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_spin_t * ntp_lock;
 191 static lck_grp_t * ntp_lock_grp;
 192 static lck_attr_t * ntp_lock_attr;
 193 static lck_grp_attr_t   *ntp_lock_grp_attr;
 194
 195 #define NTP_LOCK(enable) \
 196                 enable =  ml_set_interrupts_enabled(FALSE); \
 197                 lck_spin_lock(ntp_lock);
 198
 199 #define NTP_UNLOCK(enable) \
 200                 lck_spin_unlock(ntp_lock);\
 201                 ml_set_interrupts_enabled(enable);
 202
 203 #define NTP_ASSERT_LOCKED()     LCK_SPIN_ASSERT(ntp_lock, LCK_ASSERT_OWNED)
 204
 205 static timer_call_data_t ntp_loop_update;
 206 static uint64_t ntp_loop_deadline;
 207 static uint32_t ntp_loop_active;
 208 static uint32_t ntp_loop_period;
 209 #define NTP_LOOP_PERIOD_INTERVAL (NSEC_PER_SEC) /*1 second interval*/
 210
 211 void ntp_init(void);
 212 static void hardupdate(long offset);
 213 static void ntp_gettime1(struct ntptimeval *ntvp);
 214 static bool ntp_is_time_error(int tsl);
 215
 216 static void ntp_loop_update_call(void);
 217 static void refresh_ntp_loop(void);
 218 static void start_ntp_loop(void);
 219
 220 #if DEVELOPMENT || DEBUG
 221 uint32_t g_should_log_clock_adjustments = 0;
 222 SYSCTL_INT(_kern, OID_AUTO, log_clock_adjustments, CTLFLAG_RW | CTLFLAG_LOCKED, &g_should_log_clock_adjustments, 0, "enable kernel clock adjustment logging");
 223 #endif
 224
 225 static bool
 226 ntp_is_time_error(int tsl)
 227 {
 228         if (tsl & (STA_UNSYNC | STA_CLOCKERR)) {
 229                 return true;
 230         }
 231
 232         return false;
 233 }
 234
 235 static void
 236 ntp_gettime1(struct ntptimeval *ntvp)
 237 {
 238         struct timespec atv;
 239
 240         NTP_ASSERT_LOCKED();
 241
 242         nanotime(&atv);
 243         ntvp->time.tv_sec = atv.tv_sec;
 244         ntvp->time.tv_nsec = atv.tv_nsec;
 245         if ((unsigned long)atv.tv_sec > last_time_maxerror_update) {
 246                 time_maxerror += (MAXFREQ / 1000) * (atv.tv_sec - last_time_maxerror_update);
 247                 last_time_maxerror_update = atv.tv_sec;
 248         }
 249         ntvp->maxerror = time_maxerror;
 250         ntvp->esterror = time_esterror;
 251         ntvp->tai = time_tai;
 252         ntvp->time_state = time_state;
 253
 254         if (ntp_is_time_error(time_status)) {
 255                 ntvp->time_state = TIME_ERROR;
 256         }
 257 }
 258
 259 int
 260 ntp_gettime(struct proc *p, struct ntp_gettime_args *uap, __unused int32_t *retval)
 261 {
 262         struct ntptimeval ntv;
 263         int error;
 264         boolean_t enable;
 265
 266         NTP_LOCK(enable);
 267         ntp_gettime1(&ntv);
 268         NTP_UNLOCK(enable);
 269
 270         if (IS_64BIT_PROCESS(p)) {
 271                 struct user64_ntptimeval user_ntv = {};
 272                 user_ntv.time.tv_sec = ntv.time.tv_sec;
 273                 user_ntv.time.tv_nsec = ntv.time.tv_nsec;
 274                 user_ntv.maxerror = ntv.maxerror;
 275                 user_ntv.esterror = ntv.esterror;
 276                 user_ntv.tai = ntv.tai;
 277                 user_ntv.time_state = ntv.time_state;
 278                 error = copyout(&user_ntv, uap->ntvp, sizeof(user_ntv));
 279         } else {
 280                 struct user32_ntptimeval user_ntv = {};
 281                 user_ntv.time.tv_sec = ntv.time.tv_sec;
 282                 user_ntv.time.tv_nsec = ntv.time.tv_nsec;
 283                 user_ntv.maxerror = ntv.maxerror;
 284                 user_ntv.esterror = ntv.esterror;
 285                 user_ntv.tai = ntv.tai;
 286                 user_ntv.time_state = ntv.time_state;
 287                 error = copyout(&user_ntv, uap->ntvp, sizeof(user_ntv));
 288         }
 289
 290         if (error) {
 291                 return error;
 292         }
 293
 294         return ntv.time_state;
 295 }
 296
 297 int
 298 ntp_adjtime(struct proc *p, struct ntp_adjtime_args *uap, int32_t *retval)
 299 {
 300         struct timex ntv = {};
 301         long freq;
 302         unsigned int modes;
 303         int error, ret = 0;
 304         clock_sec_t sec;
 305         clock_usec_t microsecs;
 306         boolean_t enable;
 307
 308         if (IS_64BIT_PROCESS(p)) {
 309                 struct user64_timex user_ntv;
 310                 error = copyin(uap->tp, &user_ntv, sizeof(user_ntv));
 311                 ntv.modes = user_ntv.modes;
 312                 ntv.offset = user_ntv.offset;
 313                 ntv.freq = user_ntv.freq;
 314                 ntv.maxerror = user_ntv.maxerror;
 315                 ntv.esterror = user_ntv.esterror;
 316                 ntv.status = user_ntv.status;
 317                 ntv.constant = user_ntv.constant;
 318                 ntv.precision = user_ntv.precision;
 319                 ntv.tolerance = user_ntv.tolerance;
 320         } else {
 321                 struct user32_timex user_ntv;
 322                 error = copyin(uap->tp, &user_ntv, sizeof(user_ntv));
 323                 ntv.modes = user_ntv.modes;
 324                 ntv.offset = user_ntv.offset;
 325                 ntv.freq = user_ntv.freq;
 326                 ntv.maxerror = user_ntv.maxerror;
 327                 ntv.esterror = user_ntv.esterror;
 328                 ntv.status = user_ntv.status;
 329                 ntv.constant = user_ntv.constant;
 330                 ntv.precision = user_ntv.precision;
 331                 ntv.tolerance = user_ntv.tolerance;
 332         }
 333         if (error) {
 334                 return error;
 335         }
 336
 337 #if DEVELOPMENT || DEBUG
 338         if (g_should_log_clock_adjustments) {
 339                 os_log(OS_LOG_DEFAULT, "%s: BEFORE modes %u offset %ld freq %ld status %d constant %ld time_adjtime %lld\n",
 340                     __func__, ntv.modes, ntv.offset, ntv.freq, ntv.status, ntv.constant, time_adjtime);
 341         }
 342 #endif
 343         /*
 344          * Update selected clock variables - only the superuser can
 345          * change anything. Note that there is no error checking here on
 346          * the assumption the superuser should know what it is doing.
 347          * Note that either the time constant or TAI offset are loaded
 348          * from the ntv.constant member, depending on the mode bits. If
 349          * the STA_PLL bit in the status word is cleared, the state and
 350          * status words are reset to the initial values at boot.
 351          */
 352         modes = ntv.modes;
 353         if (modes) {
 354                 /* Check that this task is entitled to set the time or it is root */
 355                 if (!IOTaskHasEntitlement(current_task(), SETTIME_ENTITLEMENT)) {
 356 #if CONFIG_MACF
 357                         error = mac_system_check_settime(kauth_cred_get());
 358                         if (error) {
 359                                 return error;
 360                         }
 361 #endif
 362                         if ((error = priv_check_cred(kauth_cred_get(), PRIV_ADJTIME, 0))) {
 363                                 return error;
 364                         }
 365                 }
 366         }
 367
 368         NTP_LOCK(enable);
 369
 370         if (modes & MOD_MAXERROR) {
 371                 clock_gettimeofday(&sec, &microsecs);
 372                 time_maxerror = ntv.maxerror;
 373                 last_time_maxerror_update = sec;
 374         }
 375         if (modes & MOD_ESTERROR) {
 376                 time_esterror = ntv.esterror;
 377         }
 378         if (modes & MOD_STATUS) {
 379                 if (time_status & STA_PLL && !(ntv.status & STA_PLL)) {
 380                         time_state = TIME_OK;
 381                         time_status = STA_UNSYNC;
 382                 }
 383                 time_status &= STA_RONLY;
 384                 time_status |= ntv.status & ~STA_RONLY;
 385                 /*
 386                  * Nor PPS or leaps seconds are supported.
 387                  * Filter out unsupported bits.
 388                  */
 389                 time_status &= STA_SUPPORTED;
 390         }
 391         if (modes & MOD_TIMECONST) {
 392                 if (ntv.constant < 0) {
 393                         time_constant = 0;
 394                 } else if (ntv.constant > MAXTC) {
 395                         time_constant = MAXTC;
 396                 } else {
 397                         time_constant = ntv.constant;
 398                 }
 399         }
 400         if (modes & MOD_TAI) {
 401                 if (ntv.constant > 0) {
 402                         time_tai = ntv.constant;
 403                 }
 404         }
 405         if (modes & MOD_NANO) {
 406                 time_status |= STA_NANO;
 407         }
 408         if (modes & MOD_MICRO) {
 409                 time_status &= ~STA_NANO;
 410         }
 411         if (modes & MOD_CLKB) {
 412                 time_status |= STA_CLK;
 413         }
 414         if (modes & MOD_CLKA) {
 415                 time_status &= ~STA_CLK;
 416         }
 417         if (modes & MOD_FREQUENCY) {
 418                 freq = (ntv.freq * 1000LL) >> 16;
 419                 if (freq > MAXFREQ) {
 420                         L_LINT(time_freq, MAXFREQ);
 421                 } else if (freq < -MAXFREQ) {
 422                         L_LINT(time_freq, -MAXFREQ);
 423                 } else {
 424                         /*
 425                          * ntv.freq is [PPM * 2^16] = [us/s * 2^16]
 426                          * time_freq is [ns/s * 2^32]
 427                          */
 428                         time_freq = ntv.freq * 1000LL * 65536LL;
 429                 }
 430         }
 431         if (modes & MOD_OFFSET) {
 432                 if (time_status & STA_NANO) {
 433                         hardupdate(ntv.offset);
 434                 } else {
 435                         hardupdate(ntv.offset * 1000);
 436                 }
 437         }
 438
 439         ret = ntp_is_time_error(time_status) ? TIME_ERROR : time_state;
 440
 441 #if DEVELOPMENT || DEBUG
 442         if (g_should_log_clock_adjustments) {
 443                 os_log(OS_LOG_DEFAULT, "%s: AFTER modes %u offset %lld freq %lld status %d constant %ld time_adjtime %lld\n",
 444                     __func__, modes, time_offset, time_freq, time_status, time_constant, time_adjtime);
 445         }
 446 #endif
 447
 448         /*
 449          * Retrieve all clock variables. Note that the TAI offset is
 450          * returned only by ntp_gettime();
 451          */
 452         if (IS_64BIT_PROCESS(p)) {
 453                 struct user64_timex user_ntv = {};
 454
 455                 user_ntv.modes = modes;
 456                 if (time_status & STA_NANO) {
 457                         user_ntv.offset = L_GINT(time_offset);
 458                 } else {
 459                         user_ntv.offset = L_GINT(time_offset) / 1000;
 460                 }
 461                 user_ntv.freq = L_GINT((time_freq / 1000LL) << 16);
 462                 user_ntv.maxerror = time_maxerror;
 463                 user_ntv.esterror = time_esterror;
 464                 user_ntv.status = time_status;
 465                 user_ntv.constant = time_constant;
 466                 if (time_status & STA_NANO) {
 467                         user_ntv.precision = time_precision;
 468                 } else {
 469                         user_ntv.precision = time_precision / 1000;
 470                 }
 471                 user_ntv.tolerance = MAXFREQ * SCALE_PPM;
 472
 473                 /* unlock before copyout */
 474                 NTP_UNLOCK(enable);
 475
 476                 error = copyout(&user_ntv, uap->tp, sizeof(user_ntv));
 477         } else {
 478                 struct user32_timex user_ntv = {};
 479
 480                 user_ntv.modes = modes;
 481                 if (time_status & STA_NANO) {
 482                         user_ntv.offset = L_GINT(time_offset);
 483                 } else {
 484                         user_ntv.offset = L_GINT(time_offset) / 1000;
 485                 }
 486                 user_ntv.freq = L_GINT((time_freq / 1000LL) << 16);
 487                 user_ntv.maxerror = time_maxerror;
 488                 user_ntv.esterror = time_esterror;
 489                 user_ntv.status = time_status;
 490                 user_ntv.constant = time_constant;
 491                 if (time_status & STA_NANO) {
 492                         user_ntv.precision = time_precision;
 493                 } else {
 494                         user_ntv.precision = time_precision / 1000;
 495                 }
 496                 user_ntv.tolerance = MAXFREQ * SCALE_PPM;
 497
 498                 /* unlock before copyout */
 499                 NTP_UNLOCK(enable);
 500
 501                 error = copyout(&user_ntv, uap->tp, sizeof(user_ntv));
 502         }
 503
 504         if (modes) {
 505                 start_ntp_loop();
 506         }
 507
 508         if (error == 0) {
 509                 *retval = ret;
 510         }
 511
 512         return error;
 513 }
 514
 515 int64_t
 516 ntp_get_freq(void)
 517 {
 518         return time_freq;
 519 }
 520
 521 /*
 522  * Compute the adjustment to add to the next second.
 523  */
 524 void
 525 ntp_update_second(int64_t *adjustment, clock_sec_t secs)
 526 {
 527         int tickrate;
 528         l_fp time_adj;
 529         l_fp ftemp, old_time_adjtime, old_offset;
 530
 531         NTP_ASSERT_LOCKED();
 532
 533         if (secs > last_time_maxerror_update) {
 534                 time_maxerror += (MAXFREQ / 1000) * (secs - last_time_maxerror_update);
 535                 last_time_maxerror_update = secs;
 536         }
 537
 538         old_offset = time_offset;
 539         old_time_adjtime = time_adjtime;
 540
 541         ftemp = time_offset;
 542         L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
 543         time_adj = ftemp;
 544         L_SUB(time_offset, ftemp);
 545         L_ADD(time_adj, time_freq);
 546
 547         /*
 548          * Apply any correction from adjtime.  If more than one second
 549          * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM)
 550          * until the last second is slewed the final < 500 usecs.
 551          */
 552         if (time_adjtime != 0) {
 553                 if (time_adjtime > 1000000) {
 554                         tickrate = 5000;
 555                 } else if (time_adjtime < -1000000) {
 556                         tickrate = -5000;
 557                 } else if (time_adjtime > 500) {
 558                         tickrate = 500;
 559                 } else if (time_adjtime < -500) {
 560                         tickrate = -500;
 561                 } else {
 562                         tickrate = time_adjtime;
 563                 }
 564                 time_adjtime -= tickrate;
 565                 L_LINT(ftemp, tickrate * 1000);
 566                 L_ADD(time_adj, ftemp);
 567         }
 568
 569         if (old_time_adjtime || ((time_offset || old_offset) && (time_offset != old_offset))) {
 570                 updated = 1;
 571         } else {
 572                 updated = 0;
 573         }
 574
 575 #if DEVELOPMENT || DEBUG
 576         if (g_should_log_clock_adjustments) {
 577                 int64_t nano = (time_adj > 0)? time_adj >> 32 : -((-time_adj) >> 32);
 578                 int64_t frac = (time_adj > 0)? ((uint32_t) time_adj) : -((uint32_t) (-time_adj));
 579
 580                 os_log(OS_LOG_DEFAULT, "%s:AFTER offset %lld (%lld) freq %lld status %d "
 581                     "constant %ld time_adjtime %lld nano %lld frac %lld adj %lld\n",
 582                     __func__, time_offset, (time_offset > 0)? time_offset >> 32 : -((-time_offset) >> 32),
 583                     time_freq, time_status, time_constant, time_adjtime, nano, frac, time_adj);
 584         }
 585 #endif
 586
 587         *adjustment = time_adj;
 588 }
 589
 590 /*
 591  * hardupdate() - local clock update
 592  *
 593  * This routine is called by ntp_adjtime() when an offset is provided
 594  * to update the local clock phase and frequency.
 595  * The implementation is of an adaptive-parameter, hybrid
 596  * phase/frequency-lock loop (PLL/FLL). The routine computes new
 597  * time and frequency offset estimates for each call.
 598  * Presumably, calls to ntp_adjtime() occur only when the caller
 599  * believes the local clock is valid within some bound (+-128 ms with
 600  * NTP).
 601  *
 602  * For uncompensated quartz crystal oscillators and nominal update
 603  * intervals less than 256 s, operation should be in phase-lock mode,
 604  * where the loop is disciplined to phase. For update intervals greater
 605  * than 1024 s, operation should be in frequency-lock mode, where the
 606  * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
 607  * is selected by the STA_MODE status bit.
 608  */
 609 static void
 610 hardupdate(offset)
 611 long offset;
 612 {
 613         long mtemp = 0;
 614         long time_monitor;
 615         clock_sec_t time_uptime;
 616         l_fp ftemp;
 617
 618         NTP_ASSERT_LOCKED();
 619
 620         if (!(time_status & STA_PLL)) {
 621                 return;
 622         }
 623
 624         if (offset > MAXPHASE) {
 625                 time_monitor = MAXPHASE;
 626         } else if (offset < -MAXPHASE) {
 627                 time_monitor = -MAXPHASE;
 628         } else {
 629                 time_monitor = offset;
 630         }
 631         L_LINT(time_offset, time_monitor);
 632
 633         clock_get_calendar_uptime(&time_uptime);
 634
 635         if (time_status & STA_FREQHOLD || time_reftime == 0) {
 636                 time_reftime = time_uptime;
 637         }
 638
 639         mtemp = time_uptime - time_reftime;
 640         L_LINT(ftemp, time_monitor);
 641         L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
 642         L_MPY(ftemp, mtemp);
 643         L_ADD(time_freq, ftemp);
 644         time_status &= ~STA_MODE;
 645         if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
 646             MAXSEC)) {
 647                 L_LINT(ftemp, (time_monitor << 4) / mtemp);
 648                 L_RSHIFT(ftemp, SHIFT_FLL + 4);
 649                 L_ADD(time_freq, ftemp);
 650                 time_status |= STA_MODE;
 651         }
 652         time_reftime = time_uptime;
 653
 654         if (L_GINT(time_freq) > MAXFREQ) {
 655                 L_LINT(time_freq, MAXFREQ);
 656         } else if (L_GINT(time_freq) < -MAXFREQ) {
 657                 L_LINT(time_freq, -MAXFREQ);
 658         }
 659 }
 660
 661
 662 static int
 663 kern_adjtime(struct timeval *delta)
 664 {
 665         struct timeval atv;
 666         int64_t ltr, ltw;
 667         boolean_t enable;
 668
 669         if (delta == NULL) {
 670                 return EINVAL;
 671         }
 672
 673         ltw = (int64_t)delta->tv_sec * (int64_t)USEC_PER_SEC + delta->tv_usec;
 674
 675         NTP_LOCK(enable);
 676         ltr = time_adjtime;
 677         time_adjtime = ltw;
 678 #if DEVELOPMENT || DEBUG
 679         if (g_should_log_clock_adjustments) {
 680                 os_log(OS_LOG_DEFAULT, "%s:AFTER offset %lld freq %lld status %d constant %ld time_adjtime %lld\n",
 681                     __func__, time_offset, time_freq, time_status, time_constant, time_adjtime);
 682         }
 683 #endif
 684         NTP_UNLOCK(enable);
 685
 686         atv.tv_sec = ltr / (int64_t)USEC_PER_SEC;
 687         atv.tv_usec = ltr % (int64_t)USEC_PER_SEC;
 688         if (atv.tv_usec < 0) {
 689                 atv.tv_usec += (suseconds_t)USEC_PER_SEC;
 690                 atv.tv_sec--;
 691         }
 692
 693         *delta = atv;
 694
 695         start_ntp_loop();
 696
 697         return 0;
 698 }
 699
 700 int
 701 adjtime(struct proc *p, struct adjtime_args *uap, __unused int32_t *retval)
 702 {
 703         struct timeval atv;
 704         int error;
 705
 706         /* Check that this task is entitled to set the time or it is root */
 707         if (!IOTaskHasEntitlement(current_task(), SETTIME_ENTITLEMENT)) {
 708 #if CONFIG_MACF
 709                 error = mac_system_check_settime(kauth_cred_get());
 710                 if (error) {
 711                         return error;
 712                 }
 713 #endif
 714                 if ((error = priv_check_cred(kauth_cred_get(), PRIV_ADJTIME, 0))) {
 715                         return error;
 716                 }
 717         }
 718
 719         if (IS_64BIT_PROCESS(p)) {
 720                 struct user64_timeval user_atv;
 721                 error = copyin(uap->delta, &user_atv, sizeof(user_atv));
 722                 atv.tv_sec = user_atv.tv_sec;
 723                 atv.tv_usec = user_atv.tv_usec;
 724         } else {
 725                 struct user32_timeval user_atv;
 726                 error = copyin(uap->delta, &user_atv, sizeof(user_atv));
 727                 atv.tv_sec = user_atv.tv_sec;
 728                 atv.tv_usec = user_atv.tv_usec;
 729         }
 730         if (error) {
 731                 return error;
 732         }
 733
 734         kern_adjtime(&atv);
 735
 736         if (uap->olddelta) {
 737                 if (IS_64BIT_PROCESS(p)) {
 738                         struct user64_timeval user_atv = {};
 739                         user_atv.tv_sec = atv.tv_sec;
 740                         user_atv.tv_usec = atv.tv_usec;
 741                         error = copyout(&user_atv, uap->olddelta, sizeof(user_atv));
 742                 } else {
 743                         struct user32_timeval user_atv = {};
 744                         user_atv.tv_sec = atv.tv_sec;
 745                         user_atv.tv_usec = atv.tv_usec;
 746                         error = copyout(&user_atv, uap->olddelta, sizeof(user_atv));
 747                 }
 748         }
 749
 750         return error;
 751 }
 752
 753 static void
 754 ntp_loop_update_call(void)
 755 {
 756         boolean_t enable;
 757
 758         NTP_LOCK(enable);
 759
 760         /*
 761          * Update the scale factor used by clock_calend.
 762          * NOTE: clock_update_calendar will call ntp_update_second to compute the next adjustment.
 763          */
 764         clock_update_calendar();
 765
 766         refresh_ntp_loop();
 767
 768         NTP_UNLOCK(enable);
 769 }
 770
 771 static void
 772 refresh_ntp_loop(void)
 773 {
 774         NTP_ASSERT_LOCKED();
 775         if (--ntp_loop_active == 0) {
 776                 /*
 777                  * Activate the timer only if the next second adjustment might change.
 778                  * ntp_update_second checks it and sets updated accordingly.
 779                  */
 780                 if (updated) {
 781                         clock_deadline_for_periodic_event(ntp_loop_period, mach_absolute_time(), &ntp_loop_deadline);
 782
 783                         if (!timer_call_enter(&ntp_loop_update, ntp_loop_deadline, TIMER_CALL_SYS_CRITICAL)) {
 784                                 ntp_loop_active++;
 785                         }
 786                 }
 787         }
 788 }
 789
 790 /*
 791  * This function triggers a timer that each second will calculate the adjustment to
 792  * provide to clock_calendar to scale the time (used by gettimeofday-family syscalls).
 793  * The periodic timer will stop when the adjustment will reach a stable value.
 794  */
 795 static void
 796 start_ntp_loop(void)
 797 {
 798         boolean_t enable;
 799
 800         NTP_LOCK(enable);
 801
 802         ntp_loop_deadline = mach_absolute_time() + ntp_loop_period;
 803
 804         if (!timer_call_enter(&ntp_loop_update, ntp_loop_deadline, TIMER_CALL_SYS_CRITICAL)) {
 805                 ntp_loop_active++;
 806         }
 807
 808         NTP_UNLOCK(enable);
 809 }
 810
 811
 812 static void
 813 init_ntp_loop(void)
 814 {
 815         uint64_t        abstime;
 816
 817         ntp_loop_active = 0;
 818         nanoseconds_to_absolutetime(NTP_LOOP_PERIOD_INTERVAL, &abstime);
 819         ntp_loop_period = (uint32_t)abstime;
 820         timer_call_setup(&ntp_loop_update, (timer_call_func_t)ntp_loop_update_call, NULL);
 821 }
 822
 823 void
 824 ntp_init(void)
 825 {
 826         L_CLR(time_offset);
 827         L_CLR(time_freq);
 828
 829         ntp_lock_grp_attr = lck_grp_attr_alloc_init();
 830         ntp_lock_grp =  lck_grp_alloc_init("ntp_lock", ntp_lock_grp_attr);
 831         ntp_lock_attr = lck_attr_alloc_init();
 832         ntp_lock = lck_spin_alloc_init(ntp_lock_grp, ntp_lock_attr);
 833
 834         updated = 0;
 835
 836         init_ntp_loop();
 837 }
 838
 839 SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL);