1 /* 2 * Copyright (c) 1982, 1986, 1989 Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * @(#)kern_time.c 7.15 (Berkeley) 03/17/91 8 */ 9 10 #include "param.h" 11 #include "resourcevar.h" 12 #include "kernel.h" 13 #include "proc.h" 14 15 #include "machine/cpu.h" 16 17 /* 18 * Time of day and interval timer support. 19 * 20 * These routines provide the kernel entry points to get and set 21 * the time-of-day and per-process interval timers. Subroutines 22 * here provide support for adding and subtracting timeval structures 23 * and decrementing interval timers, optionally reloading the interval 24 * timers when they expire. 25 */ 26 27 /* ARGSUSED */ 28 gettimeofday(p, uap, retval) 29 struct proc *p; 30 register struct args { 31 struct timeval *tp; 32 struct timezone *tzp; 33 } *uap; 34 int *retval; 35 { 36 struct timeval atv; 37 int error = 0; 38 39 if (uap->tp) { 40 microtime(&atv); 41 if (error = copyout((caddr_t)&atv, (caddr_t)uap->tp, 42 sizeof (atv))) 43 return (error); 44 } 45 if (uap->tzp) 46 error = copyout((caddr_t)&tz, (caddr_t)uap->tzp, 47 sizeof (tz)); 48 return (error); 49 } 50 51 /* ARGSUSED */ 52 settimeofday(p, uap, retval) 53 struct proc *p; 54 struct args { 55 struct timeval *tv; 56 struct timezone *tzp; 57 } *uap; 58 int *retval; 59 { 60 struct timeval atv; 61 struct timezone atz; 62 int error, s; 63 64 if (error = suser(p->p_ucred, &p->p_acflag)) 65 return (error); 66 if (uap->tv) { 67 if (error = copyin((caddr_t)uap->tv, (caddr_t)&atv, 68 sizeof (struct timeval))) 69 return (error); 70 /* WHAT DO WE DO ABOUT PENDING REAL-TIME TIMEOUTS??? */ 71 boottime.tv_sec += atv.tv_sec - time.tv_sec; 72 s = splhigh(); time = atv; splx(s); 73 resettodr(); 74 } 75 if (uap->tzp && (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz, 76 sizeof (atz))) == 0) 77 tz = atz; 78 return (error); 79 } 80 81 extern int tickadj; /* "standard" clock skew, us./tick */ 82 int tickdelta; /* current clock skew, us. per tick */ 83 long timedelta; /* unapplied time correction, us. */ 84 long bigadj = 1000000; /* use 10x skew above bigadj us. */ 85 86 /* ARGSUSED */ 87 adjtime(p, uap, retval) 88 struct proc *p; 89 register struct args { 90 struct timeval *delta; 91 struct timeval *olddelta; 92 } *uap; 93 int *retval; 94 { 95 struct timeval atv, oatv; 96 register long ndelta; 97 int s, error; 98 99 if (error = suser(p->p_ucred, &p->p_acflag)) 100 return (error); 101 if (error = 102 copyin((caddr_t)uap->delta, (caddr_t)&atv, sizeof (struct timeval))) 103 return (error); 104 ndelta = atv.tv_sec * 1000000 + atv.tv_usec; 105 if (timedelta == 0) 106 if (ndelta > bigadj) 107 tickdelta = 10 * tickadj; 108 else 109 tickdelta = tickadj; 110 if (ndelta % tickdelta) 111 ndelta = ndelta / tickadj * tickadj; 112 113 s = splclock(); 114 if (uap->olddelta) { 115 oatv.tv_sec = timedelta / 1000000; 116 oatv.tv_usec = timedelta % 1000000; 117 } 118 timedelta = ndelta; 119 splx(s); 120 121 if (uap->olddelta) 122 (void) copyout((caddr_t)&oatv, (caddr_t)uap->olddelta, 123 sizeof (struct timeval)); 124 return (0); 125 } 126 127 /* 128 * Get value of an interval timer. The process virtual and 129 * profiling virtual time timers are kept in the p_stats area, since 130 * they can be swapped out. These are kept internally in the 131 * way they are specified externally: in time until they expire. 132 * 133 * The real time interval timer is kept in the process table slot 134 * for the process, and its value (it_value) is kept as an 135 * absolute time rather than as a delta, so that it is easy to keep 136 * periodic real-time signals from drifting. 137 * 138 * Virtual time timers are processed in the hardclock() routine of 139 * kern_clock.c. The real time timer is processed by a timeout 140 * routine, called from the softclock() routine. Since a callout 141 * may be delayed in real time due to interrupt processing in the system, 142 * it is possible for the real time timeout routine (realitexpire, given below), 143 * to be delayed in real time past when it is supposed to occur. It 144 * does not suffice, therefore, to reload the real timer .it_value from the 145 * real time timers .it_interval. Rather, we compute the next time in 146 * absolute time the timer should go off. 147 */ 148 /* ARGSUSED */ 149 getitimer(p, uap, retval) 150 struct proc *p; 151 register struct args { 152 u_int which; 153 struct itimerval *itv; 154 } *uap; 155 int *retval; 156 { 157 struct itimerval aitv; 158 int s; 159 160 if (uap->which > ITIMER_PROF) 161 return (EINVAL); 162 s = splclock(); 163 if (uap->which == ITIMER_REAL) { 164 /* 165 * Convert from absoulte to relative time in .it_value 166 * part of real time timer. If time for real time timer 167 * has passed return 0, else return difference between 168 * current time and time for the timer to go off. 169 */ 170 aitv = p->p_realtimer; 171 if (timerisset(&aitv.it_value)) 172 if (timercmp(&aitv.it_value, &time, <)) 173 timerclear(&aitv.it_value); 174 else 175 timevalsub(&aitv.it_value, &time); 176 } else 177 aitv = p->p_stats->p_timer[uap->which]; 178 splx(s); 179 return (copyout((caddr_t)&aitv, (caddr_t)uap->itv, 180 sizeof (struct itimerval))); 181 } 182 183 /* ARGSUSED */ 184 setitimer(p, uap, retval) 185 struct proc *p; 186 register struct args { 187 u_int which; 188 struct itimerval *itv, *oitv; 189 } *uap; 190 int *retval; 191 { 192 struct itimerval aitv; 193 register struct itimerval *itvp; 194 int s, error; 195 196 if (uap->which > ITIMER_PROF) 197 return (EINVAL); 198 itvp = uap->itv; 199 if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv, 200 sizeof(struct itimerval)))) 201 return (error); 202 if ((uap->itv = uap->oitv) && (error = getitimer(p, uap, retval))) 203 return (error); 204 if (itvp == 0) 205 return (0); 206 if (itimerfix(&aitv.it_value) || itimerfix(&aitv.it_interval)) 207 return (EINVAL); 208 s = splclock(); 209 if (uap->which == ITIMER_REAL) { 210 untimeout(realitexpire, (caddr_t)p); 211 if (timerisset(&aitv.it_value)) { 212 timevaladd(&aitv.it_value, &time); 213 timeout(realitexpire, (caddr_t)p, hzto(&aitv.it_value)); 214 } 215 p->p_realtimer = aitv; 216 } else 217 p->p_stats->p_timer[uap->which] = aitv; 218 splx(s); 219 return (0); 220 } 221 222 /* 223 * Real interval timer expired: 224 * send process whose timer expired an alarm signal. 225 * If time is not set up to reload, then just return. 226 * Else compute next time timer should go off which is > current time. 227 * This is where delay in processing this timeout causes multiple 228 * SIGALRM calls to be compressed into one. 229 */ 230 realitexpire(p) 231 register struct proc *p; 232 { 233 int s; 234 235 psignal(p, SIGALRM); 236 if (!timerisset(&p->p_realtimer.it_interval)) { 237 timerclear(&p->p_realtimer.it_value); 238 return; 239 } 240 for (;;) { 241 s = splclock(); 242 timevaladd(&p->p_realtimer.it_value, 243 &p->p_realtimer.it_interval); 244 if (timercmp(&p->p_realtimer.it_value, &time, >)) { 245 timeout(realitexpire, (caddr_t)p, 246 hzto(&p->p_realtimer.it_value)); 247 splx(s); 248 return; 249 } 250 splx(s); 251 } 252 } 253 254 /* 255 * Check that a proposed value to load into the .it_value or 256 * .it_interval part of an interval timer is acceptable, and 257 * fix it to have at least minimal value (i.e. if it is less 258 * than the resolution of the clock, round it up.) 259 */ 260 itimerfix(tv) 261 struct timeval *tv; 262 { 263 264 if (tv->tv_sec < 0 || tv->tv_sec > 100000000 || 265 tv->tv_usec < 0 || tv->tv_usec >= 1000000) 266 return (EINVAL); 267 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick) 268 tv->tv_usec = tick; 269 return (0); 270 } 271 272 /* 273 * Decrement an interval timer by a specified number 274 * of microseconds, which must be less than a second, 275 * i.e. < 1000000. If the timer expires, then reload 276 * it. In this case, carry over (usec - old value) to 277 * reducint the value reloaded into the timer so that 278 * the timer does not drift. This routine assumes 279 * that it is called in a context where the timers 280 * on which it is operating cannot change in value. 281 */ 282 itimerdecr(itp, usec) 283 register struct itimerval *itp; 284 int usec; 285 { 286 287 if (itp->it_value.tv_usec < usec) { 288 if (itp->it_value.tv_sec == 0) { 289 /* expired, and already in next interval */ 290 usec -= itp->it_value.tv_usec; 291 goto expire; 292 } 293 itp->it_value.tv_usec += 1000000; 294 itp->it_value.tv_sec--; 295 } 296 itp->it_value.tv_usec -= usec; 297 usec = 0; 298 if (timerisset(&itp->it_value)) 299 return (1); 300 /* expired, exactly at end of interval */ 301 expire: 302 if (timerisset(&itp->it_interval)) { 303 itp->it_value = itp->it_interval; 304 itp->it_value.tv_usec -= usec; 305 if (itp->it_value.tv_usec < 0) { 306 itp->it_value.tv_usec += 1000000; 307 itp->it_value.tv_sec--; 308 } 309 } else 310 itp->it_value.tv_usec = 0; /* sec is already 0 */ 311 return (0); 312 } 313 314 /* 315 * Add and subtract routines for timevals. 316 * N.B.: subtract routine doesn't deal with 317 * results which are before the beginning, 318 * it just gets very confused in this case. 319 * Caveat emptor. 320 */ 321 timevaladd(t1, t2) 322 struct timeval *t1, *t2; 323 { 324 325 t1->tv_sec += t2->tv_sec; 326 t1->tv_usec += t2->tv_usec; 327 timevalfix(t1); 328 } 329 330 timevalsub(t1, t2) 331 struct timeval *t1, *t2; 332 { 333 334 t1->tv_sec -= t2->tv_sec; 335 t1->tv_usec -= t2->tv_usec; 336 timevalfix(t1); 337 } 338 339 timevalfix(t1) 340 struct timeval *t1; 341 { 342 343 if (t1->tv_usec < 0) { 344 t1->tv_sec--; 345 t1->tv_usec += 1000000; 346 } 347 if (t1->tv_usec >= 1000000) { 348 t1->tv_sec++; 349 t1->tv_usec -= 1000000; 350 } 351 } 352