Return to sys_process.c CVS log

Up to [cvs.NetBSD.org] / src / sys / kern

Apply patch, requested by jmcneill in ticket #1668:
	sys/arch/amd64/amd64/syscall.c			patch
	sys/arch/i386/i386/syscall.c			patch
	sys/arch/i386/i386/trap.c			patch
	sys/kern/kern_sig.c				patch
	sys/kern/kern_sleepq.c				patch
	sys/kern/kern_subr.c				patch
	sys/kern/sys_process.c				patch
	sys/secmodel/bsd44/secmodel_bsd44_suser.c	patch
	sys/sys/proc.h					patch
	sys/sys/ptrace.h				patch

arch/i386/i386/machdep.c, arch/amd64/amd64/machdep.c (from
arch/x86/x86/machdep.c) by christos:
Remove code that was used to avoid register spills. setcontext(2) can change
the registers, so re-fetching will produce the wrong result for trace_exit().
arch/i386/i386/trap.c by reinoud:
Fix the illegal instruction return address. It was using the value of the
cpu's %cr2 register but thats not valid:

CR2 Contains a value called Page Fault Linear Address (PFLA). When a page
fault occurs, the address the program attempted to access is stored in the CR2
register.

And this is thus NOT the illegal instruction address!
kern/kern_sig.c by christos:
PR kern/45327: Jared McNeill: ptrace: siginfo doesn't work with traced processes
When saving the signal in p->p_xstat, clear it from the pending mask, but
don't remove it from the siginfo queue, so that next time the debugger
delivers it, the original information is found.
When posting a signal from the debugger l->l_sigpendset is not set, so we
use the process pending signal and add it back to the process pending set.
Split sigget into sigget() and siggetinfo(). When a signal comes from the
debugger (l->l_sigpendset == NULL), using siggetinfo() try to fetch the
siginfo information from l->l_sigpend and then from p->p_sigpend if it
was not found. This allows us to pass siginfo information for traps from
the debugger.
don't delete signal from the debugger.
kern/kern_sleepq.c by christos:
PR kern/40594: Antti Kantee: Don't call issignal() here to determine what errno
to set for the interrupted syscall, because issignal() will consume the signal
and it will not be delivered to the process afterwards. Instead call
sigispending() (which now returns the first pending signal) and does not
consume the signal.
We need to process SA_STOP signals immediately, and not deliver them to
the process. Instead of re-structuring the code to do that, call issignal()
like before in that case. (tail -F /file^Zfg should not get interrupted).
kern/kern_subr.c by jmcneill, christos:
PR kern/45312: ptrace: PT_SETREGS can't alter system calls

Add a new PT_SYSCALLEMU request that cancels the current syscall, for
use with PT_SYSCALL.
For PT_SYSCALLEMU, no need to stop again on syscall exit.
ifdef unused variable with -UPTRACE

kern/sys_process.c, sys/proc.h, sys/ptrace.h, secmodel/bsd44/secmodel_bsd44_suser.c by jmcneill, christos:
PR kern/43681: PT_SYSCALL appears to be broken

sys_ptrace: For PT_CONTINUE/PT_SYSCALL/PT_DETACH, modify the p_trace_enabled
flag of the target process, not the calling process.
Process the signal now, otherwise calling issignal() and ignoring
the return will lose the signal if it came from the debugger
(issignal() clears p->p_xstat)
PR kern/45312: ptrace: PT_SETREGS can't alter system calls

Add a new PT_SYSCALLEMU request that cancels the current syscall, for
use with PT_SYSCALL.
PR kern/45330: ptrace: signals can alter syscall return values

process_stoptrace: defer signal processing to userret, ok christos@

/*	$NetBSD: sys_process.c,v 1.143.4.2 2012/02/04 16:57:59 bouyer Exp $	*/

/*-
 * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Andrew Doran.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*-
 * Copyright (c) 1982, 1986, 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * This code is derived from software contributed to Berkeley by
 * Jan-Simon Pendry.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	from: @(#)sys_process.c	8.1 (Berkeley) 6/10/93
 */

/*-
 * Copyright (c) 1993 Jan-Simon Pendry.
 * Copyright (c) 1994 Christopher G. Demetriou.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Jan-Simon Pendry.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	from: @(#)sys_process.c	8.1 (Berkeley) 6/10/93
 */

/*
 * References:
 *	(1) Bach's "The Design of the UNIX Operating System",
 *	(2) sys/miscfs/procfs from UCB's 4.4BSD-Lite distribution,
 *	(3) the "4.4BSD Programmer's Reference Manual" published
 *		by USENIX and O'Reilly & Associates.
 * The 4.4BSD PRM does a reasonably good job of documenting what the various
 * ptrace() requests should actually do, and its text is quoted several times
 * in this file.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sys_process.c,v 1.143.4.2 2012/02/04 16:57:59 bouyer Exp $");

#include "opt_coredump.h"
#include "opt_ptrace.h"
#include "opt_ktrace.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/errno.h>
#include <sys/ptrace.h>
#include <sys/uio.h>
#include <sys/user.h>
#include <sys/ras.h>
#include <sys/malloc.h>
#include <sys/kauth.h>
#include <sys/mount.h>
#include <sys/syscallargs.h>

#include <uvm/uvm_extern.h>

#include <machine/reg.h>

#ifdef PTRACE
/*
 * Process debugging system call.
 */
int
sys_ptrace(struct lwp *l, const struct sys_ptrace_args *uap, register_t *retval)
{
	/* {
		syscallarg(int) req;
		syscallarg(pid_t) pid;
		syscallarg(void *) addr;
		syscallarg(int) data;
	} */
	struct proc *p = l->l_proc;
	struct lwp *lt;
	struct proc *t;				/* target process */
	struct uio uio;
	struct iovec iov;
	struct ptrace_io_desc piod;
	struct ptrace_lwpinfo pl;
	struct vmspace *vm;
	int error, write, tmp, req, pheld;
	int signo;
	ksiginfo_t ksi;
#ifdef COREDUMP
	char *path;
#endif

	error = 0;
	req = SCARG(uap, req);

	/*
	 * If attaching or detaching, we need to get a write hold on the
	 * proclist lock so that we can re-parent the target process.
	 */
	mutex_enter(proc_lock);

	/* "A foolish consistency..." XXX */
	if (req == PT_TRACE_ME) {
		t = p;
		mutex_enter(t->p_lock);
	} else {
		/* Find the process we're supposed to be operating on. */
		if ((t = p_find(SCARG(uap, pid), PFIND_LOCKED)) == NULL) {
			mutex_exit(proc_lock);
			return (ESRCH);
		}

		/* XXX-elad */
		mutex_enter(t->p_lock);
		error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_CANSEE,
		    t, KAUTH_ARG(KAUTH_REQ_PROCESS_CANSEE_ENTRY), NULL, NULL);
		if (error) {
			mutex_exit(proc_lock);
			mutex_exit(t->p_lock);
			return (ESRCH);
		}
	}

	/*
	 * Grab a reference on the process to prevent it from execing or
	 * exiting.
	 */
	if (!rw_tryenter(&t->p_reflock, RW_READER)) {
		mutex_exit(proc_lock);
		mutex_exit(t->p_lock);
		return EBUSY;
	}

	/* Make sure we can operate on it. */
	switch (req) {
	case  PT_TRACE_ME:
		/* Saying that you're being traced is always legal. */
		break;

	case  PT_ATTACH:
		/*
		 * You can't attach to a process if:
		 *	(1) it's the process that's doing the attaching,
		 */
		if (t->p_pid == p->p_pid) {
			error = EINVAL;
			break;
		}

		/*
		 *  (2) it's a system process
		 */
		if (t->p_flag & PK_SYSTEM) {
			error = EPERM;
			break;
		}

		/*
		 *	(3) it's already being traced, or
		 */
		if (ISSET(t->p_slflag, PSL_TRACED)) {
			error = EBUSY;
			break;
		}

		/*
		 * 	(4) the tracer is chrooted, and its root directory is
		 * 	    not at or above the root directory of the tracee
		 */
		mutex_exit(t->p_lock);	/* XXXSMP */
		tmp = proc_isunder(t, l);
		mutex_enter(t->p_lock);	/* XXXSMP */
		if (!tmp) {
			error = EPERM;
			break;
		}
		break;

	case  PT_READ_I:
	case  PT_READ_D:
	case  PT_WRITE_I:
	case  PT_WRITE_D:
	case  PT_IO:
#ifdef PT_GETREGS
	case  PT_GETREGS:
#endif
#ifdef PT_SETREGS
	case  PT_SETREGS:
#endif
#ifdef PT_GETFPREGS
	case  PT_GETFPREGS:
#endif
#ifdef PT_SETFPREGS
	case  PT_SETFPREGS:
#endif
#ifdef __HAVE_PTRACE_MACHDEP
	PTRACE_MACHDEP_REQUEST_CASES
#endif
		/*
		 * You can't read/write the memory or registers of a process
		 * if the tracer is chrooted, and its root directory is not at
		 * or above the root directory of the tracee.
		 */
		mutex_exit(t->p_lock);	/* XXXSMP */
		tmp = proc_isunder(t, l);
		mutex_enter(t->p_lock);	/* XXXSMP */
		if (!tmp) {
			error = EPERM;
			break;
		}
		/*FALLTHROUGH*/

	case  PT_CONTINUE:
	case  PT_KILL:
	case  PT_DETACH:
	case  PT_LWPINFO:
	case  PT_SYSCALL:
	case  PT_SYSCALLEMU:
#ifdef COREDUMP
	case  PT_DUMPCORE:
#endif
#ifdef PT_STEP
	case  PT_STEP:
#endif
		/*
		 * You can't do what you want to the process if:
		 *	(1) It's not being traced at all,
		 */
		if (!ISSET(t->p_slflag, PSL_TRACED)) {
			error = EPERM;
			break;
		}

		/*
		 *	(2) it's being traced by procfs (which has
		 *	    different signal delivery semantics),
		 */
		if (ISSET(t->p_slflag, PSL_FSTRACE)) {
			uprintf("file system traced\n");
			error = EBUSY;
			break;
		}

		/*
		 *	(3) it's not being traced by _you_, or
		 */
		if (t->p_pptr != p) {
			uprintf("parent %d != %d\n", t->p_pptr->p_pid, p->p_pid);
			error = EBUSY;
			break;
		}

		/*
		 *	(4) it's not currently stopped.
		 */
		if (t->p_stat != SSTOP || !t->p_waited /* XXXSMP */) {
			uprintf("stat %d flag %d\n", t->p_stat,
			    !t->p_waited);
			error = EBUSY;
			break;
		}
		break;

	default:			/* It was not a legal request. */
		error = EINVAL;
		break;
	}

	if (error == 0) {
		error = kauth_authorize_process(l->l_cred,
		    KAUTH_PROCESS_PTRACE, t, KAUTH_ARG(req),
		    NULL, NULL);
	}
	if (error == 0) {
		lt = lwp_find_first(t);
		if (lt == NULL)
			error = ESRCH;
	}

	if (error != 0) {
		mutex_exit(proc_lock);
		mutex_exit(t->p_lock);
		rw_exit(&t->p_reflock);
		return error;
	}

	/* Do single-step fixup if needed. */
	FIX_SSTEP(t);
	KASSERT(lt != NULL);
	lwp_addref(lt);

	/*
	 * Which locks do we need held? XXX Ugly.
	 */
	switch (req) {
#ifdef PT_STEP
	case PT_STEP:
#endif
	case PT_CONTINUE:
	case PT_DETACH:
	case PT_KILL:
	case PT_SYSCALL:
	case PT_SYSCALLEMU:
	case PT_ATTACH:
	case PT_TRACE_ME:
		pheld = 1;
		break;
	default:
		mutex_exit(proc_lock);
		mutex_exit(t->p_lock);
		pheld = 0;
		break;
	}

	/* Now do the operation. */
	write = 0;
	*retval = 0;
	tmp = 0;

	switch (req) {
	case  PT_TRACE_ME:
		/* Just set the trace flag. */
		SET(t->p_slflag, PSL_TRACED);
		t->p_opptr = t->p_pptr;
		break;

	case  PT_WRITE_I:		/* XXX no separate I and D spaces */
	case  PT_WRITE_D:
#if defined(__HAVE_RAS)
		/*
		 * Can't write to a RAS
		 */
		if (ras_lookup(t, SCARG(uap, addr)) != (void *)-1) {
			error = EACCES;
			break;
		}
#endif
		write = 1;
		tmp = SCARG(uap, data);
		/* FALLTHROUGH */

	case  PT_READ_I:		/* XXX no separate I and D spaces */
	case  PT_READ_D:
		/* write = 0 done above. */
		iov.iov_base = (void *)&tmp;
		iov.iov_len = sizeof(tmp);
		uio.uio_iov = &iov;
		uio.uio_iovcnt = 1;
		uio.uio_offset = (off_t)(unsigned long)SCARG(uap, addr);
		uio.uio_resid = sizeof(tmp);
		uio.uio_rw = write ? UIO_WRITE : UIO_READ;
		UIO_SETUP_SYSSPACE(&uio);

		error = process_domem(l, lt, &uio);
		if (!write)
			*retval = tmp;
		break;

	case  PT_IO:
		error = copyin(SCARG(uap, addr), &piod, sizeof(piod));
		if (error)
			break;
		switch (piod.piod_op) {
		case PIOD_READ_D:
		case PIOD_READ_I:
			uio.uio_rw = UIO_READ;
			break;
		case PIOD_WRITE_D:
		case PIOD_WRITE_I:
			/*
			 * Can't write to a RAS
			 */
			if (ras_lookup(t, SCARG(uap, addr)) != (void *)-1) {
				return (EACCES);
			}
			uio.uio_rw = UIO_WRITE;
			break;
		default:
			error = EINVAL;
			break;
		}
		if (error)
			break;
		error = proc_vmspace_getref(l->l_proc, &vm);
		if (error)
			break;
		iov.iov_base = piod.piod_addr;
		iov.iov_len = piod.piod_len;
		uio.uio_iov = &iov;
		uio.uio_iovcnt = 1;
		uio.uio_offset = (off_t)(unsigned long)piod.piod_offs;
		uio.uio_resid = piod.piod_len;
		uio.uio_vmspace = vm;

		error = process_domem(l, lt, &uio);
		piod.piod_len -= uio.uio_resid;
		(void) copyout(&piod, SCARG(uap, addr), sizeof(piod));
		uvmspace_free(vm);
		break;

#ifdef COREDUMP
	case  PT_DUMPCORE:
		if ((path = SCARG(uap, addr)) != NULL) {
			char *dst;
			int len = SCARG(uap, data);
			if (len < 0 || len >= MAXPATHLEN) {
				error = EINVAL;
				break;
			}
			dst = malloc(len + 1, M_TEMP, M_WAITOK);
			if ((error = copyin(path, dst, len)) != 0) {
				free(dst, M_TEMP);
				break;
			}
			path = dst;
			path[len] = '\0';
		}
		error = coredump(lt, path);
		if (path)
			free(path, M_TEMP);
		break;
#endif

#ifdef PT_STEP
	case  PT_STEP:
		/*
		 * From the 4.4BSD PRM:
		 * "Execution continues as in request PT_CONTINUE; however
		 * as soon as possible after execution of at least one
		 * instruction, execution stops again. [ ... ]"
		 */
#endif
	case  PT_CONTINUE:
	case  PT_SYSCALL:
	case  PT_DETACH:
		if (req == PT_SYSCALL) {
			if (!ISSET(t->p_slflag, PSL_SYSCALL)) {
				SET(t->p_slflag, PSL_SYSCALL);
#ifdef __HAVE_SYSCALL_INTERN
				(*t->p_emul->e_syscall_intern)(t);
#endif
			}
		} else {
			if (ISSET(t->p_slflag, PSL_SYSCALL)) {
				CLR(t->p_slflag, PSL_SYSCALL);
#ifdef __HAVE_SYSCALL_INTERN
				(*t->p_emul->e_syscall_intern)(t);
#endif
			}
		}
		t->p_trace_enabled = trace_is_enabled(t);

		/*
		 * From the 4.4BSD PRM:
		 * "The data argument is taken as a signal number and the
		 * child's execution continues at location addr as if it
		 * incurred that signal.  Normally the signal number will
		 * be either 0 to indicate that the signal that caused the
		 * stop should be ignored, or that value fetched out of
		 * the process's image indicating which signal caused
		 * the stop.  If addr is (int *)1 then execution continues
		 * from where it stopped."
		 */

		/* Check that the data is a valid signal number or zero. */
		if (SCARG(uap, data) < 0 || SCARG(uap, data) >= NSIG) {
			error = EINVAL;
			break;
		}

		uvm_lwp_hold(lt);

		/* If the address parameter is not (int *)1, set the pc. */
		if ((int *)SCARG(uap, addr) != (int *)1)
			if ((error = process_set_pc(lt, SCARG(uap, addr))) != 0) {
				uvm_lwp_rele(lt);
				break;
			}

#ifdef PT_STEP
		/*
		 * Arrange for a single-step, if that's requested and possible.
		 */
		error = process_sstep(lt, req == PT_STEP);
		if (error) {
			uvm_lwp_rele(lt);
			break;
		}
#endif

		uvm_lwp_rele(lt);

		if (req == PT_DETACH) {
			CLR(t->p_slflag, PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL);

			/* give process back to original parent or init */
			if (t->p_opptr != t->p_pptr) {
				struct proc *pp = t->p_opptr;
				proc_reparent(t, pp ? pp : initproc);
			}

			/* not being traced any more */
			t->p_opptr = NULL;
		}

		signo = SCARG(uap, data);
	sendsig:
		/* Finally, deliver the requested signal (or none). */
		if (t->p_stat == SSTOP) {
			/*
			 * Unstop the process.  If it needs to take a
			 * signal, make all efforts to ensure that at
			 * an LWP runs to see it.
			 */
			t->p_xstat = signo;
			proc_unstop(t);
		} else if (signo != 0) {
			KSI_INIT_EMPTY(&ksi);
			ksi.ksi_signo = signo;
			kpsignal2(t, &ksi);
		}
		break;

	case  PT_SYSCALLEMU:
		if (!ISSET(t->p_slflag, PSL_SYSCALL) || t->p_stat != SSTOP) {
			error = EINVAL;
			break;
		}
		SET(t->p_slflag, PSL_SYSCALLEMU);
		break;

	case  PT_KILL:
		/* just send the process a KILL signal. */
		signo = SIGKILL;
		goto sendsig;	/* in PT_CONTINUE, above. */

	case  PT_ATTACH:
		/*
		 * Go ahead and set the trace flag.
		 * Save the old parent (it's reset in
		 *   _DETACH, and also in kern_exit.c:wait4()
		 * Reparent the process so that the tracing
		 *   proc gets to see all the action.
		 * Stop the target.
		 */
		t->p_opptr = t->p_pptr;
		if (t->p_pptr != p) {
			struct proc *parent = t->p_pptr;

			if (parent->p_lock < t->p_lock) {
				if (!mutex_tryenter(parent->p_lock)) {
					mutex_exit(t->p_lock);
					mutex_enter(parent->p_lock);
				}
			} else if (parent->p_lock > t->p_lock) {
				mutex_enter(parent->p_lock);
			}
			parent->p_slflag |= PSL_CHTRACED;
			proc_reparent(t, p);
			if (parent->p_lock != t->p_lock)
				mutex_exit(parent->p_lock);
		}
		SET(t->p_slflag, PSL_TRACED);
		signo = SIGSTOP;
		goto sendsig;

	case PT_LWPINFO:
		if (SCARG(uap, data) != sizeof(pl)) {
			error = EINVAL;
			break;
		}
		error = copyin(SCARG(uap, addr), &pl, sizeof(pl));
		if (error)
			break;
		tmp = pl.pl_lwpid;
		lwp_delref(lt);
		mutex_enter(t->p_lock);
		if (tmp == 0)
			lt = lwp_find_first(t);
		else {
			lt = lwp_find(t, tmp);
			if (lt == NULL) {
				mutex_exit(t->p_lock);
				error = ESRCH;
				break;
			}
			lt = LIST_NEXT(lt, l_sibling);
		}
		while (lt != NULL && !lwp_alive(lt))
			lt = LIST_NEXT(lt, l_sibling);
		pl.pl_lwpid = 0;
		pl.pl_event = 0;
		if (lt) {
			lwp_addref(lt);
			pl.pl_lwpid = lt->l_lid;
			if (lt->l_lid == t->p_sigctx.ps_lwp)
				pl.pl_event = PL_EVENT_SIGNAL;
		}
		mutex_exit(t->p_lock);

		error = copyout(&pl, SCARG(uap, addr), sizeof(pl));
		break;

#ifdef PT_SETREGS
	case  PT_SETREGS:
		write = 1;
#endif
#ifdef PT_GETREGS
	case  PT_GETREGS:
		/* write = 0 done above. */
#endif
#if defined(PT_SETREGS) || defined(PT_GETREGS)
		tmp = SCARG(uap, data);
		if (tmp != 0 && t->p_nlwps > 1) {
			lwp_delref(lt);
			mutex_enter(t->p_lock);
			lt = lwp_find(t, tmp);
			if (lt == NULL) {
				mutex_exit(t->p_lock);
				error = ESRCH;
				break;
			}
			lwp_addref(lt);
			mutex_exit(t->p_lock);
		}
		if (!process_validregs(lt))
			error = EINVAL;
		else {
			error = proc_vmspace_getref(l->l_proc, &vm);
			if (error)
				break;
			iov.iov_base = SCARG(uap, addr);
			iov.iov_len = sizeof(struct reg);
			uio.uio_iov = &iov;
			uio.uio_iovcnt = 1;
			uio.uio_offset = 0;
			uio.uio_resid = sizeof(struct reg);
			uio.uio_rw = write ? UIO_WRITE : UIO_READ;
			uio.uio_vmspace = vm;

			error = process_doregs(l, lt, &uio);
			uvmspace_free(vm);
		}
		break;
#endif

#ifdef PT_SETFPREGS
	case  PT_SETFPREGS:
		write = 1;
#endif
#ifdef PT_GETFPREGS
	case  PT_GETFPREGS:
		/* write = 0 done above. */
#endif
#if defined(PT_SETFPREGS) || defined(PT_GETFPREGS)
		tmp = SCARG(uap, data);
		if (tmp != 0 && t->p_nlwps > 1) {
			lwp_delref(lt);
			mutex_enter(t->p_lock);
			lt = lwp_find(t, tmp);
			if (lt == NULL) {
				mutex_exit(t->p_lock);
				error = ESRCH;
				break;
			}
			lwp_addref(lt);
			mutex_exit(t->p_lock);
		}
		if (!process_validfpregs(lt))
			error = EINVAL;
		else {
			error = proc_vmspace_getref(l->l_proc, &vm);
			if (error)
				break;
			iov.iov_base = SCARG(uap, addr);
			iov.iov_len = sizeof(struct fpreg);
			uio.uio_iov = &iov;
			uio.uio_iovcnt = 1;
			uio.uio_offset = 0;
			uio.uio_resid = sizeof(struct fpreg);
			uio.uio_rw = write ? UIO_WRITE : UIO_READ;
			uio.uio_vmspace = vm;

			error = process_dofpregs(l, lt, &uio);
			uvmspace_free(vm);
		}
		break;
#endif

#ifdef __HAVE_PTRACE_MACHDEP
	PTRACE_MACHDEP_REQUEST_CASES
		error = ptrace_machdep_dorequest(l, lt,
		    req, SCARG(uap, addr), SCARG(uap, data));
		break;
#endif
	}

	if (pheld) {
		mutex_exit(t->p_lock);
		mutex_exit(proc_lock);
	}
	if (lt != NULL)
		lwp_delref(lt);
	rw_exit(&t->p_reflock);

	return error;
}

int
process_doregs(struct lwp *curl /*tracer*/,
    struct lwp *l /*traced*/,
    struct uio *uio)
{
#if defined(PT_GETREGS) || defined(PT_SETREGS)
	int error;
	struct reg r;
	char *kv;
	int kl;

	if (uio->uio_offset < 0 || uio->uio_offset > (off_t)sizeof(r))
		return EINVAL;

	kl = sizeof(r);
	kv = (char *)&r;

	kv += uio->uio_offset;
	kl -= uio->uio_offset;
	if ((size_t)kl > uio->uio_resid)
		kl = uio->uio_resid;

	uvm_lwp_hold(l);

	error = process_read_regs(l, &r);
	if (error == 0)
		error = uiomove(kv, kl, uio);
	if (error == 0 && uio->uio_rw == UIO_WRITE) {
		if (l->l_stat != LSSTOP)
			error = EBUSY;
		else
			error = process_write_regs(l, &r);
	}

	uvm_lwp_rele(l);

	uio->uio_offset = 0;
	return (error);
#else
	return (EINVAL);
#endif
}

int
process_validregs(struct lwp *l)
{

#if defined(PT_SETREGS) || defined(PT_GETREGS)
	return ((l->l_flag & LW_SYSTEM) == 0);
#else
	return (0);
#endif
}

int
process_dofpregs(struct lwp *curl /*tracer*/,
    struct lwp *l /*traced*/,
    struct uio *uio)
{
#if defined(PT_GETFPREGS) || defined(PT_SETFPREGS)
	int error;
	struct fpreg r;
	char *kv;
	int kl;

	if (uio->uio_offset < 0 || uio->uio_offset > (off_t)sizeof(r))
		return EINVAL;

	kl = sizeof(r);
	kv = (char *)&r;

	kv += uio->uio_offset;
	kl -= uio->uio_offset;
	if ((size_t)kl > uio->uio_resid)
		kl = uio->uio_resid;

	uvm_lwp_hold(l);

	error = process_read_fpregs(l, &r);
	if (error == 0)
		error = uiomove(kv, kl, uio);
	if (error == 0 && uio->uio_rw == UIO_WRITE) {
		if (l->l_stat != LSSTOP)
			error = EBUSY;
		else
			error = process_write_fpregs(l, &r);
	}

	uvm_lwp_rele(l);

	uio->uio_offset = 0;
	return (error);
#else
	return (EINVAL);
#endif
}

int
process_validfpregs(struct lwp *l)
{

#if defined(PT_SETFPREGS) || defined(PT_GETFPREGS)
	return ((l->l_flag & LW_SYSTEM) == 0);
#else
	return (0);
#endif
}
#endif /* PTRACE */

#if defined(KTRACE) || defined(PTRACE)
int
process_domem(struct lwp *curl /*tracer*/,
    struct lwp *l /*traced*/,
    struct uio *uio)
{
	struct proc *p = l->l_proc;	/* traced */
	struct vmspace *vm;
	int error;

	size_t len;
#ifdef PMAP_NEED_PROCWR
	vaddr_t	addr;
#endif

	error = 0;
	len = uio->uio_resid;

	if (len == 0)
		return (0);

#ifdef PMAP_NEED_PROCWR
	addr = uio->uio_offset;
#endif

	vm = p->p_vmspace;

	mutex_enter(&vm->vm_map.misc_lock);
	if ((l->l_flag & LW_WEXIT) || vm->vm_refcnt < 1)
		error = EFAULT;
	if (error == 0)
		p->p_vmspace->vm_refcnt++;  /* XXX */
	mutex_exit(&vm->vm_map.misc_lock);
	if (error != 0)
		return (error);
	error = uvm_io(&vm->vm_map, uio);
	uvmspace_free(vm);

#ifdef PMAP_NEED_PROCWR
	if (error == 0 && uio->uio_rw == UIO_WRITE)
		pmap_procwr(p, addr, len);
#endif
	return (error);
}
#endif /* KTRACE || PTRACE */

#if defined(KTRACE) || defined(PTRACE)
void
process_stoptrace(void)
{
	struct lwp *l = curlwp;
	struct proc *p = l->l_proc, *pp;

	mutex_enter(proc_lock);
	mutex_enter(p->p_lock);
	pp = p->p_pptr;
	if (pp->p_pid == 1) {
		CLR(p->p_slflag, PSL_SYSCALL);	/* XXXSMP */
		mutex_exit(p->p_lock);
		mutex_exit(proc_lock);
		return;
	}

	p->p_xstat = SIGTRAP;
	proc_stop(p, 1, SIGSTOP);
	mutex_exit(proc_lock);

	if (sigispending(l, 0)) {
		lwp_lock(l);
		l->l_flag |= LW_PENDSIG;
		lwp_unlock(l);
	}
	mutex_exit(p->p_lock);
}
#endif	/* KTRACE || PTRACE */