uvm_io.c revision 1.17 
1/*	$NetBSD: uvm_io.c,v 1.17 2001/11/10 07:37:00 lukem 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 1.17 2001/11/10 07:37:00 lukem 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(map, uio)
66	struct vm_map *map;
67	struct uio *uio;
68{
69	vaddr_t baseva, endva, pageoffset, kva;
70	vsize_t chunksz, togo, sz;
71	struct vm_map_entry *dead_entries;
72	int error;
73
74	/*
75	 * step 0: sanity checks and set up for copy loop.  start with a
76	 * large chunk size.  if we have trouble finding vm space we will
77	 * reduce it.
78	 */
79
80	if (uio->uio_resid == 0)
81		return(0);
82	togo = uio->uio_resid;
83
84	baseva = (vaddr_t) uio->uio_offset;
85	endva = baseva + (togo - 1);
86
87	if (endva < baseva)   /* wrap around? */
88		return(EIO);
89
90	if (baseva >= VM_MAXUSER_ADDRESS)
91		return(0);
92	if (endva >= VM_MAXUSER_ADDRESS)
93		/* EOF truncate */
94		togo = togo - (endva - VM_MAXUSER_ADDRESS + 1);
95	pageoffset = baseva & PAGE_MASK;
96	baseva = trunc_page(baseva);
97	chunksz = MIN(round_page(togo + pageoffset), MAXBSIZE);
98	error = 0;
99
100	/*
101	 * step 1: main loop...  while we've got data to move
102	 */
103
104	for (/*null*/; togo > 0 ; pageoffset = 0) {
105
106		/*
107		 * step 2: extract mappings from the map into kernel_map
108		 */
109
110		error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
111			    UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG |
112			    UVM_EXTRACT_FIXPROT);
113		if (error) {
114
115			/* retry with a smaller chunk... */
116			if (error == ENOMEM && chunksz > PAGE_SIZE) {
117				chunksz = trunc_page(chunksz / 2);
118				if (chunksz < PAGE_SIZE)
119					chunksz = PAGE_SIZE;
120				continue;
121			}
122
123			break;
124		}
125
126		/*
127		 * step 3: move a chunk of data
128		 */
129
130		sz = chunksz - pageoffset;
131		if (sz > togo)
132			sz = togo;
133		error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
134		if (error)
135			break;
136		togo -= sz;
137		baseva += chunksz;
138
139
140		/*
141		 * step 4: unmap the area of kernel memory
142		 */
143
144		vm_map_lock(kernel_map);
145		uvm_unmap_remove(kernel_map, kva, kva + chunksz, &dead_entries);
146		vm_map_unlock(kernel_map);
147		if (dead_entries != NULL)
148			uvm_unmap_detach(dead_entries, AMAP_REFALL);
149	}
150	return (error);
151}
152