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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/clocksource.h>

#include <linux/errno.h>

#include <linux/syscalls.h>

#include <linux/security.h>

#include <linux/fs.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 = get_seconds();

        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;

        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;

                update_vsyscall_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;

}

/**

 * 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);

/*

 * Convert jiffies to milliseconds and back.

 *

 * Avoid unnecessary multiplications/divisions in the

 * two most common HZ cases:

 */

unsigned int inline 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 inline 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);

/**

 * 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);

#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

/* 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;

}

EXPORT_SYMBOL(ns_to_timespec);

/**

 * 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;

}

EXPORT_SYMBOL(ns_to_timeval);

/*

 * 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);