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Annotation of 43BSDReno/sys/kern/kern_time.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1982, 1986, 1989 Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution is only permitted until one year after the first shipment
        !             6:  * of 4.4BSD by the Regents.  Otherwise, redistribution and use in source and
        !             7:  * binary forms are permitted provided that: (1) source distributions retain
        !             8:  * this entire copyright notice and comment, and (2) distributions including
        !             9:  * binaries display the following acknowledgement:  This product includes
        !            10:  * software developed by the University of California, Berkeley and its
        !            11:  * contributors'' in the documentation or other materials provided with the
        !            12:  * distribution and in all advertising materials mentioning features or use
        !            13:  * of this software.  Neither the name of the University nor the names of
        !            14:  * its contributors may be used to endorse or promote products derived from
        !            15:  * this software without specific prior written permission.
        !            16:  * THIS SOFTWARE IS PROVIDED AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
        !            17:  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
        !            18:  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            19:  *
        !            20:  *     @(#)kern_time.c 7.13 (Berkeley) 6/28/90
        !            21:  */
        !            22: 
        !            23: #include "param.h"
        !            24: #include "user.h"
        !            25: #include "kernel.h"
        !            26: #include "proc.h"
        !            27: 
        !            28: #include "machine/reg.h"
        !            29: #include "machine/cpu.h"
        !            30: 
        !            31: /* 
        !            32:  * Time of day and interval timer support.
        !            33:  *
        !            34:  * These routines provide the kernel entry points to get and set
        !            35:  * the time-of-day and per-process interval timers.  Subroutines
        !            36:  * here provide support for adding and subtracting timeval structures
        !            37:  * and decrementing interval timers, optionally reloading the interval
        !            38:  * timers when they expire.
        !            39:  */
        !            40: 
        !            41: /* ARGSUSED */
        !            42: gettimeofday(p, uap, retval)
        !            43:        struct proc *p;
        !            44:        register struct args {
        !            45:                struct  timeval *tp;
        !            46:                struct  timezone *tzp;
        !            47:        } *uap;
        !            48:        int *retval;
        !            49: {
        !            50:        struct timeval atv;
        !            51:        int error = 0;
        !            52: 
        !            53:        if (uap->tp) {
        !            54:                microtime(&atv);
        !            55:                if (error = copyout((caddr_t)&atv, (caddr_t)uap->tp,
        !            56:                    sizeof (atv)))
        !            57:                        return (error);
        !            58:        }
        !            59:        if (uap->tzp)
        !            60:                error = copyout((caddr_t)&tz, (caddr_t)uap->tzp,
        !            61:                    sizeof (tz));
        !            62:        return (error);
        !            63: }
        !            64: 
        !            65: settimeofday(p, uap, retval)
        !            66:        struct proc *p;
        !            67:        struct args {
        !            68:                struct  timeval *tv;
        !            69:                struct  timezone *tzp;
        !            70:        } *uap;
        !            71:        int *retval;
        !            72: {
        !            73:        struct timeval atv;
        !            74:        struct timezone atz;
        !            75:        int error, s;
        !            76: 
        !            77:        if (error = suser(u.u_cred, &u.u_acflag))
        !            78:                return (error);
        !            79:        if (uap->tv) {
        !            80:                if (error = copyin((caddr_t)uap->tv, (caddr_t)&atv,
        !            81:                    sizeof (struct timeval)))
        !            82:                        return (error);
        !            83:                /* WHAT DO WE DO ABOUT PENDING REAL-TIME TIMEOUTS??? */
        !            84:                boottime.tv_sec += atv.tv_sec - time.tv_sec;
        !            85:                s = splhigh(); time = atv; splx(s);
        !            86:                resettodr();
        !            87:        }
        !            88:        if (uap->tzp && (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz,
        !            89:            sizeof (atz))) == 0)
        !            90:                tz = atz;
        !            91:        return (error);
        !            92: }
        !            93: 
        !            94: extern int tickadj;                    /* "standard" clock skew, us./tick */
        !            95: int    tickdelta;                      /* current clock skew, us. per tick */
        !            96: long   timedelta;                      /* unapplied time correction, us. */
        !            97: long   bigadj = 1000000;               /* use 10x skew above bigadj us. */
        !            98: 
        !            99: /* ARGSUSED */
        !           100: adjtime(p, uap, retval)
        !           101:        struct proc *p;
        !           102:        register struct args {
        !           103:                struct timeval *delta;
        !           104:                struct timeval *olddelta;
        !           105:        } *uap;
        !           106:        int *retval;
        !           107: {
        !           108:        struct timeval atv, oatv;
        !           109:        register long ndelta;
        !           110:        int s, error;
        !           111: 
        !           112:        if (error = suser(u.u_cred, &u.u_acflag))
        !           113:                return (error);
        !           114:        if (error =
        !           115:            copyin((caddr_t)uap->delta, (caddr_t)&atv, sizeof (struct timeval)))
        !           116:                return (error);
        !           117:        ndelta = atv.tv_sec * 1000000 + atv.tv_usec;
        !           118:        if (timedelta == 0)
        !           119:                if (ndelta > bigadj)
        !           120:                        tickdelta = 10 * tickadj;
        !           121:                else
        !           122:                        tickdelta = tickadj;
        !           123:        if (ndelta % tickdelta)
        !           124:                ndelta = ndelta / tickadj * tickadj;
        !           125: 
        !           126:        s = splclock();
        !           127:        if (uap->olddelta) {
        !           128:                oatv.tv_sec = timedelta / 1000000;
        !           129:                oatv.tv_usec = timedelta % 1000000;
        !           130:        }
        !           131:        timedelta = ndelta;
        !           132:        splx(s);
        !           133: 
        !           134:        if (uap->olddelta)
        !           135:                (void) copyout((caddr_t)&oatv, (caddr_t)uap->olddelta,
        !           136:                        sizeof (struct timeval));
        !           137:        return (0);
        !           138: }
        !           139: 
        !           140: /*
        !           141:  * Get value of an interval timer.  The process virtual and
        !           142:  * profiling virtual time timers are kept in the u. area, since
        !           143:  * they can be swapped out.  These are kept internally in the
        !           144:  * way they are specified externally: in time until they expire.
        !           145:  *
        !           146:  * The real time interval timer is kept in the process table slot
        !           147:  * for the process, and its value (it_value) is kept as an
        !           148:  * absolute time rather than as a delta, so that it is easy to keep
        !           149:  * periodic real-time signals from drifting.
        !           150:  *
        !           151:  * Virtual time timers are processed in the hardclock() routine of
        !           152:  * kern_clock.c.  The real time timer is processed by a timeout
        !           153:  * routine, called from the softclock() routine.  Since a callout
        !           154:  * may be delayed in real time due to interrupt processing in the system,
        !           155:  * it is possible for the real time timeout routine (realitexpire, given below),
        !           156:  * to be delayed in real time past when it is supposed to occur.  It
        !           157:  * does not suffice, therefore, to reload the real timer .it_value from the
        !           158:  * real time timers .it_interval.  Rather, we compute the next time in
        !           159:  * absolute time the timer should go off.
        !           160:  */
        !           161: /* ARGSUSED */
        !           162: getitimer(p, uap, retval)
        !           163:        struct proc *p;
        !           164:        register struct args {
        !           165:                u_int   which;
        !           166:                struct  itimerval *itv;
        !           167:        } *uap;
        !           168:        int *retval;
        !           169: {
        !           170:        struct itimerval aitv;
        !           171:        int s;
        !           172: 
        !           173:        if (uap->which > ITIMER_PROF)
        !           174:                return (EINVAL);
        !           175:        s = splclock();
        !           176:        if (uap->which == ITIMER_REAL) {
        !           177:                /*
        !           178:                 * Convert from absoulte to relative time in .it_value
        !           179:                 * part of real time timer.  If time for real time timer
        !           180:                 * has passed return 0, else return difference between
        !           181:                 * current time and time for the timer to go off.
        !           182:                 */
        !           183:                aitv = p->p_realtimer;
        !           184:                if (timerisset(&aitv.it_value))
        !           185:                        if (timercmp(&aitv.it_value, &time, <))
        !           186:                                timerclear(&aitv.it_value);
        !           187:                        else
        !           188:                                timevalsub(&aitv.it_value, &time);
        !           189:        } else
        !           190:                aitv = u.u_timer[uap->which];
        !           191:        splx(s);
        !           192:        return (copyout((caddr_t)&aitv, (caddr_t)uap->itv,
        !           193:            sizeof (struct itimerval)));
        !           194: }
        !           195: 
        !           196: /* ARGSUSED */
        !           197: setitimer(p, uap, retval)
        !           198:        struct proc *p;
        !           199:        register struct args {
        !           200:                u_int   which;
        !           201:                struct  itimerval *itv, *oitv;
        !           202:        } *uap;
        !           203:        int *retval;
        !           204: {
        !           205:        struct itimerval aitv;
        !           206:        register struct itimerval *itvp;
        !           207:        int s, error;
        !           208: 
        !           209:        if (uap->which > ITIMER_PROF)
        !           210:                return (EINVAL);
        !           211:        itvp = uap->itv;
        !           212:        if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv,
        !           213:            sizeof(struct itimerval))))
        !           214:                return (error);
        !           215:        if ((uap->itv = uap->oitv) && (error = getitimer(p, uap, retval)))
        !           216:                return (error);
        !           217:        if (itvp == 0)
        !           218:                return (0);
        !           219:        if (itimerfix(&aitv.it_value) || itimerfix(&aitv.it_interval))
        !           220:                return (EINVAL);
        !           221:        s = splclock();
        !           222:        if (uap->which == ITIMER_REAL) {
        !           223:                untimeout(realitexpire, (caddr_t)p);
        !           224:                if (timerisset(&aitv.it_value)) {
        !           225:                        timevaladd(&aitv.it_value, &time);
        !           226:                        timeout(realitexpire, (caddr_t)p, hzto(&aitv.it_value));
        !           227:                }
        !           228:                p->p_realtimer = aitv;
        !           229:        } else
        !           230:                u.u_timer[uap->which] = aitv;
        !           231:        splx(s);
        !           232:        return (0);
        !           233: }
        !           234: 
        !           235: /*
        !           236:  * Real interval timer expired:
        !           237:  * send process whose timer expired an alarm signal.
        !           238:  * If time is not set up to reload, then just return.
        !           239:  * Else compute next time timer should go off which is > current time.
        !           240:  * This is where delay in processing this timeout causes multiple
        !           241:  * SIGALRM calls to be compressed into one.
        !           242:  */
        !           243: realitexpire(p)
        !           244:        register struct proc *p;
        !           245: {
        !           246:        int s;
        !           247: 
        !           248:        psignal(p, SIGALRM);
        !           249:        if (!timerisset(&p->p_realtimer.it_interval)) {
        !           250:                timerclear(&p->p_realtimer.it_value);
        !           251:                return;
        !           252:        }
        !           253:        for (;;) {
        !           254:                s = splclock();
        !           255:                timevaladd(&p->p_realtimer.it_value,
        !           256:                    &p->p_realtimer.it_interval);
        !           257:                if (timercmp(&p->p_realtimer.it_value, &time, >)) {
        !           258:                        timeout(realitexpire, (caddr_t)p,
        !           259:                            hzto(&p->p_realtimer.it_value));
        !           260:                        splx(s);
        !           261:                        return;
        !           262:                }
        !           263:                splx(s);
        !           264:        }
        !           265: }
        !           266: 
        !           267: /*
        !           268:  * Check that a proposed value to load into the .it_value or
        !           269:  * .it_interval part of an interval timer is acceptable, and
        !           270:  * fix it to have at least minimal value (i.e. if it is less
        !           271:  * than the resolution of the clock, round it up.)
        !           272:  */
        !           273: itimerfix(tv)
        !           274:        struct timeval *tv;
        !           275: {
        !           276: 
        !           277:        if (tv->tv_sec < 0 || tv->tv_sec > 100000000 ||
        !           278:            tv->tv_usec < 0 || tv->tv_usec >= 1000000)
        !           279:                return (EINVAL);
        !           280:        if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
        !           281:                tv->tv_usec = tick;
        !           282:        return (0);
        !           283: }
        !           284: 
        !           285: /*
        !           286:  * Decrement an interval timer by a specified number
        !           287:  * of microseconds, which must be less than a second,
        !           288:  * i.e. < 1000000.  If the timer expires, then reload
        !           289:  * it.  In this case, carry over (usec - old value) to
        !           290:  * reducint the value reloaded into the timer so that
        !           291:  * the timer does not drift.  This routine assumes
        !           292:  * that it is called in a context where the timers
        !           293:  * on which it is operating cannot change in value.
        !           294:  */
        !           295: itimerdecr(itp, usec)
        !           296:        register struct itimerval *itp;
        !           297:        int usec;
        !           298: {
        !           299: 
        !           300:        if (itp->it_value.tv_usec < usec) {
        !           301:                if (itp->it_value.tv_sec == 0) {
        !           302:                        /* expired, and already in next interval */
        !           303:                        usec -= itp->it_value.tv_usec;
        !           304:                        goto expire;
        !           305:                }
        !           306:                itp->it_value.tv_usec += 1000000;
        !           307:                itp->it_value.tv_sec--;
        !           308:        }
        !           309:        itp->it_value.tv_usec -= usec;
        !           310:        usec = 0;
        !           311:        if (timerisset(&itp->it_value))
        !           312:                return (1);
        !           313:        /* expired, exactly at end of interval */
        !           314: expire:
        !           315:        if (timerisset(&itp->it_interval)) {
        !           316:                itp->it_value = itp->it_interval;
        !           317:                itp->it_value.tv_usec -= usec;
        !           318:                if (itp->it_value.tv_usec < 0) {
        !           319:                        itp->it_value.tv_usec += 1000000;
        !           320:                        itp->it_value.tv_sec--;
        !           321:                }
        !           322:        } else
        !           323:                itp->it_value.tv_usec = 0;              /* sec is already 0 */
        !           324:        return (0);
        !           325: }
        !           326: 
        !           327: /*
        !           328:  * Add and subtract routines for timevals.
        !           329:  * N.B.: subtract routine doesn't deal with
        !           330:  * results which are before the beginning,
        !           331:  * it just gets very confused in this case.
        !           332:  * Caveat emptor.
        !           333:  */
        !           334: timevaladd(t1, t2)
        !           335:        struct timeval *t1, *t2;
        !           336: {
        !           337: 
        !           338:        t1->tv_sec += t2->tv_sec;
        !           339:        t1->tv_usec += t2->tv_usec;
        !           340:        timevalfix(t1);
        !           341: }
        !           342: 
        !           343: timevalsub(t1, t2)
        !           344:        struct timeval *t1, *t2;
        !           345: {
        !           346: 
        !           347:        t1->tv_sec -= t2->tv_sec;
        !           348:        t1->tv_usec -= t2->tv_usec;
        !           349:        timevalfix(t1);
        !           350: }
        !           351: 
        !           352: timevalfix(t1)
        !           353:        struct timeval *t1;
        !           354: {
        !           355: 
        !           356:        if (t1->tv_usec < 0) {
        !           357:                t1->tv_sec--;
        !           358:                t1->tv_usec += 1000000;
        !           359:        }
        !           360:        if (t1->tv_usec >= 1000000) {
        !           361:                t1->tv_sec++;
        !           362:                t1->tv_usec -= 1000000;
        !           363:        }
        !           364: }

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