/* * ntp_loopfilter.c - implements the NTP loop filter algorithm * * ATTENTION: Get approval from Dave Mills on all changes to this file! * */ #ifdef HAVE_CONFIG_H # include <config.h> #endif #include "ntpd.h" #include "ntp_io.h" #include "ntp_unixtime.h" #include "ntp_stdlib.h" #include <stdio.h> #include <ctype.h> #include <signal.h> #include <setjmp.h> #if defined(VMS) && defined(VMS_LOCALUNIT) /*wjm*/ #include "ntp_refclock.h" #endif /* VMS */ #ifdef KERNEL_PLL #include "ntp_syscall.h" #endif /* KERNEL_PLL */ /* * This is an implementation of the clock discipline algorithm described * in UDel TR 97-4-3, as amended. It operates as an adaptive parameter, * hybrid phase/frequency-lock loop. A number of sanity checks are * included to protect against timewarps, timespikes and general mayhem. * All units are in s and s/s, unless noted otherwise. */ #define CLOCK_MAX .128 /* default step threshold (s) */ #define CLOCK_MINSTEP 900. /* default stepout threshold (s) */ #define CLOCK_PANIC 1000. /* default panic threshold (s) */ #define CLOCK_PHI 15e-6 /* max frequency error (s/s) */ #define CLOCK_PLL 16. /* PLL loop gain (log2) */ #define CLOCK_AVG 8. /* parameter averaging constant */ #define CLOCK_FLL (NTP_MAXPOLL + CLOCK_AVG) /* FLL loop gain */ #define CLOCK_ALLAN 1500. /* compromise Allan intercept (s) */ #define CLOCK_DAY 86400. /* one day in seconds (s) */ #define CLOCK_JUNE (CLOCK_DAY * 30) /* June in seconds (s) */ #define CLOCK_LIMIT 30 /* poll-adjust threshold */ #define CLOCK_PGATE 4. /* poll-adjust gate */ #define PPS_MAXAGE 120 /* kernel pps signal timeout (s) */ /* * Clock discipline state machine. This is used to control the * synchronization behavior during initialization and following a * timewarp. * * State < step > step Comments * ==================================================== * NSET FREQ step, FREQ no ntp.drift * * FSET SYNC step, SYNC ntp.drift * * FREQ if (mu < 900) if (mu < 900) set freq * ignore ignore * else else * freq, SYNC freq, step, SYNC * * SYNC SYNC if (mu < 900) adjust phase/freq * ignore * else * SPIK * * SPIK SYNC step, SYNC set phase */ #define S_NSET 0 /* clock never set */ #define S_FSET 1 /* frequency set from the drift file */ #define S_SPIK 2 /* spike detected */ #define S_FREQ 3 /* frequency mode */ #define S_SYNC 4 /* clock synchronized */ /* * Kernel PLL/PPS state machine. This is used with the kernel PLL * modifications described in the README.kernel file. * * If kernel support for the ntp_adjtime() system call is available, the * ntp_control flag is set. The ntp_enable and kern_enable flags can be * set at configuration time or run time using ntpdc. If ntp_enable is * false, the discipline loop is unlocked and no corrections of any kind * are made. If both ntp_control and kern_enable are set, the kernel * support is used as described above; if false, the kernel is bypassed * entirely and the daemon discipline used instead. * * There have been three versions of the kernel discipline code. The * first (microkernel) now in Solaris discipilnes the microseconds. The * second and third (nanokernel) disciplines the clock in nanoseconds. * These versions are identifed if the symbol STA_PLL is present in the * header file /usr/include/sys/timex.h. The third and current version * includes TAI offset and is identified by the symbol NTP_API with * value 4. * * Each update to a prefer peer sets pps_stratum if it survives the * intersection algorithm and its time is within range. The PPS time * discipline is enabled (STA_PPSTIME bit set in the status word) when * pps_stratum is true and the PPS frequency discipline is enabled. If * the PPS time discipline is enabled and the kernel reports a PPS * signal is present, the pps_control variable is set to the current * time. If the current time is later than pps_control by PPS_MAXAGE * (120 s), this variable is set to zero. * * If an external clock is present, the clock driver sets STA_CLK in the * status word. When the local clock driver sees this bit, it updates * via this routine, which then calls ntp_adjtime() with the STA_PLL bit * set to zero, in which case the system clock is not adjusted. This is * also a signal for the external clock driver to discipline the system * clock. */ /* * Program variables that can be tinkered. */ double clock_max = CLOCK_MAX; /* step threshold (s) */ double clock_minstep = CLOCK_MINSTEP; /* stepout threshold (s) */ double clock_panic = CLOCK_PANIC; /* panic threshold (s) */ double clock_phi = CLOCK_PHI; /* dispersion rate (s/s) */ double allan_xpt = CLOCK_ALLAN; /* Allan intercept (s) */ /* * Program variables */ static double clock_offset; /* offset (s) */ double clock_jitter; /* offset jitter (s) */ double drift_comp; /* frequency (s/s) */ double clock_stability; /* frequency stability (wander) (s/s) */ u_long sys_clocktime; /* last system clock update */ u_long pps_control; /* last pps update */ u_long sys_tai; /* UTC offset from TAI (s) */ static void rstclock P((int, u_long, double)); /* transition function */ #ifdef KERNEL_PLL struct timex ntv; /* kernel API parameters */ int pll_status; /* status bits for kernel pll */ #endif /* KERNEL_PLL */ /* * Clock state machine control flags */ int ntp_enable; /* clock discipline enabled */ int pll_control; /* kernel support available */ int kern_enable; /* kernel support enabled */ int pps_enable; /* kernel PPS discipline enabled */ int ext_enable; /* external clock enabled */ int pps_stratum; /* pps stratum */ int allow_panic = FALSE; /* allow panic correction */ int mode_ntpdate = FALSE; /* exit on first clock set */ /* * Clock state machine variables */ int state; /* clock discipline state */ u_char sys_poll = NTP_MINDPOLL; /* time constant/poll (log2 s) */ int tc_counter; /* jiggle counter */ double last_offset; /* last offset (s) */ double last_base; /* last base offset (s) */ /* * Huff-n'-puff filter variables */ static double *sys_huffpuff; /* huff-n'-puff filter */ static int sys_hufflen; /* huff-n'-puff filter stages */ static int sys_huffptr; /* huff-n'-puff filter pointer */ static double sys_mindly; /* huff-n'-puff filter min delay */ #if defined(KERNEL_PLL) /* Emacs cc-mode goes nuts if we split the next line... */ #define MOD_BITS (MOD_OFFSET | MOD_MAXERROR | MOD_ESTERROR | \ MOD_STATUS | MOD_TIMECONST) #ifdef SIGSYS static void pll_trap P((int)); /* configuration trap */ static struct sigaction sigsys; /* current sigaction status */ static struct sigaction newsigsys; /* new sigaction status */ static sigjmp_buf env; /* environment var. for pll_trap() */ #endif /* SIGSYS */ #endif /* KERNEL_PLL */ /* * init_loopfilter - initialize loop filter data */ void init_loopfilter(void) { /* * Initialize state variables. Initially, we expect no drift * file, so set the state to S_NSET. If a drift file is present, * it will be detected later and the state set to S_FSET. */ rstclock(S_NSET, 0, 0); clock_jitter = LOGTOD(sys_precision); } /* * local_clock - the NTP logical clock loop filter. * * Return codes: * -1 update ignored: exceeds panic threshold * 0 update ignored: popcorn or exceeds step threshold * 1 clock was slewed * 2 clock was stepped * * LOCKCLOCK: The only thing this routine does is set the * sys_rootdispersion variable equal to the peer dispersion. */ int local_clock( struct peer *peer, /* synch source peer structure */ double fp_offset /* clock offset (s) */ ) { int rval; /* return code */ u_long mu; /* interval since last update (s) */ double flladj; /* FLL frequency adjustment (ppm) */ double plladj; /* PLL frequency adjustment (ppm) */ double clock_frequency; /* clock frequency adjustment (ppm) */ double dtemp, etemp; /* double temps */ #ifdef OPENSSL u_int32 *tpt; int i; u_int len; long togo; #endif /* OPENSSL */ /* * If the loop is opened or the NIST LOCKCLOCK is in use, * monitor and record the offsets anyway in order to determine * the open-loop response and then go home. */ #ifdef DEBUG if (debug) printf( "local_clock: assocID %d offset %.9f freq %.3f state %d\n", peer->associd, fp_offset, drift_comp * 1e6, state); #endif #ifdef LOCKCLOCK return (0); #else /* LOCKCLOCK */ if (!ntp_enable) { record_loop_stats(fp_offset, drift_comp, clock_jitter, clock_stability, sys_poll); return (0); } /* * If the clock is way off, panic is declared. The clock_panic * defaults to 1000 s; if set to zero, the panic will never * occur. The allow_panic defaults to FALSE, so the first panic * will exit. It can be set TRUE by a command line option, in * which case the clock will be set anyway and time marches on. * But, allow_panic will be set FALSE when the update is less * than the step threshold; so, subsequent panics will exit. */ if (fabs(fp_offset) > clock_panic && clock_panic > 0 && !allow_panic) { msyslog(LOG_ERR, "time correction of %.0f seconds exceeds sanity limit (%.0f); set clock manually to the correct UTC time.", fp_offset, clock_panic); return (-1); } /* * If simulating ntpdate, set the clock directly, rather than * using the discipline. The clock_max defines the step * threshold, above which the clock will be stepped instead of * slewed. The value defaults to 128 ms, but can be set to even * unreasonable values. If set to zero, the clock will never be * stepped. Note that a slew will persist beyond the life of * this program. * * Note that if ntpdate is active, the terminal does not detach, * so the termination comments print directly to the console. */ if (mode_ntpdate) { if (fabs(fp_offset) > clock_max && clock_max > 0) { step_systime(fp_offset); msyslog(LOG_NOTICE, "time reset %+.6f s", fp_offset); printf("ntpd: time set %+.6fs\n", fp_offset); } else { adj_systime(fp_offset); msyslog(LOG_NOTICE, "time slew %+.6f s", fp_offset); printf("ntpd: time slew %+.6fs\n", fp_offset); } record_loop_stats(fp_offset, drift_comp, clock_jitter, clock_stability, sys_poll); exit (0); } /* * The huff-n'-puff filter finds the lowest delay in the recent * interval. This is used to correct the offset by one-half the * difference between the sample delay and minimum delay. This * is most effective if the delays are highly assymetric and * clockhopping is avoided and the clock frequency wander is * relatively small. * * Note either there is no prefer peer or this update is from * the prefer peer. */ if (sys_huffpuff != NULL && (sys_prefer == NULL || sys_prefer == peer)) { if (peer->delay < sys_huffpuff[sys_huffptr]) sys_huffpuff[sys_huffptr] = peer->delay; if (peer->delay < sys_mindly) sys_mindly = peer->delay; if (fp_offset > 0) dtemp = -(peer->delay - sys_mindly) / 2; else dtemp = (peer->delay - sys_mindly) / 2; fp_offset += dtemp; #ifdef DEBUG if (debug) printf( "local_clock: size %d mindly %.6f huffpuff %.6f\n", sys_hufflen, sys_mindly, dtemp); #endif } /* * Clock state machine transition function. This is where the * action is and defines how the system reacts to large phase * and frequency errors. There are two main regimes: when the * offset exceeds the step threshold and when it does not. * However, if the step threshold is set to zero, a step will * never occur. See the instruction manual for the details how * these actions interact with the command line options. * * Note the system poll is set to minpoll only if the clock is * stepped. */ clock_frequency = flladj = plladj = 0; mu = peer->epoch - sys_clocktime; rval = 1; if (fabs(fp_offset) > clock_max && clock_max > 0) { switch (state) { /* * In S_SYNC state we ignore the first outlyer amd * switch to S_SPIK state. */ case S_SYNC: state = S_SPIK; return (0); /* * In S_FREQ state we ignore outlyers and inlyers. At * the first outlyer after the stepout threshold, * compute the apparent frequency correction and step * the phase. */ case S_FREQ: if (mu < clock_minstep) return (0); clock_frequency = (fp_offset - last_base - clock_offset) / mu; /* fall through to S_SPIK */ /* * In S_SPIK state we ignore succeeding outlyers until * either an inlyer is found or the stepout threshold is * exceeded. */ case S_SPIK: if (mu < clock_minstep) return (0); /* fall through to default */ /* * We get here by default in S_NSET and S_FSET states * and from above in S_FREQ or S_SPIK states. * * In S_NSET state an initial frequency correction is * not available, usually because the frequency file has * not yet been written. Since the time is outside the * step threshold, the clock is stepped. The frequency * will be set directly following the stepout interval. * * In S_FSET state the initial frequency has been set * from the frequency file. Since the time is outside * the step threshold, the clock is stepped immediately, * rather than after the stepout interval. Guys get * nervous if it takes 17 minutes to set the clock for * the first time. * * In S_FREQ and S_SPIK states the stepout threshold has * expired and the phase is still above the step * threshold. Note that a single spike greater than the * step threshold is always suppressed, even at the * longer poll intervals. */ default: step_systime(fp_offset); msyslog(LOG_NOTICE, "time reset %+.6f s", fp_offset); reinit_timer(); tc_counter = 0; sys_poll = NTP_MINPOLL; sys_tai = 0; clock_jitter = LOGTOD(sys_precision); rval = 2; if (state == S_NSET) { rstclock(S_FREQ, peer->epoch, 0); return (rval); } break; } rstclock(S_SYNC, peer->epoch, 0); } else { /* * The offset is less than the step threshold. Calculate * the jitter as the exponentially weighted offset * differences. */ etemp = SQUARE(clock_jitter); dtemp = SQUARE(max(fabs(fp_offset - last_offset), LOGTOD(sys_precision))); clock_jitter = SQRT(etemp + (dtemp - etemp) / CLOCK_AVG); switch (state) { /* * In S_NSET state this is the first update received and * the frequency has not been initialized. The first * thing to do is directly measure the frequency offset. */ case S_NSET: clock_offset = fp_offset; rstclock(S_FREQ, peer->epoch, fp_offset); return (0); /* * In S_FSET state this is the first update and the * frequency has been initialized. Adjust the phase, but * don't adjust the frequency until the next update. */ case S_FSET: clock_offset = fp_offset; break; /* * In S_FREQ state ignore updates until the stepout * threshold. After that, correct the phase and * frequency and switch to S_SYNC state. */ case S_FREQ: if (mu < clock_minstep) return (0); clock_frequency = (fp_offset - last_base - clock_offset) / mu; break; /* * We get here by default in S_SYNC and S_SPIK states. * Here we compute the frequency update due to PLL and * FLL contributions. */ default: allow_panic = FALSE; /* * The FLL and PLL frequency gain constants * depend on the poll interval and Allan * intercept. The PLL is always used, but * becomes ineffective above the Allan * intercept. The FLL is not used below one-half * the Allan intercept. Above that the loop gain * increases in steps to 1 / CLOCK_AVG. */ if (ULOGTOD(sys_poll) > allan_xpt / 2) { dtemp = CLOCK_FLL - sys_poll; flladj = (fp_offset - clock_offset) / (max(mu, allan_xpt) * dtemp); } /* * For the PLL the integration interval * (numerator) is the minimum of the update * interval and poll interval. This allows * oversampling, but not undersampling. */ etemp = min(mu, (u_long)ULOGTOD(sys_poll)); dtemp = 4 * CLOCK_PLL * ULOGTOD(sys_poll); plladj = fp_offset * etemp / (dtemp * dtemp); break; } rstclock(S_SYNC, peer->epoch, fp_offset); } #ifdef OPENSSL /* * Scan the loopsecond table to determine the TAI offset. If * there is a scheduled leap in future, set the leap warning, * but only if less than 30 days before the leap. */ tpt = (u_int32 *)tai_leap.ptr; len = ntohl(tai_leap.vallen) / sizeof(u_int32); if (tpt != NULL) { for (i = 0; i < len; i++) { togo = (long)ntohl(tpt[i]) - (long)peer->rec.l_ui; if (togo > 0) { if (togo < CLOCK_JUNE) leap_next |= LEAP_ADDSECOND; break; } } #if defined(STA_NANO) && NTP_API == 4 if (pll_control && kern_enable && sys_tai == 0) { memset(&ntv, 0, sizeof(ntv)); ntv.modes = MOD_TAI; ntv.constant = i + TAI_1972 - 1; ntp_adjtime(&ntv); } #endif /* STA_NANO */ sys_tai = i + TAI_1972 - 1; } #endif /* OPENSSL */ #ifdef KERNEL_PLL /* * This code segment works when clock adjustments are made using * precision time kernel support and the ntp_adjtime() system * call. This support is available in Solaris 2.6 and later, * Digital Unix 4.0 and later, FreeBSD, Linux and specially * modified kernels for HP-UX 9 and Ultrix 4. In the case of the * DECstation 5000/240 and Alpha AXP, additional kernel * modifications provide a true microsecond clock and nanosecond * clock, respectively. * * Important note: The kernel discipline is used only if the * offset is less than 0.5 s, as anything higher can lead to * overflow problems. This might occur if some misguided lad set * the step threshold to something ridiculous. No problem; use * the ntp discipline until the residual offset sinks beneath * the waves. */ if (pll_control && kern_enable && fabs(clock_offset) < .5) { /* * We initialize the structure for the ntp_adjtime() * system call. We have to convert everything to * microseconds or nanoseconds first. Do not update the * system variables if the ext_enable flag is set. In * this case, the external clock driver will update the * variables, which will be read later by the local * clock driver. Afterwards, remember the time and * frequency offsets for jitter and stability values and * to update the frequency file. */ memset(&ntv, 0, sizeof(ntv)); if (ext_enable) { ntv.modes = MOD_STATUS; } else { struct tm *tm = NULL; time_t tstamp; #ifdef STA_NANO ntv.modes = MOD_BITS | MOD_NANO; #else /* STA_NANO */ ntv.modes = MOD_BITS; #endif /* STA_NANO */ if (clock_offset < 0) dtemp = -.5; else dtemp = .5; #ifdef STA_NANO ntv.offset = (int32)(clock_offset * 1e9 + dtemp); ntv.constant = sys_poll; #else /* STA_NANO */ ntv.offset = (int32)(clock_offset * 1e6 + dtemp); ntv.constant = sys_poll - 4; #endif /* STA_NANO */ /* * The frequency is set directly only if * clock_frequency is nonzero coming out of FREQ * state. */ if (clock_frequency != 0) { ntv.modes |= MOD_FREQUENCY; ntv.freq = (int32)((clock_frequency + drift_comp) * 65536e6); } ntv.esterror = (u_int32)(clock_jitter * 1e6); ntv.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdispersion) * 1e6); ntv.status = STA_PLL; /* * Set the leap bits in the status word, but * only on the last day of June or December. */ tstamp = peer->rec.l_ui - JAN_1970; tm = gmtime(&tstamp); if (tm != NULL) { if ((tm->tm_mon + 1 == 6 && tm->tm_mday == 30) || (tm->tm_mon + 1 == 12 && tm->tm_mday == 31)) { if (leap_next & LEAP_ADDSECOND) ntv.status |= STA_INS; else if (leap_next & LEAP_DELSECOND) ntv.status |= STA_DEL; } } /* * Switch to FLL mode if the poll interval is * greater than MAXDPOLL, so that the kernel * loop behaves as the daemon loop; viz., * selects the FLL when necessary, etc. For * legacy only. */ if (sys_poll > NTP_MAXDPOLL) ntv.status |= STA_FLL; /* * If the PPS signal is up and enabled, light * the frequency bit. If the PPS driver is * working, light the phase bit as well. If not, * douse the lights, since somebody else may * have left the switch on. */ if (pps_enable && pll_status & STA_PPSSIGNAL) { ntv.status |= STA_PPSFREQ; if (pps_stratum < STRATUM_UNSPEC) ntv.status |= STA_PPSTIME; } else { ntv.status &= ~(STA_PPSFREQ | STA_PPSTIME); } } /* * Pass the stuff to the kernel. If it squeals, turn off * the pig. In any case, fetch the kernel offset and * frequency and pretend we did it here. */ if (ntp_adjtime(&ntv) == TIME_ERROR) { if (ntv.status != pll_status) NLOG(NLOG_SYNCEVENT | NLOG_SYSEVENT) msyslog(LOG_NOTICE, "kernel time sync disabled %04x", ntv.status); ntv.status &= ~(STA_PPSFREQ | STA_PPSTIME); } else { if (ntv.status != pll_status) NLOG(NLOG_SYNCEVENT | NLOG_SYSEVENT) msyslog(LOG_NOTICE, "kernel time sync enabled %04x", ntv.status); } pll_status = ntv.status; #ifdef STA_NANO clock_offset = ntv.offset / 1e9; #else /* STA_NANO */ clock_offset = ntv.offset / 1e6; #endif /* STA_NANO */ clock_frequency = ntv.freq / 65536e6; flladj = plladj = 0; /* * If the kernel PPS is lit, monitor its performance. */ if (ntv.status & STA_PPSTIME) { pps_control = current_time; #ifdef STA_NANO clock_jitter = ntv.jitter / 1e9; #else /* STA_NANO */ clock_jitter = ntv.jitter / 1e6; #endif /* STA_NANO */ } } else { #endif /* KERNEL_PLL */ /* * We get here if the kernel discipline is not enabled. * Adjust the clock frequency as the sum of the directly * computed frequency (if measured) and the PLL and FLL * increments. */ clock_frequency = drift_comp + clock_frequency + flladj + plladj; #ifdef KERNEL_PLL } #endif /* KERNEL_PLL */ /* * Clamp the frequency within the tolerance range and calculate * the frequency change since the last update. */ if (fabs(clock_frequency) > NTP_MAXFREQ) NLOG(NLOG_SYNCEVENT | NLOG_SYSEVENT) msyslog(LOG_NOTICE, "frequency error %.0f PPM exceeds tolerance %.0f PPM", clock_frequency * 1e6, NTP_MAXFREQ * 1e6); dtemp = SQUARE(clock_frequency - drift_comp); if (clock_frequency > NTP_MAXFREQ) drift_comp = NTP_MAXFREQ; else if (clock_frequency < -NTP_MAXFREQ) drift_comp = -NTP_MAXFREQ; else drift_comp = clock_frequency; /* * Calculate the wander as the exponentially weighted frequency * differences. */ etemp = SQUARE(clock_stability); clock_stability = SQRT(etemp + (dtemp - etemp) / CLOCK_AVG); /* * Here we adjust the poll interval by comparing the current * offset with the clock jitter. If the offset is less than the * clock jitter times a constant, then the averaging interval is * increased, otherwise it is decreased. A bit of hysteresis * helps calm the dance. Works best using burst mode. */ if (fabs(clock_offset) < CLOCK_PGATE * clock_jitter) { tc_counter += sys_poll; if (tc_counter > CLOCK_LIMIT) { tc_counter = CLOCK_LIMIT; if (sys_poll < peer->maxpoll) { tc_counter = 0; sys_poll++; } } } else { tc_counter -= sys_poll << 1; if (tc_counter < -CLOCK_LIMIT) { tc_counter = -CLOCK_LIMIT; if (sys_poll > peer->minpoll) { tc_counter = 0; sys_poll--; } } } /* * Yibbidy, yibbbidy, yibbidy; that'h all folks. */ record_loop_stats(clock_offset, drift_comp, clock_jitter, clock_stability, sys_poll); #ifdef DEBUG if (debug) printf( "local_clock: mu %lu jitr %.6f freq %.3f stab %.6f poll %d count %d\n", mu, clock_jitter, drift_comp * 1e6, clock_stability * 1e6, sys_poll, tc_counter); #endif /* DEBUG */ return (rval); #endif /* LOCKCLOCK */ } /* * adj_host_clock - Called once every second to update the local clock. * * LOCKCLOCK: The only thing this routine does is increment the * sys_rootdispersion variable. */ void adj_host_clock( void ) { double adjustment; /* * Update the dispersion since the last update. In contrast to * NTPv3, NTPv4 does not declare unsynchronized after one day, * since the dispersion check serves this function. Also, * since the poll interval can exceed one day, the old test * would be counterproductive. Note we do this even with * external clocks, since the clock driver will recompute the * maximum error and the local clock driver will pick it up and * pass to the common refclock routines. Very elegant. */ sys_rootdispersion += clock_phi; #ifndef LOCKCLOCK /* * Declare PPS kernel unsync if the pps signal has not been * heard for a few minutes. */ if (pps_control && current_time - pps_control > PPS_MAXAGE) { if (pps_control) NLOG(NLOG_SYNCEVENT | NLOG_SYSEVENT) msyslog(LOG_NOTICE, "pps sync disabled"); pps_control = 0; } /* * If NTP is disabled or ntpdate mode enabled or the kernel * discipline is enabled, we have no business going further. */ if (!ntp_enable || mode_ntpdate || (pll_control && kern_enable)) return; /* * Implement the phase and frequency adjustments. The gain * factor (denominator) is not allowed to increase beyond the * Allan intercept. It doesn't make sense to average phase noise * beyond this point and it helps to damp residual offset at the * longer poll intervals. */ adjustment = clock_offset / (CLOCK_PLL * min(ULOGTOD(sys_poll), allan_xpt)); clock_offset -= adjustment; adj_systime(adjustment + drift_comp); #endif /* LOCKCLOCK */ } /* * Clock state machine. Enter new state and set state variables. Note we * use the time of the last clock filter sample, which may be earlier * than the current time. */ static void rstclock( int trans, /* new state */ u_long update, /* new update time */ double offset /* new offset */ ) { state = trans; sys_clocktime = update; last_base = offset - clock_offset; last_offset = clock_offset = offset; #ifdef DEBUG if (debug) printf("local_clock: time %lu base %.6f offset %.6f freq %.3f state %d\n", sys_clocktime, last_base, last_offset, drift_comp * 1e6, trans); #endif } /* * huff-n'-puff filter */ void huffpuff() { int i; if (sys_huffpuff == NULL) return; sys_huffptr = (sys_huffptr + 1) % sys_hufflen; sys_huffpuff[sys_huffptr] = 1e9; sys_mindly = 1e9; for (i = 0; i < sys_hufflen; i++) { if (sys_huffpuff[i] < sys_mindly) sys_mindly = sys_huffpuff[i]; } } /* * loop_config - configure the loop filter * * LOCKCLOCK: The LOOP_DRIFTINIT and LOOP_DRIFTCOMP cases are no-ops. */ void loop_config( int item, double freq ) { int i; switch (item) { case LOOP_DRIFTINIT: #ifndef LOCKCLOCK #ifdef KERNEL_PLL /* * Assume the kernel supports the ntp_adjtime() syscall. * If that syscall works, initialize the kernel time * variables. Otherwise, continue leaving no harm * behind. While at it, ask to set nanosecond mode. If * the kernel agrees, rejoice; othewise, it does only * microseconds. * * Call out the safety patrol. If ntpdate mode or if the * step threshold has been increased by the -x option or * tinker command, kernel discipline is unsafe, so don't * do any of this stuff. Otherwise, initialize the * kernel to appear unsynchronized until the first * update is received. */ if (mode_ntpdate || clock_max > CLOCK_MAX) break; pll_control = 1; memset(&ntv, 0, sizeof(ntv)); #ifdef STA_NANO ntv.modes = MOD_BITS | MOD_NANO; #else /* STA_NANO */ ntv.modes = MOD_BITS; #endif /* STA_NANO */ ntv.maxerror = MAXDISPERSE; ntv.esterror = MAXDISPERSE; ntv.status = STA_UNSYNC; #ifdef SIGSYS /* * Use sigsetjmp() to save state and then call * ntp_adjtime(); if it fails, then siglongjmp() is used * to return control */ newsigsys.sa_handler = pll_trap; newsigsys.sa_flags = 0; if (sigaction(SIGSYS, &newsigsys, &sigsys)) { msyslog(LOG_ERR, "sigaction() fails to save SIGSYS trap: %m"); pll_control = 0; } if (sigsetjmp(env, 1) == 0) ntp_adjtime(&ntv); if ((sigaction(SIGSYS, &sigsys, (struct sigaction *)NULL))) { msyslog(LOG_ERR, "sigaction() fails to restore SIGSYS trap: %m"); pll_control = 0; } #else /* SIGSYS */ ntp_adjtime(&ntv); #endif /* SIGSYS */ /* * Save the result status and light up an external clock * if available. */ pll_status = ntv.status; if (pll_control) { #ifdef STA_NANO if (pll_status & STA_CLK) ext_enable = 1; #endif /* STA_NANO */ NLOG(NLOG_SYNCEVENT | NLOG_SYSEVENT) msyslog(LOG_INFO, "kernel time sync status %04x", pll_status); } #endif /* KERNEL_PLL */ #endif /* LOCKCLOCK */ break; case LOOP_DRIFTCOMP: #ifndef LOCKCLOCK /* * If the frequency value is reasonable, set the initial * frequency to the given value and the state to S_FSET. * Otherwise, the drift file may be missing or broken, * so set the frequency to zero. This erases past * history should somebody break something. */ if (freq <= NTP_MAXFREQ && freq >= -NTP_MAXFREQ) { drift_comp = freq; rstclock(S_FSET, 0, 0); } else { drift_comp = 0; } #ifdef KERNEL_PLL /* * Sanity check. If the kernel is available, load the * frequency and light up the loop. Make sure the offset * is zero to cancel any previous nonsense. If you don't * want this initialization, remove the ntp.drift file. */ if (pll_control && kern_enable) { memset((char *)&ntv, 0, sizeof(ntv)); ntv.modes = MOD_FREQUENCY; ntv.freq = (int32)(drift_comp * 65536e6); ntp_adjtime(&ntv); } #endif /* KERNEL_PLL */ #endif /* LOCKCLOCK */ break; case LOOP_KERN_CLEAR: #ifndef LOCKCLOCK #ifdef KERNEL_PLL /* Completely turn off the kernel time adjustments. */ if (pll_control) { memset((char *)&ntv, 0, sizeof(ntv)); ntv.modes = MOD_BITS | MOD_FREQUENCY; ntv.status = STA_UNSYNC; ntp_adjtime(&ntv); NLOG(NLOG_SYNCEVENT | NLOG_SYSEVENT) msyslog(LOG_INFO, "kernel time sync disabled %04x", ntv.status); } #endif /* KERNEL_PLL */ #endif /* LOCKCLOCK */ break; /* * Special tinker variables for Ulrich Windl. Very dangerous. */ case LOOP_MAX: /* step threshold */ clock_max = freq; break; case LOOP_PANIC: /* panic threshold */ clock_panic = freq; break; case LOOP_PHI: /* dispersion rate */ clock_phi = freq; break; case LOOP_MINSTEP: /* watchdog bark */ clock_minstep = freq; break; case LOOP_ALLAN: /* Allan intercept */ allan_xpt = freq; break; case LOOP_HUFFPUFF: /* huff-n'-puff filter length */ if (freq < HUFFPUFF) freq = HUFFPUFF; sys_hufflen = (int)(freq / HUFFPUFF); sys_huffpuff = (double *)emalloc(sizeof(double) * sys_hufflen); for (i = 0; i < sys_hufflen; i++) sys_huffpuff[i] = 1e9; sys_mindly = 1e9; break; case LOOP_FREQ: /* initial frequency */ drift_comp = freq / 1e6; rstclock(S_FSET, 0, 0); break; } } #if defined(KERNEL_PLL) && defined(SIGSYS) /* * _trap - trap processor for undefined syscalls * * This nugget is called by the kernel when the SYS_ntp_adjtime() * syscall bombs because the silly thing has not been implemented in * the kernel. In this case the phase-lock loop is emulated by * the stock adjtime() syscall and a lot of indelicate abuse. */ static RETSIGTYPE pll_trap( int arg ) { pll_control = 0; siglongjmp(env, 1); } #endif /* KERNEL_PLL && SIGSYS */