1 /*- 2 * Copyright (C) 2001 Julian Elischer <julian@freebsd.org>. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice(s), this list of conditions and the following disclaimer as 10 * the first lines of this file unmodified other than the possible 11 * addition of one or more copyright notices. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice(s), this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 17 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 19 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 20 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 22 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 23 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 26 * DAMAGE. 27 */ 28 29 #include "opt_witness.h" 30 #include "opt_hwpmc_hooks.h" 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/kernel.h> 38 #include <sys/lock.h> 39 #include <sys/mutex.h> 40 #include <sys/proc.h> 41 #include <sys/rangelock.h> 42 #include <sys/resourcevar.h> 43 #include <sys/sdt.h> 44 #include <sys/smp.h> 45 #include <sys/sched.h> 46 #include <sys/sleepqueue.h> 47 #include <sys/selinfo.h> 48 #include <sys/syscallsubr.h> 49 #include <sys/sysent.h> 50 #include <sys/turnstile.h> 51 #include <sys/ktr.h> 52 #include <sys/rwlock.h> 53 #include <sys/umtx.h> 54 #include <sys/cpuset.h> 55 #ifdef HWPMC_HOOKS 56 #include <sys/pmckern.h> 57 #endif 58 59 #include <security/audit/audit.h> 60 61 #include <vm/vm.h> 62 #include <vm/vm_extern.h> 63 #include <vm/uma.h> 64 #include <vm/vm_domain.h> 65 #include <sys/eventhandler.h> 66 67 SDT_PROVIDER_DECLARE(proc); 68 SDT_PROBE_DEFINE(proc, , , lwp__exit); 69 70 /* 71 * thread related storage. 72 */ 73 static uma_zone_t thread_zone; 74 75 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); 76 static struct mtx zombie_lock; 77 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN); 78 79 static void thread_zombie(struct thread *); 80 static int thread_unsuspend_one(struct thread *td, struct proc *p, 81 bool boundary); 82 83 #define TID_BUFFER_SIZE 1024 84 85 struct mtx tid_lock; 86 static struct unrhdr *tid_unrhdr; 87 static lwpid_t tid_buffer[TID_BUFFER_SIZE]; 88 static int tid_head, tid_tail; 89 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); 90 91 struct tidhashhead *tidhashtbl; 92 u_long tidhash; 93 struct rwlock tidhash_lock; 94 95 static lwpid_t 96 tid_alloc(void) 97 { 98 lwpid_t tid; 99 100 tid = alloc_unr(tid_unrhdr); 101 if (tid != -1) 102 return (tid); 103 mtx_lock(&tid_lock); 104 if (tid_head == tid_tail) { 105 mtx_unlock(&tid_lock); 106 return (-1); 107 } 108 tid = tid_buffer[tid_head]; 109 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 110 mtx_unlock(&tid_lock); 111 return (tid); 112 } 113 114 static void 115 tid_free(lwpid_t tid) 116 { 117 lwpid_t tmp_tid = -1; 118 119 mtx_lock(&tid_lock); 120 if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) { 121 tmp_tid = tid_buffer[tid_head]; 122 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 123 } 124 tid_buffer[tid_tail] = tid; 125 tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE; 126 mtx_unlock(&tid_lock); 127 if (tmp_tid != -1) 128 free_unr(tid_unrhdr, tmp_tid); 129 } 130 131 /* 132 * Prepare a thread for use. 133 */ 134 static int 135 thread_ctor(void *mem, int size, void *arg, int flags) 136 { 137 struct thread *td; 138 139 td = (struct thread *)mem; 140 td->td_state = TDS_INACTIVE; 141 td->td_oncpu = NOCPU; 142 143 td->td_tid = tid_alloc(); 144 145 /* 146 * Note that td_critnest begins life as 1 because the thread is not 147 * running and is thereby implicitly waiting to be on the receiving 148 * end of a context switch. 149 */ 150 td->td_critnest = 1; 151 td->td_lend_user_pri = PRI_MAX; 152 EVENTHANDLER_INVOKE(thread_ctor, td); 153 #ifdef AUDIT 154 audit_thread_alloc(td); 155 #endif 156 umtx_thread_alloc(td); 157 return (0); 158 } 159 160 /* 161 * Reclaim a thread after use. 162 */ 163 static void 164 thread_dtor(void *mem, int size, void *arg) 165 { 166 struct thread *td; 167 168 td = (struct thread *)mem; 169 170 #ifdef INVARIANTS 171 /* Verify that this thread is in a safe state to free. */ 172 switch (td->td_state) { 173 case TDS_INHIBITED: 174 case TDS_RUNNING: 175 case TDS_CAN_RUN: 176 case TDS_RUNQ: 177 /* 178 * We must never unlink a thread that is in one of 179 * these states, because it is currently active. 180 */ 181 panic("bad state for thread unlinking"); 182 /* NOTREACHED */ 183 case TDS_INACTIVE: 184 break; 185 default: 186 panic("bad thread state"); 187 /* NOTREACHED */ 188 } 189 #endif 190 #ifdef AUDIT 191 audit_thread_free(td); 192 #endif 193 /* Free all OSD associated to this thread. */ 194 osd_thread_exit(td); 195 td_softdep_cleanup(td); 196 MPASS(td->td_su == NULL); 197 198 EVENTHANDLER_INVOKE(thread_dtor, td); 199 tid_free(td->td_tid); 200 } 201 202 /* 203 * Initialize type-stable parts of a thread (when newly created). 204 */ 205 static int 206 thread_init(void *mem, int size, int flags) 207 { 208 struct thread *td; 209 210 td = (struct thread *)mem; 211 212 td->td_sleepqueue = sleepq_alloc(); 213 td->td_turnstile = turnstile_alloc(); 214 td->td_rlqe = NULL; 215 EVENTHANDLER_INVOKE(thread_init, td); 216 umtx_thread_init(td); 217 td->td_kstack = 0; 218 td->td_sel = NULL; 219 return (0); 220 } 221 222 /* 223 * Tear down type-stable parts of a thread (just before being discarded). 224 */ 225 static void 226 thread_fini(void *mem, int size) 227 { 228 struct thread *td; 229 230 td = (struct thread *)mem; 231 EVENTHANDLER_INVOKE(thread_fini, td); 232 rlqentry_free(td->td_rlqe); 233 turnstile_free(td->td_turnstile); 234 sleepq_free(td->td_sleepqueue); 235 umtx_thread_fini(td); 236 seltdfini(td); 237 } 238 239 /* 240 * For a newly created process, 241 * link up all the structures and its initial threads etc. 242 * called from: 243 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc. 244 * proc_dtor() (should go away) 245 * proc_init() 246 */ 247 void 248 proc_linkup0(struct proc *p, struct thread *td) 249 { 250 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 251 proc_linkup(p, td); 252 } 253 254 void 255 proc_linkup(struct proc *p, struct thread *td) 256 { 257 258 sigqueue_init(&p->p_sigqueue, p); 259 p->p_ksi = ksiginfo_alloc(1); 260 if (p->p_ksi != NULL) { 261 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 262 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 263 } 264 LIST_INIT(&p->p_mqnotifier); 265 p->p_numthreads = 0; 266 thread_link(td, p); 267 } 268 269 /* 270 * Initialize global thread allocation resources. 271 */ 272 void 273 threadinit(void) 274 { 275 276 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 277 278 /* 279 * pid_max cannot be greater than PID_MAX. 280 * leave one number for thread0. 281 */ 282 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock); 283 284 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 285 thread_ctor, thread_dtor, thread_init, thread_fini, 286 32 - 1, UMA_ZONE_NOFREE); 287 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 288 rw_init(&tidhash_lock, "tidhash"); 289 } 290 291 /* 292 * Place an unused thread on the zombie list. 293 * Use the slpq as that must be unused by now. 294 */ 295 void 296 thread_zombie(struct thread *td) 297 { 298 mtx_lock_spin(&zombie_lock); 299 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 300 mtx_unlock_spin(&zombie_lock); 301 } 302 303 /* 304 * Release a thread that has exited after cpu_throw(). 305 */ 306 void 307 thread_stash(struct thread *td) 308 { 309 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 310 thread_zombie(td); 311 } 312 313 /* 314 * Reap zombie resources. 315 */ 316 void 317 thread_reap(void) 318 { 319 struct thread *td_first, *td_next; 320 321 /* 322 * Don't even bother to lock if none at this instant, 323 * we really don't care about the next instant. 324 */ 325 if (!TAILQ_EMPTY(&zombie_threads)) { 326 mtx_lock_spin(&zombie_lock); 327 td_first = TAILQ_FIRST(&zombie_threads); 328 if (td_first) 329 TAILQ_INIT(&zombie_threads); 330 mtx_unlock_spin(&zombie_lock); 331 while (td_first) { 332 td_next = TAILQ_NEXT(td_first, td_slpq); 333 thread_cow_free(td_first); 334 thread_free(td_first); 335 td_first = td_next; 336 } 337 } 338 } 339 340 /* 341 * Allocate a thread. 342 */ 343 struct thread * 344 thread_alloc(int pages) 345 { 346 struct thread *td; 347 348 thread_reap(); /* check if any zombies to get */ 349 350 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK); 351 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 352 if (!vm_thread_new(td, pages)) { 353 uma_zfree(thread_zone, td); 354 return (NULL); 355 } 356 cpu_thread_alloc(td); 357 vm_domain_policy_init(&td->td_vm_dom_policy); 358 return (td); 359 } 360 361 int 362 thread_alloc_stack(struct thread *td, int pages) 363 { 364 365 KASSERT(td->td_kstack == 0, 366 ("thread_alloc_stack called on a thread with kstack")); 367 if (!vm_thread_new(td, pages)) 368 return (0); 369 cpu_thread_alloc(td); 370 return (1); 371 } 372 373 /* 374 * Deallocate a thread. 375 */ 376 void 377 thread_free(struct thread *td) 378 { 379 380 lock_profile_thread_exit(td); 381 if (td->td_cpuset) 382 cpuset_rel(td->td_cpuset); 383 td->td_cpuset = NULL; 384 cpu_thread_free(td); 385 if (td->td_kstack != 0) 386 vm_thread_dispose(td); 387 vm_domain_policy_cleanup(&td->td_vm_dom_policy); 388 callout_drain(&td->td_slpcallout); 389 uma_zfree(thread_zone, td); 390 } 391 392 void 393 thread_cow_get_proc(struct thread *newtd, struct proc *p) 394 { 395 396 PROC_LOCK_ASSERT(p, MA_OWNED); 397 newtd->td_ucred = crhold(p->p_ucred); 398 newtd->td_limit = lim_hold(p->p_limit); 399 newtd->td_cowgen = p->p_cowgen; 400 } 401 402 void 403 thread_cow_get(struct thread *newtd, struct thread *td) 404 { 405 406 newtd->td_ucred = crhold(td->td_ucred); 407 newtd->td_limit = lim_hold(td->td_limit); 408 newtd->td_cowgen = td->td_cowgen; 409 } 410 411 void 412 thread_cow_free(struct thread *td) 413 { 414 415 if (td->td_ucred != NULL) 416 crfree(td->td_ucred); 417 if (td->td_limit != NULL) 418 lim_free(td->td_limit); 419 } 420 421 void 422 thread_cow_update(struct thread *td) 423 { 424 struct proc *p; 425 struct ucred *oldcred; 426 struct plimit *oldlimit; 427 428 p = td->td_proc; 429 oldcred = NULL; 430 oldlimit = NULL; 431 PROC_LOCK(p); 432 if (td->td_ucred != p->p_ucred) { 433 oldcred = td->td_ucred; 434 td->td_ucred = crhold(p->p_ucred); 435 } 436 if (td->td_limit != p->p_limit) { 437 oldlimit = td->td_limit; 438 td->td_limit = lim_hold(p->p_limit); 439 } 440 td->td_cowgen = p->p_cowgen; 441 PROC_UNLOCK(p); 442 if (oldcred != NULL) 443 crfree(oldcred); 444 if (oldlimit != NULL) 445 lim_free(oldlimit); 446 } 447 448 /* 449 * Discard the current thread and exit from its context. 450 * Always called with scheduler locked. 451 * 452 * Because we can't free a thread while we're operating under its context, 453 * push the current thread into our CPU's deadthread holder. This means 454 * we needn't worry about someone else grabbing our context before we 455 * do a cpu_throw(). 456 */ 457 void 458 thread_exit(void) 459 { 460 uint64_t runtime, new_switchtime; 461 struct thread *td; 462 struct thread *td2; 463 struct proc *p; 464 int wakeup_swapper; 465 466 td = curthread; 467 p = td->td_proc; 468 469 PROC_SLOCK_ASSERT(p, MA_OWNED); 470 mtx_assert(&Giant, MA_NOTOWNED); 471 472 PROC_LOCK_ASSERT(p, MA_OWNED); 473 KASSERT(p != NULL, ("thread exiting without a process")); 474 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 475 (long)p->p_pid, td->td_name); 476 SDT_PROBE0(proc, , , lwp__exit); 477 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 478 479 #ifdef AUDIT 480 AUDIT_SYSCALL_EXIT(0, td); 481 #endif 482 /* 483 * drop FPU & debug register state storage, or any other 484 * architecture specific resources that 485 * would not be on a new untouched process. 486 */ 487 cpu_thread_exit(td); 488 489 /* 490 * The last thread is left attached to the process 491 * So that the whole bundle gets recycled. Skip 492 * all this stuff if we never had threads. 493 * EXIT clears all sign of other threads when 494 * it goes to single threading, so the last thread always 495 * takes the short path. 496 */ 497 if (p->p_flag & P_HADTHREADS) { 498 if (p->p_numthreads > 1) { 499 atomic_add_int(&td->td_proc->p_exitthreads, 1); 500 thread_unlink(td); 501 td2 = FIRST_THREAD_IN_PROC(p); 502 sched_exit_thread(td2, td); 503 504 /* 505 * The test below is NOT true if we are the 506 * sole exiting thread. P_STOPPED_SINGLE is unset 507 * in exit1() after it is the only survivor. 508 */ 509 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 510 if (p->p_numthreads == p->p_suspcount) { 511 thread_lock(p->p_singlethread); 512 wakeup_swapper = thread_unsuspend_one( 513 p->p_singlethread, p, false); 514 thread_unlock(p->p_singlethread); 515 if (wakeup_swapper) 516 kick_proc0(); 517 } 518 } 519 520 PCPU_SET(deadthread, td); 521 } else { 522 /* 523 * The last thread is exiting.. but not through exit() 524 */ 525 panic ("thread_exit: Last thread exiting on its own"); 526 } 527 } 528 #ifdef HWPMC_HOOKS 529 /* 530 * If this thread is part of a process that is being tracked by hwpmc(4), 531 * inform the module of the thread's impending exit. 532 */ 533 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 534 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 535 #endif 536 PROC_UNLOCK(p); 537 PROC_STATLOCK(p); 538 thread_lock(td); 539 PROC_SUNLOCK(p); 540 541 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 542 new_switchtime = cpu_ticks(); 543 runtime = new_switchtime - PCPU_GET(switchtime); 544 td->td_runtime += runtime; 545 td->td_incruntime += runtime; 546 PCPU_SET(switchtime, new_switchtime); 547 PCPU_SET(switchticks, ticks); 548 PCPU_INC(cnt.v_swtch); 549 550 /* Save our resource usage in our process. */ 551 td->td_ru.ru_nvcsw++; 552 ruxagg(p, td); 553 rucollect(&p->p_ru, &td->td_ru); 554 PROC_STATUNLOCK(p); 555 556 td->td_state = TDS_INACTIVE; 557 #ifdef WITNESS 558 witness_thread_exit(td); 559 #endif 560 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 561 sched_throw(td); 562 panic("I'm a teapot!"); 563 /* NOTREACHED */ 564 } 565 566 /* 567 * Do any thread specific cleanups that may be needed in wait() 568 * called with Giant, proc and schedlock not held. 569 */ 570 void 571 thread_wait(struct proc *p) 572 { 573 struct thread *td; 574 575 mtx_assert(&Giant, MA_NOTOWNED); 576 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()")); 577 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking")); 578 td = FIRST_THREAD_IN_PROC(p); 579 /* Lock the last thread so we spin until it exits cpu_throw(). */ 580 thread_lock(td); 581 thread_unlock(td); 582 lock_profile_thread_exit(td); 583 cpuset_rel(td->td_cpuset); 584 td->td_cpuset = NULL; 585 cpu_thread_clean(td); 586 thread_cow_free(td); 587 callout_drain(&td->td_slpcallout); 588 thread_reap(); /* check for zombie threads etc. */ 589 } 590 591 /* 592 * Link a thread to a process. 593 * set up anything that needs to be initialized for it to 594 * be used by the process. 595 */ 596 void 597 thread_link(struct thread *td, struct proc *p) 598 { 599 600 /* 601 * XXX This can't be enabled because it's called for proc0 before 602 * its lock has been created. 603 * PROC_LOCK_ASSERT(p, MA_OWNED); 604 */ 605 td->td_state = TDS_INACTIVE; 606 td->td_proc = p; 607 td->td_flags = TDF_INMEM; 608 609 LIST_INIT(&td->td_contested); 610 LIST_INIT(&td->td_lprof[0]); 611 LIST_INIT(&td->td_lprof[1]); 612 sigqueue_init(&td->td_sigqueue, p); 613 callout_init(&td->td_slpcallout, 1); 614 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist); 615 p->p_numthreads++; 616 } 617 618 /* 619 * Called from: 620 * thread_exit() 621 */ 622 void 623 thread_unlink(struct thread *td) 624 { 625 struct proc *p = td->td_proc; 626 627 PROC_LOCK_ASSERT(p, MA_OWNED); 628 TAILQ_REMOVE(&p->p_threads, td, td_plist); 629 p->p_numthreads--; 630 /* could clear a few other things here */ 631 /* Must NOT clear links to proc! */ 632 } 633 634 static int 635 calc_remaining(struct proc *p, int mode) 636 { 637 int remaining; 638 639 PROC_LOCK_ASSERT(p, MA_OWNED); 640 PROC_SLOCK_ASSERT(p, MA_OWNED); 641 if (mode == SINGLE_EXIT) 642 remaining = p->p_numthreads; 643 else if (mode == SINGLE_BOUNDARY) 644 remaining = p->p_numthreads - p->p_boundary_count; 645 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC) 646 remaining = p->p_numthreads - p->p_suspcount; 647 else 648 panic("calc_remaining: wrong mode %d", mode); 649 return (remaining); 650 } 651 652 static int 653 remain_for_mode(int mode) 654 { 655 656 return (mode == SINGLE_ALLPROC ? 0 : 1); 657 } 658 659 static int 660 weed_inhib(int mode, struct thread *td2, struct proc *p) 661 { 662 int wakeup_swapper; 663 664 PROC_LOCK_ASSERT(p, MA_OWNED); 665 PROC_SLOCK_ASSERT(p, MA_OWNED); 666 THREAD_LOCK_ASSERT(td2, MA_OWNED); 667 668 wakeup_swapper = 0; 669 switch (mode) { 670 case SINGLE_EXIT: 671 if (TD_IS_SUSPENDED(td2)) 672 wakeup_swapper |= thread_unsuspend_one(td2, p, true); 673 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 674 wakeup_swapper |= sleepq_abort(td2, EINTR); 675 break; 676 case SINGLE_BOUNDARY: 677 case SINGLE_NO_EXIT: 678 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0) 679 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 680 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 681 wakeup_swapper |= sleepq_abort(td2, ERESTART); 682 break; 683 case SINGLE_ALLPROC: 684 /* 685 * ALLPROC suspend tries to avoid spurious EINTR for 686 * threads sleeping interruptable, by suspending the 687 * thread directly, similarly to sig_suspend_threads(). 688 * Since such sleep is not performed at the user 689 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP 690 * is used to avoid immediate un-suspend. 691 */ 692 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY | 693 TDF_ALLPROCSUSP)) == 0) 694 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 695 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) { 696 if ((td2->td_flags & TDF_SBDRY) == 0) { 697 thread_suspend_one(td2); 698 td2->td_flags |= TDF_ALLPROCSUSP; 699 } else { 700 wakeup_swapper |= sleepq_abort(td2, ERESTART); 701 } 702 } 703 break; 704 } 705 return (wakeup_swapper); 706 } 707 708 /* 709 * Enforce single-threading. 710 * 711 * Returns 1 if the caller must abort (another thread is waiting to 712 * exit the process or similar). Process is locked! 713 * Returns 0 when you are successfully the only thread running. 714 * A process has successfully single threaded in the suspend mode when 715 * There are no threads in user mode. Threads in the kernel must be 716 * allowed to continue until they get to the user boundary. They may even 717 * copy out their return values and data before suspending. They may however be 718 * accelerated in reaching the user boundary as we will wake up 719 * any sleeping threads that are interruptable. (PCATCH). 720 */ 721 int 722 thread_single(struct proc *p, int mode) 723 { 724 struct thread *td; 725 struct thread *td2; 726 int remaining, wakeup_swapper; 727 728 td = curthread; 729 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 730 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 731 ("invalid mode %d", mode)); 732 /* 733 * If allowing non-ALLPROC singlethreading for non-curproc 734 * callers, calc_remaining() and remain_for_mode() should be 735 * adjusted to also account for td->td_proc != p. For now 736 * this is not implemented because it is not used. 737 */ 738 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) || 739 (mode != SINGLE_ALLPROC && td->td_proc == p), 740 ("mode %d proc %p curproc %p", mode, p, td->td_proc)); 741 mtx_assert(&Giant, MA_NOTOWNED); 742 PROC_LOCK_ASSERT(p, MA_OWNED); 743 744 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC) 745 return (0); 746 747 /* Is someone already single threading? */ 748 if (p->p_singlethread != NULL && p->p_singlethread != td) 749 return (1); 750 751 if (mode == SINGLE_EXIT) { 752 p->p_flag |= P_SINGLE_EXIT; 753 p->p_flag &= ~P_SINGLE_BOUNDARY; 754 } else { 755 p->p_flag &= ~P_SINGLE_EXIT; 756 if (mode == SINGLE_BOUNDARY) 757 p->p_flag |= P_SINGLE_BOUNDARY; 758 else 759 p->p_flag &= ~P_SINGLE_BOUNDARY; 760 } 761 if (mode == SINGLE_ALLPROC) 762 p->p_flag |= P_TOTAL_STOP; 763 p->p_flag |= P_STOPPED_SINGLE; 764 PROC_SLOCK(p); 765 p->p_singlethread = td; 766 remaining = calc_remaining(p, mode); 767 while (remaining != remain_for_mode(mode)) { 768 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 769 goto stopme; 770 wakeup_swapper = 0; 771 FOREACH_THREAD_IN_PROC(p, td2) { 772 if (td2 == td) 773 continue; 774 thread_lock(td2); 775 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 776 if (TD_IS_INHIBITED(td2)) { 777 wakeup_swapper |= weed_inhib(mode, td2, p); 778 #ifdef SMP 779 } else if (TD_IS_RUNNING(td2) && td != td2) { 780 forward_signal(td2); 781 #endif 782 } 783 thread_unlock(td2); 784 } 785 if (wakeup_swapper) 786 kick_proc0(); 787 remaining = calc_remaining(p, mode); 788 789 /* 790 * Maybe we suspended some threads.. was it enough? 791 */ 792 if (remaining == remain_for_mode(mode)) 793 break; 794 795 stopme: 796 /* 797 * Wake us up when everyone else has suspended. 798 * In the mean time we suspend as well. 799 */ 800 thread_suspend_switch(td, p); 801 remaining = calc_remaining(p, mode); 802 } 803 if (mode == SINGLE_EXIT) { 804 /* 805 * Convert the process to an unthreaded process. The 806 * SINGLE_EXIT is called by exit1() or execve(), in 807 * both cases other threads must be retired. 808 */ 809 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 810 p->p_singlethread = NULL; 811 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 812 813 /* 814 * Wait for any remaining threads to exit cpu_throw(). 815 */ 816 while (p->p_exitthreads != 0) { 817 PROC_SUNLOCK(p); 818 PROC_UNLOCK(p); 819 sched_relinquish(td); 820 PROC_LOCK(p); 821 PROC_SLOCK(p); 822 } 823 } else if (mode == SINGLE_BOUNDARY) { 824 /* 825 * Wait until all suspended threads are removed from 826 * the processors. The thread_suspend_check() 827 * increments p_boundary_count while it is still 828 * running, which makes it possible for the execve() 829 * to destroy vmspace while our other threads are 830 * still using the address space. 831 * 832 * We lock the thread, which is only allowed to 833 * succeed after context switch code finished using 834 * the address space. 835 */ 836 FOREACH_THREAD_IN_PROC(p, td2) { 837 if (td2 == td) 838 continue; 839 thread_lock(td2); 840 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0, 841 ("td %p not on boundary", td2)); 842 KASSERT(TD_IS_SUSPENDED(td2), 843 ("td %p is not suspended", td2)); 844 thread_unlock(td2); 845 } 846 } 847 PROC_SUNLOCK(p); 848 return (0); 849 } 850 851 bool 852 thread_suspend_check_needed(void) 853 { 854 struct proc *p; 855 struct thread *td; 856 857 td = curthread; 858 p = td->td_proc; 859 PROC_LOCK_ASSERT(p, MA_OWNED); 860 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 && 861 (td->td_dbgflags & TDB_SUSPEND) != 0)); 862 } 863 864 /* 865 * Called in from locations that can safely check to see 866 * whether we have to suspend or at least throttle for a 867 * single-thread event (e.g. fork). 868 * 869 * Such locations include userret(). 870 * If the "return_instead" argument is non zero, the thread must be able to 871 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 872 * 873 * The 'return_instead' argument tells the function if it may do a 874 * thread_exit() or suspend, or whether the caller must abort and back 875 * out instead. 876 * 877 * If the thread that set the single_threading request has set the 878 * P_SINGLE_EXIT bit in the process flags then this call will never return 879 * if 'return_instead' is false, but will exit. 880 * 881 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 882 *---------------+--------------------+--------------------- 883 * 0 | returns 0 | returns 0 or 1 884 * | when ST ends | immediately 885 *---------------+--------------------+--------------------- 886 * 1 | thread exits | returns 1 887 * | | immediately 888 * 0 = thread_exit() or suspension ok, 889 * other = return error instead of stopping the thread. 890 * 891 * While a full suspension is under effect, even a single threading 892 * thread would be suspended if it made this call (but it shouldn't). 893 * This call should only be made from places where 894 * thread_exit() would be safe as that may be the outcome unless 895 * return_instead is set. 896 */ 897 int 898 thread_suspend_check(int return_instead) 899 { 900 struct thread *td; 901 struct proc *p; 902 int wakeup_swapper; 903 904 td = curthread; 905 p = td->td_proc; 906 mtx_assert(&Giant, MA_NOTOWNED); 907 PROC_LOCK_ASSERT(p, MA_OWNED); 908 while (thread_suspend_check_needed()) { 909 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 910 KASSERT(p->p_singlethread != NULL, 911 ("singlethread not set")); 912 /* 913 * The only suspension in action is a 914 * single-threading. Single threader need not stop. 915 * It is safe to access p->p_singlethread unlocked 916 * because it can only be set to our address by us. 917 */ 918 if (p->p_singlethread == td) 919 return (0); /* Exempt from stopping. */ 920 } 921 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 922 return (EINTR); 923 924 /* Should we goto user boundary if we didn't come from there? */ 925 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 926 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 927 return (ERESTART); 928 929 /* 930 * Ignore suspend requests if they are deferred. 931 */ 932 if ((td->td_flags & TDF_SBDRY) != 0) { 933 KASSERT(return_instead, 934 ("TDF_SBDRY set for unsafe thread_suspend_check")); 935 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) != 936 (TDF_SEINTR | TDF_SERESTART), 937 ("both TDF_SEINTR and TDF_SERESTART")); 938 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0); 939 } 940 941 /* 942 * If the process is waiting for us to exit, 943 * this thread should just suicide. 944 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 945 */ 946 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 947 PROC_UNLOCK(p); 948 949 /* 950 * Allow Linux emulation layer to do some work 951 * before thread suicide. 952 */ 953 if (__predict_false(p->p_sysent->sv_thread_detach != NULL)) 954 (p->p_sysent->sv_thread_detach)(td); 955 umtx_thread_exit(td); 956 kern_thr_exit(td); 957 panic("stopped thread did not exit"); 958 } 959 960 PROC_SLOCK(p); 961 thread_stopped(p); 962 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 963 if (p->p_numthreads == p->p_suspcount + 1) { 964 thread_lock(p->p_singlethread); 965 wakeup_swapper = thread_unsuspend_one( 966 p->p_singlethread, p, false); 967 thread_unlock(p->p_singlethread); 968 if (wakeup_swapper) 969 kick_proc0(); 970 } 971 } 972 PROC_UNLOCK(p); 973 thread_lock(td); 974 /* 975 * When a thread suspends, it just 976 * gets taken off all queues. 977 */ 978 thread_suspend_one(td); 979 if (return_instead == 0) { 980 p->p_boundary_count++; 981 td->td_flags |= TDF_BOUNDARY; 982 } 983 PROC_SUNLOCK(p); 984 mi_switch(SW_INVOL | SWT_SUSPEND, NULL); 985 thread_unlock(td); 986 PROC_LOCK(p); 987 } 988 return (0); 989 } 990 991 void 992 thread_suspend_switch(struct thread *td, struct proc *p) 993 { 994 995 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 996 PROC_LOCK_ASSERT(p, MA_OWNED); 997 PROC_SLOCK_ASSERT(p, MA_OWNED); 998 /* 999 * We implement thread_suspend_one in stages here to avoid 1000 * dropping the proc lock while the thread lock is owned. 1001 */ 1002 if (p == td->td_proc) { 1003 thread_stopped(p); 1004 p->p_suspcount++; 1005 } 1006 PROC_UNLOCK(p); 1007 thread_lock(td); 1008 td->td_flags &= ~TDF_NEEDSUSPCHK; 1009 TD_SET_SUSPENDED(td); 1010 sched_sleep(td, 0); 1011 PROC_SUNLOCK(p); 1012 DROP_GIANT(); 1013 mi_switch(SW_VOL | SWT_SUSPEND, NULL); 1014 thread_unlock(td); 1015 PICKUP_GIANT(); 1016 PROC_LOCK(p); 1017 PROC_SLOCK(p); 1018 } 1019 1020 void 1021 thread_suspend_one(struct thread *td) 1022 { 1023 struct proc *p; 1024 1025 p = td->td_proc; 1026 PROC_SLOCK_ASSERT(p, MA_OWNED); 1027 THREAD_LOCK_ASSERT(td, MA_OWNED); 1028 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1029 p->p_suspcount++; 1030 td->td_flags &= ~TDF_NEEDSUSPCHK; 1031 TD_SET_SUSPENDED(td); 1032 sched_sleep(td, 0); 1033 } 1034 1035 static int 1036 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary) 1037 { 1038 1039 THREAD_LOCK_ASSERT(td, MA_OWNED); 1040 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 1041 TD_CLR_SUSPENDED(td); 1042 td->td_flags &= ~TDF_ALLPROCSUSP; 1043 if (td->td_proc == p) { 1044 PROC_SLOCK_ASSERT(p, MA_OWNED); 1045 p->p_suspcount--; 1046 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) { 1047 td->td_flags &= ~TDF_BOUNDARY; 1048 p->p_boundary_count--; 1049 } 1050 } 1051 return (setrunnable(td)); 1052 } 1053 1054 /* 1055 * Allow all threads blocked by single threading to continue running. 1056 */ 1057 void 1058 thread_unsuspend(struct proc *p) 1059 { 1060 struct thread *td; 1061 int wakeup_swapper; 1062 1063 PROC_LOCK_ASSERT(p, MA_OWNED); 1064 PROC_SLOCK_ASSERT(p, MA_OWNED); 1065 wakeup_swapper = 0; 1066 if (!P_SHOULDSTOP(p)) { 1067 FOREACH_THREAD_IN_PROC(p, td) { 1068 thread_lock(td); 1069 if (TD_IS_SUSPENDED(td)) { 1070 wakeup_swapper |= thread_unsuspend_one(td, p, 1071 true); 1072 } 1073 thread_unlock(td); 1074 } 1075 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1076 p->p_numthreads == p->p_suspcount) { 1077 /* 1078 * Stopping everything also did the job for the single 1079 * threading request. Now we've downgraded to single-threaded, 1080 * let it continue. 1081 */ 1082 if (p->p_singlethread->td_proc == p) { 1083 thread_lock(p->p_singlethread); 1084 wakeup_swapper = thread_unsuspend_one( 1085 p->p_singlethread, p, false); 1086 thread_unlock(p->p_singlethread); 1087 } 1088 } 1089 if (wakeup_swapper) 1090 kick_proc0(); 1091 } 1092 1093 /* 1094 * End the single threading mode.. 1095 */ 1096 void 1097 thread_single_end(struct proc *p, int mode) 1098 { 1099 struct thread *td; 1100 int wakeup_swapper; 1101 1102 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1103 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1104 ("invalid mode %d", mode)); 1105 PROC_LOCK_ASSERT(p, MA_OWNED); 1106 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) || 1107 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0), 1108 ("mode %d does not match P_TOTAL_STOP", mode)); 1109 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread, 1110 ("thread_single_end from other thread %p %p", 1111 curthread, p->p_singlethread)); 1112 KASSERT(mode != SINGLE_BOUNDARY || 1113 (p->p_flag & P_SINGLE_BOUNDARY) != 0, 1114 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag)); 1115 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY | 1116 P_TOTAL_STOP); 1117 PROC_SLOCK(p); 1118 p->p_singlethread = NULL; 1119 wakeup_swapper = 0; 1120 /* 1121 * If there are other threads they may now run, 1122 * unless of course there is a blanket 'stop order' 1123 * on the process. The single threader must be allowed 1124 * to continue however as this is a bad place to stop. 1125 */ 1126 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) { 1127 FOREACH_THREAD_IN_PROC(p, td) { 1128 thread_lock(td); 1129 if (TD_IS_SUSPENDED(td)) { 1130 wakeup_swapper |= thread_unsuspend_one(td, p, 1131 mode == SINGLE_BOUNDARY); 1132 } 1133 thread_unlock(td); 1134 } 1135 } 1136 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0, 1137 ("inconsistent boundary count %d", p->p_boundary_count)); 1138 PROC_SUNLOCK(p); 1139 if (wakeup_swapper) 1140 kick_proc0(); 1141 } 1142 1143 struct thread * 1144 thread_find(struct proc *p, lwpid_t tid) 1145 { 1146 struct thread *td; 1147 1148 PROC_LOCK_ASSERT(p, MA_OWNED); 1149 FOREACH_THREAD_IN_PROC(p, td) { 1150 if (td->td_tid == tid) 1151 break; 1152 } 1153 return (td); 1154 } 1155 1156 /* Locate a thread by number; return with proc lock held. */ 1157 struct thread * 1158 tdfind(lwpid_t tid, pid_t pid) 1159 { 1160 #define RUN_THRESH 16 1161 struct thread *td; 1162 int run = 0; 1163 1164 rw_rlock(&tidhash_lock); 1165 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1166 if (td->td_tid == tid) { 1167 if (pid != -1 && td->td_proc->p_pid != pid) { 1168 td = NULL; 1169 break; 1170 } 1171 PROC_LOCK(td->td_proc); 1172 if (td->td_proc->p_state == PRS_NEW) { 1173 PROC_UNLOCK(td->td_proc); 1174 td = NULL; 1175 break; 1176 } 1177 if (run > RUN_THRESH) { 1178 if (rw_try_upgrade(&tidhash_lock)) { 1179 LIST_REMOVE(td, td_hash); 1180 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1181 td, td_hash); 1182 rw_wunlock(&tidhash_lock); 1183 return (td); 1184 } 1185 } 1186 break; 1187 } 1188 run++; 1189 } 1190 rw_runlock(&tidhash_lock); 1191 return (td); 1192 } 1193 1194 void 1195 tidhash_add(struct thread *td) 1196 { 1197 rw_wlock(&tidhash_lock); 1198 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1199 rw_wunlock(&tidhash_lock); 1200 } 1201 1202 void 1203 tidhash_remove(struct thread *td) 1204 { 1205 rw_wlock(&tidhash_lock); 1206 LIST_REMOVE(td, td_hash); 1207 rw_wunlock(&tidhash_lock); 1208 } 1209