FreeBSD/Linux Kernel Cross Reference
sys/vm/device_pager.c
1 /*
2 * Copyright (c) 1990 University of Utah.
3 * Copyright (c) 1991, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * the Systems Programming Group of the University of Utah Computer
8 * Science Department.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * @(#)device_pager.c 8.1 (Berkeley) 6/11/93
39 * $FreeBSD: src/sys/vm/device_pager.c,v 1.23.2.1 1999/09/05 08:24:15 peter Exp $
40 */
41
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/conf.h>
45 #include <sys/mman.h>
46 #include <sys/malloc.h>
47 #include <sys/proc.h>
48 #include <sys/queue.h>
49
50 #include <vm/vm.h>
51 #include <vm/vm_param.h>
52 #include <vm/vm_prot.h>
53 #include <vm/vm_kern.h>
54 #include <vm/vm_object.h>
55 #include <vm/vm_page.h>
56 #include <vm/vm_pager.h>
57 #include <vm/device_pager.h>
58
59 static void dev_pager_init __P((void));
60 static vm_object_t dev_pager_alloc __P((void *, vm_size_t, vm_prot_t,
61 vm_ooffset_t));
62 static void dev_pager_dealloc __P((vm_object_t));
63 static int dev_pager_getpages __P((vm_object_t, vm_page_t *, int, int));
64 static int dev_pager_putpages __P((vm_object_t, vm_page_t *, int,
65 boolean_t, int *));
66 static boolean_t dev_pager_haspage __P((vm_object_t, vm_pindex_t, int *,
67 int *));
68
69 /* list of device pager objects */
70 static struct pagerlst dev_pager_object_list;
71
72 /* list of available vm_page_t's */
73 static TAILQ_HEAD(, vm_page) dev_pager_fakelist;
74
75 static vm_page_t dev_pager_getfake __P((vm_offset_t));
76 static void dev_pager_putfake __P((vm_page_t));
77
78 static int dev_pager_alloc_lock, dev_pager_alloc_lock_want;
79
80 struct pagerops devicepagerops = {
81 dev_pager_init,
82 dev_pager_alloc,
83 dev_pager_dealloc,
84 dev_pager_getpages,
85 dev_pager_putpages,
86 dev_pager_haspage,
87 NULL
88 };
89
90 static void
91 dev_pager_init()
92 {
93 TAILQ_INIT(&dev_pager_object_list);
94 TAILQ_INIT(&dev_pager_fakelist);
95 }
96
97 static vm_object_t
98 dev_pager_alloc(handle, size, prot, foff)
99 void *handle;
100 vm_size_t size;
101 vm_prot_t prot;
102 vm_ooffset_t foff;
103 {
104 dev_t dev;
105 d_mmap_t *mapfunc;
106 vm_object_t object;
107 unsigned int npages, off;
108
109 /*
110 * Make sure this device can be mapped.
111 */
112 dev = (dev_t) (u_long) handle;
113 mapfunc = cdevsw[major(dev)]->d_mmap;
114 if (mapfunc == NULL || mapfunc == (d_mmap_t *)nullop) {
115 printf("obsolete map function %p\n", (void *)mapfunc);
116 return (NULL);
117 }
118
119 /*
120 * Offset should be page aligned.
121 */
122 if (foff & PAGE_MASK)
123 return (NULL);
124
125 /*
126 * Check that the specified range of the device allows the desired
127 * protection.
128 *
129 * XXX assumes VM_PROT_* == PROT_*
130 */
131 npages = size;
132 for (off = foff; npages--; off += PAGE_SIZE)
133 if ((*mapfunc) (dev, off, (int) prot) == -1)
134 return (NULL);
135
136 /*
137 * Lock to prevent object creation race contion.
138 */
139 while (dev_pager_alloc_lock) {
140 dev_pager_alloc_lock_want++;
141 tsleep(&dev_pager_alloc_lock, PVM, "dvpall", 0);
142 dev_pager_alloc_lock_want--;
143 }
144 dev_pager_alloc_lock = 1;
145
146 /*
147 * Look up pager, creating as necessary.
148 */
149 object = vm_pager_object_lookup(&dev_pager_object_list, handle);
150 if (object == NULL) {
151 /*
152 * Allocate object and associate it with the pager.
153 */
154 object = vm_object_allocate(OBJT_DEVICE,
155 OFF_TO_IDX(foff) + size);
156 object->handle = handle;
157 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
158 TAILQ_INSERT_TAIL(&dev_pager_object_list, object, pager_object_list);
159 } else {
160 /*
161 * Gain a reference to the object.
162 */
163 vm_object_reference(object);
164 if (OFF_TO_IDX(foff) + size > object->size)
165 object->size = OFF_TO_IDX(foff) + size;
166 }
167
168 dev_pager_alloc_lock = 0;
169 if (dev_pager_alloc_lock_want)
170 wakeup(&dev_pager_alloc_lock);
171
172 return (object);
173 }
174
175 static void
176 dev_pager_dealloc(object)
177 vm_object_t object;
178 {
179 vm_page_t m;
180
181 TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
182 /*
183 * Free up our fake pages.
184 */
185 while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
186 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
187 dev_pager_putfake(m);
188 }
189 }
190
191 static int
192 dev_pager_getpages(object, m, count, reqpage)
193 vm_object_t object;
194 vm_page_t *m;
195 int count;
196 int reqpage;
197 {
198 vm_offset_t offset;
199 vm_offset_t paddr;
200 vm_page_t page;
201 dev_t dev;
202 int i, s;
203 d_mmap_t *mapfunc;
204 int prot;
205
206 dev = (dev_t) (u_long) object->handle;
207 offset = m[reqpage]->pindex + OFF_TO_IDX(object->paging_offset);
208 prot = PROT_READ; /* XXX should pass in? */
209 mapfunc = cdevsw[major(dev)]->d_mmap;
210
211 if (mapfunc == NULL || mapfunc == (d_mmap_t *)nullop)
212 panic("dev_pager_getpage: no map function");
213
214 paddr = pmap_phys_address((*mapfunc) ((dev_t) dev, (int) offset << PAGE_SHIFT, prot));
215 #ifdef DIAGNOSTIC
216 if (paddr == -1)
217 panic("dev_pager_getpage: map function returns error");
218 #endif
219 /*
220 * Replace the passed in reqpage page with our own fake page and free up the
221 * all of the original pages.
222 */
223 page = dev_pager_getfake(paddr);
224 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
225 for (i = 0; i < count; i++) {
226 PAGE_WAKEUP(m[i]);
227 vm_page_free(m[i]);
228 }
229 s = splhigh();
230 vm_page_insert(page, object, offset);
231 splx(s);
232
233 return (VM_PAGER_OK);
234 }
235
236 static int
237 dev_pager_putpages(object, m, count, sync, rtvals)
238 vm_object_t object;
239 vm_page_t *m;
240 int count;
241 boolean_t sync;
242 int *rtvals;
243 {
244 panic("dev_pager_putpage called");
245 }
246
247 static boolean_t
248 dev_pager_haspage(object, pindex, before, after)
249 vm_object_t object;
250 vm_pindex_t pindex;
251 int *before;
252 int *after;
253 {
254 if (before != NULL)
255 *before = 0;
256 if (after != NULL)
257 *after = 0;
258 return (TRUE);
259 }
260
261 static vm_page_t
262 dev_pager_getfake(paddr)
263 vm_offset_t paddr;
264 {
265 vm_page_t m;
266 int i;
267
268 if (TAILQ_FIRST(&dev_pager_fakelist) == NULL) {
269 m = (vm_page_t) malloc(PAGE_SIZE * 2, M_VMPGDATA, M_WAITOK);
270 for (i = (PAGE_SIZE * 2) / sizeof(*m); i > 0; i--) {
271 TAILQ_INSERT_TAIL(&dev_pager_fakelist, m, pageq);
272 m++;
273 }
274 }
275 m = TAILQ_FIRST(&dev_pager_fakelist);
276 TAILQ_REMOVE(&dev_pager_fakelist, m, pageq);
277
278 m->flags = PG_BUSY | PG_FICTITIOUS;
279 m->valid = VM_PAGE_BITS_ALL;
280 m->dirty = 0;
281 m->busy = 0;
282 m->queue = PQ_NONE;
283
284 m->wire_count = 1;
285 m->hold_count = 0;
286 m->phys_addr = paddr;
287
288 return (m);
289 }
290
291 static void
292 dev_pager_putfake(m)
293 vm_page_t m;
294 {
295 if (!(m->flags & PG_FICTITIOUS))
296 panic("dev_pager_putfake: bad page");
297 TAILQ_INSERT_TAIL(&dev_pager_fakelist, m, pageq);
298 }
Cache object: bfa591d0d1fbcff3b07c21fdc9f917e7
|