1/* $OpenBSD: kern_fork.c,v 1.260 2024/06/03 12:48:25 claudio Exp $ */ 2/* $NetBSD: kern_fork.c,v 1.29 1996/02/09 18:59:34 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_fork.c 8.6 (Berkeley) 4/8/94 38 */ 39 40#include <sys/param.h> 41#include <sys/systm.h> 42#include <sys/filedesc.h> 43#include <sys/malloc.h> 44#include <sys/mount.h> 45#include <sys/proc.h> 46#include <sys/resourcevar.h> 47#include <sys/signalvar.h> 48#include <sys/vnode.h> 49#include <sys/vmmeter.h> 50#include <sys/acct.h> 51#include <sys/ktrace.h> 52#include <sys/sched.h> 53#include <sys/smr.h> 54#include <sys/sysctl.h> 55#include <sys/pool.h> 56#include <sys/mman.h> 57#include <sys/ptrace.h> 58#include <sys/atomic.h> 59#include <sys/unistd.h> 60#include <sys/tracepoint.h> 61 62#include <sys/syscallargs.h> 63 64#include <uvm/uvm.h> 65#include <machine/tcb.h> 66 67int nprocesses = 1; /* process 0 */ 68int nthreads = 1; /* proc 0 */ 69struct forkstat forkstat; 70 71void fork_return(void *); 72pid_t alloctid(void); 73pid_t allocpid(void); 74int ispidtaken(pid_t); 75 76void unveil_copy(struct process *parent, struct process *child); 77 78struct proc *thread_new(struct proc *_parent, vaddr_t _uaddr); 79struct process *process_new(struct proc *, struct process *, int); 80int fork_check_maxthread(uid_t _uid); 81 82void 83fork_return(void *arg) 84{ 85 struct proc *p = (struct proc *)arg; 86 87 if (p->p_p->ps_flags & PS_TRACED) 88 psignal(p, SIGTRAP); 89 90 child_return(p); 91} 92 93int 94sys_fork(struct proc *p, void *v, register_t *retval) 95{ 96 void (*func)(void *) = child_return; 97 int flags; 98 99 flags = FORK_FORK; 100 if (p->p_p->ps_ptmask & PTRACE_FORK) { 101 flags |= FORK_PTRACE; 102 func = fork_return; 103 } 104 return fork1(p, flags, func, NULL, retval, NULL); 105} 106 107int 108sys_vfork(struct proc *p, void *v, register_t *retval) 109{ 110 return fork1(p, FORK_VFORK|FORK_PPWAIT, child_return, NULL, 111 retval, NULL); 112} 113 114int 115sys___tfork(struct proc *p, void *v, register_t *retval) 116{ 117 struct sys___tfork_args /* { 118 syscallarg(const struct __tfork) *param; 119 syscallarg(size_t) psize; 120 } */ *uap = v; 121 size_t psize = SCARG(uap, psize); 122 struct __tfork param = { 0 }; 123 int error; 124 125 if (psize == 0 || psize > sizeof(param)) 126 return EINVAL; 127 if ((error = copyin(SCARG(uap, param), ¶m, psize))) 128 return error; 129#ifdef KTRACE 130 if (KTRPOINT(p, KTR_STRUCT)) 131 ktrstruct(p, "tfork", ¶m, sizeof(param)); 132#endif 133#ifdef TCB_INVALID 134 if (TCB_INVALID(param.tf_tcb)) 135 return EINVAL; 136#endif /* TCB_INVALID */ 137 138 return thread_fork(p, param.tf_stack, param.tf_tcb, param.tf_tid, 139 retval); 140} 141 142/* 143 * Allocate and initialize a thread (proc) structure, given the parent thread. 144 */ 145struct proc * 146thread_new(struct proc *parent, vaddr_t uaddr) 147{ 148 struct proc *p; 149 150 p = pool_get(&proc_pool, PR_WAITOK); 151 p->p_stat = SIDL; /* protect against others */ 152 p->p_runpri = 0; 153 p->p_flag = 0; 154 155 /* 156 * Make a proc table entry for the new process. 157 * Start by zeroing the section of proc that is zero-initialized, 158 * then copy the section that is copied directly from the parent. 159 */ 160 memset(&p->p_startzero, 0, 161 (caddr_t)&p->p_endzero - (caddr_t)&p->p_startzero); 162 memcpy(&p->p_startcopy, &parent->p_startcopy, 163 (caddr_t)&p->p_endcopy - (caddr_t)&p->p_startcopy); 164 crhold(p->p_ucred); 165 p->p_addr = (struct user *)uaddr; 166 167 /* 168 * Initialize the timeouts. 169 */ 170 timeout_set(&p->p_sleep_to, endtsleep, p); 171 172 return p; 173} 174 175/* 176 * Initialize common bits of a process structure, given the initial thread. 177 */ 178void 179process_initialize(struct process *pr, struct proc *p) 180{ 181 /* initialize the thread links */ 182 pr->ps_mainproc = p; 183 TAILQ_INIT(&pr->ps_threads); 184 TAILQ_INSERT_TAIL(&pr->ps_threads, p, p_thr_link); 185 pr->ps_threadcnt = 1; 186 p->p_p = pr; 187 188 /* give the process the same creds as the initial thread */ 189 pr->ps_ucred = p->p_ucred; 190 crhold(pr->ps_ucred); 191 /* new thread and new process */ 192 KASSERT(p->p_ucred->cr_refcnt.r_refs >= 2); 193 194 LIST_INIT(&pr->ps_children); 195 LIST_INIT(&pr->ps_orphans); 196 LIST_INIT(&pr->ps_ftlist); 197 LIST_INIT(&pr->ps_sigiolst); 198 TAILQ_INIT(&pr->ps_tslpqueue); 199 200 rw_init(&pr->ps_lock, "pslock"); 201 mtx_init(&pr->ps_mtx, IPL_HIGH); 202 203 timeout_set_flags(&pr->ps_realit_to, realitexpire, pr, 204 KCLOCK_UPTIME, 0); 205 timeout_set(&pr->ps_rucheck_to, rucheck, pr); 206} 207 208 209/* 210 * Allocate and initialize a new process. 211 */ 212struct process * 213process_new(struct proc *p, struct process *parent, int flags) 214{ 215 struct process *pr; 216 217 pr = pool_get(&process_pool, PR_WAITOK); 218 219 /* 220 * Make a process structure for the new process. 221 * Start by zeroing the section of proc that is zero-initialized, 222 * then copy the section that is copied directly from the parent. 223 */ 224 memset(&pr->ps_startzero, 0, 225 (caddr_t)&pr->ps_endzero - (caddr_t)&pr->ps_startzero); 226 memcpy(&pr->ps_startcopy, &parent->ps_startcopy, 227 (caddr_t)&pr->ps_endcopy - (caddr_t)&pr->ps_startcopy); 228 229 process_initialize(pr, p); 230 pr->ps_pid = allocpid(); 231 lim_fork(parent, pr); 232 233 /* post-copy fixups */ 234 pr->ps_pptr = parent; 235 pr->ps_ppid = parent->ps_pid; 236 237 /* bump references to the text vnode (for sysctl) */ 238 pr->ps_textvp = parent->ps_textvp; 239 if (pr->ps_textvp) 240 vref(pr->ps_textvp); 241 242 /* copy unveil if unveil is active */ 243 unveil_copy(parent, pr); 244 245 pr->ps_flags = parent->ps_flags & 246 (PS_SUGID | PS_SUGIDEXEC | PS_PLEDGE | PS_EXECPLEDGE | 247 PS_WXNEEDED | PS_CHROOT); 248 if (parent->ps_session->s_ttyvp != NULL) 249 pr->ps_flags |= parent->ps_flags & PS_CONTROLT; 250 251 if (parent->ps_pin.pn_pins) { 252 pr->ps_pin.pn_pins = mallocarray(parent->ps_pin.pn_npins, 253 sizeof(u_int), M_PINSYSCALL, M_WAITOK); 254 memcpy(pr->ps_pin.pn_pins, parent->ps_pin.pn_pins, 255 parent->ps_pin.pn_npins * sizeof(u_int)); 256 pr->ps_flags |= PS_PIN; 257 } 258 if (parent->ps_libcpin.pn_pins) { 259 pr->ps_libcpin.pn_pins = mallocarray(parent->ps_libcpin.pn_npins, 260 sizeof(u_int), M_PINSYSCALL, M_WAITOK); 261 memcpy(pr->ps_libcpin.pn_pins, parent->ps_libcpin.pn_pins, 262 parent->ps_libcpin.pn_npins * sizeof(u_int)); 263 pr->ps_flags |= PS_LIBCPIN; 264 } 265 266 /* 267 * Duplicate sub-structures as needed. 268 * Increase reference counts on shared objects. 269 */ 270 if (flags & FORK_SHAREFILES) 271 pr->ps_fd = fdshare(parent); 272 else 273 pr->ps_fd = fdcopy(parent); 274 pr->ps_sigacts = sigactsinit(parent); 275 if (flags & FORK_SHAREVM) 276 pr->ps_vmspace = uvmspace_share(parent); 277 else 278 pr->ps_vmspace = uvmspace_fork(parent); 279 280 if (parent->ps_flags & PS_PROFIL) 281 startprofclock(pr); 282 if (flags & FORK_PTRACE) 283 pr->ps_flags |= parent->ps_flags & PS_TRACED; 284 if (flags & FORK_NOZOMBIE) 285 pr->ps_flags |= PS_NOZOMBIE; 286 if (flags & FORK_SYSTEM) 287 pr->ps_flags |= PS_SYSTEM; 288 289 /* mark as embryo to protect against others */ 290 pr->ps_flags |= PS_EMBRYO; 291 292 /* Force visibility of all of the above changes */ 293 membar_producer(); 294 295 /* it's sufficiently inited to be globally visible */ 296 LIST_INSERT_HEAD(&allprocess, pr, ps_list); 297 298 return pr; 299} 300 301/* print the 'table full' message once per 10 seconds */ 302struct timeval fork_tfmrate = { 10, 0 }; 303 304int 305fork_check_maxthread(uid_t uid) 306{ 307 /* 308 * Although process entries are dynamically created, we still keep 309 * a global limit on the maximum number we will create. We reserve 310 * the last 5 processes to root. The variable nprocesses is the 311 * current number of processes, maxprocess is the limit. Similar 312 * rules for threads (struct proc): we reserve the last 5 to root; 313 * the variable nthreads is the current number of procs, maxthread is 314 * the limit. 315 */ 316 if ((nthreads >= maxthread - 5 && uid != 0) || nthreads >= maxthread) { 317 static struct timeval lasttfm; 318 319 if (ratecheck(&lasttfm, &fork_tfmrate)) 320 tablefull("thread"); 321 return EAGAIN; 322 } 323 nthreads++; 324 325 return 0; 326} 327 328static inline void 329fork_thread_start(struct proc *p, struct proc *parent, int flags) 330{ 331 struct cpu_info *ci; 332 333 SCHED_LOCK(); 334 ci = sched_choosecpu_fork(parent, flags); 335 TRACEPOINT(sched, fork, p->p_tid + THREAD_PID_OFFSET, 336 p->p_p->ps_pid, CPU_INFO_UNIT(ci)); 337 setrunqueue(ci, p, p->p_usrpri); 338 SCHED_UNLOCK(); 339} 340 341int 342fork1(struct proc *curp, int flags, void (*func)(void *), void *arg, 343 register_t *retval, struct proc **rnewprocp) 344{ 345 struct process *curpr = curp->p_p; 346 struct process *pr; 347 struct proc *p; 348 uid_t uid = curp->p_ucred->cr_ruid; 349 struct vmspace *vm; 350 int count; 351 vaddr_t uaddr; 352 int error; 353 struct ptrace_state *newptstat = NULL; 354 355 KASSERT((flags & ~(FORK_FORK | FORK_VFORK | FORK_PPWAIT | FORK_PTRACE 356 | FORK_IDLE | FORK_SHAREVM | FORK_SHAREFILES | FORK_NOZOMBIE 357 | FORK_SYSTEM)) == 0); 358 KASSERT(func != NULL); 359 360 if ((error = fork_check_maxthread(uid))) 361 return error; 362 363 if ((nprocesses >= maxprocess - 5 && uid != 0) || 364 nprocesses >= maxprocess) { 365 static struct timeval lasttfm; 366 367 if (ratecheck(&lasttfm, &fork_tfmrate)) 368 tablefull("process"); 369 nthreads--; 370 return EAGAIN; 371 } 372 nprocesses++; 373 374 /* 375 * Increment the count of processes running with this uid. 376 * Don't allow a nonprivileged user to exceed their current limit. 377 */ 378 count = chgproccnt(uid, 1); 379 if (uid != 0 && count > lim_cur(RLIMIT_NPROC)) { 380 (void)chgproccnt(uid, -1); 381 nprocesses--; 382 nthreads--; 383 return EAGAIN; 384 } 385 386 uaddr = uvm_uarea_alloc(); 387 if (uaddr == 0) { 388 (void)chgproccnt(uid, -1); 389 nprocesses--; 390 nthreads--; 391 return (ENOMEM); 392 } 393 394 /* 395 * From now on, we're committed to the fork and cannot fail. 396 */ 397 p = thread_new(curp, uaddr); 398 pr = process_new(p, curpr, flags); 399 400 p->p_fd = pr->ps_fd; 401 p->p_vmspace = pr->ps_vmspace; 402 if (pr->ps_flags & PS_SYSTEM) 403 atomic_setbits_int(&p->p_flag, P_SYSTEM); 404 405 if (flags & FORK_PPWAIT) { 406 atomic_setbits_int(&pr->ps_flags, PS_PPWAIT); 407 atomic_setbits_int(&curpr->ps_flags, PS_ISPWAIT); 408 } 409 410#ifdef KTRACE 411 /* 412 * Copy traceflag and tracefile if enabled. 413 * If not inherited, these were zeroed above. 414 */ 415 if (curpr->ps_traceflag & KTRFAC_INHERIT) 416 ktrsettrace(pr, curpr->ps_traceflag, curpr->ps_tracevp, 417 curpr->ps_tracecred); 418#endif 419 420 /* 421 * Finish creating the child thread. cpu_fork() will copy 422 * and update the pcb and make the child ready to run. If 423 * this is a normal user fork, the child will exit directly 424 * to user mode via child_return() on its first time slice 425 * and will not return here. If this is a kernel thread, 426 * the specified entry point will be executed. 427 */ 428 cpu_fork(curp, p, NULL, NULL, func, arg ? arg : p); 429 430 vm = pr->ps_vmspace; 431 432 if (flags & FORK_FORK) { 433 forkstat.cntfork++; 434 forkstat.sizfork += vm->vm_dsize + vm->vm_ssize; 435 } else if (flags & FORK_VFORK) { 436 forkstat.cntvfork++; 437 forkstat.sizvfork += vm->vm_dsize + vm->vm_ssize; 438 } else { 439 forkstat.cntkthread++; 440 } 441 442 if (pr->ps_flags & PS_TRACED && flags & FORK_FORK) 443 newptstat = malloc(sizeof(*newptstat), M_SUBPROC, M_WAITOK); 444 445 p->p_tid = alloctid(); 446 447 LIST_INSERT_HEAD(&allproc, p, p_list); 448 LIST_INSERT_HEAD(TIDHASH(p->p_tid), p, p_hash); 449 LIST_INSERT_HEAD(PIDHASH(pr->ps_pid), pr, ps_hash); 450 LIST_INSERT_AFTER(curpr, pr, ps_pglist); 451 LIST_INSERT_HEAD(&curpr->ps_children, pr, ps_sibling); 452 453 if (pr->ps_flags & PS_TRACED) { 454 pr->ps_oppid = curpr->ps_pid; 455 process_reparent(pr, curpr->ps_pptr); 456 457 /* 458 * Set ptrace status. 459 */ 460 if (newptstat != NULL) { 461 pr->ps_ptstat = newptstat; 462 newptstat = NULL; 463 curpr->ps_ptstat->pe_report_event = PTRACE_FORK; 464 pr->ps_ptstat->pe_report_event = PTRACE_FORK; 465 curpr->ps_ptstat->pe_other_pid = pr->ps_pid; 466 pr->ps_ptstat->pe_other_pid = curpr->ps_pid; 467 } 468 } 469 470 /* 471 * For new processes, set accounting bits and mark as complete. 472 */ 473 nanouptime(&pr->ps_start); 474 pr->ps_acflag = AFORK; 475 atomic_clearbits_int(&pr->ps_flags, PS_EMBRYO); 476 477 if ((flags & FORK_IDLE) == 0) 478 fork_thread_start(p, curp, flags); 479 else 480 p->p_cpu = arg; 481 482 free(newptstat, M_SUBPROC, sizeof(*newptstat)); 483 484 /* 485 * Notify any interested parties about the new process. 486 */ 487 knote_locked(&curpr->ps_klist, NOTE_FORK | pr->ps_pid); 488 489 /* 490 * Update stats now that we know the fork was successful. 491 */ 492 uvmexp.forks++; 493 if (flags & FORK_PPWAIT) 494 uvmexp.forks_ppwait++; 495 if (flags & FORK_SHAREVM) 496 uvmexp.forks_sharevm++; 497 498 /* 499 * Pass a pointer to the new process to the caller. 500 */ 501 if (rnewprocp != NULL) 502 *rnewprocp = p; 503 504 /* 505 * Preserve synchronization semantics of vfork. If waiting for 506 * child to exec or exit, set PS_PPWAIT on child and PS_ISPWAIT 507 * on ourselves, and sleep on our process for the latter flag 508 * to go away. 509 * XXX Need to stop other rthreads in the parent 510 */ 511 if (flags & FORK_PPWAIT) 512 while (curpr->ps_flags & PS_ISPWAIT) 513 tsleep_nsec(curpr, PWAIT, "ppwait", INFSLP); 514 515 /* 516 * If we're tracing the child, alert the parent too. 517 */ 518 if ((flags & FORK_PTRACE) && (curpr->ps_flags & PS_TRACED)) 519 psignal(curp, SIGTRAP); 520 521 /* 522 * Return child pid to parent process 523 */ 524 if (retval != NULL) 525 *retval = pr->ps_pid; 526 return (0); 527} 528 529int 530thread_fork(struct proc *curp, void *stack, void *tcb, pid_t *tidptr, 531 register_t *retval) 532{ 533 struct process *pr = curp->p_p; 534 struct proc *p; 535 pid_t tid; 536 vaddr_t uaddr; 537 int error; 538 539 if (stack == NULL) 540 return EINVAL; 541 542 if ((error = fork_check_maxthread(curp->p_ucred->cr_ruid))) 543 return error; 544 545 uaddr = uvm_uarea_alloc(); 546 if (uaddr == 0) { 547 nthreads--; 548 return ENOMEM; 549 } 550 551 /* 552 * From now on, we're committed to the fork and cannot fail. 553 */ 554 p = thread_new(curp, uaddr); 555 atomic_setbits_int(&p->p_flag, P_THREAD); 556 sigstkinit(&p->p_sigstk); 557 memset(p->p_name, 0, sizeof p->p_name); 558 559 /* other links */ 560 p->p_p = pr; 561 562 /* local copies */ 563 p->p_fd = pr->ps_fd; 564 p->p_vmspace = pr->ps_vmspace; 565 566 /* 567 * Finish creating the child thread. cpu_fork() will copy 568 * and update the pcb and make the child ready to run. The 569 * child will exit directly to user mode via child_return() 570 * on its first time slice and will not return here. 571 */ 572 cpu_fork(curp, p, stack, tcb, child_return, p); 573 574 p->p_tid = alloctid(); 575 576 LIST_INSERT_HEAD(&allproc, p, p_list); 577 LIST_INSERT_HEAD(TIDHASH(p->p_tid), p, p_hash); 578 579 mtx_enter(&pr->ps_mtx); 580 TAILQ_INSERT_TAIL(&pr->ps_threads, p, p_thr_link); 581 pr->ps_threadcnt++; 582 583 /* 584 * if somebody else wants to take us to single threaded mode, 585 * count ourselves in. 586 */ 587 if (pr->ps_single) { 588 pr->ps_singlecnt++; 589 atomic_setbits_int(&p->p_flag, P_SUSPSINGLE); 590 } 591 mtx_leave(&pr->ps_mtx); 592 593 /* 594 * Return tid to parent thread and copy it out to userspace 595 */ 596 *retval = tid = p->p_tid + THREAD_PID_OFFSET; 597 if (tidptr != NULL) { 598 if (copyout(&tid, tidptr, sizeof(tid))) 599 psignal(curp, SIGSEGV); 600 } 601 602 fork_thread_start(p, curp, 0); 603 604 /* 605 * Update stats now that we know the fork was successful. 606 */ 607 forkstat.cnttfork++; 608 uvmexp.forks++; 609 uvmexp.forks_sharevm++; 610 611 return 0; 612} 613 614 615/* Find an unused tid */ 616pid_t 617alloctid(void) 618{ 619 pid_t tid; 620 621 do { 622 /* (0 .. TID_MASK+1] */ 623 tid = 1 + (arc4random() & TID_MASK); 624 } while (tfind(tid) != NULL); 625 626 return (tid); 627} 628 629/* 630 * Checks for current use of a pid, either as a pid or pgid. 631 */ 632pid_t oldpids[128]; 633int 634ispidtaken(pid_t pid) 635{ 636 uint32_t i; 637 638 for (i = 0; i < nitems(oldpids); i++) 639 if (pid == oldpids[i]) 640 return (1); 641 642 if (prfind(pid) != NULL) 643 return (1); 644 if (pgfind(pid) != NULL) 645 return (1); 646 if (zombiefind(pid) != NULL) 647 return (1); 648 return (0); 649} 650 651/* Find an unused pid */ 652pid_t 653allocpid(void) 654{ 655 static int first = 1; 656 pid_t pid; 657 658 /* The first PID allocated is always 1. */ 659 if (first) { 660 first = 0; 661 return 1; 662 } 663 664 /* 665 * All subsequent PIDs are chosen randomly. We need to 666 * find an unused PID in the range [2, PID_MAX]. 667 */ 668 do { 669 pid = 2 + arc4random_uniform(PID_MAX - 1); 670 } while (ispidtaken(pid)); 671 return pid; 672} 673 674void 675freepid(pid_t pid) 676{ 677 static uint32_t idx; 678 679 oldpids[idx++ % nitems(oldpids)] = pid; 680} 681 682/* Do machine independent parts of switching to a new process */ 683void 684proc_trampoline_mi(void) 685{ 686 struct schedstate_percpu *spc = &curcpu()->ci_schedstate; 687 struct proc *p = curproc; 688 689 SCHED_ASSERT_LOCKED(); 690 clear_resched(curcpu()); 691 mtx_leave(&sched_lock); 692 spl0(); 693 694 SCHED_ASSERT_UNLOCKED(); 695 KERNEL_ASSERT_UNLOCKED(); 696 assertwaitok(); 697 smr_idle(); 698 699 /* Start any optional clock interrupts needed by the thread. */ 700 if (ISSET(p->p_p->ps_flags, PS_ITIMER)) { 701 atomic_setbits_int(&spc->spc_schedflags, SPCF_ITIMER); 702 clockintr_advance(&spc->spc_itimer, hardclock_period); 703 } 704 if (ISSET(p->p_p->ps_flags, PS_PROFIL)) { 705 atomic_setbits_int(&spc->spc_schedflags, SPCF_PROFCLOCK); 706 clockintr_advance(&spc->spc_profclock, profclock_period); 707 } 708 709 nanouptime(&spc->spc_runtime); 710 KERNEL_LOCK(); 711} 712