sys/kern/kern_time.c

   1 /*
   2  * Copyright (c) 1982, 1986, 1989, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)kern_time.c 8.1 (Berkeley) 6/10/93
  34  * $FreeBSD: src/sys/kern/kern_time.c,v 1.68.2.1 2002/10/01 08:00:41 bde Exp $
  35  * $DragonFly: src/sys/kern/kern_time.c,v 1.39 2007/02/03 18:05:58 corecode Exp $
  36  */
  37
  38 #include <sys/param.h>
  39 #include <sys/systm.h>
  40 #include <sys/buf.h>
  41 #include <sys/sysproto.h>
  42 #include <sys/resourcevar.h>
  43 #include <sys/signalvar.h>
  44 #include <sys/kernel.h>
  45 #include <sys/systm.h>
  46 #include <sys/sysent.h>
  47 #include <sys/sysunion.h>
  48 #include <sys/proc.h>
  49 #include <sys/time.h>
  50 #include <sys/vnode.h>
  51 #include <sys/sysctl.h>
  52 #include <vm/vm.h>
  53 #include <vm/vm_extern.h>
  54 #include <sys/msgport2.h>
  55 #include <sys/thread2.h>
  56
  57 struct timezone tz;
  58
  59 /*
  60  * Time of day and interval timer support.
  61  *
  62  * These routines provide the kernel entry points to get and set
  63  * the time-of-day and per-process interval timers.  Subroutines
  64  * here provide support for adding and subtracting timeval structures
  65  * and decrementing interval timers, optionally reloading the interval
  66  * timers when they expire.
  67  */
  68
  69 static int      nanosleep1 (struct timespec *rqt,
  70                     struct timespec *rmt);
  71 static int      settime (struct timeval *);
  72 static void     timevalfix (struct timeval *);
  73
  74 static int     sleep_hard_us = 100;
  75 SYSCTL_INT(_kern, OID_AUTO, sleep_hard_us, CTLFLAG_RW, &sleep_hard_us, 0, "")
  76
  77 static int
  78 settime(struct timeval *tv)
  79 {
  80         struct timeval delta, tv1, tv2;
  81         static struct timeval maxtime, laststep;
  82         struct timespec ts;
  83         int origcpu;
  84
  85         if ((origcpu = mycpu->gd_cpuid) != 0)
  86                 lwkt_setcpu_self(globaldata_find(0));
  87
  88         crit_enter();
  89         microtime(&tv1);
  90         delta = *tv;
  91         timevalsub(&delta, &tv1);
  92
  93         /*
  94          * If the system is secure, we do not allow the time to be
  95          * set to a value earlier than 1 second less than the highest
  96          * time we have yet seen. The worst a miscreant can do in
  97          * this circumstance is "freeze" time. He couldn't go
  98          * back to the past.
  99          *
 100          * We similarly do not allow the clock to be stepped more
 101          * than one second, nor more than once per second. This allows
 102          * a miscreant to make the clock march double-time, but no worse.
 103          */
 104         if (securelevel > 1) {
 105                 if (delta.tv_sec < 0 || delta.tv_usec < 0) {
 106                         /*
 107                          * Update maxtime to latest time we've seen.
 108                          */
 109                         if (tv1.tv_sec > maxtime.tv_sec)
 110                                 maxtime = tv1;
 111                         tv2 = *tv;
 112                         timevalsub(&tv2, &maxtime);
 113                         if (tv2.tv_sec < -1) {
 114                                 tv->tv_sec = maxtime.tv_sec - 1;
 115                                 kprintf("Time adjustment clamped to -1 second\n");
 116                         }
 117                 } else {
 118                         if (tv1.tv_sec == laststep.tv_sec) {
 119                                 crit_exit();
 120                                 return (EPERM);
 121                         }
 122                         if (delta.tv_sec > 1) {
 123                                 tv->tv_sec = tv1.tv_sec + 1;
 124                                 kprintf("Time adjustment clamped to +1 second\n");
 125                         }
 126                         laststep = *tv;
 127                 }
 128         }
 129
 130         ts.tv_sec = tv->tv_sec;
 131         ts.tv_nsec = tv->tv_usec * 1000;
 132         set_timeofday(&ts);
 133         crit_exit();
 134
 135         if (origcpu != 0)
 136                 lwkt_setcpu_self(globaldata_find(origcpu));
 137
 138         resettodr();
 139         return (0);
 140 }
 141
 142 /* ARGSUSED */
 143 int
 144 sys_clock_gettime(struct clock_gettime_args *uap)
 145 {
 146         struct timespec ats;
 147
 148         switch(uap->clock_id) {
 149         case CLOCK_REALTIME:
 150                 nanotime(&ats);
 151                 return (copyout(&ats, uap->tp, sizeof(ats)));
 152         case CLOCK_MONOTONIC:
 153                 nanouptime(&ats);
 154                 return (copyout(&ats, uap->tp, sizeof(ats)));
 155         default:
 156                 return (EINVAL);
 157         }
 158 }
 159
 160 /* ARGSUSED */
 161 int
 162 sys_clock_settime(struct clock_settime_args *uap)
 163 {
 164         struct thread *td = curthread;
 165         struct timeval atv;
 166         struct timespec ats;
 167         int error;
 168
 169         if ((error = suser(td)) != 0)
 170                 return (error);
 171         switch(uap->clock_id) {
 172         case CLOCK_REALTIME:
 173                 if ((error = copyin(uap->tp, &ats, sizeof(ats))) != 0)
 174                         return (error);
 175                 if (ats.tv_nsec < 0 || ats.tv_nsec >= 1000000000)
 176                         return (EINVAL);
 177                 /* XXX Don't convert nsec->usec and back */
 178                 TIMESPEC_TO_TIMEVAL(&atv, &ats);
 179                 error = settime(&atv);
 180                 return (error);
 181         default:
 182                 return (EINVAL);
 183         }
 184 }
 185
 186 int
 187 sys_clock_getres(struct clock_getres_args *uap)
 188 {
 189         struct timespec ts;
 190
 191         switch(uap->clock_id) {
 192         case CLOCK_REALTIME:
 193         case CLOCK_MONOTONIC:
 194                 /*
 195                  * Round up the result of the division cheaply
 196                  * by adding 1.  Rounding up is especially important
 197                  * if rounding down would give 0.  Perfect rounding
 198                  * is unimportant.
 199                  */
 200                 ts.tv_sec = 0;
 201                 ts.tv_nsec = 1000000000 / sys_cputimer->freq + 1;
 202                 return(copyout(&ts, uap->tp, sizeof(ts)));
 203         default:
 204                 return(EINVAL);
 205         }
 206 }
 207
 208 /*
 209  * nanosleep1()
 210  *
 211  *      This is a general helper function for nanosleep() (aka sleep() aka
 212  *      usleep()).
 213  *
 214  *      If there is less then one tick's worth of time left and
 215  *      we haven't done a yield, or the remaining microseconds is
 216  *      ridiculously low, do a yield.  This avoids having
 217  *      to deal with systimer overheads when the system is under
 218  *      heavy loads.  If we have done a yield already then use
 219  *      a systimer and an uninterruptable thread wait.
 220  *
 221  *      If there is more then a tick's worth of time left,
 222  *      calculate the baseline ticks and use an interruptable
 223  *      tsleep, then handle the fine-grained delay on the next
 224  *      loop.  This usually results in two sleeps occuring, a long one
 225  *      and a short one.
 226  */
 227 static void
 228 ns1_systimer(systimer_t info)
 229 {
 230         lwkt_schedule(info->data);
 231 }
 232
 233 static int
 234 nanosleep1(struct timespec *rqt, struct timespec *rmt)
 235 {
 236         static int nanowait;
 237         struct timespec ts, ts2, ts3;
 238         struct timeval tv;
 239         int error;
 240         int tried_yield;
 241
 242         if (rqt->tv_nsec < 0 || rqt->tv_nsec >= 1000000000)
 243                 return (EINVAL);
 244         if (rqt->tv_sec < 0 || (rqt->tv_sec == 0 && rqt->tv_nsec == 0))
 245                 return (0);
 246         nanouptime(&ts);
 247         timespecadd(&ts, rqt);          /* ts = target timestamp compare */
 248         TIMESPEC_TO_TIMEVAL(&tv, rqt);  /* tv = sleep interval */
 249         tried_yield = 0;
 250
 251         for (;;) {
 252                 int ticks;
 253                 struct systimer info;
 254
 255                 ticks = tv.tv_usec / tick;      /* approximate */
 256
 257                 if (tv.tv_sec == 0 && ticks == 0) {
 258                         thread_t td = curthread;
 259                         if (tried_yield || tv.tv_usec < sleep_hard_us) {
 260                                 tried_yield = 0;
 261                                 uio_yield();
 262                         } else {
 263                                 crit_enter_quick(td);
 264                                 systimer_init_oneshot(&info, ns1_systimer,
 265                                                 td, tv.tv_usec);
 266                                 lwkt_deschedule_self(td);
 267                                 crit_exit_quick(td);
 268                                 lwkt_switch();
 269                                 systimer_del(&info); /* make sure it's gone */
 270                         }
 271                         error = iscaught(td->td_lwp);
 272                 } else if (tv.tv_sec == 0) {
 273                         error = tsleep(&nanowait, PCATCH, "nanslp", ticks);
 274                 } else {
 275                         ticks = tvtohz_low(&tv); /* also handles overflow */
 276                         error = tsleep(&nanowait, PCATCH, "nanslp", ticks);
 277                 }
 278                 nanouptime(&ts2);
 279                 if (error && error != EWOULDBLOCK) {
 280                         if (error == ERESTART)
 281                                 error = EINTR;
 282                         if (rmt != NULL) {
 283                                 timespecsub(&ts, &ts2);
 284                                 if (ts.tv_sec < 0)
 285                                         timespecclear(&ts);
 286                                 *rmt = ts;
 287                         }
 288                         return (error);
 289                 }
 290                 if (timespeccmp(&ts2, &ts, >=))
 291                         return (0);
 292                 ts3 = ts;
 293                 timespecsub(&ts3, &ts2);
 294                 TIMESPEC_TO_TIMEVAL(&tv, &ts3);
 295         }
 296 }
 297
 298 /* ARGSUSED */
 299 int
 300 sys_nanosleep(struct nanosleep_args *uap)
 301 {
 302         int error;
 303         struct timespec rqt;
 304         struct timespec rmt;
 305
 306         error = copyin(uap->rqtp, &rqt, sizeof(rqt));
 307         if (error)
 308                 return (error);
 309
 310         error = nanosleep1(&rqt, &rmt);
 311
 312         /*
 313          * copyout the residual if nanosleep was interrupted.
 314          */
 315         if (error && uap->rmtp)
 316                 error = copyout(&rmt, uap->rmtp, sizeof(rmt));
 317         return (error);
 318 }
 319
 320 /* ARGSUSED */
 321 int
 322 sys_gettimeofday(struct gettimeofday_args *uap)
 323 {
 324         struct timeval atv;
 325         int error = 0;
 326
 327         if (uap->tp) {
 328                 microtime(&atv);
 329                 if ((error = copyout((caddr_t)&atv, (caddr_t)uap->tp,
 330                     sizeof (atv))))
 331                         return (error);
 332         }
 333         if (uap->tzp)
 334                 error = copyout((caddr_t)&tz, (caddr_t)uap->tzp,
 335                     sizeof (tz));
 336         return (error);
 337 }
 338
 339 /* ARGSUSED */
 340 int
 341 sys_settimeofday(struct settimeofday_args *uap)
 342 {
 343         struct thread *td = curthread;
 344         struct timeval atv;
 345         struct timezone atz;
 346         int error;
 347
 348         if ((error = suser(td)))
 349                 return (error);
 350         /* Verify all parameters before changing time. */
 351         if (uap->tv) {
 352                 if ((error = copyin((caddr_t)uap->tv, (caddr_t)&atv,
 353                     sizeof(atv))))
 354                         return (error);
 355                 if (atv.tv_usec < 0 || atv.tv_usec >= 1000000)
 356                         return (EINVAL);
 357         }
 358         if (uap->tzp &&
 359             (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz, sizeof(atz))))
 360                 return (error);
 361         if (uap->tv && (error = settime(&atv)))
 362                 return (error);
 363         if (uap->tzp)
 364                 tz = atz;
 365         return (0);
 366 }
 367
 368 static void
 369 kern_adjtime_common(void)
 370 {
 371         if ((ntp_delta >= 0 && ntp_delta < ntp_default_tick_delta) ||
 372             (ntp_delta < 0 && ntp_delta > -ntp_default_tick_delta))
 373                 ntp_tick_delta = ntp_delta;
 374         else if (ntp_delta > ntp_big_delta)
 375                 ntp_tick_delta = 10 * ntp_default_tick_delta;
 376         else if (ntp_delta < -ntp_big_delta)
 377                 ntp_tick_delta = -10 * ntp_default_tick_delta;
 378         else if (ntp_delta > 0)
 379                 ntp_tick_delta = ntp_default_tick_delta;
 380         else
 381                 ntp_tick_delta = -ntp_default_tick_delta;
 382 }
 383
 384 void
 385 kern_adjtime(int64_t delta, int64_t *odelta)
 386 {
 387         int origcpu;
 388
 389         if ((origcpu = mycpu->gd_cpuid) != 0)
 390                 lwkt_setcpu_self(globaldata_find(0));
 391
 392         crit_enter();
 393         *odelta = ntp_delta;
 394         ntp_delta = delta;
 395         kern_adjtime_common();
 396         crit_exit();
 397
 398         if (origcpu != 0)
 399                 lwkt_setcpu_self(globaldata_find(origcpu));
 400 }
 401
 402 static void
 403 kern_get_ntp_delta(int64_t *delta)
 404 {
 405         int origcpu;
 406
 407         if ((origcpu = mycpu->gd_cpuid) != 0)
 408                 lwkt_setcpu_self(globaldata_find(0));
 409
 410         crit_enter();
 411         *delta = ntp_delta;
 412         crit_exit();
 413
 414         if (origcpu != 0)
 415                 lwkt_setcpu_self(globaldata_find(origcpu));
 416 }
 417
 418 void
 419 kern_reladjtime(int64_t delta)
 420 {
 421         int origcpu;
 422
 423         if ((origcpu = mycpu->gd_cpuid) != 0)
 424                 lwkt_setcpu_self(globaldata_find(0));
 425
 426         crit_enter();
 427         ntp_delta += delta;
 428         kern_adjtime_common();
 429         crit_exit();
 430
 431         if (origcpu != 0)
 432                 lwkt_setcpu_self(globaldata_find(origcpu));
 433 }
 434
 435 static void
 436 kern_adjfreq(int64_t rate)
 437 {
 438         int origcpu;
 439
 440         if ((origcpu = mycpu->gd_cpuid) != 0)
 441                 lwkt_setcpu_self(globaldata_find(0));
 442
 443         crit_enter();
 444         ntp_tick_permanent = rate;
 445         crit_exit();
 446
 447         if (origcpu != 0)
 448                 lwkt_setcpu_self(globaldata_find(origcpu));
 449 }
 450
 451 /* ARGSUSED */
 452 int
 453 sys_adjtime(struct adjtime_args *uap)
 454 {
 455         struct thread *td = curthread;
 456         struct timeval atv;
 457         int64_t ndelta, odelta;
 458         int error;
 459
 460         if ((error = suser(td)))
 461                 return (error);
 462         if ((error =
 463             copyin((caddr_t)uap->delta, (caddr_t)&atv, sizeof(struct timeval))))
 464                 return (error);
 465
 466         /*
 467          * Compute the total correction and the rate at which to apply it.
 468          * Round the adjustment down to a whole multiple of the per-tick
 469          * delta, so that after some number of incremental changes in
 470          * hardclock(), tickdelta will become zero, lest the correction
 471          * overshoot and start taking us away from the desired final time.
 472          */
 473         ndelta = (int64_t)atv.tv_sec * 1000000000 + atv.tv_usec * 1000;
 474         kern_adjtime(ndelta, &odelta);
 475
 476         if (uap->olddelta) {
 477                 atv.tv_sec = odelta / 1000000000;
 478                 atv.tv_usec = odelta % 1000000000 / 1000;
 479                 (void) copyout((caddr_t)&atv, (caddr_t)uap->olddelta,
 480                     sizeof(struct timeval));
 481         }
 482         return (0);
 483 }
 484
 485 static int
 486 sysctl_adjtime(SYSCTL_HANDLER_ARGS)
 487 {
 488         int64_t delta;
 489         int error;
 490
 491         if (req->newptr != NULL) {
 492                 if (suser(curthread))
 493                         return (EPERM);
 494                 error = SYSCTL_IN(req, &delta, sizeof(delta));
 495                 if (error)
 496                         return (error);
 497                 kern_reladjtime(delta);
 498         }
 499
 500         if (req->oldptr)
 501                 kern_get_ntp_delta(&delta);
 502         error = SYSCTL_OUT(req, &delta, sizeof(delta));
 503         return (error);
 504 }
 505
 506 /*
 507  * delta is in nanoseconds.
 508  */
 509 static int
 510 sysctl_delta(SYSCTL_HANDLER_ARGS)
 511 {
 512         int64_t delta, old_delta;
 513         int error;
 514
 515         if (req->newptr != NULL) {
 516                 if (suser(curthread))
 517                         return (EPERM);
 518                 error = SYSCTL_IN(req, &delta, sizeof(delta));
 519                 if (error)
 520                         return (error);
 521                 kern_adjtime(delta, &old_delta);
 522         }
 523
 524         if (req->oldptr != NULL)
 525                 kern_get_ntp_delta(&old_delta);
 526         error = SYSCTL_OUT(req, &old_delta, sizeof(old_delta));
 527         return (error);
 528 }
 529
 530 /*
 531  * frequency is in nanoseconds per second shifted left 32.
 532  * kern_adjfreq() needs it in nanoseconds per tick shifted left 32.
 533  */
 534 static int
 535 sysctl_adjfreq(SYSCTL_HANDLER_ARGS)
 536 {
 537         int64_t freqdelta;
 538         int error;
 539
 540         if (req->newptr != NULL) {
 541                 if (suser(curthread))
 542                         return (EPERM);
 543                 error = SYSCTL_IN(req, &freqdelta, sizeof(freqdelta));
 544                 if (error)
 545                         return (error);
 546
 547                 freqdelta /= hz;
 548                 kern_adjfreq(freqdelta);
 549         }
 550
 551         if (req->oldptr != NULL)
 552                 freqdelta = ntp_tick_permanent * hz;
 553         error = SYSCTL_OUT(req, &freqdelta, sizeof(freqdelta));
 554         if (error)
 555                 return (error);
 556
 557         return (0);
 558 }
 559
 560 SYSCTL_NODE(_kern, OID_AUTO, ntp, CTLFLAG_RW, 0, "NTP related controls");
 561 SYSCTL_PROC(_kern_ntp, OID_AUTO, permanent,
 562     CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
 563     sysctl_adjfreq, "Q", "permanent correction per second");
 564 SYSCTL_PROC(_kern_ntp, OID_AUTO, delta,
 565     CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
 566     sysctl_delta, "Q", "one-time delta");
 567 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, big_delta, CTLFLAG_RD,
 568     &ntp_big_delta, sizeof(ntp_big_delta), "Q",
 569     "threshold for fast adjustment");
 570 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, tick_delta, CTLFLAG_RD,
 571     &ntp_tick_delta, sizeof(ntp_tick_delta), "LU",
 572     "per-tick adjustment");
 573 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, default_tick_delta, CTLFLAG_RD,
 574     &ntp_default_tick_delta, sizeof(ntp_default_tick_delta), "LU",
 575     "default per-tick adjustment");
 576 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, next_leap_second, CTLFLAG_RW,
 577     &ntp_leap_second, sizeof(ntp_leap_second), "LU",
 578     "next leap second");
 579 SYSCTL_INT(_kern_ntp, OID_AUTO, insert_leap_second, CTLFLAG_RW,
 580     &ntp_leap_insert, 0, "insert or remove leap second");
 581 SYSCTL_PROC(_kern_ntp, OID_AUTO, adjust,
 582     CTLTYPE_QUAD|CTLFLAG_RW, 0, 0,
 583     sysctl_adjtime, "Q", "relative adjust for delta");
 584
 585 /*
 586  * Get value of an interval timer.  The process virtual and
 587  * profiling virtual time timers are kept in the p_stats area, since
 588  * they can be swapped out.  These are kept internally in the
 589  * way they are specified externally: in time until they expire.
 590  *
 591  * The real time interval timer is kept in the process table slot
 592  * for the process, and its value (it_value) is kept as an
 593  * absolute time rather than as a delta, so that it is easy to keep
 594  * periodic real-time signals from drifting.
 595  *
 596  * Virtual time timers are processed in the hardclock() routine of
 597  * kern_clock.c.  The real time timer is processed by a timeout
 598  * routine, called from the softclock() routine.  Since a callout
 599  * may be delayed in real time due to interrupt processing in the system,
 600  * it is possible for the real time timeout routine (realitexpire, given below),
 601  * to be delayed in real time past when it is supposed to occur.  It
 602  * does not suffice, therefore, to reload the real timer .it_value from the
 603  * real time timers .it_interval.  Rather, we compute the next time in
 604  * absolute time the timer should go off.
 605  */
 606 /* ARGSUSED */
 607 int
 608 sys_getitimer(struct getitimer_args *uap)
 609 {
 610         struct proc *p = curproc;
 611         struct timeval ctv;
 612         struct itimerval aitv;
 613
 614         if (uap->which > ITIMER_PROF)
 615                 return (EINVAL);
 616         crit_enter();
 617         if (uap->which == ITIMER_REAL) {
 618                 /*
 619                  * Convert from absolute to relative time in .it_value
 620                  * part of real time timer.  If time for real time timer
 621                  * has passed return 0, else return difference between
 622                  * current time and time for the timer to go off.
 623                  */
 624                 aitv = p->p_realtimer;
 625                 if (timevalisset(&aitv.it_value)) {
 626                         getmicrouptime(&ctv);
 627                         if (timevalcmp(&aitv.it_value, &ctv, <))
 628                                 timevalclear(&aitv.it_value);
 629                         else
 630                                 timevalsub(&aitv.it_value, &ctv);
 631                 }
 632         } else {
 633                 aitv = p->p_timer[uap->which];
 634         }
 635         crit_exit();
 636         return (copyout((caddr_t)&aitv, (caddr_t)uap->itv,
 637             sizeof (struct itimerval)));
 638 }
 639
 640 /* ARGSUSED */
 641 int
 642 sys_setitimer(struct setitimer_args *uap)
 643 {
 644         struct itimerval aitv;
 645         struct timeval ctv;
 646         struct itimerval *itvp;
 647         struct proc *p = curproc;
 648         int error;
 649
 650         if (uap->which > ITIMER_PROF)
 651                 return (EINVAL);
 652         itvp = uap->itv;
 653         if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv,
 654             sizeof(struct itimerval))))
 655                 return (error);
 656         if ((uap->itv = uap->oitv) &&
 657             (error = sys_getitimer((struct getitimer_args *)uap)))
 658                 return (error);
 659         if (itvp == 0)
 660                 return (0);
 661         if (itimerfix(&aitv.it_value))
 662                 return (EINVAL);
 663         if (!timevalisset(&aitv.it_value))
 664                 timevalclear(&aitv.it_interval);
 665         else if (itimerfix(&aitv.it_interval))
 666                 return (EINVAL);
 667         crit_enter();
 668         if (uap->which == ITIMER_REAL) {
 669                 if (timevalisset(&p->p_realtimer.it_value))
 670                         callout_stop(&p->p_ithandle);
 671                 if (timevalisset(&aitv.it_value))
 672                         callout_reset(&p->p_ithandle,
 673                             tvtohz_high(&aitv.it_value), realitexpire, p);
 674                 getmicrouptime(&ctv);
 675                 timevaladd(&aitv.it_value, &ctv);
 676                 p->p_realtimer = aitv;
 677         } else {
 678                 p->p_timer[uap->which] = aitv;
 679         }
 680         crit_exit();
 681         return (0);
 682 }
 683
 684 /*
 685  * Real interval timer expired:
 686  * send process whose timer expired an alarm signal.
 687  * If time is not set up to reload, then just return.
 688  * Else compute next time timer should go off which is > current time.
 689  * This is where delay in processing this timeout causes multiple
 690  * SIGALRM calls to be compressed into one.
 691  * tvtohz_high() always adds 1 to allow for the time until the next clock
 692  * interrupt being strictly less than 1 clock tick, but we don't want
 693  * that here since we want to appear to be in sync with the clock
 694  * interrupt even when we're delayed.
 695  */
 696 void
 697 realitexpire(void *arg)
 698 {
 699         struct proc *p;
 700         struct timeval ctv, ntv;
 701
 702         p = (struct proc *)arg;
 703         ksignal(p, SIGALRM);
 704         if (!timevalisset(&p->p_realtimer.it_interval)) {
 705                 timevalclear(&p->p_realtimer.it_value);
 706                 return;
 707         }
 708         for (;;) {
 709                 crit_enter();
 710                 timevaladd(&p->p_realtimer.it_value,
 711                     &p->p_realtimer.it_interval);
 712                 getmicrouptime(&ctv);
 713                 if (timevalcmp(&p->p_realtimer.it_value, &ctv, >)) {
 714                         ntv = p->p_realtimer.it_value;
 715                         timevalsub(&ntv, &ctv);
 716                         callout_reset(&p->p_ithandle, tvtohz_low(&ntv),
 717                                       realitexpire, p);
 718                         crit_exit();
 719                         return;
 720                 }
 721                 crit_exit();
 722         }
 723 }
 724
 725 /*
 726  * Check that a proposed value to load into the .it_value or
 727  * .it_interval part of an interval timer is acceptable, and
 728  * fix it to have at least minimal value (i.e. if it is less
 729  * than the resolution of the clock, round it up.)
 730  */
 731 int
 732 itimerfix(struct timeval *tv)
 733 {
 734
 735         if (tv->tv_sec < 0 || tv->tv_sec > 100000000 ||
 736             tv->tv_usec < 0 || tv->tv_usec >= 1000000)
 737                 return (EINVAL);
 738         if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
 739                 tv->tv_usec = tick;
 740         return (0);
 741 }
 742
 743 /*
 744  * Decrement an interval timer by a specified number
 745  * of microseconds, which must be less than a second,
 746  * i.e. < 1000000.  If the timer expires, then reload
 747  * it.  In this case, carry over (usec - old value) to
 748  * reduce the value reloaded into the timer so that
 749  * the timer does not drift.  This routine assumes
 750  * that it is called in a context where the timers
 751  * on which it is operating cannot change in value.
 752  */
 753 int
 754 itimerdecr(struct itimerval *itp, int usec)
 755 {
 756
 757         if (itp->it_value.tv_usec < usec) {
 758                 if (itp->it_value.tv_sec == 0) {
 759                         /* expired, and already in next interval */
 760                         usec -= itp->it_value.tv_usec;
 761                         goto expire;
 762                 }
 763                 itp->it_value.tv_usec += 1000000;
 764                 itp->it_value.tv_sec--;
 765         }
 766         itp->it_value.tv_usec -= usec;
 767         usec = 0;
 768         if (timevalisset(&itp->it_value))
 769                 return (1);
 770         /* expired, exactly at end of interval */
 771 expire:
 772         if (timevalisset(&itp->it_interval)) {
 773                 itp->it_value = itp->it_interval;
 774                 itp->it_value.tv_usec -= usec;
 775                 if (itp->it_value.tv_usec < 0) {
 776                         itp->it_value.tv_usec += 1000000;
 777                         itp->it_value.tv_sec--;
 778                 }
 779         } else
 780                 itp->it_value.tv_usec = 0;              /* sec is already 0 */
 781         return (0);
 782 }
 783
 784 /*
 785  * Add and subtract routines for timevals.
 786  * N.B.: subtract routine doesn't deal with
 787  * results which are before the beginning,
 788  * it just gets very confused in this case.
 789  * Caveat emptor.
 790  */
 791 void
 792 timevaladd(struct timeval *t1, struct timeval *t2)
 793 {
 794
 795         t1->tv_sec += t2->tv_sec;
 796         t1->tv_usec += t2->tv_usec;
 797         timevalfix(t1);
 798 }
 799
 800 void
 801 timevalsub(struct timeval *t1, struct timeval *t2)
 802 {
 803
 804         t1->tv_sec -= t2->tv_sec;
 805         t1->tv_usec -= t2->tv_usec;
 806         timevalfix(t1);
 807 }
 808
 809 static void
 810 timevalfix(struct timeval *t1)
 811 {
 812
 813         if (t1->tv_usec < 0) {
 814                 t1->tv_sec--;
 815                 t1->tv_usec += 1000000;
 816         }
 817         if (t1->tv_usec >= 1000000) {
 818                 t1->tv_sec++;
 819                 t1->tv_usec -= 1000000;
 820         }
 821 }
 822
 823 /*
 824  * ratecheck(): simple time-based rate-limit checking.
 825  */
 826 int
 827 ratecheck(struct timeval *lasttime, const struct timeval *mininterval)
 828 {
 829         struct timeval tv, delta;
 830         int rv = 0;
 831
 832         getmicrouptime(&tv);            /* NB: 10ms precision */
 833         delta = tv;
 834         timevalsub(&delta, lasttime);
 835
 836         /*
 837          * check for 0,0 is so that the message will be seen at least once,
 838          * even if interval is huge.
 839          */
 840         if (timevalcmp(&delta, mininterval, >=) ||
 841             (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
 842                 *lasttime = tv;
 843                 rv = 1;
 844         }
 845
 846         return (rv);
 847 }
 848
 849 /*
 850  * ppsratecheck(): packets (or events) per second limitation.
 851  *
 852  * Return 0 if the limit is to be enforced (e.g. the caller
 853  * should drop a packet because of the rate limitation).
 854  *
 855  * maxpps of 0 always causes zero to be returned.  maxpps of -1
 856  * always causes 1 to be returned; this effectively defeats rate
 857  * limiting.
 858  *
 859  * Note that we maintain the struct timeval for compatibility
 860  * with other bsd systems.  We reuse the storage and just monitor
 861  * clock ticks for minimal overhead.
 862  */
 863 int
 864 ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
 865 {
 866         int now;
 867
 868         /*
 869          * Reset the last time and counter if this is the first call
 870          * or more than a second has passed since the last update of
 871          * lasttime.
 872          */
 873         now = ticks;
 874         if (lasttime->tv_sec == 0 || (u_int)(now - lasttime->tv_sec) >= hz) {
 875                 lasttime->tv_sec = now;
 876                 *curpps = 1;
 877                 return (maxpps != 0);
 878         } else {
 879                 (*curpps)++;            /* NB: ignore potential overflow */
 880                 return (maxpps < 0 || *curpps < maxpps);
 881         }
 882 }
 883