1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Kernel timekeeping code and accessor functions. Based on code from
4 * timer.c, moved in commit 8524070b7982.
5 */
6 #include <linux/timekeeper_internal.h>
7 #include <linux/module.h>
8 #include <linux/interrupt.h>
9 #include <linux/percpu.h>
10 #include <linux/init.h>
11 #include <linux/mm.h>
12 #include <linux/nmi.h>
13 #include <linux/sched.h>
14 #include <linux/sched/loadavg.h>
15 #include <linux/sched/clock.h>
16 #include <linux/syscore_ops.h>
17 #include <linux/clocksource.h>
18 #include <linux/jiffies.h>
19 #include <linux/time.h>
20 #include <linux/timex.h>
21 #include <linux/tick.h>
22 #include <linux/stop_machine.h>
23 #include <linux/pvclock_gtod.h>
24 #include <linux/compiler.h>
25 #include <linux/audit.h>
26 #include <linux/random.h>
27
28 #include "tick-internal.h"
29 #include "ntp_internal.h"
30 #include "timekeeping_internal.h"
31
32 #define TK_CLEAR_NTP (1 << 0)
33 #define TK_MIRROR (1 << 1)
34 #define TK_CLOCK_WAS_SET (1 << 2)
35
36 enum timekeeping_adv_mode {
37 /* Update timekeeper when a tick has passed */
38 TK_ADV_TICK,
39
40 /* Update timekeeper on a direct frequency change */
41 TK_ADV_FREQ
42 };
43
44 DEFINE_RAW_SPINLOCK(timekeeper_lock);
45
46 /*
47 * The most important data for readout fits into a single 64 byte
48 * cache line.
49 */
50 static struct {
51 seqcount_raw_spinlock_t seq;
52 struct timekeeper timekeeper;
53 } tk_core ____cacheline_aligned = {
54 .seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_core.seq, &timekeeper_lock),
55 };
56
57 static struct timekeeper shadow_timekeeper;
58
59 /* flag for if timekeeping is suspended */
60 int __read_mostly timekeeping_suspended;
61
62 /**
63 * struct tk_fast - NMI safe timekeeper
64 * @seq: Sequence counter for protecting updates. The lowest bit
65 * is the index for the tk_read_base array
66 * @base: tk_read_base array. Access is indexed by the lowest bit of
67 * @seq.
68 *
69 * See @update_fast_timekeeper() below.
70 */
71 struct tk_fast {
72 seqcount_latch_t seq;
73 struct tk_read_base base[2];
74 };
75
76 /* Suspend-time cycles value for halted fast timekeeper. */
77 static u64 cycles_at_suspend;
78
dummy_clock_read(struct clocksource * cs)79 static u64 dummy_clock_read(struct clocksource *cs)
80 {
81 if (timekeeping_suspended)
82 return cycles_at_suspend;
83 return local_clock();
84 }
85
86 static struct clocksource dummy_clock = {
87 .read = dummy_clock_read,
88 };
89
90 /*
91 * Boot time initialization which allows local_clock() to be utilized
92 * during early boot when clocksources are not available. local_clock()
93 * returns nanoseconds already so no conversion is required, hence mult=1
94 * and shift=0. When the first proper clocksource is installed then
95 * the fast time keepers are updated with the correct values.
96 */
97 #define FAST_TK_INIT \
98 { \
99 .clock = &dummy_clock, \
100 .mask = CLOCKSOURCE_MASK(64), \
101 .mult = 1, \
102 .shift = 0, \
103 }
104
105 static struct tk_fast tk_fast_mono ____cacheline_aligned = {
106 .seq = SEQCNT_LATCH_ZERO(tk_fast_mono.seq),
107 .base[0] = FAST_TK_INIT,
108 .base[1] = FAST_TK_INIT,
109 };
110
111 static struct tk_fast tk_fast_raw ____cacheline_aligned = {
112 .seq = SEQCNT_LATCH_ZERO(tk_fast_raw.seq),
113 .base[0] = FAST_TK_INIT,
114 .base[1] = FAST_TK_INIT,
115 };
116
tk_normalize_xtime(struct timekeeper * tk)117 static inline void tk_normalize_xtime(struct timekeeper *tk)
118 {
119 while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
120 tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
121 tk->xtime_sec++;
122 }
123 while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) {
124 tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
125 tk->raw_sec++;
126 }
127 }
128
tk_xtime(const struct timekeeper * tk)129 static inline struct timespec64 tk_xtime(const struct timekeeper *tk)
130 {
131 struct timespec64 ts;
132
133 ts.tv_sec = tk->xtime_sec;
134 ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
135 return ts;
136 }
137
tk_set_xtime(struct timekeeper * tk,const struct timespec64 * ts)138 static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
139 {
140 tk->xtime_sec = ts->tv_sec;
141 tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
142 }
143
tk_xtime_add(struct timekeeper * tk,const struct timespec64 * ts)144 static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts)
145 {
146 tk->xtime_sec += ts->tv_sec;
147 tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift;
148 tk_normalize_xtime(tk);
149 }
150
tk_set_wall_to_mono(struct timekeeper * tk,struct timespec64 wtm)151 static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
152 {
153 struct timespec64 tmp;
154
155 /*
156 * Verify consistency of: offset_real = -wall_to_monotonic
157 * before modifying anything
158 */
159 set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
160 -tk->wall_to_monotonic.tv_nsec);
161 WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp));
162 tk->wall_to_monotonic = wtm;
163 set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
164 tk->offs_real = timespec64_to_ktime(tmp);
165 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
166 }
167
tk_update_sleep_time(struct timekeeper * tk,ktime_t delta)168 static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
169 {
170 tk->offs_boot = ktime_add(tk->offs_boot, delta);
171 /*
172 * Timespec representation for VDSO update to avoid 64bit division
173 * on every update.
174 */
175 tk->monotonic_to_boot = ktime_to_timespec64(tk->offs_boot);
176 }
177
178 /*
179 * tk_clock_read - atomic clocksource read() helper
180 *
181 * This helper is necessary to use in the read paths because, while the
182 * seqcount ensures we don't return a bad value while structures are updated,
183 * it doesn't protect from potential crashes. There is the possibility that
184 * the tkr's clocksource may change between the read reference, and the
185 * clock reference passed to the read function. This can cause crashes if
186 * the wrong clocksource is passed to the wrong read function.
187 * This isn't necessary to use when holding the timekeeper_lock or doing
188 * a read of the fast-timekeeper tkrs (which is protected by its own locking
189 * and update logic).
190 */
tk_clock_read(const struct tk_read_base * tkr)191 static inline u64 tk_clock_read(const struct tk_read_base *tkr)
192 {
193 struct clocksource *clock = READ_ONCE(tkr->clock);
194
195 return clock->read(clock);
196 }
197
198 #ifdef CONFIG_DEBUG_TIMEKEEPING
199 #define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
200
timekeeping_check_update(struct timekeeper * tk,u64 offset)201 static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
202 {
203
204 u64 max_cycles = tk->tkr_mono.clock->max_cycles;
205 const char *name = tk->tkr_mono.clock->name;
206
207 if (offset > max_cycles) {
208 printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
209 offset, name, max_cycles);
210 printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
211 } else {
212 if (offset > (max_cycles >> 1)) {
213 printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
214 offset, name, max_cycles >> 1);
215 printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
216 }
217 }
218
219 if (tk->underflow_seen) {
220 if (jiffies - tk->last_warning > WARNING_FREQ) {
221 printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
222 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
223 printk_deferred(" Your kernel is probably still fine.\n");
224 tk->last_warning = jiffies;
225 }
226 tk->underflow_seen = 0;
227 }
228
229 if (tk->overflow_seen) {
230 if (jiffies - tk->last_warning > WARNING_FREQ) {
231 printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
232 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
233 printk_deferred(" Your kernel is probably still fine.\n");
234 tk->last_warning = jiffies;
235 }
236 tk->overflow_seen = 0;
237 }
238 }
239
240 static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles);
241
timekeeping_debug_get_ns(const struct tk_read_base * tkr)242 static inline u64 timekeeping_debug_get_ns(const struct tk_read_base *tkr)
243 {
244 struct timekeeper *tk = &tk_core.timekeeper;
245 u64 now, last, mask, max, delta;
246 unsigned int seq;
247
248 /*
249 * Since we're called holding a seqcount, the data may shift
250 * under us while we're doing the calculation. This can cause
251 * false positives, since we'd note a problem but throw the
252 * results away. So nest another seqcount here to atomically
253 * grab the points we are checking with.
254 */
255 do {
256 seq = read_seqcount_begin(&tk_core.seq);
257 now = tk_clock_read(tkr);
258 last = tkr->cycle_last;
259 mask = tkr->mask;
260 max = tkr->clock->max_cycles;
261 } while (read_seqcount_retry(&tk_core.seq, seq));
262
263 delta = clocksource_delta(now, last, mask);
264
265 /*
266 * Try to catch underflows by checking if we are seeing small
267 * mask-relative negative values.
268 */
269 if (unlikely((~delta & mask) < (mask >> 3)))
270 tk->underflow_seen = 1;
271
272 /* Check for multiplication overflows */
273 if (unlikely(delta > max))
274 tk->overflow_seen = 1;
275
276 /* timekeeping_cycles_to_ns() handles both under and overflow */
277 return timekeeping_cycles_to_ns(tkr, now);
278 }
279 #else
timekeeping_check_update(struct timekeeper * tk,u64 offset)280 static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
281 {
282 }
timekeeping_debug_get_ns(const struct tk_read_base * tkr)283 static inline u64 timekeeping_debug_get_ns(const struct tk_read_base *tkr)
284 {
285 BUG();
286 }
287 #endif
288
289 /**
290 * tk_setup_internals - Set up internals to use clocksource clock.
291 *
292 * @tk: The target timekeeper to setup.
293 * @clock: Pointer to clocksource.
294 *
295 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
296 * pair and interval request.
297 *
298 * Unless you're the timekeeping code, you should not be using this!
299 */
tk_setup_internals(struct timekeeper * tk,struct clocksource * clock)300 static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
301 {
302 u64 interval;
303 u64 tmp, ntpinterval;
304 struct clocksource *old_clock;
305
306 ++tk->cs_was_changed_seq;
307 old_clock = tk->tkr_mono.clock;
308 tk->tkr_mono.clock = clock;
309 tk->tkr_mono.mask = clock->mask;
310 tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono);
311
312 tk->tkr_raw.clock = clock;
313 tk->tkr_raw.mask = clock->mask;
314 tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
315
316 /* Do the ns -> cycle conversion first, using original mult */
317 tmp = NTP_INTERVAL_LENGTH;
318 tmp <<= clock->shift;
319 ntpinterval = tmp;
320 tmp += clock->mult/2;
321 do_div(tmp, clock->mult);
322 if (tmp == 0)
323 tmp = 1;
324
325 interval = (u64) tmp;
326 tk->cycle_interval = interval;
327
328 /* Go back from cycles -> shifted ns */
329 tk->xtime_interval = interval * clock->mult;
330 tk->xtime_remainder = ntpinterval - tk->xtime_interval;
331 tk->raw_interval = interval * clock->mult;
332
333 /* if changing clocks, convert xtime_nsec shift units */
334 if (old_clock) {
335 int shift_change = clock->shift - old_clock->shift;
336 if (shift_change < 0) {
337 tk->tkr_mono.xtime_nsec >>= -shift_change;
338 tk->tkr_raw.xtime_nsec >>= -shift_change;
339 } else {
340 tk->tkr_mono.xtime_nsec <<= shift_change;
341 tk->tkr_raw.xtime_nsec <<= shift_change;
342 }
343 }
344
345 tk->tkr_mono.shift = clock->shift;
346 tk->tkr_raw.shift = clock->shift;
347
348 tk->ntp_error = 0;
349 tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
350 tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
351
352 /*
353 * The timekeeper keeps its own mult values for the currently
354 * active clocksource. These value will be adjusted via NTP
355 * to counteract clock drifting.
356 */
357 tk->tkr_mono.mult = clock->mult;
358 tk->tkr_raw.mult = clock->mult;
359 tk->ntp_err_mult = 0;
360 tk->skip_second_overflow = 0;
361 }
362
363 /* Timekeeper helper functions. */
delta_to_ns_safe(const struct tk_read_base * tkr,u64 delta)364 static noinline u64 delta_to_ns_safe(const struct tk_read_base *tkr, u64 delta)
365 {
366 return mul_u64_u32_add_u64_shr(delta, tkr->mult, tkr->xtime_nsec, tkr->shift);
367 }
368
timekeeping_cycles_to_ns(const struct tk_read_base * tkr,u64 cycles)369 static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles)
370 {
371 /* Calculate the delta since the last update_wall_time() */
372 u64 mask = tkr->mask, delta = (cycles - tkr->cycle_last) & mask;
373
374 /*
375 * This detects both negative motion and the case where the delta
376 * overflows the multiplication with tkr->mult.
377 */
378 if (unlikely(delta > tkr->clock->max_cycles)) {
379 /*
380 * Handle clocksource inconsistency between CPUs to prevent
381 * time from going backwards by checking for the MSB of the
382 * mask being set in the delta.
383 */
384 if (delta & ~(mask >> 1))
385 return tkr->xtime_nsec >> tkr->shift;
386
387 return delta_to_ns_safe(tkr, delta);
388 }
389
390 return ((delta * tkr->mult) + tkr->xtime_nsec) >> tkr->shift;
391 }
392
__timekeeping_get_ns(const struct tk_read_base * tkr)393 static __always_inline u64 __timekeeping_get_ns(const struct tk_read_base *tkr)
394 {
395 return timekeeping_cycles_to_ns(tkr, tk_clock_read(tkr));
396 }
397
timekeeping_get_ns(const struct tk_read_base * tkr)398 static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr)
399 {
400 if (IS_ENABLED(CONFIG_DEBUG_TIMEKEEPING))
401 return timekeeping_debug_get_ns(tkr);
402
403 return __timekeeping_get_ns(tkr);
404 }
405
406 /**
407 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
408 * @tkr: Timekeeping readout base from which we take the update
409 * @tkf: Pointer to NMI safe timekeeper
410 *
411 * We want to use this from any context including NMI and tracing /
412 * instrumenting the timekeeping code itself.
413 *
414 * Employ the latch technique; see @raw_write_seqcount_latch.
415 *
416 * So if a NMI hits the update of base[0] then it will use base[1]
417 * which is still consistent. In the worst case this can result is a
418 * slightly wrong timestamp (a few nanoseconds). See
419 * @ktime_get_mono_fast_ns.
420 */
update_fast_timekeeper(const struct tk_read_base * tkr,struct tk_fast * tkf)421 static void update_fast_timekeeper(const struct tk_read_base *tkr,
422 struct tk_fast *tkf)
423 {
424 struct tk_read_base *base = tkf->base;
425
426 /* Force readers off to base[1] */
427 raw_write_seqcount_latch(&tkf->seq);
428
429 /* Update base[0] */
430 memcpy(base, tkr, sizeof(*base));
431
432 /* Force readers back to base[0] */
433 raw_write_seqcount_latch(&tkf->seq);
434
435 /* Update base[1] */
436 memcpy(base + 1, base, sizeof(*base));
437 }
438
__ktime_get_fast_ns(struct tk_fast * tkf)439 static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
440 {
441 struct tk_read_base *tkr;
442 unsigned int seq;
443 u64 now;
444
445 do {
446 seq = raw_read_seqcount_latch(&tkf->seq);
447 tkr = tkf->base + (seq & 0x01);
448 now = ktime_to_ns(tkr->base);
449 now += __timekeeping_get_ns(tkr);
450 } while (raw_read_seqcount_latch_retry(&tkf->seq, seq));
451
452 return now;
453 }
454
455 /**
456 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
457 *
458 * This timestamp is not guaranteed to be monotonic across an update.
459 * The timestamp is calculated by:
460 *
461 * now = base_mono + clock_delta * slope
462 *
463 * So if the update lowers the slope, readers who are forced to the
464 * not yet updated second array are still using the old steeper slope.
465 *
466 * tmono
467 * ^
468 * | o n
469 * | o n
470 * | u
471 * | o
472 * |o
473 * |12345678---> reader order
474 *
475 * o = old slope
476 * u = update
477 * n = new slope
478 *
479 * So reader 6 will observe time going backwards versus reader 5.
480 *
481 * While other CPUs are likely to be able to observe that, the only way
482 * for a CPU local observation is when an NMI hits in the middle of
483 * the update. Timestamps taken from that NMI context might be ahead
484 * of the following timestamps. Callers need to be aware of that and
485 * deal with it.
486 */
ktime_get_mono_fast_ns(void)487 u64 notrace ktime_get_mono_fast_ns(void)
488 {
489 return __ktime_get_fast_ns(&tk_fast_mono);
490 }
491 EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
492
493 /**
494 * ktime_get_raw_fast_ns - Fast NMI safe access to clock monotonic raw
495 *
496 * Contrary to ktime_get_mono_fast_ns() this is always correct because the
497 * conversion factor is not affected by NTP/PTP correction.
498 */
ktime_get_raw_fast_ns(void)499 u64 notrace ktime_get_raw_fast_ns(void)
500 {
501 return __ktime_get_fast_ns(&tk_fast_raw);
502 }
503 EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
504
505 /**
506 * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
507 *
508 * To keep it NMI safe since we're accessing from tracing, we're not using a
509 * separate timekeeper with updates to monotonic clock and boot offset
510 * protected with seqcounts. This has the following minor side effects:
511 *
512 * (1) Its possible that a timestamp be taken after the boot offset is updated
513 * but before the timekeeper is updated. If this happens, the new boot offset
514 * is added to the old timekeeping making the clock appear to update slightly
515 * earlier:
516 * CPU 0 CPU 1
517 * timekeeping_inject_sleeptime64()
518 * __timekeeping_inject_sleeptime(tk, delta);
519 * timestamp();
520 * timekeeping_update(tk, TK_CLEAR_NTP...);
521 *
522 * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
523 * partially updated. Since the tk->offs_boot update is a rare event, this
524 * should be a rare occurrence which postprocessing should be able to handle.
525 *
526 * The caveats vs. timestamp ordering as documented for ktime_get_mono_fast_ns()
527 * apply as well.
528 */
ktime_get_boot_fast_ns(void)529 u64 notrace ktime_get_boot_fast_ns(void)
530 {
531 struct timekeeper *tk = &tk_core.timekeeper;
532
533 return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_boot)));
534 }
535 EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
536
537 /**
538 * ktime_get_tai_fast_ns - NMI safe and fast access to tai clock.
539 *
540 * The same limitations as described for ktime_get_boot_fast_ns() apply. The
541 * mono time and the TAI offset are not read atomically which may yield wrong
542 * readouts. However, an update of the TAI offset is an rare event e.g., caused
543 * by settime or adjtimex with an offset. The user of this function has to deal
544 * with the possibility of wrong timestamps in post processing.
545 */
ktime_get_tai_fast_ns(void)546 u64 notrace ktime_get_tai_fast_ns(void)
547 {
548 struct timekeeper *tk = &tk_core.timekeeper;
549
550 return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_tai)));
551 }
552 EXPORT_SYMBOL_GPL(ktime_get_tai_fast_ns);
553
__ktime_get_real_fast(struct tk_fast * tkf,u64 * mono)554 static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono)
555 {
556 struct tk_read_base *tkr;
557 u64 basem, baser, delta;
558 unsigned int seq;
559
560 do {
561 seq = raw_read_seqcount_latch(&tkf->seq);
562 tkr = tkf->base + (seq & 0x01);
563 basem = ktime_to_ns(tkr->base);
564 baser = ktime_to_ns(tkr->base_real);
565 delta = __timekeeping_get_ns(tkr);
566 } while (raw_read_seqcount_latch_retry(&tkf->seq, seq));
567
568 if (mono)
569 *mono = basem + delta;
570 return baser + delta;
571 }
572
573 /**
574 * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime.
575 *
576 * See ktime_get_mono_fast_ns() for documentation of the time stamp ordering.
577 */
ktime_get_real_fast_ns(void)578 u64 ktime_get_real_fast_ns(void)
579 {
580 return __ktime_get_real_fast(&tk_fast_mono, NULL);
581 }
582 EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns);
583
584 /**
585 * ktime_get_fast_timestamps: - NMI safe timestamps
586 * @snapshot: Pointer to timestamp storage
587 *
588 * Stores clock monotonic, boottime and realtime timestamps.
589 *
590 * Boot time is a racy access on 32bit systems if the sleep time injection
591 * happens late during resume and not in timekeeping_resume(). That could
592 * be avoided by expanding struct tk_read_base with boot offset for 32bit
593 * and adding more overhead to the update. As this is a hard to observe
594 * once per resume event which can be filtered with reasonable effort using
595 * the accurate mono/real timestamps, it's probably not worth the trouble.
596 *
597 * Aside of that it might be possible on 32 and 64 bit to observe the
598 * following when the sleep time injection happens late:
599 *
600 * CPU 0 CPU 1
601 * timekeeping_resume()
602 * ktime_get_fast_timestamps()
603 * mono, real = __ktime_get_real_fast()
604 * inject_sleep_time()
605 * update boot offset
606 * boot = mono + bootoffset;
607 *
608 * That means that boot time already has the sleep time adjustment, but
609 * real time does not. On the next readout both are in sync again.
610 *
611 * Preventing this for 64bit is not really feasible without destroying the
612 * careful cache layout of the timekeeper because the sequence count and
613 * struct tk_read_base would then need two cache lines instead of one.
614 *
615 * Access to the time keeper clock source is disabled across the innermost
616 * steps of suspend/resume. The accessors still work, but the timestamps
617 * are frozen until time keeping is resumed which happens very early.
618 *
619 * For regular suspend/resume there is no observable difference vs. sched
620 * clock, but it might affect some of the nasty low level debug printks.
621 *
622 * OTOH, access to sched clock is not guaranteed across suspend/resume on
623 * all systems either so it depends on the hardware in use.
624 *
625 * If that turns out to be a real problem then this could be mitigated by
626 * using sched clock in a similar way as during early boot. But it's not as
627 * trivial as on early boot because it needs some careful protection
628 * against the clock monotonic timestamp jumping backwards on resume.
629 */
ktime_get_fast_timestamps(struct ktime_timestamps * snapshot)630 void ktime_get_fast_timestamps(struct ktime_timestamps *snapshot)
631 {
632 struct timekeeper *tk = &tk_core.timekeeper;
633
634 snapshot->real = __ktime_get_real_fast(&tk_fast_mono, &snapshot->mono);
635 snapshot->boot = snapshot->mono + ktime_to_ns(data_race(tk->offs_boot));
636 }
637
638 /**
639 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
640 * @tk: Timekeeper to snapshot.
641 *
642 * It generally is unsafe to access the clocksource after timekeeping has been
643 * suspended, so take a snapshot of the readout base of @tk and use it as the
644 * fast timekeeper's readout base while suspended. It will return the same
645 * number of cycles every time until timekeeping is resumed at which time the
646 * proper readout base for the fast timekeeper will be restored automatically.
647 */
halt_fast_timekeeper(const struct timekeeper * tk)648 static void halt_fast_timekeeper(const struct timekeeper *tk)
649 {
650 static struct tk_read_base tkr_dummy;
651 const struct tk_read_base *tkr = &tk->tkr_mono;
652
653 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
654 cycles_at_suspend = tk_clock_read(tkr);
655 tkr_dummy.clock = &dummy_clock;
656 tkr_dummy.base_real = tkr->base + tk->offs_real;
657 update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
658
659 tkr = &tk->tkr_raw;
660 memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
661 tkr_dummy.clock = &dummy_clock;
662 update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
663 }
664
665 static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
666
update_pvclock_gtod(struct timekeeper * tk,bool was_set)667 static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
668 {
669 raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
670 }
671
672 /**
673 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
674 * @nb: Pointer to the notifier block to register
675 */
pvclock_gtod_register_notifier(struct notifier_block * nb)676 int pvclock_gtod_register_notifier(struct notifier_block *nb)
677 {
678 struct timekeeper *tk = &tk_core.timekeeper;
679 unsigned long flags;
680 int ret;
681
682 raw_spin_lock_irqsave(&timekeeper_lock, flags);
683 ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
684 update_pvclock_gtod(tk, true);
685 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
686
687 return ret;
688 }
689 EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
690
691 /**
692 * pvclock_gtod_unregister_notifier - unregister a pvclock
693 * timedata update listener
694 * @nb: Pointer to the notifier block to unregister
695 */
pvclock_gtod_unregister_notifier(struct notifier_block * nb)696 int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
697 {
698 unsigned long flags;
699 int ret;
700
701 raw_spin_lock_irqsave(&timekeeper_lock, flags);
702 ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
703 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
704
705 return ret;
706 }
707 EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
708
709 /*
710 * tk_update_leap_state - helper to update the next_leap_ktime
711 */
tk_update_leap_state(struct timekeeper * tk)712 static inline void tk_update_leap_state(struct timekeeper *tk)
713 {
714 tk->next_leap_ktime = ntp_get_next_leap();
715 if (tk->next_leap_ktime != KTIME_MAX)
716 /* Convert to monotonic time */
717 tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
718 }
719
720 /*
721 * Update the ktime_t based scalar nsec members of the timekeeper
722 */
tk_update_ktime_data(struct timekeeper * tk)723 static inline void tk_update_ktime_data(struct timekeeper *tk)
724 {
725 u64 seconds;
726 u32 nsec;
727
728 /*
729 * The xtime based monotonic readout is:
730 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
731 * The ktime based monotonic readout is:
732 * nsec = base_mono + now();
733 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
734 */
735 seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
736 nsec = (u32) tk->wall_to_monotonic.tv_nsec;
737 tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
738
739 /*
740 * The sum of the nanoseconds portions of xtime and
741 * wall_to_monotonic can be greater/equal one second. Take
742 * this into account before updating tk->ktime_sec.
743 */
744 nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
745 if (nsec >= NSEC_PER_SEC)
746 seconds++;
747 tk->ktime_sec = seconds;
748
749 /* Update the monotonic raw base */
750 tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
751 }
752
753 /* must hold timekeeper_lock */
timekeeping_update(struct timekeeper * tk,unsigned int action)754 static void timekeeping_update(struct timekeeper *tk, unsigned int action)
755 {
756 if (action & TK_CLEAR_NTP) {
757 tk->ntp_error = 0;
758 ntp_clear();
759 }
760
761 tk_update_leap_state(tk);
762 tk_update_ktime_data(tk);
763
764 update_vsyscall(tk);
765 update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
766
767 tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
768 update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
769 update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
770
771 if (action & TK_CLOCK_WAS_SET)
772 tk->clock_was_set_seq++;
773 /*
774 * The mirroring of the data to the shadow-timekeeper needs
775 * to happen last here to ensure we don't over-write the
776 * timekeeper structure on the next update with stale data
777 */
778 if (action & TK_MIRROR)
779 memcpy(&shadow_timekeeper, &tk_core.timekeeper,
780 sizeof(tk_core.timekeeper));
781 }
782
783 /**
784 * timekeeping_forward_now - update clock to the current time
785 * @tk: Pointer to the timekeeper to update
786 *
787 * Forward the current clock to update its state since the last call to
788 * update_wall_time(). This is useful before significant clock changes,
789 * as it avoids having to deal with this time offset explicitly.
790 */
timekeeping_forward_now(struct timekeeper * tk)791 static void timekeeping_forward_now(struct timekeeper *tk)
792 {
793 u64 cycle_now, delta;
794
795 cycle_now = tk_clock_read(&tk->tkr_mono);
796 delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
797 tk->tkr_mono.cycle_last = cycle_now;
798 tk->tkr_raw.cycle_last = cycle_now;
799
800 while (delta > 0) {
801 u64 max = tk->tkr_mono.clock->max_cycles;
802 u64 incr = delta < max ? delta : max;
803
804 tk->tkr_mono.xtime_nsec += incr * tk->tkr_mono.mult;
805 tk->tkr_raw.xtime_nsec += incr * tk->tkr_raw.mult;
806 tk_normalize_xtime(tk);
807 delta -= incr;
808 }
809 }
810
811 /**
812 * ktime_get_real_ts64 - Returns the time of day in a timespec64.
813 * @ts: pointer to the timespec to be set
814 *
815 * Returns the time of day in a timespec64 (WARN if suspended).
816 */
ktime_get_real_ts64(struct timespec64 * ts)817 void ktime_get_real_ts64(struct timespec64 *ts)
818 {
819 struct timekeeper *tk = &tk_core.timekeeper;
820 unsigned int seq;
821 u64 nsecs;
822
823 WARN_ON(timekeeping_suspended);
824
825 do {
826 seq = read_seqcount_begin(&tk_core.seq);
827
828 ts->tv_sec = tk->xtime_sec;
829 nsecs = timekeeping_get_ns(&tk->tkr_mono);
830
831 } while (read_seqcount_retry(&tk_core.seq, seq));
832
833 ts->tv_nsec = 0;
834 timespec64_add_ns(ts, nsecs);
835 }
836 EXPORT_SYMBOL(ktime_get_real_ts64);
837
ktime_get(void)838 ktime_t ktime_get(void)
839 {
840 struct timekeeper *tk = &tk_core.timekeeper;
841 unsigned int seq;
842 ktime_t base;
843 u64 nsecs;
844
845 WARN_ON(timekeeping_suspended);
846
847 do {
848 seq = read_seqcount_begin(&tk_core.seq);
849 base = tk->tkr_mono.base;
850 nsecs = timekeeping_get_ns(&tk->tkr_mono);
851
852 } while (read_seqcount_retry(&tk_core.seq, seq));
853
854 return ktime_add_ns(base, nsecs);
855 }
856 EXPORT_SYMBOL_GPL(ktime_get);
857
ktime_get_resolution_ns(void)858 u32 ktime_get_resolution_ns(void)
859 {
860 struct timekeeper *tk = &tk_core.timekeeper;
861 unsigned int seq;
862 u32 nsecs;
863
864 WARN_ON(timekeeping_suspended);
865
866 do {
867 seq = read_seqcount_begin(&tk_core.seq);
868 nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
869 } while (read_seqcount_retry(&tk_core.seq, seq));
870
871 return nsecs;
872 }
873 EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
874
875 static ktime_t *offsets[TK_OFFS_MAX] = {
876 [TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
877 [TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
878 [TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai,
879 };
880
ktime_get_with_offset(enum tk_offsets offs)881 ktime_t ktime_get_with_offset(enum tk_offsets offs)
882 {
883 struct timekeeper *tk = &tk_core.timekeeper;
884 unsigned int seq;
885 ktime_t base, *offset = offsets[offs];
886 u64 nsecs;
887
888 WARN_ON(timekeeping_suspended);
889
890 do {
891 seq = read_seqcount_begin(&tk_core.seq);
892 base = ktime_add(tk->tkr_mono.base, *offset);
893 nsecs = timekeeping_get_ns(&tk->tkr_mono);
894
895 } while (read_seqcount_retry(&tk_core.seq, seq));
896
897 return ktime_add_ns(base, nsecs);
898
899 }
900 EXPORT_SYMBOL_GPL(ktime_get_with_offset);
901
ktime_get_coarse_with_offset(enum tk_offsets offs)902 ktime_t ktime_get_coarse_with_offset(enum tk_offsets offs)
903 {
904 struct timekeeper *tk = &tk_core.timekeeper;
905 unsigned int seq;
906 ktime_t base, *offset = offsets[offs];
907 u64 nsecs;
908
909 WARN_ON(timekeeping_suspended);
910
911 do {
912 seq = read_seqcount_begin(&tk_core.seq);
913 base = ktime_add(tk->tkr_mono.base, *offset);
914 nsecs = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
915
916 } while (read_seqcount_retry(&tk_core.seq, seq));
917
918 return ktime_add_ns(base, nsecs);
919 }
920 EXPORT_SYMBOL_GPL(ktime_get_coarse_with_offset);
921
922 /**
923 * ktime_mono_to_any() - convert monotonic time to any other time
924 * @tmono: time to convert.
925 * @offs: which offset to use
926 */
ktime_mono_to_any(ktime_t tmono,enum tk_offsets offs)927 ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
928 {
929 ktime_t *offset = offsets[offs];
930 unsigned int seq;
931 ktime_t tconv;
932
933 do {
934 seq = read_seqcount_begin(&tk_core.seq);
935 tconv = ktime_add(tmono, *offset);
936 } while (read_seqcount_retry(&tk_core.seq, seq));
937
938 return tconv;
939 }
940 EXPORT_SYMBOL_GPL(ktime_mono_to_any);
941
942 /**
943 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
944 */
ktime_get_raw(void)945 ktime_t ktime_get_raw(void)
946 {
947 struct timekeeper *tk = &tk_core.timekeeper;
948 unsigned int seq;
949 ktime_t base;
950 u64 nsecs;
951
952 do {
953 seq = read_seqcount_begin(&tk_core.seq);
954 base = tk->tkr_raw.base;
955 nsecs = timekeeping_get_ns(&tk->tkr_raw);
956
957 } while (read_seqcount_retry(&tk_core.seq, seq));
958
959 return ktime_add_ns(base, nsecs);
960 }
961 EXPORT_SYMBOL_GPL(ktime_get_raw);
962
963 /**
964 * ktime_get_ts64 - get the monotonic clock in timespec64 format
965 * @ts: pointer to timespec variable
966 *
967 * The function calculates the monotonic clock from the realtime
968 * clock and the wall_to_monotonic offset and stores the result
969 * in normalized timespec64 format in the variable pointed to by @ts.
970 */
ktime_get_ts64(struct timespec64 * ts)971 void ktime_get_ts64(struct timespec64 *ts)
972 {
973 struct timekeeper *tk = &tk_core.timekeeper;
974 struct timespec64 tomono;
975 unsigned int seq;
976 u64 nsec;
977
978 WARN_ON(timekeeping_suspended);
979
980 do {
981 seq = read_seqcount_begin(&tk_core.seq);
982 ts->tv_sec = tk->xtime_sec;
983 nsec = timekeeping_get_ns(&tk->tkr_mono);
984 tomono = tk->wall_to_monotonic;
985
986 } while (read_seqcount_retry(&tk_core.seq, seq));
987
988 ts->tv_sec += tomono.tv_sec;
989 ts->tv_nsec = 0;
990 timespec64_add_ns(ts, nsec + tomono.tv_nsec);
991 }
992 EXPORT_SYMBOL_GPL(ktime_get_ts64);
993
994 /**
995 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
996 *
997 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
998 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
999 * works on both 32 and 64 bit systems. On 32 bit systems the readout
1000 * covers ~136 years of uptime which should be enough to prevent
1001 * premature wrap arounds.
1002 */
ktime_get_seconds(void)1003 time64_t ktime_get_seconds(void)
1004 {
1005 struct timekeeper *tk = &tk_core.timekeeper;
1006
1007 WARN_ON(timekeeping_suspended);
1008 return tk->ktime_sec;
1009 }
1010 EXPORT_SYMBOL_GPL(ktime_get_seconds);
1011
1012 /**
1013 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
1014 *
1015 * Returns the wall clock seconds since 1970.
1016 *
1017 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
1018 * 32bit systems the access must be protected with the sequence
1019 * counter to provide "atomic" access to the 64bit tk->xtime_sec
1020 * value.
1021 */
ktime_get_real_seconds(void)1022 time64_t ktime_get_real_seconds(void)
1023 {
1024 struct timekeeper *tk = &tk_core.timekeeper;
1025 time64_t seconds;
1026 unsigned int seq;
1027
1028 if (IS_ENABLED(CONFIG_64BIT))
1029 return tk->xtime_sec;
1030
1031 do {
1032 seq = read_seqcount_begin(&tk_core.seq);
1033 seconds = tk->xtime_sec;
1034
1035 } while (read_seqcount_retry(&tk_core.seq, seq));
1036
1037 return seconds;
1038 }
1039 EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
1040
1041 /**
1042 * __ktime_get_real_seconds - The same as ktime_get_real_seconds
1043 * but without the sequence counter protect. This internal function
1044 * is called just when timekeeping lock is already held.
1045 */
__ktime_get_real_seconds(void)1046 noinstr time64_t __ktime_get_real_seconds(void)
1047 {
1048 struct timekeeper *tk = &tk_core.timekeeper;
1049
1050 return tk->xtime_sec;
1051 }
1052
1053 /**
1054 * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
1055 * @systime_snapshot: pointer to struct receiving the system time snapshot
1056 */
ktime_get_snapshot(struct system_time_snapshot * systime_snapshot)1057 void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
1058 {
1059 struct timekeeper *tk = &tk_core.timekeeper;
1060 unsigned int seq;
1061 ktime_t base_raw;
1062 ktime_t base_real;
1063 u64 nsec_raw;
1064 u64 nsec_real;
1065 u64 now;
1066
1067 WARN_ON_ONCE(timekeeping_suspended);
1068
1069 do {
1070 seq = read_seqcount_begin(&tk_core.seq);
1071 now = tk_clock_read(&tk->tkr_mono);
1072 systime_snapshot->cs_id = tk->tkr_mono.clock->id;
1073 systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
1074 systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
1075 base_real = ktime_add(tk->tkr_mono.base,
1076 tk_core.timekeeper.offs_real);
1077 base_raw = tk->tkr_raw.base;
1078 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
1079 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
1080 } while (read_seqcount_retry(&tk_core.seq, seq));
1081
1082 systime_snapshot->cycles = now;
1083 systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
1084 systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
1085 }
1086 EXPORT_SYMBOL_GPL(ktime_get_snapshot);
1087
1088 /* Scale base by mult/div checking for overflow */
scale64_check_overflow(u64 mult,u64 div,u64 * base)1089 static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
1090 {
1091 u64 tmp, rem;
1092
1093 tmp = div64_u64_rem(*base, div, &rem);
1094
1095 if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
1096 ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
1097 return -EOVERFLOW;
1098 tmp *= mult;
1099
1100 rem = div64_u64(rem * mult, div);
1101 *base = tmp + rem;
1102 return 0;
1103 }
1104
1105 /**
1106 * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
1107 * @history: Snapshot representing start of history
1108 * @partial_history_cycles: Cycle offset into history (fractional part)
1109 * @total_history_cycles: Total history length in cycles
1110 * @discontinuity: True indicates clock was set on history period
1111 * @ts: Cross timestamp that should be adjusted using
1112 * partial/total ratio
1113 *
1114 * Helper function used by get_device_system_crosststamp() to correct the
1115 * crosstimestamp corresponding to the start of the current interval to the
1116 * system counter value (timestamp point) provided by the driver. The
1117 * total_history_* quantities are the total history starting at the provided
1118 * reference point and ending at the start of the current interval. The cycle
1119 * count between the driver timestamp point and the start of the current
1120 * interval is partial_history_cycles.
1121 */
adjust_historical_crosststamp(struct system_time_snapshot * history,u64 partial_history_cycles,u64 total_history_cycles,bool discontinuity,struct system_device_crosststamp * ts)1122 static int adjust_historical_crosststamp(struct system_time_snapshot *history,
1123 u64 partial_history_cycles,
1124 u64 total_history_cycles,
1125 bool discontinuity,
1126 struct system_device_crosststamp *ts)
1127 {
1128 struct timekeeper *tk = &tk_core.timekeeper;
1129 u64 corr_raw, corr_real;
1130 bool interp_forward;
1131 int ret;
1132
1133 if (total_history_cycles == 0 || partial_history_cycles == 0)
1134 return 0;
1135
1136 /* Interpolate shortest distance from beginning or end of history */
1137 interp_forward = partial_history_cycles > total_history_cycles / 2;
1138 partial_history_cycles = interp_forward ?
1139 total_history_cycles - partial_history_cycles :
1140 partial_history_cycles;
1141
1142 /*
1143 * Scale the monotonic raw time delta by:
1144 * partial_history_cycles / total_history_cycles
1145 */
1146 corr_raw = (u64)ktime_to_ns(
1147 ktime_sub(ts->sys_monoraw, history->raw));
1148 ret = scale64_check_overflow(partial_history_cycles,
1149 total_history_cycles, &corr_raw);
1150 if (ret)
1151 return ret;
1152
1153 /*
1154 * If there is a discontinuity in the history, scale monotonic raw
1155 * correction by:
1156 * mult(real)/mult(raw) yielding the realtime correction
1157 * Otherwise, calculate the realtime correction similar to monotonic
1158 * raw calculation
1159 */
1160 if (discontinuity) {
1161 corr_real = mul_u64_u32_div
1162 (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1163 } else {
1164 corr_real = (u64)ktime_to_ns(
1165 ktime_sub(ts->sys_realtime, history->real));
1166 ret = scale64_check_overflow(partial_history_cycles,
1167 total_history_cycles, &corr_real);
1168 if (ret)
1169 return ret;
1170 }
1171
1172 /* Fixup monotonic raw and real time time values */
1173 if (interp_forward) {
1174 ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1175 ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1176 } else {
1177 ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1178 ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1179 }
1180
1181 return 0;
1182 }
1183
1184 /*
1185 * timestamp_in_interval - true if ts is chronologically in [start, end]
1186 *
1187 * True if ts occurs chronologically at or after start, and before or at end.
1188 */
timestamp_in_interval(u64 start,u64 end,u64 ts)1189 static bool timestamp_in_interval(u64 start, u64 end, u64 ts)
1190 {
1191 if (ts >= start && ts <= end)
1192 return true;
1193 if (start > end && (ts >= start || ts <= end))
1194 return true;
1195 return false;
1196 }
1197
1198 /**
1199 * get_device_system_crosststamp - Synchronously capture system/device timestamp
1200 * @get_time_fn: Callback to get simultaneous device time and
1201 * system counter from the device driver
1202 * @ctx: Context passed to get_time_fn()
1203 * @history_begin: Historical reference point used to interpolate system
1204 * time when counter provided by the driver is before the current interval
1205 * @xtstamp: Receives simultaneously captured system and device time
1206 *
1207 * Reads a timestamp from a device and correlates it to system time
1208 */
get_device_system_crosststamp(int (* get_time_fn)(ktime_t * device_time,struct system_counterval_t * sys_counterval,void * ctx),void * ctx,struct system_time_snapshot * history_begin,struct system_device_crosststamp * xtstamp)1209 int get_device_system_crosststamp(int (*get_time_fn)
1210 (ktime_t *device_time,
1211 struct system_counterval_t *sys_counterval,
1212 void *ctx),
1213 void *ctx,
1214 struct system_time_snapshot *history_begin,
1215 struct system_device_crosststamp *xtstamp)
1216 {
1217 struct system_counterval_t system_counterval;
1218 struct timekeeper *tk = &tk_core.timekeeper;
1219 u64 cycles, now, interval_start;
1220 unsigned int clock_was_set_seq = 0;
1221 ktime_t base_real, base_raw;
1222 u64 nsec_real, nsec_raw;
1223 u8 cs_was_changed_seq;
1224 unsigned int seq;
1225 bool do_interp;
1226 int ret;
1227
1228 do {
1229 seq = read_seqcount_begin(&tk_core.seq);
1230 /*
1231 * Try to synchronously capture device time and a system
1232 * counter value calling back into the device driver
1233 */
1234 ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1235 if (ret)
1236 return ret;
1237
1238 /*
1239 * Verify that the clocksource ID associated with the captured
1240 * system counter value is the same as for the currently
1241 * installed timekeeper clocksource
1242 */
1243 if (system_counterval.cs_id == CSID_GENERIC ||
1244 tk->tkr_mono.clock->id != system_counterval.cs_id)
1245 return -ENODEV;
1246 cycles = system_counterval.cycles;
1247
1248 /*
1249 * Check whether the system counter value provided by the
1250 * device driver is on the current timekeeping interval.
1251 */
1252 now = tk_clock_read(&tk->tkr_mono);
1253 interval_start = tk->tkr_mono.cycle_last;
1254 if (!timestamp_in_interval(interval_start, now, cycles)) {
1255 clock_was_set_seq = tk->clock_was_set_seq;
1256 cs_was_changed_seq = tk->cs_was_changed_seq;
1257 cycles = interval_start;
1258 do_interp = true;
1259 } else {
1260 do_interp = false;
1261 }
1262
1263 base_real = ktime_add(tk->tkr_mono.base,
1264 tk_core.timekeeper.offs_real);
1265 base_raw = tk->tkr_raw.base;
1266
1267 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, cycles);
1268 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, cycles);
1269 } while (read_seqcount_retry(&tk_core.seq, seq));
1270
1271 xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1272 xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1273
1274 /*
1275 * Interpolate if necessary, adjusting back from the start of the
1276 * current interval
1277 */
1278 if (do_interp) {
1279 u64 partial_history_cycles, total_history_cycles;
1280 bool discontinuity;
1281
1282 /*
1283 * Check that the counter value is not before the provided
1284 * history reference and that the history doesn't cross a
1285 * clocksource change
1286 */
1287 if (!history_begin ||
1288 !timestamp_in_interval(history_begin->cycles,
1289 cycles, system_counterval.cycles) ||
1290 history_begin->cs_was_changed_seq != cs_was_changed_seq)
1291 return -EINVAL;
1292 partial_history_cycles = cycles - system_counterval.cycles;
1293 total_history_cycles = cycles - history_begin->cycles;
1294 discontinuity =
1295 history_begin->clock_was_set_seq != clock_was_set_seq;
1296
1297 ret = adjust_historical_crosststamp(history_begin,
1298 partial_history_cycles,
1299 total_history_cycles,
1300 discontinuity, xtstamp);
1301 if (ret)
1302 return ret;
1303 }
1304
1305 return 0;
1306 }
1307 EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1308
1309 /**
1310 * do_settimeofday64 - Sets the time of day.
1311 * @ts: pointer to the timespec64 variable containing the new time
1312 *
1313 * Sets the time of day to the new time and update NTP and notify hrtimers
1314 */
do_settimeofday64(const struct timespec64 * ts)1315 int do_settimeofday64(const struct timespec64 *ts)
1316 {
1317 struct timekeeper *tk = &tk_core.timekeeper;
1318 struct timespec64 ts_delta, xt;
1319 unsigned long flags;
1320 int ret = 0;
1321
1322 if (!timespec64_valid_settod(ts))
1323 return -EINVAL;
1324
1325 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1326 write_seqcount_begin(&tk_core.seq);
1327
1328 timekeeping_forward_now(tk);
1329
1330 xt = tk_xtime(tk);
1331 ts_delta = timespec64_sub(*ts, xt);
1332
1333 if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1334 ret = -EINVAL;
1335 goto out;
1336 }
1337
1338 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1339
1340 tk_set_xtime(tk, ts);
1341 out:
1342 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1343
1344 write_seqcount_end(&tk_core.seq);
1345 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1346
1347 /* Signal hrtimers about time change */
1348 clock_was_set(CLOCK_SET_WALL);
1349
1350 if (!ret) {
1351 audit_tk_injoffset(ts_delta);
1352 add_device_randomness(ts, sizeof(*ts));
1353 }
1354
1355 return ret;
1356 }
1357 EXPORT_SYMBOL(do_settimeofday64);
1358
1359 /**
1360 * timekeeping_inject_offset - Adds or subtracts from the current time.
1361 * @ts: Pointer to the timespec variable containing the offset
1362 *
1363 * Adds or subtracts an offset value from the current time.
1364 */
timekeeping_inject_offset(const struct timespec64 * ts)1365 static int timekeeping_inject_offset(const struct timespec64 *ts)
1366 {
1367 struct timekeeper *tk = &tk_core.timekeeper;
1368 unsigned long flags;
1369 struct timespec64 tmp;
1370 int ret = 0;
1371
1372 if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
1373 return -EINVAL;
1374
1375 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1376 write_seqcount_begin(&tk_core.seq);
1377
1378 timekeeping_forward_now(tk);
1379
1380 /* Make sure the proposed value is valid */
1381 tmp = timespec64_add(tk_xtime(tk), *ts);
1382 if (timespec64_compare(&tk->wall_to_monotonic, ts) > 0 ||
1383 !timespec64_valid_settod(&tmp)) {
1384 ret = -EINVAL;
1385 goto error;
1386 }
1387
1388 tk_xtime_add(tk, ts);
1389 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *ts));
1390
1391 error: /* even if we error out, we forwarded the time, so call update */
1392 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1393
1394 write_seqcount_end(&tk_core.seq);
1395 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1396
1397 /* Signal hrtimers about time change */
1398 clock_was_set(CLOCK_SET_WALL);
1399
1400 return ret;
1401 }
1402
1403 /*
1404 * Indicates if there is an offset between the system clock and the hardware
1405 * clock/persistent clock/rtc.
1406 */
1407 int persistent_clock_is_local;
1408
1409 /*
1410 * Adjust the time obtained from the CMOS to be UTC time instead of
1411 * local time.
1412 *
1413 * This is ugly, but preferable to the alternatives. Otherwise we
1414 * would either need to write a program to do it in /etc/rc (and risk
1415 * confusion if the program gets run more than once; it would also be
1416 * hard to make the program warp the clock precisely n hours) or
1417 * compile in the timezone information into the kernel. Bad, bad....
1418 *
1419 * - TYT, 1992-01-01
1420 *
1421 * The best thing to do is to keep the CMOS clock in universal time (UTC)
1422 * as real UNIX machines always do it. This avoids all headaches about
1423 * daylight saving times and warping kernel clocks.
1424 */
timekeeping_warp_clock(void)1425 void timekeeping_warp_clock(void)
1426 {
1427 if (sys_tz.tz_minuteswest != 0) {
1428 struct timespec64 adjust;
1429
1430 persistent_clock_is_local = 1;
1431 adjust.tv_sec = sys_tz.tz_minuteswest * 60;
1432 adjust.tv_nsec = 0;
1433 timekeeping_inject_offset(&adjust);
1434 }
1435 }
1436
1437 /*
1438 * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1439 */
__timekeeping_set_tai_offset(struct timekeeper * tk,s32 tai_offset)1440 static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1441 {
1442 tk->tai_offset = tai_offset;
1443 tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1444 }
1445
1446 /*
1447 * change_clocksource - Swaps clocksources if a new one is available
1448 *
1449 * Accumulates current time interval and initializes new clocksource
1450 */
change_clocksource(void * data)1451 static int change_clocksource(void *data)
1452 {
1453 struct timekeeper *tk = &tk_core.timekeeper;
1454 struct clocksource *new, *old = NULL;
1455 unsigned long flags;
1456 bool change = false;
1457
1458 new = (struct clocksource *) data;
1459
1460 /*
1461 * If the cs is in module, get a module reference. Succeeds
1462 * for built-in code (owner == NULL) as well.
1463 */
1464 if (try_module_get(new->owner)) {
1465 if (!new->enable || new->enable(new) == 0)
1466 change = true;
1467 else
1468 module_put(new->owner);
1469 }
1470
1471 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1472 write_seqcount_begin(&tk_core.seq);
1473
1474 timekeeping_forward_now(tk);
1475
1476 if (change) {
1477 old = tk->tkr_mono.clock;
1478 tk_setup_internals(tk, new);
1479 }
1480
1481 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1482
1483 write_seqcount_end(&tk_core.seq);
1484 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1485
1486 if (old) {
1487 if (old->disable)
1488 old->disable(old);
1489
1490 module_put(old->owner);
1491 }
1492
1493 return 0;
1494 }
1495
1496 /**
1497 * timekeeping_notify - Install a new clock source
1498 * @clock: pointer to the clock source
1499 *
1500 * This function is called from clocksource.c after a new, better clock
1501 * source has been registered. The caller holds the clocksource_mutex.
1502 */
timekeeping_notify(struct clocksource * clock)1503 int timekeeping_notify(struct clocksource *clock)
1504 {
1505 struct timekeeper *tk = &tk_core.timekeeper;
1506
1507 if (tk->tkr_mono.clock == clock)
1508 return 0;
1509 stop_machine(change_clocksource, clock, NULL);
1510 tick_clock_notify();
1511 return tk->tkr_mono.clock == clock ? 0 : -1;
1512 }
1513
1514 /**
1515 * ktime_get_raw_ts64 - Returns the raw monotonic time in a timespec
1516 * @ts: pointer to the timespec64 to be set
1517 *
1518 * Returns the raw monotonic time (completely un-modified by ntp)
1519 */
ktime_get_raw_ts64(struct timespec64 * ts)1520 void ktime_get_raw_ts64(struct timespec64 *ts)
1521 {
1522 struct timekeeper *tk = &tk_core.timekeeper;
1523 unsigned int seq;
1524 u64 nsecs;
1525
1526 do {
1527 seq = read_seqcount_begin(&tk_core.seq);
1528 ts->tv_sec = tk->raw_sec;
1529 nsecs = timekeeping_get_ns(&tk->tkr_raw);
1530
1531 } while (read_seqcount_retry(&tk_core.seq, seq));
1532
1533 ts->tv_nsec = 0;
1534 timespec64_add_ns(ts, nsecs);
1535 }
1536 EXPORT_SYMBOL(ktime_get_raw_ts64);
1537
1538
1539 /**
1540 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1541 */
timekeeping_valid_for_hres(void)1542 int timekeeping_valid_for_hres(void)
1543 {
1544 struct timekeeper *tk = &tk_core.timekeeper;
1545 unsigned int seq;
1546 int ret;
1547
1548 do {
1549 seq = read_seqcount_begin(&tk_core.seq);
1550
1551 ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1552
1553 } while (read_seqcount_retry(&tk_core.seq, seq));
1554
1555 return ret;
1556 }
1557
1558 /**
1559 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1560 */
timekeeping_max_deferment(void)1561 u64 timekeeping_max_deferment(void)
1562 {
1563 struct timekeeper *tk = &tk_core.timekeeper;
1564 unsigned int seq;
1565 u64 ret;
1566
1567 do {
1568 seq = read_seqcount_begin(&tk_core.seq);
1569
1570 ret = tk->tkr_mono.clock->max_idle_ns;
1571
1572 } while (read_seqcount_retry(&tk_core.seq, seq));
1573
1574 return ret;
1575 }
1576
1577 /**
1578 * read_persistent_clock64 - Return time from the persistent clock.
1579 * @ts: Pointer to the storage for the readout value
1580 *
1581 * Weak dummy function for arches that do not yet support it.
1582 * Reads the time from the battery backed persistent clock.
1583 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1584 *
1585 * XXX - Do be sure to remove it once all arches implement it.
1586 */
read_persistent_clock64(struct timespec64 * ts)1587 void __weak read_persistent_clock64(struct timespec64 *ts)
1588 {
1589 ts->tv_sec = 0;
1590 ts->tv_nsec = 0;
1591 }
1592
1593 /**
1594 * read_persistent_wall_and_boot_offset - Read persistent clock, and also offset
1595 * from the boot.
1596 * @wall_time: current time as returned by persistent clock
1597 * @boot_offset: offset that is defined as wall_time - boot_time
1598 *
1599 * Weak dummy function for arches that do not yet support it.
1600 *
1601 * The default function calculates offset based on the current value of
1602 * local_clock(). This way architectures that support sched_clock() but don't
1603 * support dedicated boot time clock will provide the best estimate of the
1604 * boot time.
1605 */
1606 void __weak __init
read_persistent_wall_and_boot_offset(struct timespec64 * wall_time,struct timespec64 * boot_offset)1607 read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
1608 struct timespec64 *boot_offset)
1609 {
1610 read_persistent_clock64(wall_time);
1611 *boot_offset = ns_to_timespec64(local_clock());
1612 }
1613
1614 /*
1615 * Flag reflecting whether timekeeping_resume() has injected sleeptime.
1616 *
1617 * The flag starts of false and is only set when a suspend reaches
1618 * timekeeping_suspend(), timekeeping_resume() sets it to false when the
1619 * timekeeper clocksource is not stopping across suspend and has been
1620 * used to update sleep time. If the timekeeper clocksource has stopped
1621 * then the flag stays true and is used by the RTC resume code to decide
1622 * whether sleeptime must be injected and if so the flag gets false then.
1623 *
1624 * If a suspend fails before reaching timekeeping_resume() then the flag
1625 * stays false and prevents erroneous sleeptime injection.
1626 */
1627 static bool suspend_timing_needed;
1628
1629 /* Flag for if there is a persistent clock on this platform */
1630 static bool persistent_clock_exists;
1631
1632 /*
1633 * timekeeping_init - Initializes the clocksource and common timekeeping values
1634 */
timekeeping_init(void)1635 void __init timekeeping_init(void)
1636 {
1637 struct timespec64 wall_time, boot_offset, wall_to_mono;
1638 struct timekeeper *tk = &tk_core.timekeeper;
1639 struct clocksource *clock;
1640 unsigned long flags;
1641
1642 read_persistent_wall_and_boot_offset(&wall_time, &boot_offset);
1643 if (timespec64_valid_settod(&wall_time) &&
1644 timespec64_to_ns(&wall_time) > 0) {
1645 persistent_clock_exists = true;
1646 } else if (timespec64_to_ns(&wall_time) != 0) {
1647 pr_warn("Persistent clock returned invalid value");
1648 wall_time = (struct timespec64){0};
1649 }
1650
1651 if (timespec64_compare(&wall_time, &boot_offset) < 0)
1652 boot_offset = (struct timespec64){0};
1653
1654 /*
1655 * We want set wall_to_mono, so the following is true:
1656 * wall time + wall_to_mono = boot time
1657 */
1658 wall_to_mono = timespec64_sub(boot_offset, wall_time);
1659
1660 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1661 write_seqcount_begin(&tk_core.seq);
1662 ntp_init();
1663
1664 clock = clocksource_default_clock();
1665 if (clock->enable)
1666 clock->enable(clock);
1667 tk_setup_internals(tk, clock);
1668
1669 tk_set_xtime(tk, &wall_time);
1670 tk->raw_sec = 0;
1671
1672 tk_set_wall_to_mono(tk, wall_to_mono);
1673
1674 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1675
1676 write_seqcount_end(&tk_core.seq);
1677 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1678 }
1679
1680 /* time in seconds when suspend began for persistent clock */
1681 static struct timespec64 timekeeping_suspend_time;
1682
1683 /**
1684 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1685 * @tk: Pointer to the timekeeper to be updated
1686 * @delta: Pointer to the delta value in timespec64 format
1687 *
1688 * Takes a timespec offset measuring a suspend interval and properly
1689 * adds the sleep offset to the timekeeping variables.
1690 */
__timekeeping_inject_sleeptime(struct timekeeper * tk,const struct timespec64 * delta)1691 static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1692 const struct timespec64 *delta)
1693 {
1694 if (!timespec64_valid_strict(delta)) {
1695 printk_deferred(KERN_WARNING
1696 "__timekeeping_inject_sleeptime: Invalid "
1697 "sleep delta value!\n");
1698 return;
1699 }
1700 tk_xtime_add(tk, delta);
1701 tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1702 tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1703 tk_debug_account_sleep_time(delta);
1704 }
1705
1706 #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1707 /*
1708 * We have three kinds of time sources to use for sleep time
1709 * injection, the preference order is:
1710 * 1) non-stop clocksource
1711 * 2) persistent clock (ie: RTC accessible when irqs are off)
1712 * 3) RTC
1713 *
1714 * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1715 * If system has neither 1) nor 2), 3) will be used finally.
1716 *
1717 *
1718 * If timekeeping has injected sleeptime via either 1) or 2),
1719 * 3) becomes needless, so in this case we don't need to call
1720 * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1721 * means.
1722 */
timekeeping_rtc_skipresume(void)1723 bool timekeeping_rtc_skipresume(void)
1724 {
1725 return !suspend_timing_needed;
1726 }
1727
1728 /*
1729 * 1) can be determined whether to use or not only when doing
1730 * timekeeping_resume() which is invoked after rtc_suspend(),
1731 * so we can't skip rtc_suspend() surely if system has 1).
1732 *
1733 * But if system has 2), 2) will definitely be used, so in this
1734 * case we don't need to call rtc_suspend(), and this is what
1735 * timekeeping_rtc_skipsuspend() means.
1736 */
timekeeping_rtc_skipsuspend(void)1737 bool timekeeping_rtc_skipsuspend(void)
1738 {
1739 return persistent_clock_exists;
1740 }
1741
1742 /**
1743 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1744 * @delta: pointer to a timespec64 delta value
1745 *
1746 * This hook is for architectures that cannot support read_persistent_clock64
1747 * because their RTC/persistent clock is only accessible when irqs are enabled.
1748 * and also don't have an effective nonstop clocksource.
1749 *
1750 * This function should only be called by rtc_resume(), and allows
1751 * a suspend offset to be injected into the timekeeping values.
1752 */
timekeeping_inject_sleeptime64(const struct timespec64 * delta)1753 void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
1754 {
1755 struct timekeeper *tk = &tk_core.timekeeper;
1756 unsigned long flags;
1757
1758 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1759 write_seqcount_begin(&tk_core.seq);
1760
1761 suspend_timing_needed = false;
1762
1763 timekeeping_forward_now(tk);
1764
1765 __timekeeping_inject_sleeptime(tk, delta);
1766
1767 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1768
1769 write_seqcount_end(&tk_core.seq);
1770 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1771
1772 /* Signal hrtimers about time change */
1773 clock_was_set(CLOCK_SET_WALL | CLOCK_SET_BOOT);
1774 }
1775 #endif
1776
1777 /**
1778 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1779 */
timekeeping_resume(void)1780 void timekeeping_resume(void)
1781 {
1782 struct timekeeper *tk = &tk_core.timekeeper;
1783 struct clocksource *clock = tk->tkr_mono.clock;
1784 unsigned long flags;
1785 struct timespec64 ts_new, ts_delta;
1786 u64 cycle_now, nsec;
1787 bool inject_sleeptime = false;
1788
1789 read_persistent_clock64(&ts_new);
1790
1791 clockevents_resume();
1792 clocksource_resume();
1793
1794 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1795 write_seqcount_begin(&tk_core.seq);
1796
1797 /*
1798 * After system resumes, we need to calculate the suspended time and
1799 * compensate it for the OS time. There are 3 sources that could be
1800 * used: Nonstop clocksource during suspend, persistent clock and rtc
1801 * device.
1802 *
1803 * One specific platform may have 1 or 2 or all of them, and the
1804 * preference will be:
1805 * suspend-nonstop clocksource -> persistent clock -> rtc
1806 * The less preferred source will only be tried if there is no better
1807 * usable source. The rtc part is handled separately in rtc core code.
1808 */
1809 cycle_now = tk_clock_read(&tk->tkr_mono);
1810 nsec = clocksource_stop_suspend_timing(clock, cycle_now);
1811 if (nsec > 0) {
1812 ts_delta = ns_to_timespec64(nsec);
1813 inject_sleeptime = true;
1814 } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1815 ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1816 inject_sleeptime = true;
1817 }
1818
1819 if (inject_sleeptime) {
1820 suspend_timing_needed = false;
1821 __timekeeping_inject_sleeptime(tk, &ts_delta);
1822 }
1823
1824 /* Re-base the last cycle value */
1825 tk->tkr_mono.cycle_last = cycle_now;
1826 tk->tkr_raw.cycle_last = cycle_now;
1827
1828 tk->ntp_error = 0;
1829 timekeeping_suspended = 0;
1830 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1831 write_seqcount_end(&tk_core.seq);
1832 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1833
1834 touch_softlockup_watchdog();
1835
1836 /* Resume the clockevent device(s) and hrtimers */
1837 tick_resume();
1838 /* Notify timerfd as resume is equivalent to clock_was_set() */
1839 timerfd_resume();
1840 }
1841
timekeeping_suspend(void)1842 int timekeeping_suspend(void)
1843 {
1844 struct timekeeper *tk = &tk_core.timekeeper;
1845 unsigned long flags;
1846 struct timespec64 delta, delta_delta;
1847 static struct timespec64 old_delta;
1848 struct clocksource *curr_clock;
1849 u64 cycle_now;
1850
1851 read_persistent_clock64(&timekeeping_suspend_time);
1852
1853 /*
1854 * On some systems the persistent_clock can not be detected at
1855 * timekeeping_init by its return value, so if we see a valid
1856 * value returned, update the persistent_clock_exists flag.
1857 */
1858 if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1859 persistent_clock_exists = true;
1860
1861 suspend_timing_needed = true;
1862
1863 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1864 write_seqcount_begin(&tk_core.seq);
1865 timekeeping_forward_now(tk);
1866 timekeeping_suspended = 1;
1867
1868 /*
1869 * Since we've called forward_now, cycle_last stores the value
1870 * just read from the current clocksource. Save this to potentially
1871 * use in suspend timing.
1872 */
1873 curr_clock = tk->tkr_mono.clock;
1874 cycle_now = tk->tkr_mono.cycle_last;
1875 clocksource_start_suspend_timing(curr_clock, cycle_now);
1876
1877 if (persistent_clock_exists) {
1878 /*
1879 * To avoid drift caused by repeated suspend/resumes,
1880 * which each can add ~1 second drift error,
1881 * try to compensate so the difference in system time
1882 * and persistent_clock time stays close to constant.
1883 */
1884 delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1885 delta_delta = timespec64_sub(delta, old_delta);
1886 if (abs(delta_delta.tv_sec) >= 2) {
1887 /*
1888 * if delta_delta is too large, assume time correction
1889 * has occurred and set old_delta to the current delta.
1890 */
1891 old_delta = delta;
1892 } else {
1893 /* Otherwise try to adjust old_system to compensate */
1894 timekeeping_suspend_time =
1895 timespec64_add(timekeeping_suspend_time, delta_delta);
1896 }
1897 }
1898
1899 timekeeping_update(tk, TK_MIRROR);
1900 halt_fast_timekeeper(tk);
1901 write_seqcount_end(&tk_core.seq);
1902 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1903
1904 tick_suspend();
1905 clocksource_suspend();
1906 clockevents_suspend();
1907
1908 return 0;
1909 }
1910
1911 /* sysfs resume/suspend bits for timekeeping */
1912 static struct syscore_ops timekeeping_syscore_ops = {
1913 .resume = timekeeping_resume,
1914 .suspend = timekeeping_suspend,
1915 };
1916
timekeeping_init_ops(void)1917 static int __init timekeeping_init_ops(void)
1918 {
1919 register_syscore_ops(&timekeeping_syscore_ops);
1920 return 0;
1921 }
1922 device_initcall(timekeeping_init_ops);
1923
1924 /*
1925 * Apply a multiplier adjustment to the timekeeper
1926 */
timekeeping_apply_adjustment(struct timekeeper * tk,s64 offset,s32 mult_adj)1927 static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1928 s64 offset,
1929 s32 mult_adj)
1930 {
1931 s64 interval = tk->cycle_interval;
1932
1933 if (mult_adj == 0) {
1934 return;
1935 } else if (mult_adj == -1) {
1936 interval = -interval;
1937 offset = -offset;
1938 } else if (mult_adj != 1) {
1939 interval *= mult_adj;
1940 offset *= mult_adj;
1941 }
1942
1943 /*
1944 * So the following can be confusing.
1945 *
1946 * To keep things simple, lets assume mult_adj == 1 for now.
1947 *
1948 * When mult_adj != 1, remember that the interval and offset values
1949 * have been appropriately scaled so the math is the same.
1950 *
1951 * The basic idea here is that we're increasing the multiplier
1952 * by one, this causes the xtime_interval to be incremented by
1953 * one cycle_interval. This is because:
1954 * xtime_interval = cycle_interval * mult
1955 * So if mult is being incremented by one:
1956 * xtime_interval = cycle_interval * (mult + 1)
1957 * Its the same as:
1958 * xtime_interval = (cycle_interval * mult) + cycle_interval
1959 * Which can be shortened to:
1960 * xtime_interval += cycle_interval
1961 *
1962 * So offset stores the non-accumulated cycles. Thus the current
1963 * time (in shifted nanoseconds) is:
1964 * now = (offset * adj) + xtime_nsec
1965 * Now, even though we're adjusting the clock frequency, we have
1966 * to keep time consistent. In other words, we can't jump back
1967 * in time, and we also want to avoid jumping forward in time.
1968 *
1969 * So given the same offset value, we need the time to be the same
1970 * both before and after the freq adjustment.
1971 * now = (offset * adj_1) + xtime_nsec_1
1972 * now = (offset * adj_2) + xtime_nsec_2
1973 * So:
1974 * (offset * adj_1) + xtime_nsec_1 =
1975 * (offset * adj_2) + xtime_nsec_2
1976 * And we know:
1977 * adj_2 = adj_1 + 1
1978 * So:
1979 * (offset * adj_1) + xtime_nsec_1 =
1980 * (offset * (adj_1+1)) + xtime_nsec_2
1981 * (offset * adj_1) + xtime_nsec_1 =
1982 * (offset * adj_1) + offset + xtime_nsec_2
1983 * Canceling the sides:
1984 * xtime_nsec_1 = offset + xtime_nsec_2
1985 * Which gives us:
1986 * xtime_nsec_2 = xtime_nsec_1 - offset
1987 * Which simplifies to:
1988 * xtime_nsec -= offset
1989 */
1990 if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1991 /* NTP adjustment caused clocksource mult overflow */
1992 WARN_ON_ONCE(1);
1993 return;
1994 }
1995
1996 tk->tkr_mono.mult += mult_adj;
1997 tk->xtime_interval += interval;
1998 tk->tkr_mono.xtime_nsec -= offset;
1999 }
2000
2001 /*
2002 * Adjust the timekeeper's multiplier to the correct frequency
2003 * and also to reduce the accumulated error value.
2004 */
timekeeping_adjust(struct timekeeper * tk,s64 offset)2005 static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
2006 {
2007 u32 mult;
2008
2009 /*
2010 * Determine the multiplier from the current NTP tick length.
2011 * Avoid expensive division when the tick length doesn't change.
2012 */
2013 if (likely(tk->ntp_tick == ntp_tick_length())) {
2014 mult = tk->tkr_mono.mult - tk->ntp_err_mult;
2015 } else {
2016 tk->ntp_tick = ntp_tick_length();
2017 mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) -
2018 tk->xtime_remainder, tk->cycle_interval);
2019 }
2020
2021 /*
2022 * If the clock is behind the NTP time, increase the multiplier by 1
2023 * to catch up with it. If it's ahead and there was a remainder in the
2024 * tick division, the clock will slow down. Otherwise it will stay
2025 * ahead until the tick length changes to a non-divisible value.
2026 */
2027 tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0;
2028 mult += tk->ntp_err_mult;
2029
2030 timekeeping_apply_adjustment(tk, offset, mult - tk->tkr_mono.mult);
2031
2032 if (unlikely(tk->tkr_mono.clock->maxadj &&
2033 (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
2034 > tk->tkr_mono.clock->maxadj))) {
2035 printk_once(KERN_WARNING
2036 "Adjusting %s more than 11%% (%ld vs %ld)\n",
2037 tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
2038 (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
2039 }
2040
2041 /*
2042 * It may be possible that when we entered this function, xtime_nsec
2043 * was very small. Further, if we're slightly speeding the clocksource
2044 * in the code above, its possible the required corrective factor to
2045 * xtime_nsec could cause it to underflow.
2046 *
2047 * Now, since we have already accumulated the second and the NTP
2048 * subsystem has been notified via second_overflow(), we need to skip
2049 * the next update.
2050 */
2051 if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
2052 tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC <<
2053 tk->tkr_mono.shift;
2054 tk->xtime_sec--;
2055 tk->skip_second_overflow = 1;
2056 }
2057 }
2058
2059 /*
2060 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
2061 *
2062 * Helper function that accumulates the nsecs greater than a second
2063 * from the xtime_nsec field to the xtime_secs field.
2064 * It also calls into the NTP code to handle leapsecond processing.
2065 */
accumulate_nsecs_to_secs(struct timekeeper * tk)2066 static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
2067 {
2068 u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
2069 unsigned int clock_set = 0;
2070
2071 while (tk->tkr_mono.xtime_nsec >= nsecps) {
2072 int leap;
2073
2074 tk->tkr_mono.xtime_nsec -= nsecps;
2075 tk->xtime_sec++;
2076
2077 /*
2078 * Skip NTP update if this second was accumulated before,
2079 * i.e. xtime_nsec underflowed in timekeeping_adjust()
2080 */
2081 if (unlikely(tk->skip_second_overflow)) {
2082 tk->skip_second_overflow = 0;
2083 continue;
2084 }
2085
2086 /* Figure out if its a leap sec and apply if needed */
2087 leap = second_overflow(tk->xtime_sec);
2088 if (unlikely(leap)) {
2089 struct timespec64 ts;
2090
2091 tk->xtime_sec += leap;
2092
2093 ts.tv_sec = leap;
2094 ts.tv_nsec = 0;
2095 tk_set_wall_to_mono(tk,
2096 timespec64_sub(tk->wall_to_monotonic, ts));
2097
2098 __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
2099
2100 clock_set = TK_CLOCK_WAS_SET;
2101 }
2102 }
2103 return clock_set;
2104 }
2105
2106 /*
2107 * logarithmic_accumulation - shifted accumulation of cycles
2108 *
2109 * This functions accumulates a shifted interval of cycles into
2110 * a shifted interval nanoseconds. Allows for O(log) accumulation
2111 * loop.
2112 *
2113 * Returns the unconsumed cycles.
2114 */
logarithmic_accumulation(struct timekeeper * tk,u64 offset,u32 shift,unsigned int * clock_set)2115 static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2116 u32 shift, unsigned int *clock_set)
2117 {
2118 u64 interval = tk->cycle_interval << shift;
2119 u64 snsec_per_sec;
2120
2121 /* If the offset is smaller than a shifted interval, do nothing */
2122 if (offset < interval)
2123 return offset;
2124
2125 /* Accumulate one shifted interval */
2126 offset -= interval;
2127 tk->tkr_mono.cycle_last += interval;
2128 tk->tkr_raw.cycle_last += interval;
2129
2130 tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2131 *clock_set |= accumulate_nsecs_to_secs(tk);
2132
2133 /* Accumulate raw time */
2134 tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2135 snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2136 while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2137 tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2138 tk->raw_sec++;
2139 }
2140
2141 /* Accumulate error between NTP and clock interval */
2142 tk->ntp_error += tk->ntp_tick << shift;
2143 tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2144 (tk->ntp_error_shift + shift);
2145
2146 return offset;
2147 }
2148
2149 /*
2150 * timekeeping_advance - Updates the timekeeper to the current time and
2151 * current NTP tick length
2152 */
timekeeping_advance(enum timekeeping_adv_mode mode)2153 static bool timekeeping_advance(enum timekeeping_adv_mode mode)
2154 {
2155 struct timekeeper *real_tk = &tk_core.timekeeper;
2156 struct timekeeper *tk = &shadow_timekeeper;
2157 u64 offset;
2158 int shift = 0, maxshift;
2159 unsigned int clock_set = 0;
2160 unsigned long flags;
2161
2162 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2163
2164 /* Make sure we're fully resumed: */
2165 if (unlikely(timekeeping_suspended))
2166 goto out;
2167
2168 offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
2169 tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2170
2171 /* Check if there's really nothing to do */
2172 if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK)
2173 goto out;
2174
2175 /* Do some additional sanity checking */
2176 timekeeping_check_update(tk, offset);
2177
2178 /*
2179 * With NO_HZ we may have to accumulate many cycle_intervals
2180 * (think "ticks") worth of time at once. To do this efficiently,
2181 * we calculate the largest doubling multiple of cycle_intervals
2182 * that is smaller than the offset. We then accumulate that
2183 * chunk in one go, and then try to consume the next smaller
2184 * doubled multiple.
2185 */
2186 shift = ilog2(offset) - ilog2(tk->cycle_interval);
2187 shift = max(0, shift);
2188 /* Bound shift to one less than what overflows tick_length */
2189 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2190 shift = min(shift, maxshift);
2191 while (offset >= tk->cycle_interval) {
2192 offset = logarithmic_accumulation(tk, offset, shift,
2193 &clock_set);
2194 if (offset < tk->cycle_interval<<shift)
2195 shift--;
2196 }
2197
2198 /* Adjust the multiplier to correct NTP error */
2199 timekeeping_adjust(tk, offset);
2200
2201 /*
2202 * Finally, make sure that after the rounding
2203 * xtime_nsec isn't larger than NSEC_PER_SEC
2204 */
2205 clock_set |= accumulate_nsecs_to_secs(tk);
2206
2207 write_seqcount_begin(&tk_core.seq);
2208 /*
2209 * Update the real timekeeper.
2210 *
2211 * We could avoid this memcpy by switching pointers, but that
2212 * requires changes to all other timekeeper usage sites as
2213 * well, i.e. move the timekeeper pointer getter into the
2214 * spinlocked/seqcount protected sections. And we trade this
2215 * memcpy under the tk_core.seq against one before we start
2216 * updating.
2217 */
2218 timekeeping_update(tk, clock_set);
2219 memcpy(real_tk, tk, sizeof(*tk));
2220 /* The memcpy must come last. Do not put anything here! */
2221 write_seqcount_end(&tk_core.seq);
2222 out:
2223 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2224
2225 return !!clock_set;
2226 }
2227
2228 /**
2229 * update_wall_time - Uses the current clocksource to increment the wall time
2230 *
2231 */
update_wall_time(void)2232 void update_wall_time(void)
2233 {
2234 if (timekeeping_advance(TK_ADV_TICK))
2235 clock_was_set_delayed();
2236 }
2237
2238 /**
2239 * getboottime64 - Return the real time of system boot.
2240 * @ts: pointer to the timespec64 to be set
2241 *
2242 * Returns the wall-time of boot in a timespec64.
2243 *
2244 * This is based on the wall_to_monotonic offset and the total suspend
2245 * time. Calls to settimeofday will affect the value returned (which
2246 * basically means that however wrong your real time clock is at boot time,
2247 * you get the right time here).
2248 */
getboottime64(struct timespec64 * ts)2249 void getboottime64(struct timespec64 *ts)
2250 {
2251 struct timekeeper *tk = &tk_core.timekeeper;
2252 ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2253
2254 *ts = ktime_to_timespec64(t);
2255 }
2256 EXPORT_SYMBOL_GPL(getboottime64);
2257
ktime_get_coarse_real_ts64(struct timespec64 * ts)2258 void ktime_get_coarse_real_ts64(struct timespec64 *ts)
2259 {
2260 struct timekeeper *tk = &tk_core.timekeeper;
2261 unsigned int seq;
2262
2263 do {
2264 seq = read_seqcount_begin(&tk_core.seq);
2265
2266 *ts = tk_xtime(tk);
2267 } while (read_seqcount_retry(&tk_core.seq, seq));
2268 }
2269 EXPORT_SYMBOL(ktime_get_coarse_real_ts64);
2270
ktime_get_coarse_ts64(struct timespec64 * ts)2271 void ktime_get_coarse_ts64(struct timespec64 *ts)
2272 {
2273 struct timekeeper *tk = &tk_core.timekeeper;
2274 struct timespec64 now, mono;
2275 unsigned int seq;
2276
2277 do {
2278 seq = read_seqcount_begin(&tk_core.seq);
2279
2280 now = tk_xtime(tk);
2281 mono = tk->wall_to_monotonic;
2282 } while (read_seqcount_retry(&tk_core.seq, seq));
2283
2284 set_normalized_timespec64(ts, now.tv_sec + mono.tv_sec,
2285 now.tv_nsec + mono.tv_nsec);
2286 }
2287 EXPORT_SYMBOL(ktime_get_coarse_ts64);
2288
2289 /*
2290 * Must hold jiffies_lock
2291 */
do_timer(unsigned long ticks)2292 void do_timer(unsigned long ticks)
2293 {
2294 jiffies_64 += ticks;
2295 calc_global_load();
2296 }
2297
2298 /**
2299 * ktime_get_update_offsets_now - hrtimer helper
2300 * @cwsseq: pointer to check and store the clock was set sequence number
2301 * @offs_real: pointer to storage for monotonic -> realtime offset
2302 * @offs_boot: pointer to storage for monotonic -> boottime offset
2303 * @offs_tai: pointer to storage for monotonic -> clock tai offset
2304 *
2305 * Returns current monotonic time and updates the offsets if the
2306 * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2307 * different.
2308 *
2309 * Called from hrtimer_interrupt() or retrigger_next_event()
2310 */
ktime_get_update_offsets_now(unsigned int * cwsseq,ktime_t * offs_real,ktime_t * offs_boot,ktime_t * offs_tai)2311 ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2312 ktime_t *offs_boot, ktime_t *offs_tai)
2313 {
2314 struct timekeeper *tk = &tk_core.timekeeper;
2315 unsigned int seq;
2316 ktime_t base;
2317 u64 nsecs;
2318
2319 do {
2320 seq = read_seqcount_begin(&tk_core.seq);
2321
2322 base = tk->tkr_mono.base;
2323 nsecs = timekeeping_get_ns(&tk->tkr_mono);
2324 base = ktime_add_ns(base, nsecs);
2325
2326 if (*cwsseq != tk->clock_was_set_seq) {
2327 *cwsseq = tk->clock_was_set_seq;
2328 *offs_real = tk->offs_real;
2329 *offs_boot = tk->offs_boot;
2330 *offs_tai = tk->offs_tai;
2331 }
2332
2333 /* Handle leapsecond insertion adjustments */
2334 if (unlikely(base >= tk->next_leap_ktime))
2335 *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2336
2337 } while (read_seqcount_retry(&tk_core.seq, seq));
2338
2339 return base;
2340 }
2341
2342 /*
2343 * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2344 */
timekeeping_validate_timex(const struct __kernel_timex * txc)2345 static int timekeeping_validate_timex(const struct __kernel_timex *txc)
2346 {
2347 if (txc->modes & ADJ_ADJTIME) {
2348 /* singleshot must not be used with any other mode bits */
2349 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2350 return -EINVAL;
2351 if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2352 !capable(CAP_SYS_TIME))
2353 return -EPERM;
2354 } else {
2355 /* In order to modify anything, you gotta be super-user! */
2356 if (txc->modes && !capable(CAP_SYS_TIME))
2357 return -EPERM;
2358 /*
2359 * if the quartz is off by more than 10% then
2360 * something is VERY wrong!
2361 */
2362 if (txc->modes & ADJ_TICK &&
2363 (txc->tick < 900000/USER_HZ ||
2364 txc->tick > 1100000/USER_HZ))
2365 return -EINVAL;
2366 }
2367
2368 if (txc->modes & ADJ_SETOFFSET) {
2369 /* In order to inject time, you gotta be super-user! */
2370 if (!capable(CAP_SYS_TIME))
2371 return -EPERM;
2372
2373 /*
2374 * Validate if a timespec/timeval used to inject a time
2375 * offset is valid. Offsets can be positive or negative, so
2376 * we don't check tv_sec. The value of the timeval/timespec
2377 * is the sum of its fields,but *NOTE*:
2378 * The field tv_usec/tv_nsec must always be non-negative and
2379 * we can't have more nanoseconds/microseconds than a second.
2380 */
2381 if (txc->time.tv_usec < 0)
2382 return -EINVAL;
2383
2384 if (txc->modes & ADJ_NANO) {
2385 if (txc->time.tv_usec >= NSEC_PER_SEC)
2386 return -EINVAL;
2387 } else {
2388 if (txc->time.tv_usec >= USEC_PER_SEC)
2389 return -EINVAL;
2390 }
2391 }
2392
2393 /*
2394 * Check for potential multiplication overflows that can
2395 * only happen on 64-bit systems:
2396 */
2397 if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2398 if (LLONG_MIN / PPM_SCALE > txc->freq)
2399 return -EINVAL;
2400 if (LLONG_MAX / PPM_SCALE < txc->freq)
2401 return -EINVAL;
2402 }
2403
2404 return 0;
2405 }
2406
2407 /**
2408 * random_get_entropy_fallback - Returns the raw clock source value,
2409 * used by random.c for platforms with no valid random_get_entropy().
2410 */
random_get_entropy_fallback(void)2411 unsigned long random_get_entropy_fallback(void)
2412 {
2413 struct tk_read_base *tkr = &tk_core.timekeeper.tkr_mono;
2414 struct clocksource *clock = READ_ONCE(tkr->clock);
2415
2416 if (unlikely(timekeeping_suspended || !clock))
2417 return 0;
2418 return clock->read(clock);
2419 }
2420 EXPORT_SYMBOL_GPL(random_get_entropy_fallback);
2421
2422 /**
2423 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2424 */
do_adjtimex(struct __kernel_timex * txc)2425 int do_adjtimex(struct __kernel_timex *txc)
2426 {
2427 struct timekeeper *tk = &tk_core.timekeeper;
2428 struct audit_ntp_data ad;
2429 bool clock_set = false;
2430 struct timespec64 ts;
2431 unsigned long flags;
2432 s32 orig_tai, tai;
2433 int ret;
2434
2435 /* Validate the data before disabling interrupts */
2436 ret = timekeeping_validate_timex(txc);
2437 if (ret)
2438 return ret;
2439 add_device_randomness(txc, sizeof(*txc));
2440
2441 if (txc->modes & ADJ_SETOFFSET) {
2442 struct timespec64 delta;
2443 delta.tv_sec = txc->time.tv_sec;
2444 delta.tv_nsec = txc->time.tv_usec;
2445 if (!(txc->modes & ADJ_NANO))
2446 delta.tv_nsec *= 1000;
2447 ret = timekeeping_inject_offset(&delta);
2448 if (ret)
2449 return ret;
2450
2451 audit_tk_injoffset(delta);
2452 }
2453
2454 audit_ntp_init(&ad);
2455
2456 ktime_get_real_ts64(&ts);
2457 add_device_randomness(&ts, sizeof(ts));
2458
2459 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2460 write_seqcount_begin(&tk_core.seq);
2461
2462 orig_tai = tai = tk->tai_offset;
2463 ret = __do_adjtimex(txc, &ts, &tai, &ad);
2464
2465 if (tai != orig_tai) {
2466 __timekeeping_set_tai_offset(tk, tai);
2467 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2468 clock_set = true;
2469 }
2470 tk_update_leap_state(tk);
2471
2472 write_seqcount_end(&tk_core.seq);
2473 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2474
2475 audit_ntp_log(&ad);
2476
2477 /* Update the multiplier immediately if frequency was set directly */
2478 if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
2479 clock_set |= timekeeping_advance(TK_ADV_FREQ);
2480
2481 if (clock_set)
2482 clock_was_set(CLOCK_REALTIME);
2483
2484 ntp_notify_cmos_timer();
2485
2486 return ret;
2487 }
2488
2489 #ifdef CONFIG_NTP_PPS
2490 /**
2491 * hardpps() - Accessor function to NTP __hardpps function
2492 */
hardpps(const struct timespec64 * phase_ts,const struct timespec64 * raw_ts)2493 void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2494 {
2495 unsigned long flags;
2496
2497 raw_spin_lock_irqsave(&timekeeper_lock, flags);
2498 write_seqcount_begin(&tk_core.seq);
2499
2500 __hardpps(phase_ts, raw_ts);
2501
2502 write_seqcount_end(&tk_core.seq);
2503 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2504 }
2505 EXPORT_SYMBOL(hardpps);
2506 #endif /* CONFIG_NTP_PPS */
2507