source: mainline/kernel/generic/src/mm/backend_anon.c@ a000878c

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since a000878c was 98000fb, checked in by Martin Decky <martin@…>, 16 years ago

remove redundant index_t and count_t types (which were always quite ambiguous and not actually needed)
  • Property mode set to 100644
File size: 6.6 KB
Line 
1/*
2 * Copyright (c) 2006 Jakub Jermar
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * - 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 * - The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/** @addtogroup genericmm
30 * @{
31 */
32
33/**
34 * @file
35 * @brief Backend for anonymous memory address space areas.
36 *
37 */
38
39#include <mm/as.h>
40#include <mm/page.h>
41#include <genarch/mm/page_pt.h>
42#include <genarch/mm/page_ht.h>
43#include <mm/frame.h>
44#include <mm/slab.h>
45#include <synch/mutex.h>
46#include <adt/list.h>
47#include <adt/btree.h>
48#include <errno.h>
49#include <arch/types.h>
50#include <align.h>
51#include <arch.h>
52
53#ifdef CONFIG_VIRT_IDX_DCACHE
54#include <arch/mm/cache.h>
55#endif
56
57static int anon_page_fault(as_area_t *area, uintptr_t addr, pf_access_t access);
58static void anon_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame);
59static void anon_share(as_area_t *area);
60
61mem_backend_t anon_backend = {
62 .page_fault = anon_page_fault,
63 .frame_free = anon_frame_free,
64 .share = anon_share
65};
66
67/** Service a page fault in the anonymous memory address space area.
68 *
69 * The address space area and page tables must be already locked.
70 *
71 * @param area Pointer to the address space area.
72 * @param addr Faulting virtual address.
73 * @param access Access mode that caused the fault (i.e. read/write/exec).
74 *
75 * @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e.
76 * serviced).
77 */
78int anon_page_fault(as_area_t *area, uintptr_t addr, pf_access_t access)
79{
80 uintptr_t frame;
81
82 if (!as_area_check_access(area, access))
83 return AS_PF_FAULT;
84
85 if (area->sh_info) {
86 btree_node_t *leaf;
87
88 /*
89 * The area is shared, chances are that the mapping can be found
90 * in the pagemap of the address space area share info
91 * structure.
92 * In the case that the pagemap does not contain the respective
93 * mapping, a new frame is allocated and the mapping is created.
94 */
95 mutex_lock(&area->sh_info->lock);
96 frame = (uintptr_t) btree_search(&area->sh_info->pagemap,
97 ALIGN_DOWN(addr, PAGE_SIZE) - area->base, &leaf);
98 if (!frame) {
99 bool allocate = true;
100 unsigned int i;
101
102 /*
103 * Zero can be returned as a valid frame address.
104 * Just a small workaround.
105 */
106 for (i = 0; i < leaf->keys; i++) {
107 if (leaf->key[i] ==
108 ALIGN_DOWN(addr, PAGE_SIZE) - area->base) {
109 allocate = false;
110 break;
111 }
112 }
113 if (allocate) {
114 frame = (uintptr_t) frame_alloc(ONE_FRAME, 0);
115 memsetb((void *) PA2KA(frame), FRAME_SIZE, 0);
116
117 /*
118 * Insert the address of the newly allocated
119 * frame to the pagemap.
120 */
121 btree_insert(&area->sh_info->pagemap,
122 ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
123 (void *) frame, leaf);
124 }
125 }
126 frame_reference_add(ADDR2PFN(frame));
127 mutex_unlock(&area->sh_info->lock);
128 } else {
129
130 /*
131 * In general, there can be several reasons that
132 * can have caused this fault.
133 *
134 * - non-existent mapping: the area is an anonymous
135 * area (e.g. heap or stack) and so far has not been
136 * allocated a frame for the faulting page
137 *
138 * - non-present mapping: another possibility,
139 * currently not implemented, would be frame
140 * reuse; when this becomes a possibility,
141 * do not forget to distinguish between
142 * the different causes
143 */
144 frame = (uintptr_t) frame_alloc(ONE_FRAME, 0);
145 memsetb((void *) PA2KA(frame), FRAME_SIZE, 0);
146 }
147
148 /*
149 * Map 'page' to 'frame'.
150 * Note that TLB shootdown is not attempted as only new information is
151 * being inserted into page tables.
152 */
153 page_mapping_insert(AS, addr, frame, as_area_get_flags(area));
154 if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
155 panic("Cannot insert used space.");
156
157 return AS_PF_OK;
158}
159
160/** Free a frame that is backed by the anonymous memory backend.
161 *
162 * The address space area and page tables must be already locked.
163 *
164 * @param area Ignored.
165 * @param page Virtual address of the page corresponding to the frame.
166 * @param frame Frame to be released.
167 */
168void anon_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame)
169{
170 frame_free(frame);
171}
172
173/** Share the anonymous address space area.
174 *
175 * Sharing of anonymous area is done by duplicating its entire mapping
176 * to the pagemap. Page faults will primarily search for frames there.
177 *
178 * The address space and address space area must be already locked.
179 *
180 * @param area Address space area to be shared.
181 */
182void anon_share(as_area_t *area)
183{
184 link_t *cur;
185
186 /*
187 * Copy used portions of the area to sh_info's page map.
188 */
189 mutex_lock(&area->sh_info->lock);
190 for (cur = area->used_space.leaf_head.next;
191 cur != &area->used_space.leaf_head; cur = cur->next) {
192 btree_node_t *node;
193 unsigned int i;
194
195 node = list_get_instance(cur, btree_node_t, leaf_link);
196 for (i = 0; i < node->keys; i++) {
197 uintptr_t base = node->key[i];
198 size_t count = (size_t) node->value[i];
199 unsigned int j;
200
201 for (j = 0; j < count; j++) {
202 pte_t *pte;
203
204 page_table_lock(area->as, false);
205 pte = page_mapping_find(area->as,
206 base + j * PAGE_SIZE);
207 ASSERT(pte && PTE_VALID(pte) &&
208 PTE_PRESENT(pte));
209 btree_insert(&area->sh_info->pagemap,
210 (base + j * PAGE_SIZE) - area->base,
211 (void *) PTE_GET_FRAME(pte), NULL);
212 page_table_unlock(area->as, false);
213
214 pfn_t pfn = ADDR2PFN(PTE_GET_FRAME(pte));
215 frame_reference_add(pfn);
216 }
217
218 }
219 }
220 mutex_unlock(&area->sh_info->lock);
221}
222
223/** @}
224 */
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