xref: /freebsd/sys/kern/sys_process.c (revision e92ffd9b626833ebdbf2742c8ffddc6cd94b963e)
1 /*-
2  * SPDX-License-Identifier: BSD-4-Clause
3  *
4  * Copyright (c) 1994, Sean Eric Fagan
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by Sean Eric Fagan.
18  * 4. The name of the author may not be used to endorse or promote products
19  *    derived from this software without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36 
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/ktr.h>
40 #include <sys/limits.h>
41 #include <sys/lock.h>
42 #include <sys/mutex.h>
43 #include <sys/reg.h>
44 #include <sys/syscallsubr.h>
45 #include <sys/sysent.h>
46 #include <sys/sysproto.h>
47 #include <sys/priv.h>
48 #include <sys/proc.h>
49 #include <sys/vnode.h>
50 #include <sys/ptrace.h>
51 #include <sys/rwlock.h>
52 #include <sys/sx.h>
53 #include <sys/malloc.h>
54 #include <sys/signalvar.h>
55 #include <sys/caprights.h>
56 #include <sys/filedesc.h>
57 
58 #include <security/audit/audit.h>
59 
60 #include <vm/vm.h>
61 #include <vm/pmap.h>
62 #include <vm/vm_extern.h>
63 #include <vm/vm_map.h>
64 #include <vm/vm_kern.h>
65 #include <vm/vm_object.h>
66 #include <vm/vm_page.h>
67 #include <vm/vm_param.h>
68 
69 #ifdef COMPAT_FREEBSD32
70 #include <sys/procfs.h>
71 #endif
72 
73 /*
74  * Functions implemented using PROC_ACTION():
75  *
76  * proc_read_regs(proc, regs)
77  *	Get the current user-visible register set from the process
78  *	and copy it into the regs structure (<machine/reg.h>).
79  *	The process is stopped at the time read_regs is called.
80  *
81  * proc_write_regs(proc, regs)
82  *	Update the current register set from the passed in regs
83  *	structure.  Take care to avoid clobbering special CPU
84  *	registers or privileged bits in the PSL.
85  *	Depending on the architecture this may have fix-up work to do,
86  *	especially if the IAR or PCW are modified.
87  *	The process is stopped at the time write_regs is called.
88  *
89  * proc_read_fpregs, proc_write_fpregs
90  *	deal with the floating point register set, otherwise as above.
91  *
92  * proc_read_dbregs, proc_write_dbregs
93  *	deal with the processor debug register set, otherwise as above.
94  *
95  * proc_sstep(proc)
96  *	Arrange for the process to trap after executing a single instruction.
97  */
98 
99 #define	PROC_ACTION(action) do {					\
100 	int error;							\
101 									\
102 	PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);			\
103 	if ((td->td_proc->p_flag & P_INMEM) == 0)			\
104 		error = EIO;						\
105 	else								\
106 		error = (action);					\
107 	return (error);							\
108 } while (0)
109 
110 int
111 proc_read_regs(struct thread *td, struct reg *regs)
112 {
113 
114 	PROC_ACTION(fill_regs(td, regs));
115 }
116 
117 int
118 proc_write_regs(struct thread *td, struct reg *regs)
119 {
120 
121 	PROC_ACTION(set_regs(td, regs));
122 }
123 
124 int
125 proc_read_dbregs(struct thread *td, struct dbreg *dbregs)
126 {
127 
128 	PROC_ACTION(fill_dbregs(td, dbregs));
129 }
130 
131 int
132 proc_write_dbregs(struct thread *td, struct dbreg *dbregs)
133 {
134 
135 	PROC_ACTION(set_dbregs(td, dbregs));
136 }
137 
138 /*
139  * Ptrace doesn't support fpregs at all, and there are no security holes
140  * or translations for fpregs, so we can just copy them.
141  */
142 int
143 proc_read_fpregs(struct thread *td, struct fpreg *fpregs)
144 {
145 
146 	PROC_ACTION(fill_fpregs(td, fpregs));
147 }
148 
149 int
150 proc_write_fpregs(struct thread *td, struct fpreg *fpregs)
151 {
152 
153 	PROC_ACTION(set_fpregs(td, fpregs));
154 }
155 
156 #ifdef COMPAT_FREEBSD32
157 /* For 32 bit binaries, we need to expose the 32 bit regs layouts. */
158 int
159 proc_read_regs32(struct thread *td, struct reg32 *regs32)
160 {
161 
162 	PROC_ACTION(fill_regs32(td, regs32));
163 }
164 
165 int
166 proc_write_regs32(struct thread *td, struct reg32 *regs32)
167 {
168 
169 	PROC_ACTION(set_regs32(td, regs32));
170 }
171 
172 int
173 proc_read_dbregs32(struct thread *td, struct dbreg32 *dbregs32)
174 {
175 
176 	PROC_ACTION(fill_dbregs32(td, dbregs32));
177 }
178 
179 int
180 proc_write_dbregs32(struct thread *td, struct dbreg32 *dbregs32)
181 {
182 
183 	PROC_ACTION(set_dbregs32(td, dbregs32));
184 }
185 
186 int
187 proc_read_fpregs32(struct thread *td, struct fpreg32 *fpregs32)
188 {
189 
190 	PROC_ACTION(fill_fpregs32(td, fpregs32));
191 }
192 
193 int
194 proc_write_fpregs32(struct thread *td, struct fpreg32 *fpregs32)
195 {
196 
197 	PROC_ACTION(set_fpregs32(td, fpregs32));
198 }
199 #endif
200 
201 int
202 proc_sstep(struct thread *td)
203 {
204 
205 	PROC_ACTION(ptrace_single_step(td));
206 }
207 
208 int
209 proc_rwmem(struct proc *p, struct uio *uio)
210 {
211 	vm_map_t map;
212 	vm_offset_t pageno;		/* page number */
213 	vm_prot_t reqprot;
214 	int error, fault_flags, page_offset, writing;
215 
216 	/*
217 	 * Assert that someone has locked this vmspace.  (Should be
218 	 * curthread but we can't assert that.)  This keeps the process
219 	 * from exiting out from under us until this operation completes.
220 	 */
221 	PROC_ASSERT_HELD(p);
222 	PROC_LOCK_ASSERT(p, MA_NOTOWNED);
223 
224 	/*
225 	 * The map we want...
226 	 */
227 	map = &p->p_vmspace->vm_map;
228 
229 	/*
230 	 * If we are writing, then we request vm_fault() to create a private
231 	 * copy of each page.  Since these copies will not be writeable by the
232 	 * process, we must explicity request that they be dirtied.
233 	 */
234 	writing = uio->uio_rw == UIO_WRITE;
235 	reqprot = writing ? VM_PROT_COPY | VM_PROT_READ : VM_PROT_READ;
236 	fault_flags = writing ? VM_FAULT_DIRTY : VM_FAULT_NORMAL;
237 
238 	/*
239 	 * Only map in one page at a time.  We don't have to, but it
240 	 * makes things easier.  This way is trivial - right?
241 	 */
242 	do {
243 		vm_offset_t uva;
244 		u_int len;
245 		vm_page_t m;
246 
247 		uva = (vm_offset_t)uio->uio_offset;
248 
249 		/*
250 		 * Get the page number of this segment.
251 		 */
252 		pageno = trunc_page(uva);
253 		page_offset = uva - pageno;
254 
255 		/*
256 		 * How many bytes to copy
257 		 */
258 		len = min(PAGE_SIZE - page_offset, uio->uio_resid);
259 
260 		/*
261 		 * Fault and hold the page on behalf of the process.
262 		 */
263 		error = vm_fault(map, pageno, reqprot, fault_flags, &m);
264 		if (error != KERN_SUCCESS) {
265 			if (error == KERN_RESOURCE_SHORTAGE)
266 				error = ENOMEM;
267 			else
268 				error = EFAULT;
269 			break;
270 		}
271 
272 		/*
273 		 * Now do the i/o move.
274 		 */
275 		error = uiomove_fromphys(&m, page_offset, len, uio);
276 
277 		/* Make the I-cache coherent for breakpoints. */
278 		if (writing && error == 0) {
279 			vm_map_lock_read(map);
280 			if (vm_map_check_protection(map, pageno, pageno +
281 			    PAGE_SIZE, VM_PROT_EXECUTE))
282 				vm_sync_icache(map, uva, len);
283 			vm_map_unlock_read(map);
284 		}
285 
286 		/*
287 		 * Release the page.
288 		 */
289 		vm_page_unwire(m, PQ_ACTIVE);
290 
291 	} while (error == 0 && uio->uio_resid > 0);
292 
293 	return (error);
294 }
295 
296 static ssize_t
297 proc_iop(struct thread *td, struct proc *p, vm_offset_t va, void *buf,
298     size_t len, enum uio_rw rw)
299 {
300 	struct iovec iov;
301 	struct uio uio;
302 	ssize_t slen;
303 
304 	MPASS(len < SSIZE_MAX);
305 	slen = (ssize_t)len;
306 
307 	iov.iov_base = (caddr_t)buf;
308 	iov.iov_len = len;
309 	uio.uio_iov = &iov;
310 	uio.uio_iovcnt = 1;
311 	uio.uio_offset = va;
312 	uio.uio_resid = slen;
313 	uio.uio_segflg = UIO_SYSSPACE;
314 	uio.uio_rw = rw;
315 	uio.uio_td = td;
316 	proc_rwmem(p, &uio);
317 	if (uio.uio_resid == slen)
318 		return (-1);
319 	return (slen - uio.uio_resid);
320 }
321 
322 ssize_t
323 proc_readmem(struct thread *td, struct proc *p, vm_offset_t va, void *buf,
324     size_t len)
325 {
326 
327 	return (proc_iop(td, p, va, buf, len, UIO_READ));
328 }
329 
330 ssize_t
331 proc_writemem(struct thread *td, struct proc *p, vm_offset_t va, void *buf,
332     size_t len)
333 {
334 
335 	return (proc_iop(td, p, va, buf, len, UIO_WRITE));
336 }
337 
338 static int
339 ptrace_vm_entry(struct thread *td, struct proc *p, struct ptrace_vm_entry *pve)
340 {
341 	struct vattr vattr;
342 	vm_map_t map;
343 	vm_map_entry_t entry;
344 	vm_object_t obj, tobj, lobj;
345 	struct vmspace *vm;
346 	struct vnode *vp;
347 	char *freepath, *fullpath;
348 	u_int pathlen;
349 	int error, index;
350 
351 	error = 0;
352 	obj = NULL;
353 
354 	vm = vmspace_acquire_ref(p);
355 	map = &vm->vm_map;
356 	vm_map_lock_read(map);
357 
358 	do {
359 		KASSERT((map->header.eflags & MAP_ENTRY_IS_SUB_MAP) == 0,
360 		    ("Submap in map header"));
361 		index = 0;
362 		VM_MAP_ENTRY_FOREACH(entry, map) {
363 			if (index >= pve->pve_entry &&
364 			    (entry->eflags & MAP_ENTRY_IS_SUB_MAP) == 0)
365 				break;
366 			index++;
367 		}
368 		if (index < pve->pve_entry) {
369 			error = EINVAL;
370 			break;
371 		}
372 		if (entry == &map->header) {
373 			error = ENOENT;
374 			break;
375 		}
376 
377 		/* We got an entry. */
378 		pve->pve_entry = index + 1;
379 		pve->pve_timestamp = map->timestamp;
380 		pve->pve_start = entry->start;
381 		pve->pve_end = entry->end - 1;
382 		pve->pve_offset = entry->offset;
383 		pve->pve_prot = entry->protection;
384 
385 		/* Backing object's path needed? */
386 		if (pve->pve_pathlen == 0)
387 			break;
388 
389 		pathlen = pve->pve_pathlen;
390 		pve->pve_pathlen = 0;
391 
392 		obj = entry->object.vm_object;
393 		if (obj != NULL)
394 			VM_OBJECT_RLOCK(obj);
395 	} while (0);
396 
397 	vm_map_unlock_read(map);
398 
399 	pve->pve_fsid = VNOVAL;
400 	pve->pve_fileid = VNOVAL;
401 
402 	if (error == 0 && obj != NULL) {
403 		lobj = obj;
404 		for (tobj = obj; tobj != NULL; tobj = tobj->backing_object) {
405 			if (tobj != obj)
406 				VM_OBJECT_RLOCK(tobj);
407 			if (lobj != obj)
408 				VM_OBJECT_RUNLOCK(lobj);
409 			lobj = tobj;
410 			pve->pve_offset += tobj->backing_object_offset;
411 		}
412 		vp = vm_object_vnode(lobj);
413 		if (vp != NULL)
414 			vref(vp);
415 		if (lobj != obj)
416 			VM_OBJECT_RUNLOCK(lobj);
417 		VM_OBJECT_RUNLOCK(obj);
418 
419 		if (vp != NULL) {
420 			freepath = NULL;
421 			fullpath = NULL;
422 			vn_fullpath(vp, &fullpath, &freepath);
423 			vn_lock(vp, LK_SHARED | LK_RETRY);
424 			if (VOP_GETATTR(vp, &vattr, td->td_ucred) == 0) {
425 				pve->pve_fileid = vattr.va_fileid;
426 				pve->pve_fsid = vattr.va_fsid;
427 			}
428 			vput(vp);
429 
430 			if (fullpath != NULL) {
431 				pve->pve_pathlen = strlen(fullpath) + 1;
432 				if (pve->pve_pathlen <= pathlen) {
433 					error = copyout(fullpath, pve->pve_path,
434 					    pve->pve_pathlen);
435 				} else
436 					error = ENAMETOOLONG;
437 			}
438 			if (freepath != NULL)
439 				free(freepath, M_TEMP);
440 		}
441 	}
442 	vmspace_free(vm);
443 	if (error == 0)
444 		CTR3(KTR_PTRACE, "PT_VM_ENTRY: pid %d, entry %d, start %p",
445 		    p->p_pid, pve->pve_entry, pve->pve_start);
446 
447 	return (error);
448 }
449 
450 /*
451  * Process debugging system call.
452  */
453 #ifndef _SYS_SYSPROTO_H_
454 struct ptrace_args {
455 	int	req;
456 	pid_t	pid;
457 	caddr_t	addr;
458 	int	data;
459 };
460 #endif
461 
462 int
463 sys_ptrace(struct thread *td, struct ptrace_args *uap)
464 {
465 	/*
466 	 * XXX this obfuscation is to reduce stack usage, but the register
467 	 * structs may be too large to put on the stack anyway.
468 	 */
469 	union {
470 		struct ptrace_io_desc piod;
471 		struct ptrace_lwpinfo pl;
472 		struct ptrace_vm_entry pve;
473 		struct ptrace_coredump pc;
474 		struct dbreg dbreg;
475 		struct fpreg fpreg;
476 		struct reg reg;
477 		char args[sizeof(td->td_sa.args)];
478 		struct ptrace_sc_ret psr;
479 		int ptevents;
480 	} r;
481 	void *addr;
482 	int error;
483 
484 	if (!allow_ptrace)
485 		return (ENOSYS);
486 	error = 0;
487 
488 	AUDIT_ARG_PID(uap->pid);
489 	AUDIT_ARG_CMD(uap->req);
490 	AUDIT_ARG_VALUE(uap->data);
491 	addr = &r;
492 	switch (uap->req) {
493 	case PT_GET_EVENT_MASK:
494 	case PT_LWPINFO:
495 	case PT_GET_SC_ARGS:
496 	case PT_GET_SC_RET:
497 		break;
498 	case PT_GETREGS:
499 		bzero(&r.reg, sizeof(r.reg));
500 		break;
501 	case PT_GETFPREGS:
502 		bzero(&r.fpreg, sizeof(r.fpreg));
503 		break;
504 	case PT_GETDBREGS:
505 		bzero(&r.dbreg, sizeof(r.dbreg));
506 		break;
507 	case PT_SETREGS:
508 		error = copyin(uap->addr, &r.reg, sizeof(r.reg));
509 		break;
510 	case PT_SETFPREGS:
511 		error = copyin(uap->addr, &r.fpreg, sizeof(r.fpreg));
512 		break;
513 	case PT_SETDBREGS:
514 		error = copyin(uap->addr, &r.dbreg, sizeof(r.dbreg));
515 		break;
516 	case PT_SET_EVENT_MASK:
517 		if (uap->data != sizeof(r.ptevents))
518 			error = EINVAL;
519 		else
520 			error = copyin(uap->addr, &r.ptevents, uap->data);
521 		break;
522 	case PT_IO:
523 		error = copyin(uap->addr, &r.piod, sizeof(r.piod));
524 		break;
525 	case PT_VM_ENTRY:
526 		error = copyin(uap->addr, &r.pve, sizeof(r.pve));
527 		break;
528 	case PT_COREDUMP:
529 		if (uap->data != sizeof(r.pc))
530 			error = EINVAL;
531 		else
532 			error = copyin(uap->addr, &r.pc, uap->data);
533 		break;
534 	default:
535 		addr = uap->addr;
536 		break;
537 	}
538 	if (error)
539 		return (error);
540 
541 	error = kern_ptrace(td, uap->req, uap->pid, addr, uap->data);
542 	if (error)
543 		return (error);
544 
545 	switch (uap->req) {
546 	case PT_VM_ENTRY:
547 		error = copyout(&r.pve, uap->addr, sizeof(r.pve));
548 		break;
549 	case PT_IO:
550 		error = copyout(&r.piod, uap->addr, sizeof(r.piod));
551 		break;
552 	case PT_GETREGS:
553 		error = copyout(&r.reg, uap->addr, sizeof(r.reg));
554 		break;
555 	case PT_GETFPREGS:
556 		error = copyout(&r.fpreg, uap->addr, sizeof(r.fpreg));
557 		break;
558 	case PT_GETDBREGS:
559 		error = copyout(&r.dbreg, uap->addr, sizeof(r.dbreg));
560 		break;
561 	case PT_GET_EVENT_MASK:
562 		/* NB: The size in uap->data is validated in kern_ptrace(). */
563 		error = copyout(&r.ptevents, uap->addr, uap->data);
564 		break;
565 	case PT_LWPINFO:
566 		/* NB: The size in uap->data is validated in kern_ptrace(). */
567 		error = copyout(&r.pl, uap->addr, uap->data);
568 		break;
569 	case PT_GET_SC_ARGS:
570 		error = copyout(r.args, uap->addr, MIN(uap->data,
571 		    sizeof(r.args)));
572 		break;
573 	case PT_GET_SC_RET:
574 		error = copyout(&r.psr, uap->addr, MIN(uap->data,
575 		    sizeof(r.psr)));
576 		break;
577 	}
578 
579 	return (error);
580 }
581 
582 #ifdef COMPAT_FREEBSD32
583 /*
584  *   PROC_READ(regs, td2, addr);
585  * becomes either:
586  *   proc_read_regs(td2, addr);
587  * or
588  *   proc_read_regs32(td2, addr);
589  * .. except this is done at runtime.  There is an additional
590  * complication in that PROC_WRITE disallows 32 bit consumers
591  * from writing to 64 bit address space targets.
592  */
593 #define	PROC_READ(w, t, a)	wrap32 ? \
594 	proc_read_ ## w ## 32(t, a) : \
595 	proc_read_ ## w (t, a)
596 #define	PROC_WRITE(w, t, a)	wrap32 ? \
597 	(safe ? proc_write_ ## w ## 32(t, a) : EINVAL ) : \
598 	proc_write_ ## w (t, a)
599 #else
600 #define	PROC_READ(w, t, a)	proc_read_ ## w (t, a)
601 #define	PROC_WRITE(w, t, a)	proc_write_ ## w (t, a)
602 #endif
603 
604 void
605 proc_set_traced(struct proc *p, bool stop)
606 {
607 
608 	sx_assert(&proctree_lock, SX_XLOCKED);
609 	PROC_LOCK_ASSERT(p, MA_OWNED);
610 	p->p_flag |= P_TRACED;
611 	if (stop)
612 		p->p_flag2 |= P2_PTRACE_FSTP;
613 	p->p_ptevents = PTRACE_DEFAULT;
614 }
615 
616 void
617 ptrace_unsuspend(struct proc *p)
618 {
619 	PROC_LOCK_ASSERT(p, MA_OWNED);
620 
621 	PROC_SLOCK(p);
622 	p->p_flag &= ~(P_STOPPED_TRACE | P_STOPPED_SIG | P_WAITED);
623 	thread_unsuspend(p);
624 	PROC_SUNLOCK(p);
625 	itimer_proc_continue(p);
626 	kqtimer_proc_continue(p);
627 }
628 
629 static int
630 proc_can_ptrace(struct thread *td, struct proc *p)
631 {
632 	int error;
633 
634 	PROC_LOCK_ASSERT(p, MA_OWNED);
635 
636 	if ((p->p_flag & P_WEXIT) != 0)
637 		return (ESRCH);
638 
639 	if ((error = p_cansee(td, p)) != 0)
640 		return (error);
641 	if ((error = p_candebug(td, p)) != 0)
642 		return (error);
643 
644 	/* not being traced... */
645 	if ((p->p_flag & P_TRACED) == 0)
646 		return (EPERM);
647 
648 	/* not being traced by YOU */
649 	if (p->p_pptr != td->td_proc)
650 		return (EBUSY);
651 
652 	/* not currently stopped */
653 	if ((p->p_flag & P_STOPPED_TRACE) == 0 ||
654 	    p->p_suspcount != p->p_numthreads  ||
655 	    (p->p_flag & P_WAITED) == 0)
656 		return (EBUSY);
657 
658 	return (0);
659 }
660 
661 static struct thread *
662 ptrace_sel_coredump_thread(struct proc *p)
663 {
664 	struct thread *td2;
665 
666 	PROC_LOCK_ASSERT(p, MA_OWNED);
667 	MPASS((p->p_flag & P_STOPPED_TRACE) != 0);
668 
669 	FOREACH_THREAD_IN_PROC(p, td2) {
670 		if ((td2->td_dbgflags & TDB_SSWITCH) != 0)
671 			return (td2);
672 	}
673 	return (NULL);
674 }
675 
676 int
677 kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
678 {
679 	struct iovec iov;
680 	struct uio uio;
681 	struct proc *curp, *p, *pp;
682 	struct thread *td2 = NULL, *td3;
683 	struct ptrace_io_desc *piod = NULL;
684 	struct ptrace_lwpinfo *pl;
685 	struct ptrace_sc_ret *psr;
686 	struct file *fp;
687 	struct ptrace_coredump *pc;
688 	struct thr_coredump_req *tcq;
689 	int error, num, tmp;
690 	lwpid_t tid = 0, *buf;
691 #ifdef COMPAT_FREEBSD32
692 	int wrap32 = 0, safe = 0;
693 #endif
694 	bool proctree_locked, p2_req_set;
695 
696 	curp = td->td_proc;
697 	proctree_locked = false;
698 	p2_req_set = false;
699 
700 	/* Lock proctree before locking the process. */
701 	switch (req) {
702 	case PT_TRACE_ME:
703 	case PT_ATTACH:
704 	case PT_STEP:
705 	case PT_CONTINUE:
706 	case PT_TO_SCE:
707 	case PT_TO_SCX:
708 	case PT_SYSCALL:
709 	case PT_FOLLOW_FORK:
710 	case PT_LWP_EVENTS:
711 	case PT_GET_EVENT_MASK:
712 	case PT_SET_EVENT_MASK:
713 	case PT_DETACH:
714 	case PT_GET_SC_ARGS:
715 		sx_xlock(&proctree_lock);
716 		proctree_locked = true;
717 		break;
718 	default:
719 		break;
720 	}
721 
722 	if (req == PT_TRACE_ME) {
723 		p = td->td_proc;
724 		PROC_LOCK(p);
725 	} else {
726 		if (pid <= PID_MAX) {
727 			if ((p = pfind(pid)) == NULL) {
728 				if (proctree_locked)
729 					sx_xunlock(&proctree_lock);
730 				return (ESRCH);
731 			}
732 		} else {
733 			td2 = tdfind(pid, -1);
734 			if (td2 == NULL) {
735 				if (proctree_locked)
736 					sx_xunlock(&proctree_lock);
737 				return (ESRCH);
738 			}
739 			p = td2->td_proc;
740 			tid = pid;
741 			pid = p->p_pid;
742 		}
743 	}
744 	AUDIT_ARG_PROCESS(p);
745 
746 	if ((p->p_flag & P_WEXIT) != 0) {
747 		error = ESRCH;
748 		goto fail;
749 	}
750 	if ((error = p_cansee(td, p)) != 0)
751 		goto fail;
752 
753 	if ((error = p_candebug(td, p)) != 0)
754 		goto fail;
755 
756 	/*
757 	 * System processes can't be debugged.
758 	 */
759 	if ((p->p_flag & P_SYSTEM) != 0) {
760 		error = EINVAL;
761 		goto fail;
762 	}
763 
764 	if (tid == 0) {
765 		if ((p->p_flag & P_STOPPED_TRACE) != 0) {
766 			KASSERT(p->p_xthread != NULL, ("NULL p_xthread"));
767 			td2 = p->p_xthread;
768 		} else {
769 			td2 = FIRST_THREAD_IN_PROC(p);
770 		}
771 		tid = td2->td_tid;
772 	}
773 
774 #ifdef COMPAT_FREEBSD32
775 	/*
776 	 * Test if we're a 32 bit client and what the target is.
777 	 * Set the wrap controls accordingly.
778 	 */
779 	if (SV_CURPROC_FLAG(SV_ILP32)) {
780 		if (SV_PROC_FLAG(td2->td_proc, SV_ILP32))
781 			safe = 1;
782 		wrap32 = 1;
783 	}
784 #endif
785 	/*
786 	 * Permissions check
787 	 */
788 	switch (req) {
789 	case PT_TRACE_ME:
790 		/*
791 		 * Always legal, when there is a parent process which
792 		 * could trace us.  Otherwise, reject.
793 		 */
794 		if ((p->p_flag & P_TRACED) != 0) {
795 			error = EBUSY;
796 			goto fail;
797 		}
798 		if (p->p_pptr == initproc) {
799 			error = EPERM;
800 			goto fail;
801 		}
802 		break;
803 
804 	case PT_ATTACH:
805 		/* Self */
806 		if (p == td->td_proc) {
807 			error = EINVAL;
808 			goto fail;
809 		}
810 
811 		/* Already traced */
812 		if (p->p_flag & P_TRACED) {
813 			error = EBUSY;
814 			goto fail;
815 		}
816 
817 		/* Can't trace an ancestor if you're being traced. */
818 		if (curp->p_flag & P_TRACED) {
819 			for (pp = curp->p_pptr; pp != NULL; pp = pp->p_pptr) {
820 				if (pp == p) {
821 					error = EINVAL;
822 					goto fail;
823 				}
824 			}
825 		}
826 
827 		/* OK */
828 		break;
829 
830 	case PT_CLEARSTEP:
831 		/* Allow thread to clear single step for itself */
832 		if (td->td_tid == tid)
833 			break;
834 
835 		/* FALLTHROUGH */
836 	default:
837 		/*
838 		 * Check for ptrace eligibility before waiting for
839 		 * holds to drain.
840 		 */
841 		error = proc_can_ptrace(td, p);
842 		if (error != 0)
843 			goto fail;
844 
845 		/*
846 		 * Block parallel ptrace requests.  Most important, do
847 		 * not allow other thread in debugger to continue the
848 		 * debuggee until coredump finished.
849 		 */
850 		while ((p->p_flag2 & P2_PTRACEREQ) != 0) {
851 			if (proctree_locked)
852 				sx_xunlock(&proctree_lock);
853 			error = msleep(&p->p_flag2, &p->p_mtx, PPAUSE | PCATCH |
854 			    (proctree_locked ? PDROP : 0), "pptrace", 0);
855 			if (proctree_locked) {
856 				sx_xlock(&proctree_lock);
857 				PROC_LOCK(p);
858 			}
859 			if (error == 0 && td2->td_proc != p)
860 				error = ESRCH;
861 			if (error == 0)
862 				error = proc_can_ptrace(td, p);
863 			if (error != 0)
864 				goto fail;
865 		}
866 
867 		/* Ok */
868 		break;
869 	}
870 
871 	/*
872 	 * Keep this process around and request parallel ptrace()
873 	 * request to wait until we finish this request.
874 	 */
875 	MPASS((p->p_flag2 & P2_PTRACEREQ) == 0);
876 	p->p_flag2 |= P2_PTRACEREQ;
877 	p2_req_set = true;
878 	_PHOLD(p);
879 
880 	/*
881 	 * Actually do the requests
882 	 */
883 
884 	td->td_retval[0] = 0;
885 
886 	switch (req) {
887 	case PT_TRACE_ME:
888 		/* set my trace flag and "owner" so it can read/write me */
889 		proc_set_traced(p, false);
890 		if (p->p_flag & P_PPWAIT)
891 			p->p_flag |= P_PPTRACE;
892 		CTR1(KTR_PTRACE, "PT_TRACE_ME: pid %d", p->p_pid);
893 		break;
894 
895 	case PT_ATTACH:
896 		/* security check done above */
897 		/*
898 		 * It would be nice if the tracing relationship was separate
899 		 * from the parent relationship but that would require
900 		 * another set of links in the proc struct or for "wait"
901 		 * to scan the entire proc table.  To make life easier,
902 		 * we just re-parent the process we're trying to trace.
903 		 * The old parent is remembered so we can put things back
904 		 * on a "detach".
905 		 */
906 		proc_set_traced(p, true);
907 		proc_reparent(p, td->td_proc, false);
908 		CTR2(KTR_PTRACE, "PT_ATTACH: pid %d, oppid %d", p->p_pid,
909 		    p->p_oppid);
910 
911 		sx_xunlock(&proctree_lock);
912 		proctree_locked = false;
913 		MPASS(p->p_xthread == NULL);
914 		MPASS((p->p_flag & P_STOPPED_TRACE) == 0);
915 
916 		/*
917 		 * If already stopped due to a stop signal, clear the
918 		 * existing stop before triggering a traced SIGSTOP.
919 		 */
920 		if ((p->p_flag & P_STOPPED_SIG) != 0) {
921 			PROC_SLOCK(p);
922 			p->p_flag &= ~(P_STOPPED_SIG | P_WAITED);
923 			thread_unsuspend(p);
924 			PROC_SUNLOCK(p);
925 		}
926 
927 		kern_psignal(p, SIGSTOP);
928 		break;
929 
930 	case PT_CLEARSTEP:
931 		CTR2(KTR_PTRACE, "PT_CLEARSTEP: tid %d (pid %d)", td2->td_tid,
932 		    p->p_pid);
933 		error = ptrace_clear_single_step(td2);
934 		break;
935 
936 	case PT_SETSTEP:
937 		CTR2(KTR_PTRACE, "PT_SETSTEP: tid %d (pid %d)", td2->td_tid,
938 		    p->p_pid);
939 		error = ptrace_single_step(td2);
940 		break;
941 
942 	case PT_SUSPEND:
943 		CTR2(KTR_PTRACE, "PT_SUSPEND: tid %d (pid %d)", td2->td_tid,
944 		    p->p_pid);
945 		td2->td_dbgflags |= TDB_SUSPEND;
946 		thread_lock(td2);
947 		td2->td_flags |= TDF_NEEDSUSPCHK;
948 		thread_unlock(td2);
949 		break;
950 
951 	case PT_RESUME:
952 		CTR2(KTR_PTRACE, "PT_RESUME: tid %d (pid %d)", td2->td_tid,
953 		    p->p_pid);
954 		td2->td_dbgflags &= ~TDB_SUSPEND;
955 		break;
956 
957 	case PT_FOLLOW_FORK:
958 		CTR3(KTR_PTRACE, "PT_FOLLOW_FORK: pid %d %s -> %s", p->p_pid,
959 		    p->p_ptevents & PTRACE_FORK ? "enabled" : "disabled",
960 		    data ? "enabled" : "disabled");
961 		if (data)
962 			p->p_ptevents |= PTRACE_FORK;
963 		else
964 			p->p_ptevents &= ~PTRACE_FORK;
965 		break;
966 
967 	case PT_LWP_EVENTS:
968 		CTR3(KTR_PTRACE, "PT_LWP_EVENTS: pid %d %s -> %s", p->p_pid,
969 		    p->p_ptevents & PTRACE_LWP ? "enabled" : "disabled",
970 		    data ? "enabled" : "disabled");
971 		if (data)
972 			p->p_ptevents |= PTRACE_LWP;
973 		else
974 			p->p_ptevents &= ~PTRACE_LWP;
975 		break;
976 
977 	case PT_GET_EVENT_MASK:
978 		if (data != sizeof(p->p_ptevents)) {
979 			error = EINVAL;
980 			break;
981 		}
982 		CTR2(KTR_PTRACE, "PT_GET_EVENT_MASK: pid %d mask %#x", p->p_pid,
983 		    p->p_ptevents);
984 		*(int *)addr = p->p_ptevents;
985 		break;
986 
987 	case PT_SET_EVENT_MASK:
988 		if (data != sizeof(p->p_ptevents)) {
989 			error = EINVAL;
990 			break;
991 		}
992 		tmp = *(int *)addr;
993 		if ((tmp & ~(PTRACE_EXEC | PTRACE_SCE | PTRACE_SCX |
994 		    PTRACE_FORK | PTRACE_LWP | PTRACE_VFORK)) != 0) {
995 			error = EINVAL;
996 			break;
997 		}
998 		CTR3(KTR_PTRACE, "PT_SET_EVENT_MASK: pid %d mask %#x -> %#x",
999 		    p->p_pid, p->p_ptevents, tmp);
1000 		p->p_ptevents = tmp;
1001 		break;
1002 
1003 	case PT_GET_SC_ARGS:
1004 		CTR1(KTR_PTRACE, "PT_GET_SC_ARGS: pid %d", p->p_pid);
1005 		if ((td2->td_dbgflags & (TDB_SCE | TDB_SCX)) == 0
1006 #ifdef COMPAT_FREEBSD32
1007 		    || (wrap32 && !safe)
1008 #endif
1009 		    ) {
1010 			error = EINVAL;
1011 			break;
1012 		}
1013 		bzero(addr, sizeof(td2->td_sa.args));
1014 		/* See the explanation in linux_ptrace_get_syscall_info(). */
1015 		bcopy(td2->td_sa.args, addr, SV_PROC_ABI(td->td_proc) ==
1016 		    SV_ABI_LINUX ? sizeof(td2->td_sa.args) :
1017 		    td2->td_sa.callp->sy_narg * sizeof(register_t));
1018 		break;
1019 
1020 	case PT_GET_SC_RET:
1021 		if ((td2->td_dbgflags & (TDB_SCX)) == 0
1022 #ifdef COMPAT_FREEBSD32
1023 		    || (wrap32 && !safe)
1024 #endif
1025 		    ) {
1026 			error = EINVAL;
1027 			break;
1028 		}
1029 		psr = addr;
1030 		bzero(psr, sizeof(*psr));
1031 		psr->sr_error = td2->td_errno;
1032 		if (psr->sr_error == 0) {
1033 			psr->sr_retval[0] = td2->td_retval[0];
1034 			psr->sr_retval[1] = td2->td_retval[1];
1035 		}
1036 		CTR4(KTR_PTRACE,
1037 		    "PT_GET_SC_RET: pid %d error %d retval %#lx,%#lx",
1038 		    p->p_pid, psr->sr_error, psr->sr_retval[0],
1039 		    psr->sr_retval[1]);
1040 		break;
1041 
1042 	case PT_STEP:
1043 	case PT_CONTINUE:
1044 	case PT_TO_SCE:
1045 	case PT_TO_SCX:
1046 	case PT_SYSCALL:
1047 	case PT_DETACH:
1048 		/* Zero means do not send any signal */
1049 		if (data < 0 || data > _SIG_MAXSIG) {
1050 			error = EINVAL;
1051 			break;
1052 		}
1053 
1054 		switch (req) {
1055 		case PT_STEP:
1056 			CTR3(KTR_PTRACE, "PT_STEP: tid %d (pid %d), sig = %d",
1057 			    td2->td_tid, p->p_pid, data);
1058 			error = ptrace_single_step(td2);
1059 			if (error)
1060 				goto out;
1061 			break;
1062 		case PT_CONTINUE:
1063 		case PT_TO_SCE:
1064 		case PT_TO_SCX:
1065 		case PT_SYSCALL:
1066 			if (addr != (void *)1) {
1067 				error = ptrace_set_pc(td2,
1068 				    (u_long)(uintfptr_t)addr);
1069 				if (error)
1070 					goto out;
1071 			}
1072 			switch (req) {
1073 			case PT_TO_SCE:
1074 				p->p_ptevents |= PTRACE_SCE;
1075 				CTR4(KTR_PTRACE,
1076 		    "PT_TO_SCE: pid %d, events = %#x, PC = %#lx, sig = %d",
1077 				    p->p_pid, p->p_ptevents,
1078 				    (u_long)(uintfptr_t)addr, data);
1079 				break;
1080 			case PT_TO_SCX:
1081 				p->p_ptevents |= PTRACE_SCX;
1082 				CTR4(KTR_PTRACE,
1083 		    "PT_TO_SCX: pid %d, events = %#x, PC = %#lx, sig = %d",
1084 				    p->p_pid, p->p_ptevents,
1085 				    (u_long)(uintfptr_t)addr, data);
1086 				break;
1087 			case PT_SYSCALL:
1088 				p->p_ptevents |= PTRACE_SYSCALL;
1089 				CTR4(KTR_PTRACE,
1090 		    "PT_SYSCALL: pid %d, events = %#x, PC = %#lx, sig = %d",
1091 				    p->p_pid, p->p_ptevents,
1092 				    (u_long)(uintfptr_t)addr, data);
1093 				break;
1094 			case PT_CONTINUE:
1095 				CTR3(KTR_PTRACE,
1096 				    "PT_CONTINUE: pid %d, PC = %#lx, sig = %d",
1097 				    p->p_pid, (u_long)(uintfptr_t)addr, data);
1098 				break;
1099 			}
1100 			break;
1101 		case PT_DETACH:
1102 			/*
1103 			 * Clear P_TRACED before reparenting
1104 			 * a detached process back to its original
1105 			 * parent.  Otherwise the debugee will be set
1106 			 * as an orphan of the debugger.
1107 			 */
1108 			p->p_flag &= ~(P_TRACED | P_WAITED);
1109 
1110 			/*
1111 			 * Reset the process parent.
1112 			 */
1113 			if (p->p_oppid != p->p_pptr->p_pid) {
1114 				PROC_LOCK(p->p_pptr);
1115 				sigqueue_take(p->p_ksi);
1116 				PROC_UNLOCK(p->p_pptr);
1117 
1118 				pp = proc_realparent(p);
1119 				proc_reparent(p, pp, false);
1120 				if (pp == initproc)
1121 					p->p_sigparent = SIGCHLD;
1122 				CTR3(KTR_PTRACE,
1123 			    "PT_DETACH: pid %d reparented to pid %d, sig %d",
1124 				    p->p_pid, pp->p_pid, data);
1125 			} else {
1126 				CTR2(KTR_PTRACE, "PT_DETACH: pid %d, sig %d",
1127 				    p->p_pid, data);
1128 			}
1129 
1130 			p->p_ptevents = 0;
1131 			FOREACH_THREAD_IN_PROC(p, td3) {
1132 				if ((td3->td_dbgflags & TDB_FSTP) != 0) {
1133 					sigqueue_delete(&td3->td_sigqueue,
1134 					    SIGSTOP);
1135 				}
1136 				td3->td_dbgflags &= ~(TDB_XSIG | TDB_FSTP |
1137 				    TDB_SUSPEND);
1138 			}
1139 
1140 			if ((p->p_flag2 & P2_PTRACE_FSTP) != 0) {
1141 				sigqueue_delete(&p->p_sigqueue, SIGSTOP);
1142 				p->p_flag2 &= ~P2_PTRACE_FSTP;
1143 			}
1144 
1145 			/* should we send SIGCHLD? */
1146 			/* childproc_continued(p); */
1147 			break;
1148 		}
1149 
1150 		sx_xunlock(&proctree_lock);
1151 		proctree_locked = false;
1152 
1153 	sendsig:
1154 		MPASS(!proctree_locked);
1155 
1156 		/*
1157 		 * Clear the pending event for the thread that just
1158 		 * reported its event (p_xthread).  This may not be
1159 		 * the thread passed to PT_CONTINUE, PT_STEP, etc. if
1160 		 * the debugger is resuming a different thread.
1161 		 *
1162 		 * Deliver any pending signal via the reporting thread.
1163 		 */
1164 		MPASS(p->p_xthread != NULL);
1165 		p->p_xthread->td_dbgflags &= ~TDB_XSIG;
1166 		p->p_xthread->td_xsig = data;
1167 		p->p_xthread = NULL;
1168 		p->p_xsig = data;
1169 
1170 		/*
1171 		 * P_WKILLED is insurance that a PT_KILL/SIGKILL
1172 		 * always works immediately, even if another thread is
1173 		 * unsuspended first and attempts to handle a
1174 		 * different signal or if the POSIX.1b style signal
1175 		 * queue cannot accommodate any new signals.
1176 		 */
1177 		if (data == SIGKILL)
1178 			proc_wkilled(p);
1179 
1180 		/*
1181 		 * Unsuspend all threads.  To leave a thread
1182 		 * suspended, use PT_SUSPEND to suspend it before
1183 		 * continuing the process.
1184 		 */
1185 		ptrace_unsuspend(p);
1186 		break;
1187 
1188 	case PT_WRITE_I:
1189 	case PT_WRITE_D:
1190 		td2->td_dbgflags |= TDB_USERWR;
1191 		PROC_UNLOCK(p);
1192 		error = 0;
1193 		if (proc_writemem(td, p, (off_t)(uintptr_t)addr, &data,
1194 		    sizeof(int)) != sizeof(int))
1195 			error = ENOMEM;
1196 		else
1197 			CTR3(KTR_PTRACE, "PT_WRITE: pid %d: %p <= %#x",
1198 			    p->p_pid, addr, data);
1199 		PROC_LOCK(p);
1200 		break;
1201 
1202 	case PT_READ_I:
1203 	case PT_READ_D:
1204 		PROC_UNLOCK(p);
1205 		error = tmp = 0;
1206 		if (proc_readmem(td, p, (off_t)(uintptr_t)addr, &tmp,
1207 		    sizeof(int)) != sizeof(int))
1208 			error = ENOMEM;
1209 		else
1210 			CTR3(KTR_PTRACE, "PT_READ: pid %d: %p >= %#x",
1211 			    p->p_pid, addr, tmp);
1212 		td->td_retval[0] = tmp;
1213 		PROC_LOCK(p);
1214 		break;
1215 
1216 	case PT_IO:
1217 		piod = addr;
1218 		iov.iov_base = piod->piod_addr;
1219 		iov.iov_len = piod->piod_len;
1220 		uio.uio_offset = (off_t)(uintptr_t)piod->piod_offs;
1221 		uio.uio_resid = piod->piod_len;
1222 		uio.uio_iov = &iov;
1223 		uio.uio_iovcnt = 1;
1224 		uio.uio_segflg = UIO_USERSPACE;
1225 		uio.uio_td = td;
1226 		switch (piod->piod_op) {
1227 		case PIOD_READ_D:
1228 		case PIOD_READ_I:
1229 			CTR3(KTR_PTRACE, "PT_IO: pid %d: READ (%p, %#x)",
1230 			    p->p_pid, (uintptr_t)uio.uio_offset, uio.uio_resid);
1231 			uio.uio_rw = UIO_READ;
1232 			break;
1233 		case PIOD_WRITE_D:
1234 		case PIOD_WRITE_I:
1235 			CTR3(KTR_PTRACE, "PT_IO: pid %d: WRITE (%p, %#x)",
1236 			    p->p_pid, (uintptr_t)uio.uio_offset, uio.uio_resid);
1237 			td2->td_dbgflags |= TDB_USERWR;
1238 			uio.uio_rw = UIO_WRITE;
1239 			break;
1240 		default:
1241 			error = EINVAL;
1242 			goto out;
1243 		}
1244 		PROC_UNLOCK(p);
1245 		error = proc_rwmem(p, &uio);
1246 		piod->piod_len -= uio.uio_resid;
1247 		PROC_LOCK(p);
1248 		break;
1249 
1250 	case PT_KILL:
1251 		CTR1(KTR_PTRACE, "PT_KILL: pid %d", p->p_pid);
1252 		data = SIGKILL;
1253 		goto sendsig;	/* in PT_CONTINUE above */
1254 
1255 	case PT_SETREGS:
1256 		CTR2(KTR_PTRACE, "PT_SETREGS: tid %d (pid %d)", td2->td_tid,
1257 		    p->p_pid);
1258 		td2->td_dbgflags |= TDB_USERWR;
1259 		error = PROC_WRITE(regs, td2, addr);
1260 		break;
1261 
1262 	case PT_GETREGS:
1263 		CTR2(KTR_PTRACE, "PT_GETREGS: tid %d (pid %d)", td2->td_tid,
1264 		    p->p_pid);
1265 		error = PROC_READ(regs, td2, addr);
1266 		break;
1267 
1268 	case PT_SETFPREGS:
1269 		CTR2(KTR_PTRACE, "PT_SETFPREGS: tid %d (pid %d)", td2->td_tid,
1270 		    p->p_pid);
1271 		td2->td_dbgflags |= TDB_USERWR;
1272 		error = PROC_WRITE(fpregs, td2, addr);
1273 		break;
1274 
1275 	case PT_GETFPREGS:
1276 		CTR2(KTR_PTRACE, "PT_GETFPREGS: tid %d (pid %d)", td2->td_tid,
1277 		    p->p_pid);
1278 		error = PROC_READ(fpregs, td2, addr);
1279 		break;
1280 
1281 	case PT_SETDBREGS:
1282 		CTR2(KTR_PTRACE, "PT_SETDBREGS: tid %d (pid %d)", td2->td_tid,
1283 		    p->p_pid);
1284 		td2->td_dbgflags |= TDB_USERWR;
1285 		error = PROC_WRITE(dbregs, td2, addr);
1286 		break;
1287 
1288 	case PT_GETDBREGS:
1289 		CTR2(KTR_PTRACE, "PT_GETDBREGS: tid %d (pid %d)", td2->td_tid,
1290 		    p->p_pid);
1291 		error = PROC_READ(dbregs, td2, addr);
1292 		break;
1293 
1294 	case PT_LWPINFO:
1295 		if (data <= 0 || data > sizeof(*pl)) {
1296 			error = EINVAL;
1297 			break;
1298 		}
1299 		pl = addr;
1300 		bzero(pl, sizeof(*pl));
1301 		pl->pl_lwpid = td2->td_tid;
1302 		pl->pl_event = PL_EVENT_NONE;
1303 		pl->pl_flags = 0;
1304 		if (td2->td_dbgflags & TDB_XSIG) {
1305 			pl->pl_event = PL_EVENT_SIGNAL;
1306 			if (td2->td_si.si_signo != 0 &&
1307 			    data >= offsetof(struct ptrace_lwpinfo, pl_siginfo)
1308 			    + sizeof(pl->pl_siginfo)){
1309 				pl->pl_flags |= PL_FLAG_SI;
1310 				pl->pl_siginfo = td2->td_si;
1311 			}
1312 		}
1313 		if (td2->td_dbgflags & TDB_SCE)
1314 			pl->pl_flags |= PL_FLAG_SCE;
1315 		else if (td2->td_dbgflags & TDB_SCX)
1316 			pl->pl_flags |= PL_FLAG_SCX;
1317 		if (td2->td_dbgflags & TDB_EXEC)
1318 			pl->pl_flags |= PL_FLAG_EXEC;
1319 		if (td2->td_dbgflags & TDB_FORK) {
1320 			pl->pl_flags |= PL_FLAG_FORKED;
1321 			pl->pl_child_pid = td2->td_dbg_forked;
1322 			if (td2->td_dbgflags & TDB_VFORK)
1323 				pl->pl_flags |= PL_FLAG_VFORKED;
1324 		} else if ((td2->td_dbgflags & (TDB_SCX | TDB_VFORK)) ==
1325 		    TDB_VFORK)
1326 			pl->pl_flags |= PL_FLAG_VFORK_DONE;
1327 		if (td2->td_dbgflags & TDB_CHILD)
1328 			pl->pl_flags |= PL_FLAG_CHILD;
1329 		if (td2->td_dbgflags & TDB_BORN)
1330 			pl->pl_flags |= PL_FLAG_BORN;
1331 		if (td2->td_dbgflags & TDB_EXIT)
1332 			pl->pl_flags |= PL_FLAG_EXITED;
1333 		pl->pl_sigmask = td2->td_sigmask;
1334 		pl->pl_siglist = td2->td_siglist;
1335 		strcpy(pl->pl_tdname, td2->td_name);
1336 		if ((td2->td_dbgflags & (TDB_SCE | TDB_SCX)) != 0) {
1337 			pl->pl_syscall_code = td2->td_sa.code;
1338 			pl->pl_syscall_narg = td2->td_sa.callp->sy_narg;
1339 		} else {
1340 			pl->pl_syscall_code = 0;
1341 			pl->pl_syscall_narg = 0;
1342 		}
1343 		CTR6(KTR_PTRACE,
1344     "PT_LWPINFO: tid %d (pid %d) event %d flags %#x child pid %d syscall %d",
1345 		    td2->td_tid, p->p_pid, pl->pl_event, pl->pl_flags,
1346 		    pl->pl_child_pid, pl->pl_syscall_code);
1347 		break;
1348 
1349 	case PT_GETNUMLWPS:
1350 		CTR2(KTR_PTRACE, "PT_GETNUMLWPS: pid %d: %d threads", p->p_pid,
1351 		    p->p_numthreads);
1352 		td->td_retval[0] = p->p_numthreads;
1353 		break;
1354 
1355 	case PT_GETLWPLIST:
1356 		CTR3(KTR_PTRACE, "PT_GETLWPLIST: pid %d: data %d, actual %d",
1357 		    p->p_pid, data, p->p_numthreads);
1358 		if (data <= 0) {
1359 			error = EINVAL;
1360 			break;
1361 		}
1362 		num = imin(p->p_numthreads, data);
1363 		PROC_UNLOCK(p);
1364 		buf = malloc(num * sizeof(lwpid_t), M_TEMP, M_WAITOK);
1365 		tmp = 0;
1366 		PROC_LOCK(p);
1367 		FOREACH_THREAD_IN_PROC(p, td2) {
1368 			if (tmp >= num)
1369 				break;
1370 			buf[tmp++] = td2->td_tid;
1371 		}
1372 		PROC_UNLOCK(p);
1373 		error = copyout(buf, addr, tmp * sizeof(lwpid_t));
1374 		free(buf, M_TEMP);
1375 		if (!error)
1376 			td->td_retval[0] = tmp;
1377 		PROC_LOCK(p);
1378 		break;
1379 
1380 	case PT_VM_TIMESTAMP:
1381 		CTR2(KTR_PTRACE, "PT_VM_TIMESTAMP: pid %d: timestamp %d",
1382 		    p->p_pid, p->p_vmspace->vm_map.timestamp);
1383 		td->td_retval[0] = p->p_vmspace->vm_map.timestamp;
1384 		break;
1385 
1386 	case PT_VM_ENTRY:
1387 		PROC_UNLOCK(p);
1388 		error = ptrace_vm_entry(td, p, addr);
1389 		PROC_LOCK(p);
1390 		break;
1391 
1392 	case PT_COREDUMP:
1393 		pc = addr;
1394 		CTR2(KTR_PTRACE, "PT_COREDUMP: pid %d, fd %d",
1395 		    p->p_pid, pc->pc_fd);
1396 
1397 		if ((pc->pc_flags & ~(PC_COMPRESS | PC_ALL)) != 0) {
1398 			error = EINVAL;
1399 			break;
1400 		}
1401 		PROC_UNLOCK(p);
1402 
1403 		tcq = malloc(sizeof(*tcq), M_TEMP, M_WAITOK | M_ZERO);
1404 		fp = NULL;
1405 		error = fget_write(td, pc->pc_fd, &cap_write_rights, &fp);
1406 		if (error != 0)
1407 			goto coredump_cleanup_nofp;
1408 		if (fp->f_type != DTYPE_VNODE || fp->f_vnode->v_type != VREG) {
1409 			error = EPIPE;
1410 			goto coredump_cleanup;
1411 		}
1412 
1413 		PROC_LOCK(p);
1414 		error = proc_can_ptrace(td, p);
1415 		if (error != 0)
1416 			goto coredump_cleanup_locked;
1417 
1418 		td2 = ptrace_sel_coredump_thread(p);
1419 		if (td2 == NULL) {
1420 			error = EBUSY;
1421 			goto coredump_cleanup_locked;
1422 		}
1423 		KASSERT((td2->td_dbgflags & TDB_COREDUMPRQ) == 0,
1424 		    ("proc %d tid %d req coredump", p->p_pid, td2->td_tid));
1425 
1426 		tcq->tc_vp = fp->f_vnode;
1427 		tcq->tc_limit = pc->pc_limit == 0 ? OFF_MAX : pc->pc_limit;
1428 		tcq->tc_flags = SVC_PT_COREDUMP;
1429 		if ((pc->pc_flags & PC_COMPRESS) == 0)
1430 			tcq->tc_flags |= SVC_NOCOMPRESS;
1431 		if ((pc->pc_flags & PC_ALL) != 0)
1432 			tcq->tc_flags |= SVC_ALL;
1433 		td2->td_coredump = tcq;
1434 		td2->td_dbgflags |= TDB_COREDUMPRQ;
1435 		thread_run_flash(td2);
1436 		while ((td2->td_dbgflags & TDB_COREDUMPRQ) != 0)
1437 			msleep(p, &p->p_mtx, PPAUSE, "crdmp", 0);
1438 		error = tcq->tc_error;
1439 coredump_cleanup_locked:
1440 		PROC_UNLOCK(p);
1441 coredump_cleanup:
1442 		fdrop(fp, td);
1443 coredump_cleanup_nofp:
1444 		free(tcq, M_TEMP);
1445 		PROC_LOCK(p);
1446 		break;
1447 
1448 	default:
1449 #ifdef __HAVE_PTRACE_MACHDEP
1450 		if (req >= PT_FIRSTMACH) {
1451 			PROC_UNLOCK(p);
1452 			error = cpu_ptrace(td2, req, addr, data);
1453 			PROC_LOCK(p);
1454 		} else
1455 #endif
1456 			/* Unknown request. */
1457 			error = EINVAL;
1458 		break;
1459 	}
1460 out:
1461 	/* Drop our hold on this process now that the request has completed. */
1462 	_PRELE(p);
1463 fail:
1464 	if (p2_req_set) {
1465 		if ((p->p_flag2 & P2_PTRACEREQ) != 0)
1466 			wakeup(&p->p_flag2);
1467 		p->p_flag2 &= ~P2_PTRACEREQ;
1468 	}
1469 	PROC_UNLOCK(p);
1470 	if (proctree_locked)
1471 		sx_xunlock(&proctree_lock);
1472 	return (error);
1473 }
1474 #undef PROC_READ
1475 #undef PROC_WRITE
1476