xref: /freebsd/sys/kern/sys_process.c (revision 6829dae12bb055451fa467da4589c43bd03b1e64)
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/lock.h>
40 #include <sys/mutex.h>
41 #include <sys/syscallsubr.h>
42 #include <sys/sysent.h>
43 #include <sys/sysproto.h>
44 #include <sys/pioctl.h>
45 #include <sys/priv.h>
46 #include <sys/proc.h>
47 #include <sys/vnode.h>
48 #include <sys/ptrace.h>
49 #include <sys/rwlock.h>
50 #include <sys/sx.h>
51 #include <sys/malloc.h>
52 #include <sys/signalvar.h>
53 
54 #include <machine/reg.h>
55 
56 #include <security/audit/audit.h>
57 
58 #include <vm/vm.h>
59 #include <vm/pmap.h>
60 #include <vm/vm_extern.h>
61 #include <vm/vm_map.h>
62 #include <vm/vm_kern.h>
63 #include <vm/vm_object.h>
64 #include <vm/vm_page.h>
65 #include <vm/vm_param.h>
66 
67 #ifdef COMPAT_FREEBSD32
68 #include <sys/procfs.h>
69 #include <compat/freebsd32/freebsd32_signal.h>
70 
71 struct ptrace_io_desc32 {
72 	int		piod_op;
73 	uint32_t	piod_offs;
74 	uint32_t	piod_addr;
75 	uint32_t	piod_len;
76 };
77 
78 struct ptrace_vm_entry32 {
79 	int		pve_entry;
80 	int		pve_timestamp;
81 	uint32_t	pve_start;
82 	uint32_t	pve_end;
83 	uint32_t	pve_offset;
84 	u_int		pve_prot;
85 	u_int		pve_pathlen;
86 	int32_t		pve_fileid;
87 	u_int		pve_fsid;
88 	uint32_t	pve_path;
89 };
90 #endif
91 
92 /*
93  * Functions implemented using PROC_ACTION():
94  *
95  * proc_read_regs(proc, regs)
96  *	Get the current user-visible register set from the process
97  *	and copy it into the regs structure (<machine/reg.h>).
98  *	The process is stopped at the time read_regs is called.
99  *
100  * proc_write_regs(proc, regs)
101  *	Update the current register set from the passed in regs
102  *	structure.  Take care to avoid clobbering special CPU
103  *	registers or privileged bits in the PSL.
104  *	Depending on the architecture this may have fix-up work to do,
105  *	especially if the IAR or PCW are modified.
106  *	The process is stopped at the time write_regs is called.
107  *
108  * proc_read_fpregs, proc_write_fpregs
109  *	deal with the floating point register set, otherwise as above.
110  *
111  * proc_read_dbregs, proc_write_dbregs
112  *	deal with the processor debug register set, otherwise as above.
113  *
114  * proc_sstep(proc)
115  *	Arrange for the process to trap after executing a single instruction.
116  */
117 
118 #define	PROC_ACTION(action) do {					\
119 	int error;							\
120 									\
121 	PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);			\
122 	if ((td->td_proc->p_flag & P_INMEM) == 0)			\
123 		error = EIO;						\
124 	else								\
125 		error = (action);					\
126 	return (error);							\
127 } while(0)
128 
129 int
130 proc_read_regs(struct thread *td, struct reg *regs)
131 {
132 
133 	PROC_ACTION(fill_regs(td, regs));
134 }
135 
136 int
137 proc_write_regs(struct thread *td, struct reg *regs)
138 {
139 
140 	PROC_ACTION(set_regs(td, regs));
141 }
142 
143 int
144 proc_read_dbregs(struct thread *td, struct dbreg *dbregs)
145 {
146 
147 	PROC_ACTION(fill_dbregs(td, dbregs));
148 }
149 
150 int
151 proc_write_dbregs(struct thread *td, struct dbreg *dbregs)
152 {
153 
154 	PROC_ACTION(set_dbregs(td, dbregs));
155 }
156 
157 /*
158  * Ptrace doesn't support fpregs at all, and there are no security holes
159  * or translations for fpregs, so we can just copy them.
160  */
161 int
162 proc_read_fpregs(struct thread *td, struct fpreg *fpregs)
163 {
164 
165 	PROC_ACTION(fill_fpregs(td, fpregs));
166 }
167 
168 int
169 proc_write_fpregs(struct thread *td, struct fpreg *fpregs)
170 {
171 
172 	PROC_ACTION(set_fpregs(td, fpregs));
173 }
174 
175 #ifdef COMPAT_FREEBSD32
176 /* For 32 bit binaries, we need to expose the 32 bit regs layouts. */
177 int
178 proc_read_regs32(struct thread *td, struct reg32 *regs32)
179 {
180 
181 	PROC_ACTION(fill_regs32(td, regs32));
182 }
183 
184 int
185 proc_write_regs32(struct thread *td, struct reg32 *regs32)
186 {
187 
188 	PROC_ACTION(set_regs32(td, regs32));
189 }
190 
191 int
192 proc_read_dbregs32(struct thread *td, struct dbreg32 *dbregs32)
193 {
194 
195 	PROC_ACTION(fill_dbregs32(td, dbregs32));
196 }
197 
198 int
199 proc_write_dbregs32(struct thread *td, struct dbreg32 *dbregs32)
200 {
201 
202 	PROC_ACTION(set_dbregs32(td, dbregs32));
203 }
204 
205 int
206 proc_read_fpregs32(struct thread *td, struct fpreg32 *fpregs32)
207 {
208 
209 	PROC_ACTION(fill_fpregs32(td, fpregs32));
210 }
211 
212 int
213 proc_write_fpregs32(struct thread *td, struct fpreg32 *fpregs32)
214 {
215 
216 	PROC_ACTION(set_fpregs32(td, fpregs32));
217 }
218 #endif
219 
220 int
221 proc_sstep(struct thread *td)
222 {
223 
224 	PROC_ACTION(ptrace_single_step(td));
225 }
226 
227 int
228 proc_rwmem(struct proc *p, struct uio *uio)
229 {
230 	vm_map_t map;
231 	vm_offset_t pageno;		/* page number */
232 	vm_prot_t reqprot;
233 	int error, fault_flags, page_offset, writing;
234 
235 	/*
236 	 * Assert that someone has locked this vmspace.  (Should be
237 	 * curthread but we can't assert that.)  This keeps the process
238 	 * from exiting out from under us until this operation completes.
239 	 */
240 	PROC_ASSERT_HELD(p);
241 	PROC_LOCK_ASSERT(p, MA_NOTOWNED);
242 
243 	/*
244 	 * The map we want...
245 	 */
246 	map = &p->p_vmspace->vm_map;
247 
248 	/*
249 	 * If we are writing, then we request vm_fault() to create a private
250 	 * copy of each page.  Since these copies will not be writeable by the
251 	 * process, we must explicity request that they be dirtied.
252 	 */
253 	writing = uio->uio_rw == UIO_WRITE;
254 	reqprot = writing ? VM_PROT_COPY | VM_PROT_READ : VM_PROT_READ;
255 	fault_flags = writing ? VM_FAULT_DIRTY : VM_FAULT_NORMAL;
256 
257 	/*
258 	 * Only map in one page at a time.  We don't have to, but it
259 	 * makes things easier.  This way is trivial - right?
260 	 */
261 	do {
262 		vm_offset_t uva;
263 		u_int len;
264 		vm_page_t m;
265 
266 		uva = (vm_offset_t)uio->uio_offset;
267 
268 		/*
269 		 * Get the page number of this segment.
270 		 */
271 		pageno = trunc_page(uva);
272 		page_offset = uva - pageno;
273 
274 		/*
275 		 * How many bytes to copy
276 		 */
277 		len = min(PAGE_SIZE - page_offset, uio->uio_resid);
278 
279 		/*
280 		 * Fault and hold the page on behalf of the process.
281 		 */
282 		error = vm_fault_hold(map, pageno, reqprot, fault_flags, &m);
283 		if (error != KERN_SUCCESS) {
284 			if (error == KERN_RESOURCE_SHORTAGE)
285 				error = ENOMEM;
286 			else
287 				error = EFAULT;
288 			break;
289 		}
290 
291 		/*
292 		 * Now do the i/o move.
293 		 */
294 		error = uiomove_fromphys(&m, page_offset, len, uio);
295 
296 		/* Make the I-cache coherent for breakpoints. */
297 		if (writing && error == 0) {
298 			vm_map_lock_read(map);
299 			if (vm_map_check_protection(map, pageno, pageno +
300 			    PAGE_SIZE, VM_PROT_EXECUTE))
301 				vm_sync_icache(map, uva, len);
302 			vm_map_unlock_read(map);
303 		}
304 
305 		/*
306 		 * Release the page.
307 		 */
308 		vm_page_lock(m);
309 		vm_page_unhold(m);
310 		vm_page_unlock(m);
311 
312 	} while (error == 0 && uio->uio_resid > 0);
313 
314 	return (error);
315 }
316 
317 static ssize_t
318 proc_iop(struct thread *td, struct proc *p, vm_offset_t va, void *buf,
319     size_t len, enum uio_rw rw)
320 {
321 	struct iovec iov;
322 	struct uio uio;
323 	ssize_t slen;
324 
325 	MPASS(len < SSIZE_MAX);
326 	slen = (ssize_t)len;
327 
328 	iov.iov_base = (caddr_t)buf;
329 	iov.iov_len = len;
330 	uio.uio_iov = &iov;
331 	uio.uio_iovcnt = 1;
332 	uio.uio_offset = va;
333 	uio.uio_resid = slen;
334 	uio.uio_segflg = UIO_SYSSPACE;
335 	uio.uio_rw = rw;
336 	uio.uio_td = td;
337 	proc_rwmem(p, &uio);
338 	if (uio.uio_resid == slen)
339 		return (-1);
340 	return (slen - uio.uio_resid);
341 }
342 
343 ssize_t
344 proc_readmem(struct thread *td, struct proc *p, vm_offset_t va, void *buf,
345     size_t len)
346 {
347 
348 	return (proc_iop(td, p, va, buf, len, UIO_READ));
349 }
350 
351 ssize_t
352 proc_writemem(struct thread *td, struct proc *p, vm_offset_t va, void *buf,
353     size_t len)
354 {
355 
356 	return (proc_iop(td, p, va, buf, len, UIO_WRITE));
357 }
358 
359 static int
360 ptrace_vm_entry(struct thread *td, struct proc *p, struct ptrace_vm_entry *pve)
361 {
362 	struct vattr vattr;
363 	vm_map_t map;
364 	vm_map_entry_t entry;
365 	vm_object_t obj, tobj, lobj;
366 	struct vmspace *vm;
367 	struct vnode *vp;
368 	char *freepath, *fullpath;
369 	u_int pathlen;
370 	int error, index;
371 
372 	error = 0;
373 	obj = NULL;
374 
375 	vm = vmspace_acquire_ref(p);
376 	map = &vm->vm_map;
377 	vm_map_lock_read(map);
378 
379 	do {
380 		entry = map->header.next;
381 		index = 0;
382 		while (index < pve->pve_entry && entry != &map->header) {
383 			entry = entry->next;
384 			index++;
385 		}
386 		if (index != pve->pve_entry) {
387 			error = EINVAL;
388 			break;
389 		}
390 		KASSERT((map->header.eflags & MAP_ENTRY_IS_SUB_MAP) == 0,
391 		    ("Submap in map header"));
392 		while ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) {
393 			entry = entry->next;
394 			index++;
395 		}
396 		if (entry == &map->header) {
397 			error = ENOENT;
398 			break;
399 		}
400 
401 		/* We got an entry. */
402 		pve->pve_entry = index + 1;
403 		pve->pve_timestamp = map->timestamp;
404 		pve->pve_start = entry->start;
405 		pve->pve_end = entry->end - 1;
406 		pve->pve_offset = entry->offset;
407 		pve->pve_prot = entry->protection;
408 
409 		/* Backing object's path needed? */
410 		if (pve->pve_pathlen == 0)
411 			break;
412 
413 		pathlen = pve->pve_pathlen;
414 		pve->pve_pathlen = 0;
415 
416 		obj = entry->object.vm_object;
417 		if (obj != NULL)
418 			VM_OBJECT_RLOCK(obj);
419 	} while (0);
420 
421 	vm_map_unlock_read(map);
422 
423 	pve->pve_fsid = VNOVAL;
424 	pve->pve_fileid = VNOVAL;
425 
426 	if (error == 0 && obj != NULL) {
427 		lobj = obj;
428 		for (tobj = obj; tobj != NULL; tobj = tobj->backing_object) {
429 			if (tobj != obj)
430 				VM_OBJECT_RLOCK(tobj);
431 			if (lobj != obj)
432 				VM_OBJECT_RUNLOCK(lobj);
433 			lobj = tobj;
434 			pve->pve_offset += tobj->backing_object_offset;
435 		}
436 		vp = vm_object_vnode(lobj);
437 		if (vp != NULL)
438 			vref(vp);
439 		if (lobj != obj)
440 			VM_OBJECT_RUNLOCK(lobj);
441 		VM_OBJECT_RUNLOCK(obj);
442 
443 		if (vp != NULL) {
444 			freepath = NULL;
445 			fullpath = NULL;
446 			vn_fullpath(td, vp, &fullpath, &freepath);
447 			vn_lock(vp, LK_SHARED | LK_RETRY);
448 			if (VOP_GETATTR(vp, &vattr, td->td_ucred) == 0) {
449 				pve->pve_fileid = vattr.va_fileid;
450 				pve->pve_fsid = vattr.va_fsid;
451 			}
452 			vput(vp);
453 
454 			if (fullpath != NULL) {
455 				pve->pve_pathlen = strlen(fullpath) + 1;
456 				if (pve->pve_pathlen <= pathlen) {
457 					error = copyout(fullpath, pve->pve_path,
458 					    pve->pve_pathlen);
459 				} else
460 					error = ENAMETOOLONG;
461 			}
462 			if (freepath != NULL)
463 				free(freepath, M_TEMP);
464 		}
465 	}
466 	vmspace_free(vm);
467 	if (error == 0)
468 		CTR3(KTR_PTRACE, "PT_VM_ENTRY: pid %d, entry %d, start %p",
469 		    p->p_pid, pve->pve_entry, pve->pve_start);
470 
471 	return (error);
472 }
473 
474 #ifdef COMPAT_FREEBSD32
475 static int
476 ptrace_vm_entry32(struct thread *td, struct proc *p,
477     struct ptrace_vm_entry32 *pve32)
478 {
479 	struct ptrace_vm_entry pve;
480 	int error;
481 
482 	pve.pve_entry = pve32->pve_entry;
483 	pve.pve_pathlen = pve32->pve_pathlen;
484 	pve.pve_path = (void *)(uintptr_t)pve32->pve_path;
485 
486 	error = ptrace_vm_entry(td, p, &pve);
487 	if (error == 0) {
488 		pve32->pve_entry = pve.pve_entry;
489 		pve32->pve_timestamp = pve.pve_timestamp;
490 		pve32->pve_start = pve.pve_start;
491 		pve32->pve_end = pve.pve_end;
492 		pve32->pve_offset = pve.pve_offset;
493 		pve32->pve_prot = pve.pve_prot;
494 		pve32->pve_fileid = pve.pve_fileid;
495 		pve32->pve_fsid = pve.pve_fsid;
496 	}
497 
498 	pve32->pve_pathlen = pve.pve_pathlen;
499 	return (error);
500 }
501 
502 static void
503 ptrace_lwpinfo_to32(const struct ptrace_lwpinfo *pl,
504     struct ptrace_lwpinfo32 *pl32)
505 {
506 
507 	bzero(pl32, sizeof(*pl32));
508 	pl32->pl_lwpid = pl->pl_lwpid;
509 	pl32->pl_event = pl->pl_event;
510 	pl32->pl_flags = pl->pl_flags;
511 	pl32->pl_sigmask = pl->pl_sigmask;
512 	pl32->pl_siglist = pl->pl_siglist;
513 	siginfo_to_siginfo32(&pl->pl_siginfo, &pl32->pl_siginfo);
514 	strcpy(pl32->pl_tdname, pl->pl_tdname);
515 	pl32->pl_child_pid = pl->pl_child_pid;
516 	pl32->pl_syscall_code = pl->pl_syscall_code;
517 	pl32->pl_syscall_narg = pl->pl_syscall_narg;
518 }
519 #endif /* COMPAT_FREEBSD32 */
520 
521 /*
522  * Process debugging system call.
523  */
524 #ifndef _SYS_SYSPROTO_H_
525 struct ptrace_args {
526 	int	req;
527 	pid_t	pid;
528 	caddr_t	addr;
529 	int	data;
530 };
531 #endif
532 
533 #ifdef COMPAT_FREEBSD32
534 /*
535  * This CPP subterfuge is to try and reduce the number of ifdefs in
536  * the body of the code.
537  *   COPYIN(uap->addr, &r.reg, sizeof r.reg);
538  * becomes either:
539  *   copyin(uap->addr, &r.reg, sizeof r.reg);
540  * or
541  *   copyin(uap->addr, &r.reg32, sizeof r.reg32);
542  * .. except this is done at runtime.
543  */
544 #define	BZERO(a, s)		wrap32 ? \
545 	bzero(a ## 32, s ## 32) : \
546 	bzero(a, s)
547 #define	COPYIN(u, k, s)		wrap32 ? \
548 	copyin(u, k ## 32, s ## 32) : \
549 	copyin(u, k, s)
550 #define	COPYOUT(k, u, s)	wrap32 ? \
551 	copyout(k ## 32, u, s ## 32) : \
552 	copyout(k, u, s)
553 #else
554 #define	BZERO(a, s)		bzero(a, s)
555 #define	COPYIN(u, k, s)		copyin(u, k, s)
556 #define	COPYOUT(k, u, s)	copyout(k, u, s)
557 #endif
558 int
559 sys_ptrace(struct thread *td, struct ptrace_args *uap)
560 {
561 	/*
562 	 * XXX this obfuscation is to reduce stack usage, but the register
563 	 * structs may be too large to put on the stack anyway.
564 	 */
565 	union {
566 		struct ptrace_io_desc piod;
567 		struct ptrace_lwpinfo pl;
568 		struct ptrace_vm_entry pve;
569 		struct dbreg dbreg;
570 		struct fpreg fpreg;
571 		struct reg reg;
572 #ifdef COMPAT_FREEBSD32
573 		struct dbreg32 dbreg32;
574 		struct fpreg32 fpreg32;
575 		struct reg32 reg32;
576 		struct ptrace_io_desc32 piod32;
577 		struct ptrace_lwpinfo32 pl32;
578 		struct ptrace_vm_entry32 pve32;
579 #endif
580 		char args[sizeof(td->td_sa.args)];
581 		int ptevents;
582 	} r;
583 	void *addr;
584 	int error = 0;
585 #ifdef COMPAT_FREEBSD32
586 	int wrap32 = 0;
587 
588 	if (SV_CURPROC_FLAG(SV_ILP32))
589 		wrap32 = 1;
590 #endif
591 	AUDIT_ARG_PID(uap->pid);
592 	AUDIT_ARG_CMD(uap->req);
593 	AUDIT_ARG_VALUE(uap->data);
594 	addr = &r;
595 	switch (uap->req) {
596 	case PT_GET_EVENT_MASK:
597 	case PT_LWPINFO:
598 	case PT_GET_SC_ARGS:
599 		break;
600 	case PT_GETREGS:
601 		BZERO(&r.reg, sizeof r.reg);
602 		break;
603 	case PT_GETFPREGS:
604 		BZERO(&r.fpreg, sizeof r.fpreg);
605 		break;
606 	case PT_GETDBREGS:
607 		BZERO(&r.dbreg, sizeof r.dbreg);
608 		break;
609 	case PT_SETREGS:
610 		error = COPYIN(uap->addr, &r.reg, sizeof r.reg);
611 		break;
612 	case PT_SETFPREGS:
613 		error = COPYIN(uap->addr, &r.fpreg, sizeof r.fpreg);
614 		break;
615 	case PT_SETDBREGS:
616 		error = COPYIN(uap->addr, &r.dbreg, sizeof r.dbreg);
617 		break;
618 	case PT_SET_EVENT_MASK:
619 		if (uap->data != sizeof(r.ptevents))
620 			error = EINVAL;
621 		else
622 			error = copyin(uap->addr, &r.ptevents, uap->data);
623 		break;
624 	case PT_IO:
625 		error = COPYIN(uap->addr, &r.piod, sizeof r.piod);
626 		break;
627 	case PT_VM_ENTRY:
628 		error = COPYIN(uap->addr, &r.pve, sizeof r.pve);
629 		break;
630 	default:
631 		addr = uap->addr;
632 		break;
633 	}
634 	if (error)
635 		return (error);
636 
637 	error = kern_ptrace(td, uap->req, uap->pid, addr, uap->data);
638 	if (error)
639 		return (error);
640 
641 	switch (uap->req) {
642 	case PT_VM_ENTRY:
643 		error = COPYOUT(&r.pve, uap->addr, sizeof r.pve);
644 		break;
645 	case PT_IO:
646 		error = COPYOUT(&r.piod, uap->addr, sizeof r.piod);
647 		break;
648 	case PT_GETREGS:
649 		error = COPYOUT(&r.reg, uap->addr, sizeof r.reg);
650 		break;
651 	case PT_GETFPREGS:
652 		error = COPYOUT(&r.fpreg, uap->addr, sizeof r.fpreg);
653 		break;
654 	case PT_GETDBREGS:
655 		error = COPYOUT(&r.dbreg, uap->addr, sizeof r.dbreg);
656 		break;
657 	case PT_GET_EVENT_MASK:
658 		/* NB: The size in uap->data is validated in kern_ptrace(). */
659 		error = copyout(&r.ptevents, uap->addr, uap->data);
660 		break;
661 	case PT_LWPINFO:
662 		/* NB: The size in uap->data is validated in kern_ptrace(). */
663 		error = copyout(&r.pl, uap->addr, uap->data);
664 		break;
665 	case PT_GET_SC_ARGS:
666 		error = copyout(r.args, uap->addr, MIN(uap->data,
667 		    sizeof(r.args)));
668 		break;
669 	}
670 
671 	return (error);
672 }
673 #undef COPYIN
674 #undef COPYOUT
675 #undef BZERO
676 
677 #ifdef COMPAT_FREEBSD32
678 /*
679  *   PROC_READ(regs, td2, addr);
680  * becomes either:
681  *   proc_read_regs(td2, addr);
682  * or
683  *   proc_read_regs32(td2, addr);
684  * .. except this is done at runtime.  There is an additional
685  * complication in that PROC_WRITE disallows 32 bit consumers
686  * from writing to 64 bit address space targets.
687  */
688 #define	PROC_READ(w, t, a)	wrap32 ? \
689 	proc_read_ ## w ## 32(t, a) : \
690 	proc_read_ ## w (t, a)
691 #define	PROC_WRITE(w, t, a)	wrap32 ? \
692 	(safe ? proc_write_ ## w ## 32(t, a) : EINVAL ) : \
693 	proc_write_ ## w (t, a)
694 #else
695 #define	PROC_READ(w, t, a)	proc_read_ ## w (t, a)
696 #define	PROC_WRITE(w, t, a)	proc_write_ ## w (t, a)
697 #endif
698 
699 void
700 proc_set_traced(struct proc *p, bool stop)
701 {
702 
703 	sx_assert(&proctree_lock, SX_XLOCKED);
704 	PROC_LOCK_ASSERT(p, MA_OWNED);
705 	p->p_flag |= P_TRACED;
706 	if (stop)
707 		p->p_flag2 |= P2_PTRACE_FSTP;
708 	p->p_ptevents = PTRACE_DEFAULT;
709 }
710 
711 int
712 kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
713 {
714 	struct iovec iov;
715 	struct uio uio;
716 	struct proc *curp, *p, *pp;
717 	struct thread *td2 = NULL, *td3;
718 	struct ptrace_io_desc *piod = NULL;
719 	struct ptrace_lwpinfo *pl;
720 	int error, num, tmp;
721 	int proctree_locked = 0;
722 	lwpid_t tid = 0, *buf;
723 #ifdef COMPAT_FREEBSD32
724 	int wrap32 = 0, safe = 0;
725 	struct ptrace_io_desc32 *piod32 = NULL;
726 	struct ptrace_lwpinfo32 *pl32 = NULL;
727 	struct ptrace_lwpinfo plr;
728 #endif
729 
730 	curp = td->td_proc;
731 
732 	/* Lock proctree before locking the process. */
733 	switch (req) {
734 	case PT_TRACE_ME:
735 	case PT_ATTACH:
736 	case PT_STEP:
737 	case PT_CONTINUE:
738 	case PT_TO_SCE:
739 	case PT_TO_SCX:
740 	case PT_SYSCALL:
741 	case PT_FOLLOW_FORK:
742 	case PT_LWP_EVENTS:
743 	case PT_GET_EVENT_MASK:
744 	case PT_SET_EVENT_MASK:
745 	case PT_DETACH:
746 	case PT_GET_SC_ARGS:
747 		sx_xlock(&proctree_lock);
748 		proctree_locked = 1;
749 		break;
750 	default:
751 		break;
752 	}
753 
754 	if (req == PT_TRACE_ME) {
755 		p = td->td_proc;
756 		PROC_LOCK(p);
757 	} else {
758 		if (pid <= PID_MAX) {
759 			if ((p = pfind(pid)) == NULL) {
760 				if (proctree_locked)
761 					sx_xunlock(&proctree_lock);
762 				return (ESRCH);
763 			}
764 		} else {
765 			td2 = tdfind(pid, -1);
766 			if (td2 == NULL) {
767 				if (proctree_locked)
768 					sx_xunlock(&proctree_lock);
769 				return (ESRCH);
770 			}
771 			p = td2->td_proc;
772 			tid = pid;
773 			pid = p->p_pid;
774 		}
775 	}
776 	AUDIT_ARG_PROCESS(p);
777 
778 	if ((p->p_flag & P_WEXIT) != 0) {
779 		error = ESRCH;
780 		goto fail;
781 	}
782 	if ((error = p_cansee(td, p)) != 0)
783 		goto fail;
784 
785 	if ((error = p_candebug(td, p)) != 0)
786 		goto fail;
787 
788 	/*
789 	 * System processes can't be debugged.
790 	 */
791 	if ((p->p_flag & P_SYSTEM) != 0) {
792 		error = EINVAL;
793 		goto fail;
794 	}
795 
796 	if (tid == 0) {
797 		if ((p->p_flag & P_STOPPED_TRACE) != 0) {
798 			KASSERT(p->p_xthread != NULL, ("NULL p_xthread"));
799 			td2 = p->p_xthread;
800 		} else {
801 			td2 = FIRST_THREAD_IN_PROC(p);
802 		}
803 		tid = td2->td_tid;
804 	}
805 
806 #ifdef COMPAT_FREEBSD32
807 	/*
808 	 * Test if we're a 32 bit client and what the target is.
809 	 * Set the wrap controls accordingly.
810 	 */
811 	if (SV_CURPROC_FLAG(SV_ILP32)) {
812 		if (SV_PROC_FLAG(td2->td_proc, SV_ILP32))
813 			safe = 1;
814 		wrap32 = 1;
815 	}
816 #endif
817 	/*
818 	 * Permissions check
819 	 */
820 	switch (req) {
821 	case PT_TRACE_ME:
822 		/*
823 		 * Always legal, when there is a parent process which
824 		 * could trace us.  Otherwise, reject.
825 		 */
826 		if ((p->p_flag & P_TRACED) != 0) {
827 			error = EBUSY;
828 			goto fail;
829 		}
830 		if (p->p_pptr == initproc) {
831 			error = EPERM;
832 			goto fail;
833 		}
834 		break;
835 
836 	case PT_ATTACH:
837 		/* Self */
838 		if (p == td->td_proc) {
839 			error = EINVAL;
840 			goto fail;
841 		}
842 
843 		/* Already traced */
844 		if (p->p_flag & P_TRACED) {
845 			error = EBUSY;
846 			goto fail;
847 		}
848 
849 		/* Can't trace an ancestor if you're being traced. */
850 		if (curp->p_flag & P_TRACED) {
851 			for (pp = curp->p_pptr; pp != NULL; pp = pp->p_pptr) {
852 				if (pp == p) {
853 					error = EINVAL;
854 					goto fail;
855 				}
856 			}
857 		}
858 
859 
860 		/* OK */
861 		break;
862 
863 	case PT_CLEARSTEP:
864 		/* Allow thread to clear single step for itself */
865 		if (td->td_tid == tid)
866 			break;
867 
868 		/* FALLTHROUGH */
869 	default:
870 		/* not being traced... */
871 		if ((p->p_flag & P_TRACED) == 0) {
872 			error = EPERM;
873 			goto fail;
874 		}
875 
876 		/* not being traced by YOU */
877 		if (p->p_pptr != td->td_proc) {
878 			error = EBUSY;
879 			goto fail;
880 		}
881 
882 		/* not currently stopped */
883 		if ((p->p_flag & P_STOPPED_TRACE) == 0 ||
884 		    p->p_suspcount != p->p_numthreads  ||
885 		    (p->p_flag & P_WAITED) == 0) {
886 			error = EBUSY;
887 			goto fail;
888 		}
889 
890 		/* OK */
891 		break;
892 	}
893 
894 	/* Keep this process around until we finish this request. */
895 	_PHOLD(p);
896 
897 #ifdef FIX_SSTEP
898 	/*
899 	 * Single step fixup ala procfs
900 	 */
901 	FIX_SSTEP(td2);
902 #endif
903 
904 	/*
905 	 * Actually do the requests
906 	 */
907 
908 	td->td_retval[0] = 0;
909 
910 	switch (req) {
911 	case PT_TRACE_ME:
912 		/* set my trace flag and "owner" so it can read/write me */
913 		proc_set_traced(p, false);
914 		if (p->p_flag & P_PPWAIT)
915 			p->p_flag |= P_PPTRACE;
916 		CTR1(KTR_PTRACE, "PT_TRACE_ME: pid %d", p->p_pid);
917 		break;
918 
919 	case PT_ATTACH:
920 		/* security check done above */
921 		/*
922 		 * It would be nice if the tracing relationship was separate
923 		 * from the parent relationship but that would require
924 		 * another set of links in the proc struct or for "wait"
925 		 * to scan the entire proc table.  To make life easier,
926 		 * we just re-parent the process we're trying to trace.
927 		 * The old parent is remembered so we can put things back
928 		 * on a "detach".
929 		 */
930 		proc_set_traced(p, true);
931 		if (p->p_pptr != td->td_proc) {
932 			proc_reparent(p, td->td_proc, false);
933 		}
934 		CTR2(KTR_PTRACE, "PT_ATTACH: pid %d, oppid %d", p->p_pid,
935 		    p->p_oppid);
936 
937 		sx_xunlock(&proctree_lock);
938 		proctree_locked = 0;
939 		MPASS(p->p_xthread == NULL);
940 		MPASS((p->p_flag & P_STOPPED_TRACE) == 0);
941 
942 		/*
943 		 * If already stopped due to a stop signal, clear the
944 		 * existing stop before triggering a traced SIGSTOP.
945 		 */
946 		if ((p->p_flag & P_STOPPED_SIG) != 0) {
947 			PROC_SLOCK(p);
948 			p->p_flag &= ~(P_STOPPED_SIG | P_WAITED);
949 			thread_unsuspend(p);
950 			PROC_SUNLOCK(p);
951 		}
952 
953 		kern_psignal(p, SIGSTOP);
954 		break;
955 
956 	case PT_CLEARSTEP:
957 		CTR2(KTR_PTRACE, "PT_CLEARSTEP: tid %d (pid %d)", td2->td_tid,
958 		    p->p_pid);
959 		error = ptrace_clear_single_step(td2);
960 		break;
961 
962 	case PT_SETSTEP:
963 		CTR2(KTR_PTRACE, "PT_SETSTEP: tid %d (pid %d)", td2->td_tid,
964 		    p->p_pid);
965 		error = ptrace_single_step(td2);
966 		break;
967 
968 	case PT_SUSPEND:
969 		CTR2(KTR_PTRACE, "PT_SUSPEND: tid %d (pid %d)", td2->td_tid,
970 		    p->p_pid);
971 		td2->td_dbgflags |= TDB_SUSPEND;
972 		thread_lock(td2);
973 		td2->td_flags |= TDF_NEEDSUSPCHK;
974 		thread_unlock(td2);
975 		break;
976 
977 	case PT_RESUME:
978 		CTR2(KTR_PTRACE, "PT_RESUME: tid %d (pid %d)", td2->td_tid,
979 		    p->p_pid);
980 		td2->td_dbgflags &= ~TDB_SUSPEND;
981 		break;
982 
983 	case PT_FOLLOW_FORK:
984 		CTR3(KTR_PTRACE, "PT_FOLLOW_FORK: pid %d %s -> %s", p->p_pid,
985 		    p->p_ptevents & PTRACE_FORK ? "enabled" : "disabled",
986 		    data ? "enabled" : "disabled");
987 		if (data)
988 			p->p_ptevents |= PTRACE_FORK;
989 		else
990 			p->p_ptevents &= ~PTRACE_FORK;
991 		break;
992 
993 	case PT_LWP_EVENTS:
994 		CTR3(KTR_PTRACE, "PT_LWP_EVENTS: pid %d %s -> %s", p->p_pid,
995 		    p->p_ptevents & PTRACE_LWP ? "enabled" : "disabled",
996 		    data ? "enabled" : "disabled");
997 		if (data)
998 			p->p_ptevents |= PTRACE_LWP;
999 		else
1000 			p->p_ptevents &= ~PTRACE_LWP;
1001 		break;
1002 
1003 	case PT_GET_EVENT_MASK:
1004 		if (data != sizeof(p->p_ptevents)) {
1005 			error = EINVAL;
1006 			break;
1007 		}
1008 		CTR2(KTR_PTRACE, "PT_GET_EVENT_MASK: pid %d mask %#x", p->p_pid,
1009 		    p->p_ptevents);
1010 		*(int *)addr = p->p_ptevents;
1011 		break;
1012 
1013 	case PT_SET_EVENT_MASK:
1014 		if (data != sizeof(p->p_ptevents)) {
1015 			error = EINVAL;
1016 			break;
1017 		}
1018 		tmp = *(int *)addr;
1019 		if ((tmp & ~(PTRACE_EXEC | PTRACE_SCE | PTRACE_SCX |
1020 		    PTRACE_FORK | PTRACE_LWP | PTRACE_VFORK)) != 0) {
1021 			error = EINVAL;
1022 			break;
1023 		}
1024 		CTR3(KTR_PTRACE, "PT_SET_EVENT_MASK: pid %d mask %#x -> %#x",
1025 		    p->p_pid, p->p_ptevents, tmp);
1026 		p->p_ptevents = tmp;
1027 		break;
1028 
1029 	case PT_GET_SC_ARGS:
1030 		CTR1(KTR_PTRACE, "PT_GET_SC_ARGS: pid %d", p->p_pid);
1031 		if ((td2->td_dbgflags & (TDB_SCE | TDB_SCX)) == 0
1032 #ifdef COMPAT_FREEBSD32
1033 		    || (wrap32 && !safe)
1034 #endif
1035 		    ) {
1036 			error = EINVAL;
1037 			break;
1038 		}
1039 		bzero(addr, sizeof(td2->td_sa.args));
1040 #ifdef COMPAT_FREEBSD32
1041 		if (wrap32)
1042 			for (num = 0; num < nitems(td2->td_sa.args); num++)
1043 				((uint32_t *)addr)[num] = (uint32_t)
1044 				    td2->td_sa.args[num];
1045 		else
1046 #endif
1047 			bcopy(td2->td_sa.args, addr, td2->td_sa.narg *
1048 			    sizeof(register_t));
1049 		break;
1050 
1051 	case PT_STEP:
1052 	case PT_CONTINUE:
1053 	case PT_TO_SCE:
1054 	case PT_TO_SCX:
1055 	case PT_SYSCALL:
1056 	case PT_DETACH:
1057 		/* Zero means do not send any signal */
1058 		if (data < 0 || data > _SIG_MAXSIG) {
1059 			error = EINVAL;
1060 			break;
1061 		}
1062 
1063 		switch (req) {
1064 		case PT_STEP:
1065 			CTR3(KTR_PTRACE, "PT_STEP: tid %d (pid %d), sig = %d",
1066 			    td2->td_tid, p->p_pid, data);
1067 			error = ptrace_single_step(td2);
1068 			if (error)
1069 				goto out;
1070 			break;
1071 		case PT_CONTINUE:
1072 		case PT_TO_SCE:
1073 		case PT_TO_SCX:
1074 		case PT_SYSCALL:
1075 			if (addr != (void *)1) {
1076 				error = ptrace_set_pc(td2,
1077 				    (u_long)(uintfptr_t)addr);
1078 				if (error)
1079 					goto out;
1080 			}
1081 			switch (req) {
1082 			case PT_TO_SCE:
1083 				p->p_ptevents |= PTRACE_SCE;
1084 				CTR4(KTR_PTRACE,
1085 		    "PT_TO_SCE: pid %d, events = %#x, PC = %#lx, sig = %d",
1086 				    p->p_pid, p->p_ptevents,
1087 				    (u_long)(uintfptr_t)addr, data);
1088 				break;
1089 			case PT_TO_SCX:
1090 				p->p_ptevents |= PTRACE_SCX;
1091 				CTR4(KTR_PTRACE,
1092 		    "PT_TO_SCX: pid %d, events = %#x, PC = %#lx, sig = %d",
1093 				    p->p_pid, p->p_ptevents,
1094 				    (u_long)(uintfptr_t)addr, data);
1095 				break;
1096 			case PT_SYSCALL:
1097 				p->p_ptevents |= PTRACE_SYSCALL;
1098 				CTR4(KTR_PTRACE,
1099 		    "PT_SYSCALL: pid %d, events = %#x, PC = %#lx, sig = %d",
1100 				    p->p_pid, p->p_ptevents,
1101 				    (u_long)(uintfptr_t)addr, data);
1102 				break;
1103 			case PT_CONTINUE:
1104 				CTR3(KTR_PTRACE,
1105 				    "PT_CONTINUE: pid %d, PC = %#lx, sig = %d",
1106 				    p->p_pid, (u_long)(uintfptr_t)addr, data);
1107 				break;
1108 			}
1109 			break;
1110 		case PT_DETACH:
1111 			/*
1112 			 * Reset the process parent.
1113 			 *
1114 			 * NB: This clears P_TRACED before reparenting
1115 			 * a detached process back to its original
1116 			 * parent.  Otherwise the debugee will be set
1117 			 * as an orphan of the debugger.
1118 			 */
1119 			p->p_flag &= ~(P_TRACED | P_WAITED);
1120 			if (p->p_oppid != p->p_pptr->p_pid) {
1121 				PROC_LOCK(p->p_pptr);
1122 				sigqueue_take(p->p_ksi);
1123 				PROC_UNLOCK(p->p_pptr);
1124 
1125 				pp = proc_realparent(p);
1126 				proc_reparent(p, pp, false);
1127 				if (pp == initproc)
1128 					p->p_sigparent = SIGCHLD;
1129 				CTR3(KTR_PTRACE,
1130 			    "PT_DETACH: pid %d reparented to pid %d, sig %d",
1131 				    p->p_pid, pp->p_pid, data);
1132 			} else
1133 				CTR2(KTR_PTRACE, "PT_DETACH: pid %d, sig %d",
1134 				    p->p_pid, data);
1135 			p->p_ptevents = 0;
1136 			FOREACH_THREAD_IN_PROC(p, td3) {
1137 				if ((td3->td_dbgflags & TDB_FSTP) != 0) {
1138 					sigqueue_delete(&td3->td_sigqueue,
1139 					    SIGSTOP);
1140 				}
1141 				td3->td_dbgflags &= ~(TDB_XSIG | TDB_FSTP |
1142 				    TDB_SUSPEND);
1143 			}
1144 
1145 			if ((p->p_flag2 & P2_PTRACE_FSTP) != 0) {
1146 				sigqueue_delete(&p->p_sigqueue, SIGSTOP);
1147 				p->p_flag2 &= ~P2_PTRACE_FSTP;
1148 			}
1149 
1150 			/* should we send SIGCHLD? */
1151 			/* childproc_continued(p); */
1152 			break;
1153 		}
1154 
1155 		sx_xunlock(&proctree_lock);
1156 		proctree_locked = 0;
1157 
1158 	sendsig:
1159 		MPASS(proctree_locked == 0);
1160 
1161 		/*
1162 		 * Clear the pending event for the thread that just
1163 		 * reported its event (p_xthread).  This may not be
1164 		 * the thread passed to PT_CONTINUE, PT_STEP, etc. if
1165 		 * the debugger is resuming a different thread.
1166 		 *
1167 		 * Deliver any pending signal via the reporting thread.
1168 		 */
1169 		MPASS(p->p_xthread != NULL);
1170 		p->p_xthread->td_dbgflags &= ~TDB_XSIG;
1171 		p->p_xthread->td_xsig = data;
1172 		p->p_xthread = NULL;
1173 		p->p_xsig = data;
1174 
1175 		/*
1176 		 * P_WKILLED is insurance that a PT_KILL/SIGKILL
1177 		 * always works immediately, even if another thread is
1178 		 * unsuspended first and attempts to handle a
1179 		 * different signal or if the POSIX.1b style signal
1180 		 * queue cannot accommodate any new signals.
1181 		 */
1182 		if (data == SIGKILL)
1183 			proc_wkilled(p);
1184 
1185 		/*
1186 		 * Unsuspend all threads.  To leave a thread
1187 		 * suspended, use PT_SUSPEND to suspend it before
1188 		 * continuing the process.
1189 		 */
1190 		PROC_SLOCK(p);
1191 		p->p_flag &= ~(P_STOPPED_TRACE | P_STOPPED_SIG | P_WAITED);
1192 		thread_unsuspend(p);
1193 		PROC_SUNLOCK(p);
1194 		break;
1195 
1196 	case PT_WRITE_I:
1197 	case PT_WRITE_D:
1198 		td2->td_dbgflags |= TDB_USERWR;
1199 		PROC_UNLOCK(p);
1200 		error = 0;
1201 		if (proc_writemem(td, p, (off_t)(uintptr_t)addr, &data,
1202 		    sizeof(int)) != sizeof(int))
1203 			error = ENOMEM;
1204 		else
1205 			CTR3(KTR_PTRACE, "PT_WRITE: pid %d: %p <= %#x",
1206 			    p->p_pid, addr, data);
1207 		PROC_LOCK(p);
1208 		break;
1209 
1210 	case PT_READ_I:
1211 	case PT_READ_D:
1212 		PROC_UNLOCK(p);
1213 		error = tmp = 0;
1214 		if (proc_readmem(td, p, (off_t)(uintptr_t)addr, &tmp,
1215 		    sizeof(int)) != sizeof(int))
1216 			error = ENOMEM;
1217 		else
1218 			CTR3(KTR_PTRACE, "PT_READ: pid %d: %p >= %#x",
1219 			    p->p_pid, addr, tmp);
1220 		td->td_retval[0] = tmp;
1221 		PROC_LOCK(p);
1222 		break;
1223 
1224 	case PT_IO:
1225 #ifdef COMPAT_FREEBSD32
1226 		if (wrap32) {
1227 			piod32 = addr;
1228 			iov.iov_base = (void *)(uintptr_t)piod32->piod_addr;
1229 			iov.iov_len = piod32->piod_len;
1230 			uio.uio_offset = (off_t)(uintptr_t)piod32->piod_offs;
1231 			uio.uio_resid = piod32->piod_len;
1232 		} else
1233 #endif
1234 		{
1235 			piod = addr;
1236 			iov.iov_base = piod->piod_addr;
1237 			iov.iov_len = piod->piod_len;
1238 			uio.uio_offset = (off_t)(uintptr_t)piod->piod_offs;
1239 			uio.uio_resid = piod->piod_len;
1240 		}
1241 		uio.uio_iov = &iov;
1242 		uio.uio_iovcnt = 1;
1243 		uio.uio_segflg = UIO_USERSPACE;
1244 		uio.uio_td = td;
1245 #ifdef COMPAT_FREEBSD32
1246 		tmp = wrap32 ? piod32->piod_op : piod->piod_op;
1247 #else
1248 		tmp = piod->piod_op;
1249 #endif
1250 		switch (tmp) {
1251 		case PIOD_READ_D:
1252 		case PIOD_READ_I:
1253 			CTR3(KTR_PTRACE, "PT_IO: pid %d: READ (%p, %#x)",
1254 			    p->p_pid, (uintptr_t)uio.uio_offset, uio.uio_resid);
1255 			uio.uio_rw = UIO_READ;
1256 			break;
1257 		case PIOD_WRITE_D:
1258 		case PIOD_WRITE_I:
1259 			CTR3(KTR_PTRACE, "PT_IO: pid %d: WRITE (%p, %#x)",
1260 			    p->p_pid, (uintptr_t)uio.uio_offset, uio.uio_resid);
1261 			td2->td_dbgflags |= TDB_USERWR;
1262 			uio.uio_rw = UIO_WRITE;
1263 			break;
1264 		default:
1265 			error = EINVAL;
1266 			goto out;
1267 		}
1268 		PROC_UNLOCK(p);
1269 		error = proc_rwmem(p, &uio);
1270 #ifdef COMPAT_FREEBSD32
1271 		if (wrap32)
1272 			piod32->piod_len -= uio.uio_resid;
1273 		else
1274 #endif
1275 			piod->piod_len -= uio.uio_resid;
1276 		PROC_LOCK(p);
1277 		break;
1278 
1279 	case PT_KILL:
1280 		CTR1(KTR_PTRACE, "PT_KILL: pid %d", p->p_pid);
1281 		data = SIGKILL;
1282 		goto sendsig;	/* in PT_CONTINUE above */
1283 
1284 	case PT_SETREGS:
1285 		CTR2(KTR_PTRACE, "PT_SETREGS: tid %d (pid %d)", td2->td_tid,
1286 		    p->p_pid);
1287 		td2->td_dbgflags |= TDB_USERWR;
1288 		error = PROC_WRITE(regs, td2, addr);
1289 		break;
1290 
1291 	case PT_GETREGS:
1292 		CTR2(KTR_PTRACE, "PT_GETREGS: tid %d (pid %d)", td2->td_tid,
1293 		    p->p_pid);
1294 		error = PROC_READ(regs, td2, addr);
1295 		break;
1296 
1297 	case PT_SETFPREGS:
1298 		CTR2(KTR_PTRACE, "PT_SETFPREGS: tid %d (pid %d)", td2->td_tid,
1299 		    p->p_pid);
1300 		td2->td_dbgflags |= TDB_USERWR;
1301 		error = PROC_WRITE(fpregs, td2, addr);
1302 		break;
1303 
1304 	case PT_GETFPREGS:
1305 		CTR2(KTR_PTRACE, "PT_GETFPREGS: tid %d (pid %d)", td2->td_tid,
1306 		    p->p_pid);
1307 		error = PROC_READ(fpregs, td2, addr);
1308 		break;
1309 
1310 	case PT_SETDBREGS:
1311 		CTR2(KTR_PTRACE, "PT_SETDBREGS: tid %d (pid %d)", td2->td_tid,
1312 		    p->p_pid);
1313 		td2->td_dbgflags |= TDB_USERWR;
1314 		error = PROC_WRITE(dbregs, td2, addr);
1315 		break;
1316 
1317 	case PT_GETDBREGS:
1318 		CTR2(KTR_PTRACE, "PT_GETDBREGS: tid %d (pid %d)", td2->td_tid,
1319 		    p->p_pid);
1320 		error = PROC_READ(dbregs, td2, addr);
1321 		break;
1322 
1323 	case PT_LWPINFO:
1324 		if (data <= 0 ||
1325 #ifdef COMPAT_FREEBSD32
1326 		    (!wrap32 && data > sizeof(*pl)) ||
1327 		    (wrap32 && data > sizeof(*pl32))) {
1328 #else
1329 		    data > sizeof(*pl)) {
1330 #endif
1331 			error = EINVAL;
1332 			break;
1333 		}
1334 #ifdef COMPAT_FREEBSD32
1335 		if (wrap32) {
1336 			pl = &plr;
1337 			pl32 = addr;
1338 		} else
1339 #endif
1340 		pl = addr;
1341 		bzero(pl, sizeof(*pl));
1342 		pl->pl_lwpid = td2->td_tid;
1343 		pl->pl_event = PL_EVENT_NONE;
1344 		pl->pl_flags = 0;
1345 		if (td2->td_dbgflags & TDB_XSIG) {
1346 			pl->pl_event = PL_EVENT_SIGNAL;
1347 			if (td2->td_si.si_signo != 0 &&
1348 #ifdef COMPAT_FREEBSD32
1349 			    ((!wrap32 && data >= offsetof(struct ptrace_lwpinfo,
1350 			    pl_siginfo) + sizeof(pl->pl_siginfo)) ||
1351 			    (wrap32 && data >= offsetof(struct ptrace_lwpinfo32,
1352 			    pl_siginfo) + sizeof(struct siginfo32)))
1353 #else
1354 			    data >= offsetof(struct ptrace_lwpinfo, pl_siginfo)
1355 			    + sizeof(pl->pl_siginfo)
1356 #endif
1357 			){
1358 				pl->pl_flags |= PL_FLAG_SI;
1359 				pl->pl_siginfo = td2->td_si;
1360 			}
1361 		}
1362 		if (td2->td_dbgflags & TDB_SCE)
1363 			pl->pl_flags |= PL_FLAG_SCE;
1364 		else if (td2->td_dbgflags & TDB_SCX)
1365 			pl->pl_flags |= PL_FLAG_SCX;
1366 		if (td2->td_dbgflags & TDB_EXEC)
1367 			pl->pl_flags |= PL_FLAG_EXEC;
1368 		if (td2->td_dbgflags & TDB_FORK) {
1369 			pl->pl_flags |= PL_FLAG_FORKED;
1370 			pl->pl_child_pid = td2->td_dbg_forked;
1371 			if (td2->td_dbgflags & TDB_VFORK)
1372 				pl->pl_flags |= PL_FLAG_VFORKED;
1373 		} else if ((td2->td_dbgflags & (TDB_SCX | TDB_VFORK)) ==
1374 		    TDB_VFORK)
1375 			pl->pl_flags |= PL_FLAG_VFORK_DONE;
1376 		if (td2->td_dbgflags & TDB_CHILD)
1377 			pl->pl_flags |= PL_FLAG_CHILD;
1378 		if (td2->td_dbgflags & TDB_BORN)
1379 			pl->pl_flags |= PL_FLAG_BORN;
1380 		if (td2->td_dbgflags & TDB_EXIT)
1381 			pl->pl_flags |= PL_FLAG_EXITED;
1382 		pl->pl_sigmask = td2->td_sigmask;
1383 		pl->pl_siglist = td2->td_siglist;
1384 		strcpy(pl->pl_tdname, td2->td_name);
1385 		if ((td2->td_dbgflags & (TDB_SCE | TDB_SCX)) != 0) {
1386 			pl->pl_syscall_code = td2->td_sa.code;
1387 			pl->pl_syscall_narg = td2->td_sa.narg;
1388 		} else {
1389 			pl->pl_syscall_code = 0;
1390 			pl->pl_syscall_narg = 0;
1391 		}
1392 #ifdef COMPAT_FREEBSD32
1393 		if (wrap32)
1394 			ptrace_lwpinfo_to32(pl, pl32);
1395 #endif
1396 		CTR6(KTR_PTRACE,
1397     "PT_LWPINFO: tid %d (pid %d) event %d flags %#x child pid %d syscall %d",
1398 		    td2->td_tid, p->p_pid, pl->pl_event, pl->pl_flags,
1399 		    pl->pl_child_pid, pl->pl_syscall_code);
1400 		break;
1401 
1402 	case PT_GETNUMLWPS:
1403 		CTR2(KTR_PTRACE, "PT_GETNUMLWPS: pid %d: %d threads", p->p_pid,
1404 		    p->p_numthreads);
1405 		td->td_retval[0] = p->p_numthreads;
1406 		break;
1407 
1408 	case PT_GETLWPLIST:
1409 		CTR3(KTR_PTRACE, "PT_GETLWPLIST: pid %d: data %d, actual %d",
1410 		    p->p_pid, data, p->p_numthreads);
1411 		if (data <= 0) {
1412 			error = EINVAL;
1413 			break;
1414 		}
1415 		num = imin(p->p_numthreads, data);
1416 		PROC_UNLOCK(p);
1417 		buf = malloc(num * sizeof(lwpid_t), M_TEMP, M_WAITOK);
1418 		tmp = 0;
1419 		PROC_LOCK(p);
1420 		FOREACH_THREAD_IN_PROC(p, td2) {
1421 			if (tmp >= num)
1422 				break;
1423 			buf[tmp++] = td2->td_tid;
1424 		}
1425 		PROC_UNLOCK(p);
1426 		error = copyout(buf, addr, tmp * sizeof(lwpid_t));
1427 		free(buf, M_TEMP);
1428 		if (!error)
1429 			td->td_retval[0] = tmp;
1430 		PROC_LOCK(p);
1431 		break;
1432 
1433 	case PT_VM_TIMESTAMP:
1434 		CTR2(KTR_PTRACE, "PT_VM_TIMESTAMP: pid %d: timestamp %d",
1435 		    p->p_pid, p->p_vmspace->vm_map.timestamp);
1436 		td->td_retval[0] = p->p_vmspace->vm_map.timestamp;
1437 		break;
1438 
1439 	case PT_VM_ENTRY:
1440 		PROC_UNLOCK(p);
1441 #ifdef COMPAT_FREEBSD32
1442 		if (wrap32)
1443 			error = ptrace_vm_entry32(td, p, addr);
1444 		else
1445 #endif
1446 		error = ptrace_vm_entry(td, p, addr);
1447 		PROC_LOCK(p);
1448 		break;
1449 
1450 	default:
1451 #ifdef __HAVE_PTRACE_MACHDEP
1452 		if (req >= PT_FIRSTMACH) {
1453 			PROC_UNLOCK(p);
1454 			error = cpu_ptrace(td2, req, addr, data);
1455 			PROC_LOCK(p);
1456 		} else
1457 #endif
1458 			/* Unknown request. */
1459 			error = EINVAL;
1460 		break;
1461 	}
1462 
1463 out:
1464 	/* Drop our hold on this process now that the request has completed. */
1465 	_PRELE(p);
1466 fail:
1467 	PROC_UNLOCK(p);
1468 	if (proctree_locked)
1469 		sx_xunlock(&proctree_lock);
1470 	return (error);
1471 }
1472 #undef PROC_READ
1473 #undef PROC_WRITE
1474 
1475 /*
1476  * Stop a process because of a debugging event;
1477  * stay stopped until p->p_step is cleared
1478  * (cleared by PIOCCONT in procfs).
1479  */
1480 void
1481 stopevent(struct proc *p, unsigned int event, unsigned int val)
1482 {
1483 
1484 	PROC_LOCK_ASSERT(p, MA_OWNED);
1485 	p->p_step = 1;
1486 	CTR3(KTR_PTRACE, "stopevent: pid %d event %u val %u", p->p_pid, event,
1487 	    val);
1488 	do {
1489 		if (event != S_EXIT)
1490 			p->p_xsig = val;
1491 		p->p_xthread = NULL;
1492 		p->p_stype = event;	/* Which event caused the stop? */
1493 		wakeup(&p->p_stype);	/* Wake up any PIOCWAIT'ing procs */
1494 		msleep(&p->p_step, &p->p_mtx, PWAIT, "stopevent", 0);
1495 	} while (p->p_step);
1496 }
1497