1 | /* |
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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 | * |
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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 |
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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 | |
81 | int |
82 | physio( 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 | |
222 | done: |
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 | */ |
240 | u_int |
241 | minphys(struct buf *bp) |
242 | { |
243 | |
244 | buf_setcount(bp, min(MAXPHYS, buf_count(bp))); |
245 | return buf_count(bp); |
246 | } |
247 | |