1 /* $OpenBSD: kern_exit.c,v 1.171 2018/11/12 15:09:17 visa Exp $ */ 2 /* $NetBSD: kern_exit.c,v 1.39 1996/04/22 01:38:25 christos Exp $ */ 3 4 /* 5 * Copyright (c) 1982, 1986, 1989, 1991, 1993 6 * The Regents of the University of California. All rights reserved. 7 * (c) UNIX System Laboratories, Inc. 8 * All or some portions of this file are derived from material licensed 9 * to the University of California by American Telephone and Telegraph 10 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 11 * the permission of UNIX System Laboratories, Inc. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * @(#)kern_exit.c 8.7 (Berkeley) 2/12/94 38 */ 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/ioctl.h> 43 #include <sys/proc.h> 44 #include <sys/tty.h> 45 #include <sys/time.h> 46 #include <sys/resource.h> 47 #include <sys/kernel.h> 48 #include <sys/sysctl.h> 49 #include <sys/wait.h> 50 #include <sys/vnode.h> 51 #include <sys/syslog.h> 52 #include <sys/malloc.h> 53 #include <sys/resourcevar.h> 54 #include <sys/ptrace.h> 55 #include <sys/acct.h> 56 #include <sys/filedesc.h> 57 #include <sys/signalvar.h> 58 #include <sys/sched.h> 59 #include <sys/ktrace.h> 60 #include <sys/pool.h> 61 #include <sys/mutex.h> 62 #include <sys/pledge.h> 63 #ifdef SYSVSEM 64 #include <sys/sem.h> 65 #endif 66 #include <sys/witness.h> 67 68 #include <sys/mount.h> 69 #include <sys/syscallargs.h> 70 71 #include <uvm/uvm_extern.h> 72 73 #include "kcov.h" 74 #if NKCOV > 0 75 #include <sys/kcov.h> 76 #endif 77 78 void proc_finish_wait(struct proc *, struct proc *); 79 void process_zap(struct process *); 80 void proc_free(struct proc *); 81 void unveil_destroy(struct process *ps); 82 83 /* 84 * exit -- 85 * Death of process. 86 */ 87 int 88 sys_exit(struct proc *p, void *v, register_t *retval) 89 { 90 struct sys_exit_args /* { 91 syscallarg(int) rval; 92 } */ *uap = v; 93 94 exit1(p, W_EXITCODE(SCARG(uap, rval), 0), EXIT_NORMAL); 95 /* NOTREACHED */ 96 return (0); 97 } 98 99 int 100 sys___threxit(struct proc *p, void *v, register_t *retval) 101 { 102 struct sys___threxit_args /* { 103 syscallarg(pid_t *) notdead; 104 } */ *uap = v; 105 106 if (SCARG(uap, notdead) != NULL) { 107 pid_t zero = 0; 108 if (copyout(&zero, SCARG(uap, notdead), sizeof(zero))) 109 psignal(p, SIGSEGV); 110 } 111 exit1(p, 0, EXIT_THREAD); 112 113 return (0); 114 } 115 116 /* 117 * Exit: deallocate address space and other resources, change proc state 118 * to zombie, and unlink proc from allproc and parent's lists. Save exit 119 * status and rusage for wait(). Check for child processes and orphan them. 120 */ 121 void 122 exit1(struct proc *p, int rv, int flags) 123 { 124 struct process *pr, *qr, *nqr; 125 struct rusage *rup; 126 127 atomic_setbits_int(&p->p_flag, P_WEXIT); 128 129 pr = p->p_p; 130 131 /* single-threaded? */ 132 if (!P_HASSIBLING(p)) { 133 flags = EXIT_NORMAL; 134 } else { 135 /* nope, multi-threaded */ 136 if (flags == EXIT_NORMAL) 137 single_thread_set(p, SINGLE_EXIT, 0); 138 else if (flags == EXIT_THREAD) 139 single_thread_check(p, 0); 140 } 141 142 if (flags == EXIT_NORMAL) { 143 if (pr->ps_pid == 1) 144 panic("init died (signal %d, exit %d)", 145 WTERMSIG(rv), WEXITSTATUS(rv)); 146 147 atomic_setbits_int(&pr->ps_flags, PS_EXITING); 148 pr->ps_mainproc->p_xstat = rv; 149 150 /* 151 * If parent is waiting for us to exit or exec, PS_PPWAIT 152 * is set; we wake up the parent early to avoid deadlock. 153 */ 154 if (pr->ps_flags & PS_PPWAIT) { 155 atomic_clearbits_int(&pr->ps_flags, PS_PPWAIT); 156 atomic_clearbits_int(&pr->ps_pptr->ps_flags, 157 PS_ISPWAIT); 158 wakeup(pr->ps_pptr); 159 } 160 } 161 162 /* unlink ourselves from the active threads */ 163 TAILQ_REMOVE(&pr->ps_threads, p, p_thr_link); 164 if ((p->p_flag & P_THREAD) == 0) { 165 /* main thread gotta wait because it has the pid, et al */ 166 while (pr->ps_refcnt > 1) 167 tsleep(&pr->ps_threads, PUSER, "thrdeath", 0); 168 if (pr->ps_flags & PS_PROFIL) 169 stopprofclock(pr); 170 } 171 172 rup = pr->ps_ru; 173 if (rup == NULL) { 174 rup = pool_get(&rusage_pool, PR_WAITOK | PR_ZERO); 175 if (pr->ps_ru == NULL) { 176 pr->ps_ru = rup; 177 } else { 178 pool_put(&rusage_pool, rup); 179 rup = pr->ps_ru; 180 } 181 } 182 p->p_siglist = 0; 183 184 #if NKCOV > 0 185 kcov_exit(p); 186 #endif 187 188 if ((p->p_flag & P_THREAD) == 0) { 189 sigio_freelist(&pr->ps_sigiolst); 190 191 /* close open files and release open-file table */ 192 fdfree(p); 193 194 timeout_del(&pr->ps_realit_to); 195 #ifdef SYSVSEM 196 semexit(pr); 197 #endif 198 killjobc(pr); 199 #ifdef ACCOUNTING 200 acct_process(p); 201 #endif 202 203 #ifdef KTRACE 204 /* release trace file */ 205 if (pr->ps_tracevp) 206 ktrcleartrace(pr); 207 #endif 208 209 unveil_destroy(pr); 210 211 /* 212 * If parent has the SAS_NOCLDWAIT flag set, we're not 213 * going to become a zombie. 214 */ 215 if (pr->ps_pptr->ps_sigacts->ps_flags & SAS_NOCLDWAIT) 216 atomic_setbits_int(&pr->ps_flags, PS_NOZOMBIE); 217 } 218 219 p->p_fd = NULL; /* zap the thread's copy */ 220 221 /* 222 * Remove proc from pidhash chain and allproc so looking 223 * it up won't work. We will put the proc on the 224 * deadproc list later (using the p_hash member), and 225 * wake up the reaper when we do. If this is the last 226 * thread of a process that isn't PS_NOZOMBIE, we'll put 227 * the process on the zombprocess list below. 228 */ 229 /* 230 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 231 */ 232 p->p_stat = SDEAD; 233 234 LIST_REMOVE(p, p_hash); 235 LIST_REMOVE(p, p_list); 236 237 if ((p->p_flag & P_THREAD) == 0) { 238 LIST_REMOVE(pr, ps_hash); 239 LIST_REMOVE(pr, ps_list); 240 241 if ((pr->ps_flags & PS_NOZOMBIE) == 0) 242 LIST_INSERT_HEAD(&zombprocess, pr, ps_list); 243 else { 244 /* 245 * Not going to be a zombie, so it's now off all 246 * the lists scanned by ispidtaken(), so block 247 * fast reuse of the pid now. 248 */ 249 freepid(pr->ps_pid); 250 } 251 252 /* 253 * Give orphaned children to init(8). 254 */ 255 qr = LIST_FIRST(&pr->ps_children); 256 if (qr) /* only need this if any child is S_ZOMB */ 257 wakeup(initprocess); 258 for (; qr != 0; qr = nqr) { 259 nqr = LIST_NEXT(qr, ps_sibling); 260 proc_reparent(qr, initprocess); 261 /* 262 * Traced processes are killed since their 263 * existence means someone is screwing up. 264 */ 265 if (qr->ps_flags & PS_TRACED && 266 !(qr->ps_flags & PS_EXITING)) { 267 atomic_clearbits_int(&qr->ps_flags, PS_TRACED); 268 /* 269 * If single threading is active, 270 * direct the signal to the active 271 * thread to avoid deadlock. 272 */ 273 if (qr->ps_single) 274 ptsignal(qr->ps_single, SIGKILL, 275 STHREAD); 276 else 277 prsignal(qr, SIGKILL); 278 } 279 } 280 } 281 282 /* add thread's accumulated rusage into the process's total */ 283 ruadd(rup, &p->p_ru); 284 tuagg(pr, p); 285 286 /* 287 * clear %cpu usage during swap 288 */ 289 p->p_pctcpu = 0; 290 291 if ((p->p_flag & P_THREAD) == 0) { 292 /* 293 * Final thread has died, so add on our children's rusage 294 * and calculate the total times 295 */ 296 calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL); 297 ruadd(rup, &pr->ps_cru); 298 299 /* notify interested parties of our demise and clean up */ 300 knote_processexit(p); 301 302 /* 303 * Notify parent that we're gone. If we're not going to 304 * become a zombie, reparent to process 1 (init) so that 305 * we can wake our original parent to possibly unblock 306 * wait4() to return ECHILD. 307 */ 308 if (pr->ps_flags & PS_NOZOMBIE) { 309 struct process *ppr = pr->ps_pptr; 310 proc_reparent(pr, initprocess); 311 wakeup(ppr); 312 } 313 314 /* 315 * Release the process's signal state. 316 */ 317 sigactsfree(pr); 318 } 319 320 /* just a thread? detach it from its process */ 321 if (p->p_flag & P_THREAD) { 322 /* scheduler_wait_hook(pr->ps_mainproc, p); XXX */ 323 if (--pr->ps_refcnt == 1) 324 wakeup(&pr->ps_threads); 325 KASSERT(pr->ps_refcnt > 0); 326 } 327 328 /* 329 * Other substructures are freed from reaper and wait(). 330 */ 331 332 /* 333 * Finally, call machine-dependent code to switch to a new 334 * context (possibly the idle context). Once we are no longer 335 * using the dead process's vmspace and stack, exit2() will be 336 * called to schedule those resources to be released by the 337 * reaper thread. 338 * 339 * Note that cpu_exit() will end with a call equivalent to 340 * cpu_switch(), finishing our execution (pun intended). 341 */ 342 uvmexp.swtch++; 343 cpu_exit(p); 344 panic("cpu_exit returned"); 345 } 346 347 /* 348 * Locking of this proclist is special; it's accessed in a 349 * critical section of process exit, and thus locking it can't 350 * modify interrupt state. We use a simple spin lock for this 351 * proclist. We use the p_hash member to linkup to deadproc. 352 */ 353 struct mutex deadproc_mutex = 354 MUTEX_INITIALIZER_FLAGS(IPL_NONE, NULL, MTX_NOWITNESS); 355 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 356 357 /* 358 * We are called from cpu_exit() once it is safe to schedule the 359 * dead process's resources to be freed. 360 * 361 * NOTE: One must be careful with locking in this routine. It's 362 * called from a critical section in machine-dependent code, so 363 * we should refrain from changing any interrupt state. 364 * 365 * We lock the deadproc list, place the proc on that list (using 366 * the p_hash member), and wake up the reaper. 367 */ 368 void 369 exit2(struct proc *p) 370 { 371 mtx_enter(&deadproc_mutex); 372 LIST_INSERT_HEAD(&deadproc, p, p_hash); 373 mtx_leave(&deadproc_mutex); 374 375 wakeup(&deadproc); 376 } 377 378 void 379 proc_free(struct proc *p) 380 { 381 crfree(p->p_ucred); 382 pool_put(&proc_pool, p); 383 nthreads--; 384 } 385 386 /* 387 * Process reaper. This is run by a kernel thread to free the resources 388 * of a dead process. Once the resources are free, the process becomes 389 * a zombie, and the parent is allowed to read the undead's status. 390 */ 391 void 392 reaper(void *arg) 393 { 394 struct proc *p; 395 396 KERNEL_UNLOCK(); 397 398 SCHED_ASSERT_UNLOCKED(); 399 400 for (;;) { 401 mtx_enter(&deadproc_mutex); 402 while ((p = LIST_FIRST(&deadproc)) == NULL) 403 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 404 405 /* Remove us from the deadproc list. */ 406 LIST_REMOVE(p, p_hash); 407 mtx_leave(&deadproc_mutex); 408 409 WITNESS_THREAD_EXIT(p); 410 411 KERNEL_LOCK(); 412 413 /* 414 * Free the VM resources we're still holding on to. 415 * We must do this from a valid thread because doing 416 * so may block. 417 */ 418 uvm_uarea_free(p); 419 p->p_vmspace = NULL; /* zap the thread's copy */ 420 421 if (p->p_flag & P_THREAD) { 422 /* Just a thread */ 423 proc_free(p); 424 } else { 425 struct process *pr = p->p_p; 426 427 /* Release the rest of the process's vmspace */ 428 uvm_exit(pr); 429 430 if ((pr->ps_flags & PS_NOZOMBIE) == 0) { 431 /* Process is now a true zombie. */ 432 atomic_setbits_int(&pr->ps_flags, PS_ZOMBIE); 433 prsignal(pr->ps_pptr, SIGCHLD); 434 435 /* Wake up the parent so it can get exit status. */ 436 wakeup(pr->ps_pptr); 437 } else { 438 /* No one will wait for us. Just zap the process now */ 439 process_zap(pr); 440 } 441 } 442 443 KERNEL_UNLOCK(); 444 } 445 } 446 447 int 448 sys_wait4(struct proc *q, void *v, register_t *retval) 449 { 450 struct sys_wait4_args /* { 451 syscallarg(pid_t) pid; 452 syscallarg(int *) status; 453 syscallarg(int) options; 454 syscallarg(struct rusage *) rusage; 455 } */ *uap = v; 456 struct rusage ru; 457 int status, error; 458 459 error = dowait4(q, SCARG(uap, pid), 460 SCARG(uap, status) ? &status : NULL, 461 SCARG(uap, options), SCARG(uap, rusage) ? &ru : NULL, retval); 462 if (error == 0 && retval[0] > 0 && SCARG(uap, status)) { 463 error = copyout(&status, SCARG(uap, status), sizeof(status)); 464 } 465 if (error == 0 && retval[0] > 0 && SCARG(uap, rusage)) { 466 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 467 #ifdef KTRACE 468 if (error == 0 && KTRPOINT(q, KTR_STRUCT)) 469 ktrrusage(q, &ru); 470 #endif 471 } 472 return (error); 473 } 474 475 int 476 dowait4(struct proc *q, pid_t pid, int *statusp, int options, 477 struct rusage *rusage, register_t *retval) 478 { 479 int nfound; 480 struct process *pr; 481 struct proc *p; 482 int error; 483 484 if (pid == 0) 485 pid = -q->p_p->ps_pgid; 486 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED)) 487 return (EINVAL); 488 489 loop: 490 nfound = 0; 491 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 492 if ((pr->ps_flags & PS_NOZOMBIE) || 493 (pid != WAIT_ANY && 494 pr->ps_pid != pid && 495 pr->ps_pgid != -pid)) 496 continue; 497 498 p = pr->ps_mainproc; 499 500 nfound++; 501 if (pr->ps_flags & PS_ZOMBIE) { 502 retval[0] = pr->ps_pid; 503 504 if (statusp != NULL) 505 *statusp = p->p_xstat; /* convert to int */ 506 if (rusage != NULL) 507 memcpy(rusage, pr->ps_ru, sizeof(*rusage)); 508 proc_finish_wait(q, p); 509 return (0); 510 } 511 if (pr->ps_flags & PS_TRACED && 512 (pr->ps_flags & PS_WAITED) == 0 && pr->ps_single && 513 pr->ps_single->p_stat == SSTOP && 514 (pr->ps_single->p_flag & P_SUSPSINGLE) == 0) { 515 single_thread_wait(pr); 516 517 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 518 retval[0] = pr->ps_pid; 519 520 if (statusp != NULL) 521 *statusp = W_STOPCODE(pr->ps_single->p_xstat); 522 if (rusage != NULL) 523 memset(rusage, 0, sizeof(*rusage)); 524 return (0); 525 } 526 if (p->p_stat == SSTOP && 527 (pr->ps_flags & PS_WAITED) == 0 && 528 (p->p_flag & P_SUSPSINGLE) == 0 && 529 (pr->ps_flags & PS_TRACED || 530 options & WUNTRACED)) { 531 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 532 retval[0] = pr->ps_pid; 533 534 if (statusp != NULL) 535 *statusp = W_STOPCODE(p->p_xstat); 536 if (rusage != NULL) 537 memset(rusage, 0, sizeof(*rusage)); 538 return (0); 539 } 540 if ((options & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 541 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 542 retval[0] = pr->ps_pid; 543 544 if (statusp != NULL) 545 *statusp = _WCONTINUED; 546 if (rusage != NULL) 547 memset(rusage, 0, sizeof(*rusage)); 548 return (0); 549 } 550 } 551 if (nfound == 0) 552 return (ECHILD); 553 if (options & WNOHANG) { 554 retval[0] = 0; 555 return (0); 556 } 557 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 558 return (error); 559 goto loop; 560 } 561 562 void 563 proc_finish_wait(struct proc *waiter, struct proc *p) 564 { 565 struct process *pr, *tr; 566 struct rusage *rup; 567 568 /* 569 * If we got the child via a ptrace 'attach', 570 * we need to give it back to the old parent. 571 */ 572 pr = p->p_p; 573 if (pr->ps_oppid && (tr = prfind(pr->ps_oppid))) { 574 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 575 pr->ps_oppid = 0; 576 proc_reparent(pr, tr); 577 prsignal(tr, SIGCHLD); 578 wakeup(tr); 579 } else { 580 scheduler_wait_hook(waiter, p); 581 p->p_xstat = 0; 582 rup = &waiter->p_p->ps_cru; 583 ruadd(rup, pr->ps_ru); 584 LIST_REMOVE(pr, ps_list); /* off zombprocess */ 585 freepid(pr->ps_pid); 586 process_zap(pr); 587 } 588 } 589 590 /* 591 * make process 'parent' the new parent of process 'child'. 592 */ 593 void 594 proc_reparent(struct process *child, struct process *parent) 595 { 596 597 if (child->ps_pptr == parent) 598 return; 599 600 LIST_REMOVE(child, ps_sibling); 601 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 602 child->ps_pptr = parent; 603 } 604 605 void 606 process_zap(struct process *pr) 607 { 608 struct vnode *otvp; 609 struct proc *p = pr->ps_mainproc; 610 611 /* 612 * Finally finished with old proc entry. 613 * Unlink it from its process group and free it. 614 */ 615 leavepgrp(pr); 616 LIST_REMOVE(pr, ps_sibling); 617 618 /* 619 * Decrement the count of procs running with this uid. 620 */ 621 (void)chgproccnt(pr->ps_ucred->cr_ruid, -1); 622 623 /* 624 * Release reference to text vnode 625 */ 626 otvp = pr->ps_textvp; 627 pr->ps_textvp = NULL; 628 if (otvp) 629 vrele(otvp); 630 631 KASSERT(pr->ps_refcnt == 1); 632 if (pr->ps_ptstat != NULL) 633 free(pr->ps_ptstat, M_SUBPROC, sizeof(*pr->ps_ptstat)); 634 pool_put(&rusage_pool, pr->ps_ru); 635 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 636 limfree(pr->ps_limit); 637 crfree(pr->ps_ucred); 638 pool_put(&process_pool, pr); 639 nprocesses--; 640 641 proc_free(p); 642 } 643