sys/kern/kern_tc.c

   1 /*-
   2  * SPDX-License-Identifier: Beerware
   3  *
   4  * ----------------------------------------------------------------------------
   5  * "THE BEER-WARE LICENSE" (Revision 42):
   6  * <phk@FreeBSD.ORG> wrote this file.  As long as you retain this notice you
   7  * can do whatever you want with this stuff. If we meet some day, and you think
   8  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
   9  * ----------------------------------------------------------------------------
  10  *
  11  * Copyright (c) 2011, 2015, 2016 The FreeBSD Foundation
  12  * All rights reserved.
  13  *
  14  * Portions of this software were developed by Julien Ridoux at the University
  15  * of Melbourne under sponsorship from the FreeBSD Foundation.
  16  *
  17  * Portions of this software were developed by Konstantin Belousov
  18  * under sponsorship from the FreeBSD Foundation.
  19  */
  20
  21 #include <sys/cdefs.h>
  22 __FBSDID("$FreeBSD$");
  23
  24 #include "opt_ntp.h"
  25 #include "opt_ffclock.h"
  26
  27 #include <sys/param.h>
  28 #include <sys/kernel.h>
  29 #include <sys/limits.h>
  30 #include <sys/lock.h>
  31 #include <sys/mutex.h>
  32 #include <sys/proc.h>
  33 #include <sys/sbuf.h>
  34 #include <sys/sleepqueue.h>
  35 #include <sys/sysctl.h>
  36 #include <sys/syslog.h>
  37 #include <sys/systm.h>
  38 #include <sys/timeffc.h>
  39 #include <sys/timepps.h>
  40 #include <sys/timetc.h>
  41 #include <sys/timex.h>
  42 #include <sys/vdso.h>
  43
  44 /*
  45  * A large step happens on boot.  This constant detects such steps.
  46  * It is relatively small so that ntp_update_second gets called enough
  47  * in the typical 'missed a couple of seconds' case, but doesn't loop
  48  * forever when the time step is large.
  49  */
  50 #define LARGE_STEP      200
  51
  52 /*
  53  * Implement a dummy timecounter which we can use until we get a real one
  54  * in the air.  This allows the console and other early stuff to use
  55  * time services.
  56  */
  57
  58 static u_int
  59 dummy_get_timecount(struct timecounter *tc)
  60 {
  61         static u_int now;
  62
  63         return (++now);
  64 }
  65
  66 static struct timecounter dummy_timecounter = {
  67         dummy_get_timecount, 0, ~0u, 1000000, "dummy", -1000000
  68 };
  69
  70 struct timehands {
  71         /* These fields must be initialized by the driver. */
  72         struct timecounter      *th_counter;
  73         int64_t                 th_adjustment;
  74         uint64_t                th_scale;
  75         u_int                   th_large_delta;
  76         u_int                   th_offset_count;
  77         struct bintime          th_offset;
  78         struct bintime          th_bintime;
  79         struct timeval          th_microtime;
  80         struct timespec         th_nanotime;
  81         struct bintime          th_boottime;
  82         /* Fields not to be copied in tc_windup start with th_generation. */
  83         u_int                   th_generation;
  84         struct timehands        *th_next;
  85 };
  86
  87 static struct timehands ths[16] = {
  88     [0] =  {
  89         .th_counter = &dummy_timecounter,
  90         .th_scale = (uint64_t)-1 / 1000000,
  91         .th_large_delta = 1000000,
  92         .th_offset = { .sec = 1 },
  93         .th_generation = 1,
  94     },
  95 };
  96
  97 static struct timehands *volatile timehands = &ths[0];
  98 struct timecounter *timecounter = &dummy_timecounter;
  99 static struct timecounter *timecounters = &dummy_timecounter;
 100
 101 int tc_min_ticktock_freq = 1;
 102
 103 volatile time_t time_second = 1;
 104 volatile time_t time_uptime = 1;
 105
 106 static int sysctl_kern_boottime(SYSCTL_HANDLER_ARGS);
 107 SYSCTL_PROC(_kern, KERN_BOOTTIME, boottime,
 108     CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
 109     sysctl_kern_boottime, "S,timeval",
 110     "System boottime");
 111
 112 SYSCTL_NODE(_kern, OID_AUTO, timecounter, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
 113     "");
 114 static SYSCTL_NODE(_kern_timecounter, OID_AUTO, tc,
 115     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
 116     "");
 117
 118 static int timestepwarnings;
 119 SYSCTL_INT(_kern_timecounter, OID_AUTO, stepwarnings, CTLFLAG_RW,
 120     &timestepwarnings, 0, "Log time steps");
 121
 122 static int timehands_count = 2;
 123 SYSCTL_INT(_kern_timecounter, OID_AUTO, timehands_count,
 124     CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
 125     &timehands_count, 0, "Count of timehands in rotation");
 126
 127 struct bintime bt_timethreshold;
 128 struct bintime bt_tickthreshold;
 129 sbintime_t sbt_timethreshold;
 130 sbintime_t sbt_tickthreshold;
 131 struct bintime tc_tick_bt;
 132 sbintime_t tc_tick_sbt;
 133 int tc_precexp;
 134 int tc_timepercentage = TC_DEFAULTPERC;
 135 static int sysctl_kern_timecounter_adjprecision(SYSCTL_HANDLER_ARGS);
 136 SYSCTL_PROC(_kern_timecounter, OID_AUTO, alloweddeviation,
 137     CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, 0, 0,
 138     sysctl_kern_timecounter_adjprecision, "I",
 139     "Allowed time interval deviation in percents");
 140
 141 volatile int rtc_generation = 1;
 142
 143 static int tc_chosen;   /* Non-zero if a specific tc was chosen via sysctl. */
 144 static char tc_from_tunable[16];
 145
 146 static void tc_windup(struct bintime *new_boottimebin);
 147 static void cpu_tick_calibrate(int);
 148
 149 void dtrace_getnanotime(struct timespec *tsp);
 150 void dtrace_getnanouptime(struct timespec *tsp);
 151
 152 static int
 153 sysctl_kern_boottime(SYSCTL_HANDLER_ARGS)
 154 {
 155         struct timeval boottime;
 156
 157         getboottime(&boottime);
 158
 159 /* i386 is the only arch which uses a 32bits time_t */
 160 #ifdef __amd64__
 161 #ifdef SCTL_MASK32
 162         int tv[2];
 163
 164         if (req->flags & SCTL_MASK32) {
 165                 tv[0] = boottime.tv_sec;
 166                 tv[1] = boottime.tv_usec;
 167                 return (SYSCTL_OUT(req, tv, sizeof(tv)));
 168         }
 169 #endif
 170 #endif
 171         return (SYSCTL_OUT(req, &boottime, sizeof(boottime)));
 172 }
 173
 174 static int
 175 sysctl_kern_timecounter_get(SYSCTL_HANDLER_ARGS)
 176 {
 177         u_int ncount;
 178         struct timecounter *tc = arg1;
 179
 180         ncount = tc->tc_get_timecount(tc);
 181         return (sysctl_handle_int(oidp, &ncount, 0, req));
 182 }
 183
 184 static int
 185 sysctl_kern_timecounter_freq(SYSCTL_HANDLER_ARGS)
 186 {
 187         uint64_t freq;
 188         struct timecounter *tc = arg1;
 189
 190         freq = tc->tc_frequency;
 191         return (sysctl_handle_64(oidp, &freq, 0, req));
 192 }
 193
 194 /*
 195  * Return the difference between the timehands' counter value now and what
 196  * was when we copied it to the timehands' offset_count.
 197  */
 198 static __inline u_int
 199 tc_delta(struct timehands *th)
 200 {
 201         struct timecounter *tc;
 202
 203         tc = th->th_counter;
 204         return ((tc->tc_get_timecount(tc) - th->th_offset_count) &
 205             tc->tc_counter_mask);
 206 }
 207
 208 /*
 209  * Functions for reading the time.  We have to loop until we are sure that
 210  * the timehands that we operated on was not updated under our feet.  See
 211  * the comment in <sys/time.h> for a description of these 12 functions.
 212  */
 213
 214 static __inline void
 215 bintime_off(struct bintime *bt, u_int off)
 216 {
 217         struct timehands *th;
 218         struct bintime *btp;
 219         uint64_t scale, x;
 220         u_int delta, gen, large_delta;
 221
 222         do {
 223                 th = timehands;
 224                 gen = atomic_load_acq_int(&th->th_generation);
 225                 btp = (struct bintime *)((vm_offset_t)th + off);
 226                 *bt = *btp;
 227                 scale = th->th_scale;
 228                 delta = tc_delta(th);
 229                 large_delta = th->th_large_delta;
 230                 atomic_thread_fence_acq();
 231         } while (gen == 0 || gen != th->th_generation);
 232
 233         if (__predict_false(delta >= large_delta)) {
 234                 /* Avoid overflow for scale * delta. */
 235                 x = (scale >> 32) * delta;
 236                 bt->sec += x >> 32;
 237                 bintime_addx(bt, x << 32);
 238                 bintime_addx(bt, (scale & 0xffffffff) * delta);
 239         } else {
 240                 bintime_addx(bt, scale * delta);
 241         }
 242 }
 243 #define GETTHBINTIME(dst, member)                                       \
 244 do {                                                                    \
 245         _Static_assert(_Generic(((struct timehands *)NULL)->member,     \
 246             struct bintime: 1, default: 0) == 1,                        \
 247             "struct timehands member is not of struct bintime type");   \
 248         bintime_off(dst, __offsetof(struct timehands, member));         \
 249 } while (0)
 250
 251 static __inline void
 252 getthmember(void *out, size_t out_size, u_int off)
 253 {
 254         struct timehands *th;
 255         u_int gen;
 256
 257         do {
 258                 th = timehands;
 259                 gen = atomic_load_acq_int(&th->th_generation);
 260                 memcpy(out, (char *)th + off, out_size);
 261                 atomic_thread_fence_acq();
 262         } while (gen == 0 || gen != th->th_generation);
 263 }
 264 #define GETTHMEMBER(dst, member)                                        \
 265 do {                                                                    \
 266         _Static_assert(_Generic(*dst,                                   \
 267             __typeof(((struct timehands *)NULL)->member): 1,            \
 268             default: 0) == 1,                                           \
 269             "*dst and struct timehands member have different types");   \
 270         getthmember(dst, sizeof(*dst), __offsetof(struct timehands,     \
 271             member));                                                   \
 272 } while (0)
 273
 274 #ifdef FFCLOCK
 275 void
 276 fbclock_binuptime(struct bintime *bt)
 277 {
 278
 279         GETTHBINTIME(bt, th_offset);
 280 }
 281
 282 void
 283 fbclock_nanouptime(struct timespec *tsp)
 284 {
 285         struct bintime bt;
 286
 287         fbclock_binuptime(&bt);
 288         bintime2timespec(&bt, tsp);
 289 }
 290
 291 void
 292 fbclock_microuptime(struct timeval *tvp)
 293 {
 294         struct bintime bt;
 295
 296         fbclock_binuptime(&bt);
 297         bintime2timeval(&bt, tvp);
 298 }
 299
 300 void
 301 fbclock_bintime(struct bintime *bt)
 302 {
 303
 304         GETTHBINTIME(bt, th_bintime);
 305 }
 306
 307 void
 308 fbclock_nanotime(struct timespec *tsp)
 309 {
 310         struct bintime bt;
 311
 312         fbclock_bintime(&bt);
 313         bintime2timespec(&bt, tsp);
 314 }
 315
 316 void
 317 fbclock_microtime(struct timeval *tvp)
 318 {
 319         struct bintime bt;
 320
 321         fbclock_bintime(&bt);
 322         bintime2timeval(&bt, tvp);
 323 }
 324
 325 void
 326 fbclock_getbinuptime(struct bintime *bt)
 327 {
 328
 329         GETTHMEMBER(bt, th_offset);
 330 }
 331
 332 void
 333 fbclock_getnanouptime(struct timespec *tsp)
 334 {
 335         struct bintime bt;
 336
 337         GETTHMEMBER(&bt, th_offset);
 338         bintime2timespec(&bt, tsp);
 339 }
 340
 341 void
 342 fbclock_getmicrouptime(struct timeval *tvp)
 343 {
 344         struct bintime bt;
 345
 346         GETTHMEMBER(&bt, th_offset);
 347         bintime2timeval(&bt, tvp);
 348 }
 349
 350 void
 351 fbclock_getbintime(struct bintime *bt)
 352 {
 353
 354         GETTHMEMBER(bt, th_bintime);
 355 }
 356
 357 void
 358 fbclock_getnanotime(struct timespec *tsp)
 359 {
 360
 361         GETTHMEMBER(tsp, th_nanotime);
 362 }
 363
 364 void
 365 fbclock_getmicrotime(struct timeval *tvp)
 366 {
 367
 368         GETTHMEMBER(tvp, th_microtime);
 369 }
 370 #else /* !FFCLOCK */
 371
 372 void
 373 binuptime(struct bintime *bt)
 374 {
 375
 376         GETTHBINTIME(bt, th_offset);
 377 }
 378
 379 void
 380 nanouptime(struct timespec *tsp)
 381 {
 382         struct bintime bt;
 383
 384         binuptime(&bt);
 385         bintime2timespec(&bt, tsp);
 386 }
 387
 388 void
 389 microuptime(struct timeval *tvp)
 390 {
 391         struct bintime bt;
 392
 393         binuptime(&bt);
 394         bintime2timeval(&bt, tvp);
 395 }
 396
 397 void
 398 bintime(struct bintime *bt)
 399 {
 400
 401         GETTHBINTIME(bt, th_bintime);
 402 }
 403
 404 void
 405 nanotime(struct timespec *tsp)
 406 {
 407         struct bintime bt;
 408
 409         bintime(&bt);
 410         bintime2timespec(&bt, tsp);
 411 }
 412
 413 void
 414 microtime(struct timeval *tvp)
 415 {
 416         struct bintime bt;
 417
 418         bintime(&bt);
 419         bintime2timeval(&bt, tvp);
 420 }
 421
 422 void
 423 getbinuptime(struct bintime *bt)
 424 {
 425
 426         GETTHMEMBER(bt, th_offset);
 427 }
 428
 429 void
 430 getnanouptime(struct timespec *tsp)
 431 {
 432         struct bintime bt;
 433
 434         GETTHMEMBER(&bt, th_offset);
 435         bintime2timespec(&bt, tsp);
 436 }
 437
 438 void
 439 getmicrouptime(struct timeval *tvp)
 440 {
 441         struct bintime bt;
 442
 443         GETTHMEMBER(&bt, th_offset);
 444         bintime2timeval(&bt, tvp);
 445 }
 446
 447 void
 448 getbintime(struct bintime *bt)
 449 {
 450
 451         GETTHMEMBER(bt, th_bintime);
 452 }
 453
 454 void
 455 getnanotime(struct timespec *tsp)
 456 {
 457
 458         GETTHMEMBER(tsp, th_nanotime);
 459 }
 460
 461 void
 462 getmicrotime(struct timeval *tvp)
 463 {
 464
 465         GETTHMEMBER(tvp, th_microtime);
 466 }
 467 #endif /* FFCLOCK */
 468
 469 void
 470 getboottime(struct timeval *boottime)
 471 {
 472         struct bintime boottimebin;
 473
 474         getboottimebin(&boottimebin);
 475         bintime2timeval(&boottimebin, boottime);
 476 }
 477
 478 void
 479 getboottimebin(struct bintime *boottimebin)
 480 {
 481
 482         GETTHMEMBER(boottimebin, th_boottime);
 483 }
 484
 485 #ifdef FFCLOCK
 486 /*
 487  * Support for feed-forward synchronization algorithms. This is heavily inspired
 488  * by the timehands mechanism but kept independent from it. *_windup() functions
 489  * have some connection to avoid accessing the timecounter hardware more than
 490  * necessary.
 491  */
 492
 493 /* Feed-forward clock estimates kept updated by the synchronization daemon. */
 494 struct ffclock_estimate ffclock_estimate;
 495 struct bintime ffclock_boottime;        /* Feed-forward boot time estimate. */
 496 uint32_t ffclock_status;                /* Feed-forward clock status. */
 497 int8_t ffclock_updated;                 /* New estimates are available. */
 498 struct mtx ffclock_mtx;                 /* Mutex on ffclock_estimate. */
 499
 500 struct fftimehands {
 501         struct ffclock_estimate cest;
 502         struct bintime          tick_time;
 503         struct bintime          tick_time_lerp;
 504         ffcounter               tick_ffcount;
 505         uint64_t                period_lerp;
 506         volatile uint8_t        gen;
 507         struct fftimehands      *next;
 508 };
 509
 510 #define NUM_ELEMENTS(x) (sizeof(x) / sizeof(*x))
 511
 512 static struct fftimehands ffth[10];
 513 static struct fftimehands *volatile fftimehands = ffth;
 514
 515 static void
 516 ffclock_init(void)
 517 {
 518         struct fftimehands *cur;
 519         struct fftimehands *last;
 520
 521         memset(ffth, 0, sizeof(ffth));
 522
 523         last = ffth + NUM_ELEMENTS(ffth) - 1;
 524         for (cur = ffth; cur < last; cur++)
 525                 cur->next = cur + 1;
 526         last->next = ffth;
 527
 528         ffclock_updated = 0;
 529         ffclock_status = FFCLOCK_STA_UNSYNC;
 530         mtx_init(&ffclock_mtx, "ffclock lock", NULL, MTX_DEF);
 531 }
 532
 533 /*
 534  * Reset the feed-forward clock estimates. Called from inittodr() to get things
 535  * kick started and uses the timecounter nominal frequency as a first period
 536  * estimate. Note: this function may be called several time just after boot.
 537  * Note: this is the only function that sets the value of boot time for the
 538  * monotonic (i.e. uptime) version of the feed-forward clock.
 539  */
 540 void
 541 ffclock_reset_clock(struct timespec *ts)
 542 {
 543         struct timecounter *tc;
 544         struct ffclock_estimate cest;
 545
 546         tc = timehands->th_counter;
 547         memset(&cest, 0, sizeof(struct ffclock_estimate));
 548
 549         timespec2bintime(ts, &ffclock_boottime);
 550         timespec2bintime(ts, &(cest.update_time));
 551         ffclock_read_counter(&cest.update_ffcount);
 552         cest.leapsec_next = 0;
 553         cest.period = ((1ULL << 63) / tc->tc_frequency) << 1;
 554         cest.errb_abs = 0;
 555         cest.errb_rate = 0;
 556         cest.status = FFCLOCK_STA_UNSYNC;
 557         cest.leapsec_total = 0;
 558         cest.leapsec = 0;
 559
 560         mtx_lock(&ffclock_mtx);
 561         bcopy(&cest, &ffclock_estimate, sizeof(struct ffclock_estimate));
 562         ffclock_updated = INT8_MAX;
 563         mtx_unlock(&ffclock_mtx);
 564
 565         printf("ffclock reset: %s (%llu Hz), time = %ld.%09lu\n", tc->tc_name,
 566             (unsigned long long)tc->tc_frequency, (long)ts->tv_sec,
 567             (unsigned long)ts->tv_nsec);
 568 }
 569
 570 /*
 571  * Sub-routine to convert a time interval measured in RAW counter units to time
 572  * in seconds stored in bintime format.
 573  * NOTE: bintime_mul requires u_int, but the value of the ffcounter may be
 574  * larger than the max value of u_int (on 32 bit architecture). Loop to consume
 575  * extra cycles.
 576  */
 577 static void
 578 ffclock_convert_delta(ffcounter ffdelta, uint64_t period, struct bintime *bt)
 579 {
 580         struct bintime bt2;
 581         ffcounter delta, delta_max;
 582
 583         delta_max = (1ULL << (8 * sizeof(unsigned int))) - 1;
 584         bintime_clear(bt);
 585         do {
 586                 if (ffdelta > delta_max)
 587                         delta = delta_max;
 588                 else
 589                         delta = ffdelta;
 590                 bt2.sec = 0;
 591                 bt2.frac = period;
 592                 bintime_mul(&bt2, (unsigned int)delta);
 593                 bintime_add(bt, &bt2);
 594                 ffdelta -= delta;
 595         } while (ffdelta > 0);
 596 }
 597
 598 /*
 599  * Update the fftimehands.
 600  * Push the tick ffcount and time(s) forward based on current clock estimate.
 601  * The conversion from ffcounter to bintime relies on the difference clock
 602  * principle, whose accuracy relies on computing small time intervals. If a new
 603  * clock estimate has been passed by the synchronisation daemon, make it
 604  * current, and compute the linear interpolation for monotonic time if needed.
 605  */
 606 static void
 607 ffclock_windup(unsigned int delta)
 608 {
 609         struct ffclock_estimate *cest;
 610         struct fftimehands *ffth;
 611         struct bintime bt, gap_lerp;
 612         ffcounter ffdelta;
 613         uint64_t frac;
 614         unsigned int polling;
 615         uint8_t forward_jump, ogen;
 616
 617         /*
 618          * Pick the next timehand, copy current ffclock estimates and move tick
 619          * times and counter forward.
 620          */
 621         forward_jump = 0;
 622         ffth = fftimehands->next;
 623         ogen = ffth->gen;
 624         ffth->gen = 0;
 625         cest = &ffth->cest;
 626         bcopy(&fftimehands->cest, cest, sizeof(struct ffclock_estimate));
 627         ffdelta = (ffcounter)delta;
 628         ffth->period_lerp = fftimehands->period_lerp;
 629
 630         ffth->tick_time = fftimehands->tick_time;
 631         ffclock_convert_delta(ffdelta, cest->period, &bt);
 632         bintime_add(&ffth->tick_time, &bt);
 633
 634         ffth->tick_time_lerp = fftimehands->tick_time_lerp;
 635         ffclock_convert_delta(ffdelta, ffth->period_lerp, &bt);
 636         bintime_add(&ffth->tick_time_lerp, &bt);
 637
 638         ffth->tick_ffcount = fftimehands->tick_ffcount + ffdelta;
 639
 640         /*
 641          * Assess the status of the clock, if the last update is too old, it is
 642          * likely the synchronisation daemon is dead and the clock is free
 643          * running.
 644          */
 645         if (ffclock_updated == 0) {
 646                 ffdelta = ffth->tick_ffcount - cest->update_ffcount;
 647                 ffclock_convert_delta(ffdelta, cest->period, &bt);
 648                 if (bt.sec > 2 * FFCLOCK_SKM_SCALE)
 649                         ffclock_status |= FFCLOCK_STA_UNSYNC;
 650         }
 651
 652         /*
 653          * If available, grab updated clock estimates and make them current.
 654          * Recompute time at this tick using the updated estimates. The clock
 655          * estimates passed the feed-forward synchronisation daemon may result
 656          * in time conversion that is not monotonically increasing (just after
 657          * the update). time_lerp is a particular linear interpolation over the
 658          * synchronisation algo polling period that ensures monotonicity for the
 659          * clock ids requesting it.
 660          */
 661         if (ffclock_updated > 0) {
 662                 bcopy(&ffclock_estimate, cest, sizeof(struct ffclock_estimate));
 663                 ffdelta = ffth->tick_ffcount - cest->update_ffcount;
 664                 ffth->tick_time = cest->update_time;
 665                 ffclock_convert_delta(ffdelta, cest->period, &bt);
 666                 bintime_add(&ffth->tick_time, &bt);
 667
 668                 /* ffclock_reset sets ffclock_updated to INT8_MAX */
 669                 if (ffclock_updated == INT8_MAX)
 670                         ffth->tick_time_lerp = ffth->tick_time;
 671
 672                 if (bintime_cmp(&ffth->tick_time, &ffth->tick_time_lerp, >))
 673                         forward_jump = 1;
 674                 else
 675                         forward_jump = 0;
 676
 677                 bintime_clear(&gap_lerp);
 678                 if (forward_jump) {
 679                         gap_lerp = ffth->tick_time;
 680                         bintime_sub(&gap_lerp, &ffth->tick_time_lerp);
 681                 } else {
 682                         gap_lerp = ffth->tick_time_lerp;
 683                         bintime_sub(&gap_lerp, &ffth->tick_time);
 684                 }
 685
 686                 /*
 687                  * The reset from the RTC clock may be far from accurate, and
 688                  * reducing the gap between real time and interpolated time
 689                  * could take a very long time if the interpolated clock insists
 690                  * on strict monotonicity. The clock is reset under very strict
 691                  * conditions (kernel time is known to be wrong and
 692                  * synchronization daemon has been restarted recently.
 693                  * ffclock_boottime absorbs the jump to ensure boot time is
 694                  * correct and uptime functions stay consistent.
 695                  */
 696                 if (((ffclock_status & FFCLOCK_STA_UNSYNC) == FFCLOCK_STA_UNSYNC) &&
 697                     ((cest->status & FFCLOCK_STA_UNSYNC) == 0) &&
 698                     ((cest->status & FFCLOCK_STA_WARMUP) == FFCLOCK_STA_WARMUP)) {
 699                         if (forward_jump)
 700                                 bintime_add(&ffclock_boottime, &gap_lerp);
 701                         else
 702                                 bintime_sub(&ffclock_boottime, &gap_lerp);
 703                         ffth->tick_time_lerp = ffth->tick_time;
 704                         bintime_clear(&gap_lerp);
 705                 }
 706
 707                 ffclock_status = cest->status;
 708                 ffth->period_lerp = cest->period;
 709
 710                 /*
 711                  * Compute corrected period used for the linear interpolation of
 712                  * time. The rate of linear interpolation is capped to 5000PPM
 713                  * (5ms/s).
 714                  */
 715                 if (bintime_isset(&gap_lerp)) {
 716                         ffdelta = cest->update_ffcount;
 717                         ffdelta -= fftimehands->cest.update_ffcount;
 718                         ffclock_convert_delta(ffdelta, cest->period, &bt);
 719                         polling = bt.sec;
 720                         bt.sec = 0;
 721                         bt.frac = 5000000 * (uint64_t)18446744073LL;
 722                         bintime_mul(&bt, polling);
 723                         if (bintime_cmp(&gap_lerp, &bt, >))
 724                                 gap_lerp = bt;
 725
 726                         /* Approximate 1 sec by 1-(1/2^64) to ease arithmetic */
 727                         frac = 0;
 728                         if (gap_lerp.sec > 0) {
 729                                 frac -= 1;
 730                                 frac /= ffdelta / gap_lerp.sec;
 731                         }
 732                         frac += gap_lerp.frac / ffdelta;
 733
 734                         if (forward_jump)
 735                                 ffth->period_lerp += frac;
 736                         else
 737                                 ffth->period_lerp -= frac;
 738                 }
 739
 740                 ffclock_updated = 0;
 741         }
 742         if (++ogen == 0)
 743                 ogen = 1;
 744         ffth->gen = ogen;
 745         fftimehands = ffth;
 746 }
 747
 748 /*
 749  * Adjust the fftimehands when the timecounter is changed. Stating the obvious,
 750  * the old and new hardware counter cannot be read simultaneously. tc_windup()
 751  * does read the two counters 'back to back', but a few cycles are effectively
 752  * lost, and not accumulated in tick_ffcount. This is a fairly radical
 753  * operation for a feed-forward synchronization daemon, and it is its job to not
 754  * pushing irrelevant data to the kernel. Because there is no locking here,
 755  * simply force to ignore pending or next update to give daemon a chance to
 756  * realize the counter has changed.
 757  */
 758 static void
 759 ffclock_change_tc(struct timehands *th)
 760 {
 761         struct fftimehands *ffth;
 762         struct ffclock_estimate *cest;
 763         struct timecounter *tc;
 764         uint8_t ogen;
 765
 766         tc = th->th_counter;
 767         ffth = fftimehands->next;
 768         ogen = ffth->gen;
 769         ffth->gen = 0;
 770
 771         cest = &ffth->cest;
 772         bcopy(&(fftimehands->cest), cest, sizeof(struct ffclock_estimate));
 773         cest->period = ((1ULL << 63) / tc->tc_frequency ) << 1;
 774         cest->errb_abs = 0;
 775         cest->errb_rate = 0;
 776         cest->status |= FFCLOCK_STA_UNSYNC;
 777
 778         ffth->tick_ffcount = fftimehands->tick_ffcount;
 779         ffth->tick_time_lerp = fftimehands->tick_time_lerp;
 780         ffth->tick_time = fftimehands->tick_time;
 781         ffth->period_lerp = cest->period;
 782
 783         /* Do not lock but ignore next update from synchronization daemon. */
 784         ffclock_updated--;
 785
 786         if (++ogen == 0)
 787                 ogen = 1;
 788         ffth->gen = ogen;
 789         fftimehands = ffth;
 790 }
 791
 792 /*
 793  * Retrieve feed-forward counter and time of last kernel tick.
 794  */
 795 void
 796 ffclock_last_tick(ffcounter *ffcount, struct bintime *bt, uint32_t flags)
 797 {
 798         struct fftimehands *ffth;
 799         uint8_t gen;
 800
 801         /*
 802          * No locking but check generation has not changed. Also need to make
 803          * sure ffdelta is positive, i.e. ffcount > tick_ffcount.
 804          */
 805         do {
 806                 ffth = fftimehands;
 807                 gen = ffth->gen;
 808                 if ((flags & FFCLOCK_LERP) == FFCLOCK_LERP)
 809                         *bt = ffth->tick_time_lerp;
 810                 else
 811                         *bt = ffth->tick_time;
 812                 *ffcount = ffth->tick_ffcount;
 813         } while (gen == 0 || gen != ffth->gen);
 814 }
 815
 816 /*
 817  * Absolute clock conversion. Low level function to convert ffcounter to
 818  * bintime. The ffcounter is converted using the current ffclock period estimate
 819  * or the "interpolated period" to ensure monotonicity.
 820  * NOTE: this conversion may have been deferred, and the clock updated since the
 821  * hardware counter has been read.
 822  */
 823 void
 824 ffclock_convert_abs(ffcounter ffcount, struct bintime *bt, uint32_t flags)
 825 {
 826         struct fftimehands *ffth;
 827         struct bintime bt2;
 828         ffcounter ffdelta;
 829         uint8_t gen;
 830
 831         /*
 832          * No locking but check generation has not changed. Also need to make
 833          * sure ffdelta is positive, i.e. ffcount > tick_ffcount.
 834          */
 835         do {
 836                 ffth = fftimehands;
 837                 gen = ffth->gen;
 838                 if (ffcount > ffth->tick_ffcount)
 839                         ffdelta = ffcount - ffth->tick_ffcount;
 840                 else
 841                         ffdelta = ffth->tick_ffcount - ffcount;
 842
 843                 if ((flags & FFCLOCK_LERP) == FFCLOCK_LERP) {
 844                         *bt = ffth->tick_time_lerp;
 845                         ffclock_convert_delta(ffdelta, ffth->period_lerp, &bt2);
 846                 } else {
 847                         *bt = ffth->tick_time;
 848                         ffclock_convert_delta(ffdelta, ffth->cest.period, &bt2);
 849                 }
 850
 851                 if (ffcount > ffth->tick_ffcount)
 852                         bintime_add(bt, &bt2);
 853                 else
 854                         bintime_sub(bt, &bt2);
 855         } while (gen == 0 || gen != ffth->gen);
 856 }
 857
 858 /*
 859  * Difference clock conversion.
 860  * Low level function to Convert a time interval measured in RAW counter units
 861  * into bintime. The difference clock allows measuring small intervals much more
 862  * reliably than the absolute clock.
 863  */
 864 void
 865 ffclock_convert_diff(ffcounter ffdelta, struct bintime *bt)
 866 {
 867         struct fftimehands *ffth;
 868         uint8_t gen;
 869
 870         /* No locking but check generation has not changed. */
 871         do {
 872                 ffth = fftimehands;
 873                 gen = ffth->gen;
 874                 ffclock_convert_delta(ffdelta, ffth->cest.period, bt);
 875         } while (gen == 0 || gen != ffth->gen);
 876 }
 877
 878 /*
 879  * Access to current ffcounter value.
 880  */
 881 void
 882 ffclock_read_counter(ffcounter *ffcount)
 883 {
 884         struct timehands *th;
 885         struct fftimehands *ffth;
 886         unsigned int gen, delta;
 887
 888         /*
 889          * ffclock_windup() called from tc_windup(), safe to rely on
 890          * th->th_generation only, for correct delta and ffcounter.
 891          */
 892         do {
 893                 th = timehands;
 894                 gen = atomic_load_acq_int(&th->th_generation);
 895                 ffth = fftimehands;
 896                 delta = tc_delta(th);
 897                 *ffcount = ffth->tick_ffcount;
 898                 atomic_thread_fence_acq();
 899         } while (gen == 0 || gen != th->th_generation);
 900
 901         *ffcount += delta;
 902 }
 903
 904 void
 905 binuptime(struct bintime *bt)
 906 {
 907
 908         binuptime_fromclock(bt, sysclock_active);
 909 }
 910
 911 void
 912 nanouptime(struct timespec *tsp)
 913 {
 914
 915         nanouptime_fromclock(tsp, sysclock_active);
 916 }
 917
 918 void
 919 microuptime(struct timeval *tvp)
 920 {
 921
 922         microuptime_fromclock(tvp, sysclock_active);
 923 }
 924
 925 void
 926 bintime(struct bintime *bt)
 927 {
 928
 929         bintime_fromclock(bt, sysclock_active);
 930 }
 931
 932 void
 933 nanotime(struct timespec *tsp)
 934 {
 935
 936         nanotime_fromclock(tsp, sysclock_active);
 937 }
 938
 939 void
 940 microtime(struct timeval *tvp)
 941 {
 942
 943         microtime_fromclock(tvp, sysclock_active);
 944 }
 945
 946 void
 947 getbinuptime(struct bintime *bt)
 948 {
 949
 950         getbinuptime_fromclock(bt, sysclock_active);
 951 }
 952
 953 void
 954 getnanouptime(struct timespec *tsp)
 955 {
 956
 957         getnanouptime_fromclock(tsp, sysclock_active);
 958 }
 959
 960 void
 961 getmicrouptime(struct timeval *tvp)
 962 {
 963
 964         getmicrouptime_fromclock(tvp, sysclock_active);
 965 }
 966
 967 void
 968 getbintime(struct bintime *bt)
 969 {
 970
 971         getbintime_fromclock(bt, sysclock_active);
 972 }
 973
 974 void
 975 getnanotime(struct timespec *tsp)
 976 {
 977
 978         getnanotime_fromclock(tsp, sysclock_active);
 979 }
 980
 981 void
 982 getmicrotime(struct timeval *tvp)
 983 {
 984
 985         getmicrouptime_fromclock(tvp, sysclock_active);
 986 }
 987
 988 #endif /* FFCLOCK */
 989
 990 /*
 991  * This is a clone of getnanotime and used for walltimestamps.
 992  * The dtrace_ prefix prevents fbt from creating probes for
 993  * it so walltimestamp can be safely used in all fbt probes.
 994  */
 995 void
 996 dtrace_getnanotime(struct timespec *tsp)
 997 {
 998
 999         GETTHMEMBER(tsp, th_nanotime);
1000 }
1001
1002 /*
1003  * This is a clone of getnanouptime used for time since boot.
1004  * The dtrace_ prefix prevents fbt from creating probes for
1005  * it so an uptime that can be safely used in all fbt probes.
1006  */
1007 void
1008 dtrace_getnanouptime(struct timespec *tsp)
1009 {
1010         struct bintime bt;
1011
1012         GETTHMEMBER(&bt, th_offset);
1013         bintime2timespec(&bt, tsp);
1014 }
1015
1016 /*
1017  * System clock currently providing time to the system. Modifiable via sysctl
1018  * when the FFCLOCK option is defined.
1019  */
1020 int sysclock_active = SYSCLOCK_FBCK;
1021
1022 /* Internal NTP status and error estimates. */
1023 extern int time_status;
1024 extern long time_esterror;
1025
1026 /*
1027  * Take a snapshot of sysclock data which can be used to compare system clocks
1028  * and generate timestamps after the fact.
1029  */
1030 void
1031 sysclock_getsnapshot(struct sysclock_snap *clock_snap, int fast)
1032 {
1033         struct fbclock_info *fbi;
1034         struct timehands *th;
1035         struct bintime bt;
1036         unsigned int delta, gen;
1037 #ifdef FFCLOCK
1038         ffcounter ffcount;
1039         struct fftimehands *ffth;
1040         struct ffclock_info *ffi;
1041         struct ffclock_estimate cest;
1042
1043         ffi = &clock_snap->ff_info;
1044 #endif
1045
1046         fbi = &clock_snap->fb_info;
1047         delta = 0;
1048
1049         do {
1050                 th = timehands;
1051                 gen = atomic_load_acq_int(&th->th_generation);
1052                 fbi->th_scale = th->th_scale;
1053                 fbi->tick_time = th->th_offset;
1054 #ifdef FFCLOCK
1055                 ffth = fftimehands;
1056                 ffi->tick_time = ffth->tick_time_lerp;
1057                 ffi->tick_time_lerp = ffth->tick_time_lerp;
1058                 ffi->period = ffth->cest.period;
1059                 ffi->period_lerp = ffth->period_lerp;
1060                 clock_snap->ffcount = ffth->tick_ffcount;
1061                 cest = ffth->cest;
1062 #endif
1063                 if (!fast)
1064                         delta = tc_delta(th);
1065                 atomic_thread_fence_acq();
1066         } while (gen == 0 || gen != th->th_generation);
1067
1068         clock_snap->delta = delta;
1069         clock_snap->sysclock_active = sysclock_active;
1070
1071         /* Record feedback clock status and error. */
1072         clock_snap->fb_info.status = time_status;
1073         /* XXX: Very crude estimate of feedback clock error. */
1074         bt.sec = time_esterror / 1000000;
1075         bt.frac = ((time_esterror - bt.sec) * 1000000) *
1076             (uint64_t)18446744073709ULL;
1077         clock_snap->fb_info.error = bt;
1078
1079 #ifdef FFCLOCK
1080         if (!fast)
1081                 clock_snap->ffcount += delta;
1082
1083         /* Record feed-forward clock leap second adjustment. */
1084         ffi->leapsec_adjustment = cest.leapsec_total;
1085         if (clock_snap->ffcount > cest.leapsec_next)
1086                 ffi->leapsec_adjustment -= cest.leapsec;
1087
1088         /* Record feed-forward clock status and error. */
1089         clock_snap->ff_info.status = cest.status;
1090         ffcount = clock_snap->ffcount - cest.update_ffcount;
1091         ffclock_convert_delta(ffcount, cest.period, &bt);
1092         /* 18446744073709 = int(2^64/1e12), err_bound_rate in [ps/s]. */
1093         bintime_mul(&bt, cest.errb_rate * (uint64_t)18446744073709ULL);
1094         /* 18446744073 = int(2^64 / 1e9), since err_abs in [ns]. */
1095         bintime_addx(&bt, cest.errb_abs * (uint64_t)18446744073ULL);
1096         clock_snap->ff_info.error = bt;
1097 #endif
1098 }
1099
1100 /*
1101  * Convert a sysclock snapshot into a struct bintime based on the specified
1102  * clock source and flags.
1103  */
1104 int
1105 sysclock_snap2bintime(struct sysclock_snap *cs, struct bintime *bt,
1106     int whichclock, uint32_t flags)
1107 {
1108         struct bintime boottimebin;
1109 #ifdef FFCLOCK
1110         struct bintime bt2;
1111         uint64_t period;
1112 #endif
1113
1114         switch (whichclock) {
1115         case SYSCLOCK_FBCK:
1116                 *bt = cs->fb_info.tick_time;
1117
1118                 /* If snapshot was created with !fast, delta will be >0. */
1119                 if (cs->delta > 0)
1120                         bintime_addx(bt, cs->fb_info.th_scale * cs->delta);
1121
1122                 if ((flags & FBCLOCK_UPTIME) == 0) {
1123                         getboottimebin(&boottimebin);
1124                         bintime_add(bt, &boottimebin);
1125                 }
1126                 break;
1127 #ifdef FFCLOCK
1128         case SYSCLOCK_FFWD:
1129                 if (flags & FFCLOCK_LERP) {
1130                         *bt = cs->ff_info.tick_time_lerp;
1131                         period = cs->ff_info.period_lerp;
1132                 } else {
1133                         *bt = cs->ff_info.tick_time;
1134                         period = cs->ff_info.period;
1135                 }
1136
1137                 /* If snapshot was created with !fast, delta will be >0. */
1138                 if (cs->delta > 0) {
1139                         ffclock_convert_delta(cs->delta, period, &bt2);
1140                         bintime_add(bt, &bt2);
1141                 }
1142
1143                 /* Leap second adjustment. */
1144                 if (flags & FFCLOCK_LEAPSEC)
1145                         bt->sec -= cs->ff_info.leapsec_adjustment;
1146
1147                 /* Boot time adjustment, for uptime/monotonic clocks. */
1148                 if (flags & FFCLOCK_UPTIME)
1149                         bintime_sub(bt, &ffclock_boottime);
1150                 break;
1151 #endif
1152         default:
1153                 return (EINVAL);
1154                 break;
1155         }
1156
1157         return (0);
1158 }
1159
1160 /*
1161  * Initialize a new timecounter and possibly use it.
1162  */
1163 void
1164 tc_init(struct timecounter *tc)
1165 {
1166         u_int u;
1167         struct sysctl_oid *tc_root;
1168
1169         u = tc->tc_frequency / tc->tc_counter_mask;
1170         /* XXX: We need some margin here, 10% is a guess */
1171         u *= 11;
1172         u /= 10;
1173         if (u > hz && tc->tc_quality >= 0) {
1174                 tc->tc_quality = -2000;
1175                 if (bootverbose) {
1176                         printf("Timecounter \"%s\" frequency %ju Hz",
1177                             tc->tc_name, (uintmax_t)tc->tc_frequency);
1178                         printf(" -- Insufficient hz, needs at least %u\n", u);
1179                 }
1180         } else if (tc->tc_quality >= 0 || bootverbose) {
1181                 printf("Timecounter \"%s\" frequency %ju Hz quality %d\n",
1182                     tc->tc_name, (uintmax_t)tc->tc_frequency,
1183                     tc->tc_quality);
1184         }
1185
1186         tc->tc_next = timecounters;
1187         timecounters = tc;
1188         /*
1189          * Set up sysctl tree for this counter.
1190          */
1191         tc_root = SYSCTL_ADD_NODE_WITH_LABEL(NULL,
1192             SYSCTL_STATIC_CHILDREN(_kern_timecounter_tc), OID_AUTO, tc->tc_name,
1193             CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
1194             "timecounter description", "timecounter");
1195         SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
1196             "mask", CTLFLAG_RD, &(tc->tc_counter_mask), 0,
1197             "mask for implemented bits");
1198         SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
1199             "counter", CTLTYPE_UINT | CTLFLAG_RD | CTLFLAG_MPSAFE, tc,
1200             sizeof(*tc), sysctl_kern_timecounter_get, "IU",
1201             "current timecounter value");
1202         SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
1203             "frequency", CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, tc,
1204             sizeof(*tc), sysctl_kern_timecounter_freq, "QU",
1205             "timecounter frequency");
1206         SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
1207             "quality", CTLFLAG_RD, &(tc->tc_quality), 0,
1208             "goodness of time counter");
1209         /*
1210          * Do not automatically switch if the current tc was specifically
1211          * chosen.  Never automatically use a timecounter with negative quality.
1212          * Even though we run on the dummy counter, switching here may be
1213          * worse since this timecounter may not be monotonic.
1214          */
1215         if (tc_chosen)
1216                 return;
1217         if (tc->tc_quality < 0)
1218                 return;
1219         if (tc_from_tunable[0] != '\0' &&
1220             strcmp(tc->tc_name, tc_from_tunable) == 0) {
1221                 tc_chosen = 1;
1222                 tc_from_tunable[0] = '\0';
1223         } else {
1224                 if (tc->tc_quality < timecounter->tc_quality)
1225                         return;
1226                 if (tc->tc_quality == timecounter->tc_quality &&
1227                     tc->tc_frequency < timecounter->tc_frequency)
1228                         return;
1229         }
1230         (void)tc->tc_get_timecount(tc);
1231         timecounter = tc;
1232 }
1233
1234 /* Report the frequency of the current timecounter. */
1235 uint64_t
1236 tc_getfrequency(void)
1237 {
1238
1239         return (timehands->th_counter->tc_frequency);
1240 }
1241
1242 static bool
1243 sleeping_on_old_rtc(struct thread *td)
1244 {
1245
1246         /*
1247          * td_rtcgen is modified by curthread when it is running,
1248          * and by other threads in this function.  By finding the thread
1249          * on a sleepqueue and holding the lock on the sleepqueue
1250          * chain, we guarantee that the thread is not running and that
1251          * modifying td_rtcgen is safe.  Setting td_rtcgen to zero informs
1252          * the thread that it was woken due to a real-time clock adjustment.
1253          * (The declaration of td_rtcgen refers to this comment.)
1254          */
1255         if (td->td_rtcgen != 0 && td->td_rtcgen != rtc_generation) {
1256                 td->td_rtcgen = 0;
1257                 return (true);
1258         }
1259         return (false);
1260 }
1261
1262 static struct mtx tc_setclock_mtx;
1263 MTX_SYSINIT(tc_setclock_init, &tc_setclock_mtx, "tcsetc", MTX_SPIN);
1264
1265 /*
1266  * Step our concept of UTC.  This is done by modifying our estimate of
1267  * when we booted.
1268  */
1269 void
1270 tc_setclock(struct timespec *ts)
1271 {
1272         struct timespec tbef, taft;
1273         struct bintime bt, bt2;
1274
1275         timespec2bintime(ts, &bt);
1276         nanotime(&tbef);
1277         mtx_lock_spin(&tc_setclock_mtx);
1278         cpu_tick_calibrate(1);
1279         binuptime(&bt2);
1280         bintime_sub(&bt, &bt2);
1281
1282         /* XXX fiddle all the little crinkly bits around the fiords... */
1283         tc_windup(&bt);
1284         mtx_unlock_spin(&tc_setclock_mtx);
1285
1286         /* Avoid rtc_generation == 0, since td_rtcgen == 0 is special. */
1287         atomic_add_rel_int(&rtc_generation, 2);
1288         sleepq_chains_remove_matching(sleeping_on_old_rtc);
1289         if (timestepwarnings) {
1290                 nanotime(&taft);
1291                 log(LOG_INFO,
1292                     "Time stepped from %jd.%09ld to %jd.%09ld (%jd.%09ld)\n",
1293                     (intmax_t)tbef.tv_sec, tbef.tv_nsec,
1294                     (intmax_t)taft.tv_sec, taft.tv_nsec,
1295                     (intmax_t)ts->tv_sec, ts->tv_nsec);
1296         }
1297 }
1298
1299 /*
1300  * Initialize the next struct timehands in the ring and make
1301  * it the active timehands.  Along the way we might switch to a different
1302  * timecounter and/or do seconds processing in NTP.  Slightly magic.
1303  */
1304 static void
1305 tc_windup(struct bintime *new_boottimebin)
1306 {
1307         struct bintime bt;
1308         struct timehands *th, *tho;
1309         uint64_t scale;
1310         u_int delta, ncount, ogen;
1311         int i;
1312         time_t t;
1313
1314         /*
1315          * Make the next timehands a copy of the current one, but do
1316          * not overwrite the generation or next pointer.  While we
1317          * update the contents, the generation must be zero.  We need
1318          * to ensure that the zero generation is visible before the
1319          * data updates become visible, which requires release fence.
1320          * For similar reasons, re-reading of the generation after the
1321          * data is read should use acquire fence.
1322          */
1323         tho = timehands;
1324         th = tho->th_next;
1325         ogen = th->th_generation;
1326         th->th_generation = 0;
1327         atomic_thread_fence_rel();
1328         memcpy(th, tho, offsetof(struct timehands, th_generation));
1329         if (new_boottimebin != NULL)
1330                 th->th_boottime = *new_boottimebin;
1331
1332         /*
1333          * Capture a timecounter delta on the current timecounter and if
1334          * changing timecounters, a counter value from the new timecounter.
1335          * Update the offset fields accordingly.
1336          */
1337         delta = tc_delta(th);
1338         if (th->th_counter != timecounter)
1339                 ncount = timecounter->tc_get_timecount(timecounter);
1340         else
1341                 ncount = 0;
1342 #ifdef FFCLOCK
1343         ffclock_windup(delta);
1344 #endif
1345         th->th_offset_count += delta;
1346         th->th_offset_count &= th->th_counter->tc_counter_mask;
1347         while (delta > th->th_counter->tc_frequency) {
1348                 /* Eat complete unadjusted seconds. */
1349                 delta -= th->th_counter->tc_frequency;
1350                 th->th_offset.sec++;
1351         }
1352         if ((delta > th->th_counter->tc_frequency / 2) &&
1353             (th->th_scale * delta < ((uint64_t)1 << 63))) {
1354                 /* The product th_scale * delta just barely overflows. */
1355                 th->th_offset.sec++;
1356         }
1357         bintime_addx(&th->th_offset, th->th_scale * delta);
1358
1359         /*
1360          * Hardware latching timecounters may not generate interrupts on
1361          * PPS events, so instead we poll them.  There is a finite risk that
1362          * the hardware might capture a count which is later than the one we
1363          * got above, and therefore possibly in the next NTP second which might
1364          * have a different rate than the current NTP second.  It doesn't
1365          * matter in practice.
1366          */
1367         if (tho->th_counter->tc_poll_pps)
1368                 tho->th_counter->tc_poll_pps(tho->th_counter);
1369
1370         /*
1371          * Deal with NTP second processing.  The for loop normally
1372          * iterates at most once, but in extreme situations it might
1373          * keep NTP sane if timeouts are not run for several seconds.
1374          * At boot, the time step can be large when the TOD hardware
1375          * has been read, so on really large steps, we call
1376          * ntp_update_second only twice.  We need to call it twice in
1377          * case we missed a leap second.
1378          */
1379         bt = th->th_offset;
1380         bintime_add(&bt, &th->th_boottime);
1381         i = bt.sec - tho->th_microtime.tv_sec;
1382         if (i > LARGE_STEP)
1383                 i = 2;
1384         for (; i > 0; i--) {
1385                 t = bt.sec;
1386                 ntp_update_second(&th->th_adjustment, &bt.sec);
1387                 if (bt.sec != t)
1388                         th->th_boottime.sec += bt.sec - t;
1389         }
1390         /* Update the UTC timestamps used by the get*() functions. */
1391         th->th_bintime = bt;
1392         bintime2timeval(&bt, &th->th_microtime);
1393         bintime2timespec(&bt, &th->th_nanotime);
1394
1395         /* Now is a good time to change timecounters. */
1396         if (th->th_counter != timecounter) {
1397 #ifndef __arm__
1398                 if ((timecounter->tc_flags & TC_FLAGS_C2STOP) != 0)
1399                         cpu_disable_c2_sleep++;
1400                 if ((th->th_counter->tc_flags & TC_FLAGS_C2STOP) != 0)
1401                         cpu_disable_c2_sleep--;
1402 #endif
1403                 th->th_counter = timecounter;
1404                 th->th_offset_count = ncount;
1405                 tc_min_ticktock_freq = max(1, timecounter->tc_frequency /
1406                     (((uint64_t)timecounter->tc_counter_mask + 1) / 3));
1407 #ifdef FFCLOCK
1408                 ffclock_change_tc(th);
1409 #endif
1410         }
1411
1412         /*-
1413          * Recalculate the scaling factor.  We want the number of 1/2^64
1414          * fractions of a second per period of the hardware counter, taking
1415          * into account the th_adjustment factor which the NTP PLL/adjtime(2)
1416          * processing provides us with.
1417          *
1418          * The th_adjustment is nanoseconds per second with 32 bit binary
1419          * fraction and we want 64 bit binary fraction of second:
1420          *
1421          *       x = a * 2^32 / 10^9 = a * 4.294967296
1422          *
1423          * The range of th_adjustment is +/- 5000PPM so inside a 64bit int
1424          * we can only multiply by about 850 without overflowing, that
1425          * leaves no suitably precise fractions for multiply before divide.
1426          *
1427          * Divide before multiply with a fraction of 2199/512 results in a
1428          * systematic undercompensation of 10PPM of th_adjustment.  On a
1429          * 5000PPM adjustment this is a 0.05PPM error.  This is acceptable.
1430          *
1431          * We happily sacrifice the lowest of the 64 bits of our result
1432          * to the goddess of code clarity.
1433          *
1434          */
1435         scale = (uint64_t)1 << 63;
1436         scale += (th->th_adjustment / 1024) * 2199;
1437         scale /= th->th_counter->tc_frequency;
1438         th->th_scale = scale * 2;
1439         th->th_large_delta = MIN(((uint64_t)1 << 63) / scale, UINT_MAX);
1440
1441         /*
1442          * Now that the struct timehands is again consistent, set the new
1443          * generation number, making sure to not make it zero.
1444          */
1445         if (++ogen == 0)
1446                 ogen = 1;
1447         atomic_store_rel_int(&th->th_generation, ogen);
1448
1449         /* Go live with the new struct timehands. */
1450 #ifdef FFCLOCK
1451         switch (sysclock_active) {
1452         case SYSCLOCK_FBCK:
1453 #endif
1454                 time_second = th->th_microtime.tv_sec;
1455                 time_uptime = th->th_offset.sec;
1456 #ifdef FFCLOCK
1457                 break;
1458         case SYSCLOCK_FFWD:
1459                 time_second = fftimehands->tick_time_lerp.sec;
1460                 time_uptime = fftimehands->tick_time_lerp.sec - ffclock_boottime.sec;
1461                 break;
1462         }
1463 #endif
1464
1465         timehands = th;
1466         timekeep_push_vdso();
1467 }
1468
1469 /* Report or change the active timecounter hardware. */
1470 static int
1471 sysctl_kern_timecounter_hardware(SYSCTL_HANDLER_ARGS)
1472 {
1473         char newname[32];
1474         struct timecounter *newtc, *tc;
1475         int error;
1476
1477         tc = timecounter;
1478         strlcpy(newname, tc->tc_name, sizeof(newname));
1479
1480         error = sysctl_handle_string(oidp, &newname[0], sizeof(newname), req);
1481         if (error != 0 || req->newptr == NULL)
1482                 return (error);
1483         /* Record that the tc in use now was specifically chosen. */
1484         tc_chosen = 1;
1485         if (strcmp(newname, tc->tc_name) == 0)
1486                 return (0);
1487         for (newtc = timecounters; newtc != NULL; newtc = newtc->tc_next) {
1488                 if (strcmp(newname, newtc->tc_name) != 0)
1489                         continue;
1490
1491                 /* Warm up new timecounter. */
1492                 (void)newtc->tc_get_timecount(newtc);
1493
1494                 timecounter = newtc;
1495
1496                 /*
1497                  * The vdso timehands update is deferred until the next
1498                  * 'tc_windup()'.
1499                  *
1500                  * This is prudent given that 'timekeep_push_vdso()' does not
1501                  * use any locking and that it can be called in hard interrupt
1502                  * context via 'tc_windup()'.
1503                  */
1504                 return (0);
1505         }
1506         return (EINVAL);
1507 }
1508
1509 SYSCTL_PROC(_kern_timecounter, OID_AUTO, hardware,
1510     CTLTYPE_STRING | CTLFLAG_RWTUN | CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, 0, 0,
1511     sysctl_kern_timecounter_hardware, "A",
1512     "Timecounter hardware selected");
1513
1514 /* Report the available timecounter hardware. */
1515 static int
1516 sysctl_kern_timecounter_choice(SYSCTL_HANDLER_ARGS)
1517 {
1518         struct sbuf sb;
1519         struct timecounter *tc;
1520         int error;
1521
1522         sbuf_new_for_sysctl(&sb, NULL, 0, req);
1523         for (tc = timecounters; tc != NULL; tc = tc->tc_next) {
1524                 if (tc != timecounters)
1525                         sbuf_putc(&sb, ' ');
1526                 sbuf_printf(&sb, "%s(%d)", tc->tc_name, tc->tc_quality);
1527         }
1528         error = sbuf_finish(&sb);
1529         sbuf_delete(&sb);
1530         return (error);
1531 }
1532
1533 SYSCTL_PROC(_kern_timecounter, OID_AUTO, choice,
1534     CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 0,
1535     sysctl_kern_timecounter_choice, "A",
1536     "Timecounter hardware detected");
1537
1538 /*
1539  * RFC 2783 PPS-API implementation.
1540  */
1541
1542 /*
1543  *  Return true if the driver is aware of the abi version extensions in the
1544  *  pps_state structure, and it supports at least the given abi version number.
1545  */
1546 static inline int
1547 abi_aware(struct pps_state *pps, int vers)
1548 {
1549
1550         return ((pps->kcmode & KCMODE_ABIFLAG) && pps->driver_abi >= vers);
1551 }
1552
1553 static int
1554 pps_fetch(struct pps_fetch_args *fapi, struct pps_state *pps)
1555 {
1556         int err, timo;
1557         pps_seq_t aseq, cseq;
1558         struct timeval tv;
1559
1560         if (fapi->tsformat && fapi->tsformat != PPS_TSFMT_TSPEC)
1561                 return (EINVAL);
1562
1563         /*
1564          * If no timeout is requested, immediately return whatever values were
1565          * most recently captured.  If timeout seconds is -1, that's a request
1566          * to block without a timeout.  WITNESS won't let us sleep forever
1567          * without a lock (we really don't need a lock), so just repeatedly
1568          * sleep a long time.
1569          */
1570         if (fapi->timeout.tv_sec || fapi->timeout.tv_nsec) {
1571                 if (fapi->timeout.tv_sec == -1)
1572                         timo = 0x7fffffff;
1573                 else {
1574                         tv.tv_sec = fapi->timeout.tv_sec;
1575                         tv.tv_usec = fapi->timeout.tv_nsec / 1000;
1576                         timo = tvtohz(&tv);
1577                 }
1578                 aseq = atomic_load_int(&pps->ppsinfo.assert_sequence);
1579                 cseq = atomic_load_int(&pps->ppsinfo.clear_sequence);
1580                 while (aseq == atomic_load_int(&pps->ppsinfo.assert_sequence) &&
1581                     cseq == atomic_load_int(&pps->ppsinfo.clear_sequence)) {
1582                         if (abi_aware(pps, 1) && pps->driver_mtx != NULL) {
1583                                 if (pps->flags & PPSFLAG_MTX_SPIN) {
1584                                         err = msleep_spin(pps, pps->driver_mtx,
1585                                             "ppsfch", timo);
1586                                 } else {
1587                                         err = msleep(pps, pps->driver_mtx, PCATCH,
1588                                             "ppsfch", timo);
1589                                 }
1590                         } else {
1591                                 err = tsleep(pps, PCATCH, "ppsfch", timo);
1592                         }
1593                         if (err == EWOULDBLOCK) {
1594                                 if (fapi->timeout.tv_sec == -1) {
1595                                         continue;
1596                                 } else {
1597                                         return (ETIMEDOUT);
1598                                 }
1599                         } else if (err != 0) {
1600                                 return (err);
1601                         }
1602                 }
1603         }
1604
1605         pps->ppsinfo.current_mode = pps->ppsparam.mode;
1606         fapi->pps_info_buf = pps->ppsinfo;
1607
1608         return (0);
1609 }
1610
1611 int
1612 pps_ioctl(u_long cmd, caddr_t data, struct pps_state *pps)
1613 {
1614         pps_params_t *app;
1615         struct pps_fetch_args *fapi;
1616 #ifdef FFCLOCK
1617         struct pps_fetch_ffc_args *fapi_ffc;
1618 #endif
1619 #ifdef PPS_SYNC
1620         struct pps_kcbind_args *kapi;
1621 #endif
1622
1623         KASSERT(pps != NULL, ("NULL pps pointer in pps_ioctl"));
1624         switch (cmd) {
1625         case PPS_IOC_CREATE:
1626                 return (0);
1627         case PPS_IOC_DESTROY:
1628                 return (0);
1629         case PPS_IOC_SETPARAMS:
1630                 app = (pps_params_t *)data;
1631                 if (app->mode & ~pps->ppscap)
1632                         return (EINVAL);
1633 #ifdef FFCLOCK
1634                 /* Ensure only a single clock is selected for ffc timestamp. */
1635                 if ((app->mode & PPS_TSCLK_MASK) == PPS_TSCLK_MASK)
1636                         return (EINVAL);
1637 #endif
1638                 pps->ppsparam = *app;
1639                 return (0);
1640         case PPS_IOC_GETPARAMS:
1641                 app = (pps_params_t *)data;
1642                 *app = pps->ppsparam;
1643                 app->api_version = PPS_API_VERS_1;
1644                 return (0);
1645         case PPS_IOC_GETCAP:
1646                 *(int*)data = pps->ppscap;
1647                 return (0);
1648         case PPS_IOC_FETCH:
1649                 fapi = (struct pps_fetch_args *)data;
1650                 return (pps_fetch(fapi, pps));
1651 #ifdef FFCLOCK
1652         case PPS_IOC_FETCH_FFCOUNTER:
1653                 fapi_ffc = (struct pps_fetch_ffc_args *)data;
1654                 if (fapi_ffc->tsformat && fapi_ffc->tsformat !=
1655                     PPS_TSFMT_TSPEC)
1656                         return (EINVAL);
1657                 if (fapi_ffc->timeout.tv_sec || fapi_ffc->timeout.tv_nsec)
1658                         return (EOPNOTSUPP);
1659                 pps->ppsinfo_ffc.current_mode = pps->ppsparam.mode;
1660                 fapi_ffc->pps_info_buf_ffc = pps->ppsinfo_ffc;
1661                 /* Overwrite timestamps if feedback clock selected. */
1662                 switch (pps->ppsparam.mode & PPS_TSCLK_MASK) {
1663                 case PPS_TSCLK_FBCK:
1664                         fapi_ffc->pps_info_buf_ffc.assert_timestamp =
1665                             pps->ppsinfo.assert_timestamp;
1666                         fapi_ffc->pps_info_buf_ffc.clear_timestamp =
1667                             pps->ppsinfo.clear_timestamp;
1668                         break;
1669                 case PPS_TSCLK_FFWD:
1670                         break;
1671                 default:
1672                         break;
1673                 }
1674                 return (0);
1675 #endif /* FFCLOCK */
1676         case PPS_IOC_KCBIND:
1677 #ifdef PPS_SYNC
1678                 kapi = (struct pps_kcbind_args *)data;
1679                 /* XXX Only root should be able to do this */
1680                 if (kapi->tsformat && kapi->tsformat != PPS_TSFMT_TSPEC)
1681                         return (EINVAL);
1682                 if (kapi->kernel_consumer != PPS_KC_HARDPPS)
1683                         return (EINVAL);
1684                 if (kapi->edge & ~pps->ppscap)
1685                         return (EINVAL);
1686                 pps->kcmode = (kapi->edge & KCMODE_EDGEMASK) |
1687                     (pps->kcmode & KCMODE_ABIFLAG);
1688                 return (0);
1689 #else
1690                 return (EOPNOTSUPP);
1691 #endif
1692         default:
1693                 return (ENOIOCTL);
1694         }
1695 }
1696
1697 void
1698 pps_init(struct pps_state *pps)
1699 {
1700         pps->ppscap |= PPS_TSFMT_TSPEC | PPS_CANWAIT;
1701         if (pps->ppscap & PPS_CAPTUREASSERT)
1702                 pps->ppscap |= PPS_OFFSETASSERT;
1703         if (pps->ppscap & PPS_CAPTURECLEAR)
1704                 pps->ppscap |= PPS_OFFSETCLEAR;
1705 #ifdef FFCLOCK
1706         pps->ppscap |= PPS_TSCLK_MASK;
1707 #endif
1708         pps->kcmode &= ~KCMODE_ABIFLAG;
1709 }
1710
1711 void
1712 pps_init_abi(struct pps_state *pps)
1713 {
1714
1715         pps_init(pps);
1716         if (pps->driver_abi > 0) {
1717                 pps->kcmode |= KCMODE_ABIFLAG;
1718                 pps->kernel_abi = PPS_ABI_VERSION;
1719         }
1720 }
1721
1722 void
1723 pps_capture(struct pps_state *pps)
1724 {
1725         struct timehands *th;
1726
1727         KASSERT(pps != NULL, ("NULL pps pointer in pps_capture"));
1728         th = timehands;
1729         pps->capgen = atomic_load_acq_int(&th->th_generation);
1730         pps->capth = th;
1731 #ifdef FFCLOCK
1732         pps->capffth = fftimehands;
1733 #endif
1734         pps->capcount = th->th_counter->tc_get_timecount(th->th_counter);
1735         atomic_thread_fence_acq();
1736         if (pps->capgen != th->th_generation)
1737                 pps->capgen = 0;
1738 }
1739
1740 void
1741 pps_event(struct pps_state *pps, int event)
1742 {
1743         struct bintime bt;
1744         struct timespec ts, *tsp, *osp;
1745         u_int tcount, *pcount;
1746         int foff;
1747         pps_seq_t *pseq;
1748 #ifdef FFCLOCK
1749         struct timespec *tsp_ffc;
1750         pps_seq_t *pseq_ffc;
1751         ffcounter *ffcount;
1752 #endif
1753 #ifdef PPS_SYNC
1754         int fhard;
1755 #endif
1756
1757         KASSERT(pps != NULL, ("NULL pps pointer in pps_event"));
1758         /* Nothing to do if not currently set to capture this event type. */
1759         if ((event & pps->ppsparam.mode) == 0)
1760                 return;
1761         /* If the timecounter was wound up underneath us, bail out. */
1762         if (pps->capgen == 0 || pps->capgen !=
1763             atomic_load_acq_int(&pps->capth->th_generation))
1764                 return;
1765
1766         /* Things would be easier with arrays. */
1767         if (event == PPS_CAPTUREASSERT) {
1768                 tsp = &pps->ppsinfo.assert_timestamp;
1769                 osp = &pps->ppsparam.assert_offset;
1770                 foff = pps->ppsparam.mode & PPS_OFFSETASSERT;
1771 #ifdef PPS_SYNC
1772                 fhard = pps->kcmode & PPS_CAPTUREASSERT;
1773 #endif
1774                 pcount = &pps->ppscount[0];
1775                 pseq = &pps->ppsinfo.assert_sequence;
1776 #ifdef FFCLOCK
1777                 ffcount = &pps->ppsinfo_ffc.assert_ffcount;
1778                 tsp_ffc = &pps->ppsinfo_ffc.assert_timestamp;
1779                 pseq_ffc = &pps->ppsinfo_ffc.assert_sequence;
1780 #endif
1781         } else {
1782                 tsp = &pps->ppsinfo.clear_timestamp;
1783                 osp = &pps->ppsparam.clear_offset;
1784                 foff = pps->ppsparam.mode & PPS_OFFSETCLEAR;
1785 #ifdef PPS_SYNC
1786                 fhard = pps->kcmode & PPS_CAPTURECLEAR;
1787 #endif
1788                 pcount = &pps->ppscount[1];
1789                 pseq = &pps->ppsinfo.clear_sequence;
1790 #ifdef FFCLOCK
1791                 ffcount = &pps->ppsinfo_ffc.clear_ffcount;
1792                 tsp_ffc = &pps->ppsinfo_ffc.clear_timestamp;
1793                 pseq_ffc = &pps->ppsinfo_ffc.clear_sequence;
1794 #endif
1795         }
1796
1797         /*
1798          * If the timecounter changed, we cannot compare the count values, so
1799          * we have to drop the rest of the PPS-stuff until the next event.
1800          */
1801         if (pps->ppstc != pps->capth->th_counter) {
1802                 pps->ppstc = pps->capth->th_counter;
1803                 *pcount = pps->capcount;
1804                 pps->ppscount[2] = pps->capcount;
1805                 return;
1806         }
1807
1808         /* Convert the count to a timespec. */
1809         tcount = pps->capcount - pps->capth->th_offset_count;
1810         tcount &= pps->capth->th_counter->tc_counter_mask;
1811         bt = pps->capth->th_bintime;
1812         bintime_addx(&bt, pps->capth->th_scale * tcount);
1813         bintime2timespec(&bt, &ts);
1814
1815         /* If the timecounter was wound up underneath us, bail out. */
1816         atomic_thread_fence_acq();
1817         if (pps->capgen != pps->capth->th_generation)
1818                 return;
1819
1820         *pcount = pps->capcount;
1821         (*pseq)++;
1822         *tsp = ts;
1823
1824         if (foff) {
1825                 timespecadd(tsp, osp, tsp);
1826                 if (tsp->tv_nsec < 0) {
1827                         tsp->tv_nsec += 1000000000;
1828                         tsp->tv_sec -= 1;
1829                 }
1830         }
1831
1832 #ifdef FFCLOCK
1833         *ffcount = pps->capffth->tick_ffcount + tcount;
1834         bt = pps->capffth->tick_time;
1835         ffclock_convert_delta(tcount, pps->capffth->cest.period, &bt);
1836         bintime_add(&bt, &pps->capffth->tick_time);
1837         bintime2timespec(&bt, &ts);
1838         (*pseq_ffc)++;
1839         *tsp_ffc = ts;
1840 #endif
1841
1842 #ifdef PPS_SYNC
1843         if (fhard) {
1844                 uint64_t scale;
1845
1846                 /*
1847                  * Feed the NTP PLL/FLL.
1848                  * The FLL wants to know how many (hardware) nanoseconds
1849                  * elapsed since the previous event.
1850                  */
1851                 tcount = pps->capcount - pps->ppscount[2];
1852                 pps->ppscount[2] = pps->capcount;
1853                 tcount &= pps->capth->th_counter->tc_counter_mask;
1854                 scale = (uint64_t)1 << 63;
1855                 scale /= pps->capth->th_counter->tc_frequency;
1856                 scale *= 2;
1857                 bt.sec = 0;
1858                 bt.frac = 0;
1859                 bintime_addx(&bt, scale * tcount);
1860                 bintime2timespec(&bt, &ts);
1861                 hardpps(tsp, ts.tv_nsec + 1000000000 * ts.tv_sec);
1862         }
1863 #endif
1864
1865         /* Wakeup anyone sleeping in pps_fetch().  */
1866         wakeup(pps);
1867 }
1868
1869 /*
1870  * Timecounters need to be updated every so often to prevent the hardware
1871  * counter from overflowing.  Updating also recalculates the cached values
1872  * used by the get*() family of functions, so their precision depends on
1873  * the update frequency.
1874  */
1875
1876 static int tc_tick;
1877 SYSCTL_INT(_kern_timecounter, OID_AUTO, tick, CTLFLAG_RD, &tc_tick, 0,
1878     "Approximate number of hardclock ticks in a millisecond");
1879
1880 void
1881 tc_ticktock(int cnt)
1882 {
1883         static int count;
1884
1885         if (mtx_trylock_spin(&tc_setclock_mtx)) {
1886                 count += cnt;
1887                 if (count >= tc_tick) {
1888                         count = 0;
1889                         tc_windup(NULL);
1890                 }
1891                 mtx_unlock_spin(&tc_setclock_mtx);
1892         }
1893 }
1894
1895 static void __inline
1896 tc_adjprecision(void)
1897 {
1898         int t;
1899
1900         if (tc_timepercentage > 0) {
1901                 t = (99 + tc_timepercentage) / tc_timepercentage;
1902                 tc_precexp = fls(t + (t >> 1)) - 1;
1903                 FREQ2BT(hz / tc_tick, &bt_timethreshold);
1904                 FREQ2BT(hz, &bt_tickthreshold);
1905                 bintime_shift(&bt_timethreshold, tc_precexp);
1906                 bintime_shift(&bt_tickthreshold, tc_precexp);
1907         } else {
1908                 tc_precexp = 31;
1909                 bt_timethreshold.sec = INT_MAX;
1910                 bt_timethreshold.frac = ~(uint64_t)0;
1911                 bt_tickthreshold = bt_timethreshold;
1912         }
1913         sbt_timethreshold = bttosbt(bt_timethreshold);
1914         sbt_tickthreshold = bttosbt(bt_tickthreshold);
1915 }
1916
1917 static int
1918 sysctl_kern_timecounter_adjprecision(SYSCTL_HANDLER_ARGS)
1919 {
1920         int error, val;
1921
1922         val = tc_timepercentage;
1923         error = sysctl_handle_int(oidp, &val, 0, req);
1924         if (error != 0 || req->newptr == NULL)
1925                 return (error);
1926         tc_timepercentage = val;
1927         if (cold)
1928                 goto done;
1929         tc_adjprecision();
1930 done:
1931         return (0);
1932 }
1933
1934 /* Set up the requested number of timehands. */
1935 static void
1936 inittimehands(void *dummy)
1937 {
1938         struct timehands *thp;
1939         int i;
1940
1941         TUNABLE_INT_FETCH("kern.timecounter.timehands_count",
1942             &timehands_count);
1943         if (timehands_count < 1)
1944                 timehands_count = 1;
1945         if (timehands_count > nitems(ths))
1946                 timehands_count = nitems(ths);
1947         for (i = 1, thp = &ths[0]; i < timehands_count;  thp = &ths[i++])
1948                 thp->th_next = &ths[i];
1949         thp->th_next = &ths[0];
1950
1951         TUNABLE_STR_FETCH("kern.timecounter.hardware", tc_from_tunable,
1952             sizeof(tc_from_tunable));
1953 }
1954 SYSINIT(timehands, SI_SUB_TUNABLES, SI_ORDER_ANY, inittimehands, NULL);
1955
1956 static void
1957 inittimecounter(void *dummy)
1958 {
1959         u_int p;
1960         int tick_rate;
1961
1962         /*
1963          * Set the initial timeout to
1964          * max(1, <approx. number of hardclock ticks in a millisecond>).
1965          * People should probably not use the sysctl to set the timeout
1966          * to smaller than its initial value, since that value is the
1967          * smallest reasonable one.  If they want better timestamps they
1968          * should use the non-"get"* functions.
1969          */
1970         if (hz > 1000)
1971                 tc_tick = (hz + 500) / 1000;
1972         else
1973                 tc_tick = 1;
1974         tc_adjprecision();
1975         FREQ2BT(hz, &tick_bt);
1976         tick_sbt = bttosbt(tick_bt);
1977         tick_rate = hz / tc_tick;
1978         FREQ2BT(tick_rate, &tc_tick_bt);
1979         tc_tick_sbt = bttosbt(tc_tick_bt);
1980         p = (tc_tick * 1000000) / hz;
1981         printf("Timecounters tick every %d.%03u msec\n", p / 1000, p % 1000);
1982
1983 #ifdef FFCLOCK
1984         ffclock_init();
1985 #endif
1986
1987         /* warm up new timecounter (again) and get rolling. */
1988         (void)timecounter->tc_get_timecount(timecounter);
1989         mtx_lock_spin(&tc_setclock_mtx);
1990         tc_windup(NULL);
1991         mtx_unlock_spin(&tc_setclock_mtx);
1992 }
1993
1994 SYSINIT(timecounter, SI_SUB_CLOCKS, SI_ORDER_SECOND, inittimecounter, NULL);
1995
1996 /* Cpu tick handling -------------------------------------------------*/
1997
1998 static int cpu_tick_variable;
1999 static uint64_t cpu_tick_frequency;
2000
2001 DPCPU_DEFINE_STATIC(uint64_t, tc_cpu_ticks_base);
2002 DPCPU_DEFINE_STATIC(unsigned, tc_cpu_ticks_last);
2003
2004 static uint64_t
2005 tc_cpu_ticks(void)
2006 {
2007         struct timecounter *tc;
2008         uint64_t res, *base;
2009         unsigned u, *last;
2010
2011         critical_enter();
2012         base = DPCPU_PTR(tc_cpu_ticks_base);
2013         last = DPCPU_PTR(tc_cpu_ticks_last);
2014         tc = timehands->th_counter;
2015         u = tc->tc_get_timecount(tc) & tc->tc_counter_mask;
2016         if (u < *last)
2017                 *base += (uint64_t)tc->tc_counter_mask + 1;
2018         *last = u;
2019         res = u + *base;
2020         critical_exit();
2021         return (res);
2022 }
2023
2024 void
2025 cpu_tick_calibration(void)
2026 {
2027         static time_t last_calib;
2028
2029         if (time_uptime != last_calib && !(time_uptime & 0xf)) {
2030                 cpu_tick_calibrate(0);
2031                 last_calib = time_uptime;
2032         }
2033 }
2034
2035 /*
2036  * This function gets called every 16 seconds on only one designated
2037  * CPU in the system from hardclock() via cpu_tick_calibration()().
2038  *
2039  * Whenever the real time clock is stepped we get called with reset=1
2040  * to make sure we handle suspend/resume and similar events correctly.
2041  */
2042
2043 static void
2044 cpu_tick_calibrate(int reset)
2045 {
2046         static uint64_t c_last;
2047         uint64_t c_this, c_delta;
2048         static struct bintime  t_last;
2049         struct bintime t_this, t_delta;
2050         uint32_t divi;
2051
2052         if (reset) {
2053                 /* The clock was stepped, abort & reset */
2054                 t_last.sec = 0;
2055                 return;
2056         }
2057
2058         /* we don't calibrate fixed rate cputicks */
2059         if (!cpu_tick_variable)
2060                 return;
2061
2062         getbinuptime(&t_this);
2063         c_this = cpu_ticks();
2064         if (t_last.sec != 0) {
2065                 c_delta = c_this - c_last;
2066                 t_delta = t_this;
2067                 bintime_sub(&t_delta, &t_last);
2068                 /*
2069                  * Headroom:
2070                  *      2^(64-20) / 16[s] =
2071                  *      2^(44) / 16[s] =
2072                  *      17.592.186.044.416 / 16 =
2073                  *      1.099.511.627.776 [Hz]
2074                  */
2075                 divi = t_delta.sec << 20;
2076                 divi |= t_delta.frac >> (64 - 20);
2077                 c_delta <<= 20;
2078                 c_delta /= divi;
2079                 if (c_delta > cpu_tick_frequency) {
2080                         if (0 && bootverbose)
2081                                 printf("cpu_tick increased to %ju Hz\n",
2082                                     c_delta);
2083                         cpu_tick_frequency = c_delta;
2084                 }
2085         }
2086         c_last = c_this;
2087         t_last = t_this;
2088 }
2089
2090 void
2091 set_cputicker(cpu_tick_f *func, uint64_t freq, unsigned var)
2092 {
2093
2094         if (func == NULL) {
2095                 cpu_ticks = tc_cpu_ticks;
2096         } else {
2097                 cpu_tick_frequency = freq;
2098                 cpu_tick_variable = var;
2099                 cpu_ticks = func;
2100         }
2101 }
2102
2103 uint64_t
2104 cpu_tickrate(void)
2105 {
2106
2107         if (cpu_ticks == tc_cpu_ticks)
2108                 return (tc_getfrequency());
2109         return (cpu_tick_frequency);
2110 }
2111
2112 /*
2113  * We need to be slightly careful converting cputicks to microseconds.
2114  * There is plenty of margin in 64 bits of microseconds (half a million
2115  * years) and in 64 bits at 4 GHz (146 years), but if we do a multiply
2116  * before divide conversion (to retain precision) we find that the
2117  * margin shrinks to 1.5 hours (one millionth of 146y).
2118  * With a three prong approach we never lose significant bits, no
2119  * matter what the cputick rate and length of timeinterval is.
2120  */
2121
2122 uint64_t
2123 cputick2usec(uint64_t tick)
2124 {
2125
2126         if (tick > 18446744073709551LL)         /* floor(2^64 / 1000) */
2127                 return (tick / (cpu_tickrate() / 1000000LL));
2128         else if (tick > 18446744073709LL)       /* floor(2^64 / 1000000) */
2129                 return ((tick * 1000LL) / (cpu_tickrate() / 1000LL));
2130         else
2131                 return ((tick * 1000000LL) / cpu_tickrate());
2132 }
2133
2134 cpu_tick_f      *cpu_ticks = tc_cpu_ticks;
2135
2136 static int vdso_th_enable = 1;
2137 static int
2138 sysctl_fast_gettime(SYSCTL_HANDLER_ARGS)
2139 {
2140         int old_vdso_th_enable, error;
2141
2142         old_vdso_th_enable = vdso_th_enable;
2143         error = sysctl_handle_int(oidp, &old_vdso_th_enable, 0, req);
2144         if (error != 0)
2145                 return (error);
2146         vdso_th_enable = old_vdso_th_enable;
2147         return (0);
2148 }
2149 SYSCTL_PROC(_kern_timecounter, OID_AUTO, fast_gettime,
2150     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
2151     NULL, 0, sysctl_fast_gettime, "I", "Enable fast time of day");
2152
2153 uint32_t
2154 tc_fill_vdso_timehands(struct vdso_timehands *vdso_th)
2155 {
2156         struct timehands *th;
2157         uint32_t enabled;
2158
2159         th = timehands;
2160         vdso_th->th_scale = th->th_scale;
2161         vdso_th->th_offset_count = th->th_offset_count;
2162         vdso_th->th_counter_mask = th->th_counter->tc_counter_mask;
2163         vdso_th->th_offset = th->th_offset;
2164         vdso_th->th_boottime = th->th_boottime;
2165         if (th->th_counter->tc_fill_vdso_timehands != NULL) {
2166                 enabled = th->th_counter->tc_fill_vdso_timehands(vdso_th,
2167                     th->th_counter);
2168         } else
2169                 enabled = 0;
2170         if (!vdso_th_enable)
2171                 enabled = 0;
2172         return (enabled);
2173 }
2174
2175 #ifdef COMPAT_FREEBSD32
2176 uint32_t
2177 tc_fill_vdso_timehands32(struct vdso_timehands32 *vdso_th32)
2178 {
2179         struct timehands *th;
2180         uint32_t enabled;
2181
2182         th = timehands;
2183         *(uint64_t *)&vdso_th32->th_scale[0] = th->th_scale;
2184         vdso_th32->th_offset_count = th->th_offset_count;
2185         vdso_th32->th_counter_mask = th->th_counter->tc_counter_mask;
2186         vdso_th32->th_offset.sec = th->th_offset.sec;
2187         *(uint64_t *)&vdso_th32->th_offset.frac[0] = th->th_offset.frac;
2188         vdso_th32->th_boottime.sec = th->th_boottime.sec;
2189         *(uint64_t *)&vdso_th32->th_boottime.frac[0] = th->th_boottime.frac;
2190         if (th->th_counter->tc_fill_vdso_timehands32 != NULL) {
2191                 enabled = th->th_counter->tc_fill_vdso_timehands32(vdso_th32,
2192                     th->th_counter);
2193         } else
2194                 enabled = 0;
2195         if (!vdso_th_enable)
2196                 enabled = 0;
2197         return (enabled);
2198 }
2199 #endif
2200
2201 #include "opt_ddb.h"
2202 #ifdef DDB
2203 #include <ddb/ddb.h>
2204
2205 DB_SHOW_COMMAND(timecounter, db_show_timecounter)
2206 {
2207         struct timehands *th;
2208         struct timecounter *tc;
2209         u_int val1, val2;
2210
2211         th = timehands;
2212         tc = th->th_counter;
2213         val1 = tc->tc_get_timecount(tc);
2214         __compiler_membar();
2215         val2 = tc->tc_get_timecount(tc);
2216
2217         db_printf("timecounter %p %s\n", tc, tc->tc_name);
2218         db_printf("  mask %#x freq %ju qual %d flags %#x priv %p\n",
2219             tc->tc_counter_mask, (uintmax_t)tc->tc_frequency, tc->tc_quality,
2220             tc->tc_flags, tc->tc_priv);
2221         db_printf("  val %#x %#x\n", val1, val2);
2222         db_printf("timehands adj %#jx scale %#jx ldelta %d off_cnt %d gen %d\n",
2223             (uintmax_t)th->th_adjustment, (uintmax_t)th->th_scale,
2224             th->th_large_delta, th->th_offset_count, th->th_generation);
2225         db_printf("  offset %jd %jd boottime %jd %jd\n",
2226             (intmax_t)th->th_offset.sec, (uintmax_t)th->th_offset.frac,
2227             (intmax_t)th->th_boottime.sec, (uintmax_t)th->th_boottime.frac);
2228 }
2229 #endif