FreeBSD/Linux Kernel Cross Reference
sys/vm/sg_pager.c
1 /*-
2 * Copyright (c) 2009 Advanced Computing Technologies LLC
3 * Written by: John H. Baldwin <jhb@FreeBSD.org>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD: releng/9.0/sys/vm/sg_pager.c 219476 2011-03-11 07:07:48Z alc $");
30
31 /*
32 * This pager manages OBJT_SG objects. These objects are backed by
33 * a scatter/gather list of physical address ranges.
34 */
35
36 #include <sys/param.h>
37 #include <sys/lock.h>
38 #include <sys/mutex.h>
39 #include <sys/sglist.h>
40 #include <vm/vm.h>
41 #include <vm/vm_object.h>
42 #include <vm/vm_page.h>
43 #include <vm/vm_pager.h>
44 #include <vm/uma.h>
45
46 static vm_object_t sg_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
47 vm_ooffset_t, struct ucred *);
48 static void sg_pager_dealloc(vm_object_t);
49 static int sg_pager_getpages(vm_object_t, vm_page_t *, int, int);
50 static void sg_pager_putpages(vm_object_t, vm_page_t *, int,
51 boolean_t, int *);
52 static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *,
53 int *);
54
55 struct pagerops sgpagerops = {
56 .pgo_alloc = sg_pager_alloc,
57 .pgo_dealloc = sg_pager_dealloc,
58 .pgo_getpages = sg_pager_getpages,
59 .pgo_putpages = sg_pager_putpages,
60 .pgo_haspage = sg_pager_haspage,
61 };
62
63 static vm_object_t
64 sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
65 vm_ooffset_t foff, struct ucred *cred)
66 {
67 struct sglist *sg;
68 vm_object_t object;
69 vm_pindex_t npages, pindex;
70 int i;
71
72 /*
73 * Offset should be page aligned.
74 */
75 if (foff & PAGE_MASK)
76 return (NULL);
77
78 /*
79 * The scatter/gather list must only include page-aligned
80 * ranges.
81 */
82 npages = 0;
83 sg = handle;
84 for (i = 0; i < sg->sg_nseg; i++) {
85 if ((sg->sg_segs[i].ss_paddr % PAGE_SIZE) != 0 ||
86 (sg->sg_segs[i].ss_len % PAGE_SIZE) != 0)
87 return (NULL);
88 npages += sg->sg_segs[i].ss_len / PAGE_SIZE;
89 }
90
91 /*
92 * The scatter/gather list has a fixed size. Refuse requests
93 * to map beyond that.
94 */
95 size = round_page(size);
96 pindex = OFF_TO_IDX(foff + size);
97 if (pindex > npages)
98 return (NULL);
99
100 /*
101 * Allocate a new object and associate it with the
102 * scatter/gather list. It is ok for our purposes to have
103 * multiple VM objects associated with the same scatter/gather
104 * list because scatter/gather lists are static. This is also
105 * simpler than ensuring a unique object per scatter/gather
106 * list.
107 */
108 object = vm_object_allocate(OBJT_SG, npages);
109 object->handle = sglist_hold(sg);
110 TAILQ_INIT(&object->un_pager.sgp.sgp_pglist);
111 return (object);
112 }
113
114 static void
115 sg_pager_dealloc(vm_object_t object)
116 {
117 struct sglist *sg;
118 vm_page_t m;
119
120 /*
121 * Free up our fake pages.
122 */
123 while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) {
124 TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, pageq);
125 vm_page_putfake(m);
126 }
127
128 sg = object->handle;
129 sglist_free(sg);
130 }
131
132 static int
133 sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
134 {
135 struct sglist *sg;
136 vm_page_t m_paddr, page;
137 vm_pindex_t offset;
138 vm_paddr_t paddr;
139 vm_memattr_t memattr;
140 size_t space;
141 int i;
142
143 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
144 sg = object->handle;
145 memattr = object->memattr;
146 VM_OBJECT_UNLOCK(object);
147 offset = m[reqpage]->pindex;
148
149 /*
150 * Lookup the physical address of the requested page. An initial
151 * value of '1' instead of '' is used so we can assert that the
152 * page is found since '' can be a valid page-aligned physical
153 * address.
154 */
155 space = 0;
156 paddr = 1;
157 for (i = 0; i < sg->sg_nseg; i++) {
158 if (space + sg->sg_segs[i].ss_len <= (offset * PAGE_SIZE)) {
159 space += sg->sg_segs[i].ss_len;
160 continue;
161 }
162 paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space;
163 break;
164 }
165 KASSERT(paddr != 1, ("invalid SG page index"));
166
167 /* If "paddr" is a real page, perform a sanity check on "memattr". */
168 if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL &&
169 pmap_page_get_memattr(m_paddr) != memattr) {
170 memattr = pmap_page_get_memattr(m_paddr);
171 printf(
172 "WARNING: A device driver has set \"memattr\" inconsistently.\n");
173 }
174
175 /* Return a fake page for the requested page. */
176 KASSERT(!(m[reqpage]->flags & PG_FICTITIOUS),
177 ("backing page for SG is fake"));
178
179 /* Construct a new fake page. */
180 page = vm_page_getfake(paddr, memattr);
181 VM_OBJECT_LOCK(object);
182 TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, pageq);
183
184 /* Free the original pages and insert this fake page into the object. */
185 for (i = 0; i < count; i++) {
186 vm_page_lock(m[i]);
187 vm_page_free(m[i]);
188 vm_page_unlock(m[i]);
189 }
190 vm_page_insert(page, object, offset);
191 m[reqpage] = page;
192 page->valid = VM_PAGE_BITS_ALL;
193
194 return (VM_PAGER_OK);
195 }
196
197 static void
198 sg_pager_putpages(vm_object_t object, vm_page_t *m, int count,
199 boolean_t sync, int *rtvals)
200 {
201
202 panic("sg_pager_putpage called");
203 }
204
205 static boolean_t
206 sg_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
207 int *after)
208 {
209
210 if (before != NULL)
211 *before = 0;
212 if (after != NULL)
213 *after = 0;
214 return (TRUE);
215 }
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