1 /* $OpenBSD: uvm_io.c,v 1.16 2005/11/04 21:48:07 miod Exp $ */
2 /* $NetBSD: uvm_io.c,v 1.12 2000/06/27 17:29:23 mrg Exp $ */
3
4 /*
5 *
6 * Copyright (c) 1997 Charles D. Cranor and Washington University.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed by Charles D. Cranor and
20 * Washington University.
21 * 4. The name of the author may not be used to endorse or promote products
22 * derived from this software without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 *
35 * from: Id: uvm_io.c,v 1.1.2.2 1997/12/30 12:02:00 mrg Exp
36 */
37
38 /*
39 * uvm_io.c: uvm i/o ops
40 */
41
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/mman.h>
45 #include <sys/proc.h>
46 #include <sys/malloc.h>
47 #include <sys/uio.h>
48
49 #include <uvm/uvm.h>
50
51 /*
52 * functions
53 */
54
55 /*
56 * uvm_io: perform I/O on a map
57 *
58 * => caller must have a reference to "map" so that it doesn't go away
59 * while we are working.
60 */
61
62 int
63 uvm_io(vm_map_t map, struct uio *uio, int flags)
64 {
65 vaddr_t baseva, endva, pageoffset, kva;
66 vsize_t chunksz, togo, sz;
67 vm_map_entry_t dead_entries;
68 int error, extractflags;
69
70 /*
71 * step 0: sanity checks and set up for copy loop. start with a
72 * large chunk size. if we have trouble finding vm space we will
73 * reduce it.
74 */
75
76 if (uio->uio_resid == 0)
77 return(0);
78 togo = uio->uio_resid;
79
80 baseva = (vaddr_t) uio->uio_offset;
81 endva = baseva + (togo - 1);
82
83 if (endva < baseva) /* wrap around? */
84 return(EIO);
85
86 if (baseva >= VM_MAXUSER_ADDRESS)
87 return(0);
88 if (endva >= VM_MAXUSER_ADDRESS)
89 /* EOF truncate */
90 togo = togo - (endva - VM_MAXUSER_ADDRESS + 1);
91 pageoffset = baseva & PAGE_MASK;
92 baseva = trunc_page(baseva);
93 chunksz = min(round_page(togo + pageoffset), MAXBSIZE);
94 error = 0;
95
96 extractflags = UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG;
97 if (flags & UVM_IO_FIXPROT)
98 extractflags |= UVM_EXTRACT_FIXPROT;
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 extractflags);
112 if (error) {
113
114 /* retry with a smaller chunk... */
115 if (error == ENOMEM && chunksz > PAGE_SIZE) {
116 chunksz = trunc_page(chunksz / 2);
117 if (chunksz < PAGE_SIZE)
118 chunksz = PAGE_SIZE;
119 continue;
120 }
121
122 break;
123 }
124
125 /*
126 * step 3: move a chunk of data
127 */
128
129 sz = chunksz - pageoffset;
130 if (sz > togo)
131 sz = togo;
132 error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
133 togo -= sz;
134 baseva += chunksz;
135
136
137 /*
138 * step 4: unmap the area of kernel memory
139 */
140
141 vm_map_lock(kernel_map);
142 uvm_unmap_remove(kernel_map, kva, kva+chunksz,
143 &dead_entries, NULL);
144 vm_map_unlock(kernel_map);
145
146 if (dead_entries != NULL)
147 uvm_unmap_detach(dead_entries, AMAP_REFALL);
148
149 /*
150 * We defer checking the error return from uiomove until
151 * here so that we won't leak memory.
152 */
153 if (error)
154 break;
155 }
156
157 /*
158 * done
159 */
160
161 return (error);
162 }