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489 lines
12 KiB
489 lines
12 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/capability.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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if (tv && !timespec_valid(tv))
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return -EINVAL;
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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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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 granularity 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 granularity
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* @t: Timespec
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* @gran: Granularity in ns.
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*
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* Truncate a timespec to a granularity. 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;
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tv->tv_nsec = nsec;
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}
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EXPORT_SYMBOL_GPL(getnstimeofday);
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int do_settimeofday (struct timespec *tv)
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{
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time_t wtm_sec, sec = tv->tv_sec;
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long wtm_nsec, nsec = tv->tv_nsec;
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if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
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return -EINVAL;
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write_seqlock_irq(&xtime_lock);
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{
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wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
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wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
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set_normalized_timespec(&xtime, sec, nsec);
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set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
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time_adjust = 0; /* stop active adjtime() */
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time_status |= STA_UNSYNC;
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time_maxerror = NTP_PHASE_LIMIT;
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time_esterror = NTP_PHASE_LIMIT;
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time_interpolator_reset();
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}
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write_sequnlock_irq(&xtime_lock);
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clock_was_set();
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return 0;
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}
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EXPORT_SYMBOL(do_settimeofday);
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void do_gettimeofday (struct timeval *tv)
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{
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unsigned long seq, nsec, usec, sec, offset;
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do {
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seq = read_seqbegin(&xtime_lock);
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offset = time_interpolator_get_offset();
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sec = xtime.tv_sec;
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nsec = xtime.tv_nsec;
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} while (unlikely(read_seqretry(&xtime_lock, seq)));
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usec = (nsec + offset) / 1000;
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while (unlikely(usec >= USEC_PER_SEC)) {
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usec -= USEC_PER_SEC;
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++sec;
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}
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tv->tv_sec = sec;
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tv->tv_usec = usec;
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}
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EXPORT_SYMBOL(do_gettimeofday);
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#else
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#ifndef CONFIG_GENERIC_TIME
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/*
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* Simulate gettimeofday using do_gettimeofday which only allows a timeval
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* and therefore only yields usec accuracy
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*/
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void getnstimeofday(struct timespec *tv)
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{
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struct timeval x;
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do_gettimeofday(&x);
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tv->tv_sec = x.tv_sec;
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tv->tv_nsec = x.tv_usec * NSEC_PER_USEC;
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}
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EXPORT_SYMBOL_GPL(getnstimeofday);
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#endif
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#endif
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/* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
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* Assumes input in normal date format, i.e. 1980-12-31 23:59:59
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* => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
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*
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* [For the Julian calendar (which was used in Russia before 1917,
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* Britain & colonies before 1752, anywhere else before 1582,
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* and is still in use by some communities) leave out the
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* -year/100+year/400 terms, and add 10.]
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*
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* This algorithm was first published by Gauss (I think).
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*
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* WARNING: this function will overflow on 2106-02-07 06:28:16 on
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* machines were long is 32-bit! (However, as time_t is signed, we
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* will already get problems at other places on 2038-01-19 03:14:08)
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*/
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unsigned long
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mktime(const unsigned int year0, const unsigned int mon0,
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const unsigned int day, const unsigned int hour,
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const unsigned int min, const unsigned int sec)
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{
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unsigned int mon = mon0, year = year0;
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/* 1..12 -> 11,12,1..10 */
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if (0 >= (int) (mon -= 2)) {
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mon += 12; /* Puts Feb last since it has leap day */
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year -= 1;
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}
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return ((((unsigned long)
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(year/4 - year/100 + year/400 + 367*mon/12 + day) +
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year*365 - 719499
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)*24 + hour /* now have hours */
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)*60 + min /* now have minutes */
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)*60 + sec; /* finally seconds */
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}
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EXPORT_SYMBOL(mktime);
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/**
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* set_normalized_timespec - set timespec sec and nsec parts and normalize
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*
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* @ts: pointer to timespec variable to be set
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* @sec: seconds to set
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* @nsec: nanoseconds to set
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*
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* Set seconds and nanoseconds field of a timespec variable and
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* normalize to the timespec storage format
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*
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* Note: The tv_nsec part is always in the range of
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* 0 <= tv_nsec < NSEC_PER_SEC
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* For negative values only the tv_sec field is negative !
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*/
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void set_normalized_timespec(struct timespec *ts, time_t sec, long nsec)
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{
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while (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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while (nsec < 0) {
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nsec += NSEC_PER_SEC;
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--sec;
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}
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ts->tv_sec = sec;
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ts->tv_nsec = nsec;
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}
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/**
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* ns_to_timespec - Convert nanoseconds to timespec
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* @nsec: the nanoseconds value to be converted
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*
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* Returns the timespec representation of the nsec parameter.
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*/
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struct timespec ns_to_timespec(const s64 nsec)
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{
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struct timespec ts;
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if (!nsec)
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return (struct timespec) {0, 0};
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ts.tv_sec = div_long_long_rem_signed(nsec, NSEC_PER_SEC, &ts.tv_nsec);
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if (unlikely(nsec < 0))
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set_normalized_timespec(&ts, ts.tv_sec, ts.tv_nsec);
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return ts;
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}
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/**
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* ns_to_timeval - Convert nanoseconds to timeval
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* @nsec: the nanoseconds value to be converted
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*
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* Returns the timeval representation of the nsec parameter.
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*/
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struct timeval ns_to_timeval(const s64 nsec)
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{
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struct timespec ts = ns_to_timespec(nsec);
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struct timeval tv;
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tv.tv_sec = ts.tv_sec;
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tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000;
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return tv;
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}
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#if (BITS_PER_LONG < 64)
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u64 get_jiffies_64(void)
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{
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unsigned long seq;
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u64 ret;
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do {
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seq = read_seqbegin(&xtime_lock);
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ret = jiffies_64;
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} while (read_seqretry(&xtime_lock, seq));
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return ret;
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}
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EXPORT_SYMBOL(get_jiffies_64);
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#endif
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EXPORT_SYMBOL(jiffies);
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