uvm_io.c revision 1.13 
1/*	$NetBSD: uvm_io.c,v 1.13 2001/03/15 06:10:57 chs 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/param.h>
42#include <sys/systm.h>
43#include <sys/mman.h>
44#include <sys/proc.h>
45#include <sys/malloc.h>
46#include <sys/uio.h>
47
48#include <uvm/uvm.h>
49
50/*
51 * functions
52 */
53
54/*
55 * uvm_io: perform I/O on a map
56 *
57 * => caller must have a reference to "map" so that it doesn't go away
58 *    while we are working.
59 */
60
61int
62uvm_io(map, uio)
63	vm_map_t map;
64	struct uio *uio;
65{
66	vaddr_t baseva, endva, pageoffset, kva;
67	vsize_t chunksz, togo, sz;
68	vm_map_entry_t dead_entries;
69	int error;
70
71	/*
72	 * step 0: sanity checks and set up for copy loop.  start with a
73	 * large chunk size.  if we have trouble finding vm space we will
74	 * reduce it.
75	 */
76
77	if (uio->uio_resid == 0)
78		return(0);
79	togo = uio->uio_resid;
80
81	baseva = (vaddr_t) uio->uio_offset;
82	endva = baseva + (togo - 1);
83
84	if (endva < baseva)   /* wrap around? */
85		return(EIO);
86
87	if (baseva >= VM_MAXUSER_ADDRESS)
88		return(0);
89	if (endva >= VM_MAXUSER_ADDRESS)
90		/* EOF truncate */
91		togo = togo - (endva - VM_MAXUSER_ADDRESS + 1);
92	pageoffset = baseva & PAGE_MASK;
93	baseva = trunc_page(baseva);
94	chunksz = min(round_page(togo + pageoffset), MAXBSIZE);
95	error = 0;
96
97	/*
98	 * step 1: main loop...  while we've got data to move
99	 */
100
101	for (/*null*/; togo > 0 ; pageoffset = 0) {
102
103		/*
104		 * step 2: extract mappings from the map into kernel_map
105		 */
106
107		error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
108			    UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG |
109			    UVM_EXTRACT_FIXPROT);
110		if (error) {
111
112			/* retry with a smaller chunk... */
113			if (error == ENOMEM && chunksz > PAGE_SIZE) {
114				chunksz = trunc_page(chunksz / 2);
115				if (chunksz < PAGE_SIZE)
116					chunksz = PAGE_SIZE;
117				continue;
118			}
119
120			break;
121		}
122
123		/*
124		 * step 3: move a chunk of data
125		 */
126
127		sz = chunksz - pageoffset;
128		if (sz > togo)
129			sz = togo;
130		error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
131		if (error)
132			break;
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, &dead_entries);
143		vm_map_unlock(kernel_map);
144		if (dead_entries != NULL)
145			uvm_unmap_detach(dead_entries, AMAP_REFALL);
146	}
147	return (error);
148}
149