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
);
152 * Try to catch underflows by checking if we are seeing small
153 * mask-relative negative values.
155 if (unlikely((~delta
& tkr
->mask
) < (tkr
->mask
>> 3)))
158 /* Cap delta value to the max_cycles values to avoid mult overflows */
159 if (unlikely(delta
> tkr
->clock
->max_cycles
))
160 delta
= tkr
->clock
->max_cycles
;
165 static inline void timekeeping_check_update(struct timekeeper
*tk
, cycle_t offset
)
168 static inline cycle_t
timekeeping_get_delta(struct tk_read_base
*tkr
)
170 cycle_t cycle_now
, delta
;
172 /* read clocksource */
173 cycle_now
= tkr
->read(tkr
->clock
);
175 /* calculate the delta since the last update_wall_time */
176 delta
= clocksource_delta(cycle_now
, tkr
->cycle_last
, tkr
->mask
);
183 * tk_setup_internals - Set up internals to use clocksource clock.
185 * @tk: The target timekeeper to setup.
186 * @clock: Pointer to clocksource.
188 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
189 * pair and interval request.
191 * Unless you're the timekeeping code, you should not be using this!
193 static void tk_setup_internals(struct timekeeper
*tk
, struct clocksource
*clock
)
196 u64 tmp
, ntpinterval
;
197 struct clocksource
*old_clock
;
199 old_clock
= tk
->tkr
.clock
;
200 tk
->tkr
.clock
= clock
;
201 tk
->tkr
.read
= clock
->read
;
202 tk
->tkr
.mask
= clock
->mask
;
203 tk
->tkr
.cycle_last
= tk
->tkr
.read(clock
);
205 /* Do the ns -> cycle conversion first, using original mult */
206 tmp
= NTP_INTERVAL_LENGTH
;
207 tmp
<<= clock
->shift
;
209 tmp
+= clock
->mult
/2;
210 do_div(tmp
, clock
->mult
);
214 interval
= (cycle_t
) tmp
;
215 tk
->cycle_interval
= interval
;
217 /* Go back from cycles -> shifted ns */
218 tk
->xtime_interval
= (u64
) interval
* clock
->mult
;
219 tk
->xtime_remainder
= ntpinterval
- tk
->xtime_interval
;
221 ((u64
) interval
* clock
->mult
) >> clock
->shift
;
223 /* if changing clocks, convert xtime_nsec shift units */
225 int shift_change
= clock
->shift
- old_clock
->shift
;
226 if (shift_change
< 0)
227 tk
->tkr
.xtime_nsec
>>= -shift_change
;
229 tk
->tkr
.xtime_nsec
<<= shift_change
;
231 tk
->tkr
.shift
= clock
->shift
;
234 tk
->ntp_error_shift
= NTP_SCALE_SHIFT
- clock
->shift
;
235 tk
->ntp_tick
= ntpinterval
<< tk
->ntp_error_shift
;
238 * The timekeeper keeps its own mult values for the currently
239 * active clocksource. These value will be adjusted via NTP
240 * to counteract clock drifting.
242 tk
->tkr
.mult
= clock
->mult
;
243 tk
->ntp_err_mult
= 0;
246 /* Timekeeper helper functions. */
248 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
249 static u32
default_arch_gettimeoffset(void) { return 0; }
250 u32 (*arch_gettimeoffset
)(void) = default_arch_gettimeoffset
;
252 static inline u32
arch_gettimeoffset(void) { return 0; }
255 static inline s64
timekeeping_get_ns(struct tk_read_base
*tkr
)
260 delta
= timekeeping_get_delta(tkr
);
262 nsec
= delta
* tkr
->mult
+ tkr
->xtime_nsec
;
265 /* If arch requires, add in get_arch_timeoffset() */
266 return nsec
+ arch_gettimeoffset();
269 static inline s64
timekeeping_get_ns_raw(struct timekeeper
*tk
)
271 struct clocksource
*clock
= tk
->tkr
.clock
;
275 delta
= timekeeping_get_delta(&tk
->tkr
);
277 /* convert delta to nanoseconds. */
278 nsec
= clocksource_cyc2ns(delta
, clock
->mult
, clock
->shift
);
280 /* If arch requires, add in get_arch_timeoffset() */
281 return nsec
+ arch_gettimeoffset();
285 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
286 * @tkr: Timekeeping readout base from which we take the update
288 * We want to use this from any context including NMI and tracing /
289 * instrumenting the timekeeping code itself.
291 * So we handle this differently than the other timekeeping accessor
292 * functions which retry when the sequence count has changed. The
295 * smp_wmb(); <- Ensure that the last base[1] update is visible
297 * smp_wmb(); <- Ensure that the seqcount update is visible
298 * update(tkf->base[0], tkr);
299 * smp_wmb(); <- Ensure that the base[0] update is visible
301 * smp_wmb(); <- Ensure that the seqcount update is visible
302 * update(tkf->base[1], tkr);
304 * The reader side does:
310 * now = now(tkf->base[idx]);
312 * } while (seq != tkf->seq)
314 * As long as we update base[0] readers are forced off to
315 * base[1]. Once base[0] is updated readers are redirected to base[0]
316 * and the base[1] update takes place.
318 * So if a NMI hits the update of base[0] then it will use base[1]
319 * which is still consistent. In the worst case this can result is a
320 * slightly wrong timestamp (a few nanoseconds). See
321 * @ktime_get_mono_fast_ns.
323 static void update_fast_timekeeper(struct tk_read_base
*tkr
)
325 struct tk_read_base
*base
= tk_fast_mono
.base
;
327 /* Force readers off to base[1] */
328 raw_write_seqcount_latch(&tk_fast_mono
.seq
);
331 memcpy(base
, tkr
, sizeof(*base
));
333 /* Force readers back to base[0] */
334 raw_write_seqcount_latch(&tk_fast_mono
.seq
);
337 memcpy(base
+ 1, base
, sizeof(*base
));
341 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
343 * This timestamp is not guaranteed to be monotonic across an update.
344 * The timestamp is calculated by:
346 * now = base_mono + clock_delta * slope
348 * So if the update lowers the slope, readers who are forced to the
349 * not yet updated second array are still using the old steeper slope.
358 * |12345678---> reader order
364 * So reader 6 will observe time going backwards versus reader 5.
366 * While other CPUs are likely to be able observe that, the only way
367 * for a CPU local observation is when an NMI hits in the middle of
368 * the update. Timestamps taken from that NMI context might be ahead
369 * of the following timestamps. Callers need to be aware of that and
372 u64 notrace
ktime_get_mono_fast_ns(void)
374 struct tk_read_base
*tkr
;
379 seq
= raw_read_seqcount(&tk_fast_mono
.seq
);
380 tkr
= tk_fast_mono
.base
+ (seq
& 0x01);
381 now
= ktime_to_ns(tkr
->base_mono
) + timekeeping_get_ns(tkr
);
383 } while (read_seqcount_retry(&tk_fast_mono
.seq
, seq
));
386 EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns
);
388 /* Suspend-time cycles value for halted fast timekeeper. */
389 static cycle_t cycles_at_suspend
;
391 static cycle_t
dummy_clock_read(struct clocksource
*cs
)
393 return cycles_at_suspend
;
397 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
398 * @tk: Timekeeper to snapshot.
400 * It generally is unsafe to access the clocksource after timekeeping has been
401 * suspended, so take a snapshot of the readout base of @tk and use it as the
402 * fast timekeeper's readout base while suspended. It will return the same
403 * number of cycles every time until timekeeping is resumed at which time the
404 * proper readout base for the fast timekeeper will be restored automatically.
406 static void halt_fast_timekeeper(struct timekeeper
*tk
)
408 static struct tk_read_base tkr_dummy
;
409 struct tk_read_base
*tkr
= &tk
->tkr
;
411 memcpy(&tkr_dummy
, tkr
, sizeof(tkr_dummy
));
412 cycles_at_suspend
= tkr
->read(tkr
->clock
);
413 tkr_dummy
.read
= dummy_clock_read
;
414 update_fast_timekeeper(&tkr_dummy
);
417 #ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
419 static inline void update_vsyscall(struct timekeeper
*tk
)
421 struct timespec xt
, wm
;
423 xt
= timespec64_to_timespec(tk_xtime(tk
));
424 wm
= timespec64_to_timespec(tk
->wall_to_monotonic
);
425 update_vsyscall_old(&xt
, &wm
, tk
->tkr
.clock
, tk
->tkr
.mult
,
429 static inline void old_vsyscall_fixup(struct timekeeper
*tk
)
434 * Store only full nanoseconds into xtime_nsec after rounding
435 * it up and add the remainder to the error difference.
436 * XXX - This is necessary to avoid small 1ns inconsistnecies caused
437 * by truncating the remainder in vsyscalls. However, it causes
438 * additional work to be done in timekeeping_adjust(). Once
439 * the vsyscall implementations are converted to use xtime_nsec
440 * (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
441 * users are removed, this can be killed.
443 remainder
= tk
->tkr
.xtime_nsec
& ((1ULL << tk
->tkr
.shift
) - 1);
444 tk
->tkr
.xtime_nsec
-= remainder
;
445 tk
->tkr
.xtime_nsec
+= 1ULL << tk
->tkr
.shift
;
446 tk
->ntp_error
+= remainder
<< tk
->ntp_error_shift
;
447 tk
->ntp_error
-= (1ULL << tk
->tkr
.shift
) << tk
->ntp_error_shift
;
450 #define old_vsyscall_fixup(tk)
453 static RAW_NOTIFIER_HEAD(pvclock_gtod_chain
);
455 static void update_pvclock_gtod(struct timekeeper
*tk
, bool was_set
)
457 raw_notifier_call_chain(&pvclock_gtod_chain
, was_set
, tk
);
461 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
463 int pvclock_gtod_register_notifier(struct notifier_block
*nb
)
465 struct timekeeper
*tk
= &tk_core
.timekeeper
;
469 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
470 ret
= raw_notifier_chain_register(&pvclock_gtod_chain
, nb
);
471 update_pvclock_gtod(tk
, true);
472 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
476 EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier
);
479 * pvclock_gtod_unregister_notifier - unregister a pvclock
480 * timedata update listener
482 int pvclock_gtod_unregister_notifier(struct notifier_block
*nb
)
487 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
488 ret
= raw_notifier_chain_unregister(&pvclock_gtod_chain
, nb
);
489 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
493 EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier
);
496 * Update the ktime_t based scalar nsec members of the timekeeper
498 static inline void tk_update_ktime_data(struct timekeeper
*tk
)
504 * The xtime based monotonic readout is:
505 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
506 * The ktime based monotonic readout is:
507 * nsec = base_mono + now();
508 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
510 seconds
= (u64
)(tk
->xtime_sec
+ tk
->wall_to_monotonic
.tv_sec
);
511 nsec
= (u32
) tk
->wall_to_monotonic
.tv_nsec
;
512 tk
->tkr
.base_mono
= ns_to_ktime(seconds
* NSEC_PER_SEC
+ nsec
);
514 /* Update the monotonic raw base */
515 tk
->base_raw
= timespec64_to_ktime(tk
->raw_time
);
518 * The sum of the nanoseconds portions of xtime and
519 * wall_to_monotonic can be greater/equal one second. Take
520 * this into account before updating tk->ktime_sec.
522 nsec
+= (u32
)(tk
->tkr
.xtime_nsec
>> tk
->tkr
.shift
);
523 if (nsec
>= NSEC_PER_SEC
)
525 tk
->ktime_sec
= seconds
;
528 /* must hold timekeeper_lock */
529 static void timekeeping_update(struct timekeeper
*tk
, unsigned int action
)
531 if (action
& TK_CLEAR_NTP
) {
536 tk_update_ktime_data(tk
);
539 update_pvclock_gtod(tk
, action
& TK_CLOCK_WAS_SET
);
541 if (action
& TK_MIRROR
)
542 memcpy(&shadow_timekeeper
, &tk_core
.timekeeper
,
543 sizeof(tk_core
.timekeeper
));
545 update_fast_timekeeper(&tk
->tkr
);
549 * timekeeping_forward_now - update clock to the current time
551 * Forward the current clock to update its state since the last call to
552 * update_wall_time(). This is useful before significant clock changes,
553 * as it avoids having to deal with this time offset explicitly.
555 static void timekeeping_forward_now(struct timekeeper
*tk
)
557 struct clocksource
*clock
= tk
->tkr
.clock
;
558 cycle_t cycle_now
, delta
;
561 cycle_now
= tk
->tkr
.read(clock
);
562 delta
= clocksource_delta(cycle_now
, tk
->tkr
.cycle_last
, tk
->tkr
.mask
);
563 tk
->tkr
.cycle_last
= cycle_now
;
565 tk
->tkr
.xtime_nsec
+= delta
* tk
->tkr
.mult
;
567 /* If arch requires, add in get_arch_timeoffset() */
568 tk
->tkr
.xtime_nsec
+= (u64
)arch_gettimeoffset() << tk
->tkr
.shift
;
570 tk_normalize_xtime(tk
);
572 nsec
= clocksource_cyc2ns(delta
, clock
->mult
, clock
->shift
);
573 timespec64_add_ns(&tk
->raw_time
, nsec
);
577 * __getnstimeofday64 - Returns the time of day in a timespec64.
578 * @ts: pointer to the timespec to be set
580 * Updates the time of day in the timespec.
581 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
583 int __getnstimeofday64(struct timespec64
*ts
)
585 struct timekeeper
*tk
= &tk_core
.timekeeper
;
590 seq
= read_seqcount_begin(&tk_core
.seq
);
592 ts
->tv_sec
= tk
->xtime_sec
;
593 nsecs
= timekeeping_get_ns(&tk
->tkr
);
595 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
598 timespec64_add_ns(ts
, nsecs
);
601 * Do not bail out early, in case there were callers still using
602 * the value, even in the face of the WARN_ON.
604 if (unlikely(timekeeping_suspended
))
608 EXPORT_SYMBOL(__getnstimeofday64
);
611 * getnstimeofday64 - Returns the time of day in a timespec64.
612 * @ts: pointer to the timespec64 to be set
614 * Returns the time of day in a timespec64 (WARN if suspended).
616 void getnstimeofday64(struct timespec64
*ts
)
618 WARN_ON(__getnstimeofday64(ts
));
620 EXPORT_SYMBOL(getnstimeofday64
);
622 ktime_t
ktime_get(void)
624 struct timekeeper
*tk
= &tk_core
.timekeeper
;
629 WARN_ON(timekeeping_suspended
);
632 seq
= read_seqcount_begin(&tk_core
.seq
);
633 base
= tk
->tkr
.base_mono
;
634 nsecs
= timekeeping_get_ns(&tk
->tkr
);
636 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
638 return ktime_add_ns(base
, nsecs
);
640 EXPORT_SYMBOL_GPL(ktime_get
);
642 static ktime_t
*offsets
[TK_OFFS_MAX
] = {
643 [TK_OFFS_REAL
] = &tk_core
.timekeeper
.offs_real
,
644 [TK_OFFS_BOOT
] = &tk_core
.timekeeper
.offs_boot
,
645 [TK_OFFS_TAI
] = &tk_core
.timekeeper
.offs_tai
,
648 ktime_t
ktime_get_with_offset(enum tk_offsets offs
)
650 struct timekeeper
*tk
= &tk_core
.timekeeper
;
652 ktime_t base
, *offset
= offsets
[offs
];
655 WARN_ON(timekeeping_suspended
);
658 seq
= read_seqcount_begin(&tk_core
.seq
);
659 base
= ktime_add(tk
->tkr
.base_mono
, *offset
);
660 nsecs
= timekeeping_get_ns(&tk
->tkr
);
662 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
664 return ktime_add_ns(base
, nsecs
);
667 EXPORT_SYMBOL_GPL(ktime_get_with_offset
);
670 * ktime_mono_to_any() - convert mononotic time to any other time
671 * @tmono: time to convert.
672 * @offs: which offset to use
674 ktime_t
ktime_mono_to_any(ktime_t tmono
, enum tk_offsets offs
)
676 ktime_t
*offset
= offsets
[offs
];
681 seq
= read_seqcount_begin(&tk_core
.seq
);
682 tconv
= ktime_add(tmono
, *offset
);
683 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
687 EXPORT_SYMBOL_GPL(ktime_mono_to_any
);
690 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
692 ktime_t
ktime_get_raw(void)
694 struct timekeeper
*tk
= &tk_core
.timekeeper
;
700 seq
= read_seqcount_begin(&tk_core
.seq
);
702 nsecs
= timekeeping_get_ns_raw(tk
);
704 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
706 return ktime_add_ns(base
, nsecs
);
708 EXPORT_SYMBOL_GPL(ktime_get_raw
);
711 * ktime_get_ts64 - get the monotonic clock in timespec64 format
712 * @ts: pointer to timespec variable
714 * The function calculates the monotonic clock from the realtime
715 * clock and the wall_to_monotonic offset and stores the result
716 * in normalized timespec64 format in the variable pointed to by @ts.
718 void ktime_get_ts64(struct timespec64
*ts
)
720 struct timekeeper
*tk
= &tk_core
.timekeeper
;
721 struct timespec64 tomono
;
725 WARN_ON(timekeeping_suspended
);
728 seq
= read_seqcount_begin(&tk_core
.seq
);
729 ts
->tv_sec
= tk
->xtime_sec
;
730 nsec
= timekeeping_get_ns(&tk
->tkr
);
731 tomono
= tk
->wall_to_monotonic
;
733 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
735 ts
->tv_sec
+= tomono
.tv_sec
;
737 timespec64_add_ns(ts
, nsec
+ tomono
.tv_nsec
);
739 EXPORT_SYMBOL_GPL(ktime_get_ts64
);
742 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
744 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
745 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
746 * works on both 32 and 64 bit systems. On 32 bit systems the readout
747 * covers ~136 years of uptime which should be enough to prevent
748 * premature wrap arounds.
750 time64_t
ktime_get_seconds(void)
752 struct timekeeper
*tk
= &tk_core
.timekeeper
;
754 WARN_ON(timekeeping_suspended
);
755 return tk
->ktime_sec
;
757 EXPORT_SYMBOL_GPL(ktime_get_seconds
);
760 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
762 * Returns the wall clock seconds since 1970. This replaces the
763 * get_seconds() interface which is not y2038 safe on 32bit systems.
765 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
766 * 32bit systems the access must be protected with the sequence
767 * counter to provide "atomic" access to the 64bit tk->xtime_sec
770 time64_t
ktime_get_real_seconds(void)
772 struct timekeeper
*tk
= &tk_core
.timekeeper
;
776 if (IS_ENABLED(CONFIG_64BIT
))
777 return tk
->xtime_sec
;
780 seq
= read_seqcount_begin(&tk_core
.seq
);
781 seconds
= tk
->xtime_sec
;
783 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
787 EXPORT_SYMBOL_GPL(ktime_get_real_seconds
);
789 #ifdef CONFIG_NTP_PPS
792 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
793 * @ts_raw: pointer to the timespec to be set to raw monotonic time
794 * @ts_real: pointer to the timespec to be set to the time of day
796 * This function reads both the time of day and raw monotonic time at the
797 * same time atomically and stores the resulting timestamps in timespec
800 void getnstime_raw_and_real(struct timespec
*ts_raw
, struct timespec
*ts_real
)
802 struct timekeeper
*tk
= &tk_core
.timekeeper
;
804 s64 nsecs_raw
, nsecs_real
;
806 WARN_ON_ONCE(timekeeping_suspended
);
809 seq
= read_seqcount_begin(&tk_core
.seq
);
811 *ts_raw
= timespec64_to_timespec(tk
->raw_time
);
812 ts_real
->tv_sec
= tk
->xtime_sec
;
813 ts_real
->tv_nsec
= 0;
815 nsecs_raw
= timekeeping_get_ns_raw(tk
);
816 nsecs_real
= timekeeping_get_ns(&tk
->tkr
);
818 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
820 timespec_add_ns(ts_raw
, nsecs_raw
);
821 timespec_add_ns(ts_real
, nsecs_real
);
823 EXPORT_SYMBOL(getnstime_raw_and_real
);
825 #endif /* CONFIG_NTP_PPS */
828 * do_gettimeofday - Returns the time of day in a timeval
829 * @tv: pointer to the timeval to be set
831 * NOTE: Users should be converted to using getnstimeofday()
833 void do_gettimeofday(struct timeval
*tv
)
835 struct timespec64 now
;
837 getnstimeofday64(&now
);
838 tv
->tv_sec
= now
.tv_sec
;
839 tv
->tv_usec
= now
.tv_nsec
/1000;
841 EXPORT_SYMBOL(do_gettimeofday
);
844 * do_settimeofday64 - Sets the time of day.
845 * @ts: pointer to the timespec64 variable containing the new time
847 * Sets the time of day to the new time and update NTP and notify hrtimers
849 int do_settimeofday64(const struct timespec64
*ts
)
851 struct timekeeper
*tk
= &tk_core
.timekeeper
;
852 struct timespec64 ts_delta
, xt
;
855 if (!timespec64_valid_strict(ts
))
858 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
859 write_seqcount_begin(&tk_core
.seq
);
861 timekeeping_forward_now(tk
);
864 ts_delta
.tv_sec
= ts
->tv_sec
- xt
.tv_sec
;
865 ts_delta
.tv_nsec
= ts
->tv_nsec
- xt
.tv_nsec
;
867 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, ts_delta
));
869 tk_set_xtime(tk
, ts
);
871 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
873 write_seqcount_end(&tk_core
.seq
);
874 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
876 /* signal hrtimers about time change */
881 EXPORT_SYMBOL(do_settimeofday64
);
884 * timekeeping_inject_offset - Adds or subtracts from the current time.
885 * @tv: pointer to the timespec variable containing the offset
887 * Adds or subtracts an offset value from the current time.
889 int timekeeping_inject_offset(struct timespec
*ts
)
891 struct timekeeper
*tk
= &tk_core
.timekeeper
;
893 struct timespec64 ts64
, tmp
;
896 if ((unsigned long)ts
->tv_nsec
>= NSEC_PER_SEC
)
899 ts64
= timespec_to_timespec64(*ts
);
901 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
902 write_seqcount_begin(&tk_core
.seq
);
904 timekeeping_forward_now(tk
);
906 /* Make sure the proposed value is valid */
907 tmp
= timespec64_add(tk_xtime(tk
), ts64
);
908 if (!timespec64_valid_strict(&tmp
)) {
913 tk_xtime_add(tk
, &ts64
);
914 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, ts64
));
916 error
: /* even if we error out, we forwarded the time, so call update */
917 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
919 write_seqcount_end(&tk_core
.seq
);
920 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
922 /* signal hrtimers about time change */
927 EXPORT_SYMBOL(timekeeping_inject_offset
);
931 * timekeeping_get_tai_offset - Returns current TAI offset from UTC
934 s32
timekeeping_get_tai_offset(void)
936 struct timekeeper
*tk
= &tk_core
.timekeeper
;
941 seq
= read_seqcount_begin(&tk_core
.seq
);
942 ret
= tk
->tai_offset
;
943 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
949 * __timekeeping_set_tai_offset - Lock free worker function
952 static void __timekeeping_set_tai_offset(struct timekeeper
*tk
, s32 tai_offset
)
954 tk
->tai_offset
= tai_offset
;
955 tk
->offs_tai
= ktime_add(tk
->offs_real
, ktime_set(tai_offset
, 0));
959 * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
962 void timekeeping_set_tai_offset(s32 tai_offset
)
964 struct timekeeper
*tk
= &tk_core
.timekeeper
;
967 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
968 write_seqcount_begin(&tk_core
.seq
);
969 __timekeeping_set_tai_offset(tk
, tai_offset
);
970 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
971 write_seqcount_end(&tk_core
.seq
);
972 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
977 * change_clocksource - Swaps clocksources if a new one is available
979 * Accumulates current time interval and initializes new clocksource
981 static int change_clocksource(void *data
)
983 struct timekeeper
*tk
= &tk_core
.timekeeper
;
984 struct clocksource
*new, *old
;
987 new = (struct clocksource
*) data
;
989 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
990 write_seqcount_begin(&tk_core
.seq
);
992 timekeeping_forward_now(tk
);
994 * If the cs is in module, get a module reference. Succeeds
995 * for built-in code (owner == NULL) as well.
997 if (try_module_get(new->owner
)) {
998 if (!new->enable
|| new->enable(new) == 0) {
1000 tk_setup_internals(tk
, new);
1003 module_put(old
->owner
);
1005 module_put(new->owner
);
1008 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
1010 write_seqcount_end(&tk_core
.seq
);
1011 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1017 * timekeeping_notify - Install a new clock source
1018 * @clock: pointer to the clock source
1020 * This function is called from clocksource.c after a new, better clock
1021 * source has been registered. The caller holds the clocksource_mutex.
1023 int timekeeping_notify(struct clocksource
*clock
)
1025 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1027 if (tk
->tkr
.clock
== clock
)
1029 stop_machine(change_clocksource
, clock
, NULL
);
1030 tick_clock_notify();
1031 return tk
->tkr
.clock
== clock
? 0 : -1;
1035 * getrawmonotonic64 - Returns the raw monotonic time in a timespec
1036 * @ts: pointer to the timespec64 to be set
1038 * Returns the raw monotonic time (completely un-modified by ntp)
1040 void getrawmonotonic64(struct timespec64
*ts
)
1042 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1043 struct timespec64 ts64
;
1048 seq
= read_seqcount_begin(&tk_core
.seq
);
1049 nsecs
= timekeeping_get_ns_raw(tk
);
1050 ts64
= tk
->raw_time
;
1052 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1054 timespec64_add_ns(&ts64
, nsecs
);
1057 EXPORT_SYMBOL(getrawmonotonic64
);
1061 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1063 int timekeeping_valid_for_hres(void)
1065 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1070 seq
= read_seqcount_begin(&tk_core
.seq
);
1072 ret
= tk
->tkr
.clock
->flags
& CLOCK_SOURCE_VALID_FOR_HRES
;
1074 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1080 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1082 u64
timekeeping_max_deferment(void)
1084 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1089 seq
= read_seqcount_begin(&tk_core
.seq
);
1091 ret
= tk
->tkr
.clock
->max_idle_ns
;
1093 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1099 * read_persistent_clock - Return time from the persistent clock.
1101 * Weak dummy function for arches that do not yet support it.
1102 * Reads the time from the battery backed persistent clock.
1103 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1105 * XXX - Do be sure to remove it once all arches implement it.
1107 void __weak
read_persistent_clock(struct timespec
*ts
)
1114 * read_boot_clock - Return time of the system start.
1116 * Weak dummy function for arches that do not yet support it.
1117 * Function to read the exact time the system has been started.
1118 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1120 * XXX - Do be sure to remove it once all arches implement it.
1122 void __weak
read_boot_clock(struct timespec
*ts
)
1129 * timekeeping_init - Initializes the clocksource and common timekeeping values
1131 void __init
timekeeping_init(void)
1133 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1134 struct clocksource
*clock
;
1135 unsigned long flags
;
1136 struct timespec64 now
, boot
, tmp
;
1139 read_persistent_clock(&ts
);
1140 now
= timespec_to_timespec64(ts
);
1141 if (!timespec64_valid_strict(&now
)) {
1142 pr_warn("WARNING: Persistent clock returned invalid value!\n"
1143 " Check your CMOS/BIOS settings.\n");
1146 } else if (now
.tv_sec
|| now
.tv_nsec
)
1147 persistent_clock_exist
= true;
1149 read_boot_clock(&ts
);
1150 boot
= timespec_to_timespec64(ts
);
1151 if (!timespec64_valid_strict(&boot
)) {
1152 pr_warn("WARNING: Boot clock returned invalid value!\n"
1153 " Check your CMOS/BIOS settings.\n");
1158 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1159 write_seqcount_begin(&tk_core
.seq
);
1162 clock
= clocksource_default_clock();
1164 clock
->enable(clock
);
1165 tk_setup_internals(tk
, clock
);
1167 tk_set_xtime(tk
, &now
);
1168 tk
->raw_time
.tv_sec
= 0;
1169 tk
->raw_time
.tv_nsec
= 0;
1170 tk
->base_raw
.tv64
= 0;
1171 if (boot
.tv_sec
== 0 && boot
.tv_nsec
== 0)
1172 boot
= tk_xtime(tk
);
1174 set_normalized_timespec64(&tmp
, -boot
.tv_sec
, -boot
.tv_nsec
);
1175 tk_set_wall_to_mono(tk
, tmp
);
1177 timekeeping_update(tk
, TK_MIRROR
);
1179 write_seqcount_end(&tk_core
.seq
);
1180 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1183 /* time in seconds when suspend began */
1184 static struct timespec64 timekeeping_suspend_time
;
1187 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1188 * @delta: pointer to a timespec delta value
1190 * Takes a timespec offset measuring a suspend interval and properly
1191 * adds the sleep offset to the timekeeping variables.
1193 static void __timekeeping_inject_sleeptime(struct timekeeper
*tk
,
1194 struct timespec64
*delta
)
1196 if (!timespec64_valid_strict(delta
)) {
1197 printk_deferred(KERN_WARNING
1198 "__timekeeping_inject_sleeptime: Invalid "
1199 "sleep delta value!\n");
1202 tk_xtime_add(tk
, delta
);
1203 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, *delta
));
1204 tk_update_sleep_time(tk
, timespec64_to_ktime(*delta
));
1205 tk_debug_account_sleep_time(delta
);
1209 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1210 * @delta: pointer to a timespec64 delta value
1212 * This hook is for architectures that cannot support read_persistent_clock
1213 * because their RTC/persistent clock is only accessible when irqs are enabled.
1215 * This function should only be called by rtc_resume(), and allows
1216 * a suspend offset to be injected into the timekeeping values.
1218 void timekeeping_inject_sleeptime64(struct timespec64
*delta
)
1220 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1221 unsigned long flags
;
1224 * Make sure we don't set the clock twice, as timekeeping_resume()
1227 if (has_persistent_clock())
1230 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1231 write_seqcount_begin(&tk_core
.seq
);
1233 timekeeping_forward_now(tk
);
1235 __timekeeping_inject_sleeptime(tk
, delta
);
1237 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
1239 write_seqcount_end(&tk_core
.seq
);
1240 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1242 /* signal hrtimers about time change */
1247 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1249 * This is for the generic clocksource timekeeping.
1250 * xtime/wall_to_monotonic/jiffies/etc are
1251 * still managed by arch specific suspend/resume code.
1253 void timekeeping_resume(void)
1255 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1256 struct clocksource
*clock
= tk
->tkr
.clock
;
1257 unsigned long flags
;
1258 struct timespec64 ts_new
, ts_delta
;
1259 struct timespec tmp
;
1260 cycle_t cycle_now
, cycle_delta
;
1261 bool suspendtime_found
= false;
1263 read_persistent_clock(&tmp
);
1264 ts_new
= timespec_to_timespec64(tmp
);
1266 clockevents_resume();
1267 clocksource_resume();
1269 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1270 write_seqcount_begin(&tk_core
.seq
);
1273 * After system resumes, we need to calculate the suspended time and
1274 * compensate it for the OS time. There are 3 sources that could be
1275 * used: Nonstop clocksource during suspend, persistent clock and rtc
1278 * One specific platform may have 1 or 2 or all of them, and the
1279 * preference will be:
1280 * suspend-nonstop clocksource -> persistent clock -> rtc
1281 * The less preferred source will only be tried if there is no better
1282 * usable source. The rtc part is handled separately in rtc core code.
1284 cycle_now
= tk
->tkr
.read(clock
);
1285 if ((clock
->flags
& CLOCK_SOURCE_SUSPEND_NONSTOP
) &&
1286 cycle_now
> tk
->tkr
.cycle_last
) {
1287 u64 num
, max
= ULLONG_MAX
;
1288 u32 mult
= clock
->mult
;
1289 u32 shift
= clock
->shift
;
1292 cycle_delta
= clocksource_delta(cycle_now
, tk
->tkr
.cycle_last
,
1296 * "cycle_delta * mutl" may cause 64 bits overflow, if the
1297 * suspended time is too long. In that case we need do the
1298 * 64 bits math carefully
1301 if (cycle_delta
> max
) {
1302 num
= div64_u64(cycle_delta
, max
);
1303 nsec
= (((u64
) max
* mult
) >> shift
) * num
;
1304 cycle_delta
-= num
* max
;
1306 nsec
+= ((u64
) cycle_delta
* mult
) >> shift
;
1308 ts_delta
= ns_to_timespec64(nsec
);
1309 suspendtime_found
= true;
1310 } else if (timespec64_compare(&ts_new
, &timekeeping_suspend_time
) > 0) {
1311 ts_delta
= timespec64_sub(ts_new
, timekeeping_suspend_time
);
1312 suspendtime_found
= true;
1315 if (suspendtime_found
)
1316 __timekeeping_inject_sleeptime(tk
, &ts_delta
);
1318 /* Re-base the last cycle value */
1319 tk
->tkr
.cycle_last
= cycle_now
;
1321 timekeeping_suspended
= 0;
1322 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
1323 write_seqcount_end(&tk_core
.seq
);
1324 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1326 touch_softlockup_watchdog();
1328 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME
, NULL
);
1330 /* Resume hrtimers */
1334 int timekeeping_suspend(void)
1336 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1337 unsigned long flags
;
1338 struct timespec64 delta
, delta_delta
;
1339 static struct timespec64 old_delta
;
1340 struct timespec tmp
;
1342 read_persistent_clock(&tmp
);
1343 timekeeping_suspend_time
= timespec_to_timespec64(tmp
);
1346 * On some systems the persistent_clock can not be detected at
1347 * timekeeping_init by its return value, so if we see a valid
1348 * value returned, update the persistent_clock_exists flag.
1350 if (timekeeping_suspend_time
.tv_sec
|| timekeeping_suspend_time
.tv_nsec
)
1351 persistent_clock_exist
= true;
1353 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1354 write_seqcount_begin(&tk_core
.seq
);
1355 timekeeping_forward_now(tk
);
1356 timekeeping_suspended
= 1;
1359 * To avoid drift caused by repeated suspend/resumes,
1360 * which each can add ~1 second drift error,
1361 * try to compensate so the difference in system time
1362 * and persistent_clock time stays close to constant.
1364 delta
= timespec64_sub(tk_xtime(tk
), timekeeping_suspend_time
);
1365 delta_delta
= timespec64_sub(delta
, old_delta
);
1366 if (abs(delta_delta
.tv_sec
) >= 2) {
1368 * if delta_delta is too large, assume time correction
1369 * has occured and set old_delta to the current delta.
1373 /* Otherwise try to adjust old_system to compensate */
1374 timekeeping_suspend_time
=
1375 timespec64_add(timekeeping_suspend_time
, delta_delta
);
1378 timekeeping_update(tk
, TK_MIRROR
);
1379 halt_fast_timekeeper(tk
);
1380 write_seqcount_end(&tk_core
.seq
);
1381 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1383 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND
, NULL
);
1384 clocksource_suspend();
1385 clockevents_suspend();
1390 /* sysfs resume/suspend bits for timekeeping */
1391 static struct syscore_ops timekeeping_syscore_ops
= {
1392 .resume
= timekeeping_resume
,
1393 .suspend
= timekeeping_suspend
,
1396 static int __init
timekeeping_init_ops(void)
1398 register_syscore_ops(&timekeeping_syscore_ops
);
1401 device_initcall(timekeeping_init_ops
);
1404 * Apply a multiplier adjustment to the timekeeper
1406 static __always_inline
void timekeeping_apply_adjustment(struct timekeeper
*tk
,
1411 s64 interval
= tk
->cycle_interval
;
1415 mult_adj
= -mult_adj
;
1416 interval
= -interval
;
1419 mult_adj
<<= adj_scale
;
1420 interval
<<= adj_scale
;
1421 offset
<<= adj_scale
;
1424 * So the following can be confusing.
1426 * To keep things simple, lets assume mult_adj == 1 for now.
1428 * When mult_adj != 1, remember that the interval and offset values
1429 * have been appropriately scaled so the math is the same.
1431 * The basic idea here is that we're increasing the multiplier
1432 * by one, this causes the xtime_interval to be incremented by
1433 * one cycle_interval. This is because:
1434 * xtime_interval = cycle_interval * mult
1435 * So if mult is being incremented by one:
1436 * xtime_interval = cycle_interval * (mult + 1)
1438 * xtime_interval = (cycle_interval * mult) + cycle_interval
1439 * Which can be shortened to:
1440 * xtime_interval += cycle_interval
1442 * So offset stores the non-accumulated cycles. Thus the current
1443 * time (in shifted nanoseconds) is:
1444 * now = (offset * adj) + xtime_nsec
1445 * Now, even though we're adjusting the clock frequency, we have
1446 * to keep time consistent. In other words, we can't jump back
1447 * in time, and we also want to avoid jumping forward in time.
1449 * So given the same offset value, we need the time to be the same
1450 * both before and after the freq adjustment.
1451 * now = (offset * adj_1) + xtime_nsec_1
1452 * now = (offset * adj_2) + xtime_nsec_2
1454 * (offset * adj_1) + xtime_nsec_1 =
1455 * (offset * adj_2) + xtime_nsec_2
1459 * (offset * adj_1) + xtime_nsec_1 =
1460 * (offset * (adj_1+1)) + xtime_nsec_2
1461 * (offset * adj_1) + xtime_nsec_1 =
1462 * (offset * adj_1) + offset + xtime_nsec_2
1463 * Canceling the sides:
1464 * xtime_nsec_1 = offset + xtime_nsec_2
1466 * xtime_nsec_2 = xtime_nsec_1 - offset
1467 * Which simplfies to:
1468 * xtime_nsec -= offset
1470 * XXX - TODO: Doc ntp_error calculation.
1472 if ((mult_adj
> 0) && (tk
->tkr
.mult
+ mult_adj
< mult_adj
)) {
1473 /* NTP adjustment caused clocksource mult overflow */
1478 tk
->tkr
.mult
+= mult_adj
;
1479 tk
->xtime_interval
+= interval
;
1480 tk
->tkr
.xtime_nsec
-= offset
;
1481 tk
->ntp_error
-= (interval
- offset
) << tk
->ntp_error_shift
;
1485 * Calculate the multiplier adjustment needed to match the frequency
1488 static __always_inline
void timekeeping_freqadjust(struct timekeeper
*tk
,
1491 s64 interval
= tk
->cycle_interval
;
1492 s64 xinterval
= tk
->xtime_interval
;
1497 /* Remove any current error adj from freq calculation */
1498 if (tk
->ntp_err_mult
)
1499 xinterval
-= tk
->cycle_interval
;
1501 tk
->ntp_tick
= ntp_tick_length();
1503 /* Calculate current error per tick */
1504 tick_error
= ntp_tick_length() >> tk
->ntp_error_shift
;
1505 tick_error
-= (xinterval
+ tk
->xtime_remainder
);
1507 /* Don't worry about correcting it if its small */
1508 if (likely((tick_error
>= 0) && (tick_error
<= interval
)))
1511 /* preserve the direction of correction */
1512 negative
= (tick_error
< 0);
1514 /* Sort out the magnitude of the correction */
1515 tick_error
= abs(tick_error
);
1516 for (adj
= 0; tick_error
> interval
; adj
++)
1519 /* scale the corrections */
1520 timekeeping_apply_adjustment(tk
, offset
, negative
, adj
);
1524 * Adjust the timekeeper's multiplier to the correct frequency
1525 * and also to reduce the accumulated error value.
1527 static void timekeeping_adjust(struct timekeeper
*tk
, s64 offset
)
1529 /* Correct for the current frequency error */
1530 timekeeping_freqadjust(tk
, offset
);
1532 /* Next make a small adjustment to fix any cumulative error */
1533 if (!tk
->ntp_err_mult
&& (tk
->ntp_error
> 0)) {
1534 tk
->ntp_err_mult
= 1;
1535 timekeeping_apply_adjustment(tk
, offset
, 0, 0);
1536 } else if (tk
->ntp_err_mult
&& (tk
->ntp_error
<= 0)) {
1537 /* Undo any existing error adjustment */
1538 timekeeping_apply_adjustment(tk
, offset
, 1, 0);
1539 tk
->ntp_err_mult
= 0;
1542 if (unlikely(tk
->tkr
.clock
->maxadj
&&
1543 (abs(tk
->tkr
.mult
- tk
->tkr
.clock
->mult
)
1544 > tk
->tkr
.clock
->maxadj
))) {
1545 printk_once(KERN_WARNING
1546 "Adjusting %s more than 11%% (%ld vs %ld)\n",
1547 tk
->tkr
.clock
->name
, (long)tk
->tkr
.mult
,
1548 (long)tk
->tkr
.clock
->mult
+ tk
->tkr
.clock
->maxadj
);
1552 * It may be possible that when we entered this function, xtime_nsec
1553 * was very small. Further, if we're slightly speeding the clocksource
1554 * in the code above, its possible the required corrective factor to
1555 * xtime_nsec could cause it to underflow.
1557 * Now, since we already accumulated the second, cannot simply roll
1558 * the accumulated second back, since the NTP subsystem has been
1559 * notified via second_overflow. So instead we push xtime_nsec forward
1560 * by the amount we underflowed, and add that amount into the error.
1562 * We'll correct this error next time through this function, when
1563 * xtime_nsec is not as small.
1565 if (unlikely((s64
)tk
->tkr
.xtime_nsec
< 0)) {
1566 s64 neg
= -(s64
)tk
->tkr
.xtime_nsec
;
1567 tk
->tkr
.xtime_nsec
= 0;
1568 tk
->ntp_error
+= neg
<< tk
->ntp_error_shift
;
1573 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1575 * Helper function that accumulates a the nsecs greater then a second
1576 * from the xtime_nsec field to the xtime_secs field.
1577 * It also calls into the NTP code to handle leapsecond processing.
1580 static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper
*tk
)
1582 u64 nsecps
= (u64
)NSEC_PER_SEC
<< tk
->tkr
.shift
;
1583 unsigned int clock_set
= 0;
1585 while (tk
->tkr
.xtime_nsec
>= nsecps
) {
1588 tk
->tkr
.xtime_nsec
-= nsecps
;
1591 /* Figure out if its a leap sec and apply if needed */
1592 leap
= second_overflow(tk
->xtime_sec
);
1593 if (unlikely(leap
)) {
1594 struct timespec64 ts
;
1596 tk
->xtime_sec
+= leap
;
1600 tk_set_wall_to_mono(tk
,
1601 timespec64_sub(tk
->wall_to_monotonic
, ts
));
1603 __timekeeping_set_tai_offset(tk
, tk
->tai_offset
- leap
);
1605 clock_set
= TK_CLOCK_WAS_SET
;
1612 * logarithmic_accumulation - shifted accumulation of cycles
1614 * This functions accumulates a shifted interval of cycles into
1615 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1618 * Returns the unconsumed cycles.
1620 static cycle_t
logarithmic_accumulation(struct timekeeper
*tk
, cycle_t offset
,
1622 unsigned int *clock_set
)
1624 cycle_t interval
= tk
->cycle_interval
<< shift
;
1627 /* If the offset is smaller then a shifted interval, do nothing */
1628 if (offset
< interval
)
1631 /* Accumulate one shifted interval */
1633 tk
->tkr
.cycle_last
+= interval
;
1635 tk
->tkr
.xtime_nsec
+= tk
->xtime_interval
<< shift
;
1636 *clock_set
|= accumulate_nsecs_to_secs(tk
);
1638 /* Accumulate raw time */
1639 raw_nsecs
= (u64
)tk
->raw_interval
<< shift
;
1640 raw_nsecs
+= tk
->raw_time
.tv_nsec
;
1641 if (raw_nsecs
>= NSEC_PER_SEC
) {
1642 u64 raw_secs
= raw_nsecs
;
1643 raw_nsecs
= do_div(raw_secs
, NSEC_PER_SEC
);
1644 tk
->raw_time
.tv_sec
+= raw_secs
;
1646 tk
->raw_time
.tv_nsec
= raw_nsecs
;
1648 /* Accumulate error between NTP and clock interval */
1649 tk
->ntp_error
+= tk
->ntp_tick
<< shift
;
1650 tk
->ntp_error
-= (tk
->xtime_interval
+ tk
->xtime_remainder
) <<
1651 (tk
->ntp_error_shift
+ shift
);
1657 * update_wall_time - Uses the current clocksource to increment the wall time
1660 void update_wall_time(void)
1662 struct timekeeper
*real_tk
= &tk_core
.timekeeper
;
1663 struct timekeeper
*tk
= &shadow_timekeeper
;
1665 int shift
= 0, maxshift
;
1666 unsigned int clock_set
= 0;
1667 unsigned long flags
;
1669 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1671 /* Make sure we're fully resumed: */
1672 if (unlikely(timekeeping_suspended
))
1675 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1676 offset
= real_tk
->cycle_interval
;
1678 offset
= clocksource_delta(tk
->tkr
.read(tk
->tkr
.clock
),
1679 tk
->tkr
.cycle_last
, tk
->tkr
.mask
);
1682 /* Check if there's really nothing to do */
1683 if (offset
< real_tk
->cycle_interval
)
1686 /* Do some additional sanity checking */
1687 timekeeping_check_update(real_tk
, offset
);
1690 * With NO_HZ we may have to accumulate many cycle_intervals
1691 * (think "ticks") worth of time at once. To do this efficiently,
1692 * we calculate the largest doubling multiple of cycle_intervals
1693 * that is smaller than the offset. We then accumulate that
1694 * chunk in one go, and then try to consume the next smaller
1697 shift
= ilog2(offset
) - ilog2(tk
->cycle_interval
);
1698 shift
= max(0, shift
);
1699 /* Bound shift to one less than what overflows tick_length */
1700 maxshift
= (64 - (ilog2(ntp_tick_length())+1)) - 1;
1701 shift
= min(shift
, maxshift
);
1702 while (offset
>= tk
->cycle_interval
) {
1703 offset
= logarithmic_accumulation(tk
, offset
, shift
,
1705 if (offset
< tk
->cycle_interval
<<shift
)
1709 /* correct the clock when NTP error is too big */
1710 timekeeping_adjust(tk
, offset
);
1713 * XXX This can be killed once everyone converts
1714 * to the new update_vsyscall.
1716 old_vsyscall_fixup(tk
);
1719 * Finally, make sure that after the rounding
1720 * xtime_nsec isn't larger than NSEC_PER_SEC
1722 clock_set
|= accumulate_nsecs_to_secs(tk
);
1724 write_seqcount_begin(&tk_core
.seq
);
1726 * Update the real timekeeper.
1728 * We could avoid this memcpy by switching pointers, but that
1729 * requires changes to all other timekeeper usage sites as
1730 * well, i.e. move the timekeeper pointer getter into the
1731 * spinlocked/seqcount protected sections. And we trade this
1732 * memcpy under the tk_core.seq against one before we start
1735 memcpy(real_tk
, tk
, sizeof(*tk
));
1736 timekeeping_update(real_tk
, clock_set
);
1737 write_seqcount_end(&tk_core
.seq
);
1739 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1741 /* Have to call _delayed version, since in irq context*/
1742 clock_was_set_delayed();
1746 * getboottime64 - Return the real time of system boot.
1747 * @ts: pointer to the timespec64 to be set
1749 * Returns the wall-time of boot in a timespec64.
1751 * This is based on the wall_to_monotonic offset and the total suspend
1752 * time. Calls to settimeofday will affect the value returned (which
1753 * basically means that however wrong your real time clock is at boot time,
1754 * you get the right time here).
1756 void getboottime64(struct timespec64
*ts
)
1758 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1759 ktime_t t
= ktime_sub(tk
->offs_real
, tk
->offs_boot
);
1761 *ts
= ktime_to_timespec64(t
);
1763 EXPORT_SYMBOL_GPL(getboottime64
);
1765 unsigned long get_seconds(void)
1767 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1769 return tk
->xtime_sec
;
1771 EXPORT_SYMBOL(get_seconds
);
1773 struct timespec
__current_kernel_time(void)
1775 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1777 return timespec64_to_timespec(tk_xtime(tk
));
1780 struct timespec
current_kernel_time(void)
1782 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1783 struct timespec64 now
;
1787 seq
= read_seqcount_begin(&tk_core
.seq
);
1790 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1792 return timespec64_to_timespec(now
);
1794 EXPORT_SYMBOL(current_kernel_time
);
1796 struct timespec64
get_monotonic_coarse64(void)
1798 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1799 struct timespec64 now
, mono
;
1803 seq
= read_seqcount_begin(&tk_core
.seq
);
1806 mono
= tk
->wall_to_monotonic
;
1807 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1809 set_normalized_timespec64(&now
, now
.tv_sec
+ mono
.tv_sec
,
1810 now
.tv_nsec
+ mono
.tv_nsec
);
1816 * Must hold jiffies_lock
1818 void do_timer(unsigned long ticks
)
1820 jiffies_64
+= ticks
;
1821 calc_global_load(ticks
);
1825 * ktime_get_update_offsets_tick - hrtimer helper
1826 * @offs_real: pointer to storage for monotonic -> realtime offset
1827 * @offs_boot: pointer to storage for monotonic -> boottime offset
1828 * @offs_tai: pointer to storage for monotonic -> clock tai offset
1830 * Returns monotonic time at last tick and various offsets
1832 ktime_t
ktime_get_update_offsets_tick(ktime_t
*offs_real
, ktime_t
*offs_boot
,
1835 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1841 seq
= read_seqcount_begin(&tk_core
.seq
);
1843 base
= tk
->tkr
.base_mono
;
1844 nsecs
= tk
->tkr
.xtime_nsec
>> tk
->tkr
.shift
;
1846 *offs_real
= tk
->offs_real
;
1847 *offs_boot
= tk
->offs_boot
;
1848 *offs_tai
= tk
->offs_tai
;
1849 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1851 return ktime_add_ns(base
, nsecs
);
1854 #ifdef CONFIG_HIGH_RES_TIMERS
1856 * ktime_get_update_offsets_now - hrtimer helper
1857 * @offs_real: pointer to storage for monotonic -> realtime offset
1858 * @offs_boot: pointer to storage for monotonic -> boottime offset
1859 * @offs_tai: pointer to storage for monotonic -> clock tai offset
1861 * Returns current monotonic time and updates the offsets
1862 * Called from hrtimer_interrupt() or retrigger_next_event()
1864 ktime_t
ktime_get_update_offsets_now(ktime_t
*offs_real
, ktime_t
*offs_boot
,
1867 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1873 seq
= read_seqcount_begin(&tk_core
.seq
);
1875 base
= tk
->tkr
.base_mono
;
1876 nsecs
= timekeeping_get_ns(&tk
->tkr
);
1878 *offs_real
= tk
->offs_real
;
1879 *offs_boot
= tk
->offs_boot
;
1880 *offs_tai
= tk
->offs_tai
;
1881 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1883 return ktime_add_ns(base
, nsecs
);
1888 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
1890 int do_adjtimex(struct timex
*txc
)
1892 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1893 unsigned long flags
;
1894 struct timespec64 ts
;
1898 /* Validate the data before disabling interrupts */
1899 ret
= ntp_validate_timex(txc
);
1903 if (txc
->modes
& ADJ_SETOFFSET
) {
1904 struct timespec delta
;
1905 delta
.tv_sec
= txc
->time
.tv_sec
;
1906 delta
.tv_nsec
= txc
->time
.tv_usec
;
1907 if (!(txc
->modes
& ADJ_NANO
))
1908 delta
.tv_nsec
*= 1000;
1909 ret
= timekeeping_inject_offset(&delta
);
1914 getnstimeofday64(&ts
);
1916 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1917 write_seqcount_begin(&tk_core
.seq
);
1919 orig_tai
= tai
= tk
->tai_offset
;
1920 ret
= __do_adjtimex(txc
, &ts
, &tai
);
1922 if (tai
!= orig_tai
) {
1923 __timekeeping_set_tai_offset(tk
, tai
);
1924 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
1926 write_seqcount_end(&tk_core
.seq
);
1927 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1929 if (tai
!= orig_tai
)
1932 ntp_notify_cmos_timer();
1937 #ifdef CONFIG_NTP_PPS
1939 * hardpps() - Accessor function to NTP __hardpps function
1941 void hardpps(const struct timespec
*phase_ts
, const struct timespec
*raw_ts
)
1943 unsigned long flags
;
1945 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1946 write_seqcount_begin(&tk_core
.seq
);
1948 __hardpps(phase_ts
, raw_ts
);
1950 write_seqcount_end(&tk_core
.seq
);
1951 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1953 EXPORT_SYMBOL(hardpps
);
1957 * xtime_update() - advances the timekeeping infrastructure
1958 * @ticks: number of ticks, that have elapsed since the last call.
1960 * Must be called with interrupts disabled.
1962 void xtime_update(unsigned long ticks
)
1964 write_seqlock(&jiffies_lock
);
1966 write_sequnlock(&jiffies_lock
);