1 /* $NetBSD: uvm_io.c,v 1.29 2020/09/21 18:41:59 chs Exp $ */
2
3 /*
4 * Copyright (c) 1997 Charles D. Cranor and Washington University.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 *
27 * from: Id: uvm_io.c,v 1.1.2.2 1997/12/30 12:02:00 mrg Exp
28 */
29
30 /*
31 * uvm_io.c: uvm i/o ops
32 */
33
34 #include <sys/cdefs.h>
35 __KERNEL_RCSID(0, "$NetBSD: uvm_io.c,v 1.29 2020/09/21 18:41:59 chs Exp $");
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/mman.h>
40 #include <sys/uio.h>
41
42 #include <uvm/uvm.h>
43
44 /*
45 * functions
46 */
47
48 /*
49 * uvm_io: perform I/O on a map
50 *
51 * => caller must have a reference to "map" so that it doesn't go away
52 * while we are working.
53 */
54
55 int
uvm_io(struct vm_map * map,struct uio * uio,int flags)56 uvm_io(struct vm_map *map, struct uio *uio, int flags)
57 {
58 vaddr_t baseva, endva, pageoffset, kva;
59 vsize_t chunksz, togo, sz;
60 struct vm_map_entry *dead_entries;
61 int error;
62
63 /*
64 * step 0: sanity checks and set up for copy loop. start with a
65 * large chunk size. if we have trouble finding vm space we will
66 * reduce it.
67 */
68
69 if (uio->uio_resid == 0)
70 return(0);
71 togo = uio->uio_resid;
72
73 baseva = (vaddr_t) uio->uio_offset;
74 endva = baseva + (togo - 1);
75
76 if (endva < baseva) /* wrap around? */
77 return(EIO);
78
79 if (baseva >= VM_MAXUSER_ADDRESS)
80 return(0);
81 if (endva >= VM_MAXUSER_ADDRESS)
82 /* EOF truncate */
83 togo = togo - (endva - VM_MAXUSER_ADDRESS + 1);
84 pageoffset = baseva & PAGE_MASK;
85 baseva = trunc_page(baseva);
86 chunksz = MIN(round_page(togo + pageoffset), trunc_page(MAXPHYS));
87 error = 0;
88
89 flags |= UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG | UVM_EXTRACT_FIXPROT;
90
91 /* XXX cannot use QREF with without AMAP_REFALL, and REFALL is unsafe */
92 flags &= ~UVM_EXTRACT_QREF;
93
94 /*
95 * step 1: main loop... while we've got data to move
96 */
97
98 for (/*null*/; togo > 0 ; pageoffset = 0) {
99
100 /*
101 * step 2: extract mappings from the map into kernel_map
102 */
103
104 error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
105 flags);
106 if (error) {
107
108 /* retry with a smaller chunk... */
109 if (error == ENOMEM && chunksz > PAGE_SIZE) {
110 chunksz = trunc_page(chunksz / 2);
111 if (chunksz < PAGE_SIZE)
112 chunksz = PAGE_SIZE;
113 continue;
114 }
115
116 break;
117 }
118
119 /*
120 * step 3: move a chunk of data
121 */
122
123 sz = chunksz - pageoffset;
124 if (sz > togo)
125 sz = togo;
126 error = uiomove((void *) (kva + pageoffset), sz, uio);
127 togo -= sz;
128 baseva += chunksz;
129
130 /*
131 * step 4: unmap the area of kernel memory
132 */
133
134 vm_map_lock(kernel_map);
135 uvm_unmap_remove(kernel_map, kva, kva + chunksz, &dead_entries,
136 0);
137 vm_map_unlock(kernel_map);
138 if (dead_entries != NULL)
139 uvm_unmap_detach(dead_entries, AMAP_REFALL);
140
141 if (error)
142 break;
143 }
144 return (error);
145 }
146