/*- *********************************************************************** * * * Copyright (c) David L. Mills 1993-2001 * * * * Permission to use, copy, modify, and distribute this software and * * its documentation for any purpose and without fee is hereby * * granted, provided that the above copyright notice appears in all * * copies and that both the copyright notice and this permission * * notice appear in supporting documentation, and that the name * * University of Delaware not be used in advertising or publicity * * pertaining to distribution of the software without specific, * * written prior permission. The University of Delaware makes no * * representations about the suitability this software for any * * purpose. It is provided "as is" without express or implied * * warranty. * * * **********************************************************************/ /* * Adapted from the original sources for FreeBSD and timecounters by: * Poul-Henning Kamp . * * The 32bit version of the "LP" macros seems a bit past its "sell by" * date so I have retained only the 64bit version and included it directly * in this file. * * Only minor changes done to interface with the timecounters over in * sys/kern/kern_clock.c. Some of the comments below may be (even more) * confusing and/or plain wrong in that context. */ /* * Copyright (c) 2017 Apple Computer, Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if CONFIG_MACF #include #endif #include #include typedef int64_t l_fp; #define L_ADD(v, u) ((v) += (u)) #define L_SUB(v, u) ((v) -= (u)) #define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32) #define L_NEG(v) ((v) = -(v)) #define L_RSHIFT(v, n) \ do { \ if ((v) < 0) \ (v) = -(-(v) >> (n)); \ else \ (v) = (v) >> (n); \ } while (0) #define L_MPY(v, a) ((v) *= (a)) #define L_CLR(v) ((v) = 0) #define L_ISNEG(v) ((v) < 0) #define L_LINT(v, a) \ do { \ if ((a) > 0) \ ((v) = (int64_t)(a) << 32); \ else \ ((v) = -((int64_t)(-(a)) << 32)); \ } while (0) #define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32) /* * Generic NTP kernel interface * * These routines constitute the Network Time Protocol (NTP) interfaces * for user and daemon application programs. The ntp_gettime() routine * provides the time, maximum error (synch distance) and estimated error * (dispersion) to client user application programs. The ntp_adjtime() * routine is used by the NTP daemon to adjust the calendar clock to an * externally derived time. The time offset and related variables set by * this routine are used by other routines in this module to adjust the * phase and frequency of the clock discipline loop which controls the * system clock. * * When the kernel time is reckoned directly in nanoseconds (NTP_NANO * defined), the time at each tick interrupt is derived directly from * the kernel time variable. When the kernel time is reckoned in * microseconds, (NTP_NANO undefined), the time is derived from the * kernel time variable together with a variable representing the * leftover nanoseconds at the last tick interrupt. In either case, the * current nanosecond time is reckoned from these values plus an * interpolated value derived by the clock routines in another * architecture-specific module. The interpolation can use either a * dedicated counter or a processor cycle counter (PCC) implemented in * some architectures. * */ /* * Phase/frequency-lock loop (PLL/FLL) definitions * * The nanosecond clock discipline uses two variable types, time * variables and frequency variables. Both types are represented as 64- * bit fixed-point quantities with the decimal point between two 32-bit * halves. On a 32-bit machine, each half is represented as a single * word and mathematical operations are done using multiple-precision * arithmetic. On a 64-bit machine, ordinary computer arithmetic is * used. * * A time variable is a signed 64-bit fixed-point number in ns and * fraction. It represents the remaining time offset to be amortized * over succeeding tick interrupts. The maximum time offset is about * 0.5 s and the resolution is about 2.3e-10 ns. * * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 * 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 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * |s s s| ns | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | fraction | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * * A frequency variable is a signed 64-bit fixed-point number in ns/s * and fraction. It represents the ns and fraction to be added to the * kernel time variable at each second. The maximum frequency offset is * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s. * * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 * 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 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * |s s s s s s s s s s s s s| ns/s | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | fraction | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ */ #define SHIFT_PLL 4 #define SHIFT_FLL 2 static int time_state = TIME_OK; int time_status = STA_UNSYNC; static long time_tai; static long time_constant; static long time_precision = 1; static long time_maxerror = MAXPHASE / 1000; static unsigned long last_time_maxerror_update; long time_esterror = MAXPHASE / 1000; static long time_reftime; static l_fp time_offset; static l_fp time_freq; static int64_t time_adjtime; static int updated; static LCK_GRP_DECLARE(ntp_lock_grp, "ntp_lock"); static LCK_SPIN_DECLARE(ntp_lock, &ntp_lock_grp); #define NTP_LOCK(enable) \ enable = ml_set_interrupts_enabled(FALSE); \ lck_spin_lock(&ntp_lock); #define NTP_UNLOCK(enable) \ lck_spin_unlock(&ntp_lock);\ ml_set_interrupts_enabled(enable); #define NTP_ASSERT_LOCKED() LCK_SPIN_ASSERT(&ntp_lock, LCK_ASSERT_OWNED) static timer_call_data_t ntp_loop_update; static uint64_t ntp_loop_deadline; static uint32_t ntp_loop_active; static uint32_t ntp_loop_period; #define NTP_LOOP_PERIOD_INTERVAL (NSEC_PER_SEC) /*1 second interval*/ void ntp_init(void); static void hardupdate(long offset); static void ntp_gettime1(struct ntptimeval *ntvp); static bool ntp_is_time_error(int tsl); static void ntp_loop_update_call(void); static void refresh_ntp_loop(void); static void start_ntp_loop(void); #if DEVELOPMENT || DEBUG uint32_t g_should_log_clock_adjustments = 0; SYSCTL_INT(_kern, OID_AUTO, log_clock_adjustments, CTLFLAG_RW | CTLFLAG_LOCKED, &g_should_log_clock_adjustments, 0, "enable kernel clock adjustment logging"); #endif static bool ntp_is_time_error(int tsl) { if (tsl & (STA_UNSYNC | STA_CLOCKERR)) { return true; } return false; } static void ntp_gettime1(struct ntptimeval *ntvp) { struct timespec atv; NTP_ASSERT_LOCKED(); nanotime(&atv); ntvp->time.tv_sec = atv.tv_sec; ntvp->time.tv_nsec = atv.tv_nsec; if ((unsigned long)atv.tv_sec > last_time_maxerror_update) { time_maxerror += (MAXFREQ / 1000) * (atv.tv_sec - last_time_maxerror_update); last_time_maxerror_update = atv.tv_sec; } ntvp->maxerror = time_maxerror; ntvp->esterror = time_esterror; ntvp->tai = time_tai; ntvp->time_state = time_state; if (ntp_is_time_error(time_status)) { ntvp->time_state = TIME_ERROR; } } int ntp_gettime(struct proc *p, struct ntp_gettime_args *uap, __unused int32_t *retval) { struct ntptimeval ntv; int error; boolean_t enable; NTP_LOCK(enable); ntp_gettime1(&ntv); NTP_UNLOCK(enable); if (IS_64BIT_PROCESS(p)) { struct user64_ntptimeval user_ntv = {}; user_ntv.time.tv_sec = ntv.time.tv_sec; user_ntv.time.tv_nsec = ntv.time.tv_nsec; user_ntv.maxerror = ntv.maxerror; user_ntv.esterror = ntv.esterror; user_ntv.tai = ntv.tai; user_ntv.time_state = ntv.time_state; error = copyout(&user_ntv, uap->ntvp, sizeof(user_ntv)); } else { struct user32_ntptimeval user_ntv = {}; user_ntv.time.tv_sec = (user32_long_t)ntv.time.tv_sec; user_ntv.time.tv_nsec = (user32_long_t)ntv.time.tv_nsec; user_ntv.maxerror = (user32_long_t)ntv.maxerror; user_ntv.esterror = (user32_long_t)ntv.esterror; user_ntv.tai = (user32_long_t)ntv.tai; user_ntv.time_state = ntv.time_state; error = copyout(&user_ntv, uap->ntvp, sizeof(user_ntv)); } if (error) { return error; } return ntv.time_state; } int ntp_adjtime(struct proc *p, struct ntp_adjtime_args *uap, int32_t *retval) { struct timex ntv = {}; long freq; unsigned int modes; int error, ret = 0; clock_sec_t sec; clock_usec_t microsecs; boolean_t enable; if (IS_64BIT_PROCESS(p)) { struct user64_timex user_ntv; error = copyin(uap->tp, &user_ntv, sizeof(user_ntv)); ntv.modes = user_ntv.modes; ntv.offset = (long)user_ntv.offset; ntv.freq = (long)user_ntv.freq; ntv.maxerror = (long)user_ntv.maxerror; ntv.esterror = (long)user_ntv.esterror; ntv.status = user_ntv.status; ntv.constant = (long)user_ntv.constant; ntv.precision = (long)user_ntv.precision; ntv.tolerance = (long)user_ntv.tolerance; } else { struct user32_timex user_ntv; error = copyin(uap->tp, &user_ntv, sizeof(user_ntv)); ntv.modes = user_ntv.modes; ntv.offset = user_ntv.offset; ntv.freq = user_ntv.freq; ntv.maxerror = user_ntv.maxerror; ntv.esterror = user_ntv.esterror; ntv.status = user_ntv.status; ntv.constant = user_ntv.constant; ntv.precision = user_ntv.precision; ntv.tolerance = user_ntv.tolerance; } if (error) { return error; } #if DEVELOPMENT || DEBUG if (g_should_log_clock_adjustments) { os_log(OS_LOG_DEFAULT, "%s: BEFORE modes %u offset %ld freq %ld status %d constant %ld time_adjtime %lld\n", __func__, ntv.modes, ntv.offset, ntv.freq, ntv.status, ntv.constant, time_adjtime); } #endif /* * Update selected clock variables - only the superuser can * change anything. Note that there is no error checking here on * the assumption the superuser should know what it is doing. * Note that either the time constant or TAI offset are loaded * from the ntv.constant member, depending on the mode bits. If * the STA_PLL bit in the status word is cleared, the state and * status words are reset to the initial values at boot. */ modes = ntv.modes; if (modes) { /* Check that this task is entitled to set the time or it is root */ if (!IOCurrentTaskHasEntitlement(SETTIME_ENTITLEMENT)) { #if CONFIG_MACF error = mac_system_check_settime(kauth_cred_get()); if (error) { return error; } #endif if ((error = priv_check_cred(kauth_cred_get(), PRIV_ADJTIME, 0))) { return error; } } } NTP_LOCK(enable); if (modes & MOD_MAXERROR) { clock_gettimeofday(&sec, µsecs); time_maxerror = ntv.maxerror; last_time_maxerror_update = sec; } if (modes & MOD_ESTERROR) { time_esterror = ntv.esterror; } if (modes & MOD_STATUS) { if (time_status & STA_PLL && !(ntv.status & STA_PLL)) { time_state = TIME_OK; time_status = STA_UNSYNC; } time_status &= STA_RONLY; time_status |= ntv.status & ~STA_RONLY; /* * Nor PPS or leaps seconds are supported. * Filter out unsupported bits. */ time_status &= STA_SUPPORTED; } if (modes & MOD_TIMECONST) { if (ntv.constant < 0) { time_constant = 0; } else if (ntv.constant > MAXTC) { time_constant = MAXTC; } else { time_constant = ntv.constant; } } if (modes & MOD_TAI) { if (ntv.constant > 0) { time_tai = ntv.constant; } } if (modes & MOD_NANO) { time_status |= STA_NANO; } if (modes & MOD_MICRO) { time_status &= ~STA_NANO; } if (modes & MOD_CLKB) { time_status |= STA_CLK; } if (modes & MOD_CLKA) { time_status &= ~STA_CLK; } if (modes & MOD_FREQUENCY) { freq = (ntv.freq * 1000LL) >> 16; if (freq > MAXFREQ) { L_LINT(time_freq, MAXFREQ); } else if (freq < -MAXFREQ) { L_LINT(time_freq, -MAXFREQ); } else { /* * ntv.freq is [PPM * 2^16] = [us/s * 2^16] * time_freq is [ns/s * 2^32] */ time_freq = ntv.freq * 1000LL * 65536LL; } } if (modes & MOD_OFFSET) { if (time_status & STA_NANO) { hardupdate(ntv.offset); } else { hardupdate(ntv.offset * 1000); } } ret = ntp_is_time_error(time_status) ? TIME_ERROR : time_state; #if DEVELOPMENT || DEBUG if (g_should_log_clock_adjustments) { os_log(OS_LOG_DEFAULT, "%s: AFTER modes %u offset %lld freq %lld status %d constant %ld time_adjtime %lld\n", __func__, modes, time_offset, time_freq, time_status, time_constant, time_adjtime); } #endif /* * Retrieve all clock variables. Note that the TAI offset is * returned only by ntp_gettime(); */ if (IS_64BIT_PROCESS(p)) { struct user64_timex user_ntv = {}; user_ntv.modes = modes; if (time_status & STA_NANO) { user_ntv.offset = L_GINT(time_offset); } else { user_ntv.offset = L_GINT(time_offset) / 1000; } if (time_freq > 0) { user_ntv.freq = L_GINT(((int64_t)(time_freq / 1000LL)) << 16); } else { user_ntv.freq = -L_GINT(((int64_t)(-(time_freq) / 1000LL)) << 16); } user_ntv.maxerror = time_maxerror; user_ntv.esterror = time_esterror; user_ntv.status = time_status; user_ntv.constant = time_constant; if (time_status & STA_NANO) { user_ntv.precision = time_precision; } else { user_ntv.precision = time_precision / 1000; } user_ntv.tolerance = MAXFREQ * SCALE_PPM; /* unlock before copyout */ NTP_UNLOCK(enable); error = copyout(&user_ntv, uap->tp, sizeof(user_ntv)); } else { struct user32_timex user_ntv = {}; user_ntv.modes = modes; if (time_status & STA_NANO) { user_ntv.offset = L_GINT(time_offset); } else { user_ntv.offset = L_GINT(time_offset) / 1000; } if (time_freq > 0) { user_ntv.freq = L_GINT((time_freq / 1000LL) << 16); } else { user_ntv.freq = -L_GINT((-(time_freq) / 1000LL) << 16); } user_ntv.maxerror = (user32_long_t)time_maxerror; user_ntv.esterror = (user32_long_t)time_esterror; user_ntv.status = time_status; user_ntv.constant = (user32_long_t)time_constant; if (time_status & STA_NANO) { user_ntv.precision = (user32_long_t)time_precision; } else { user_ntv.precision = (user32_long_t)(time_precision / 1000); } user_ntv.tolerance = MAXFREQ * SCALE_PPM; /* unlock before copyout */ NTP_UNLOCK(enable); error = copyout(&user_ntv, uap->tp, sizeof(user_ntv)); } if (modes) { start_ntp_loop(); } if (error == 0) { *retval = ret; } return error; } int64_t ntp_get_freq(void) { return time_freq; } /* * Compute the adjustment to add to the next second. */ void ntp_update_second(int64_t *adjustment, clock_sec_t secs) { int tickrate; l_fp time_adj; l_fp ftemp, old_time_adjtime, old_offset; NTP_ASSERT_LOCKED(); if (secs > last_time_maxerror_update) { time_maxerror += (MAXFREQ / 1000) * (secs - last_time_maxerror_update); last_time_maxerror_update = secs; } old_offset = time_offset; old_time_adjtime = time_adjtime; ftemp = time_offset; L_RSHIFT(ftemp, SHIFT_PLL + time_constant); time_adj = ftemp; L_SUB(time_offset, ftemp); L_ADD(time_adj, time_freq); /* * Apply any correction from adjtime. If more than one second * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM) * until the last second is slewed the final < 500 usecs. */ if (time_adjtime != 0) { if (time_adjtime > 1000000) { tickrate = 5000; } else if (time_adjtime < -1000000) { tickrate = -5000; } else if (time_adjtime > 500) { tickrate = 500; } else if (time_adjtime < -500) { tickrate = -500; } else { tickrate = (int)time_adjtime; } time_adjtime -= tickrate; L_LINT(ftemp, tickrate * 1000); L_ADD(time_adj, ftemp); } if (old_time_adjtime || ((time_offset || old_offset) && (time_offset != old_offset))) { updated = 1; } else { updated = 0; } #if DEVELOPMENT || DEBUG if (g_should_log_clock_adjustments) { int64_t nano = (time_adj > 0)? time_adj >> 32 : -((-time_adj) >> 32); int64_t frac = (time_adj > 0)? ((uint32_t) time_adj) : -((uint32_t) (-time_adj)); os_log(OS_LOG_DEFAULT, "%s:AFTER offset %lld (%lld) freq %lld status %d " "constant %ld time_adjtime %lld nano %lld frac %lld adj %lld\n", __func__, time_offset, (time_offset > 0)? time_offset >> 32 : -((-time_offset) >> 32), time_freq, time_status, time_constant, time_adjtime, nano, frac, time_adj); } #endif *adjustment = time_adj; } /* * hardupdate() - local clock update * * This routine is called by ntp_adjtime() when an offset is provided * to update the local clock phase and frequency. * The implementation is of an adaptive-parameter, hybrid * phase/frequency-lock loop (PLL/FLL). The routine computes new * time and frequency offset estimates for each call. * Presumably, calls to ntp_adjtime() occur only when the caller * believes the local clock is valid within some bound (+-128 ms with * NTP). * * For uncompensated quartz crystal oscillators and nominal update * intervals less than 256 s, operation should be in phase-lock mode, * where the loop is disciplined to phase. For update intervals greater * than 1024 s, operation should be in frequency-lock mode, where the * loop is disciplined to frequency. Between 256 s and 1024 s, the mode * is selected by the STA_MODE status bit. */ static void hardupdate(long offset) { long mtemp = 0; long time_monitor; clock_sec_t time_uptime; l_fp ftemp; NTP_ASSERT_LOCKED(); if (!(time_status & STA_PLL)) { return; } if (offset > MAXPHASE) { time_monitor = MAXPHASE; } else if (offset < -MAXPHASE) { time_monitor = -MAXPHASE; } else { time_monitor = offset; } L_LINT(time_offset, time_monitor); clock_get_calendar_uptime(&time_uptime); if (time_status & STA_FREQHOLD || time_reftime == 0) { time_reftime = time_uptime; } mtemp = time_uptime - time_reftime; L_LINT(ftemp, time_monitor); L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); L_MPY(ftemp, mtemp); L_ADD(time_freq, ftemp); time_status &= ~STA_MODE; if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) { if (time_monitor > 0) { L_LINT(ftemp, (time_monitor << 4) / mtemp); } else { L_LINT(ftemp, -((int64_t)(-(time_monitor)) << 4) / mtemp); } L_RSHIFT(ftemp, SHIFT_FLL + 4); L_ADD(time_freq, ftemp); time_status |= STA_MODE; } time_reftime = time_uptime; if (L_GINT(time_freq) > MAXFREQ) { L_LINT(time_freq, MAXFREQ); } else if (L_GINT(time_freq) < -MAXFREQ) { L_LINT(time_freq, -MAXFREQ); } } static int kern_adjtime(struct timeval *delta) { struct timeval atv; int64_t ltr, ltw; boolean_t enable; if (delta == NULL) { return EINVAL; } ltw = (int64_t)delta->tv_sec * (int64_t)USEC_PER_SEC + delta->tv_usec; NTP_LOCK(enable); ltr = time_adjtime; time_adjtime = ltw; #if DEVELOPMENT || DEBUG if (g_should_log_clock_adjustments) { os_log(OS_LOG_DEFAULT, "%s:AFTER offset %lld freq %lld status %d constant %ld time_adjtime %lld\n", __func__, time_offset, time_freq, time_status, time_constant, time_adjtime); } #endif NTP_UNLOCK(enable); atv.tv_sec = (__darwin_time_t)(ltr / (int64_t)USEC_PER_SEC); atv.tv_usec = ltr % (int64_t)USEC_PER_SEC; if (atv.tv_usec < 0) { atv.tv_usec += (suseconds_t)USEC_PER_SEC; atv.tv_sec--; } *delta = atv; start_ntp_loop(); return 0; } int adjtime(struct proc *p, struct adjtime_args *uap, __unused int32_t *retval) { struct timeval atv; int error; /* Check that this task is entitled to set the time or it is root */ if (!IOCurrentTaskHasEntitlement(SETTIME_ENTITLEMENT)) { #if CONFIG_MACF error = mac_system_check_settime(kauth_cred_get()); if (error) { return error; } #endif if ((error = priv_check_cred(kauth_cred_get(), PRIV_ADJTIME, 0))) { return error; } } if (IS_64BIT_PROCESS(p)) { struct user64_timeval user_atv; error = copyin(uap->delta, &user_atv, sizeof(user_atv)); atv.tv_sec = (__darwin_time_t)user_atv.tv_sec; atv.tv_usec = user_atv.tv_usec; } else { struct user32_timeval user_atv; error = copyin(uap->delta, &user_atv, sizeof(user_atv)); atv.tv_sec = user_atv.tv_sec; atv.tv_usec = user_atv.tv_usec; } if (error) { return error; } kern_adjtime(&atv); if (uap->olddelta) { if (IS_64BIT_PROCESS(p)) { struct user64_timeval user_atv = {}; user_atv.tv_sec = atv.tv_sec; user_atv.tv_usec = atv.tv_usec; error = copyout(&user_atv, uap->olddelta, sizeof(user_atv)); } else { struct user32_timeval user_atv = {}; user_atv.tv_sec = (user32_time_t)atv.tv_sec; user_atv.tv_usec = atv.tv_usec; error = copyout(&user_atv, uap->olddelta, sizeof(user_atv)); } } return error; } static void ntp_loop_update_call(void) { boolean_t enable; NTP_LOCK(enable); /* * Update the scale factor used by clock_calend. * NOTE: clock_update_calendar will call ntp_update_second to compute the next adjustment. */ clock_update_calendar(); refresh_ntp_loop(); NTP_UNLOCK(enable); } static void refresh_ntp_loop(void) { NTP_ASSERT_LOCKED(); if (--ntp_loop_active == 0) { /* * Activate the timer only if the next second adjustment might change. * ntp_update_second checks it and sets updated accordingly. */ if (updated) { clock_deadline_for_periodic_event(ntp_loop_period, mach_absolute_time(), &ntp_loop_deadline); if (!timer_call_enter(&ntp_loop_update, ntp_loop_deadline, TIMER_CALL_SYS_CRITICAL)) { ntp_loop_active++; } } } } /* * This function triggers a timer that each second will calculate the adjustment to * provide to clock_calendar to scale the time (used by gettimeofday-family syscalls). * The periodic timer will stop when the adjustment will reach a stable value. */ static void start_ntp_loop(void) { boolean_t enable; NTP_LOCK(enable); ntp_loop_deadline = mach_absolute_time() + ntp_loop_period; if (!timer_call_enter(&ntp_loop_update, ntp_loop_deadline, TIMER_CALL_SYS_CRITICAL)) { ntp_loop_active++; } NTP_UNLOCK(enable); } static void init_ntp_loop(void) { uint64_t abstime; ntp_loop_active = 0; nanoseconds_to_absolutetime(NTP_LOOP_PERIOD_INTERVAL, &abstime); ntp_loop_period = (uint32_t)abstime; timer_call_setup(&ntp_loop_update, (timer_call_func_t)ntp_loop_update_call, NULL); } void ntp_init(void) { init_ntp_loop(); }