FreeBSD/Linux Kernel Cross Reference
sys/uvm/uvm_io.c
1 /* $OpenBSD: uvm_io.c,v 1.30 2022/10/07 14:59:39 deraadt Exp $ */
2 /* $NetBSD: uvm_io.c,v 1.12 2000/06/27 17:29:23 mrg Exp $ */
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 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * from: Id: uvm_io.c,v 1.1.2.2 1997/12/30 12:02:00 mrg Exp
29 */
30
31 /*
32 * uvm_io.c: uvm i/o ops
33 */
34
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/mman.h>
38 #include <sys/uio.h>
39
40 #include <uvm/uvm.h>
41
42 /*
43 * functions
44 */
45
46 /*
47 * uvm_io: perform I/O on a map
48 *
49 * => caller must have a reference to "map" so that it doesn't go away
50 * while we are working.
51 */
52
53 int
54 uvm_io(vm_map_t map, struct uio *uio, int flags)
55 {
56 vaddr_t baseva, endva, pageoffset, kva;
57 vsize_t chunksz, togo, sz;
58 struct uvm_map_deadq dead_entries;
59 int error, extractflags;
60
61 /*
62 * step 0: sanity checks and set up for copy loop. start with a
63 * large chunk size. if we have trouble finding vm space we will
64 * reduce it.
65 */
66 if (uio->uio_resid == 0)
67 return(0);
68 togo = uio->uio_resid;
69
70 baseva = (vaddr_t) uio->uio_offset;
71 endva = baseva + (togo - 1);
72
73 if (endva < baseva) /* wrap around? */
74 return(EIO);
75
76 if (baseva >= VM_MAXUSER_ADDRESS)
77 return(0);
78 if (endva >= VM_MAXUSER_ADDRESS)
79 /* EOF truncate */
80 togo = togo - (endva - VM_MAXUSER_ADDRESS + 1);
81 pageoffset = baseva & PAGE_MASK;
82 baseva = trunc_page(baseva);
83 chunksz = min(round_page(togo + pageoffset), MAXBSIZE);
84 error = 0;
85
86 extractflags = 0;
87 if (flags & UVM_IO_FIXPROT)
88 extractflags |= UVM_EXTRACT_FIXPROT;
89
90 /*
91 * step 1: main loop... while we've got data to move
92 */
93 for (/*null*/; togo > 0 ; pageoffset = 0) {
94
95 /*
96 * step 2: extract mappings from the map into kernel_map
97 */
98 error = uvm_map_extract(map, baseva, chunksz, &kva,
99 extractflags);
100 if (error) {
101
102 /* retry with a smaller chunk... */
103 if (error == ENOMEM && chunksz > PAGE_SIZE) {
104 chunksz = trunc_page(chunksz / 2);
105 if (chunksz < PAGE_SIZE)
106 chunksz = PAGE_SIZE;
107 continue;
108 }
109
110 break;
111 }
112
113 /*
114 * step 3: move a chunk of data
115 */
116 sz = chunksz - pageoffset;
117 if (sz > togo)
118 sz = togo;
119 error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
120 togo -= sz;
121 baseva += chunksz;
122
123
124 /*
125 * step 4: unmap the area of kernel memory
126 */
127 vm_map_lock(kernel_map);
128 TAILQ_INIT(&dead_entries);
129 uvm_unmap_remove(kernel_map, kva, kva+chunksz,
130 &dead_entries, FALSE, TRUE, FALSE);
131 vm_map_unlock(kernel_map);
132 uvm_unmap_detach(&dead_entries, AMAP_REFALL);
133
134 if (error)
135 break;
136 }
137
138 return (error);
139 }
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