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Annotation of XNU/bsd/kern/kern_time.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * The contents of this file constitute Original Code as defined in and
        !             7:  * are subject to the Apple Public Source License Version 1.1 (the
        !             8:  * "License").  You may not use this file except in compliance with the
        !             9:  * License.  Please obtain a copy of the License at
        !            10:  * http://www.apple.com/publicsource and read it before using this file.
        !            11:  * 
        !            12:  * This Original Code and all software distributed under the License are
        !            13:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            14:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            15:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            16:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            17:  * License for the specific language governing rights and limitations
        !            18:  * under the License.
        !            19:  * 
        !            20:  * @APPLE_LICENSE_HEADER_END@
        !            21:  */
        !            22: /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
        !            23: /*
        !            24:  * Copyright (c) 1982, 1986, 1989, 1993
        !            25:  *     The Regents of the University of California.  All rights reserved.
        !            26:  *
        !            27:  * Redistribution and use in source and binary forms, with or without
        !            28:  * modification, are permitted provided that the following conditions
        !            29:  * are met:
        !            30:  * 1. Redistributions of source code must retain the above copyright
        !            31:  *    notice, this list of conditions and the following disclaimer.
        !            32:  * 2. Redistributions in binary form must reproduce the above copyright
        !            33:  *    notice, this list of conditions and the following disclaimer in the
        !            34:  *    documentation and/or other materials provided with the distribution.
        !            35:  * 3. All advertising materials mentioning features or use of this software
        !            36:  *    must display the following acknowledgement:
        !            37:  *     This product includes software developed by the University of
        !            38:  *     California, Berkeley and its contributors.
        !            39:  * 4. Neither the name of the University nor the names of its contributors
        !            40:  *    may be used to endorse or promote products derived from this software
        !            41:  *    without specific prior written permission.
        !            42:  *
        !            43:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            44:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            45:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            46:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            47:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            48:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            49:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            50:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            51:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            52:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            53:  * SUCH DAMAGE.
        !            54:  *
        !            55:  *     @(#)kern_time.c 8.4 (Berkeley) 5/26/95
        !            56:  */
        !            57: 
        !            58: #include <sys/param.h>
        !            59: #include <sys/resourcevar.h>
        !            60: #include <sys/kernel.h>
        !            61: #include <sys/systm.h>
        !            62: #include <sys/proc.h>
        !            63: #include <sys/vnode.h>
        !            64: 
        !            65: #include <sys/mount.h>
        !            66: 
        !            67: #include <kern/cpu_number.h>
        !            68: 
        !            69: #include <kern/clock.h>
        !            70: 
        !            71: #define HZ     100     /* XXX */
        !            72: 
        !            73: struct timeval         time;
        !            74: 
        !            75: /* 
        !            76:  * Time of day and interval timer support.
        !            77:  *
        !            78:  * These routines provide the kernel entry points to get and set
        !            79:  * the time-of-day and per-process interval timers.  Subroutines
        !            80:  * here provide support for adding and subtracting timeval structures
        !            81:  * and decrementing interval timers, optionally reloading the interval
        !            82:  * timers when they expire.
        !            83:  */
        !            84: struct gettimeofday_args{
        !            85:        struct timeval *tp;
        !            86:        struct timezone *tzp;
        !            87: };
        !            88: /* ARGSUSED */
        !            89: int
        !            90: gettimeofday(p, uap, retval)
        !            91:        struct proc *p;
        !            92:        register struct gettimeofday_args *uap;
        !            93:        register_t *retval;
        !            94: {
        !            95:        struct timeval atv;
        !            96:        int error = 0;
        !            97: 
        !            98:        if (uap->tp) {
        !            99:                microtime(&atv);
        !           100:                if (error = copyout((caddr_t)&atv, (caddr_t)uap->tp,
        !           101:                        sizeof (atv)))
        !           102:                        return(error);
        !           103:        }
        !           104:        
        !           105:        if (uap->tzp)
        !           106:                error = copyout((caddr_t)&tz, (caddr_t)uap->tzp,
        !           107:                    sizeof (tz));
        !           108: 
        !           109:        return(error);
        !           110: }
        !           111: 
        !           112: struct settimeofday_args {
        !           113:        struct timeval *tv;
        !           114:        struct timezone *tzp;
        !           115: };
        !           116: /* ARGSUSED */
        !           117: int
        !           118: settimeofday(p, uap, retval)
        !           119:        struct proc *p;
        !           120:        struct settimeofday_args  *uap;
        !           121:        register_t *retval;
        !           122: {
        !           123:        struct timeval atv;
        !           124:        struct timezone atz;
        !           125:        int error, s;
        !           126: 
        !           127:        if (error = suser(p->p_ucred, &p->p_acflag))
        !           128:                return (error);
        !           129:        /* Verify all parameters before changing time. */
        !           130:        if (uap->tv && (error = copyin((caddr_t)uap->tv,
        !           131:            (caddr_t)&atv, sizeof(atv))))
        !           132:                return (error);
        !           133:        if (uap->tzp && (error = copyin((caddr_t)uap->tzp,
        !           134:            (caddr_t)&atz, sizeof(atz))))
        !           135:                return (error);
        !           136:        if (uap->tv)
        !           137:                setthetime(&atv);
        !           138:        if (uap->tzp)
        !           139:                tz = atz;
        !           140:        return (0);
        !           141: }
        !           142: 
        !           143: setthetime(tv)
        !           144:        struct timeval *tv;
        !           145: {
        !           146:        mach_timespec_t now;
        !           147:        long delta;
        !           148:        int s;
        !           149: 
        !           150:        now.tv_sec = tv->tv_sec;
        !           151:        now.tv_nsec = tv->tv_usec * NSEC_PER_USEC;
        !           152: 
        !           153:        clock_set_calendar_value(now);
        !           154:        delta = tv->tv_sec - time.tv_sec;
        !           155:        boottime.tv_sec += delta;
        !           156: #if NFSCLIENT || NFSSERVER
        !           157:        lease_updatetime(delta);
        !           158: #endif
        !           159:        s = splhigh();
        !           160:        microtime(&time);
        !           161:        splx(s);
        !           162: }
        !           163: 
        !           164: int    tickadj = 240000 / (60 * HZ);   /* "standard" clock skew, us./tick */
        !           165: int    tickdelta;                      /* current clock skew, us. per tick */
        !           166: long   timedelta;                      /* unapplied time correction, us. */
        !           167: long   bigadj = 1000000;               /* use 10x skew above bigadj us. */
        !           168: 
        !           169: struct adjtime_args {
        !           170:        struct timeval *delta;
        !           171:        struct timeval *olddelta;
        !           172: };
        !           173: /* ARGSUSED */
        !           174: int
        !           175: adjtime(p, uap, retval)
        !           176:        struct proc *p;
        !           177:        register struct adjtime_args *uap;
        !           178:        register_t *retval;
        !           179: {
        !           180:        struct timeval atv, oatv;
        !           181:        register long ndelta;
        !           182:        int s, error;
        !           183: 
        !           184:        if (error = suser(p->p_ucred, &p->p_acflag))
        !           185:                return (error);
        !           186:        if(error = copyin((caddr_t)uap->delta, (caddr_t)&atv,
        !           187:                sizeof (struct timeval)))
        !           188:                return(error);
        !           189:                
        !           190:        ndelta = atv.tv_sec * 1000000 + atv.tv_usec;
        !           191:        if (timedelta == 0)
        !           192:                if (ndelta > bigadj)
        !           193:                        tickdelta = 10 * tickadj;
        !           194:                else
        !           195:                        tickdelta = tickadj;
        !           196:        if (ndelta % tickdelta)
        !           197:                ndelta = ndelta / tickdelta * tickdelta;
        !           198: 
        !           199:        s = splclock();
        !           200:        if (uap->olddelta) {
        !           201:                oatv.tv_sec = timedelta / 1000000;
        !           202:                oatv.tv_usec = timedelta % 1000000;
        !           203:        }
        !           204:        timedelta = ndelta;
        !           205:        splx(s);
        !           206: 
        !           207:        if (uap->olddelta)
        !           208:                (void) copyout((caddr_t)&oatv, (caddr_t)uap->olddelta,
        !           209:                        sizeof (struct timeval));
        !           210:        return(0);
        !           211: }
        !           212: 
        !           213: #define SECDAY          ((unsigned)(24*60*60))          /* seconds per day */
        !           214: #define SECYR           ((unsigned)(365*SECDAY))        /* per common year */
        !           215: #define YRREF           70      /* UNIX time referenced to 1970 */
        !           216: 
        !           217: /*
        !           218:  * Initialze the time of day register, based on the time base which is, e.g.
        !           219:  * from a filesystem.
        !           220:  */
        !           221: void
        !           222: inittodr(base)
        !           223:        time_t base;
        !           224: {
        !           225:        long deltat;
        !           226: 
        !           227:        if (base < (87-YRREF) * SECYR || base < 0) {    /* fs < than 1987? */
        !           228:                printf("WARNING: preposterous time in file system");
        !           229:                goto check;
        !           230:        }
        !           231: 
        !           232:        /*
        !           233:         * Initialize the calendar by
        !           234:         * reading the BBC, if not already set.
        !           235:         */
        !           236:        clock_initialize_calendar();
        !           237: 
        !           238:        /*
        !           239:         * The value returned by microtime()
        !           240:         * is gotten from the calendar.
        !           241:         */
        !           242:        microtime(&time);
        !           243: 
        !           244:        /*
        !           245:         * This variable still exists to keep
        !           246:         * 'w' happy.  It should only be considered
        !           247:         * an approximation.
        !           248:         */
        !           249:        boottime.tv_sec = time.tv_sec;
        !           250:        boottime.tv_usec = 0;
        !           251: 
        !           252:        /*
        !           253:         * See if we gained/lost two or more days;
        !           254:         * if so, assume something is amiss.
        !           255:         * Avoid changing RTC if RTC time > file system time and delta is
        !           256:         * less than two days.
        !           257:         */
        !           258:        deltat = time.tv_sec - base;
        !           259:        if (deltat < 0)
        !           260:                deltat = -deltat;
        !           261:        if ((deltat < 2*SECDAY) && (time.tv_sec > base))
        !           262:                return;
        !           263:        if (time.tv_sec < SECYR) {
        !           264:                printf ("WARNING: clock not set properly");
        !           265:                time.tv_sec = base;
        !           266:                time.tv_usec = 0;
        !           267:                setthetime(&time);
        !           268:                boottime = time;
        !           269:                goto check;
        !           270:        }
        !           271: 
        !           272:        if (deltat > 90*SECDAY) {       /* assume rtc is way off */
        !           273:                printf ("WARNING: preposterous time in Real Time Clock");
        !           274:                time.tv_sec = base;
        !           275:                time.tv_usec = 0;
        !           276:                setthetime(&time);
        !           277:                boottime = time;
        !           278:                goto check;
        !           279:        }
        !           280:        printf("WARNING: clock lost %d days", deltat / SECDAY);
        !           281: check:
        !           282:        printf(" -- CHECK AND RESET THE DATE!\n");
        !           283: }
        !           284: 
        !           285: /*
        !           286:  * Get value of an interval timer.  The process virtual and
        !           287:  * profiling virtual time timers are kept in the u. area, since
        !           288:  * they can be swapped out.  These are kept internally in the
        !           289:  * way they are specified externally: in time until they expire.
        !           290:  *
        !           291:  * The real time interval timer is kept in the process table slot
        !           292:  * for the process, and its value (it_value) is kept as an
        !           293:  * absolute time rather than as a delta, so that it is easy to keep
        !           294:  * periodic real-time signals from drifting.
        !           295:  *
        !           296:  * Virtual time timers are processed in the hardclock() routine of
        !           297:  * kern_clock.c.  The real time timer is processed by a timeout
        !           298:  * routine, called from the softclock() routine.  Since a callout
        !           299:  * may be delayed in real time due to interrupt processing in the system,
        !           300:  * it is possible for the real time timeout routine (realitexpire, given below),
        !           301:  * to be delayed in real time past when it is supposed to occur.  It
        !           302:  * does not suffice, therefore, to reload the real timer .it_value from the
        !           303:  * real time timers .it_interval.  Rather, we compute the next time in
        !           304:  * absolute time the timer should go off.
        !           305:  */
        !           306:  
        !           307: struct getitimer_args {
        !           308:        u_int   which;
        !           309:        struct itimerval *itv;
        !           310: }; 
        !           311: /* ARGSUSED */
        !           312: int
        !           313: getitimer(p, uap, retval)
        !           314:        struct proc *p;
        !           315:        register struct getitimer_args *uap;
        !           316:        register_t *retval;
        !           317: {
        !           318:        struct itimerval aitv;
        !           319:        int s;
        !           320: 
        !           321:        if (uap->which > ITIMER_PROF)
        !           322:                return(EINVAL);
        !           323:        
        !           324:        s = splclock();
        !           325:        if (uap->which == ITIMER_REAL) {
        !           326:                /*
        !           327:                 * Convert from absoulte to relative time in .it_value
        !           328:                 * part of real time timer.  If time for real time timer
        !           329:                 * has passed return 0, else return difference between
        !           330:                 * current time and time for the timer to go off.
        !           331:                 */
        !           332:                aitv = p->p_realtimer;
        !           333:                if (timerisset(&aitv.it_value))
        !           334:                        if (timercmp(&aitv.it_value, &time, <))
        !           335:                                timerclear(&aitv.it_value);
        !           336:                        else
        !           337:                                timevalsub(&aitv.it_value, &time);
        !           338:        } else
        !           339:                aitv =p->p_stats->p_timer[uap->which];
        !           340:        splx(s);
        !           341:        return(copyout((caddr_t)&aitv, (caddr_t)uap->itv,
        !           342:            sizeof (struct itimerval)));
        !           343: }
        !           344: 
        !           345: struct setitimer_args {
        !           346:        u_int   which;
        !           347:        struct  itimerval *itv;
        !           348:        struct  itimerval *oitv;
        !           349: };
        !           350: /* ARGSUSED */
        !           351: int
        !           352: setitimer(p, uap, retval)
        !           353:        struct proc *p;
        !           354:        register struct setitimer_args *uap;
        !           355:        register_t *retval;
        !           356: {
        !           357:        struct itimerval aitv;
        !           358:        register struct itimerval *itvp;
        !           359:        int s, error;
        !           360: 
        !           361:        if (uap->which > ITIMER_PROF)
        !           362:                return(EINVAL);
        !           363:        itvp = uap->itv;
        !           364:        if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv,
        !           365:            sizeof(struct itimerval))))
        !           366:                return (error);
        !           367:        if ((uap->itv = uap->oitv) &&
        !           368:            (error = getitimer(p, uap, retval)))
        !           369:                return (error);
        !           370:        if (itvp == 0)
        !           371:                return (0);
        !           372:        if (itimerfix(&aitv.it_value) || itimerfix(&aitv.it_interval))
        !           373:                return (EINVAL);
        !           374:        s = splclock();
        !           375:        if (uap->which == ITIMER_REAL) {
        !           376:                untimeout(realitexpire, (caddr_t)p);
        !           377:                if (timerisset(&aitv.it_value)) {
        !           378:                        timevaladd(&aitv.it_value, &time);
        !           379:                        timeout(realitexpire, (caddr_t)p, hzto(&aitv.it_value));
        !           380:                }
        !           381:                p->p_realtimer = aitv;
        !           382:        } else
        !           383:                p->p_stats->p_timer[uap->which] = aitv;
        !           384:        splx(s);
        !           385:        return(0); /* To insure good return value on success */
        !           386: }
        !           387: 
        !           388: /*
        !           389:  * Real interval timer expired:
        !           390:  * send process whose timer expired an alarm signal.
        !           391:  * If time is not set up to reload, then just return.
        !           392:  * Else compute next time timer should go off which is > current time.
        !           393:  * This is where delay in processing this timeout causes multiple
        !           394:  * SIGALRM calls to be compressed into one.
        !           395:  */
        !           396: void
        !           397: realitexpire(arg)
        !           398:        void *arg;
        !           399: {
        !           400:        register struct proc *p;
        !           401:        int s;
        !           402: 
        !           403:        p = (struct proc *)arg;
        !           404:        psignal(p, SIGALRM);
        !           405:        if (!timerisset(&p->p_realtimer.it_interval)) {
        !           406:                timerclear(&p->p_realtimer.it_value);
        !           407:                return;
        !           408:        }
        !           409:        
        !           410:        /*
        !           411:         * If the time's way off, don't try to compensate by getting
        !           412:         * there incrementally.
        !           413:         */
        !           414:        s = splclock();
        !           415:        if (p->p_realtimer.it_value.tv_sec < time.tv_sec - 10) {
        !           416:                p->p_realtimer.it_value = time;
        !           417:                timeout(realitexpire, (caddr_t)p,
        !           418:                        hzto(&p->p_realtimer.it_value));
        !           419:                splx(s);
        !           420:                return;
        !           421:                
        !           422:        }
        !           423:        splx(s);
        !           424: 
        !           425:        for (;;) {
        !           426:                s = splclock();
        !           427:                timevaladd(&p->p_realtimer.it_value,
        !           428:                    &p->p_realtimer.it_interval);
        !           429:                if (timercmp(&p->p_realtimer.it_value, &time, >)) {
        !           430:                        timeout(realitexpire, (caddr_t)p,
        !           431:                            hzto(&p->p_realtimer.it_value));
        !           432:                        splx(s);
        !           433:                        return;
        !           434:                }
        !           435:                splx(s);
        !           436:        }
        !           437: }
        !           438: 
        !           439: /*
        !           440:  * Check that a proposed value to load into the .it_value or
        !           441:  * .it_interval part of an interval timer is acceptable, and
        !           442:  * fix it to have at least minimal value (i.e. if it is less
        !           443:  * than the resolution of the clock, round it up.)
        !           444:  */
        !           445: int
        !           446: itimerfix(tv)
        !           447:        struct timeval *tv;
        !           448: {
        !           449: 
        !           450:        if (tv->tv_sec < 0 || tv->tv_sec > 100000000 ||
        !           451:            tv->tv_usec < 0 || tv->tv_usec >= 1000000)
        !           452:                return (EINVAL);
        !           453:        if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
        !           454:                tv->tv_usec = tick;
        !           455:        return (0);
        !           456: }
        !           457: 
        !           458: /*
        !           459:  * Decrement an interval timer by a specified number
        !           460:  * of microseconds, which must be less than a second,
        !           461:  * i.e. < 1000000.  If the timer expires, then reload
        !           462:  * it.  In this case, carry over (usec - old value) to
        !           463:  * reducint the value reloaded into the timer so that
        !           464:  * the timer does not drift.  This routine assumes
        !           465:  * that it is called in a context where the timers
        !           466:  * on which it is operating cannot change in value.
        !           467:  */
        !           468: int
        !           469: itimerdecr(itp, usec)
        !           470:        register struct itimerval *itp;
        !           471:        int usec;
        !           472: {
        !           473: 
        !           474:        if (itp->it_value.tv_usec < usec) {
        !           475:                if (itp->it_value.tv_sec == 0) {
        !           476:                        /* expired, and already in next interval */
        !           477:                        usec -= itp->it_value.tv_usec;
        !           478:                        goto expire;
        !           479:                }
        !           480:                itp->it_value.tv_usec += 1000000;
        !           481:                itp->it_value.tv_sec--;
        !           482:        }
        !           483:        itp->it_value.tv_usec -= usec;
        !           484:        usec = 0;
        !           485:        if (timerisset(&itp->it_value))
        !           486:                return (1);
        !           487:        /* expired, exactly at end of interval */
        !           488: expire:
        !           489:        if (timerisset(&itp->it_interval)) {
        !           490:                itp->it_value = itp->it_interval;
        !           491:                itp->it_value.tv_usec -= usec;
        !           492:                if (itp->it_value.tv_usec < 0) {
        !           493:                        itp->it_value.tv_usec += 1000000;
        !           494:                        itp->it_value.tv_sec--;
        !           495:                }
        !           496:        } else
        !           497:                itp->it_value.tv_usec = 0;              /* sec is already 0 */
        !           498:        return (0);
        !           499: }
        !           500: 
        !           501: /*
        !           502:  * Add and subtract routines for timevals.
        !           503:  * N.B.: subtract routine doesn't deal with
        !           504:  * results which are before the beginning,
        !           505:  * it just gets very confused in this case.
        !           506:  * Caveat emptor.
        !           507:  */
        !           508: void
        !           509: timevaladd(t1, t2)
        !           510:        struct timeval *t1, *t2;
        !           511: {
        !           512: 
        !           513:        t1->tv_sec += t2->tv_sec;
        !           514:        t1->tv_usec += t2->tv_usec;
        !           515:        timevalfix(t1);
        !           516: }
        !           517: void
        !           518: timevalsub(t1, t2)
        !           519:        struct timeval *t1, *t2;
        !           520: {
        !           521: 
        !           522:        t1->tv_sec -= t2->tv_sec;
        !           523:        t1->tv_usec -= t2->tv_usec;
        !           524:        timevalfix(t1);
        !           525: }
        !           526: void
        !           527: timevalfix(t1)
        !           528:        struct timeval *t1;
        !           529: {
        !           530: 
        !           531:        if (t1->tv_usec < 0) {
        !           532:                t1->tv_sec--;
        !           533:                t1->tv_usec += 1000000;
        !           534:        }
        !           535:        if (t1->tv_usec >= 1000000) {
        !           536:                t1->tv_sec++;
        !           537:                t1->tv_usec -= 1000000;
        !           538:        }
        !           539: }
        !           540: 
        !           541: /*
        !           542:  * Return the best possible estimate of the time in the timeval
        !           543:  * to which tvp points.
        !           544:  */
        !           545: void
        !           546: microtime(struct timeval * tvp)
        !           547: {
        !           548:        mach_timespec_t         now = clock_get_calendar_value();
        !           549: 
        !           550:        tvp->tv_sec = now.tv_sec;
        !           551:        tvp->tv_usec = now.tv_nsec / NSEC_PER_USEC;
        !           552: }

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