xref: /dragonfly/sys/kern/sys_process.c (revision 19b217af) 
1 /*
2  * Copyright (c) 1994, Sean Eric Fagan
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by Sean Eric Fagan.
16  * 4. The name of the author may not be used to endorse or promote products
17  *    derived from this software without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  *
31  * $FreeBSD: src/sys/kern/sys_process.c,v 1.51.2.6 2003/01/08 03:06:45 kan Exp $
32  * $DragonFly: src/sys/kern/sys_process.c,v 1.30 2007/02/19 01:14:23 corecode Exp $
33  */
34 
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/sysproto.h>
38 #include <sys/proc.h>
39 #include <sys/priv.h>
40 #include <sys/vnode.h>
41 #include <sys/ptrace.h>
42 #include <sys/reg.h>
43 #include <sys/lock.h>
44 
45 #include <vm/vm.h>
46 #include <vm/pmap.h>
47 #include <vm/vm_map.h>
48 #include <vm/vm_page.h>
49 
50 #include <sys/user.h>
51 #include <vfs/procfs/procfs.h>
52 
53 #include <sys/thread2.h>
54 #include <sys/spinlock2.h>
55 
56 /* use the equivalent procfs code */
57 #if 0
58 static int
59 pread (struct proc *procp, unsigned int addr, unsigned int *retval) {
60 	int		rv;
61 	vm_map_t	map, tmap;
62 	vm_object_t	object;
63 	vm_offset_t	kva = 0;
64 	int		page_offset;	/* offset into page */
65 	vm_offset_t	pageno;		/* page number */
66 	vm_map_entry_t	out_entry;
67 	vm_prot_t	out_prot;
68 	boolean_t	wired;
69 	vm_pindex_t	pindex;
70 
71 	/* Map page into kernel space */
72 
73 	map = &procp->p_vmspace->vm_map;
74 
75 	page_offset = addr - trunc_page(addr);
76 	pageno = trunc_page(addr);
77 
78 	tmap = map;
79 	rv = vm_map_lookup(&tmap, pageno, VM_PROT_READ, &out_entry,
80 			   &object, &pindex, &out_prot, &wired);
81 
82 	if (rv != KERN_SUCCESS)
83 		return EINVAL;
84 
85 	vm_map_lookup_done (tmap, out_entry, 0);
86 
87 	/* Find space in kernel_map for the page we're interested in */
88 	rv = vm_map_find (&kernel_map, object, IDX_TO_OFF(pindex),
89 			  &kva,
90 			  PAGE_SIZE, PAGE_SIZE,
91 			  0, VM_MAPTYPE_NORMAL,
92 			  VM_PROT_ALL, VM_PROT_ALL,
93 			  0);
94 
95 	if (!rv) {
96 		vm_object_reference XXX (object);
97 
98 		rv = vm_map_wire (&kernel_map, kva, kva + PAGE_SIZE, 0);
99 		if (!rv) {
100 			*retval = 0;
101 			bcopy ((caddr_t)kva + page_offset,
102 			       retval, sizeof *retval);
103 		}
104 		vm_map_remove (&kernel_map, kva, kva + PAGE_SIZE);
105 	}
106 
107 	return rv;
108 }
109 
110 static int
111 pwrite (struct proc *procp, unsigned int addr, unsigned int datum) {
112 	int		rv;
113 	vm_map_t	map, tmap;
114 	vm_object_t	object;
115 	vm_offset_t	kva = 0;
116 	int		page_offset;	/* offset into page */
117 	vm_offset_t	pageno;		/* page number */
118 	vm_map_entry_t	out_entry;
119 	vm_prot_t	out_prot;
120 	boolean_t	wired;
121 	vm_pindex_t	pindex;
122 	boolean_t	fix_prot = 0;
123 
124 	/* Map page into kernel space */
125 
126 	map = &procp->p_vmspace->vm_map;
127 
128 	page_offset = addr - trunc_page(addr);
129 	pageno = trunc_page(addr);
130 
131 	/*
132 	 * Check the permissions for the area we're interested in.
133 	 */
134 
135 	if (vm_map_check_protection (map, pageno, pageno + PAGE_SIZE,
136 				     VM_PROT_WRITE, FALSE) == FALSE) {
137 		/*
138 		 * If the page was not writable, we make it so.
139 		 * XXX It is possible a page may *not* be read/executable,
140 		 * if a process changes that!
141 		 */
142 		fix_prot = 1;
143 		/* The page isn't writable, so let's try making it so... */
144 		if ((rv = vm_map_protect (map, pageno, pageno + PAGE_SIZE,
145 			VM_PROT_ALL, 0)) != KERN_SUCCESS)
146 		  return EFAULT;	/* I guess... */
147 	}
148 
149 	/*
150 	 * Now we need to get the page.  out_entry, out_prot, wired, and
151 	 * single_use aren't used.  One would think the vm code would be
152 	 * a *bit* nicer...  We use tmap because vm_map_lookup() can
153 	 * change the map argument.
154 	 */
155 
156 	tmap = map;
157 	rv = vm_map_lookup(&tmap, pageno, VM_PROT_WRITE, &out_entry,
158 			   &object, &pindex, &out_prot, &wired);
159 	if (rv != KERN_SUCCESS)
160 		return EINVAL;
161 
162 	/*
163 	 * Okay, we've got the page.  Let's release tmap.
164 	 */
165 	vm_map_lookup_done (tmap, out_entry, 0);
166 
167 	/*
168 	 * Fault the page in...
169 	 */
170 	rv = vm_fault(map, pageno, VM_PROT_WRITE|VM_PROT_READ, FALSE);
171 	if (rv != KERN_SUCCESS)
172 		return EFAULT;
173 
174 	/* Find space in kernel_map for the page we're interested in */
175 	rv = vm_map_find (&kernel_map, object, IDX_TO_OFF(pindex),
176 			  &kva,
177 			  PAGE_SIZE, PAGE_SIZE,
178 			  0, VM_MAPTYPE_NORMAL,
179 			  VM_PROT_ALL, VM_PROT_ALL,
180 			  0);
181 	if (!rv) {
182 		vm_object_reference XXX (object);
183 
184 		rv = vm_map_wire (&kernel_map, kva, kva + PAGE_SIZE, 0);
185 		if (!rv) {
186 		  bcopy (&datum, (caddr_t)kva + page_offset, sizeof datum);
187 		}
188 		vm_map_remove (&kernel_map, kva, kva + PAGE_SIZE);
189 	}
190 
191 	if (fix_prot)
192 		vm_map_protect (map, pageno, pageno + PAGE_SIZE,
193 			VM_PROT_READ|VM_PROT_EXECUTE, 0);
194 	return rv;
195 }
196 #endif
197 
198 /*
199  * Process debugging system call.
200  *
201  * MPALMOSTSAFE
202  */
203 int
204 sys_ptrace(struct ptrace_args *uap)
205 {
206 	struct proc *p = curproc;
207 
208 	/*
209 	 * XXX this obfuscation is to reduce stack usage, but the register
210 	 * structs may be too large to put on the stack anyway.
211 	 */
212 	union {
213 		struct ptrace_io_desc piod;
214 		struct dbreg dbreg;
215 		struct fpreg fpreg;
216 		struct reg reg;
217 	} r;
218 	void *addr;
219 	int error = 0;
220 
221 	addr = &r;
222 	switch (uap->req) {
223 	case PT_GETREGS:
224 	case PT_GETFPREGS:
225 #ifdef PT_GETDBREGS
226 	case PT_GETDBREGS:
227 #endif
228 		break;
229 	case PT_SETREGS:
230 		error = copyin(uap->addr, &r.reg, sizeof r.reg);
231 		break;
232 	case PT_SETFPREGS:
233 		error = copyin(uap->addr, &r.fpreg, sizeof r.fpreg);
234 		break;
235 #ifdef PT_SETDBREGS
236 	case PT_SETDBREGS:
237 		error = copyin(uap->addr, &r.dbreg, sizeof r.dbreg);
238 		break;
239 #endif
240 	case PT_IO:
241 		error = copyin(uap->addr, &r.piod, sizeof r.piod);
242 		break;
243 	default:
244 		addr = uap->addr;
245 	}
246 	if (error)
247 		return (error);
248 
249 	error = kern_ptrace(p, uap->req, uap->pid, addr, uap->data,
250 			&uap->sysmsg_result);
251 	if (error)
252 		return (error);
253 
254 	switch (uap->req) {
255 	case PT_IO:
256 		(void)copyout(&r.piod, uap->addr, sizeof r.piod);
257 		break;
258 	case PT_GETREGS:
259 		error = copyout(&r.reg, uap->addr, sizeof r.reg);
260 		break;
261 	case PT_GETFPREGS:
262 		error = copyout(&r.fpreg, uap->addr, sizeof r.fpreg);
263 		break;
264 #ifdef PT_GETDBREGS
265 	case PT_GETDBREGS:
266 		error = copyout(&r.dbreg, uap->addr, sizeof r.dbreg);
267 		break;
268 #endif
269 	}
270 
271 	return (error);
272 }
273 
274 int
275 kern_ptrace(struct proc *curp, int req, pid_t pid, void *addr,
276 	    int data, int *res)
277 {
278 	struct proc *p, *pp;
279 	struct lwp *lp;
280 	struct iovec iov;
281 	struct uio uio;
282 	struct ptrace_io_desc *piod;
283 	int error = 0;
284 	int write, tmp;
285 	int t;
286 
287 	write = 0;
288 	if (req == PT_TRACE_ME) {
289 		p = curp;
290 		PHOLD(p);
291 	} else {
292 		if ((p = pfind(pid)) == NULL)
293 			return ESRCH;
294 	}
295 	if (!PRISON_CHECK(curp->p_ucred, p->p_ucred)) {
296 		PRELE(p);
297 		return (ESRCH);
298 	}
299 
300 	lwkt_gettoken(&p->p_token);
301 	/* Can't trace a process that's currently exec'ing. */
302 	if ((p->p_flags & P_INEXEC) != 0) {
303 		lwkt_reltoken(&p->p_token);
304 		PRELE(p);
305 		return EAGAIN;
306 	}
307 
308 	/*
309 	 * Permissions check
310 	 */
311 	switch (req) {
312 	case PT_TRACE_ME:
313 		/* Always legal. */
314 		break;
315 
316 	case PT_ATTACH:
317 		/* Self */
318 		if (p->p_pid == curp->p_pid) {
319 			lwkt_reltoken(&p->p_token);
320 			PRELE(p);
321 			return EINVAL;
322 		}
323 
324 		/* Already traced */
325 		if (p->p_flags & P_TRACED) {
326 			lwkt_reltoken(&p->p_token);
327 			PRELE(p);
328 			return EBUSY;
329 		}
330 
331 		if (curp->p_flags & P_TRACED)
332 			for (pp = curp->p_pptr; pp != NULL; pp = pp->p_pptr)
333 				if (pp == p) {
334 					lwkt_reltoken(&p->p_token);
335 					PRELE(p);
336 					return (EINVAL);
337 				}
338 
339 		/* not owned by you, has done setuid (unless you're root) */
340 		if ((p->p_ucred->cr_ruid != curp->p_ucred->cr_ruid) ||
341 		     (p->p_flags & P_SUGID)) {
342 			if ((error = priv_check_cred(curp->p_ucred, PRIV_ROOT, 0)) != 0) {
343 				lwkt_reltoken(&p->p_token);
344 				PRELE(p);
345 				return error;
346 			}
347 		}
348 
349 		/* can't trace init when securelevel > 0 */
350 		if (securelevel > 0 && p->p_pid == 1) {
351 			lwkt_reltoken(&p->p_token);
352 			PRELE(p);
353 			return EPERM;
354 		}
355 
356 		/* OK */
357 		break;
358 
359 	case PT_READ_I:
360 	case PT_READ_D:
361 	case PT_WRITE_I:
362 	case PT_WRITE_D:
363 	case PT_IO:
364 	case PT_CONTINUE:
365 	case PT_KILL:
366 	case PT_STEP:
367 	case PT_DETACH:
368 #ifdef PT_GETREGS
369 	case PT_GETREGS:
370 #endif
371 #ifdef PT_SETREGS
372 	case PT_SETREGS:
373 #endif
374 #ifdef PT_GETFPREGS
375 	case PT_GETFPREGS:
376 #endif
377 #ifdef PT_SETFPREGS
378 	case PT_SETFPREGS:
379 #endif
380 #ifdef PT_GETDBREGS
381 	case PT_GETDBREGS:
382 #endif
383 #ifdef PT_SETDBREGS
384 	case PT_SETDBREGS:
385 #endif
386 		/* not being traced... */
387 		if ((p->p_flags & P_TRACED) == 0) {
388 			lwkt_reltoken(&p->p_token);
389 			PRELE(p);
390 			return EPERM;
391 		}
392 
393 		/* not being traced by YOU */
394 		if (p->p_pptr != curp) {
395 			lwkt_reltoken(&p->p_token);
396 			PRELE(p);
397 			return EBUSY;
398 		}
399 
400 		/* not currently stopped */
401 		if (p->p_stat != SSTOP ||
402 		    (p->p_flags & P_WAITED) == 0) {
403 			lwkt_reltoken(&p->p_token);
404 			PRELE(p);
405 			return EBUSY;
406 		}
407 
408 		/* OK */
409 		break;
410 
411 	default:
412 		lwkt_reltoken(&p->p_token);
413 		PRELE(p);
414 		return EINVAL;
415 	}
416 
417 	/* XXX lwp */
418 	lp = FIRST_LWP_IN_PROC(p);
419 #ifdef FIX_SSTEP
420 	/*
421 	 * Single step fixup ala procfs
422 	 */
423 	FIX_SSTEP(lp);
424 #endif
425 
426 	/*
427 	 * Actually do the requests
428 	 */
429 
430 	*res = 0;
431 
432 	switch (req) {
433 	case PT_TRACE_ME:
434 		/* set my trace flag and "owner" so it can read/write me */
435 		p->p_flags |= P_TRACED;
436 		p->p_oppid = p->p_pptr->p_pid;
437 		lwkt_reltoken(&p->p_token);
438 		PRELE(p);
439 		return 0;
440 
441 	case PT_ATTACH:
442 		/* security check done above */
443 		p->p_flags |= P_TRACED;
444 		p->p_oppid = p->p_pptr->p_pid;
445 		proc_reparent(p, curp);
446 		data = SIGSTOP;
447 		goto sendsig;	/* in PT_CONTINUE below */
448 
449 	case PT_STEP:
450 	case PT_CONTINUE:
451 	case PT_DETACH:
452 		/* Zero means do not send any signal */
453 		if (data < 0 || data > _SIG_MAXSIG) {
454 			lwkt_reltoken(&p->p_token);
455 			PRELE(p);
456 			return EINVAL;
457 		}
458 
459 		LWPHOLD(lp);
460 
461 		if (req == PT_STEP) {
462 			if ((error = ptrace_single_step (lp))) {
463 				LWPRELE(lp);
464 				lwkt_reltoken(&p->p_token);
465 				PRELE(p);
466 				return error;
467 			}
468 		}
469 
470 		if (addr != (void *)1) {
471 			if ((error = ptrace_set_pc (lp,
472 			    (u_long)(uintfptr_t)addr))) {
473 				LWPRELE(lp);
474 				lwkt_reltoken(&p->p_token);
475 				PRELE(p);
476 				return error;
477 			}
478 		}
479 		LWPRELE(lp);
480 
481 		if (req == PT_DETACH) {
482 			/* reset process parent */
483 			if (p->p_oppid != p->p_pptr->p_pid) {
484 				struct proc *pp;
485 
486 				pp = pfind(p->p_oppid);
487 				if (pp) {
488 					proc_reparent(p, pp);
489 					PRELE(pp);
490 				}
491 			}
492 
493 			p->p_flags &= ~(P_TRACED | P_WAITED);
494 			p->p_oppid = 0;
495 
496 			/* should we send SIGCHLD? */
497 		}
498 
499 	sendsig:
500 		/*
501 		 * Deliver or queue signal.  If the process is stopped
502 		 * force it to be SACTIVE again.
503 		 */
504 		crit_enter();
505 		if (p->p_stat == SSTOP) {
506 			p->p_xstat = data;
507 			proc_unstop(p);
508 		} else if (data) {
509 			ksignal(p, data);
510 		}
511 		crit_exit();
512 		lwkt_reltoken(&p->p_token);
513 		PRELE(p);
514 		return 0;
515 
516 	case PT_WRITE_I:
517 	case PT_WRITE_D:
518 		write = 1;
519 		/* fallthrough */
520 	case PT_READ_I:
521 	case PT_READ_D:
522 		/*
523 		 * NOTE! uio_offset represents the offset in the target
524 		 * process.  The iov is in the current process (the guy
525 		 * making the ptrace call) so uio_td must be the current
526 		 * process (though for a SYSSPACE transfer it doesn't
527 		 * really matter).
528 		 */
529 		tmp = 0;
530 		/* write = 0 set above */
531 		iov.iov_base = write ? (caddr_t)&data : (caddr_t)&tmp;
532 		iov.iov_len = sizeof(int);
533 		uio.uio_iov = &iov;
534 		uio.uio_iovcnt = 1;
535 		uio.uio_offset = (off_t)(uintptr_t)addr;
536 		uio.uio_resid = sizeof(int);
537 		uio.uio_segflg = UIO_SYSSPACE;
538 		uio.uio_rw = write ? UIO_WRITE : UIO_READ;
539 		uio.uio_td = curthread;
540 		error = procfs_domem(curp, lp, NULL, &uio);
541 		if (uio.uio_resid != 0) {
542 			/*
543 			 * XXX procfs_domem() doesn't currently return ENOSPC,
544 			 * so I think write() can bogusly return 0.
545 			 * XXX what happens for short writes?  We don't want
546 			 * to write partial data.
547 			 * XXX procfs_domem() returns EPERM for other invalid
548 			 * addresses.  Convert this to EINVAL.  Does this
549 			 * clobber returns of EPERM for other reasons?
550 			 */
551 			if (error == 0 || error == ENOSPC || error == EPERM)
552 				error = EINVAL;	/* EOF */
553 		}
554 		if (!write)
555 			*res = tmp;
556 		lwkt_reltoken(&p->p_token);
557 		PRELE(p);
558 		return (error);
559 
560 	case PT_IO:
561 		/*
562 		 * NOTE! uio_offset represents the offset in the target
563 		 * process.  The iov is in the current process (the guy
564 		 * making the ptrace call) so uio_td must be the current
565 		 * process.
566 		 */
567 		piod = addr;
568 		iov.iov_base = piod->piod_addr;
569 		iov.iov_len = piod->piod_len;
570 		uio.uio_iov = &iov;
571 		uio.uio_iovcnt = 1;
572 		uio.uio_offset = (off_t)(uintptr_t)piod->piod_offs;
573 		uio.uio_resid = piod->piod_len;
574 		uio.uio_segflg = UIO_USERSPACE;
575 		uio.uio_td = curthread;
576 		switch (piod->piod_op) {
577 		case PIOD_READ_D:
578 		case PIOD_READ_I:
579 			uio.uio_rw = UIO_READ;
580 			break;
581 		case PIOD_WRITE_D:
582 		case PIOD_WRITE_I:
583 			uio.uio_rw = UIO_WRITE;
584 			break;
585 		default:
586 			lwkt_reltoken(&p->p_token);
587 			PRELE(p);
588 			return (EINVAL);
589 		}
590 		error = procfs_domem(curp, lp, NULL, &uio);
591 		piod->piod_len -= uio.uio_resid;
592 		lwkt_reltoken(&p->p_token);
593 		PRELE(p);
594 		return (error);
595 
596 	case PT_KILL:
597 		data = SIGKILL;
598 		goto sendsig;	/* in PT_CONTINUE above */
599 
600 #ifdef PT_SETREGS
601 	case PT_SETREGS:
602 		write = 1;
603 		/* fallthrough */
604 #endif /* PT_SETREGS */
605 #ifdef PT_GETREGS
606 	case PT_GETREGS:
607 		/* write = 0 above */
608 #endif /* PT_SETREGS */
609 #if defined(PT_SETREGS) || defined(PT_GETREGS)
610 		if (!procfs_validregs(lp)) {	/* no P_SYSTEM procs please */
611 			lwkt_reltoken(&p->p_token);
612 			PRELE(p);
613 			return EINVAL;
614 		} else {
615 			iov.iov_base = addr;
616 			iov.iov_len = sizeof(struct reg);
617 			uio.uio_iov = &iov;
618 			uio.uio_iovcnt = 1;
619 			uio.uio_offset = 0;
620 			uio.uio_resid = sizeof(struct reg);
621 			uio.uio_segflg = UIO_SYSSPACE;
622 			uio.uio_rw = write ? UIO_WRITE : UIO_READ;
623 			uio.uio_td = curthread;
624 			t = procfs_doregs(curp, lp, NULL, &uio);
625 			lwkt_reltoken(&p->p_token);
626 			PRELE(p);
627 			return t;
628 		}
629 #endif /* defined(PT_SETREGS) || defined(PT_GETREGS) */
630 
631 #ifdef PT_SETFPREGS
632 	case PT_SETFPREGS:
633 		write = 1;
634 		/* fallthrough */
635 #endif /* PT_SETFPREGS */
636 #ifdef PT_GETFPREGS
637 	case PT_GETFPREGS:
638 		/* write = 0 above */
639 #endif /* PT_SETFPREGS */
640 #if defined(PT_SETFPREGS) || defined(PT_GETFPREGS)
641 		if (!procfs_validfpregs(lp)) {	/* no P_SYSTEM procs please */
642 			lwkt_reltoken(&p->p_token);
643 			PRELE(p);
644 			return EINVAL;
645 		} else {
646 			iov.iov_base = addr;
647 			iov.iov_len = sizeof(struct fpreg);
648 			uio.uio_iov = &iov;
649 			uio.uio_iovcnt = 1;
650 			uio.uio_offset = 0;
651 			uio.uio_resid = sizeof(struct fpreg);
652 			uio.uio_segflg = UIO_SYSSPACE;
653 			uio.uio_rw = write ? UIO_WRITE : UIO_READ;
654 			uio.uio_td = curthread;
655 			t = procfs_dofpregs(curp, lp, NULL, &uio);
656 			lwkt_reltoken(&p->p_token);
657 			PRELE(p);
658 			return t;
659 		}
660 #endif /* defined(PT_SETFPREGS) || defined(PT_GETFPREGS) */
661 
662 #ifdef PT_SETDBREGS
663 	case PT_SETDBREGS:
664 		write = 1;
665 		/* fallthrough */
666 #endif /* PT_SETDBREGS */
667 #ifdef PT_GETDBREGS
668 	case PT_GETDBREGS:
669 		/* write = 0 above */
670 #endif /* PT_SETDBREGS */
671 #if defined(PT_SETDBREGS) || defined(PT_GETDBREGS)
672 		if (!procfs_validdbregs(lp)) {	/* no P_SYSTEM procs please */
673 			lwkt_reltoken(&p->p_token);
674 			PRELE(p);
675 			return EINVAL;
676 		} else {
677 			iov.iov_base = addr;
678 			iov.iov_len = sizeof(struct dbreg);
679 			uio.uio_iov = &iov;
680 			uio.uio_iovcnt = 1;
681 			uio.uio_offset = 0;
682 			uio.uio_resid = sizeof(struct dbreg);
683 			uio.uio_segflg = UIO_SYSSPACE;
684 			uio.uio_rw = write ? UIO_WRITE : UIO_READ;
685 			uio.uio_td = curthread;
686 			t = procfs_dodbregs(curp, lp, NULL, &uio);
687 			lwkt_reltoken(&p->p_token);
688 			PRELE(p);
689 			return t;
690 		}
691 #endif /* defined(PT_SETDBREGS) || defined(PT_GETDBREGS) */
692 
693 	default:
694 		break;
695 	}
696 
697 	lwkt_reltoken(&p->p_token);
698 	PRELE(p);
699 
700 	return 0;
701 }
702 
703 int
704 trace_req(struct proc *p)
705 {
706 	return 1;
707 }
708 
709 /*
710  * stopevent()
711  *
712  * Stop a process because of a procfs event.  Stay stopped until p->p_step
713  * is cleared (cleared by PIOCCONT in procfs).
714  *
715  * MPSAFE
716  */
717 void
718 stopevent(struct proc *p, unsigned int event, unsigned int val)
719 {
720 	/*
721 	 * Set event info.  Recheck p_stops in case we are
722 	 * racing a close() on procfs.
723 	 */
724 	spin_lock(&p->p_spin);
725 	if ((p->p_stops & event) == 0) {
726 		spin_unlock(&p->p_spin);
727 		return;
728 	}
729 	p->p_xstat = val;
730 	p->p_stype = event;
731 	p->p_step = 1;
732 	tsleep_interlock(&p->p_step, 0);
733 	spin_unlock(&p->p_spin);
734 
735 	/*
736 	 * Wakeup any PIOCWAITing procs and wait for p_step to
737 	 * be cleared.
738 	 */
739 	for (;;) {
740 		wakeup(&p->p_stype);
741 		tsleep(&p->p_step, PINTERLOCKED, "stopevent", 0);
742 		spin_lock(&p->p_spin);
743 		if (p->p_step == 0) {
744 			spin_unlock(&p->p_spin);
745 			break;
746 		}
747 		tsleep_interlock(&p->p_step, 0);
748 		spin_unlock(&p->p_spin);
749 	}
750 }
751 
752