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/*-************************************************************************ ** 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 <phk@FreeBSD.org>.** 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.*/#include <sys/cdefs.h>__FBSDID("$FreeBSD: src/sys/kern/kern_ntptime.c,v 1.59 2005/05/28 14:34:41 rwatson Exp $");#include "opt_ntp.h"#include <sys/param.h>#include <sys/systm.h>#include <sys/sysproto.h>#include <sys/jail.h>#include <sys/kernel.h>#include <sys/proc.h>#include <sys/lock.h>#include <sys/mutex.h>#include <sys/time.h>#include <sys/timex.h>#include <sys/timetc.h>#include <sys/timepps.h>#include <sys/syscallsubr.h>#include <sys/sysctl.h>/** Single-precision macros for 64-bit machines*/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) ((v) = (int64_t)(a) << 32)#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 system 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.** Note that all routines must run at priority splclock or higher.*//** 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 |* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+*//** The following variables establish the state of the PLL/FLL and the* residual time and frequency offset of the local clock.*/#define SHIFT_PLL 4 /* PLL loop gain (shift) */#define SHIFT_FLL 2 /* FLL loop gain (shift) */static int time_state = TIME_OK; /* clock state */static int time_status = STA_UNSYNC; /* clock status bits */static long time_tai; /* TAI offset (s) */static long time_monitor; /* last time offset scaled (ns) */static long time_constant; /* poll interval (shift) (s) */static long time_precision = 1; /* clock precision (ns) */static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */static long time_reftime; /* time at last adjustment (s) */static l_fp time_offset; /* time offset (ns) */static l_fp time_freq; /* frequency offset (ns/s) */static l_fp time_adj; /* tick adjust (ns/s) */static int64_t time_adjtime; /* correction from adjtime(2) (usec) */#ifdef PPS_SYNC/** The following variables are used when a pulse-per-second (PPS) signal* is available and connected via a modem control lead. They establish* the engineering parameters of the clock discipline loop when* controlled by the PPS signal.*/#define PPS_FAVG 2 /* min freq avg interval (s) (shift) */#define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */#define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */#define PPS_PAVG 4 /* phase avg interval (s) (shift) */#define PPS_VALID 120 /* PPS signal watchdog max (s) */#define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */#define PPS_POPCORN 2 /* popcorn spike threshold (shift) */static struct timespec pps_tf[3]; /* phase median filter */static l_fp pps_freq; /* scaled frequency offset (ns/s) */static long pps_fcount; /* frequency accumulator */static long pps_jitter; /* nominal jitter (ns) */static long pps_stabil; /* nominal stability (scaled ns/s) */static long pps_lastsec; /* time at last calibration (s) */static int pps_valid; /* signal watchdog counter */static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */static int pps_intcnt; /* wander counter *//** PPS signal quality monitors*/static long pps_calcnt; /* calibration intervals */static long pps_jitcnt; /* jitter limit exceeded */static long pps_stbcnt; /* stability limit exceeded */static long pps_errcnt; /* calibration errors */#endif /* PPS_SYNC *//** End of phase/frequency-lock loop (PLL/FLL) definitions*/static void ntp_init(void);static void hardupdate(long offset);static void ntp_gettime1(struct ntptimeval *ntvp);static int cf_useradjtime;static int cf_jailadjtime;SYSCTL_INT(_kern, OID_AUTO, useradjtime, CTLFLAG_RW, &cf_useradjtime, 0,"Non-root is allowed to adjust system time");SYSCTL_INT(_kern, OID_AUTO, jailadjtime, CTLFLAG_RW, &cf_jailadjtime, 0,"System time is allowed to be adjusted from jail");static voidntp_gettime1(struct ntptimeval *ntvp){struct timespec atv; /* nanosecond time */GIANT_REQUIRED;nanotime(&atv);ntvp->time.tv_sec = atv.tv_sec;ntvp->time.tv_nsec = atv.tv_nsec;ntvp->maxerror = time_maxerror;ntvp->esterror = time_esterror;ntvp->tai = time_tai;ntvp->time_state = time_state;/** Status word error decode. If any of these conditions occur,* an error is returned, instead of the status word. Most* applications will care only about the fact the system clock* may not be trusted, not about the details.** Hardware or software error*/if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||/** PPS signal lost when either time or frequency synchronization* requested*/(time_status & (STA_PPSFREQ | STA_PPSTIME) &&!(time_status & STA_PPSSIGNAL)) ||/** PPS jitter exceeded when time synchronization requested*/(time_status & STA_PPSTIME &&time_status & STA_PPSJITTER) ||/** PPS wander exceeded or calibration error when frequency* synchronization requested*/(time_status & STA_PPSFREQ &&time_status & (STA_PPSWANDER | STA_PPSERROR)))ntvp->time_state = TIME_ERROR;}/** ntp_gettime() - NTP user application interface** See the timex.h header file for synopsis and API description. Note* that the TAI offset is returned in the ntvtimeval.tai structure* member.*/#ifndef _SYS_SYSPROTO_H_struct ntp_gettime_args {struct ntptimeval *ntvp;};#endif/* ARGSUSED */intntp_gettime(struct thread *td, struct ntp_gettime_args *uap){struct ntptimeval ntv;mtx_lock(&Giant);ntp_gettime1(&ntv);mtx_unlock(&Giant);return (copyout(&ntv, uap->ntvp, sizeof(ntv)));}static intntp_sysctl(SYSCTL_HANDLER_ARGS){struct ntptimeval ntv; /* temporary structure */ntp_gettime1(&ntv);return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req));}SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, "");SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD,0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", "");#ifdef PPS_SYNCSYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, &pps_shiftmax, 0, "");SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, &pps_shift, 0, "");SYSCTL_INT(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, &time_monitor, 0, "");SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD, &pps_freq, sizeof(pps_freq), "I", "");SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD, &time_freq, sizeof(time_freq), "I", "");#endif/** ntp_adjtime() - NTP daemon application interface** See the timex.h header file for synopsis and API description. Note* that the timex.constant structure member has a dual purpose to set* the time constant and to set the TAI offset.*/#ifndef _SYS_SYSPROTO_H_struct ntp_adjtime_args {struct timex *tp;};#endif/** MPSAFE*/intntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap){struct timex ntv; /* temporary structure */long freq; /* frequency ns/s) */int modes; /* mode bits from structure */int s; /* caller priority */int error;error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv));if (error)return(error);/** 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.*/mtx_lock(&Giant);modes = ntv.modes;if (modes) { /* XXX really check suser sometimes only? */#ifdef MACerror = mac_check_system_settime(td->td_ucred);if (error)goto done2;#endifif (!cf_jailadjtime && jailed(td->td_ucred)) {error = EPERM;goto done2;}if (!cf_useradjtime &&(error = suser_cred(td->td_ucred, SUSER_ALLOWJAIL)) != 0)goto done2; /* jail is already checked at this point */}s = splclock();if (modes & MOD_MAXERROR)time_maxerror = ntv.maxerror;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;#ifdef PPS_SYNCpps_shift = PPS_FAVG;#endif /* PPS_SYNC */}time_status &= STA_RONLY;time_status |= ntv.status & ~STA_RONLY;}if (modes & MOD_TIMECONST) {if (ntv.constant < 0)time_constant = 0;else if (ntv.constant > MAXTC)time_constant = MAXTC;elsetime_constant = ntv.constant;}if (modes & MOD_TAI) {if (ntv.constant > 0) /* XXX zero & negative numbers ? */time_tai = ntv.constant;}#ifdef PPS_SYNCif (modes & MOD_PPSMAX) {if (ntv.shift < PPS_FAVG)pps_shiftmax = PPS_FAVG;else if (ntv.shift > PPS_FAVGMAX)pps_shiftmax = PPS_FAVGMAX;elsepps_shiftmax = ntv.shift;}#endif /* PPS_SYNC */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;}#ifdef PPS_SYNCpps_freq = time_freq;#endif /* PPS_SYNC */}if (modes & MOD_OFFSET) {if (time_status & STA_NANO)hardupdate(ntv.offset);elsehardupdate(ntv.offset * 1000);}/** Retrieve all clock variables. Note that the TAI offset is* returned only by ntp_gettime();*/if (time_status & STA_NANO)ntv.offset = L_GINT(time_offset);elsentv.offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */ntv.freq = L_GINT((time_freq / 1000LL) << 16);ntv.maxerror = time_maxerror;ntv.esterror = time_esterror;ntv.status = time_status;ntv.constant = time_constant;if (time_status & STA_NANO)ntv.precision = time_precision;elsentv.precision = time_precision / 1000;ntv.tolerance = MAXFREQ * SCALE_PPM;#ifdef PPS_SYNCntv.shift = pps_shift;ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16);if (time_status & STA_NANO)ntv.jitter = pps_jitter;elsentv.jitter = pps_jitter / 1000;ntv.stabil = pps_stabil;ntv.calcnt = pps_calcnt;ntv.errcnt = pps_errcnt;ntv.jitcnt = pps_jitcnt;ntv.stbcnt = pps_stbcnt;#endif /* PPS_SYNC */splx(s);error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv));if (error)goto done2;/** Status word error decode. See comments in* ntp_gettime() routine.*/if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||(time_status & (STA_PPSFREQ | STA_PPSTIME) &&!(time_status & STA_PPSSIGNAL)) ||(time_status & STA_PPSTIME &&time_status & STA_PPSJITTER) ||(time_status & STA_PPSFREQ &&time_status & (STA_PPSWANDER | STA_PPSERROR))) {td->td_retval[0] = TIME_ERROR;} else {td->td_retval[0] = time_state;}done2:mtx_unlock(&Giant);return (error);}/** second_overflow() - called after ntp_tick_adjust()** This routine is ordinarily called immediately following the above* routine ntp_tick_adjust(). While these two routines are normally* combined, they are separated here only for the purposes of* simulation.*/voidntp_update_second(int64_t *adjustment, time_t *newsec){int tickrate;l_fp ftemp; /* 32/64-bit temporary *//** On rollover of the second both the nanosecond and microsecond* clocks are updated and the state machine cranked as* necessary. The phase adjustment to be used for the next* second is calculated and the maximum error is increased by* the tolerance.*/time_maxerror += MAXFREQ / 1000;/** Leap second processing. If in leap-insert state at* the end of the day, the system clock is set back one* second; if in leap-delete state, the system clock is* set ahead one second. The nano_time() routine or* external clock driver will insure that reported time* is always monotonic.*/switch (time_state) {/** No warning.*/case TIME_OK:if (time_status & STA_INS)time_state = TIME_INS;else if (time_status & STA_DEL)time_state = TIME_DEL;break;/** Insert second 23:59:60 following second* 23:59:59.*/case TIME_INS:if (!(time_status & STA_INS))time_state = TIME_OK;else if ((*newsec) % 86400 == 0) {(*newsec)--;time_state = TIME_OOP;time_tai++;}break;/** Delete second 23:59:59.*/case TIME_DEL:if (!(time_status & STA_DEL))time_state = TIME_OK;else if (((*newsec) + 1) % 86400 == 0) {(*newsec)++;time_tai--;time_state = TIME_WAIT;}break;/** Insert second in progress.*/case TIME_OOP:time_state = TIME_WAIT;break;/** Wait for status bits to clear.*/case TIME_WAIT:if (!(time_status & (STA_INS | STA_DEL)))time_state = TIME_OK;}/** Compute the total time adjustment for the next second* in ns. The offset is reduced by a factor depending on* whether the PPS signal is operating. Note that the* value is in effect scaled by the clock frequency,* since the adjustment is added at each tick interrupt.*/ftemp = time_offset;#ifdef PPS_SYNC/* XXX even if PPS signal dies we should finish adjustment ? */if (time_status & STA_PPSTIME && time_status &STA_PPSSIGNAL)L_RSHIFT(ftemp, pps_shift);elseL_RSHIFT(ftemp, SHIFT_PLL + time_constant);#elseL_RSHIFT(ftemp, SHIFT_PLL + time_constant);#endif /* PPS_SYNC */time_adj = ftemp;L_SUB(time_offset, ftemp);L_ADD(time_adj, time_freq);/** Apply any correction from adjtime(2). 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;elsetickrate = time_adjtime;time_adjtime -= tickrate;L_LINT(ftemp, tickrate * 1000);L_ADD(time_adj, ftemp);}*adjustment = time_adj;#ifdef PPS_SYNCif (pps_valid > 0)pps_valid--;elsetime_status &= ~STA_PPSSIGNAL;#endif /* PPS_SYNC */}/** ntp_init() - initialize variables and structures** This routine must be called after the kernel variables hz and tick* are set or changed and before the next tick interrupt. In this* particular implementation, these values are assumed set elsewhere in* the kernel. The design allows the clock frequency and tick interval* to be changed while the system is running. So, this routine should* probably be integrated with the code that does that.*/static voidntp_init(){/** The following variables are initialized only at startup. Only* those structures not cleared by the compiler need to be* initialized, and these only in the simulator. In the actual* kernel, any nonzero values here will quickly evaporate.*/L_CLR(time_offset);L_CLR(time_freq);#ifdef PPS_SYNCpps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;pps_fcount = 0;L_CLR(pps_freq);#endif /* PPS_SYNC */}SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL)/** hardupdate() - local clock update** This routine is called by ntp_adjtime() 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. If the kernel PPS* discipline code is configured (PPS_SYNC), the PPS signal itself* determines the new time offset, instead of the calling argument.* Presumably, calls to ntp_adjtime() occur only when the caller* believes the local clock is valid within some bound (+-128 ms with* NTP). If the caller's time is far different than the PPS time, an* argument will ensue, and it's not clear who will lose.** 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 voidhardupdate(offset)long offset; /* clock offset (ns) */{long mtemp;l_fp ftemp;/** Select how the phase is to be controlled and from which* source. If the PPS signal is present and enabled to* discipline the time, the PPS offset is used; otherwise, the* argument offset is used.*/if (!(time_status & STA_PLL))return;if (!(time_status & STA_PPSTIME && time_status &STA_PPSSIGNAL)) {if (offset > MAXPHASE)time_monitor = MAXPHASE;else if (offset < -MAXPHASE)time_monitor = -MAXPHASE;elsetime_monitor = offset;L_LINT(time_offset, time_monitor);}/** Select how the frequency is to be controlled and in which* mode (PLL or FLL). If the PPS signal is present and enabled* to discipline the frequency, the PPS frequency is used;* otherwise, the argument offset is used to compute it.*/if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {time_reftime = time_second;return;}if (time_status & STA_FREQHOLD || time_reftime == 0)time_reftime = time_second;mtemp = time_second - 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)) {L_LINT(ftemp, (time_monitor << 4) / mtemp);L_RSHIFT(ftemp, SHIFT_FLL + 4);L_ADD(time_freq, ftemp);time_status |= STA_MODE;}time_reftime = time_second;if (L_GINT(time_freq) > MAXFREQ)L_LINT(time_freq, MAXFREQ);else if (L_GINT(time_freq) < -MAXFREQ)L_LINT(time_freq, -MAXFREQ);}#ifdef PPS_SYNC/** hardpps() - discipline CPU clock oscillator to external PPS signal** This routine is called at each PPS interrupt in order to discipline* the CPU clock oscillator to the PPS signal. There are two independent* first-order feedback loops, one for the phase, the other for the* frequency. The phase loop measures and grooms the PPS phase offset* and leaves it in a handy spot for the seconds overflow routine. The* frequency loop averages successive PPS phase differences and* calculates the PPS frequency offset, which is also processed by the* seconds overflow routine. The code requires the caller to capture the* time and architecture-dependent hardware counter values in* nanoseconds at the on-time PPS signal transition.** Note that, on some Unix systems this routine runs at an interrupt* priority level higher than the timer interrupt routine hardclock().* Therefore, the variables used are distinct from the hardclock()* variables, except for the actual time and frequency variables, which* are determined by this routine and updated atomically.*/voidhardpps(tsp, nsec)struct timespec *tsp; /* time at PPS */long nsec; /* hardware counter at PPS */{long u_sec, u_nsec, v_nsec; /* temps */l_fp ftemp;/** The signal is first processed by a range gate and frequency* discriminator. The range gate rejects noise spikes outside* the range +-500 us. The frequency discriminator rejects input* signals with apparent frequency outside the range 1 +-500* PPM. If two hits occur in the same second, we ignore the* later hit; if not and a hit occurs outside the range gate,* keep the later hit for later comparison, but do not process* it.*/time_status |= STA_PPSSIGNAL | STA_PPSJITTER;time_status &= ~(STA_PPSWANDER | STA_PPSERROR);pps_valid = PPS_VALID;u_sec = tsp->tv_sec;u_nsec = tsp->tv_nsec;if (u_nsec >= (NANOSECOND >> 1)) {u_nsec -= NANOSECOND;u_sec++;}v_nsec = u_nsec - pps_tf[0].tv_nsec;if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND -MAXFREQ)return;pps_tf[2] = pps_tf[1];pps_tf[1] = pps_tf[0];pps_tf[0].tv_sec = u_sec;pps_tf[0].tv_nsec = u_nsec;/** Compute the difference between the current and previous* counter values. If the difference exceeds 0.5 s, assume it* has wrapped around, so correct 1.0 s. If the result exceeds* the tick interval, the sample point has crossed a tick* boundary during the last second, so correct the tick. Very* intricate.*/u_nsec = nsec;if (u_nsec > (NANOSECOND >> 1))u_nsec -= NANOSECOND;else if (u_nsec < -(NANOSECOND >> 1))u_nsec += NANOSECOND;pps_fcount += u_nsec;if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)return;time_status &= ~STA_PPSJITTER;/** A three-stage median filter is used to help denoise the PPS* time. The median sample becomes the time offset estimate; the* difference between the other two samples becomes the time* dispersion (jitter) estimate.*/if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;} else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;} else {v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;}} else {if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;} else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;} else {v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;}}/** Nominal jitter is due to PPS signal noise and interrupt* latency. If it exceeds the popcorn threshold, the sample is* discarded. otherwise, if so enabled, the time offset is* updated. We can tolerate a modest loss of data here without* much degrading time accuracy.*/if (u_nsec > (pps_jitter << PPS_POPCORN)) {time_status |= STA_PPSJITTER;pps_jitcnt++;} else if (time_status & STA_PPSTIME) {time_monitor = -v_nsec;L_LINT(time_offset, time_monitor);}pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;u_sec = pps_tf[0].tv_sec - pps_lastsec;if (u_sec < (1 << pps_shift))return;/** At the end of the calibration interval the difference between* the first and last counter values becomes the scaled* frequency. It will later be divided by the length of the* interval to determine the frequency update. If the frequency* exceeds a sanity threshold, or if the actual calibration* interval is not equal to the expected length, the data are* discarded. We can tolerate a modest loss of data here without* much degrading frequency accuracy.*/pps_calcnt++;v_nsec = -pps_fcount;pps_lastsec = pps_tf[0].tv_sec;pps_fcount = 0;u_nsec = MAXFREQ << pps_shift;if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 <<pps_shift)) {time_status |= STA_PPSERROR;pps_errcnt++;return;}/** Here the raw frequency offset and wander (stability) is* calculated. If the wander is less than the wander threshold* for four consecutive averaging intervals, the interval is* doubled; if it is greater than the threshold for four* consecutive intervals, the interval is halved. The scaled* frequency offset is converted to frequency offset. The* stability metric is calculated as the average of recent* frequency changes, but is used only for performance* monitoring.*/L_LINT(ftemp, v_nsec);L_RSHIFT(ftemp, pps_shift);L_SUB(ftemp, pps_freq);u_nsec = L_GINT(ftemp);if (u_nsec > PPS_MAXWANDER) {L_LINT(ftemp, PPS_MAXWANDER);pps_intcnt--;time_status |= STA_PPSWANDER;pps_stbcnt++;} else if (u_nsec < -PPS_MAXWANDER) {L_LINT(ftemp, -PPS_MAXWANDER);pps_intcnt--;time_status |= STA_PPSWANDER;pps_stbcnt++;} else {pps_intcnt++;}if (pps_intcnt >= 4) {pps_intcnt = 4;if (pps_shift < pps_shiftmax) {pps_shift++;pps_intcnt = 0;}} else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {pps_intcnt = -4;if (pps_shift > PPS_FAVG) {pps_shift--;pps_intcnt = 0;}}if (u_nsec < 0)u_nsec = -u_nsec;pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;/** The PPS frequency is recalculated and clamped to the maximum* MAXFREQ. If enabled, the system clock frequency is updated as* well.*/L_ADD(pps_freq, ftemp);u_nsec = L_GINT(pps_freq);if (u_nsec > MAXFREQ)L_LINT(pps_freq, MAXFREQ);else if (u_nsec < -MAXFREQ)L_LINT(pps_freq, -MAXFREQ);if (time_status & STA_PPSFREQ)time_freq = pps_freq;}#endif /* PPS_SYNC */#ifndef _SYS_SYSPROTO_H_struct adjtime_args {struct timeval *delta;struct timeval *olddelta;};#endif/** MPSAFE*//* ARGSUSED */intadjtime(struct thread *td, struct adjtime_args *uap){struct timeval delta, olddelta, *deltap;int error;if (uap->delta) {error = copyin(uap->delta, &delta, sizeof(delta));if (error)return (error);deltap = δ} elsedeltap = NULL;error = kern_adjtime(td, deltap, &olddelta);if (uap->olddelta && error == 0)error = copyout(&olddelta, uap->olddelta, sizeof(olddelta));return (error);}intkern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta){struct timeval atv;int error = 0;#ifdef MACerror = mac_check_system_settime(td->td_ucred);if (error)return (error);#endifif (!cf_jailadjtime && jailed(td->td_ucred))return (EPERM);if (!cf_useradjtime && (error = suser_cred(td->td_ucred, SUSER_ALLOWJAIL)) != 0)return (error); /* jail is already checked */mtx_lock(&Giant);if (olddelta) {atv.tv_sec = time_adjtime / 1000000;atv.tv_usec = time_adjtime % 1000000;if (atv.tv_usec < 0) {atv.tv_usec += 1000000;atv.tv_sec--;}*olddelta = atv;}if (delta)time_adjtime = (int64_t)delta->tv_sec * 1000000 +delta->tv_usec;mtx_unlock(&Giant);return (error);}