root/kernel/time/timekeeping.c

DEFINITIONS

1. dummy_clock_read
2. tk_normalize_xtime
3. tk_xtime
4. tk_set_xtime
5. tk_xtime_add
6. tk_set_wall_to_mono
7. tk_update_sleep_time
8. tk_clock_read
9. timekeeping_check_update
10. timekeeping_get_delta
11. timekeeping_check_update
12. timekeeping_get_delta
13. tk_setup_internals
14. default_arch_gettimeoffset
15. arch_gettimeoffset
16. timekeeping_delta_to_ns
17. timekeeping_get_ns
18. timekeeping_cycles_to_ns
19. update_fast_timekeeper
20. __ktime_get_fast_ns
21. ktime_get_mono_fast_ns
22. ktime_get_raw_fast_ns
23. ktime_get_boot_fast_ns
24. __ktime_get_real_fast_ns
25. ktime_get_real_fast_ns
26. halt_fast_timekeeper
27. update_pvclock_gtod
28. pvclock_gtod_register_notifier
29. pvclock_gtod_unregister_notifier
30. tk_update_leap_state
31. tk_update_ktime_data
32. timekeeping_update
33. timekeeping_forward_now
34. ktime_get_real_ts64
35. ktime_get
36. ktime_get_resolution_ns
37. ktime_get_with_offset
38. ktime_get_coarse_with_offset
39. ktime_mono_to_any
40. ktime_get_raw
41. ktime_get_ts64
42. ktime_get_seconds
43. ktime_get_real_seconds
44. __ktime_get_real_seconds
45. ktime_get_snapshot
46. scale64_check_overflow
47. adjust_historical_crosststamp
48. cycle_between
49. get_device_system_crosststamp
50. do_settimeofday64
51. timekeeping_inject_offset
52. timekeeping_warp_clock
53. __timekeeping_set_tai_offset
54. change_clocksource
55. timekeeping_notify
56. ktime_get_raw_ts64
57. timekeeping_valid_for_hres
58. timekeeping_max_deferment
59. read_persistent_clock64
60. read_persistent_wall_and_boot_offset
61. timekeeping_init
62. __timekeeping_inject_sleeptime
63. timekeeping_rtc_skipresume
64. timekeeping_rtc_skipsuspend
65. timekeeping_inject_sleeptime64
66. timekeeping_resume
67. timekeeping_suspend
68. timekeeping_init_ops
69. timekeeping_apply_adjustment
70. timekeeping_adjust
71. accumulate_nsecs_to_secs
72. logarithmic_accumulation
73. timekeeping_advance
74. update_wall_time
75. getboottime64
76. ktime_get_coarse_real_ts64
77. ktime_get_coarse_ts64
78. do_timer
79. ktime_get_update_offsets_now
80. timekeeping_validate_timex
81. do_adjtimex
82. hardpps
83. xtime_update

   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/tick.h>
  21 #include <linux/stop_machine.h>
  22 #include <linux/pvclock_gtod.h>
  23 #include <linux/compiler.h>
  24 #include <linux/audit.h>
  25 
  26 #include "tick-internal.h"
  27 #include "ntp_internal.h"
  28 #include "timekeeping_internal.h"
  29 
  30 #define TK_CLEAR_NTP            (1 << 0)
  31 #define TK_MIRROR               (1 << 1)
  32 #define TK_CLOCK_WAS_SET        (1 << 2)
  33 
  34 enum timekeeping_adv_mode {
  35         /* Update timekeeper when a tick has passed */
  36         TK_ADV_TICK,
  37 
  38         /* Update timekeeper on a direct frequency change */
  39         TK_ADV_FREQ
  40 };
  41 
  42 /*
  43  * The most important data for readout fits into a single 64 byte
  44  * cache line.
  45  */
  46 static struct {
  47         seqcount_t              seq;
  48         struct timekeeper       timekeeper;
  49 } tk_core ____cacheline_aligned = {
  50         .seq = SEQCNT_ZERO(tk_core.seq),
  51 };
  52 
  53 static DEFINE_RAW_SPINLOCK(timekeeper_lock);
  54 static struct timekeeper shadow_timekeeper;
  55 
  56 /**
  57  * struct tk_fast - NMI safe timekeeper
  58  * @seq:        Sequence counter for protecting updates. The lowest bit
  59  *              is the index for the tk_read_base array
  60  * @base:       tk_read_base array. Access is indexed by the lowest bit of
  61  *              @seq.
  62  *
  63  * See @update_fast_timekeeper() below.
  64  */
  65 struct tk_fast {
  66         seqcount_t              seq;
  67         struct tk_read_base     base[2];
  68 };
  69 
  70 /* Suspend-time cycles value for halted fast timekeeper. */
  71 static u64 cycles_at_suspend;
  72 
  73 static u64 dummy_clock_read(struct clocksource *cs)
  74 {
  75         return cycles_at_suspend;
  76 }
  77 
  78 static struct clocksource dummy_clock = {
  79         .read = dummy_clock_read,
  80 };
  81 
  82 static struct tk_fast tk_fast_mono ____cacheline_aligned = {
  83         .base[0] = { .clock = &dummy_clock, },
  84         .base[1] = { .clock = &dummy_clock, },
  85 };
  86 
  87 static struct tk_fast tk_fast_raw  ____cacheline_aligned = {
  88         .base[0] = { .clock = &dummy_clock, },
  89         .base[1] = { .clock = &dummy_clock, },
  90 };
  91 
  92 /* flag for if timekeeping is suspended */
  93 int __read_mostly timekeeping_suspended;
  94 
  95 static inline void tk_normalize_xtime(struct timekeeper *tk)
  96 {
  97         while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) {
  98                 tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
  99                 tk->xtime_sec++;
 100         }
 101         while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) {
 102                 tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
 103                 tk->raw_sec++;
 104         }
 105 }
 106 
 107 static inline struct timespec64 tk_xtime(const struct timekeeper *tk)
 108 {
 109         struct timespec64 ts;
 110 
 111         ts.tv_sec = tk->xtime_sec;
 112         ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
 113         return ts;
 114 }
 115 
 116 static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts)
 117 {
 118         tk->xtime_sec = ts->tv_sec;
 119         tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift;
 120 }
 121 
 122 static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts)
 123 {
 124         tk->xtime_sec += ts->tv_sec;
 125         tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift;
 126         tk_normalize_xtime(tk);
 127 }
 128 
 129 static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
 130 {
 131         struct timespec64 tmp;
 132 
 133         /*
 134          * Verify consistency of: offset_real = -wall_to_monotonic
 135          * before modifying anything
 136          */
 137         set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec,
 138                                         -tk->wall_to_monotonic.tv_nsec);
 139         WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp));
 140         tk->wall_to_monotonic = wtm;
 141         set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
 142         tk->offs_real = timespec64_to_ktime(tmp);
 143         tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
 144 }
 145 
 146 static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
 147 {
 148         tk->offs_boot = ktime_add(tk->offs_boot, delta);
 149         /*
 150          * Timespec representation for VDSO update to avoid 64bit division
 151          * on every update.
 152          */
 153         tk->monotonic_to_boot = ktime_to_timespec64(tk->offs_boot);
 154 }
 155 
 156 /*
 157  * tk_clock_read - atomic clocksource read() helper
 158  *
 159  * This helper is necessary to use in the read paths because, while the
 160  * seqlock ensures we don't return a bad value while structures are updated,
 161  * it doesn't protect from potential crashes. There is the possibility that
 162  * the tkr's clocksource may change between the read reference, and the
 163  * clock reference passed to the read function.  This can cause crashes if
 164  * the wrong clocksource is passed to the wrong read function.
 165  * This isn't necessary to use when holding the timekeeper_lock or doing
 166  * a read of the fast-timekeeper tkrs (which is protected by its own locking
 167  * and update logic).
 168  */
 169 static inline u64 tk_clock_read(const struct tk_read_base *tkr)
 170 {
 171         struct clocksource *clock = READ_ONCE(tkr->clock);
 172 
 173         return clock->read(clock);
 174 }
 175 
 176 #ifdef CONFIG_DEBUG_TIMEKEEPING
 177 #define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
 178 
 179 static void timekeeping_check_update(struct timekeeper *tk, u64 offset)
 180 {
 181 
 182         u64 max_cycles = tk->tkr_mono.clock->max_cycles;
 183         const char *name = tk->tkr_mono.clock->name;
 184 
 185         if (offset > max_cycles) {
 186                 printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
 187                                 offset, name, max_cycles);
 188                 printk_deferred("         timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
 189         } else {
 190                 if (offset > (max_cycles >> 1)) {
 191                         printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n",
 192                                         offset, name, max_cycles >> 1);
 193                         printk_deferred("      timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
 194                 }
 195         }
 196 
 197         if (tk->underflow_seen) {
 198                 if (jiffies - tk->last_warning > WARNING_FREQ) {
 199                         printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
 200                         printk_deferred("         Please report this, consider using a different clocksource, if possible.\n");
 201                         printk_deferred("         Your kernel is probably still fine.\n");
 202                         tk->last_warning = jiffies;
 203                 }
 204                 tk->underflow_seen = 0;
 205         }
 206 
 207         if (tk->overflow_seen) {
 208                 if (jiffies - tk->last_warning > WARNING_FREQ) {
 209                         printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
 210                         printk_deferred("         Please report this, consider using a different clocksource, if possible.\n");
 211                         printk_deferred("         Your kernel is probably still fine.\n");
 212                         tk->last_warning = jiffies;
 213                 }
 214                 tk->overflow_seen = 0;
 215         }
 216 }
 217 
 218 static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
 219 {
 220         struct timekeeper *tk = &tk_core.timekeeper;
 221         u64 now, last, mask, max, delta;
 222         unsigned int seq;
 223 
 224         /*
 225          * Since we're called holding a seqlock, the data may shift
 226          * under us while we're doing the calculation. This can cause
 227          * false positives, since we'd note a problem but throw the
 228          * results away. So nest another seqlock here to atomically
 229          * grab the points we are checking with.
 230          */
 231         do {
 232                 seq = read_seqcount_begin(&tk_core.seq);
 233                 now = tk_clock_read(tkr);
 234                 last = tkr->cycle_last;
 235                 mask = tkr->mask;
 236                 max = tkr->clock->max_cycles;
 237         } while (read_seqcount_retry(&tk_core.seq, seq));
 238 
 239         delta = clocksource_delta(now, last, mask);
 240 
 241         /*
 242          * Try to catch underflows by checking if we are seeing small
 243          * mask-relative negative values.
 244          */
 245         if (unlikely((~delta & mask) < (mask >> 3))) {
 246                 tk->underflow_seen = 1;
 247                 delta = 0;
 248         }
 249 
 250         /* Cap delta value to the max_cycles values to avoid mult overflows */
 251         if (unlikely(delta > max)) {
 252                 tk->overflow_seen = 1;
 253                 delta = tkr->clock->max_cycles;
 254         }
 255 
 256         return delta;
 257 }
 258 #else
 259 static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset)
 260 {
 261 }
 262 static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr)
 263 {
 264         u64 cycle_now, delta;
 265 
 266         /* read clocksource */
 267         cycle_now = tk_clock_read(tkr);
 268 
 269         /* calculate the delta since the last update_wall_time */
 270         delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
 271 
 272         return delta;
 273 }
 274 #endif
 275 
 276 /**
 277  * tk_setup_internals - Set up internals to use clocksource clock.
 278  *
 279  * @tk:         The target timekeeper to setup.
 280  * @clock:              Pointer to clocksource.
 281  *
 282  * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
 283  * pair and interval request.
 284  *
 285  * Unless you're the timekeeping code, you should not be using this!
 286  */
 287 static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
 288 {
 289         u64 interval;
 290         u64 tmp, ntpinterval;
 291         struct clocksource *old_clock;
 292 
 293         ++tk->cs_was_changed_seq;
 294         old_clock = tk->tkr_mono.clock;
 295         tk->tkr_mono.clock = clock;
 296         tk->tkr_mono.mask = clock->mask;
 297         tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono);
 298 
 299         tk->tkr_raw.clock = clock;
 300         tk->tkr_raw.mask = clock->mask;
 301         tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
 302 
 303         /* Do the ns -> cycle conversion first, using original mult */
 304         tmp = NTP_INTERVAL_LENGTH;
 305         tmp <<= clock->shift;
 306         ntpinterval = tmp;
 307         tmp += clock->mult/2;
 308         do_div(tmp, clock->mult);
 309         if (tmp == 0)
 310                 tmp = 1;
 311 
 312         interval = (u64) tmp;
 313         tk->cycle_interval = interval;
 314 
 315         /* Go back from cycles -> shifted ns */
 316         tk->xtime_interval = interval * clock->mult;
 317         tk->xtime_remainder = ntpinterval - tk->xtime_interval;
 318         tk->raw_interval = interval * clock->mult;
 319 
 320          /* if changing clocks, convert xtime_nsec shift units */
 321         if (old_clock) {
 322                 int shift_change = clock->shift - old_clock->shift;
 323                 if (shift_change < 0) {
 324                         tk->tkr_mono.xtime_nsec >>= -shift_change;
 325                         tk->tkr_raw.xtime_nsec >>= -shift_change;
 326                 } else {
 327                         tk->tkr_mono.xtime_nsec <<= shift_change;
 328                         tk->tkr_raw.xtime_nsec <<= shift_change;
 329                 }
 330         }
 331 
 332         tk->tkr_mono.shift = clock->shift;
 333         tk->tkr_raw.shift = clock->shift;
 334 
 335         tk->ntp_error = 0;
 336         tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
 337         tk->ntp_tick = ntpinterval << tk->ntp_error_shift;
 338 
 339         /*
 340          * The timekeeper keeps its own mult values for the currently
 341          * active clocksource. These value will be adjusted via NTP
 342          * to counteract clock drifting.
 343          */
 344         tk->tkr_mono.mult = clock->mult;
 345         tk->tkr_raw.mult = clock->mult;
 346         tk->ntp_err_mult = 0;
 347         tk->skip_second_overflow = 0;
 348 }
 349 
 350 /* Timekeeper helper functions. */
 351 
 352 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
 353 static u32 default_arch_gettimeoffset(void) { return 0; }
 354 u32 (*arch_gettimeoffset)(void) = default_arch_gettimeoffset;
 355 #else
 356 static inline u32 arch_gettimeoffset(void) { return 0; }
 357 #endif
 358 
 359 static inline u64 timekeeping_delta_to_ns(const struct tk_read_base *tkr, u64 delta)
 360 {
 361         u64 nsec;
 362 
 363         nsec = delta * tkr->mult + tkr->xtime_nsec;
 364         nsec >>= tkr->shift;
 365 
 366         /* If arch requires, add in get_arch_timeoffset() */
 367         return nsec + arch_gettimeoffset();
 368 }
 369 
 370 static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr)
 371 {
 372         u64 delta;
 373 
 374         delta = timekeeping_get_delta(tkr);
 375         return timekeeping_delta_to_ns(tkr, delta);
 376 }
 377 
 378 static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles)
 379 {
 380         u64 delta;
 381 
 382         /* calculate the delta since the last update_wall_time */
 383         delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
 384         return timekeeping_delta_to_ns(tkr, delta);
 385 }
 386 
 387 /**
 388  * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
 389  * @tkr: Timekeeping readout base from which we take the update
 390  *
 391  * We want to use this from any context including NMI and tracing /
 392  * instrumenting the timekeeping code itself.
 393  *
 394  * Employ the latch technique; see @raw_write_seqcount_latch.
 395  *
 396  * So if a NMI hits the update of base[0] then it will use base[1]
 397  * which is still consistent. In the worst case this can result is a
 398  * slightly wrong timestamp (a few nanoseconds). See
 399  * @ktime_get_mono_fast_ns.
 400  */
 401 static void update_fast_timekeeper(const struct tk_read_base *tkr,
 402                                    struct tk_fast *tkf)
 403 {
 404         struct tk_read_base *base = tkf->base;
 405 
 406         /* Force readers off to base[1] */
 407         raw_write_seqcount_latch(&tkf->seq);
 408 
 409         /* Update base[0] */
 410         memcpy(base, tkr, sizeof(*base));
 411 
 412         /* Force readers back to base[0] */
 413         raw_write_seqcount_latch(&tkf->seq);
 414 
 415         /* Update base[1] */
 416         memcpy(base + 1, base, sizeof(*base));
 417 }
 418 
 419 /**
 420  * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
 421  *
 422  * This timestamp is not guaranteed to be monotonic across an update.
 423  * The timestamp is calculated by:
 424  *
 425  *      now = base_mono + clock_delta * slope
 426  *
 427  * So if the update lowers the slope, readers who are forced to the
 428  * not yet updated second array are still using the old steeper slope.
 429  *
 430  * tmono
 431  * ^
 432  * |    o  n
 433  * |   o n
 434  * |  u
 435  * | o
 436  * |o
 437  * |12345678---> reader order
 438  *
 439  * o = old slope
 440  * u = update
 441  * n = new slope
 442  *
 443  * So reader 6 will observe time going backwards versus reader 5.
 444  *
 445  * While other CPUs are likely to be able observe that, the only way
 446  * for a CPU local observation is when an NMI hits in the middle of
 447  * the update. Timestamps taken from that NMI context might be ahead
 448  * of the following timestamps. Callers need to be aware of that and
 449  * deal with it.
 450  */
 451 static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
 452 {
 453         struct tk_read_base *tkr;
 454         unsigned int seq;
 455         u64 now;
 456 
 457         do {
 458                 seq = raw_read_seqcount_latch(&tkf->seq);
 459                 tkr = tkf->base + (seq & 0x01);
 460                 now = ktime_to_ns(tkr->base);
 461 
 462                 now += timekeeping_delta_to_ns(tkr,
 463                                 clocksource_delta(
 464                                         tk_clock_read(tkr),
 465                                         tkr->cycle_last,
 466                                         tkr->mask));
 467         } while (read_seqcount_retry(&tkf->seq, seq));
 468 
 469         return now;
 470 }
 471 
 472 u64 ktime_get_mono_fast_ns(void)
 473 {
 474         return __ktime_get_fast_ns(&tk_fast_mono);
 475 }
 476 EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
 477 
 478 u64 ktime_get_raw_fast_ns(void)
 479 {
 480         return __ktime_get_fast_ns(&tk_fast_raw);
 481 }
 482 EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
 483 
 484 /**
 485  * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
 486  *
 487  * To keep it NMI safe since we're accessing from tracing, we're not using a
 488  * separate timekeeper with updates to monotonic clock and boot offset
 489  * protected with seqlocks. This has the following minor side effects:
 490  *
 491  * (1) Its possible that a timestamp be taken after the boot offset is updated
 492  * but before the timekeeper is updated. If this happens, the new boot offset
 493  * is added to the old timekeeping making the clock appear to update slightly
 494  * earlier:
 495  *    CPU 0                                        CPU 1
 496  *    timekeeping_inject_sleeptime64()
 497  *    __timekeeping_inject_sleeptime(tk, delta);
 498  *                                                 timestamp();
 499  *    timekeeping_update(tk, TK_CLEAR_NTP...);
 500  *
 501  * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
 502  * partially updated.  Since the tk->offs_boot update is a rare event, this
 503  * should be a rare occurrence which postprocessing should be able to handle.
 504  */
 505 u64 notrace ktime_get_boot_fast_ns(void)
 506 {
 507         struct timekeeper *tk = &tk_core.timekeeper;
 508 
 509         return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot));
 510 }
 511 EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
 512 
 513 
 514 /*
 515  * See comment for __ktime_get_fast_ns() vs. timestamp ordering
 516  */
 517 static __always_inline u64 __ktime_get_real_fast_ns(struct tk_fast *tkf)
 518 {
 519         struct tk_read_base *tkr;
 520         unsigned int seq;
 521         u64 now;
 522 
 523         do {
 524                 seq = raw_read_seqcount_latch(&tkf->seq);
 525                 tkr = tkf->base + (seq & 0x01);
 526                 now = ktime_to_ns(tkr->base_real);
 527 
 528                 now += timekeeping_delta_to_ns(tkr,
 529                                 clocksource_delta(
 530                                         tk_clock_read(tkr),
 531                                         tkr->cycle_last,
 532                                         tkr->mask));
 533         } while (read_seqcount_retry(&tkf->seq, seq));
 534 
 535         return now;
 536 }
 537 
 538 /**
 539  * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime.
 540  */
 541 u64 ktime_get_real_fast_ns(void)
 542 {
 543         return __ktime_get_real_fast_ns(&tk_fast_mono);
 544 }
 545 EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns);
 546 
 547 /**
 548  * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
 549  * @tk: Timekeeper to snapshot.
 550  *
 551  * It generally is unsafe to access the clocksource after timekeeping has been
 552  * suspended, so take a snapshot of the readout base of @tk and use it as the
 553  * fast timekeeper's readout base while suspended.  It will return the same
 554  * number of cycles every time until timekeeping is resumed at which time the
 555  * proper readout base for the fast timekeeper will be restored automatically.
 556  */
 557 static void halt_fast_timekeeper(const struct timekeeper *tk)
 558 {
 559         static struct tk_read_base tkr_dummy;
 560         const struct tk_read_base *tkr = &tk->tkr_mono;
 561 
 562         memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
 563         cycles_at_suspend = tk_clock_read(tkr);
 564         tkr_dummy.clock = &dummy_clock;
 565         tkr_dummy.base_real = tkr->base + tk->offs_real;
 566         update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
 567 
 568         tkr = &tk->tkr_raw;
 569         memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
 570         tkr_dummy.clock = &dummy_clock;
 571         update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
 572 }
 573 
 574 static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
 575 
 576 static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
 577 {
 578         raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
 579 }
 580 
 581 /**
 582  * pvclock_gtod_register_notifier - register a pvclock timedata update listener
 583  */
 584 int pvclock_gtod_register_notifier(struct notifier_block *nb)
 585 {
 586         struct timekeeper *tk = &tk_core.timekeeper;
 587         unsigned long flags;
 588         int ret;
 589 
 590         raw_spin_lock_irqsave(&timekeeper_lock, flags);
 591         ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
 592         update_pvclock_gtod(tk, true);
 593         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 594 
 595         return ret;
 596 }
 597 EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
 598 
 599 /**
 600  * pvclock_gtod_unregister_notifier - unregister a pvclock
 601  * timedata update listener
 602  */
 603 int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
 604 {
 605         unsigned long flags;
 606         int ret;
 607 
 608         raw_spin_lock_irqsave(&timekeeper_lock, flags);
 609         ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
 610         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 611 
 612         return ret;
 613 }
 614 EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
 615 
 616 /*
 617  * tk_update_leap_state - helper to update the next_leap_ktime
 618  */
 619 static inline void tk_update_leap_state(struct timekeeper *tk)
 620 {
 621         tk->next_leap_ktime = ntp_get_next_leap();
 622         if (tk->next_leap_ktime != KTIME_MAX)
 623                 /* Convert to monotonic time */
 624                 tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
 625 }
 626 
 627 /*
 628  * Update the ktime_t based scalar nsec members of the timekeeper
 629  */
 630 static inline void tk_update_ktime_data(struct timekeeper *tk)
 631 {
 632         u64 seconds;
 633         u32 nsec;
 634 
 635         /*
 636          * The xtime based monotonic readout is:
 637          *      nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
 638          * The ktime based monotonic readout is:
 639          *      nsec = base_mono + now();
 640          * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
 641          */
 642         seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
 643         nsec = (u32) tk->wall_to_monotonic.tv_nsec;
 644         tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
 645 
 646         /*
 647          * The sum of the nanoseconds portions of xtime and
 648          * wall_to_monotonic can be greater/equal one second. Take
 649          * this into account before updating tk->ktime_sec.
 650          */
 651         nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
 652         if (nsec >= NSEC_PER_SEC)
 653                 seconds++;
 654         tk->ktime_sec = seconds;
 655 
 656         /* Update the monotonic raw base */
 657         tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
 658 }
 659 
 660 /* must hold timekeeper_lock */
 661 static void timekeeping_update(struct timekeeper *tk, unsigned int action)
 662 {
 663         if (action & TK_CLEAR_NTP) {
 664                 tk->ntp_error = 0;
 665                 ntp_clear();
 666         }
 667 
 668         tk_update_leap_state(tk);
 669         tk_update_ktime_data(tk);
 670 
 671         update_vsyscall(tk);
 672         update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
 673 
 674         tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real;
 675         update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
 676         update_fast_timekeeper(&tk->tkr_raw,  &tk_fast_raw);
 677 
 678         if (action & TK_CLOCK_WAS_SET)
 679                 tk->clock_was_set_seq++;
 680         /*
 681          * The mirroring of the data to the shadow-timekeeper needs
 682          * to happen last here to ensure we don't over-write the
 683          * timekeeper structure on the next update with stale data
 684          */
 685         if (action & TK_MIRROR)
 686                 memcpy(&shadow_timekeeper, &tk_core.timekeeper,
 687                        sizeof(tk_core.timekeeper));
 688 }
 689 
 690 /**
 691  * timekeeping_forward_now - update clock to the current time
 692  *
 693  * Forward the current clock to update its state since the last call to
 694  * update_wall_time(). This is useful before significant clock changes,
 695  * as it avoids having to deal with this time offset explicitly.
 696  */
 697 static void timekeeping_forward_now(struct timekeeper *tk)
 698 {
 699         u64 cycle_now, delta;
 700 
 701         cycle_now = tk_clock_read(&tk->tkr_mono);
 702         delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
 703         tk->tkr_mono.cycle_last = cycle_now;
 704         tk->tkr_raw.cycle_last  = cycle_now;
 705 
 706         tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult;
 707 
 708         /* If arch requires, add in get_arch_timeoffset() */
 709         tk->tkr_mono.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_mono.shift;
 710 
 711 
 712         tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
 713 
 714         /* If arch requires, add in get_arch_timeoffset() */
 715         tk->tkr_raw.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_raw.shift;
 716 
 717         tk_normalize_xtime(tk);
 718 }
 719 
 720 /**
 721  * ktime_get_real_ts64 - Returns the time of day in a timespec64.
 722  * @ts:         pointer to the timespec to be set
 723  *
 724  * Returns the time of day in a timespec64 (WARN if suspended).
 725  */
 726 void ktime_get_real_ts64(struct timespec64 *ts)
 727 {
 728         struct timekeeper *tk = &tk_core.timekeeper;
 729         unsigned int seq;
 730         u64 nsecs;
 731 
 732         WARN_ON(timekeeping_suspended);
 733 
 734         do {
 735                 seq = read_seqcount_begin(&tk_core.seq);
 736 
 737                 ts->tv_sec = tk->xtime_sec;
 738                 nsecs = timekeeping_get_ns(&tk->tkr_mono);
 739 
 740         } while (read_seqcount_retry(&tk_core.seq, seq));
 741 
 742         ts->tv_nsec = 0;
 743         timespec64_add_ns(ts, nsecs);
 744 }
 745 EXPORT_SYMBOL(ktime_get_real_ts64);
 746 
 747 ktime_t ktime_get(void)
 748 {
 749         struct timekeeper *tk = &tk_core.timekeeper;
 750         unsigned int seq;
 751         ktime_t base;
 752         u64 nsecs;
 753 
 754         WARN_ON(timekeeping_suspended);
 755 
 756         do {
 757                 seq = read_seqcount_begin(&tk_core.seq);
 758                 base = tk->tkr_mono.base;
 759                 nsecs = timekeeping_get_ns(&tk->tkr_mono);
 760 
 761         } while (read_seqcount_retry(&tk_core.seq, seq));
 762 
 763         return ktime_add_ns(base, nsecs);
 764 }
 765 EXPORT_SYMBOL_GPL(ktime_get);
 766 
 767 u32 ktime_get_resolution_ns(void)
 768 {
 769         struct timekeeper *tk = &tk_core.timekeeper;
 770         unsigned int seq;
 771         u32 nsecs;
 772 
 773         WARN_ON(timekeeping_suspended);
 774 
 775         do {
 776                 seq = read_seqcount_begin(&tk_core.seq);
 777                 nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
 778         } while (read_seqcount_retry(&tk_core.seq, seq));
 779 
 780         return nsecs;
 781 }
 782 EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
 783 
 784 static ktime_t *offsets[TK_OFFS_MAX] = {
 785         [TK_OFFS_REAL]  = &tk_core.timekeeper.offs_real,
 786         [TK_OFFS_BOOT]  = &tk_core.timekeeper.offs_boot,
 787         [TK_OFFS_TAI]   = &tk_core.timekeeper.offs_tai,
 788 };
 789 
 790 ktime_t ktime_get_with_offset(enum tk_offsets offs)
 791 {
 792         struct timekeeper *tk = &tk_core.timekeeper;
 793         unsigned int seq;
 794         ktime_t base, *offset = offsets[offs];
 795         u64 nsecs;
 796 
 797         WARN_ON(timekeeping_suspended);
 798 
 799         do {
 800                 seq = read_seqcount_begin(&tk_core.seq);
 801                 base = ktime_add(tk->tkr_mono.base, *offset);
 802                 nsecs = timekeeping_get_ns(&tk->tkr_mono);
 803 
 804         } while (read_seqcount_retry(&tk_core.seq, seq));
 805 
 806         return ktime_add_ns(base, nsecs);
 807 
 808 }
 809 EXPORT_SYMBOL_GPL(ktime_get_with_offset);
 810 
 811 ktime_t ktime_get_coarse_with_offset(enum tk_offsets offs)
 812 {
 813         struct timekeeper *tk = &tk_core.timekeeper;
 814         unsigned int seq;
 815         ktime_t base, *offset = offsets[offs];
 816         u64 nsecs;
 817 
 818         WARN_ON(timekeeping_suspended);
 819 
 820         do {
 821                 seq = read_seqcount_begin(&tk_core.seq);
 822                 base = ktime_add(tk->tkr_mono.base, *offset);
 823                 nsecs = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
 824 
 825         } while (read_seqcount_retry(&tk_core.seq, seq));
 826 
 827         return ktime_add_ns(base, nsecs);
 828 }
 829 EXPORT_SYMBOL_GPL(ktime_get_coarse_with_offset);
 830 
 831 /**
 832  * ktime_mono_to_any() - convert mononotic time to any other time
 833  * @tmono:      time to convert.
 834  * @offs:       which offset to use
 835  */
 836 ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
 837 {
 838         ktime_t *offset = offsets[offs];
 839         unsigned int seq;
 840         ktime_t tconv;
 841 
 842         do {
 843                 seq = read_seqcount_begin(&tk_core.seq);
 844                 tconv = ktime_add(tmono, *offset);
 845         } while (read_seqcount_retry(&tk_core.seq, seq));
 846 
 847         return tconv;
 848 }
 849 EXPORT_SYMBOL_GPL(ktime_mono_to_any);
 850 
 851 /**
 852  * ktime_get_raw - Returns the raw monotonic time in ktime_t format
 853  */
 854 ktime_t ktime_get_raw(void)
 855 {
 856         struct timekeeper *tk = &tk_core.timekeeper;
 857         unsigned int seq;
 858         ktime_t base;
 859         u64 nsecs;
 860 
 861         do {
 862                 seq = read_seqcount_begin(&tk_core.seq);
 863                 base = tk->tkr_raw.base;
 864                 nsecs = timekeeping_get_ns(&tk->tkr_raw);
 865 
 866         } while (read_seqcount_retry(&tk_core.seq, seq));
 867 
 868         return ktime_add_ns(base, nsecs);
 869 }
 870 EXPORT_SYMBOL_GPL(ktime_get_raw);
 871 
 872 /**
 873  * ktime_get_ts64 - get the monotonic clock in timespec64 format
 874  * @ts:         pointer to timespec variable
 875  *
 876  * The function calculates the monotonic clock from the realtime
 877  * clock and the wall_to_monotonic offset and stores the result
 878  * in normalized timespec64 format in the variable pointed to by @ts.
 879  */
 880 void ktime_get_ts64(struct timespec64 *ts)
 881 {
 882         struct timekeeper *tk = &tk_core.timekeeper;
 883         struct timespec64 tomono;
 884         unsigned int seq;
 885         u64 nsec;
 886 
 887         WARN_ON(timekeeping_suspended);
 888 
 889         do {
 890                 seq = read_seqcount_begin(&tk_core.seq);
 891                 ts->tv_sec = tk->xtime_sec;
 892                 nsec = timekeeping_get_ns(&tk->tkr_mono);
 893                 tomono = tk->wall_to_monotonic;
 894 
 895         } while (read_seqcount_retry(&tk_core.seq, seq));
 896 
 897         ts->tv_sec += tomono.tv_sec;
 898         ts->tv_nsec = 0;
 899         timespec64_add_ns(ts, nsec + tomono.tv_nsec);
 900 }
 901 EXPORT_SYMBOL_GPL(ktime_get_ts64);
 902 
 903 /**
 904  * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
 905  *
 906  * Returns the seconds portion of CLOCK_MONOTONIC with a single non
 907  * serialized read. tk->ktime_sec is of type 'unsigned long' so this
 908  * works on both 32 and 64 bit systems. On 32 bit systems the readout
 909  * covers ~136 years of uptime which should be enough to prevent
 910  * premature wrap arounds.
 911  */
 912 time64_t ktime_get_seconds(void)
 913 {
 914         struct timekeeper *tk = &tk_core.timekeeper;
 915 
 916         WARN_ON(timekeeping_suspended);
 917         return tk->ktime_sec;
 918 }
 919 EXPORT_SYMBOL_GPL(ktime_get_seconds);
 920 
 921 /**
 922  * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
 923  *
 924  * Returns the wall clock seconds since 1970. This replaces the
 925  * get_seconds() interface which is not y2038 safe on 32bit systems.
 926  *
 927  * For 64bit systems the fast access to tk->xtime_sec is preserved. On
 928  * 32bit systems the access must be protected with the sequence
 929  * counter to provide "atomic" access to the 64bit tk->xtime_sec
 930  * value.
 931  */
 932 time64_t ktime_get_real_seconds(void)
 933 {
 934         struct timekeeper *tk = &tk_core.timekeeper;
 935         time64_t seconds;
 936         unsigned int seq;
 937 
 938         if (IS_ENABLED(CONFIG_64BIT))
 939                 return tk->xtime_sec;
 940 
 941         do {
 942                 seq = read_seqcount_begin(&tk_core.seq);
 943                 seconds = tk->xtime_sec;
 944 
 945         } while (read_seqcount_retry(&tk_core.seq, seq));
 946 
 947         return seconds;
 948 }
 949 EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
 950 
 951 /**
 952  * __ktime_get_real_seconds - The same as ktime_get_real_seconds
 953  * but without the sequence counter protect. This internal function
 954  * is called just when timekeeping lock is already held.
 955  */
 956 time64_t __ktime_get_real_seconds(void)
 957 {
 958         struct timekeeper *tk = &tk_core.timekeeper;
 959 
 960         return tk->xtime_sec;
 961 }
 962 
 963 /**
 964  * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter
 965  * @systime_snapshot:   pointer to struct receiving the system time snapshot
 966  */
 967 void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
 968 {
 969         struct timekeeper *tk = &tk_core.timekeeper;
 970         unsigned int seq;
 971         ktime_t base_raw;
 972         ktime_t base_real;
 973         u64 nsec_raw;
 974         u64 nsec_real;
 975         u64 now;
 976 
 977         WARN_ON_ONCE(timekeeping_suspended);
 978 
 979         do {
 980                 seq = read_seqcount_begin(&tk_core.seq);
 981                 now = tk_clock_read(&tk->tkr_mono);
 982                 systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
 983                 systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
 984                 base_real = ktime_add(tk->tkr_mono.base,
 985                                       tk_core.timekeeper.offs_real);
 986                 base_raw = tk->tkr_raw.base;
 987                 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
 988                 nsec_raw  = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
 989         } while (read_seqcount_retry(&tk_core.seq, seq));
 990 
 991         systime_snapshot->cycles = now;
 992         systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
 993         systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
 994 }
 995 EXPORT_SYMBOL_GPL(ktime_get_snapshot);
 996 
 997 /* Scale base by mult/div checking for overflow */
 998 static int scale64_check_overflow(u64 mult, u64 div, u64 *base)
 999 {
1000         u64 tmp, rem;
1001 
1002         tmp = div64_u64_rem(*base, div, &rem);
1003 
1004         if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) ||
1005             ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem)))
1006                 return -EOVERFLOW;
1007         tmp *= mult;
1008         rem *= mult;
1009 
1010         do_div(rem, div);
1011         *base = tmp + rem;
1012         return 0;
1013 }
1014 
1015 /**
1016  * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval
1017  * @history:                    Snapshot representing start of history
1018  * @partial_history_cycles:     Cycle offset into history (fractional part)
1019  * @total_history_cycles:       Total history length in cycles
1020  * @discontinuity:              True indicates clock was set on history period
1021  * @ts:                         Cross timestamp that should be adjusted using
1022  *      partial/total ratio
1023  *
1024  * Helper function used by get_device_system_crosststamp() to correct the
1025  * crosstimestamp corresponding to the start of the current interval to the
1026  * system counter value (timestamp point) provided by the driver. The
1027  * total_history_* quantities are the total history starting at the provided
1028  * reference point and ending at the start of the current interval. The cycle
1029  * count between the driver timestamp point and the start of the current
1030  * interval is partial_history_cycles.
1031  */
1032 static int adjust_historical_crosststamp(struct system_time_snapshot *history,
1033                                          u64 partial_history_cycles,
1034                                          u64 total_history_cycles,
1035                                          bool discontinuity,
1036                                          struct system_device_crosststamp *ts)
1037 {
1038         struct timekeeper *tk = &tk_core.timekeeper;
1039         u64 corr_raw, corr_real;
1040         bool interp_forward;
1041         int ret;
1042 
1043         if (total_history_cycles == 0 || partial_history_cycles == 0)
1044                 return 0;
1045 
1046         /* Interpolate shortest distance from beginning or end of history */
1047         interp_forward = partial_history_cycles > total_history_cycles / 2;
1048         partial_history_cycles = interp_forward ?
1049                 total_history_cycles - partial_history_cycles :
1050                 partial_history_cycles;
1051 
1052         /*
1053          * Scale the monotonic raw time delta by:
1054          *      partial_history_cycles / total_history_cycles
1055          */
1056         corr_raw = (u64)ktime_to_ns(
1057                 ktime_sub(ts->sys_monoraw, history->raw));
1058         ret = scale64_check_overflow(partial_history_cycles,
1059                                      total_history_cycles, &corr_raw);
1060         if (ret)
1061                 return ret;
1062 
1063         /*
1064          * If there is a discontinuity in the history, scale monotonic raw
1065          *      correction by:
1066          *      mult(real)/mult(raw) yielding the realtime correction
1067          * Otherwise, calculate the realtime correction similar to monotonic
1068          *      raw calculation
1069          */
1070         if (discontinuity) {
1071                 corr_real = mul_u64_u32_div
1072                         (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult);
1073         } else {
1074                 corr_real = (u64)ktime_to_ns(
1075                         ktime_sub(ts->sys_realtime, history->real));
1076                 ret = scale64_check_overflow(partial_history_cycles,
1077                                              total_history_cycles, &corr_real);
1078                 if (ret)
1079                         return ret;
1080         }
1081 
1082         /* Fixup monotonic raw and real time time values */
1083         if (interp_forward) {
1084                 ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw);
1085                 ts->sys_realtime = ktime_add_ns(history->real, corr_real);
1086         } else {
1087                 ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw);
1088                 ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real);
1089         }
1090 
1091         return 0;
1092 }
1093 
1094 /*
1095  * cycle_between - true if test occurs chronologically between before and after
1096  */
1097 static bool cycle_between(u64 before, u64 test, u64 after)
1098 {
1099         if (test > before && test < after)
1100                 return true;
1101         if (test < before && before > after)
1102                 return true;
1103         return false;
1104 }
1105 
1106 /**
1107  * get_device_system_crosststamp - Synchronously capture system/device timestamp
1108  * @get_time_fn:        Callback to get simultaneous device time and
1109  *      system counter from the device driver
1110  * @ctx:                Context passed to get_time_fn()
1111  * @history_begin:      Historical reference point used to interpolate system
1112  *      time when counter provided by the driver is before the current interval
1113  * @xtstamp:            Receives simultaneously captured system and device time
1114  *
1115  * Reads a timestamp from a device and correlates it to system time
1116  */
1117 int get_device_system_crosststamp(int (*get_time_fn)
1118                                   (ktime_t *device_time,
1119                                    struct system_counterval_t *sys_counterval,
1120                                    void *ctx),
1121                                   void *ctx,
1122                                   struct system_time_snapshot *history_begin,
1123                                   struct system_device_crosststamp *xtstamp)
1124 {
1125         struct system_counterval_t system_counterval;
1126         struct timekeeper *tk = &tk_core.timekeeper;
1127         u64 cycles, now, interval_start;
1128         unsigned int clock_was_set_seq = 0;
1129         ktime_t base_real, base_raw;
1130         u64 nsec_real, nsec_raw;
1131         u8 cs_was_changed_seq;
1132         unsigned int seq;
1133         bool do_interp;
1134         int ret;
1135 
1136         do {
1137                 seq = read_seqcount_begin(&tk_core.seq);
1138                 /*
1139                  * Try to synchronously capture device time and a system
1140                  * counter value calling back into the device driver
1141                  */
1142                 ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);
1143                 if (ret)
1144                         return ret;
1145 
1146                 /*
1147                  * Verify that the clocksource associated with the captured
1148                  * system counter value is the same as the currently installed
1149                  * timekeeper clocksource
1150                  */
1151                 if (tk->tkr_mono.clock != system_counterval.cs)
1152                         return -ENODEV;
1153                 cycles = system_counterval.cycles;
1154 
1155                 /*
1156                  * Check whether the system counter value provided by the
1157                  * device driver is on the current timekeeping interval.
1158                  */
1159                 now = tk_clock_read(&tk->tkr_mono);
1160                 interval_start = tk->tkr_mono.cycle_last;
1161                 if (!cycle_between(interval_start, cycles, now)) {
1162                         clock_was_set_seq = tk->clock_was_set_seq;
1163                         cs_was_changed_seq = tk->cs_was_changed_seq;
1164                         cycles = interval_start;
1165                         do_interp = true;
1166                 } else {
1167                         do_interp = false;
1168                 }
1169 
1170                 base_real = ktime_add(tk->tkr_mono.base,
1171                                       tk_core.timekeeper.offs_real);
1172                 base_raw = tk->tkr_raw.base;
1173 
1174                 nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono,
1175                                                      system_counterval.cycles);
1176                 nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw,
1177                                                     system_counterval.cycles);
1178         } while (read_seqcount_retry(&tk_core.seq, seq));
1179 
1180         xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real);
1181         xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw);
1182 
1183         /*
1184          * Interpolate if necessary, adjusting back from the start of the
1185          * current interval
1186          */
1187         if (do_interp) {
1188                 u64 partial_history_cycles, total_history_cycles;
1189                 bool discontinuity;
1190 
1191                 /*
1192                  * Check that the counter value occurs after the provided
1193                  * history reference and that the history doesn't cross a
1194                  * clocksource change
1195                  */
1196                 if (!history_begin ||
1197                     !cycle_between(history_begin->cycles,
1198                                    system_counterval.cycles, cycles) ||
1199                     history_begin->cs_was_changed_seq != cs_was_changed_seq)
1200                         return -EINVAL;
1201                 partial_history_cycles = cycles - system_counterval.cycles;
1202                 total_history_cycles = cycles - history_begin->cycles;
1203                 discontinuity =
1204                         history_begin->clock_was_set_seq != clock_was_set_seq;
1205 
1206                 ret = adjust_historical_crosststamp(history_begin,
1207                                                     partial_history_cycles,
1208                                                     total_history_cycles,
1209                                                     discontinuity, xtstamp);
1210                 if (ret)
1211                         return ret;
1212         }
1213 
1214         return 0;
1215 }
1216 EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
1217 
1218 /**
1219  * do_settimeofday64 - Sets the time of day.
1220  * @ts:     pointer to the timespec64 variable containing the new time
1221  *
1222  * Sets the time of day to the new time and update NTP and notify hrtimers
1223  */
1224 int do_settimeofday64(const struct timespec64 *ts)
1225 {
1226         struct timekeeper *tk = &tk_core.timekeeper;
1227         struct timespec64 ts_delta, xt;
1228         unsigned long flags;
1229         int ret = 0;
1230 
1231         if (!timespec64_valid_settod(ts))
1232                 return -EINVAL;
1233 
1234         raw_spin_lock_irqsave(&timekeeper_lock, flags);
1235         write_seqcount_begin(&tk_core.seq);
1236 
1237         timekeeping_forward_now(tk);
1238 
1239         xt = tk_xtime(tk);
1240         ts_delta.tv_sec = ts->tv_sec - xt.tv_sec;
1241         ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec;
1242 
1243         if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
1244                 ret = -EINVAL;
1245                 goto out;
1246         }
1247 
1248         tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
1249 
1250         tk_set_xtime(tk, ts);
1251 out:
1252         timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1253 
1254         write_seqcount_end(&tk_core.seq);
1255         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1256 
1257         /* signal hrtimers about time change */
1258         clock_was_set();
1259 
1260         if (!ret)
1261                 audit_tk_injoffset(ts_delta);
1262 
1263         return ret;
1264 }
1265 EXPORT_SYMBOL(do_settimeofday64);
1266 
1267 /**
1268  * timekeeping_inject_offset - Adds or subtracts from the current time.
1269  * @tv:         pointer to the timespec variable containing the offset
1270  *
1271  * Adds or subtracts an offset value from the current time.
1272  */
1273 static int timekeeping_inject_offset(const struct timespec64 *ts)
1274 {
1275         struct timekeeper *tk = &tk_core.timekeeper;
1276         unsigned long flags;
1277         struct timespec64 tmp;
1278         int ret = 0;
1279 
1280         if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
1281                 return -EINVAL;
1282 
1283         raw_spin_lock_irqsave(&timekeeper_lock, flags);
1284         write_seqcount_begin(&tk_core.seq);
1285 
1286         timekeeping_forward_now(tk);
1287 
1288         /* Make sure the proposed value is valid */
1289         tmp = timespec64_add(tk_xtime(tk), *ts);
1290         if (timespec64_compare(&tk->wall_to_monotonic, ts) > 0 ||
1291             !timespec64_valid_settod(&tmp)) {
1292                 ret = -EINVAL;
1293                 goto error;
1294         }
1295 
1296         tk_xtime_add(tk, ts);
1297         tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *ts));
1298 
1299 error: /* even if we error out, we forwarded the time, so call update */
1300         timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1301 
1302         write_seqcount_end(&tk_core.seq);
1303         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1304 
1305         /* signal hrtimers about time change */
1306         clock_was_set();
1307 
1308         return ret;
1309 }
1310 
1311 /*
1312  * Indicates if there is an offset between the system clock and the hardware
1313  * clock/persistent clock/rtc.
1314  */
1315 int persistent_clock_is_local;
1316 
1317 /*
1318  * Adjust the time obtained from the CMOS to be UTC time instead of
1319  * local time.
1320  *
1321  * This is ugly, but preferable to the alternatives.  Otherwise we
1322  * would either need to write a program to do it in /etc/rc (and risk
1323  * confusion if the program gets run more than once; it would also be
1324  * hard to make the program warp the clock precisely n hours)  or
1325  * compile in the timezone information into the kernel.  Bad, bad....
1326  *
1327  *                                              - TYT, 1992-01-01
1328  *
1329  * The best thing to do is to keep the CMOS clock in universal time (UTC)
1330  * as real UNIX machines always do it. This avoids all headaches about
1331  * daylight saving times and warping kernel clocks.
1332  */
1333 void timekeeping_warp_clock(void)
1334 {
1335         if (sys_tz.tz_minuteswest != 0) {
1336                 struct timespec64 adjust;
1337 
1338                 persistent_clock_is_local = 1;
1339                 adjust.tv_sec = sys_tz.tz_minuteswest * 60;
1340                 adjust.tv_nsec = 0;
1341                 timekeeping_inject_offset(&adjust);
1342         }
1343 }
1344 
1345 /**
1346  * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
1347  *
1348  */
1349 static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
1350 {
1351         tk->tai_offset = tai_offset;
1352         tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
1353 }
1354 
1355 /**
1356  * change_clocksource - Swaps clocksources if a new one is available
1357  *
1358  * Accumulates current time interval and initializes new clocksource
1359  */
1360 static int change_clocksource(void *data)
1361 {
1362         struct timekeeper *tk = &tk_core.timekeeper;
1363         struct clocksource *new, *old;
1364         unsigned long flags;
1365 
1366         new = (struct clocksource *) data;
1367 
1368         raw_spin_lock_irqsave(&timekeeper_lock, flags);
1369         write_seqcount_begin(&tk_core.seq);
1370 
1371         timekeeping_forward_now(tk);
1372         /*
1373          * If the cs is in module, get a module reference. Succeeds
1374          * for built-in code (owner == NULL) as well.
1375          */
1376         if (try_module_get(new->owner)) {
1377                 if (!new->enable || new->enable(new) == 0) {
1378                         old = tk->tkr_mono.clock;
1379                         tk_setup_internals(tk, new);
1380                         if (old->disable)
1381                                 old->disable(old);
1382                         module_put(old->owner);
1383                 } else {
1384                         module_put(new->owner);
1385                 }
1386         }
1387         timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1388 
1389         write_seqcount_end(&tk_core.seq);
1390         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1391 
1392         return 0;
1393 }
1394 
1395 /**
1396  * timekeeping_notify - Install a new clock source
1397  * @clock:              pointer to the clock source
1398  *
1399  * This function is called from clocksource.c after a new, better clock
1400  * source has been registered. The caller holds the clocksource_mutex.
1401  */
1402 int timekeeping_notify(struct clocksource *clock)
1403 {
1404         struct timekeeper *tk = &tk_core.timekeeper;
1405 
1406         if (tk->tkr_mono.clock == clock)
1407                 return 0;
1408         stop_machine(change_clocksource, clock, NULL);
1409         tick_clock_notify();
1410         return tk->tkr_mono.clock == clock ? 0 : -1;
1411 }
1412 
1413 /**
1414  * ktime_get_raw_ts64 - Returns the raw monotonic time in a timespec
1415  * @ts:         pointer to the timespec64 to be set
1416  *
1417  * Returns the raw monotonic time (completely un-modified by ntp)
1418  */
1419 void ktime_get_raw_ts64(struct timespec64 *ts)
1420 {
1421         struct timekeeper *tk = &tk_core.timekeeper;
1422         unsigned int seq;
1423         u64 nsecs;
1424 
1425         do {
1426                 seq = read_seqcount_begin(&tk_core.seq);
1427                 ts->tv_sec = tk->raw_sec;
1428                 nsecs = timekeeping_get_ns(&tk->tkr_raw);
1429 
1430         } while (read_seqcount_retry(&tk_core.seq, seq));
1431 
1432         ts->tv_nsec = 0;
1433         timespec64_add_ns(ts, nsecs);
1434 }
1435 EXPORT_SYMBOL(ktime_get_raw_ts64);
1436 
1437 
1438 /**
1439  * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1440  */
1441 int timekeeping_valid_for_hres(void)
1442 {
1443         struct timekeeper *tk = &tk_core.timekeeper;
1444         unsigned int seq;
1445         int ret;
1446 
1447         do {
1448                 seq = read_seqcount_begin(&tk_core.seq);
1449 
1450                 ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
1451 
1452         } while (read_seqcount_retry(&tk_core.seq, seq));
1453 
1454         return ret;
1455 }
1456 
1457 /**
1458  * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1459  */
1460 u64 timekeeping_max_deferment(void)
1461 {
1462         struct timekeeper *tk = &tk_core.timekeeper;
1463         unsigned int seq;
1464         u64 ret;
1465 
1466         do {
1467                 seq = read_seqcount_begin(&tk_core.seq);
1468 
1469                 ret = tk->tkr_mono.clock->max_idle_ns;
1470 
1471         } while (read_seqcount_retry(&tk_core.seq, seq));
1472 
1473         return ret;
1474 }
1475 
1476 /**
1477  * read_persistent_clock64 -  Return time from the persistent clock.
1478  *
1479  * Weak dummy function for arches that do not yet support it.
1480  * Reads the time from the battery backed persistent clock.
1481  * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1482  *
1483  *  XXX - Do be sure to remove it once all arches implement it.
1484  */
1485 void __weak read_persistent_clock64(struct timespec64 *ts)
1486 {
1487         ts->tv_sec = 0;
1488         ts->tv_nsec = 0;
1489 }
1490 
1491 /**
1492  * read_persistent_wall_and_boot_offset - Read persistent clock, and also offset
1493  *                                        from the boot.
1494  *
1495  * Weak dummy function for arches that do not yet support it.
1496  * wall_time    - current time as returned by persistent clock
1497  * boot_offset  - offset that is defined as wall_time - boot_time
1498  * The default function calculates offset based on the current value of
1499  * local_clock(). This way architectures that support sched_clock() but don't
1500  * support dedicated boot time clock will provide the best estimate of the
1501  * boot time.
1502  */
1503 void __weak __init
1504 read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
1505                                      struct timespec64 *boot_offset)
1506 {
1507         read_persistent_clock64(wall_time);
1508         *boot_offset = ns_to_timespec64(local_clock());
1509 }
1510 
1511 /*
1512  * Flag reflecting whether timekeeping_resume() has injected sleeptime.
1513  *
1514  * The flag starts of false and is only set when a suspend reaches
1515  * timekeeping_suspend(), timekeeping_resume() sets it to false when the
1516  * timekeeper clocksource is not stopping across suspend and has been
1517  * used to update sleep time. If the timekeeper clocksource has stopped
1518  * then the flag stays true and is used by the RTC resume code to decide
1519  * whether sleeptime must be injected and if so the flag gets false then.
1520  *
1521  * If a suspend fails before reaching timekeeping_resume() then the flag
1522  * stays false and prevents erroneous sleeptime injection.
1523  */
1524 static bool suspend_timing_needed;
1525 
1526 /* Flag for if there is a persistent clock on this platform */
1527 static bool persistent_clock_exists;
1528 
1529 /*
1530  * timekeeping_init - Initializes the clocksource and common timekeeping values
1531  */
1532 void __init timekeeping_init(void)
1533 {
1534         struct timespec64 wall_time, boot_offset, wall_to_mono;
1535         struct timekeeper *tk = &tk_core.timekeeper;
1536         struct clocksource *clock;
1537         unsigned long flags;
1538 
1539         read_persistent_wall_and_boot_offset(&wall_time, &boot_offset);
1540         if (timespec64_valid_settod(&wall_time) &&
1541             timespec64_to_ns(&wall_time) > 0) {
1542                 persistent_clock_exists = true;
1543         } else if (timespec64_to_ns(&wall_time) != 0) {
1544                 pr_warn("Persistent clock returned invalid value");
1545                 wall_time = (struct timespec64){0};
1546         }
1547 
1548         if (timespec64_compare(&wall_time, &boot_offset) < 0)
1549                 boot_offset = (struct timespec64){0};
1550 
1551         /*
1552          * We want set wall_to_mono, so the following is true:
1553          * wall time + wall_to_mono = boot time
1554          */
1555         wall_to_mono = timespec64_sub(boot_offset, wall_time);
1556 
1557         raw_spin_lock_irqsave(&timekeeper_lock, flags);
1558         write_seqcount_begin(&tk_core.seq);
1559         ntp_init();
1560 
1561         clock = clocksource_default_clock();
1562         if (clock->enable)
1563                 clock->enable(clock);
1564         tk_setup_internals(tk, clock);
1565 
1566         tk_set_xtime(tk, &wall_time);
1567         tk->raw_sec = 0;
1568 
1569         tk_set_wall_to_mono(tk, wall_to_mono);
1570 
1571         timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1572 
1573         write_seqcount_end(&tk_core.seq);
1574         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1575 }
1576 
1577 /* time in seconds when suspend began for persistent clock */
1578 static struct timespec64 timekeeping_suspend_time;
1579 
1580 /**
1581  * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1582  * @delta: pointer to a timespec delta value
1583  *
1584  * Takes a timespec offset measuring a suspend interval and properly
1585  * adds the sleep offset to the timekeeping variables.
1586  */
1587 static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
1588                                            const struct timespec64 *delta)
1589 {
1590         if (!timespec64_valid_strict(delta)) {
1591                 printk_deferred(KERN_WARNING
1592                                 "__timekeeping_inject_sleeptime: Invalid "
1593                                 "sleep delta value!\n");
1594                 return;
1595         }
1596         tk_xtime_add(tk, delta);
1597         tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
1598         tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
1599         tk_debug_account_sleep_time(delta);
1600 }
1601 
1602 #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
1603 /**
1604  * We have three kinds of time sources to use for sleep time
1605  * injection, the preference order is:
1606  * 1) non-stop clocksource
1607  * 2) persistent clock (ie: RTC accessible when irqs are off)
1608  * 3) RTC
1609  *
1610  * 1) and 2) are used by timekeeping, 3) by RTC subsystem.
1611  * If system has neither 1) nor 2), 3) will be used finally.
1612  *
1613  *
1614  * If timekeeping has injected sleeptime via either 1) or 2),
1615  * 3) becomes needless, so in this case we don't need to call
1616  * rtc_resume(), and this is what timekeeping_rtc_skipresume()
1617  * means.
1618  */
1619 bool timekeeping_rtc_skipresume(void)
1620 {
1621         return !suspend_timing_needed;
1622 }
1623 
1624 /**
1625  * 1) can be determined whether to use or not only when doing
1626  * timekeeping_resume() which is invoked after rtc_suspend(),
1627  * so we can't skip rtc_suspend() surely if system has 1).
1628  *
1629  * But if system has 2), 2) will definitely be used, so in this
1630  * case we don't need to call rtc_suspend(), and this is what
1631  * timekeeping_rtc_skipsuspend() means.
1632  */
1633 bool timekeeping_rtc_skipsuspend(void)
1634 {
1635         return persistent_clock_exists;
1636 }
1637 
1638 /**
1639  * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1640  * @delta: pointer to a timespec64 delta value
1641  *
1642  * This hook is for architectures that cannot support read_persistent_clock64
1643  * because their RTC/persistent clock is only accessible when irqs are enabled.
1644  * and also don't have an effective nonstop clocksource.
1645  *
1646  * This function should only be called by rtc_resume(), and allows
1647  * a suspend offset to be injected into the timekeeping values.
1648  */
1649 void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
1650 {
1651         struct timekeeper *tk = &tk_core.timekeeper;
1652         unsigned long flags;
1653 
1654         raw_spin_lock_irqsave(&timekeeper_lock, flags);
1655         write_seqcount_begin(&tk_core.seq);
1656 
1657         suspend_timing_needed = false;
1658 
1659         timekeeping_forward_now(tk);
1660 
1661         __timekeeping_inject_sleeptime(tk, delta);
1662 
1663         timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
1664 
1665         write_seqcount_end(&tk_core.seq);
1666         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1667 
1668         /* signal hrtimers about time change */
1669         clock_was_set();
1670 }
1671 #endif
1672 
1673 /**
1674  * timekeeping_resume - Resumes the generic timekeeping subsystem.
1675  */
1676 void timekeeping_resume(void)
1677 {
1678         struct timekeeper *tk = &tk_core.timekeeper;
1679         struct clocksource *clock = tk->tkr_mono.clock;
1680         unsigned long flags;
1681         struct timespec64 ts_new, ts_delta;
1682         u64 cycle_now, nsec;
1683         bool inject_sleeptime = false;
1684 
1685         read_persistent_clock64(&ts_new);
1686 
1687         clockevents_resume();
1688         clocksource_resume();
1689 
1690         raw_spin_lock_irqsave(&timekeeper_lock, flags);
1691         write_seqcount_begin(&tk_core.seq);
1692 
1693         /*
1694          * After system resumes, we need to calculate the suspended time and
1695          * compensate it for the OS time. There are 3 sources that could be
1696          * used: Nonstop clocksource during suspend, persistent clock and rtc
1697          * device.
1698          *
1699          * One specific platform may have 1 or 2 or all of them, and the
1700          * preference will be:
1701          *      suspend-nonstop clocksource -> persistent clock -> rtc
1702          * The less preferred source will only be tried if there is no better
1703          * usable source. The rtc part is handled separately in rtc core code.
1704          */
1705         cycle_now = tk_clock_read(&tk->tkr_mono);
1706         nsec = clocksource_stop_suspend_timing(clock, cycle_now);
1707         if (nsec > 0) {
1708                 ts_delta = ns_to_timespec64(nsec);
1709                 inject_sleeptime = true;
1710         } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
1711                 ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
1712                 inject_sleeptime = true;
1713         }
1714 
1715         if (inject_sleeptime) {
1716                 suspend_timing_needed = false;
1717                 __timekeeping_inject_sleeptime(tk, &ts_delta);
1718         }
1719 
1720         /* Re-base the last cycle value */
1721         tk->tkr_mono.cycle_last = cycle_now;
1722         tk->tkr_raw.cycle_last  = cycle_now;
1723 
1724         tk->ntp_error = 0;
1725         timekeeping_suspended = 0;
1726         timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
1727         write_seqcount_end(&tk_core.seq);
1728         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1729 
1730         touch_softlockup_watchdog();
1731 
1732         tick_resume();
1733         hrtimers_resume();
1734 }
1735 
1736 int timekeeping_suspend(void)
1737 {
1738         struct timekeeper *tk = &tk_core.timekeeper;
1739         unsigned long flags;
1740         struct timespec64               delta, delta_delta;
1741         static struct timespec64        old_delta;
1742         struct clocksource *curr_clock;
1743         u64 cycle_now;
1744 
1745         read_persistent_clock64(&timekeeping_suspend_time);
1746 
1747         /*
1748          * On some systems the persistent_clock can not be detected at
1749          * timekeeping_init by its return value, so if we see a valid
1750          * value returned, update the persistent_clock_exists flag.
1751          */
1752         if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1753                 persistent_clock_exists = true;
1754 
1755         suspend_timing_needed = true;
1756 
1757         raw_spin_lock_irqsave(&timekeeper_lock, flags);
1758         write_seqcount_begin(&tk_core.seq);
1759         timekeeping_forward_now(tk);
1760         timekeeping_suspended = 1;
1761 
1762         /*
1763          * Since we've called forward_now, cycle_last stores the value
1764          * just read from the current clocksource. Save this to potentially
1765          * use in suspend timing.
1766          */
1767         curr_clock = tk->tkr_mono.clock;
1768         cycle_now = tk->tkr_mono.cycle_last;
1769         clocksource_start_suspend_timing(curr_clock, cycle_now);
1770 
1771         if (persistent_clock_exists) {
1772                 /*
1773                  * To avoid drift caused by repeated suspend/resumes,
1774                  * which each can add ~1 second drift error,
1775                  * try to compensate so the difference in system time
1776                  * and persistent_clock time stays close to constant.
1777                  */
1778                 delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time);
1779                 delta_delta = timespec64_sub(delta, old_delta);
1780                 if (abs(delta_delta.tv_sec) >= 2) {
1781                         /*
1782                          * if delta_delta is too large, assume time correction
1783                          * has occurred and set old_delta to the current delta.
1784                          */
1785                         old_delta = delta;
1786                 } else {
1787                         /* Otherwise try to adjust old_system to compensate */
1788                         timekeeping_suspend_time =
1789                                 timespec64_add(timekeeping_suspend_time, delta_delta);
1790                 }
1791         }
1792 
1793         timekeeping_update(tk, TK_MIRROR);
1794         halt_fast_timekeeper(tk);
1795         write_seqcount_end(&tk_core.seq);
1796         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1797 
1798         tick_suspend();
1799         clocksource_suspend();
1800         clockevents_suspend();
1801 
1802         return 0;
1803 }
1804 
1805 /* sysfs resume/suspend bits for timekeeping */
1806 static struct syscore_ops timekeeping_syscore_ops = {
1807         .resume         = timekeeping_resume,
1808         .suspend        = timekeeping_suspend,
1809 };
1810 
1811 static int __init timekeeping_init_ops(void)
1812 {
1813         register_syscore_ops(&timekeeping_syscore_ops);
1814         return 0;
1815 }
1816 device_initcall(timekeeping_init_ops);
1817 
1818 /*
1819  * Apply a multiplier adjustment to the timekeeper
1820  */
1821 static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
1822                                                          s64 offset,
1823                                                          s32 mult_adj)
1824 {
1825         s64 interval = tk->cycle_interval;
1826 
1827         if (mult_adj == 0) {
1828                 return;
1829         } else if (mult_adj == -1) {
1830                 interval = -interval;
1831                 offset = -offset;
1832         } else if (mult_adj != 1) {
1833                 interval *= mult_adj;
1834                 offset *= mult_adj;
1835         }
1836 
1837         /*
1838          * So the following can be confusing.
1839          *
1840          * To keep things simple, lets assume mult_adj == 1 for now.
1841          *
1842          * When mult_adj != 1, remember that the interval and offset values
1843          * have been appropriately scaled so the math is the same.
1844          *
1845          * The basic idea here is that we're increasing the multiplier
1846          * by one, this causes the xtime_interval to be incremented by
1847          * one cycle_interval. This is because:
1848          *      xtime_interval = cycle_interval * mult
1849          * So if mult is being incremented by one:
1850          *      xtime_interval = cycle_interval * (mult + 1)
1851          * Its the same as:
1852          *      xtime_interval = (cycle_interval * mult) + cycle_interval
1853          * Which can be shortened to:
1854          *      xtime_interval += cycle_interval
1855          *
1856          * So offset stores the non-accumulated cycles. Thus the current
1857          * time (in shifted nanoseconds) is:
1858          *      now = (offset * adj) + xtime_nsec
1859          * Now, even though we're adjusting the clock frequency, we have
1860          * to keep time consistent. In other words, we can't jump back
1861          * in time, and we also want to avoid jumping forward in time.
1862          *
1863          * So given the same offset value, we need the time to be the same
1864          * both before and after the freq adjustment.
1865          *      now = (offset * adj_1) + xtime_nsec_1
1866          *      now = (offset * adj_2) + xtime_nsec_2
1867          * So:
1868          *      (offset * adj_1) + xtime_nsec_1 =
1869          *              (offset * adj_2) + xtime_nsec_2
1870          * And we know:
1871          *      adj_2 = adj_1 + 1
1872          * So:
1873          *      (offset * adj_1) + xtime_nsec_1 =
1874          *              (offset * (adj_1+1)) + xtime_nsec_2
1875          *      (offset * adj_1) + xtime_nsec_1 =
1876          *              (offset * adj_1) + offset + xtime_nsec_2
1877          * Canceling the sides:
1878          *      xtime_nsec_1 = offset + xtime_nsec_2
1879          * Which gives us:
1880          *      xtime_nsec_2 = xtime_nsec_1 - offset
1881          * Which simplfies to:
1882          *      xtime_nsec -= offset
1883          */
1884         if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) {
1885                 /* NTP adjustment caused clocksource mult overflow */
1886                 WARN_ON_ONCE(1);
1887                 return;
1888         }
1889 
1890         tk->tkr_mono.mult += mult_adj;
1891         tk->xtime_interval += interval;
1892         tk->tkr_mono.xtime_nsec -= offset;
1893 }
1894 
1895 /*
1896  * Adjust the timekeeper's multiplier to the correct frequency
1897  * and also to reduce the accumulated error value.
1898  */
1899 static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1900 {
1901         u32 mult;
1902 
1903         /*
1904          * Determine the multiplier from the current NTP tick length.
1905          * Avoid expensive division when the tick length doesn't change.
1906          */
1907         if (likely(tk->ntp_tick == ntp_tick_length())) {
1908                 mult = tk->tkr_mono.mult - tk->ntp_err_mult;
1909         } else {
1910                 tk->ntp_tick = ntp_tick_length();
1911                 mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) -
1912                                  tk->xtime_remainder, tk->cycle_interval);
1913         }
1914 
1915         /*
1916          * If the clock is behind the NTP time, increase the multiplier by 1
1917          * to catch up with it. If it's ahead and there was a remainder in the
1918          * tick division, the clock will slow down. Otherwise it will stay
1919          * ahead until the tick length changes to a non-divisible value.
1920          */
1921         tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0;
1922         mult += tk->ntp_err_mult;
1923 
1924         timekeeping_apply_adjustment(tk, offset, mult - tk->tkr_mono.mult);
1925 
1926         if (unlikely(tk->tkr_mono.clock->maxadj &&
1927                 (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult)
1928                         > tk->tkr_mono.clock->maxadj))) {
1929                 printk_once(KERN_WARNING
1930                         "Adjusting %s more than 11%% (%ld vs %ld)\n",
1931                         tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult,
1932                         (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj);
1933         }
1934 
1935         /*
1936          * It may be possible that when we entered this function, xtime_nsec
1937          * was very small.  Further, if we're slightly speeding the clocksource
1938          * in the code above, its possible the required corrective factor to
1939          * xtime_nsec could cause it to underflow.
1940          *
1941          * Now, since we have already accumulated the second and the NTP
1942          * subsystem has been notified via second_overflow(), we need to skip
1943          * the next update.
1944          */
1945         if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) {
1946                 tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC <<
1947                                                         tk->tkr_mono.shift;
1948                 tk->xtime_sec--;
1949                 tk->skip_second_overflow = 1;
1950         }
1951 }
1952 
1953 /**
1954  * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1955  *
1956  * Helper function that accumulates the nsecs greater than a second
1957  * from the xtime_nsec field to the xtime_secs field.
1958  * It also calls into the NTP code to handle leapsecond processing.
1959  *
1960  */
1961 static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
1962 {
1963         u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
1964         unsigned int clock_set = 0;
1965 
1966         while (tk->tkr_mono.xtime_nsec >= nsecps) {
1967                 int leap;
1968 
1969                 tk->tkr_mono.xtime_nsec -= nsecps;
1970                 tk->xtime_sec++;
1971 
1972                 /*
1973                  * Skip NTP update if this second was accumulated before,
1974                  * i.e. xtime_nsec underflowed in timekeeping_adjust()
1975                  */
1976                 if (unlikely(tk->skip_second_overflow)) {
1977                         tk->skip_second_overflow = 0;
1978                         continue;
1979                 }
1980 
1981                 /* Figure out if its a leap sec and apply if needed */
1982                 leap = second_overflow(tk->xtime_sec);
1983                 if (unlikely(leap)) {
1984                         struct timespec64 ts;
1985 
1986                         tk->xtime_sec += leap;
1987 
1988                         ts.tv_sec = leap;
1989                         ts.tv_nsec = 0;
1990                         tk_set_wall_to_mono(tk,
1991                                 timespec64_sub(tk->wall_to_monotonic, ts));
1992 
1993                         __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
1994 
1995                         clock_set = TK_CLOCK_WAS_SET;
1996                 }
1997         }
1998         return clock_set;
1999 }
2000 
2001 /**
2002  * logarithmic_accumulation - shifted accumulation of cycles
2003  *
2004  * This functions accumulates a shifted interval of cycles into
2005  * into a shifted interval nanoseconds. Allows for O(log) accumulation
2006  * loop.
2007  *
2008  * Returns the unconsumed cycles.
2009  */
2010 static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
2011                                     u32 shift, unsigned int *clock_set)
2012 {
2013         u64 interval = tk->cycle_interval << shift;
2014         u64 snsec_per_sec;
2015 
2016         /* If the offset is smaller than a shifted interval, do nothing */
2017         if (offset < interval)
2018                 return offset;
2019 
2020         /* Accumulate one shifted interval */
2021         offset -= interval;
2022         tk->tkr_mono.cycle_last += interval;
2023         tk->tkr_raw.cycle_last  += interval;
2024 
2025         tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift;
2026         *clock_set |= accumulate_nsecs_to_secs(tk);
2027 
2028         /* Accumulate raw time */
2029         tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
2030         snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
2031         while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
2032                 tk->tkr_raw.xtime_nsec -= snsec_per_sec;
2033                 tk->raw_sec++;
2034         }
2035 
2036         /* Accumulate error between NTP and clock interval */
2037         tk->ntp_error += tk->ntp_tick << shift;
2038         tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
2039                                                 (tk->ntp_error_shift + shift);
2040 
2041         return offset;
2042 }
2043 
2044 /*
2045  * timekeeping_advance - Updates the timekeeper to the current time and
2046  * current NTP tick length
2047  */
2048 static void timekeeping_advance(enum timekeeping_adv_mode mode)
2049 {
2050         struct timekeeper *real_tk = &tk_core.timekeeper;
2051         struct timekeeper *tk = &shadow_timekeeper;
2052         u64 offset;
2053         int shift = 0, maxshift;
2054         unsigned int clock_set = 0;
2055         unsigned long flags;
2056 
2057         raw_spin_lock_irqsave(&timekeeper_lock, flags);
2058 
2059         /* Make sure we're fully resumed: */
2060         if (unlikely(timekeeping_suspended))
2061                 goto out;
2062 
2063 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
2064         offset = real_tk->cycle_interval;
2065 
2066         if (mode != TK_ADV_TICK)
2067                 goto out;
2068 #else
2069         offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
2070                                    tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
2071 
2072         /* Check if there's really nothing to do */
2073         if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK)
2074                 goto out;
2075 #endif
2076 
2077         /* Do some additional sanity checking */
2078         timekeeping_check_update(tk, offset);
2079 
2080         /*
2081          * With NO_HZ we may have to accumulate many cycle_intervals
2082          * (think "ticks") worth of time at once. To do this efficiently,
2083          * we calculate the largest doubling multiple of cycle_intervals
2084          * that is smaller than the offset.  We then accumulate that
2085          * chunk in one go, and then try to consume the next smaller
2086          * doubled multiple.
2087          */
2088         shift = ilog2(offset) - ilog2(tk->cycle_interval);
2089         shift = max(0, shift);
2090         /* Bound shift to one less than what overflows tick_length */
2091         maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
2092         shift = min(shift, maxshift);
2093         while (offset >= tk->cycle_interval) {
2094                 offset = logarithmic_accumulation(tk, offset, shift,
2095                                                         &clock_set);
2096                 if (offset < tk->cycle_interval<<shift)
2097                         shift--;
2098         }
2099 
2100         /* Adjust the multiplier to correct NTP error */
2101         timekeeping_adjust(tk, offset);
2102 
2103         /*
2104          * Finally, make sure that after the rounding
2105          * xtime_nsec isn't larger than NSEC_PER_SEC
2106          */
2107         clock_set |= accumulate_nsecs_to_secs(tk);
2108 
2109         write_seqcount_begin(&tk_core.seq);
2110         /*
2111          * Update the real timekeeper.
2112          *
2113          * We could avoid this memcpy by switching pointers, but that
2114          * requires changes to all other timekeeper usage sites as
2115          * well, i.e. move the timekeeper pointer getter into the
2116          * spinlocked/seqcount protected sections. And we trade this
2117          * memcpy under the tk_core.seq against one before we start
2118          * updating.
2119          */
2120         timekeeping_update(tk, clock_set);
2121         memcpy(real_tk, tk, sizeof(*tk));
2122         /* The memcpy must come last. Do not put anything here! */
2123         write_seqcount_end(&tk_core.seq);
2124 out:
2125         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2126         if (clock_set)
2127                 /* Have to call _delayed version, since in irq context*/
2128                 clock_was_set_delayed();
2129 }
2130 
2131 /**
2132  * update_wall_time - Uses the current clocksource to increment the wall time
2133  *
2134  */
2135 void update_wall_time(void)
2136 {
2137         timekeeping_advance(TK_ADV_TICK);
2138 }
2139 
2140 /**
2141  * getboottime64 - Return the real time of system boot.
2142  * @ts:         pointer to the timespec64 to be set
2143  *
2144  * Returns the wall-time of boot in a timespec64.
2145  *
2146  * This is based on the wall_to_monotonic offset and the total suspend
2147  * time. Calls to settimeofday will affect the value returned (which
2148  * basically means that however wrong your real time clock is at boot time,
2149  * you get the right time here).
2150  */
2151 void getboottime64(struct timespec64 *ts)
2152 {
2153         struct timekeeper *tk = &tk_core.timekeeper;
2154         ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
2155 
2156         *ts = ktime_to_timespec64(t);
2157 }
2158 EXPORT_SYMBOL_GPL(getboottime64);
2159 
2160 void ktime_get_coarse_real_ts64(struct timespec64 *ts)
2161 {
2162         struct timekeeper *tk = &tk_core.timekeeper;
2163         unsigned int seq;
2164 
2165         do {
2166                 seq = read_seqcount_begin(&tk_core.seq);
2167 
2168                 *ts = tk_xtime(tk);
2169         } while (read_seqcount_retry(&tk_core.seq, seq));
2170 }
2171 EXPORT_SYMBOL(ktime_get_coarse_real_ts64);
2172 
2173 void ktime_get_coarse_ts64(struct timespec64 *ts)
2174 {
2175         struct timekeeper *tk = &tk_core.timekeeper;
2176         struct timespec64 now, mono;
2177         unsigned int seq;
2178 
2179         do {
2180                 seq = read_seqcount_begin(&tk_core.seq);
2181 
2182                 now = tk_xtime(tk);
2183                 mono = tk->wall_to_monotonic;
2184         } while (read_seqcount_retry(&tk_core.seq, seq));
2185 
2186         set_normalized_timespec64(ts, now.tv_sec + mono.tv_sec,
2187                                 now.tv_nsec + mono.tv_nsec);
2188 }
2189 EXPORT_SYMBOL(ktime_get_coarse_ts64);
2190 
2191 /*
2192  * Must hold jiffies_lock
2193  */
2194 void do_timer(unsigned long ticks)
2195 {
2196         jiffies_64 += ticks;
2197         calc_global_load(ticks);
2198 }
2199 
2200 /**
2201  * ktime_get_update_offsets_now - hrtimer helper
2202  * @cwsseq:     pointer to check and store the clock was set sequence number
2203  * @offs_real:  pointer to storage for monotonic -> realtime offset
2204  * @offs_boot:  pointer to storage for monotonic -> boottime offset
2205  * @offs_tai:   pointer to storage for monotonic -> clock tai offset
2206  *
2207  * Returns current monotonic time and updates the offsets if the
2208  * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
2209  * different.
2210  *
2211  * Called from hrtimer_interrupt() or retrigger_next_event()
2212  */
2213 ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
2214                                      ktime_t *offs_boot, ktime_t *offs_tai)
2215 {
2216         struct timekeeper *tk = &tk_core.timekeeper;
2217         unsigned int seq;
2218         ktime_t base;
2219         u64 nsecs;
2220 
2221         do {
2222                 seq = read_seqcount_begin(&tk_core.seq);
2223 
2224                 base = tk->tkr_mono.base;
2225                 nsecs = timekeeping_get_ns(&tk->tkr_mono);
2226                 base = ktime_add_ns(base, nsecs);
2227 
2228                 if (*cwsseq != tk->clock_was_set_seq) {
2229                         *cwsseq = tk->clock_was_set_seq;
2230                         *offs_real = tk->offs_real;
2231                         *offs_boot = tk->offs_boot;
2232                         *offs_tai = tk->offs_tai;
2233                 }
2234 
2235                 /* Handle leapsecond insertion adjustments */
2236                 if (unlikely(base >= tk->next_leap_ktime))
2237                         *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
2238 
2239         } while (read_seqcount_retry(&tk_core.seq, seq));
2240 
2241         return base;
2242 }
2243 
2244 /**
2245  * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2246  */
2247 static int timekeeping_validate_timex(const struct __kernel_timex *txc)
2248 {
2249         if (txc->modes & ADJ_ADJTIME) {
2250                 /* singleshot must not be used with any other mode bits */
2251                 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2252                         return -EINVAL;
2253                 if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2254                     !capable(CAP_SYS_TIME))
2255                         return -EPERM;
2256         } else {
2257                 /* In order to modify anything, you gotta be super-user! */
2258                 if (txc->modes && !capable(CAP_SYS_TIME))
2259                         return -EPERM;
2260                 /*
2261                  * if the quartz is off by more than 10% then
2262                  * something is VERY wrong!
2263                  */
2264                 if (txc->modes & ADJ_TICK &&
2265                     (txc->tick <  900000/USER_HZ ||
2266                      txc->tick > 1100000/USER_HZ))
2267                         return -EINVAL;
2268         }
2269 
2270         if (txc->modes & ADJ_SETOFFSET) {
2271                 /* In order to inject time, you gotta be super-user! */
2272                 if (!capable(CAP_SYS_TIME))
2273                         return -EPERM;
2274 
2275                 /*
2276                  * Validate if a timespec/timeval used to inject a time
2277                  * offset is valid.  Offsets can be postive or negative, so
2278                  * we don't check tv_sec. The value of the timeval/timespec
2279                  * is the sum of its fields,but *NOTE*:
2280                  * The field tv_usec/tv_nsec must always be non-negative and
2281                  * we can't have more nanoseconds/microseconds than a second.
2282                  */
2283                 if (txc->time.tv_usec < 0)
2284                         return -EINVAL;
2285 
2286                 if (txc->modes & ADJ_NANO) {
2287                         if (txc->time.tv_usec >= NSEC_PER_SEC)
2288                                 return -EINVAL;
2289                 } else {
2290                         if (txc->time.tv_usec >= USEC_PER_SEC)
2291                                 return -EINVAL;
2292                 }
2293         }
2294 
2295         /*
2296          * Check for potential multiplication overflows that can
2297          * only happen on 64-bit systems:
2298          */
2299         if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2300                 if (LLONG_MIN / PPM_SCALE > txc->freq)
2301                         return -EINVAL;
2302                 if (LLONG_MAX / PPM_SCALE < txc->freq)
2303                         return -EINVAL;
2304         }
2305 
2306         return 0;
2307 }
2308 
2309 
2310 /**
2311  * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2312  */
2313 int do_adjtimex(struct __kernel_timex *txc)
2314 {
2315         struct timekeeper *tk = &tk_core.timekeeper;
2316         struct audit_ntp_data ad;
2317         unsigned long flags;
2318         struct timespec64 ts;
2319         s32 orig_tai, tai;
2320         int ret;
2321 
2322         /* Validate the data before disabling interrupts */
2323         ret = timekeeping_validate_timex(txc);
2324         if (ret)
2325                 return ret;
2326 
2327         if (txc->modes & ADJ_SETOFFSET) {
2328                 struct timespec64 delta;
2329                 delta.tv_sec  = txc->time.tv_sec;
2330                 delta.tv_nsec = txc->time.tv_usec;
2331                 if (!(txc->modes & ADJ_NANO))
2332                         delta.tv_nsec *= 1000;
2333                 ret = timekeeping_inject_offset(&delta);
2334                 if (ret)
2335                         return ret;
2336 
2337                 audit_tk_injoffset(delta);
2338         }
2339 
2340         audit_ntp_init(&ad);
2341 
2342         ktime_get_real_ts64(&ts);
2343 
2344         raw_spin_lock_irqsave(&timekeeper_lock, flags);
2345         write_seqcount_begin(&tk_core.seq);
2346 
2347         orig_tai = tai = tk->tai_offset;
2348         ret = __do_adjtimex(txc, &ts, &tai, &ad);
2349 
2350         if (tai != orig_tai) {
2351                 __timekeeping_set_tai_offset(tk, tai);
2352                 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
2353         }
2354         tk_update_leap_state(tk);
2355 
2356         write_seqcount_end(&tk_core.seq);
2357         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2358 
2359         audit_ntp_log(&ad);
2360 
2361         /* Update the multiplier immediately if frequency was set directly */
2362         if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
2363                 timekeeping_advance(TK_ADV_FREQ);
2364 
2365         if (tai != orig_tai)
2366                 clock_was_set();
2367 
2368         ntp_notify_cmos_timer();
2369 
2370         return ret;
2371 }
2372 
2373 #ifdef CONFIG_NTP_PPS
2374 /**
2375  * hardpps() - Accessor function to NTP __hardpps function
2376  */
2377 void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
2378 {
2379         unsigned long flags;
2380 
2381         raw_spin_lock_irqsave(&timekeeper_lock, flags);
2382         write_seqcount_begin(&tk_core.seq);
2383 
2384         __hardpps(phase_ts, raw_ts);
2385 
2386         write_seqcount_end(&tk_core.seq);
2387         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
2388 }
2389 EXPORT_SYMBOL(hardpps);
2390 #endif /* CONFIG_NTP_PPS */
2391 
2392 /**
2393  * xtime_update() - advances the timekeeping infrastructure
2394  * @ticks:      number of ticks, that have elapsed since the last call.
2395  *
2396  * Must be called with interrupts disabled.
2397  */
2398 void xtime_update(unsigned long ticks)
2399 {
2400         write_seqlock(&jiffies_lock);
2401         do_timer(ticks);
2402         write_sequnlock(&jiffies_lock);
2403         update_wall_time();
2404 }