uvm_io.c revision 1.24 
1/*	$NetBSD: uvm_io.c,v 1.24 2007/03/04 06:03:48 christos Exp $	*/
2
3/*
4 *
5 * Copyright (c) 1997 Charles D. Cranor and Washington University.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *      This product includes software developed by Charles D. Cranor and
19 *      Washington University.
20 * 4. The name of the author may not be used to endorse or promote products
21 *    derived from this software without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 *
34 * from: Id: uvm_io.c,v 1.1.2.2 1997/12/30 12:02:00 mrg Exp
35 */
36
37/*
38 * uvm_io.c: uvm i/o ops
39 */
40
41#include <sys/cdefs.h>
42__KERNEL_RCSID(0, "$NetBSD: uvm_io.c,v 1.24 2007/03/04 06:03:48 christos Exp $");
43
44#include <sys/param.h>
45#include <sys/systm.h>
46#include <sys/mman.h>
47#include <sys/proc.h>
48#include <sys/malloc.h>
49#include <sys/uio.h>
50
51#include <uvm/uvm.h>
52
53/*
54 * functions
55 */
56
57/*
58 * uvm_io: perform I/O on a map
59 *
60 * => caller must have a reference to "map" so that it doesn't go away
61 *    while we are working.
62 */
63
64int
65uvm_io(struct vm_map *map, struct uio *uio)
66{
67	vaddr_t baseva, endva, pageoffset, kva;
68	vsize_t chunksz, togo, sz;
69	struct vm_map_entry *dead_entries;
70	int error;
71
72	/*
73	 * step 0: sanity checks and set up for copy loop.  start with a
74	 * large chunk size.  if we have trouble finding vm space we will
75	 * reduce it.
76	 */
77
78	if (uio->uio_resid == 0)
79		return(0);
80	togo = uio->uio_resid;
81
82	baseva = (vaddr_t) uio->uio_offset;
83	endva = baseva + (togo - 1);
84
85	if (endva < baseva)   /* wrap around? */
86		return(EIO);
87
88	if (baseva >= VM_MAXUSER_ADDRESS)
89		return(0);
90	if (endva >= VM_MAXUSER_ADDRESS)
91		/* EOF truncate */
92		togo = togo - (endva - VM_MAXUSER_ADDRESS + 1);
93	pageoffset = baseva & PAGE_MASK;
94	baseva = trunc_page(baseva);
95	chunksz = MIN(round_page(togo + pageoffset), trunc_page(MAXPHYS));
96	error = 0;
97
98	/*
99	 * step 1: main loop...  while we've got data to move
100	 */
101
102	for (/*null*/; togo > 0 ; pageoffset = 0) {
103
104		/*
105		 * step 2: extract mappings from the map into kernel_map
106		 */
107
108		error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
109			    UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG |
110			    UVM_EXTRACT_FIXPROT);
111		if (error) {
112
113			/* retry with a smaller chunk... */
114			if (error == ENOMEM && chunksz > PAGE_SIZE) {
115				chunksz = trunc_page(chunksz / 2);
116				if (chunksz < PAGE_SIZE)
117					chunksz = PAGE_SIZE;
118				continue;
119			}
120
121			break;
122		}
123
124		/*
125		 * step 3: move a chunk of data
126		 */
127
128		sz = chunksz - pageoffset;
129		if (sz > togo)
130			sz = togo;
131		error = uiomove((void *) (kva + pageoffset), sz, uio);
132		togo -= sz;
133		baseva += chunksz;
134
135		/*
136		 * step 4: unmap the area of kernel memory
137		 */
138
139		vm_map_lock(kernel_map);
140		uvm_unmap_remove(kernel_map, kva, kva + chunksz, &dead_entries,
141		    NULL, 0);
142		vm_map_unlock(kernel_map);
143		if (dead_entries != NULL)
144			uvm_unmap_detach(dead_entries, AMAP_REFALL);
145
146		if (error)
147			break;
148	}
149	return (error);
150}
151