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/9.2/sys/vm/sg_pager.c 240238 2012-09-08 16:40:18Z kib $");
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_param.h>
42 #include <vm/vm_object.h>
43 #include <vm/vm_page.h>
44 #include <vm/vm_pager.h>
45 #include <vm/uma.h>
46
47 static vm_object_t sg_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
48 vm_ooffset_t, struct ucred *);
49 static void sg_pager_dealloc(vm_object_t);
50 static int sg_pager_getpages(vm_object_t, vm_page_t *, int, int);
51 static void sg_pager_putpages(vm_object_t, vm_page_t *, int,
52 boolean_t, int *);
53 static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *,
54 int *);
55
56 struct pagerops sgpagerops = {
57 .pgo_alloc = sg_pager_alloc,
58 .pgo_dealloc = sg_pager_dealloc,
59 .pgo_getpages = sg_pager_getpages,
60 .pgo_putpages = sg_pager_putpages,
61 .pgo_haspage = sg_pager_haspage,
62 };
63
64 static vm_object_t
65 sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
66 vm_ooffset_t foff, struct ucred *cred)
67 {
68 struct sglist *sg;
69 vm_object_t object;
70 vm_pindex_t npages, pindex;
71 int i;
72
73 /*
74 * Offset should be page aligned.
75 */
76 if (foff & PAGE_MASK)
77 return (NULL);
78
79 /*
80 * The scatter/gather list must only include page-aligned
81 * ranges.
82 */
83 npages = 0;
84 sg = handle;
85 for (i = 0; i < sg->sg_nseg; i++) {
86 if ((sg->sg_segs[i].ss_paddr % PAGE_SIZE) != 0 ||
87 (sg->sg_segs[i].ss_len % PAGE_SIZE) != 0)
88 return (NULL);
89 npages += sg->sg_segs[i].ss_len / PAGE_SIZE;
90 }
91
92 /*
93 * The scatter/gather list has a fixed size. Refuse requests
94 * to map beyond that.
95 */
96 size = round_page(size);
97 pindex = OFF_TO_IDX(foff + size);
98 if (pindex > npages)
99 return (NULL);
100
101 /*
102 * Allocate a new object and associate it with the
103 * scatter/gather list. It is ok for our purposes to have
104 * multiple VM objects associated with the same scatter/gather
105 * list because scatter/gather lists are static. This is also
106 * simpler than ensuring a unique object per scatter/gather
107 * list.
108 */
109 object = vm_object_allocate(OBJT_SG, npages);
110 object->handle = sglist_hold(sg);
111 TAILQ_INIT(&object->un_pager.sgp.sgp_pglist);
112 return (object);
113 }
114
115 static void
116 sg_pager_dealloc(vm_object_t object)
117 {
118 struct sglist *sg;
119 vm_page_t m;
120
121 /*
122 * Free up our fake pages.
123 */
124 while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) {
125 TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, pageq);
126 vm_page_putfake(m);
127 }
128
129 sg = object->handle;
130 sglist_free(sg);
131 }
132
133 static int
134 sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
135 {
136 struct sglist *sg;
137 vm_page_t m_paddr, page;
138 vm_pindex_t offset;
139 vm_paddr_t paddr;
140 vm_memattr_t memattr;
141 size_t space;
142 int i;
143
144 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
145 sg = object->handle;
146 memattr = object->memattr;
147 VM_OBJECT_UNLOCK(object);
148 offset = m[reqpage]->pindex;
149
150 /*
151 * Lookup the physical address of the requested page. An initial
152 * value of '1' instead of '' is used so we can assert that the
153 * page is found since '' can be a valid page-aligned physical
154 * address.
155 */
156 space = 0;
157 paddr = 1;
158 for (i = 0; i < sg->sg_nseg; i++) {
159 if (space + sg->sg_segs[i].ss_len <= (offset * PAGE_SIZE)) {
160 space += sg->sg_segs[i].ss_len;
161 continue;
162 }
163 paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space;
164 break;
165 }
166 KASSERT(paddr != 1, ("invalid SG page index"));
167
168 /* If "paddr" is a real page, perform a sanity check on "memattr". */
169 if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL &&
170 pmap_page_get_memattr(m_paddr) != memattr) {
171 memattr = pmap_page_get_memattr(m_paddr);
172 printf(
173 "WARNING: A device driver has set \"memattr\" inconsistently.\n");
174 }
175
176 /* Return a fake page for the requested page. */
177 KASSERT(!(m[reqpage]->flags & PG_FICTITIOUS),
178 ("backing page for SG is fake"));
179
180 /* Construct a new fake page. */
181 page = vm_page_getfake(paddr, memattr);
182 VM_OBJECT_LOCK(object);
183 TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, pageq);
184
185 /* Free the original pages and insert this fake page into the object. */
186 for (i = 0; i < count; i++) {
187 vm_page_lock(m[i]);
188 vm_page_free(m[i]);
189 vm_page_unlock(m[i]);
190 }
191 vm_page_insert(page, object, offset);
192 m[reqpage] = page;
193 page->valid = VM_PAGE_BITS_ALL;
194
195 return (VM_PAGER_OK);
196 }
197
198 static void
199 sg_pager_putpages(vm_object_t object, vm_page_t *m, int count,
200 boolean_t sync, int *rtvals)
201 {
202
203 panic("sg_pager_putpage called");
204 }
205
206 static boolean_t
207 sg_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
208 int *after)
209 {
210
211 if (before != NULL)
212 *before = 0;
213 if (after != NULL)
214 *after = 0;
215 return (TRUE);
216 }
Cache object: d96adb87a8935aac1d520b503cb98d28
|