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.
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11 * modification, are permitted provided that the following conditions
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
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17 * documentation and/or other materials provided with the distribution.
18 * 4. 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
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24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * @(#)kern_fork.c 8.6 (Berkeley) 4/8/94
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
40 #include "opt_kdtrace.h"
41 #include "opt_ktrace.h"
42 #include "opt_kstack_pages.h"
43 #include "opt_procdesc.h"
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/sysproto.h>
48 #include <sys/eventhandler.h>
49 #include <sys/fcntl.h>
50 #include <sys/filedesc.h>
52 #include <sys/kernel.h>
53 #include <sys/kthread.h>
54 #include <sys/sysctl.h>
56 #include <sys/malloc.h>
57 #include <sys/mutex.h>
60 #include <sys/procdesc.h>
61 #include <sys/pioctl.h>
62 #include <sys/ptrace.h>
63 #include <sys/racct.h>
64 #include <sys/resourcevar.h>
65 #include <sys/sched.h>
66 #include <sys/syscall.h>
67 #include <sys/vmmeter.h>
68 #include <sys/vnode.h>
71 #include <sys/ktrace.h>
72 #include <sys/unistd.h>
75 #include <sys/sysent.h>
76 #include <sys/signalvar.h>
78 #include <security/audit/audit.h>
79 #include <security/mac/mac_framework.h>
83 #include <vm/vm_map.h>
84 #include <vm/vm_extern.h>
88 #include <sys/dtrace_bsd.h>
89 dtrace_fork_func_t dtrace_fasttrap_fork;
92 SDT_PROVIDER_DECLARE(proc);
93 SDT_PROBE_DEFINE3(proc, kernel, , create, "struct proc *",
94 "struct proc *", "int");
96 #ifndef _SYS_SYSPROTO_H_
104 sys_fork(struct thread *td, struct fork_args *uap)
109 error = fork1(td, RFFDG | RFPROC, 0, &p2, NULL, 0);
111 td->td_retval[0] = p2->p_pid;
112 td->td_retval[1] = 0;
121 struct pdfork_args *uap;
128 * It is necessary to return fd by reference because 0 is a valid file
129 * descriptor number, and the child needs to be able to distinguish
130 * itself from the parent using the return value.
132 error = fork1(td, RFFDG | RFPROC | RFPROCDESC, 0, &p2,
135 td->td_retval[0] = p2->p_pid;
136 td->td_retval[1] = 0;
137 error = copyout(&fd, uap->fdp, sizeof(fd));
147 sys_vfork(struct thread *td, struct vfork_args *uap)
153 flags = RFFDG | RFPROC; /* validate that this is still an issue */
155 flags = RFFDG | RFPROC | RFPPWAIT | RFMEM;
157 error = fork1(td, flags, 0, &p2, NULL, 0);
159 td->td_retval[0] = p2->p_pid;
160 td->td_retval[1] = 0;
166 sys_rfork(struct thread *td, struct rfork_args *uap)
171 /* Don't allow kernel-only flags. */
172 if ((uap->flags & RFKERNELONLY) != 0)
175 AUDIT_ARG_FFLAGS(uap->flags);
176 error = fork1(td, uap->flags, 0, &p2, NULL, 0);
178 td->td_retval[0] = p2 ? p2->p_pid : 0;
179 td->td_retval[1] = 0;
184 int nprocs = 1; /* process 0 */
186 SYSCTL_INT(_kern, OID_AUTO, lastpid, CTLFLAG_RD, &lastpid, 0,
190 * Random component to lastpid generation. We mix in a random factor to make
191 * it a little harder to predict. We sanity check the modulus value to avoid
192 * doing it in critical paths. Don't let it be too small or we pointlessly
193 * waste randomness entropy, and don't let it be impossibly large. Using a
194 * modulus that is too big causes a LOT more process table scans and slows
195 * down fork processing as the pidchecked caching is defeated.
197 static int randompid = 0;
200 sysctl_kern_randompid(SYSCTL_HANDLER_ARGS)
204 error = sysctl_wire_old_buffer(req, sizeof(int));
207 sx_xlock(&allproc_lock);
209 error = sysctl_handle_int(oidp, &pid, 0, req);
210 if (error == 0 && req->newptr != NULL) {
211 if (pid < 0 || pid > pid_max - 100) /* out of range */
213 else if (pid < 2) /* NOP */
215 else if (pid < 100) /* Make it reasonable */
219 sx_xunlock(&allproc_lock);
223 SYSCTL_PROC(_kern, OID_AUTO, randompid, CTLTYPE_INT|CTLFLAG_RW,
224 0, 0, sysctl_kern_randompid, "I", "Random PID modulus");
227 fork_findpid(int flags)
231 static int pidchecked = 0;
234 * Requires allproc_lock in order to iterate over the list
235 * of processes, and proctree_lock to access p_pgrp.
237 sx_assert(&allproc_lock, SX_LOCKED);
238 sx_assert(&proctree_lock, SX_LOCKED);
241 * Find an unused process ID. We remember a range of unused IDs
242 * ready to use (from lastpid+1 through pidchecked-1).
244 * If RFHIGHPID is set (used during system boot), do not allocate
247 trypid = lastpid + 1;
248 if (flags & RFHIGHPID) {
253 trypid += arc4random() % randompid;
257 * If the process ID prototype has wrapped around,
258 * restart somewhat above 0, as the low-numbered procs
259 * tend to include daemons that don't exit.
261 if (trypid >= pid_max) {
262 trypid = trypid % pid_max;
267 if (trypid >= pidchecked) {
270 pidchecked = PID_MAX;
272 * Scan the active and zombie procs to check whether this pid
273 * is in use. Remember the lowest pid that's greater
274 * than trypid, so we can avoid checking for a while.
276 p = LIST_FIRST(&allproc);
278 for (; p != NULL; p = LIST_NEXT(p, p_list)) {
279 while (p->p_pid == trypid ||
280 (p->p_pgrp != NULL &&
281 (p->p_pgrp->pg_id == trypid ||
282 (p->p_session != NULL &&
283 p->p_session->s_sid == trypid)))) {
285 if (trypid >= pidchecked)
288 if (p->p_pid > trypid && pidchecked > p->p_pid)
289 pidchecked = p->p_pid;
290 if (p->p_pgrp != NULL) {
291 if (p->p_pgrp->pg_id > trypid &&
292 pidchecked > p->p_pgrp->pg_id)
293 pidchecked = p->p_pgrp->pg_id;
294 if (p->p_session != NULL &&
295 p->p_session->s_sid > trypid &&
296 pidchecked > p->p_session->s_sid)
297 pidchecked = p->p_session->s_sid;
302 p = LIST_FIRST(&zombproc);
308 * RFHIGHPID does not mess with the lastpid counter during boot.
310 if (flags & RFHIGHPID)
319 fork_norfproc(struct thread *td, int flags)
324 KASSERT((flags & RFPROC) == 0,
325 ("fork_norfproc called with RFPROC set"));
328 if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) &&
329 (flags & (RFCFDG | RFFDG))) {
331 if (thread_single(SINGLE_BOUNDARY)) {
338 error = vm_forkproc(td, NULL, NULL, NULL, flags);
343 * Close all file descriptors.
345 if (flags & RFCFDG) {
346 struct filedesc *fdtmp;
347 fdtmp = fdinit(td->td_proc->p_fd);
353 * Unshare file descriptors (from parent).
359 if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) &&
360 (flags & (RFCFDG | RFFDG))) {
369 do_fork(struct thread *td, int flags, struct proc *p2, struct thread *td2,
370 struct vmspace *vm2, int pdflags)
372 struct proc *p1, *pptr;
375 struct filedesc_to_leader *fdtol;
376 struct sigacts *newsigacts;
378 sx_assert(&proctree_lock, SX_SLOCKED);
379 sx_assert(&allproc_lock, SX_XLOCKED);
385 * Increment the nprocs resource before blocking can occur. There
386 * are hard-limits as to the number of processes that can run.
390 trypid = fork_findpid(flags);
392 sx_sunlock(&proctree_lock);
394 p2->p_state = PRS_NEW; /* protect against others */
396 AUDIT_ARG_PID(p2->p_pid);
397 LIST_INSERT_HEAD(&allproc, p2, p_list);
398 LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash);
403 sx_xunlock(&allproc_lock);
405 bcopy(&p1->p_startcopy, &p2->p_startcopy,
406 __rangeof(struct proc, p_startcopy, p_endcopy));
407 pargs_hold(p2->p_args);
410 bzero(&p2->p_startzero,
411 __rangeof(struct proc, p_startzero, p_endzero));
414 p2->p_ucred = crhold(td->td_ucred);
416 /* Tell the prison that we exist. */
417 prison_proc_hold(p2->p_ucred->cr_prison);
422 * Malloc things while we don't hold any locks.
424 if (flags & RFSIGSHARE)
427 newsigacts = sigacts_alloc();
432 if (flags & RFCFDG) {
433 fd = fdinit(p1->p_fd);
435 } else if (flags & RFFDG) {
436 fd = fdcopy(p1->p_fd);
439 fd = fdshare(p1->p_fd);
440 if (p1->p_fdtol == NULL)
441 p1->p_fdtol = filedesc_to_leader_alloc(NULL, NULL,
443 if ((flags & RFTHREAD) != 0) {
445 * Shared file descriptor table, and shared
449 FILEDESC_XLOCK(p1->p_fd);
450 fdtol->fdl_refcount++;
451 FILEDESC_XUNLOCK(p1->p_fd);
454 * Shared file descriptor table, and different
457 fdtol = filedesc_to_leader_alloc(p1->p_fdtol,
462 * Make a proc table entry for the new process.
463 * Start by zeroing the section of proc that is zero-initialized,
464 * then copy the section that is copied directly from the parent.
470 bzero(&td2->td_startzero,
471 __rangeof(struct thread, td_startzero, td_endzero));
473 bcopy(&td->td_startcopy, &td2->td_startcopy,
474 __rangeof(struct thread, td_startcopy, td_endcopy));
476 bcopy(&p2->p_comm, &td2->td_name, sizeof(td2->td_name));
477 td2->td_sigstk = td->td_sigstk;
478 td2->td_sigmask = td->td_sigmask;
479 td2->td_flags = TDF_INMEM;
480 td2->td_lend_user_pri = PRI_MAX;
481 td2->td_dbg_sc_code = td->td_dbg_sc_code;
482 td2->td_dbg_sc_narg = td->td_dbg_sc_narg;
486 td2->td_vnet_lpush = NULL;
490 * Allow the scheduler to initialize the child.
497 * Duplicate sub-structures as needed.
498 * Increase reference counts on shared objects.
500 p2->p_flag = P_INMEM;
502 p2->p_swtick = ticks;
503 if (p1->p_flag & P_PROFIL)
505 td2->td_ucred = crhold(p2->p_ucred);
507 if (flags & RFSIGSHARE) {
508 p2->p_sigacts = sigacts_hold(p1->p_sigacts);
510 sigacts_copy(newsigacts, p1->p_sigacts);
511 p2->p_sigacts = newsigacts;
514 if (flags & RFTSIGZMB)
515 p2->p_sigparent = RFTSIGNUM(flags);
516 else if (flags & RFLINUXTHPN)
517 p2->p_sigparent = SIGUSR1;
519 p2->p_sigparent = SIGCHLD;
521 p2->p_textvp = p1->p_textvp;
525 if (p1->p_flag2 & P2_INHERIT_PROTECTED) {
526 p2->p_flag |= P_PROTECTED;
527 p2->p_flag2 |= P2_INHERIT_PROTECTED;
531 * p_limit is copy-on-write. Bump its refcount.
535 pstats_fork(p1->p_stats, p2->p_stats);
540 /* Bump references to the text vnode (for procfs). */
545 * Set up linkage for kernel based threading.
547 if ((flags & RFTHREAD) != 0) {
548 mtx_lock(&ppeers_lock);
549 p2->p_peers = p1->p_peers;
551 p2->p_leader = p1->p_leader;
552 mtx_unlock(&ppeers_lock);
553 PROC_LOCK(p1->p_leader);
554 if ((p1->p_leader->p_flag & P_WEXIT) != 0) {
555 PROC_UNLOCK(p1->p_leader);
557 * The task leader is exiting, so process p1 is
558 * going to be killed shortly. Since p1 obviously
559 * isn't dead yet, we know that the leader is either
560 * sending SIGKILL's to all the processes in this
561 * task or is sleeping waiting for all the peers to
562 * exit. We let p1 complete the fork, but we need
563 * to go ahead and kill the new process p2 since
564 * the task leader may not get a chance to send
565 * SIGKILL to it. We leave it on the list so that
566 * the task leader will wait for this new process
570 kern_psignal(p2, SIGKILL);
573 PROC_UNLOCK(p1->p_leader);
579 sx_xlock(&proctree_lock);
580 PGRP_LOCK(p1->p_pgrp);
585 * Preserve some more flags in subprocess. P_PROFIL has already
588 p2->p_flag |= p1->p_flag & P_SUGID;
589 td2->td_pflags |= td->td_pflags & TDP_ALTSTACK;
590 SESS_LOCK(p1->p_session);
591 if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
592 p2->p_flag |= P_CONTROLT;
593 SESS_UNLOCK(p1->p_session);
594 if (flags & RFPPWAIT)
595 p2->p_flag |= P_PPWAIT;
597 p2->p_pgrp = p1->p_pgrp;
598 LIST_INSERT_AFTER(p1, p2, p_pglist);
599 PGRP_UNLOCK(p1->p_pgrp);
600 LIST_INIT(&p2->p_children);
601 LIST_INIT(&p2->p_orphans);
603 callout_init_mtx(&p2->p_itcallout, &p2->p_mtx, 0);
606 * If PF_FORK is set, the child process inherits the
607 * procfs ioctl flags from its parent.
609 if (p1->p_pfsflags & PF_FORK) {
610 p2->p_stops = p1->p_stops;
611 p2->p_pfsflags = p1->p_pfsflags;
615 * This begins the section where we must prevent the parent
616 * from being swapped.
622 * Attach the new process to its parent.
624 * If RFNOWAIT is set, the newly created process becomes a child
625 * of init. This effectively disassociates the child from the
628 if (flags & RFNOWAIT)
633 LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling);
634 sx_xunlock(&proctree_lock);
636 /* Inform accounting that we have forked. */
637 p2->p_acflag = AFORK;
645 * Finish creating the child process. It will return via a different
646 * execution path later. (ie: directly into user mode)
648 vm_forkproc(td, p2, td2, vm2, flags);
650 if (flags == (RFFDG | RFPROC)) {
651 PCPU_INC(cnt.v_forks);
652 PCPU_ADD(cnt.v_forkpages, p2->p_vmspace->vm_dsize +
653 p2->p_vmspace->vm_ssize);
654 } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) {
655 PCPU_INC(cnt.v_vforks);
656 PCPU_ADD(cnt.v_vforkpages, p2->p_vmspace->vm_dsize +
657 p2->p_vmspace->vm_ssize);
658 } else if (p1 == &proc0) {
659 PCPU_INC(cnt.v_kthreads);
660 PCPU_ADD(cnt.v_kthreadpages, p2->p_vmspace->vm_dsize +
661 p2->p_vmspace->vm_ssize);
663 PCPU_INC(cnt.v_rforks);
664 PCPU_ADD(cnt.v_rforkpages, p2->p_vmspace->vm_dsize +
665 p2->p_vmspace->vm_ssize);
670 * Associate the process descriptor with the process before anything
671 * can happen that might cause that process to need the descriptor.
672 * However, don't do this until after fork(2) can no longer fail.
674 if (flags & RFPROCDESC)
675 procdesc_new(p2, pdflags);
679 * Both processes are set up, now check if any loadable modules want
680 * to adjust anything.
682 EVENTHANDLER_INVOKE(process_fork, p1, p2, flags);
685 * Set the child start time and mark the process as being complete.
689 microuptime(&p2->p_stats->p_start);
691 p2->p_state = PRS_NORMAL;
696 * Tell the DTrace fasttrap provider about the new process so that any
697 * tracepoints inherited from the parent can be removed. We have to do
698 * this only after p_state is PRS_NORMAL since the fasttrap module will
699 * use pfind() later on.
701 if ((flags & RFMEM) == 0 && dtrace_fasttrap_fork)
702 dtrace_fasttrap_fork(p1, p2);
704 if ((p1->p_flag & (P_TRACED | P_FOLLOWFORK)) == (P_TRACED |
707 * Arrange for debugger to receive the fork event.
709 * We can report PL_FLAG_FORKED regardless of
710 * P_FOLLOWFORK settings, but it does not make a sense
713 td->td_dbgflags |= TDB_FORK;
714 td->td_dbg_forked = p2->p_pid;
715 td2->td_dbgflags |= TDB_STOPATFORK;
719 if (flags & RFPPWAIT) {
720 td->td_pflags |= TDP_RFPPWAIT;
721 td->td_rfppwait_p = p2;
724 if ((flags & RFSTOPPED) == 0) {
726 * If RFSTOPPED not requested, make child runnable and
731 sched_add(td2, SRQ_BORING);
736 * Now can be swapped.
742 * Tell any interested parties about the new process.
744 knote_fork(&p1->p_klist, p2->p_pid);
745 SDT_PROBE3(proc, kernel, , create, p2, p1, flags);
748 * Wait until debugger is attached to child.
751 while ((td2->td_dbgflags & TDB_STOPATFORK) != 0)
752 cv_wait(&p2->p_dbgwait, &p2->p_mtx);
759 fork1(struct thread *td, int flags, int pages, struct proc **procp,
760 int *procdescp, int pdflags)
763 struct proc *newproc;
767 vm_ooffset_t mem_charged;
770 static struct timeval lastfail;
772 struct file *fp_procdesc = NULL;
775 /* Check for the undefined or unimplemented flags. */
776 if ((flags & ~(RFFLAGS | RFTSIGFLAGS(RFTSIGMASK))) != 0)
779 /* Signal value requires RFTSIGZMB. */
780 if ((flags & RFTSIGFLAGS(RFTSIGMASK)) != 0 && (flags & RFTSIGZMB) == 0)
783 /* Can't copy and clear. */
784 if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
787 /* Check the validity of the signal number. */
788 if ((flags & RFTSIGZMB) != 0 && (u_int)RFTSIGNUM(flags) > _SIG_MAXSIG)
792 if ((flags & RFPROCDESC) != 0) {
793 /* Can't not create a process yet get a process descriptor. */
794 if ((flags & RFPROC) == 0)
797 /* Must provide a place to put a procdesc if creating one. */
798 if (procdescp == NULL)
806 * Here we don't create a new process, but we divorce
807 * certain parts of a process from itself.
809 if ((flags & RFPROC) == 0) {
811 return (fork_norfproc(td, flags));
816 * If required, create a process descriptor in the parent first; we
817 * will abandon it if something goes wrong. We don't finit() until
820 if (flags & RFPROCDESC) {
821 error = falloc(td, &fp_procdesc, procdescp, 0);
830 pages = KSTACK_PAGES;
831 /* Allocate new proc. */
832 newproc = uma_zalloc(proc_zone, M_WAITOK);
833 td2 = FIRST_THREAD_IN_PROC(newproc);
835 td2 = thread_alloc(pages);
840 proc_linkup(newproc, td2);
842 if (td2->td_kstack == 0 || td2->td_kstack_pages != pages) {
843 if (td2->td_kstack != 0)
844 vm_thread_dispose(td2);
845 if (!thread_alloc_stack(td2, pages)) {
852 if ((flags & RFMEM) == 0) {
853 vm2 = vmspace_fork(p1->p_vmspace, &mem_charged);
858 if (!swap_reserve(mem_charged)) {
860 * The swap reservation failed. The accounting
861 * from the entries of the copied vm2 will be
862 * substracted in vmspace_free(), so force the
865 swap_reserve_force(mem_charged);
873 * XXX: This is ugly; when we copy resource usage, we need to bump
874 * per-cred resource counters.
876 newproc->p_ucred = p1->p_ucred;
879 * Initialize resource accounting for the child process.
881 error = racct_proc_fork(p1, newproc);
888 mac_proc_init(newproc);
890 knlist_init_mtx(&newproc->p_klist, &newproc->p_mtx);
891 STAILQ_INIT(&newproc->p_ktr);
893 /* We have to lock the process tree while we look for a pid. */
894 sx_slock(&proctree_lock);
897 * Although process entries are dynamically created, we still keep
898 * a global limit on the maximum number we will create. Don't allow
899 * a nonprivileged user to use the last ten processes; don't let root
900 * exceed the limit. The variable nprocs is the current number of
901 * processes, maxproc is the limit.
903 sx_xlock(&allproc_lock);
904 if ((nprocs >= maxproc - 10 && priv_check_cred(td->td_ucred,
905 PRIV_MAXPROC, 0) != 0) || nprocs >= maxproc) {
911 * Increment the count of procs running with this uid. Don't allow
912 * a nonprivileged user to exceed their current limit.
914 * XXXRW: Can we avoid privilege here if it's not needed?
916 error = priv_check_cred(td->td_ucred, PRIV_PROC_LIMIT, 0);
918 ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 0);
921 ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1,
922 lim_cur(p1, RLIMIT_NPROC));
926 do_fork(td, flags, newproc, td2, vm2, pdflags);
929 * Return child proc pointer to parent.
933 if (flags & RFPROCDESC)
934 procdesc_finit(newproc->p_procdesc, fp_procdesc);
936 racct_proc_fork_done(newproc);
942 sx_sunlock(&proctree_lock);
943 if (ppsratecheck(&lastfail, &curfail, 1))
944 printf("maxproc limit exceeded by uid %u (pid %d); see tuning(7) and login.conf(5)\n",
945 td->td_ucred->cr_ruid, p1->p_pid);
946 sx_xunlock(&allproc_lock);
948 mac_proc_destroy(newproc);
950 racct_proc_exit(newproc);
954 uma_zfree(proc_zone, newproc);
956 if (((flags & RFPROCDESC) != 0) && (fp_procdesc != NULL))
957 fdrop(fp_procdesc, td);
959 pause("fork", hz / 2);
964 * Handle the return of a child process from fork1(). This function
965 * is called from the MD fork_trampoline() entry point.
968 fork_exit(void (*callout)(void *, struct trapframe *), void *arg,
969 struct trapframe *frame)
977 KASSERT(p->p_state == PRS_NORMAL, ("executing process is still new"));
979 CTR4(KTR_PROC, "fork_exit: new thread %p (td_sched %p, pid %d, %s)",
980 td, td->td_sched, p->p_pid, td->td_name);
984 * Processes normally resume in mi_switch() after being
985 * cpu_switch()'ed to, but when children start up they arrive here
986 * instead, so we must do much the same things as mi_switch() would.
988 if ((dtd = PCPU_GET(deadthread))) {
989 PCPU_SET(deadthread, NULL);
995 * cpu_set_fork_handler intercepts this function call to
996 * have this call a non-return function to stay in kernel mode.
997 * initproc has its own fork handler, but it does return.
999 KASSERT(callout != NULL, ("NULL callout in fork_exit"));
1000 callout(arg, frame);
1003 * Check if a kernel thread misbehaved and returned from its main
1006 if (p->p_flag & P_KTHREAD) {
1007 printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n",
1008 td->td_name, p->p_pid);
1011 mtx_assert(&Giant, MA_NOTOWNED);
1013 if (p->p_sysent->sv_schedtail != NULL)
1014 (p->p_sysent->sv_schedtail)(td);
1018 * Simplified back end of syscall(), used when returning from fork()
1019 * directly into user mode. Giant is not held on entry, and must not
1020 * be held on return. This function is passed in to fork_exit() as the
1021 * first parameter and is called when returning to a new userland process.
1024 fork_return(struct thread *td, struct trapframe *frame)
1026 struct proc *p, *dbg;
1029 if (td->td_dbgflags & TDB_STOPATFORK) {
1030 sx_xlock(&proctree_lock);
1032 if ((p->p_pptr->p_flag & (P_TRACED | P_FOLLOWFORK)) ==
1033 (P_TRACED | P_FOLLOWFORK)) {
1035 * If debugger still wants auto-attach for the
1036 * parent's children, do it now.
1038 dbg = p->p_pptr->p_pptr;
1039 p->p_flag |= P_TRACED;
1040 p->p_oppid = p->p_pptr->p_pid;
1042 "fork_return: attaching to new child pid %d: oppid %d",
1043 p->p_pid, p->p_oppid);
1044 proc_reparent(p, dbg);
1045 sx_xunlock(&proctree_lock);
1046 td->td_dbgflags |= TDB_CHILD | TDB_SCX;
1047 ptracestop(td, SIGSTOP);
1048 td->td_dbgflags &= ~(TDB_CHILD | TDB_SCX);
1051 * ... otherwise clear the request.
1053 sx_xunlock(&proctree_lock);
1054 td->td_dbgflags &= ~TDB_STOPATFORK;
1055 cv_broadcast(&p->p_dbgwait);
1058 } else if (p->p_flag & P_TRACED) {
1060 * This is the start of a new thread in a traced
1061 * process. Report a system call exit event.
1064 td->td_dbgflags |= TDB_SCX;
1065 _STOPEVENT(p, S_SCX, td->td_dbg_sc_code);
1066 if ((p->p_stops & S_PT_SCX) != 0)
1067 ptracestop(td, SIGTRAP);
1068 td->td_dbgflags &= ~TDB_SCX;
1075 if (KTRPOINT(td, KTR_SYSRET))
1076 ktrsysret(SYS_fork, 0, 0);
1078 mtx_assert(&Giant, MA_NOTOWNED);