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
53int
54uvm_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}
140