1 /* $OpenBSD: kern_fork.c,v 1.261 2024/08/06 08:44:54 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 67 int nprocesses = 1; /* process 0 */ 68 int nthreads = 1; /* proc 0 */ 69 struct forkstat forkstat; 70 71 void fork_return(void *); 72 pid_t alloctid(void); 73 pid_t allocpid(void); 74 int ispidtaken(pid_t); 75 76 void unveil_copy(struct process *parent, struct process *child); 77 78 struct proc *thread_new(struct proc *_parent, vaddr_t _uaddr); 79 struct process *process_new(struct proc *, struct process *, int); 80 int fork_check_maxthread(uid_t _uid); 81 82 void 83 fork_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 93 int 94 sys_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 } 106 107 int 108 sys_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 } 113 114 int 115 sys___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 */ 145 struct proc * 146 thread_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 */ 178 void 179 process_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 klist_init_mutex(&pr->ps_klist, &pr->ps_mtx); 203 204 timeout_set_flags(&pr->ps_realit_to, realitexpire, pr, 205 KCLOCK_UPTIME, 0); 206 timeout_set(&pr->ps_rucheck_to, rucheck, pr); 207 } 208 209 210 /* 211 * Allocate and initialize a new process. 212 */ 213 struct process * 214 process_new(struct proc *p, struct process *parent, int flags) 215 { 216 struct process *pr; 217 218 pr = pool_get(&process_pool, PR_WAITOK); 219 220 /* 221 * Make a process structure for the new process. 222 * Start by zeroing the section of proc that is zero-initialized, 223 * then copy the section that is copied directly from the parent. 224 */ 225 memset(&pr->ps_startzero, 0, 226 (caddr_t)&pr->ps_endzero - (caddr_t)&pr->ps_startzero); 227 memcpy(&pr->ps_startcopy, &parent->ps_startcopy, 228 (caddr_t)&pr->ps_endcopy - (caddr_t)&pr->ps_startcopy); 229 230 process_initialize(pr, p); 231 pr->ps_pid = allocpid(); 232 lim_fork(parent, pr); 233 234 /* post-copy fixups */ 235 pr->ps_pptr = parent; 236 pr->ps_ppid = parent->ps_pid; 237 238 /* bump references to the text vnode (for sysctl) */ 239 pr->ps_textvp = parent->ps_textvp; 240 if (pr->ps_textvp) 241 vref(pr->ps_textvp); 242 243 /* copy unveil if unveil is active */ 244 unveil_copy(parent, pr); 245 246 pr->ps_flags = parent->ps_flags & 247 (PS_SUGID | PS_SUGIDEXEC | PS_PLEDGE | PS_EXECPLEDGE | 248 PS_WXNEEDED | PS_CHROOT); 249 if (parent->ps_session->s_ttyvp != NULL) 250 pr->ps_flags |= parent->ps_flags & PS_CONTROLT; 251 252 if (parent->ps_pin.pn_pins) { 253 pr->ps_pin.pn_pins = mallocarray(parent->ps_pin.pn_npins, 254 sizeof(u_int), M_PINSYSCALL, M_WAITOK); 255 memcpy(pr->ps_pin.pn_pins, parent->ps_pin.pn_pins, 256 parent->ps_pin.pn_npins * sizeof(u_int)); 257 pr->ps_flags |= PS_PIN; 258 } 259 if (parent->ps_libcpin.pn_pins) { 260 pr->ps_libcpin.pn_pins = mallocarray(parent->ps_libcpin.pn_npins, 261 sizeof(u_int), M_PINSYSCALL, M_WAITOK); 262 memcpy(pr->ps_libcpin.pn_pins, parent->ps_libcpin.pn_pins, 263 parent->ps_libcpin.pn_npins * sizeof(u_int)); 264 pr->ps_flags |= PS_LIBCPIN; 265 } 266 267 /* 268 * Duplicate sub-structures as needed. 269 * Increase reference counts on shared objects. 270 */ 271 if (flags & FORK_SHAREFILES) 272 pr->ps_fd = fdshare(parent); 273 else 274 pr->ps_fd = fdcopy(parent); 275 pr->ps_sigacts = sigactsinit(parent); 276 if (flags & FORK_SHAREVM) 277 pr->ps_vmspace = uvmspace_share(parent); 278 else 279 pr->ps_vmspace = uvmspace_fork(parent); 280 281 if (parent->ps_flags & PS_PROFIL) 282 startprofclock(pr); 283 if (flags & FORK_PTRACE) 284 pr->ps_flags |= parent->ps_flags & PS_TRACED; 285 if (flags & FORK_NOZOMBIE) 286 pr->ps_flags |= PS_NOZOMBIE; 287 if (flags & FORK_SYSTEM) 288 pr->ps_flags |= PS_SYSTEM; 289 290 /* mark as embryo to protect against others */ 291 pr->ps_flags |= PS_EMBRYO; 292 293 /* Force visibility of all of the above changes */ 294 membar_producer(); 295 296 /* it's sufficiently inited to be globally visible */ 297 LIST_INSERT_HEAD(&allprocess, pr, ps_list); 298 299 return pr; 300 } 301 302 /* print the 'table full' message once per 10 seconds */ 303 struct timeval fork_tfmrate = { 10, 0 }; 304 305 int 306 fork_check_maxthread(uid_t uid) 307 { 308 /* 309 * Although process entries are dynamically created, we still keep 310 * a global limit on the maximum number we will create. We reserve 311 * the last 5 processes to root. The variable nprocesses is the 312 * current number of processes, maxprocess is the limit. Similar 313 * rules for threads (struct proc): we reserve the last 5 to root; 314 * the variable nthreads is the current number of procs, maxthread is 315 * the limit. 316 */ 317 if ((nthreads >= maxthread - 5 && uid != 0) || nthreads >= maxthread) { 318 static struct timeval lasttfm; 319 320 if (ratecheck(&lasttfm, &fork_tfmrate)) 321 tablefull("thread"); 322 return EAGAIN; 323 } 324 nthreads++; 325 326 return 0; 327 } 328 329 static inline void 330 fork_thread_start(struct proc *p, struct proc *parent, int flags) 331 { 332 struct cpu_info *ci; 333 334 SCHED_LOCK(); 335 ci = sched_choosecpu_fork(parent, flags); 336 TRACEPOINT(sched, fork, p->p_tid + THREAD_PID_OFFSET, 337 p->p_p->ps_pid, CPU_INFO_UNIT(ci)); 338 setrunqueue(ci, p, p->p_usrpri); 339 SCHED_UNLOCK(); 340 } 341 342 int 343 fork1(struct proc *curp, int flags, void (*func)(void *), void *arg, 344 register_t *retval, struct proc **rnewprocp) 345 { 346 struct process *curpr = curp->p_p; 347 struct process *pr; 348 struct proc *p; 349 uid_t uid = curp->p_ucred->cr_ruid; 350 struct vmspace *vm; 351 int count; 352 vaddr_t uaddr; 353 int error; 354 struct ptrace_state *newptstat = NULL; 355 356 KASSERT((flags & ~(FORK_FORK | FORK_VFORK | FORK_PPWAIT | FORK_PTRACE 357 | FORK_IDLE | FORK_SHAREVM | FORK_SHAREFILES | FORK_NOZOMBIE 358 | FORK_SYSTEM)) == 0); 359 KASSERT(func != NULL); 360 361 if ((error = fork_check_maxthread(uid))) 362 return error; 363 364 if ((nprocesses >= maxprocess - 5 && uid != 0) || 365 nprocesses >= maxprocess) { 366 static struct timeval lasttfm; 367 368 if (ratecheck(&lasttfm, &fork_tfmrate)) 369 tablefull("process"); 370 nthreads--; 371 return EAGAIN; 372 } 373 nprocesses++; 374 375 /* 376 * Increment the count of processes running with this uid. 377 * Don't allow a nonprivileged user to exceed their current limit. 378 */ 379 count = chgproccnt(uid, 1); 380 if (uid != 0 && count > lim_cur(RLIMIT_NPROC)) { 381 (void)chgproccnt(uid, -1); 382 nprocesses--; 383 nthreads--; 384 return EAGAIN; 385 } 386 387 uaddr = uvm_uarea_alloc(); 388 if (uaddr == 0) { 389 (void)chgproccnt(uid, -1); 390 nprocesses--; 391 nthreads--; 392 return (ENOMEM); 393 } 394 395 /* 396 * From now on, we're committed to the fork and cannot fail. 397 */ 398 p = thread_new(curp, uaddr); 399 pr = process_new(p, curpr, flags); 400 401 p->p_fd = pr->ps_fd; 402 p->p_vmspace = pr->ps_vmspace; 403 if (pr->ps_flags & PS_SYSTEM) 404 atomic_setbits_int(&p->p_flag, P_SYSTEM); 405 406 if (flags & FORK_PPWAIT) { 407 atomic_setbits_int(&pr->ps_flags, PS_PPWAIT); 408 atomic_setbits_int(&curpr->ps_flags, PS_ISPWAIT); 409 } 410 411 #ifdef KTRACE 412 /* 413 * Copy traceflag and tracefile if enabled. 414 * If not inherited, these were zeroed above. 415 */ 416 if (curpr->ps_traceflag & KTRFAC_INHERIT) 417 ktrsettrace(pr, curpr->ps_traceflag, curpr->ps_tracevp, 418 curpr->ps_tracecred); 419 #endif 420 421 /* 422 * Finish creating the child thread. cpu_fork() will copy 423 * and update the pcb and make the child ready to run. If 424 * this is a normal user fork, the child will exit directly 425 * to user mode via child_return() on its first time slice 426 * and will not return here. If this is a kernel thread, 427 * the specified entry point will be executed. 428 */ 429 cpu_fork(curp, p, NULL, NULL, func, arg ? arg : p); 430 431 vm = pr->ps_vmspace; 432 433 if (flags & FORK_FORK) { 434 forkstat.cntfork++; 435 forkstat.sizfork += vm->vm_dsize + vm->vm_ssize; 436 } else if (flags & FORK_VFORK) { 437 forkstat.cntvfork++; 438 forkstat.sizvfork += vm->vm_dsize + vm->vm_ssize; 439 } else { 440 forkstat.cntkthread++; 441 } 442 443 if (pr->ps_flags & PS_TRACED && flags & FORK_FORK) 444 newptstat = malloc(sizeof(*newptstat), M_SUBPROC, M_WAITOK); 445 446 p->p_tid = alloctid(); 447 448 LIST_INSERT_HEAD(&allproc, p, p_list); 449 LIST_INSERT_HEAD(TIDHASH(p->p_tid), p, p_hash); 450 LIST_INSERT_HEAD(PIDHASH(pr->ps_pid), pr, ps_hash); 451 LIST_INSERT_AFTER(curpr, pr, ps_pglist); 452 LIST_INSERT_HEAD(&curpr->ps_children, pr, ps_sibling); 453 454 if (pr->ps_flags & PS_TRACED) { 455 pr->ps_oppid = curpr->ps_pid; 456 process_reparent(pr, curpr->ps_pptr); 457 458 /* 459 * Set ptrace status. 460 */ 461 if (newptstat != NULL) { 462 pr->ps_ptstat = newptstat; 463 newptstat = NULL; 464 curpr->ps_ptstat->pe_report_event = PTRACE_FORK; 465 pr->ps_ptstat->pe_report_event = PTRACE_FORK; 466 curpr->ps_ptstat->pe_other_pid = pr->ps_pid; 467 pr->ps_ptstat->pe_other_pid = curpr->ps_pid; 468 } 469 } 470 471 /* 472 * For new processes, set accounting bits and mark as complete. 473 */ 474 nanouptime(&pr->ps_start); 475 pr->ps_acflag = AFORK; 476 atomic_clearbits_int(&pr->ps_flags, PS_EMBRYO); 477 478 if ((flags & FORK_IDLE) == 0) 479 fork_thread_start(p, curp, flags); 480 else 481 p->p_cpu = arg; 482 483 free(newptstat, M_SUBPROC, sizeof(*newptstat)); 484 485 /* 486 * Notify any interested parties about the new process. 487 */ 488 knote_processfork(curpr, pr->ps_pid); 489 490 /* 491 * Update stats now that we know the fork was successful. 492 */ 493 uvmexp.forks++; 494 if (flags & FORK_PPWAIT) 495 uvmexp.forks_ppwait++; 496 if (flags & FORK_SHAREVM) 497 uvmexp.forks_sharevm++; 498 499 /* 500 * Pass a pointer to the new process to the caller. 501 */ 502 if (rnewprocp != NULL) 503 *rnewprocp = p; 504 505 /* 506 * Preserve synchronization semantics of vfork. If waiting for 507 * child to exec or exit, set PS_PPWAIT on child and PS_ISPWAIT 508 * on ourselves, and sleep on our process for the latter flag 509 * to go away. 510 * XXX Need to stop other rthreads in the parent 511 */ 512 if (flags & FORK_PPWAIT) 513 while (curpr->ps_flags & PS_ISPWAIT) 514 tsleep_nsec(curpr, PWAIT, "ppwait", INFSLP); 515 516 /* 517 * If we're tracing the child, alert the parent too. 518 */ 519 if ((flags & FORK_PTRACE) && (curpr->ps_flags & PS_TRACED)) 520 psignal(curp, SIGTRAP); 521 522 /* 523 * Return child pid to parent process 524 */ 525 if (retval != NULL) 526 *retval = pr->ps_pid; 527 return (0); 528 } 529 530 int 531 thread_fork(struct proc *curp, void *stack, void *tcb, pid_t *tidptr, 532 register_t *retval) 533 { 534 struct process *pr = curp->p_p; 535 struct proc *p; 536 pid_t tid; 537 vaddr_t uaddr; 538 int error; 539 540 if (stack == NULL) 541 return EINVAL; 542 543 if ((error = fork_check_maxthread(curp->p_ucred->cr_ruid))) 544 return error; 545 546 uaddr = uvm_uarea_alloc(); 547 if (uaddr == 0) { 548 nthreads--; 549 return ENOMEM; 550 } 551 552 /* 553 * From now on, we're committed to the fork and cannot fail. 554 */ 555 p = thread_new(curp, uaddr); 556 atomic_setbits_int(&p->p_flag, P_THREAD); 557 sigstkinit(&p->p_sigstk); 558 memset(p->p_name, 0, sizeof p->p_name); 559 560 /* other links */ 561 p->p_p = pr; 562 563 /* local copies */ 564 p->p_fd = pr->ps_fd; 565 p->p_vmspace = pr->ps_vmspace; 566 567 /* 568 * Finish creating the child thread. cpu_fork() will copy 569 * and update the pcb and make the child ready to run. The 570 * child will exit directly to user mode via child_return() 571 * on its first time slice and will not return here. 572 */ 573 cpu_fork(curp, p, stack, tcb, child_return, p); 574 575 p->p_tid = alloctid(); 576 577 LIST_INSERT_HEAD(&allproc, p, p_list); 578 LIST_INSERT_HEAD(TIDHASH(p->p_tid), p, p_hash); 579 580 mtx_enter(&pr->ps_mtx); 581 TAILQ_INSERT_TAIL(&pr->ps_threads, p, p_thr_link); 582 pr->ps_threadcnt++; 583 584 /* 585 * if somebody else wants to take us to single threaded mode, 586 * count ourselves in. 587 */ 588 if (pr->ps_single) { 589 pr->ps_singlecnt++; 590 atomic_setbits_int(&p->p_flag, P_SUSPSINGLE); 591 } 592 mtx_leave(&pr->ps_mtx); 593 594 /* 595 * Return tid to parent thread and copy it out to userspace 596 */ 597 *retval = tid = p->p_tid + THREAD_PID_OFFSET; 598 if (tidptr != NULL) { 599 if (copyout(&tid, tidptr, sizeof(tid))) 600 psignal(curp, SIGSEGV); 601 } 602 603 fork_thread_start(p, curp, 0); 604 605 /* 606 * Update stats now that we know the fork was successful. 607 */ 608 forkstat.cnttfork++; 609 uvmexp.forks++; 610 uvmexp.forks_sharevm++; 611 612 return 0; 613 } 614 615 616 /* Find an unused tid */ 617 pid_t 618 alloctid(void) 619 { 620 pid_t tid; 621 622 do { 623 /* (0 .. TID_MASK+1] */ 624 tid = 1 + (arc4random() & TID_MASK); 625 } while (tfind(tid) != NULL); 626 627 return (tid); 628 } 629 630 /* 631 * Checks for current use of a pid, either as a pid or pgid. 632 */ 633 pid_t oldpids[128]; 634 int 635 ispidtaken(pid_t pid) 636 { 637 uint32_t i; 638 639 for (i = 0; i < nitems(oldpids); i++) 640 if (pid == oldpids[i]) 641 return (1); 642 643 if (prfind(pid) != NULL) 644 return (1); 645 if (pgfind(pid) != NULL) 646 return (1); 647 if (zombiefind(pid) != NULL) 648 return (1); 649 return (0); 650 } 651 652 /* Find an unused pid */ 653 pid_t 654 allocpid(void) 655 { 656 static int first = 1; 657 pid_t pid; 658 659 /* The first PID allocated is always 1. */ 660 if (first) { 661 first = 0; 662 return 1; 663 } 664 665 /* 666 * All subsequent PIDs are chosen randomly. We need to 667 * find an unused PID in the range [2, PID_MAX]. 668 */ 669 do { 670 pid = 2 + arc4random_uniform(PID_MAX - 1); 671 } while (ispidtaken(pid)); 672 return pid; 673 } 674 675 void 676 freepid(pid_t pid) 677 { 678 static uint32_t idx; 679 680 oldpids[idx++ % nitems(oldpids)] = pid; 681 } 682 683 /* Do machine independent parts of switching to a new process */ 684 void 685 proc_trampoline_mi(void) 686 { 687 struct schedstate_percpu *spc = &curcpu()->ci_schedstate; 688 struct proc *p = curproc; 689 690 SCHED_ASSERT_LOCKED(); 691 clear_resched(curcpu()); 692 mtx_leave(&sched_lock); 693 spl0(); 694 695 SCHED_ASSERT_UNLOCKED(); 696 KERNEL_ASSERT_UNLOCKED(); 697 assertwaitok(); 698 smr_idle(); 699 700 /* Start any optional clock interrupts needed by the thread. */ 701 if (ISSET(p->p_p->ps_flags, PS_ITIMER)) { 702 atomic_setbits_int(&spc->spc_schedflags, SPCF_ITIMER); 703 clockintr_advance(&spc->spc_itimer, hardclock_period); 704 } 705 if (ISSET(p->p_p->ps_flags, PS_PROFIL)) { 706 atomic_setbits_int(&spc->spc_schedflags, SPCF_PROFCLOCK); 707 clockintr_advance(&spc->spc_profclock, profclock_period); 708 } 709 710 nanouptime(&spc->spc_runtime); 711 KERNEL_LOCK(); 712 } 713