FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_ntptime.c

     /*      $NetBSD: kern_ntptime.c,v 1.41 2006/11/01 10:17:58 yamt Exp $   */
     #include <sys/types.h>  /* XXX to get __HAVE_TIMECOUNTER, remove
                                after all ports are converted. */
     #ifdef __HAVE_TIMECOUNTER
     
     /*-
      ***********************************************************************
      *                                                                     *
      * Copyright (c) David L. Mills 1993-2001                              *
     *                                                                     *
     * Permission to use, copy, modify, and distribute this software and   *
     * its documentation for any purpose and without fee is hereby         *
     * granted, provided that the above copyright notice appears in all    *
     * copies and that both the copyright notice and this permission       *
     * notice appear in supporting documentation, and that the name        *
     * University of Delaware not be used in advertising or publicity      *
     * pertaining to distribution of the software without specific,        *
     * written prior permission. The University of Delaware makes no       *
     * representations about the suitability this software for any         *
     * purpose. It is provided "as is" without express or implied          *
     * warranty.                                                           *
     *                                                                     *
     **********************************************************************/
    
    /*
     * Adapted from the original sources for FreeBSD and timecounters by:
     * Poul-Henning Kamp <phk@FreeBSD.org>.
     *
     * The 32bit version of the "LP" macros seems a bit past its "sell by" 
     * date so I have retained only the 64bit version and included it directly
     * in this file.
     *
     * Only minor changes done to interface with the timecounters over in
     * sys/kern/kern_clock.c.   Some of the comments below may be (even more)
     * confusing and/or plain wrong in that context.
     */
    
    #include <sys/cdefs.h>
    /* __FBSDID("$FreeBSD: src/sys/kern/kern_ntptime.c,v 1.59 2005/05/28 14:34:41 rwatson Exp $"); */
    __KERNEL_RCSID(0, "$NetBSD: kern_ntptime.c,v 1.41 2006/11/01 10:17:58 yamt Exp $");
    
    #include "opt_ntp.h"
    #include "opt_compat_netbsd.h"
    
    #include <sys/param.h>
    #include <sys/resourcevar.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/proc.h>
    #include <sys/sysctl.h>
    #include <sys/timex.h>
    #ifdef COMPAT_30
    #include <compat/sys/timex.h>
    #endif
    #include <sys/vnode.h>
    #include <sys/kauth.h>
    
    #include <sys/mount.h>
    #include <sys/sa.h>
    #include <sys/syscallargs.h>
    
    #include <machine/cpu.h>
    
    /*
     * Single-precision macros for 64-bit machines
     */
    typedef int64_t l_fp;
    #define L_ADD(v, u)     ((v) += (u))
    #define L_SUB(v, u)     ((v) -= (u))
    #define L_ADDHI(v, a)   ((v) += (int64_t)(a) << 32)
    #define L_NEG(v)        ((v) = -(v))
    #define L_RSHIFT(v, n) \
            do { \
                    if ((v) < 0) \
                            (v) = -(-(v) >> (n)); \
                    else \
                            (v) = (v) >> (n); \
            } while (0)
    #define L_MPY(v, a)     ((v) *= (a))
    #define L_CLR(v)        ((v) = 0)
    #define L_ISNEG(v)      ((v) < 0)
    #define L_LINT(v, a)    ((v) = (int64_t)(a) << 32)
    #define L_GINT(v)       ((v) < 0 ? -(-(v) >> 32) : (v) >> 32)
    
    #ifdef NTP
    /*
     * Generic NTP kernel interface
     *
     * These routines constitute the Network Time Protocol (NTP) interfaces
     * for user and daemon application programs. The ntp_gettime() routine
     * provides the time, maximum error (synch distance) and estimated error
     * (dispersion) to client user application programs. The ntp_adjtime()
     * routine is used by the NTP daemon to adjust the system clock to an
     * externally derived time. The time offset and related variables set by
     * this routine are used by other routines in this module to adjust the
     * phase and frequency of the clock discipline loop which controls the
     * system clock.
     *
     * When the kernel time is reckoned directly in nanoseconds (NTP_NANO
    * defined), the time at each tick interrupt is derived directly from
    * the kernel time variable. When the kernel time is reckoned in
    * microseconds, (NTP_NANO undefined), the time is derived from the
    * kernel time variable together with a variable representing the
    * leftover nanoseconds at the last tick interrupt. In either case, the
    * current nanosecond time is reckoned from these values plus an
    * interpolated value derived by the clock routines in another
    * architecture-specific module. The interpolation can use either a
    * dedicated counter or a processor cycle counter (PCC) implemented in
    * some architectures.
    *
    * Note that all routines must run at priority splclock or higher.
    */
   /*
    * Phase/frequency-lock loop (PLL/FLL) definitions
    *
    * The nanosecond clock discipline uses two variable types, time
    * variables and frequency variables. Both types are represented as 64-
    * bit fixed-point quantities with the decimal point between two 32-bit
    * halves. On a 32-bit machine, each half is represented as a single
    * word and mathematical operations are done using multiple-precision
    * arithmetic. On a 64-bit machine, ordinary computer arithmetic is
    * used.
    *
    * A time variable is a signed 64-bit fixed-point number in ns and
    * fraction. It represents the remaining time offset to be amortized
    * over succeeding tick interrupts. The maximum time offset is about
    * 0.5 s and the resolution is about 2.3e-10 ns.
    *
    *                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
    *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * |s s s|                       ns                                |
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * |                        fraction                               |
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    *
    * A frequency variable is a signed 64-bit fixed-point number in ns/s
    * and fraction. It represents the ns and fraction to be added to the
    * kernel time variable at each second. The maximum frequency offset is
    * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s.
    *
    *                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
    *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * |s s s s s s s s s s s s s|            ns/s                     |
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    * |                        fraction                               |
    * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    */
   /*
    * The following variables establish the state of the PLL/FLL and the
    * residual time and frequency offset of the local clock.
    */
   #define SHIFT_PLL       4               /* PLL loop gain (shift) */
   #define SHIFT_FLL       2               /* FLL loop gain (shift) */
   
   static int time_state = TIME_OK;        /* clock state */
   static int time_status = STA_UNSYNC;    /* clock status bits */
   static long time_tai;                   /* TAI offset (s) */
   static long time_monitor;               /* last time offset scaled (ns) */
   static long time_constant;              /* poll interval (shift) (s) */
   static long time_precision = 1;         /* clock precision (ns) */
   static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */
   static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */
   static long time_reftime;               /* time at last adjustment (s) */
   static l_fp time_offset;                /* time offset (ns) */
   static l_fp time_freq;                  /* frequency offset (ns/s) */
   #endif /* NTP */
   
   static l_fp time_adj;                   /* tick adjust (ns/s) */
   int64_t time_adjtime;           /* correction from adjtime(2) (usec) */
   
   extern int time_adjusted;       /* ntp might have changed the system time */
   
   #ifdef NTP
   #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);
   
   /*
    * ntp_gettime() - NTP user application interface
    */
   void
   ntp_gettime(ntv)
           struct ntptimeval *ntv;
   {
           nanotime(&ntv->time);
           ntv->maxerror = time_maxerror;
           ntv->esterror = time_esterror;
           ntv->tai = time_tai;
           ntv->time_state = time_state;
   }
   
   /* ARGSUSED */
   /*
    * ntp_adjtime() - NTP daemon application interface
    */
   int
   sys_ntp_adjtime(l, v, retval)
           struct lwp *l;
           void *v;
           register_t *retval;
   {
           struct sys_ntp_adjtime_args /* {
                   syscallarg(struct timex *) tp;
           } */ *uap = v;
           struct timex ntv;
           int error = 0;
   
           error = copyin((caddr_t)SCARG(uap, tp), (caddr_t)&ntv, sizeof(ntv));
           if (error != 0)
                   return (error);
   
           if (ntv.modes != 0 && (error = kauth_authorize_system(l->l_cred,
               KAUTH_SYSTEM_TIME, KAUTH_REQ_SYSTEM_TIME_NTPADJTIME, NULL,
               NULL, NULL)) != 0)
                   return (error);
   
           ntp_adjtime1(&ntv);
   
           error = copyout((caddr_t)&ntv, (caddr_t)SCARG(uap, tp), sizeof(ntv));
           if (!error)
                   *retval = ntp_timestatus();
   
           return error;
   }
   
   void
   ntp_adjtime1(ntv)
           struct timex *ntv;
   {
           long freq;
           int modes;
           int s;
   
           /*
            * 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;
           if (modes != 0)
                   /* We need to save the system time during shutdown */
                   time_adjusted |= 2;
           s = splclock();
           if (modes & MOD_MAXERROR)
                   time_maxerror = ntv->maxerror;
           if (modes & MOD_ESTERROR)
                   time_esterror = ntv->esterror;
           if (modes & MOD_STATUS) {
                   if (time_status & STA_PLL && !(ntv->status & STA_PLL)) {
                           time_state = TIME_OK;
                           time_status = STA_UNSYNC;
   #ifdef PPS_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 */
           splx(s);
   }
   #endif /* NTP */
   
   /*
    * 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 */
   
   #ifdef NTP
   
           /*
            * 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);
           
   #ifdef PPS_SYNC
           if (pps_valid > 0)
                   pps_valid--;
           else
                   time_status &= ~STA_PPSSIGNAL;
   #endif /* PPS_SYNC */
   #else  /* !NTP */
           L_CLR(time_adj);
   #endif /* !NTP */
   
           /*
            * Apply any correction from adjtime(2).  If more than one second
            * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM)
            * until the last second is slewed the final < 500 usecs.
            */
           if (time_adjtime != 0) {
                   if (time_adjtime > 1000000)
                           tickrate = 5000;
                   else if (time_adjtime < -1000000)
                           tickrate = -5000;
                   else if (time_adjtime > 500)
                           tickrate = 500;
                   else if (time_adjtime < -500)
                           tickrate = -500;
                   else
                           tickrate = time_adjtime;
                   time_adjtime -= tickrate;
                   L_LINT(ftemp, tickrate * 1000);
                   L_ADD(time_adj, ftemp);
           }
           *adjustment = time_adj;
   }
   
   /*
    * ntp_init() - initialize variables and structures
    *
    * This routine must be called after the kernel variables hz and tick
    * are set or changed and before the next tick interrupt. In this
    * particular implementation, these values are assumed set elsewhere in
    * the kernel. The design allows the clock frequency and tick interval
    * to be changed while the system is running. So, this routine should
    * probably be integrated with the code that does that.
    */
   void
   ntp_init(void)
   {
   
           /*
            * The following variables are initialized only at startup. Only
            * those structures not cleared by the compiler need to be
            * initialized, and these only in the simulator. In the actual
            * kernel, any nonzero values here will quickly evaporate.
            */
           L_CLR(time_adj);
   #ifdef NTP
           L_CLR(time_offset);
           L_CLR(time_freq);
   #ifdef PPS_SYNC
           pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;
           pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;
           pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;
           pps_fcount = 0;
           L_CLR(pps_freq);
   #endif /* PPS_SYNC */
   #endif
   }
   
   #ifdef NTP
   /*
    * 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.
    *
    * Note: splclock() is in effect.
    */
   void
   hardupdate(long offset)
   {
           long mtemp;
           l_fp ftemp;
   
           /*
            * Select how the phase is to be controlled and from which
            * source. If the PPS signal is present and enabled to
            * discipline the time, the PPS offset is used; otherwise, the
            * argument offset is used.
            */
           if (!(time_status & STA_PLL))
                   return;
           if (!(time_status & STA_PPSTIME && time_status &
               STA_PPSSIGNAL)) {
                   if (offset > MAXPHASE)
                           time_monitor = MAXPHASE;
                   else if (offset < -MAXPHASE)
                           time_monitor = -MAXPHASE;
                   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_second;
                   return;
           }
           if (time_status & STA_FREQHOLD || time_reftime == 0)
                   time_reftime = time_second;
           mtemp = time_second - time_reftime;
           L_LINT(ftemp, time_monitor);
           L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
           L_MPY(ftemp, mtemp);
           L_ADD(time_freq, ftemp);
           time_status &= ~STA_MODE;
           if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
               MAXSEC)) {
                   L_LINT(ftemp, (time_monitor << 4) / mtemp);
                   L_RSHIFT(ftemp, SHIFT_FLL + 4);
                   L_ADD(time_freq, ftemp);
                   time_status |= STA_MODE;
           }
           time_reftime = time_second;
           if (L_GINT(time_freq) > MAXFREQ)
                   L_LINT(time_freq, MAXFREQ);
           else if (L_GINT(time_freq) < -MAXFREQ)
                   L_LINT(time_freq, -MAXFREQ);
   }
   
   #ifdef PPS_SYNC
   /*
    * hardpps() - discipline CPU clock oscillator to external PPS signal
    *
    * This routine is called at each PPS interrupt in order to discipline
    * the CPU clock oscillator to the PPS signal. It measures the PPS phase
    * and leaves it in a handy spot for the hardclock() routine. It
    * integrates successive PPS phase differences and calculates the
    * frequency offset. This is used in hardclock() to discipline the CPU
    * clock oscillator so that intrinsic frequency error is cancelled out.
    * The code requires the caller to capture the time and hardware counter
    * value 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 certain exceptions: The PPS frequency pps_freq
    * and phase pps_offset variables are determined by this routine and
    * updated atomically. The time_tolerance variable can be considered a
    * constant, since it is infrequently changed, and then only when the
    * PPS signal is disabled. The watchdog counter pps_valid is updated
    * once per second by hardclock() and is atomically cleared in this
    * routine.
    */
   void
   hardpps(struct timespec *tsp,           /* time at PPS */
           long nsec                       /* hardware counter at PPS */)
   {
           long u_sec, u_nsec, v_nsec; /* temps */
           l_fp ftemp;
   
           /*
            * The signal is first processed by a range gate and frequency
            * discriminator. The range gate rejects noise spikes outside
            * the range +-500 us. The frequency discriminator rejects input
            * signals with apparent frequency outside the range 1 +-500
            * PPM. If two hits occur in the same second, we ignore the
            * later hit; if not and a hit occurs outside the range gate,
            * keep the later hit for later comparison, but do not process
            * it.
            */
           time_status |= STA_PPSSIGNAL | STA_PPSJITTER;
           time_status &= ~(STA_PPSWANDER | STA_PPSERROR);
           pps_valid = PPS_VALID;
           u_sec = tsp->tv_sec;
           u_nsec = tsp->tv_nsec;
           if (u_nsec >= (NANOSECOND >> 1)) {
                   u_nsec -= NANOSECOND;
                   u_sec++;
           }
           v_nsec = u_nsec - pps_tf[0].tv_nsec;
           if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND -
               MAXFREQ)
                   return;
           pps_tf[2] = pps_tf[1];
           pps_tf[1] = pps_tf[0];
           pps_tf[0].tv_sec = u_sec;
           pps_tf[0].tv_nsec = u_nsec;
   
           /*
            * Compute the difference between the current and previous
            * counter values. If the difference exceeds 0.5 s, assume it
            * has wrapped around, so correct 1.0 s. If the result exceeds
            * the tick interval, the sample point has crossed a tick
            * boundary during the last second, so correct the tick. Very
            * intricate.
            */
           u_nsec = nsec;
           if (u_nsec > (NANOSECOND >> 1))
                   u_nsec -= NANOSECOND;
           else if (u_nsec < -(NANOSECOND >> 1))
                   u_nsec += NANOSECOND;
           pps_fcount += u_nsec;
           if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
                   return;
           time_status &= ~STA_PPSJITTER;
   
           /*
            * A three-stage median filter is used to help denoise the PPS
            * time. The median sample becomes the time offset estimate; the
            * difference between the other two samples becomes the time
            * dispersion (jitter) estimate.
            */
           if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {
                   if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {
                           v_nsec = pps_tf[1].tv_nsec;     /* 0 1 2 */
                           u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;
                   } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {
                           v_nsec = pps_tf[0].tv_nsec;     /* 2 0 1 */
                           u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;
                   } else {
                           v_nsec = pps_tf[2].tv_nsec;     /* 0 2 1 */
                           u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;
                   }
           } else {
                   if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {
                           v_nsec = pps_tf[1].tv_nsec;     /* 2 1 0 */
                           u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;
                   } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {
                           v_nsec = pps_tf[0].tv_nsec;     /* 1 0 2 */
                           u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;
                   } else {
                           v_nsec = pps_tf[2].tv_nsec;     /* 1 2 0 */
                           u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;
                   }
           }
   
           /*
            * Nominal jitter is due to PPS signal noise and interrupt
            * latency. If it exceeds the popcorn threshold, the sample is
            * discarded. otherwise, if so enabled, the time offset is
            * updated. We can tolerate a modest loss of data here without
            * much degrading time accuracy.
            */
           if (u_nsec > (pps_jitter << PPS_POPCORN)) {
                   time_status |= STA_PPSJITTER;
                   pps_jitcnt++;
           } else if (time_status & STA_PPSTIME) {
                   time_monitor = -v_nsec;
                   L_LINT(time_offset, time_monitor);
           }
           pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;
           u_sec = pps_tf[0].tv_sec - pps_lastsec;
           if (u_sec < (1 << pps_shift))
                   return;
   
           /*
            * At the end of the calibration interval the difference between
            * the first and last counter values becomes the scaled
            * frequency. It will later be divided by the length of the
            * interval to determine the frequency update. If the frequency
            * exceeds a sanity threshold, or if the actual calibration
            * interval is not equal to the expected length, the data are
            * discarded. We can tolerate a modest loss of data here without
            * much degrading frequency accuracy.
            */
           pps_calcnt++;
           v_nsec = -pps_fcount;
           pps_lastsec = pps_tf[0].tv_sec;
           pps_fcount = 0;
           u_nsec = MAXFREQ << pps_shift;
           if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 <<
               pps_shift)) {
                   time_status |= STA_PPSERROR;
                   pps_errcnt++;
                   return;
           }
   
           /*
            * Here the raw frequency offset and wander (stability) is
            * calculated. If the wander is less than the wander threshold
            * for four consecutive averaging intervals, the interval is
            * doubled; if it is greater than the threshold for four
            * consecutive intervals, the interval is halved. The scaled
            * frequency offset is converted to frequency offset. The
            * stability metric is calculated as the average of recent
            * frequency changes, but is used only for performance
            * monitoring.
            */
           L_LINT(ftemp, v_nsec);
           L_RSHIFT(ftemp, pps_shift);
           L_SUB(ftemp, pps_freq);
           u_nsec = L_GINT(ftemp);
           if (u_nsec > PPS_MAXWANDER) {
                   L_LINT(ftemp, PPS_MAXWANDER);
                   pps_intcnt--;
                   time_status |= STA_PPSWANDER;
                   pps_stbcnt++;
           } else if (u_nsec < -PPS_MAXWANDER) {
                   L_LINT(ftemp, -PPS_MAXWANDER);
                   pps_intcnt--;
                   time_status |= STA_PPSWANDER;
                   pps_stbcnt++;
           } else {
                   pps_intcnt++;
           }
           if (pps_intcnt >= 4) {
                   pps_intcnt = 4;
                   if (pps_shift < pps_shiftmax) {
                           pps_shift++;
                           pps_intcnt = 0;
                   }
           } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {
                   pps_intcnt = -4;
                   if (pps_shift > PPS_FAVG) {
                           pps_shift--;
                           pps_intcnt = 0;
                   }
           }
           if (u_nsec < 0)
                   u_nsec = -u_nsec;
           pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;
   
           /*
            * The PPS frequency is recalculated and clamped to the maximum
            * MAXFREQ. If enabled, the system clock frequency is updated as
            * well.
            */
           L_ADD(pps_freq, ftemp);
           u_nsec = L_GINT(pps_freq);
           if (u_nsec > MAXFREQ)
                   L_LINT(pps_freq, MAXFREQ);
           else if (u_nsec < -MAXFREQ)
                   L_LINT(pps_freq, -MAXFREQ);
           if (time_status & STA_PPSFREQ)
                   time_freq = pps_freq;
   }
   #endif /* PPS_SYNC */
   #endif /* NTP */
   #else /* !__HAVE_TIMECOUNTER */
   /******************************************************************************
    *                                                                            *
    * Copyright (c) David L. Mills 1993, 1994                                    *
    *                                                                            *
    * 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.      *
    *                                                                            *
    ******************************************************************************/
   
   /*
    * Modification history kern_ntptime.c
    *
    * 24 Sep 94    David L. Mills
    *      Tightened code at exits.
    *
    * 24 Mar 94    David L. Mills
    *      Revised syscall interface to include new variables for PPS
    *      time discipline.
    *
    * 14 Feb 94    David L. Mills
    *      Added code for external clock
    *
    * 28 Nov 93    David L. Mills
    *      Revised frequency scaling to conform with adjusted parameters
    *
    * 17 Sep 93    David L. Mills
    *      Created file
    */
   /*
    * ntp_gettime(), ntp_adjtime() - precision time interface for SunOS
    * V4.1.1 and V4.1.3
    *
    * These routines consitute 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 hardclock() to adjust the phase and
    * frequency of the phase-lock loop which controls the system clock.
    */
   
   #include <sys/cdefs.h>
   __KERNEL_RCSID(0, "$NetBSD: kern_ntptime.c,v 1.41 2006/11/01 10:17:58 yamt Exp $");
   
   #include "opt_ntp.h"
   #include "opt_compat_netbsd.h"
   
   #include <sys/param.h>
   #include <sys/resourcevar.h>
   #include <sys/systm.h>
   #include <sys/kernel.h>
   #include <sys/proc.h>
   #include <sys/sysctl.h>
   #include <sys/timex.h>
   #ifdef COMPAT_30
   #include <compat/sys/timex.h>
   #endif
   #include <sys/vnode.h>
   #include <sys/kauth.h>
   
   #include <sys/mount.h>
   #include <sys/sa.h>
   #include <sys/syscallargs.h>
   
   #include <machine/cpu.h>
   
   #ifdef NTP
   /*
    * The following variables are used by the hardclock() routine in the
    * kern_clock.c module and are described in that module.
    */
   extern int time_state;          /* clock state */
   extern int time_status;         /* clock status bits */
   extern long time_offset;        /* time adjustment (us) */
   extern long time_freq;          /* frequency offset (scaled ppm) */
   extern long time_maxerror;      /* maximum error (us) */
   extern long time_esterror;      /* estimated error (us) */
   extern long time_constant;      /* pll time constant */
   extern long time_precision;     /* clock precision (us) */
   extern long time_tolerance;     /* frequency tolerance (scaled ppm) */
   extern int time_adjusted;       /* ntp might have changed the system time */
   
   #ifdef PPS_SYNC
   /*
    * The following variables are used only if the PPS signal discipline
    * is configured in the kernel.
    */
   extern int pps_shift;           /* interval duration (s) (shift) */
   extern long pps_freq;           /* pps frequency offset (scaled ppm) */
   extern long pps_jitter;         /* pps jitter (us) */
   extern long pps_stabil;         /* pps stability (scaled ppm) */
   extern long pps_jitcnt;         /* jitter limit exceeded */
   extern long pps_calcnt;         /* calibration intervals */
   extern long pps_errcnt;         /* calibration errors */
   extern long pps_stbcnt;         /* stability limit exceeded */
   #endif /* PPS_SYNC */
   
   /*ARGSUSED*/
   /*
    * ntp_gettime() - NTP user application interface
    */
   void
   ntp_gettime(ntvp)
           struct ntptimeval *ntvp;
   {
           struct timeval atv;
           int s;
   
           memset(ntvp, 0, sizeof(struct ntptimeval));
   
           s = splclock();
   #ifdef EXT_CLOCK
           /*
            * The microtime() external clock routine returns a
            * status code. If less than zero, we declare an error
            * in the clock status word and return the kernel
            * (software) time variable. While there are other
            * places that call microtime(), this is the only place
            * that matters from an application point of view.
            */
           if (microtime(&atv) < 0) {
                   time_status |= STA_CLOCKERR;
                   ntvp->time = time;
           } else
                   time_status &= ~STA_CLOCKERR;
   #else /* EXT_CLOCK */
           microtime(&atv);
   #endif /* EXT_CLOCK */
           ntvp->maxerror = time_maxerror;
           ntvp->esterror = time_esterror;
           (void) splx(s);
           TIMEVAL_TO_TIMESPEC(&atv, &ntvp->time);
   }
    
   
  /* ARGSUSED */
  /*
   * ntp_adjtime() - NTP daemon application interface
   */
  int
  sys_ntp_adjtime(l, v, retval)
          struct lwp *l;
          void *v;
          register_t *retval;
  {
          struct sys_ntp_adjtime_args /* {
                  syscallarg(struct timex *) tp;
          } */ *uap = v;
          struct timex ntv;
          int error = 0;
  
          error = copyin((caddr_t)SCARG(uap, tp), (caddr_t)&ntv, sizeof(ntv));
          if (error != 0)
                  return (error);
  
          if (ntv.modes != 0 && (error = kauth_authorize_system(l->l_cred,
              KAUTH_SYSTEM_TIME, KAUTH_REQ_SYSTEM_TIME_NTPADJTIME, NULL,
              NULL, NULL)) != 0)
                  return (error);
  
          ntp_adjtime1(&ntv);
  
          error = copyout((caddr_t)&ntv, (caddr_t)SCARG(uap, tp), sizeof(ntv));
          if (error == 0)
                  *retval = ntp_timestatus();
  
          return error;
  }
  
  void
  ntp_adjtime1(ntv)
          struct timex *ntv;
  {
          int modes;
          int s;
  
          /*
           * Update selected clock variables. Note that there is no error
           * checking here on the assumption the superuser should know
           * what it is doing.
           */
          modes = ntv->modes;
          if (modes != 0)
                  /* We need to save the system time during shutdown */
                  time_adjusted |= 2;
          s = splclock();
          if (modes & MOD_FREQUENCY)
  #ifdef PPS_SYNC
                  time_freq = ntv->freq - pps_freq;
  #else /* PPS_SYNC */
                  time_freq = ntv->freq;
  #endif /* PPS_SYNC */
          if (modes & MOD_MAXERROR)
                  time_maxerror = ntv->maxerror;
          if (modes & MOD_ESTERROR)
                  time_esterror = ntv->esterror;
          if (modes & MOD_STATUS) {
                  time_status &= STA_RONLY;
                  time_status |= ntv->status & ~STA_RONLY;
          }
          if (modes & MOD_TIMECONST)
                  time_constant = ntv->constant;
          if (modes & MOD_OFFSET)
                  hardupdate(ntv->offset);
  
          /*
           * Retrieve all clock variables
           */
          if (time_offset < 0)
                  ntv->offset = -(-time_offset >> SHIFT_UPDATE);
          else
                  ntv->offset = time_offset >> SHIFT_UPDATE;
  #ifdef PPS_SYNC
          ntv->freq = time_freq + pps_freq;
  #else /* PPS_SYNC */
          ntv->freq = time_freq;
  #endif /* PPS_SYNC */
          ntv->maxerror = time_maxerror;
          ntv->esterror = time_esterror;
          ntv->status = time_status;
          ntv->constant = time_constant;
          ntv->precision = time_precision;
          ntv->tolerance = time_tolerance;
  #ifdef PPS_SYNC
          ntv->shift = pps_shift;
          ntv->ppsfreq = pps_freq;
          ntv->jitter = pps_jitter >> PPS_AVG;
          ntv->stabil = pps_stabil;
          ntv->calcnt = pps_calcnt;
          ntv->errcnt = pps_errcnt;
          ntv->jitcnt = pps_jitcnt;
          ntv->stbcnt = pps_stbcnt;
  #endif /* PPS_SYNC */
          (void)splx(s);
  }
  #endif /* NTP */
  #endif /* !__HAVE_TIMECOUNTER */
  
  #ifdef NTP
  int
  ntp_timestatus()
  {
          /*
           * Status word error decode. If any of these conditions
           * occur, an error is returned, instead of the status
           * word. Most applications will care only about the fact
           * the system clock may not be trusted, not about the
           * details.
           *
           * Hardware or software error
           */
          if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||
  
          /*
           * PPS signal lost when either time or frequency
           * synchronization requested
           */
              (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
               !(time_status & STA_PPSSIGNAL)) ||
  
          /*
           * PPS jitter exceeded when time synchronization
           * requested
           */
              (time_status & STA_PPSTIME &&
               time_status & STA_PPSJITTER) ||
  
          /*
           * PPS wander exceeded or calibration error when
           * frequency synchronization requested
           */
              (time_status & STA_PPSFREQ &&
               time_status & (STA_PPSWANDER | STA_PPSERROR)))
                  return (TIME_ERROR);
          else
                  return (time_state);
  }
  
  /*ARGSUSED*/
  /*
   * ntp_gettime() - NTP user application interface
   */
  int
  sys___ntp_gettime30(struct lwp *l, void *v, register_t *retval)
  {
          struct sys___ntp_gettime30_args /* {
                  syscallarg(struct ntptimeval *) ntvp;
          } */ *uap = v;
          struct ntptimeval ntv;
          int error = 0;
  
          if (SCARG(uap, ntvp)) {
                  ntp_gettime(&ntv);
  
                  error = copyout((caddr_t)&ntv, (caddr_t)SCARG(uap, ntvp),
                                  sizeof(ntv));
          }
          if (!error) {
                  *retval = ntp_timestatus();
          }
          return(error);
  }
  
  #ifdef COMPAT_30
  int
  compat_30_sys_ntp_gettime(struct lwp *l, void *v, register_t *retval)
  {
          struct compat_30_sys_ntp_gettime_args /* {
                  syscallarg(struct ntptimeval30 *) ontvp;
          } */ *uap = v;
          struct ntptimeval ntv;
          struct ntptimeval30 ontv;
          int error = 0;
  
          if (SCARG(uap, ntvp)) {
                  ntp_gettime(&ntv);
                  TIMESPEC_TO_TIMEVAL(&ontv.time, &ntv.time);
                  ontv.maxerror = ntv.maxerror;
                  ontv.esterror = ntv.esterror;
  
                  error = copyout((caddr_t)&ontv, (caddr_t)SCARG(uap, ntvp),
                                  sizeof(ontv));
          }
          if (!error)
                  *retval = ntp_timestatus();
  
          return (error);
  }
  #endif
  
  /*
   * return information about kernel precision timekeeping
   */
  static int
  sysctl_kern_ntptime(SYSCTLFN_ARGS)
  {
          struct sysctlnode node;
          struct ntptimeval ntv;
  
          ntp_gettime(&ntv);
  
          node = *rnode;
          node.sysctl_data = &ntv;
          node.sysctl_size = sizeof(ntv);
          return (sysctl_lookup(SYSCTLFN_CALL(&node)));
  }
  
  SYSCTL_SETUP(sysctl_kern_ntptime_setup, "sysctl kern.ntptime node setup")
  {
  
          sysctl_createv(clog, 0, NULL, NULL,
                         CTLFLAG_PERMANENT,
                         CTLTYPE_NODE, "kern", NULL,
                         NULL, 0, NULL, 0,
                         CTL_KERN, CTL_EOL);
  
          sysctl_createv(clog, 0, NULL, NULL,
                         CTLFLAG_PERMANENT,
                         CTLTYPE_STRUCT, "ntptime",
                         SYSCTL_DESCR("Kernel clock values for NTP"),
                         sysctl_kern_ntptime, 0, NULL,
                         sizeof(struct ntptimeval),
                         CTL_KERN, KERN_NTPTIME, CTL_EOL);
  }
  #else /* !NTP */
  /* For some reason, raising SIGSYS (as sys_nosys would) is problematic. */
  
  int
  sys___ntp_gettime30(struct lwp *l, void *v, register_t *retval)
  {
  
          return(ENOSYS);
  }
  
  #ifdef COMPAT_30
  int
  compat_30_sys_ntp_gettime(struct lwp *l, void *v, register_t *retval)
  {
  
          return(ENOSYS);
  }
  #endif
  #endif /* !NTP */

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