1/*
2 * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
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14 *
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27 */
28/*-
29 * Copyright (c) 1982, 1986, 1990, 1993
30 * The Regents of the University of California. All rights reserved.
31 * (c) UNIX System Laboratories, Inc.
32 * All or some portions of this file are derived from material licensed
33 * to the University of California by American Telephone and Telegraph
34 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
35 * the permission of UNIX System Laboratories, Inc.
36 *
37 * Redistribution and use in source and binary forms, with or without
38 * modification, are permitted provided that the following conditions
39 * are met:
40 * 1. Redistributions of source code must retain the above copyright
41 * notice, this list of conditions and the following disclaimer.
42 * 2. Redistributions in binary form must reproduce the above copyright
43 * notice, this list of conditions and the following disclaimer in the
44 * documentation and/or other materials provided with the distribution.
45 * 3. All advertising materials mentioning features or use of this software
46 * must display the following acknowledgement:
47 * This product includes software developed by the University of
48 * California, Berkeley and its contributors.
49 * 4. Neither the name of the University nor the names of its contributors
50 * may be used to endorse or promote products derived from this software
51 * without specific prior written permission.
52 *
53 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
54 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
55 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
56 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
57 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
58 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
59 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
60 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
61 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
62 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
63 * SUCH DAMAGE.
64 *
65 * from: @(#)kern_physio.c 8.1 (Berkeley) 6/10/93
66 */
67/*
68 * HISTORY
69 * 27-July-97 Umesh Vaishampayan (umeshv@apple.com)
70 * Allow physio() to kernel space.
71 */
72
73#include <sys/param.h>
74#include <sys/systm.h>
75#include <sys/buf_internal.h>
76#include <sys/conf.h>
77#include <sys/proc_internal.h>
78#include <sys/uio_internal.h>
79#include <kern/assert.h>
80
81int
82physio( void (*f_strategy)(buf_t),
83 buf_t bp,
84 dev_t dev,
85 int flags,
86 u_int (*f_minphys)(buf_t),
87 struct uio *uio,
88 int blocksize)
89{
90 struct proc *p = current_proc();
91 int error, i, buf_allocated, todo, iosize;
92 int orig_bflags = 0;
93 int64_t done;
94
95 error = 0;
96 flags &= B_READ | B_WRITE;
97 buf_allocated = 0;
98
99 /*
100 * [check user read/write access to the data buffer]
101 *
102 * Check each iov one by one. Note that we know if we're reading or
103 * writing, so we ignore the uio's rw parameter. Also note that if
104 * we're doing a read, that's a *write* to user-space.
105 */
106 for (i = 0; i < uio->uio_iovcnt; i++) {
107 if (UIO_SEG_IS_USER_SPACE(uio->uio_segflg)) {
108 user_addr_t base;
109 user_size_t len;
110
111 if (uio_getiov(uio, i, &base, &len) ||
112 !useracc(base,
113 len,
114 (flags == B_READ) ? B_WRITE : B_READ))
115 return (EFAULT);
116 }
117 }
118 /*
119 * Make sure we have a buffer, creating one if necessary.
120 */
121 if (bp == NULL) {
122 bp = buf_alloc((vnode_t)0);
123 buf_allocated = 1;
124 } else
125 orig_bflags = buf_flags(bp);
126 /*
127 * at this point we should have a buffer
128 * that is marked BL_BUSY... we either
129 * acquired it via buf_alloc, or it was
130 * passed into us... if it was passed
131 * in, it needs to already be owned by
132 * the caller (i.e. BL_BUSY is set)
133 */
134 assert(bp->b_lflags & BL_BUSY);
135
136 /*
137 * [set up the fixed part of the buffer for a transfer]
138 */
139 bp->b_dev = dev;
140 bp->b_proc = p;
141
142 /*
143 * [mark the buffer busy for physical I/O]
144 * (i.e. set B_PHYS (because it's an I/O to user
145 * memory, and B_RAW, because B_RAW is to be
146 * "Set by physio for raw transfers.", in addition
147 * to the read/write flag.)
148 */
149 buf_setflags(bp, B_PHYS | B_RAW);
150
151 /*
152 * [while there is data to transfer and no I/O error]
153 * Note that I/O errors are handled with a 'goto' at the bottom
154 * of the 'while' loop.
155 */
156 while (uio_resid(uio) > 0) {
157
158 if ( (iosize = uio_curriovlen(uio)) > MAXPHYSIO_WIRED)
159 iosize = MAXPHYSIO_WIRED;
160 /*
161 * make sure we're set to issue a fresh I/O
162 * in the right direction
163 */
164 buf_reset(bp, flags);
165
166 /* [set up the buffer for a maximum-sized transfer] */
167 buf_setblkno(bp, uio_offset(uio) / blocksize);
168 buf_setcount(bp, iosize);
169 buf_setdataptr(bp, (uintptr_t)CAST_DOWN(caddr_t, uio_curriovbase(uio)));
170
171 /*
172 * [call f_minphys to bound the tranfer size]
173 * and remember the amount of data to transfer,
174 * for later comparison.
175 */
176 (*f_minphys)(bp);
177 todo = buf_count(bp);
178
179 /*
180 * [lock the part of the user address space involved
181 * in the transfer]
182 */
183
184 if(UIO_SEG_IS_USER_SPACE(uio->uio_segflg)) {
185 error = vslock(CAST_USER_ADDR_T(buf_dataptr(bp)),
186 (user_size_t)todo);
187 if (error)
188 goto done;
189 }
190
191 /* [call f_strategy to start the transfer] */
192 (*f_strategy)(bp);
193
194
195 /* [wait for the transfer to complete] */
196 error = (int)buf_biowait(bp);
197
198 /*
199 * [unlock the part of the address space previously
200 * locked]
201 */
202 if(UIO_SEG_IS_USER_SPACE(uio->uio_segflg))
203 vsunlock(CAST_USER_ADDR_T(buf_dataptr(bp)),
204 (user_size_t)todo,
205 (flags & B_READ));
206
207 /*
208 * [deduct the transfer size from the total number
209 * of data to transfer]
210 */
211 done = buf_count(bp) - buf_resid(bp);
212 uio_update(uio, done);
213
214 /*
215 * Now, check for an error.
216 * Also, handle weird end-of-disk semantics.
217 */
218 if (error || done < todo)
219 goto done;
220 }
221
222done:
223 if (buf_allocated)
224 buf_free(bp);
225 else
226 buf_setflags(bp, orig_bflags);
227
228 return (error);
229}
230
231/*
232 * Leffler, et al., says on p. 231:
233 * "The minphys() routine is called by physio() to adjust the
234 * size of each I/O transfer before the latter is passed to
235 * the strategy routine..."
236 *
237 * so, just adjust the buffer's count accounting to MAXPHYS here,
238 * and return the new count;
239 */
240u_int
241minphys(struct buf *bp)
242{
243
244 buf_setcount(bp, min(MAXPHYS, buf_count(bp)));
245 return buf_count(bp);
246}
247