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1424 jermar 1
/*
2071 jermar 2
 * Copyright (c) 2006 Jakub Jermar
1424 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
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 * are met:
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 *
9
 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
 */
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1757 jermar 29
/** @addtogroup genericmm
1702 cejka 30
 * @{
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 */
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1424 jermar 33
/**
1702 cejka 34
 * @file
1424 jermar 35
 * @brief	Backend for anonymous memory address space areas.
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 *
37
 */
38
 
39
#include <mm/as.h>
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#include <mm/page.h>
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#include <genarch/mm/page_pt.h>
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#include <genarch/mm/page_ht.h>
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#include <mm/frame.h>
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#include <mm/slab.h>
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#include <synch/mutex.h>
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#include <adt/list.h>
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#include <adt/btree.h>
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#include <errno.h>
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#include <arch/types.h>
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#include <align.h>
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#include <arch.h>
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2076 jermar 53
#ifdef CONFIG_VIRT_IDX_DCACHE
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#include <arch/mm/cache.h>
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#endif
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1780 jermar 57
static int anon_page_fault(as_area_t *area, uintptr_t addr, pf_access_t access);
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static void anon_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame);
1424 jermar 59
static void anon_share(as_area_t *area);
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61
mem_backend_t anon_backend = {
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	.page_fault = anon_page_fault,
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	.frame_free = anon_frame_free,
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	.share = anon_share
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};
66
 
67
/** Service a page fault in the anonymous memory address space area.
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 *
69
 * The address space area and page tables must be already locked.
70
 *
71
 * @param area Pointer to the address space area.
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 * @param addr Faulting virtual address.
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 * @param access Access mode that caused the fault (i.e. read/write/exec).
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 *
2132 jermar 75
 * @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e.
76
 *     serviced).
1424 jermar 77
 */
1780 jermar 78
int anon_page_fault(as_area_t *area, uintptr_t addr, pf_access_t access)
1424 jermar 79
{
1780 jermar 80
	uintptr_t frame;
1424 jermar 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
2132 jermar 90
		 * in the pagemap of the address space area share info
91
		 * structure.
1424 jermar 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
		 */
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		mutex_lock(&area->sh_info->lock);
1780 jermar 96
		frame = (uintptr_t) btree_search(&area->sh_info->pagemap,
2134 jermar 97
		    ALIGN_DOWN(addr, PAGE_SIZE) - area->base, &leaf);
1424 jermar 98
		if (!frame) {
99
			bool allocate = true;
2745 decky 100
			unsigned int i;
1424 jermar 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++) {
2132 jermar 107
				if (leaf->key[i] ==
3382 jermar 108
				    ALIGN_DOWN(addr, PAGE_SIZE) - area->base) {
1424 jermar 109
					allocate = false;
110
					break;
111
				}
112
			}
113
			if (allocate) {
1780 jermar 114
				frame = (uintptr_t) frame_alloc(ONE_FRAME, 0);
3104 svoboda 115
				memsetb((void *) PA2KA(frame), FRAME_SIZE, 0);
1424 jermar 116
 
117
				/*
2132 jermar 118
				 * Insert the address of the newly allocated
119
				 * frame to the pagemap.
1424 jermar 120
				 */
2132 jermar 121
				btree_insert(&area->sh_info->pagemap,
122
				    ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
123
				    (void *) frame, leaf);
1424 jermar 124
			}
125
		}
1545 jermar 126
		frame_reference_add(ADDR2PFN(frame));
1424 jermar 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
		 */
1954 jermar 144
		frame = (uintptr_t) frame_alloc(ONE_FRAME, 0);
3104 svoboda 145
		memsetb((void *) PA2KA(frame), FRAME_SIZE, 0);
1424 jermar 146
	}
147
 
148
	/*
149
	 * Map 'page' to 'frame'.
2132 jermar 150
	 * Note that TLB shootdown is not attempted as only new information is
151
	 * being inserted into page tables.
1424 jermar 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))
3790 svoboda 155
		panic("Cannot insert used space.");
1424 jermar 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.
2076 jermar 165
 * @param page Virtual address of the page corresponding to the frame.
1424 jermar 166
 * @param frame Frame to be released.
167
 */
1780 jermar 168
void anon_frame_free(as_area_t *area, uintptr_t page, uintptr_t frame)
1424 jermar 169
{
1760 palkovsky 170
	frame_free(frame);
1424 jermar 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
 *
1426 jermar 178
 * The address space and address space area must be already locked.
1424 jermar 179
 *
180
 * @param area Address space area to be shared.
181
 */
182
void 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);
2132 jermar 190
	for (cur = area->used_space.leaf_head.next;
191
	    cur != &area->used_space.leaf_head; cur = cur->next) {
1424 jermar 192
		btree_node_t *node;
2745 decky 193
		unsigned int i;
1424 jermar 194
 
195
		node = list_get_instance(cur, btree_node_t, leaf_link);
196
		for (i = 0; i < node->keys; i++) {
1780 jermar 197
			uintptr_t base = node->key[i];
4490 decky 198
			size_t count = (size_t) node->value[i];
2745 decky 199
			unsigned int j;
1424 jermar 200
 
201
			for (j = 0; j < count; j++) {
202
				pte_t *pte;
203
 
204
				page_table_lock(area->as, false);
2132 jermar 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);
1424 jermar 212
				page_table_unlock(area->as, false);
2132 jermar 213
 
214
				pfn_t pfn = ADDR2PFN(PTE_GET_FRAME(pte));
215
				frame_reference_add(pfn);
1424 jermar 216
			}
2134 jermar 217
 
1424 jermar 218
		}
219
	}
220
	mutex_unlock(&area->sh_info->lock);
221
}
1702 cejka 222
 
1757 jermar 223
/** @}
1702 cejka 224
 */