/* * ntp_loopfilter.c - implements the NTP loop filter algorithm * */ #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 offset (s) */ #define CLOCK_PANIC 1000. /* default panic offset (s) */ #define CLOCK_PHI 15e-6 /* max frequency error (s/s) */ #define SHIFT_PLL 4 /* PLL loop gain (shift) */ #define CLOCK_FLL 8. /* FLL loop gain */ #define CLOCK_AVG 4. /* parameter averaging constant */ #define CLOCK_MINSEC 256. /* min FLL update interval (s) */ #define CLOCK_MINSTEP 900. /* step-change timeout (s) */ #define CLOCK_DAY 86400. /* one day of seconds (s) */ #define CLOCK_LIMIT 30 /* poll-adjust threshold */ #define CLOCK_PGATE 4. /* poll-adjust gate */ #define CLOCK_ALLAN 10 /* min Allan intercept (log2 s) */ #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 < max > max Comments * ==================================================== * NSET FREQ FREQ no ntp.drift * * FSET TSET if (allow) TSET, ntp.drift * else FREQ * * TSET SYNC FREQ time set * * FREQ SYNC if (mu < 900) FREQ calculate frequency * else if (allow) TSET * else FREQ * * SYNC SYNC if (mu < 900) SYNC normal state * else SPIK * * SPIK SYNC if (allow) TSET spike detector * else FREQ */ #define S_NSET 0 /* clock never set */ #define S_FSET 1 /* frequency set from the drift file */ #define S_TSET 2 /* time set */ #define S_FREQ 3 /* frequency mode */ #define S_SYNC 4 /* clock synchronized */ #define S_SPIK 5 /* spike detected */ /* * 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 correctios 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 PLL used instead. * * 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; /* max offset before step (s) */ double clock_panic = CLOCK_PANIC; /* max offset before panic (s) */ double clock_phi = CLOCK_PHI; /* dispersion rate (s/s) */ double clock_minstep = CLOCK_MINSTEP; /* step timeout (s) */ u_char allan_xpt = CLOCK_ALLAN; /* minimum Allan intercept (log2 s) */ /* * Hybrid PLL/FLL parameters. These were chosen by experiment using a * MatLab program. The parameters were fudged to match a pure PLL at * poll intervals of 64 s and lower and a pure FLL at poll intervals of * 4096 s and higher. Between these extremes the parameters were chosen * as a geometric series of intervals while holding the overshoot to * less than 5 percent. */ static double fll[] = {0., 1./64, 1./32, 1./16, 1./8, 1./4, 1.}; static double pll[] = {1., 1.4, 2., 2.8, 4.1, 7., 12.}; /* * Program variables */ static double clock_offset; /* clock offset adjustment (s) */ double drift_comp; /* clock frequency (s/s) */ double clock_stability; /* clock stability (s/s) */ u_long pps_control; /* last pps sample time */ static void rstclock P((int, double, double)); /* transition function */ #ifdef KERNEL_PLL struct timex ntv; /* kernel API parameters */ int pll_status; /* status bits for kernel pll */ int pll_nano; /* nanosecond kernel switch */ #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_step = TRUE; /* allow step correction */ int allow_panic = FALSE; /* allow panic correction */ int mode_ntpdate = FALSE; /* exit on first clock set */ /* * Clock state machine variables */ u_char sys_minpoll = NTP_MINDPOLL; /* min sys poll interval (log2 s) */ u_char sys_poll = NTP_MINDPOLL; /* system poll interval (log2 s) */ int state; /* clock discipline state */ int tc_counter; /* poll-adjust counter */ u_long last_time; /* time of last clock update (s) */ double last_offset; /* last clock offset (s) */ double sys_jitter; /* system RMS jitter (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. */ rstclock(S_NSET, current_time, 0); } /* * local_clock - the NTP logical clock loop filter. Returns 1 if the * clock was stepped, 0 if it was slewed and -1 if it is hopeless. */ int local_clock( struct peer *peer, /* synch source peer structure */ double fp_offset, /* clock offset (s) */ double epsil /* jittter (square s*s) */ ) { double mu; /* interval since last update (s) */ double oerror; /* previous error estimate */ double flladj; /* FLL frequency adjustment (ppm) */ double plladj; /* PLL frequency adjustment (ppm) */ double clock_frequency; /* clock frequency adjustment (ppm) */ double dtemp, etemp; /* double temps */ int retval; /* return value */ int i; /* * If the loop is opened, monitor and record the offsets * anyway in order to determine the open-loop response. */ #ifdef DEBUG if (debug) printf( "local_clock: assocID %d off %.6f jit %.6f sta %d\n", peer->associd, fp_offset, SQRT(epsil), state); #endif if (!ntp_enable) { record_loop_stats(fp_offset, drift_comp, SQRT(epsil), 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 it FALSE when the update is * within the step range; 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 if ntpdate is active, the terminal does not detach, * so the termination comments print directly to the console. */ if (mode_ntpdate) { if (allow_step && fabs(fp_offset) > clock_max && clock_max > 0) { step_systime(fp_offset); NLOG(NLOG_SYNCEVENT|NLOG_SYSEVENT) msyslog(LOG_NOTICE, "time reset %.6f s", fp_offset); printf("ntpd: time reset %.6fs\n", fp_offset); } else { adj_systime(fp_offset); NLOG(NLOG_SYNCEVENT|NLOG_SYSEVENT) msyslog(LOG_NOTICE, "time slew %.6f s", fp_offset); printf("ntpd: time slew %.6fs\n", fp_offset); } record_loop_stats(fp_offset, drift_comp, SQRT(epsil), clock_stability, sys_poll); exit (0); } /* * If the clock has never been set, set it and initialize the * discipline parameters. We then switch to frequency mode to * speed the inital convergence process. If lucky, after an hour * the ntp.drift file is created and initialized and we don't * get here again. */ if (state == S_NSET) { step_systime(fp_offset); NLOG(NLOG_SYNCEVENT|NLOG_SYSEVENT) msyslog(LOG_NOTICE, "time set %.6f s", fp_offset); rstclock(S_FREQ, peer->epoch, fp_offset); return (1); } /* * Update the jitter estimate. */ oerror = sys_jitter; dtemp = SQUARE(sys_jitter); sys_jitter = SQRT(dtemp + (epsil - dtemp) / CLOCK_AVG); /* * 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. */ if (sys_huffpuff != NULL) { 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. */ retval = 0; if (sys_poll > peer->maxpoll) sys_poll = peer->maxpoll; else if (sys_poll < peer->minpoll) sys_poll = peer->minpoll; clock_frequency = flladj = plladj = 0; mu = peer->epoch - last_time; if (fabs(fp_offset) > clock_max && clock_max > 0) { switch (state) { /* * In S_TSET state the time has been set at the last * valid update and the offset at that time set to zero. * If following that we cruise outside the capture * range, assume a really bad frequency error and switch * to S_FREQ state. */ case S_TSET: state = S_FREQ; break; /* * In S_SYNC state we ignore outlyers. At the first * outlyer after the stepout threshold, switch to S_SPIK * state. */ case S_SYNC: if (mu < clock_minstep) return (0); state = S_SPIK; return (0); /* * In S_FREQ state we ignore outlyers. At the first * outlyer after 900 s, compute the apparent phase and * frequency correction. */ case S_FREQ: if (mu < clock_minstep) return (0); /* fall through to S_SPIK */ /* * In S_SPIK state a large correction is necessary. * Since the outlyer may be due to a large frequency * error, compute the apparent frequency correction. */ case S_SPIK: clock_frequency = (fp_offset - clock_offset) / mu; /* fall through to default */ /* * We get here directly in S_FSET state and indirectly * from S_FREQ and S_SPIK states. The clock is either * reset or shaken, but never stirred. */ default: if (allow_step) { step_systime(fp_offset); NLOG(NLOG_SYNCEVENT|NLOG_SYSEVENT) msyslog(LOG_NOTICE, "time reset %.6f s", fp_offset); rstclock(S_TSET, peer->epoch, 0); retval = 1; } else { NLOG(NLOG_SYNCEVENT|NLOG_SYSEVENT) msyslog(LOG_NOTICE, "time slew %.6f s", fp_offset); rstclock(S_FREQ, peer->epoch, fp_offset); } break; } } else { switch (state) { /* * In S_FSET state this is the first update. Adjust the * phase, but don't adjust the frequency until the next * update. */ case S_FSET: rstclock(S_TSET, peer->epoch, 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 - clock_offset) / mu; rstclock(S_SYNC, peer->epoch, fp_offset); break; /* * Either the clock has just been set or the previous * update was a spike and ignored. Since this update is * not an outlyer, fold the tent and resume life. */ case S_TSET: case S_SPIK: state = S_SYNC; /* fall through to default */ /* * We come here in the normal case for linear phase and * frequency adjustments. If the offset exceeds the * previous time error estimate by CLOCK_SGATE and the * interval since the last update is less than twice the * poll interval, consider the update a popcorn spike * and ignore it. */ default: allow_panic = FALSE; if (fabs(fp_offset - last_offset) > CLOCK_SGATE * oerror && mu < ULOGTOD(sys_poll + 1)) { #ifdef DEBUG if (debug) printf( "local_clock: popcorn %.6f %.6f\n", fabs(fp_offset - last_offset), CLOCK_SGATE * oerror); #endif last_offset = fp_offset; return (0); } /* * Compute the FLL and PLL frequency adjustments * conditioned on intricate weighting factors. * The gain factors depend on the poll interval * and Allan intercept. For the FLL, the * averaging interval is clamped to a minimum of * 1024 s and the gain increased in stages from * zero for poll intervals below half the Allan * intercept to unity above twice the Allan * intercept. For the PLL, the averaging * interval is clamped not to exceed the poll * interval. No gain factor is necessary, since * the frequency steering above the Allan * intercept is negligible. Particularly for the * PLL, these measures allow oversampling, but * not undersampling and insure stability even * when the rules of fair engagement are broken. */ i = sys_poll - allan_xpt + 4; if (i < 0) i = 0; else if (i > 6) i = 6; etemp = fll[i]; dtemp = max(mu, ULOGTOD(allan_xpt)); flladj = (fp_offset - clock_offset) * etemp / (dtemp * CLOCK_FLL); dtemp = ULOGTOD(SHIFT_PLL + 2 + sys_poll); etemp = min(mu, ULOGTOD(sys_poll)); plladj = fp_offset * etemp / (dtemp * dtemp); last_time = peer->epoch; last_offset = clock_offset = fp_offset; break; } } #if defined(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. */ if (pll_control && kern_enable) { /* * 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 drift file. */ memset(&ntv, 0, sizeof(ntv)); if (ext_enable) { ntv.modes = MOD_STATUS; } else { ntv.modes = MOD_BITS; if (clock_offset < 0) dtemp = -.5; else dtemp = .5; if (pll_nano) { ntv.offset = (int32)(clock_offset * 1e9 + dtemp); ntv.constant = sys_poll; } else { ntv.offset = (int32)(clock_offset * 1e6 + dtemp); ntv.constant = sys_poll - 4; } if (clock_frequency != 0) { ntv.modes |= MOD_FREQUENCY; ntv.freq = (int32)((clock_frequency + drift_comp) * 65536e6); } ntv.esterror = (u_int32)(sys_jitter * 1e6); ntv.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdispersion) * 1e6); ntv.status = STA_PLL; /* * Set the leap bits in the status word. */ if (sys_leap == LEAP_NOTINSYNC) { ntv.status |= STA_UNSYNC; } else if (calleapwhen(sys_reftime.l_ui) < CLOCK_DAY) { if (sys_leap & LEAP_ADDSECOND) ntv.status |= STA_INS; else if (sys_leap & 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 pigs. 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) msyslog(LOG_ERR, "kernel time discipline status change %x", ntv.status); ntv.status &= ~(STA_PPSFREQ | STA_PPSTIME); } pll_status = ntv.status; if (pll_nano) clock_offset = ntv.offset / 1e9; else clock_offset = ntv.offset / 1e6; clock_frequency = ntv.freq / 65536e6 - drift_comp; flladj = plladj = 0; /* * If the kernel PPS is lit, monitor its performance. */ if (ntv.status & STA_PPSTIME) { pps_control = current_time; if (pll_nano) sys_jitter = ntv.jitter / 1e9; else sys_jitter = ntv.jitter / 1e6; } } #endif /* KERNEL_PLL */ /* * Adjust the clock frequency and calculate the stability. If * kernel support is available, we use the results of the kernel * discipline instead of the PLL/FLL discipline. In this case, * drift_comp is a sham and used only for updating the drift * file and for billboard eye candy. */ etemp = clock_frequency + flladj + plladj; drift_comp += etemp; if (drift_comp > NTP_MAXFREQ) drift_comp = NTP_MAXFREQ; else if (drift_comp <= -NTP_MAXFREQ) drift_comp = -NTP_MAXFREQ; dtemp = SQUARE(clock_stability); etemp = SQUARE(etemp) - dtemp; clock_stability = SQRT(dtemp + etemp / CLOCK_AVG); /* * In SYNC state, adjust the poll interval. The trick here is to * compare the apparent frequency change induced by the system * jitter over the poll interval, or fritter, to the frequency * stability. If the fritter is greater than the stability, * phase noise predominates and the averaging interval is * increased; otherwise, it is decreased. A bit of hysteresis * helps calm the dance. Works best using burst mode. */ if (state == S_SYNC) { if (sys_jitter / ULOGTOD(sys_poll) > clock_stability && fabs(clock_offset) < CLOCK_PGATE * sys_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--; } } } } /* * Update the system time variables. */ dtemp = peer->disp + sys_jitter; if ((peer->flags & FLAG_REFCLOCK) == 0 && dtemp < MINDISPERSE) dtemp = MINDISPERSE; sys_rootdispersion = peer->rootdispersion + dtemp; record_loop_stats(last_offset, drift_comp, sys_jitter, clock_stability, sys_poll); #ifdef DEBUG if (debug) printf( "local_clock: mu %.0f noi %.3f stb %.3f pol %d cnt %d\n", mu, sys_jitter * 1e6, clock_stability * 1e6, sys_poll, tc_counter); #endif /* DEBUG */ return (retval); } /* * adj_host_clock - Called once every second to update the local clock. */ void adj_host_clock( void ) { double adjustment; int i; /* * 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; /* * 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_SYSEVENT) /* conditional if clause */ msyslog(LOG_INFO, "pps sync disabled"); pps_control = 0; } if (!ntp_enable) return; /* * If the phase-lock loop is implemented in the kernel, we * have no business going further. */ if (pll_control && kern_enable) return; /* * Intricate wrinkle for legacy only. If the local clock driver * is in use and selected for synchronization, somebody else may * tinker the adjtime() syscall. If this is the case, the driver * is marked prefer and we have to avoid calling adjtime(), * since that may truncate the other guy's requests. */ if (sys_peer != 0) { if (sys_peer->refclktype == REFCLK_LOCALCLOCK && sys_peer->flags & FLAG_PREFER) return; } /* * This ugly bit of business is necessary in order to move the * pole frequency higher in FLL mode. This is necessary for loop * stability. */ i = sys_poll - allan_xpt + 4; if (i < 0) i = 0; else if (i > 6) i = 6; adjustment = clock_offset / (pll[i] * ULOGTOD(SHIFT_PLL + sys_poll)); clock_offset -= adjustment; adj_systime(adjustment + drift_comp); } /* * Clock state machine. Enter new state and set state variables. */ static void rstclock( int trans, /* new state */ double epoch, /* last time */ double offset /* last offset */ ) { tc_counter = 0; sys_poll = NTP_MINPOLL; state = trans; last_time = epoch; last_offset = clock_offset = offset; } /* * 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 */ void loop_config( int item, double freq ) { int i; switch (item) { case LOOP_DRIFTINIT: #ifdef KERNEL_PLL /* * Assume the kernel supports the ntp_adjtime() syscall. * If that syscall works, initialize the kernel * 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. */ pll_control = 1; memset(&ntv, 0, sizeof(ntv)); #ifdef STA_NANO ntv.modes = MOD_BITS | MOD_NANO; #else 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 */ pll_status = ntv.status; if (pll_control) { #ifdef STA_NANO if (pll_status & STA_NANO) pll_nano = 1; if (pll_status & STA_CLK) ext_enable = 1; #endif /* STA_NANO */ msyslog(LOG_NOTICE, "kernel time discipline status %04x", pll_status); } #endif /* KERNEL_PLL */ break; case LOOP_DRIFTCOMP: /* * Initialize the kernel frequency and clamp to * reasonable value. Also set the initial state to * S_FSET to indicated the frequency has been * initialized from the previously saved drift file. */ rstclock(S_FSET, current_time, 0); drift_comp = freq; if (drift_comp > NTP_MAXFREQ) drift_comp = NTP_MAXFREQ; if (drift_comp < -NTP_MAXFREQ) drift_comp = -NTP_MAXFREQ; #ifdef KERNEL_PLL /* * Sanity check. If the kernel is enabled, load the * frequency and light up the loop. If not, set the * kernel frequency to zero and leave the loop dark. In * either case set the time to zero to cancel any * previous nonsense. */ if (pll_control) { memset((char *)&ntv, 0, sizeof(ntv)); ntv.modes = MOD_OFFSET | MOD_FREQUENCY; if (kern_enable) { ntv.modes |= MOD_STATUS; ntv.status = STA_PLL; ntv.freq = (int32)(drift_comp * 65536e6); } (void)ntp_adjtime(&ntv); } #endif /* KERNEL_PLL */ break; /* * Special tinker variables for Ulrich Windl. Very dangerous. */ case LOOP_MAX: /* step threshold */ clock_max = freq; break; case LOOP_PANIC: /* panic exit 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_MINPOLL: /* ephemeral association poll */ if (freq < NTP_MINPOLL) freq = NTP_MINPOLL; sys_minpoll = (u_char)freq; break; case LOOP_ALLAN: /* minimum Allan intercept */ if (freq < CLOCK_ALLAN) freq = CLOCK_ALLAN; allan_xpt = (u_char)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; } } #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 */