kern_fork.c revision 1.209
1 /* $NetBSD: kern_fork.c,v 1.209 2019/04/07 14:50:41 kamil Exp $ */ 2 3 /*- 4 * Copyright (c) 1999, 2001, 2004, 2006, 2007, 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, 9 * NASA Ames Research Center, by Charles M. Hannum, and by Andrew Doran. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 /* 34 * Copyright (c) 1982, 1986, 1989, 1991, 1993 35 * The Regents of the University of California. All rights reserved. 36 * (c) UNIX System Laboratories, Inc. 37 * All or some portions of this file are derived from material licensed 38 * to the University of California by American Telephone and Telegraph 39 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 40 * the permission of UNIX System Laboratories, Inc. 41 * 42 * Redistribution and use in source and binary forms, with or without 43 * modification, are permitted provided that the following conditions 44 * are met: 45 * 1. Redistributions of source code must retain the above copyright 46 * notice, this list of conditions and the following disclaimer. 47 * 2. Redistributions in binary form must reproduce the above copyright 48 * notice, this list of conditions and the following disclaimer in the 49 * documentation and/or other materials provided with the distribution. 50 * 3. Neither the name of the University nor the names of its contributors 51 * may be used to endorse or promote products derived from this software 52 * without specific prior written permission. 53 * 54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 64 * SUCH DAMAGE. 65 * 66 * @(#)kern_fork.c 8.8 (Berkeley) 2/14/95 67 */ 68 69 #include <sys/cdefs.h> 70 __KERNEL_RCSID(0, "$NetBSD: kern_fork.c,v 1.209 2019/04/07 14:50:41 kamil Exp $"); 71 72 #include "opt_ktrace.h" 73 #include "opt_dtrace.h" 74 75 #include <sys/param.h> 76 #include <sys/systm.h> 77 #include <sys/filedesc.h> 78 #include <sys/kernel.h> 79 #include <sys/pool.h> 80 #include <sys/mount.h> 81 #include <sys/proc.h> 82 #include <sys/ras.h> 83 #include <sys/resourcevar.h> 84 #include <sys/vnode.h> 85 #include <sys/file.h> 86 #include <sys/acct.h> 87 #include <sys/ktrace.h> 88 #include <sys/sched.h> 89 #include <sys/signalvar.h> 90 #include <sys/syscall.h> 91 #include <sys/kauth.h> 92 #include <sys/atomic.h> 93 #include <sys/syscallargs.h> 94 #include <sys/uidinfo.h> 95 #include <sys/sdt.h> 96 #include <sys/ptrace.h> 97 98 #include <uvm/uvm_extern.h> 99 100 /* 101 * DTrace SDT provider definitions 102 */ 103 SDT_PROVIDER_DECLARE(proc); 104 SDT_PROBE_DEFINE3(proc, kernel, , create, 105 "struct proc *", /* new process */ 106 "struct proc *", /* parent process */ 107 "int" /* flags */); 108 109 u_int nprocs __cacheline_aligned = 1; /* process 0 */ 110 111 /* 112 * Number of ticks to sleep if fork() would fail due to process hitting 113 * limits. Exported in miliseconds to userland via sysctl. 114 */ 115 int forkfsleep = 0; 116 117 int 118 sys_fork(struct lwp *l, const void *v, register_t *retval) 119 { 120 121 return fork1(l, 0, SIGCHLD, NULL, 0, NULL, NULL, retval); 122 } 123 124 /* 125 * vfork(2) system call compatible with 4.4BSD (i.e. BSD with Mach VM). 126 * Address space is not shared, but parent is blocked until child exit. 127 */ 128 int 129 sys_vfork(struct lwp *l, const void *v, register_t *retval) 130 { 131 132 return fork1(l, FORK_PPWAIT, SIGCHLD, NULL, 0, NULL, NULL, 133 retval); 134 } 135 136 /* 137 * New vfork(2) system call for NetBSD, which implements original 3BSD vfork(2) 138 * semantics. Address space is shared, and parent is blocked until child exit. 139 */ 140 int 141 sys___vfork14(struct lwp *l, const void *v, register_t *retval) 142 { 143 144 return fork1(l, FORK_PPWAIT|FORK_SHAREVM, SIGCHLD, NULL, 0, 145 NULL, NULL, retval); 146 } 147 148 /* 149 * Linux-compatible __clone(2) system call. 150 */ 151 int 152 sys___clone(struct lwp *l, const struct sys___clone_args *uap, 153 register_t *retval) 154 { 155 /* { 156 syscallarg(int) flags; 157 syscallarg(void *) stack; 158 } */ 159 int flags, sig; 160 161 /* 162 * We don't support the CLONE_PID or CLONE_PTRACE flags. 163 */ 164 if (SCARG(uap, flags) & (CLONE_PID|CLONE_PTRACE)) 165 return EINVAL; 166 167 /* 168 * Linux enforces CLONE_VM with CLONE_SIGHAND, do same. 169 */ 170 if (SCARG(uap, flags) & CLONE_SIGHAND 171 && (SCARG(uap, flags) & CLONE_VM) == 0) 172 return EINVAL; 173 174 flags = 0; 175 176 if (SCARG(uap, flags) & CLONE_VM) 177 flags |= FORK_SHAREVM; 178 if (SCARG(uap, flags) & CLONE_FS) 179 flags |= FORK_SHARECWD; 180 if (SCARG(uap, flags) & CLONE_FILES) 181 flags |= FORK_SHAREFILES; 182 if (SCARG(uap, flags) & CLONE_SIGHAND) 183 flags |= FORK_SHARESIGS; 184 if (SCARG(uap, flags) & CLONE_VFORK) 185 flags |= FORK_PPWAIT; 186 187 sig = SCARG(uap, flags) & CLONE_CSIGNAL; 188 if (sig < 0 || sig >= _NSIG) 189 return EINVAL; 190 191 /* 192 * Note that the Linux API does not provide a portable way of 193 * specifying the stack area; the caller must know if the stack 194 * grows up or down. So, we pass a stack size of 0, so that the 195 * code that makes this adjustment is a noop. 196 */ 197 return fork1(l, flags, sig, SCARG(uap, stack), 0, 198 NULL, NULL, retval); 199 } 200 201 /* 202 * Print the 'table full' message once per 10 seconds. 203 */ 204 static struct timeval fork_tfmrate = { 10, 0 }; 205 206 /* 207 * General fork call. Note that another LWP in the process may call exec() 208 * or exit() while we are forking. It's safe to continue here, because 209 * neither operation will complete until all LWPs have exited the process. 210 */ 211 int 212 fork1(struct lwp *l1, int flags, int exitsig, void *stack, size_t stacksize, 213 void (*func)(void *), void *arg, register_t *retval) 214 { 215 struct proc *p1, *p2, *parent; 216 struct plimit *p1_lim; 217 uid_t uid; 218 struct lwp *l2; 219 int count; 220 vaddr_t uaddr; 221 int tnprocs; 222 int tracefork, tracevfork, tracevforkdone; 223 int error = 0; 224 225 p1 = l1->l_proc; 226 uid = kauth_cred_getuid(l1->l_cred); 227 tnprocs = atomic_inc_uint_nv(&nprocs); 228 229 /* 230 * Although process entries are dynamically created, we still keep 231 * a global limit on the maximum number we will create. 232 */ 233 if (__predict_false(tnprocs >= maxproc)) 234 error = -1; 235 else 236 error = kauth_authorize_process(l1->l_cred, 237 KAUTH_PROCESS_FORK, p1, KAUTH_ARG(tnprocs), NULL, NULL); 238 239 if (error) { 240 static struct timeval lasttfm; 241 atomic_dec_uint(&nprocs); 242 if (ratecheck(&lasttfm, &fork_tfmrate)) 243 tablefull("proc", "increase kern.maxproc or NPROC"); 244 if (forkfsleep) 245 kpause("forkmx", false, forkfsleep, NULL); 246 return EAGAIN; 247 } 248 249 /* 250 * Enforce limits. 251 */ 252 count = chgproccnt(uid, 1); 253 if (__predict_false(count > p1->p_rlimit[RLIMIT_NPROC].rlim_cur)) { 254 if (kauth_authorize_process(l1->l_cred, KAUTH_PROCESS_RLIMIT, 255 p1, KAUTH_ARG(KAUTH_REQ_PROCESS_RLIMIT_BYPASS), 256 &p1->p_rlimit[RLIMIT_NPROC], KAUTH_ARG(RLIMIT_NPROC)) != 0) { 257 (void)chgproccnt(uid, -1); 258 atomic_dec_uint(&nprocs); 259 if (forkfsleep) 260 kpause("forkulim", false, forkfsleep, NULL); 261 return EAGAIN; 262 } 263 } 264 265 /* 266 * Allocate virtual address space for the U-area now, while it 267 * is still easy to abort the fork operation if we're out of 268 * kernel virtual address space. 269 */ 270 uaddr = uvm_uarea_alloc(); 271 if (__predict_false(uaddr == 0)) { 272 (void)chgproccnt(uid, -1); 273 atomic_dec_uint(&nprocs); 274 return ENOMEM; 275 } 276 277 /* 278 * We are now committed to the fork. From here on, we may 279 * block on resources, but resource allocation may NOT fail. 280 */ 281 282 /* Allocate new proc. */ 283 p2 = proc_alloc(); 284 285 /* 286 * Make a proc table entry for the new process. 287 * Start by zeroing the section of proc that is zero-initialized, 288 * then copy the section that is copied directly from the parent. 289 */ 290 memset(&p2->p_startzero, 0, 291 (unsigned) ((char *)&p2->p_endzero - (char *)&p2->p_startzero)); 292 memcpy(&p2->p_startcopy, &p1->p_startcopy, 293 (unsigned) ((char *)&p2->p_endcopy - (char *)&p2->p_startcopy)); 294 295 TAILQ_INIT(&p2->p_sigpend.sp_info); 296 297 LIST_INIT(&p2->p_lwps); 298 LIST_INIT(&p2->p_sigwaiters); 299 300 /* 301 * Duplicate sub-structures as needed. 302 * Increase reference counts on shared objects. 303 * Inherit flags we want to keep. The flags related to SIGCHLD 304 * handling are important in order to keep a consistent behaviour 305 * for the child after the fork. If we are a 32-bit process, the 306 * child will be too. 307 */ 308 p2->p_flag = 309 p1->p_flag & (PK_SUGID | PK_NOCLDWAIT | PK_CLDSIGIGN | PK_32); 310 p2->p_emul = p1->p_emul; 311 p2->p_execsw = p1->p_execsw; 312 313 if (flags & FORK_SYSTEM) { 314 /* 315 * Mark it as a system process. Set P_NOCLDWAIT so that 316 * children are reparented to init(8) when they exit. 317 * init(8) can easily wait them out for us. 318 */ 319 p2->p_flag |= (PK_SYSTEM | PK_NOCLDWAIT); 320 } 321 322 mutex_init(&p2->p_stmutex, MUTEX_DEFAULT, IPL_HIGH); 323 mutex_init(&p2->p_auxlock, MUTEX_DEFAULT, IPL_NONE); 324 rw_init(&p2->p_reflock); 325 cv_init(&p2->p_waitcv, "wait"); 326 cv_init(&p2->p_lwpcv, "lwpwait"); 327 328 /* 329 * Share a lock between the processes if they are to share signal 330 * state: we must synchronize access to it. 331 */ 332 if (flags & FORK_SHARESIGS) { 333 p2->p_lock = p1->p_lock; 334 mutex_obj_hold(p1->p_lock); 335 } else 336 p2->p_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE); 337 338 kauth_proc_fork(p1, p2); 339 340 p2->p_raslist = NULL; 341 #if defined(__HAVE_RAS) 342 ras_fork(p1, p2); 343 #endif 344 345 /* bump references to the text vnode (for procfs) */ 346 p2->p_textvp = p1->p_textvp; 347 if (p2->p_textvp) 348 vref(p2->p_textvp); 349 if (p1->p_path) 350 p2->p_path = kmem_strdupsize(p1->p_path, NULL, KM_SLEEP); 351 else 352 p2->p_path = NULL; 353 354 if (flags & FORK_SHAREFILES) 355 fd_share(p2); 356 else if (flags & FORK_CLEANFILES) 357 p2->p_fd = fd_init(NULL); 358 else 359 p2->p_fd = fd_copy(); 360 361 /* XXX racy */ 362 p2->p_mqueue_cnt = p1->p_mqueue_cnt; 363 364 if (flags & FORK_SHARECWD) 365 cwdshare(p2); 366 else 367 p2->p_cwdi = cwdinit(); 368 369 /* 370 * Note: p_limit (rlimit stuff) is copy-on-write, so normally 371 * we just need increase pl_refcnt. 372 */ 373 p1_lim = p1->p_limit; 374 if (!p1_lim->pl_writeable) { 375 lim_addref(p1_lim); 376 p2->p_limit = p1_lim; 377 } else { 378 p2->p_limit = lim_copy(p1_lim); 379 } 380 381 if (flags & FORK_PPWAIT) { 382 /* Mark ourselves as waiting for a child. */ 383 l1->l_pflag |= LP_VFORKWAIT; 384 p2->p_lflag = PL_PPWAIT; 385 p2->p_vforklwp = l1; 386 } else { 387 p2->p_lflag = 0; 388 } 389 p2->p_sflag = 0; 390 p2->p_slflag = 0; 391 parent = (flags & FORK_NOWAIT) ? initproc : p1; 392 p2->p_pptr = parent; 393 p2->p_ppid = parent->p_pid; 394 LIST_INIT(&p2->p_children); 395 396 p2->p_aio = NULL; 397 398 #ifdef KTRACE 399 /* 400 * Copy traceflag and tracefile if enabled. 401 * If not inherited, these were zeroed above. 402 */ 403 if (p1->p_traceflag & KTRFAC_INHERIT) { 404 mutex_enter(&ktrace_lock); 405 p2->p_traceflag = p1->p_traceflag; 406 if ((p2->p_tracep = p1->p_tracep) != NULL) 407 ktradref(p2); 408 mutex_exit(&ktrace_lock); 409 } 410 #endif 411 412 /* 413 * Create signal actions for the child process. 414 */ 415 p2->p_sigacts = sigactsinit(p1, flags & FORK_SHARESIGS); 416 mutex_enter(p1->p_lock); 417 p2->p_sflag |= 418 (p1->p_sflag & (PS_STOPFORK | PS_STOPEXEC | PS_NOCLDSTOP)); 419 sched_proc_fork(p1, p2); 420 mutex_exit(p1->p_lock); 421 422 p2->p_stflag = p1->p_stflag; 423 424 /* 425 * p_stats. 426 * Copy parts of p_stats, and zero out the rest. 427 */ 428 p2->p_stats = pstatscopy(p1->p_stats); 429 430 /* 431 * Set up the new process address space. 432 */ 433 uvm_proc_fork(p1, p2, (flags & FORK_SHAREVM) ? true : false); 434 435 /* 436 * Finish creating the child process. 437 * It will return through a different path later. 438 */ 439 lwp_create(l1, p2, uaddr, (flags & FORK_PPWAIT) ? LWP_VFORK : 0, 440 stack, stacksize, (func != NULL) ? func : child_return, arg, &l2, 441 l1->l_class, &l1->l_sigmask, &l1->l_sigstk); 442 443 /* 444 * Inherit l_private from the parent. 445 * Note that we cannot use lwp_setprivate() here since that 446 * also sets the CPU TLS register, which is incorrect if the 447 * process has changed that without letting the kernel know. 448 */ 449 l2->l_private = l1->l_private; 450 451 /* 452 * If emulation has a process fork hook, call it now. 453 */ 454 if (p2->p_emul->e_proc_fork) 455 (*p2->p_emul->e_proc_fork)(p2, l1, flags); 456 457 /* 458 * ...and finally, any other random fork hooks that subsystems 459 * might have registered. 460 */ 461 doforkhooks(p2, p1); 462 463 SDT_PROBE(proc, kernel, , create, p2, p1, flags, 0, 0); 464 465 /* 466 * It's now safe for the scheduler and other processes to see the 467 * child process. 468 */ 469 mutex_enter(proc_lock); 470 471 if (p1->p_session->s_ttyvp != NULL && p1->p_lflag & PL_CONTROLT) 472 p2->p_lflag |= PL_CONTROLT; 473 474 LIST_INSERT_HEAD(&parent->p_children, p2, p_sibling); 475 p2->p_exitsig = exitsig; /* signal for parent on exit */ 476 477 /* 478 * Trace fork(2) and vfork(2)-like events on demand in a debugger. 479 */ 480 tracefork = (p1->p_slflag & (PSL_TRACEFORK|PSL_TRACED)) == 481 (PSL_TRACEFORK|PSL_TRACED) && (flags & FORK_PPWAIT) == 0; 482 tracevfork = (p1->p_slflag & (PSL_TRACEVFORK|PSL_TRACED)) == 483 (PSL_TRACEVFORK|PSL_TRACED) && (flags & FORK_PPWAIT) != 0; 484 tracevforkdone = (p1->p_slflag & (PSL_TRACEVFORK_DONE|PSL_TRACED)) == 485 (PSL_TRACEVFORK_DONE|PSL_TRACED) && (flags & FORK_PPWAIT); 486 if (tracefork || tracevfork) 487 proc_changeparent(p2, p1->p_pptr); 488 if (tracefork) { 489 p1->p_fpid = p2->p_pid; 490 p2->p_fpid = p1->p_pid; 491 } 492 if (tracevfork) { 493 p1->p_vfpid = p2->p_pid; 494 p2->p_vfpid = p1->p_pid; 495 } 496 497 LIST_INSERT_AFTER(p1, p2, p_pglist); 498 LIST_INSERT_HEAD(&allproc, p2, p_list); 499 500 p2->p_trace_enabled = trace_is_enabled(p2); 501 #ifdef __HAVE_SYSCALL_INTERN 502 (*p2->p_emul->e_syscall_intern)(p2); 503 #endif 504 505 /* 506 * Update stats now that we know the fork was successful. 507 */ 508 uvmexp.forks++; 509 if (flags & FORK_PPWAIT) 510 uvmexp.forks_ppwait++; 511 if (flags & FORK_SHAREVM) 512 uvmexp.forks_sharevm++; 513 514 if (ktrpoint(KTR_EMUL)) 515 p2->p_traceflag |= KTRFAC_TRC_EMUL; 516 517 /* 518 * Notify any interested parties about the new process. 519 */ 520 if (!SLIST_EMPTY(&p1->p_klist)) { 521 mutex_exit(proc_lock); 522 KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid); 523 mutex_enter(proc_lock); 524 } 525 526 /* 527 * Make child runnable, set start time, and add to run queue except 528 * if the parent requested the child to start in SSTOP state. 529 */ 530 mutex_enter(p2->p_lock); 531 532 /* 533 * Start profiling. 534 */ 535 if ((p2->p_stflag & PST_PROFIL) != 0) { 536 mutex_spin_enter(&p2->p_stmutex); 537 startprofclock(p2); 538 mutex_spin_exit(&p2->p_stmutex); 539 } 540 541 getmicrotime(&p2->p_stats->p_start); 542 p2->p_acflag = AFORK; 543 lwp_lock(l2); 544 KASSERT(p2->p_nrlwps == 1); 545 if (p2->p_sflag & PS_STOPFORK) { 546 struct schedstate_percpu *spc = &l2->l_cpu->ci_schedstate; 547 p2->p_nrlwps = 0; 548 p2->p_stat = SSTOP; 549 p2->p_waited = 0; 550 p1->p_nstopchild++; 551 l2->l_stat = LSSTOP; 552 KASSERT(l2->l_wchan == NULL); 553 lwp_unlock_to(l2, spc->spc_lwplock); 554 } else { 555 p2->p_nrlwps = 1; 556 p2->p_stat = SACTIVE; 557 l2->l_stat = LSRUN; 558 sched_enqueue(l2, false); 559 lwp_unlock(l2); 560 } 561 562 /* 563 * Return child pid to parent process, 564 * marking us as parent via retval[1]. 565 */ 566 if (retval != NULL) { 567 retval[0] = p2->p_pid; 568 retval[1] = 0; 569 } 570 571 mutex_exit(p2->p_lock); 572 573 /* 574 * Let the parent know that we are tracing its child. 575 */ 576 if (tracefork || tracevfork) { 577 mutex_enter(p1->p_lock); 578 p1->p_xsig = SIGTRAP; 579 p1->p_sigctx.ps_faked = true; // XXX 580 p1->p_sigctx.ps_info._signo = p1->p_xsig; 581 p1->p_sigctx.ps_info._code = TRAP_CHLD; 582 sigswitch(0, SIGTRAP, false); 583 // XXX ktrpoint(KTR_PSIG) 584 mutex_exit(p1->p_lock); 585 mutex_enter(proc_lock); 586 } 587 588 /* 589 * Preserve synchronization semantics of vfork. If waiting for 590 * child to exec or exit, sleep until it clears LP_VFORKWAIT. 591 */ 592 while (p2->p_lflag & PL_PPWAIT) // XXX: p2 can go invalid 593 cv_wait(&p1->p_waitcv, proc_lock); 594 595 /* 596 * Let the parent know that we are tracing its child. 597 */ 598 if (tracevforkdone) { 599 mutex_enter(p1->p_lock); 600 p1->p_xsig = SIGTRAP; 601 p1->p_sigctx.ps_faked = true; // XXX 602 p1->p_sigctx.ps_info._signo = p1->p_xsig; 603 p1->p_sigctx.ps_info._code = TRAP_CHLD; 604 p1->p_vfpid_done = retval[0]; 605 sigswitch(0, SIGTRAP, false); 606 // XXX ktrpoint(KTR_PSIG) 607 mutex_exit(p1->p_lock); 608 // proc_lock unlocked 609 } else 610 mutex_exit(proc_lock); 611 612 return 0; 613 } 614 615 void 616 child_return(void *arg) 617 { 618 struct lwp *l = arg; 619 struct proc *p = l->l_proc; 620 621 if (p->p_slflag & PSL_TRACED) { 622 /* Paranoid check */ 623 mutex_enter(proc_lock); 624 if (!(p->p_slflag & PSL_TRACED)) { 625 mutex_exit(proc_lock); 626 goto my_tracer_is_gone; 627 } 628 629 mutex_enter(p->p_lock); 630 p->p_xsig = SIGTRAP; 631 p->p_sigctx.ps_faked = true; // XXX 632 p->p_sigctx.ps_info._signo = p->p_xsig; 633 p->p_sigctx.ps_info._code = TRAP_CHLD; 634 sigswitch(0, SIGTRAP, false); 635 // XXX ktrpoint(KTR_PSIG) 636 mutex_exit(p->p_lock); 637 } 638 639 my_tracer_is_gone: 640 md_child_return(l); 641 642 /* 643 * Return SYS_fork for all fork types, including vfork(2) and clone(2). 644 * 645 * This approach simplifies the code and avoids extra locking. 646 */ 647 ktrsysret(SYS_fork, 0, 0); 648 } 649
Indexes created Tue Sep 23 14:10:03 GMT 2025