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 * 4. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * @(#)device_pager.c 8.1 (Berkeley) 6/11/93
35 */
36
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
39
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/conf.h>
43 #include <sys/lock.h>
44 #include <sys/proc.h>
45 #include <sys/mutex.h>
46 #include <sys/mman.h>
47 #include <sys/sx.h>
48
49 #include <vm/vm.h>
50 #include <vm/vm_object.h>
51 #include <vm/vm_page.h>
52 #include <vm/vm_pager.h>
53 #include <vm/uma.h>
54
55 static void dev_pager_init(void);
56 static vm_object_t dev_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
57 vm_ooffset_t);
58 static void dev_pager_dealloc(vm_object_t);
59 static int dev_pager_getpages(vm_object_t, vm_page_t *, int, int);
60 static void dev_pager_putpages(vm_object_t, vm_page_t *, int,
61 boolean_t, int *);
62 static boolean_t dev_pager_haspage(vm_object_t, vm_pindex_t, int *,
63 int *);
64
65 /* list of device pager objects */
66 static struct pagerlst dev_pager_object_list;
67 /* protect against object creation */
68 static struct sx dev_pager_sx;
69 /* protect list manipulation */
70 static struct mtx dev_pager_mtx;
71
72
73 static uma_zone_t fakepg_zone;
74
75 static vm_page_t dev_pager_getfake(vm_paddr_t);
76 static void dev_pager_putfake(vm_page_t);
77 static void dev_pager_updatefake(vm_page_t, vm_paddr_t);
78
79 struct pagerops devicepagerops = {
80 .pgo_init = dev_pager_init,
81 .pgo_alloc = dev_pager_alloc,
82 .pgo_dealloc = dev_pager_dealloc,
83 .pgo_getpages = dev_pager_getpages,
84 .pgo_putpages = dev_pager_putpages,
85 .pgo_haspage = dev_pager_haspage,
86 };
87
88 static void
89 dev_pager_init()
90 {
91 TAILQ_INIT(&dev_pager_object_list);
92 sx_init(&dev_pager_sx, "dev_pager create");
93 mtx_init(&dev_pager_mtx, "dev_pager list", NULL, MTX_DEF);
94 fakepg_zone = uma_zcreate("DP fakepg", sizeof(struct vm_page),
95 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR,
96 UMA_ZONE_NOFREE|UMA_ZONE_VM);
97 }
98
99 /*
100 * MPSAFE
101 */
102 static vm_object_t
103 dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff)
104 {
105 struct cdev *dev;
106 vm_object_t object;
107 vm_pindex_t pindex;
108 unsigned int npages;
109 vm_paddr_t paddr;
110 vm_offset_t off;
111 struct cdevsw *csw;
112
113 /*
114 * Offset should be page aligned.
115 */
116 if (foff & PAGE_MASK)
117 return (NULL);
118
119 size = round_page(size);
120 pindex = OFF_TO_IDX(foff + size);
121
122 /*
123 * Make sure this device can be mapped.
124 */
125 dev = handle;
126 csw = dev_refthread(dev);
127 if (csw == NULL)
128 return (NULL);
129 mtx_lock(&Giant);
130
131 /*
132 * Check that the specified range of the device allows the desired
133 * protection.
134 *
135 * XXX assumes VM_PROT_* == PROT_*
136 */
137 npages = OFF_TO_IDX(size);
138 for (off = foff; npages--; off += PAGE_SIZE)
139 if ((*csw->d_mmap)(dev, off, &paddr, (int)prot) != 0) {
140 mtx_unlock(&Giant);
141 dev_relthread(dev);
142 return (NULL);
143 }
144
145 /*
146 * Lock to prevent object creation race condition.
147 */
148 sx_xlock(&dev_pager_sx);
149
150 /*
151 * Look up pager, creating as necessary.
152 */
153 object = vm_pager_object_lookup(&dev_pager_object_list, handle);
154 if (object == NULL) {
155 /*
156 * Allocate object and associate it with the pager.
157 */
158 object = vm_object_allocate(OBJT_DEVICE, pindex);
159 object->handle = handle;
160 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
161 mtx_lock(&dev_pager_mtx);
162 TAILQ_INSERT_TAIL(&dev_pager_object_list, object, pager_object_list);
163 mtx_unlock(&dev_pager_mtx);
164 } else {
165 /*
166 * Gain a reference to the object.
167 */
168 vm_object_reference(object);
169 if (pindex > object->size)
170 object->size = pindex;
171 }
172
173 sx_xunlock(&dev_pager_sx);
174 mtx_unlock(&Giant);
175 dev_relthread(dev);
176 return (object);
177 }
178
179 static void
180 dev_pager_dealloc(object)
181 vm_object_t object;
182 {
183 vm_page_t m;
184
185 mtx_lock(&dev_pager_mtx);
186 TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
187 mtx_unlock(&dev_pager_mtx);
188 /*
189 * Free up our fake pages.
190 */
191 while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
192 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
193 dev_pager_putfake(m);
194 }
195 }
196
197 static int
198 dev_pager_getpages(object, m, count, reqpage)
199 vm_object_t object;
200 vm_page_t *m;
201 int count;
202 int reqpage;
203 {
204 vm_pindex_t offset;
205 vm_paddr_t paddr;
206 vm_page_t page;
207 struct cdev *dev;
208 int i, ret;
209 int prot;
210 struct cdevsw *csw;
211
212 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
213 dev = object->handle;
214 offset = m[reqpage]->pindex;
215 VM_OBJECT_UNLOCK(object);
216 csw = dev_refthread(dev);
217 if (csw == NULL)
218 panic("dev_pager_getpage: no cdevsw");
219 mtx_lock(&Giant);
220 prot = PROT_READ; /* XXX should pass in? */
221
222 ret = (*csw->d_mmap)(dev, (vm_offset_t)offset << PAGE_SHIFT, &paddr, prot);
223 KASSERT(ret == 0, ("dev_pager_getpage: map function returns error"));
224 mtx_unlock(&Giant);
225 dev_relthread(dev);
226
227 if ((m[reqpage]->flags & PG_FICTITIOUS) != 0) {
228 /*
229 * If the passed in reqpage page is a fake page, update it with
230 * the new physical address.
231 */
232 VM_OBJECT_LOCK(object);
233 dev_pager_updatefake(m[reqpage], paddr);
234 if (count > 1) {
235 vm_page_lock_queues();
236 for (i = 0; i < count; i++) {
237 if (i != reqpage)
238 vm_page_free(m[i]);
239 }
240 vm_page_unlock_queues();
241 }
242 } else {
243 /*
244 * Replace the passed in reqpage page with our own fake page and
245 * free up the all of the original pages.
246 */
247 page = dev_pager_getfake(paddr);
248 VM_OBJECT_LOCK(object);
249 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
250 vm_page_lock_queues();
251 for (i = 0; i < count; i++)
252 vm_page_free(m[i]);
253 vm_page_unlock_queues();
254 vm_page_insert(page, object, offset);
255 m[reqpage] = page;
256 }
257
258 return (VM_PAGER_OK);
259 }
260
261 static void
262 dev_pager_putpages(object, m, count, sync, rtvals)
263 vm_object_t object;
264 vm_page_t *m;
265 int count;
266 boolean_t sync;
267 int *rtvals;
268 {
269 panic("dev_pager_putpage called");
270 }
271
272 static boolean_t
273 dev_pager_haspage(object, pindex, before, after)
274 vm_object_t object;
275 vm_pindex_t pindex;
276 int *before;
277 int *after;
278 {
279 if (before != NULL)
280 *before = 0;
281 if (after != NULL)
282 *after = 0;
283 return (TRUE);
284 }
285
286 /*
287 * Instantiate a fictitious page. Unlike physical memory pages, only
288 * the machine-independent fields must be initialized.
289 */
290 static vm_page_t
291 dev_pager_getfake(paddr)
292 vm_paddr_t paddr;
293 {
294 vm_page_t m;
295
296 m = uma_zalloc(fakepg_zone, M_WAITOK);
297
298 m->flags = PG_BUSY | PG_FICTITIOUS;
299 m->valid = VM_PAGE_BITS_ALL;
300 m->dirty = 0;
301 m->busy = 0;
302 m->queue = PQ_NONE;
303 m->object = NULL;
304
305 m->wire_count = 1;
306 m->hold_count = 0;
307 m->phys_addr = paddr;
308
309 return (m);
310 }
311
312 static void
313 dev_pager_putfake(m)
314 vm_page_t m;
315 {
316 if (!(m->flags & PG_FICTITIOUS))
317 panic("dev_pager_putfake: bad page");
318 uma_zfree(fakepg_zone, m);
319 }
320
321 static void
322 dev_pager_updatefake(m, paddr)
323 vm_page_t m;
324 vm_paddr_t paddr;
325 {
326 if (!(m->flags & PG_FICTITIOUS))
327 panic("dev_pager_updatefake: bad page");
328 m->phys_addr = paddr;
329 m->valid = VM_PAGE_BITS_ALL;
330 }
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