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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * NTP state machine interfaces and logic.
  *
  * This code was mainly moved from kernel/timer.c and kernel/time.c
  * Please see those files for relevant copyright info and historical
  * changelogs.
  */
 #include <linux/capability.h>
 #include <linux/clocksource.h>
 #include <linux/workqueue.h>
 #include <linux/hrtimer.h>
 #include <linux/jiffies.h>
 #include <linux/math64.h>
 #include <linux/timex.h>
 #include <linux/time.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/rtc.h>
 #include <linux/audit.h>
 
 #include "ntp_internal.h"
 #include "timekeeping_internal.h"
 
 
 /*
  * NTP timekeeping variables:
  *
  * Note: All of the NTP state is protected by the timekeeping locks.
  */
 
 
 /* USER_HZ period (usecs): */
 unsigned long           tick_usec = USER_TICK_USEC;
 
 /* SHIFTED_HZ period (nsecs): */
 unsigned long           tick_nsec;
 
 static u64          tick_length;
 static u64          tick_length_base;
 
 #define SECS_PER_DAY        86400
 #define MAX_TICKADJ     500LL       /* usecs */
 #define MAX_TICKADJ_SCALED \
     (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
 #define MAX_TAI_OFFSET      100000
 
 /*
  * phase-lock loop variables
  */
 
 /*
  * clock synchronization status
  *
  * (TIME_ERROR prevents overwriting the CMOS clock)
  */
 static int          time_state = TIME_OK;
 
 /* clock status bits:                           */
 static int          time_status = STA_UNSYNC;
 
 /* time adjustment (nsecs):                     */
 static s64          time_offset;
 
 /* pll time constant:                           */
 static long         time_constant = 2;
 
 /* maximum error (usecs):                       */
 static long         time_maxerror = NTP_PHASE_LIMIT;
 
 /* estimated error (usecs):                     */
 static long         time_esterror = NTP_PHASE_LIMIT;
 
 /* frequency offset (scaled nsecs/secs):                */
 static s64          time_freq;
 
 /* time at last adjustment (secs):                  */
 static time64_t     time_reftime;
 
 static long         time_adjust;
 
 /* constant (boot-param configurable) NTP tick adjustment (upscaled)    */
 static s64          ntp_tick_adj;
 
 /* second value of the next pending leapsecond, or TIME64_MAX if no leap */
 static time64_t         ntp_next_leap_sec = TIME64_MAX;
 
 #ifdef CONFIG_NTP_PPS
 
 /*
  * The following variables are used when a pulse-per-second (PPS) signal
  * is available. They establish the engineering parameters of the clock
  * discipline loop when controlled by the PPS signal.
  */
 #define PPS_VALID   10  /* PPS signal watchdog max (s) */
 #define PPS_POPCORN 4   /* popcorn spike threshold (shift) */
 #define PPS_INTMIN  2   /* min freq interval (s) (shift) */
 #define PPS_INTMAX  8   /* max freq interval (s) (shift) */
 #define PPS_INTCOUNT    4   /* number of consecutive good intervals to
                    increase pps_shift or consecutive bad
                    intervals to decrease it */
 #define PPS_MAXWANDER   100000  /* max PPS freq wander (ns/s) */
 
 static int pps_valid;       /* signal watchdog counter */
 static long pps_tf[3];      /* phase median filter */
 static long pps_jitter;     /* current jitter (ns) */
 static struct timespec64 pps_fbase; /* beginning of the last freq interval */
 static int pps_shift;       /* current interval duration (s) (shift) */
 static int pps_intcnt;      /* interval counter */
 static s64 pps_freq;        /* frequency offset (scaled ns/s) */
 static long pps_stabil;     /* current stability (scaled ns/s) */
 
 /*
  * 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 */
 
 
 /* PPS kernel consumer compensates the whole phase error immediately.
  * Otherwise, reduce the offset by a fixed factor times the time constant.
  */
 static inline s64 ntp_offset_chunk(s64 offset)
 {
     if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL)
         return offset;
     else
         return shift_right(offset, SHIFT_PLL + time_constant);
 }
 
 static inline void pps_reset_freq_interval(void)
 {
     /* the PPS calibration interval may end
        surprisingly early */
     pps_shift = PPS_INTMIN;
     pps_intcnt = 0;
 }
 
 /**
  * pps_clear - Clears the PPS state variables
  */
 static inline void pps_clear(void)
 {
     pps_reset_freq_interval();
     pps_tf[0] = 0;
     pps_tf[1] = 0;
     pps_tf[2] = 0;
     pps_fbase.tv_sec = pps_fbase.tv_nsec = 0;
     pps_freq = 0;
 }
 
 /* Decrease pps_valid to indicate that another second has passed since
  * the last PPS signal. When it reaches 0, indicate that PPS signal is
  * missing.
  */
 static inline void pps_dec_valid(void)
 {
     if (pps_valid > 0)
         pps_valid--;
     else {
         time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
                  STA_PPSWANDER | STA_PPSERROR);
         pps_clear();
     }
 }
 
 static inline void pps_set_freq(s64 freq)
 {
     pps_freq = freq;
 }
 
 static inline int is_error_status(int status)
 {
     return (status & (STA_UNSYNC|STA_CLOCKERR))
         /* PPS signal lost when either PPS time or
          * PPS frequency synchronization requested
          */
         || ((status & (STA_PPSFREQ|STA_PPSTIME))
             && !(status & STA_PPSSIGNAL))
         /* PPS jitter exceeded when
          * PPS time synchronization requested */
         || ((status & (STA_PPSTIME|STA_PPSJITTER))
             == (STA_PPSTIME|STA_PPSJITTER))
         /* PPS wander exceeded or calibration error when
          * PPS frequency synchronization requested
          */
         || ((status & STA_PPSFREQ)
             && (status & (STA_PPSWANDER|STA_PPSERROR)));
 }
 
 static inline void pps_fill_timex(struct __kernel_timex *txc)
 {
     txc->ppsfreq       = shift_right((pps_freq >> PPM_SCALE_INV_SHIFT) *
                      PPM_SCALE_INV, NTP_SCALE_SHIFT);
     txc->jitter    = pps_jitter;
     if (!(time_status & STA_NANO))
         txc->jitter = pps_jitter / NSEC_PER_USEC;
     txc->shift     = pps_shift;
     txc->stabil    = pps_stabil;
     txc->jitcnt    = pps_jitcnt;
     txc->calcnt    = pps_calcnt;
     txc->errcnt    = pps_errcnt;
     txc->stbcnt    = pps_stbcnt;
 }
 
 #else /* !CONFIG_NTP_PPS */
 
 static inline s64 ntp_offset_chunk(s64 offset)
 {
     return shift_right(offset, SHIFT_PLL + time_constant);
 }
 
 static inline void pps_reset_freq_interval(void) {}
 static inline void pps_clear(void) {}
 static inline void pps_dec_valid(void) {}
 static inline void pps_set_freq(s64 freq) {}
 
 static inline int is_error_status(int status)
 {
     return status & (STA_UNSYNC|STA_CLOCKERR);
 }
 
 static inline void pps_fill_timex(struct __kernel_timex *txc)
 {
     /* PPS is not implemented, so these are zero */
     txc->ppsfreq       = 0;
     txc->jitter    = 0;
     txc->shift     = 0;
     txc->stabil    = 0;
     txc->jitcnt    = 0;
     txc->calcnt    = 0;
     txc->errcnt    = 0;
     txc->stbcnt    = 0;
 }
 
 #endif /* CONFIG_NTP_PPS */
 
 
 /**
  * ntp_synced - Returns 1 if the NTP status is not UNSYNC
  *
  */
 static inline int ntp_synced(void)
 {
     return !(time_status & STA_UNSYNC);
 }
 
 
 /*
  * NTP methods:
  */
 
 /*
  * Update (tick_length, tick_length_base, tick_nsec), based
  * on (tick_usec, ntp_tick_adj, time_freq):
  */
 static void ntp_update_frequency(void)
 {
     u64 second_length;
     u64 new_base;
 
     second_length        = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
                         << NTP_SCALE_SHIFT;
 
     second_length       += ntp_tick_adj;
     second_length       += time_freq;
 
     tick_nsec        = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT;
     new_base         = div_u64(second_length, NTP_INTERVAL_FREQ);
 
     /*
      * Don't wait for the next second_overflow, apply
      * the change to the tick length immediately:
      */
     tick_length     += new_base - tick_length_base;
     tick_length_base     = new_base;
 }
 
 static inline s64 ntp_update_offset_fll(s64 offset64, long secs)
 {
     time_status &= ~STA_MODE;
 
     if (secs < MINSEC)
         return 0;
 
     if (!(time_status & STA_FLL) && (secs <= MAXSEC))
         return 0;
 
     time_status |= STA_MODE;
 
     return div64_long(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
 }
 
 static void ntp_update_offset(long offset)
 {
     s64 freq_adj;
     s64 offset64;
     long secs;
 
     if (!(time_status & STA_PLL))
         return;
 
     if (!(time_status & STA_NANO)) {
         /* Make sure the multiplication below won't overflow */
         offset = clamp(offset, -USEC_PER_SEC, USEC_PER_SEC);
         offset *= NSEC_PER_USEC;
     }
 
     /*
      * Scale the phase adjustment and
      * clamp to the operating range.
      */
     offset = clamp(offset, -MAXPHASE, MAXPHASE);
 
     /*
      * Select how the frequency is to be controlled
      * and in which mode (PLL or FLL).
      */
     secs = (long)(__ktime_get_real_seconds() - time_reftime);
     if (unlikely(time_status & STA_FREQHOLD))
         secs = 0;
 
     time_reftime = __ktime_get_real_seconds();
 
     offset64    = offset;
     freq_adj    = ntp_update_offset_fll(offset64, secs);
 
     /*
      * Clamp update interval to reduce PLL gain with low
      * sampling rate (e.g. intermittent network connection)
      * to avoid instability.
      */
     if (unlikely(secs > 1 << (SHIFT_PLL + 1 + time_constant)))
         secs = 1 << (SHIFT_PLL + 1 + time_constant);
 
     freq_adj    += (offset64 * secs) <<
             (NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant));
 
     freq_adj    = min(freq_adj + time_freq, MAXFREQ_SCALED);
 
     time_freq   = max(freq_adj, -MAXFREQ_SCALED);
 
     time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
 }
 
 /**
  * ntp_clear - Clears the NTP state variables
  */
 void ntp_clear(void)
 {
     time_adjust = 0;        /* stop active adjtime() */
     time_status |= STA_UNSYNC;
     time_maxerror   = NTP_PHASE_LIMIT;
     time_esterror   = NTP_PHASE_LIMIT;
 
     ntp_update_frequency();
 
     tick_length = tick_length_base;
     time_offset = 0;
 
     ntp_next_leap_sec = TIME64_MAX;
     /* Clear PPS state variables */
     pps_clear();
 }
 
 
 u64 ntp_tick_length(void)
 {
     return tick_length;
 }
 
 /**
  * ntp_get_next_leap - Returns the next leapsecond in CLOCK_REALTIME ktime_t
  *
  * Provides the time of the next leapsecond against CLOCK_REALTIME in
  * a ktime_t format. Returns KTIME_MAX if no leapsecond is pending.
  */
 ktime_t ntp_get_next_leap(void)
 {
     ktime_t ret;
 
     if ((time_state == TIME_INS) && (time_status & STA_INS))
         return ktime_set(ntp_next_leap_sec, 0);
     ret = KTIME_MAX;
     return ret;
 }
 
 /*
  * this routine handles the overflow of the microsecond field
  *
  * The tricky bits of code to handle the accurate clock support
  * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
  * They were originally developed for SUN and DEC kernels.
  * All the kudos should go to Dave for this stuff.
  *
  * Also handles leap second processing, and returns leap offset
  */
 int second_overflow(time64_t secs)
 {
     s64 delta;
     int leap = 0;
     s32 rem;
 
     /*
      * 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.
      */
     switch (time_state) {
     case TIME_OK:
         if (time_status & STA_INS) {
             time_state = TIME_INS;
             div_s64_rem(secs, SECS_PER_DAY, &rem);
             ntp_next_leap_sec = secs + SECS_PER_DAY - rem;
         } else if (time_status & STA_DEL) {
             time_state = TIME_DEL;
             div_s64_rem(secs + 1, SECS_PER_DAY, &rem);
             ntp_next_leap_sec = secs + SECS_PER_DAY - rem;
         }
         break;
     case TIME_INS:
         if (!(time_status & STA_INS)) {
             ntp_next_leap_sec = TIME64_MAX;
             time_state = TIME_OK;
         } else if (secs == ntp_next_leap_sec) {
             leap = -1;
             time_state = TIME_OOP;
             printk(KERN_NOTICE
                 "Clock: inserting leap second 23:59:60 UTC\n");
         }
         break;
     case TIME_DEL:
         if (!(time_status & STA_DEL)) {
             ntp_next_leap_sec = TIME64_MAX;
             time_state = TIME_OK;
         } else if (secs == ntp_next_leap_sec) {
             leap = 1;
             ntp_next_leap_sec = TIME64_MAX;
             time_state = TIME_WAIT;
             printk(KERN_NOTICE
                 "Clock: deleting leap second 23:59:59 UTC\n");
         }
         break;
     case TIME_OOP:
         ntp_next_leap_sec = TIME64_MAX;
         time_state = TIME_WAIT;
         break;
     case TIME_WAIT:
         if (!(time_status & (STA_INS | STA_DEL)))
             time_state = TIME_OK;
         break;
     }
 
 
     /* Bump the maxerror field */
     time_maxerror += MAXFREQ / NSEC_PER_USEC;
     if (time_maxerror > NTP_PHASE_LIMIT) {
         time_maxerror = NTP_PHASE_LIMIT;
         time_status |= STA_UNSYNC;
     }
 
     /* Compute the phase adjustment for the next second */
     tick_length  = tick_length_base;
 
     delta        = ntp_offset_chunk(time_offset);
     time_offset -= delta;
     tick_length += delta;
 
     /* Check PPS signal */
     pps_dec_valid();
 
     if (!time_adjust)
         goto out;
 
     if (time_adjust > MAX_TICKADJ) {
         time_adjust -= MAX_TICKADJ;
         tick_length += MAX_TICKADJ_SCALED;
         goto out;
     }
 
     if (time_adjust < -MAX_TICKADJ) {
         time_adjust += MAX_TICKADJ;
         tick_length -= MAX_TICKADJ_SCALED;
         goto out;
     }
 
     tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)
                              << NTP_SCALE_SHIFT;
     time_adjust = 0;
 
 out:
     return leap;
 }
 
 #if defined(CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC)
 static void sync_hw_clock(struct work_struct *work);
 static DECLARE_WORK(sync_work, sync_hw_clock);
 static struct hrtimer sync_hrtimer;
 #define SYNC_PERIOD_NS (11ULL * 60 * NSEC_PER_SEC)
 
 static enum hrtimer_restart sync_timer_callback(struct hrtimer *timer)
 {
     queue_work(system_freezable_power_efficient_wq, &sync_work);
 
     return HRTIMER_NORESTART;
 }
 
 static void sched_sync_hw_clock(unsigned long offset_nsec, bool retry)
 {
     ktime_t exp = ktime_set(ktime_get_real_seconds(), 0);
 
     if (retry)
         exp = ktime_add_ns(exp, 2ULL * NSEC_PER_SEC - offset_nsec);
     else
         exp = ktime_add_ns(exp, SYNC_PERIOD_NS - offset_nsec);
 
     hrtimer_start(&sync_hrtimer, exp, HRTIMER_MODE_ABS);
 }
 
 /*
  * Check whether @now is correct versus the required time to update the RTC
  * and calculate the value which needs to be written to the RTC so that the
  * next seconds increment of the RTC after the write is aligned with the next
  * seconds increment of clock REALTIME.
  *
  * tsched     t1 write(t2.tv_sec - 1sec))   t2 RTC increments seconds
  *
  * t2.tv_nsec == 0
  * tsched = t2 - set_offset_nsec
  * newval = t2 - NSEC_PER_SEC
  *
  * ==> neval = tsched + set_offset_nsec - NSEC_PER_SEC
  *
  * As the execution of this code is not guaranteed to happen exactly at
  * tsched this allows it to happen within a fuzzy region:
  *
  *  abs(now - tsched) < FUZZ
  *
  * If @now is not inside the allowed window the function returns false.
  */
 static inline bool rtc_tv_nsec_ok(unsigned long set_offset_nsec,
                   struct timespec64 *to_set,
                   const struct timespec64 *now)
 {
     /* Allowed error in tv_nsec, arbitrarily set to 5 jiffies in ns. */
     const unsigned long TIME_SET_NSEC_FUZZ = TICK_NSEC * 5;
     struct timespec64 delay = {.tv_sec = -1,
                    .tv_nsec = set_offset_nsec};
 
     *to_set = timespec64_add(*now, delay);
 
     if (to_set->tv_nsec < TIME_SET_NSEC_FUZZ) {
         to_set->tv_nsec = 0;
         return true;
     }
 
     if (to_set->tv_nsec > NSEC_PER_SEC - TIME_SET_NSEC_FUZZ) {
         to_set->tv_sec++;
         to_set->tv_nsec = 0;
         return true;
     }
     return false;
 }
 
 #ifdef CONFIG_GENERIC_CMOS_UPDATE
 int __weak update_persistent_clock64(struct timespec64 now64)
 {
     return -ENODEV;
 }
 #else
 static inline int update_persistent_clock64(struct timespec64 now64)
 {
     return -ENODEV;
 }
 #endif
 
 #ifdef CONFIG_RTC_SYSTOHC
 /* Save NTP synchronized time to the RTC */
 static int update_rtc(struct timespec64 *to_set, unsigned long *offset_nsec)
 {
     struct rtc_device *rtc;
     struct rtc_time tm;
     int err = -ENODEV;
 
     rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE);
     if (!rtc)
         return -ENODEV;
 
     if (!rtc->ops || !rtc->ops->set_time)
         goto out_close;
 
     /* First call might not have the correct offset */
     if (*offset_nsec == rtc->set_offset_nsec) {
         rtc_time64_to_tm(to_set->tv_sec, &tm);
         err = rtc_set_time(rtc, &tm);
     } else {
         /* Store the update offset and let the caller try again */
         *offset_nsec = rtc->set_offset_nsec;
         err = -EAGAIN;
     }
 out_close:
     rtc_class_close(rtc);
     return err;
 }
 #else
 static inline int update_rtc(struct timespec64 *to_set, unsigned long *offset_nsec)
 {
     return -ENODEV;
 }
 #endif
 
 /*
  * If we have an externally synchronized Linux clock, then update RTC clock
  * accordingly every ~11 minutes. Generally RTCs can only store second
  * precision, but many RTCs will adjust the phase of their second tick to
  * match the moment of update. This infrastructure arranges to call to the RTC
  * set at the correct moment to phase synchronize the RTC second tick over
  * with the kernel clock.
  */
 static void sync_hw_clock(struct work_struct *work)
 {
     /*
      * The default synchronization offset is 500ms for the deprecated
      * update_persistent_clock64() under the assumption that it uses
      * the infamous CMOS clock (MC146818).
      */
     static unsigned long offset_nsec = NSEC_PER_SEC / 2;
     struct timespec64 now, to_set;
     int res = -EAGAIN;
 
     /*
      * Don't update if STA_UNSYNC is set and if ntp_notify_cmos_timer()
      * managed to schedule the work between the timer firing and the
      * work being able to rearm the timer. Wait for the timer to expire.
      */
     if (!ntp_synced() || hrtimer_is_queued(&sync_hrtimer))
         return;
 
     ktime_get_real_ts64(&now);
     /* If @now is not in the allowed window, try again */
     if (!rtc_tv_nsec_ok(offset_nsec, &to_set, &now))
         goto rearm;
 
     /* Take timezone adjusted RTCs into account */
     if (persistent_clock_is_local)
         to_set.tv_sec -= (sys_tz.tz_minuteswest * 60);
 
     /* Try the legacy RTC first. */
     res = update_persistent_clock64(to_set);
     if (res != -ENODEV)
         goto rearm;
 
     /* Try the RTC class */
     res = update_rtc(&to_set, &offset_nsec);
     if (res == -ENODEV)
         return;
 rearm:
     sched_sync_hw_clock(offset_nsec, res != 0);
 }
 
 void ntp_notify_cmos_timer(void)
 {
     /*
      * When the work is currently executed but has not yet the timer
      * rearmed this queues the work immediately again. No big issue,
      * just a pointless work scheduled.
      */
     if (ntp_synced() && !hrtimer_is_queued(&sync_hrtimer))
         queue_work(system_freezable_power_efficient_wq, &sync_work);
 }
 
 static void __init ntp_init_cmos_sync(void)
 {
     hrtimer_init(&sync_hrtimer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
     sync_hrtimer.function = sync_timer_callback;
 }
 #else /* CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC) */
 static inline void __init ntp_init_cmos_sync(void) { }
 #endif /* !CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC) */
 
 /*
  * Propagate a new txc->status value into the NTP state:
  */
 static inline void process_adj_status(const struct __kernel_timex *txc)
 {
     if ((time_status & STA_PLL) && !(txc->status & STA_PLL)) {
         time_state = TIME_OK;
         time_status = STA_UNSYNC;
         ntp_next_leap_sec = TIME64_MAX;
         /* restart PPS frequency calibration */
         pps_reset_freq_interval();
     }
 
     /*
      * If we turn on PLL adjustments then reset the
      * reference time to current time.
      */
     if (!(time_status & STA_PLL) && (txc->status & STA_PLL))
         time_reftime = __ktime_get_real_seconds();
 
     /* only set allowed bits */
     time_status &= STA_RONLY;
     time_status |= txc->status & ~STA_RONLY;
 }
 
 
 static inline void process_adjtimex_modes(const struct __kernel_timex *txc,
                       s32 *time_tai)
 {
     if (txc->modes & ADJ_STATUS)
         process_adj_status(txc);
 
     if (txc->modes & ADJ_NANO)
         time_status |= STA_NANO;
 
     if (txc->modes & ADJ_MICRO)
         time_status &= ~STA_NANO;
 
     if (txc->modes & ADJ_FREQUENCY) {
         time_freq = txc->freq * PPM_SCALE;
         time_freq = min(time_freq, MAXFREQ_SCALED);
         time_freq = max(time_freq, -MAXFREQ_SCALED);
         /* update pps_freq */
         pps_set_freq(time_freq);
     }
 
     if (txc->modes & ADJ_MAXERROR)
         time_maxerror = txc->maxerror;
 
     if (txc->modes & ADJ_ESTERROR)
         time_esterror = txc->esterror;
 
     if (txc->modes & ADJ_TIMECONST) {
         time_constant = txc->constant;
         if (!(time_status & STA_NANO))
             time_constant += 4;
         time_constant = min(time_constant, (long)MAXTC);
         time_constant = max(time_constant, 0l);
     }
 
     if (txc->modes & ADJ_TAI &&
             txc->constant >= 0 && txc->constant <= MAX_TAI_OFFSET)
         *time_tai = txc->constant;
 
     if (txc->modes & ADJ_OFFSET)
         ntp_update_offset(txc->offset);
 
     if (txc->modes & ADJ_TICK)
         tick_usec = txc->tick;
 
     if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET))
         ntp_update_frequency();
 }
 
 
 /*
  * adjtimex mainly allows reading (and writing, if superuser) of
  * kernel time-keeping variables. used by xntpd.
  */
 int __do_adjtimex(struct __kernel_timex *txc, const struct timespec64 *ts,
           s32 *time_tai, struct audit_ntp_data *ad)
 {
     int result;
 
     if (txc->modes & ADJ_ADJTIME) {
         long save_adjust = time_adjust;
 
         if (!(txc->modes & ADJ_OFFSET_READONLY)) {
             /* adjtime() is independent from ntp_adjtime() */
             time_adjust = txc->offset;
             ntp_update_frequency();
 
             audit_ntp_set_old(ad, AUDIT_NTP_ADJUST, save_adjust);
             audit_ntp_set_new(ad, AUDIT_NTP_ADJUST, time_adjust);
         }
         txc->offset = save_adjust;
     } else {
         /* If there are input parameters, then process them: */
         if (txc->modes) {
             audit_ntp_set_old(ad, AUDIT_NTP_OFFSET, time_offset);
             audit_ntp_set_old(ad, AUDIT_NTP_FREQ,   time_freq);
             audit_ntp_set_old(ad, AUDIT_NTP_STATUS, time_status);
             audit_ntp_set_old(ad, AUDIT_NTP_TAI,    *time_tai);
             audit_ntp_set_old(ad, AUDIT_NTP_TICK,   tick_usec);
 
             process_adjtimex_modes(txc, time_tai);
 
             audit_ntp_set_new(ad, AUDIT_NTP_OFFSET, time_offset);
             audit_ntp_set_new(ad, AUDIT_NTP_FREQ,   time_freq);
             audit_ntp_set_new(ad, AUDIT_NTP_STATUS, time_status);
             audit_ntp_set_new(ad, AUDIT_NTP_TAI,    *time_tai);
             audit_ntp_set_new(ad, AUDIT_NTP_TICK,   tick_usec);
         }
 
         txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
                   NTP_SCALE_SHIFT);
         if (!(time_status & STA_NANO))
             txc->offset = (u32)txc->offset / NSEC_PER_USEC;
     }
 
     result = time_state;    /* mostly `TIME_OK' */
     /* check for errors */
     if (is_error_status(time_status))
         result = TIME_ERROR;
 
     txc->freq      = shift_right((time_freq >> PPM_SCALE_INV_SHIFT) *
                      PPM_SCALE_INV, NTP_SCALE_SHIFT);
     txc->maxerror      = time_maxerror;
     txc->esterror      = time_esterror;
     txc->status    = time_status;
     txc->constant      = time_constant;
     txc->precision     = 1;
     txc->tolerance     = MAXFREQ_SCALED / PPM_SCALE;
     txc->tick      = tick_usec;
     txc->tai       = *time_tai;
 
     /* fill PPS status fields */
     pps_fill_timex(txc);
 
     txc->time.tv_sec = ts->tv_sec;
     txc->time.tv_usec = ts->tv_nsec;
     if (!(time_status & STA_NANO))
         txc->time.tv_usec = ts->tv_nsec / NSEC_PER_USEC;
 
     /* Handle leapsec adjustments */
     if (unlikely(ts->tv_sec >= ntp_next_leap_sec)) {
         if ((time_state == TIME_INS) && (time_status & STA_INS)) {
             result = TIME_OOP;
             txc->tai++;
             txc->time.tv_sec--;
         }
         if ((time_state == TIME_DEL) && (time_status & STA_DEL)) {
             result = TIME_WAIT;
             txc->tai--;
             txc->time.tv_sec++;
         }
         if ((time_state == TIME_OOP) &&
                     (ts->tv_sec == ntp_next_leap_sec)) {
             result = TIME_WAIT;
         }
     }
 
     return result;
 }
 
 #ifdef  CONFIG_NTP_PPS
 
 /* actually struct pps_normtime is good old struct timespec, but it is
  * semantically different (and it is the reason why it was invented):
  * pps_normtime.nsec has a range of ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ]
  * while timespec.tv_nsec has a range of [0, NSEC_PER_SEC) */
 struct pps_normtime {
     s64     sec;    /* seconds */
     long        nsec;   /* nanoseconds */
 };
 
 /* normalize the timestamp so that nsec is in the
    ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ] interval */
 static inline struct pps_normtime pps_normalize_ts(struct timespec64 ts)
 {
     struct pps_normtime norm = {
         .sec = ts.tv_sec,
         .nsec = ts.tv_nsec
     };
 
     if (norm.nsec > (NSEC_PER_SEC >> 1)) {
         norm.nsec -= NSEC_PER_SEC;
         norm.sec++;
     }
 
     return norm;
 }
 
 /* get current phase correction and jitter */
 static inline long pps_phase_filter_get(long *jitter)
 {
     *jitter = pps_tf[0] - pps_tf[1];
     if (*jitter < 0)
         *jitter = -*jitter;
 
     /* TODO: test various filters */
     return pps_tf[0];
 }
 
 /* add the sample to the phase filter */
 static inline void pps_phase_filter_add(long err)
 {
     pps_tf[2] = pps_tf[1];
     pps_tf[1] = pps_tf[0];
     pps_tf[0] = err;
 }
 
 /* decrease frequency calibration interval length.
  * It is halved after four consecutive unstable intervals.
  */
 static inline void pps_dec_freq_interval(void)
 {
     if (--pps_intcnt <= -PPS_INTCOUNT) {
         pps_intcnt = -PPS_INTCOUNT;
         if (pps_shift > PPS_INTMIN) {
             pps_shift--;
             pps_intcnt = 0;
         }
     }
 }
 
 /* increase frequency calibration interval length.
  * It is doubled after four consecutive stable intervals.
  */
 static inline void pps_inc_freq_interval(void)
 {
     if (++pps_intcnt >= PPS_INTCOUNT) {
         pps_intcnt = PPS_INTCOUNT;
         if (pps_shift < PPS_INTMAX) {
             pps_shift++;
             pps_intcnt = 0;
         }
     }
 }
 
 /* update clock frequency based on MONOTONIC_RAW clock PPS signal
  * timestamps
  *
  * At the end of the calibration interval the difference between the
  * first and last MONOTONIC_RAW clock timestamps divided by the length
  * of the interval becomes the frequency update. If the interval was
  * too long, the data are discarded.
  * Returns the difference between old and new frequency values.
  */
 static long hardpps_update_freq(struct pps_normtime freq_norm)
 {
     long delta, delta_mod;
     s64 ftemp;
 
     /* check if the frequency interval was too long */
     if (freq_norm.sec > (2 << pps_shift)) {
         time_status |= STA_PPSERROR;
         pps_errcnt++;
         pps_dec_freq_interval();
         printk_deferred(KERN_ERR
             "hardpps: PPSERROR: interval too long - %lld s\n",
             freq_norm.sec);
         return 0;
     }
 
     /* here the raw frequency offset and wander (stability) is
      * calculated. If the wander is less than the wander threshold
      * the interval is increased; otherwise it is decreased.
      */
     ftemp = div_s64(((s64)(-freq_norm.nsec)) << NTP_SCALE_SHIFT,
             freq_norm.sec);
     delta = shift_right(ftemp - pps_freq, NTP_SCALE_SHIFT);
     pps_freq = ftemp;
     if (delta > PPS_MAXWANDER || delta < -PPS_MAXWANDER) {
         printk_deferred(KERN_WARNING
                 "hardpps: PPSWANDER: change=%ld\n", delta);
         time_status |= STA_PPSWANDER;
         pps_stbcnt++;
         pps_dec_freq_interval();
     } else {    /* good sample */
         pps_inc_freq_interval();
     }
 
     /* the stability metric is calculated as the average of recent
      * frequency changes, but is used only for performance
      * monitoring
      */
     delta_mod = delta;
     if (delta_mod < 0)
         delta_mod = -delta_mod;
     pps_stabil += (div_s64(((s64)delta_mod) <<
                 (NTP_SCALE_SHIFT - SHIFT_USEC),
                 NSEC_PER_USEC) - pps_stabil) >> PPS_INTMIN;
 
     /* if enabled, the system clock frequency is updated */
     if ((time_status & STA_PPSFREQ) != 0 &&
         (time_status & STA_FREQHOLD) == 0) {
         time_freq = pps_freq;
         ntp_update_frequency();
     }
 
     return delta;
 }
 
 /* correct REALTIME clock phase error against PPS signal */
 static void hardpps_update_phase(long error)
 {
     long correction = -error;
     long jitter;
 
     /* add the sample to the median filter */
     pps_phase_filter_add(correction);
     correction = pps_phase_filter_get(&jitter);
 
     /* Nominal jitter is due to PPS signal noise. If it exceeds the
      * threshold, the sample is discarded; otherwise, if so enabled,
      * the time offset is updated.
      */
     if (jitter > (pps_jitter << PPS_POPCORN)) {
         printk_deferred(KERN_WARNING
                 "hardpps: PPSJITTER: jitter=%ld, limit=%ld\n",
                 jitter, (pps_jitter << PPS_POPCORN));
         time_status |= STA_PPSJITTER;
         pps_jitcnt++;
     } else if (time_status & STA_PPSTIME) {
         /* correct the time using the phase offset */
         time_offset = div_s64(((s64)correction) << NTP_SCALE_SHIFT,
                 NTP_INTERVAL_FREQ);
         /* cancel running adjtime() */
         time_adjust = 0;
     }
     /* update jitter */
     pps_jitter += (jitter - pps_jitter) >> PPS_INTMIN;
 }
 
 /*
  * __hardpps() - discipline CPU clock oscillator to external PPS signal
  *
  * This routine is called at each PPS signal arrival in order to
  * discipline the CPU clock oscillator to the PPS signal. It takes two
  * parameters: REALTIME and MONOTONIC_RAW clock timestamps. The former
  * is used to correct clock phase error and the latter is used to
  * correct the frequency.
  *
  * This code is based on David Mills's reference nanokernel
  * implementation. It was mostly rewritten but keeps the same idea.
  */
 void __hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
 {
     struct pps_normtime pts_norm, freq_norm;
 
     pts_norm = pps_normalize_ts(*phase_ts);
 
     /* clear the error bits, they will be set again if needed */
     time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
 
     /* indicate signal presence */
     time_status |= STA_PPSSIGNAL;
     pps_valid = PPS_VALID;
 
     /* when called for the first time,
      * just start the frequency interval */
     if (unlikely(pps_fbase.tv_sec == 0)) {
         pps_fbase = *raw_ts;
         return;
     }
 
     /* ok, now we have a base for frequency calculation */
     freq_norm = pps_normalize_ts(timespec64_sub(*raw_ts, pps_fbase));
 
     /* check that the signal is in the range
      * [1s - MAXFREQ us, 1s + MAXFREQ us], otherwise reject it */
     if ((freq_norm.sec == 0) ||
             (freq_norm.nsec > MAXFREQ * freq_norm.sec) ||
             (freq_norm.nsec < -MAXFREQ * freq_norm.sec)) {
         time_status |= STA_PPSJITTER;
         /* restart the frequency calibration interval */
         pps_fbase = *raw_ts;
         printk_deferred(KERN_ERR "hardpps: PPSJITTER: bad pulse\n");
         return;
     }
 
     /* signal is ok */
 
     /* check if the current frequency interval is finished */
     if (freq_norm.sec >= (1 << pps_shift)) {
         pps_calcnt++;
         /* restart the frequency calibration interval */
         pps_fbase = *raw_ts;
         hardpps_update_freq(freq_norm);
     }
 
     hardpps_update_phase(pts_norm.nsec);
 
 }
 #endif  /* CONFIG_NTP_PPS */
 
 static int __init ntp_tick_adj_setup(char *str)
 {
     int rc = kstrtos64(str, 0, &ntp_tick_adj);
     if (rc)
         return rc;
 
     ntp_tick_adj <<= NTP_SCALE_SHIFT;
     return 1;
 }
 
 __setup("ntp_tick_adj=", ntp_tick_adj_setup);
 
 void __init ntp_init(void)
 {
     ntp_clear();
     ntp_init_cmos_sync();
 }

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