subr_uio.c revision 220114 
1/*-
2 * Copyright (c) 1982, 1986, 1991, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 4. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 *	@(#)kern_subr.c	8.3 (Berkeley) 1/21/94
35 */
36
37#include <sys/cdefs.h>
38__FBSDID("$FreeBSD: head/sys/kern/subr_uio.c 220114 2011-03-28 19:44:54Z kib $");
39
40#include "opt_zero.h"
41
42#include <sys/param.h>
43#include <sys/systm.h>
44#include <sys/kernel.h>
45#include <sys/limits.h>
46#include <sys/lock.h>
47#include <sys/mman.h>
48#include <sys/mutex.h>
49#include <sys/proc.h>
50#include <sys/resourcevar.h>
51#include <sys/sched.h>
52#include <sys/sysctl.h>
53#include <sys/vnode.h>
54
55#include <vm/vm.h>
56#include <vm/vm_extern.h>
57#include <vm/vm_page.h>
58#include <vm/vm_map.h>
59#ifdef ZERO_COPY_SOCKETS
60#include <vm/vm_param.h>
61#include <vm/vm_object.h>
62#endif
63
64SYSCTL_INT(_kern, KERN_IOV_MAX, iov_max, CTLFLAG_RD, NULL, UIO_MAXIOV,
65	"Maximum number of elements in an I/O vector; sysconf(_SC_IOV_MAX)");
66
67#ifdef ZERO_COPY_SOCKETS
68/* Declared in uipc_socket.c */
69extern int so_zero_copy_receive;
70
71/*
72 * Identify the physical page mapped at the given kernel virtual
73 * address.  Insert this physical page into the given address space at
74 * the given virtual address, replacing the physical page, if any,
75 * that already exists there.
76 */
77static int
78vm_pgmoveco(vm_map_t mapa, vm_offset_t kaddr, vm_offset_t uaddr)
79{
80	vm_map_t map = mapa;
81	vm_page_t kern_pg, user_pg;
82	vm_object_t uobject;
83	vm_map_entry_t entry;
84	vm_pindex_t upindex;
85	vm_prot_t prot;
86	boolean_t wired;
87
88	KASSERT((uaddr & PAGE_MASK) == 0,
89	    ("vm_pgmoveco: uaddr is not page aligned"));
90
91	/*
92	 * Herein the physical page is validated and dirtied.  It is
93	 * unwired in sf_buf_mext().
94	 */
95	kern_pg = PHYS_TO_VM_PAGE(vtophys(kaddr));
96	kern_pg->valid = VM_PAGE_BITS_ALL;
97	KASSERT(kern_pg->queue == PQ_NONE && kern_pg->wire_count == 1,
98	    ("vm_pgmoveco: kern_pg is not correctly wired"));
99
100	if ((vm_map_lookup(&map, uaddr,
101			   VM_PROT_WRITE, &entry, &uobject,
102			   &upindex, &prot, &wired)) != KERN_SUCCESS) {
103		return(EFAULT);
104	}
105	VM_OBJECT_LOCK(uobject);
106retry:
107	if ((user_pg = vm_page_lookup(uobject, upindex)) != NULL) {
108		if (vm_page_sleep_if_busy(user_pg, TRUE, "vm_pgmoveco"))
109			goto retry;
110		vm_page_lock(user_pg);
111		pmap_remove_all(user_pg);
112		vm_page_free(user_pg);
113		vm_page_unlock(user_pg);
114	} else {
115		/*
116		 * Even if a physical page does not exist in the
117		 * object chain's first object, a physical page from a
118		 * backing object may be mapped read only.
119		 */
120		if (uobject->backing_object != NULL)
121			pmap_remove(map->pmap, uaddr, uaddr + PAGE_SIZE);
122	}
123	vm_page_insert(kern_pg, uobject, upindex);
124	vm_page_dirty(kern_pg);
125	VM_OBJECT_UNLOCK(uobject);
126	vm_map_lookup_done(map, entry);
127	return(KERN_SUCCESS);
128}
129#endif /* ZERO_COPY_SOCKETS */
130
131int
132uiomove(void *cp, int n, struct uio *uio)
133{
134	struct thread *td = curthread;
135	struct iovec *iov;
136	u_int cnt;
137	int error = 0;
138	int save = 0;
139
140	KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
141	    ("uiomove: mode"));
142	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
143	    ("uiomove proc"));
144	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
145	    "Calling uiomove()");
146
147	save = td->td_pflags & TDP_DEADLKTREAT;
148	td->td_pflags |= TDP_DEADLKTREAT;
149
150	while (n > 0 && uio->uio_resid) {
151		iov = uio->uio_iov;
152		cnt = iov->iov_len;
153		if (cnt == 0) {
154			uio->uio_iov++;
155			uio->uio_iovcnt--;
156			continue;
157		}
158		if (cnt > n)
159			cnt = n;
160
161		switch (uio->uio_segflg) {
162
163		case UIO_USERSPACE:
164			maybe_yield();
165			if (uio->uio_rw == UIO_READ)
166				error = copyout(cp, iov->iov_base, cnt);
167			else
168				error = copyin(iov->iov_base, cp, cnt);
169			if (error)
170				goto out;
171			break;
172
173		case UIO_SYSSPACE:
174			if (uio->uio_rw == UIO_READ)
175				bcopy(cp, iov->iov_base, cnt);
176			else
177				bcopy(iov->iov_base, cp, cnt);
178			break;
179		case UIO_NOCOPY:
180			break;
181		}
182		iov->iov_base = (char *)iov->iov_base + cnt;
183		iov->iov_len -= cnt;
184		uio->uio_resid -= cnt;
185		uio->uio_offset += cnt;
186		cp = (char *)cp + cnt;
187		n -= cnt;
188	}
189out:
190	if (save == 0)
191		td->td_pflags &= ~TDP_DEADLKTREAT;
192	return (error);
193}
194
195/*
196 * Wrapper for uiomove() that validates the arguments against a known-good
197 * kernel buffer.  Currently, uiomove accepts a signed (n) argument, which
198 * is almost definitely a bad thing, so we catch that here as well.  We
199 * return a runtime failure, but it might be desirable to generate a runtime
200 * assertion failure instead.
201 */
202int
203uiomove_frombuf(void *buf, int buflen, struct uio *uio)
204{
205	unsigned int offset, n;
206
207	if (uio->uio_offset < 0 || uio->uio_resid < 0 ||
208	    (offset = uio->uio_offset) != uio->uio_offset)
209		return (EINVAL);
210	if (buflen <= 0 || offset >= buflen)
211		return (0);
212	if ((n = buflen - offset) > INT_MAX)
213		return (EINVAL);
214	return (uiomove((char *)buf + offset, n, uio));
215}
216
217#ifdef ZERO_COPY_SOCKETS
218/*
219 * Experimental support for zero-copy I/O
220 */
221static int
222userspaceco(void *cp, u_int cnt, struct uio *uio, int disposable)
223{
224	struct iovec *iov;
225	int error;
226
227	iov = uio->uio_iov;
228	if (uio->uio_rw == UIO_READ) {
229		if ((so_zero_copy_receive != 0)
230		 && ((cnt & PAGE_MASK) == 0)
231		 && ((((intptr_t) iov->iov_base) & PAGE_MASK) == 0)
232		 && ((uio->uio_offset & PAGE_MASK) == 0)
233		 && ((((intptr_t) cp) & PAGE_MASK) == 0)
234		 && (disposable != 0)) {
235			/* SOCKET: use page-trading */
236			/*
237			 * We only want to call vm_pgmoveco() on
238			 * disposeable pages, since it gives the
239			 * kernel page to the userland process.
240			 */
241			error =	vm_pgmoveco(&curproc->p_vmspace->vm_map,
242			    (vm_offset_t)cp, (vm_offset_t)iov->iov_base);
243
244			/*
245			 * If we get an error back, attempt
246			 * to use copyout() instead.  The
247			 * disposable page should be freed
248			 * automatically if we weren't able to move
249			 * it into userland.
250			 */
251			if (error != 0)
252				error = copyout(cp, iov->iov_base, cnt);
253		} else {
254			error = copyout(cp, iov->iov_base, cnt);
255		}
256	} else {
257		error = copyin(iov->iov_base, cp, cnt);
258	}
259	return (error);
260}
261
262int
263uiomoveco(void *cp, int n, struct uio *uio, int disposable)
264{
265	struct iovec *iov;
266	u_int cnt;
267	int error;
268
269	KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
270	    ("uiomoveco: mode"));
271	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
272	    ("uiomoveco proc"));
273
274	while (n > 0 && uio->uio_resid) {
275		iov = uio->uio_iov;
276		cnt = iov->iov_len;
277		if (cnt == 0) {
278			uio->uio_iov++;
279			uio->uio_iovcnt--;
280			continue;
281		}
282		if (cnt > n)
283			cnt = n;
284
285		switch (uio->uio_segflg) {
286
287		case UIO_USERSPACE:
288			maybe_yield();
289			error = userspaceco(cp, cnt, uio, disposable);
290			if (error)
291				return (error);
292			break;
293
294		case UIO_SYSSPACE:
295			if (uio->uio_rw == UIO_READ)
296				bcopy(cp, iov->iov_base, cnt);
297			else
298				bcopy(iov->iov_base, cp, cnt);
299			break;
300		case UIO_NOCOPY:
301			break;
302		}
303		iov->iov_base = (char *)iov->iov_base + cnt;
304		iov->iov_len -= cnt;
305		uio->uio_resid -= cnt;
306		uio->uio_offset += cnt;
307		cp = (char *)cp + cnt;
308		n -= cnt;
309	}
310	return (0);
311}
312#endif /* ZERO_COPY_SOCKETS */
313
314/*
315 * Give next character to user as result of read.
316 */
317int
318ureadc(int c, struct uio *uio)
319{
320	struct iovec *iov;
321	char *iov_base;
322
323	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
324	    "Calling ureadc()");
325
326again:
327	if (uio->uio_iovcnt == 0 || uio->uio_resid == 0)
328		panic("ureadc");
329	iov = uio->uio_iov;
330	if (iov->iov_len == 0) {
331		uio->uio_iovcnt--;
332		uio->uio_iov++;
333		goto again;
334	}
335	switch (uio->uio_segflg) {
336
337	case UIO_USERSPACE:
338		if (subyte(iov->iov_base, c) < 0)
339			return (EFAULT);
340		break;
341
342	case UIO_SYSSPACE:
343		iov_base = iov->iov_base;
344		*iov_base = c;
345		iov->iov_base = iov_base;
346		break;
347
348	case UIO_NOCOPY:
349		break;
350	}
351	iov->iov_base = (char *)iov->iov_base + 1;
352	iov->iov_len--;
353	uio->uio_resid--;
354	uio->uio_offset++;
355	return (0);
356}
357
358int
359copyinfrom(const void * __restrict src, void * __restrict dst, size_t len,
360    int seg)
361{
362	int error = 0;
363
364	switch (seg) {
365	case UIO_USERSPACE:
366		error = copyin(src, dst, len);
367		break;
368	case UIO_SYSSPACE:
369		bcopy(src, dst, len);
370		break;
371	default:
372		panic("copyinfrom: bad seg %d\n", seg);
373	}
374	return (error);
375}
376
377int
378copyinstrfrom(const void * __restrict src, void * __restrict dst, size_t len,
379    size_t * __restrict copied, int seg)
380{
381	int error = 0;
382
383	switch (seg) {
384	case UIO_USERSPACE:
385		error = copyinstr(src, dst, len, copied);
386		break;
387	case UIO_SYSSPACE:
388		error = copystr(src, dst, len, copied);
389		break;
390	default:
391		panic("copyinstrfrom: bad seg %d\n", seg);
392	}
393	return (error);
394}
395
396int
397copyiniov(struct iovec *iovp, u_int iovcnt, struct iovec **iov, int error)
398{
399	u_int iovlen;
400
401	*iov = NULL;
402	if (iovcnt > UIO_MAXIOV)
403		return (error);
404	iovlen = iovcnt * sizeof (struct iovec);
405	*iov = malloc(iovlen, M_IOV, M_WAITOK);
406	error = copyin(iovp, *iov, iovlen);
407	if (error) {
408		free(*iov, M_IOV);
409		*iov = NULL;
410	}
411	return (error);
412}
413
414int
415copyinuio(struct iovec *iovp, u_int iovcnt, struct uio **uiop)
416{
417	struct iovec *iov;
418	struct uio *uio;
419	u_int iovlen;
420	int error, i;
421
422	*uiop = NULL;
423	if (iovcnt > UIO_MAXIOV)
424		return (EINVAL);
425	iovlen = iovcnt * sizeof (struct iovec);
426	uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
427	iov = (struct iovec *)(uio + 1);
428	error = copyin(iovp, iov, iovlen);
429	if (error) {
430		free(uio, M_IOV);
431		return (error);
432	}
433	uio->uio_iov = iov;
434	uio->uio_iovcnt = iovcnt;
435	uio->uio_segflg = UIO_USERSPACE;
436	uio->uio_offset = -1;
437	uio->uio_resid = 0;
438	for (i = 0; i < iovcnt; i++) {
439		if (iov->iov_len > INT_MAX - uio->uio_resid) {
440			free(uio, M_IOV);
441			return (EINVAL);
442		}
443		uio->uio_resid += iov->iov_len;
444		iov++;
445	}
446	*uiop = uio;
447	return (0);
448}
449
450struct uio *
451cloneuio(struct uio *uiop)
452{
453	struct uio *uio;
454	int iovlen;
455
456	iovlen = uiop->uio_iovcnt * sizeof (struct iovec);
457	uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
458	*uio = *uiop;
459	uio->uio_iov = (struct iovec *)(uio + 1);
460	bcopy(uiop->uio_iov, uio->uio_iov, iovlen);
461	return (uio);
462}
463
464/*
465 * Map some anonymous memory in user space of size sz, rounded up to the page
466 * boundary.
467 */
468int
469copyout_map(struct thread *td, vm_offset_t *addr, size_t sz)
470{
471	struct vmspace *vms;
472	int error;
473	vm_size_t size;
474
475	vms = td->td_proc->p_vmspace;
476
477	/*
478	 * Map somewhere after heap in process memory.
479	 */
480	PROC_LOCK(td->td_proc);
481	*addr = round_page((vm_offset_t)vms->vm_daddr +
482	    lim_max(td->td_proc, RLIMIT_DATA));
483	PROC_UNLOCK(td->td_proc);
484
485	/* round size up to page boundry */
486	size = (vm_size_t)round_page(sz);
487
488	error = vm_mmap(&vms->vm_map, addr, size, PROT_READ | PROT_WRITE,
489	    VM_PROT_ALL, MAP_PRIVATE | MAP_ANON, OBJT_DEFAULT, NULL, 0);
490
491	return (error);
492}
493
494/*
495 * Unmap memory in user space.
496 */
497int
498copyout_unmap(struct thread *td, vm_offset_t addr, size_t sz)
499{
500	vm_map_t map;
501	vm_size_t size;
502
503	if (sz == 0)
504		return (0);
505
506	map = &td->td_proc->p_vmspace->vm_map;
507	size = (vm_size_t)round_page(sz);
508
509	if (vm_map_remove(map, addr, addr + size) != KERN_SUCCESS)
510		return (EINVAL);
511
512	return (0);
513}
514