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+/*
+ * 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)
+ * 2004-07-14 Christoph Lameter
+ * Added getnstimeofday to allow the posix timer functions to return
+ * with nanosecond accuracy
+ */
+
+#include <linux/module.h>
+#include <linux/timex.h>
+#include <linux/errno.h>
+#include <linux/smp_lock.h>
+#include <linux/syscalls.h>
+#include <linux/security.h>
+#include <linux/fs.h>
+#include <linux/module.h>
+
+#include <asm/uaccess.h>
+#include <asm/unistd.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;
+
+EXPORT_SYMBOL(sys_tz);
+
+#ifdef __ARCH_WANT_SYS_TIME
+
+/*
+ * 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).
+ */
+asmlinkage long sys_time(time_t __user * tloc)
+{
+ time_t i;
+ struct timeval tv;
+
+ do_gettimeofday(&tv);
+ i = tv.tv_sec;
+
+ 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(time_t __user *tptr)
+{
+ struct timespec tv;
+ int err;
+
+ if (get_user(tv.tv_sec, tptr))
+ return -EFAULT;
+
+ tv.tv_nsec = 0;
+
+ err = security_settime(&tv, NULL);
+ if (err)
+ return err;
+
+ do_settimeofday(&tv);
+ return 0;
+}
+
+#endif /* __ARCH_WANT_SYS_TIME */
+
+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);
+ wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60;
+ xtime.tv_sec += sys_tz.tz_minuteswest * 60;
+ time_interpolator_reset();
+ write_sequnlock_irq(&xtime_lock);
+ clock_was_set();
+}
+
+/*
+ * 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 timespec *tv, struct timezone *tz)
+{
+ static int firsttime = 1;
+ int error = 0;
+
+ error = security_settime(tv, tz);
+ if (error)
+ return error;
+
+ 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.
+ */
+ return do_settimeofday(tv);
+ }
+ return 0;
+}
+
+asmlinkage long sys_settimeofday(struct timeval __user *tv,
+ struct timezone __user *tz)
+{
+ struct timeval user_tv;
+ struct timespec new_ts;
+ struct timezone new_tz;
+
+ if (tv) {
+ if (copy_from_user(&user_tv, tv, sizeof(*tv)))
+ return -EFAULT;
+ new_ts.tv_sec = user_tv.tv_sec;
+ new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
+ }
+ if (tz) {
+ if (copy_from_user(&new_tz, tz, sizeof(*tz)))
+ return -EFAULT;
+ }
+
+ return do_sys_settimeofday(tv ? &new_ts : 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 *);
+
+/* we call this to notify the arch when the clock is being
+ * controlled. If no such arch routine, do nothing.
+ */
+void __attribute__ ((weak)) notify_arch_cmos_timer(void)
+{
+ return;
+}
+
+/* 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_next_adjust ? time_next_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() */
+ if ((time_next_adjust = txc->offset) == 0)
+ time_adjust = 0;
+ }
+ 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_USEC_TO_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;
+ write_sequnlock_irq(&xtime_lock);
+ do_gettimeofday(&txc->time);
+ notify_arch_cmos_timer();
+ 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;
+}
+
+inline 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;
+}
+
+EXPORT_SYMBOL(current_kernel_time);
+
+/**
+ * current_fs_time - Return FS time
+ * @sb: Superblock.
+ *
+ * Return the current time truncated to the time granuality supported by
+ * the fs.
+ */
+struct timespec current_fs_time(struct super_block *sb)
+{
+ struct timespec now = current_kernel_time();
+ return timespec_trunc(now, sb->s_time_gran);
+}
+EXPORT_SYMBOL(current_fs_time);
+
+/**
+ * timespec_trunc - Truncate timespec to a granuality
+ * @t: Timespec
+ * @gran: Granuality in ns.
+ *
+ * Truncate a timespec to a granuality. gran must be smaller than a second.
+ * Always rounds down.
+ *
+ * This function should be only used for timestamps returned by
+ * current_kernel_time() or CURRENT_TIME, not with do_gettimeofday() because
+ * it doesn't handle the better resolution of the later.
+ */
+struct timespec timespec_trunc(struct timespec t, unsigned gran)
+{
+ /*
+ * Division is pretty slow so avoid it for common cases.
+ * Currently current_kernel_time() never returns better than
+ * jiffies resolution. Exploit that.
+ */
+ if (gran <= jiffies_to_usecs(1) * 1000) {
+ /* nothing */
+ } else if (gran == 1000000000) {
+ t.tv_nsec = 0;
+ } else {
+ t.tv_nsec -= t.tv_nsec % gran;
+ }
+ return t;
+}
+EXPORT_SYMBOL(timespec_trunc);
+
+#ifdef CONFIG_TIME_INTERPOLATION
+void getnstimeofday (struct timespec *tv)
+{
+ unsigned long seq,sec,nsec;
+
+ do {
+ seq = read_seqbegin(&xtime_lock);
+ sec = xtime.tv_sec;
+ nsec = xtime.tv_nsec+time_interpolator_get_offset();
+ } while (unlikely(read_seqretry(&xtime_lock, seq)));
+
+ while (unlikely(nsec >= NSEC_PER_SEC)) {
+ nsec -= NSEC_PER_SEC;
+ ++sec;
+ }
+ tv->tv_sec = sec;
+ tv->tv_nsec = nsec;
+}
+EXPORT_SYMBOL_GPL(getnstimeofday);
+
+int do_settimeofday (struct timespec *tv)
+{
+ time_t wtm_sec, sec = tv->tv_sec;
+ long wtm_nsec, nsec = tv->tv_nsec;
+
+ if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
+ return -EINVAL;
+
+ write_seqlock_irq(&xtime_lock);
+ {
+ /*
+ * This is revolting. We need to set "xtime" correctly. However, the value
+ * in this location is the value at the most recent update of wall time.
+ * Discover what correction gettimeofday would have done, and then undo
+ * it!
+ */
+ nsec -= time_interpolator_get_offset();
+
+ wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
+ wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
+
+ set_normalized_timespec(&xtime, sec, nsec);
+ set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
+
+ time_adjust = 0; /* stop active adjtime() */
+ time_status |= STA_UNSYNC;
+ time_maxerror = NTP_PHASE_LIMIT;
+ time_esterror = NTP_PHASE_LIMIT;
+ time_interpolator_reset();
+ }
+ write_sequnlock_irq(&xtime_lock);
+ clock_was_set();
+ return 0;
+}
+
+void do_gettimeofday (struct timeval *tv)
+{
+ unsigned long seq, nsec, usec, sec, offset;
+ do {
+ seq = read_seqbegin(&xtime_lock);
+ offset = time_interpolator_get_offset();
+ sec = xtime.tv_sec;
+ nsec = xtime.tv_nsec;
+ } while (unlikely(read_seqretry(&xtime_lock, seq)));
+
+ usec = (nsec + offset) / 1000;
+
+ while (unlikely(usec >= USEC_PER_SEC)) {
+ usec -= USEC_PER_SEC;
+ ++sec;
+ }
+
+ tv->tv_sec = sec;
+ tv->tv_usec = usec;
+}
+
+EXPORT_SYMBOL(do_gettimeofday);
+
+
+#else
+/*
+ * Simulate gettimeofday using do_gettimeofday which only allows a timeval
+ * and therefore only yields usec accuracy
+ */
+void getnstimeofday(struct timespec *tv)
+{
+ struct timeval x;
+
+ do_gettimeofday(&x);
+ tv->tv_sec = x.tv_sec;
+ tv->tv_nsec = x.tv_usec * NSEC_PER_USEC;
+}
+#endif
+
+#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;
+}
+
+EXPORT_SYMBOL(get_jiffies_64);
+#endif
+
+EXPORT_SYMBOL(jiffies);
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