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593 lines
16 KiB
593 lines
16 KiB
/*
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* linux/kernel/time.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* This file contains the interface functions for the various
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* time related system calls: time, stime, gettimeofday, settimeofday,
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* adjtime
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*/
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/*
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* Modification history kernel/time.c
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*
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* 1993-09-02 Philip Gladstone
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* Created file with time related functions from sched.c and adjtimex()
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* 1993-10-08 Torsten Duwe
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* adjtime interface update and CMOS clock write code
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* 1995-08-13 Torsten Duwe
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* kernel PLL updated to 1994-12-13 specs (rfc-1589)
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* 1999-01-16 Ulrich Windl
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* Introduced error checking for many cases in adjtimex().
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* Updated NTP code according to technical memorandum Jan '96
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* "A Kernel Model for Precision Timekeeping" by Dave Mills
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* Allow time_constant larger than MAXTC(6) for NTP v4 (MAXTC == 10)
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* (Even though the technical memorandum forbids it)
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* 2004-07-14 Christoph Lameter
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* Added getnstimeofday to allow the posix timer functions to return
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* with nanosecond accuracy
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*/
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#include <linux/module.h>
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#include <linux/timex.h>
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#include <linux/errno.h>
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#include <linux/smp_lock.h>
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#include <linux/syscalls.h>
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#include <linux/security.h>
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#include <linux/fs.h>
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#include <linux/module.h>
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#include <asm/uaccess.h>
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#include <asm/unistd.h>
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/*
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* The timezone where the local system is located. Used as a default by some
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* programs who obtain this value by using gettimeofday.
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*/
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struct timezone sys_tz;
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EXPORT_SYMBOL(sys_tz);
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#ifdef __ARCH_WANT_SYS_TIME
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/*
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* sys_time() can be implemented in user-level using
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* sys_gettimeofday(). Is this for backwards compatibility? If so,
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* why not move it into the appropriate arch directory (for those
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* architectures that need it).
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*/
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asmlinkage long sys_time(time_t __user * tloc)
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{
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time_t i;
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struct timeval tv;
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do_gettimeofday(&tv);
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i = tv.tv_sec;
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if (tloc) {
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if (put_user(i,tloc))
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i = -EFAULT;
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}
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return i;
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}
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/*
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* sys_stime() can be implemented in user-level using
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* sys_settimeofday(). Is this for backwards compatibility? If so,
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* why not move it into the appropriate arch directory (for those
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* architectures that need it).
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*/
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asmlinkage long sys_stime(time_t __user *tptr)
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{
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struct timespec tv;
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int err;
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if (get_user(tv.tv_sec, tptr))
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return -EFAULT;
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tv.tv_nsec = 0;
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err = security_settime(&tv, NULL);
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if (err)
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return err;
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do_settimeofday(&tv);
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return 0;
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}
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#endif /* __ARCH_WANT_SYS_TIME */
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asmlinkage long sys_gettimeofday(struct timeval __user *tv, struct timezone __user *tz)
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{
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if (likely(tv != NULL)) {
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struct timeval ktv;
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do_gettimeofday(&ktv);
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if (copy_to_user(tv, &ktv, sizeof(ktv)))
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return -EFAULT;
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}
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if (unlikely(tz != NULL)) {
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if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
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return -EFAULT;
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}
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return 0;
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}
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/*
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* Adjust the time obtained from the CMOS to be UTC time instead of
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* local time.
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*
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* This is ugly, but preferable to the alternatives. Otherwise we
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* would either need to write a program to do it in /etc/rc (and risk
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* confusion if the program gets run more than once; it would also be
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* hard to make the program warp the clock precisely n hours) or
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* compile in the timezone information into the kernel. Bad, bad....
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*
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* - TYT, 1992-01-01
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*
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* The best thing to do is to keep the CMOS clock in universal time (UTC)
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* as real UNIX machines always do it. This avoids all headaches about
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* daylight saving times and warping kernel clocks.
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*/
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static inline void warp_clock(void)
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{
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write_seqlock_irq(&xtime_lock);
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wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60;
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xtime.tv_sec += sys_tz.tz_minuteswest * 60;
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time_interpolator_reset();
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write_sequnlock_irq(&xtime_lock);
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clock_was_set();
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}
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/*
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* In case for some reason the CMOS clock has not already been running
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* in UTC, but in some local time: The first time we set the timezone,
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* we will warp the clock so that it is ticking UTC time instead of
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* local time. Presumably, if someone is setting the timezone then we
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* are running in an environment where the programs understand about
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* timezones. This should be done at boot time in the /etc/rc script,
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* as soon as possible, so that the clock can be set right. Otherwise,
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* various programs will get confused when the clock gets warped.
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*/
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int do_sys_settimeofday(struct timespec *tv, struct timezone *tz)
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{
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static int firsttime = 1;
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int error = 0;
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error = security_settime(tv, tz);
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if (error)
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return error;
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if (tz) {
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/* SMP safe, global irq locking makes it work. */
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sys_tz = *tz;
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if (firsttime) {
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firsttime = 0;
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if (!tv)
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warp_clock();
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}
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}
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if (tv)
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{
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/* SMP safe, again the code in arch/foo/time.c should
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* globally block out interrupts when it runs.
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*/
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return do_settimeofday(tv);
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}
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return 0;
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}
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asmlinkage long sys_settimeofday(struct timeval __user *tv,
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struct timezone __user *tz)
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{
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struct timeval user_tv;
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struct timespec new_ts;
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struct timezone new_tz;
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if (tv) {
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if (copy_from_user(&user_tv, tv, sizeof(*tv)))
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return -EFAULT;
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new_ts.tv_sec = user_tv.tv_sec;
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new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
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}
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if (tz) {
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if (copy_from_user(&new_tz, tz, sizeof(*tz)))
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return -EFAULT;
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}
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return do_sys_settimeofday(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
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}
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long pps_offset; /* pps time offset (us) */
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long pps_jitter = MAXTIME; /* time dispersion (jitter) (us) */
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long pps_freq; /* frequency offset (scaled ppm) */
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long pps_stabil = MAXFREQ; /* frequency dispersion (scaled ppm) */
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long pps_valid = PPS_VALID; /* pps signal watchdog counter */
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int pps_shift = PPS_SHIFT; /* interval duration (s) (shift) */
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long pps_jitcnt; /* jitter limit exceeded */
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long pps_calcnt; /* calibration intervals */
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long pps_errcnt; /* calibration errors */
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long pps_stbcnt; /* stability limit exceeded */
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/* hook for a loadable hardpps kernel module */
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void (*hardpps_ptr)(struct timeval *);
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/* we call this to notify the arch when the clock is being
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* controlled. If no such arch routine, do nothing.
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*/
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void __attribute__ ((weak)) notify_arch_cmos_timer(void)
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{
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return;
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}
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/* adjtimex mainly allows reading (and writing, if superuser) of
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* kernel time-keeping variables. used by xntpd.
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*/
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int do_adjtimex(struct timex *txc)
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{
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long ltemp, mtemp, save_adjust;
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int result;
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/* In order to modify anything, you gotta be super-user! */
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if (txc->modes && !capable(CAP_SYS_TIME))
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return -EPERM;
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/* Now we validate the data before disabling interrupts */
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if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
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/* singleshot must not be used with any other mode bits */
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if (txc->modes != ADJ_OFFSET_SINGLESHOT)
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return -EINVAL;
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if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
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/* adjustment Offset limited to +- .512 seconds */
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if (txc->offset <= - MAXPHASE || txc->offset >= MAXPHASE )
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return -EINVAL;
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/* if the quartz is off by more than 10% something is VERY wrong ! */
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if (txc->modes & ADJ_TICK)
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if (txc->tick < 900000/USER_HZ ||
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txc->tick > 1100000/USER_HZ)
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return -EINVAL;
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write_seqlock_irq(&xtime_lock);
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result = time_state; /* mostly `TIME_OK' */
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/* Save for later - semantics of adjtime is to return old value */
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save_adjust = time_next_adjust ? time_next_adjust : time_adjust;
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#if 0 /* STA_CLOCKERR is never set yet */
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time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */
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#endif
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/* If there are input parameters, then process them */
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if (txc->modes)
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{
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if (txc->modes & ADJ_STATUS) /* only set allowed bits */
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time_status = (txc->status & ~STA_RONLY) |
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(time_status & STA_RONLY);
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if (txc->modes & ADJ_FREQUENCY) { /* p. 22 */
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if (txc->freq > MAXFREQ || txc->freq < -MAXFREQ) {
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result = -EINVAL;
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goto leave;
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}
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time_freq = txc->freq - pps_freq;
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}
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if (txc->modes & ADJ_MAXERROR) {
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if (txc->maxerror < 0 || txc->maxerror >= NTP_PHASE_LIMIT) {
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result = -EINVAL;
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goto leave;
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}
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time_maxerror = txc->maxerror;
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}
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if (txc->modes & ADJ_ESTERROR) {
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if (txc->esterror < 0 || txc->esterror >= NTP_PHASE_LIMIT) {
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result = -EINVAL;
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goto leave;
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}
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time_esterror = txc->esterror;
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}
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if (txc->modes & ADJ_TIMECONST) { /* p. 24 */
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if (txc->constant < 0) { /* NTP v4 uses values > 6 */
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result = -EINVAL;
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goto leave;
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}
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time_constant = txc->constant;
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}
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if (txc->modes & ADJ_OFFSET) { /* values checked earlier */
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if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
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/* adjtime() is independent from ntp_adjtime() */
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if ((time_next_adjust = txc->offset) == 0)
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time_adjust = 0;
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}
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else if ( time_status & (STA_PLL | STA_PPSTIME) ) {
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ltemp = (time_status & (STA_PPSTIME | STA_PPSSIGNAL)) ==
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(STA_PPSTIME | STA_PPSSIGNAL) ?
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pps_offset : txc->offset;
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/*
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* Scale the phase adjustment and
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* clamp to the operating range.
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*/
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if (ltemp > MAXPHASE)
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time_offset = MAXPHASE << SHIFT_UPDATE;
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else if (ltemp < -MAXPHASE)
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time_offset = -(MAXPHASE << SHIFT_UPDATE);
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else
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time_offset = ltemp << SHIFT_UPDATE;
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/*
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* Select whether the frequency is to be controlled
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* and in which mode (PLL or FLL). Clamp to the operating
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* range. Ugly multiply/divide should be replaced someday.
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*/
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if (time_status & STA_FREQHOLD || time_reftime == 0)
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time_reftime = xtime.tv_sec;
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mtemp = xtime.tv_sec - time_reftime;
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time_reftime = xtime.tv_sec;
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if (time_status & STA_FLL) {
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if (mtemp >= MINSEC) {
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ltemp = (time_offset / mtemp) << (SHIFT_USEC -
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SHIFT_UPDATE);
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if (ltemp < 0)
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time_freq -= -ltemp >> SHIFT_KH;
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else
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time_freq += ltemp >> SHIFT_KH;
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} else /* calibration interval too short (p. 12) */
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result = TIME_ERROR;
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} else { /* PLL mode */
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if (mtemp < MAXSEC) {
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ltemp *= mtemp;
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if (ltemp < 0)
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time_freq -= -ltemp >> (time_constant +
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time_constant +
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SHIFT_KF - SHIFT_USEC);
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else
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time_freq += ltemp >> (time_constant +
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time_constant +
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SHIFT_KF - SHIFT_USEC);
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} else /* calibration interval too long (p. 12) */
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result = TIME_ERROR;
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}
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if (time_freq > time_tolerance)
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time_freq = time_tolerance;
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else if (time_freq < -time_tolerance)
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time_freq = -time_tolerance;
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} /* STA_PLL || STA_PPSTIME */
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} /* txc->modes & ADJ_OFFSET */
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if (txc->modes & ADJ_TICK) {
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tick_usec = txc->tick;
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tick_nsec = TICK_USEC_TO_NSEC(tick_usec);
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}
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} /* txc->modes */
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leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0
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|| ((time_status & (STA_PPSFREQ|STA_PPSTIME)) != 0
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&& (time_status & STA_PPSSIGNAL) == 0)
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/* p. 24, (b) */
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|| ((time_status & (STA_PPSTIME|STA_PPSJITTER))
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== (STA_PPSTIME|STA_PPSJITTER))
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/* p. 24, (c) */
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|| ((time_status & STA_PPSFREQ) != 0
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&& (time_status & (STA_PPSWANDER|STA_PPSERROR)) != 0))
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/* p. 24, (d) */
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result = TIME_ERROR;
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if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
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txc->offset = save_adjust;
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else {
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if (time_offset < 0)
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txc->offset = -(-time_offset >> SHIFT_UPDATE);
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else
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txc->offset = time_offset >> SHIFT_UPDATE;
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}
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txc->freq = time_freq + pps_freq;
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txc->maxerror = time_maxerror;
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txc->esterror = time_esterror;
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txc->status = time_status;
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txc->constant = time_constant;
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txc->precision = time_precision;
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txc->tolerance = time_tolerance;
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txc->tick = tick_usec;
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txc->ppsfreq = pps_freq;
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txc->jitter = pps_jitter >> PPS_AVG;
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txc->shift = pps_shift;
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txc->stabil = pps_stabil;
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txc->jitcnt = pps_jitcnt;
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txc->calcnt = pps_calcnt;
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txc->errcnt = pps_errcnt;
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txc->stbcnt = pps_stbcnt;
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write_sequnlock_irq(&xtime_lock);
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do_gettimeofday(&txc->time);
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notify_arch_cmos_timer();
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return(result);
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}
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asmlinkage long sys_adjtimex(struct timex __user *txc_p)
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{
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struct timex txc; /* Local copy of parameter */
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int ret;
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/* Copy the user data space into the kernel copy
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* structure. But bear in mind that the structures
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* may change
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*/
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if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
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return -EFAULT;
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ret = do_adjtimex(&txc);
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return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
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}
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inline struct timespec current_kernel_time(void)
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{
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struct timespec now;
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unsigned long seq;
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do {
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seq = read_seqbegin(&xtime_lock);
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now = xtime;
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} while (read_seqretry(&xtime_lock, seq));
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return now;
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}
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EXPORT_SYMBOL(current_kernel_time);
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/**
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* current_fs_time - Return FS time
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* @sb: Superblock.
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*
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* Return the current time truncated to the time granuality supported by
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* the fs.
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*/
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struct timespec current_fs_time(struct super_block *sb)
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{
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struct timespec now = current_kernel_time();
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return timespec_trunc(now, sb->s_time_gran);
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}
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EXPORT_SYMBOL(current_fs_time);
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/**
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* timespec_trunc - Truncate timespec to a granuality
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* @t: Timespec
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* @gran: Granuality in ns.
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*
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* Truncate a timespec to a granuality. gran must be smaller than a second.
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* Always rounds down.
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*
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* This function should be only used for timestamps returned by
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* current_kernel_time() or CURRENT_TIME, not with do_gettimeofday() because
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* it doesn't handle the better resolution of the later.
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*/
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struct timespec timespec_trunc(struct timespec t, unsigned gran)
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{
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/*
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* Division is pretty slow so avoid it for common cases.
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* Currently current_kernel_time() never returns better than
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* jiffies resolution. Exploit that.
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*/
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if (gran <= jiffies_to_usecs(1) * 1000) {
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/* nothing */
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} else if (gran == 1000000000) {
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t.tv_nsec = 0;
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} else {
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t.tv_nsec -= t.tv_nsec % gran;
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}
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return t;
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}
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EXPORT_SYMBOL(timespec_trunc);
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#ifdef CONFIG_TIME_INTERPOLATION
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void getnstimeofday (struct timespec *tv)
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{
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unsigned long seq,sec,nsec;
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do {
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seq = read_seqbegin(&xtime_lock);
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sec = xtime.tv_sec;
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nsec = xtime.tv_nsec+time_interpolator_get_offset();
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} while (unlikely(read_seqretry(&xtime_lock, seq)));
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while (unlikely(nsec >= NSEC_PER_SEC)) {
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nsec -= NSEC_PER_SEC;
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++sec;
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}
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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
|
|
|
|
#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);
|
|
|