1 /* $NetBSD: kern_ntptime.c,v 1.64 2022/10/26 23:23:52 riastradh Exp $ */
2
3 /*-
4 * Copyright (c) 2008 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 /*-
30 ***********************************************************************
31 * *
32 * Copyright (c) David L. Mills 1993-2001 *
33 * *
34 * Permission to use, copy, modify, and distribute this software and *
35 * its documentation for any purpose and without fee is hereby *
36 * granted, provided that the above copyright notice appears in all *
37 * copies and that both the copyright notice and this permission *
38 * notice appear in supporting documentation, and that the name *
39 * University of Delaware not be used in advertising or publicity *
40 * pertaining to distribution of the software without specific, *
41 * written prior permission. The University of Delaware makes no *
42 * representations about the suitability this software for any *
43 * purpose. It is provided "as is" without express or implied *
44 * warranty. *
45 * *
46 **********************************************************************/
47
48 /*
49 * Adapted from the original sources for FreeBSD and timecounters by:
50 * Poul-Henning Kamp <phk@FreeBSD.org>.
51 *
52 * The 32bit version of the "LP" macros seems a bit past its "sell by"
53 * date so I have retained only the 64bit version and included it directly
54 * in this file.
55 *
56 * Only minor changes done to interface with the timecounters over in
57 * sys/kern/kern_clock.c. Some of the comments below may be (even more)
58 * confusing and/or plain wrong in that context.
59 */
60
61 #include <sys/cdefs.h>
62 /* __FBSDID("$FreeBSD: src/sys/kern/kern_ntptime.c,v 1.59 2005/05/28 14:34:41 rwatson Exp $"); */
63 __KERNEL_RCSID(0, "$NetBSD: kern_ntptime.c,v 1.64 2022/10/26 23:23:52 riastradh Exp $");
64
65 #ifdef _KERNEL_OPT
66 #include "opt_ntp.h"
67 #endif
68
69 #include <sys/param.h>
70 #include <sys/resourcevar.h>
71 #include <sys/systm.h>
72 #include <sys/kernel.h>
73 #include <sys/proc.h>
74 #include <sys/sysctl.h>
75 #include <sys/timex.h>
76 #include <sys/vnode.h>
77 #include <sys/kauth.h>
78 #include <sys/mount.h>
79 #include <sys/syscallargs.h>
80 #include <sys/cpu.h>
81
82 #include <compat/sys/timex.h>
83
84 /*
85 * Single-precision macros for 64-bit machines
86 */
87 typedef int64_t l_fp;
88 #define L_ADD(v, u) ((v) += (u))
89 #define L_SUB(v, u) ((v) -= (u))
90 #define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32)
91 #define L_NEG(v) ((v) = -(v))
92 #define L_RSHIFT(v, n) \
93 do { \
94 if ((v) < 0) \
95 (v) = -(-(v) >> (n)); \
96 else \
97 (v) = (v) >> (n); \
98 } while (0)
99 #define L_MPY(v, a) ((v) *= (a))
100 #define L_CLR(v) ((v) = 0)
101 #define L_ISNEG(v) ((v) < 0)
102 #define L_LINT(v, a) ((v) = (int64_t)((uint64_t)(a) << 32))
103 #define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32)
104
105 #ifdef NTP
106 /*
107 * Generic NTP kernel interface
108 *
109 * These routines constitute the Network Time Protocol (NTP) interfaces
110 * for user and daemon application programs. The ntp_gettime() routine
111 * provides the time, maximum error (synch distance) and estimated error
112 * (dispersion) to client user application programs. The ntp_adjtime()
113 * routine is used by the NTP daemon to adjust the system clock to an
114 * externally derived time. The time offset and related variables set by
115 * this routine are used by other routines in this module to adjust the
116 * phase and frequency of the clock discipline loop which controls the
117 * system clock.
118 *
119 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO
120 * defined), the time at each tick interrupt is derived directly from
121 * the kernel time variable. When the kernel time is reckoned in
122 * microseconds, (NTP_NANO undefined), the time is derived from the
123 * kernel time variable together with a variable representing the
124 * leftover nanoseconds at the last tick interrupt. In either case, the
125 * current nanosecond time is reckoned from these values plus an
126 * interpolated value derived by the clock routines in another
127 * architecture-specific module. The interpolation can use either a
128 * dedicated counter or a processor cycle counter (PCC) implemented in
129 * some architectures.
130 *
131 * Note that all routines must run at priority splclock or higher.
132 */
133 /*
134 * Phase/frequency-lock loop (PLL/FLL) definitions
135 *
136 * The nanosecond clock discipline uses two variable types, time
137 * variables and frequency variables. Both types are represented as 64-
138 * bit fixed-point quantities with the decimal point between two 32-bit
139 * halves. On a 32-bit machine, each half is represented as a single
140 * word and mathematical operations are done using multiple-precision
141 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is
142 * used.
143 *
144 * A time variable is a signed 64-bit fixed-point number in ns and
145 * fraction. It represents the remaining time offset to be amortized
146 * over succeeding tick interrupts. The maximum time offset is about
147 * 0.5 s and the resolution is about 2.3e-10 ns.
148 *
149 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
150 * 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
151 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
152 * |s s s| ns |
153 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
154 * | fraction |
155 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
156 *
157 * A frequency variable is a signed 64-bit fixed-point number in ns/s
158 * and fraction. It represents the ns and fraction to be added to the
159 * kernel time variable at each second. The maximum frequency offset is
160 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s.
161 *
162 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
163 * 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
164 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
165 * |s s s s s s s s s s s s s| ns/s |
166 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
167 * | fraction |
168 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
169 */
170 /*
171 * The following variables establish the state of the PLL/FLL and the
172 * residual time and frequency offset of the local clock.
173 */
174 #define SHIFT_PLL 4 /* PLL loop gain (shift) */
175 #define SHIFT_FLL 2 /* FLL loop gain (shift) */
176
177 static int time_state = TIME_OK; /* clock state */
178 static int time_status = STA_UNSYNC; /* clock status bits */
179 static long time_tai; /* TAI offset (s) */
180 static long time_monitor; /* last time offset scaled (ns) */
181 static long time_constant; /* poll interval (shift) (s) */
182 static long time_precision = 1; /* clock precision (ns) */
183 static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */
184 static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */
185 static time_t time_reftime; /* time at last adjustment (s) */
186 static l_fp time_offset; /* time offset (ns) */
187 static l_fp time_freq; /* frequency offset (ns/s) */
188 #endif /* NTP */
189
190 static l_fp time_adj; /* tick adjust (ns/s) */
191 int64_t time_adjtime; /* correction from adjtime(2) (usec) */
192
193 #ifdef NTP
194 #ifdef PPS_SYNC
195 /*
196 * The following variables are used when a pulse-per-second (PPS) signal
197 * is available and connected via a modem control lead. They establish
198 * the engineering parameters of the clock discipline loop when
199 * controlled by the PPS signal.
200 */
201 #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */
202 #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */
203 #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */
204 #define PPS_PAVG 4 /* phase avg interval (s) (shift) */
205 #define PPS_VALID 120 /* PPS signal watchdog max (s) */
206 #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */
207 #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */
208
209 static struct timespec pps_tf[3]; /* phase median filter */
210 static l_fp pps_freq; /* scaled frequency offset (ns/s) */
211 static long pps_fcount; /* frequency accumulator */
212 static long pps_jitter; /* nominal jitter (ns) */
213 static long pps_stabil; /* nominal stability (scaled ns/s) */
214 static long pps_lastsec; /* time at last calibration (s) */
215 static int pps_valid; /* signal watchdog counter */
216 static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */
217 static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */
218 static int pps_intcnt; /* wander counter */
219
220 /*
221 * PPS signal quality monitors
222 */
223 static long pps_calcnt; /* calibration intervals */
224 static long pps_jitcnt; /* jitter limit exceeded */
225 static long pps_stbcnt; /* stability limit exceeded */
226 static long pps_errcnt; /* calibration errors */
227 #endif /* PPS_SYNC */
228 /*
229 * End of phase/frequency-lock loop (PLL/FLL) definitions
230 */
231
232 static void hardupdate(long offset);
233
234 /*
235 * ntp_gettime() - NTP user application interface
236 */
237 void
ntp_gettime(struct ntptimeval * ntv)238 ntp_gettime(struct ntptimeval *ntv)
239 {
240 memset(ntv, 0, sizeof(*ntv));
241
242 mutex_spin_enter(&timecounter_lock);
243 nanotime(&ntv->time);
244 ntv->maxerror = time_maxerror;
245 ntv->esterror = time_esterror;
246 ntv->tai = time_tai;
247 ntv->time_state = time_state;
248 mutex_spin_exit(&timecounter_lock);
249 }
250
251 /* ARGSUSED */
252 /*
253 * ntp_adjtime() - NTP daemon application interface
254 */
255 int
sys_ntp_adjtime(struct lwp * l,const struct sys_ntp_adjtime_args * uap,register_t * retval)256 sys_ntp_adjtime(struct lwp *l, const struct sys_ntp_adjtime_args *uap, register_t *retval)
257 {
258 /* {
259 syscallarg(struct timex *) tp;
260 } */
261 struct timex ntv;
262 int error;
263
264 error = copyin((void *)SCARG(uap, tp), (void *)&ntv, sizeof(ntv));
265 if (error != 0)
266 return (error);
267
268 if (ntv.modes != 0 && (error = kauth_authorize_system(l->l_cred,
269 KAUTH_SYSTEM_TIME, KAUTH_REQ_SYSTEM_TIME_NTPADJTIME, NULL,
270 NULL, NULL)) != 0)
271 return (error);
272
273 ntp_adjtime1(&ntv);
274
275 error = copyout((void *)&ntv, (void *)SCARG(uap, tp), sizeof(ntv));
276 if (!error)
277 *retval = ntp_timestatus();
278
279 return error;
280 }
281
282 void
ntp_adjtime1(struct timex * ntv)283 ntp_adjtime1(struct timex *ntv)
284 {
285 long freq;
286 int modes;
287
288 /*
289 * Update selected clock variables - only the superuser can
290 * change anything. Note that there is no error checking here on
291 * the assumption the superuser should know what it is doing.
292 * Note that either the time constant or TAI offset are loaded
293 * from the ntv.constant member, depending on the mode bits. If
294 * the STA_PLL bit in the status word is cleared, the state and
295 * status words are reset to the initial values at boot.
296 */
297 mutex_spin_enter(&timecounter_lock);
298 modes = ntv->modes;
299 if (modes != 0)
300 /* We need to save the system time during shutdown */
301 time_adjusted |= 2;
302 if (modes & MOD_MAXERROR)
303 time_maxerror = ntv->maxerror;
304 if (modes & MOD_ESTERROR)
305 time_esterror = ntv->esterror;
306 if (modes & MOD_STATUS) {
307 if (time_status & STA_PLL && !(ntv->status & STA_PLL)) {
308 time_state = TIME_OK;
309 time_status = STA_UNSYNC;
310 #ifdef PPS_SYNC
311 pps_shift = PPS_FAVG;
312 #endif /* PPS_SYNC */
313 }
314 time_status &= STA_RONLY;
315 time_status |= ntv->status & ~STA_RONLY;
316 }
317 if (modes & MOD_TIMECONST) {
318 if (ntv->constant < 0)
319 time_constant = 0;
320 else if (ntv->constant > MAXTC)
321 time_constant = MAXTC;
322 else
323 time_constant = ntv->constant;
324 }
325 if (modes & MOD_TAI) {
326 if (ntv->constant > 0) /* XXX zero & negative numbers ? */
327 time_tai = ntv->constant;
328 }
329 #ifdef PPS_SYNC
330 if (modes & MOD_PPSMAX) {
331 if (ntv->shift < PPS_FAVG)
332 pps_shiftmax = PPS_FAVG;
333 else if (ntv->shift > PPS_FAVGMAX)
334 pps_shiftmax = PPS_FAVGMAX;
335 else
336 pps_shiftmax = ntv->shift;
337 }
338 #endif /* PPS_SYNC */
339 if (modes & MOD_NANO)
340 time_status |= STA_NANO;
341 if (modes & MOD_MICRO)
342 time_status &= ~STA_NANO;
343 if (modes & MOD_CLKB)
344 time_status |= STA_CLK;
345 if (modes & MOD_CLKA)
346 time_status &= ~STA_CLK;
347 if (modes & MOD_FREQUENCY) {
348 freq = MIN(INT32_MAX, MAX(INT32_MIN, ntv->freq));
349 freq = (freq * (int64_t)1000) >> 16;
350 if (freq > MAXFREQ)
351 L_LINT(time_freq, MAXFREQ);
352 else if (freq < -MAXFREQ)
353 L_LINT(time_freq, -MAXFREQ);
354 else {
355 /*
356 * ntv.freq is [PPM * 2^16] = [us/s * 2^16]
357 * time_freq is [ns/s * 2^32]
358 */
359 time_freq = ntv->freq * 1000LL * 65536LL;
360 }
361 #ifdef PPS_SYNC
362 pps_freq = time_freq;
363 #endif /* PPS_SYNC */
364 }
365 if (modes & MOD_OFFSET) {
366 if (time_status & STA_NANO) {
367 hardupdate(ntv->offset);
368 } else {
369 long offset = ntv->offset;
370 offset = MIN(offset, MAXPHASE/1000);
371 offset = MAX(offset, -MAXPHASE/1000);
372 hardupdate(offset * 1000);
373 }
374 }
375
376 /*
377 * Retrieve all clock variables. Note that the TAI offset is
378 * returned only by ntp_gettime();
379 */
380 if (time_status & STA_NANO)
381 ntv->offset = L_GINT(time_offset);
382 else
383 ntv->offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */
384 if (time_freq < 0)
385 ntv->freq = L_GINT(-((-time_freq / 1000LL) << 16));
386 else
387 ntv->freq = L_GINT((time_freq / 1000LL) << 16);
388 ntv->maxerror = time_maxerror;
389 ntv->esterror = time_esterror;
390 ntv->status = time_status;
391 ntv->constant = time_constant;
392 if (time_status & STA_NANO)
393 ntv->precision = time_precision;
394 else
395 ntv->precision = time_precision / 1000;
396 ntv->tolerance = MAXFREQ * SCALE_PPM;
397 #ifdef PPS_SYNC
398 ntv->shift = pps_shift;
399 ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16);
400 if (time_status & STA_NANO)
401 ntv->jitter = pps_jitter;
402 else
403 ntv->jitter = pps_jitter / 1000;
404 ntv->stabil = pps_stabil;
405 ntv->calcnt = pps_calcnt;
406 ntv->errcnt = pps_errcnt;
407 ntv->jitcnt = pps_jitcnt;
408 ntv->stbcnt = pps_stbcnt;
409 #endif /* PPS_SYNC */
410 mutex_spin_exit(&timecounter_lock);
411 }
412 #endif /* NTP */
413
414 /*
415 * second_overflow() - called after ntp_tick_adjust()
416 *
417 * This routine is ordinarily called immediately following the above
418 * routine ntp_tick_adjust(). While these two routines are normally
419 * combined, they are separated here only for the purposes of
420 * simulation.
421 */
422 void
ntp_update_second(int64_t * adjustment,time_t * newsec)423 ntp_update_second(int64_t *adjustment, time_t *newsec)
424 {
425 int tickrate;
426 l_fp ftemp; /* 32/64-bit temporary */
427
428 KASSERT(mutex_owned(&timecounter_lock));
429
430 #ifdef NTP
431
432 /*
433 * On rollover of the second both the nanosecond and microsecond
434 * clocks are updated and the state machine cranked as
435 * necessary. The phase adjustment to be used for the next
436 * second is calculated and the maximum error is increased by
437 * the tolerance.
438 */
439 time_maxerror += MAXFREQ / 1000;
440
441 /*
442 * Leap second processing. If in leap-insert state at
443 * the end of the day, the system clock is set back one
444 * second; if in leap-delete state, the system clock is
445 * set ahead one second. The nano_time() routine or
446 * external clock driver will insure that reported time
447 * is always monotonic.
448 */
449 switch (time_state) {
450
451 /*
452 * No warning.
453 */
454 case TIME_OK:
455 if (time_status & STA_INS)
456 time_state = TIME_INS;
457 else if (time_status & STA_DEL)
458 time_state = TIME_DEL;
459 break;
460
461 /*
462 * Insert second 23:59:60 following second
463 * 23:59:59.
464 */
465 case TIME_INS:
466 if (!(time_status & STA_INS))
467 time_state = TIME_OK;
468 else if ((*newsec) % 86400 == 0) {
469 (*newsec)--;
470 time_state = TIME_OOP;
471 time_tai++;
472 }
473 break;
474
475 /*
476 * Delete second 23:59:59.
477 */
478 case TIME_DEL:
479 if (!(time_status & STA_DEL))
480 time_state = TIME_OK;
481 else if (((*newsec) + 1) % 86400 == 0) {
482 (*newsec)++;
483 time_tai--;
484 time_state = TIME_WAIT;
485 }
486 break;
487
488 /*
489 * Insert second in progress.
490 */
491 case TIME_OOP:
492 time_state = TIME_WAIT;
493 break;
494
495 /*
496 * Wait for status bits to clear.
497 */
498 case TIME_WAIT:
499 if (!(time_status & (STA_INS | STA_DEL)))
500 time_state = TIME_OK;
501 }
502
503 /*
504 * Compute the total time adjustment for the next second
505 * in ns. The offset is reduced by a factor depending on
506 * whether the PPS signal is operating. Note that the
507 * value is in effect scaled by the clock frequency,
508 * since the adjustment is added at each tick interrupt.
509 */
510 ftemp = time_offset;
511 #ifdef PPS_SYNC
512 /* XXX even if PPS signal dies we should finish adjustment ? */
513 if (time_status & STA_PPSTIME && time_status &
514 STA_PPSSIGNAL)
515 L_RSHIFT(ftemp, pps_shift);
516 else
517 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
518 #else
519 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
520 #endif /* PPS_SYNC */
521 time_adj = ftemp;
522 L_SUB(time_offset, ftemp);
523 L_ADD(time_adj, time_freq);
524
525 #ifdef PPS_SYNC
526 if (pps_valid > 0)
527 pps_valid--;
528 else
529 time_status &= ~STA_PPSSIGNAL;
530 #endif /* PPS_SYNC */
531 #else /* !NTP */
532 L_CLR(time_adj);
533 #endif /* !NTP */
534
535 /*
536 * Apply any correction from adjtime(2). If more than one second
537 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM)
538 * until the last second is slewed the final < 500 usecs.
539 */
540 if (time_adjtime != 0) {
541 if (time_adjtime > 1000000)
542 tickrate = 5000;
543 else if (time_adjtime < -1000000)
544 tickrate = -5000;
545 else if (time_adjtime > 500)
546 tickrate = 500;
547 else if (time_adjtime < -500)
548 tickrate = -500;
549 else
550 tickrate = time_adjtime;
551 time_adjtime -= tickrate;
552 L_LINT(ftemp, tickrate * 1000);
553 L_ADD(time_adj, ftemp);
554 }
555 *adjustment = time_adj;
556 }
557
558 /*
559 * ntp_init() - initialize variables and structures
560 *
561 * This routine must be called after the kernel variables hz and tick
562 * are set or changed and before the next tick interrupt. In this
563 * particular implementation, these values are assumed set elsewhere in
564 * the kernel. The design allows the clock frequency and tick interval
565 * to be changed while the system is running. So, this routine should
566 * probably be integrated with the code that does that.
567 */
568 void
ntp_init(void)569 ntp_init(void)
570 {
571
572 /*
573 * The following variables are initialized only at startup. Only
574 * those structures not cleared by the compiler need to be
575 * initialized, and these only in the simulator. In the actual
576 * kernel, any nonzero values here will quickly evaporate.
577 */
578 L_CLR(time_adj);
579 #ifdef NTP
580 L_CLR(time_offset);
581 L_CLR(time_freq);
582 #ifdef PPS_SYNC
583 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;
584 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;
585 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;
586 pps_fcount = 0;
587 L_CLR(pps_freq);
588 #endif /* PPS_SYNC */
589 #endif
590 }
591
592 #ifdef NTP
593 /*
594 * hardupdate() - local clock update
595 *
596 * This routine is called by ntp_adjtime() to update the local clock
597 * phase and frequency. The implementation is of an adaptive-parameter,
598 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
599 * time and frequency offset estimates for each call. If the kernel PPS
600 * discipline code is configured (PPS_SYNC), the PPS signal itself
601 * determines the new time offset, instead of the calling argument.
602 * Presumably, calls to ntp_adjtime() occur only when the caller
603 * believes the local clock is valid within some bound (+-128 ms with
604 * NTP). If the caller's time is far different than the PPS time, an
605 * argument will ensue, and it's not clear who will lose.
606 *
607 * For uncompensated quartz crystal oscillators and nominal update
608 * intervals less than 256 s, operation should be in phase-lock mode,
609 * where the loop is disciplined to phase. For update intervals greater
610 * than 1024 s, operation should be in frequency-lock mode, where the
611 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
612 * is selected by the STA_MODE status bit.
613 *
614 * Note: splclock() is in effect.
615 */
616 void
hardupdate(long offset)617 hardupdate(long offset)
618 {
619 long mtemp;
620 l_fp ftemp;
621
622 KASSERT(mutex_owned(&timecounter_lock));
623
624 /*
625 * Select how the phase is to be controlled and from which
626 * source. If the PPS signal is present and enabled to
627 * discipline the time, the PPS offset is used; otherwise, the
628 * argument offset is used.
629 */
630 if (!(time_status & STA_PLL))
631 return;
632 if (!(time_status & STA_PPSTIME && time_status &
633 STA_PPSSIGNAL)) {
634 if (offset > MAXPHASE)
635 time_monitor = MAXPHASE;
636 else if (offset < -MAXPHASE)
637 time_monitor = -MAXPHASE;
638 else
639 time_monitor = offset;
640 L_LINT(time_offset, time_monitor);
641 }
642
643 /*
644 * Select how the frequency is to be controlled and in which
645 * mode (PLL or FLL). If the PPS signal is present and enabled
646 * to discipline the frequency, the PPS frequency is used;
647 * otherwise, the argument offset is used to compute it.
648 */
649 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {
650 time_reftime = time_second;
651 return;
652 }
653 if (time_status & STA_FREQHOLD || time_reftime == 0)
654 time_reftime = time_second;
655 mtemp = time_second - time_reftime;
656 L_LINT(ftemp, time_monitor);
657 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
658 L_MPY(ftemp, mtemp);
659 L_ADD(time_freq, ftemp);
660 time_status &= ~STA_MODE;
661 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
662 MAXSEC)) {
663 L_LINT(ftemp, (time_monitor << 4) / mtemp);
664 L_RSHIFT(ftemp, SHIFT_FLL + 4);
665 L_ADD(time_freq, ftemp);
666 time_status |= STA_MODE;
667 }
668 time_reftime = time_second;
669 if (L_GINT(time_freq) > MAXFREQ)
670 L_LINT(time_freq, MAXFREQ);
671 else if (L_GINT(time_freq) < -MAXFREQ)
672 L_LINT(time_freq, -MAXFREQ);
673 }
674
675 #ifdef PPS_SYNC
676 /*
677 * hardpps() - discipline CPU clock oscillator to external PPS signal
678 *
679 * This routine is called at each PPS interrupt in order to discipline
680 * the CPU clock oscillator to the PPS signal. It measures the PPS phase
681 * and leaves it in a handy spot for the hardclock() routine. It
682 * integrates successive PPS phase differences and calculates the
683 * frequency offset. This is used in hardclock() to discipline the CPU
684 * clock oscillator so that intrinsic frequency error is cancelled out.
685 * The code requires the caller to capture the time and hardware counter
686 * value at the on-time PPS signal transition.
687 *
688 * Note that, on some Unix systems, this routine runs at an interrupt
689 * priority level higher than the timer interrupt routine hardclock().
690 * Therefore, the variables used are distinct from the hardclock()
691 * variables, except for certain exceptions: The PPS frequency pps_freq
692 * and phase pps_offset variables are determined by this routine and
693 * updated atomically. The time_tolerance variable can be considered a
694 * constant, since it is infrequently changed, and then only when the
695 * PPS signal is disabled. The watchdog counter pps_valid is updated
696 * once per second by hardclock() and is atomically cleared in this
697 * routine.
698 */
699 void
hardpps(struct timespec * tsp,long nsec)700 hardpps(struct timespec *tsp, /* time at PPS */
701 long nsec /* hardware counter at PPS */)
702 {
703 long u_sec, u_nsec, v_nsec; /* temps */
704 l_fp ftemp;
705
706 KASSERT(mutex_owned(&timecounter_lock));
707
708 /*
709 * The signal is first processed by a range gate and frequency
710 * discriminator. The range gate rejects noise spikes outside
711 * the range +-500 us. The frequency discriminator rejects input
712 * signals with apparent frequency outside the range 1 +-500
713 * PPM. If two hits occur in the same second, we ignore the
714 * later hit; if not and a hit occurs outside the range gate,
715 * keep the later hit for later comparison, but do not process
716 * it.
717 */
718 time_status |= STA_PPSSIGNAL | STA_PPSJITTER;
719 time_status &= ~(STA_PPSWANDER | STA_PPSERROR);
720 pps_valid = PPS_VALID;
721 u_sec = tsp->tv_sec;
722 u_nsec = tsp->tv_nsec;
723 if (u_nsec >= (NANOSECOND >> 1)) {
724 u_nsec -= NANOSECOND;
725 u_sec++;
726 }
727 v_nsec = u_nsec - pps_tf[0].tv_nsec;
728 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND -
729 MAXFREQ)
730 return;
731 pps_tf[2] = pps_tf[1];
732 pps_tf[1] = pps_tf[0];
733 pps_tf[0].tv_sec = u_sec;
734 pps_tf[0].tv_nsec = u_nsec;
735
736 /*
737 * Compute the difference between the current and previous
738 * counter values. If the difference exceeds 0.5 s, assume it
739 * has wrapped around, so correct 1.0 s. If the result exceeds
740 * the tick interval, the sample point has crossed a tick
741 * boundary during the last second, so correct the tick. Very
742 * intricate.
743 */
744 u_nsec = nsec;
745 if (u_nsec > (NANOSECOND >> 1))
746 u_nsec -= NANOSECOND;
747 else if (u_nsec < -(NANOSECOND >> 1))
748 u_nsec += NANOSECOND;
749 pps_fcount += u_nsec;
750 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
751 return;
752 time_status &= ~STA_PPSJITTER;
753
754 /*
755 * A three-stage median filter is used to help denoise the PPS
756 * time. The median sample becomes the time offset estimate; the
757 * difference between the other two samples becomes the time
758 * dispersion (jitter) estimate.
759 */
760 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {
761 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {
762 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */
763 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;
764 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {
765 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */
766 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;
767 } else {
768 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */
769 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;
770 }
771 } else {
772 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {
773 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */
774 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;
775 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {
776 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */
777 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;
778 } else {
779 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */
780 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;
781 }
782 }
783
784 /*
785 * Nominal jitter is due to PPS signal noise and interrupt
786 * latency. If it exceeds the popcorn threshold, the sample is
787 * discarded. otherwise, if so enabled, the time offset is
788 * updated. We can tolerate a modest loss of data here without
789 * much degrading time accuracy.
790 */
791 if (u_nsec > (pps_jitter << PPS_POPCORN)) {
792 time_status |= STA_PPSJITTER;
793 pps_jitcnt++;
794 } else if (time_status & STA_PPSTIME) {
795 time_monitor = -v_nsec;
796 L_LINT(time_offset, time_monitor);
797 }
798 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;
799 u_sec = pps_tf[0].tv_sec - pps_lastsec;
800 if (u_sec < (1 << pps_shift))
801 return;
802
803 /*
804 * At the end of the calibration interval the difference between
805 * the first and last counter values becomes the scaled
806 * frequency. It will later be divided by the length of the
807 * interval to determine the frequency update. If the frequency
808 * exceeds a sanity threshold, or if the actual calibration
809 * interval is not equal to the expected length, the data are
810 * discarded. We can tolerate a modest loss of data here without
811 * much degrading frequency accuracy.
812 */
813 pps_calcnt++;
814 v_nsec = -pps_fcount;
815 pps_lastsec = pps_tf[0].tv_sec;
816 pps_fcount = 0;
817 u_nsec = MAXFREQ << pps_shift;
818 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 <<
819 pps_shift)) {
820 time_status |= STA_PPSERROR;
821 pps_errcnt++;
822 return;
823 }
824
825 /*
826 * Here the raw frequency offset and wander (stability) is
827 * calculated. If the wander is less than the wander threshold
828 * for four consecutive averaging intervals, the interval is
829 * doubled; if it is greater than the threshold for four
830 * consecutive intervals, the interval is halved. The scaled
831 * frequency offset is converted to frequency offset. The
832 * stability metric is calculated as the average of recent
833 * frequency changes, but is used only for performance
834 * monitoring.
835 */
836 L_LINT(ftemp, v_nsec);
837 L_RSHIFT(ftemp, pps_shift);
838 L_SUB(ftemp, pps_freq);
839 u_nsec = L_GINT(ftemp);
840 if (u_nsec > PPS_MAXWANDER) {
841 L_LINT(ftemp, PPS_MAXWANDER);
842 pps_intcnt--;
843 time_status |= STA_PPSWANDER;
844 pps_stbcnt++;
845 } else if (u_nsec < -PPS_MAXWANDER) {
846 L_LINT(ftemp, -PPS_MAXWANDER);
847 pps_intcnt--;
848 time_status |= STA_PPSWANDER;
849 pps_stbcnt++;
850 } else {
851 pps_intcnt++;
852 }
853 if (pps_intcnt >= 4) {
854 pps_intcnt = 4;
855 if (pps_shift < pps_shiftmax) {
856 pps_shift++;
857 pps_intcnt = 0;
858 }
859 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {
860 pps_intcnt = -4;
861 if (pps_shift > PPS_FAVG) {
862 pps_shift--;
863 pps_intcnt = 0;
864 }
865 }
866 if (u_nsec < 0)
867 u_nsec = -u_nsec;
868 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;
869
870 /*
871 * The PPS frequency is recalculated and clamped to the maximum
872 * MAXFREQ. If enabled, the system clock frequency is updated as
873 * well.
874 */
875 L_ADD(pps_freq, ftemp);
876 u_nsec = L_GINT(pps_freq);
877 if (u_nsec > MAXFREQ)
878 L_LINT(pps_freq, MAXFREQ);
879 else if (u_nsec < -MAXFREQ)
880 L_LINT(pps_freq, -MAXFREQ);
881 if (time_status & STA_PPSFREQ)
882 time_freq = pps_freq;
883 }
884 #endif /* PPS_SYNC */
885 #endif /* NTP */
886
887 #ifdef NTP
888 int
ntp_timestatus(void)889 ntp_timestatus(void)
890 {
891 int rv;
892
893 /*
894 * Status word error decode. If any of these conditions
895 * occur, an error is returned, instead of the status
896 * word. Most applications will care only about the fact
897 * the system clock may not be trusted, not about the
898 * details.
899 *
900 * Hardware or software error
901 */
902 mutex_spin_enter(&timecounter_lock);
903 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||
904
905 /*
906 * PPS signal lost when either time or frequency
907 * synchronization requested
908 */
909 (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
910 !(time_status & STA_PPSSIGNAL)) ||
911
912 /*
913 * PPS jitter exceeded when time synchronization
914 * requested
915 */
916 (time_status & STA_PPSTIME &&
917 time_status & STA_PPSJITTER) ||
918
919 /*
920 * PPS wander exceeded or calibration error when
921 * frequency synchronization requested
922 */
923 (time_status & STA_PPSFREQ &&
924 time_status & (STA_PPSWANDER | STA_PPSERROR)))
925 rv = TIME_ERROR;
926 else
927 rv = time_state;
928 mutex_spin_exit(&timecounter_lock);
929
930 return rv;
931 }
932
933 /*ARGSUSED*/
934 /*
935 * ntp_gettime() - NTP user application interface
936 */
937 int
sys___ntp_gettime50(struct lwp * l,const struct sys___ntp_gettime50_args * uap,register_t * retval)938 sys___ntp_gettime50(struct lwp *l, const struct sys___ntp_gettime50_args *uap, register_t *retval)
939 {
940 /* {
941 syscallarg(struct ntptimeval *) ntvp;
942 } */
943 struct ntptimeval ntv;
944 int error = 0;
945
946 if (SCARG(uap, ntvp)) {
947 ntp_gettime(&ntv);
948
949 error = copyout((void *)&ntv, (void *)SCARG(uap, ntvp),
950 sizeof(ntv));
951 }
952 if (!error) {
953 *retval = ntp_timestatus();
954 }
955 return(error);
956 }
957
958 /*
959 * return information about kernel precision timekeeping
960 */
961 static int
sysctl_kern_ntptime(SYSCTLFN_ARGS)962 sysctl_kern_ntptime(SYSCTLFN_ARGS)
963 {
964 struct sysctlnode node;
965 struct ntptimeval ntv;
966
967 ntp_gettime(&ntv);
968
969 node = *rnode;
970 node.sysctl_data = &ntv;
971 node.sysctl_size = sizeof(ntv);
972 return (sysctl_lookup(SYSCTLFN_CALL(&node)));
973 }
974
975 SYSCTL_SETUP(sysctl_kern_ntptime_setup, "sysctl kern.ntptime node setup")
976 {
977
978 sysctl_createv(clog, 0, NULL, NULL,
979 CTLFLAG_PERMANENT,
980 CTLTYPE_STRUCT, "ntptime",
981 SYSCTL_DESCR("Kernel clock values for NTP"),
982 sysctl_kern_ntptime, 0, NULL,
983 sizeof(struct ntptimeval),
984 CTL_KERN, KERN_NTPTIME, CTL_EOL);
985 }
986 #endif /* !NTP */
987