1 /* $OpenBSD: kern_exit.c,v 1.177 2019/06/13 21:19:28 mpi 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, PWAIT, "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 if ((p->p_flag & P_THREAD) == 0) 184 pr->ps_siglist = 0; 185 186 #if NKCOV > 0 187 kcov_exit(p); 188 #endif 189 190 if ((p->p_flag & P_THREAD) == 0) { 191 sigio_freelist(&pr->ps_sigiolst); 192 193 /* close open files and release open-file table */ 194 fdfree(p); 195 196 timeout_del(&pr->ps_realit_to); 197 timeout_del(&pr->ps_rucheck_to); 198 #ifdef SYSVSEM 199 semexit(pr); 200 #endif 201 killjobc(pr); 202 #ifdef ACCOUNTING 203 acct_process(p); 204 #endif 205 206 #ifdef KTRACE 207 /* release trace file */ 208 if (pr->ps_tracevp) 209 ktrcleartrace(pr); 210 #endif 211 212 unveil_destroy(pr); 213 214 /* 215 * If parent has the SAS_NOCLDWAIT flag set, we're not 216 * going to become a zombie. 217 */ 218 if (pr->ps_pptr->ps_sigacts->ps_flags & SAS_NOCLDWAIT) 219 atomic_setbits_int(&pr->ps_flags, PS_NOZOMBIE); 220 } 221 222 p->p_fd = NULL; /* zap the thread's copy */ 223 224 /* 225 * Remove proc from pidhash chain and allproc so looking 226 * it up won't work. We will put the proc on the 227 * deadproc list later (using the p_hash member), and 228 * wake up the reaper when we do. If this is the last 229 * thread of a process that isn't PS_NOZOMBIE, we'll put 230 * the process on the zombprocess list below. 231 */ 232 /* 233 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 234 */ 235 p->p_stat = SDEAD; 236 237 LIST_REMOVE(p, p_hash); 238 LIST_REMOVE(p, p_list); 239 240 if ((p->p_flag & P_THREAD) == 0) { 241 LIST_REMOVE(pr, ps_hash); 242 LIST_REMOVE(pr, ps_list); 243 244 if ((pr->ps_flags & PS_NOZOMBIE) == 0) 245 LIST_INSERT_HEAD(&zombprocess, pr, ps_list); 246 else { 247 /* 248 * Not going to be a zombie, so it's now off all 249 * the lists scanned by ispidtaken(), so block 250 * fast reuse of the pid now. 251 */ 252 freepid(pr->ps_pid); 253 } 254 255 /* 256 * Give orphaned children to init(8). 257 */ 258 qr = LIST_FIRST(&pr->ps_children); 259 if (qr) /* only need this if any child is S_ZOMB */ 260 wakeup(initprocess); 261 for (; qr != 0; qr = nqr) { 262 nqr = LIST_NEXT(qr, ps_sibling); 263 proc_reparent(qr, initprocess); 264 /* 265 * Traced processes are killed since their 266 * existence means someone is screwing up. 267 */ 268 if (qr->ps_flags & PS_TRACED && 269 !(qr->ps_flags & PS_EXITING)) { 270 atomic_clearbits_int(&qr->ps_flags, PS_TRACED); 271 /* 272 * If single threading is active, 273 * direct the signal to the active 274 * thread to avoid deadlock. 275 */ 276 if (qr->ps_single) 277 ptsignal(qr->ps_single, SIGKILL, 278 STHREAD); 279 else 280 prsignal(qr, SIGKILL); 281 } 282 } 283 } 284 285 /* add thread's accumulated rusage into the process's total */ 286 ruadd(rup, &p->p_ru); 287 tuagg(pr, p); 288 289 /* 290 * clear %cpu usage during swap 291 */ 292 p->p_pctcpu = 0; 293 294 if ((p->p_flag & P_THREAD) == 0) { 295 /* 296 * Final thread has died, so add on our children's rusage 297 * and calculate the total times 298 */ 299 calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL); 300 ruadd(rup, &pr->ps_cru); 301 302 /* notify interested parties of our demise and clean up */ 303 knote_processexit(p); 304 305 /* 306 * Notify parent that we're gone. If we're not going to 307 * become a zombie, reparent to process 1 (init) so that 308 * we can wake our original parent to possibly unblock 309 * wait4() to return ECHILD. 310 */ 311 if (pr->ps_flags & PS_NOZOMBIE) { 312 struct process *ppr = pr->ps_pptr; 313 proc_reparent(pr, initprocess); 314 wakeup(ppr); 315 } 316 317 /* 318 * Release the process's signal state. 319 */ 320 sigactsfree(pr); 321 } 322 323 /* just a thread? detach it from its process */ 324 if (p->p_flag & P_THREAD) { 325 /* scheduler_wait_hook(pr->ps_mainproc, p); XXX */ 326 if (--pr->ps_refcnt == 1) 327 wakeup(&pr->ps_threads); 328 KASSERT(pr->ps_refcnt > 0); 329 } 330 331 /* 332 * Other substructures are freed from reaper and wait(). 333 */ 334 335 /* 336 * Finally, call machine-dependent code to switch to a new 337 * context (possibly the idle context). Once we are no longer 338 * using the dead process's vmspace and stack, exit2() will be 339 * called to schedule those resources to be released by the 340 * reaper thread. 341 * 342 * Note that cpu_exit() will end with a call equivalent to 343 * cpu_switch(), finishing our execution (pun intended). 344 */ 345 uvmexp.swtch++; 346 cpu_exit(p); 347 panic("cpu_exit returned"); 348 } 349 350 /* 351 * Locking of this proclist is special; it's accessed in a 352 * critical section of process exit, and thus locking it can't 353 * modify interrupt state. We use a simple spin lock for this 354 * proclist. We use the p_hash member to linkup to deadproc. 355 */ 356 struct mutex deadproc_mutex = 357 MUTEX_INITIALIZER_FLAGS(IPL_NONE, "deadproc", MTX_NOWITNESS); 358 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 359 360 /* 361 * We are called from cpu_exit() once it is safe to schedule the 362 * dead process's resources to be freed. 363 * 364 * NOTE: One must be careful with locking in this routine. It's 365 * called from a critical section in machine-dependent code, so 366 * we should refrain from changing any interrupt state. 367 * 368 * We lock the deadproc list, place the proc on that list (using 369 * the p_hash member), and wake up the reaper. 370 */ 371 void 372 exit2(struct proc *p) 373 { 374 mtx_enter(&deadproc_mutex); 375 LIST_INSERT_HEAD(&deadproc, p, p_hash); 376 mtx_leave(&deadproc_mutex); 377 378 wakeup(&deadproc); 379 } 380 381 void 382 proc_free(struct proc *p) 383 { 384 crfree(p->p_ucred); 385 pool_put(&proc_pool, p); 386 nthreads--; 387 } 388 389 /* 390 * Process reaper. This is run by a kernel thread to free the resources 391 * of a dead process. Once the resources are free, the process becomes 392 * a zombie, and the parent is allowed to read the undead's status. 393 */ 394 void 395 reaper(void *arg) 396 { 397 struct proc *p; 398 399 KERNEL_UNLOCK(); 400 401 SCHED_ASSERT_UNLOCKED(); 402 403 for (;;) { 404 mtx_enter(&deadproc_mutex); 405 while ((p = LIST_FIRST(&deadproc)) == NULL) 406 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 407 408 /* Remove us from the deadproc list. */ 409 LIST_REMOVE(p, p_hash); 410 mtx_leave(&deadproc_mutex); 411 412 WITNESS_THREAD_EXIT(p); 413 414 KERNEL_LOCK(); 415 416 /* 417 * Free the VM resources we're still holding on to. 418 * We must do this from a valid thread because doing 419 * so may block. 420 */ 421 uvm_uarea_free(p); 422 p->p_vmspace = NULL; /* zap the thread's copy */ 423 424 if (p->p_flag & P_THREAD) { 425 /* Just a thread */ 426 proc_free(p); 427 } else { 428 struct process *pr = p->p_p; 429 430 /* Release the rest of the process's vmspace */ 431 uvm_exit(pr); 432 433 if ((pr->ps_flags & PS_NOZOMBIE) == 0) { 434 /* Process is now a true zombie. */ 435 atomic_setbits_int(&pr->ps_flags, PS_ZOMBIE); 436 prsignal(pr->ps_pptr, SIGCHLD); 437 438 /* Wake up the parent so it can get exit status. */ 439 wakeup(pr->ps_pptr); 440 } else { 441 /* No one will wait for us. Just zap the process now */ 442 process_zap(pr); 443 } 444 } 445 446 KERNEL_UNLOCK(); 447 } 448 } 449 450 int 451 sys_wait4(struct proc *q, void *v, register_t *retval) 452 { 453 struct sys_wait4_args /* { 454 syscallarg(pid_t) pid; 455 syscallarg(int *) status; 456 syscallarg(int) options; 457 syscallarg(struct rusage *) rusage; 458 } */ *uap = v; 459 struct rusage ru; 460 int status, error; 461 462 error = dowait4(q, SCARG(uap, pid), 463 SCARG(uap, status) ? &status : NULL, 464 SCARG(uap, options), SCARG(uap, rusage) ? &ru : NULL, retval); 465 if (error == 0 && retval[0] > 0 && SCARG(uap, status)) { 466 error = copyout(&status, SCARG(uap, status), sizeof(status)); 467 } 468 if (error == 0 && retval[0] > 0 && SCARG(uap, rusage)) { 469 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 470 #ifdef KTRACE 471 if (error == 0 && KTRPOINT(q, KTR_STRUCT)) 472 ktrrusage(q, &ru); 473 #endif 474 } 475 return (error); 476 } 477 478 int 479 dowait4(struct proc *q, pid_t pid, int *statusp, int options, 480 struct rusage *rusage, register_t *retval) 481 { 482 int nfound; 483 struct process *pr; 484 struct proc *p; 485 int error; 486 487 if (pid == 0) 488 pid = -q->p_p->ps_pgid; 489 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED)) 490 return (EINVAL); 491 492 loop: 493 nfound = 0; 494 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 495 if ((pr->ps_flags & PS_NOZOMBIE) || 496 (pid != WAIT_ANY && 497 pr->ps_pid != pid && 498 pr->ps_pgid != -pid)) 499 continue; 500 501 p = pr->ps_mainproc; 502 503 nfound++; 504 if (pr->ps_flags & PS_ZOMBIE) { 505 retval[0] = pr->ps_pid; 506 507 if (statusp != NULL) 508 *statusp = p->p_xstat; /* convert to int */ 509 if (rusage != NULL) 510 memcpy(rusage, pr->ps_ru, sizeof(*rusage)); 511 proc_finish_wait(q, p); 512 return (0); 513 } 514 if (pr->ps_flags & PS_TRACED && 515 (pr->ps_flags & PS_WAITED) == 0 && pr->ps_single && 516 pr->ps_single->p_stat == SSTOP && 517 (pr->ps_single->p_flag & P_SUSPSINGLE) == 0) { 518 single_thread_wait(pr); 519 520 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 521 retval[0] = pr->ps_pid; 522 523 if (statusp != NULL) 524 *statusp = W_STOPCODE(pr->ps_single->p_xstat); 525 if (rusage != NULL) 526 memset(rusage, 0, sizeof(*rusage)); 527 return (0); 528 } 529 if (p->p_stat == SSTOP && 530 (pr->ps_flags & PS_WAITED) == 0 && 531 (p->p_flag & P_SUSPSINGLE) == 0 && 532 (pr->ps_flags & PS_TRACED || 533 options & WUNTRACED)) { 534 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 535 retval[0] = pr->ps_pid; 536 537 if (statusp != NULL) 538 *statusp = W_STOPCODE(p->p_xstat); 539 if (rusage != NULL) 540 memset(rusage, 0, sizeof(*rusage)); 541 return (0); 542 } 543 if ((options & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 544 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 545 retval[0] = pr->ps_pid; 546 547 if (statusp != NULL) 548 *statusp = _WCONTINUED; 549 if (rusage != NULL) 550 memset(rusage, 0, sizeof(*rusage)); 551 return (0); 552 } 553 } 554 if (nfound == 0) 555 return (ECHILD); 556 if (options & WNOHANG) { 557 retval[0] = 0; 558 return (0); 559 } 560 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 561 return (error); 562 goto loop; 563 } 564 565 void 566 proc_finish_wait(struct proc *waiter, struct proc *p) 567 { 568 struct process *pr, *tr; 569 struct rusage *rup; 570 571 /* 572 * If we got the child via a ptrace 'attach', 573 * we need to give it back to the old parent. 574 */ 575 pr = p->p_p; 576 if (pr->ps_oppid && (tr = prfind(pr->ps_oppid))) { 577 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 578 pr->ps_oppid = 0; 579 proc_reparent(pr, tr); 580 prsignal(tr, SIGCHLD); 581 wakeup(tr); 582 } else { 583 scheduler_wait_hook(waiter, p); 584 p->p_xstat = 0; 585 rup = &waiter->p_p->ps_cru; 586 ruadd(rup, pr->ps_ru); 587 LIST_REMOVE(pr, ps_list); /* off zombprocess */ 588 freepid(pr->ps_pid); 589 process_zap(pr); 590 } 591 } 592 593 /* 594 * make process 'parent' the new parent of process 'child'. 595 */ 596 void 597 proc_reparent(struct process *child, struct process *parent) 598 { 599 600 if (child->ps_pptr == parent) 601 return; 602 603 LIST_REMOVE(child, ps_sibling); 604 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 605 child->ps_pptr = parent; 606 } 607 608 void 609 process_zap(struct process *pr) 610 { 611 struct vnode *otvp; 612 struct proc *p = pr->ps_mainproc; 613 614 /* 615 * Finally finished with old proc entry. 616 * Unlink it from its process group and free it. 617 */ 618 leavepgrp(pr); 619 LIST_REMOVE(pr, ps_sibling); 620 621 /* 622 * Decrement the count of procs running with this uid. 623 */ 624 (void)chgproccnt(pr->ps_ucred->cr_ruid, -1); 625 626 /* 627 * Release reference to text vnode 628 */ 629 otvp = pr->ps_textvp; 630 pr->ps_textvp = NULL; 631 if (otvp) 632 vrele(otvp); 633 634 KASSERT(pr->ps_refcnt == 1); 635 if (pr->ps_ptstat != NULL) 636 free(pr->ps_ptstat, M_SUBPROC, sizeof(*pr->ps_ptstat)); 637 pool_put(&rusage_pool, pr->ps_ru); 638 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 639 limfree(pr->ps_limit); 640 crfree(pr->ps_ucred); 641 pool_put(&process_pool, pr); 642 nprocesses--; 643 644 proc_free(p); 645 } 646