1 /* 2 * Copyright (c) 1982, 1986, 1989, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)kern_fork.c 8.6 (Berkeley) 4/8/94 35 * $FreeBSD: src/sys/kern/kern_fork.c,v 1.72.2.14 2003/06/26 04:15:10 silby Exp $ 36 */ 37 38 #include "opt_ktrace.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/sysmsg.h> 43 #include <sys/filedesc.h> 44 #include <sys/kernel.h> 45 #include <sys/sysctl.h> 46 #include <sys/malloc.h> 47 #include <sys/proc.h> 48 #include <sys/resourcevar.h> 49 #include <sys/vnode.h> 50 #include <sys/acct.h> 51 #include <sys/ktrace.h> 52 #include <sys/unistd.h> 53 #include <sys/jail.h> 54 #include <sys/lwp.h> 55 56 #include <vm/vm.h> 57 #include <sys/lock.h> 58 #include <vm/pmap.h> 59 #include <vm/vm_map.h> 60 #include <vm/vm_extern.h> 61 62 #include <sys/vmmeter.h> 63 #include <sys/refcount.h> 64 #include <sys/thread2.h> 65 #include <sys/signal2.h> 66 #include <sys/spinlock2.h> 67 68 #include <sys/dsched.h> 69 70 static MALLOC_DEFINE(M_ATFORK, "atfork", "atfork callback"); 71 static MALLOC_DEFINE(M_REAPER, "reaper", "process reapers"); 72 73 /* 74 * These are the stuctures used to create a callout list for things to do 75 * when forking a process 76 */ 77 struct forklist { 78 forklist_fn function; 79 TAILQ_ENTRY(forklist) next; 80 }; 81 82 TAILQ_HEAD(forklist_head, forklist); 83 static struct forklist_head fork_list = TAILQ_HEAD_INITIALIZER(fork_list); 84 85 static struct lwp *lwp_fork1(struct lwp *, struct proc *, int flags, 86 const cpumask_t *mask); 87 static void lwp_fork2(struct lwp *lp1, struct proc *destproc, 88 struct lwp *lp2, int flags); 89 static int lwp_create1(struct lwp_params *params, 90 const cpumask_t *mask); 91 static struct lock reaper_lock = LOCK_INITIALIZER("reapgl", 0, 0); 92 93 int forksleep; /* Place for fork1() to sleep on. */ 94 95 /* 96 * Red-Black tree support for LWPs 97 */ 98 99 static int 100 rb_lwp_compare(struct lwp *lp1, struct lwp *lp2) 101 { 102 if (lp1->lwp_tid < lp2->lwp_tid) 103 return(-1); 104 if (lp1->lwp_tid > lp2->lwp_tid) 105 return(1); 106 return(0); 107 } 108 109 RB_GENERATE2(lwp_rb_tree, lwp, u.lwp_rbnode, rb_lwp_compare, lwpid_t, lwp_tid); 110 111 /* 112 * When forking, memory underpinning umtx-supported mutexes may be set 113 * COW causing the physical address to change. We must wakeup any threads 114 * blocked on the physical address to allow them to re-resolve their VM. 115 * 116 * (caller is holding p->p_token) 117 */ 118 static void 119 wake_umtx_threads(struct proc *p1) 120 { 121 struct lwp *lp; 122 struct thread *td; 123 124 RB_FOREACH(lp, lwp_rb_tree, &p1->p_lwp_tree) { 125 td = lp->lwp_thread; 126 if (td && (td->td_flags & TDF_TSLEEPQ) && 127 (td->td_wdomain & PDOMAIN_MASK) == PDOMAIN_UMTX) { 128 wakeup_domain(td->td_wchan, PDOMAIN_UMTX); 129 } 130 } 131 } 132 133 /* 134 * fork() system call 135 */ 136 int 137 sys_fork(struct sysmsg *sysmsg, const struct fork_args *uap) 138 { 139 struct lwp *lp = curthread->td_lwp; 140 struct proc *p2; 141 int error; 142 143 error = fork1(lp, RFFDG | RFPROC | RFPGLOCK, &p2); 144 if (error == 0) { 145 PHOLD(p2); 146 start_forked_proc(lp, p2); 147 sysmsg->sysmsg_fds[0] = p2->p_pid; 148 sysmsg->sysmsg_fds[1] = 0; 149 PRELE(p2); 150 } 151 return error; 152 } 153 154 /* 155 * vfork() system call 156 */ 157 int 158 sys_vfork(struct sysmsg *sysmsg, const struct vfork_args *uap) 159 { 160 struct lwp *lp = curthread->td_lwp; 161 struct proc *p2; 162 int error; 163 164 error = fork1(lp, RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK, &p2); 165 if (error == 0) { 166 PHOLD(p2); 167 start_forked_proc(lp, p2); 168 sysmsg->sysmsg_fds[0] = p2->p_pid; 169 sysmsg->sysmsg_fds[1] = 0; 170 PRELE(p2); 171 } 172 return error; 173 } 174 175 /* 176 * Handle rforks. An rfork may (1) operate on the current process without 177 * creating a new, (2) create a new process that shared the current process's 178 * vmspace, signals, and/or descriptors, or (3) create a new process that does 179 * not share these things (normal fork). 180 * 181 * Note that we only call start_forked_proc() if a new process is actually 182 * created. 183 * 184 * rfork { int flags } 185 */ 186 int 187 sys_rfork(struct sysmsg *sysmsg, const struct rfork_args *uap) 188 { 189 struct lwp *lp = curthread->td_lwp; 190 struct proc *p2; 191 int error; 192 193 if ((uap->flags & RFKERNELONLY) != 0) 194 return (EINVAL); 195 196 error = fork1(lp, uap->flags | RFPGLOCK, &p2); 197 if (error == 0) { 198 if (p2) { 199 PHOLD(p2); 200 start_forked_proc(lp, p2); 201 sysmsg->sysmsg_fds[0] = p2->p_pid; 202 sysmsg->sysmsg_fds[1] = 0; 203 PRELE(p2); 204 } else { 205 sysmsg->sysmsg_fds[0] = 0; 206 sysmsg->sysmsg_fds[1] = 0; 207 } 208 } 209 return error; 210 } 211 212 static int 213 lwp_create1(struct lwp_params *uprm, const cpumask_t *umask) 214 { 215 struct proc *p = curproc; 216 struct lwp *lp; 217 struct lwp_params params; 218 cpumask_t *mask = NULL, mask0; 219 int error; 220 221 error = copyin(uprm, ¶ms, sizeof(params)); 222 if (error) 223 goto fail2; 224 225 if (umask != NULL) { 226 error = copyin(umask, &mask0, sizeof(mask0)); 227 if (error) 228 goto fail2; 229 CPUMASK_ANDMASK(mask0, smp_active_mask); 230 if (CPUMASK_TESTNZERO(mask0)) 231 mask = &mask0; 232 } 233 234 lwkt_gettoken(&p->p_token); 235 plimit_lwp_fork(p); /* force exclusive access */ 236 lp = lwp_fork1(curthread->td_lwp, p, RFPROC | RFMEM, mask); 237 lwp_fork2(curthread->td_lwp, p, lp, RFPROC | RFMEM); 238 error = cpu_prepare_lwp(lp, ¶ms); 239 if (error) 240 goto fail; 241 if (params.lwp_tid1 != NULL && 242 (error = copyout(&lp->lwp_tid, params.lwp_tid1, sizeof(lp->lwp_tid)))) 243 goto fail; 244 if (params.lwp_tid2 != NULL && 245 (error = copyout(&lp->lwp_tid, params.lwp_tid2, sizeof(lp->lwp_tid)))) 246 goto fail; 247 248 /* 249 * Now schedule the new lwp. 250 */ 251 p->p_usched->resetpriority(lp); 252 crit_enter(); 253 lp->lwp_stat = LSRUN; 254 p->p_usched->setrunqueue(lp); 255 crit_exit(); 256 lwkt_reltoken(&p->p_token); 257 258 return (0); 259 260 fail: 261 /* 262 * Make sure no one is using this lwp, before it is removed from 263 * the tree. If we didn't wait it here, lwp tree iteration with 264 * blocking operation would be broken. 265 */ 266 while (lp->lwp_lock > 0) 267 tsleep(lp, 0, "lwpfail", 1); 268 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp); 269 --p->p_nthreads; 270 /* lwp_dispose expects an exited lwp, and a held proc */ 271 atomic_set_int(&lp->lwp_mpflags, LWP_MP_WEXIT); 272 lp->lwp_thread->td_flags |= TDF_EXITING; 273 lwkt_remove_tdallq(lp->lwp_thread); 274 PHOLD(p); 275 biosched_done(lp->lwp_thread); 276 dsched_exit_thread(lp->lwp_thread); 277 lwp_dispose(lp); 278 lwkt_reltoken(&p->p_token); 279 fail2: 280 return (error); 281 } 282 283 /* 284 * Low level thread create used by pthreads. 285 */ 286 int 287 sys_lwp_create(struct sysmsg *sysmsg, const struct lwp_create_args *uap) 288 { 289 290 return (lwp_create1(uap->params, NULL)); 291 } 292 293 int 294 sys_lwp_create2(struct sysmsg *sysmsg, const struct lwp_create2_args *uap) 295 { 296 297 return (lwp_create1(uap->params, uap->mask)); 298 } 299 300 int nprocs = 1; /* process 0 */ 301 302 int 303 fork1(struct lwp *lp1, int flags, struct proc **procp) 304 { 305 struct proc *p1 = lp1->lwp_proc; 306 struct proc *p2; 307 struct proc *pptr; 308 struct pgrp *p1grp; 309 struct pgrp *plkgrp; 310 struct lwp *lp2; 311 struct sysreaper *reap; 312 uid_t uid; 313 int ok, error; 314 static int curfail = 0; 315 static struct timeval lastfail; 316 struct forklist *ep; 317 struct filedesc_to_leader *fdtol; 318 319 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG)) 320 return (EINVAL); 321 322 lwkt_gettoken(&p1->p_token); 323 plkgrp = NULL; 324 p2 = NULL; 325 326 /* 327 * Here we don't create a new process, but we divorce 328 * certain parts of a process from itself. 329 */ 330 if ((flags & RFPROC) == 0) { 331 /* 332 * This kind of stunt does not work anymore if 333 * there are native threads (lwps) running 334 */ 335 if (p1->p_nthreads != 1) { 336 error = EINVAL; 337 goto done; 338 } 339 340 vm_fork(p1, NULL, NULL, flags); 341 if ((flags & RFMEM) == 0) 342 wake_umtx_threads(p1); 343 344 /* 345 * Close all file descriptors. 346 */ 347 if (flags & RFCFDG) { 348 struct filedesc *fdtmp; 349 fdtmp = fdinit(p1); 350 fdfree(p1, fdtmp); 351 } 352 353 /* 354 * Unshare file descriptors (from parent.) 355 */ 356 if (flags & RFFDG) { 357 if (p1->p_fd->fd_refcnt > 1) { 358 struct filedesc *newfd; 359 error = fdcopy(p1, &newfd); 360 if (error != 0) { 361 error = ENOMEM; 362 goto done; 363 } 364 fdfree(p1, newfd); 365 } 366 } 367 *procp = NULL; 368 error = 0; 369 goto done; 370 } 371 372 /* 373 * Interlock against process group signal delivery. If signals 374 * are pending after the interlock is obtained we have to restart 375 * the system call to process the signals. If we don't the child 376 * can miss a pgsignal (such as ^C) sent during the fork. 377 * 378 * We can't use CURSIG() here because it will process any STOPs 379 * and cause the process group lock to be held indefinitely. If 380 * a STOP occurs, the fork will be restarted after the CONT. 381 */ 382 p1grp = p1->p_pgrp; 383 if ((flags & RFPGLOCK) && (plkgrp = p1->p_pgrp) != NULL) { 384 pgref(plkgrp); 385 lockmgr(&plkgrp->pg_lock, LK_SHARED); 386 if (CURSIG_NOBLOCK(lp1)) { 387 error = ERESTART; 388 goto done; 389 } 390 } 391 392 /* 393 * Although process entries are dynamically created, we still keep 394 * a global limit on the maximum number we will create. Don't allow 395 * a nonprivileged user to use the last ten processes; don't let root 396 * exceed the limit. The variable nprocs is the current number of 397 * processes, maxproc is the limit. 398 */ 399 uid = lp1->lwp_thread->td_ucred->cr_ruid; 400 if ((nprocs >= maxproc - 10 && uid != 0) || nprocs >= maxproc) { 401 if (ppsratecheck(&lastfail, &curfail, 1)) 402 kprintf("maxproc limit exceeded by uid %d, please " 403 "see tuning(7) and login.conf(5).\n", uid); 404 tsleep(&forksleep, 0, "fork", hz / 2); 405 error = EAGAIN; 406 goto done; 407 } 408 409 /* 410 * Increment the nprocs resource before blocking can occur. There 411 * are hard-limits as to the number of processes that can run. 412 */ 413 atomic_add_int(&nprocs, 1); 414 415 /* 416 * Increment the count of procs running with this uid. This also 417 * applies to root. 418 */ 419 ok = chgproccnt(lp1->lwp_thread->td_ucred->cr_ruidinfo, 1, 420 plimit_getadjvalue(RLIMIT_NPROC)); 421 if (!ok) { 422 /* 423 * Back out the process count 424 */ 425 atomic_add_int(&nprocs, -1); 426 if (ppsratecheck(&lastfail, &curfail, 1)) { 427 kprintf("maxproc limit of %jd " 428 "exceeded by \"%s\" uid %d, " 429 "please see tuning(7) and login.conf(5).\n", 430 plimit_getadjvalue(RLIMIT_NPROC), 431 p1->p_comm, 432 uid); 433 } 434 tsleep(&forksleep, 0, "fork", hz / 2); 435 error = EAGAIN; 436 goto done; 437 } 438 439 /* 440 * Allocate a new process, don't get fancy: zero the structure. 441 */ 442 p2 = kmalloc(sizeof(struct proc), M_PROC, M_WAITOK|M_ZERO); 443 444 /* 445 * Core initialization. SIDL is a safety state that protects the 446 * partially initialized process once it starts getting hooked 447 * into system structures and becomes addressable. 448 * 449 * We must be sure to acquire p2->p_token as well, we must hold it 450 * once the process is on the allproc list to avoid things such 451 * as competing modifications to p_flags. 452 */ 453 mycpu->gd_forkid += ncpus; 454 p2->p_forkid = mycpu->gd_forkid + mycpu->gd_cpuid; 455 p2->p_lasttid = 0; /* first tid will be 1 */ 456 p2->p_stat = SIDL; 457 458 /* 459 * NOTE: Process 0 will not have a reaper, but process 1 (init) and 460 * all other processes always will. 461 */ 462 if ((reap = p1->p_reaper) != NULL) { 463 reaper_hold(reap); 464 p2->p_reaper = reap; 465 } else { 466 p2->p_reaper = NULL; 467 } 468 469 RB_INIT(&p2->p_lwp_tree); 470 spin_init(&p2->p_spin, "procfork1"); 471 lwkt_token_init(&p2->p_token, "proc"); 472 lwkt_gettoken(&p2->p_token); 473 p2->p_uidpcpu = kmalloc(sizeof(*p2->p_uidpcpu) * ncpus, 474 M_SUBPROC, M_WAITOK | M_ZERO); 475 476 /* 477 * Setup linkage for kernel based threading XXX lwp. Also add the 478 * process to the allproclist. 479 * 480 * The process structure is addressable after this point. 481 */ 482 if (flags & RFTHREAD) { 483 p2->p_peers = p1->p_peers; 484 p1->p_peers = p2; 485 p2->p_leader = p1->p_leader; 486 } else { 487 p2->p_leader = p2; 488 } 489 proc_add_allproc(p2); 490 491 /* 492 * Initialize the section which is copied verbatim from the parent. 493 */ 494 bcopy(&p1->p_startcopy, &p2->p_startcopy, 495 ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy)); 496 497 /* 498 * Duplicate sub-structures as needed. Increase reference counts 499 * on shared objects. 500 * 501 * NOTE: because we are now on the allproc list it is possible for 502 * other consumers to gain temporary references to p2 503 * (p2->p_lock can change). 504 */ 505 if (p1->p_flags & P_PROFIL) 506 startprofclock(p2); 507 p2->p_ucred = crhold(lp1->lwp_thread->td_ucred); 508 509 if (jailed(p2->p_ucred)) 510 p2->p_flags |= P_JAILED; 511 512 if (p2->p_args) 513 refcount_acquire(&p2->p_args->ar_ref); 514 515 p2->p_usched = p1->p_usched; 516 /* XXX: verify copy of the secondary iosched stuff */ 517 dsched_enter_proc(p2); 518 519 if (flags & RFSIGSHARE) { 520 p2->p_sigacts = p1->p_sigacts; 521 refcount_acquire(&p2->p_sigacts->ps_refcnt); 522 } else { 523 p2->p_sigacts = kmalloc(sizeof(*p2->p_sigacts), 524 M_SUBPROC, M_WAITOK); 525 bcopy(p1->p_sigacts, p2->p_sigacts, sizeof(*p2->p_sigacts)); 526 refcount_init(&p2->p_sigacts->ps_refcnt, 1); 527 } 528 if (flags & RFLINUXTHPN) 529 p2->p_sigparent = SIGUSR1; 530 else 531 p2->p_sigparent = SIGCHLD; 532 533 /* bump references to the text vnode (for procfs) */ 534 p2->p_textvp = p1->p_textvp; 535 if (p2->p_textvp) 536 vref(p2->p_textvp); 537 538 /* copy namecache handle to the text file */ 539 if (p1->p_textnch.mount) 540 cache_copy(&p1->p_textnch, &p2->p_textnch); 541 542 /* 543 * Handle file descriptors 544 */ 545 if (flags & RFCFDG) { 546 p2->p_fd = fdinit(p1); 547 fdtol = NULL; 548 } else if (flags & RFFDG) { 549 error = fdcopy(p1, &p2->p_fd); 550 if (error != 0) { 551 error = ENOMEM; 552 goto done; 553 } 554 fdtol = NULL; 555 } else { 556 p2->p_fd = fdshare(p1); 557 if (p1->p_fdtol == NULL) { 558 p1->p_fdtol = filedesc_to_leader_alloc(NULL, 559 p1->p_leader); 560 } 561 if ((flags & RFTHREAD) != 0) { 562 /* 563 * Shared file descriptor table and 564 * shared process leaders. 565 */ 566 fdtol = p1->p_fdtol; 567 fdtol->fdl_refcount++; 568 } else { 569 /* 570 * Shared file descriptor table, and 571 * different process leaders 572 */ 573 fdtol = filedesc_to_leader_alloc(p1->p_fdtol, p2); 574 } 575 } 576 p2->p_fdtol = fdtol; 577 p2->p_limit = plimit_fork(p1); 578 579 /* 580 * Adjust depth for resource downscaling 581 */ 582 if ((p2->p_depth & 31) != 31) 583 ++p2->p_depth; 584 585 /* 586 * Preserve some more flags in subprocess. P_PROFIL has already 587 * been preserved. 588 */ 589 p2->p_flags |= p1->p_flags & P_SUGID; 590 if (p1->p_session->s_ttyvp != NULL && (p1->p_flags & P_CONTROLT)) 591 p2->p_flags |= P_CONTROLT; 592 if (flags & RFPPWAIT) { 593 p2->p_flags |= P_PPWAIT; 594 if (p1->p_upmap) 595 atomic_add_int(&p1->p_upmap->invfork, 1); 596 } 597 598 /* 599 * Inherit the virtual kernel structure (allows a virtual kernel 600 * to fork to simulate multiple cpus). 601 */ 602 if (p1->p_vkernel) 603 vkernel_inherit(p1, p2); 604 605 /* 606 * Once we are on a pglist we may receive signals. XXX we might 607 * race a ^C being sent to the process group by not receiving it 608 * at all prior to this line. 609 */ 610 pgref(p1grp); 611 lwkt_gettoken(&p1grp->pg_token); 612 LIST_INSERT_AFTER(p1, p2, p_pglist); 613 lwkt_reltoken(&p1grp->pg_token); 614 615 /* 616 * Attach the new process to its parent. 617 * 618 * If RFNOWAIT is set, the newly created process becomes a child 619 * of the reaper (typically init). This effectively disassociates 620 * the child from the parent. 621 * 622 * Temporarily hold pptr for the RFNOWAIT case to avoid ripouts. 623 */ 624 if (flags & RFNOWAIT) { 625 pptr = reaper_get(reap); 626 if (pptr == NULL) { 627 pptr = initproc; 628 PHOLD(pptr); 629 } 630 } else { 631 pptr = p1; 632 } 633 p2->p_pptr = pptr; 634 p2->p_ppid = pptr->p_pid; 635 LIST_INIT(&p2->p_children); 636 637 lwkt_gettoken(&pptr->p_token); 638 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); 639 lwkt_reltoken(&pptr->p_token); 640 641 if (flags & RFNOWAIT) 642 PRELE(pptr); 643 644 varsymset_init(&p2->p_varsymset, &p1->p_varsymset); 645 callout_init_mp(&p2->p_ithandle); 646 647 #ifdef KTRACE 648 /* 649 * Copy traceflag and tracefile if enabled. If not inherited, 650 * these were zeroed above but we still could have a trace race 651 * so make sure p2's p_tracenode is NULL. 652 */ 653 if ((p1->p_traceflag & KTRFAC_INHERIT) && p2->p_tracenode == NULL) { 654 p2->p_traceflag = p1->p_traceflag; 655 p2->p_tracenode = ktrinherit(p1->p_tracenode); 656 } 657 #endif 658 659 /* 660 * This begins the section where we must prevent the parent 661 * from being messed with too heavily while we run through the 662 * fork operation. 663 * 664 * Gets PRELE'd in the caller in start_forked_proc(). 665 * 666 * Create the first lwp associated with the new proc. It will 667 * return via a different execution path later, directly into 668 * userland, after it was put on the runq by start_forked_proc(). 669 */ 670 PHOLD(p1); 671 672 lp2 = lwp_fork1(lp1, p2, flags, NULL); 673 vm_fork(p1, p2, lp2, flags); 674 if ((flags & RFMEM) == 0) 675 wake_umtx_threads(p1); 676 lwp_fork2(lp1, p2, lp2, flags); 677 678 if (flags == (RFFDG | RFPROC | RFPGLOCK)) { 679 mycpu->gd_cnt.v_forks++; 680 mycpu->gd_cnt.v_forkpages += btoc(p2->p_vmspace->vm_dsize) + 681 btoc(p2->p_vmspace->vm_ssize); 682 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK)) { 683 mycpu->gd_cnt.v_vforks++; 684 mycpu->gd_cnt.v_vforkpages += btoc(p2->p_vmspace->vm_dsize) + 685 btoc(p2->p_vmspace->vm_ssize); 686 } else if (p1 == &proc0) { 687 mycpu->gd_cnt.v_kthreads++; 688 mycpu->gd_cnt.v_kthreadpages += btoc(p2->p_vmspace->vm_dsize) + 689 btoc(p2->p_vmspace->vm_ssize); 690 } else { 691 mycpu->gd_cnt.v_rforks++; 692 mycpu->gd_cnt.v_rforkpages += btoc(p2->p_vmspace->vm_dsize) + 693 btoc(p2->p_vmspace->vm_ssize); 694 } 695 696 /* 697 * Both processes are set up, now check if any loadable modules want 698 * to adjust anything. 699 * What if they have an error? XXX 700 */ 701 TAILQ_FOREACH(ep, &fork_list, next) { 702 (*ep->function)(p1, p2, flags); 703 } 704 705 /* 706 * Set the start time. Note that the process is not runnable. The 707 * caller is responsible for making it runnable. 708 */ 709 microtime(&p2->p_start); 710 p2->p_acflag = AFORK; 711 712 /* 713 * tell any interested parties about the new process 714 */ 715 KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid); 716 717 /* 718 * Return child proc pointer to parent. 719 */ 720 *procp = p2; 721 error = 0; 722 done: 723 if (p2) 724 lwkt_reltoken(&p2->p_token); 725 lwkt_reltoken(&p1->p_token); 726 if (plkgrp) { 727 lockmgr(&plkgrp->pg_lock, LK_RELEASE); 728 pgrel(plkgrp); 729 } 730 return (error); 731 } 732 733 /* 734 * The first part of lwp_fork*() allocates enough of the new lwp that 735 * vm_fork() can use it to deal with /dev/lpmap mappings. 736 */ 737 static struct lwp * 738 lwp_fork1(struct lwp *lp1, struct proc *destproc, int flags, 739 const cpumask_t *mask) 740 { 741 struct lwp *lp2; 742 743 lp2 = kmalloc(sizeof(struct lwp), M_LWP, M_WAITOK|M_ZERO); 744 lp2->lwp_proc = destproc; 745 lp2->lwp_stat = LSRUN; 746 bcopy(&lp1->lwp_startcopy, &lp2->lwp_startcopy, 747 (unsigned) ((caddr_t)&lp2->lwp_endcopy - 748 (caddr_t)&lp2->lwp_startcopy)); 749 if (mask != NULL) 750 lp2->lwp_cpumask = *mask; 751 752 lwkt_token_init(&lp2->lwp_token, "lwp_token"); 753 TAILQ_INIT(&lp2->lwp_lpmap_backing_list); 754 spin_init(&lp2->lwp_spin, "lwptoken"); 755 756 /* 757 * Use the same TID for the first thread in the new process after 758 * a fork or vfork. This is needed to keep pthreads and /dev/lpmap 759 * sane. In particular a consequence of implementing the per-thread 760 * /dev/lpmap map code makes this mandatory. 761 * 762 * NOTE: exec*() will reset the TID to 1 to keep things sane in that 763 * department too. 764 * 765 * NOTE: In the case of lwp_create(), this TID represents a conflict 766 * which will be resolved in lwp_fork2(), but in the case of 767 * a fork(), the TID has to be correct or vm_fork() will not 768 * keep the correct lpmap. 769 */ 770 lp2->lwp_tid = lp1->lwp_tid; 771 772 return lp2; 773 } 774 775 /* 776 * The second part of lwp_fork*() 777 */ 778 static void 779 lwp_fork2(struct lwp *lp1, struct proc *destproc, struct lwp *lp2, int flags) 780 { 781 globaldata_t gd = mycpu; 782 struct thread *td2; 783 784 lp2->lwp_vmspace = destproc->p_vmspace; 785 786 /* 787 * Reset the sigaltstack if memory is shared, otherwise inherit 788 * it. 789 */ 790 if (flags & RFMEM) { 791 lp2->lwp_sigstk.ss_flags = SS_DISABLE; 792 lp2->lwp_sigstk.ss_size = 0; 793 lp2->lwp_sigstk.ss_sp = NULL; 794 lp2->lwp_flags &= ~LWP_ALTSTACK; 795 } else { 796 lp2->lwp_flags |= lp1->lwp_flags & LWP_ALTSTACK; 797 } 798 799 /* 800 * Set cpbase to the last timeout that occured (not the upcoming 801 * timeout). 802 * 803 * A critical section is required since a timer IPI can update 804 * scheduler specific data. 805 */ 806 crit_enter(); 807 lp2->lwp_cpbase = gd->gd_schedclock.time - gd->gd_schedclock.periodic; 808 destproc->p_usched->heuristic_forking(lp1, lp2); 809 crit_exit(); 810 CPUMASK_ANDMASK(lp2->lwp_cpumask, usched_mastermask); 811 812 /* 813 * Assign the thread to the current cpu to begin with so we 814 * can manipulate it. 815 */ 816 td2 = lwkt_alloc_thread(NULL, LWKT_THREAD_STACK, gd->gd_cpuid, 0); 817 lp2->lwp_thread = td2; 818 td2->td_wakefromcpu = gd->gd_cpuid; 819 td2->td_ucred = crhold(destproc->p_ucred); 820 td2->td_proc = destproc; 821 td2->td_lwp = lp2; 822 td2->td_switch = cpu_heavy_switch; 823 #ifdef NO_LWKT_SPLIT_USERPRI 824 lwkt_setpri(td2, TDPRI_USER_NORM); 825 #else 826 lwkt_setpri(td2, TDPRI_KERN_USER); 827 #endif 828 lwkt_set_comm(td2, "%s", destproc->p_comm); 829 830 /* 831 * cpu_fork will copy and update the pcb, set up the kernel stack, 832 * and make the child ready to run. 833 */ 834 cpu_fork(lp1, lp2, flags); 835 kqueue_init(&lp2->lwp_kqueue, destproc->p_fd); 836 837 /* 838 * Associate the new thread with destproc, after we've set most of 839 * it up and gotten its related td2 installed. Otherwise we can 840 * race other random kernel code that iterates LWPs and expects the 841 * thread to be assigned. 842 * 843 * Leave 2 bits open so the pthreads library can optimize locks 844 * by combining the TID with a few Lock-related flags. 845 */ 846 while (lwp_rb_tree_RB_INSERT(&destproc->p_lwp_tree, lp2) != NULL) { 847 ++lp2->lwp_tid; 848 if (lp2->lwp_tid == 0 || lp2->lwp_tid == 0x3FFFFFFF) 849 lp2->lwp_tid = 1; 850 } 851 852 destproc->p_lasttid = lp2->lwp_tid; 853 destproc->p_nthreads++; 854 855 /* 856 * This flag is set and never cleared. It means that the process 857 * was threaded at some point. Used to improve exit performance. 858 */ 859 pmap_maybethreaded(&destproc->p_vmspace->vm_pmap); 860 destproc->p_flags |= P_MAYBETHREADED; 861 862 /* 863 * If the original lp had a lpmap and a non-zero blockallsigs 864 * count, give the lp for the forked process the same count. 865 * 866 * This makes the user code and expectations less confusing 867 * in terms of unwinding locks and also allows userland to start 868 * the forked process with signals blocked via the blockallsigs() 869 * mechanism if desired. 870 */ 871 if (lp1->lwp_lpmap && 872 (lp1->lwp_lpmap->blockallsigs & 0x7FFFFFFF)) { 873 lwp_usermap(lp2, 0); 874 if (lp2->lwp_lpmap) { 875 lp2->lwp_lpmap->blockallsigs = 876 lp1->lwp_lpmap->blockallsigs; 877 } 878 } 879 } 880 881 /* 882 * The next two functionms are general routines to handle adding/deleting 883 * items on the fork callout list. 884 * 885 * at_fork(): 886 * Take the arguments given and put them onto the fork callout list, 887 * However first make sure that it's not already there. 888 * Returns 0 on success or a standard error number. 889 */ 890 int 891 at_fork(forklist_fn function) 892 { 893 struct forklist *ep; 894 895 #ifdef INVARIANTS 896 /* let the programmer know if he's been stupid */ 897 if (rm_at_fork(function)) { 898 kprintf("WARNING: fork callout entry (%p) already present\n", 899 function); 900 } 901 #endif 902 ep = kmalloc(sizeof(*ep), M_ATFORK, M_WAITOK|M_ZERO); 903 ep->function = function; 904 TAILQ_INSERT_TAIL(&fork_list, ep, next); 905 return (0); 906 } 907 908 /* 909 * Scan the exit callout list for the given item and remove it.. 910 * Returns the number of items removed (0 or 1) 911 */ 912 int 913 rm_at_fork(forklist_fn function) 914 { 915 struct forklist *ep; 916 917 TAILQ_FOREACH(ep, &fork_list, next) { 918 if (ep->function == function) { 919 TAILQ_REMOVE(&fork_list, ep, next); 920 kfree(ep, M_ATFORK); 921 return(1); 922 } 923 } 924 return (0); 925 } 926 927 /* 928 * Add a forked process to the run queue after any remaining setup, such 929 * as setting the fork handler, has been completed. 930 * 931 * p2 is held by the caller. 932 */ 933 void 934 start_forked_proc(struct lwp *lp1, struct proc *p2) 935 { 936 struct lwp *lp2 = ONLY_LWP_IN_PROC(p2); 937 int pflags; 938 939 /* 940 * Move from SIDL to RUN queue, and activate the process's thread. 941 * Activation of the thread effectively makes the process "a" 942 * current process, so we do not setrunqueue(). 943 * 944 * YYY setrunqueue works here but we should clean up the trampoline 945 * code so we just schedule the LWKT thread and let the trampoline 946 * deal with the userland scheduler on return to userland. 947 */ 948 KASSERT(p2->p_stat == SIDL, 949 ("cannot start forked process, bad status: %p", p2)); 950 p2->p_usched->resetpriority(lp2); 951 crit_enter(); 952 p2->p_stat = SACTIVE; 953 lp2->lwp_stat = LSRUN; 954 p2->p_usched->setrunqueue(lp2); 955 crit_exit(); 956 957 /* 958 * Now can be swapped. 959 */ 960 PRELE(lp1->lwp_proc); 961 962 /* 963 * Preserve synchronization semantics of vfork. P_PPWAIT is set in 964 * the child until it has retired the parent's resources. The parent 965 * must wait for the flag to be cleared by the child. 966 * 967 * Interlock the flag/tsleep with atomic ops to avoid unnecessary 968 * p_token conflicts. 969 * 970 * XXX Is this use of an atomic op on a field that is not normally 971 * manipulated with atomic ops ok? 972 */ 973 while ((pflags = p2->p_flags) & P_PPWAIT) { 974 cpu_ccfence(); 975 tsleep_interlock(lp1->lwp_proc, 0); 976 if (atomic_cmpset_int(&p2->p_flags, pflags, pflags)) 977 tsleep(lp1->lwp_proc, PINTERLOCKED, "ppwait", 0); 978 } 979 } 980 981 /* 982 * procctl (idtype_t idtype, id_t id, int cmd, void *arg) 983 */ 984 int 985 sys_procctl(struct sysmsg *sysmsg, const struct procctl_args *uap) 986 { 987 struct proc *p = curproc; 988 struct proc *p2; 989 struct sysreaper *reap; 990 union reaper_info udata; 991 int error; 992 993 if (uap->idtype != P_PID) 994 return EINVAL; 995 if (uap->id != 0 && uap->id != (id_t)p->p_pid) 996 return EINVAL; 997 998 switch(uap->cmd) { 999 case PROC_REAP_ACQUIRE: 1000 lwkt_gettoken(&p->p_token); 1001 reap = kmalloc(sizeof(*reap), M_REAPER, M_WAITOK|M_ZERO); 1002 if (p->p_reaper == NULL || p->p_reaper->p != p) { 1003 reaper_init(p, reap); 1004 error = 0; 1005 } else { 1006 kfree(reap, M_REAPER); 1007 error = EALREADY; 1008 } 1009 lwkt_reltoken(&p->p_token); 1010 break; 1011 case PROC_REAP_RELEASE: 1012 lwkt_gettoken(&p->p_token); 1013 release_again: 1014 reap = p->p_reaper; 1015 KKASSERT(reap != NULL); 1016 if (reap->p == p) { 1017 reaper_hold(reap); /* in case of thread race */ 1018 lockmgr(&reap->lock, LK_EXCLUSIVE); 1019 if (reap->p != p) { 1020 lockmgr(&reap->lock, LK_RELEASE); 1021 reaper_drop(reap); 1022 goto release_again; 1023 } 1024 reap->p = NULL; 1025 p->p_reaper = reap->parent; 1026 if (p->p_reaper) 1027 reaper_hold(p->p_reaper); 1028 lockmgr(&reap->lock, LK_RELEASE); 1029 reaper_drop(reap); /* our ref */ 1030 reaper_drop(reap); /* old p_reaper ref */ 1031 error = 0; 1032 } else { 1033 error = ENOTCONN; 1034 } 1035 lwkt_reltoken(&p->p_token); 1036 break; 1037 case PROC_REAP_STATUS: 1038 bzero(&udata, sizeof(udata)); 1039 lwkt_gettoken_shared(&p->p_token); 1040 if ((reap = p->p_reaper) != NULL && reap->p == p) { 1041 udata.status.flags = reap->flags; 1042 udata.status.refs = reap->refs - 1; /* minus ours */ 1043 } 1044 p2 = LIST_FIRST(&p->p_children); 1045 udata.status.pid_head = p2 ? p2->p_pid : -1; 1046 lwkt_reltoken(&p->p_token); 1047 1048 if (uap->data) { 1049 error = copyout(&udata, uap->data, 1050 sizeof(udata.status)); 1051 } else { 1052 error = 0; 1053 } 1054 break; 1055 case PROC_PDEATHSIG_CTL: 1056 error = EINVAL; 1057 if (uap->data) { 1058 int dsig = 0; 1059 1060 error = copyin(uap->data, &dsig, sizeof(dsig)); 1061 if (error == 0 && dsig >= 0 && dsig <= _SIG_MAXSIG) 1062 p->p_deathsig = dsig; 1063 } 1064 break; 1065 case PROC_PDEATHSIG_STATUS: 1066 error = EINVAL; 1067 if (uap->data) { 1068 error = copyout(&p->p_deathsig, uap->data, 1069 sizeof(p->p_deathsig)); 1070 } 1071 break; 1072 default: 1073 error = EINVAL; 1074 break; 1075 } 1076 return error; 1077 } 1078 1079 /* 1080 * Bump ref on reaper, preventing destruction 1081 */ 1082 void 1083 reaper_hold(struct sysreaper *reap) 1084 { 1085 KKASSERT(reap->refs > 0); 1086 refcount_acquire(&reap->refs); 1087 } 1088 1089 /* 1090 * Drop ref on reaper, destroy the structure on the 1->0 1091 * transition and loop on the parent. 1092 */ 1093 void 1094 reaper_drop(struct sysreaper *next) 1095 { 1096 struct sysreaper *reap; 1097 1098 while ((reap = next) != NULL) { 1099 if (refcount_release(&reap->refs)) { 1100 next = reap->parent; 1101 KKASSERT(reap->p == NULL); 1102 lockmgr(&reaper_lock, LK_EXCLUSIVE); 1103 reap->parent = NULL; 1104 kfree(reap, M_REAPER); 1105 lockmgr(&reaper_lock, LK_RELEASE); 1106 } else { 1107 next = NULL; 1108 } 1109 } 1110 } 1111 1112 /* 1113 * Initialize a static or newly allocated reaper structure 1114 */ 1115 void 1116 reaper_init(struct proc *p, struct sysreaper *reap) 1117 { 1118 reap->parent = p->p_reaper; 1119 reap->p = p; 1120 if (p == initproc) { 1121 reap->flags = REAPER_STAT_OWNED | REAPER_STAT_REALINIT; 1122 reap->refs = 2; 1123 } else { 1124 reap->flags = REAPER_STAT_OWNED; 1125 reap->refs = 1; 1126 } 1127 lockinit(&reap->lock, "subrp", 0, 0); 1128 cpu_sfence(); 1129 p->p_reaper = reap; 1130 } 1131 1132 /* 1133 * Called with p->p_token held during exit. 1134 * 1135 * This is a bit simpler than RELEASE because there are no threads remaining 1136 * to race. We only release if we own the reaper, the exit code will handle 1137 * the final p_reaper release. 1138 */ 1139 struct sysreaper * 1140 reaper_exit(struct proc *p) 1141 { 1142 struct sysreaper *reap; 1143 1144 /* 1145 * Release acquired reaper 1146 */ 1147 if ((reap = p->p_reaper) != NULL && reap->p == p) { 1148 lockmgr(&reap->lock, LK_EXCLUSIVE); 1149 p->p_reaper = reap->parent; 1150 if (p->p_reaper) 1151 reaper_hold(p->p_reaper); 1152 reap->p = NULL; 1153 lockmgr(&reap->lock, LK_RELEASE); 1154 reaper_drop(reap); 1155 } 1156 1157 /* 1158 * Return and clear reaper (caller is holding p_token for us) 1159 * (reap->p does not equal p). Caller must drop it. 1160 */ 1161 if ((reap = p->p_reaper) != NULL) { 1162 p->p_reaper = NULL; 1163 } 1164 return reap; 1165 } 1166 1167 /* 1168 * Return a held (PHOLD) process representing the reaper for process (p). 1169 * NULL should not normally be returned. Caller should PRELE() the returned 1170 * reaper process when finished. 1171 * 1172 * Remove dead internal nodes while we are at it. 1173 * 1174 * Process (p)'s token must be held on call. 1175 * The returned process's token is NOT acquired by this routine. 1176 */ 1177 struct proc * 1178 reaper_get(struct sysreaper *reap) 1179 { 1180 struct sysreaper *next; 1181 struct proc *reproc; 1182 1183 if (reap == NULL) 1184 return NULL; 1185 1186 /* 1187 * Extra hold for loop 1188 */ 1189 reaper_hold(reap); 1190 1191 while (reap) { 1192 lockmgr(&reap->lock, LK_SHARED); 1193 if (reap->p) { 1194 /* 1195 * Probable reaper 1196 */ 1197 if (reap->p) { 1198 reproc = reap->p; 1199 PHOLD(reproc); 1200 lockmgr(&reap->lock, LK_RELEASE); 1201 reaper_drop(reap); 1202 return reproc; 1203 } 1204 1205 /* 1206 * Raced, try again 1207 */ 1208 lockmgr(&reap->lock, LK_RELEASE); 1209 continue; 1210 } 1211 1212 /* 1213 * Traverse upwards in the reaper topology, destroy 1214 * dead internal nodes when possible. 1215 * 1216 * NOTE: Our ref on next means that a dead node should 1217 * have 2 (ours and reap->parent's). 1218 */ 1219 next = reap->parent; 1220 while (next) { 1221 reaper_hold(next); 1222 if (next->refs == 2 && next->p == NULL) { 1223 lockmgr(&reap->lock, LK_RELEASE); 1224 lockmgr(&reap->lock, LK_EXCLUSIVE); 1225 if (next->refs == 2 && 1226 reap->parent == next && 1227 next->p == NULL) { 1228 /* 1229 * reap->parent inherits ref from next. 1230 */ 1231 reap->parent = next->parent; 1232 next->parent = NULL; 1233 reaper_drop(next); /* ours */ 1234 reaper_drop(next); /* old parent */ 1235 next = reap->parent; 1236 continue; /* possible chain */ 1237 } 1238 } 1239 break; 1240 } 1241 lockmgr(&reap->lock, LK_RELEASE); 1242 reaper_drop(reap); 1243 reap = next; 1244 } 1245 return NULL; 1246 } 1247 1248 /* 1249 * Test that the sender is allowed to send a signal to the target. 1250 * The sender process is assumed to have a stable reaper. The 1251 * target can be e.g. from a scan callback. 1252 * 1253 * Target cannot be the reaper process itself unless reaper_ok is specified, 1254 * or sender == target. 1255 */ 1256 int 1257 reaper_sigtest(struct proc *sender, struct proc *target, int reaper_ok) 1258 { 1259 struct sysreaper *sreap; 1260 struct sysreaper *reap; 1261 int r; 1262 1263 sreap = sender->p_reaper; 1264 if (sreap == NULL) 1265 return 1; 1266 1267 if (sreap == target->p_reaper) { 1268 if (sreap->p == target && sreap->p != sender && reaper_ok == 0) 1269 return 0; 1270 return 1; 1271 } 1272 lockmgr(&reaper_lock, LK_SHARED); 1273 r = 0; 1274 for (reap = target->p_reaper; reap; reap = reap->parent) { 1275 if (sreap == reap) { 1276 if (sreap->p != target || reaper_ok) 1277 r = 1; 1278 break; 1279 } 1280 } 1281 lockmgr(&reaper_lock, LK_RELEASE); 1282 1283 return r; 1284 } 1285