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: releng/7.3/sys/vm/device_pager.c 198595 2009-10-29 15:10:38Z jhb $");
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 list manipulation */
68 static struct mtx dev_pager_mtx;
69
70
71 static uma_zone_t fakepg_zone;
72
73 static vm_page_t dev_pager_getfake(vm_paddr_t, vm_memattr_t);
74 static void dev_pager_putfake(vm_page_t);
75 static void dev_pager_updatefake(vm_page_t, vm_paddr_t, vm_memattr_t);
76
77 struct pagerops devicepagerops = {
78 .pgo_init = dev_pager_init,
79 .pgo_alloc = dev_pager_alloc,
80 .pgo_dealloc = dev_pager_dealloc,
81 .pgo_getpages = dev_pager_getpages,
82 .pgo_putpages = dev_pager_putpages,
83 .pgo_haspage = dev_pager_haspage,
84 };
85
86 static void
87 dev_pager_init()
88 {
89 TAILQ_INIT(&dev_pager_object_list);
90 mtx_init(&dev_pager_mtx, "dev_pager list", NULL, MTX_DEF);
91 fakepg_zone = uma_zcreate("DP fakepg", sizeof(struct vm_page),
92 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR,
93 UMA_ZONE_NOFREE|UMA_ZONE_VM);
94 }
95
96 static __inline int
97 dev_mmap(struct cdevsw *csw, struct cdev *dev, vm_offset_t offset,
98 vm_paddr_t *paddr, int nprot, vm_memattr_t *memattr)
99 {
100
101 if (csw->d_flags & D_MMAP2)
102 return (csw->d_mmap2(dev, offset, paddr, nprot, memattr));
103 else
104 return (csw->d_mmap(dev, offset, paddr, nprot));
105 }
106
107 /*
108 * MPSAFE
109 */
110 static vm_object_t
111 dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff)
112 {
113 struct cdev *dev;
114 vm_object_t object, object1;
115 vm_pindex_t pindex;
116 unsigned int npages;
117 vm_paddr_t paddr;
118 vm_offset_t off;
119 vm_memattr_t dummy;
120 struct cdevsw *csw;
121
122 /*
123 * Offset should be page aligned.
124 */
125 if (foff & PAGE_MASK)
126 return (NULL);
127
128 size = round_page(size);
129 pindex = OFF_TO_IDX(foff + size);
130
131 /*
132 * Make sure this device can be mapped.
133 */
134 dev = handle;
135 csw = dev_refthread(dev);
136 if (csw == NULL)
137 return (NULL);
138
139 /*
140 * Check that the specified range of the device allows the desired
141 * protection.
142 *
143 * XXX assumes VM_PROT_* == PROT_*
144 */
145 npages = OFF_TO_IDX(size);
146 for (off = foff; npages--; off += PAGE_SIZE)
147 if (dev_mmap(csw, dev, off, &paddr, (int)prot, &dummy) != 0) {
148 dev_relthread(dev);
149 return (NULL);
150 }
151
152 mtx_lock(&dev_pager_mtx);
153
154 /*
155 * Look up pager, creating as necessary.
156 */
157 object1 = NULL;
158 object = vm_pager_object_lookup(&dev_pager_object_list, handle);
159 if (object == NULL) {
160 /*
161 * Allocate object and associate it with the pager. Initialize
162 * the object's pg_color based upon the physical address of the
163 * device's memory.
164 */
165 mtx_unlock(&dev_pager_mtx);
166 object1 = vm_object_allocate(OBJT_DEVICE, pindex);
167 object1->flags |= OBJ_COLORED;
168 object1->pg_color = atop(paddr) - OFF_TO_IDX(off - PAGE_SIZE);
169 mtx_lock(&dev_pager_mtx);
170 object = vm_pager_object_lookup(&dev_pager_object_list, handle);
171 if (object != NULL) {
172 /*
173 * We raced with other thread while allocating object.
174 */
175 if (pindex > object->size)
176 object->size = pindex;
177 } else {
178 object = object1;
179 object1 = NULL;
180 object->handle = handle;
181 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
182 TAILQ_INSERT_TAIL(&dev_pager_object_list, object,
183 pager_object_list);
184 }
185 } else {
186 if (pindex > object->size)
187 object->size = pindex;
188 }
189 mtx_unlock(&dev_pager_mtx);
190 dev_relthread(dev);
191 vm_object_deallocate(object1);
192 return (object);
193 }
194
195 static void
196 dev_pager_dealloc(object)
197 vm_object_t object;
198 {
199 vm_page_t m;
200
201 VM_OBJECT_UNLOCK(object);
202 mtx_lock(&dev_pager_mtx);
203 TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
204 mtx_unlock(&dev_pager_mtx);
205 VM_OBJECT_LOCK(object);
206 /*
207 * Free up our fake pages.
208 */
209 while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != NULL) {
210 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
211 dev_pager_putfake(m);
212 }
213 }
214
215 static int
216 dev_pager_getpages(object, m, count, reqpage)
217 vm_object_t object;
218 vm_page_t *m;
219 int count;
220 int reqpage;
221 {
222 vm_pindex_t offset;
223 vm_paddr_t paddr;
224 vm_page_t m_paddr, page;
225 vm_memattr_t memattr;
226 struct cdev *dev;
227 int i, ret;
228 struct cdevsw *csw;
229 struct thread *td;
230 struct file *fpop;
231
232 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
233 dev = object->handle;
234 page = m[reqpage];
235 offset = page->pindex;
236 memattr = object->memattr;
237 VM_OBJECT_UNLOCK(object);
238 csw = dev_refthread(dev);
239 if (csw == NULL)
240 panic("dev_pager_getpage: no cdevsw");
241 td = curthread;
242 fpop = td->td_fpop;
243 td->td_fpop = NULL;
244 ret = dev_mmap(csw, dev, (vm_offset_t)offset << PAGE_SHIFT, &paddr,
245 PROT_READ, &memattr);
246 KASSERT(ret == 0, ("dev_pager_getpage: map function returns error"));
247 td->td_fpop = fpop;
248 dev_relthread(dev);
249 /* If "paddr" is a real page, perform a sanity check on "memattr". */
250 if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL &&
251 pmap_page_get_memattr(m_paddr) != memattr) {
252 memattr = pmap_page_get_memattr(m_paddr);
253 printf(
254 "WARNING: A device driver has set \"memattr\" inconsistently.\n");
255 }
256 if ((page->flags & PG_FICTITIOUS) != 0) {
257 /*
258 * If the passed in reqpage page is a fake page, update it with
259 * the new physical address.
260 */
261 VM_OBJECT_LOCK(object);
262 dev_pager_updatefake(page, paddr, memattr);
263 if (count > 1) {
264 vm_page_lock_queues();
265 for (i = 0; i < count; i++) {
266 if (i != reqpage)
267 vm_page_free(m[i]);
268 }
269 vm_page_unlock_queues();
270 }
271 } else {
272 /*
273 * Replace the passed in reqpage page with our own fake page and
274 * free up the all of the original pages.
275 */
276 page = dev_pager_getfake(paddr, memattr);
277 VM_OBJECT_LOCK(object);
278 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
279 vm_page_lock_queues();
280 for (i = 0; i < count; i++)
281 vm_page_free(m[i]);
282 vm_page_unlock_queues();
283 vm_page_insert(page, object, offset);
284 m[reqpage] = page;
285 }
286 page->valid = VM_PAGE_BITS_ALL;
287 return (VM_PAGER_OK);
288 }
289
290 static void
291 dev_pager_putpages(object, m, count, sync, rtvals)
292 vm_object_t object;
293 vm_page_t *m;
294 int count;
295 boolean_t sync;
296 int *rtvals;
297 {
298 panic("dev_pager_putpage called");
299 }
300
301 static boolean_t
302 dev_pager_haspage(object, pindex, before, after)
303 vm_object_t object;
304 vm_pindex_t pindex;
305 int *before;
306 int *after;
307 {
308 if (before != NULL)
309 *before = 0;
310 if (after != NULL)
311 *after = 0;
312 return (TRUE);
313 }
314
315 /*
316 * Create a fictitious page with the specified physical address and memory
317 * attribute. The memory attribute is the only the machine-dependent aspect
318 * of a fictitious page that must be initialized.
319 */
320 static vm_page_t
321 dev_pager_getfake(vm_paddr_t paddr, vm_memattr_t memattr)
322 {
323 vm_page_t m;
324
325 m = uma_zalloc(fakepg_zone, M_WAITOK | M_ZERO);
326 m->phys_addr = paddr;
327 /* Fictitious pages don't use "segind". */
328 m->flags = PG_FICTITIOUS;
329 /* Fictitious pages don't use "order" or "pool". */
330 m->oflags = VPO_BUSY;
331 m->wire_count = 1;
332 pmap_page_set_memattr(m, memattr);
333 return (m);
334 }
335
336 /*
337 * Release a fictitious page.
338 */
339 static void
340 dev_pager_putfake(vm_page_t m)
341 {
342
343 if (!(m->flags & PG_FICTITIOUS))
344 panic("dev_pager_putfake: bad page");
345 uma_zfree(fakepg_zone, m);
346 }
347
348 /*
349 * Update the given fictitious page to the specified physical address and
350 * memory attribute.
351 */
352 static void
353 dev_pager_updatefake(vm_page_t m, vm_paddr_t paddr, vm_memattr_t memattr)
354 {
355
356 if (!(m->flags & PG_FICTITIOUS))
357 panic("dev_pager_updatefake: bad page");
358 m->phys_addr = paddr;
359 pmap_page_set_memattr(m, memattr);
360 }
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