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 | * |
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 |
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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; |
92 | size_t iosize; |
93 | int orig_bflags = 0; |
94 | int64_t done; |
95 | |
96 | error = 0; |
97 | flags &= B_READ | B_WRITE; |
98 | buf_allocated = 0; |
99 | |
100 | /* |
101 | * [check user read/write access to the data buffer] |
102 | * |
103 | * Check each iov one by one. Note that we know if we're reading or |
104 | * writing, so we ignore the uio's rw parameter. Also note that if |
105 | * we're doing a read, that's a *write* to user-space. |
106 | */ |
107 | for (i = 0; i < uio->uio_iovcnt; i++) { |
108 | if (UIO_SEG_IS_USER_SPACE(uio->uio_segflg)) { |
109 | user_addr_t base; |
110 | user_size_t len; |
111 | |
112 | if (uio_getiov(a_uio: uio, a_index: i, a_baseaddr_p: &base, a_length_p: &len) || |
113 | !useracc(addr: base, |
114 | len, |
115 | prot: (flags == B_READ) ? B_WRITE : B_READ)) { |
116 | return EFAULT; |
117 | } |
118 | } |
119 | } |
120 | /* |
121 | * Make sure we have a buffer, creating one if necessary. |
122 | */ |
123 | if (bp == NULL) { |
124 | bp = buf_alloc(vp: (vnode_t)0); |
125 | buf_allocated = 1; |
126 | } else { |
127 | orig_bflags = buf_flags(bp); |
128 | } |
129 | /* |
130 | * at this point we should have a buffer |
131 | * that is marked BL_BUSY... we either |
132 | * acquired it via buf_alloc, or it was |
133 | * passed into us... if it was passed |
134 | * in, it needs to already be owned by |
135 | * the caller (i.e. BL_BUSY is set) |
136 | */ |
137 | assert(bp->b_lflags & BL_BUSY); |
138 | |
139 | /* |
140 | * [set up the fixed part of the buffer for a transfer] |
141 | */ |
142 | bp->b_dev = dev; |
143 | bp->b_proc = p; |
144 | |
145 | /* |
146 | * [mark the buffer busy for physical I/O] |
147 | * (i.e. set B_PHYS (because it's an I/O to user |
148 | * memory, and B_RAW, because B_RAW is to be |
149 | * "Set by physio for raw transfers.", in addition |
150 | * to the read/write flag.) |
151 | */ |
152 | buf_setflags(bp, B_PHYS | B_RAW); |
153 | |
154 | /* |
155 | * [while there is data to transfer and no I/O error] |
156 | * Note that I/O errors are handled with a 'goto' at the bottom |
157 | * of the 'while' loop. |
158 | */ |
159 | while (uio_resid(a_uio: uio) > 0) { |
160 | iosize = uio_curriovlen(a_uio: uio); |
161 | if (iosize > MAXPHYSIO_WIRED) { |
162 | iosize = MAXPHYSIO_WIRED; |
163 | } |
164 | |
165 | /* |
166 | * make sure we're set to issue a fresh I/O |
167 | * in the right direction |
168 | */ |
169 | buf_reset(bp, flags); |
170 | |
171 | /* [set up the buffer for a maximum-sized transfer] */ |
172 | buf_setblkno(bp, blkno: uio_offset(a_uio: uio) / blocksize); |
173 | assert(iosize <= UINT32_MAX); |
174 | buf_setcount(bp, bcount: (uint32_t)iosize); |
175 | buf_setdataptr(bp, data: (uintptr_t)CAST_DOWN(caddr_t, uio_curriovbase(uio))); |
176 | |
177 | /* |
178 | * [call f_minphys to bound the tranfer size] |
179 | * and remember the amount of data to transfer, |
180 | * for later comparison. |
181 | */ |
182 | (*f_minphys)(bp); |
183 | todo = buf_count(bp); |
184 | |
185 | /* |
186 | * [lock the part of the user address space involved |
187 | * in the transfer] |
188 | */ |
189 | |
190 | if (UIO_SEG_IS_USER_SPACE(uio->uio_segflg)) { |
191 | error = vslock(CAST_USER_ADDR_T(buf_dataptr(bp)), |
192 | len: (user_size_t)todo); |
193 | if (error) { |
194 | goto finished; |
195 | } |
196 | } |
197 | |
198 | /* [call f_strategy to start the transfer] */ |
199 | (*f_strategy)(bp); |
200 | |
201 | |
202 | /* [wait for the transfer to complete] */ |
203 | error = (int)buf_biowait(bp); |
204 | |
205 | /* |
206 | * [unlock the part of the address space previously |
207 | * locked] |
208 | */ |
209 | if (UIO_SEG_IS_USER_SPACE(uio->uio_segflg)) { |
210 | vsunlock(CAST_USER_ADDR_T(buf_dataptr(bp)), |
211 | len: (user_size_t)todo, |
212 | dirtied: (flags & B_READ)); |
213 | } |
214 | |
215 | /* |
216 | * [deduct the transfer size from the total number |
217 | * of data to transfer] |
218 | */ |
219 | done = buf_count(bp) - buf_resid(bp); |
220 | assert(0 <= done && done <= UINT32_MAX); |
221 | uio_update(a_uio: uio, a_count: (user_size_t)done); |
222 | |
223 | /* |
224 | * Now, check for an error. |
225 | * Also, handle weird end-of-disk semantics. |
226 | */ |
227 | if (error || done < todo) { |
228 | goto finished; |
229 | } |
230 | } |
231 | |
232 | finished: |
233 | if (buf_allocated) { |
234 | buf_free(bp); |
235 | } else { |
236 | buf_setflags(bp, flags: orig_bflags); |
237 | } |
238 | |
239 | return error; |
240 | } |
241 | |
242 | /* |
243 | * Leffler, et al., says on p. 231: |
244 | * "The minphys() routine is called by physio() to adjust the |
245 | * size of each I/O transfer before the latter is passed to |
246 | * the strategy routine..." |
247 | * |
248 | * so, just adjust the buffer's count accounting to MAXPHYS here, |
249 | * and return the new count; |
250 | */ |
251 | u_int |
252 | minphys(struct buf *bp) |
253 | { |
254 | buf_setcount(bp, bcount: min(MAXPHYS, b: buf_count(bp))); |
255 | return buf_count(bp); |
256 | } |
257 | |