1 /* $OpenBSD: kern_exit.c,v 1.169 2018/08/25 15:38:07 anton 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 /* close open files and release open-file table */ 190 fdfree(p); 191 192 timeout_del(&pr->ps_realit_to); 193 #ifdef SYSVSEM 194 semexit(pr); 195 #endif 196 killjobc(pr); 197 #ifdef ACCOUNTING 198 acct_process(p); 199 #endif 200 201 #ifdef KTRACE 202 /* release trace file */ 203 if (pr->ps_tracevp) 204 ktrcleartrace(pr); 205 #endif 206 207 /* 208 * If parent has the SAS_NOCLDWAIT flag set, we're not 209 * going to become a zombie. 210 */ 211 if (pr->ps_pptr->ps_sigacts->ps_flags & SAS_NOCLDWAIT) 212 atomic_setbits_int(&pr->ps_flags, PS_NOZOMBIE); 213 } 214 215 p->p_fd = NULL; /* zap the thread's copy */ 216 217 /* 218 * Remove proc from pidhash chain and allproc so looking 219 * it up won't work. We will put the proc on the 220 * deadproc list later (using the p_hash member), and 221 * wake up the reaper when we do. If this is the last 222 * thread of a process that isn't PS_NOZOMBIE, we'll put 223 * the process on the zombprocess list below. 224 */ 225 /* 226 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 227 */ 228 p->p_stat = SDEAD; 229 230 LIST_REMOVE(p, p_hash); 231 LIST_REMOVE(p, p_list); 232 233 if ((p->p_flag & P_THREAD) == 0) { 234 LIST_REMOVE(pr, ps_hash); 235 LIST_REMOVE(pr, ps_list); 236 237 if ((pr->ps_flags & PS_NOZOMBIE) == 0) 238 LIST_INSERT_HEAD(&zombprocess, pr, ps_list); 239 else { 240 /* 241 * Not going to be a zombie, so it's now off all 242 * the lists scanned by ispidtaken(), so block 243 * fast reuse of the pid now. 244 */ 245 freepid(pr->ps_pid); 246 } 247 248 /* 249 * Give orphaned children to init(8). 250 */ 251 qr = LIST_FIRST(&pr->ps_children); 252 if (qr) /* only need this if any child is S_ZOMB */ 253 wakeup(initprocess); 254 for (; qr != 0; qr = nqr) { 255 nqr = LIST_NEXT(qr, ps_sibling); 256 proc_reparent(qr, initprocess); 257 /* 258 * Traced processes are killed since their 259 * existence means someone is screwing up. 260 */ 261 if (qr->ps_flags & PS_TRACED && 262 !(qr->ps_flags & PS_EXITING)) { 263 atomic_clearbits_int(&qr->ps_flags, PS_TRACED); 264 /* 265 * If single threading is active, 266 * direct the signal to the active 267 * thread to avoid deadlock. 268 */ 269 if (qr->ps_single) 270 ptsignal(qr->ps_single, SIGKILL, 271 STHREAD); 272 else 273 prsignal(qr, SIGKILL); 274 } 275 } 276 } 277 278 /* add thread's accumulated rusage into the process's total */ 279 ruadd(rup, &p->p_ru); 280 tuagg(pr, p); 281 282 /* 283 * clear %cpu usage during swap 284 */ 285 p->p_pctcpu = 0; 286 287 if ((p->p_flag & P_THREAD) == 0) { 288 /* 289 * Final thread has died, so add on our children's rusage 290 * and calculate the total times 291 */ 292 calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL); 293 ruadd(rup, &pr->ps_cru); 294 295 /* notify interested parties of our demise and clean up */ 296 knote_processexit(p); 297 298 /* 299 * Notify parent that we're gone. If we're not going to 300 * become a zombie, reparent to process 1 (init) so that 301 * we can wake our original parent to possibly unblock 302 * wait4() to return ECHILD. 303 */ 304 if (pr->ps_flags & PS_NOZOMBIE) { 305 struct process *ppr = pr->ps_pptr; 306 proc_reparent(pr, initprocess); 307 wakeup(ppr); 308 } 309 310 /* 311 * Release the process's signal state. 312 */ 313 sigactsfree(pr); 314 } 315 316 /* just a thread? detach it from its process */ 317 if (p->p_flag & P_THREAD) { 318 /* scheduler_wait_hook(pr->ps_mainproc, p); XXX */ 319 if (--pr->ps_refcnt == 1) 320 wakeup(&pr->ps_threads); 321 KASSERT(pr->ps_refcnt > 0); 322 } 323 324 /* 325 * Other substructures are freed from reaper and wait(). 326 */ 327 328 /* 329 * Finally, call machine-dependent code to switch to a new 330 * context (possibly the idle context). Once we are no longer 331 * using the dead process's vmspace and stack, exit2() will be 332 * called to schedule those resources to be released by the 333 * reaper thread. 334 * 335 * Note that cpu_exit() will end with a call equivalent to 336 * cpu_switch(), finishing our execution (pun intended). 337 */ 338 uvmexp.swtch++; 339 cpu_exit(p); 340 panic("cpu_exit returned"); 341 } 342 343 /* 344 * Locking of this proclist is special; it's accessed in a 345 * critical section of process exit, and thus locking it can't 346 * modify interrupt state. We use a simple spin lock for this 347 * proclist. We use the p_hash member to linkup to deadproc. 348 */ 349 struct mutex deadproc_mutex = 350 MUTEX_INITIALIZER_FLAGS(IPL_NONE, NULL, MTX_NOWITNESS); 351 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 352 353 /* 354 * We are called from cpu_exit() once it is safe to schedule the 355 * dead process's resources to be freed. 356 * 357 * NOTE: One must be careful with locking in this routine. It's 358 * called from a critical section in machine-dependent code, so 359 * we should refrain from changing any interrupt state. 360 * 361 * We lock the deadproc list, place the proc on that list (using 362 * the p_hash member), and wake up the reaper. 363 */ 364 void 365 exit2(struct proc *p) 366 { 367 mtx_enter(&deadproc_mutex); 368 LIST_INSERT_HEAD(&deadproc, p, p_hash); 369 mtx_leave(&deadproc_mutex); 370 371 wakeup(&deadproc); 372 } 373 374 void 375 proc_free(struct proc *p) 376 { 377 crfree(p->p_ucred); 378 pool_put(&proc_pool, p); 379 nthreads--; 380 } 381 382 /* 383 * Process reaper. This is run by a kernel thread to free the resources 384 * of a dead process. Once the resources are free, the process becomes 385 * a zombie, and the parent is allowed to read the undead's status. 386 */ 387 void 388 reaper(void *arg) 389 { 390 struct proc *p; 391 392 KERNEL_UNLOCK(); 393 394 SCHED_ASSERT_UNLOCKED(); 395 396 for (;;) { 397 mtx_enter(&deadproc_mutex); 398 while ((p = LIST_FIRST(&deadproc)) == NULL) 399 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 400 401 /* Remove us from the deadproc list. */ 402 LIST_REMOVE(p, p_hash); 403 mtx_leave(&deadproc_mutex); 404 405 WITNESS_THREAD_EXIT(p); 406 407 KERNEL_LOCK(); 408 409 /* 410 * Free the VM resources we're still holding on to. 411 * We must do this from a valid thread because doing 412 * so may block. 413 */ 414 uvm_uarea_free(p); 415 p->p_vmspace = NULL; /* zap the thread's copy */ 416 417 if (p->p_flag & P_THREAD) { 418 /* Just a thread */ 419 proc_free(p); 420 } else { 421 struct process *pr = p->p_p; 422 423 /* Release the rest of the process's vmspace */ 424 uvm_exit(pr); 425 426 if ((pr->ps_flags & PS_NOZOMBIE) == 0) { 427 /* Process is now a true zombie. */ 428 atomic_setbits_int(&pr->ps_flags, PS_ZOMBIE); 429 prsignal(pr->ps_pptr, SIGCHLD); 430 431 /* Wake up the parent so it can get exit status. */ 432 wakeup(pr->ps_pptr); 433 } else { 434 /* No one will wait for us. Just zap the process now */ 435 process_zap(pr); 436 } 437 } 438 439 KERNEL_UNLOCK(); 440 } 441 } 442 443 int 444 sys_wait4(struct proc *q, void *v, register_t *retval) 445 { 446 struct sys_wait4_args /* { 447 syscallarg(pid_t) pid; 448 syscallarg(int *) status; 449 syscallarg(int) options; 450 syscallarg(struct rusage *) rusage; 451 } */ *uap = v; 452 struct rusage ru; 453 int status, error; 454 455 error = dowait4(q, SCARG(uap, pid), 456 SCARG(uap, status) ? &status : NULL, 457 SCARG(uap, options), SCARG(uap, rusage) ? &ru : NULL, retval); 458 if (error == 0 && retval[0] > 0 && SCARG(uap, status)) { 459 error = copyout(&status, SCARG(uap, status), sizeof(status)); 460 } 461 if (error == 0 && retval[0] > 0 && SCARG(uap, rusage)) { 462 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 463 #ifdef KTRACE 464 if (error == 0 && KTRPOINT(q, KTR_STRUCT)) 465 ktrrusage(q, &ru); 466 #endif 467 } 468 return (error); 469 } 470 471 int 472 dowait4(struct proc *q, pid_t pid, int *statusp, int options, 473 struct rusage *rusage, register_t *retval) 474 { 475 int nfound; 476 struct process *pr; 477 struct proc *p; 478 int error; 479 480 if (pid == 0) 481 pid = -q->p_p->ps_pgid; 482 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED)) 483 return (EINVAL); 484 485 loop: 486 nfound = 0; 487 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 488 if ((pr->ps_flags & PS_NOZOMBIE) || 489 (pid != WAIT_ANY && 490 pr->ps_pid != pid && 491 pr->ps_pgid != -pid)) 492 continue; 493 494 p = pr->ps_mainproc; 495 496 nfound++; 497 if (pr->ps_flags & PS_ZOMBIE) { 498 retval[0] = pr->ps_pid; 499 500 if (statusp != NULL) 501 *statusp = p->p_xstat; /* convert to int */ 502 if (rusage != NULL) 503 memcpy(rusage, pr->ps_ru, sizeof(*rusage)); 504 proc_finish_wait(q, p); 505 return (0); 506 } 507 if (pr->ps_flags & PS_TRACED && 508 (pr->ps_flags & PS_WAITED) == 0 && pr->ps_single && 509 pr->ps_single->p_stat == SSTOP && 510 (pr->ps_single->p_flag & P_SUSPSINGLE) == 0) { 511 single_thread_wait(pr); 512 513 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 514 retval[0] = pr->ps_pid; 515 516 if (statusp != NULL) 517 *statusp = W_STOPCODE(pr->ps_single->p_xstat); 518 if (rusage != NULL) 519 memset(rusage, 0, sizeof(*rusage)); 520 return (0); 521 } 522 if (p->p_stat == SSTOP && 523 (pr->ps_flags & PS_WAITED) == 0 && 524 (p->p_flag & P_SUSPSINGLE) == 0 && 525 (pr->ps_flags & PS_TRACED || 526 options & WUNTRACED)) { 527 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 528 retval[0] = pr->ps_pid; 529 530 if (statusp != NULL) 531 *statusp = W_STOPCODE(p->p_xstat); 532 if (rusage != NULL) 533 memset(rusage, 0, sizeof(*rusage)); 534 return (0); 535 } 536 if ((options & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 537 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 538 retval[0] = pr->ps_pid; 539 540 if (statusp != NULL) 541 *statusp = _WCONTINUED; 542 if (rusage != NULL) 543 memset(rusage, 0, sizeof(*rusage)); 544 return (0); 545 } 546 } 547 if (nfound == 0) 548 return (ECHILD); 549 if (options & WNOHANG) { 550 retval[0] = 0; 551 return (0); 552 } 553 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 554 return (error); 555 goto loop; 556 } 557 558 void 559 proc_finish_wait(struct proc *waiter, struct proc *p) 560 { 561 struct process *pr, *tr; 562 struct rusage *rup; 563 564 /* 565 * If we got the child via a ptrace 'attach', 566 * we need to give it back to the old parent. 567 */ 568 pr = p->p_p; 569 if (pr->ps_oppid && (tr = prfind(pr->ps_oppid))) { 570 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 571 pr->ps_oppid = 0; 572 proc_reparent(pr, tr); 573 prsignal(tr, SIGCHLD); 574 wakeup(tr); 575 } else { 576 scheduler_wait_hook(waiter, p); 577 p->p_xstat = 0; 578 rup = &waiter->p_p->ps_cru; 579 ruadd(rup, pr->ps_ru); 580 LIST_REMOVE(pr, ps_list); /* off zombprocess */ 581 freepid(pr->ps_pid); 582 process_zap(pr); 583 } 584 } 585 586 /* 587 * make process 'parent' the new parent of process 'child'. 588 */ 589 void 590 proc_reparent(struct process *child, struct process *parent) 591 { 592 593 if (child->ps_pptr == parent) 594 return; 595 596 LIST_REMOVE(child, ps_sibling); 597 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 598 child->ps_pptr = parent; 599 } 600 601 void 602 process_zap(struct process *pr) 603 { 604 struct vnode *otvp; 605 struct proc *p = pr->ps_mainproc; 606 607 /* 608 * Finally finished with old proc entry. 609 * Unlink it from its process group and free it. 610 */ 611 leavepgrp(pr); 612 LIST_REMOVE(pr, ps_sibling); 613 614 /* 615 * Decrement the count of procs running with this uid. 616 */ 617 (void)chgproccnt(pr->ps_ucred->cr_ruid, -1); 618 619 unveil_destroy(pr); 620 621 /* 622 * Release reference to text vnode 623 */ 624 otvp = pr->ps_textvp; 625 pr->ps_textvp = NULL; 626 if (otvp) 627 vrele(otvp); 628 629 KASSERT(pr->ps_refcnt == 1); 630 if (pr->ps_ptstat != NULL) 631 free(pr->ps_ptstat, M_SUBPROC, sizeof(*pr->ps_ptstat)); 632 pool_put(&rusage_pool, pr->ps_ru); 633 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 634 limfree(pr->ps_limit); 635 crfree(pr->ps_ucred); 636 pool_put(&process_pool, pr); 637 nprocesses--; 638 639 proc_free(p); 640 } 641