kernel/time.c - pub/scm/linux/kernel/git/joro/linux - Git at Google

 /*
  *  linux/kernel/time.c
  *
  *  Copyright (C) 1991, 1992  Linus Torvalds
  *
  *  This file contains the interface functions for the various
  *  time related system calls: time, stime, gettimeofday, settimeofday,
  *			       adjtime
  */
 /*
  * Modification history kernel/time.c
  *
  * 1993-09-02    Philip Gladstone
  *      Created file with time related functions from sched.c and adjtimex()
  * 1993-10-08    Torsten Duwe
  *      adjtime interface update and CMOS clock write code
  * 1995-08-13    Torsten Duwe
  *      kernel PLL updated to 1994-12-13 specs (rfc-1589)
  * 1999-01-16    Ulrich Windl
  *	Introduced error checking for many cases in adjtimex().
  *	Updated NTP code according to technical memorandum Jan '96
  *	"A Kernel Model for Precision Timekeeping" by Dave Mills
  *	Allow time_constant larger than MAXTC(6) for NTP v4 (MAXTC == 10)
  *	(Even though the technical memorandum forbids it)
  */

 #include <linux/timex.h>
 #include <linux/errno.h>
 #include <linux/smp_lock.h>
 #include <asm/uaccess.h>

 /*
  * The timezone where the local system is located.  Used as a default by some
  * programs who obtain this value by using gettimeofday.
  */
 struct timezone sys_tz;

 extern unsigned long last_time_offset;

 #if !defined(__alpha__) && !defined(__ia64__)

 /*
  * sys_time() can be implemented in user-level using
  * sys_gettimeofday().  Is this for backwards compatibility?  If so,
  * why not move it into the appropriate arch directory (for those
  * architectures that need it).
  *
  * XXX This function is NOT 64-bit clean!
  */
 asmlinkage long sys_time(int * tloc)
 {
 	int i;

 	/* SMP: This is fairly trivial. We grab CURRENT_TIME and
 	   stuff it to user space. No side effects */
 	i = get_seconds();
 	if (tloc) {
 		if (put_user(i,tloc))
 			i = -EFAULT;
 	}
 	return i;
 }

 /*
  * sys_stime() can be implemented in user-level using
  * sys_settimeofday().  Is this for backwards compatibility?  If so,
  * why not move it into the appropriate arch directory (for those
  * architectures that need it).
  */

 asmlinkage long sys_stime(int * tptr)
 {
 	int value;

 	if (!capable(CAP_SYS_TIME))
 		return -EPERM;
 	if (get_user(value, tptr))
 		return -EFAULT;
 	write_seqlock_irq(&xtime_lock);
 	xtime.tv_sec = value;
 	xtime.tv_nsec = 0;
 	last_time_offset = 0;
 	time_adjust = 0;	/* stop active adjtime() */
 	time_status |= STA_UNSYNC;
 	time_maxerror = NTP_PHASE_LIMIT;
 	time_esterror = NTP_PHASE_LIMIT;
 	write_sequnlock_irq(&xtime_lock);
 	return 0;
 }

 #endif

 asmlinkage long sys_gettimeofday(struct timeval __user *tv, struct timezone __user *tz)
 {
 	if (likely(tv != NULL)) {
 		struct timeval ktv;
 		do_gettimeofday(&ktv);
 		if (copy_to_user(tv, &ktv, sizeof(ktv)))
 			return -EFAULT;
 	}
 	if (unlikely(tz != NULL)) {
 		if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
 			return -EFAULT;
 	}
 	return 0;
 }

 /*
  * Adjust the time obtained from the CMOS to be UTC time instead of
  * local time.
  *
  * This is ugly, but preferable to the alternatives.  Otherwise we
  * would either need to write a program to do it in /etc/rc (and risk
  * confusion if the program gets run more than once; it would also be
  * hard to make the program warp the clock precisely n hours)  or
  * compile in the timezone information into the kernel.  Bad, bad....
  *
  *              				- TYT, 1992-01-01
  *
  * The best thing to do is to keep the CMOS clock in universal time (UTC)
  * as real UNIX machines always do it. This avoids all headaches about
  * daylight saving times and warping kernel clocks.
  */
 inline static void warp_clock(void)
 {
 	write_seqlock_irq(&xtime_lock);
 	xtime.tv_sec += sys_tz.tz_minuteswest * 60;
 	last_time_offset = 0;
 	write_sequnlock_irq(&xtime_lock);
 }

 /*
  * In case for some reason the CMOS clock has not already been running
  * in UTC, but in some local time: The first time we set the timezone,
  * we will warp the clock so that it is ticking UTC time instead of
  * local time. Presumably, if someone is setting the timezone then we
  * are running in an environment where the programs understand about
  * timezones. This should be done at boot time in the /etc/rc script,
  * as soon as possible, so that the clock can be set right. Otherwise,
  * various programs will get confused when the clock gets warped.
  */

 int do_sys_settimeofday(struct timeval *tv, struct timezone *tz)
 {
 	static int firsttime = 1;

 	if (!capable(CAP_SYS_TIME))
 		return -EPERM;

 	if (tz) {
 		/* SMP safe, global irq locking makes it work. */
 		sys_tz = *tz;
 		if (firsttime) {
 			firsttime = 0;
 			if (!tv)
 				warp_clock();
 		}
 	}
 	if (tv)
 	{
 		/* SMP safe, again the code in arch/foo/time.c should
 		 * globally block out interrupts when it runs.
 		 */
 		do_settimeofday(tv);
 	}
 	return 0;
 }

 asmlinkage long sys_settimeofday(struct timeval __user *tv, struct timezone __user *tz)
 {
 	struct timeval	new_tv;
 	struct timezone new_tz;

 	if (tv) {
 		if (copy_from_user(&new_tv, tv, sizeof(*tv)))
 			return -EFAULT;
 	}
 	if (tz) {
 		if (copy_from_user(&new_tz, tz, sizeof(*tz)))
 			return -EFAULT;
 	}

 	return do_sys_settimeofday(tv ? &new_tv : NULL, tz ? &new_tz : NULL);
 }

 long pps_offset;		/* pps time offset (us) */
 long pps_jitter = MAXTIME;	/* time dispersion (jitter) (us) */

 long pps_freq;			/* frequency offset (scaled ppm) */
 long pps_stabil = MAXFREQ;	/* frequency dispersion (scaled ppm) */

 long pps_valid = PPS_VALID;	/* pps signal watchdog counter */

 int pps_shift = PPS_SHIFT;	/* interval duration (s) (shift) */

 long pps_jitcnt;		/* jitter limit exceeded */
 long pps_calcnt;		/* calibration intervals */
 long pps_errcnt;		/* calibration errors */
 long pps_stbcnt;		/* stability limit exceeded */

 /* hook for a loadable hardpps kernel module */
 void (*hardpps_ptr)(struct timeval *);

 /* adjtimex mainly allows reading (and writing, if superuser) of
  * kernel time-keeping variables. used by xntpd.
  */
 int do_adjtimex(struct timex *txc)
 {
         long ltemp, mtemp, save_adjust;
 	int result;

 	/* In order to modify anything, you gotta be super-user! */
 	if (txc->modes && !capable(CAP_SYS_TIME))
 		return -EPERM;

 	/* Now we validate the data before disabling interrupts */

 	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
 	  /* singleshot must not be used with any other mode bits */
 		if (txc->modes != ADJ_OFFSET_SINGLESHOT)
 			return -EINVAL;

 	if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
 	  /* adjustment Offset limited to +- .512 seconds */
 		if (txc->offset <= - MAXPHASE || txc->offset >= MAXPHASE )
 			return -EINVAL;

 	/* if the quartz is off by more than 10% something is VERY wrong ! */
 	if (txc->modes & ADJ_TICK)
 		if (txc->tick <  900000/USER_HZ ||
 		    txc->tick > 1100000/USER_HZ)
 			return -EINVAL;

 	write_seqlock_irq(&xtime_lock);
 	result = time_state;	/* mostly `TIME_OK' */

 	/* Save for later - semantics of adjtime is to return old value */
 	save_adjust = time_adjust;

 #if 0	/* STA_CLOCKERR is never set yet */
 	time_status &= ~STA_CLOCKERR;		/* reset STA_CLOCKERR */
 #endif
 	/* If there are input parameters, then process them */
 	if (txc->modes)
 	{
 	    if (txc->modes & ADJ_STATUS)	/* only set allowed bits */
 		time_status =  (txc->status & ~STA_RONLY) |
 			      (time_status & STA_RONLY);

 	    if (txc->modes & ADJ_FREQUENCY) {	/* p. 22 */
 		if (txc->freq > MAXFREQ || txc->freq < -MAXFREQ) {
 		    result = -EINVAL;
 		    goto leave;
 		}
 		time_freq = txc->freq - pps_freq;
 	    }

 	    if (txc->modes & ADJ_MAXERROR) {
 		if (txc->maxerror < 0 || txc->maxerror >= NTP_PHASE_LIMIT) {
 		    result = -EINVAL;
 		    goto leave;
 		}
 		time_maxerror = txc->maxerror;
 	    }

 	    if (txc->modes & ADJ_ESTERROR) {
 		if (txc->esterror < 0 || txc->esterror >= NTP_PHASE_LIMIT) {
 		    result = -EINVAL;
 		    goto leave;
 		}
 		time_esterror = txc->esterror;
 	    }

 	    if (txc->modes & ADJ_TIMECONST) {	/* p. 24 */
 		if (txc->constant < 0) {	/* NTP v4 uses values > 6 */
 		    result = -EINVAL;
 		    goto leave;
 		}
 		time_constant = txc->constant;
 	    }

 	    if (txc->modes & ADJ_OFFSET) {	/* values checked earlier */
 		if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
 		    /* adjtime() is independent from ntp_adjtime() */
 		    time_adjust = txc->offset;
 		}
 		else if ( time_status & (STA_PLL | STA_PPSTIME) ) {
 		    ltemp = (time_status & (STA_PPSTIME | STA_PPSSIGNAL)) ==
 		            (STA_PPSTIME | STA_PPSSIGNAL) ?
 		            pps_offset : txc->offset;

 		    /*
 		     * Scale the phase adjustment and
 		     * clamp to the operating range.
 		     */
 		    if (ltemp > MAXPHASE)
 		        time_offset = MAXPHASE << SHIFT_UPDATE;
 		    else if (ltemp < -MAXPHASE)
 			time_offset = -(MAXPHASE << SHIFT_UPDATE);
 		    else
 		        time_offset = ltemp << SHIFT_UPDATE;

 		    /*
 		     * Select whether the frequency is to be controlled
 		     * and in which mode (PLL or FLL). Clamp to the operating
 		     * range. Ugly multiply/divide should be replaced someday.
 		     */

 		    if (time_status & STA_FREQHOLD || time_reftime == 0)
 		        time_reftime = xtime.tv_sec;
 		    mtemp = xtime.tv_sec - time_reftime;
 		    time_reftime = xtime.tv_sec;
 		    if (time_status & STA_FLL) {
 		        if (mtemp >= MINSEC) {
 			    ltemp = (time_offset / mtemp) << (SHIFT_USEC -
 							      SHIFT_UPDATE);
 			    if (ltemp < 0)
 			        time_freq -= -ltemp >> SHIFT_KH;
 			    else
 			        time_freq += ltemp >> SHIFT_KH;
 			} else /* calibration interval too short (p. 12) */
 				result = TIME_ERROR;
 		    } else {	/* PLL mode */
 		        if (mtemp < MAXSEC) {
 			    ltemp *= mtemp;
 			    if (ltemp < 0)
 			        time_freq -= -ltemp >> (time_constant +
 							time_constant +
 							SHIFT_KF - SHIFT_USEC);
 			    else
 			        time_freq += ltemp >> (time_constant +
 						       time_constant +
 						       SHIFT_KF - SHIFT_USEC);
 			} else /* calibration interval too long (p. 12) */
 				result = TIME_ERROR;
 		    }
 		    if (time_freq > time_tolerance)
 		        time_freq = time_tolerance;
 		    else if (time_freq < -time_tolerance)
 		        time_freq = -time_tolerance;
 		} /* STA_PLL || STA_PPSTIME */
 	    } /* txc->modes & ADJ_OFFSET */
 	    if (txc->modes & ADJ_TICK) {
 		tick_usec = txc->tick;
 		tick_nsec = TICK_NSEC(tick_usec);
 	    }
 	} /* txc->modes */
 leave:	if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0
 	    || ((time_status & (STA_PPSFREQ|STA_PPSTIME)) != 0
 		&& (time_status & STA_PPSSIGNAL) == 0)
 	    /* p. 24, (b) */
 	    || ((time_status & (STA_PPSTIME|STA_PPSJITTER))
 		== (STA_PPSTIME|STA_PPSJITTER))
 	    /* p. 24, (c) */
 	    || ((time_status & STA_PPSFREQ) != 0
 		&& (time_status & (STA_PPSWANDER|STA_PPSERROR)) != 0))
 	    /* p. 24, (d) */
 		result = TIME_ERROR;

 	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
 	    txc->offset	   = save_adjust;
 	else {
 	    if (time_offset < 0)
 		txc->offset = -(-time_offset >> SHIFT_UPDATE);
 	    else
 		txc->offset = time_offset >> SHIFT_UPDATE;
 	}
 	txc->freq	   = time_freq + pps_freq;
 	txc->maxerror	   = time_maxerror;
 	txc->esterror	   = time_esterror;
 	txc->status	   = time_status;
 	txc->constant	   = time_constant;
 	txc->precision	   = time_precision;
 	txc->tolerance	   = time_tolerance;
 	txc->tick	   = tick_usec;
 	txc->ppsfreq	   = pps_freq;
 	txc->jitter	   = pps_jitter >> PPS_AVG;
 	txc->shift	   = pps_shift;
 	txc->stabil	   = pps_stabil;
 	txc->jitcnt	   = pps_jitcnt;
 	txc->calcnt	   = pps_calcnt;
 	txc->errcnt	   = pps_errcnt;
 	txc->stbcnt	   = pps_stbcnt;
 	last_time_offset = 0;
 	write_sequnlock_irq(&xtime_lock);
 	do_gettimeofday(&txc->time);
 	return(result);
 }

 asmlinkage long sys_adjtimex(struct timex __user *txc_p)
 {
 	struct timex txc;		/* Local copy of parameter */
 	int ret;

 	/* Copy the user data space into the kernel copy
 	 * structure. But bear in mind that the structures
 	 * may change
 	 */
 	if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
 		return -EFAULT;
 	ret = do_adjtimex(&txc);
 	return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
 }

 struct timespec current_kernel_time(void)
 {
         struct timespec now;
         unsigned long seq;

 	do {
 		seq = read_seqbegin(&xtime_lock);

 		now = xtime;
 	} while (read_seqretry(&xtime_lock, seq));

 	return now;
 }

 #if (BITS_PER_LONG < 64)
 u64 get_jiffies_64(void)
 {
 	unsigned long seq;
 	u64 ret;

 	do {
 		seq = read_seqbegin(&xtime_lock);
 		ret = jiffies_64;
 	} while (read_seqretry(&xtime_lock, seq));
 	return ret;
 }
 #endif
	/*
	* linux/kernel/time.c
	*
	* Copyright (C) 1991, 1992 Linus Torvalds
	*
	* This file contains the interface functions for the various
	* time related system calls: time, stime, gettimeofday, settimeofday,
	* adjtime
	*/
	/*
	* Modification history kernel/time.c
	*
	* 1993-09-02 Philip Gladstone
	* Created file with time related functions from sched.c and adjtimex()
	* 1993-10-08 Torsten Duwe
	* adjtime interface update and CMOS clock write code
	* 1995-08-13 Torsten Duwe
	* kernel PLL updated to 1994-12-13 specs (rfc-1589)
	* 1999-01-16 Ulrich Windl
	* Introduced error checking for many cases in adjtimex().
	* Updated NTP code according to technical memorandum Jan '96
	* "A Kernel Model for Precision Timekeeping" by Dave Mills
	* Allow time_constant larger than MAXTC(6) for NTP v4 (MAXTC == 10)
	* (Even though the technical memorandum forbids it)
	*/

	#include <linux/timex.h>
	#include <linux/errno.h>
	#include <linux/smp_lock.h>
	#include <asm/uaccess.h>

	/*
	* The timezone where the local system is located. Used as a default by some
	* programs who obtain this value by using gettimeofday.
	*/
	struct timezone sys_tz;

	extern unsigned long last_time_offset;

	#if !defined(__alpha__) && !defined(__ia64__)

	/*
	* sys_time() can be implemented in user-level using
	* sys_gettimeofday(). Is this for backwards compatibility? If so,
	* why not move it into the appropriate arch directory (for those
	* architectures that need it).
	*
	* XXX This function is NOT 64-bit clean!
	*/
	asmlinkage long sys_time(int * tloc)
	{
	int i;

	/* SMP: This is fairly trivial. We grab CURRENT_TIME and
	stuff it to user space. No side effects */
	i = get_seconds();
	if (tloc) {
	if (put_user(i,tloc))
	i = -EFAULT;
	}
	return i;
	}

	/*
	* sys_stime() can be implemented in user-level using
	* sys_settimeofday(). Is this for backwards compatibility? If so,
	* why not move it into the appropriate arch directory (for those
	* architectures that need it).
	*/

	asmlinkage long sys_stime(int * tptr)
	{
	int value;

	if (!capable(CAP_SYS_TIME))
	return -EPERM;
	if (get_user(value, tptr))
	return -EFAULT;
	write_seqlock_irq(&xtime_lock);
	xtime.tv_sec = value;
	xtime.tv_nsec = 0;
	last_time_offset = 0;
	time_adjust = 0; /* stop active adjtime() */
	time_status \|= STA_UNSYNC;
	time_maxerror = NTP_PHASE_LIMIT;
	time_esterror = NTP_PHASE_LIMIT;
	write_sequnlock_irq(&xtime_lock);
	return 0;
	}

	#endif

	asmlinkage long sys_gettimeofday(struct timeval __user tv, struct timezone __user tz)
	{
	if (likely(tv != NULL)) {
	struct timeval ktv;
	do_gettimeofday(&ktv);
	if (copy_to_user(tv, &ktv, sizeof(ktv)))
	return -EFAULT;
	}
	if (unlikely(tz != NULL)) {
	if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
	return -EFAULT;
	}
	return 0;
	}

	/*
	* Adjust the time obtained from the CMOS to be UTC time instead of
	* local time.
	*
	* This is ugly, but preferable to the alternatives. Otherwise we
	* would either need to write a program to do it in /etc/rc (and risk
	* confusion if the program gets run more than once; it would also be
	* hard to make the program warp the clock precisely n hours) or
	* compile in the timezone information into the kernel. Bad, bad....
	*
	* - TYT, 1992-01-01
	*
	* The best thing to do is to keep the CMOS clock in universal time (UTC)
	* as real UNIX machines always do it. This avoids all headaches about
	* daylight saving times and warping kernel clocks.
	*/
	inline static void warp_clock(void)
	{
	write_seqlock_irq(&xtime_lock);
	xtime.tv_sec += sys_tz.tz_minuteswest * 60;
	last_time_offset = 0;
	write_sequnlock_irq(&xtime_lock);
	}

	/*
	* In case for some reason the CMOS clock has not already been running
	* in UTC, but in some local time: The first time we set the timezone,
	* we will warp the clock so that it is ticking UTC time instead of
	* local time. Presumably, if someone is setting the timezone then we
	* are running in an environment where the programs understand about
	* timezones. This should be done at boot time in the /etc/rc script,
	* as soon as possible, so that the clock can be set right. Otherwise,
	* various programs will get confused when the clock gets warped.
	*/

	int do_sys_settimeofday(struct timeval tv, struct timezone tz)
	{
	static int firsttime = 1;

	if (!capable(CAP_SYS_TIME))
	return -EPERM;

	if (tz) {
	/* SMP safe, global irq locking makes it work. */
	sys_tz = *tz;
	if (firsttime) {
	firsttime = 0;
	if (!tv)
	warp_clock();
	}
	}
	if (tv)
	{
	/* SMP safe, again the code in arch/foo/time.c should
	* globally block out interrupts when it runs.
	*/
	do_settimeofday(tv);
	}
	return 0;
	}

	asmlinkage long sys_settimeofday(struct timeval __user tv, struct timezone __user tz)
	{
	struct timeval new_tv;
	struct timezone new_tz;

	if (tv) {
	if (copy_from_user(&new_tv, tv, sizeof(*tv)))
	return -EFAULT;
	}
	if (tz) {
	if (copy_from_user(&new_tz, tz, sizeof(*tz)))
	return -EFAULT;
	}

	return do_sys_settimeofday(tv ? &new_tv : NULL, tz ? &new_tz : NULL);
	}

	long pps_offset; /* pps time offset (us) */
	long pps_jitter = MAXTIME; /* time dispersion (jitter) (us) */

	long pps_freq; /* frequency offset (scaled ppm) */
	long pps_stabil = MAXFREQ; /* frequency dispersion (scaled ppm) */

	long pps_valid = PPS_VALID; /* pps signal watchdog counter */

	int pps_shift = PPS_SHIFT; /* interval duration (s) (shift) */

	long pps_jitcnt; /* jitter limit exceeded */
	long pps_calcnt; /* calibration intervals */
	long pps_errcnt; /* calibration errors */
	long pps_stbcnt; /* stability limit exceeded */

	/* hook for a loadable hardpps kernel module */
	void (hardpps_ptr)(struct timeval );

	/* adjtimex mainly allows reading (and writing, if superuser) of
	* kernel time-keeping variables. used by xntpd.
	*/
	int do_adjtimex(struct timex *txc)
	{
	long ltemp, mtemp, save_adjust;
	int result;

	/* In order to modify anything, you gotta be super-user! */
	if (txc->modes && !capable(CAP_SYS_TIME))
	return -EPERM;

	/* Now we validate the data before disabling interrupts */

	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
	/* singleshot must not be used with any other mode bits */
	if (txc->modes != ADJ_OFFSET_SINGLESHOT)
	return -EINVAL;

	if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
	/* adjustment Offset limited to +- .512 seconds */
	if (txc->offset <= - MAXPHASE \|\| txc->offset >= MAXPHASE )
	return -EINVAL;

	/* if the quartz is off by more than 10% something is VERY wrong ! */
	if (txc->modes & ADJ_TICK)
	if (txc->tick < 900000/USER_HZ \|\|
	txc->tick > 1100000/USER_HZ)
	return -EINVAL;

	write_seqlock_irq(&xtime_lock);
	result = time_state; /* mostly `TIME_OK' */

	/* Save for later - semantics of adjtime is to return old value */
	save_adjust = time_adjust;

	#if 0 /* STA_CLOCKERR is never set yet */
	time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */
	#endif
	/* If there are input parameters, then process them */
	if (txc->modes)
	{
	if (txc->modes & ADJ_STATUS) /* only set allowed bits */
	time_status = (txc->status & ~STA_RONLY) \|
	(time_status & STA_RONLY);

	if (txc->modes & ADJ_FREQUENCY) { /* p. 22 */
	if (txc->freq > MAXFREQ \|\| txc->freq < -MAXFREQ) {
	result = -EINVAL;
	goto leave;
	}
	time_freq = txc->freq - pps_freq;
	}

	if (txc->modes & ADJ_MAXERROR) {
	if (txc->maxerror < 0 \|\| txc->maxerror >= NTP_PHASE_LIMIT) {
	result = -EINVAL;
	goto leave;
	}
	time_maxerror = txc->maxerror;
	}

	if (txc->modes & ADJ_ESTERROR) {
	if (txc->esterror < 0 \|\| txc->esterror >= NTP_PHASE_LIMIT) {
	result = -EINVAL;
	goto leave;
	}
	time_esterror = txc->esterror;
	}

	if (txc->modes & ADJ_TIMECONST) { /* p. 24 */
	if (txc->constant < 0) { /* NTP v4 uses values > 6 */
	result = -EINVAL;
	goto leave;
	}
	time_constant = txc->constant;
	}

	if (txc->modes & ADJ_OFFSET) { /* values checked earlier */
	if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
	/* adjtime() is independent from ntp_adjtime() */
	time_adjust = txc->offset;
	}
	else if ( time_status & (STA_PLL \| STA_PPSTIME) ) {
	ltemp = (time_status & (STA_PPSTIME \| STA_PPSSIGNAL)) ==
	(STA_PPSTIME \| STA_PPSSIGNAL) ?
	pps_offset : txc->offset;

	/*
	* Scale the phase adjustment and
	* clamp to the operating range.
	*/
	if (ltemp > MAXPHASE)
	time_offset = MAXPHASE << SHIFT_UPDATE;
	else if (ltemp < -MAXPHASE)
	time_offset = -(MAXPHASE << SHIFT_UPDATE);
	else
	time_offset = ltemp << SHIFT_UPDATE;

	/*
	* Select whether the frequency is to be controlled
	* and in which mode (PLL or FLL). Clamp to the operating
	* range. Ugly multiply/divide should be replaced someday.
	*/

	if (time_status & STA_FREQHOLD \|\| time_reftime == 0)
	time_reftime = xtime.tv_sec;
	mtemp = xtime.tv_sec - time_reftime;
	time_reftime = xtime.tv_sec;
	if (time_status & STA_FLL) {
	if (mtemp >= MINSEC) {
	ltemp = (time_offset / mtemp) << (SHIFT_USEC -
	SHIFT_UPDATE);
	if (ltemp < 0)
	time_freq -= -ltemp >> SHIFT_KH;
	else
	time_freq += ltemp >> SHIFT_KH;
	} else /* calibration interval too short (p. 12) */
	result = TIME_ERROR;
	} else { /* PLL mode */
	if (mtemp < MAXSEC) {
	ltemp *= mtemp;
	if (ltemp < 0)
	time_freq -= -ltemp >> (time_constant +
	time_constant +
	SHIFT_KF - SHIFT_USEC);
	else
	time_freq += ltemp >> (time_constant +
	time_constant +
	SHIFT_KF - SHIFT_USEC);
	} else /* calibration interval too long (p. 12) */
	result = TIME_ERROR;
	}
	if (time_freq > time_tolerance)
	time_freq = time_tolerance;
	else if (time_freq < -time_tolerance)
	time_freq = -time_tolerance;
	} /* STA_PLL \|\| STA_PPSTIME */
	} /* txc->modes & ADJ_OFFSET */
	if (txc->modes & ADJ_TICK) {
	tick_usec = txc->tick;
	tick_nsec = TICK_NSEC(tick_usec);
	}
	} /* txc->modes */
	leave: if ((time_status & (STA_UNSYNC\|STA_CLOCKERR)) != 0
	\|\| ((time_status & (STA_PPSFREQ\|STA_PPSTIME)) != 0
	&& (time_status & STA_PPSSIGNAL) == 0)
	/* p. 24, (b) */
	\|\| ((time_status & (STA_PPSTIME\|STA_PPSJITTER))
	== (STA_PPSTIME\|STA_PPSJITTER))
	/* p. 24, (c) */
	\|\| ((time_status & STA_PPSFREQ) != 0
	&& (time_status & (STA_PPSWANDER\|STA_PPSERROR)) != 0))
	/* p. 24, (d) */
	result = TIME_ERROR;

	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
	txc->offset = save_adjust;
	else {
	if (time_offset < 0)
	txc->offset = -(-time_offset >> SHIFT_UPDATE);
	else
	txc->offset = time_offset >> SHIFT_UPDATE;
	}
	txc->freq = time_freq + pps_freq;
	txc->maxerror = time_maxerror;
	txc->esterror = time_esterror;
	txc->status = time_status;
	txc->constant = time_constant;
	txc->precision = time_precision;
	txc->tolerance = time_tolerance;
	txc->tick = tick_usec;
	txc->ppsfreq = pps_freq;
	txc->jitter = pps_jitter >> PPS_AVG;
	txc->shift = pps_shift;
	txc->stabil = pps_stabil;
	txc->jitcnt = pps_jitcnt;
	txc->calcnt = pps_calcnt;
	txc->errcnt = pps_errcnt;
	txc->stbcnt = pps_stbcnt;
	last_time_offset = 0;
	write_sequnlock_irq(&xtime_lock);
	do_gettimeofday(&txc->time);
	return(result);
	}

	asmlinkage long sys_adjtimex(struct timex __user *txc_p)
	{
	struct timex txc; /* Local copy of parameter */
	int ret;

	/* Copy the user data space into the kernel copy
	* structure. But bear in mind that the structures
	* may change
	*/
	if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
	return -EFAULT;
	ret = do_adjtimex(&txc);
	return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
	}

	struct timespec current_kernel_time(void)
	{
	struct timespec now;
	unsigned long seq;

	do {
	seq = read_seqbegin(&xtime_lock);

	now = xtime;
	} while (read_seqretry(&xtime_lock, seq));

	return now;
	}

	#if (BITS_PER_LONG < 64)
	u64 get_jiffies_64(void)
	{
	unsigned long seq;
	u64 ret;

	do {
	seq = read_seqbegin(&xtime_lock);
	ret = jiffies_64;
	} while (read_seqretry(&xtime_lock, seq));
	return ret;
	}
	#endif