1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * NTP state machine interfaces and logic. 4 * 5 * This code was mainly moved from kernel/timer.c and kernel/time.c 6 * Please see those files for relevant copyright info and historical 7 * changelogs. 8 */ 9 #include <linux/capability.h> 10 #include <linux/clocksource.h> 11 #include <linux/workqueue.h> 12 #include <linux/hrtimer.h> 13 #include <linux/jiffies.h> 14 #include <linux/math64.h> 15 #include <linux/timex.h> 16 #include <linux/time.h> 17 #include <linux/mm.h> 18 #include <linux/module.h> 19 #include <linux/rtc.h> 20 #include <linux/audit.h> 21 22 #include "ntp_internal.h" 23 #include "timekeeping_internal.h" 24 25 /** 26 * struct ntp_data - Structure holding all NTP related state 27 * @tick_usec: USER_HZ period in microseconds 28 * @tick_length: Adjusted tick length 29 * @tick_length_base: Base value for @tick_length 30 * @time_state: State of the clock synchronization 31 * @time_status: Clock status bits 32 * @time_offset: Time adjustment in nanoseconds 33 * @time_constant: PLL time constant 34 * @time_maxerror: Maximum error in microseconds holding the NTP sync distance 35 * (NTP dispersion + delay / 2) 36 * @time_esterror: Estimated error in microseconds holding NTP dispersion 37 * @time_freq: Frequency offset scaled nsecs/secs 38 * @time_reftime: Time at last adjustment in seconds 39 * @time_adjust: Adjustment value 40 * @ntp_tick_adj: Constant boot-param configurable NTP tick adjustment (upscaled) 41 * @ntp_next_leap_sec: Second value of the next pending leapsecond, or TIME64_MAX if no leap 42 * 43 * @pps_valid: PPS signal watchdog counter 44 * @pps_tf: PPS phase median filter 45 * @pps_jitter: PPS current jitter in nanoseconds 46 * @pps_fbase: PPS beginning of the last freq interval 47 * @pps_shift: PPS current interval duration in seconds (shift value) 48 * @pps_intcnt: PPS interval counter 49 * @pps_freq: PPS frequency offset in scaled ns/s 50 * @pps_stabil: PPS current stability in scaled ns/s 51 * @pps_calcnt: PPS monitor: calibration intervals 52 * @pps_jitcnt: PPS monitor: jitter limit exceeded 53 * @pps_stbcnt: PPS monitor: stability limit exceeded 54 * @pps_errcnt: PPS monitor: calibration errors 55 * 56 * Protected by the timekeeping locks. 57 */ 58 struct ntp_data { 59 unsigned long tick_usec; 60 u64 tick_length; 61 u64 tick_length_base; 62 int time_state; 63 int time_status; 64 s64 time_offset; 65 long time_constant; 66 long time_maxerror; 67 long time_esterror; 68 s64 time_freq; 69 time64_t time_reftime; 70 long time_adjust; 71 s64 ntp_tick_adj; 72 time64_t ntp_next_leap_sec; 73 #ifdef CONFIG_NTP_PPS 74 int pps_valid; 75 long pps_tf[3]; 76 long pps_jitter; 77 struct timespec64 pps_fbase; 78 int pps_shift; 79 int pps_intcnt; 80 s64 pps_freq; 81 long pps_stabil; 82 long pps_calcnt; 83 long pps_jitcnt; 84 long pps_stbcnt; 85 long pps_errcnt; 86 #endif 87 }; 88 89 static struct ntp_data tk_ntp_data = { 90 .tick_usec = USER_TICK_USEC, 91 .time_state = TIME_OK, 92 .time_status = STA_UNSYNC, 93 .time_constant = 2, 94 .time_maxerror = NTP_PHASE_LIMIT, 95 .time_esterror = NTP_PHASE_LIMIT, 96 .ntp_next_leap_sec = TIME64_MAX, 97 }; 98 99 #define SECS_PER_DAY 86400 100 #define MAX_TICKADJ 500LL /* usecs */ 101 #define MAX_TICKADJ_SCALED \ 102 (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ) 103 #define MAX_TAI_OFFSET 100000 104 105 #ifdef CONFIG_NTP_PPS 106 107 /* 108 * The following variables are used when a pulse-per-second (PPS) signal 109 * is available. They establish the engineering parameters of the clock 110 * discipline loop when controlled by the PPS signal. 111 */ 112 #define PPS_VALID 10 /* PPS signal watchdog max (s) */ 113 #define PPS_POPCORN 4 /* popcorn spike threshold (shift) */ 114 #define PPS_INTMIN 2 /* min freq interval (s) (shift) */ 115 #define PPS_INTMAX 8 /* max freq interval (s) (shift) */ 116 #define PPS_INTCOUNT 4 /* number of consecutive good intervals to 117 increase pps_shift or consecutive bad 118 intervals to decrease it */ 119 #define PPS_MAXWANDER 100000 /* max PPS freq wander (ns/s) */ 120 121 /* 122 * PPS kernel consumer compensates the whole phase error immediately. 123 * Otherwise, reduce the offset by a fixed factor times the time constant. 124 */ 125 static inline s64 ntp_offset_chunk(struct ntp_data *ntpdata, s64 offset) 126 { 127 if (ntpdata->time_status & STA_PPSTIME && ntpdata->time_status & STA_PPSSIGNAL) 128 return offset; 129 else 130 return shift_right(offset, SHIFT_PLL + ntpdata->time_constant); 131 } 132 133 static inline void pps_reset_freq_interval(struct ntp_data *ntpdata) 134 { 135 /* The PPS calibration interval may end surprisingly early */ 136 ntpdata->pps_shift = PPS_INTMIN; 137 ntpdata->pps_intcnt = 0; 138 } 139 140 /** 141 * pps_clear - Clears the PPS state variables 142 * @ntpdata: Pointer to ntp data 143 */ 144 static inline void pps_clear(struct ntp_data *ntpdata) 145 { 146 pps_reset_freq_interval(ntpdata); 147 ntpdata->pps_tf[0] = 0; 148 ntpdata->pps_tf[1] = 0; 149 ntpdata->pps_tf[2] = 0; 150 ntpdata->pps_fbase.tv_sec = ntpdata->pps_fbase.tv_nsec = 0; 151 ntpdata->pps_freq = 0; 152 } 153 154 /* 155 * Decrease pps_valid to indicate that another second has passed since the 156 * last PPS signal. When it reaches 0, indicate that PPS signal is missing. 157 */ 158 static inline void pps_dec_valid(struct ntp_data *ntpdata) 159 { 160 if (ntpdata->pps_valid > 0) { 161 ntpdata->pps_valid--; 162 } else { 163 ntpdata->time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER | 164 STA_PPSWANDER | STA_PPSERROR); 165 pps_clear(ntpdata); 166 } 167 } 168 169 static inline void pps_set_freq(struct ntp_data *ntpdata) 170 { 171 ntpdata->pps_freq = ntpdata->time_freq; 172 } 173 174 static inline bool is_error_status(int status) 175 { 176 return (status & (STA_UNSYNC|STA_CLOCKERR)) 177 /* 178 * PPS signal lost when either PPS time or PPS frequency 179 * synchronization requested 180 */ 181 || ((status & (STA_PPSFREQ|STA_PPSTIME)) 182 && !(status & STA_PPSSIGNAL)) 183 /* 184 * PPS jitter exceeded when PPS time synchronization 185 * requested 186 */ 187 || ((status & (STA_PPSTIME|STA_PPSJITTER)) 188 == (STA_PPSTIME|STA_PPSJITTER)) 189 /* 190 * PPS wander exceeded or calibration error when PPS 191 * frequency synchronization requested 192 */ 193 || ((status & STA_PPSFREQ) 194 && (status & (STA_PPSWANDER|STA_PPSERROR))); 195 } 196 197 static inline void pps_fill_timex(struct ntp_data *ntpdata, struct __kernel_timex *txc) 198 { 199 txc->ppsfreq = shift_right((ntpdata->pps_freq >> PPM_SCALE_INV_SHIFT) * 200 PPM_SCALE_INV, NTP_SCALE_SHIFT); 201 txc->jitter = ntpdata->pps_jitter; 202 if (!(ntpdata->time_status & STA_NANO)) 203 txc->jitter = ntpdata->pps_jitter / NSEC_PER_USEC; 204 txc->shift = ntpdata->pps_shift; 205 txc->stabil = ntpdata->pps_stabil; 206 txc->jitcnt = ntpdata->pps_jitcnt; 207 txc->calcnt = ntpdata->pps_calcnt; 208 txc->errcnt = ntpdata->pps_errcnt; 209 txc->stbcnt = ntpdata->pps_stbcnt; 210 } 211 212 #else /* !CONFIG_NTP_PPS */ 213 214 static inline s64 ntp_offset_chunk(struct ntp_data *ntpdata, s64 offset) 215 { 216 return shift_right(offset, SHIFT_PLL + ntpdata->time_constant); 217 } 218 219 static inline void pps_reset_freq_interval(struct ntp_data *ntpdata) {} 220 static inline void pps_clear(struct ntp_data *ntpdata) {} 221 static inline void pps_dec_valid(struct ntp_data *ntpdata) {} 222 static inline void pps_set_freq(struct ntp_data *ntpdata) {} 223 224 static inline bool is_error_status(int status) 225 { 226 return status & (STA_UNSYNC|STA_CLOCKERR); 227 } 228 229 static inline void pps_fill_timex(struct ntp_data *ntpdata, struct __kernel_timex *txc) 230 { 231 /* PPS is not implemented, so these are zero */ 232 txc->ppsfreq = 0; 233 txc->jitter = 0; 234 txc->shift = 0; 235 txc->stabil = 0; 236 txc->jitcnt = 0; 237 txc->calcnt = 0; 238 txc->errcnt = 0; 239 txc->stbcnt = 0; 240 } 241 242 #endif /* CONFIG_NTP_PPS */ 243 244 /* 245 * Update tick_length and tick_length_base, based on tick_usec, ntp_tick_adj and 246 * time_freq: 247 */ 248 static void ntp_update_frequency(struct ntp_data *ntpdata) 249 { 250 u64 second_length, new_base, tick_usec = (u64)ntpdata->tick_usec; 251 252 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) << NTP_SCALE_SHIFT; 253 254 second_length += ntpdata->ntp_tick_adj; 255 second_length += ntpdata->time_freq; 256 257 new_base = div_u64(second_length, NTP_INTERVAL_FREQ); 258 259 /* 260 * Don't wait for the next second_overflow, apply the change to the 261 * tick length immediately: 262 */ 263 ntpdata->tick_length += new_base - ntpdata->tick_length_base; 264 ntpdata->tick_length_base = new_base; 265 } 266 267 static inline s64 ntp_update_offset_fll(struct ntp_data *ntpdata, s64 offset64, long secs) 268 { 269 ntpdata->time_status &= ~STA_MODE; 270 271 if (secs < MINSEC) 272 return 0; 273 274 if (!(ntpdata->time_status & STA_FLL) && (secs <= MAXSEC)) 275 return 0; 276 277 ntpdata->time_status |= STA_MODE; 278 279 return div64_long(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs); 280 } 281 282 static void ntp_update_offset(struct ntp_data *ntpdata, long offset) 283 { 284 s64 freq_adj, offset64; 285 long secs, real_secs; 286 287 if (!(ntpdata->time_status & STA_PLL)) 288 return; 289 290 if (!(ntpdata->time_status & STA_NANO)) { 291 /* Make sure the multiplication below won't overflow */ 292 offset = clamp(offset, -USEC_PER_SEC, USEC_PER_SEC); 293 offset *= NSEC_PER_USEC; 294 } 295 296 /* Scale the phase adjustment and clamp to the operating range. */ 297 offset = clamp(offset, -MAXPHASE, MAXPHASE); 298 299 /* 300 * Select how the frequency is to be controlled 301 * and in which mode (PLL or FLL). 302 */ 303 real_secs = __ktime_get_real_seconds(); 304 secs = (long)(real_secs - ntpdata->time_reftime); 305 if (unlikely(ntpdata->time_status & STA_FREQHOLD)) 306 secs = 0; 307 308 ntpdata->time_reftime = real_secs; 309 310 offset64 = offset; 311 freq_adj = ntp_update_offset_fll(ntpdata, offset64, secs); 312 313 /* 314 * Clamp update interval to reduce PLL gain with low 315 * sampling rate (e.g. intermittent network connection) 316 * to avoid instability. 317 */ 318 if (unlikely(secs > 1 << (SHIFT_PLL + 1 + ntpdata->time_constant))) 319 secs = 1 << (SHIFT_PLL + 1 + ntpdata->time_constant); 320 321 freq_adj += (offset64 * secs) << 322 (NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + ntpdata->time_constant)); 323 324 freq_adj = min(freq_adj + ntpdata->time_freq, MAXFREQ_SCALED); 325 326 ntpdata->time_freq = max(freq_adj, -MAXFREQ_SCALED); 327 328 ntpdata->time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ); 329 } 330 331 static void __ntp_clear(struct ntp_data *ntpdata) 332 { 333 /* Stop active adjtime() */ 334 ntpdata->time_adjust = 0; 335 ntpdata->time_status |= STA_UNSYNC; 336 ntpdata->time_maxerror = NTP_PHASE_LIMIT; 337 ntpdata->time_esterror = NTP_PHASE_LIMIT; 338 339 ntp_update_frequency(ntpdata); 340 341 ntpdata->tick_length = ntpdata->tick_length_base; 342 ntpdata->time_offset = 0; 343 344 ntpdata->ntp_next_leap_sec = TIME64_MAX; 345 /* Clear PPS state variables */ 346 pps_clear(ntpdata); 347 } 348 349 /** 350 * ntp_clear - Clears the NTP state variables 351 */ 352 void ntp_clear(void) 353 { 354 __ntp_clear(&tk_ntp_data); 355 } 356 357 358 u64 ntp_tick_length(void) 359 { 360 return tk_ntp_data.tick_length; 361 } 362 363 /** 364 * ntp_get_next_leap - Returns the next leapsecond in CLOCK_REALTIME ktime_t 365 * 366 * Provides the time of the next leapsecond against CLOCK_REALTIME in 367 * a ktime_t format. Returns KTIME_MAX if no leapsecond is pending. 368 */ 369 ktime_t ntp_get_next_leap(void) 370 { 371 struct ntp_data *ntpdata = &tk_ntp_data; 372 ktime_t ret; 373 374 if ((ntpdata->time_state == TIME_INS) && (ntpdata->time_status & STA_INS)) 375 return ktime_set(ntpdata->ntp_next_leap_sec, 0); 376 ret = KTIME_MAX; 377 return ret; 378 } 379 380 /* 381 * This routine handles the overflow of the microsecond field 382 * 383 * The tricky bits of code to handle the accurate clock support 384 * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame. 385 * They were originally developed for SUN and DEC kernels. 386 * All the kudos should go to Dave for this stuff. 387 * 388 * Also handles leap second processing, and returns leap offset 389 */ 390 int second_overflow(time64_t secs) 391 { 392 struct ntp_data *ntpdata = &tk_ntp_data; 393 s64 delta; 394 int leap = 0; 395 s32 rem; 396 397 /* 398 * Leap second processing. If in leap-insert state at the end of the 399 * day, the system clock is set back one second; if in leap-delete 400 * state, the system clock is set ahead one second. 401 */ 402 switch (ntpdata->time_state) { 403 case TIME_OK: 404 if (ntpdata->time_status & STA_INS) { 405 ntpdata->time_state = TIME_INS; 406 div_s64_rem(secs, SECS_PER_DAY, &rem); 407 ntpdata->ntp_next_leap_sec = secs + SECS_PER_DAY - rem; 408 } else if (ntpdata->time_status & STA_DEL) { 409 ntpdata->time_state = TIME_DEL; 410 div_s64_rem(secs + 1, SECS_PER_DAY, &rem); 411 ntpdata->ntp_next_leap_sec = secs + SECS_PER_DAY - rem; 412 } 413 break; 414 case TIME_INS: 415 if (!(ntpdata->time_status & STA_INS)) { 416 ntpdata->ntp_next_leap_sec = TIME64_MAX; 417 ntpdata->time_state = TIME_OK; 418 } else if (secs == ntpdata->ntp_next_leap_sec) { 419 leap = -1; 420 ntpdata->time_state = TIME_OOP; 421 pr_notice("Clock: inserting leap second 23:59:60 UTC\n"); 422 } 423 break; 424 case TIME_DEL: 425 if (!(ntpdata->time_status & STA_DEL)) { 426 ntpdata->ntp_next_leap_sec = TIME64_MAX; 427 ntpdata->time_state = TIME_OK; 428 } else if (secs == ntpdata->ntp_next_leap_sec) { 429 leap = 1; 430 ntpdata->ntp_next_leap_sec = TIME64_MAX; 431 ntpdata->time_state = TIME_WAIT; 432 pr_notice("Clock: deleting leap second 23:59:59 UTC\n"); 433 } 434 break; 435 case TIME_OOP: 436 ntpdata->ntp_next_leap_sec = TIME64_MAX; 437 ntpdata->time_state = TIME_WAIT; 438 break; 439 case TIME_WAIT: 440 if (!(ntpdata->time_status & (STA_INS | STA_DEL))) 441 ntpdata->time_state = TIME_OK; 442 break; 443 } 444 445 /* Bump the maxerror field */ 446 ntpdata->time_maxerror += MAXFREQ / NSEC_PER_USEC; 447 if (ntpdata->time_maxerror > NTP_PHASE_LIMIT) { 448 ntpdata->time_maxerror = NTP_PHASE_LIMIT; 449 ntpdata->time_status |= STA_UNSYNC; 450 } 451 452 /* Compute the phase adjustment for the next second */ 453 ntpdata->tick_length = ntpdata->tick_length_base; 454 455 delta = ntp_offset_chunk(ntpdata, ntpdata->time_offset); 456 ntpdata->time_offset -= delta; 457 ntpdata->tick_length += delta; 458 459 /* Check PPS signal */ 460 pps_dec_valid(ntpdata); 461 462 if (!ntpdata->time_adjust) 463 goto out; 464 465 if (ntpdata->time_adjust > MAX_TICKADJ) { 466 ntpdata->time_adjust -= MAX_TICKADJ; 467 ntpdata->tick_length += MAX_TICKADJ_SCALED; 468 goto out; 469 } 470 471 if (ntpdata->time_adjust < -MAX_TICKADJ) { 472 ntpdata->time_adjust += MAX_TICKADJ; 473 ntpdata->tick_length -= MAX_TICKADJ_SCALED; 474 goto out; 475 } 476 477 ntpdata->tick_length += (s64)(ntpdata->time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ) 478 << NTP_SCALE_SHIFT; 479 ntpdata->time_adjust = 0; 480 481 out: 482 return leap; 483 } 484 485 #if defined(CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC) 486 static void sync_hw_clock(struct work_struct *work); 487 static DECLARE_WORK(sync_work, sync_hw_clock); 488 static struct hrtimer sync_hrtimer; 489 #define SYNC_PERIOD_NS (11ULL * 60 * NSEC_PER_SEC) 490 491 static enum hrtimer_restart sync_timer_callback(struct hrtimer *timer) 492 { 493 queue_work(system_freezable_power_efficient_wq, &sync_work); 494 495 return HRTIMER_NORESTART; 496 } 497 498 static void sched_sync_hw_clock(unsigned long offset_nsec, bool retry) 499 { 500 ktime_t exp = ktime_set(ktime_get_real_seconds(), 0); 501 502 if (retry) 503 exp = ktime_add_ns(exp, 2ULL * NSEC_PER_SEC - offset_nsec); 504 else 505 exp = ktime_add_ns(exp, SYNC_PERIOD_NS - offset_nsec); 506 507 hrtimer_start(&sync_hrtimer, exp, HRTIMER_MODE_ABS); 508 } 509 510 /* 511 * Check whether @now is correct versus the required time to update the RTC 512 * and calculate the value which needs to be written to the RTC so that the 513 * next seconds increment of the RTC after the write is aligned with the next 514 * seconds increment of clock REALTIME. 515 * 516 * tsched t1 write(t2.tv_sec - 1sec)) t2 RTC increments seconds 517 * 518 * t2.tv_nsec == 0 519 * tsched = t2 - set_offset_nsec 520 * newval = t2 - NSEC_PER_SEC 521 * 522 * ==> neval = tsched + set_offset_nsec - NSEC_PER_SEC 523 * 524 * As the execution of this code is not guaranteed to happen exactly at 525 * tsched this allows it to happen within a fuzzy region: 526 * 527 * abs(now - tsched) < FUZZ 528 * 529 * If @now is not inside the allowed window the function returns false. 530 */ 531 static inline bool rtc_tv_nsec_ok(unsigned long set_offset_nsec, 532 struct timespec64 *to_set, 533 const struct timespec64 *now) 534 { 535 /* Allowed error in tv_nsec, arbitrarily set to 5 jiffies in ns. */ 536 const unsigned long TIME_SET_NSEC_FUZZ = TICK_NSEC * 5; 537 struct timespec64 delay = {.tv_sec = -1, 538 .tv_nsec = set_offset_nsec}; 539 540 *to_set = timespec64_add(*now, delay); 541 542 if (to_set->tv_nsec < TIME_SET_NSEC_FUZZ) { 543 to_set->tv_nsec = 0; 544 return true; 545 } 546 547 if (to_set->tv_nsec > NSEC_PER_SEC - TIME_SET_NSEC_FUZZ) { 548 to_set->tv_sec++; 549 to_set->tv_nsec = 0; 550 return true; 551 } 552 return false; 553 } 554 555 #ifdef CONFIG_GENERIC_CMOS_UPDATE 556 int __weak update_persistent_clock64(struct timespec64 now64) 557 { 558 return -ENODEV; 559 } 560 #else 561 static inline int update_persistent_clock64(struct timespec64 now64) 562 { 563 return -ENODEV; 564 } 565 #endif 566 567 #ifdef CONFIG_RTC_SYSTOHC 568 /* Save NTP synchronized time to the RTC */ 569 static int update_rtc(struct timespec64 *to_set, unsigned long *offset_nsec) 570 { 571 struct rtc_device *rtc; 572 struct rtc_time tm; 573 int err = -ENODEV; 574 575 rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE); 576 if (!rtc) 577 return -ENODEV; 578 579 if (!rtc->ops || !rtc->ops->set_time) 580 goto out_close; 581 582 /* First call might not have the correct offset */ 583 if (*offset_nsec == rtc->set_offset_nsec) { 584 rtc_time64_to_tm(to_set->tv_sec, &tm); 585 err = rtc_set_time(rtc, &tm); 586 } else { 587 /* Store the update offset and let the caller try again */ 588 *offset_nsec = rtc->set_offset_nsec; 589 err = -EAGAIN; 590 } 591 out_close: 592 rtc_class_close(rtc); 593 return err; 594 } 595 #else 596 static inline int update_rtc(struct timespec64 *to_set, unsigned long *offset_nsec) 597 { 598 return -ENODEV; 599 } 600 #endif 601 602 /** 603 * ntp_synced - Tells whether the NTP status is not UNSYNC 604 * Returns: true if not UNSYNC, false otherwise 605 */ 606 static inline bool ntp_synced(void) 607 { 608 return !(tk_ntp_data.time_status & STA_UNSYNC); 609 } 610 611 /* 612 * If we have an externally synchronized Linux clock, then update RTC clock 613 * accordingly every ~11 minutes. Generally RTCs can only store second 614 * precision, but many RTCs will adjust the phase of their second tick to 615 * match the moment of update. This infrastructure arranges to call to the RTC 616 * set at the correct moment to phase synchronize the RTC second tick over 617 * with the kernel clock. 618 */ 619 static void sync_hw_clock(struct work_struct *work) 620 { 621 /* 622 * The default synchronization offset is 500ms for the deprecated 623 * update_persistent_clock64() under the assumption that it uses 624 * the infamous CMOS clock (MC146818). 625 */ 626 static unsigned long offset_nsec = NSEC_PER_SEC / 2; 627 struct timespec64 now, to_set; 628 int res = -EAGAIN; 629 630 /* 631 * Don't update if STA_UNSYNC is set and if ntp_notify_cmos_timer() 632 * managed to schedule the work between the timer firing and the 633 * work being able to rearm the timer. Wait for the timer to expire. 634 */ 635 if (!ntp_synced() || hrtimer_is_queued(&sync_hrtimer)) 636 return; 637 638 ktime_get_real_ts64(&now); 639 /* If @now is not in the allowed window, try again */ 640 if (!rtc_tv_nsec_ok(offset_nsec, &to_set, &now)) 641 goto rearm; 642 643 /* Take timezone adjusted RTCs into account */ 644 if (persistent_clock_is_local) 645 to_set.tv_sec -= (sys_tz.tz_minuteswest * 60); 646 647 /* Try the legacy RTC first. */ 648 res = update_persistent_clock64(to_set); 649 if (res != -ENODEV) 650 goto rearm; 651 652 /* Try the RTC class */ 653 res = update_rtc(&to_set, &offset_nsec); 654 if (res == -ENODEV) 655 return; 656 rearm: 657 sched_sync_hw_clock(offset_nsec, res != 0); 658 } 659 660 void ntp_notify_cmos_timer(bool offset_set) 661 { 662 /* 663 * If the time jumped (using ADJ_SETOFFSET) cancels sync timer, 664 * which may have been running if the time was synchronized 665 * prior to the ADJ_SETOFFSET call. 666 */ 667 if (offset_set) 668 hrtimer_cancel(&sync_hrtimer); 669 670 /* 671 * When the work is currently executed but has not yet the timer 672 * rearmed this queues the work immediately again. No big issue, 673 * just a pointless work scheduled. 674 */ 675 if (ntp_synced() && !hrtimer_is_queued(&sync_hrtimer)) 676 queue_work(system_freezable_power_efficient_wq, &sync_work); 677 } 678 679 static void __init ntp_init_cmos_sync(void) 680 { 681 hrtimer_init(&sync_hrtimer, CLOCK_REALTIME, HRTIMER_MODE_ABS); 682 sync_hrtimer.function = sync_timer_callback; 683 } 684 #else /* CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC) */ 685 static inline void __init ntp_init_cmos_sync(void) { } 686 #endif /* !CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC) */ 687 688 /* 689 * Propagate a new txc->status value into the NTP state: 690 */ 691 static inline void process_adj_status(struct ntp_data *ntpdata, const struct __kernel_timex *txc) 692 { 693 if ((ntpdata->time_status & STA_PLL) && !(txc->status & STA_PLL)) { 694 ntpdata->time_state = TIME_OK; 695 ntpdata->time_status = STA_UNSYNC; 696 ntpdata->ntp_next_leap_sec = TIME64_MAX; 697 /* Restart PPS frequency calibration */ 698 pps_reset_freq_interval(ntpdata); 699 } 700 701 /* 702 * If we turn on PLL adjustments then reset the 703 * reference time to current time. 704 */ 705 if (!(ntpdata->time_status & STA_PLL) && (txc->status & STA_PLL)) 706 ntpdata->time_reftime = __ktime_get_real_seconds(); 707 708 /* only set allowed bits */ 709 ntpdata->time_status &= STA_RONLY; 710 ntpdata->time_status |= txc->status & ~STA_RONLY; 711 } 712 713 static inline void process_adjtimex_modes(struct ntp_data *ntpdata, const struct __kernel_timex *txc, 714 s32 *time_tai) 715 { 716 if (txc->modes & ADJ_STATUS) 717 process_adj_status(ntpdata, txc); 718 719 if (txc->modes & ADJ_NANO) 720 ntpdata->time_status |= STA_NANO; 721 722 if (txc->modes & ADJ_MICRO) 723 ntpdata->time_status &= ~STA_NANO; 724 725 if (txc->modes & ADJ_FREQUENCY) { 726 ntpdata->time_freq = txc->freq * PPM_SCALE; 727 ntpdata->time_freq = min(ntpdata->time_freq, MAXFREQ_SCALED); 728 ntpdata->time_freq = max(ntpdata->time_freq, -MAXFREQ_SCALED); 729 /* Update pps_freq */ 730 pps_set_freq(ntpdata); 731 } 732 733 if (txc->modes & ADJ_MAXERROR) 734 ntpdata->time_maxerror = clamp(txc->maxerror, 0, NTP_PHASE_LIMIT); 735 736 if (txc->modes & ADJ_ESTERROR) 737 ntpdata->time_esterror = clamp(txc->esterror, 0, NTP_PHASE_LIMIT); 738 739 if (txc->modes & ADJ_TIMECONST) { 740 ntpdata->time_constant = clamp(txc->constant, 0, MAXTC); 741 if (!(ntpdata->time_status & STA_NANO)) 742 ntpdata->time_constant += 4; 743 ntpdata->time_constant = clamp(ntpdata->time_constant, 0, MAXTC); 744 } 745 746 if (txc->modes & ADJ_TAI && txc->constant >= 0 && txc->constant <= MAX_TAI_OFFSET) 747 *time_tai = txc->constant; 748 749 if (txc->modes & ADJ_OFFSET) 750 ntp_update_offset(ntpdata, txc->offset); 751 752 if (txc->modes & ADJ_TICK) 753 ntpdata->tick_usec = txc->tick; 754 755 if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET)) 756 ntp_update_frequency(ntpdata); 757 } 758 759 /* 760 * adjtimex() mainly allows reading (and writing, if superuser) of 761 * kernel time-keeping variables. used by xntpd. 762 */ 763 int __do_adjtimex(struct __kernel_timex *txc, const struct timespec64 *ts, 764 s32 *time_tai, struct audit_ntp_data *ad) 765 { 766 struct ntp_data *ntpdata = &tk_ntp_data; 767 int result; 768 769 if (txc->modes & ADJ_ADJTIME) { 770 long save_adjust = ntpdata->time_adjust; 771 772 if (!(txc->modes & ADJ_OFFSET_READONLY)) { 773 /* adjtime() is independent from ntp_adjtime() */ 774 ntpdata->time_adjust = txc->offset; 775 ntp_update_frequency(ntpdata); 776 777 audit_ntp_set_old(ad, AUDIT_NTP_ADJUST, save_adjust); 778 audit_ntp_set_new(ad, AUDIT_NTP_ADJUST, ntpdata->time_adjust); 779 } 780 txc->offset = save_adjust; 781 } else { 782 /* If there are input parameters, then process them: */ 783 if (txc->modes) { 784 audit_ntp_set_old(ad, AUDIT_NTP_OFFSET, ntpdata->time_offset); 785 audit_ntp_set_old(ad, AUDIT_NTP_FREQ, ntpdata->time_freq); 786 audit_ntp_set_old(ad, AUDIT_NTP_STATUS, ntpdata->time_status); 787 audit_ntp_set_old(ad, AUDIT_NTP_TAI, *time_tai); 788 audit_ntp_set_old(ad, AUDIT_NTP_TICK, ntpdata->tick_usec); 789 790 process_adjtimex_modes(ntpdata, txc, time_tai); 791 792 audit_ntp_set_new(ad, AUDIT_NTP_OFFSET, ntpdata->time_offset); 793 audit_ntp_set_new(ad, AUDIT_NTP_FREQ, ntpdata->time_freq); 794 audit_ntp_set_new(ad, AUDIT_NTP_STATUS, ntpdata->time_status); 795 audit_ntp_set_new(ad, AUDIT_NTP_TAI, *time_tai); 796 audit_ntp_set_new(ad, AUDIT_NTP_TICK, ntpdata->tick_usec); 797 } 798 799 txc->offset = shift_right(ntpdata->time_offset * NTP_INTERVAL_FREQ, NTP_SCALE_SHIFT); 800 if (!(ntpdata->time_status & STA_NANO)) 801 txc->offset = (u32)txc->offset / NSEC_PER_USEC; 802 } 803 804 result = ntpdata->time_state; 805 if (is_error_status(ntpdata->time_status)) 806 result = TIME_ERROR; 807 808 txc->freq = shift_right((ntpdata->time_freq >> PPM_SCALE_INV_SHIFT) * 809 PPM_SCALE_INV, NTP_SCALE_SHIFT); 810 txc->maxerror = ntpdata->time_maxerror; 811 txc->esterror = ntpdata->time_esterror; 812 txc->status = ntpdata->time_status; 813 txc->constant = ntpdata->time_constant; 814 txc->precision = 1; 815 txc->tolerance = MAXFREQ_SCALED / PPM_SCALE; 816 txc->tick = ntpdata->tick_usec; 817 txc->tai = *time_tai; 818 819 /* Fill PPS status fields */ 820 pps_fill_timex(ntpdata, txc); 821 822 txc->time.tv_sec = ts->tv_sec; 823 txc->time.tv_usec = ts->tv_nsec; 824 if (!(ntpdata->time_status & STA_NANO)) 825 txc->time.tv_usec = ts->tv_nsec / NSEC_PER_USEC; 826 827 /* Handle leapsec adjustments */ 828 if (unlikely(ts->tv_sec >= ntpdata->ntp_next_leap_sec)) { 829 if ((ntpdata->time_state == TIME_INS) && (ntpdata->time_status & STA_INS)) { 830 result = TIME_OOP; 831 txc->tai++; 832 txc->time.tv_sec--; 833 } 834 if ((ntpdata->time_state == TIME_DEL) && (ntpdata->time_status & STA_DEL)) { 835 result = TIME_WAIT; 836 txc->tai--; 837 txc->time.tv_sec++; 838 } 839 if ((ntpdata->time_state == TIME_OOP) && (ts->tv_sec == ntpdata->ntp_next_leap_sec)) 840 result = TIME_WAIT; 841 } 842 843 return result; 844 } 845 846 #ifdef CONFIG_NTP_PPS 847 848 /* 849 * struct pps_normtime is basically a struct timespec, but it is 850 * semantically different (and it is the reason why it was invented): 851 * pps_normtime.nsec has a range of ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ] 852 * while timespec.tv_nsec has a range of [0, NSEC_PER_SEC) 853 */ 854 struct pps_normtime { 855 s64 sec; /* seconds */ 856 long nsec; /* nanoseconds */ 857 }; 858 859 /* 860 * Normalize the timestamp so that nsec is in the 861 * [ -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ] interval 862 */ 863 static inline struct pps_normtime pps_normalize_ts(struct timespec64 ts) 864 { 865 struct pps_normtime norm = { 866 .sec = ts.tv_sec, 867 .nsec = ts.tv_nsec 868 }; 869 870 if (norm.nsec > (NSEC_PER_SEC >> 1)) { 871 norm.nsec -= NSEC_PER_SEC; 872 norm.sec++; 873 } 874 875 return norm; 876 } 877 878 /* Get current phase correction and jitter */ 879 static inline long pps_phase_filter_get(struct ntp_data *ntpdata, long *jitter) 880 { 881 *jitter = ntpdata->pps_tf[0] - ntpdata->pps_tf[1]; 882 if (*jitter < 0) 883 *jitter = -*jitter; 884 885 /* TODO: test various filters */ 886 return ntpdata->pps_tf[0]; 887 } 888 889 /* Add the sample to the phase filter */ 890 static inline void pps_phase_filter_add(struct ntp_data *ntpdata, long err) 891 { 892 ntpdata->pps_tf[2] = ntpdata->pps_tf[1]; 893 ntpdata->pps_tf[1] = ntpdata->pps_tf[0]; 894 ntpdata->pps_tf[0] = err; 895 } 896 897 /* 898 * Decrease frequency calibration interval length. It is halved after four 899 * consecutive unstable intervals. 900 */ 901 static inline void pps_dec_freq_interval(struct ntp_data *ntpdata) 902 { 903 if (--ntpdata->pps_intcnt <= -PPS_INTCOUNT) { 904 ntpdata->pps_intcnt = -PPS_INTCOUNT; 905 if (ntpdata->pps_shift > PPS_INTMIN) { 906 ntpdata->pps_shift--; 907 ntpdata->pps_intcnt = 0; 908 } 909 } 910 } 911 912 /* 913 * Increase frequency calibration interval length. It is doubled after 914 * four consecutive stable intervals. 915 */ 916 static inline void pps_inc_freq_interval(struct ntp_data *ntpdata) 917 { 918 if (++ntpdata->pps_intcnt >= PPS_INTCOUNT) { 919 ntpdata->pps_intcnt = PPS_INTCOUNT; 920 if (ntpdata->pps_shift < PPS_INTMAX) { 921 ntpdata->pps_shift++; 922 ntpdata->pps_intcnt = 0; 923 } 924 } 925 } 926 927 /* 928 * Update clock frequency based on MONOTONIC_RAW clock PPS signal 929 * timestamps 930 * 931 * At the end of the calibration interval the difference between the 932 * first and last MONOTONIC_RAW clock timestamps divided by the length 933 * of the interval becomes the frequency update. If the interval was 934 * too long, the data are discarded. 935 * Returns the difference between old and new frequency values. 936 */ 937 static long hardpps_update_freq(struct ntp_data *ntpdata, struct pps_normtime freq_norm) 938 { 939 long delta, delta_mod; 940 s64 ftemp; 941 942 /* Check if the frequency interval was too long */ 943 if (freq_norm.sec > (2 << ntpdata->pps_shift)) { 944 ntpdata->time_status |= STA_PPSERROR; 945 ntpdata->pps_errcnt++; 946 pps_dec_freq_interval(ntpdata); 947 printk_deferred(KERN_ERR "hardpps: PPSERROR: interval too long - %lld s\n", 948 freq_norm.sec); 949 return 0; 950 } 951 952 /* 953 * Here the raw frequency offset and wander (stability) is 954 * calculated. If the wander is less than the wander threshold the 955 * interval is increased; otherwise it is decreased. 956 */ 957 ftemp = div_s64(((s64)(-freq_norm.nsec)) << NTP_SCALE_SHIFT, 958 freq_norm.sec); 959 delta = shift_right(ftemp - ntpdata->pps_freq, NTP_SCALE_SHIFT); 960 ntpdata->pps_freq = ftemp; 961 if (delta > PPS_MAXWANDER || delta < -PPS_MAXWANDER) { 962 printk_deferred(KERN_WARNING "hardpps: PPSWANDER: change=%ld\n", delta); 963 ntpdata->time_status |= STA_PPSWANDER; 964 ntpdata->pps_stbcnt++; 965 pps_dec_freq_interval(ntpdata); 966 } else { 967 /* Good sample */ 968 pps_inc_freq_interval(ntpdata); 969 } 970 971 /* 972 * The stability metric is calculated as the average of recent 973 * frequency changes, but is used only for performance monitoring 974 */ 975 delta_mod = delta; 976 if (delta_mod < 0) 977 delta_mod = -delta_mod; 978 ntpdata->pps_stabil += (div_s64(((s64)delta_mod) << (NTP_SCALE_SHIFT - SHIFT_USEC), 979 NSEC_PER_USEC) - ntpdata->pps_stabil) >> PPS_INTMIN; 980 981 /* If enabled, the system clock frequency is updated */ 982 if ((ntpdata->time_status & STA_PPSFREQ) && !(ntpdata->time_status & STA_FREQHOLD)) { 983 ntpdata->time_freq = ntpdata->pps_freq; 984 ntp_update_frequency(ntpdata); 985 } 986 987 return delta; 988 } 989 990 /* Correct REALTIME clock phase error against PPS signal */ 991 static void hardpps_update_phase(struct ntp_data *ntpdata, long error) 992 { 993 long correction = -error; 994 long jitter; 995 996 /* Add the sample to the median filter */ 997 pps_phase_filter_add(ntpdata, correction); 998 correction = pps_phase_filter_get(ntpdata, &jitter); 999 1000 /* 1001 * Nominal jitter is due to PPS signal noise. If it exceeds the 1002 * threshold, the sample is discarded; otherwise, if so enabled, 1003 * the time offset is updated. 1004 */ 1005 if (jitter > (ntpdata->pps_jitter << PPS_POPCORN)) { 1006 printk_deferred(KERN_WARNING "hardpps: PPSJITTER: jitter=%ld, limit=%ld\n", 1007 jitter, (ntpdata->pps_jitter << PPS_POPCORN)); 1008 ntpdata->time_status |= STA_PPSJITTER; 1009 ntpdata->pps_jitcnt++; 1010 } else if (ntpdata->time_status & STA_PPSTIME) { 1011 /* Correct the time using the phase offset */ 1012 ntpdata->time_offset = div_s64(((s64)correction) << NTP_SCALE_SHIFT, 1013 NTP_INTERVAL_FREQ); 1014 /* Cancel running adjtime() */ 1015 ntpdata->time_adjust = 0; 1016 } 1017 /* Update jitter */ 1018 ntpdata->pps_jitter += (jitter - ntpdata->pps_jitter) >> PPS_INTMIN; 1019 } 1020 1021 /* 1022 * __hardpps() - discipline CPU clock oscillator to external PPS signal 1023 * 1024 * This routine is called at each PPS signal arrival in order to 1025 * discipline the CPU clock oscillator to the PPS signal. It takes two 1026 * parameters: REALTIME and MONOTONIC_RAW clock timestamps. The former 1027 * is used to correct clock phase error and the latter is used to 1028 * correct the frequency. 1029 * 1030 * This code is based on David Mills's reference nanokernel 1031 * implementation. It was mostly rewritten but keeps the same idea. 1032 */ 1033 void __hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts) 1034 { 1035 struct pps_normtime pts_norm, freq_norm; 1036 struct ntp_data *ntpdata = &tk_ntp_data; 1037 1038 pts_norm = pps_normalize_ts(*phase_ts); 1039 1040 /* Clear the error bits, they will be set again if needed */ 1041 ntpdata->time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR); 1042 1043 /* indicate signal presence */ 1044 ntpdata->time_status |= STA_PPSSIGNAL; 1045 ntpdata->pps_valid = PPS_VALID; 1046 1047 /* 1048 * When called for the first time, just start the frequency 1049 * interval 1050 */ 1051 if (unlikely(ntpdata->pps_fbase.tv_sec == 0)) { 1052 ntpdata->pps_fbase = *raw_ts; 1053 return; 1054 } 1055 1056 /* Ok, now we have a base for frequency calculation */ 1057 freq_norm = pps_normalize_ts(timespec64_sub(*raw_ts, ntpdata->pps_fbase)); 1058 1059 /* 1060 * Check that the signal is in the range 1061 * [1s - MAXFREQ us, 1s + MAXFREQ us], otherwise reject it 1062 */ 1063 if ((freq_norm.sec == 0) || (freq_norm.nsec > MAXFREQ * freq_norm.sec) || 1064 (freq_norm.nsec < -MAXFREQ * freq_norm.sec)) { 1065 ntpdata->time_status |= STA_PPSJITTER; 1066 /* Restart the frequency calibration interval */ 1067 ntpdata->pps_fbase = *raw_ts; 1068 printk_deferred(KERN_ERR "hardpps: PPSJITTER: bad pulse\n"); 1069 return; 1070 } 1071 1072 /* Signal is ok. Check if the current frequency interval is finished */ 1073 if (freq_norm.sec >= (1 << ntpdata->pps_shift)) { 1074 ntpdata->pps_calcnt++; 1075 /* Restart the frequency calibration interval */ 1076 ntpdata->pps_fbase = *raw_ts; 1077 hardpps_update_freq(ntpdata, freq_norm); 1078 } 1079 1080 hardpps_update_phase(ntpdata, pts_norm.nsec); 1081 1082 } 1083 #endif /* CONFIG_NTP_PPS */ 1084 1085 static int __init ntp_tick_adj_setup(char *str) 1086 { 1087 int rc = kstrtos64(str, 0, &tk_ntp_data.ntp_tick_adj); 1088 if (rc) 1089 return rc; 1090 1091 tk_ntp_data.ntp_tick_adj <<= NTP_SCALE_SHIFT; 1092 return 1; 1093 } 1094 1095 __setup("ntp_tick_adj=", ntp_tick_adj_setup); 1096 1097 void __init ntp_init(void) 1098 { 1099 ntp_clear(); 1100 ntp_init_cmos_sync(); 1101 } 1102