xref: /dragonfly/sys/kern/sys_process.c (revision 36a3d1d6) 
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 (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 	/*
164 	 * Okay, we've got the page.  Let's release tmap.
165 	 */
166 
167 	vm_map_lookup_done (tmap, out_entry, 0);
168 
169 	/*
170 	 * Fault the page in...
171 	 */
172 
173 	rv = vm_fault(map, pageno, VM_PROT_WRITE|VM_PROT_READ, FALSE);
174 	if (rv != KERN_SUCCESS)
175 		return EFAULT;
176 
177 	/* Find space in kernel_map for the page we're interested in */
178 	rv = vm_map_find (&kernel_map, object, IDX_TO_OFF(pindex),
179 			  &kva,
180 			  PAGE_SIZE, PAGE_SIZE,
181 			  0, VM_MAPTYPE_NORMAL,
182 			  VM_PROT_ALL, VM_PROT_ALL,
183 			  0);
184 	if (!rv) {
185 		vm_object_reference (object);
186 
187 		rv = vm_map_wire (&kernel_map, kva, kva + PAGE_SIZE, 0);
188 		if (!rv) {
189 		  bcopy (&datum, (caddr_t)kva + page_offset, sizeof datum);
190 		}
191 		vm_map_remove (&kernel_map, kva, kva + PAGE_SIZE);
192 	}
193 
194 	if (fix_prot)
195 		vm_map_protect (map, pageno, pageno + PAGE_SIZE,
196 			VM_PROT_READ|VM_PROT_EXECUTE, 0);
197 	return rv;
198 }
199 #endif
200 
201 /*
202  * Process debugging system call.
203  *
204  * MPALMOSTSAFE
205  */
206 int
207 sys_ptrace(struct ptrace_args *uap)
208 {
209 	struct proc *p = curproc;
210 
211 	/*
212 	 * XXX this obfuscation is to reduce stack usage, but the register
213 	 * structs may be too large to put on the stack anyway.
214 	 */
215 	union {
216 		struct ptrace_io_desc piod;
217 		struct dbreg dbreg;
218 		struct fpreg fpreg;
219 		struct reg reg;
220 	} r;
221 	void *addr;
222 	int error = 0;
223 
224 	addr = &r;
225 	switch (uap->req) {
226 	case PT_GETREGS:
227 	case PT_GETFPREGS:
228 #ifdef PT_GETDBREGS
229 	case PT_GETDBREGS:
230 #endif
231 		break;
232 	case PT_SETREGS:
233 		error = copyin(uap->addr, &r.reg, sizeof r.reg);
234 		break;
235 	case PT_SETFPREGS:
236 		error = copyin(uap->addr, &r.fpreg, sizeof r.fpreg);
237 		break;
238 #ifdef PT_SETDBREGS
239 	case PT_SETDBREGS:
240 		error = copyin(uap->addr, &r.dbreg, sizeof r.dbreg);
241 		break;
242 #endif
243 	case PT_IO:
244 		error = copyin(uap->addr, &r.piod, sizeof r.piod);
245 		break;
246 	default:
247 		addr = uap->addr;
248 	}
249 	if (error)
250 		return (error);
251 
252 	error = kern_ptrace(p, uap->req, uap->pid, addr, uap->data,
253 			&uap->sysmsg_result);
254 	if (error)
255 		return (error);
256 
257 	switch (uap->req) {
258 	case PT_IO:
259 		(void)copyout(&r.piod, uap->addr, sizeof r.piod);
260 		break;
261 	case PT_GETREGS:
262 		error = copyout(&r.reg, uap->addr, sizeof r.reg);
263 		break;
264 	case PT_GETFPREGS:
265 		error = copyout(&r.fpreg, uap->addr, sizeof r.fpreg);
266 		break;
267 #ifdef PT_GETDBREGS
268 	case PT_GETDBREGS:
269 		error = copyout(&r.dbreg, uap->addr, sizeof r.dbreg);
270 		break;
271 #endif
272 	}
273 
274 	return (error);
275 }
276 
277 int
278 kern_ptrace(struct proc *curp, int req, pid_t pid, void *addr, int data, int *res)
279 {
280 	struct proc *p, *pp;
281 	struct lwp *lp;
282 	struct iovec iov;
283 	struct uio uio;
284 	struct ptrace_io_desc *piod;
285 	int error = 0;
286 	int write, tmp;
287 	int t;
288 
289 	lwkt_gettoken(&proc_token);
290 
291 	write = 0;
292 	if (req == PT_TRACE_ME) {
293 		p = curp;
294 	} else {
295 		if ((p = pfind(pid)) == NULL) {
296 			lwkt_reltoken(&proc_token);
297 			return ESRCH;
298 		}
299 	}
300 	if (!PRISON_CHECK(curp->p_ucred, p->p_ucred)) {
301 		lwkt_reltoken(&proc_token);
302 		return (ESRCH);
303 	}
304 
305 	/* Can't trace a process that's currently exec'ing. */
306 	if ((p->p_flag & P_INEXEC) != 0) {
307 		lwkt_reltoken(&proc_token);
308 		return EAGAIN;
309 	}
310 
311 	/*
312 	 * Permissions check
313 	 */
314 	switch (req) {
315 	case PT_TRACE_ME:
316 		/* Always legal. */
317 		break;
318 
319 	case PT_ATTACH:
320 		/* Self */
321 		if (p->p_pid == curp->p_pid) {
322 			lwkt_reltoken(&proc_token);
323 			return EINVAL;
324 		}
325 
326 		/* Already traced */
327 		if (p->p_flag & P_TRACED) {
328 			lwkt_reltoken(&proc_token);
329 			return EBUSY;
330 		}
331 
332 		if (curp->p_flag & P_TRACED)
333 			for (pp = curp->p_pptr; pp != NULL; pp = pp->p_pptr)
334 				if (pp == p) {
335 					lwkt_reltoken(&proc_token);
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_flag & P_SUGID)) {
342 			if ((error = priv_check_cred(curp->p_ucred, PRIV_ROOT, 0)) != 0) {
343 				lwkt_reltoken(&proc_token);
344 				return error;
345 			}
346 		}
347 
348 		/* can't trace init when securelevel > 0 */
349 		if (securelevel > 0 && p->p_pid == 1) {
350 			lwkt_reltoken(&proc_token);
351 			return EPERM;
352 		}
353 
354 		/* OK */
355 		break;
356 
357 	case PT_READ_I:
358 	case PT_READ_D:
359 	case PT_WRITE_I:
360 	case PT_WRITE_D:
361 	case PT_IO:
362 	case PT_CONTINUE:
363 	case PT_KILL:
364 	case PT_STEP:
365 	case PT_DETACH:
366 #ifdef PT_GETREGS
367 	case PT_GETREGS:
368 #endif
369 #ifdef PT_SETREGS
370 	case PT_SETREGS:
371 #endif
372 #ifdef PT_GETFPREGS
373 	case PT_GETFPREGS:
374 #endif
375 #ifdef PT_SETFPREGS
376 	case PT_SETFPREGS:
377 #endif
378 #ifdef PT_GETDBREGS
379 	case PT_GETDBREGS:
380 #endif
381 #ifdef PT_SETDBREGS
382 	case PT_SETDBREGS:
383 #endif
384 		/* not being traced... */
385 		if ((p->p_flag & P_TRACED) == 0) {
386 			lwkt_reltoken(&proc_token);
387 			return EPERM;
388 		}
389 
390 		/* not being traced by YOU */
391 		if (p->p_pptr != curp) {
392 			lwkt_reltoken(&proc_token);
393 			return EBUSY;
394 		}
395 
396 		/* not currently stopped */
397 		if (p->p_stat != SSTOP ||
398 		    (p->p_flag & P_WAITED) == 0) {
399 			lwkt_reltoken(&proc_token);
400 			return EBUSY;
401 		}
402 
403 		/* OK */
404 		break;
405 
406 	default:
407 		lwkt_reltoken(&proc_token);
408 		return EINVAL;
409 	}
410 
411 	/* XXX lwp */
412 	lp = FIRST_LWP_IN_PROC(p);
413 #ifdef FIX_SSTEP
414 	/*
415 	 * Single step fixup ala procfs
416 	 */
417 	FIX_SSTEP(lp);
418 #endif
419 
420 	/*
421 	 * Actually do the requests
422 	 */
423 
424 	*res = 0;
425 
426 	switch (req) {
427 	case PT_TRACE_ME:
428 		/* set my trace flag and "owner" so it can read/write me */
429 		p->p_flag |= P_TRACED;
430 		p->p_oppid = p->p_pptr->p_pid;
431 		lwkt_reltoken(&proc_token);
432 		return 0;
433 
434 	case PT_ATTACH:
435 		/* security check done above */
436 		p->p_flag |= P_TRACED;
437 		p->p_oppid = p->p_pptr->p_pid;
438 		if (p->p_pptr != curp)
439 			proc_reparent(p, curp);
440 		data = SIGSTOP;
441 		goto sendsig;	/* in PT_CONTINUE below */
442 
443 	case PT_STEP:
444 	case PT_CONTINUE:
445 	case PT_DETACH:
446 		/* Zero means do not send any signal */
447 		if (data < 0 || data > _SIG_MAXSIG) {
448 			lwkt_reltoken(&proc_token);
449 			return EINVAL;
450 		}
451 
452 		LWPHOLD(lp);
453 
454 		if (req == PT_STEP) {
455 			if ((error = ptrace_single_step (lp))) {
456 				LWPRELE(lp);
457 				lwkt_reltoken(&proc_token);
458 				return error;
459 			}
460 		}
461 
462 		if (addr != (void *)1) {
463 			if ((error = ptrace_set_pc (lp,
464 			    (u_long)(uintfptr_t)addr))) {
465 				LWPRELE(lp);
466 				lwkt_reltoken(&proc_token);
467 				return error;
468 			}
469 		}
470 		LWPRELE(lp);
471 
472 		if (req == PT_DETACH) {
473 			/* reset process parent */
474 			if (p->p_oppid != p->p_pptr->p_pid) {
475 				struct proc *pp;
476 
477 				pp = pfind(p->p_oppid);
478 				proc_reparent(p, pp ? pp : initproc);
479 			}
480 
481 			p->p_flag &= ~(P_TRACED | P_WAITED);
482 			p->p_oppid = 0;
483 
484 			/* should we send SIGCHLD? */
485 		}
486 
487 	sendsig:
488 		/*
489 		 * Deliver or queue signal.  If the process is stopped
490 		 * force it to be SACTIVE again.
491 		 */
492 		crit_enter();
493 		if (p->p_stat == SSTOP) {
494 			p->p_xstat = data;
495 			lp->lwp_flag |= LWP_BREAKTSLEEP;
496 			proc_unstop(p);
497 		} else if (data) {
498 			ksignal(p, data);
499 		}
500 		crit_exit();
501 		lwkt_reltoken(&proc_token);
502 		return 0;
503 
504 	case PT_WRITE_I:
505 	case PT_WRITE_D:
506 		write = 1;
507 		/* fallthrough */
508 	case PT_READ_I:
509 	case PT_READ_D:
510 		/*
511 		 * NOTE! uio_offset represents the offset in the target
512 		 * process.  The iov is in the current process (the guy
513 		 * making the ptrace call) so uio_td must be the current
514 		 * process (though for a SYSSPACE transfer it doesn't
515 		 * really matter).
516 		 */
517 		tmp = 0;
518 		/* write = 0 set above */
519 		iov.iov_base = write ? (caddr_t)&data : (caddr_t)&tmp;
520 		iov.iov_len = sizeof(int);
521 		uio.uio_iov = &iov;
522 		uio.uio_iovcnt = 1;
523 		uio.uio_offset = (off_t)(uintptr_t)addr;
524 		uio.uio_resid = sizeof(int);
525 		uio.uio_segflg = UIO_SYSSPACE;
526 		uio.uio_rw = write ? UIO_WRITE : UIO_READ;
527 		uio.uio_td = curthread;
528 		error = procfs_domem(curp, lp, NULL, &uio);
529 		if (uio.uio_resid != 0) {
530 			/*
531 			 * XXX procfs_domem() doesn't currently return ENOSPC,
532 			 * so I think write() can bogusly return 0.
533 			 * XXX what happens for short writes?  We don't want
534 			 * to write partial data.
535 			 * XXX procfs_domem() returns EPERM for other invalid
536 			 * addresses.  Convert this to EINVAL.  Does this
537 			 * clobber returns of EPERM for other reasons?
538 			 */
539 			if (error == 0 || error == ENOSPC || error == EPERM)
540 				error = EINVAL;	/* EOF */
541 		}
542 		if (!write)
543 			*res = tmp;
544 		lwkt_reltoken(&proc_token);
545 		return (error);
546 
547 	case PT_IO:
548 		/*
549 		 * NOTE! uio_offset represents the offset in the target
550 		 * process.  The iov is in the current process (the guy
551 		 * making the ptrace call) so uio_td must be the current
552 		 * process.
553 		 */
554 		piod = addr;
555 		iov.iov_base = piod->piod_addr;
556 		iov.iov_len = piod->piod_len;
557 		uio.uio_iov = &iov;
558 		uio.uio_iovcnt = 1;
559 		uio.uio_offset = (off_t)(uintptr_t)piod->piod_offs;
560 		uio.uio_resid = piod->piod_len;
561 		uio.uio_segflg = UIO_USERSPACE;
562 		uio.uio_td = curthread;
563 		switch (piod->piod_op) {
564 		case PIOD_READ_D:
565 		case PIOD_READ_I:
566 			uio.uio_rw = UIO_READ;
567 			break;
568 		case PIOD_WRITE_D:
569 		case PIOD_WRITE_I:
570 			uio.uio_rw = UIO_WRITE;
571 			break;
572 		default:
573 			lwkt_reltoken(&proc_token);
574 			return (EINVAL);
575 		}
576 		error = procfs_domem(curp, lp, NULL, &uio);
577 		piod->piod_len -= uio.uio_resid;
578 		lwkt_reltoken(&proc_token);
579 		return (error);
580 
581 	case PT_KILL:
582 		data = SIGKILL;
583 		goto sendsig;	/* in PT_CONTINUE above */
584 
585 #ifdef PT_SETREGS
586 	case PT_SETREGS:
587 		write = 1;
588 		/* fallthrough */
589 #endif /* PT_SETREGS */
590 #ifdef PT_GETREGS
591 	case PT_GETREGS:
592 		/* write = 0 above */
593 #endif /* PT_SETREGS */
594 #if defined(PT_SETREGS) || defined(PT_GETREGS)
595 		if (!procfs_validregs(lp)) {	/* no P_SYSTEM procs please */
596 			lwkt_reltoken(&proc_token);
597 			return EINVAL;
598 		} else {
599 			iov.iov_base = addr;
600 			iov.iov_len = sizeof(struct reg);
601 			uio.uio_iov = &iov;
602 			uio.uio_iovcnt = 1;
603 			uio.uio_offset = 0;
604 			uio.uio_resid = sizeof(struct reg);
605 			uio.uio_segflg = UIO_SYSSPACE;
606 			uio.uio_rw = write ? UIO_WRITE : UIO_READ;
607 			uio.uio_td = curthread;
608 			t = procfs_doregs(curp, lp, NULL, &uio);
609 			lwkt_reltoken(&proc_token);
610 			return t;
611 		}
612 #endif /* defined(PT_SETREGS) || defined(PT_GETREGS) */
613 
614 #ifdef PT_SETFPREGS
615 	case PT_SETFPREGS:
616 		write = 1;
617 		/* fallthrough */
618 #endif /* PT_SETFPREGS */
619 #ifdef PT_GETFPREGS
620 	case PT_GETFPREGS:
621 		/* write = 0 above */
622 #endif /* PT_SETFPREGS */
623 #if defined(PT_SETFPREGS) || defined(PT_GETFPREGS)
624 		if (!procfs_validfpregs(lp)) {	/* no P_SYSTEM procs please */
625 			lwkt_reltoken(&proc_token);
626 			return EINVAL;
627 		} else {
628 			iov.iov_base = addr;
629 			iov.iov_len = sizeof(struct fpreg);
630 			uio.uio_iov = &iov;
631 			uio.uio_iovcnt = 1;
632 			uio.uio_offset = 0;
633 			uio.uio_resid = sizeof(struct fpreg);
634 			uio.uio_segflg = UIO_SYSSPACE;
635 			uio.uio_rw = write ? UIO_WRITE : UIO_READ;
636 			uio.uio_td = curthread;
637 			t = procfs_dofpregs(curp, lp, NULL, &uio);
638 			lwkt_reltoken(&proc_token);
639 			return t;
640 		}
641 #endif /* defined(PT_SETFPREGS) || defined(PT_GETFPREGS) */
642 
643 #ifdef PT_SETDBREGS
644 	case PT_SETDBREGS:
645 		write = 1;
646 		/* fallthrough */
647 #endif /* PT_SETDBREGS */
648 #ifdef PT_GETDBREGS
649 	case PT_GETDBREGS:
650 		/* write = 0 above */
651 #endif /* PT_SETDBREGS */
652 #if defined(PT_SETDBREGS) || defined(PT_GETDBREGS)
653 		if (!procfs_validdbregs(lp)) {	/* no P_SYSTEM procs please */
654 			lwkt_reltoken(&proc_token);
655 			return EINVAL;
656 		} else {
657 			iov.iov_base = addr;
658 			iov.iov_len = sizeof(struct dbreg);
659 			uio.uio_iov = &iov;
660 			uio.uio_iovcnt = 1;
661 			uio.uio_offset = 0;
662 			uio.uio_resid = sizeof(struct dbreg);
663 			uio.uio_segflg = UIO_SYSSPACE;
664 			uio.uio_rw = write ? UIO_WRITE : UIO_READ;
665 			uio.uio_td = curthread;
666 			t = procfs_dodbregs(curp, lp, NULL, &uio);
667 			lwkt_reltoken(&proc_token);
668 			return t;
669 		}
670 #endif /* defined(PT_SETDBREGS) || defined(PT_GETDBREGS) */
671 
672 	default:
673 		break;
674 	}
675 
676 	lwkt_reltoken(&proc_token);
677 	return 0;
678 }
679 
680 int
681 trace_req(struct proc *p)
682 {
683 	return 1;
684 }
685 
686 /*
687  * stopevent()
688  *
689  * Stop a process because of a procfs event.  Stay stopped until p->p_step
690  * is cleared (cleared by PIOCCONT in procfs).
691  *
692  * MPSAFE
693  */
694 void
695 stopevent(struct proc *p, unsigned int event, unsigned int val)
696 {
697 	/*
698 	 * Set event info.  Recheck p_stops in case we are
699 	 * racing a close() on procfs.
700 	 */
701 	spin_lock(&p->p_spin);
702 	if ((p->p_stops & event) == 0) {
703 		spin_unlock(&p->p_spin);
704 		return;
705 	}
706 	p->p_xstat = val;
707 	p->p_stype = event;
708 	p->p_step = 1;
709 	tsleep_interlock(&p->p_step, 0);
710 	spin_unlock(&p->p_spin);
711 
712 	/*
713 	 * Wakeup any PIOCWAITing procs and wait for p_step to
714 	 * be cleared.
715 	 */
716 	for (;;) {
717 		wakeup(&p->p_stype);
718 		tsleep(&p->p_step, PINTERLOCKED, "stopevent", 0);
719 		spin_lock(&p->p_spin);
720 		if (p->p_step == 0) {
721 			spin_unlock(&p->p_spin);
722 			break;
723 		}
724 		tsleep_interlock(&p->p_step, 0);
725 		spin_unlock(&p->p_spin);
726 	}
727 }
728 
729