bsd/kern/kern_ntptime.c

   1 /*-
   2  ***********************************************************************
   3  *                                                                     *
   4  * Copyright (c) David L. Mills 1993-2001                              *
   5  *                                                                     *
   6  * Permission to use, copy, modify, and distribute this software and   *
   7  * its documentation for any purpose and without fee is hereby         *
   8  * granted, provided that the above copyright notice appears in all    *
   9  * copies and that both the copyright notice and this permission       *
  10  * notice appear in supporting documentation, and that the name        *
  11  * University of Delaware not be used in advertising or publicity      *
  12  * pertaining to distribution of the software without specific,        *
  13  * written prior permission. The University of Delaware makes no       *
  14  * representations about the suitability this software for any         *
  15  * purpose. It is provided "as is" without express or implied          *
  16  * warranty.                                                           *
  17  *                                                                     *
  18  **********************************************************************/
  19
  20
  21 /*
  22  * Adapted from the original sources for FreeBSD and timecounters by:
  23  * Poul-Henning Kamp <phk@FreeBSD.org>.
  24  *
  25  * The 32bit version of the "LP" macros seems a bit past its "sell by"
  26  * date so I have retained only the 64bit version and included it directly
  27  * in this file.
  28  *
  29  * Only minor changes done to interface with the timecounters over in
  30  * sys/kern/kern_clock.c.   Some of the comments below may be (even more)
  31  * confusing and/or plain wrong in that context.
  32  */
  33
  34 /*
  35  * Copyright (c) 2017 Apple Computer, Inc. All rights reserved.
  36  *
  37  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  38  *
  39  * This file contains Original Code and/or Modifications of Original Code
  40  * as defined in and that are subject to the Apple Public Source License
  41  * Version 2.0 (the 'License'). You may not use this file except in
  42  * compliance with the License. The rights granted to you under the License
  43  * may not be used to create, or enable the creation or redistribution of,
  44  * unlawful or unlicensed copies of an Apple operating system, or to
  45  * circumvent, violate, or enable the circumvention or violation of, any
  46  * terms of an Apple operating system software license agreement.
  47  *
  48  * Please obtain a copy of the License at
  49  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  50  *
  51  * The Original Code and all software distributed under the License are
  52  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  53  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  54  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  55  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  56  * Please see the License for the specific language governing rights and
  57  * limitations under the License.
  58  *
  59  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  60  */
  61
  62 #include <sys/cdefs.h>
  63 #include <sys/param.h>
  64 #include <sys/systm.h>
  65 #include <sys/eventhandler.h>
  66 #include <sys/kernel.h>
  67 #include <sys/priv.h>
  68 #include <sys/proc.h>
  69 #include <sys/lock.h>
  70 #include <sys/time.h>
  71 #include <sys/timex.h>
  72 #include <kern/clock.h>
  73 #include <sys/sysctl.h>
  74 #include <sys/sysproto.h>
  75 #include <sys/kauth.h>
  76 #include <kern/thread_call.h>
  77 #include <kern/timer_call.h>
  78 #include <machine/machine_routines.h>
  79 #if CONFIG_MACF
  80 #include <security/mac_framework.h>
  81 #endif
  82 #include <IOKit/IOBSD.h>
  83 #include <os/log.h>
  84
  85 typedef int64_t l_fp;
  86 #define L_ADD(v, u)     ((v) += (u))
  87 #define L_SUB(v, u)     ((v) -= (u))
  88 #define L_ADDHI(v, a)   ((v) += (int64_t)(a) << 32)
  89 #define L_NEG(v)        ((v) = -(v))
  90 #define L_RSHIFT(v, n) \
  91         do { \
  92                 if ((v) < 0) \
  93                         (v) = -(-(v) >> (n)); \
  94                 else \
  95                         (v) = (v) >> (n); \
  96         } while (0)
  97 #define L_MPY(v, a)     ((v) *= (a))
  98 #define L_CLR(v)        ((v) = 0)
  99 #define L_ISNEG(v)      ((v) < 0)
 100 #define L_LINT(v, a) \
 101         do { \
 102                 if ((a) > 0) \
 103                         ((v) = (int64_t)(a) << 32); \
 104                 else \
 105                         ((v) = -((int64_t)(-(a)) << 32)); \
 106         } while (0)
 107 #define L_GINT(v)       ((v) < 0 ? -(-(v) >> 32) : (v) >> 32)
 108
 109 /*
 110  * Generic NTP kernel interface
 111  *
 112  * These routines constitute the Network Time Protocol (NTP) interfaces
 113  * for user and daemon application programs. The ntp_gettime() routine
 114  * provides the time, maximum error (synch distance) and estimated error
 115  * (dispersion) to client user application programs. The ntp_adjtime()
 116  * routine is used by the NTP daemon to adjust the calendar clock to an
 117  * externally derived time. The time offset and related variables set by
 118  * this routine are used by other routines in this module to adjust the
 119  * phase and frequency of the clock discipline loop which controls the
 120  * system clock.
 121  *
 122  * When the kernel time is reckoned directly in nanoseconds (NTP_NANO
 123  * defined), the time at each tick interrupt is derived directly from
 124  * the kernel time variable. When the kernel time is reckoned in
 125  * microseconds, (NTP_NANO undefined), the time is derived from the
 126  * kernel time variable together with a variable representing the
 127  * leftover nanoseconds at the last tick interrupt. In either case, the
 128  * current nanosecond time is reckoned from these values plus an
 129  * interpolated value derived by the clock routines in another
 130  * architecture-specific module. The interpolation can use either a
 131  * dedicated counter or a processor cycle counter (PCC) implemented in
 132  * some architectures.
 133  *
 134  */
 135 /*
 136  * Phase/frequency-lock loop (PLL/FLL) definitions
 137  *
 138  * The nanosecond clock discipline uses two variable types, time
 139  * variables and frequency variables. Both types are represented as 64-
 140  * bit fixed-point quantities with the decimal point between two 32-bit
 141  * halves. On a 32-bit machine, each half is represented as a single
 142  * word and mathematical operations are done using multiple-precision
 143  * arithmetic. On a 64-bit machine, ordinary computer arithmetic is
 144  * used.
 145  *
 146  * A time variable is a signed 64-bit fixed-point number in ns and
 147  * fraction. It represents the remaining time offset to be amortized
 148  * over succeeding tick interrupts. The maximum time offset is about
 149  * 0.5 s and the resolution is about 2.3e-10 ns.
 150  *
 151  *                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 152  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 153  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 154  * |s s s|                       ns                                |
 155  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 156  * |                        fraction                               |
 157  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 158  *
 159  * A frequency variable is a signed 64-bit fixed-point number in ns/s
 160  * and fraction. It represents the ns and fraction to be added to the
 161  * kernel time variable at each second. The maximum frequency offset is
 162  * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s.
 163  *
 164  *                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 165  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 166  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 167  * |s s s s s s s s s s s s s|            ns/s                     |
 168  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 169  * |                        fraction                               |
 170  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 171  */
 172
 173 #define SHIFT_PLL       4
 174 #define SHIFT_FLL       2
 175
 176 static int time_state = TIME_OK;
 177 int time_status = STA_UNSYNC;
 178 static long time_tai;
 179 static long time_constant;
 180 static long time_precision = 1;
 181 static long time_maxerror = MAXPHASE / 1000;
 182 static unsigned long last_time_maxerror_update;
 183 long time_esterror = MAXPHASE / 1000;
 184 static long time_reftime;
 185 static l_fp time_offset;
 186 static l_fp time_freq;
 187 static int64_t time_adjtime;
 188 static int updated;
 189
 190 static LCK_GRP_DECLARE(ntp_lock_grp, "ntp_lock");
 191 static LCK_SPIN_DECLARE(ntp_lock, &ntp_lock_grp);
 192
 193 #define NTP_LOCK(enable) \
 194                 enable =  ml_set_interrupts_enabled(FALSE); \
 195                 lck_spin_lock(&ntp_lock);
 196
 197 #define NTP_UNLOCK(enable) \
 198                 lck_spin_unlock(&ntp_lock);\
 199                 ml_set_interrupts_enabled(enable);
 200
 201 #define NTP_ASSERT_LOCKED()     LCK_SPIN_ASSERT(&ntp_lock, LCK_ASSERT_OWNED)
 202
 203 static timer_call_data_t ntp_loop_update;
 204 static uint64_t ntp_loop_deadline;
 205 static uint32_t ntp_loop_active;
 206 static uint32_t ntp_loop_period;
 207 #define NTP_LOOP_PERIOD_INTERVAL (NSEC_PER_SEC) /*1 second interval*/
 208
 209 void ntp_init(void);
 210 static void hardupdate(long offset);
 211 static void ntp_gettime1(struct ntptimeval *ntvp);
 212 static bool ntp_is_time_error(int tsl);
 213
 214 static void ntp_loop_update_call(void);
 215 static void refresh_ntp_loop(void);
 216 static void start_ntp_loop(void);
 217
 218 #if DEVELOPMENT || DEBUG
 219 uint32_t g_should_log_clock_adjustments = 0;
 220 SYSCTL_INT(_kern, OID_AUTO, log_clock_adjustments, CTLFLAG_RW | CTLFLAG_LOCKED, &g_should_log_clock_adjustments, 0, "enable kernel clock adjustment logging");
 221 #endif
 222
 223 static bool
 224 ntp_is_time_error(int tsl)
 225 {
 226         if (tsl & (STA_UNSYNC | STA_CLOCKERR)) {
 227                 return true;
 228         }
 229
 230         return false;
 231 }
 232
 233 static void
 234 ntp_gettime1(struct ntptimeval *ntvp)
 235 {
 236         struct timespec atv;
 237
 238         NTP_ASSERT_LOCKED();
 239
 240         nanotime(&atv);
 241         ntvp->time.tv_sec = atv.tv_sec;
 242         ntvp->time.tv_nsec = atv.tv_nsec;
 243         if ((unsigned long)atv.tv_sec > last_time_maxerror_update) {
 244                 time_maxerror += (MAXFREQ / 1000) * (atv.tv_sec - last_time_maxerror_update);
 245                 last_time_maxerror_update = atv.tv_sec;
 246         }
 247         ntvp->maxerror = time_maxerror;
 248         ntvp->esterror = time_esterror;
 249         ntvp->tai = time_tai;
 250         ntvp->time_state = time_state;
 251
 252         if (ntp_is_time_error(time_status)) {
 253                 ntvp->time_state = TIME_ERROR;
 254         }
 255 }
 256
 257 int
 258 ntp_gettime(struct proc *p, struct ntp_gettime_args *uap, __unused int32_t *retval)
 259 {
 260         struct ntptimeval ntv;
 261         int error;
 262         boolean_t enable;
 263
 264         NTP_LOCK(enable);
 265         ntp_gettime1(&ntv);
 266         NTP_UNLOCK(enable);
 267
 268         if (IS_64BIT_PROCESS(p)) {
 269                 struct user64_ntptimeval user_ntv = {};
 270                 user_ntv.time.tv_sec = ntv.time.tv_sec;
 271                 user_ntv.time.tv_nsec = ntv.time.tv_nsec;
 272                 user_ntv.maxerror = ntv.maxerror;
 273                 user_ntv.esterror = ntv.esterror;
 274                 user_ntv.tai = ntv.tai;
 275                 user_ntv.time_state = ntv.time_state;
 276                 error = copyout(&user_ntv, uap->ntvp, sizeof(user_ntv));
 277         } else {
 278                 struct user32_ntptimeval user_ntv = {};
 279                 user_ntv.time.tv_sec = (user32_long_t)ntv.time.tv_sec;
 280                 user_ntv.time.tv_nsec = (user32_long_t)ntv.time.tv_nsec;
 281                 user_ntv.maxerror = (user32_long_t)ntv.maxerror;
 282                 user_ntv.esterror = (user32_long_t)ntv.esterror;
 283                 user_ntv.tai = (user32_long_t)ntv.tai;
 284                 user_ntv.time_state = ntv.time_state;
 285                 error = copyout(&user_ntv, uap->ntvp, sizeof(user_ntv));
 286         }
 287
 288         if (error) {
 289                 return error;
 290         }
 291
 292         return ntv.time_state;
 293 }
 294
 295 int
 296 ntp_adjtime(struct proc *p, struct ntp_adjtime_args *uap, int32_t *retval)
 297 {
 298         struct timex ntv = {};
 299         long freq;
 300         unsigned int modes;
 301         int error, ret = 0;
 302         clock_sec_t sec;
 303         clock_usec_t microsecs;
 304         boolean_t enable;
 305
 306         if (IS_64BIT_PROCESS(p)) {
 307                 struct user64_timex user_ntv;
 308                 error = copyin(uap->tp, &user_ntv, sizeof(user_ntv));
 309                 ntv.modes = user_ntv.modes;
 310                 ntv.offset = (long)user_ntv.offset;
 311                 ntv.freq = (long)user_ntv.freq;
 312                 ntv.maxerror = (long)user_ntv.maxerror;
 313                 ntv.esterror = (long)user_ntv.esterror;
 314                 ntv.status = user_ntv.status;
 315                 ntv.constant = (long)user_ntv.constant;
 316                 ntv.precision = (long)user_ntv.precision;
 317                 ntv.tolerance = (long)user_ntv.tolerance;
 318         } else {
 319                 struct user32_timex user_ntv;
 320                 error = copyin(uap->tp, &user_ntv, sizeof(user_ntv));
 321                 ntv.modes = user_ntv.modes;
 322                 ntv.offset = user_ntv.offset;
 323                 ntv.freq = user_ntv.freq;
 324                 ntv.maxerror = user_ntv.maxerror;
 325                 ntv.esterror = user_ntv.esterror;
 326                 ntv.status = user_ntv.status;
 327                 ntv.constant = user_ntv.constant;
 328                 ntv.precision = user_ntv.precision;
 329                 ntv.tolerance = user_ntv.tolerance;
 330         }
 331         if (error) {
 332                 return error;
 333         }
 334
 335 #if DEVELOPMENT || DEBUG
 336         if (g_should_log_clock_adjustments) {
 337                 os_log(OS_LOG_DEFAULT, "%s: BEFORE modes %u offset %ld freq %ld status %d constant %ld time_adjtime %lld\n",
 338                     __func__, ntv.modes, ntv.offset, ntv.freq, ntv.status, ntv.constant, time_adjtime);
 339         }
 340 #endif
 341         /*
 342          * Update selected clock variables - only the superuser can
 343          * change anything. Note that there is no error checking here on
 344          * the assumption the superuser should know what it is doing.
 345          * Note that either the time constant or TAI offset are loaded
 346          * from the ntv.constant member, depending on the mode bits. If
 347          * the STA_PLL bit in the status word is cleared, the state and
 348          * status words are reset to the initial values at boot.
 349          */
 350         modes = ntv.modes;
 351         if (modes) {
 352                 /* Check that this task is entitled to set the time or it is root */
 353                 if (!IOTaskHasEntitlement(current_task(), SETTIME_ENTITLEMENT)) {
 354 #if CONFIG_MACF
 355                         error = mac_system_check_settime(kauth_cred_get());
 356                         if (error) {
 357                                 return error;
 358                         }
 359 #endif
 360                         if ((error = priv_check_cred(kauth_cred_get(), PRIV_ADJTIME, 0))) {
 361                                 return error;
 362                         }
 363                 }
 364         }
 365
 366         NTP_LOCK(enable);
 367
 368         if (modes & MOD_MAXERROR) {
 369                 clock_gettimeofday(&sec, &microsecs);
 370                 time_maxerror = ntv.maxerror;
 371                 last_time_maxerror_update = sec;
 372         }
 373         if (modes & MOD_ESTERROR) {
 374                 time_esterror = ntv.esterror;
 375         }
 376         if (modes & MOD_STATUS) {
 377                 if (time_status & STA_PLL && !(ntv.status & STA_PLL)) {
 378                         time_state = TIME_OK;
 379                         time_status = STA_UNSYNC;
 380                 }
 381                 time_status &= STA_RONLY;
 382                 time_status |= ntv.status & ~STA_RONLY;
 383                 /*
 384                  * Nor PPS or leaps seconds are supported.
 385                  * Filter out unsupported bits.
 386                  */
 387                 time_status &= STA_SUPPORTED;
 388         }
 389         if (modes & MOD_TIMECONST) {
 390                 if (ntv.constant < 0) {
 391                         time_constant = 0;
 392                 } else if (ntv.constant > MAXTC) {
 393                         time_constant = MAXTC;
 394                 } else {
 395                         time_constant = ntv.constant;
 396                 }
 397         }
 398         if (modes & MOD_TAI) {
 399                 if (ntv.constant > 0) {
 400                         time_tai = ntv.constant;
 401                 }
 402         }
 403         if (modes & MOD_NANO) {
 404                 time_status |= STA_NANO;
 405         }
 406         if (modes & MOD_MICRO) {
 407                 time_status &= ~STA_NANO;
 408         }
 409         if (modes & MOD_CLKB) {
 410                 time_status |= STA_CLK;
 411         }
 412         if (modes & MOD_CLKA) {
 413                 time_status &= ~STA_CLK;
 414         }
 415         if (modes & MOD_FREQUENCY) {
 416                 freq = (ntv.freq * 1000LL) >> 16;
 417                 if (freq > MAXFREQ) {
 418                         L_LINT(time_freq, MAXFREQ);
 419                 } else if (freq < -MAXFREQ) {
 420                         L_LINT(time_freq, -MAXFREQ);
 421                 } else {
 422                         /*
 423                          * ntv.freq is [PPM * 2^16] = [us/s * 2^16]
 424                          * time_freq is [ns/s * 2^32]
 425                          */
 426                         time_freq = ntv.freq * 1000LL * 65536LL;
 427                 }
 428         }
 429         if (modes & MOD_OFFSET) {
 430                 if (time_status & STA_NANO) {
 431                         hardupdate(ntv.offset);
 432                 } else {
 433                         hardupdate(ntv.offset * 1000);
 434                 }
 435         }
 436
 437         ret = ntp_is_time_error(time_status) ? TIME_ERROR : time_state;
 438
 439 #if DEVELOPMENT || DEBUG
 440         if (g_should_log_clock_adjustments) {
 441                 os_log(OS_LOG_DEFAULT, "%s: AFTER modes %u offset %lld freq %lld status %d constant %ld time_adjtime %lld\n",
 442                     __func__, modes, time_offset, time_freq, time_status, time_constant, time_adjtime);
 443         }
 444 #endif
 445
 446         /*
 447          * Retrieve all clock variables. Note that the TAI offset is
 448          * returned only by ntp_gettime();
 449          */
 450         if (IS_64BIT_PROCESS(p)) {
 451                 struct user64_timex user_ntv = {};
 452
 453                 user_ntv.modes = modes;
 454                 if (time_status & STA_NANO) {
 455                         user_ntv.offset = L_GINT(time_offset);
 456                 } else {
 457                         user_ntv.offset = L_GINT(time_offset) / 1000;
 458                 }
 459                 if (time_freq > 0) {
 460                         user_ntv.freq = L_GINT(((int64_t)(time_freq / 1000LL)) << 16);
 461                 } else {
 462                         user_ntv.freq = -L_GINT(((int64_t)(-(time_freq) / 1000LL)) << 16);
 463                 }
 464                 user_ntv.maxerror = time_maxerror;
 465                 user_ntv.esterror = time_esterror;
 466                 user_ntv.status = time_status;
 467                 user_ntv.constant = time_constant;
 468                 if (time_status & STA_NANO) {
 469                         user_ntv.precision = time_precision;
 470                 } else {
 471                         user_ntv.precision = time_precision / 1000;
 472                 }
 473                 user_ntv.tolerance = MAXFREQ * SCALE_PPM;
 474
 475                 /* unlock before copyout */
 476                 NTP_UNLOCK(enable);
 477
 478                 error = copyout(&user_ntv, uap->tp, sizeof(user_ntv));
 479         } else {
 480                 struct user32_timex user_ntv = {};
 481
 482                 user_ntv.modes = modes;
 483                 if (time_status & STA_NANO) {
 484                         user_ntv.offset = L_GINT(time_offset);
 485                 } else {
 486                         user_ntv.offset = L_GINT(time_offset) / 1000;
 487                 }
 488                 if (time_freq > 0) {
 489                         user_ntv.freq = L_GINT((time_freq / 1000LL) << 16);
 490                 } else {
 491                         user_ntv.freq = -L_GINT((-(time_freq) / 1000LL) << 16);
 492                 }
 493                 user_ntv.maxerror = (user32_long_t)time_maxerror;
 494                 user_ntv.esterror = (user32_long_t)time_esterror;
 495                 user_ntv.status = time_status;
 496                 user_ntv.constant = (user32_long_t)time_constant;
 497                 if (time_status & STA_NANO) {
 498                         user_ntv.precision = (user32_long_t)time_precision;
 499                 } else {
 500                         user_ntv.precision = (user32_long_t)(time_precision / 1000);
 501                 }
 502                 user_ntv.tolerance = MAXFREQ * SCALE_PPM;
 503
 504                 /* unlock before copyout */
 505                 NTP_UNLOCK(enable);
 506
 507                 error = copyout(&user_ntv, uap->tp, sizeof(user_ntv));
 508         }
 509
 510         if (modes) {
 511                 start_ntp_loop();
 512         }
 513
 514         if (error == 0) {
 515                 *retval = ret;
 516         }
 517
 518         return error;
 519 }
 520
 521 int64_t
 522 ntp_get_freq(void)
 523 {
 524         return time_freq;
 525 }
 526
 527 /*
 528  * Compute the adjustment to add to the next second.
 529  */
 530 void
 531 ntp_update_second(int64_t *adjustment, clock_sec_t secs)
 532 {
 533         int tickrate;
 534         l_fp time_adj;
 535         l_fp ftemp, old_time_adjtime, old_offset;
 536
 537         NTP_ASSERT_LOCKED();
 538
 539         if (secs > last_time_maxerror_update) {
 540                 time_maxerror += (MAXFREQ / 1000) * (secs - last_time_maxerror_update);
 541                 last_time_maxerror_update = secs;
 542         }
 543
 544         old_offset = time_offset;
 545         old_time_adjtime = time_adjtime;
 546
 547         ftemp = time_offset;
 548         L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
 549         time_adj = ftemp;
 550         L_SUB(time_offset, ftemp);
 551         L_ADD(time_adj, time_freq);
 552
 553         /*
 554          * Apply any correction from adjtime.  If more than one second
 555          * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM)
 556          * until the last second is slewed the final < 500 usecs.
 557          */
 558         if (time_adjtime != 0) {
 559                 if (time_adjtime > 1000000) {
 560                         tickrate = 5000;
 561                 } else if (time_adjtime < -1000000) {
 562                         tickrate = -5000;
 563                 } else if (time_adjtime > 500) {
 564                         tickrate = 500;
 565                 } else if (time_adjtime < -500) {
 566                         tickrate = -500;
 567                 } else {
 568                         tickrate = (int)time_adjtime;
 569                 }
 570                 time_adjtime -= tickrate;
 571                 L_LINT(ftemp, tickrate * 1000);
 572                 L_ADD(time_adj, ftemp);
 573         }
 574
 575         if (old_time_adjtime || ((time_offset || old_offset) && (time_offset != old_offset))) {
 576                 updated = 1;
 577         } else {
 578                 updated = 0;
 579         }
 580
 581 #if DEVELOPMENT || DEBUG
 582         if (g_should_log_clock_adjustments) {
 583                 int64_t nano = (time_adj > 0)? time_adj >> 32 : -((-time_adj) >> 32);
 584                 int64_t frac = (time_adj > 0)? ((uint32_t) time_adj) : -((uint32_t) (-time_adj));
 585
 586                 os_log(OS_LOG_DEFAULT, "%s:AFTER offset %lld (%lld) freq %lld status %d "
 587                     "constant %ld time_adjtime %lld nano %lld frac %lld adj %lld\n",
 588                     __func__, time_offset, (time_offset > 0)? time_offset >> 32 : -((-time_offset) >> 32),
 589                     time_freq, time_status, time_constant, time_adjtime, nano, frac, time_adj);
 590         }
 591 #endif
 592
 593         *adjustment = time_adj;
 594 }
 595
 596 /*
 597  * hardupdate() - local clock update
 598  *
 599  * This routine is called by ntp_adjtime() when an offset is provided
 600  * to update the local clock phase and frequency.
 601  * The implementation is of an adaptive-parameter, hybrid
 602  * phase/frequency-lock loop (PLL/FLL). The routine computes new
 603  * time and frequency offset estimates for each call.
 604  * Presumably, calls to ntp_adjtime() occur only when the caller
 605  * believes the local clock is valid within some bound (+-128 ms with
 606  * NTP).
 607  *
 608  * For uncompensated quartz crystal oscillators and nominal update
 609  * intervals less than 256 s, operation should be in phase-lock mode,
 610  * where the loop is disciplined to phase. For update intervals greater
 611  * than 1024 s, operation should be in frequency-lock mode, where the
 612  * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
 613  * is selected by the STA_MODE status bit.
 614  */
 615 static void
 616 hardupdate(offset)
 617 long offset;
 618 {
 619         long mtemp = 0;
 620         long time_monitor;
 621         clock_sec_t time_uptime;
 622         l_fp ftemp;
 623
 624         NTP_ASSERT_LOCKED();
 625
 626         if (!(time_status & STA_PLL)) {
 627                 return;
 628         }
 629
 630         if (offset > MAXPHASE) {
 631                 time_monitor = MAXPHASE;
 632         } else if (offset < -MAXPHASE) {
 633                 time_monitor = -MAXPHASE;
 634         } else {
 635                 time_monitor = offset;
 636         }
 637         L_LINT(time_offset, time_monitor);
 638
 639         clock_get_calendar_uptime(&time_uptime);
 640
 641         if (time_status & STA_FREQHOLD || time_reftime == 0) {
 642                 time_reftime = time_uptime;
 643         }
 644
 645         mtemp = time_uptime - time_reftime;
 646         L_LINT(ftemp, time_monitor);
 647         L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
 648         L_MPY(ftemp, mtemp);
 649         L_ADD(time_freq, ftemp);
 650         time_status &= ~STA_MODE;
 651         if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
 652             MAXSEC)) {
 653                 L_LINT(ftemp, (time_monitor << 4) / mtemp);
 654                 L_RSHIFT(ftemp, SHIFT_FLL + 4);
 655                 L_ADD(time_freq, ftemp);
 656                 time_status |= STA_MODE;
 657         }
 658         time_reftime = time_uptime;
 659
 660         if (L_GINT(time_freq) > MAXFREQ) {
 661                 L_LINT(time_freq, MAXFREQ);
 662         } else if (L_GINT(time_freq) < -MAXFREQ) {
 663                 L_LINT(time_freq, -MAXFREQ);
 664         }
 665 }
 666
 667
 668 static int
 669 kern_adjtime(struct timeval *delta)
 670 {
 671         struct timeval atv;
 672         int64_t ltr, ltw;
 673         boolean_t enable;
 674
 675         if (delta == NULL) {
 676                 return EINVAL;
 677         }
 678
 679         ltw = (int64_t)delta->tv_sec * (int64_t)USEC_PER_SEC + delta->tv_usec;
 680
 681         NTP_LOCK(enable);
 682         ltr = time_adjtime;
 683         time_adjtime = ltw;
 684 #if DEVELOPMENT || DEBUG
 685         if (g_should_log_clock_adjustments) {
 686                 os_log(OS_LOG_DEFAULT, "%s:AFTER offset %lld freq %lld status %d constant %ld time_adjtime %lld\n",
 687                     __func__, time_offset, time_freq, time_status, time_constant, time_adjtime);
 688         }
 689 #endif
 690         NTP_UNLOCK(enable);
 691
 692         atv.tv_sec = (__darwin_time_t)(ltr / (int64_t)USEC_PER_SEC);
 693         atv.tv_usec = ltr % (int64_t)USEC_PER_SEC;
 694         if (atv.tv_usec < 0) {
 695                 atv.tv_usec += (suseconds_t)USEC_PER_SEC;
 696                 atv.tv_sec--;
 697         }
 698
 699         *delta = atv;
 700
 701         start_ntp_loop();
 702
 703         return 0;
 704 }
 705
 706 int
 707 adjtime(struct proc *p, struct adjtime_args *uap, __unused int32_t *retval)
 708 {
 709         struct timeval atv;
 710         int error;
 711
 712         /* Check that this task is entitled to set the time or it is root */
 713         if (!IOTaskHasEntitlement(current_task(), SETTIME_ENTITLEMENT)) {
 714 #if CONFIG_MACF
 715                 error = mac_system_check_settime(kauth_cred_get());
 716                 if (error) {
 717                         return error;
 718                 }
 719 #endif
 720                 if ((error = priv_check_cred(kauth_cred_get(), PRIV_ADJTIME, 0))) {
 721                         return error;
 722                 }
 723         }
 724
 725         if (IS_64BIT_PROCESS(p)) {
 726                 struct user64_timeval user_atv;
 727                 error = copyin(uap->delta, &user_atv, sizeof(user_atv));
 728                 atv.tv_sec = (__darwin_time_t)user_atv.tv_sec;
 729                 atv.tv_usec = user_atv.tv_usec;
 730         } else {
 731                 struct user32_timeval user_atv;
 732                 error = copyin(uap->delta, &user_atv, sizeof(user_atv));
 733                 atv.tv_sec = user_atv.tv_sec;
 734                 atv.tv_usec = user_atv.tv_usec;
 735         }
 736         if (error) {
 737                 return error;
 738         }
 739
 740         kern_adjtime(&atv);
 741
 742         if (uap->olddelta) {
 743                 if (IS_64BIT_PROCESS(p)) {
 744                         struct user64_timeval user_atv = {};
 745                         user_atv.tv_sec = atv.tv_sec;
 746                         user_atv.tv_usec = atv.tv_usec;
 747                         error = copyout(&user_atv, uap->olddelta, sizeof(user_atv));
 748                 } else {
 749                         struct user32_timeval user_atv = {};
 750                         user_atv.tv_sec = (user32_time_t)atv.tv_sec;
 751                         user_atv.tv_usec = atv.tv_usec;
 752                         error = copyout(&user_atv, uap->olddelta, sizeof(user_atv));
 753                 }
 754         }
 755
 756         return error;
 757 }
 758
 759 static void
 760 ntp_loop_update_call(void)
 761 {
 762         boolean_t enable;
 763
 764         NTP_LOCK(enable);
 765
 766         /*
 767          * Update the scale factor used by clock_calend.
 768          * NOTE: clock_update_calendar will call ntp_update_second to compute the next adjustment.
 769          */
 770         clock_update_calendar();
 771
 772         refresh_ntp_loop();
 773
 774         NTP_UNLOCK(enable);
 775 }
 776
 777 static void
 778 refresh_ntp_loop(void)
 779 {
 780         NTP_ASSERT_LOCKED();
 781         if (--ntp_loop_active == 0) {
 782                 /*
 783                  * Activate the timer only if the next second adjustment might change.
 784                  * ntp_update_second checks it and sets updated accordingly.
 785                  */
 786                 if (updated) {
 787                         clock_deadline_for_periodic_event(ntp_loop_period, mach_absolute_time(), &ntp_loop_deadline);
 788
 789                         if (!timer_call_enter(&ntp_loop_update, ntp_loop_deadline, TIMER_CALL_SYS_CRITICAL)) {
 790                                 ntp_loop_active++;
 791                         }
 792                 }
 793         }
 794 }
 795
 796 /*
 797  * This function triggers a timer that each second will calculate the adjustment to
 798  * provide to clock_calendar to scale the time (used by gettimeofday-family syscalls).
 799  * The periodic timer will stop when the adjustment will reach a stable value.
 800  */
 801 static void
 802 start_ntp_loop(void)
 803 {
 804         boolean_t enable;
 805
 806         NTP_LOCK(enable);
 807
 808         ntp_loop_deadline = mach_absolute_time() + ntp_loop_period;
 809
 810         if (!timer_call_enter(&ntp_loop_update, ntp_loop_deadline, TIMER_CALL_SYS_CRITICAL)) {
 811                 ntp_loop_active++;
 812         }
 813
 814         NTP_UNLOCK(enable);
 815 }
 816
 817
 818 static void
 819 init_ntp_loop(void)
 820 {
 821         uint64_t        abstime;
 822
 823         ntp_loop_active = 0;
 824         nanoseconds_to_absolutetime(NTP_LOOP_PERIOD_INTERVAL, &abstime);
 825         ntp_loop_period = (uint32_t)abstime;
 826         timer_call_setup(&ntp_loop_update, (timer_call_func_t)ntp_loop_update_call, NULL);
 827 }
 828
 829 void
 830 ntp_init(void)
 831 {
 832         init_ntp_loop();
 833 }