
1455 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
1457 write_seqcount_end(&tk_core
.seq
);
1458 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1464 * timekeeping_notify - Install a new clock source
1465 * @clock: pointer to the clock source
1467 * This function is called from clocksource.c after a new, better clock
1468 * source has been registered. The caller holds the clocksource_mutex.
1470 int timekeeping_notify(struct clocksource
*clock
)
1472 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1474 if (tk
->tkr_mono
.clock
== clock
)
1476 stop_machine(change_clocksource
, clock
, NULL
);
1477 tick_clock_notify();
1478 return tk
->tkr_mono
.clock
== clock
? 0 : -1;
1482 * ktime_get_raw_ts64 - Returns the raw monotonic time in a timespec
1483 * @ts: pointer to the timespec64 to be set
1485 * Returns the raw monotonic time (completely un-modified by ntp)
1487 void ktime_get_raw_ts64(struct timespec64
*ts
)
1489 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1494 seq
= read_seqcount_begin(&tk_core
.seq
);
1495 ts
->tv_sec
= tk
->raw_sec
;
1496 nsecs
= timekeeping_get_ns(&tk
->tkr_raw
);
1498 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1501 timespec64_add_ns(ts
, nsecs
);
1503 EXPORT_SYMBOL(ktime_get_raw_ts64
);
1507 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1509 int timekeeping_valid_for_hres(void)
1511 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1516 seq
= read_seqcount_begin(&tk_core
.seq
);
1518 ret
= tk
->tkr_mono
.clock
->flags
& CLOCK_SOURCE_VALID_FOR_HRES
;
1520 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1526 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1528 u64
timekeeping_max_deferment(void)
1530 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1535 seq
= read_seqcount_begin(&tk_core
.seq
);
1537 ret
= tk
->tkr_mono
.clock
->max_idle_ns
;
1539 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1545 * read_persistent_clock64 - Return time from the persistent clock.
1546 * @ts: Pointer to the storage for the readout value
1548 * Weak dummy function for arches that do not yet support it.
1549 * Reads the time from the battery backed persistent clock.
1550 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1552 * XXX - Do be sure to remove it once all arches implement it.
1554 void __weak
read_persistent_clock64(struct timespec64
*ts
)
1561 * read_persistent_wall_and_boot_offset - Read persistent clock, and also offset
1564 * Weak dummy function for arches that do not yet support it.
1565 * @wall_time: - current time as returned by persistent clock
1566 * @boot_offset: - offset that is defined as wall_time - boot_time
1568 * The default function calculates offset based on the current value of
1569 * local_clock(). This way architectures that support sched_clock() but don't
1570 * support dedicated boot time clock will provide the best estimate of the
1574 read_persistent_wall_and_boot_offset(struct timespec64
*wall_time
,
1575 struct timespec64
*boot_offset
)
1577 read_persistent_clock64(wall_time
);
1578 *boot_offset
= ns_to_timespec64(local_clock());
1582 * Flag reflecting whether timekeeping_resume() has injected sleeptime.
1584 * The flag starts of false and is only set when a suspend reaches
1585 * timekeeping_suspend(), timekeeping_resume() sets it to false when the
1586 * timekeeper clocksource is not stopping across suspend and has been
1587 * used to update sleep time. If the timekeeper clocksource has stopped
1588 * then the flag stays true and is used by the RTC resume code to decide
1589 * whether sleeptime must be injected and if so the flag gets false then.
1591 * If a suspend fails before reaching timekeeping_resume() then the flag
1592 * stays false and prevents erroneous sleeptime injection.
1594 static bool suspend_timing_needed
;
1596 /* Flag for if there is a persistent clock on this platform */
1597 static bool persistent_clock_exists
;
1600 * timekeeping_init - Initializes the clocksource and common timekeeping values
1602 void __init
timekeeping_init(void)
1604 struct timespec64 wall_time
, boot_offset
, wall_to_mono
;
1605 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1606 struct clocksource
*clock
;
1607 unsigned long flags
;
1609 read_persistent_wall_and_boot_offset(&wall_time
, &boot_offset
);
1610 if (timespec64_valid_settod(&wall_time
) &&
1611 timespec64_to_ns(&wall_time
) > 0) {
1612 persistent_clock_exists
= true;
1613 } else if (timespec64_to_ns(&wall_time
) != 0) {
1614 pr_warn("Persistent clock returned invalid value");
1615 wall_time
= (struct timespec64
){0};
1618 if (timespec64_compare(&wall_time
, &boot_offset
) < 0)
1619 boot_offset
= (struct timespec64
){0};
1622 * We want set wall_to_mono, so the following is true:
1623 * wall time + wall_to_mono = boot time
1625 wall_to_mono
= timespec64_sub(boot_offset
, wall_time
);
1627 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1628 write_seqcount_begin(&tk_core
.seq
);
1631 clock
= clocksource_default_clock();
1633 clock
->enable(clock
);
1634 tk_setup_internals(tk
, clock
);
1636 tk_set_xtime(tk
, &wall_time
);
1639 tk_set_wall_to_mono(tk
, wall_to_mono
);
1641 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
1643 write_seqcount_end(&tk_core
.seq
);
1644 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1647 /* time in seconds when suspend began for persistent clock */
1648 static struct timespec64 timekeeping_suspend_time
;
1651 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1652 * @tk: Pointer to the timekeeper to be updated
1653 * @delta: Pointer to the delta value in timespec64 format
1655 * Takes a timespec offset measuring a suspend interval and properly
1656 * adds the sleep offset to the timekeeping variables.
1658 static void __timekeeping_inject_sleeptime(struct timekeeper
*tk
,
1659 const struct timespec64
*delta
)
1661 if (!timespec64_valid_strict(delta
)) {
1662 printk_deferred(KERN_WARNING
1663 "__timekeeping_inject_sleeptime: Invalid "
1664 "sleep delta value!\n");
1667 tk_xtime_add(tk
, delta
);
1668 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, *delta
));
1669 tk_update_sleep_time(tk
, timespec64_to_ktime(*delta
));
1670 tk_debug_account_sleep_time(delta
);
1673 #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1675 * We have three kinds of time sources to use for sleep time
1676 * injection, the preference order is:
1677 * 1) non-stop clocksource
1678 * 2) persistent clock (ie: RTC accessible when irqs are off)
1681 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1682 * If system has neither 1) nor 2), 3) will be used finally.
1685 * If timekeeping has injected sleeptime via either 1) or 2),
1686 * 3) becomes needless, so in this case we don't need to call
1687 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1690 bool timekeeping_rtc_skipresume(void)
1692 return !suspend_timing_needed
;
1696 * 1) can be determined whether to use or not only when doing
1697 * timekeeping_resume() which is invoked after rtc_suspend(),
1698 * so we can't skip rtc_suspend() surely if system has 1).
1700 * But if system has 2), 2) will definitely be used, so in this
1701 * case we don't need to call rtc_suspend(), and this is what
1702 * timekeeping_rtc_skipsuspend() means.
1704 bool timekeeping_rtc_skipsuspend(void)
1706 return persistent_clock_exists
;
1710 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1711 * @delta: pointer to a timespec64 delta value
1713 * This hook is for architectures that cannot support read_persistent_clock64
1714 * because their RTC/persistent clock is only accessible when irqs are enabled.
1715 * and also don't have an effective nonstop clocksource.
1717 * This function should only be called by rtc_resume(), and allows
1718 * a suspend offset to be injected into the timekeeping values.
1720 void timekeeping_inject_sleeptime64(const struct timespec64
*delta
)
1722 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1723 unsigned long flags
;
1725 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1726 write_seqcount_begin(&tk_core
.seq
);
1728 suspend_timing_needed
= false;
1730 timekeeping_forward_now(tk
);
1732 __timekeeping_inject_sleeptime(tk
, delta
);
1734 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
1736 write_seqcount_end(&tk_core
.seq
);
1737 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1739 /* signal hrtimers about time change */
1745 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1747 void timekeeping_resume(void)
1749 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1750 struct clocksource
*clock
= tk
->tkr_mono
.clock
;
1751 unsigned long flags
;
1752 struct timespec64 ts_new
, ts_delta
;
1753 u64 cycle_now
, nsec
;
1754 bool inject_sleeptime
= false;
1756 read_persistent_clock64(&ts_new
);
1758 clockevents_resume();
1759 clocksource_resume();
1761 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1762 write_seqcount_begin(&tk_core
.seq
);
1765 * After system resumes, we need to calculate the suspended time and
1766 * compensate it for the OS time. There are 3 sources that could be
1767 * used: Nonstop clocksource during suspend, persistent clock and rtc
1770 * One specific platform may have 1 or 2 or all of them, and the
1771 * preference will be:
1772 * suspend-nonstop clocksource -> persistent clock -> rtc
1773 * The less preferred source will only be tried if there is no better
1774 * usable source. The rtc part is handled separately in rtc core code.
1776 cycle_now
= tk_clock_read(&tk
->tkr_mono
);
1777 nsec
= clocksource_stop_suspend_timing(clock
, cycle_now
);
1779 ts_delta
= ns_to_timespec64(nsec
);
1780 inject_sleeptime
= true;
1781 } else if (timespec64_compare(&ts_new
, &timekeeping_suspend_time
) > 0) {
1782 ts_delta
= timespec64_sub(ts_new
, timekeeping_suspend_time
);
1783 inject_sleeptime
= true;
1786 if (inject_sleeptime
) {
1787 suspend_timing_needed
= false;
1788 __timekeeping_inject_sleeptime(tk
, &ts_delta
);
1791 /* Re-base the last cycle value */
1792 tk
->tkr_mono
.cycle_last
= cycle_now
;
1793 tk
->tkr_raw
.cycle_last
= cycle_now
;
1796 timekeeping_suspended
= 0;
1797 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
1798 write_seqcount_end(&tk_core
.seq
);
1799 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1801 touch_softlockup_watchdog();
1807 int timekeeping_suspend(void)
1809 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1810 unsigned long flags
;
1811 struct timespec64 delta
, delta_delta
;
1812 static struct timespec64 old_delta
;
1813 struct clocksource
*curr_clock
;
1816 read_persistent_clock64(&timekeeping_suspend_time
);
1819 * On some systems the persistent_clock can not be detected at
1820 * timekeeping_init by its return value, so if we see a valid
1821 * value returned, update the persistent_clock_exists flag.
1823 if (timekeeping_suspend_time
.tv_sec
|| timekeeping_suspend_time
.tv_nsec
)
1824 persistent_clock_exists
= true;
1826 suspend_timing_needed
= true;
1828 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1829 write_seqcount_begin(&tk_core
.seq
);
1830 timekeeping_forward_now(tk
);
1831 timekeeping_suspended
= 1;
1834 * Since we've called forward_now, cycle_last stores the value
1835 * just read from the current clocksource. Save this to potentially
1836 * use in suspend timing.
1838 curr_clock
= tk
->tkr_mono
.clock
;
1839 cycle_now
= tk
->tkr_mono
.cycle_last
;
1840 clocksource_start_suspend_timing(curr_clock
, cycle_now
);
1842 if (persistent_clock_exists
) {
1844 * To avoid drift caused by repeated suspend/resumes,
1845 * which each can add ~1 second drift error,
1846 * try to compensate so the difference in system time
1847 * and persistent_clock time stays close to constant.
1849 delta
= timespec64_sub(tk_xtime(tk
), timekeeping_suspend_time
);
1850 delta_delta
= timespec64_sub(delta
, old_delta
);
1851 if (abs(delta_delta
.tv_sec
) >= 2) {
1853 * if delta_delta is too large, assume time correction
1854 * has occurred and set old_delta to the current delta.
1858 /* Otherwise try to adjust old_system to compensate */
1859 timekeeping_suspend_time
=
1860 timespec64_add(timekeeping_suspend_time
, delta_delta
);
1864 timekeeping_update(tk
, TK_MIRROR
);
1865 halt_fast_timekeeper(tk
);
1866 write_seqcount_end(&tk_core
.seq
);
1867 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1870 clocksource_suspend();
1871 clockevents_suspend();
1876 /* sysfs resume/suspend bits for timekeeping */
1877 static struct syscore_ops timekeeping_syscore_ops
= {
1878 .resume
= timekeeping_resume
,
1879 .suspend
= timekeeping_suspend
,
1882 static int __init
timekeeping_init_ops(void)
1884 register_syscore_ops(&timekeeping_syscore_ops
);
1887 device_initcall(timekeeping_init_ops
);
1890 * Apply a multiplier adjustment to the timekeeper
1892 static __always_inline
void timekeeping_apply_adjustment(struct timekeeper
*tk
,
1896 s64 interval
= tk
->cycle_interval
;
1898 if (mult_adj
== 0) {
1900 } else if (mult_adj
== -1) {
1901 interval
= -interval
;
1903 } else if (mult_adj
!= 1) {
1904 interval
*= mult_adj
;
1909 * So the following can be confusing.
1911 * To keep things simple, lets assume mult_adj == 1 for now.
1913 * When mult_adj != 1, remember that the interval and offset values
1914 * have been appropriately scaled so the math is the same.
1916 * The basic idea here is that we're increasing the multiplier
1917 * by one, this causes the xtime_interval to be incremented by
1918 * one cycle_interval. This is because:
1919 * xtime_interval = cycle_interval * mult
1920 * So if mult is being incremented by one:
1921 * xtime_interval = cycle_interval * (mult + 1)
1923 * xtime_interval = (cycle_interval * mult) + cycle_interval
1924 * Which can be shortened to:
1925 * xtime_interval += cycle_interval
1927 * So offset stores the non-accumulated cycles. Thus the current
1928 * time (in shifted nanoseconds) is:
1929 * now = (offset * adj) + xtime_nsec
1930 * Now, even though we're adjusting the clock frequency, we have
1931 * to keep time consistent. In other words, we can't jump back
1932 * in time, and we also want to avoid jumping forward in time.
1934 * So given the same offset value, we need the time to be the same
1935 * both before and after the freq adjustment.
1936 * now = (offset * adj_1) + xtime_nsec_1
1937 * now = (offset * adj_2) + xtime_nsec_2
1939 * (offset * adj_1) + xtime_nsec_1 =
1940 * (offset * adj_2) + xtime_nsec_2
1944 * (offset * adj_1) + xtime_nsec_1 =
1945 * (offset * (adj_1+1)) + xtime_nsec_2
1946 * (offset * adj_1) + xtime_nsec_1 =
1947 * (offset * adj_1) + offset + xtime_nsec_2
1948 * Canceling the sides:
1949 * xtime_nsec_1 = offset + xtime_nsec_2
1951 * xtime_nsec_2 = xtime_nsec_1 - offset
1952 * Which simplfies to:
1953 * xtime_nsec -= offset
1955 if ((mult_adj
> 0) && (tk
->tkr_mono
.mult
+ mult_adj
< mult_adj
)) {
1956 /* NTP adjustment caused clocksource mult overflow */
1961 tk
->tkr_mono
.mult
+= mult_adj
;
1962 tk
->xtime_interval
+= interval
;
1963 tk
->tkr_mono
.xtime_nsec
-= offset
;
1967 * Adjust the timekeeper's multiplier to the correct frequency
1968 * and also to reduce the accumulated error value.
1970 static void timekeeping_adjust(struct timekeeper
*tk
, s64 offset
)
1975 * Determine the multiplier from the current NTP tick length.
1976 * Avoid expensive division when the tick length doesn't change.
1978 if (likely(tk
->ntp_tick
== ntp_tick_length())) {
1979 mult
= tk
->tkr_mono
.mult
- tk
->ntp_err_mult
;
1981 tk
->ntp_tick
= ntp_tick_length();
1982 mult
= div64_u64((tk
->ntp_tick
>> tk
->ntp_error_shift
) -
1983 tk
->xtime_remainder
, tk
->cycle_interval
);
1987 * If the clock is behind the NTP time, increase the multiplier by 1
1988 * to catch up with it. If it's ahead and there was a remainder in the
1989 * tick division, the clock will slow down. Otherwise it will stay
1990 * ahead until the tick length changes to a non-divisible value.
1992 tk
->ntp_err_mult
= tk
->ntp_error
> 0 ? 1 : 0;
1993 mult
+= tk
->ntp_err_mult
;
1995 timekeeping_apply_adjustment(tk
, offset
, mult
- tk
->tkr_mono
.mult
);
1997 if (unlikely(tk
->tkr_mono
.clock
->maxadj
&&
1998 (abs(tk
->tkr_mono
.mult
- tk
->tkr_mono
.clock
->mult
)
1999 > tk
->tkr_mono
.clock
->maxadj
))) {
2000 printk_once(KERN_WARNING
2001 "Adjusting %s more than 11%% (%ld vs %ld)\n",
2002 tk
->tkr_mono
.clock
->name
, (long)tk
->tkr_mono
.mult
,
2003 (long)tk
->tkr_mono
.clock
->mult
+ tk
->tkr_mono
.clock
->maxadj
);
2007 * It may be possible that when we entered this function, xtime_nsec
2008 * was very small. Further, if we're slightly speeding the clocksource
2009 * in the code above, its possible the required corrective factor to
2010 * xtime_nsec could cause it to underflow.
2012 * Now, since we have already accumulated the second and the NTP
2013 * subsystem has been notified via second_overflow(), we need to skip
2016 if (unlikely((s64
)tk
->tkr_mono
.xtime_nsec
< 0)) {
2017 tk
->tkr_mono
.xtime_nsec
+= (u64
)NSEC_PER_SEC
<<
2020 tk
->skip_second_overflow
= 1;
2025 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
2027 * Helper function that accumulates the nsecs greater than a second
2028 * from the xtime_nsec field to the xtime_secs field.
2029 * It also calls into the NTP code to handle leapsecond processing.
2031 static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper
*tk
)
2033 u64 nsecps
= (u64
)NSEC_PER_SEC
<< tk
->tkr_mono
.shift
;
2034 unsigned int clock_set
= 0;
2036 while (tk
->tkr_mono
.xtime_nsec
>= nsecps
) {
2039 tk
->tkr_mono
.xtime_nsec
-= nsecps
;
2043 * Skip NTP update if this second was accumulated before,
2044 * i.e. xtime_nsec underflowed in timekeeping_adjust()
2046 if (unlikely(tk
->skip_second_overflow
)) {
2047 tk
->skip_second_overflow
= 0;
2051 /* Figure out if its a leap sec and apply if needed */
2052 leap
= second_overflow(tk
->xtime_sec
);
2053 if (unlikely(leap
)) {
2054 struct timespec64 ts
;
2056 tk
->xtime_sec
+= leap
;
2060 tk_set_wall_to_mono(tk
,
2061 timespec64_sub(tk
->wall_to_monotonic
, ts
));
2063 __timekeeping_set_tai_offset(tk
, tk
->tai_offset
- leap
);
2065 clock_set
= TK_CLOCK_WAS_SET
;
2072 * logarithmic_accumulation - shifted accumulation of cycles
2074 * This functions accumulates a shifted interval of cycles into
2075 * a shifted interval nanoseconds. Allows for O(log) accumulation
2078 * Returns the unconsumed cycles.
2080 static u64
logarithmic_accumulation(struct timekeeper
*tk
, u64 offset
,
2081 u32 shift
, unsigned int *clock_set
)
2083 u64 interval
= tk
->cycle_interval
<< shift
;
2086 /* If the offset is smaller than a shifted interval, do nothing */
2087 if (offset
< interval
)
2090 /* Accumulate one shifted interval */
2092 tk
->tkr_mono
.cycle_last
+= interval
;
2093 tk
->tkr_raw
.cycle_last
+= interval
;
2095 tk
->tkr_mono
.xtime_nsec
+= tk
->xtime_interval
<< shift
;
2096 *clock_set
|= accumulate_nsecs_to_secs(tk
);
2098 /* Accumulate raw time */
2099 tk
->tkr_raw
.xtime_nsec
+= tk
->raw_interval
<< shift
;
2100 snsec_per_sec
= (u64
)NSEC_PER_SEC
<< tk
->tkr_raw
.shift
;
2101 while (tk
->tkr_raw
.xtime_nsec
>= snsec_per_sec
) {
2102 tk
->tkr_raw
.xtime_nsec
-= snsec_per_sec
;
2106 /* Accumulate error between NTP and clock interval */
2107 tk
->ntp_error
+= tk
->ntp_tick
<< shift
;
2108 tk
->ntp_error
-= (tk
->xtime_interval
+ tk
->xtime_remainder
) <<
2109 (tk
->ntp_error_shift
+ shift
);
2115 * timekeeping_advance - Updates the timekeeper to the current time and
2116 * current NTP tick length
2118 static void timekeeping_advance(enum timekeeping_adv_mode mode
)
2120 struct timekeeper
*real_tk
= &tk_core
.timekeeper
;
2121 struct timekeeper
*tk
= &shadow_timekeeper
;
2123 int shift
= 0, maxshift
;
2124 unsigned int clock_set
= 0;
2125 unsigned long flags
;
2127 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
2129 /* Make sure we're fully resumed: */
2130 if (unlikely(timekeeping_suspended
))
2133 offset
= clocksource_delta(tk_clock_read(&tk
->tkr_mono
),
2134 tk
->tkr_mono
.cycle_last
, tk
->tkr_mono
.mask
);
2136 /* Check if there's really nothing to do */
2137 if (offset
< real_tk
->cycle_interval
&& mode
== TK_ADV_TICK
)
2140 /* Do some additional sanity checking */
2141 timekeeping_check_update(tk
, offset
);
2144 * With NO_HZ we may have to accumulate many cycle_intervals
2145 * (think "ticks") worth of time at once. To do this efficiently,
2146 * we calculate the largest doubling multiple of cycle_intervals
2147 * that is smaller than the offset. We then accumulate that
2148 * chunk in one go, and then try to consume the next smaller
2151 shift
= ilog2(offset
) - ilog2(tk
->cycle_interval
);
2152 shift
= max(0, shift
);
2153 /* Bound shift to one less than what overflows tick_length */
2154 maxshift
= (64 - (ilog2(ntp_tick_length())+1)) - 1;
2155 shift
= min(shift
, maxshift
);
2156 while (offset
>= tk
->cycle_interval
) {
2157 offset
= logarithmic_accumulation(tk
, offset
, shift
,
2159 if (offset
< tk
->cycle_interval
<<shift
)
2163 /* Adjust the multiplier to correct NTP error */
2164 timekeeping_adjust(tk
, offset
);
2167 * Finally, make sure that after the rounding
2168 * xtime_nsec isn't larger than NSEC_PER_SEC
2170 clock_set
|= accumulate_nsecs_to_secs(tk
);
2172 write_seqcount_begin(&tk_core
.seq
);
2174 * Update the real timekeeper.
2176 * We could avoid this memcpy by switching pointers, but that
2177 * requires changes to all other timekeeper usage sites as
2178 * well, i.e. move the timekeeper pointer getter into the
2179 * spinlocked/seqcount protected sections. And we trade this
2180 * memcpy under the tk_core.seq against one before we start
2183 timekeeping_update(tk
, clock_set
);
2184 memcpy(real_tk
, tk
, sizeof(*tk
));
2185 /* The memcpy must come last. Do not put anything here! */
2186 write_seqcount_end(&tk_core
.seq
);
2188 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
2190 /* Have to call _delayed version, since in irq context*/
2191 clock_was_set_delayed();
2195 * update_wall_time - Uses the current clocksource to increment the wall time
2198 void update_wall_time(void)
2200 timekeeping_advance(TK_ADV_TICK
);
2204 * getboottime64 - Return the real time of system boot.
2205 * @ts: pointer to the timespec64 to be set
2207 * Returns the wall-time of boot in a timespec64.
2209 * This is based on the wall_to_monotonic offset and the total suspend
2210 * time. Calls to settimeofday will affect the value returned (which
2211 * basically means that however wrong your real time clock is at boot time,
2212 * you get the right time here).
2214 void getboottime64(struct timespec64
*ts
)
2216 struct timekeeper
*tk
= &tk_core
.timekeeper
;
2217 ktime_t t
= ktime_sub(tk
->offs_real
, tk
->offs_boot
);
2219 *ts
= ktime_to_timespec64(t
);
2221 EXPORT_SYMBOL_GPL(getboottime64
);
2223 void ktime_get_coarse_real_ts64(struct timespec64
*ts
)
2225 struct timekeeper
*tk
= &tk_core
.timekeeper
;
2229 seq
= read_seqcount_begin(&tk_core
.seq
);
2232 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
2234 EXPORT_SYMBOL(ktime_get_coarse_real_ts64
);
2236 void ktime_get_coarse_ts64(struct timespec64
*ts
)
2238 struct timekeeper
*tk
= &tk_core
.timekeeper
;
2239 struct timespec64 now
, mono
;
2243 seq
= read_seqcount_begin(&tk_core
.seq
);
2246 mono
= tk
->wall_to_monotonic
;
2247 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
2249 set_normalized_timespec64(ts
, now
.tv_sec
+ mono
.tv_sec
,
2250 now
.tv_nsec
+ mono
.tv_nsec
);
2252 EXPORT_SYMBOL(ktime_get_coarse_ts64
);
2255 * Must hold jiffies_lock
2257 void do_timer(unsigned long ticks
)
2259 jiffies_64
+= ticks
;
2264 * ktime_get_update_offsets_now - hrtimer helper
2265 * @cwsseq: pointer to check and store the clock was set sequence number
2266 * @offs_real: pointer to storage for monotonic -> realtime offset
2267 * @offs_boot: pointer to storage for monotonic -> boottime offset
2268 * @offs_tai: pointer to storage for monotonic -> clock tai offset
2270 * Returns current monotonic time and updates the offsets if the
2271 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2274 * Called from hrtimer_interrupt() or retrigger_next_event()
2276 ktime_t
ktime_get_update_offsets_now(unsigned int *cwsseq
, ktime_t
*offs_real
,
2277 ktime_t
*offs_boot
, ktime_t
*offs_tai
)
2279 struct timekeeper
*tk
= &tk_core
.timekeeper
;
2285 seq
= read_seqcount_begin(&tk_core
.seq
);
2287 base
= tk
->tkr_mono
.base
;
2288 nsecs
= timekeeping_get_ns(&tk
->tkr_mono
);
2289 base
= ktime_add_ns(base
, nsecs
);
2291 if (*cwsseq
!= tk
->clock_was_set_seq
) {
2292 *cwsseq
= tk
->clock_was_set_seq
;
2293 *offs_real
= tk
->offs_real
;
2294 *offs_boot
= tk
->offs_boot
;
2295 *offs_tai
= tk
->offs_tai
;
2298 /* Handle leapsecond insertion adjustments */
2299 if (unlikely(base
>= tk
->next_leap_ktime
))
2300 *offs_real
= ktime_sub(tk
->offs_real
, ktime_set(1, 0));
2302 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
2308 * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2310 static int timekeeping_validate_timex(const struct __kernel_timex
*txc
)
2312 if (txc
->modes
& ADJ_ADJTIME
) {
2313 /* singleshot must not be used with any other mode bits */
2314 if (!(txc
->modes
& ADJ_OFFSET_SINGLESHOT
))
2316 if (!(txc
->modes
& ADJ_OFFSET_READONLY
) &&
2317 !capable(CAP_SYS_TIME
))
2320 /* In order to modify anything, you gotta be super-user! */
2321 if (txc
->modes
&& !capable(CAP_SYS_TIME
))
2324 * if the quartz is off by more than 10% then
2325 * something is VERY wrong!
2327 if (txc
->modes
& ADJ_TICK
&&
2328 (txc
->tick
< 900000/USER_HZ
||
2329 txc
->tick
> 1100000/USER_HZ
))
2333 if (txc
->modes
& ADJ_SETOFFSET
) {
2334 /* In order to inject time, you gotta be super-user! */
2335 if (!capable(CAP_SYS_TIME
))
2339 * Validate if a timespec/timeval used to inject a time
2340 * offset is valid. Offsets can be postive or negative, so
2341 * we don't check tv_sec. The value of the timeval/timespec
2342 * is the sum of its fields,but *NOTE*:
2343 * The field tv_usec/tv_nsec must always be non-negative and
2344 * we can't have more nanoseconds/microseconds than a second.
2346 if (txc
->time
.tv_usec
< 0)
2349 if (txc
->modes
& ADJ_NANO
) {
2350 if (txc
->time
.tv_usec
>= NSEC_PER_SEC
)
2353 if (txc
->time
.tv_usec
>= USEC_PER_SEC
)
2359 * Check for potential multiplication overflows that can
2360 * only happen on 64-bit systems:
2362 if ((txc
->modes
& ADJ_FREQUENCY
) && (BITS_PER_LONG
== 64)) {
2363 if (LLONG_MIN
/ PPM_SCALE
> txc
->freq
)
2365 if (LLONG_MAX
/ PPM_SCALE
< txc
->freq
)
2374 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2376 int do_adjtimex(struct __kernel_timex
*txc
)
2378 struct timekeeper
*tk
= &tk_core
.timekeeper
;
2379 struct audit_ntp_data ad
;
2380 unsigned long flags
;
2381 struct timespec64 ts
;
2385 /* Validate the data before disabling interrupts */
2386 ret
= timekeeping_validate_timex(txc
);
2390 if (txc
->modes
& ADJ_SETOFFSET
) {
2391 struct timespec64 delta
;
2392 delta
.tv_sec
= txc
->time
.tv_sec
;
2393 delta
.tv_nsec
= txc
->time
.tv_usec
;
2394 if (!(txc
->modes
& ADJ_NANO
))
2395 delta
.tv_nsec
*= 1000;
2396 ret
= timekeeping_inject_offset(&delta
);
2400 audit_tk_injoffset(delta
);
2403 audit_ntp_init(&ad
);
2405 ktime_get_real_ts64(&ts
);
2407 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
2408 write_seqcount_begin(&tk_core
.seq
);
2410 orig_tai
= tai
= tk
->tai_offset
;
2411 ret
= __do_adjtimex(txc
, &ts
, &tai
, &ad
);
2413 if (tai
!= orig_tai
) {
2414 __timekeeping_set_tai_offset(tk
, tai
);
2415 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
2417 tk_update_leap_state(tk
);
2419 write_seqcount_end(&tk_core
.seq
);
2420 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
2424 /* Update the multiplier immediately if frequency was set directly */
2425 if (txc
->modes
& (ADJ_FREQUENCY
| ADJ_TICK
))
2426 timekeeping_advance(TK_ADV_FREQ
);
2428 if (tai
!= orig_tai
)
2431 ntp_notify_cmos_timer();
2436 #ifdef CONFIG_NTP_PPS
2438 * hardpps() - Accessor function to NTP __hardpps function
2440 void hardpps(const struct timespec64
*phase_ts
, const struct timespec64
*raw_ts
)
2442 unsigned long flags
;
2444 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
2445 write_seqcount_begin(&tk_core
.seq
);
2447 __hardpps(phase_ts
, raw_ts
);
2449 write_seqcount_end(&tk_core
.seq
);
2450 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
2452 EXPORT_SYMBOL(hardpps
);
2453 #endif /* CONFIG_NTP_PPS */