uvm_io.c revision 1.3 
1/*	$NetBSD: uvm_io.c,v 1.3 1998/02/07 11:08:43 mrg Exp $	*/
2
3/*
4 * XXXCDC: "ROUGH DRAFT" QUALITY UVM PRE-RELEASE FILE!
5 *	   >>>USE AT YOUR OWN RISK, WORK IS NOT FINISHED<<<
6 */
7/*
8 *
9 * Copyright (c) 1997 Charles D. Cranor and Washington University.
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 *    notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 *    notice, this list of conditions and the following disclaimer in the
19 *    documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 *    must display the following acknowledgement:
22 *      This product includes software developed by Charles D. Cranor and
23 *      Washington University.
24 * 4. The name of the author may not be used to endorse or promote products
25 *    derived from this software without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 *
38 * from: Id: uvm_io.c,v 1.1.2.2 1997/12/30 12:02:00 mrg Exp
39 */
40
41/*
42 * uvm_io.c: uvm i/o ops
43 */
44
45#include <sys/param.h>
46#include <sys/systm.h>
47#include <sys/mount.h>
48#include <sys/mman.h>
49#include <sys/proc.h>
50#include <sys/malloc.h>
51#include <sys/uio.h>
52
53#include <vm/vm.h>
54#include <vm/vm_page.h>
55#include <vm/vm_kern.h>
56
57#include <sys/syscallargs.h>
58
59#include <uvm/uvm.h>
60
61/*
62 * functions
63 */
64
65/*
66 * uvm_io: perform I/O on a map
67 *
68 * => caller must have a reference to "map" so that it doesn't go away
69 *    while we are working.
70 */
71
72int uvm_io(map, uio)
73
74vm_map_t map;
75struct uio *uio;
76
77{
78  vm_offset_t baseva, endva, pageoffset, kva;
79  vm_size_t chunksz, togo, sz;
80  vm_map_entry_t dead_entries;
81  int error;
82
83  /*
84   * step 0: sanity checks and set up for copy loop.  start with a
85   * large chunk size.  if we have trouble finding vm space we will
86   * reduce it.
87   */
88
89  if (uio->uio_resid == 0)
90    return(0);
91  togo = uio->uio_resid;
92
93  baseva = (vm_offset_t) uio->uio_offset;
94  endva = baseva + (togo - 1);
95
96  if (endva < baseva)   /* wrap around? */
97    return(EIO);
98
99  if (baseva >= VM_MAXUSER_ADDRESS)
100    return(0);
101  if (endva >= VM_MAXUSER_ADDRESS)
102    togo = togo - (endva - VM_MAXUSER_ADDRESS + 1); /* EOF truncate */
103  pageoffset = baseva & PAGE_MASK;
104  baseva = trunc_page(baseva);
105  chunksz = min(round_page(togo + pageoffset), MAXBSIZE);
106  error = 0;
107
108  /*
109   * step 1: main loop...  while we've got data to move
110   */
111
112  for (/*null*/; togo > 0 ; pageoffset = 0) {
113
114    /*
115     * step 2: extract mappings from the map into kernel_map
116     */
117
118    error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
119			    UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG |
120			    UVM_EXTRACT_FIXPROT);
121    if (error) {
122
123      /* retry with a smaller chunk... */
124      if (error == ENOMEM && chunksz > PAGE_SIZE) {
125	chunksz = trunc_page(chunksz / 2);
126	if (chunksz < PAGE_SIZE)
127	  chunksz = PAGE_SIZE;
128	continue;
129      }
130
131      break;
132    }
133
134    /*
135     * step 3: move a chunk of data
136     */
137
138    sz = chunksz - pageoffset;
139    if (sz > togo)
140      sz = togo;
141    error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
142    if (error)
143      break;
144    togo -= sz;
145    baseva += chunksz;
146
147
148    /*
149     * step 4: unmap the area of kernel memory
150     */
151
152    vm_map_lock(kernel_map);
153    (void) uvm_unmap_remove(kernel_map, kva, kva+chunksz, 1, &dead_entries);
154    vm_map_unlock(kernel_map);
155
156    if (dead_entries != NULL)
157      uvm_unmap_detach(dead_entries, AMAP_REFALL);
158
159  }
160
161  /*
162   * done
163   */
164
165  return(error);
166}
167