forked from KolibriOS/kolibrios
598 lines
17 KiB
C
598 lines
17 KiB
C
/*
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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/core.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/jiffies.h>
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#include <linux/errno.h>
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#include <linux/math64.h>
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#define HZ_TO_MSEC_MUL32 0xA0000000
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#define HZ_TO_MSEC_ADJ32 0x0
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#define HZ_TO_MSEC_SHR32 28
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#define HZ_TO_MSEC_MUL64 0xA000000000000000
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#define HZ_TO_MSEC_ADJ64 0x0
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#define HZ_TO_MSEC_SHR64 60
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#define MSEC_TO_HZ_MUL32 0xCCCCCCCD
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#define MSEC_TO_HZ_ADJ32 0x733333333
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#define MSEC_TO_HZ_SHR32 35
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#define MSEC_TO_HZ_MUL64 0xCCCCCCCCCCCCCCCD
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#define MSEC_TO_HZ_ADJ64 0x73333333333333333
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#define MSEC_TO_HZ_SHR64 67
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#define HZ_TO_MSEC_NUM 10
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#define HZ_TO_MSEC_DEN 1
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#define MSEC_TO_HZ_NUM 1
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#define MSEC_TO_HZ_DEN 10
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#define HZ_TO_USEC_MUL32 0x9C400000
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#define HZ_TO_USEC_ADJ32 0x0
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#define HZ_TO_USEC_SHR32 18
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#define HZ_TO_USEC_MUL64 0x9C40000000000000
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#define HZ_TO_USEC_ADJ64 0x0
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#define HZ_TO_USEC_SHR64 50
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#define USEC_TO_HZ_MUL32 0xD1B71759
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#define USEC_TO_HZ_ADJ32 0x1FFF2E48E8A7
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#define USEC_TO_HZ_SHR32 45
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#define USEC_TO_HZ_MUL64 0xD1B71758E219652C
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#define USEC_TO_HZ_ADJ64 0x1FFF2E48E8A71DE69AD4
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#define USEC_TO_HZ_SHR64 77
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#define HZ_TO_USEC_NUM 10000
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#define HZ_TO_USEC_DEN 1
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#define USEC_TO_HZ_NUM 1
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#define USEC_TO_HZ_DEN 10000
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#define MSEC_PER_SEC 1000L
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#define USEC_PER_MSEC 1000L
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#define NSEC_PER_USEC 1000L
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#define NSEC_PER_MSEC 1000000L
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#define USEC_PER_SEC 1000000L
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#define NSEC_PER_SEC 1000000000L
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#define FSEC_PER_SEC 1000000000000000LL
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# define USER_HZ 100
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/*
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* Convert jiffies to milliseconds and back.
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*
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* Avoid unnecessary multiplications/divisions in the
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* two most common HZ cases:
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*/
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unsigned int jiffies_to_msecs(const unsigned long j)
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{
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#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
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return (MSEC_PER_SEC / HZ) * j;
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#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
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return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
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#else
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# if BITS_PER_LONG == 32
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return (HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32;
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# else
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return (j * HZ_TO_MSEC_NUM) / HZ_TO_MSEC_DEN;
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# endif
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#endif
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}
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EXPORT_SYMBOL(jiffies_to_msecs);
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unsigned int jiffies_to_usecs(const unsigned long j)
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{
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#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
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return (USEC_PER_SEC / HZ) * j;
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#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
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return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC);
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#else
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# if BITS_PER_LONG == 32
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return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32;
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# else
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return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN;
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# endif
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#endif
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}
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EXPORT_SYMBOL(jiffies_to_usecs);
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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. Always rounds down. gran must
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* not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns).
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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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/* Avoid division in the common cases 1 ns and 1 s. */
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if (gran == 1) {
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/* nothing */
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} else if (gran == NSEC_PER_SEC) {
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t.tv_nsec = 0;
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} else if (gran > 1 && gran < NSEC_PER_SEC) {
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t.tv_nsec -= t.tv_nsec % gran;
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} else {
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WARN(1, "illegal file time granularity: %u", 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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/*
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* mktime64 - Converts date to seconds.
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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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time64_t mktime64(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 ((((time64_t)
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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(mktime64);
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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, s64 nsec)
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{
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while (nsec >= NSEC_PER_SEC) {
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/*
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* The following asm() prevents the compiler from
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* optimising this loop into a modulo operation. See
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* also __iter_div_u64_rem() in include/linux/time.h
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*/
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asm("" : "+rm"(nsec));
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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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asm("" : "+rm"(nsec));
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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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EXPORT_SYMBOL(set_normalized_timespec);
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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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s32 rem;
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if (!nsec)
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return (struct timespec) {0, 0};
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ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
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if (unlikely(rem < 0)) {
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ts.tv_sec--;
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rem += NSEC_PER_SEC;
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}
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ts.tv_nsec = rem;
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return ts;
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}
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EXPORT_SYMBOL(ns_to_timespec);
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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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EXPORT_SYMBOL(ns_to_timeval);
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#if BITS_PER_LONG == 32
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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_timespec64(struct timespec64 *ts, time64_t sec, s64 nsec)
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{
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while (nsec >= NSEC_PER_SEC) {
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/*
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* The following asm() prevents the compiler from
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* optimising this loop into a modulo operation. See
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* also __iter_div_u64_rem() in include/linux/time.h
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*/
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asm("" : "+rm"(nsec));
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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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asm("" : "+rm"(nsec));
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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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EXPORT_SYMBOL(set_normalized_timespec64);
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/**
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* ns_to_timespec64 - Convert nanoseconds to timespec64
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* @nsec: the nanoseconds value to be converted
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*
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* Returns the timespec64 representation of the nsec parameter.
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*/
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struct timespec64 ns_to_timespec64(const s64 nsec)
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{
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struct timespec64 ts;
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s32 rem;
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if (!nsec)
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return (struct timespec64) {0, 0};
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ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
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if (unlikely(rem < 0)) {
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ts.tv_sec--;
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rem += NSEC_PER_SEC;
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}
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ts.tv_nsec = rem;
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return ts;
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}
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EXPORT_SYMBOL(ns_to_timespec64);
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#endif
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/**
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* msecs_to_jiffies: - convert milliseconds to jiffies
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* @m: time in milliseconds
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*
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* conversion is done as follows:
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*
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* - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
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*
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* - 'too large' values [that would result in larger than
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* MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
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*
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* - all other values are converted to jiffies by either multiplying
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* the input value by a factor or dividing it with a factor and
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* handling any 32-bit overflows.
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* for the details see __msecs_to_jiffies()
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*
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* msecs_to_jiffies() checks for the passed in value being a constant
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* via __builtin_constant_p() allowing gcc to eliminate most of the
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* code, __msecs_to_jiffies() is called if the value passed does not
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* allow constant folding and the actual conversion must be done at
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* runtime.
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* the _msecs_to_jiffies helpers are the HZ dependent conversion
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* routines found in include/linux/jiffies.h
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*/
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unsigned long __msecs_to_jiffies(const unsigned int m)
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{
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/*
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* Negative value, means infinite timeout:
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*/
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if ((int)m < 0)
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return MAX_JIFFY_OFFSET;
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return _msecs_to_jiffies(m);
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}
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EXPORT_SYMBOL(__msecs_to_jiffies);
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unsigned long __usecs_to_jiffies(const unsigned int u)
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{
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if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
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return MAX_JIFFY_OFFSET;
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return _usecs_to_jiffies(u);
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}
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EXPORT_SYMBOL(__usecs_to_jiffies);
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/*
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* The TICK_NSEC - 1 rounds up the value to the next resolution. Note
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* that a remainder subtract here would not do the right thing as the
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* resolution values don't fall on second boundries. I.e. the line:
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* nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding.
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* Note that due to the small error in the multiplier here, this
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* rounding is incorrect for sufficiently large values of tv_nsec, but
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* well formed timespecs should have tv_nsec < NSEC_PER_SEC, so we're
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* OK.
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*
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* Rather, we just shift the bits off the right.
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*
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* The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
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* value to a scaled second value.
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*/
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static unsigned long
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__timespec64_to_jiffies(u64 sec, long nsec)
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{
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nsec = nsec + TICK_NSEC - 1;
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if (sec >= MAX_SEC_IN_JIFFIES){
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sec = MAX_SEC_IN_JIFFIES;
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nsec = 0;
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}
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return ((sec * SEC_CONVERSION) +
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(((u64)nsec * NSEC_CONVERSION) >>
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(NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
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}
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static unsigned long
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__timespec_to_jiffies(unsigned long sec, long nsec)
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{
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return __timespec64_to_jiffies((u64)sec, nsec);
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}
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unsigned long
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timespec64_to_jiffies(const struct timespec64 *value)
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{
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return __timespec64_to_jiffies(value->tv_sec, value->tv_nsec);
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}
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EXPORT_SYMBOL(timespec64_to_jiffies);
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void
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jiffies_to_timespec64(const unsigned long jiffies, struct timespec64 *value)
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{
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/*
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* Convert jiffies to nanoseconds and separate with
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* one divide.
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*/
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u32 rem;
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value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
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NSEC_PER_SEC, &rem);
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value->tv_nsec = rem;
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}
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EXPORT_SYMBOL(jiffies_to_timespec64);
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/*
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* We could use a similar algorithm to timespec_to_jiffies (with a
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* different multiplier for usec instead of nsec). But this has a
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* problem with rounding: we can't exactly add TICK_NSEC - 1 to the
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* usec value, since it's not necessarily integral.
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*
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* We could instead round in the intermediate scaled representation
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* (i.e. in units of 1/2^(large scale) jiffies) but that's also
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* perilous: the scaling introduces a small positive error, which
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* combined with a division-rounding-upward (i.e. adding 2^(scale) - 1
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* units to the intermediate before shifting) leads to accidental
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* overflow and overestimates.
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*
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* At the cost of one additional multiplication by a constant, just
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* use the timespec implementation.
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*/
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unsigned long
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timeval_to_jiffies(const struct timeval *value)
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{
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return __timespec_to_jiffies(value->tv_sec,
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value->tv_usec * NSEC_PER_USEC);
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}
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EXPORT_SYMBOL(timeval_to_jiffies);
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void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value)
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{
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/*
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* Convert jiffies to nanoseconds and separate with
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* one divide.
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*/
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u32 rem;
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value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
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NSEC_PER_SEC, &rem);
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value->tv_usec = rem / NSEC_PER_USEC;
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}
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EXPORT_SYMBOL(jiffies_to_timeval);
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/*
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* Convert jiffies/jiffies_64 to clock_t and back.
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*/
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clock_t jiffies_to_clock_t(unsigned long x)
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{
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#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
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# if HZ < USER_HZ
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return x * (USER_HZ / HZ);
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# else
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return x / (HZ / USER_HZ);
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# endif
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#else
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return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
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#endif
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}
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EXPORT_SYMBOL(jiffies_to_clock_t);
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unsigned long clock_t_to_jiffies(unsigned long x)
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{
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#if (HZ % USER_HZ)==0
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if (x >= ~0UL / (HZ / USER_HZ))
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return ~0UL;
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return x * (HZ / USER_HZ);
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#else
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/* Don't worry about loss of precision here .. */
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if (x >= ~0UL / HZ * USER_HZ)
|
|
return ~0UL;
|
|
|
|
/* .. but do try to contain it here */
|
|
return div_u64((u64)x * HZ, USER_HZ);
|
|
#endif
|
|
}
|
|
EXPORT_SYMBOL(clock_t_to_jiffies);
|
|
|
|
u64 jiffies_64_to_clock_t(u64 x)
|
|
{
|
|
#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
|
|
# if HZ < USER_HZ
|
|
x = div_u64(x * USER_HZ, HZ);
|
|
# elif HZ > USER_HZ
|
|
x = div_u64(x, HZ / USER_HZ);
|
|
# else
|
|
/* Nothing to do */
|
|
# endif
|
|
#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 = div_u64(x * TICK_NSEC, (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
|
|
return div_u64(x, NSEC_PER_SEC / USER_HZ);
|
|
#elif (USER_HZ % 512) == 0
|
|
return div_u64(x * USER_HZ / 512, 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, ...
|
|
*/
|
|
return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ);
|
|
#endif
|
|
}
|
|
|
|
/**
|
|
* nsecs_to_jiffies64 - Convert nsecs in u64 to jiffies64
|
|
*
|
|
* @n: nsecs in u64
|
|
*
|
|
* Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
|
|
* And this doesn't return MAX_JIFFY_OFFSET since this function is designed
|
|
* for scheduler, not for use in device drivers to calculate timeout value.
|
|
*
|
|
* note:
|
|
* NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
|
|
* ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
|
|
*/
|
|
u64 nsecs_to_jiffies64(u64 n)
|
|
{
|
|
#if (NSEC_PER_SEC % HZ) == 0
|
|
/* Common case, HZ = 100, 128, 200, 250, 256, 500, 512, 1000 etc. */
|
|
return div_u64(n, NSEC_PER_SEC / HZ);
|
|
#elif (HZ % 512) == 0
|
|
/* overflow after 292 years if HZ = 1024 */
|
|
return div_u64(n * HZ / 512, NSEC_PER_SEC / 512);
|
|
#else
|
|
/*
|
|
* Generic case - optimized for cases where HZ is a multiple of 3.
|
|
* overflow after 64.99 years, exact for HZ = 60, 72, 90, 120 etc.
|
|
*/
|
|
return div_u64(n * 9, (9ull * NSEC_PER_SEC + HZ / 2) / HZ);
|
|
#endif
|
|
}
|
|
EXPORT_SYMBOL(nsecs_to_jiffies64);
|
|
|
|
/**
|
|
* nsecs_to_jiffies - Convert nsecs in u64 to jiffies
|
|
*
|
|
* @n: nsecs in u64
|
|
*
|
|
* Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
|
|
* And this doesn't return MAX_JIFFY_OFFSET since this function is designed
|
|
* for scheduler, not for use in device drivers to calculate timeout value.
|
|
*
|
|
* note:
|
|
* NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
|
|
* ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
|
|
*/
|
|
unsigned long nsecs_to_jiffies(u64 n)
|
|
{
|
|
return (unsigned long)nsecs_to_jiffies64(n);
|
|
}
|
|
EXPORT_SYMBOL_GPL(nsecs_to_jiffies);
|
|
|
|
/*
|
|
* Add two timespec values and do a safety check for overflow.
|
|
* It's assumed that both values are valid (>= 0)
|
|
*/
|
|
struct timespec timespec_add_safe(const struct timespec lhs,
|
|
const struct timespec rhs)
|
|
{
|
|
struct timespec res;
|
|
|
|
set_normalized_timespec(&res, lhs.tv_sec + rhs.tv_sec,
|
|
lhs.tv_nsec + rhs.tv_nsec);
|
|
|
|
if (res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec)
|
|
res.tv_sec = TIME_T_MAX;
|
|
|
|
return res;
|
|
}
|
|
|
|
|
|
|
|
|