FreeBSD/Linux Kernel Cross Reference
sys/vm/phys_pager.c
1 /*-
2 * Copyright (c) 2000 Peter Wemm
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 */
25
26 #include <sys/cdefs.h>
27 __FBSDID("$FreeBSD: releng/8.4/sys/vm/phys_pager.c 221125 2011-04-27 18:00:46Z jhb $");
28
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/conf.h>
32 #include <sys/kernel.h>
33 #include <sys/lock.h>
34 #include <sys/proc.h>
35 #include <sys/mutex.h>
36 #include <sys/mman.h>
37 #include <sys/sysctl.h>
38
39 #include <vm/vm.h>
40 #include <vm/vm_object.h>
41 #include <vm/vm_page.h>
42 #include <vm/vm_pager.h>
43
44 /* list of phys pager objects */
45 static struct pagerlst phys_pager_object_list;
46 /* protect access to phys_pager_object_list */
47 static struct mtx phys_pager_mtx;
48
49 static void
50 phys_pager_init(void)
51 {
52
53 TAILQ_INIT(&phys_pager_object_list);
54 mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
55 }
56
57 /*
58 * MPSAFE
59 */
60 static vm_object_t
61 phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
62 vm_ooffset_t foff, struct ucred *cred)
63 {
64 vm_object_t object, object1;
65 vm_pindex_t pindex;
66
67 /*
68 * Offset should be page aligned.
69 */
70 if (foff & PAGE_MASK)
71 return (NULL);
72
73 pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
74
75 if (handle != NULL) {
76 mtx_lock(&phys_pager_mtx);
77 /*
78 * Look up pager, creating as necessary.
79 */
80 object1 = NULL;
81 object = vm_pager_object_lookup(&phys_pager_object_list, handle);
82 if (object == NULL) {
83 /*
84 * Allocate object and associate it with the pager.
85 */
86 mtx_unlock(&phys_pager_mtx);
87 object1 = vm_object_allocate(OBJT_PHYS, pindex);
88 mtx_lock(&phys_pager_mtx);
89 object = vm_pager_object_lookup(&phys_pager_object_list,
90 handle);
91 if (object != NULL) {
92 /*
93 * We raced with other thread while
94 * allocating object.
95 */
96 if (pindex > object->size)
97 object->size = pindex;
98 } else {
99 object = object1;
100 object1 = NULL;
101 object->handle = handle;
102 TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
103 pager_object_list);
104 }
105 } else {
106 if (pindex > object->size)
107 object->size = pindex;
108 }
109 mtx_unlock(&phys_pager_mtx);
110 vm_object_deallocate(object1);
111 } else {
112 object = vm_object_allocate(OBJT_PHYS, pindex);
113 }
114
115 return (object);
116 }
117
118 /*
119 * MPSAFE
120 */
121 static void
122 phys_pager_dealloc(vm_object_t object)
123 {
124
125 if (object->handle != NULL) {
126 VM_OBJECT_UNLOCK(object);
127 mtx_lock(&phys_pager_mtx);
128 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
129 mtx_unlock(&phys_pager_mtx);
130 VM_OBJECT_LOCK(object);
131 }
132 }
133
134 /*
135 * Fill as many pages as vm_fault has allocated for us.
136 */
137 static int
138 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
139 {
140 int i;
141
142 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
143 for (i = 0; i < count; i++) {
144 if (m[i]->valid == 0) {
145 if ((m[i]->flags & PG_ZERO) == 0)
146 pmap_zero_page(m[i]);
147 m[i]->valid = VM_PAGE_BITS_ALL;
148 }
149 KASSERT(m[i]->valid == VM_PAGE_BITS_ALL,
150 ("phys_pager_getpages: partially valid page %p", m[i]));
151 KASSERT(m[i]->dirty == 0,
152 ("phys_pager_getpages: dirty page %p", m[i]));
153 /* The requested page must remain busy, the others not. */
154 if (i == reqpage)
155 vm_page_flash(m[i]);
156 else
157 vm_page_wakeup(m[i]);
158 }
159 return (VM_PAGER_OK);
160 }
161
162 static void
163 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
164 int *rtvals)
165 {
166
167 panic("phys_pager_putpage called");
168 }
169
170 /*
171 * Implement a pretty aggressive clustered getpages strategy. Hint that
172 * everything in an entire 4MB window should be prefaulted at once.
173 *
174 * XXX 4MB (1024 slots per page table page) is convenient for x86,
175 * but may not be for other arches.
176 */
177 #ifndef PHYSCLUSTER
178 #define PHYSCLUSTER 1024
179 #endif
180 static boolean_t
181 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
182 int *after)
183 {
184 vm_pindex_t base, end;
185
186 base = pindex & (~(PHYSCLUSTER - 1));
187 end = base + (PHYSCLUSTER - 1);
188 if (before != NULL)
189 *before = pindex - base;
190 if (after != NULL)
191 *after = end - pindex;
192 return (TRUE);
193 }
194
195 struct pagerops physpagerops = {
196 .pgo_init = phys_pager_init,
197 .pgo_alloc = phys_pager_alloc,
198 .pgo_dealloc = phys_pager_dealloc,
199 .pgo_getpages = phys_pager_getpages,
200 .pgo_putpages = phys_pager_putpages,
201 .pgo_haspage = phys_pager_haspage,
202 };
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