FreeBSD-5.3/sys/kern/kern_time.c
/*
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)kern_time.c 8.1 (Berkeley) 6/10/93
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/sys/kern/kern_time.c,v 1.108 2004/06/21 22:34:57 kbyanc Exp $");
#include "opt_mac.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sysproto.h>
#include <sys/resourcevar.h>
#include <sys/signalvar.h>
#include <sys/kernel.h>
#include <sys/mac.h>
#include <sys/sysent.h>
#include <sys/proc.h>
#include <sys/time.h>
#include <sys/timetc.h>
#include <sys/vnode.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
int tz_minuteswest;
int tz_dsttime;
/*
* Time of day and interval timer support.
*
* These routines provide the kernel entry points to get and set
* the time-of-day and per-process interval timers. Subroutines
* here provide support for adding and subtracting timeval structures
* and decrementing interval timers, optionally reloading the interval
* timers when they expire.
*/
static int nanosleep1(struct thread *td, struct timespec *rqt,
struct timespec *rmt);
static int settime(struct thread *, struct timeval *);
static void timevalfix(struct timeval *);
static void no_lease_updatetime(int);
static void
no_lease_updatetime(deltat)
int deltat;
{
}
void (*lease_updatetime)(int) = no_lease_updatetime;
static int
settime(struct thread *td, struct timeval *tv)
{
struct timeval delta, tv1, tv2;
static struct timeval maxtime, laststep;
struct timespec ts;
int s;
s = splclock();
microtime(&tv1);
delta = *tv;
timevalsub(&delta, &tv1);
/*
* If the system is secure, we do not allow the time to be
* set to a value earlier than 1 second less than the highest
* time we have yet seen. The worst a miscreant can do in
* this circumstance is "freeze" time. He couldn't go
* back to the past.
*
* We similarly do not allow the clock to be stepped more
* than one second, nor more than once per second. This allows
* a miscreant to make the clock march double-time, but no worse.
*/
if (securelevel_gt(td->td_ucred, 1) != 0) {
if (delta.tv_sec < 0 || delta.tv_usec < 0) {
/*
* Update maxtime to latest time we've seen.
*/
if (tv1.tv_sec > maxtime.tv_sec)
maxtime = tv1;
tv2 = *tv;
timevalsub(&tv2, &maxtime);
if (tv2.tv_sec < -1) {
tv->tv_sec = maxtime.tv_sec - 1;
printf("Time adjustment clamped to -1 second\n");
}
} else {
if (tv1.tv_sec == laststep.tv_sec) {
splx(s);
return (EPERM);
}
if (delta.tv_sec > 1) {
tv->tv_sec = tv1.tv_sec + 1;
printf("Time adjustment clamped to +1 second\n");
}
laststep = *tv;
}
}
ts.tv_sec = tv->tv_sec;
ts.tv_nsec = tv->tv_usec * 1000;
mtx_lock(&Giant);
tc_setclock(&ts);
(void) splsoftclock();
lease_updatetime(delta.tv_sec);
splx(s);
resettodr();
mtx_unlock(&Giant);
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct clock_gettime_args {
clockid_t clock_id;
struct timespec *tp;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
clock_gettime(struct thread *td, struct clock_gettime_args *uap)
{
struct timespec ats;
struct timeval sys, user;
switch (uap->clock_id) {
case CLOCK_REALTIME:
nanotime(&ats);
break;
case CLOCK_VIRTUAL:
mtx_lock_spin(&sched_lock);
calcru(td->td_proc, &user, &sys, NULL);
mtx_unlock_spin(&sched_lock);
TIMEVAL_TO_TIMESPEC(&user, &ats);
break;
case CLOCK_PROF:
mtx_lock_spin(&sched_lock);
calcru(td->td_proc, &user, &sys, NULL);
mtx_unlock_spin(&sched_lock);
timevaladd(&user, &sys);
TIMEVAL_TO_TIMESPEC(&user, &ats);
break;
case CLOCK_MONOTONIC:
nanouptime(&ats);
break;
default:
return (EINVAL);
}
return (copyout(&ats, uap->tp, sizeof(ats)));
}
#ifndef _SYS_SYSPROTO_H_
struct clock_settime_args {
clockid_t clock_id;
const struct timespec *tp;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
clock_settime(struct thread *td, struct clock_settime_args *uap)
{
struct timeval atv;
struct timespec ats;
int error;
#ifdef MAC
error = mac_check_system_settime(td->td_ucred);
if (error)
return (error);
#endif
if ((error = suser(td)) != 0)
return (error);
if (uap->clock_id != CLOCK_REALTIME)
return (EINVAL);
if ((error = copyin(uap->tp, &ats, sizeof(ats))) != 0)
return (error);
if (ats.tv_nsec < 0 || ats.tv_nsec >= 1000000000)
return (EINVAL);
/* XXX Don't convert nsec->usec and back */
TIMESPEC_TO_TIMEVAL(&atv, &ats);
error = settime(td, &atv);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct clock_getres_args {
clockid_t clock_id;
struct timespec *tp;
};
#endif
int
clock_getres(struct thread *td, struct clock_getres_args *uap)
{
struct timespec ts;
ts.tv_sec = 0;
switch (uap->clock_id) {
case CLOCK_REALTIME:
case CLOCK_MONOTONIC:
/*
* Round up the result of the division cheaply by adding 1.
* Rounding up is especially important if rounding down
* would give 0. Perfect rounding is unimportant.
*/
ts.tv_nsec = 1000000000 / tc_getfrequency() + 1;
break;
case CLOCK_VIRTUAL:
case CLOCK_PROF:
/* Accurately round up here because we can do so cheaply. */
ts.tv_nsec = (1000000000 + hz - 1) / hz;
break;
default:
return (EINVAL);
}
if (uap->tp == NULL)
return (0);
return (copyout(&ts, uap->tp, sizeof(ts)));
}
static int nanowait;
static int
nanosleep1(struct thread *td, struct timespec *rqt, struct timespec *rmt)
{
struct timespec ts, ts2, ts3;
struct timeval tv;
int error;
if (rqt->tv_nsec < 0 || rqt->tv_nsec >= 1000000000)
return (EINVAL);
if (rqt->tv_sec < 0 || (rqt->tv_sec == 0 && rqt->tv_nsec == 0))
return (0);
getnanouptime(&ts);
timespecadd(&ts, rqt);
TIMESPEC_TO_TIMEVAL(&tv, rqt);
for (;;) {
error = tsleep(&nanowait, PWAIT | PCATCH, "nanslp",
tvtohz(&tv));
getnanouptime(&ts2);
if (error != EWOULDBLOCK) {
if (error == ERESTART)
error = EINTR;
if (rmt != NULL) {
timespecsub(&ts, &ts2);
if (ts.tv_sec < 0)
timespecclear(&ts);
*rmt = ts;
}
return (error);
}
if (timespeccmp(&ts2, &ts, >=))
return (0);
ts3 = ts;
timespecsub(&ts3, &ts2);
TIMESPEC_TO_TIMEVAL(&tv, &ts3);
}
}
#ifndef _SYS_SYSPROTO_H_
struct nanosleep_args {
struct timespec *rqtp;
struct timespec *rmtp;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
nanosleep(struct thread *td, struct nanosleep_args *uap)
{
struct timespec rmt, rqt;
int error;
error = copyin(uap->rqtp, &rqt, sizeof(rqt));
if (error)
return (error);
if (uap->rmtp &&
!useracc((caddr_t)uap->rmtp, sizeof(rmt), VM_PROT_WRITE))
return (EFAULT);
error = nanosleep1(td, &rqt, &rmt);
if (error && uap->rmtp) {
int error2;
error2 = copyout(&rmt, uap->rmtp, sizeof(rmt));
if (error2)
error = error2;
}
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct gettimeofday_args {
struct timeval *tp;
struct timezone *tzp;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
gettimeofday(struct thread *td, struct gettimeofday_args *uap)
{
struct timeval atv;
struct timezone rtz;
int error = 0;
if (uap->tp) {
microtime(&atv);
error = copyout(&atv, uap->tp, sizeof (atv));
}
if (error == 0 && uap->tzp != NULL) {
rtz.tz_minuteswest = tz_minuteswest;
rtz.tz_dsttime = tz_dsttime;
error = copyout(&rtz, uap->tzp, sizeof (rtz));
}
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct settimeofday_args {
struct timeval *tv;
struct timezone *tzp;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
settimeofday(struct thread *td, struct settimeofday_args *uap)
{
struct timeval atv;
struct timezone atz;
int error = 0;
#ifdef MAC
error = mac_check_system_settime(td->td_ucred);
if (error)
return (error);
#endif
if ((error = suser(td)))
return (error);
/* Verify all parameters before changing time. */
if (uap->tv) {
if ((error = copyin(uap->tv, &atv, sizeof(atv))))
return (error);
if (atv.tv_usec < 0 || atv.tv_usec >= 1000000)
return (EINVAL);
}
if (uap->tzp &&
(error = copyin(uap->tzp, &atz, sizeof(atz))))
return (error);
if (uap->tv && (error = settime(td, &atv)))
return (error);
if (uap->tzp) {
tz_minuteswest = atz.tz_minuteswest;
tz_dsttime = atz.tz_dsttime;
}
return (error);
}
/*
* Get value of an interval timer. The process virtual and
* profiling virtual time timers are kept in the p_stats area, since
* they can be swapped out. These are kept internally in the
* way they are specified externally: in time until they expire.
*
* The real time interval timer is kept in the process table slot
* for the process, and its value (it_value) is kept as an
* absolute time rather than as a delta, so that it is easy to keep
* periodic real-time signals from drifting.
*
* Virtual time timers are processed in the hardclock() routine of
* kern_clock.c. The real time timer is processed by a timeout
* routine, called from the softclock() routine. Since a callout
* may be delayed in real time due to interrupt processing in the system,
* it is possible for the real time timeout routine (realitexpire, given below),
* to be delayed in real time past when it is supposed to occur. It
* does not suffice, therefore, to reload the real timer .it_value from the
* real time timers .it_interval. Rather, we compute the next time in
* absolute time the timer should go off.
*/
#ifndef _SYS_SYSPROTO_H_
struct getitimer_args {
u_int which;
struct itimerval *itv;
};
#endif
/*
* MPSAFE
*/
int
getitimer(struct thread *td, struct getitimer_args *uap)
{
struct proc *p = td->td_proc;
struct timeval ctv;
struct itimerval aitv;
if (uap->which > ITIMER_PROF)
return (EINVAL);
if (uap->which == ITIMER_REAL) {
/*
* Convert from absolute to relative time in .it_value
* part of real time timer. If time for real time timer
* has passed return 0, else return difference between
* current time and time for the timer to go off.
*/
PROC_LOCK(p);
aitv = p->p_realtimer;
PROC_UNLOCK(p);
if (timevalisset(&aitv.it_value)) {
getmicrouptime(&ctv);
if (timevalcmp(&aitv.it_value, &ctv, <))
timevalclear(&aitv.it_value);
else
timevalsub(&aitv.it_value, &ctv);
}
} else {
mtx_lock_spin(&sched_lock);
aitv = p->p_stats->p_timer[uap->which];
mtx_unlock_spin(&sched_lock);
}
return (copyout(&aitv, uap->itv, sizeof (struct itimerval)));
}
#ifndef _SYS_SYSPROTO_H_
struct setitimer_args {
u_int which;
struct itimerval *itv, *oitv;
};
#endif
/*
* MPSAFE
*/
int
setitimer(struct thread *td, struct setitimer_args *uap)
{
struct proc *p = td->td_proc;
struct itimerval aitv, oitv;
struct timeval ctv;
int error;
if (uap->itv == NULL) {
uap->itv = uap->oitv;
return (getitimer(td, (struct getitimer_args *)uap));
}
if (uap->which > ITIMER_PROF)
return (EINVAL);
if ((error = copyin(uap->itv, &aitv, sizeof(struct itimerval))))
return (error);
if (itimerfix(&aitv.it_value))
return (EINVAL);
if (!timevalisset(&aitv.it_value))
timevalclear(&aitv.it_interval);
else if (itimerfix(&aitv.it_interval))
return (EINVAL);
if (uap->which == ITIMER_REAL) {
PROC_LOCK(p);
if (timevalisset(&p->p_realtimer.it_value))
callout_stop(&p->p_itcallout);
getmicrouptime(&ctv);
if (timevalisset(&aitv.it_value)) {
callout_reset(&p->p_itcallout, tvtohz(&aitv.it_value),
realitexpire, p);
timevaladd(&aitv.it_value, &ctv);
}
oitv = p->p_realtimer;
p->p_realtimer = aitv;
PROC_UNLOCK(p);
if (timevalisset(&oitv.it_value)) {
if (timevalcmp(&oitv.it_value, &ctv, <))
timevalclear(&oitv.it_value);
else
timevalsub(&oitv.it_value, &ctv);
}
} else {
mtx_lock_spin(&sched_lock);
oitv = p->p_stats->p_timer[uap->which];
p->p_stats->p_timer[uap->which] = aitv;
mtx_unlock_spin(&sched_lock);
}
if (uap->oitv == NULL)
return (0);
return (copyout(&oitv, uap->oitv, sizeof(struct itimerval)));
}
/*
* Real interval timer expired:
* send process whose timer expired an alarm signal.
* If time is not set up to reload, then just return.
* Else compute next time timer should go off which is > current time.
* This is where delay in processing this timeout causes multiple
* SIGALRM calls to be compressed into one.
* tvtohz() always adds 1 to allow for the time until the next clock
* interrupt being strictly less than 1 clock tick, but we don't want
* that here since we want to appear to be in sync with the clock
* interrupt even when we're delayed.
*/
void
realitexpire(void *arg)
{
struct proc *p;
struct timeval ctv, ntv;
p = (struct proc *)arg;
PROC_LOCK(p);
psignal(p, SIGALRM);
if (!timevalisset(&p->p_realtimer.it_interval)) {
timevalclear(&p->p_realtimer.it_value);
if (p->p_flag & P_WEXIT)
wakeup(&p->p_itcallout);
PROC_UNLOCK(p);
return;
}
for (;;) {
timevaladd(&p->p_realtimer.it_value,
&p->p_realtimer.it_interval);
getmicrouptime(&ctv);
if (timevalcmp(&p->p_realtimer.it_value, &ctv, >)) {
ntv = p->p_realtimer.it_value;
timevalsub(&ntv, &ctv);
callout_reset(&p->p_itcallout, tvtohz(&ntv) - 1,
realitexpire, p);
PROC_UNLOCK(p);
return;
}
}
/*NOTREACHED*/
}
/*
* Check that a proposed value to load into the .it_value or
* .it_interval part of an interval timer is acceptable, and
* fix it to have at least minimal value (i.e. if it is less
* than the resolution of the clock, round it up.)
*/
int
itimerfix(struct timeval *tv)
{
if (tv->tv_sec < 0 || tv->tv_sec > 100000000 ||
tv->tv_usec < 0 || tv->tv_usec >= 1000000)
return (EINVAL);
if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
tv->tv_usec = tick;
return (0);
}
/*
* Decrement an interval timer by a specified number
* of microseconds, which must be less than a second,
* i.e. < 1000000. If the timer expires, then reload
* it. In this case, carry over (usec - old value) to
* reduce the value reloaded into the timer so that
* the timer does not drift. This routine assumes
* that it is called in a context where the timers
* on which it is operating cannot change in value.
*/
int
itimerdecr(struct itimerval *itp, int usec)
{
if (itp->it_value.tv_usec < usec) {
if (itp->it_value.tv_sec == 0) {
/* expired, and already in next interval */
usec -= itp->it_value.tv_usec;
goto expire;
}
itp->it_value.tv_usec += 1000000;
itp->it_value.tv_sec--;
}
itp->it_value.tv_usec -= usec;
usec = 0;
if (timevalisset(&itp->it_value))
return (1);
/* expired, exactly at end of interval */
expire:
if (timevalisset(&itp->it_interval)) {
itp->it_value = itp->it_interval;
itp->it_value.tv_usec -= usec;
if (itp->it_value.tv_usec < 0) {
itp->it_value.tv_usec += 1000000;
itp->it_value.tv_sec--;
}
} else
itp->it_value.tv_usec = 0; /* sec is already 0 */
return (0);
}
/*
* Add and subtract routines for timevals.
* N.B.: subtract routine doesn't deal with
* results which are before the beginning,
* it just gets very confused in this case.
* Caveat emptor.
*/
void
timevaladd(struct timeval *t1, const struct timeval *t2)
{
t1->tv_sec += t2->tv_sec;
t1->tv_usec += t2->tv_usec;
timevalfix(t1);
}
void
timevalsub(struct timeval *t1, const struct timeval *t2)
{
t1->tv_sec -= t2->tv_sec;
t1->tv_usec -= t2->tv_usec;
timevalfix(t1);
}
static void
timevalfix(struct timeval *t1)
{
if (t1->tv_usec < 0) {
t1->tv_sec--;
t1->tv_usec += 1000000;
}
if (t1->tv_usec >= 1000000) {
t1->tv_sec++;
t1->tv_usec -= 1000000;
}
}
/*
* ratecheck(): simple time-based rate-limit checking.
*/
int
ratecheck(struct timeval *lasttime, const struct timeval *mininterval)
{
struct timeval tv, delta;
int rv = 0;
getmicrouptime(&tv); /* NB: 10ms precision */
delta = tv;
timevalsub(&delta, lasttime);
/*
* check for 0,0 is so that the message will be seen at least once,
* even if interval is huge.
*/
if (timevalcmp(&delta, mininterval, >=) ||
(lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
*lasttime = tv;
rv = 1;
}
return (rv);
}
/*
* ppsratecheck(): packets (or events) per second limitation.
*
* Return 0 if the limit is to be enforced (e.g. the caller
* should drop a packet because of the rate limitation).
*
* maxpps of 0 always causes zero to be returned. maxpps of -1
* always causes 1 to be returned; this effectively defeats rate
* limiting.
*
* Note that we maintain the struct timeval for compatibility
* with other bsd systems. We reuse the storage and just monitor
* clock ticks for minimal overhead.
*/
int
ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
{
int now;
/*
* Reset the last time and counter if this is the first call
* or more than a second has passed since the last update of
* lasttime.
*/
now = ticks;
if (lasttime->tv_sec == 0 || (u_int)(now - lasttime->tv_sec) >= hz) {
lasttime->tv_sec = now;
*curpps = 1;
return (maxpps != 0);
} else {
(*curpps)++; /* NB: ignore potential overflow */
return (maxpps < 0 || *curpps < maxpps);
}
}