xref: /dragonfly/sys/kern/kern_memio.c (revision 2b3f93ea)
1 /*-
2  * Copyright (c) 1988 University of Utah.
3  * Copyright (c) 1982, 1986, 1990 The Regents of the University of California.
4  * All rights reserved.
5  *
6  * This code is derived from software contributed to Berkeley by
7  * the Systems Programming Group of the University of Utah Computer
8  * Science Department, and code derived from software contributed to
9  * Berkeley by William Jolitz.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  *
35  *	from: Utah $Hdr: mem.c 1.13 89/10/08$
36  *	from: @(#)mem.c	7.2 (Berkeley) 5/9/91
37  * $FreeBSD: src/sys/i386/i386/mem.c,v 1.79.2.9 2003/01/04 22:58:01 njl Exp $
38  */
39 
40 /*
41  * Memory special file
42  */
43 
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/buf.h>
47 #include <sys/conf.h>
48 #include <sys/fcntl.h>
49 #include <sys/filio.h>
50 #include <sys/interrupt.h>
51 #include <sys/kernel.h>
52 #include <sys/malloc.h>
53 #include <sys/memrange.h>
54 #include <sys/proc.h>
55 #include <sys/caps.h>
56 #include <sys/queue.h>
57 #include <sys/random.h>
58 #include <sys/signalvar.h>
59 #include <sys/uio.h>
60 #include <sys/vnode.h>
61 #include <sys/sysctl.h>
62 
63 #include <sys/signal2.h>
64 #include <sys/spinlock2.h>
65 
66 #include <vm/vm.h>
67 #include <vm/pmap.h>
68 #include <vm/vm_map.h>
69 #include <vm/vm_extern.h>
70 
71 
72 static	d_open_t	mmopen;
73 static	d_close_t	mmclose;
74 static	d_read_t	mmread;
75 static	d_write_t	mmwrite;
76 static	d_ioctl_t	mmioctl;
77 #if 0
78 static	d_mmap_t	memmmap;
79 #endif
80 static	d_kqfilter_t	mmkqfilter;
81 static int memuksmap(vm_map_backing_t ba, int op, cdev_t dev, vm_page_t fake);
82 
83 #define CDEV_MAJOR 2
84 static struct dev_ops mem_ops = {
85 	{ "mem", 0, D_MPSAFE | D_QUICK },
86 	.d_open =	mmopen,
87 	.d_close =	mmclose,
88 	.d_read =	mmread,
89 	.d_write =	mmwrite,
90 	.d_ioctl =	mmioctl,
91 	.d_kqfilter =	mmkqfilter,
92 #if 0
93 	.d_mmap =	memmmap,
94 #endif
95 	.d_uksmap =	memuksmap
96 };
97 
98 static struct dev_ops mem_ops_mem = {
99 	{ "mem", 0, D_MEM | D_MPSAFE | D_QUICK },
100 	.d_open =	mmopen,
101 	.d_close =	mmclose,
102 	.d_read =	mmread,
103 	.d_write =	mmwrite,
104 	.d_ioctl =	mmioctl,
105 	.d_kqfilter =	mmkqfilter,
106 #if 0
107 	.d_mmap =	memmmap,
108 #endif
109 	.d_uksmap =	memuksmap
110 };
111 
112 static struct dev_ops mem_ops_noq = {
113 	{ "mem", 0, D_MPSAFE },
114 	.d_open =	mmopen,
115 	.d_close =	mmclose,
116 	.d_read =	mmread,
117 	.d_write =	mmwrite,
118 	.d_ioctl =	mmioctl,
119 	.d_kqfilter =	mmkqfilter,
120 #if 0
121 	.d_mmap =	memmmap,
122 #endif
123 	.d_uksmap =	memuksmap
124 };
125 
126 static int rand_bolt;
127 static caddr_t	zbuf;
128 static cdev_t	zerodev = NULL;
129 static struct lock mem_lock = LOCK_INITIALIZER("memlk", 0, 0);
130 
131 MALLOC_DEFINE(M_MEMDESC, "memdesc", "memory range descriptors");
132 static int mem_ioctl (cdev_t, u_long, caddr_t, int, struct ucred *);
133 static int random_ioctl (cdev_t, u_long, caddr_t, int, struct ucred *);
134 
135 struct mem_range_softc mem_range_softc;
136 
137 static int seedenable;
138 SYSCTL_INT(_kern, OID_AUTO, seedenable, CTLFLAG_RW, &seedenable, 0, "");
139 
140 static int
141 mmopen(struct dev_open_args *ap)
142 {
143 	cdev_t dev = ap->a_head.a_dev;
144 	int error;
145 
146 	switch (minor(dev)) {
147 	case 0:
148 	case 1:
149 		/*
150 		 * /dev/mem and /dev/kmem
151 		 */
152 		if (ap->a_oflags & FWRITE) {
153 			if (securelevel > 0 || kernel_mem_readonly)
154 				return (EPERM);
155 		}
156 		error = 0;
157 		break;
158 	case 6:
159 		/*
160 		 * /dev/kpmap can only be opened for reading.
161 		 */
162 		if (ap->a_oflags & FWRITE)
163 			return (EPERM);
164 		error = 0;
165 		break;
166 	case 14:
167 		error = caps_priv_check(ap->a_cred, SYSCAP_RESTRICTEDROOT);
168 		if (error != 0)
169 			break;
170 		if (securelevel > 0 || kernel_mem_readonly) {
171 			error = EPERM;
172 			break;
173 		}
174 		error = cpu_set_iopl();
175 		break;
176 	default:
177 		error = 0;
178 		break;
179 	}
180 	return (error);
181 }
182 
183 static int
184 mmclose(struct dev_close_args *ap)
185 {
186 	cdev_t dev = ap->a_head.a_dev;
187 	int error;
188 
189 	switch (minor(dev)) {
190 	case 14:
191 		error = cpu_clr_iopl();
192 		break;
193 	default:
194 		error = 0;
195 		break;
196 	}
197 	return (error);
198 }
199 
200 
201 static int
202 mmrw(cdev_t dev, struct uio *uio, int flags)
203 {
204 	int o;
205 	u_int c;
206 	u_int poolsize;
207 	u_long v;
208 	struct iovec *iov;
209 	int error = 0;
210 	caddr_t buf = NULL;
211 
212 	while (uio->uio_resid > 0 && error == 0) {
213 		iov = uio->uio_iov;
214 		if (iov->iov_len == 0) {
215 			uio->uio_iov++;
216 			uio->uio_iovcnt--;
217 			if (uio->uio_iovcnt < 0)
218 				panic("mmrw");
219 			continue;
220 		}
221 		switch (minor(dev)) {
222 		case 0:
223 			/*
224 			 * minor device 0 is physical memory, /dev/mem
225 			 */
226 			v = uio->uio_offset;
227 			v &= ~(long)PAGE_MASK;
228 			pmap_kenter((vm_offset_t)ptvmmap, v);
229 			o = (int)uio->uio_offset & PAGE_MASK;
230 			c = (u_int)(PAGE_SIZE - ((uintptr_t)iov->iov_base & PAGE_MASK));
231 			c = min(c, (u_int)(PAGE_SIZE - o));
232 			c = min(c, (u_int)iov->iov_len);
233 			error = uiomove((caddr_t)&ptvmmap[o], (int)c, uio);
234 			pmap_kremove((vm_offset_t)ptvmmap);
235 			continue;
236 
237 		case 1: {
238 			/*
239 			 * minor device 1 is kernel memory, /dev/kmem
240 			 */
241 			vm_offset_t saddr, eaddr;
242 			int prot;
243 
244 			c = iov->iov_len;
245 
246 			/*
247 			 * Make sure that all of the pages are currently
248 			 * resident so that we don't create any zero-fill
249 			 * pages.
250 			 */
251 			saddr = trunc_page(uio->uio_offset);
252 			eaddr = round_page(uio->uio_offset + c);
253 			if (saddr > eaddr)
254 				return EFAULT;
255 
256 			/*
257 			 * Make sure the kernel addresses are mapped.
258 			 * platform_direct_mapped() can be used to bypass
259 			 * default mapping via the page table (virtual kernels
260 			 * contain a lot of out-of-band data).
261 			 */
262 			prot = VM_PROT_READ;
263 			if (uio->uio_rw != UIO_READ)
264 				prot |= VM_PROT_WRITE;
265 			error = kvm_access_check(saddr, eaddr, prot);
266 			if (error)
267 				return (error);
268 			error = uiomove((caddr_t)(vm_offset_t)uio->uio_offset,
269 					(int)c, uio);
270 			continue;
271 		}
272 		case 2:
273 			/*
274 			 * minor device 2 (/dev/null) is EOF/RATHOLE
275 			 */
276 			if (uio->uio_rw == UIO_READ)
277 				return (0);
278 			c = iov->iov_len;
279 			break;
280 		case 3:
281 			/*
282 			 * minor device 3 (/dev/random) is source of filth
283 			 * on read, seeder on write
284 			 */
285 			if (buf == NULL)
286 				buf = kmalloc(PAGE_SIZE, M_TEMP, M_WAITOK);
287 			c = min(iov->iov_len, PAGE_SIZE);
288 			if (uio->uio_rw == UIO_WRITE) {
289 				error = uiomove(buf, (int)c, uio);
290 				if (error == 0 &&
291 				    seedenable &&
292 				    securelevel <= 0) {
293 					error = add_buffer_randomness_src(buf, c, RAND_SRC_SEEDING);
294 				} else if (error == 0) {
295 					error = EPERM;
296 				}
297 			} else {
298 				poolsize = read_random(buf, c, 0);
299 				if (poolsize == 0) {
300 					if (buf)
301 						kfree(buf, M_TEMP);
302 					if ((flags & IO_NDELAY) != 0)
303 						return (EWOULDBLOCK);
304 					return (0);
305 				}
306 				c = min(c, poolsize);
307 				error = uiomove(buf, (int)c, uio);
308 			}
309 			continue;
310 		case 4:
311 			/*
312 			 * minor device 4 (/dev/urandom) is source of muck
313 			 * on read, writes are disallowed.
314 			 */
315 			c = min(iov->iov_len, PAGE_SIZE);
316 			if (uio->uio_rw == UIO_WRITE) {
317 				error = EPERM;
318 				break;
319 			}
320 			if (CURSIG(curthread->td_lwp) != 0) {
321 				/*
322 				 * Use tsleep() to get the error code right.
323 				 * It should return immediately.
324 				 */
325 				error = tsleep(&rand_bolt, PCATCH, "urand", 1);
326 				if (error != 0 && error != EWOULDBLOCK)
327 					continue;
328 			}
329 			if (buf == NULL)
330 				buf = kmalloc(PAGE_SIZE, M_TEMP, M_WAITOK);
331 			poolsize = read_random(buf, c, 1);
332 			c = min(c, poolsize);
333 			error = uiomove(buf, (int)c, uio);
334 			continue;
335 		/* case 5: read/write not supported, mmap only */
336 		/* case 6: read/write not supported, mmap only */
337 		case 12:
338 			/*
339 			 * minor device 12 (/dev/zero) is source of nulls
340 			 * on read, write are disallowed.
341 			 */
342 			if (uio->uio_rw == UIO_WRITE) {
343 				c = iov->iov_len;
344 				break;
345 			}
346 			if (zbuf == NULL) {
347 				zbuf = (caddr_t)kmalloc(PAGE_SIZE, M_TEMP,
348 				    M_WAITOK | M_ZERO);
349 			}
350 			c = min(iov->iov_len, PAGE_SIZE);
351 			error = uiomove(zbuf, (int)c, uio);
352 			continue;
353 		default:
354 			return (ENODEV);
355 		}
356 		if (error)
357 			break;
358 		iov->iov_base = (char *)iov->iov_base + c;
359 		iov->iov_len -= c;
360 		uio->uio_offset += c;
361 		uio->uio_resid -= c;
362 	}
363 	if (buf)
364 		kfree(buf, M_TEMP);
365 	return (error);
366 }
367 
368 static int
369 mmread(struct dev_read_args *ap)
370 {
371 	return(mmrw(ap->a_head.a_dev, ap->a_uio, ap->a_ioflag));
372 }
373 
374 static int
375 mmwrite(struct dev_write_args *ap)
376 {
377 	return(mmrw(ap->a_head.a_dev, ap->a_uio, ap->a_ioflag));
378 }
379 
380 /*******************************************************\
381 * allow user processes to MMAP some memory sections	*
382 * instead of going through read/write			*
383 \*******************************************************/
384 
385 static int user_kernel_mapping(vm_map_backing_t ba, int num,
386 			vm_ooffset_t offset, vm_ooffset_t *resultp);
387 
388 static int
389 memuksmap(vm_map_backing_t ba, int op, cdev_t dev, vm_page_t fake)
390 {
391 	vm_ooffset_t result;
392 	int error;
393 	struct lwp *lp;
394 
395 	error = 0;
396 
397 	switch(op) {
398 	case UKSMAPOP_ADD:
399 		/*
400 		 * We only need to track mappings for /dev/lpmap, all process
401 		 * mappings will be deleted when the process exits and we
402 		 * do not need to track kernel mappings.
403 		 */
404 		if (minor(dev) == 7) {
405 			lp = ba->aux_info;
406 			spin_lock(&lp->lwp_spin);
407 			TAILQ_INSERT_TAIL(&lp->lwp_lpmap_backing_list,
408 					  ba, entry);
409 			spin_unlock(&lp->lwp_spin);
410 		}
411 		break;
412 	case UKSMAPOP_REM:
413 		/*
414 		 * We only need to track mappings for /dev/lpmap, all process
415 		 * mappings will be deleted when the process exits and we
416 		 * do not need to track kernel mappings.
417 		 */
418 		if (minor(dev) == 7) {
419 			lp = ba->aux_info;
420 			spin_lock(&lp->lwp_spin);
421 			TAILQ_REMOVE(&lp->lwp_lpmap_backing_list, ba, entry);
422 			spin_unlock(&lp->lwp_spin);
423 		}
424 		break;
425 	case UKSMAPOP_FAULT:
426 		switch (minor(dev)) {
427 		case 0:
428 			/*
429 			 * minor device 0 is physical memory
430 			 */
431 			fake->phys_addr = ptoa(fake->pindex);
432 			break;
433 		case 1:
434 			/*
435 			 * minor device 1 is kernel memory
436 			 */
437 			fake->phys_addr = vtophys(ptoa(fake->pindex));
438 			break;
439 		case 5:
440 		case 6:
441 		case 7:
442 			/*
443 			 * minor device 5 is /dev/upmap (see sys/upmap.h)
444 			 * minor device 6 is /dev/kpmap (see sys/upmap.h)
445 			 * minor device 7 is /dev/lpmap (see sys/upmap.h)
446 			 */
447 			result = 0;
448 			error = user_kernel_mapping(ba,
449 						    minor(dev),
450 						    ptoa(fake->pindex),
451 						    &result);
452 			fake->phys_addr = result;
453 			break;
454 		default:
455 			error = EINVAL;
456 			break;
457 		}
458 		break;
459 	default:
460 		error = EINVAL;
461 		break;
462 	}
463 	return error;
464 }
465 
466 static int
467 mmioctl(struct dev_ioctl_args *ap)
468 {
469 	cdev_t dev = ap->a_head.a_dev;
470 	int error;
471 
472 	lockmgr(&mem_lock, LK_EXCLUSIVE);
473 
474 	switch (minor(dev)) {
475 	case 0:
476 		error = mem_ioctl(dev, ap->a_cmd, ap->a_data,
477 				  ap->a_fflag, ap->a_cred);
478 		break;
479 	case 3:
480 	case 4:
481 		error = random_ioctl(dev, ap->a_cmd, ap->a_data,
482 				     ap->a_fflag, ap->a_cred);
483 		break;
484 	default:
485 		error = ENODEV;
486 		break;
487 	}
488 
489 	lockmgr(&mem_lock, LK_RELEASE);
490 
491 	return (error);
492 }
493 
494 /*
495  * Operations for changing memory attributes.
496  *
497  * This is basically just an ioctl shim for mem_range_attr_get
498  * and mem_range_attr_set.
499  */
500 static int
501 mem_ioctl(cdev_t dev, u_long cmd, caddr_t data, int flags, struct ucred *cred)
502 {
503 	int nd, error = 0;
504 	struct mem_range_op *mo = (struct mem_range_op *)data;
505 	struct mem_range_desc *md;
506 
507 	/* is this for us? */
508 	if ((cmd != MEMRANGE_GET) &&
509 	    (cmd != MEMRANGE_SET))
510 		return (ENOTTY);
511 
512 	/* any chance we can handle this? */
513 	if (mem_range_softc.mr_op == NULL)
514 		return (EOPNOTSUPP);
515 
516 	/* do we have any descriptors? */
517 	if (mem_range_softc.mr_ndesc == 0)
518 		return (ENXIO);
519 
520 	switch (cmd) {
521 	case MEMRANGE_GET:
522 		nd = imin(mo->mo_arg[0], mem_range_softc.mr_ndesc);
523 		if (nd > 0) {
524 			md = (struct mem_range_desc *)
525 				kmalloc(nd * sizeof(struct mem_range_desc),
526 				       M_MEMDESC, M_WAITOK);
527 			error = mem_range_attr_get(md, &nd);
528 			if (!error)
529 				error = copyout(md, mo->mo_desc,
530 					nd * sizeof(struct mem_range_desc));
531 			kfree(md, M_MEMDESC);
532 		} else {
533 			nd = mem_range_softc.mr_ndesc;
534 		}
535 		mo->mo_arg[0] = nd;
536 		break;
537 
538 	case MEMRANGE_SET:
539 		md = (struct mem_range_desc *)kmalloc(sizeof(struct mem_range_desc),
540 						    M_MEMDESC, M_WAITOK);
541 		error = copyin(mo->mo_desc, md, sizeof(struct mem_range_desc));
542 		/* clamp description string */
543 		md->mr_owner[sizeof(md->mr_owner) - 1] = 0;
544 		if (error == 0)
545 			error = mem_range_attr_set(md, &mo->mo_arg[0]);
546 		kfree(md, M_MEMDESC);
547 		break;
548 	}
549 	return (error);
550 }
551 
552 /*
553  * Implementation-neutral, kernel-callable functions for manipulating
554  * memory range attributes.
555  */
556 int
557 mem_range_attr_get(struct mem_range_desc *mrd, int *arg)
558 {
559 	/* can we handle this? */
560 	if (mem_range_softc.mr_op == NULL)
561 		return (EOPNOTSUPP);
562 
563 	if (*arg == 0) {
564 		*arg = mem_range_softc.mr_ndesc;
565 	} else {
566 		bcopy(mem_range_softc.mr_desc, mrd, (*arg) * sizeof(struct mem_range_desc));
567 	}
568 	return (0);
569 }
570 
571 int
572 mem_range_attr_set(struct mem_range_desc *mrd, int *arg)
573 {
574 	/* can we handle this? */
575 	if (mem_range_softc.mr_op == NULL)
576 		return (EOPNOTSUPP);
577 
578 	return (mem_range_softc.mr_op->set(&mem_range_softc, mrd, arg));
579 }
580 
581 void
582 mem_range_AP_init(void)
583 {
584 	if (mem_range_softc.mr_op && mem_range_softc.mr_op->initAP)
585 		mem_range_softc.mr_op->initAP(&mem_range_softc);
586 }
587 
588 static int
589 random_ioctl(cdev_t dev, u_long cmd, caddr_t data, int flags, struct ucred *cred)
590 {
591 	int error;
592 	int intr;
593 
594 	/*
595 	 * Even inspecting the state is privileged, since it gives a hint
596 	 * about how easily the randomness might be guessed.
597 	 */
598 	error = 0;
599 
600 	switch (cmd) {
601 	/* Really handled in upper layer */
602 	case FIOASYNC:
603 		break;
604 	case MEM_SETIRQ:
605 		intr = *(int16_t *)data;
606 		if ((error = caps_priv_check(cred, SYSCAP_RESTRICTEDROOT)) != 0)
607 			break;
608 		if (intr < 0 || intr >= MAX_INTS)
609 			return (EINVAL);
610 		register_randintr(intr);
611 		break;
612 	case MEM_CLEARIRQ:
613 		intr = *(int16_t *)data;
614 		if ((error = caps_priv_check(cred, SYSCAP_RESTRICTEDROOT)) != 0)
615 			break;
616 		if (intr < 0 || intr >= MAX_INTS)
617 			return (EINVAL);
618 		unregister_randintr(intr);
619 		break;
620 	case MEM_RETURNIRQ:
621 		error = ENOTSUP;
622 		break;
623 	case MEM_FINDIRQ:
624 		intr = *(int16_t *)data;
625 		if ((error = caps_priv_check(cred, SYSCAP_RESTRICTEDROOT)) != 0)
626 			break;
627 		if (intr < 0 || intr >= MAX_INTS)
628 			return (EINVAL);
629 		intr = next_registered_randintr(intr);
630 		if (intr == MAX_INTS)
631 			return (ENOENT);
632 		*(u_int16_t *)data = intr;
633 		break;
634 	default:
635 		error = ENOTSUP;
636 		break;
637 	}
638 	return (error);
639 }
640 
641 static int
642 mm_filter_read(struct knote *kn, long hint)
643 {
644 	return (1);
645 }
646 
647 static int
648 mm_filter_write(struct knote *kn, long hint)
649 {
650 	return (1);
651 }
652 
653 static void
654 dummy_filter_detach(struct knote *kn) {}
655 
656 /* Implemented in kern_nrandom.c */
657 static struct filterops random_read_filtops =
658         { FILTEROP_ISFD|FILTEROP_MPSAFE, NULL, dummy_filter_detach, random_filter_read };
659 
660 static struct filterops mm_read_filtops =
661         { FILTEROP_ISFD|FILTEROP_MPSAFE, NULL, dummy_filter_detach, mm_filter_read };
662 
663 static struct filterops mm_write_filtops =
664         { FILTEROP_ISFD|FILTEROP_MPSAFE, NULL, dummy_filter_detach, mm_filter_write };
665 
666 static int
667 mmkqfilter(struct dev_kqfilter_args *ap)
668 {
669 	struct knote *kn = ap->a_kn;
670 	cdev_t dev = ap->a_head.a_dev;
671 
672 	ap->a_result = 0;
673 	switch (kn->kn_filter) {
674 	case EVFILT_READ:
675 		switch (minor(dev)) {
676 		case 3:
677 			kn->kn_fop = &random_read_filtops;
678 			break;
679 		default:
680 			kn->kn_fop = &mm_read_filtops;
681 			break;
682 		}
683 		break;
684 	case EVFILT_WRITE:
685 		kn->kn_fop = &mm_write_filtops;
686 		break;
687 	default:
688 		ap->a_result = EOPNOTSUPP;
689 		return (0);
690 	}
691 
692 	return (0);
693 }
694 
695 int
696 iszerodev(cdev_t dev)
697 {
698 	return (zerodev == dev);
699 }
700 
701 /*
702  * /dev/lpmap, /dev/upmap, /dev/kpmap.
703  */
704 static int
705 user_kernel_mapping(vm_map_backing_t ba, int num, vm_ooffset_t offset,
706 		    vm_ooffset_t *resultp)
707 {
708 	struct proc *p;
709 	struct lwp *lp;
710 	int error;
711 	int invfork;
712 
713 	if (offset < 0)
714 		return (EINVAL);
715 
716 	error = EINVAL;
717 
718 	switch(num) {
719 	case 5:
720 		/*
721 		 * /dev/upmap - maps RW per-process shared user-kernel area.
722 		 */
723 
724 		/*
725 		 * If this is a child currently in vfork the pmap is shared
726 		 * with the parent!  We need to actually set-up the parent's
727 		 * p_upmap, not the child's, and we need to set the invfork
728 		 * flag.  Userland will probably adjust its static state so
729 		 * it must be consistent with the parent or userland will be
730 		 * really badly confused.
731 		 *
732 		 * (this situation can happen when user code in vfork() calls
733 		 *  libc's getpid() or some other function which then decides
734 		 *  it wants the upmap).
735 		 */
736 		p = ba->aux_info;
737 		if (p == NULL)
738 			break;
739 		if (p->p_flags & P_PPWAIT) {
740 			p = p->p_pptr;
741 			if (p == NULL)
742 				return (EINVAL);
743 			invfork = 1;
744 		} else {
745 			invfork = 0;
746 		}
747 
748 		/*
749 		 * Create the kernel structure as required, set the invfork
750 		 * flag if we are faulting in on a vfork().
751 		 */
752 		if (p->p_upmap == NULL)
753 			proc_usermap(p, invfork);
754 		if (p->p_upmap && invfork)
755 			p->p_upmap->invfork = invfork;
756 
757 		/*
758 		 * Extract address for pmap
759 		 */
760 		if (p->p_upmap &&
761 		    offset < roundup2(sizeof(*p->p_upmap), PAGE_SIZE)) {
762 			/* only good for current process */
763 			*resultp = pmap_kextract((vm_offset_t)p->p_upmap +
764 						 offset);
765 			error = 0;
766 		}
767 		break;
768 	case 6:
769 		/*
770 		 * /dev/kpmap - maps RO shared kernel global page
771 		 *
772 		 * Extract address for pmap
773 		 */
774 		if (kpmap &&
775 		    offset < roundup2(sizeof(*kpmap), PAGE_SIZE)) {
776 			*resultp = pmap_kextract((vm_offset_t)kpmap + offset);
777 			error = 0;
778 		}
779 		break;
780 	case 7:
781 		/*
782 		 * /dev/lpmap - maps RW per-thread shared user-kernel area.
783 		 */
784 		lp = ba->aux_info;
785 		if (lp == NULL)
786 			break;
787 
788 		/*
789 		 * Create the kernel structure as required
790 		 */
791 		if (lp->lwp_lpmap == NULL)
792 			lwp_usermap(lp, -1);	/* second arg not yet XXX */
793 
794 		/*
795 		 * Extract address for pmap
796 		 */
797 		if (lp->lwp_lpmap &&
798 		    offset < roundup2(sizeof(*lp->lwp_lpmap), PAGE_SIZE)) {
799 			/* only good for current process */
800 			*resultp = pmap_kextract((vm_offset_t)lp->lwp_lpmap +
801 						 offset);
802 			error = 0;
803 		}
804 		break;
805 	default:
806 		break;
807 	}
808 	return error;
809 }
810 
811 static void
812 mem_drvinit(void *unused)
813 {
814 
815 	/* Initialise memory range handling */
816 	if (mem_range_softc.mr_op != NULL)
817 		mem_range_softc.mr_op->init(&mem_range_softc);
818 
819 	make_dev(&mem_ops_mem, 0, UID_ROOT, GID_KMEM, 0640, "mem");
820 	make_dev(&mem_ops_mem, 1, UID_ROOT, GID_KMEM, 0640, "kmem");
821 	make_dev(&mem_ops, 2, UID_ROOT, GID_WHEEL, 0666, "null");
822 	make_dev(&mem_ops, 3, UID_ROOT, GID_WHEEL, 0644, "random");
823 	make_dev(&mem_ops, 4, UID_ROOT, GID_WHEEL, 0644, "urandom");
824 	make_dev(&mem_ops, 5, UID_ROOT, GID_WHEEL, 0666, "upmap");
825 	make_dev(&mem_ops, 6, UID_ROOT, GID_WHEEL, 0444, "kpmap");
826 	make_dev(&mem_ops, 7, UID_ROOT, GID_WHEEL, 0666, "lpmap");
827 	zerodev = make_dev(&mem_ops, 12, UID_ROOT, GID_WHEEL, 0666, "zero");
828 	make_dev(&mem_ops_noq, 14, UID_ROOT, GID_WHEEL, 0600, "io");
829 }
830 
831 SYSINIT(memdev, SI_SUB_DRIVERS, SI_ORDER_MIDDLE + CDEV_MAJOR, mem_drvinit,
832     NULL);
833 
834