2 * linux/kernel/time/timekeeping.c
4 * Kernel timekeeping code and accessor functions
6 * This code was moved from linux/kernel/timer.c.
7 * Please see that file for copyright and history logs.
11 #include <linux/timekeeper_internal.h>
12 #include <linux/module.h>
13 #include <linux/interrupt.h>
14 #include <linux/percpu.h>
15 #include <linux/init.h>
17 #include <linux/sched.h>
18 #include <linux/syscore_ops.h>
19 #include <linux/clocksource.h>
20 #include <linux/jiffies.h>
21 #include <linux/time.h>
22 #include <linux/tick.h>
23 #include <linux/stop_machine.h>
24 #include <linux/pvclock_gtod.h>
25 #include <linux/compiler.h>
27 #include "tick-internal.h"
28 #include "ntp_internal.h"
29 #include "timekeeping_internal.h"
31 #define TK_CLEAR_NTP (1 << 0)
32 #define TK_MIRROR (1 << 1)
33 #define TK_CLOCK_WAS_SET (1 << 2)
36 * The most important data for readout fits into a single 64 byte
41 struct timekeeper timekeeper
;
42 } tk_core ____cacheline_aligned
;
44 static DEFINE_RAW_SPINLOCK(timekeeper_lock
);
45 static struct timekeeper shadow_timekeeper
;
48 * struct tk_fast - NMI safe timekeeper
49 * @seq: Sequence counter for protecting updates. The lowest bit
50 * is the index for the tk_read_base array
51 * @base: tk_read_base array. Access is indexed by the lowest bit of
54 * See @update_fast_timekeeper() below.
58 struct tk_read_base base
[2];
61 static struct tk_fast tk_fast_mono ____cacheline_aligned
;
63 /* flag for if timekeeping is suspended */
64 int __read_mostly timekeeping_suspended
;
66 /* Flag for if there is a persistent clock on this platform */
67 bool __read_mostly persistent_clock_exist
= false;
69 static inline void tk_normalize_xtime(struct timekeeper
*tk
)
71 while (tk
->tkr
.xtime_nsec
>= ((u64
)NSEC_PER_SEC
<< tk
->tkr
.shift
)) {
72 tk
->tkr
.xtime_nsec
-= (u64
)NSEC_PER_SEC
<< tk
->tkr
.shift
;
77 static inline struct timespec64
tk_xtime(struct timekeeper
*tk
)
81 ts
.tv_sec
= tk
->xtime_sec
;
82 ts
.tv_nsec
= (long)(tk
->tkr
.xtime_nsec
>> tk
->tkr
.shift
);
86 static void tk_set_xtime(struct timekeeper
*tk
, const struct timespec64
*ts
)
88 tk
->xtime_sec
= ts
->tv_sec
;
89 tk
->tkr
.xtime_nsec
= (u64
)ts
->tv_nsec
<< tk
->tkr
.shift
;
92 static void tk_xtime_add(struct timekeeper
*tk
, const struct timespec64
*ts
)
94 tk
->xtime_sec
+= ts
->tv_sec
;
95 tk
->tkr
.xtime_nsec
+= (u64
)ts
->tv_nsec
<< tk
->tkr
.shift
;
96 tk_normalize_xtime(tk
);
99 static void tk_set_wall_to_mono(struct timekeeper
*tk
, struct timespec64 wtm
)
101 struct timespec64 tmp
;
104 * Verify consistency of: offset_real = -wall_to_monotonic
105 * before modifying anything
107 set_normalized_timespec64(&tmp
, -tk
->wall_to_monotonic
.tv_sec
,
108 -tk
->wall_to_monotonic
.tv_nsec
);
109 WARN_ON_ONCE(tk
->offs_real
.tv64
!= timespec64_to_ktime(tmp
).tv64
);
110 tk
->wall_to_monotonic
= wtm
;
111 set_normalized_timespec64(&tmp
, -wtm
.tv_sec
, -wtm
.tv_nsec
);
112 tk
->offs_real
= timespec64_to_ktime(tmp
);
113 tk
->offs_tai
= ktime_add(tk
->offs_real
, ktime_set(tk
->tai_offset
, 0));
116 static inline void tk_update_sleep_time(struct timekeeper
*tk
, ktime_t delta
)
118 tk
->offs_boot
= ktime_add(tk
->offs_boot
, delta
);
121 #ifdef CONFIG_DEBUG_TIMEKEEPING
122 static void timekeeping_check_update(struct timekeeper
*tk
, cycle_t offset
)
125 cycle_t max_cycles
= tk
->tkr
.clock
->max_cycles
;
126 const char *name
= tk
->tkr
.clock
->name
;
128 if (offset
> max_cycles
) {
129 printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
130 offset
, name
, max_cycles
);
131 printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
133 if (offset
> (max_cycles
>> 1)) {
134 printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the the '%s' clock's 50%% safety margin (%lld)\n",
135 offset
, name
, max_cycles
>> 1);
136 printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
141 static inline cycle_t
timekeeping_get_delta(struct tk_read_base
*tkr
)
143 cycle_t cycle_now
, delta
;
145 /* read clocksource */
146 cycle_now
= tkr
->read(tkr
->clock
);
148 /* calculate the delta since the last update_wall_time */
149 delta
= clocksource_delta(cycle_now
, tkr
->cycle_last
, tkr
->mask
);
151 /* Cap delta value to the max_cycles values to avoid mult overflows */
152 if (unlikely(delta
> tkr
->clock
->max_cycles
))
153 delta
= tkr
->clock
->max_cycles
;
158 static inline void timekeeping_check_update(struct timekeeper
*tk
, cycle_t offset
)
161 static inline cycle_t
timekeeping_get_delta(struct tk_read_base
*tkr
)
163 cycle_t cycle_now
, delta
;
165 /* read clocksource */
166 cycle_now
= tkr
->read(tkr
->clock
);
168 /* calculate the delta since the last update_wall_time */
169 delta
= clocksource_delta(cycle_now
, tkr
->cycle_last
, tkr
->mask
);
176 * tk_setup_internals - Set up internals to use clocksource clock.
178 * @tk: The target timekeeper to setup.
179 * @clock: Pointer to clocksource.
181 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
182 * pair and interval request.
184 * Unless you're the timekeeping code, you should not be using this!
186 static void tk_setup_internals(struct timekeeper
*tk
, struct clocksource
*clock
)
189 u64 tmp
, ntpinterval
;
190 struct clocksource
*old_clock
;
192 old_clock
= tk
->tkr
.clock
;
193 tk
->tkr
.clock
= clock
;
194 tk
->tkr
.read
= clock
->read
;
195 tk
->tkr
.mask
= clock
->mask
;
196 tk
->tkr
.cycle_last
= tk
->tkr
.read(clock
);
198 /* Do the ns -> cycle conversion first, using original mult */
199 tmp
= NTP_INTERVAL_LENGTH
;
200 tmp
<<= clock
->shift
;
202 tmp
+= clock
->mult
/2;
203 do_div(tmp
, clock
->mult
);
207 interval
= (cycle_t
) tmp
;
208 tk
->cycle_interval
= interval
;
210 /* Go back from cycles -> shifted ns */
211 tk
->xtime_interval
= (u64
) interval
* clock
->mult
;
212 tk
->xtime_remainder
= ntpinterval
- tk
->xtime_interval
;
214 ((u64
) interval
* clock
->mult
) >> clock
->shift
;
216 /* if changing clocks, convert xtime_nsec shift units */
218 int shift_change
= clock
->shift
- old_clock
->shift
;
219 if (shift_change
< 0)
220 tk
->tkr
.xtime_nsec
>>= -shift_change
;
222 tk
->tkr
.xtime_nsec
<<= shift_change
;
224 tk
->tkr
.shift
= clock
->shift
;
227 tk
->ntp_error_shift
= NTP_SCALE_SHIFT
- clock
->shift
;
228 tk
->ntp_tick
= ntpinterval
<< tk
->ntp_error_shift
;
231 * The timekeeper keeps its own mult values for the currently
232 * active clocksource. These value will be adjusted via NTP
233 * to counteract clock drifting.
235 tk
->tkr
.mult
= clock
->mult
;
236 tk
->ntp_err_mult
= 0;
239 /* Timekeeper helper functions. */
241 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
242 static u32
default_arch_gettimeoffset(void) { return 0; }
243 u32 (*arch_gettimeoffset
)(void) = default_arch_gettimeoffset
;
245 static inline u32
arch_gettimeoffset(void) { return 0; }
248 static inline s64
timekeeping_get_ns(struct tk_read_base
*tkr
)
253 delta
= timekeeping_get_delta(tkr
);
255 nsec
= delta
* tkr
->mult
+ tkr
->xtime_nsec
;
258 /* If arch requires, add in get_arch_timeoffset() */
259 return nsec
+ arch_gettimeoffset();
262 static inline s64
timekeeping_get_ns_raw(struct timekeeper
*tk
)
264 struct clocksource
*clock
= tk
->tkr
.clock
;
268 delta
= timekeeping_get_delta(&tk
->tkr
);
270 /* convert delta to nanoseconds. */
271 nsec
= clocksource_cyc2ns(delta
, clock
->mult
, clock
->shift
);
273 /* If arch requires, add in get_arch_timeoffset() */
274 return nsec
+ arch_gettimeoffset();
278 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
279 * @tkr: Timekeeping readout base from which we take the update
281 * We want to use this from any context including NMI and tracing /
282 * instrumenting the timekeeping code itself.
284 * So we handle this differently than the other timekeeping accessor
285 * functions which retry when the sequence count has changed. The
288 * smp_wmb(); <- Ensure that the last base[1] update is visible
290 * smp_wmb(); <- Ensure that the seqcount update is visible
291 * update(tkf->base[0], tkr);
292 * smp_wmb(); <- Ensure that the base[0] update is visible
294 * smp_wmb(); <- Ensure that the seqcount update is visible
295 * update(tkf->base[1], tkr);
297 * The reader side does:
303 * now = now(tkf->base[idx]);
305 * } while (seq != tkf->seq)
307 * As long as we update base[0] readers are forced off to
308 * base[1]. Once base[0] is updated readers are redirected to base[0]
309 * and the base[1] update takes place.
311 * So if a NMI hits the update of base[0] then it will use base[1]
312 * which is still consistent. In the worst case this can result is a
313 * slightly wrong timestamp (a few nanoseconds). See
314 * @ktime_get_mono_fast_ns.
316 static void update_fast_timekeeper(struct tk_read_base
*tkr
)
318 struct tk_read_base
*base
= tk_fast_mono
.base
;
320 /* Force readers off to base[1] */
321 raw_write_seqcount_latch(&tk_fast_mono
.seq
);
324 memcpy(base
, tkr
, sizeof(*base
));
326 /* Force readers back to base[0] */
327 raw_write_seqcount_latch(&tk_fast_mono
.seq
);
330 memcpy(base
+ 1, base
, sizeof(*base
));
334 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
336 * This timestamp is not guaranteed to be monotonic across an update.
337 * The timestamp is calculated by:
339 * now = base_mono + clock_delta * slope
341 * So if the update lowers the slope, readers who are forced to the
342 * not yet updated second array are still using the old steeper slope.
351 * |12345678---> reader order
357 * So reader 6 will observe time going backwards versus reader 5.
359 * While other CPUs are likely to be able observe that, the only way
360 * for a CPU local observation is when an NMI hits in the middle of
361 * the update. Timestamps taken from that NMI context might be ahead
362 * of the following timestamps. Callers need to be aware of that and
365 u64 notrace
ktime_get_mono_fast_ns(void)
367 struct tk_read_base
*tkr
;
372 seq
= raw_read_seqcount(&tk_fast_mono
.seq
);
373 tkr
= tk_fast_mono
.base
+ (seq
& 0x01);
374 now
= ktime_to_ns(tkr
->base_mono
) + timekeeping_get_ns(tkr
);
376 } while (read_seqcount_retry(&tk_fast_mono
.seq
, seq
));
379 EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns
);
381 /* Suspend-time cycles value for halted fast timekeeper. */
382 static cycle_t cycles_at_suspend
;
384 static cycle_t
dummy_clock_read(struct clocksource
*cs
)
386 return cycles_at_suspend
;
390 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
391 * @tk: Timekeeper to snapshot.
393 * It generally is unsafe to access the clocksource after timekeeping has been
394 * suspended, so take a snapshot of the readout base of @tk and use it as the
395 * fast timekeeper's readout base while suspended. It will return the same
396 * number of cycles every time until timekeeping is resumed at which time the
397 * proper readout base for the fast timekeeper will be restored automatically.
399 static void halt_fast_timekeeper(struct timekeeper
*tk
)
401 static struct tk_read_base tkr_dummy
;
402 struct tk_read_base
*tkr
= &tk
->tkr
;
404 memcpy(&tkr_dummy
, tkr
, sizeof(tkr_dummy
));
405 cycles_at_suspend
= tkr
->read(tkr
->clock
);
406 tkr_dummy
.read
= dummy_clock_read
;
407 update_fast_timekeeper(&tkr_dummy
);
410 #ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
412 static inline void update_vsyscall(struct timekeeper
*tk
)
414 struct timespec xt
, wm
;
416 xt
= timespec64_to_timespec(tk_xtime(tk
));
417 wm
= timespec64_to_timespec(tk
->wall_to_monotonic
);
418 update_vsyscall_old(&xt
, &wm
, tk
->tkr
.clock
, tk
->tkr
.mult
,
422 static inline void old_vsyscall_fixup(struct timekeeper
*tk
)
427 * Store only full nanoseconds into xtime_nsec after rounding
428 * it up and add the remainder to the error difference.
429 * XXX - This is necessary to avoid small 1ns inconsistnecies caused
430 * by truncating the remainder in vsyscalls. However, it causes
431 * additional work to be done in timekeeping_adjust(). Once
432 * the vsyscall implementations are converted to use xtime_nsec
433 * (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
434 * users are removed, this can be killed.
436 remainder
= tk
->tkr
.xtime_nsec
& ((1ULL << tk
->tkr
.shift
) - 1);
437 tk
->tkr
.xtime_nsec
-= remainder
;
438 tk
->tkr
.xtime_nsec
+= 1ULL << tk
->tkr
.shift
;
439 tk
->ntp_error
+= remainder
<< tk
->ntp_error_shift
;
440 tk
->ntp_error
-= (1ULL << tk
->tkr
.shift
) << tk
->ntp_error_shift
;
443 #define old_vsyscall_fixup(tk)
446 static RAW_NOTIFIER_HEAD(pvclock_gtod_chain
);
448 static void update_pvclock_gtod(struct timekeeper
*tk
, bool was_set
)
450 raw_notifier_call_chain(&pvclock_gtod_chain
, was_set
, tk
);
454 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
456 int pvclock_gtod_register_notifier(struct notifier_block
*nb
)
458 struct timekeeper
*tk
= &tk_core
.timekeeper
;
462 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
463 ret
= raw_notifier_chain_register(&pvclock_gtod_chain
, nb
);
464 update_pvclock_gtod(tk
, true);
465 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
469 EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier
);
472 * pvclock_gtod_unregister_notifier - unregister a pvclock
473 * timedata update listener
475 int pvclock_gtod_unregister_notifier(struct notifier_block
*nb
)
480 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
481 ret
= raw_notifier_chain_unregister(&pvclock_gtod_chain
, nb
);
482 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
486 EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier
);
489 * Update the ktime_t based scalar nsec members of the timekeeper
491 static inline void tk_update_ktime_data(struct timekeeper
*tk
)
497 * The xtime based monotonic readout is:
498 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
499 * The ktime based monotonic readout is:
500 * nsec = base_mono + now();
501 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
503 seconds
= (u64
)(tk
->xtime_sec
+ tk
->wall_to_monotonic
.tv_sec
);
504 nsec
= (u32
) tk
->wall_to_monotonic
.tv_nsec
;
505 tk
->tkr
.base_mono
= ns_to_ktime(seconds
* NSEC_PER_SEC
+ nsec
);
507 /* Update the monotonic raw base */
508 tk
->base_raw
= timespec64_to_ktime(tk
->raw_time
);
511 * The sum of the nanoseconds portions of xtime and
512 * wall_to_monotonic can be greater/equal one second. Take
513 * this into account before updating tk->ktime_sec.
515 nsec
+= (u32
)(tk
->tkr
.xtime_nsec
>> tk
->tkr
.shift
);
516 if (nsec
>= NSEC_PER_SEC
)
518 tk
->ktime_sec
= seconds
;
521 /* must hold timekeeper_lock */
522 static void timekeeping_update(struct timekeeper
*tk
, unsigned int action
)
524 if (action
& TK_CLEAR_NTP
) {
529 tk_update_ktime_data(tk
);
532 update_pvclock_gtod(tk
, action
& TK_CLOCK_WAS_SET
);
534 if (action
& TK_MIRROR
)
535 memcpy(&shadow_timekeeper
, &tk_core
.timekeeper
,
536 sizeof(tk_core
.timekeeper
));
538 update_fast_timekeeper(&tk
->tkr
);
542 * timekeeping_forward_now - update clock to the current time
544 * Forward the current clock to update its state since the last call to
545 * update_wall_time(). This is useful before significant clock changes,
546 * as it avoids having to deal with this time offset explicitly.
548 static void timekeeping_forward_now(struct timekeeper
*tk
)
550 struct clocksource
*clock
= tk
->tkr
.clock
;
551 cycle_t cycle_now
, delta
;
554 cycle_now
= tk
->tkr
.read(clock
);
555 delta
= clocksource_delta(cycle_now
, tk
->tkr
.cycle_last
, tk
->tkr
.mask
);
556 tk
->tkr
.cycle_last
= cycle_now
;
558 tk
->tkr
.xtime_nsec
+= delta
* tk
->tkr
.mult
;
560 /* If arch requires, add in get_arch_timeoffset() */
561 tk
->tkr
.xtime_nsec
+= (u64
)arch_gettimeoffset() << tk
->tkr
.shift
;
563 tk_normalize_xtime(tk
);
565 nsec
= clocksource_cyc2ns(delta
, clock
->mult
, clock
->shift
);
566 timespec64_add_ns(&tk
->raw_time
, nsec
);
570 * __getnstimeofday64 - Returns the time of day in a timespec64.
571 * @ts: pointer to the timespec to be set
573 * Updates the time of day in the timespec.
574 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
576 int __getnstimeofday64(struct timespec64
*ts
)
578 struct timekeeper
*tk
= &tk_core
.timekeeper
;
583 seq
= read_seqcount_begin(&tk_core
.seq
);
585 ts
->tv_sec
= tk
->xtime_sec
;
586 nsecs
= timekeeping_get_ns(&tk
->tkr
);
588 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
591 timespec64_add_ns(ts
, nsecs
);
594 * Do not bail out early, in case there were callers still using
595 * the value, even in the face of the WARN_ON.
597 if (unlikely(timekeeping_suspended
))
601 EXPORT_SYMBOL(__getnstimeofday64
);
604 * getnstimeofday64 - Returns the time of day in a timespec64.
605 * @ts: pointer to the timespec64 to be set
607 * Returns the time of day in a timespec64 (WARN if suspended).
609 void getnstimeofday64(struct timespec64
*ts
)
611 WARN_ON(__getnstimeofday64(ts
));
613 EXPORT_SYMBOL(getnstimeofday64
);
615 ktime_t
ktime_get(void)
617 struct timekeeper
*tk
= &tk_core
.timekeeper
;
622 WARN_ON(timekeeping_suspended
);
625 seq
= read_seqcount_begin(&tk_core
.seq
);
626 base
= tk
->tkr
.base_mono
;
627 nsecs
= timekeeping_get_ns(&tk
->tkr
);
629 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
631 return ktime_add_ns(base
, nsecs
);
633 EXPORT_SYMBOL_GPL(ktime_get
);
635 static ktime_t
*offsets
[TK_OFFS_MAX
] = {
636 [TK_OFFS_REAL
] = &tk_core
.timekeeper
.offs_real
,
637 [TK_OFFS_BOOT
] = &tk_core
.timekeeper
.offs_boot
,
638 [TK_OFFS_TAI
] = &tk_core
.timekeeper
.offs_tai
,
641 ktime_t
ktime_get_with_offset(enum tk_offsets offs
)
643 struct timekeeper
*tk
= &tk_core
.timekeeper
;
645 ktime_t base
, *offset
= offsets
[offs
];
648 WARN_ON(timekeeping_suspended
);
651 seq
= read_seqcount_begin(&tk_core
.seq
);
652 base
= ktime_add(tk
->tkr
.base_mono
, *offset
);
653 nsecs
= timekeeping_get_ns(&tk
->tkr
);
655 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
657 return ktime_add_ns(base
, nsecs
);
660 EXPORT_SYMBOL_GPL(ktime_get_with_offset
);
663 * ktime_mono_to_any() - convert mononotic time to any other time
664 * @tmono: time to convert.
665 * @offs: which offset to use
667 ktime_t
ktime_mono_to_any(ktime_t tmono
, enum tk_offsets offs
)
669 ktime_t
*offset
= offsets
[offs
];
674 seq
= read_seqcount_begin(&tk_core
.seq
);
675 tconv
= ktime_add(tmono
, *offset
);
676 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
680 EXPORT_SYMBOL_GPL(ktime_mono_to_any
);
683 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
685 ktime_t
ktime_get_raw(void)
687 struct timekeeper
*tk
= &tk_core
.timekeeper
;
693 seq
= read_seqcount_begin(&tk_core
.seq
);
695 nsecs
= timekeeping_get_ns_raw(tk
);
697 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
699 return ktime_add_ns(base
, nsecs
);
701 EXPORT_SYMBOL_GPL(ktime_get_raw
);
704 * ktime_get_ts64 - get the monotonic clock in timespec64 format
705 * @ts: pointer to timespec variable
707 * The function calculates the monotonic clock from the realtime
708 * clock and the wall_to_monotonic offset and stores the result
709 * in normalized timespec64 format in the variable pointed to by @ts.
711 void ktime_get_ts64(struct timespec64
*ts
)
713 struct timekeeper
*tk
= &tk_core
.timekeeper
;
714 struct timespec64 tomono
;
718 WARN_ON(timekeeping_suspended
);
721 seq
= read_seqcount_begin(&tk_core
.seq
);
722 ts
->tv_sec
= tk
->xtime_sec
;
723 nsec
= timekeeping_get_ns(&tk
->tkr
);
724 tomono
= tk
->wall_to_monotonic
;
726 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
728 ts
->tv_sec
+= tomono
.tv_sec
;
730 timespec64_add_ns(ts
, nsec
+ tomono
.tv_nsec
);
732 EXPORT_SYMBOL_GPL(ktime_get_ts64
);
735 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
737 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
738 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
739 * works on both 32 and 64 bit systems. On 32 bit systems the readout
740 * covers ~136 years of uptime which should be enough to prevent
741 * premature wrap arounds.
743 time64_t
ktime_get_seconds(void)
745 struct timekeeper
*tk
= &tk_core
.timekeeper
;
747 WARN_ON(timekeeping_suspended
);
748 return tk
->ktime_sec
;
750 EXPORT_SYMBOL_GPL(ktime_get_seconds
);
753 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
755 * Returns the wall clock seconds since 1970. This replaces the
756 * get_seconds() interface which is not y2038 safe on 32bit systems.
758 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
759 * 32bit systems the access must be protected with the sequence
760 * counter to provide "atomic" access to the 64bit tk->xtime_sec
763 time64_t
ktime_get_real_seconds(void)
765 struct timekeeper
*tk
= &tk_core
.timekeeper
;
769 if (IS_ENABLED(CONFIG_64BIT
))
770 return tk
->xtime_sec
;
773 seq
= read_seqcount_begin(&tk_core
.seq
);
774 seconds
= tk
->xtime_sec
;
776 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
780 EXPORT_SYMBOL_GPL(ktime_get_real_seconds
);
782 #ifdef CONFIG_NTP_PPS
785 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
786 * @ts_raw: pointer to the timespec to be set to raw monotonic time
787 * @ts_real: pointer to the timespec to be set to the time of day
789 * This function reads both the time of day and raw monotonic time at the
790 * same time atomically and stores the resulting timestamps in timespec
793 void getnstime_raw_and_real(struct timespec
*ts_raw
, struct timespec
*ts_real
)
795 struct timekeeper
*tk
= &tk_core
.timekeeper
;
797 s64 nsecs_raw
, nsecs_real
;
799 WARN_ON_ONCE(timekeeping_suspended
);
802 seq
= read_seqcount_begin(&tk_core
.seq
);
804 *ts_raw
= timespec64_to_timespec(tk
->raw_time
);
805 ts_real
->tv_sec
= tk
->xtime_sec
;
806 ts_real
->tv_nsec
= 0;
808 nsecs_raw
= timekeeping_get_ns_raw(tk
);
809 nsecs_real
= timekeeping_get_ns(&tk
->tkr
);
811 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
813 timespec_add_ns(ts_raw
, nsecs_raw
);
814 timespec_add_ns(ts_real
, nsecs_real
);
816 EXPORT_SYMBOL(getnstime_raw_and_real
);
818 #endif /* CONFIG_NTP_PPS */
821 * do_gettimeofday - Returns the time of day in a timeval
822 * @tv: pointer to the timeval to be set
824 * NOTE: Users should be converted to using getnstimeofday()
826 void do_gettimeofday(struct timeval
*tv
)
828 struct timespec64 now
;
830 getnstimeofday64(&now
);
831 tv
->tv_sec
= now
.tv_sec
;
832 tv
->tv_usec
= now
.tv_nsec
/1000;
834 EXPORT_SYMBOL(do_gettimeofday
);
837 * do_settimeofday64 - Sets the time of day.
838 * @ts: pointer to the timespec64 variable containing the new time
840 * Sets the time of day to the new time and update NTP and notify hrtimers
842 int do_settimeofday64(const struct timespec64
*ts
)
844 struct timekeeper
*tk
= &tk_core
.timekeeper
;
845 struct timespec64 ts_delta
, xt
;
848 if (!timespec64_valid_strict(ts
))
851 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
852 write_seqcount_begin(&tk_core
.seq
);
854 timekeeping_forward_now(tk
);
857 ts_delta
.tv_sec
= ts
->tv_sec
- xt
.tv_sec
;
858 ts_delta
.tv_nsec
= ts
->tv_nsec
- xt
.tv_nsec
;
860 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, ts_delta
));
862 tk_set_xtime(tk
, ts
);
864 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
866 write_seqcount_end(&tk_core
.seq
);
867 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
869 /* signal hrtimers about time change */
874 EXPORT_SYMBOL(do_settimeofday64
);
877 * timekeeping_inject_offset - Adds or subtracts from the current time.
878 * @tv: pointer to the timespec variable containing the offset
880 * Adds or subtracts an offset value from the current time.
882 int timekeeping_inject_offset(struct timespec
*ts
)
884 struct timekeeper
*tk
= &tk_core
.timekeeper
;
886 struct timespec64 ts64
, tmp
;
889 if ((unsigned long)ts
->tv_nsec
>= NSEC_PER_SEC
)
892 ts64
= timespec_to_timespec64(*ts
);
894 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
895 write_seqcount_begin(&tk_core
.seq
);
897 timekeeping_forward_now(tk
);
899 /* Make sure the proposed value is valid */
900 tmp
= timespec64_add(tk_xtime(tk
), ts64
);
901 if (!timespec64_valid_strict(&tmp
)) {
906 tk_xtime_add(tk
, &ts64
);
907 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, ts64
));
909 error
: /* even if we error out, we forwarded the time, so call update */
910 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
912 write_seqcount_end(&tk_core
.seq
);
913 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
915 /* signal hrtimers about time change */
920 EXPORT_SYMBOL(timekeeping_inject_offset
);
924 * timekeeping_get_tai_offset - Returns current TAI offset from UTC
927 s32
timekeeping_get_tai_offset(void)
929 struct timekeeper
*tk
= &tk_core
.timekeeper
;
934 seq
= read_seqcount_begin(&tk_core
.seq
);
935 ret
= tk
->tai_offset
;
936 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
942 * __timekeeping_set_tai_offset - Lock free worker function
945 static void __timekeeping_set_tai_offset(struct timekeeper
*tk
, s32 tai_offset
)
947 tk
->tai_offset
= tai_offset
;
948 tk
->offs_tai
= ktime_add(tk
->offs_real
, ktime_set(tai_offset
, 0));
952 * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
955 void timekeeping_set_tai_offset(s32 tai_offset
)
957 struct timekeeper
*tk
= &tk_core
.timekeeper
;
960 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
961 write_seqcount_begin(&tk_core
.seq
);
962 __timekeeping_set_tai_offset(tk
, tai_offset
);
963 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
964 write_seqcount_end(&tk_core
.seq
);
965 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
970 * change_clocksource - Swaps clocksources if a new one is available
972 * Accumulates current time interval and initializes new clocksource
974 static int change_clocksource(void *data
)
976 struct timekeeper
*tk
= &tk_core
.timekeeper
;
977 struct clocksource
*new, *old
;
980 new = (struct clocksource
*) data
;
982 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
983 write_seqcount_begin(&tk_core
.seq
);
985 timekeeping_forward_now(tk
);
987 * If the cs is in module, get a module reference. Succeeds
988 * for built-in code (owner == NULL) as well.
990 if (try_module_get(new->owner
)) {
991 if (!new->enable
|| new->enable(new) == 0) {
993 tk_setup_internals(tk
, new);
996 module_put(old
->owner
);
998 module_put(new->owner
);
1001 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
1003 write_seqcount_end(&tk_core
.seq
);
1004 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1010 * timekeeping_notify - Install a new clock source
1011 * @clock: pointer to the clock source
1013 * This function is called from clocksource.c after a new, better clock
1014 * source has been registered. The caller holds the clocksource_mutex.
1016 int timekeeping_notify(struct clocksource
*clock
)
1018 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1020 if (tk
->tkr
.clock
== clock
)
1022 stop_machine(change_clocksource
, clock
, NULL
);
1023 tick_clock_notify();
1024 return tk
->tkr
.clock
== clock
? 0 : -1;
1028 * getrawmonotonic64 - Returns the raw monotonic time in a timespec
1029 * @ts: pointer to the timespec64 to be set
1031 * Returns the raw monotonic time (completely un-modified by ntp)
1033 void getrawmonotonic64(struct timespec64
*ts
)
1035 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1036 struct timespec64 ts64
;
1041 seq
= read_seqcount_begin(&tk_core
.seq
);
1042 nsecs
= timekeeping_get_ns_raw(tk
);
1043 ts64
= tk
->raw_time
;
1045 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1047 timespec64_add_ns(&ts64
, nsecs
);
1050 EXPORT_SYMBOL(getrawmonotonic64
);
1054 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1056 int timekeeping_valid_for_hres(void)
1058 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1063 seq
= read_seqcount_begin(&tk_core
.seq
);
1065 ret
= tk
->tkr
.clock
->flags
& CLOCK_SOURCE_VALID_FOR_HRES
;
1067 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1073 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1075 u64
timekeeping_max_deferment(void)
1077 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1082 seq
= read_seqcount_begin(&tk_core
.seq
);
1084 ret
= tk
->tkr
.clock
->max_idle_ns
;
1086 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1092 * read_persistent_clock - Return time from the persistent clock.
1094 * Weak dummy function for arches that do not yet support it.
1095 * Reads the time from the battery backed persistent clock.
1096 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1098 * XXX - Do be sure to remove it once all arches implement it.
1100 void __weak
read_persistent_clock(struct timespec
*ts
)
1107 * read_boot_clock - Return time of the system start.
1109 * Weak dummy function for arches that do not yet support it.
1110 * Function to read the exact time the system has been started.
1111 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1113 * XXX - Do be sure to remove it once all arches implement it.
1115 void __weak
read_boot_clock(struct timespec
*ts
)
1122 * timekeeping_init - Initializes the clocksource and common timekeeping values
1124 void __init
timekeeping_init(void)
1126 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1127 struct clocksource
*clock
;
1128 unsigned long flags
;
1129 struct timespec64 now
, boot
, tmp
;
1132 read_persistent_clock(&ts
);
1133 now
= timespec_to_timespec64(ts
);
1134 if (!timespec64_valid_strict(&now
)) {
1135 pr_warn("WARNING: Persistent clock returned invalid value!\n"
1136 " Check your CMOS/BIOS settings.\n");
1139 } else if (now
.tv_sec
|| now
.tv_nsec
)
1140 persistent_clock_exist
= true;
1142 read_boot_clock(&ts
);
1143 boot
= timespec_to_timespec64(ts
);
1144 if (!timespec64_valid_strict(&boot
)) {
1145 pr_warn("WARNING: Boot clock returned invalid value!\n"
1146 " Check your CMOS/BIOS settings.\n");
1151 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1152 write_seqcount_begin(&tk_core
.seq
);
1155 clock
= clocksource_default_clock();
1157 clock
->enable(clock
);
1158 tk_setup_internals(tk
, clock
);
1160 tk_set_xtime(tk
, &now
);
1161 tk
->raw_time
.tv_sec
= 0;
1162 tk
->raw_time
.tv_nsec
= 0;
1163 tk
->base_raw
.tv64
= 0;
1164 if (boot
.tv_sec
== 0 && boot
.tv_nsec
== 0)
1165 boot
= tk_xtime(tk
);
1167 set_normalized_timespec64(&tmp
, -boot
.tv_sec
, -boot
.tv_nsec
);
1168 tk_set_wall_to_mono(tk
, tmp
);
1170 timekeeping_update(tk
, TK_MIRROR
);
1172 write_seqcount_end(&tk_core
.seq
);
1173 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1176 /* time in seconds when suspend began */
1177 static struct timespec64 timekeeping_suspend_time
;
1180 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1181 * @delta: pointer to a timespec delta value
1183 * Takes a timespec offset measuring a suspend interval and properly
1184 * adds the sleep offset to the timekeeping variables.
1186 static void __timekeeping_inject_sleeptime(struct timekeeper
*tk
,
1187 struct timespec64
*delta
)
1189 if (!timespec64_valid_strict(delta
)) {
1190 printk_deferred(KERN_WARNING
1191 "__timekeeping_inject_sleeptime: Invalid "
1192 "sleep delta value!\n");
1195 tk_xtime_add(tk
, delta
);
1196 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, *delta
));
1197 tk_update_sleep_time(tk
, timespec64_to_ktime(*delta
));
1198 tk_debug_account_sleep_time(delta
);
1202 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1203 * @delta: pointer to a timespec64 delta value
1205 * This hook is for architectures that cannot support read_persistent_clock
1206 * because their RTC/persistent clock is only accessible when irqs are enabled.
1208 * This function should only be called by rtc_resume(), and allows
1209 * a suspend offset to be injected into the timekeeping values.
1211 void timekeeping_inject_sleeptime64(struct timespec64
*delta
)
1213 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1214 unsigned long flags
;
1217 * Make sure we don't set the clock twice, as timekeeping_resume()
1220 if (has_persistent_clock())
1223 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1224 write_seqcount_begin(&tk_core
.seq
);
1226 timekeeping_forward_now(tk
);
1228 __timekeeping_inject_sleeptime(tk
, delta
);
1230 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
1232 write_seqcount_end(&tk_core
.seq
);
1233 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1235 /* signal hrtimers about time change */
1240 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1242 * This is for the generic clocksource timekeeping.
1243 * xtime/wall_to_monotonic/jiffies/etc are
1244 * still managed by arch specific suspend/resume code.
1246 void timekeeping_resume(void)
1248 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1249 struct clocksource
*clock
= tk
->tkr
.clock
;
1250 unsigned long flags
;
1251 struct timespec64 ts_new
, ts_delta
;
1252 struct timespec tmp
;
1253 cycle_t cycle_now
, cycle_delta
;
1254 bool suspendtime_found
= false;
1256 read_persistent_clock(&tmp
);
1257 ts_new
= timespec_to_timespec64(tmp
);
1259 clockevents_resume();
1260 clocksource_resume();
1262 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1263 write_seqcount_begin(&tk_core
.seq
);
1266 * After system resumes, we need to calculate the suspended time and
1267 * compensate it for the OS time. There are 3 sources that could be
1268 * used: Nonstop clocksource during suspend, persistent clock and rtc
1271 * One specific platform may have 1 or 2 or all of them, and the
1272 * preference will be:
1273 * suspend-nonstop clocksource -> persistent clock -> rtc
1274 * The less preferred source will only be tried if there is no better
1275 * usable source. The rtc part is handled separately in rtc core code.
1277 cycle_now
= tk
->tkr
.read(clock
);
1278 if ((clock
->flags
& CLOCK_SOURCE_SUSPEND_NONSTOP
) &&
1279 cycle_now
> tk
->tkr
.cycle_last
) {
1280 u64 num
, max
= ULLONG_MAX
;
1281 u32 mult
= clock
->mult
;
1282 u32 shift
= clock
->shift
;
1285 cycle_delta
= clocksource_delta(cycle_now
, tk
->tkr
.cycle_last
,
1289 * "cycle_delta * mutl" may cause 64 bits overflow, if the
1290 * suspended time is too long. In that case we need do the
1291 * 64 bits math carefully
1294 if (cycle_delta
> max
) {
1295 num
= div64_u64(cycle_delta
, max
);
1296 nsec
= (((u64
) max
* mult
) >> shift
) * num
;
1297 cycle_delta
-= num
* max
;
1299 nsec
+= ((u64
) cycle_delta
* mult
) >> shift
;
1301 ts_delta
= ns_to_timespec64(nsec
);
1302 suspendtime_found
= true;
1303 } else if (timespec64_compare(&ts_new
, &timekeeping_suspend_time
) > 0) {
1304 ts_delta
= timespec64_sub(ts_new
, timekeeping_suspend_time
);
1305 suspendtime_found
= true;
1308 if (suspendtime_found
)
1309 __timekeeping_inject_sleeptime(tk
, &ts_delta
);
1311 /* Re-base the last cycle value */
1312 tk
->tkr
.cycle_last
= cycle_now
;
1314 timekeeping_suspended
= 0;
1315 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
1316 write_seqcount_end(&tk_core
.seq
);
1317 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1319 touch_softlockup_watchdog();
1321 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME
, NULL
);
1323 /* Resume hrtimers */
1327 int timekeeping_suspend(void)
1329 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1330 unsigned long flags
;
1331 struct timespec64 delta
, delta_delta
;
1332 static struct timespec64 old_delta
;
1333 struct timespec tmp
;
1335 read_persistent_clock(&tmp
);
1336 timekeeping_suspend_time
= timespec_to_timespec64(tmp
);
1339 * On some systems the persistent_clock can not be detected at
1340 * timekeeping_init by its return value, so if we see a valid
1341 * value returned, update the persistent_clock_exists flag.
1343 if (timekeeping_suspend_time
.tv_sec
|| timekeeping_suspend_time
.tv_nsec
)
1344 persistent_clock_exist
= true;
1346 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1347 write_seqcount_begin(&tk_core
.seq
);
1348 timekeeping_forward_now(tk
);
1349 timekeeping_suspended
= 1;
1352 * To avoid drift caused by repeated suspend/resumes,
1353 * which each can add ~1 second drift error,
1354 * try to compensate so the difference in system time
1355 * and persistent_clock time stays close to constant.
1357 delta
= timespec64_sub(tk_xtime(tk
), timekeeping_suspend_time
);
1358 delta_delta
= timespec64_sub(delta
, old_delta
);
1359 if (abs(delta_delta
.tv_sec
) >= 2) {
1361 * if delta_delta is too large, assume time correction
1362 * has occured and set old_delta to the current delta.
1366 /* Otherwise try to adjust old_system to compensate */
1367 timekeeping_suspend_time
=
1368 timespec64_add(timekeeping_suspend_time
, delta_delta
);
1371 timekeeping_update(tk
, TK_MIRROR
);
1372 halt_fast_timekeeper(tk
);
1373 write_seqcount_end(&tk_core
.seq
);
1374 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1376 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND
, NULL
);
1377 clocksource_suspend();
1378 clockevents_suspend();
1383 /* sysfs resume/suspend bits for timekeeping */
1384 static struct syscore_ops timekeeping_syscore_ops
= {
1385 .resume
= timekeeping_resume
,
1386 .suspend
= timekeeping_suspend
,
1389 static int __init
timekeeping_init_ops(void)
1391 register_syscore_ops(&timekeeping_syscore_ops
);
1394 device_initcall(timekeeping_init_ops
);
1397 * Apply a multiplier adjustment to the timekeeper
1399 static __always_inline
void timekeeping_apply_adjustment(struct timekeeper
*tk
,
1404 s64 interval
= tk
->cycle_interval
;
1408 mult_adj
= -mult_adj
;
1409 interval
= -interval
;
1412 mult_adj
<<= adj_scale
;
1413 interval
<<= adj_scale
;
1414 offset
<<= adj_scale
;
1417 * So the following can be confusing.
1419 * To keep things simple, lets assume mult_adj == 1 for now.
1421 * When mult_adj != 1, remember that the interval and offset values
1422 * have been appropriately scaled so the math is the same.
1424 * The basic idea here is that we're increasing the multiplier
1425 * by one, this causes the xtime_interval to be incremented by
1426 * one cycle_interval. This is because:
1427 * xtime_interval = cycle_interval * mult
1428 * So if mult is being incremented by one:
1429 * xtime_interval = cycle_interval * (mult + 1)
1431 * xtime_interval = (cycle_interval * mult) + cycle_interval
1432 * Which can be shortened to:
1433 * xtime_interval += cycle_interval
1435 * So offset stores the non-accumulated cycles. Thus the current
1436 * time (in shifted nanoseconds) is:
1437 * now = (offset * adj) + xtime_nsec
1438 * Now, even though we're adjusting the clock frequency, we have
1439 * to keep time consistent. In other words, we can't jump back
1440 * in time, and we also want to avoid jumping forward in time.
1442 * So given the same offset value, we need the time to be the same
1443 * both before and after the freq adjustment.
1444 * now = (offset * adj_1) + xtime_nsec_1
1445 * now = (offset * adj_2) + xtime_nsec_2
1447 * (offset * adj_1) + xtime_nsec_1 =
1448 * (offset * adj_2) + xtime_nsec_2
1452 * (offset * adj_1) + xtime_nsec_1 =
1453 * (offset * (adj_1+1)) + xtime_nsec_2
1454 * (offset * adj_1) + xtime_nsec_1 =
1455 * (offset * adj_1) + offset + xtime_nsec_2
1456 * Canceling the sides:
1457 * xtime_nsec_1 = offset + xtime_nsec_2
1459 * xtime_nsec_2 = xtime_nsec_1 - offset
1460 * Which simplfies to:
1461 * xtime_nsec -= offset
1463 * XXX - TODO: Doc ntp_error calculation.
1465 if ((mult_adj
> 0) && (tk
->tkr
.mult
+ mult_adj
< mult_adj
)) {
1466 /* NTP adjustment caused clocksource mult overflow */
1471 tk
->tkr
.mult
+= mult_adj
;
1472 tk
->xtime_interval
+= interval
;
1473 tk
->tkr
.xtime_nsec
-= offset
;
1474 tk
->ntp_error
-= (interval
- offset
) << tk
->ntp_error_shift
;
1478 * Calculate the multiplier adjustment needed to match the frequency
1481 static __always_inline
void timekeeping_freqadjust(struct timekeeper
*tk
,
1484 s64 interval
= tk
->cycle_interval
;
1485 s64 xinterval
= tk
->xtime_interval
;
1490 /* Remove any current error adj from freq calculation */
1491 if (tk
->ntp_err_mult
)
1492 xinterval
-= tk
->cycle_interval
;
1494 tk
->ntp_tick
= ntp_tick_length();
1496 /* Calculate current error per tick */
1497 tick_error
= ntp_tick_length() >> tk
->ntp_error_shift
;
1498 tick_error
-= (xinterval
+ tk
->xtime_remainder
);
1500 /* Don't worry about correcting it if its small */
1501 if (likely((tick_error
>= 0) && (tick_error
<= interval
)))
1504 /* preserve the direction of correction */
1505 negative
= (tick_error
< 0);
1507 /* Sort out the magnitude of the correction */
1508 tick_error
= abs(tick_error
);
1509 for (adj
= 0; tick_error
> interval
; adj
++)
1512 /* scale the corrections */
1513 timekeeping_apply_adjustment(tk
, offset
, negative
, adj
);
1517 * Adjust the timekeeper's multiplier to the correct frequency
1518 * and also to reduce the accumulated error value.
1520 static void timekeeping_adjust(struct timekeeper
*tk
, s64 offset
)
1522 /* Correct for the current frequency error */
1523 timekeeping_freqadjust(tk
, offset
);
1525 /* Next make a small adjustment to fix any cumulative error */
1526 if (!tk
->ntp_err_mult
&& (tk
->ntp_error
> 0)) {
1527 tk
->ntp_err_mult
= 1;
1528 timekeeping_apply_adjustment(tk
, offset
, 0, 0);
1529 } else if (tk
->ntp_err_mult
&& (tk
->ntp_error
<= 0)) {
1530 /* Undo any existing error adjustment */
1531 timekeeping_apply_adjustment(tk
, offset
, 1, 0);
1532 tk
->ntp_err_mult
= 0;
1535 if (unlikely(tk
->tkr
.clock
->maxadj
&&
1536 (abs(tk
->tkr
.mult
- tk
->tkr
.clock
->mult
)
1537 > tk
->tkr
.clock
->maxadj
))) {
1538 printk_once(KERN_WARNING
1539 "Adjusting %s more than 11%% (%ld vs %ld)\n",
1540 tk
->tkr
.clock
->name
, (long)tk
->tkr
.mult
,
1541 (long)tk
->tkr
.clock
->mult
+ tk
->tkr
.clock
->maxadj
);
1545 * It may be possible that when we entered this function, xtime_nsec
1546 * was very small. Further, if we're slightly speeding the clocksource
1547 * in the code above, its possible the required corrective factor to
1548 * xtime_nsec could cause it to underflow.
1550 * Now, since we already accumulated the second, cannot simply roll
1551 * the accumulated second back, since the NTP subsystem has been
1552 * notified via second_overflow. So instead we push xtime_nsec forward
1553 * by the amount we underflowed, and add that amount into the error.
1555 * We'll correct this error next time through this function, when
1556 * xtime_nsec is not as small.
1558 if (unlikely((s64
)tk
->tkr
.xtime_nsec
< 0)) {
1559 s64 neg
= -(s64
)tk
->tkr
.xtime_nsec
;
1560 tk
->tkr
.xtime_nsec
= 0;
1561 tk
->ntp_error
+= neg
<< tk
->ntp_error_shift
;
1566 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1568 * Helper function that accumulates a the nsecs greater then a second
1569 * from the xtime_nsec field to the xtime_secs field.
1570 * It also calls into the NTP code to handle leapsecond processing.
1573 static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper
*tk
)
1575 u64 nsecps
= (u64
)NSEC_PER_SEC
<< tk
->tkr
.shift
;
1576 unsigned int clock_set
= 0;
1578 while (tk
->tkr
.xtime_nsec
>= nsecps
) {
1581 tk
->tkr
.xtime_nsec
-= nsecps
;
1584 /* Figure out if its a leap sec and apply if needed */
1585 leap
= second_overflow(tk
->xtime_sec
);
1586 if (unlikely(leap
)) {
1587 struct timespec64 ts
;
1589 tk
->xtime_sec
+= leap
;
1593 tk_set_wall_to_mono(tk
,
1594 timespec64_sub(tk
->wall_to_monotonic
, ts
));
1596 __timekeeping_set_tai_offset(tk
, tk
->tai_offset
- leap
);
1598 clock_set
= TK_CLOCK_WAS_SET
;
1605 * logarithmic_accumulation - shifted accumulation of cycles
1607 * This functions accumulates a shifted interval of cycles into
1608 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1611 * Returns the unconsumed cycles.
1613 static cycle_t
logarithmic_accumulation(struct timekeeper
*tk
, cycle_t offset
,
1615 unsigned int *clock_set
)
1617 cycle_t interval
= tk
->cycle_interval
<< shift
;
1620 /* If the offset is smaller then a shifted interval, do nothing */
1621 if (offset
< interval
)
1624 /* Accumulate one shifted interval */
1626 tk
->tkr
.cycle_last
+= interval
;
1628 tk
->tkr
.xtime_nsec
+= tk
->xtime_interval
<< shift
;
1629 *clock_set
|= accumulate_nsecs_to_secs(tk
);
1631 /* Accumulate raw time */
1632 raw_nsecs
= (u64
)tk
->raw_interval
<< shift
;
1633 raw_nsecs
+= tk
->raw_time
.tv_nsec
;
1634 if (raw_nsecs
>= NSEC_PER_SEC
) {
1635 u64 raw_secs
= raw_nsecs
;
1636 raw_nsecs
= do_div(raw_secs
, NSEC_PER_SEC
);
1637 tk
->raw_time
.tv_sec
+= raw_secs
;
1639 tk
->raw_time
.tv_nsec
= raw_nsecs
;
1641 /* Accumulate error between NTP and clock interval */
1642 tk
->ntp_error
+= tk
->ntp_tick
<< shift
;
1643 tk
->ntp_error
-= (tk
->xtime_interval
+ tk
->xtime_remainder
) <<
1644 (tk
->ntp_error_shift
+ shift
);
1650 * update_wall_time - Uses the current clocksource to increment the wall time
1653 void update_wall_time(void)
1655 struct timekeeper
*real_tk
= &tk_core
.timekeeper
;
1656 struct timekeeper
*tk
= &shadow_timekeeper
;
1658 int shift
= 0, maxshift
;
1659 unsigned int clock_set
= 0;
1660 unsigned long flags
;
1662 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1664 /* Make sure we're fully resumed: */
1665 if (unlikely(timekeeping_suspended
))
1668 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1669 offset
= real_tk
->cycle_interval
;
1671 offset
= clocksource_delta(tk
->tkr
.read(tk
->tkr
.clock
),
1672 tk
->tkr
.cycle_last
, tk
->tkr
.mask
);
1675 /* Check if there's really nothing to do */
1676 if (offset
< real_tk
->cycle_interval
)
1679 /* Do some additional sanity checking */
1680 timekeeping_check_update(real_tk
, offset
);
1683 * With NO_HZ we may have to accumulate many cycle_intervals
1684 * (think "ticks") worth of time at once. To do this efficiently,
1685 * we calculate the largest doubling multiple of cycle_intervals
1686 * that is smaller than the offset. We then accumulate that
1687 * chunk in one go, and then try to consume the next smaller
1690 shift
= ilog2(offset
) - ilog2(tk
->cycle_interval
);
1691 shift
= max(0, shift
);
1692 /* Bound shift to one less than what overflows tick_length */
1693 maxshift
= (64 - (ilog2(ntp_tick_length())+1)) - 1;
1694 shift
= min(shift
, maxshift
);
1695 while (offset
>= tk
->cycle_interval
) {
1696 offset
= logarithmic_accumulation(tk
, offset
, shift
,
1698 if (offset
< tk
->cycle_interval
<<shift
)
1702 /* correct the clock when NTP error is too big */
1703 timekeeping_adjust(tk
, offset
);
1706 * XXX This can be killed once everyone converts
1707 * to the new update_vsyscall.
1709 old_vsyscall_fixup(tk
);
1712 * Finally, make sure that after the rounding
1713 * xtime_nsec isn't larger than NSEC_PER_SEC
1715 clock_set
|= accumulate_nsecs_to_secs(tk
);
1717 write_seqcount_begin(&tk_core
.seq
);
1719 * Update the real timekeeper.
1721 * We could avoid this memcpy by switching pointers, but that
1722 * requires changes to all other timekeeper usage sites as
1723 * well, i.e. move the timekeeper pointer getter into the
1724 * spinlocked/seqcount protected sections. And we trade this
1725 * memcpy under the tk_core.seq against one before we start
1728 memcpy(real_tk
, tk
, sizeof(*tk
));
1729 timekeeping_update(real_tk
, clock_set
);
1730 write_seqcount_end(&tk_core
.seq
);
1732 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1734 /* Have to call _delayed version, since in irq context*/
1735 clock_was_set_delayed();
1739 * getboottime64 - Return the real time of system boot.
1740 * @ts: pointer to the timespec64 to be set
1742 * Returns the wall-time of boot in a timespec64.
1744 * This is based on the wall_to_monotonic offset and the total suspend
1745 * time. Calls to settimeofday will affect the value returned (which
1746 * basically means that however wrong your real time clock is at boot time,
1747 * you get the right time here).
1749 void getboottime64(struct timespec64
*ts
)
1751 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1752 ktime_t t
= ktime_sub(tk
->offs_real
, tk
->offs_boot
);
1754 *ts
= ktime_to_timespec64(t
);
1756 EXPORT_SYMBOL_GPL(getboottime64
);
1758 unsigned long get_seconds(void)
1760 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1762 return tk
->xtime_sec
;
1764 EXPORT_SYMBOL(get_seconds
);
1766 struct timespec
__current_kernel_time(void)
1768 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1770 return timespec64_to_timespec(tk_xtime(tk
));
1773 struct timespec
current_kernel_time(void)
1775 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1776 struct timespec64 now
;
1780 seq
= read_seqcount_begin(&tk_core
.seq
);
1783 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1785 return timespec64_to_timespec(now
);
1787 EXPORT_SYMBOL(current_kernel_time
);
1789 struct timespec64
get_monotonic_coarse64(void)
1791 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1792 struct timespec64 now
, mono
;
1796 seq
= read_seqcount_begin(&tk_core
.seq
);
1799 mono
= tk
->wall_to_monotonic
;
1800 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1802 set_normalized_timespec64(&now
, now
.tv_sec
+ mono
.tv_sec
,
1803 now
.tv_nsec
+ mono
.tv_nsec
);
1809 * Must hold jiffies_lock
1811 void do_timer(unsigned long ticks
)
1813 jiffies_64
+= ticks
;
1814 calc_global_load(ticks
);
1818 * ktime_get_update_offsets_tick - hrtimer helper
1819 * @offs_real: pointer to storage for monotonic -> realtime offset
1820 * @offs_boot: pointer to storage for monotonic -> boottime offset
1821 * @offs_tai: pointer to storage for monotonic -> clock tai offset
1823 * Returns monotonic time at last tick and various offsets
1825 ktime_t
ktime_get_update_offsets_tick(ktime_t
*offs_real
, ktime_t
*offs_boot
,
1828 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1834 seq
= read_seqcount_begin(&tk_core
.seq
);
1836 base
= tk
->tkr
.base_mono
;
1837 nsecs
= tk
->tkr
.xtime_nsec
>> tk
->tkr
.shift
;
1839 *offs_real
= tk
->offs_real
;
1840 *offs_boot
= tk
->offs_boot
;
1841 *offs_tai
= tk
->offs_tai
;
1842 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1844 return ktime_add_ns(base
, nsecs
);
1847 #ifdef CONFIG_HIGH_RES_TIMERS
1849 * ktime_get_update_offsets_now - hrtimer helper
1850 * @offs_real: pointer to storage for monotonic -> realtime offset
1851 * @offs_boot: pointer to storage for monotonic -> boottime offset
1852 * @offs_tai: pointer to storage for monotonic -> clock tai offset
1854 * Returns current monotonic time and updates the offsets
1855 * Called from hrtimer_interrupt() or retrigger_next_event()
1857 ktime_t
ktime_get_update_offsets_now(ktime_t
*offs_real
, ktime_t
*offs_boot
,
1860 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1866 seq
= read_seqcount_begin(&tk_core
.seq
);
1868 base
= tk
->tkr
.base_mono
;
1869 nsecs
= timekeeping_get_ns(&tk
->tkr
);
1871 *offs_real
= tk
->offs_real
;
1872 *offs_boot
= tk
->offs_boot
;
1873 *offs_tai
= tk
->offs_tai
;
1874 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1876 return ktime_add_ns(base
, nsecs
);
1881 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
1883 int do_adjtimex(struct timex
*txc
)
1885 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1886 unsigned long flags
;
1887 struct timespec64 ts
;
1891 /* Validate the data before disabling interrupts */
1892 ret
= ntp_validate_timex(txc
);
1896 if (txc
->modes
& ADJ_SETOFFSET
) {
1897 struct timespec delta
;
1898 delta
.tv_sec
= txc
->time
.tv_sec
;
1899 delta
.tv_nsec
= txc
->time
.tv_usec
;
1900 if (!(txc
->modes
& ADJ_NANO
))
1901 delta
.tv_nsec
*= 1000;
1902 ret
= timekeeping_inject_offset(&delta
);
1907 getnstimeofday64(&ts
);
1909 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1910 write_seqcount_begin(&tk_core
.seq
);
1912 orig_tai
= tai
= tk
->tai_offset
;
1913 ret
= __do_adjtimex(txc
, &ts
, &tai
);
1915 if (tai
!= orig_tai
) {
1916 __timekeeping_set_tai_offset(tk
, tai
);
1917 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
1919 write_seqcount_end(&tk_core
.seq
);
1920 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1922 if (tai
!= orig_tai
)
1925 ntp_notify_cmos_timer();
1930 #ifdef CONFIG_NTP_PPS
1932 * hardpps() - Accessor function to NTP __hardpps function
1934 void hardpps(const struct timespec
*phase_ts
, const struct timespec
*raw_ts
)
1936 unsigned long flags
;
1938 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1939 write_seqcount_begin(&tk_core
.seq
);
1941 __hardpps(phase_ts
, raw_ts
);
1943 write_seqcount_end(&tk_core
.seq
);
1944 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1946 EXPORT_SYMBOL(hardpps
);
1950 * xtime_update() - advances the timekeeping infrastructure
1951 * @ticks: number of ticks, that have elapsed since the last call.
1953 * Must be called with interrupts disabled.
1955 void xtime_update(unsigned long ticks
)
1957 write_seqlock(&jiffies_lock
);
1959 write_sequnlock(&jiffies_lock
);