/* * Copyright 2005 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ #pragma ident "%Z%%M% %I% %E% SMI" /* * Copyright (c) 1982, 1986 Regents of the University of California. * All rights reserved. The Berkeley software License Agreement * specifies the terms and conditions for redistribution. */ #include #include #include #include #include #include #include #include #include #include #include #include #include static void realitexpire(void *); static void realprofexpire(void *); static void timeval_advance(struct timeval *, struct timeval *); kmutex_t tod_lock; /* protects time-of-day stuff */ /* * Constant to define the minimum interval value of the ITIMER_REALPROF timer. * Value is in microseconds; defaults to 500 usecs. Setting this value * significantly lower may allow for denial-of-service attacks. */ int itimer_realprof_minimum = 500; /* * macro to compare a timeval to a timestruc */ #define TVTSCMP(tvp, tsp, cmp) \ /* CSTYLED */ \ ((tvp)->tv_sec cmp (tsp)->tv_sec || \ ((tvp)->tv_sec == (tsp)->tv_sec && \ /* CSTYLED */ \ (tvp)->tv_usec * 1000 cmp (tsp)->tv_nsec)) /* * 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. */ /* * SunOS function to generate monotonically increasing time values. */ void uniqtime(struct timeval *tv) { static struct timeval last; timestruc_t ts; time_t sec; int usec, nsec; /* * protect modification of last */ mutex_enter(&tod_lock); gethrestime(&ts); /* * Fast algorithm to convert nsec to usec -- see hrt2ts() * in common/os/timers.c for a full description. */ nsec = ts.tv_nsec; usec = nsec + (nsec >> 2); usec = nsec + (usec >> 1); usec = nsec + (usec >> 2); usec = nsec + (usec >> 4); usec = nsec - (usec >> 3); usec = nsec + (usec >> 2); usec = nsec + (usec >> 3); usec = nsec + (usec >> 4); usec = nsec + (usec >> 1); usec = nsec + (usec >> 6); usec = usec >> 10; sec = ts.tv_sec; /* * Try to keep timestamps unique, but don't be obsessive about * it in the face of large differences. */ if ((sec <= last.tv_sec) && /* same or lower seconds, and */ ((sec != last.tv_sec) || /* either different second or */ (usec <= last.tv_usec)) && /* lower microsecond, and */ ((last.tv_sec - sec) <= 5)) { /* not way back in time */ sec = last.tv_sec; usec = last.tv_usec + 1; if (usec >= MICROSEC) { usec -= MICROSEC; sec++; } } last.tv_sec = sec; last.tv_usec = usec; mutex_exit(&tod_lock); tv->tv_sec = sec; tv->tv_usec = usec; } /* * Timestamps are exported from the kernel in several places. * Such timestamps are commonly used for either uniqueness or for * sequencing - truncation to 32-bits is fine for uniqueness, * but sequencing is going to take more work as we get closer to 2038! */ void uniqtime32(struct timeval32 *tv32p) { struct timeval tv; uniqtime(&tv); TIMEVAL_TO_TIMEVAL32(tv32p, &tv); } int gettimeofday(struct timeval *tp) { struct timeval atv; if (tp) { uniqtime(&atv); if (get_udatamodel() == DATAMODEL_NATIVE) { if (copyout(&atv, tp, sizeof (atv))) return (set_errno(EFAULT)); } else { struct timeval32 tv32; if (TIMEVAL_OVERFLOW(&atv)) return (set_errno(EOVERFLOW)); TIMEVAL_TO_TIMEVAL32(&tv32, &atv); if (copyout(&tv32, tp, sizeof (tv32))) return (set_errno(EFAULT)); } } return (0); } int getitimer(uint_t which, struct itimerval *itv) { int error; if (get_udatamodel() == DATAMODEL_NATIVE) error = xgetitimer(which, itv, 0); else { struct itimerval kitv; if ((error = xgetitimer(which, &kitv, 1)) == 0) { if (ITIMERVAL_OVERFLOW(&kitv)) { error = EOVERFLOW; } else { struct itimerval32 itv32; ITIMERVAL_TO_ITIMERVAL32(&itv32, &kitv); if (copyout(&itv32, itv, sizeof (itv32)) != 0) error = EFAULT; } } } return (error ? (set_errno(error)) : 0); } int xgetitimer(uint_t which, struct itimerval *itv, int iskaddr) { struct proc *p = curproc; struct timeval now; struct itimerval aitv; hrtime_t ts, first, interval, remain; mutex_enter(&p->p_lock); switch (which) { case ITIMER_VIRTUAL: case ITIMER_PROF: aitv = ttolwp(curthread)->lwp_timer[which]; break; case ITIMER_REAL: uniqtime(&now); aitv = p->p_realitimer; if (timerisset(&aitv.it_value)) { /*CSTYLED*/ if (timercmp(&aitv.it_value, &now, <)) { timerclear(&aitv.it_value); } else { timevalsub(&aitv.it_value, &now); } } break; case ITIMER_REALPROF: if (curproc->p_rprof_cyclic == CYCLIC_NONE) { bzero(&aitv, sizeof (aitv)); break; } aitv = curproc->p_rprof_timer; first = tv2hrt(&aitv.it_value); interval = tv2hrt(&aitv.it_interval); if ((ts = gethrtime()) < first) { /* * We haven't gone off for the first time; the time * remaining is simply the first time we will go * off minus the current time. */ remain = first - ts; } else { if (interval == 0) { /* * This was set as a one-shot, and we've * already gone off; there is no time * remaining. */ remain = 0; } else { /* * We have a non-zero interval; we need to * determine how far we are into the current * interval, and subtract that from the * interval to determine the time remaining. */ remain = interval - ((ts - first) % interval); } } hrt2tv(remain, &aitv.it_value); break; default: mutex_exit(&p->p_lock); return (EINVAL); } mutex_exit(&p->p_lock); if (iskaddr) { bcopy(&aitv, itv, sizeof (*itv)); } else { ASSERT(get_udatamodel() == DATAMODEL_NATIVE); if (copyout(&aitv, itv, sizeof (*itv))) return (EFAULT); } return (0); } int setitimer(uint_t which, struct itimerval *itv, struct itimerval *oitv) { int error; if (oitv != NULL) if ((error = getitimer(which, oitv)) != 0) return (error); if (itv == NULL) return (0); if (get_udatamodel() == DATAMODEL_NATIVE) error = xsetitimer(which, itv, 0); else { struct itimerval32 itv32; struct itimerval kitv; if (copyin(itv, &itv32, sizeof (itv32))) error = EFAULT; ITIMERVAL32_TO_ITIMERVAL(&kitv, &itv32); error = xsetitimer(which, &kitv, 1); } return (error ? (set_errno(error)) : 0); } int xsetitimer(uint_t which, struct itimerval *itv, int iskaddr) { struct itimerval aitv; struct timeval now; struct proc *p = curproc; kthread_t *t; timeout_id_t tmp_id; cyc_handler_t hdlr; cyc_time_t when; cyclic_id_t cyclic; hrtime_t ts; int min; if (itv == NULL) return (0); if (iskaddr) { bcopy(itv, &aitv, sizeof (aitv)); } else { ASSERT(get_udatamodel() == DATAMODEL_NATIVE); if (copyin(itv, &aitv, sizeof (aitv))) return (EFAULT); } if (which == ITIMER_REALPROF) { min = MAX((int)(cyclic_getres() / (NANOSEC / MICROSEC)), itimer_realprof_minimum); } else { min = usec_per_tick; } if (itimerfix(&aitv.it_value, min) || (itimerfix(&aitv.it_interval, min) && timerisset(&aitv.it_value))) return (EINVAL); mutex_enter(&p->p_lock); switch (which) { case ITIMER_REAL: /* * The SITBUSY flag prevents conflicts with multiple * threads attempting to perform setitimer(ITIMER_REAL) * at the same time, even when we drop p->p_lock below. * Any blocked thread returns successfully because the * effect is the same as if it got here first, finished, * and the other thread then came through and destroyed * what it did. We are just protecting the system from * malfunctioning due to the race condition. */ if (p->p_flag & SITBUSY) { mutex_exit(&p->p_lock); return (0); } p->p_flag |= SITBUSY; while ((tmp_id = p->p_itimerid) != 0) { /* * Avoid deadlock in callout_delete (called from * untimeout) which may go to sleep (while holding * p_lock). Drop p_lock and re-acquire it after * untimeout returns. Need to clear p_itimerid * while holding p_lock. */ p->p_itimerid = 0; mutex_exit(&p->p_lock); (void) untimeout(tmp_id); mutex_enter(&p->p_lock); } if (timerisset(&aitv.it_value)) { uniqtime(&now); timevaladd(&aitv.it_value, &now); p->p_itimerid = realtime_timeout(realitexpire, p, hzto(&aitv.it_value)); } p->p_realitimer = aitv; p->p_flag &= ~SITBUSY; break; case ITIMER_REALPROF: cyclic = p->p_rprof_cyclic; p->p_rprof_cyclic = CYCLIC_NONE; mutex_exit(&p->p_lock); /* * We're now going to acquire cpu_lock, remove the old cyclic * if necessary, and add our new cyclic. */ mutex_enter(&cpu_lock); if (cyclic != CYCLIC_NONE) cyclic_remove(cyclic); if (!timerisset(&aitv.it_value)) { /* * If we were passed a value of 0, we're done. */ mutex_exit(&cpu_lock); return (0); } hdlr.cyh_func = realprofexpire; hdlr.cyh_arg = p; hdlr.cyh_level = CY_LOW_LEVEL; when.cyt_when = (ts = gethrtime() + tv2hrt(&aitv.it_value)); when.cyt_interval = tv2hrt(&aitv.it_interval); if (when.cyt_interval == 0) { /* * Using the same logic as for CLOCK_HIGHRES timers, we * set the interval to be INT64_MAX - when.cyt_when to * effect a one-shot; see the comment in clock_highres.c * for more details on why this works. */ when.cyt_interval = INT64_MAX - when.cyt_when; } cyclic = cyclic_add(&hdlr, &when); mutex_exit(&cpu_lock); /* * We have now successfully added the cyclic. Reacquire * p_lock, and see if anyone has snuck in. */ mutex_enter(&p->p_lock); if (p->p_rprof_cyclic != CYCLIC_NONE) { /* * We're racing with another thread establishing an * ITIMER_REALPROF interval timer. We'll let the other * thread win (this is a race at the application level, * so letting the other thread win is acceptable). */ mutex_exit(&p->p_lock); mutex_enter(&cpu_lock); cyclic_remove(cyclic); mutex_exit(&cpu_lock); return (0); } /* * Success. Set our tracking variables in the proc structure, * cancel any outstanding ITIMER_PROF, and allocate the * per-thread SIGPROF buffers, if possible. */ hrt2tv(ts, &aitv.it_value); p->p_rprof_timer = aitv; p->p_rprof_cyclic = cyclic; t = p->p_tlist; do { struct itimerval *itvp; itvp = &ttolwp(t)->lwp_timer[ITIMER_PROF]; timerclear(&itvp->it_interval); timerclear(&itvp->it_value); if (t->t_rprof != NULL) continue; t->t_rprof = kmem_zalloc(sizeof (struct rprof), KM_NOSLEEP); aston(t); } while ((t = t->t_forw) != p->p_tlist); break; case ITIMER_VIRTUAL: ttolwp(curthread)->lwp_timer[ITIMER_VIRTUAL] = aitv; break; case ITIMER_PROF: if (p->p_rprof_cyclic != CYCLIC_NONE) { /* * Silently ignore ITIMER_PROF if ITIMER_REALPROF * is in effect. */ break; } ttolwp(curthread)->lwp_timer[ITIMER_PROF] = aitv; break; default: mutex_exit(&p->p_lock); return (EINVAL); } mutex_exit(&p->p_lock); return (0); } /* * 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. */ static void realitexpire(void *arg) { struct proc *p = arg; struct timeval *valp = &p->p_realitimer.it_value; struct timeval *intervalp = &p->p_realitimer.it_interval; #if !defined(_LP64) clock_t ticks; #endif mutex_enter(&p->p_lock); #if !defined(_LP64) if ((ticks = hzto(valp)) > 1) { /* * If we are executing before we were meant to, it must be * because of an overflow in a prior hzto() calculation. * In this case, we want to go to sleep for the recalculated * number of ticks. For the special meaning of the value "1" * see comment in timespectohz(). */ p->p_itimerid = realtime_timeout(realitexpire, p, ticks); mutex_exit(&p->p_lock); return; } #endif sigtoproc(p, NULL, SIGALRM); if (!timerisset(intervalp)) { timerclear(valp); p->p_itimerid = 0; } else { /* advance timer value past current time */ timeval_advance(valp, intervalp); p->p_itimerid = realtime_timeout(realitexpire, p, hzto(valp)); } mutex_exit(&p->p_lock); } /* * Real time profiling interval timer expired: * Increment microstate counters for each lwp in the process * and ensure that running lwps are kicked into the kernel. * If time is not set up to reload, then just return. * Else compute next time timer should go off which is > current time, * as above. */ static void realprofexpire(void *arg) { struct proc *p = arg; kthread_t *t; mutex_enter(&p->p_lock); if ((t = p->p_tlist) == NULL) { mutex_exit(&p->p_lock); return; } do { int mstate; /* * Attempt to allocate the SIGPROF buffer, but don't sleep. */ if (t->t_rprof == NULL) t->t_rprof = kmem_zalloc(sizeof (struct rprof), KM_NOSLEEP); if (t->t_rprof == NULL) continue; thread_lock(t); switch (t->t_state) { case TS_SLEEP: /* * Don't touch the lwp is it is swapped out. */ if (!(t->t_schedflag & TS_LOAD)) { mstate = LMS_SLEEP; break; } switch (mstate = ttolwp(t)->lwp_mstate.ms_prev) { case LMS_TFAULT: case LMS_DFAULT: case LMS_KFAULT: case LMS_USER_LOCK: break; default: mstate = LMS_SLEEP; break; } break; case TS_RUN: mstate = LMS_WAIT_CPU; break; case TS_ONPROC: switch (mstate = t->t_mstate) { case LMS_USER: case LMS_SYSTEM: case LMS_TRAP: break; default: mstate = LMS_SYSTEM; break; } break; default: mstate = t->t_mstate; break; } t->t_rprof->rp_anystate = 1; t->t_rprof->rp_state[mstate]++; aston(t); /* * force the thread into the kernel * if it is not already there. */ if (t->t_state == TS_ONPROC && t->t_cpu != CPU) poke_cpu(t->t_cpu->cpu_id); thread_unlock(t); } while ((t = t->t_forw) != p->p_tlist); mutex_exit(&p->p_lock); } /* * Advances timer value past the current time of day. See the detailed * comment for this logic in realitsexpire(), above. */ static void timeval_advance(struct timeval *valp, struct timeval *intervalp) { int cnt2nth; struct timeval interval2nth; for (;;) { interval2nth = *intervalp; for (cnt2nth = 0; ; cnt2nth++) { timevaladd(valp, &interval2nth); /*CSTYLED*/ if (TVTSCMP(valp, &hrestime, >)) break; timevaladd(&interval2nth, &interval2nth); } if (cnt2nth == 0) break; timevalsub(valp, &interval2nth); } } /* * Check that a proposed value to load into the .it_value or .it_interval * part of an interval timer is acceptable, and set it to at least a * specified minimal value. */ int itimerfix(struct timeval *tv, int minimum) { if (tv->tv_sec < 0 || tv->tv_sec > 100000000 || tv->tv_usec < 0 || tv->tv_usec >= MICROSEC) return (EINVAL); if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < minimum) tv->tv_usec = minimum; return (0); } /* * Same as itimerfix, except a) it takes a timespec instead of a timeval and * b) it doesn't truncate based on timeout granularity; consumers of this * interface (e.g. timer_settime()) depend on the passed timespec not being * modified implicitly. */ int itimerspecfix(timespec_t *tv) { if (tv->tv_sec < 0 || tv->tv_nsec < 0 || tv->tv_nsec >= NANOSEC) return (EINVAL); 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 * reducint 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 += MICROSEC; itp->it_value.tv_sec--; } itp->it_value.tv_usec -= usec; usec = 0; if (timerisset(&itp->it_value)) return (1); /* expired, exactly at end of interval */ expire: if (timerisset(&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 += MICROSEC; 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, struct timeval *t2) { t1->tv_sec += t2->tv_sec; t1->tv_usec += t2->tv_usec; timevalfix(t1); } void timevalsub(struct timeval *t1, struct timeval *t2) { t1->tv_sec -= t2->tv_sec; t1->tv_usec -= t2->tv_usec; timevalfix(t1); } void timevalfix(struct timeval *t1) { if (t1->tv_usec < 0) { t1->tv_sec--; t1->tv_usec += MICROSEC; } if (t1->tv_usec >= MICROSEC) { t1->tv_sec++; t1->tv_usec -= MICROSEC; } } /* * Same as the routines above. These routines take a timespec instead * of a timeval. */ void timespecadd(timespec_t *t1, timespec_t *t2) { t1->tv_sec += t2->tv_sec; t1->tv_nsec += t2->tv_nsec; timespecfix(t1); } void timespecsub(timespec_t *t1, timespec_t *t2) { t1->tv_sec -= t2->tv_sec; t1->tv_nsec -= t2->tv_nsec; timespecfix(t1); } void timespecfix(timespec_t *t1) { if (t1->tv_nsec < 0) { t1->tv_sec--; t1->tv_nsec += NANOSEC; } else { if (t1->tv_nsec >= NANOSEC) { t1->tv_sec++; t1->tv_nsec -= NANOSEC; } } } /* * Compute number of hz until specified time. * Used to compute third argument to timeout() from an absolute time. */ clock_t hzto(struct timeval *tv) { timespec_t ts, now; ts.tv_sec = tv->tv_sec; ts.tv_nsec = tv->tv_usec * 1000; gethrestime_lasttick(&now); return (timespectohz(&ts, now)); } /* * Compute number of hz until specified time for a given timespec value. * Used to compute third argument to timeout() from an absolute time. */ clock_t timespectohz(timespec_t *tv, timespec_t now) { clock_t ticks; time_t sec; int nsec; /* * Compute number of ticks we will see between now and * the target time; returns "1" if the destination time * is before the next tick, so we always get some delay, * and returns LONG_MAX ticks if we would overflow. */ sec = tv->tv_sec - now.tv_sec; nsec = tv->tv_nsec - now.tv_nsec + nsec_per_tick - 1; if (nsec < 0) { sec--; nsec += NANOSEC; } else if (nsec >= NANOSEC) { sec++; nsec -= NANOSEC; } ticks = NSEC_TO_TICK(nsec); /* * Compute ticks, accounting for negative and overflow as above. * Overflow protection kicks in at about 70 weeks for hz=50 * and at about 35 weeks for hz=100. (Rather longer for the 64-bit * kernel :-) */ if (sec < 0 || (sec == 0 && ticks < 1)) ticks = 1; /* protect vs nonpositive */ else if (sec > (LONG_MAX - ticks) / hz) ticks = LONG_MAX; /* protect vs overflow */ else ticks += sec * hz; /* common case */ return (ticks); } /* * Same as timespectohz() except that we adjust the clock ticks down a bit. * If we will be waiting for a long time, we may encounter skewing problems * due to adjtime() system calls. Since we can skew up to 1/16 lbolt rate * if adjtime is going crazy, we reduce the time delta since timeout() takes * clock ticks rather than wallclock elapsed time. This may cause the caller * (who calls timeout()) to return with a timeout prematurely and callers * must accommodate this. See lwp_timeout(), queue_lwptimer() and * cv_waituntil_sig(), currently the only callers of this function. */ clock_t timespectohz_adj(timespec_t *tv, timespec_t now) { timespec_t wait_time = *tv; timespecsub(&wait_time, &now); wait_time.tv_sec -= wait_time.tv_sec >> 4; wait_time.tv_nsec -= wait_time.tv_nsec >> 4; timespecadd(&wait_time, &now); return (timespectohz(&wait_time, now)); } /* * hrt2ts(): convert from hrtime_t to timestruc_t. * * All this routine really does is: * * tsp->sec = hrt / NANOSEC; * tsp->nsec = hrt % NANOSEC; * * The black magic below avoids doing a 64-bit by 32-bit integer divide, * which is quite expensive. There's actually much more going on here than * it might first appear -- don't try this at home. * * For the adventuresome, here's an explanation of how it works. * * Multiplication by a fixed constant is easy -- you just do the appropriate * shifts and adds. For example, to multiply by 10, we observe that * * x * 10 = x * (8 + 2) * = (x * 8) + (x * 2) * = (x << 3) + (x << 1). * * In general, you can read the algorithm right off the bits: the number 10 * is 1010 in binary; bits 1 and 3 are ones, so x * 10 = (x << 1) + (x << 3). * * Sometimes you can do better. For example, 15 is 1111 binary, so the normal * shift/add computation is x * 15 = (x << 0) + (x << 1) + (x << 2) + (x << 3). * But, it's cheaper if you capitalize on the fact that you have a run of ones: * 1111 = 10000 - 1, hence x * 15 = (x << 4) - (x << 0). [You would never * actually perform the operation << 0, since it's a no-op; I'm just writing * it that way for clarity.] * * The other way you can win is if you get lucky with the prime factorization * of your constant. The number 1,000,000,000, which we have to multiply * by below, is a good example. One billion is 111011100110101100101000000000 * in binary. If you apply the bit-grouping trick, it doesn't buy you very * much, because it's only a win for groups of three or more equal bits: * * 111011100110101100101000000000 = 1000000000000000000000000000000 * - 000100011001010011011000000000 * * Thus, instead of the 13 shift/add pairs (26 operations) implied by the LHS, * we have reduced this to 10 shift/add pairs (20 operations) on the RHS. * This is better, but not great. * * However, we can factor 1,000,000,000 = 2^9 * 5^9 = 2^9 * 125 * 125 * 125, * and multiply by each factor. Multiplication by 125 is particularly easy, * since 128 is nearby: x * 125 = (x << 7) - x - x - x, which is just four * operations. So, to multiply by 1,000,000,000, we perform three multipli- * cations by 125, then << 9, a total of only 3 * 4 + 1 = 13 operations. * This is the algorithm we actually use in both hrt2ts() and ts2hrt(). * * Division is harder; there is no equivalent of the simple shift-add algorithm * we used for multiplication. However, we can convert the division problem * into a multiplication problem by pre-computing the binary representation * of the reciprocal of the divisor. For the case of interest, we have * * 1 / 1,000,000,000 = 1.0001001011100000101111101000001B-30, * * to 32 bits of precision. (The notation B-30 means "* 2^-30", just like * E-18 means "* 10^-18".) * * So, to compute x / 1,000,000,000, we just multiply x by the 32-bit * integer 10001001011100000101111101000001, then normalize (shift) the * result. This constant has several large bits runs, so the multiply * is relatively cheap: * * 10001001011100000101111101000001 = 10001001100000000110000001000001 * - 00000000000100000000000100000000 * * Again, you can just read the algorithm right off the bits: * * sec = hrt; * sec += (hrt << 6); * sec -= (hrt << 8); * sec += (hrt << 13); * sec += (hrt << 14); * sec -= (hrt << 20); * sec += (hrt << 23); * sec += (hrt << 24); * sec += (hrt << 27); * sec += (hrt << 31); * sec >>= (32 + 30); * * Voila! The only problem is, since hrt is 64 bits, we need to use 96-bit * arithmetic to perform this calculation. That's a waste, because ultimately * we only need the highest 32 bits of the result. * * The first thing we do is to realize that we don't need to use all of hrt * in the calculation. The lowest 30 bits can contribute at most 1 to the * quotient (2^30 / 1,000,000,000 = 1.07...), so we'll deal with them later. * The highest 2 bits have to be zero, or hrt won't fit in a timestruc_t. * Thus, the only bits of hrt that matter for division are bits 30..61. * These 32 bits are just the lower-order word of (hrt >> 30). This brings * us down from 96-bit math to 64-bit math, and our algorithm becomes: * * tmp = (uint32_t) (hrt >> 30); * sec = tmp; * sec += (tmp << 6); * sec -= (tmp << 8); * sec += (tmp << 13); * sec += (tmp << 14); * sec -= (tmp << 20); * sec += (tmp << 23); * sec += (tmp << 24); * sec += (tmp << 27); * sec += (tmp << 31); * sec >>= 32; * * Next, we're going to reduce this 64-bit computation to a 32-bit * computation. We begin by rewriting the above algorithm to use relative * shifts instead of absolute shifts. That is, instead of computing * tmp << 6, tmp << 8, tmp << 13, etc, we'll just shift incrementally: * tmp <<= 6, tmp <<= 2 (== 8 - 6), tmp <<= 5 (== 13 - 8), etc: * * tmp = (uint32_t) (hrt >> 30); * sec = tmp; * tmp <<= 6; sec += tmp; * tmp <<= 2; sec -= tmp; * tmp <<= 5; sec += tmp; * tmp <<= 1; sec += tmp; * tmp <<= 6; sec -= tmp; * tmp <<= 3; sec += tmp; * tmp <<= 1; sec += tmp; * tmp <<= 3; sec += tmp; * tmp <<= 4; sec += tmp; * sec >>= 32; * * Now for the final step. Instead of throwing away the low 32 bits at * the end, we can throw them away as we go, only keeping the high 32 bits * of the product at each step. So, for example, where we now have * * tmp <<= 6; sec = sec + tmp; * we will instead have * tmp <<= 6; sec = (sec + tmp) >> 6; * which is equivalent to * sec = (sec >> 6) + tmp; * * The final shift ("sec >>= 32") goes away. * * All we're really doing here is long multiplication, just like we learned in * grade school, except that at each step, we only look at the leftmost 32 * columns. The cumulative error is, at most, the sum of all the bits we * throw away, which is 2^-32 + 2^-31 + ... + 2^-2 + 2^-1 == 1 - 2^-32. * Thus, the final result ("sec") is correct to +/- 1. * * It turns out to be important to keep "sec" positive at each step, because * we don't want to have to explicitly extend the sign bit. Therefore, * starting with the last line of code above, each line that would have read * "sec = (sec >> n) - tmp" must be changed to "sec = tmp - (sec >> n)", and * the operators (+ or -) in all previous lines must be toggled accordingly. * Thus, we end up with: * * tmp = (uint32_t) (hrt >> 30); * sec = tmp + (sec >> 6); * sec = tmp - (tmp >> 2); * sec = tmp - (sec >> 5); * sec = tmp + (sec >> 1); * sec = tmp - (sec >> 6); * sec = tmp - (sec >> 3); * sec = tmp + (sec >> 1); * sec = tmp + (sec >> 3); * sec = tmp + (sec >> 4); * * This yields a value for sec that is accurate to +1/-1, so we have two * cases to deal with. The mysterious-looking "+ 7" in the code below biases * the rounding toward zero, so that sec is always less than or equal to * the correct value. With this modified code, sec is accurate to +0/-2, with * the -2 case being very rare in practice. With this change, we only have to * deal with one case (sec too small) in the cleanup code. * * The other modification we make is to delete the second line above * ("sec = tmp + (sec >> 6);"), since it only has an effect when bit 31 is * set, and the cleanup code can handle that rare case. This reduces the * *guaranteed* accuracy of sec to +0/-3, but speeds up the common cases. * * Finally, we compute nsec = hrt - (sec * 1,000,000,000). nsec will always * be positive (since sec is never too large), and will at most be equal to * the error in sec (times 1,000,000,000) plus the low-order 30 bits of hrt. * Thus, nsec < 3 * 1,000,000,000 + 2^30, which is less than 2^32, so we can * safely assume that nsec fits in 32 bits. Consequently, when we compute * sec * 1,000,000,000, we only need the low 32 bits, so we can just do 32-bit * arithmetic and let the high-order bits fall off the end. * * Since nsec < 3 * 1,000,000,000 + 2^30 == 4,073,741,824, the cleanup loop: * * while (nsec >= NANOSEC) { * nsec -= NANOSEC; * sec++; * } * * is guaranteed to complete in at most 4 iterations. In practice, the loop * completes in 0 or 1 iteration over 95% of the time. * * On an SS2, this implementation of hrt2ts() takes 1.7 usec, versus about * 35 usec for software division -- about 20 times faster. */ void hrt2ts(hrtime_t hrt, timestruc_t *tsp) { uint32_t sec, nsec, tmp; tmp = (uint32_t)(hrt >> 30); sec = tmp - (tmp >> 2); sec = tmp - (sec >> 5); sec = tmp + (sec >> 1); sec = tmp - (sec >> 6) + 7; sec = tmp - (sec >> 3); sec = tmp + (sec >> 1); sec = tmp + (sec >> 3); sec = tmp + (sec >> 4); tmp = (sec << 7) - sec - sec - sec; tmp = (tmp << 7) - tmp - tmp - tmp; tmp = (tmp << 7) - tmp - tmp - tmp; nsec = (uint32_t)hrt - (tmp << 9); while (nsec >= NANOSEC) { nsec -= NANOSEC; sec++; } tsp->tv_sec = (time_t)sec; tsp->tv_nsec = nsec; } /* * Convert from timestruc_t to hrtime_t. * * The code below is equivalent to: * * hrt = tsp->tv_sec * NANOSEC + tsp->tv_nsec; * * but requires no integer multiply. */ hrtime_t ts2hrt(const timestruc_t *tsp) { hrtime_t hrt; hrt = tsp->tv_sec; hrt = (hrt << 7) - hrt - hrt - hrt; hrt = (hrt << 7) - hrt - hrt - hrt; hrt = (hrt << 7) - hrt - hrt - hrt; hrt = (hrt << 9) + tsp->tv_nsec; return (hrt); } /* * For the various 32-bit "compatibility" paths in the system. */ void hrt2ts32(hrtime_t hrt, timestruc32_t *ts32p) { timestruc_t ts; hrt2ts(hrt, &ts); TIMESPEC_TO_TIMESPEC32(ts32p, &ts); } /* * If this ever becomes performance critical (ha!), we can borrow the * code from ts2hrt(), above, to multiply tv_sec by 1,000,000 and the * straightforward (x << 10) - (x << 5) + (x << 3) to multiply tv_usec by * 1,000. For now, we'll opt for readability (besides, the compiler does * a passable job of optimizing constant multiplication into shifts and adds). */ hrtime_t tv2hrt(struct timeval *tvp) { return ((hrtime_t)tvp->tv_sec * NANOSEC + (hrtime_t)tvp->tv_usec * (NANOSEC / MICROSEC)); } void hrt2tv(hrtime_t ts, struct timeval *tvp) { tvp->tv_sec = ts / NANOSEC; tvp->tv_usec = (ts % NANOSEC) / (NANOSEC / MICROSEC); } int nanosleep(timespec_t *rqtp, timespec_t *rmtp) { timespec_t rqtime; timespec_t rmtime; timespec_t now; int timecheck; int ret = 1; model_t datamodel = get_udatamodel(); if (datamodel == DATAMODEL_NATIVE) { if (copyin(rqtp, &rqtime, sizeof (rqtime))) return (set_errno(EFAULT)); } else { timespec32_t rqtime32; if (copyin(rqtp, &rqtime32, sizeof (rqtime32))) return (set_errno(EFAULT)); TIMESPEC32_TO_TIMESPEC(&rqtime, &rqtime32); } if (rqtime.tv_sec < 0 || rqtime.tv_nsec < 0 || rqtime.tv_nsec >= NANOSEC) return (set_errno(EINVAL)); if (timerspecisset(&rqtime)) { timecheck = timechanged; gethrestime(&now); timespecadd(&rqtime, &now); mutex_enter(&curthread->t_delay_lock); while ((ret = cv_waituntil_sig(&curthread->t_delay_cv, &curthread->t_delay_lock, &rqtime, timecheck)) > 0) continue; mutex_exit(&curthread->t_delay_lock); } if (rmtp) { /* * If cv_waituntil_sig() returned due to a signal, and * there is time remaining, then set the time remaining. * Else set time remaining to zero */ rmtime.tv_sec = rmtime.tv_nsec = 0; if (ret == 0) { gethrestime(&now); if ((now.tv_sec < rqtime.tv_sec) || ((now.tv_sec == rqtime.tv_sec) && (now.tv_nsec < rqtime.tv_nsec))) { rmtime = rqtime; timespecsub(&rmtime, &now); } } if (datamodel == DATAMODEL_NATIVE) { if (copyout(&rmtime, rmtp, sizeof (rmtime))) return (set_errno(EFAULT)); } else { timespec32_t rmtime32; TIMESPEC_TO_TIMESPEC32(&rmtime32, &rmtime); if (copyout(&rmtime32, rmtp, sizeof (rmtime32))) return (set_errno(EFAULT)); } } if (ret == 0) return (set_errno(EINTR)); return (0); } /* * Routines to convert standard UNIX time (seconds since Jan 1, 1970) * into year/month/day/hour/minute/second format, and back again. * Note: these routines require tod_lock held to protect cached state. */ static int days_thru_month[64] = { 0, 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366, 0, 0, 0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365, 0, 0, 0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365, 0, 0, 0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365, 0, 0, }; todinfo_t saved_tod; int saved_utc = -60; todinfo_t utc_to_tod(time_t utc) { long dse, day, month, year; todinfo_t tod; ASSERT(MUTEX_HELD(&tod_lock)); if (utc < 0) /* should never happen */ utc = 0; saved_tod.tod_sec += utc - saved_utc; saved_utc = utc; if (saved_tod.tod_sec >= 0 && saved_tod.tod_sec < 60) return (saved_tod); /* only the seconds changed */ dse = utc / 86400; /* days since epoch */ tod.tod_sec = utc % 60; tod.tod_min = (utc % 3600) / 60; tod.tod_hour = (utc % 86400) / 3600; tod.tod_dow = (dse + 4) % 7 + 1; /* epoch was a Thursday */ year = dse / 365 + 72; /* first guess -- always a bit too large */ do { year--; day = dse - 365 * (year - 70) - ((year - 69) >> 2); } while (day < 0); month = ((year & 3) << 4) + 1; while (day >= days_thru_month[month + 1]) month++; tod.tod_day = day - days_thru_month[month] + 1; tod.tod_month = month & 15; tod.tod_year = year; saved_tod = tod; return (tod); } time_t tod_to_utc(todinfo_t tod) { time_t utc; int year = tod.tod_year; int month = tod.tod_month + ((year & 3) << 4); #ifdef DEBUG /* only warn once, not each time called */ static int year_warn = 1; static int month_warn = 1; static int day_warn = 1; static int hour_warn = 1; static int min_warn = 1; static int sec_warn = 1; int days_diff = days_thru_month[month + 1] - days_thru_month[month]; #endif ASSERT(MUTEX_HELD(&tod_lock)); #ifdef DEBUG if (year_warn && (year < 70 || year > 8029)) { cmn_err(CE_WARN, "The hardware real-time clock appears to have the " "wrong years value %d -- time needs to be reset\n", year); year_warn = 0; } if (month_warn && (tod.tod_month < 1 || tod.tod_month > 12)) { cmn_err(CE_WARN, "The hardware real-time clock appears to have the " "wrong months value %d -- time needs to be reset\n", tod.tod_month); month_warn = 0; } if (day_warn && (tod.tod_day < 1 || tod.tod_day > days_diff)) { cmn_err(CE_WARN, "The hardware real-time clock appears to have the " "wrong days value %d -- time needs to be reset\n", tod.tod_day); day_warn = 0; } if (hour_warn && (tod.tod_hour < 0 || tod.tod_hour > 23)) { cmn_err(CE_WARN, "The hardware real-time clock appears to have the " "wrong hours value %d -- time needs to be reset\n", tod.tod_hour); hour_warn = 0; } if (min_warn && (tod.tod_min < 0 || tod.tod_min > 59)) { cmn_err(CE_WARN, "The hardware real-time clock appears to have the " "wrong minutes value %d -- time needs to be reset\n", tod.tod_min); min_warn = 0; } if (sec_warn && (tod.tod_sec < 0 || tod.tod_sec > 59)) { cmn_err(CE_WARN, "The hardware real-time clock appears to have the " "wrong seconds value %d -- time needs to be reset\n", tod.tod_sec); sec_warn = 0; } #endif utc = (year - 70); /* next 3 lines: utc = 365y + y/4 */ utc += (utc << 3) + (utc << 6); utc += (utc << 2) + ((year - 69) >> 2); utc += days_thru_month[month] + tod.tod_day - 1; utc = (utc << 3) + (utc << 4) + tod.tod_hour; /* 24 * day + hour */ utc = (utc << 6) - (utc << 2) + tod.tod_min; /* 60 * hour + min */ utc = (utc << 6) - (utc << 2) + tod.tod_sec; /* 60 * min + sec */ return (utc); }