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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/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);
- }
- 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 granularity 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 granularity
- * @t: Timespec
- * @gran: Granularity in ns.
- *
- * Truncate a timespec to a granularity. 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
- #ifndef CONFIG_GENERIC_TIME
- /*
- * 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
- #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;
- }
- /*
- * Convert jiffies to milliseconds and back.
- *
- * Avoid unnecessary multiplications/divisions in the
- * two most common HZ cases:
- */
- unsigned int jiffies_to_msecs(const unsigned long j)
- {
- #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
- return (MSEC_PER_SEC / HZ) * j;
- #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
- return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
- #else
- return (j * MSEC_PER_SEC) / HZ;
- #endif
- }
- EXPORT_SYMBOL(jiffies_to_msecs);
- unsigned int jiffies_to_usecs(const unsigned long j)
- {
- #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
- return (USEC_PER_SEC / HZ) * j;
- #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
- return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC);
- #else
- return (j * USEC_PER_SEC) / HZ;
- #endif
- }
- EXPORT_SYMBOL(jiffies_to_usecs);
- /*
- * When we convert to jiffies then we interpret incoming values
- * the following way:
- *
- * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
- *
- * - 'too large' values [that would result in larger than
- * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
- *
- * - all other values are converted to jiffies by either multiplying
- * the input value by a factor or dividing it with a factor
- *
- * We must also be careful about 32-bit overflows.
- */
- unsigned long msecs_to_jiffies(const unsigned int m)
- {
- /*
- * Negative value, means infinite timeout:
- */
- if ((int)m < 0)
- return MAX_JIFFY_OFFSET;
- #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
- /*
- * HZ is equal to or smaller than 1000, and 1000 is a nice
- * round multiple of HZ, divide with the factor between them,
- * but round upwards:
- */
- return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);
- #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
- /*
- * HZ is larger than 1000, and HZ is a nice round multiple of
- * 1000 - simply multiply with the factor between them.
- *
- * But first make sure the multiplication result cannot
- * overflow:
- */
- if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
- return MAX_JIFFY_OFFSET;
- return m * (HZ / MSEC_PER_SEC);
- #else
- /*
- * Generic case - multiply, round and divide. But first
- * check that if we are doing a net multiplication, that
- * we wouldnt overflow:
- */
- if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
- return MAX_JIFFY_OFFSET;
- return (m * HZ + MSEC_PER_SEC - 1) / MSEC_PER_SEC;
- #endif
- }
- EXPORT_SYMBOL(msecs_to_jiffies);
- unsigned long usecs_to_jiffies(const unsigned int u)
- {
- if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
- return MAX_JIFFY_OFFSET;
- #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
- return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ);
- #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
- return u * (HZ / USEC_PER_SEC);
- #else
- return (u * HZ + USEC_PER_SEC - 1) / USEC_PER_SEC;
- #endif
- }
- EXPORT_SYMBOL(usecs_to_jiffies);
- /*
- * The TICK_NSEC - 1 rounds up the value to the next resolution. Note
- * that a remainder subtract here would not do the right thing as the
- * resolution values don't fall on second boundries. I.e. the line:
- * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding.
- *
- * Rather, we just shift the bits off the right.
- *
- * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
- * value to a scaled second value.
- */
- unsigned long
- timespec_to_jiffies(const struct timespec *value)
- {
- unsigned long sec = value->tv_sec;
- long nsec = value->tv_nsec + TICK_NSEC - 1;
- if (sec >= MAX_SEC_IN_JIFFIES){
- sec = MAX_SEC_IN_JIFFIES;
- nsec = 0;
- }
- return (((u64)sec * SEC_CONVERSION) +
- (((u64)nsec * NSEC_CONVERSION) >>
- (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
- }
- EXPORT_SYMBOL(timespec_to_jiffies);
- void
- jiffies_to_timespec(const unsigned long jiffies, struct timespec *value)
- {
- /*
- * Convert jiffies to nanoseconds and separate with
- * one divide.
- */
- u64 nsec = (u64)jiffies * TICK_NSEC;
- value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &value->tv_nsec);
- }
- EXPORT_SYMBOL(jiffies_to_timespec);
- /* Same for "timeval"
- *
- * Well, almost. The problem here is that the real system resolution is
- * in nanoseconds and the value being converted is in micro seconds.
- * Also for some machines (those that use HZ = 1024, in-particular),
- * there is a LARGE error in the tick size in microseconds.
- * The solution we use is to do the rounding AFTER we convert the
- * microsecond part. Thus the USEC_ROUND, the bits to be shifted off.
- * Instruction wise, this should cost only an additional add with carry
- * instruction above the way it was done above.
- */
- unsigned long
- timeval_to_jiffies(const struct timeval *value)
- {
- unsigned long sec = value->tv_sec;
- long usec = value->tv_usec;
- if (sec >= MAX_SEC_IN_JIFFIES){
- sec = MAX_SEC_IN_JIFFIES;
- usec = 0;
- }
- return (((u64)sec * SEC_CONVERSION) +
- (((u64)usec * USEC_CONVERSION + USEC_ROUND) >>
- (USEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
- }
- EXPORT_SYMBOL(timeval_to_jiffies);
- void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value)
- {
- /*
- * Convert jiffies to nanoseconds and separate with
- * one divide.
- */
- u64 nsec = (u64)jiffies * TICK_NSEC;
- long tv_usec;
- value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &tv_usec);
- tv_usec /= NSEC_PER_USEC;
- value->tv_usec = tv_usec;
- }
- EXPORT_SYMBOL(jiffies_to_timeval);
- /*
- * Convert jiffies/jiffies_64 to clock_t and back.
- */
- clock_t jiffies_to_clock_t(long x)
- {
- #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
- return x / (HZ / USER_HZ);
- #else
- u64 tmp = (u64)x * TICK_NSEC;
- do_div(tmp, (NSEC_PER_SEC / USER_HZ));
- return (long)tmp;
- #endif
- }
- EXPORT_SYMBOL(jiffies_to_clock_t);
- unsigned long clock_t_to_jiffies(unsigned long x)
- {
- #if (HZ % USER_HZ)==0
- if (x >= ~0UL / (HZ / USER_HZ))
- return ~0UL;
- return x * (HZ / USER_HZ);
- #else
- u64 jif;
- /* Don't worry about loss of precision here .. */
- if (x >= ~0UL / HZ * USER_HZ)
- return ~0UL;
- /* .. but do try to contain it here */
- jif = x * (u64) HZ;
- do_div(jif, USER_HZ);
- return jif;
- #endif
- }
- EXPORT_SYMBOL(clock_t_to_jiffies);
- u64 jiffies_64_to_clock_t(u64 x)
- {
- #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
- do_div(x, HZ / USER_HZ);
- #else
- /*
- * There are better ways that don't overflow early,
- * but even this doesn't overflow in hundreds of years
- * in 64 bits, so..
- */
- x *= TICK_NSEC;
- do_div(x, (NSEC_PER_SEC / USER_HZ));
- #endif
- return x;
- }
- EXPORT_SYMBOL(jiffies_64_to_clock_t);
- u64 nsec_to_clock_t(u64 x)
- {
- #if (NSEC_PER_SEC % USER_HZ) == 0
- do_div(x, (NSEC_PER_SEC / USER_HZ));
- #elif (USER_HZ % 512) == 0
- x *= USER_HZ/512;
- do_div(x, (NSEC_PER_SEC / 512));
- #else
- /*
- * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
- * overflow after 64.99 years.
- * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
- */
- x *= 9;
- do_div(x, (unsigned long)((9ull * NSEC_PER_SEC + (USER_HZ/2)) /
- USER_HZ));
- #endif
- return x;
- }
- #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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