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freebsd-dev/sys/kern/kern_ntptime.c
Dmitriy Alexandrov af9ce4e9bb kern_ntptime: Fix undefined behavior of the shift operator 
L_LINT macro is used with negative numbers [i.e.
L_LINT(time_freq, -MAXFREQ)], it could cause undefined
behavior. It should be similar to the L_RSHIFT(v, n) macro.

MFC after:	2 weeks
Reviewed by:	cy
Pull Request:	https://github.com/freebsd/freebsd-src/pull/769
Signed-off-by: Dmitriy Alexandrov <d06alexandrov@gmail.com>
2023-06-09 14:04:54 -07:00

1050 lines
31 KiB
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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("$FreeBSD$");
#include "opt_ntp.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/priv.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>
#ifdef PPS_SYNC
FEATURE(pps_sync, "Support usage of external PPS signal by kernel PLL");
#endif
/*
* 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) \
do { \
if ((a) < 0) \
((v) = -((int64_t)(-(a)) << 32)); \
else \
((v) = (int64_t)(a) << 32); \
} while (0)
#define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32)
/*
* Generic NTP kernel interface
*
* These routines constitute the Network Time Protocol (NTP) interfaces
* for user and daemon application programs. The ntp_gettime() routine
* provides the time, maximum error (synch distance) and estimated error
* (dispersion) to client user application programs. The ntp_adjtime()
* routine is used by the NTP daemon to adjust the 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 */
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) */
long time_esterror = MAXPHASE / 1000; /* estimated error (us) */
static long time_reftime; /* uptime 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) */
static struct mtx ntp_lock;
MTX_SYSINIT(ntp, &ntp_lock, "ntp", MTX_SPIN);
#define NTP_LOCK() mtx_lock_spin(&ntp_lock)
#define NTP_UNLOCK() mtx_unlock_spin(&ntp_lock)
#define NTP_ASSERT_LOCKED() mtx_assert(&ntp_lock, MA_OWNED)
#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 hardupdate(long offset);
static void ntp_gettime1(struct ntptimeval *ntvp);
static bool ntp_is_time_error(int tsl);
static bool
ntp_is_time_error(int tsl)
{
/*
* 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 ((tsl & (STA_UNSYNC | STA_CLOCKERR)) ||
/*
* PPS signal lost when either time or frequency synchronization
* requested
*/
(tsl & (STA_PPSFREQ | STA_PPSTIME) &&
!(tsl & STA_PPSSIGNAL)) ||
/*
* PPS jitter exceeded when time synchronization requested
*/
(tsl & STA_PPSTIME && tsl & STA_PPSJITTER) ||
/*
* PPS wander exceeded or calibration error when frequency
* synchronization requested
*/
(tsl & STA_PPSFREQ &&
tsl & (STA_PPSWANDER | STA_PPSERROR)))
return (true);
return (false);
}
static void
ntp_gettime1(struct ntptimeval *ntvp)
{
struct timespec atv; /* nanosecond time */
NTP_ASSERT_LOCKED();
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;
if (ntp_is_time_error(time_status))
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 */
int
sys_ntp_gettime(struct thread *td, struct ntp_gettime_args *uap)
{
struct ntptimeval ntv;
memset(&ntv, 0, sizeof(ntv));
NTP_LOCK();
ntp_gettime1(&ntv);
NTP_UNLOCK();
td->td_retval[0] = ntv.time_state;
return (copyout(&ntv, uap->ntvp, sizeof(ntv)));
}
static int
ntp_sysctl(SYSCTL_HANDLER_ARGS)
{
struct ntptimeval ntv; /* temporary structure */
memset(&ntv, 0, sizeof(ntv));
NTP_LOCK();
ntp_gettime1(&ntv);
NTP_UNLOCK();
return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req));
}
SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
"");
SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE | CTLFLAG_RD |
CTLFLAG_MPSAFE, 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval",
"");
#ifdef PPS_SYNC
SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW,
&pps_shiftmax, 0, "Max interval duration (sec) (shift)");
SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW,
&pps_shift, 0, "Interval duration (sec) (shift)");
SYSCTL_LONG(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD,
&time_monitor, 0, "Last time offset scaled (ns)");
SYSCTL_S64(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD | CTLFLAG_MPSAFE,
&pps_freq, 0,
"Scaled frequency offset (ns/sec)");
SYSCTL_S64(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD | CTLFLAG_MPSAFE,
&time_freq, 0,
"Frequency offset (ns/sec)");
#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.
*/
int
kern_ntp_adjtime(struct thread *td, struct timex *ntv, int *retvalp)
{
long freq; /* frequency ns/s) */
int modes; /* mode bits from structure */
int error, retval;
/*
* Update selected clock variables - only the superuser can
* change anything. Note that there is no error checking here on
* the assumption the superuser should know what it is doing.
* Note that either the time constant or TAI offset are loaded
* from the ntv.constant member, depending on the mode bits. If
* the STA_PLL bit in the status word is cleared, the state and
* status words are reset to the initial values at boot.
*/
modes = ntv->modes;
error = 0;
if (modes)
error = priv_check(td, PRIV_NTP_ADJTIME);
if (error != 0)
return (error);
NTP_LOCK();
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_SYNC
pps_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;
else
time_constant = ntv->constant;
}
if (modes & MOD_TAI) {
if (ntv->constant > 0) /* XXX zero & negative numbers ? */
time_tai = ntv->constant;
}
#ifdef PPS_SYNC
if (modes & MOD_PPSMAX) {
if (ntv->shift < PPS_FAVG)
pps_shiftmax = PPS_FAVG;
else if (ntv->shift > PPS_FAVGMAX)
pps_shiftmax = PPS_FAVGMAX;
else
pps_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_SYNC
pps_freq = time_freq;
#endif /* PPS_SYNC */
}
if (modes & MOD_OFFSET) {
if (time_status & STA_NANO)
hardupdate(ntv->offset);
else
hardupdate(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);
else
ntv->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;
else
ntv->precision = time_precision / 1000;
ntv->tolerance = MAXFREQ * SCALE_PPM;
#ifdef PPS_SYNC
ntv->shift = pps_shift;
ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16);
if (time_status & STA_NANO)
ntv->jitter = pps_jitter;
else
ntv->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 */
retval = ntp_is_time_error(time_status) ? TIME_ERROR : time_state;
NTP_UNLOCK();
*retvalp = retval;
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct ntp_adjtime_args {
struct timex *tp;
};
#endif
int
sys_ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap)
{
struct timex ntv;
int error, retval;
error = copyin(uap->tp, &ntv, sizeof(ntv));
if (error == 0) {
error = kern_ntp_adjtime(td, &ntv, &retval);
if (error == 0) {
error = copyout(&ntv, uap->tp, sizeof(ntv));
if (error == 0)
td->td_retval[0] = retval;
}
}
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.
*/
void
ntp_update_second(int64_t *adjustment, time_t *newsec)
{
int tickrate;
l_fp ftemp; /* 32/64-bit temporary */
NTP_LOCK();
/*
* 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);
else
L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
#else
L_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 (500 PPM)
* until the last second is slewed the final < 500 usecs.
*/
if (time_adjtime != 0) {
if (time_adjtime > 1000000)
tickrate = 5000;
else if (time_adjtime < -1000000)
tickrate = -5000;
else if (time_adjtime > 500)
tickrate = 500;
else if (time_adjtime < -500)
tickrate = -500;
else
tickrate = time_adjtime;
time_adjtime -= tickrate;
L_LINT(ftemp, tickrate * 1000);
L_ADD(time_adj, ftemp);
}
*adjustment = time_adj;
#ifdef PPS_SYNC
if (pps_valid > 0)
pps_valid--;
else
time_status &= ~STA_PPSSIGNAL;
#endif /* PPS_SYNC */
NTP_UNLOCK();
}
/*
* 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 void
hardupdate(long offset /* clock offset (ns) */)
{
long mtemp;
l_fp ftemp;
NTP_ASSERT_LOCKED();
/*
* 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;
else
time_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_uptime;
return;
}
if (time_status & STA_FREQHOLD || time_reftime == 0)
time_reftime = time_uptime;
mtemp = time_uptime - time_reftime;
L_LINT(ftemp, time_monitor);
L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
L_MPY(ftemp, mtemp);
L_ADD(time_freq, ftemp);
time_status &= ~STA_MODE;
if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
MAXSEC)) {
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_uptime;
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.
*
* tsp - time at current PPS event
* delta_nsec - time elapsed between the previous and current PPS event
*/
void
hardpps(struct timespec *tsp, long delta_nsec)
{
long u_sec, u_nsec, v_nsec; /* temps */
l_fp ftemp;
NTP_LOCK();
/*
* 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)
goto out;
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;
/*
* Update the frequency accumulator using the difference between the
* current and previous PPS event measured directly by the timecounter.
*/
pps_fcount += delta_nsec - NANOSECOND;
if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
goto out;
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.
*
* The measurements being checked here were made with the system
* timecounter, so the popcorn threshold is not allowed to fall below
* the number of nanoseconds in two ticks of the timecounter. For a
* timecounter running faster than 1 GHz the lower bound is 2ns, just
* to avoid a nonsensical threshold of zero.
*/
if (u_nsec > lmax(pps_jitter << PPS_POPCORN,
2 * (NANOSECOND / (long)qmin(NANOSECOND, tc_getfrequency())))) {
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))
goto out;
/*
* 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++;
goto out;
}
/*
* 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;
out:
NTP_UNLOCK();
}
#endif /* PPS_SYNC */
#ifndef _SYS_SYSPROTO_H_
struct adjtime_args {
struct timeval *delta;
struct timeval *olddelta;
};
#endif
/* ARGSUSED */
int
sys_adjtime(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 = &delta;
} else
deltap = NULL;
error = kern_adjtime(td, deltap, &olddelta);
if (uap->olddelta && error == 0)
error = copyout(&olddelta, uap->olddelta, sizeof(olddelta));
return (error);
}
int
kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta)
{
struct timeval atv;
int64_t ltr, ltw;
int error;
if (delta != NULL) {
error = priv_check(td, PRIV_ADJTIME);
if (error != 0)
return (error);
ltw = (int64_t)delta->tv_sec * 1000000 + delta->tv_usec;
}
NTP_LOCK();
ltr = time_adjtime;
if (delta != NULL)
time_adjtime = ltw;
NTP_UNLOCK();
if (olddelta != NULL) {
atv.tv_sec = ltr / 1000000;
atv.tv_usec = ltr % 1000000;
if (atv.tv_usec < 0) {
atv.tv_usec += 1000000;
atv.tv_sec--;
}
*olddelta = atv;
}
return (0);
}
static struct callout resettodr_callout;
static int resettodr_period = 1800;
static void
periodic_resettodr(void *arg __unused)
{
/*
* Read of time_status is lock-less, which is fine since
* ntp_is_time_error() operates on the consistent read value.
*/
if (!ntp_is_time_error(time_status))
resettodr();
if (resettodr_period > 0)
callout_schedule(&resettodr_callout, resettodr_period * hz);
}
static void
shutdown_resettodr(void *arg __unused, int howto __unused)
{
callout_drain(&resettodr_callout);
/* Another unlocked read of time_status */
if (resettodr_period > 0 && !ntp_is_time_error(time_status))
resettodr();
}
static int
sysctl_resettodr_period(SYSCTL_HANDLER_ARGS)
{
int error;
error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
if (error || !req->newptr)
return (error);
if (cold)
goto done;
if (resettodr_period == 0)
callout_stop(&resettodr_callout);
else
callout_reset(&resettodr_callout, resettodr_period * hz,
periodic_resettodr, NULL);
done:
return (0);
}
SYSCTL_PROC(_machdep, OID_AUTO, rtc_save_period, CTLTYPE_INT | CTLFLAG_RWTUN |
CTLFLAG_MPSAFE, &resettodr_period, 1800, sysctl_resettodr_period, "I",
"Save system time to RTC with this period (in seconds)");
static void
start_periodic_resettodr(void *arg __unused)
{
EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_resettodr, NULL,
SHUTDOWN_PRI_FIRST);
callout_init(&resettodr_callout, 1);
if (resettodr_period == 0)
return;
callout_reset(&resettodr_callout, resettodr_period * hz,
periodic_resettodr, NULL);
}
SYSINIT(periodic_resettodr, SI_SUB_LAST, SI_ORDER_MIDDLE,
start_periodic_resettodr, NULL);
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