/* * 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/capability.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. */ static inline 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; if (tv && !timespec_valid(tv)) return -EINVAL; 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); } /* 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; } 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) { ltemp = 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); time_freq += shift_right(ltemp, SHIFT_KH); } else /* calibration interval too short (p. 12) */ result = TIME_ERROR; } else { /* PLL mode */ if (mtemp < MAXSEC) { ltemp *= mtemp; time_freq += shift_right(ltemp,(time_constant + time_constant + SHIFT_KF - SHIFT_USEC)); } else /* calibration interval too long (p. 12) */ result = TIME_ERROR; } time_freq = min(time_freq, time_tolerance); time_freq = max(time_freq, -time_tolerance); } /* STA_PLL */ } /* 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) result = TIME_ERROR; if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) txc->offset = save_adjust; else { txc->offset = shift_right(time_offset, SHIFT_UPDATE); } txc->freq = time_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; /* 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; 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); { 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; } EXPORT_SYMBOL(do_settimeofday); 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; } EXPORT_SYMBOL_GPL(getnstimeofday); #endif /* Converts Gregorian date to seconds since 1970-01-01 00:00:00. * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. * * [For the Julian calendar (which was used in Russia before 1917, * Britain & colonies before 1752, anywhere else before 1582, * and is still in use by some communities) leave out the * -year/100+year/400 terms, and add 10.] * * This algorithm was first published by Gauss (I think). * * WARNING: this function will overflow on 2106-02-07 06:28:16 on * machines were long is 32-bit! (However, as time_t is signed, we * will already get problems at other places on 2038-01-19 03:14:08) */ unsigned long mktime(const unsigned int year0, const unsigned int mon0, const unsigned int day, const unsigned int hour, const unsigned int min, const unsigned int sec) { unsigned int mon = mon0, year = year0; /* 1..12 -> 11,12,1..10 */ if (0 >= (int) (mon -= 2)) { mon += 12; /* Puts Feb last since it has leap day */ year -= 1; } return ((((unsigned long) (year/4 - year/100 + year/400 + 367*mon/12 + day) + year*365 - 719499 )*24 + hour /* now have hours */ )*60 + min /* now have minutes */ )*60 + sec; /* finally seconds */ } EXPORT_SYMBOL(mktime); /** * set_normalized_timespec - set timespec sec and nsec parts and normalize * * @ts: pointer to timespec variable to be set * @sec: seconds to set * @nsec: nanoseconds to set * * Set seconds and nanoseconds field of a timespec variable and * normalize to the timespec storage format * * Note: The tv_nsec part is always in the range of * 0 <= tv_nsec < NSEC_PER_SEC * For negative values only the tv_sec field is negative ! */ void set_normalized_timespec(struct timespec *ts, time_t sec, long nsec) { while (nsec >= NSEC_PER_SEC) { nsec -= NSEC_PER_SEC; ++sec; } while (nsec < 0) { nsec += NSEC_PER_SEC; --sec; } ts->tv_sec = sec; ts->tv_nsec = nsec; } /** * ns_to_timespec - Convert nanoseconds to timespec * @nsec: the nanoseconds value to be converted * * Returns the timespec representation of the nsec parameter. */ struct timespec ns_to_timespec(const s64 nsec) { struct timespec ts; if (!nsec) return (struct timespec) {0, 0}; ts.tv_sec = div_long_long_rem_signed(nsec, NSEC_PER_SEC, &ts.tv_nsec); if (unlikely(nsec < 0)) set_normalized_timespec(&ts, ts.tv_sec, ts.tv_nsec); return ts; } /** * ns_to_timeval - Convert nanoseconds to timeval * @nsec: the nanoseconds value to be converted * * Returns the timeval representation of the nsec parameter. */ struct timeval ns_to_timeval(const s64 nsec) { struct timespec ts = ns_to_timespec(nsec); struct timeval tv; tv.tv_sec = ts.tv_sec; tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000; return tv; } #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);