1 /*
2 * Copyright (c) 2000-2019 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28 /*
29 * @OSF_COPYRIGHT@
30 */
31 /*
32 */
33 /*-
34 * Copyright (c) 1982, 1986, 1993
35 * The Regents of the University of California. All rights reserved.
36 *
37 * Redistribution and use in source and binary forms, with or without
38 * modification, are permitted provided that the following conditions
39 * are met:
40 * 1. Redistributions of source code must retain the above copyright
41 * notice, this list of conditions and the following disclaimer.
42 * 2. Redistributions in binary form must reproduce the above copyright
43 * notice, this list of conditions and the following disclaimer in the
44 * documentation and/or other materials provided with the distribution.
45 * 4. Neither the name of the University nor the names of its contributors
46 * may be used to endorse or promote products derived from this software
47 * without specific prior written permission.
48 *
49 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
50 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
51 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
52 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
53 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
54 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
55 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
56 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
57 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
58 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
59 * SUCH DAMAGE.
60 *
61 * @(#)time.h 8.5 (Berkeley) 5/4/95
62 * $FreeBSD$
63 */
64
65 #include <mach/mach_types.h>
66
67 #include <kern/spl.h>
68 #include <kern/sched_prim.h>
69 #include <kern/thread.h>
70 #include <kern/clock.h>
71 #include <kern/host_notify.h>
72 #include <kern/thread_call.h>
73 #include <libkern/OSAtomic.h>
74
75 #include <IOKit/IOPlatformExpert.h>
76
77 #include <machine/commpage.h>
78 #include <machine/config.h>
79 #include <machine/machine_routines.h>
80
81 #include <mach/mach_traps.h>
82 #include <mach/mach_time.h>
83
84 #include <sys/kdebug.h>
85 #include <sys/timex.h>
86 #include <kern/arithmetic_128.h>
87 #include <os/log.h>
88
89 #if HIBERNATION && HAS_CONTINUOUS_HWCLOCK
90 // On ARM64, the hwclock keeps ticking across a normal S2R so we use it to reset the
91 // system clock after a normal wake. However, on hibernation we cut power to the hwclock,
92 // so we have to add an offset to the hwclock to compute continuous_time after hibernate resume.
93 uint64_t hwclock_conttime_offset = 0;
94 #endif /* HIBERNATION && HAS_CONTINUOUS_HWCLOCK */
95
96 #if HIBERNATION_USES_LEGACY_CLOCK || !HAS_CONTINUOUS_HWCLOCK
97 #define ENABLE_LEGACY_CLOCK_CODE 1
98 #endif /* HIBERNATION_USES_LEGACY_CLOCK || !HAS_CONTINUOUS_HWCLOCK */
99
100 #if HIBERNATION_USES_LEGACY_CLOCK
101 #include <IOKit/IOHibernatePrivate.h>
102 #endif /* HIBERNATION_USES_LEGACY_CLOCK */
103
104 uint32_t hz_tick_interval = 1;
105 #if ENABLE_LEGACY_CLOCK_CODE
106 static uint64_t has_monotonic_clock = 0;
107 #endif /* ENABLE_LEGACY_CLOCK_CODE */
108
109 lck_ticket_t clock_lock;
110
111 static LCK_GRP_DECLARE(settime_lock_grp, "settime");
112 static LCK_MTX_DECLARE(settime_lock, &settime_lock_grp);
113
114 #define clock_lock() \
115 lck_ticket_lock(&clock_lock, LCK_GRP_NULL)
116
117 #define clock_unlock() \
118 lck_ticket_unlock(&clock_lock)
119
120 boolean_t
kdp_clock_is_locked()121 kdp_clock_is_locked()
122 {
123 return kdp_lck_ticket_is_acquired(&clock_lock);
124 }
125
126 struct bintime {
127 time_t sec;
128 uint64_t frac;
129 };
130
131 static __inline void
bintime_addx(struct bintime * _bt,uint64_t _x)132 bintime_addx(struct bintime *_bt, uint64_t _x)
133 {
134 uint64_t _u;
135
136 _u = _bt->frac;
137 _bt->frac += _x;
138 if (_u > _bt->frac) {
139 _bt->sec++;
140 }
141 }
142
143 static __inline void
bintime_subx(struct bintime * _bt,uint64_t _x)144 bintime_subx(struct bintime *_bt, uint64_t _x)
145 {
146 uint64_t _u;
147
148 _u = _bt->frac;
149 _bt->frac -= _x;
150 if (_u < _bt->frac) {
151 _bt->sec--;
152 }
153 }
154
155 static __inline void
bintime_addns(struct bintime * bt,uint64_t ns)156 bintime_addns(struct bintime *bt, uint64_t ns)
157 {
158 bt->sec += ns / (uint64_t)NSEC_PER_SEC;
159 ns = ns % (uint64_t)NSEC_PER_SEC;
160 if (ns) {
161 /* 18446744073 = int(2^64 / NSEC_PER_SEC) */
162 ns = ns * (uint64_t)18446744073LL;
163 bintime_addx(bt, ns);
164 }
165 }
166
167 static __inline void
bintime_subns(struct bintime * bt,uint64_t ns)168 bintime_subns(struct bintime *bt, uint64_t ns)
169 {
170 bt->sec -= ns / (uint64_t)NSEC_PER_SEC;
171 ns = ns % (uint64_t)NSEC_PER_SEC;
172 if (ns) {
173 /* 18446744073 = int(2^64 / NSEC_PER_SEC) */
174 ns = ns * (uint64_t)18446744073LL;
175 bintime_subx(bt, ns);
176 }
177 }
178
179 static __inline void
bintime_addxns(struct bintime * bt,uint64_t a,int64_t xns)180 bintime_addxns(struct bintime *bt, uint64_t a, int64_t xns)
181 {
182 uint64_t uxns = (xns > 0)?(uint64_t)xns:(uint64_t)-xns;
183 uint64_t ns = multi_overflow(a, uxns);
184 if (xns > 0) {
185 if (ns) {
186 bintime_addns(bt, ns);
187 }
188 ns = (a * uxns) / (uint64_t)NSEC_PER_SEC;
189 bintime_addx(bt, ns);
190 } else {
191 if (ns) {
192 bintime_subns(bt, ns);
193 }
194 ns = (a * uxns) / (uint64_t)NSEC_PER_SEC;
195 bintime_subx(bt, ns);
196 }
197 }
198
199
200 static __inline void
bintime_add(struct bintime * _bt,const struct bintime * _bt2)201 bintime_add(struct bintime *_bt, const struct bintime *_bt2)
202 {
203 uint64_t _u;
204
205 _u = _bt->frac;
206 _bt->frac += _bt2->frac;
207 if (_u > _bt->frac) {
208 _bt->sec++;
209 }
210 _bt->sec += _bt2->sec;
211 }
212
213 static __inline void
bintime_sub(struct bintime * _bt,const struct bintime * _bt2)214 bintime_sub(struct bintime *_bt, const struct bintime *_bt2)
215 {
216 uint64_t _u;
217
218 _u = _bt->frac;
219 _bt->frac -= _bt2->frac;
220 if (_u < _bt->frac) {
221 _bt->sec--;
222 }
223 _bt->sec -= _bt2->sec;
224 }
225
226 static __inline void
clock2bintime(const clock_sec_t * secs,const clock_usec_t * microsecs,struct bintime * _bt)227 clock2bintime(const clock_sec_t *secs, const clock_usec_t *microsecs, struct bintime *_bt)
228 {
229 _bt->sec = *secs;
230 /* 18446744073709 = int(2^64 / 1000000) */
231 _bt->frac = *microsecs * (uint64_t)18446744073709LL;
232 }
233
234 static __inline void
bintime2usclock(const struct bintime * _bt,clock_sec_t * secs,clock_usec_t * microsecs)235 bintime2usclock(const struct bintime *_bt, clock_sec_t *secs, clock_usec_t *microsecs)
236 {
237 *secs = _bt->sec;
238 *microsecs = ((uint64_t)USEC_PER_SEC * (uint32_t)(_bt->frac >> 32)) >> 32;
239 }
240
241 static __inline void
bintime2nsclock(const struct bintime * _bt,clock_sec_t * secs,clock_usec_t * nanosecs)242 bintime2nsclock(const struct bintime *_bt, clock_sec_t *secs, clock_usec_t *nanosecs)
243 {
244 *secs = _bt->sec;
245 *nanosecs = ((uint64_t)NSEC_PER_SEC * (uint32_t)(_bt->frac >> 32)) >> 32;
246 }
247
248 #if ENABLE_LEGACY_CLOCK_CODE
249 static __inline void
bintime2absolutetime(const struct bintime * _bt,uint64_t * abs)250 bintime2absolutetime(const struct bintime *_bt, uint64_t *abs)
251 {
252 uint64_t nsec;
253 nsec = (uint64_t) _bt->sec * (uint64_t)NSEC_PER_SEC + (((uint64_t)NSEC_PER_SEC * (uint32_t)(_bt->frac >> 32)) >> 32);
254 nanoseconds_to_absolutetime(nsec, abs);
255 }
256
257 struct latched_time {
258 uint64_t monotonic_time_usec;
259 uint64_t mach_time;
260 };
261
262 extern int
263 kernel_sysctlbyname(const char *name, void *oldp, size_t *oldlenp, void *newp, size_t newlen);
264
265 #endif /* ENABLE_LEGACY_CLOCK_CODE */
266 /*
267 * Time of day (calendar) variables.
268 *
269 * Algorithm:
270 *
271 * TOD <- bintime + delta*scale
272 *
273 * where :
274 * bintime is a cumulative offset that includes bootime and scaled time elapsed betweed bootime and last scale update.
275 * delta is ticks elapsed since last scale update.
276 * scale is computed according to an adjustment provided by ntp_kern.
277 */
278 static struct clock_calend {
279 uint64_t s_scale_ns; /* scale to apply for each second elapsed, it converts in ns */
280 int64_t s_adj_nsx; /* additional adj to apply for each second elapsed, it is expressed in 64 bit frac of ns */
281 uint64_t tick_scale_x; /* scale to apply for each tick elapsed, it converts in 64 bit frac of s */
282 uint64_t offset_count; /* abs time from which apply current scales */
283 struct bintime offset; /* cumulative offset expressed in (sec, 64 bits frac of a second) */
284 struct bintime bintime; /* cumulative offset (it includes bootime) expressed in (sec, 64 bits frac of a second) */
285 struct bintime boottime; /* boot time expressed in (sec, 64 bits frac of a second) */
286 #if ENABLE_LEGACY_CLOCK_CODE
287 struct bintime basesleep;
288 #endif /* ENABLE_LEGACY_CLOCK_CODE */
289 } clock_calend;
290
291 static uint64_t ticks_per_sec; /* ticks in a second (expressed in abs time) */
292
293 #if DEVELOPMENT || DEBUG
294 extern int g_should_log_clock_adjustments;
295
296 static void print_all_clock_variables(const char*, clock_sec_t* pmu_secs, clock_usec_t* pmu_usec, clock_sec_t* sys_secs, clock_usec_t* sys_usec, struct clock_calend* calend_cp);
297 static void print_all_clock_variables_internal(const char *, struct clock_calend* calend_cp);
298 #else
299 #define print_all_clock_variables(...) do { } while (0)
300 #define print_all_clock_variables_internal(...) do { } while (0)
301 #endif
302
303 #if CONFIG_DTRACE
304
305
306 /*
307 * Unlocked calendar flipflop; this is used to track a clock_calend such
308 * that we can safely access a snapshot of a valid clock_calend structure
309 * without needing to take any locks to do it.
310 *
311 * The trick is to use a generation count and set the low bit when it is
312 * being updated/read; by doing this, we guarantee, through use of the
313 * os_atomic functions, that the generation is incremented when the bit
314 * is cleared atomically (by using a 1 bit add).
315 */
316 static struct unlocked_clock_calend {
317 struct clock_calend calend; /* copy of calendar */
318 uint32_t gen; /* generation count */
319 } flipflop[2];
320
321 static void clock_track_calend_nowait(void);
322
323 #endif
324
325 void _clock_delay_until_deadline(uint64_t interval, uint64_t deadline);
326 void _clock_delay_until_deadline_with_leeway(uint64_t interval, uint64_t deadline, uint64_t leeway);
327
328 /* Boottime variables*/
329 static uint64_t clock_boottime;
330 static uint32_t clock_boottime_usec;
331
332 #define TIME_ADD(rsecs, secs, rfrac, frac, unit) \
333 MACRO_BEGIN \
334 if (((rfrac) += (frac)) >= (unit)) { \
335 (rfrac) -= (unit); \
336 (rsecs) += 1; \
337 } \
338 (rsecs) += (secs); \
339 MACRO_END
340
341 #define TIME_SUB(rsecs, secs, rfrac, frac, unit) \
342 MACRO_BEGIN \
343 if ((int)((rfrac) -= (frac)) < 0) { \
344 (rfrac) += (unit); \
345 (rsecs) -= 1; \
346 } \
347 (rsecs) -= (secs); \
348 MACRO_END
349
350 /*
351 * clock_config:
352 *
353 * Called once at boot to configure the clock subsystem.
354 */
355 void
clock_config(void)356 clock_config(void)
357 {
358 lck_ticket_init(&clock_lock, 0);
359
360 clock_oldconfig();
361
362 ntp_init();
363
364 nanoseconds_to_absolutetime((uint64_t)NSEC_PER_SEC, &ticks_per_sec);
365 }
366
367 /*
368 * clock_init:
369 *
370 * Called on a processor each time started.
371 */
372 void
clock_init(void)373 clock_init(void)
374 {
375 clock_oldinit();
376 }
377
378 /*
379 * clock_timebase_init:
380 *
381 * Called by machine dependent code
382 * to initialize areas dependent on the
383 * timebase value. May be called multiple
384 * times during start up.
385 */
386 void
clock_timebase_init(void)387 clock_timebase_init(void)
388 {
389 uint64_t abstime;
390
391 nanoseconds_to_absolutetime(NSEC_PER_SEC / 100, &abstime);
392 hz_tick_interval = (uint32_t)abstime;
393
394 sched_timebase_init();
395 }
396
397 /*
398 * mach_timebase_info_trap:
399 *
400 * User trap returns timebase constant.
401 */
402 kern_return_t
mach_timebase_info_trap(struct mach_timebase_info_trap_args * args)403 mach_timebase_info_trap(
404 struct mach_timebase_info_trap_args *args)
405 {
406 mach_vm_address_t out_info_addr = args->info;
407 mach_timebase_info_data_t info = {};
408
409 clock_timebase_info(&info);
410
411 copyout((void *)&info, out_info_addr, sizeof(info));
412
413 return KERN_SUCCESS;
414 }
415
416 /*
417 * Calendar routines.
418 */
419
420 /*
421 * clock_get_calendar_microtime:
422 *
423 * Returns the current calendar value,
424 * microseconds as the fraction.
425 */
426 void
clock_get_calendar_microtime(clock_sec_t * secs,clock_usec_t * microsecs)427 clock_get_calendar_microtime(
428 clock_sec_t *secs,
429 clock_usec_t *microsecs)
430 {
431 clock_get_calendar_absolute_and_microtime(secs, microsecs, NULL);
432 }
433
434 /*
435 * get_scale_factors_from_adj:
436 *
437 * computes scale factors from the value given in adjustment.
438 *
439 * Part of the code has been taken from tc_windup of FreeBSD
440 * written by Poul-Henning Kamp <[email protected]>, Julien Ridoux and
441 * Konstantin Belousov.
442 * https://github.com/freebsd/freebsd/blob/master/sys/kern/kern_tc.c
443 */
444 static void
get_scale_factors_from_adj(int64_t adjustment,uint64_t * tick_scale_x,uint64_t * s_scale_ns,int64_t * s_adj_nsx)445 get_scale_factors_from_adj(int64_t adjustment, uint64_t* tick_scale_x, uint64_t* s_scale_ns, int64_t* s_adj_nsx)
446 {
447 uint64_t scale;
448 int64_t nano, frac;
449
450 /*-
451 * Calculating the scaling factor. We want the number of 1/2^64
452 * fractions of a second per period of the hardware counter, taking
453 * into account the th_adjustment factor which the NTP PLL/adjtime(2)
454 * processing provides us with.
455 *
456 * The th_adjustment is nanoseconds per second with 32 bit binary
457 * fraction and we want 64 bit binary fraction of second:
458 *
459 * x = a * 2^32 / 10^9 = a * 4.294967296
460 *
461 * The range of th_adjustment is +/- 5000PPM so inside a 64bit int
462 * we can only multiply by about 850 without overflowing, that
463 * leaves no suitably precise fractions for multiply before divide.
464 *
465 * Divide before multiply with a fraction of 2199/512 results in a
466 * systematic undercompensation of 10PPM of th_adjustment. On a
467 * 5000PPM adjustment this is a 0.05PPM error. This is acceptable.
468 *
469 * We happily sacrifice the lowest of the 64 bits of our result
470 * to the goddess of code clarity.
471 *
472 */
473 scale = (uint64_t)1 << 63;
474 scale += (adjustment / 1024) * 2199;
475 scale /= ticks_per_sec;
476 *tick_scale_x = scale * 2;
477
478 /*
479 * hi part of adj
480 * it contains ns (without fraction) to add to the next sec.
481 * Get ns scale factor for the next sec.
482 */
483 nano = (adjustment > 0)? adjustment >> 32 : -((-adjustment) >> 32);
484 scale = (uint64_t) NSEC_PER_SEC;
485 scale += nano;
486 *s_scale_ns = scale;
487
488 /*
489 * lo part of adj
490 * it contains 32 bit frac of ns to add to the next sec.
491 * Keep it as additional adjustment for the next sec.
492 */
493 frac = (adjustment > 0)? ((uint32_t) adjustment) : -((uint32_t) (-adjustment));
494 *s_adj_nsx = (frac > 0)? ((uint64_t) frac) << 32 : -(((uint64_t) (-frac)) << 32);
495
496 return;
497 }
498
499 /*
500 * scale_delta:
501 *
502 * returns a bintime struct representing delta scaled accordingly to the
503 * scale factors provided to this function.
504 */
505 static struct bintime
scale_delta(uint64_t delta,uint64_t tick_scale_x,uint64_t s_scale_ns,int64_t s_adj_nsx)506 scale_delta(uint64_t delta, uint64_t tick_scale_x, uint64_t s_scale_ns, int64_t s_adj_nsx)
507 {
508 uint64_t sec, new_ns, over;
509 struct bintime bt;
510
511 bt.sec = 0;
512 bt.frac = 0;
513
514 /*
515 * If more than one second is elapsed,
516 * scale fully elapsed seconds using scale factors for seconds.
517 * s_scale_ns -> scales sec to ns.
518 * s_adj_nsx -> additional adj expressed in 64 bit frac of ns to apply to each sec.
519 */
520 if (delta > ticks_per_sec) {
521 sec = (delta / ticks_per_sec);
522 new_ns = sec * s_scale_ns;
523 bintime_addns(&bt, new_ns);
524 if (s_adj_nsx) {
525 if (sec == 1) {
526 /* shortcut, no overflow can occur */
527 if (s_adj_nsx > 0) {
528 bintime_addx(&bt, (uint64_t)s_adj_nsx / (uint64_t)NSEC_PER_SEC);
529 } else {
530 bintime_subx(&bt, (uint64_t)-s_adj_nsx / (uint64_t)NSEC_PER_SEC);
531 }
532 } else {
533 /*
534 * s_adj_nsx is 64 bit frac of ns.
535 * sec*s_adj_nsx might overflow in int64_t.
536 * use bintime_addxns to not lose overflowed ns.
537 */
538 bintime_addxns(&bt, sec, s_adj_nsx);
539 }
540 }
541 delta = (delta % ticks_per_sec);
542 }
543
544 over = multi_overflow(tick_scale_x, delta);
545 if (over) {
546 bt.sec += over;
547 }
548
549 /*
550 * scale elapsed ticks using the scale factor for ticks.
551 */
552 bintime_addx(&bt, delta * tick_scale_x);
553
554 return bt;
555 }
556
557 /*
558 * get_scaled_time:
559 *
560 * returns the scaled time of the time elapsed from the last time
561 * scale factors were updated to now.
562 */
563 static struct bintime
get_scaled_time(uint64_t now)564 get_scaled_time(uint64_t now)
565 {
566 uint64_t delta;
567
568 /*
569 * Compute ticks elapsed since last scale update.
570 * This time will be scaled according to the value given by ntp kern.
571 */
572 delta = now - clock_calend.offset_count;
573
574 return scale_delta(delta, clock_calend.tick_scale_x, clock_calend.s_scale_ns, clock_calend.s_adj_nsx);
575 }
576
577 static void
clock_get_calendar_absolute_and_microtime_locked(clock_sec_t * secs,clock_usec_t * microsecs,uint64_t * abstime)578 clock_get_calendar_absolute_and_microtime_locked(
579 clock_sec_t *secs,
580 clock_usec_t *microsecs,
581 uint64_t *abstime)
582 {
583 uint64_t now;
584 struct bintime bt;
585
586 now = mach_absolute_time();
587 if (abstime) {
588 *abstime = now;
589 }
590
591 bt = get_scaled_time(now);
592 bintime_add(&bt, &clock_calend.bintime);
593 bintime2usclock(&bt, secs, microsecs);
594 }
595
596 static void
clock_get_calendar_absolute_and_nanotime_locked(clock_sec_t * secs,clock_usec_t * nanosecs,uint64_t * abstime)597 clock_get_calendar_absolute_and_nanotime_locked(
598 clock_sec_t *secs,
599 clock_usec_t *nanosecs,
600 uint64_t *abstime)
601 {
602 uint64_t now;
603 struct bintime bt;
604
605 now = mach_absolute_time();
606 if (abstime) {
607 *abstime = now;
608 }
609
610 bt = get_scaled_time(now);
611 bintime_add(&bt, &clock_calend.bintime);
612 bintime2nsclock(&bt, secs, nanosecs);
613 }
614
615 /*
616 * clock_get_calendar_absolute_and_microtime:
617 *
618 * Returns the current calendar value,
619 * microseconds as the fraction. Also
620 * returns mach_absolute_time if abstime
621 * is not NULL.
622 */
623 void
clock_get_calendar_absolute_and_microtime(clock_sec_t * secs,clock_usec_t * microsecs,uint64_t * abstime)624 clock_get_calendar_absolute_and_microtime(
625 clock_sec_t *secs,
626 clock_usec_t *microsecs,
627 uint64_t *abstime)
628 {
629 spl_t s;
630
631 s = splclock();
632 clock_lock();
633
634 clock_get_calendar_absolute_and_microtime_locked(secs, microsecs, abstime);
635
636 clock_unlock();
637 splx(s);
638 }
639
640 /*
641 * clock_get_calendar_nanotime:
642 *
643 * Returns the current calendar value,
644 * nanoseconds as the fraction.
645 *
646 * Since we do not have an interface to
647 * set the calendar with resolution greater
648 * than a microsecond, we honor that here.
649 */
650 void
clock_get_calendar_nanotime(clock_sec_t * secs,clock_nsec_t * nanosecs)651 clock_get_calendar_nanotime(
652 clock_sec_t *secs,
653 clock_nsec_t *nanosecs)
654 {
655 spl_t s;
656
657 s = splclock();
658 clock_lock();
659
660 clock_get_calendar_absolute_and_nanotime_locked(secs, nanosecs, NULL);
661
662 clock_unlock();
663 splx(s);
664 }
665
666 /*
667 * clock_gettimeofday:
668 *
669 * Kernel interface for commpage implementation of
670 * gettimeofday() syscall.
671 *
672 * Returns the current calendar value, and updates the
673 * commpage info as appropriate. Because most calls to
674 * gettimeofday() are handled in user mode by the commpage,
675 * this routine should be used infrequently.
676 */
677 void
clock_gettimeofday(clock_sec_t * secs,clock_usec_t * microsecs)678 clock_gettimeofday(
679 clock_sec_t *secs,
680 clock_usec_t *microsecs)
681 {
682 clock_gettimeofday_and_absolute_time(secs, microsecs, NULL);
683 }
684
685 void
clock_gettimeofday_and_absolute_time(clock_sec_t * secs,clock_usec_t * microsecs,uint64_t * mach_time)686 clock_gettimeofday_and_absolute_time(
687 clock_sec_t *secs,
688 clock_usec_t *microsecs,
689 uint64_t *mach_time)
690 {
691 uint64_t now;
692 spl_t s;
693 struct bintime bt;
694
695 s = splclock();
696 clock_lock();
697
698 now = mach_absolute_time();
699 bt = get_scaled_time(now);
700 bintime_add(&bt, &clock_calend.bintime);
701 bintime2usclock(&bt, secs, microsecs);
702
703 clock_gettimeofday_set_commpage(now, bt.sec, bt.frac, clock_calend.tick_scale_x, ticks_per_sec);
704
705 clock_unlock();
706 splx(s);
707
708 if (mach_time) {
709 *mach_time = now;
710 }
711 }
712
713 /*
714 * clock_set_calendar_microtime:
715 *
716 * Sets the current calendar value by
717 * recalculating the epoch and offset
718 * from the system clock.
719 *
720 * Also adjusts the boottime to keep the
721 * value consistent, writes the new
722 * calendar value to the platform clock,
723 * and sends calendar change notifications.
724 */
725 void
clock_set_calendar_microtime(clock_sec_t secs,clock_usec_t microsecs)726 clock_set_calendar_microtime(
727 clock_sec_t secs,
728 clock_usec_t microsecs)
729 {
730 uint64_t absolutesys;
731 clock_sec_t newsecs;
732 clock_sec_t oldsecs;
733 clock_usec_t newmicrosecs;
734 clock_usec_t oldmicrosecs;
735 uint64_t commpage_value;
736 spl_t s;
737 struct bintime bt;
738 clock_sec_t deltasecs;
739 clock_usec_t deltamicrosecs;
740
741 newsecs = secs;
742 newmicrosecs = microsecs;
743
744 /*
745 * settime_lock mtx is used to avoid that racing settimeofdays update the wall clock and
746 * the platform clock concurrently.
747 *
748 * clock_lock cannot be used for this race because it is acquired from interrupt context
749 * and it needs interrupts disabled while instead updating the platform clock needs to be
750 * called with interrupts enabled.
751 */
752 lck_mtx_lock(&settime_lock);
753
754 s = splclock();
755 clock_lock();
756
757 #if DEVELOPMENT || DEBUG
758 struct clock_calend clock_calend_cp = clock_calend;
759 #endif
760 commpage_disable_timestamp();
761
762 /*
763 * Adjust the boottime based on the delta.
764 */
765 clock_get_calendar_absolute_and_microtime_locked(&oldsecs, &oldmicrosecs, &absolutesys);
766
767 #if DEVELOPMENT || DEBUG
768 if (g_should_log_clock_adjustments) {
769 os_log(OS_LOG_DEFAULT, "%s wall %lu s %d u computed with %llu abs\n",
770 __func__, (unsigned long)oldsecs, oldmicrosecs, absolutesys);
771 os_log(OS_LOG_DEFAULT, "%s requested %lu s %d u\n",
772 __func__, (unsigned long)secs, microsecs );
773 }
774 #endif
775
776 if (oldsecs < secs || (oldsecs == secs && oldmicrosecs < microsecs)) {
777 // moving forwards
778 deltasecs = secs;
779 deltamicrosecs = microsecs;
780
781 TIME_SUB(deltasecs, oldsecs, deltamicrosecs, oldmicrosecs, USEC_PER_SEC);
782
783 TIME_ADD(clock_boottime, deltasecs, clock_boottime_usec, deltamicrosecs, USEC_PER_SEC);
784 clock2bintime(&deltasecs, &deltamicrosecs, &bt);
785 bintime_add(&clock_calend.boottime, &bt);
786 } else {
787 // moving backwards
788 deltasecs = oldsecs;
789 deltamicrosecs = oldmicrosecs;
790
791 TIME_SUB(deltasecs, secs, deltamicrosecs, microsecs, USEC_PER_SEC);
792
793 TIME_SUB(clock_boottime, deltasecs, clock_boottime_usec, deltamicrosecs, USEC_PER_SEC);
794 clock2bintime(&deltasecs, &deltamicrosecs, &bt);
795 bintime_sub(&clock_calend.boottime, &bt);
796 }
797
798 clock_calend.bintime = clock_calend.boottime;
799 bintime_add(&clock_calend.bintime, &clock_calend.offset);
800
801 clock2bintime((clock_sec_t *) &secs, (clock_usec_t *) µsecs, &bt);
802
803 clock_gettimeofday_set_commpage(absolutesys, bt.sec, bt.frac, clock_calend.tick_scale_x, ticks_per_sec);
804
805 #if DEVELOPMENT || DEBUG
806 struct clock_calend clock_calend_cp1 = clock_calend;
807 #endif
808
809 commpage_value = clock_boottime * USEC_PER_SEC + clock_boottime_usec;
810
811 clock_unlock();
812 splx(s);
813
814 /*
815 * Set the new value for the platform clock.
816 * This call might block, so interrupts must be enabled.
817 */
818 #if DEVELOPMENT || DEBUG
819 uint64_t now_b = mach_absolute_time();
820 #endif
821
822 PESetUTCTimeOfDay(newsecs, newmicrosecs);
823
824 #if DEVELOPMENT || DEBUG
825 uint64_t now_a = mach_absolute_time();
826 if (g_should_log_clock_adjustments) {
827 os_log(OS_LOG_DEFAULT, "%s mach bef PESet %llu mach aft %llu \n", __func__, now_b, now_a);
828 }
829 #endif
830
831 print_all_clock_variables_internal(__func__, &clock_calend_cp);
832 print_all_clock_variables_internal(__func__, &clock_calend_cp1);
833
834 commpage_update_boottime(commpage_value);
835
836 /*
837 * Send host notifications.
838 */
839 host_notify_calendar_change();
840 host_notify_calendar_set();
841
842 #if CONFIG_DTRACE
843 clock_track_calend_nowait();
844 #endif
845
846 lck_mtx_unlock(&settime_lock);
847 }
848
849 uint64_t mach_absolutetime_asleep = 0;
850 uint64_t mach_absolutetime_last_sleep = 0;
851
852 void
clock_get_calendar_uptime(clock_sec_t * secs)853 clock_get_calendar_uptime(clock_sec_t *secs)
854 {
855 uint64_t now;
856 spl_t s;
857 struct bintime bt;
858
859 s = splclock();
860 clock_lock();
861
862 now = mach_absolute_time();
863
864 bt = get_scaled_time(now);
865 bintime_add(&bt, &clock_calend.offset);
866
867 *secs = bt.sec;
868
869 clock_unlock();
870 splx(s);
871 }
872
873
874 /*
875 * clock_update_calendar:
876 *
877 * called by ntp timer to update scale factors.
878 */
879 void
clock_update_calendar(void)880 clock_update_calendar(void)
881 {
882 uint64_t now, delta;
883 struct bintime bt;
884 spl_t s;
885 int64_t adjustment;
886
887 s = splclock();
888 clock_lock();
889
890 now = mach_absolute_time();
891
892 /*
893 * scale the time elapsed since the last update and
894 * add it to offset.
895 */
896 bt = get_scaled_time(now);
897 bintime_add(&clock_calend.offset, &bt);
898
899 /*
900 * update the base from which apply next scale factors.
901 */
902 delta = now - clock_calend.offset_count;
903 clock_calend.offset_count += delta;
904
905 clock_calend.bintime = clock_calend.offset;
906 bintime_add(&clock_calend.bintime, &clock_calend.boottime);
907
908 /*
909 * recompute next adjustment.
910 */
911 ntp_update_second(&adjustment, clock_calend.bintime.sec);
912
913 #if DEVELOPMENT || DEBUG
914 if (g_should_log_clock_adjustments) {
915 os_log(OS_LOG_DEFAULT, "%s adjustment %lld\n", __func__, adjustment);
916 }
917 #endif
918
919 /*
920 * recomputing scale factors.
921 */
922 get_scale_factors_from_adj(adjustment, &clock_calend.tick_scale_x, &clock_calend.s_scale_ns, &clock_calend.s_adj_nsx);
923
924 clock_gettimeofday_set_commpage(now, clock_calend.bintime.sec, clock_calend.bintime.frac, clock_calend.tick_scale_x, ticks_per_sec);
925
926 #if DEVELOPMENT || DEBUG
927 struct clock_calend calend_cp = clock_calend;
928 #endif
929
930 clock_unlock();
931 splx(s);
932
933 print_all_clock_variables(__func__, NULL, NULL, NULL, NULL, &calend_cp);
934 }
935
936
937 #if DEVELOPMENT || DEBUG
938
939 void
print_all_clock_variables_internal(const char * func,struct clock_calend * clock_calend_cp)940 print_all_clock_variables_internal(const char* func, struct clock_calend* clock_calend_cp)
941 {
942 clock_sec_t offset_secs;
943 clock_usec_t offset_microsecs;
944 clock_sec_t bintime_secs;
945 clock_usec_t bintime_microsecs;
946 clock_sec_t bootime_secs;
947 clock_usec_t bootime_microsecs;
948
949 if (!g_should_log_clock_adjustments) {
950 return;
951 }
952
953 bintime2usclock(&clock_calend_cp->offset, &offset_secs, &offset_microsecs);
954 bintime2usclock(&clock_calend_cp->bintime, &bintime_secs, &bintime_microsecs);
955 bintime2usclock(&clock_calend_cp->boottime, &bootime_secs, &bootime_microsecs);
956
957 os_log(OS_LOG_DEFAULT, "%s s_scale_ns %llu s_adj_nsx %lld tick_scale_x %llu offset_count %llu\n",
958 func, clock_calend_cp->s_scale_ns, clock_calend_cp->s_adj_nsx,
959 clock_calend_cp->tick_scale_x, clock_calend_cp->offset_count);
960 os_log(OS_LOG_DEFAULT, "%s offset.sec %ld offset.frac %llu offset_secs %lu offset_microsecs %d\n",
961 func, clock_calend_cp->offset.sec, clock_calend_cp->offset.frac,
962 (unsigned long)offset_secs, offset_microsecs);
963 os_log(OS_LOG_DEFAULT, "%s bintime.sec %ld bintime.frac %llu bintime_secs %lu bintime_microsecs %d\n",
964 func, clock_calend_cp->bintime.sec, clock_calend_cp->bintime.frac,
965 (unsigned long)bintime_secs, bintime_microsecs);
966 os_log(OS_LOG_DEFAULT, "%s bootime.sec %ld bootime.frac %llu bootime_secs %lu bootime_microsecs %d\n",
967 func, clock_calend_cp->boottime.sec, clock_calend_cp->boottime.frac,
968 (unsigned long)bootime_secs, bootime_microsecs);
969
970 #if !HAS_CONTINUOUS_HWCLOCK
971 clock_sec_t basesleep_secs;
972 clock_usec_t basesleep_microsecs;
973
974 bintime2usclock(&clock_calend_cp->basesleep, &basesleep_secs, &basesleep_microsecs);
975 os_log(OS_LOG_DEFAULT, "%s basesleep.sec %ld basesleep.frac %llu basesleep_secs %lu basesleep_microsecs %d\n",
976 func, clock_calend_cp->basesleep.sec, clock_calend_cp->basesleep.frac,
977 (unsigned long)basesleep_secs, basesleep_microsecs);
978 #endif
979 }
980
981
982 void
print_all_clock_variables(const char * func,clock_sec_t * pmu_secs,clock_usec_t * pmu_usec,clock_sec_t * sys_secs,clock_usec_t * sys_usec,struct clock_calend * clock_calend_cp)983 print_all_clock_variables(const char* func, clock_sec_t* pmu_secs, clock_usec_t* pmu_usec, clock_sec_t* sys_secs, clock_usec_t* sys_usec, struct clock_calend* clock_calend_cp)
984 {
985 if (!g_should_log_clock_adjustments) {
986 return;
987 }
988
989 struct bintime bt;
990 clock_sec_t wall_secs;
991 clock_usec_t wall_microsecs;
992 uint64_t now;
993 uint64_t delta;
994
995 if (pmu_secs) {
996 os_log(OS_LOG_DEFAULT, "%s PMU %lu s %d u \n", func, (unsigned long)*pmu_secs, *pmu_usec);
997 }
998 if (sys_secs) {
999 os_log(OS_LOG_DEFAULT, "%s sys %lu s %d u \n", func, (unsigned long)*sys_secs, *sys_usec);
1000 }
1001
1002 print_all_clock_variables_internal(func, clock_calend_cp);
1003
1004 now = mach_absolute_time();
1005 delta = now - clock_calend_cp->offset_count;
1006
1007 bt = scale_delta(delta, clock_calend_cp->tick_scale_x, clock_calend_cp->s_scale_ns, clock_calend_cp->s_adj_nsx);
1008 bintime_add(&bt, &clock_calend_cp->bintime);
1009 bintime2usclock(&bt, &wall_secs, &wall_microsecs);
1010
1011 os_log(OS_LOG_DEFAULT, "%s wall %lu s %d u computed with %llu abs\n",
1012 func, (unsigned long)wall_secs, wall_microsecs, now);
1013 }
1014
1015
1016 #endif /* DEVELOPMENT || DEBUG */
1017
1018
1019 /*
1020 * clock_initialize_calendar:
1021 *
1022 * Set the calendar and related clocks
1023 * from the platform clock at boot.
1024 *
1025 * Also sends host notifications.
1026 */
1027 void
clock_initialize_calendar(void)1028 clock_initialize_calendar(void)
1029 {
1030 clock_sec_t sys; // sleepless time since boot in seconds
1031 clock_sec_t secs; // Current UTC time
1032 clock_sec_t utc_offset_secs; // Difference in current UTC time and sleepless time since boot
1033 clock_usec_t microsys;
1034 clock_usec_t microsecs;
1035 clock_usec_t utc_offset_microsecs;
1036 spl_t s;
1037 struct bintime bt;
1038 #if ENABLE_LEGACY_CLOCK_CODE
1039 struct bintime monotonic_bt;
1040 struct latched_time monotonic_time;
1041 uint64_t monotonic_usec_total;
1042 clock_sec_t sys2, monotonic_sec;
1043 clock_usec_t microsys2, monotonic_usec;
1044 size_t size;
1045
1046 #endif /* ENABLE_LEGACY_CLOCK_CODE */
1047 //Get the UTC time and corresponding sys time
1048 PEGetUTCTimeOfDay(&secs, µsecs);
1049 clock_get_system_microtime(&sys, µsys);
1050
1051 #if ENABLE_LEGACY_CLOCK_CODE
1052 /*
1053 * If the platform has a monotonic clock, use kern.monotonicclock_usecs
1054 * to estimate the sleep/wake time, otherwise use the UTC time to estimate
1055 * the sleep time.
1056 */
1057 size = sizeof(monotonic_time);
1058 if (kernel_sysctlbyname("kern.monotonicclock_usecs", &monotonic_time, &size, NULL, 0) != 0) {
1059 has_monotonic_clock = 0;
1060 os_log(OS_LOG_DEFAULT, "%s system does not have monotonic clock\n", __func__);
1061 } else {
1062 has_monotonic_clock = 1;
1063 monotonic_usec_total = monotonic_time.monotonic_time_usec;
1064 absolutetime_to_microtime(monotonic_time.mach_time, &sys2, µsys2);
1065 os_log(OS_LOG_DEFAULT, "%s system has monotonic clock\n", __func__);
1066 }
1067 #endif /* ENABLE_LEGACY_CLOCK_CODE */
1068
1069 s = splclock();
1070 clock_lock();
1071
1072 commpage_disable_timestamp();
1073
1074 utc_offset_secs = secs;
1075 utc_offset_microsecs = microsecs;
1076
1077 /*
1078 * We normally expect the UTC clock to be always-on and produce
1079 * greater readings than the tick counter. There may be corner cases
1080 * due to differing clock resolutions (UTC clock is likely lower) and
1081 * and errors reading the UTC clock (some implementations return 0
1082 * on error) in which that doesn't hold true. Bring the UTC measurements
1083 * in-line with the tick counter measurements as a best effort in that case.
1084 */
1085 if ((sys > secs) || ((sys == secs) && (microsys > microsecs))) {
1086 os_log(OS_LOG_DEFAULT, "%s WARNING: UTC time is less then sys time, (%lu s %d u) UTC (%lu s %d u) sys\n",
1087 __func__, (unsigned long) secs, microsecs, (unsigned long)sys, microsys);
1088 secs = utc_offset_secs = sys;
1089 microsecs = utc_offset_microsecs = microsys;
1090 }
1091
1092 // UTC - sys
1093 // This macro stores the subtraction result in utc_offset_secs and utc_offset_microsecs
1094 TIME_SUB(utc_offset_secs, sys, utc_offset_microsecs, microsys, USEC_PER_SEC);
1095 // This function converts utc_offset_secs and utc_offset_microsecs in bintime
1096 clock2bintime(&utc_offset_secs, &utc_offset_microsecs, &bt);
1097
1098 /*
1099 * Initialize the boot time based on the platform clock.
1100 */
1101 clock_boottime = secs;
1102 clock_boottime_usec = microsecs;
1103 commpage_update_boottime(clock_boottime * USEC_PER_SEC + clock_boottime_usec);
1104
1105 nanoseconds_to_absolutetime((uint64_t)NSEC_PER_SEC, &ticks_per_sec);
1106 clock_calend.boottime = bt;
1107 clock_calend.bintime = bt;
1108 clock_calend.offset.sec = 0;
1109 clock_calend.offset.frac = 0;
1110
1111 clock_calend.tick_scale_x = (uint64_t)1 << 63;
1112 clock_calend.tick_scale_x /= ticks_per_sec;
1113 clock_calend.tick_scale_x *= 2;
1114
1115 clock_calend.s_scale_ns = NSEC_PER_SEC;
1116 clock_calend.s_adj_nsx = 0;
1117
1118 #if ENABLE_LEGACY_CLOCK_CODE
1119 if (has_monotonic_clock) {
1120 OS_ANALYZER_SUPPRESS("82347749") monotonic_sec = monotonic_usec_total / (clock_sec_t)USEC_PER_SEC;
1121 monotonic_usec = monotonic_usec_total % (clock_usec_t)USEC_PER_SEC;
1122
1123 // monotonic clock - sys
1124 // This macro stores the subtraction result in monotonic_sec and monotonic_usec
1125 TIME_SUB(monotonic_sec, sys2, monotonic_usec, microsys2, USEC_PER_SEC);
1126 clock2bintime(&monotonic_sec, &monotonic_usec, &monotonic_bt);
1127
1128 // set the baseleep as the difference between monotonic clock - sys
1129 clock_calend.basesleep = monotonic_bt;
1130 }
1131 #endif /* ENABLE_LEGACY_CLOCK_CODE */
1132 commpage_update_mach_continuous_time(mach_absolutetime_asleep);
1133
1134 #if DEVELOPMENT || DEBUG
1135 struct clock_calend clock_calend_cp = clock_calend;
1136 #endif
1137
1138 clock_unlock();
1139 splx(s);
1140
1141 print_all_clock_variables(__func__, &secs, µsecs, &sys, µsys, &clock_calend_cp);
1142
1143 /*
1144 * Send host notifications.
1145 */
1146 host_notify_calendar_change();
1147
1148 #if CONFIG_DTRACE
1149 clock_track_calend_nowait();
1150 #endif
1151 }
1152
1153 #if HAS_CONTINUOUS_HWCLOCK
1154
1155 static void
scale_sleep_time(void)1156 scale_sleep_time(void)
1157 {
1158 /* Apply the current NTP frequency adjustment to the time slept.
1159 * The frequency adjustment remains stable between calls to ntp_adjtime(),
1160 * and should thus provide a reasonable approximation of the total adjustment
1161 * required for the time slept. */
1162 struct bintime sleep_time;
1163 uint64_t tick_scale_x, s_scale_ns;
1164 int64_t s_adj_nsx;
1165 int64_t sleep_adj = ntp_get_freq();
1166 if (sleep_adj) {
1167 get_scale_factors_from_adj(sleep_adj, &tick_scale_x, &s_scale_ns, &s_adj_nsx);
1168 sleep_time = scale_delta(mach_absolutetime_last_sleep, tick_scale_x, s_scale_ns, s_adj_nsx);
1169 } else {
1170 tick_scale_x = (uint64_t)1 << 63;
1171 tick_scale_x /= ticks_per_sec;
1172 tick_scale_x *= 2;
1173 sleep_time.sec = mach_absolutetime_last_sleep / ticks_per_sec;
1174 sleep_time.frac = (mach_absolutetime_last_sleep % ticks_per_sec) * tick_scale_x;
1175 }
1176 bintime_add(&clock_calend.offset, &sleep_time);
1177 bintime_add(&clock_calend.bintime, &sleep_time);
1178 }
1179
1180 static void
clock_wakeup_calendar_hwclock(void)1181 clock_wakeup_calendar_hwclock(void)
1182 {
1183 spl_t s;
1184
1185 s = splclock();
1186 clock_lock();
1187
1188 commpage_disable_timestamp();
1189
1190 uint64_t abstime = mach_absolute_time();
1191 uint64_t total_sleep_time = mach_continuous_time() - abstime;
1192
1193 mach_absolutetime_last_sleep = total_sleep_time - mach_absolutetime_asleep;
1194 mach_absolutetime_asleep = total_sleep_time;
1195
1196 scale_sleep_time();
1197
1198 KDBG_RELEASE(MACHDBG_CODE(DBG_MACH_CLOCK, MACH_EPOCH_CHANGE),
1199 (uintptr_t)mach_absolutetime_last_sleep,
1200 (uintptr_t)mach_absolutetime_asleep,
1201 (uintptr_t)(mach_absolutetime_last_sleep >> 32),
1202 (uintptr_t)(mach_absolutetime_asleep >> 32));
1203
1204 commpage_update_mach_continuous_time(mach_absolutetime_asleep);
1205 #if HIBERNATION
1206 commpage_update_mach_continuous_time_hw_offset(hwclock_conttime_offset);
1207 #endif
1208 adjust_cont_time_thread_calls();
1209
1210 clock_unlock();
1211 splx(s);
1212
1213 host_notify_calendar_change();
1214
1215 #if CONFIG_DTRACE
1216 clock_track_calend_nowait();
1217 #endif
1218 }
1219
1220 #endif /* HAS_CONTINUOUS_HWCLOCK */
1221
1222 #if ENABLE_LEGACY_CLOCK_CODE
1223
1224 static void
clock_wakeup_calendar_legacy(void)1225 clock_wakeup_calendar_legacy(void)
1226 {
1227 clock_sec_t wake_sys_sec;
1228 clock_usec_t wake_sys_usec;
1229 clock_sec_t wake_sec;
1230 clock_usec_t wake_usec;
1231 clock_sec_t wall_time_sec;
1232 clock_usec_t wall_time_usec;
1233 clock_sec_t diff_sec;
1234 clock_usec_t diff_usec;
1235 clock_sec_t var_s;
1236 clock_usec_t var_us;
1237 spl_t s;
1238 struct bintime bt, last_sleep_bt;
1239 struct latched_time monotonic_time;
1240 uint64_t monotonic_usec_total;
1241 uint64_t wake_abs;
1242 size_t size;
1243
1244 /*
1245 * If the platform has the monotonic clock use that to
1246 * compute the sleep time. The monotonic clock does not have an offset
1247 * that can be modified, so nor kernel or userspace can change the time
1248 * of this clock, it can only monotonically increase over time.
1249 * During sleep mach_absolute_time (sys time) does not tick,
1250 * so the sleep time is the difference between the current monotonic time
1251 * less the absolute time and the previous difference stored at wake time.
1252 *
1253 * basesleep = (monotonic - sys) ---> computed at last wake
1254 * sleep_time = (monotonic - sys) - basesleep
1255 *
1256 * If the platform does not support monotonic clock we set the wall time to what the
1257 * UTC clock returns us.
1258 * Setting the wall time to UTC time implies that we loose all the adjustments
1259 * done during wake time through adjtime/ntp_adjustime.
1260 * The UTC time is the monotonic clock + an offset that can be set
1261 * by kernel.
1262 * The time slept in this case is the difference between wall time and UTC
1263 * at wake.
1264 *
1265 * IMPORTANT:
1266 * We assume that only the kernel is setting the offset of the PMU/RTC and that
1267 * it is doing it only througth the settimeofday interface.
1268 */
1269 if (has_monotonic_clock) {
1270 #if DEVELOPMENT || DEBUG
1271 /*
1272 * Just for debugging, get the wake UTC time.
1273 */
1274 PEGetUTCTimeOfDay(&var_s, &var_us);
1275 #endif
1276 /*
1277 * Get monotonic time with corresponding sys time
1278 */
1279 size = sizeof(monotonic_time);
1280 if (kernel_sysctlbyname("kern.monotonicclock_usecs", &monotonic_time, &size, NULL, 0) != 0) {
1281 panic("%s: could not call kern.monotonicclock_usecs", __func__);
1282 }
1283 wake_abs = monotonic_time.mach_time;
1284 absolutetime_to_microtime(wake_abs, &wake_sys_sec, &wake_sys_usec);
1285
1286 monotonic_usec_total = monotonic_time.monotonic_time_usec;
1287 wake_sec = monotonic_usec_total / (clock_sec_t)USEC_PER_SEC;
1288 wake_usec = monotonic_usec_total % (clock_usec_t)USEC_PER_SEC;
1289 } else {
1290 /*
1291 * Get UTC time and corresponding sys time
1292 */
1293 PEGetUTCTimeOfDay(&wake_sec, &wake_usec);
1294 wake_abs = mach_absolute_time();
1295 absolutetime_to_microtime(wake_abs, &wake_sys_sec, &wake_sys_usec);
1296 }
1297
1298 #if DEVELOPMENT || DEBUG
1299 os_log(OS_LOG_DEFAULT, "time at wake %lu s %d u from %s clock, abs %llu\n", (unsigned long)wake_sec, wake_usec, (has_monotonic_clock)?"monotonic":"UTC", wake_abs);
1300 if (has_monotonic_clock) {
1301 OS_ANALYZER_SUPPRESS("82347749") os_log(OS_LOG_DEFAULT, "UTC time %lu s %d u\n", (unsigned long)var_s, var_us);
1302 }
1303 #endif /* DEVELOPMENT || DEBUG */
1304
1305 s = splclock();
1306 clock_lock();
1307
1308 commpage_disable_timestamp();
1309
1310 #if DEVELOPMENT || DEBUG
1311 struct clock_calend clock_calend_cp1 = clock_calend;
1312 #endif /* DEVELOPMENT || DEBUG */
1313
1314 /*
1315 * We normally expect the UTC/monotonic clock to be always-on and produce
1316 * greater readings than the sys counter. There may be corner cases
1317 * due to differing clock resolutions (UTC/monotonic clock is likely lower) and
1318 * and errors reading the UTC/monotonic clock (some implementations return 0
1319 * on error) in which that doesn't hold true.
1320 */
1321 if ((wake_sys_sec > wake_sec) || ((wake_sys_sec == wake_sec) && (wake_sys_usec > wake_usec))) {
1322 os_log_error(OS_LOG_DEFAULT, "WARNING: %s clock is less then sys clock at wake: %lu s %d u vs %lu s %d u, defaulting sleep time to zero\n", (has_monotonic_clock)?"monotonic":"UTC", (unsigned long)wake_sec, wake_usec, (unsigned long)wake_sys_sec, wake_sys_usec);
1323 mach_absolutetime_last_sleep = 0;
1324 goto done;
1325 }
1326
1327 if (has_monotonic_clock) {
1328 /*
1329 * computer the difference monotonic - sys
1330 * we already checked that monotonic time is
1331 * greater than sys.
1332 */
1333 diff_sec = wake_sec;
1334 diff_usec = wake_usec;
1335 // This macro stores the subtraction result in diff_sec and diff_usec
1336 TIME_SUB(diff_sec, wake_sys_sec, diff_usec, wake_sys_usec, USEC_PER_SEC);
1337 //This function converts diff_sec and diff_usec in bintime
1338 clock2bintime(&diff_sec, &diff_usec, &bt);
1339
1340 /*
1341 * Safety belt: the monotonic clock will likely have a lower resolution than the sys counter.
1342 * It's also possible that the device didn't fully transition to the powered-off state on
1343 * the most recent sleep, so the sys counter may not have reset or may have only briefly
1344 * turned off. In that case it's possible for the difference between the monotonic clock and the
1345 * sys counter to be less than the previously recorded value in clock.calend.basesleep.
1346 * In that case simply record that we slept for 0 ticks.
1347 */
1348 if ((bt.sec > clock_calend.basesleep.sec) ||
1349 ((bt.sec == clock_calend.basesleep.sec) && (bt.frac > clock_calend.basesleep.frac))) {
1350 //last_sleep is the difference between (current monotonic - abs) and (last wake monotonic - abs)
1351 last_sleep_bt = bt;
1352 bintime_sub(&last_sleep_bt, &clock_calend.basesleep);
1353
1354 bintime2absolutetime(&last_sleep_bt, &mach_absolutetime_last_sleep);
1355 mach_absolutetime_asleep += mach_absolutetime_last_sleep;
1356
1357 //set basesleep to current monotonic - abs
1358 clock_calend.basesleep = bt;
1359
1360 //update wall time
1361 bintime_add(&clock_calend.offset, &last_sleep_bt);
1362 bintime_add(&clock_calend.bintime, &last_sleep_bt);
1363
1364 bintime2usclock(&last_sleep_bt, &var_s, &var_us);
1365 os_log(OS_LOG_DEFAULT, "time_slept (%lu s %d u)\n", (unsigned long) var_s, var_us);
1366 } else {
1367 bintime2usclock(&clock_calend.basesleep, &var_s, &var_us);
1368 os_log_error(OS_LOG_DEFAULT, "WARNING: last wake monotonic-sys time (%lu s %d u) is greater then current monotonic-sys time(%lu s %d u), defaulting sleep time to zero\n", (unsigned long) var_s, var_us, (unsigned long) diff_sec, diff_usec);
1369
1370 mach_absolutetime_last_sleep = 0;
1371 }
1372 } else {
1373 /*
1374 * set the wall time to UTC value
1375 */
1376 bt = get_scaled_time(wake_abs);
1377 bintime_add(&bt, &clock_calend.bintime);
1378 bintime2usclock(&bt, &wall_time_sec, &wall_time_usec);
1379
1380 if (wall_time_sec > wake_sec || (wall_time_sec == wake_sec && wall_time_usec > wake_usec)) {
1381 os_log(OS_LOG_DEFAULT, "WARNING: wall time (%lu s %d u) is greater than current UTC time (%lu s %d u), defaulting sleep time to zero\n", (unsigned long) wall_time_sec, wall_time_usec, (unsigned long) wake_sec, wake_usec);
1382
1383 mach_absolutetime_last_sleep = 0;
1384 } else {
1385 diff_sec = wake_sec;
1386 diff_usec = wake_usec;
1387 // This macro stores the subtraction result in diff_sec and diff_usec
1388 TIME_SUB(diff_sec, wall_time_sec, diff_usec, wall_time_usec, USEC_PER_SEC);
1389 //This function converts diff_sec and diff_usec in bintime
1390 clock2bintime(&diff_sec, &diff_usec, &bt);
1391
1392 //time slept in this case is the difference between PMU/RTC and wall time
1393 last_sleep_bt = bt;
1394
1395 bintime2absolutetime(&last_sleep_bt, &mach_absolutetime_last_sleep);
1396 mach_absolutetime_asleep += mach_absolutetime_last_sleep;
1397
1398 //update wall time
1399 bintime_add(&clock_calend.offset, &last_sleep_bt);
1400 bintime_add(&clock_calend.bintime, &last_sleep_bt);
1401
1402 bintime2usclock(&last_sleep_bt, &var_s, &var_us);
1403 os_log(OS_LOG_DEFAULT, "time_slept (%lu s %d u)\n", (unsigned long)var_s, var_us);
1404 }
1405 }
1406 done:
1407 KDBG_RELEASE(MACHDBG_CODE(DBG_MACH_CLOCK, MACH_EPOCH_CHANGE),
1408 (uintptr_t)mach_absolutetime_last_sleep,
1409 (uintptr_t)mach_absolutetime_asleep,
1410 (uintptr_t)(mach_absolutetime_last_sleep >> 32),
1411 (uintptr_t)(mach_absolutetime_asleep >> 32));
1412
1413 commpage_update_mach_continuous_time(mach_absolutetime_asleep);
1414 adjust_cont_time_thread_calls();
1415
1416 #if DEVELOPMENT || DEBUG
1417 struct clock_calend clock_calend_cp = clock_calend;
1418 #endif
1419
1420 clock_unlock();
1421 splx(s);
1422
1423 #if DEVELOPMENT || DEBUG
1424 if (g_should_log_clock_adjustments) {
1425 print_all_clock_variables("clock_wakeup_calendar: BEFORE", NULL, NULL, NULL, NULL, &clock_calend_cp1);
1426 print_all_clock_variables("clock_wakeup_calendar: AFTER", NULL, NULL, NULL, NULL, &clock_calend_cp);
1427 }
1428 #endif /* DEVELOPMENT || DEBUG */
1429
1430 host_notify_calendar_change();
1431
1432 #if CONFIG_DTRACE
1433 clock_track_calend_nowait();
1434 #endif
1435 }
1436
1437 #endif /* ENABLE_LEGACY_CLOCK_CODE */
1438
1439 void
clock_wakeup_calendar(void)1440 clock_wakeup_calendar(void)
1441 {
1442 #if HAS_CONTINUOUS_HWCLOCK
1443 #if HIBERNATION_USES_LEGACY_CLOCK
1444 if (gIOHibernateState) {
1445 // if we're resuming from hibernation, we have to take the legacy wakeup path
1446 return clock_wakeup_calendar_legacy();
1447 }
1448 #endif /* HIBERNATION_USES_LEGACY_CLOCK */
1449 // use the hwclock wakeup path
1450 return clock_wakeup_calendar_hwclock();
1451 #elif ENABLE_LEGACY_CLOCK_CODE
1452 return clock_wakeup_calendar_legacy();
1453 #else
1454 #error "can't determine which clock code to run"
1455 #endif
1456 }
1457
1458 /*
1459 * clock_get_boottime_nanotime:
1460 *
1461 * Return the boottime, used by sysctl.
1462 */
1463 void
clock_get_boottime_nanotime(clock_sec_t * secs,clock_nsec_t * nanosecs)1464 clock_get_boottime_nanotime(
1465 clock_sec_t *secs,
1466 clock_nsec_t *nanosecs)
1467 {
1468 spl_t s;
1469
1470 s = splclock();
1471 clock_lock();
1472
1473 *secs = (clock_sec_t)clock_boottime;
1474 *nanosecs = (clock_nsec_t)clock_boottime_usec * NSEC_PER_USEC;
1475
1476 clock_unlock();
1477 splx(s);
1478 }
1479
1480 /*
1481 * clock_get_boottime_nanotime:
1482 *
1483 * Return the boottime, used by sysctl.
1484 */
1485 void
clock_get_boottime_microtime(clock_sec_t * secs,clock_usec_t * microsecs)1486 clock_get_boottime_microtime(
1487 clock_sec_t *secs,
1488 clock_usec_t *microsecs)
1489 {
1490 spl_t s;
1491
1492 s = splclock();
1493 clock_lock();
1494
1495 *secs = (clock_sec_t)clock_boottime;
1496 *microsecs = (clock_nsec_t)clock_boottime_usec;
1497
1498 clock_unlock();
1499 splx(s);
1500 }
1501
1502
1503 /*
1504 * Wait / delay routines.
1505 */
1506 static void
mach_wait_until_continue(__unused void * parameter,wait_result_t wresult)1507 mach_wait_until_continue(
1508 __unused void *parameter,
1509 wait_result_t wresult)
1510 {
1511 thread_syscall_return((wresult == THREAD_INTERRUPTED)? KERN_ABORTED: KERN_SUCCESS);
1512 /*NOTREACHED*/
1513 }
1514
1515 /*
1516 * mach_wait_until_trap: Suspend execution of calling thread until the specified time has passed
1517 *
1518 * Parameters: args->deadline Amount of time to wait
1519 *
1520 * Returns: 0 Success
1521 * !0 Not success
1522 *
1523 */
1524 kern_return_t
mach_wait_until_trap(struct mach_wait_until_trap_args * args)1525 mach_wait_until_trap(
1526 struct mach_wait_until_trap_args *args)
1527 {
1528 uint64_t deadline = args->deadline;
1529 wait_result_t wresult;
1530
1531
1532 wresult = assert_wait_deadline_with_leeway((event_t)mach_wait_until_trap, THREAD_ABORTSAFE,
1533 TIMEOUT_URGENCY_USER_NORMAL, deadline, 0);
1534 if (wresult == THREAD_WAITING) {
1535 wresult = thread_block(mach_wait_until_continue);
1536 }
1537
1538 return (wresult == THREAD_INTERRUPTED)? KERN_ABORTED: KERN_SUCCESS;
1539 }
1540
1541 void
clock_delay_until(uint64_t deadline)1542 clock_delay_until(
1543 uint64_t deadline)
1544 {
1545 uint64_t now = mach_absolute_time();
1546
1547 if (now >= deadline) {
1548 return;
1549 }
1550
1551 _clock_delay_until_deadline(deadline - now, deadline);
1552 }
1553
1554 /*
1555 * Preserve the original precise interval that the client
1556 * requested for comparison to the spin threshold.
1557 */
1558 void
_clock_delay_until_deadline(uint64_t interval,uint64_t deadline)1559 _clock_delay_until_deadline(
1560 uint64_t interval,
1561 uint64_t deadline)
1562 {
1563 _clock_delay_until_deadline_with_leeway(interval, deadline, 0);
1564 }
1565
1566 /*
1567 * Like _clock_delay_until_deadline, but it accepts a
1568 * leeway value.
1569 */
1570 void
_clock_delay_until_deadline_with_leeway(uint64_t interval,uint64_t deadline,uint64_t leeway)1571 _clock_delay_until_deadline_with_leeway(
1572 uint64_t interval,
1573 uint64_t deadline,
1574 uint64_t leeway)
1575 {
1576 if (interval == 0) {
1577 return;
1578 }
1579
1580 if (ml_delay_should_spin(interval) ||
1581 get_preemption_level() != 0 ||
1582 ml_get_interrupts_enabled() == FALSE) {
1583 machine_delay_until(interval, deadline);
1584 } else {
1585 /*
1586 * For now, assume a leeway request of 0 means the client does not want a leeway
1587 * value. We may want to change this interpretation in the future.
1588 */
1589
1590 if (leeway) {
1591 assert_wait_deadline_with_leeway((event_t)clock_delay_until, THREAD_UNINT, TIMEOUT_URGENCY_LEEWAY, deadline, leeway);
1592 } else {
1593 assert_wait_deadline((event_t)clock_delay_until, THREAD_UNINT, deadline);
1594 }
1595
1596 thread_block(THREAD_CONTINUE_NULL);
1597 }
1598 }
1599
1600 void
delay_for_interval(uint32_t interval,uint32_t scale_factor)1601 delay_for_interval(
1602 uint32_t interval,
1603 uint32_t scale_factor)
1604 {
1605 uint64_t abstime;
1606
1607 clock_interval_to_absolutetime_interval(interval, scale_factor, &abstime);
1608
1609 _clock_delay_until_deadline(abstime, mach_absolute_time() + abstime);
1610 }
1611
1612 void
delay_for_interval_with_leeway(uint32_t interval,uint32_t leeway,uint32_t scale_factor)1613 delay_for_interval_with_leeway(
1614 uint32_t interval,
1615 uint32_t leeway,
1616 uint32_t scale_factor)
1617 {
1618 uint64_t abstime_interval;
1619 uint64_t abstime_leeway;
1620
1621 clock_interval_to_absolutetime_interval(interval, scale_factor, &abstime_interval);
1622 clock_interval_to_absolutetime_interval(leeway, scale_factor, &abstime_leeway);
1623
1624 _clock_delay_until_deadline_with_leeway(abstime_interval, mach_absolute_time() + abstime_interval, abstime_leeway);
1625 }
1626
1627 void
delay(int usec)1628 delay(
1629 int usec)
1630 {
1631 delay_for_interval((usec < 0)? -usec: usec, NSEC_PER_USEC);
1632 }
1633
1634 /*
1635 * Miscellaneous routines.
1636 */
1637 void
clock_interval_to_deadline(uint32_t interval,uint32_t scale_factor,uint64_t * result)1638 clock_interval_to_deadline(
1639 uint32_t interval,
1640 uint32_t scale_factor,
1641 uint64_t *result)
1642 {
1643 uint64_t abstime;
1644
1645 clock_interval_to_absolutetime_interval(interval, scale_factor, &abstime);
1646
1647 if (os_add_overflow(mach_absolute_time(), abstime, result)) {
1648 *result = UINT64_MAX;
1649 }
1650 }
1651
1652 void
nanoseconds_to_deadline(uint64_t interval,uint64_t * result)1653 nanoseconds_to_deadline(
1654 uint64_t interval,
1655 uint64_t *result)
1656 {
1657 uint64_t abstime;
1658
1659 nanoseconds_to_absolutetime(interval, &abstime);
1660
1661 if (os_add_overflow(mach_absolute_time(), abstime, result)) {
1662 *result = UINT64_MAX;
1663 }
1664 }
1665
1666 void
clock_absolutetime_interval_to_deadline(uint64_t abstime,uint64_t * result)1667 clock_absolutetime_interval_to_deadline(
1668 uint64_t abstime,
1669 uint64_t *result)
1670 {
1671 if (os_add_overflow(mach_absolute_time(), abstime, result)) {
1672 *result = UINT64_MAX;
1673 }
1674 }
1675
1676 void
clock_continuoustime_interval_to_deadline(uint64_t conttime,uint64_t * result)1677 clock_continuoustime_interval_to_deadline(
1678 uint64_t conttime,
1679 uint64_t *result)
1680 {
1681 if (os_add_overflow(mach_continuous_time(), conttime, result)) {
1682 *result = UINT64_MAX;
1683 }
1684 }
1685
1686 void
clock_get_uptime(uint64_t * result)1687 clock_get_uptime(
1688 uint64_t *result)
1689 {
1690 *result = mach_absolute_time();
1691 }
1692
1693 void
clock_deadline_for_periodic_event(uint64_t interval,uint64_t abstime,uint64_t * deadline)1694 clock_deadline_for_periodic_event(
1695 uint64_t interval,
1696 uint64_t abstime,
1697 uint64_t *deadline)
1698 {
1699 assert(interval != 0);
1700
1701 // *deadline += interval;
1702 if (os_add_overflow(*deadline, interval, deadline)) {
1703 *deadline = UINT64_MAX;
1704 }
1705
1706 if (*deadline <= abstime) {
1707 // *deadline = abstime + interval;
1708 if (os_add_overflow(abstime, interval, deadline)) {
1709 *deadline = UINT64_MAX;
1710 }
1711
1712 abstime = mach_absolute_time();
1713 if (*deadline <= abstime) {
1714 // *deadline = abstime + interval;
1715 if (os_add_overflow(abstime, interval, deadline)) {
1716 *deadline = UINT64_MAX;
1717 }
1718 }
1719 }
1720 }
1721
1722 uint64_t
mach_continuous_time(void)1723 mach_continuous_time(void)
1724 {
1725 #if HIBERNATION && HAS_CONTINUOUS_HWCLOCK
1726 return ml_get_hwclock() + hwclock_conttime_offset;
1727 #elif HAS_CONTINUOUS_HWCLOCK
1728 return ml_get_hwclock();
1729 #else
1730 while (1) {
1731 uint64_t read1 = mach_absolutetime_asleep;
1732 uint64_t absolute = mach_absolute_time();
1733 OSMemoryBarrier();
1734 uint64_t read2 = mach_absolutetime_asleep;
1735
1736 if (__builtin_expect(read1 == read2, 1)) {
1737 return absolute + read1;
1738 }
1739 }
1740 #endif
1741 }
1742
1743 uint64_t
mach_continuous_approximate_time(void)1744 mach_continuous_approximate_time(void)
1745 {
1746 #if HAS_CONTINUOUS_HWCLOCK
1747 return mach_continuous_time();
1748 #else
1749 while (1) {
1750 uint64_t read1 = mach_absolutetime_asleep;
1751 uint64_t absolute = mach_approximate_time();
1752 OSMemoryBarrier();
1753 uint64_t read2 = mach_absolutetime_asleep;
1754
1755 if (__builtin_expect(read1 == read2, 1)) {
1756 return absolute + read1;
1757 }
1758 }
1759 #endif
1760 }
1761
1762 /*
1763 * continuoustime_to_absolutetime
1764 * Must be called with interrupts disabled
1765 * Returned value is only valid until the next update to
1766 * mach_continuous_time
1767 */
1768 uint64_t
continuoustime_to_absolutetime(uint64_t conttime)1769 continuoustime_to_absolutetime(uint64_t conttime)
1770 {
1771 if (conttime <= mach_absolutetime_asleep) {
1772 return 0;
1773 } else {
1774 return conttime - mach_absolutetime_asleep;
1775 }
1776 }
1777
1778 /*
1779 * absolutetime_to_continuoustime
1780 * Must be called with interrupts disabled
1781 * Returned value is only valid until the next update to
1782 * mach_continuous_time
1783 */
1784 uint64_t
absolutetime_to_continuoustime(uint64_t abstime)1785 absolutetime_to_continuoustime(uint64_t abstime)
1786 {
1787 return abstime + mach_absolutetime_asleep;
1788 }
1789
1790 #if CONFIG_DTRACE
1791
1792 /*
1793 * clock_get_calendar_nanotime_nowait
1794 *
1795 * Description: Non-blocking version of clock_get_calendar_nanotime()
1796 *
1797 * Notes: This function operates by separately tracking calendar time
1798 * updates using a two element structure to copy the calendar
1799 * state, which may be asynchronously modified. It utilizes
1800 * barrier instructions in the tracking process and in the local
1801 * stable snapshot process in order to ensure that a consistent
1802 * snapshot is used to perform the calculation.
1803 */
1804 void
clock_get_calendar_nanotime_nowait(clock_sec_t * secs,clock_nsec_t * nanosecs)1805 clock_get_calendar_nanotime_nowait(
1806 clock_sec_t *secs,
1807 clock_nsec_t *nanosecs)
1808 {
1809 int i = 0;
1810 uint64_t now;
1811 struct unlocked_clock_calend stable;
1812 struct bintime bt;
1813
1814 for (;;) {
1815 stable = flipflop[i]; /* take snapshot */
1816
1817 /*
1818 * Use a barrier instructions to ensure atomicity. We AND
1819 * off the "in progress" bit to get the current generation
1820 * count.
1821 */
1822 os_atomic_andnot(&stable.gen, 1, relaxed);
1823
1824 /*
1825 * If an update _is_ in progress, the generation count will be
1826 * off by one, if it _was_ in progress, it will be off by two,
1827 * and if we caught it at a good time, it will be equal (and
1828 * our snapshot is threfore stable).
1829 */
1830 if (flipflop[i].gen == stable.gen) {
1831 break;
1832 }
1833
1834 /* Switch to the other element of the flipflop, and try again. */
1835 i ^= 1;
1836 }
1837
1838 now = mach_absolute_time();
1839
1840 bt = get_scaled_time(now);
1841
1842 bintime_add(&bt, &clock_calend.bintime);
1843
1844 bintime2nsclock(&bt, secs, nanosecs);
1845 }
1846
1847 static void
clock_track_calend_nowait(void)1848 clock_track_calend_nowait(void)
1849 {
1850 int i;
1851
1852 for (i = 0; i < 2; i++) {
1853 struct clock_calend tmp = clock_calend;
1854
1855 /*
1856 * Set the low bit if the generation count; since we use a
1857 * barrier instruction to do this, we are guaranteed that this
1858 * will flag an update in progress to an async caller trying
1859 * to examine the contents.
1860 */
1861 os_atomic_or(&flipflop[i].gen, 1, relaxed);
1862
1863 flipflop[i].calend = tmp;
1864
1865 /*
1866 * Increment the generation count to clear the low bit to
1867 * signal completion. If a caller compares the generation
1868 * count after taking a copy while in progress, the count
1869 * will be off by two.
1870 */
1871 os_atomic_inc(&flipflop[i].gen, relaxed);
1872 }
1873 }
1874
1875 #endif /* CONFIG_DTRACE */
1876