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1424 jermar 1
/*
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 * Copyright (C) 2006 Jakub Jermar
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
8
 *
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 * - 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
18
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19
 * 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
 */
28
 
1702 cejka 29
 /** @addtogroup genericmm
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 * @{
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 */
32
 
1424 jermar 33
/**
1702 cejka 34
 * @file
1424 jermar 35
 * @brief	Backend for address space areas backed by an ELF image.
36
 */
37
 
38
#include <elf.h>
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#include <debug.h>
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#include <arch/types.h>
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#include <typedefs.h>
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#include <mm/as.h>
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#include <mm/frame.h>
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#include <mm/slab.h>
1426 jermar 45
#include <mm/page.h>
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#include <genarch/mm/page_pt.h>
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#include <genarch/mm/page_ht.h>
1424 jermar 48
#include <align.h>
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#include <memstr.h>
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#include <macros.h>
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#include <arch.h>
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53
static int elf_page_fault(as_area_t *area, __address addr, pf_access_t access);
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static void elf_frame_free(as_area_t *area, __address page, __address frame);
1426 jermar 55
static void elf_share(as_area_t *area);
1424 jermar 56
 
57
mem_backend_t elf_backend = {
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	.page_fault = elf_page_fault,
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	.frame_free = elf_frame_free,
1426 jermar 60
	.share = elf_share
1424 jermar 61
};
62
 
63
/** Service a page fault in the ELF backend address space area.
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 *
65
 * The address space area and page tables must be already locked.
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 *
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 * @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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 *
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 * @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e. serviced).
72
 */
73
int elf_page_fault(as_area_t *area, __address addr, pf_access_t access)
74
{
1425 jermar 75
	elf_header_t *elf = area->backend_data.elf;
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	elf_segment_header_t *entry = area->backend_data.segment;
1426 jermar 77
	btree_node_t *leaf;
1424 jermar 78
	__address base, frame;
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	index_t i;
80
 
81
	if (!as_area_check_access(area, access))
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		return AS_PF_FAULT;
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84
	ASSERT((addr >= entry->p_vaddr) && (addr < entry->p_vaddr + entry->p_memsz));
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	i = (addr - entry->p_vaddr) >> PAGE_WIDTH;
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	base = (__address) (((void *) elf) + entry->p_offset);
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	ASSERT(ALIGN_UP(base, FRAME_SIZE) == base);
1426 jermar 88
 
89
	if (area->sh_info) {
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		bool found = false;
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92
		/*
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		 * The address space area is shared.
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		 */
95
 
96
		mutex_lock(&area->sh_info->lock);
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		frame = (__address) btree_search(&area->sh_info->pagemap,
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			ALIGN_DOWN(addr, PAGE_SIZE) - area->base, &leaf);
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		if (!frame) {
100
			int i;
101
 
102
			/*
103
			 * Workaround for valid NULL address.
104
			 */
105
 
106
			for (i = 0; i < leaf->keys; i++) {
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				if (leaf->key[i] == ALIGN_DOWN(addr, PAGE_SIZE)) {
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					found = true;
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					break;
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				}
111
			}
112
		}
113
		if (frame || found) {
1546 jermar 114
			frame_reference_add(ADDR2PFN(frame));
1426 jermar 115
			page_mapping_insert(AS, addr, frame, as_area_get_flags(area));
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			if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
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				panic("Could not insert used space.\n");
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			mutex_unlock(&area->sh_info->lock);
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			return AS_PF_OK;
120
		}
121
	}
1424 jermar 122
 
1426 jermar 123
	/*
124
	 * The area is either not shared or the pagemap does not contain the mapping.
125
	 */
126
 
1424 jermar 127
	if (ALIGN_DOWN(addr, PAGE_SIZE) + PAGE_SIZE < entry->p_vaddr + entry->p_filesz) {
128
		/*
129
		 * Initialized portion of the segment. The memory is backed
130
		 * directly by the content of the ELF image. Pages are
131
		 * only copied if the segment is writable so that there
132
		 * can be more instantions of the same memory ELF image
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		 * used at a time. Note that this could be later done
134
		 * as COW.
135
		 */
136
		if (entry->p_flags & PF_W) {
137
			frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
138
			memcpy((void *) PA2KA(frame), (void *) (base + i*FRAME_SIZE), FRAME_SIZE);
1426 jermar 139
 
140
			if (area->sh_info) {
1546 jermar 141
				frame_reference_add(ADDR2PFN(frame));
1426 jermar 142
				btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
143
					(void *) frame, leaf);
144
			}
145
 
1424 jermar 146
		} else {
147
			frame = KA2PA(base + i*FRAME_SIZE);
148
		}	
149
	} else if (ALIGN_DOWN(addr, PAGE_SIZE) >= ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
150
		/*
151
		 * This is the uninitialized portion of the segment.
152
		 * It is not physically present in the ELF image.
153
		 * To resolve the situation, a frame must be allocated
154
		 * and cleared.
155
		 */
156
		frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
157
		memsetb(PA2KA(frame), FRAME_SIZE, 0);
1426 jermar 158
 
159
		if (area->sh_info) {
1546 jermar 160
			frame_reference_add(ADDR2PFN(frame));
1426 jermar 161
			btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
162
				(void *) frame, leaf);
163
		}
164
 
1424 jermar 165
	} else {
166
		size_t size;
167
		/*
168
		 * The mixed case.
169
		 * The lower part is backed by the ELF image and
170
		 * the upper part is anonymous memory.
171
		 */
172
		size = entry->p_filesz - (i<<PAGE_WIDTH);
173
		frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
174
		memsetb(PA2KA(frame) + size, FRAME_SIZE - size, 0);
175
		memcpy((void *) PA2KA(frame), (void *) (base + i*FRAME_SIZE), size);
1426 jermar 176
 
177
		if (area->sh_info) {
1546 jermar 178
			frame_reference_add(ADDR2PFN(frame));
1426 jermar 179
			btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
180
				(void *) frame, leaf);
181
		}
182
 
1424 jermar 183
	}
184
 
1426 jermar 185
	if (area->sh_info)
186
		mutex_unlock(&area->sh_info->lock);
187
 
1424 jermar 188
	page_mapping_insert(AS, addr, frame, as_area_get_flags(area));
1426 jermar 189
	if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
190
		panic("Could not insert used space.\n");
1424 jermar 191
 
192
	return AS_PF_OK;
193
}
194
 
195
/** Free a frame that is backed by the ELF backend.
196
 *
197
 * The address space area and page tables must be already locked.
198
 *
199
 * @param area Pointer to the address space area.
200
 * @param page Page that is mapped to frame. Must be aligned to PAGE_SIZE.
201
 * @param frame Frame to be released.
202
 *
203
 */
204
void elf_frame_free(as_area_t *area, __address page, __address frame)
205
{
1425 jermar 206
	elf_header_t *elf = area->backend_data.elf;
207
	elf_segment_header_t *entry = area->backend_data.segment;
1424 jermar 208
	__address base;
209
	index_t i;
210
 
211
	ASSERT((page >= entry->p_vaddr) && (page < entry->p_vaddr + entry->p_memsz));
212
	i = (page - entry->p_vaddr) >> PAGE_WIDTH;
213
	base = (__address) (((void *) elf) + entry->p_offset);
214
	ASSERT(ALIGN_UP(base, FRAME_SIZE) == base);
215
 
216
	if (page + PAGE_SIZE < ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
217
		if (entry->p_flags & PF_W) {
218
			/*
219
			 * Free the frame with the copy of writable segment data.
220
			 */
221
			frame_free(ADDR2PFN(frame));
222
		}
223
	} else {
224
		/*
225
		 * The frame is either anonymous memory or the mixed case (i.e. lower
226
		 * part is backed by the ELF image and the upper is anonymous).
227
		 * In any case, a frame needs to be freed.
228
		 */
229
		frame_free(ADDR2PFN(frame)); 
230
	}
231
}
1426 jermar 232
 
233
/** Share ELF image backed address space area.
234
 *
235
 * If the area is writable, then all mapped pages are duplicated in the pagemap.
236
 * Otherwise only portions of the area that are not backed by the ELF image
237
 * are put into the pagemap.
238
 *
239
 * The address space and address space area must be locked prior to the call.
240
 *
241
 * @param area Address space area.
242
 */
243
void elf_share(as_area_t *area)
244
{
245
	elf_segment_header_t *entry = area->backend_data.segment;
246
	link_t *cur;
247
	btree_node_t *leaf, *node;
248
	__address start_anon = entry->p_vaddr + entry->p_filesz;
249
 
250
	/*
251
	 * Find the node in which to start linear search.
252
	 */
253
	if (area->flags & AS_AREA_WRITE) {
254
		node = list_get_instance(area->used_space.leaf_head.next, btree_node_t, leaf_link);
255
	} else {
256
		(void) btree_search(&area->sh_info->pagemap, start_anon, &leaf);
257
		node = btree_leaf_node_left_neighbour(&area->sh_info->pagemap, leaf);
258
		if (!node)
259
			node = leaf;
260
	}
261
 
262
	/*
263
	 * Copy used anonymous portions of the area to sh_info's page map.
264
	 */
265
	mutex_lock(&area->sh_info->lock);
266
	for (cur = &node->leaf_link; cur != &area->used_space.leaf_head; cur = cur->next) {
267
		int i;
268
 
269
		node = list_get_instance(cur, btree_node_t, leaf_link);
270
 
271
		for (i = 0; i < node->keys; i++) {
272
			__address base = node->key[i];
273
			count_t count = (count_t) node->value[i];
274
			int j;
275
 
276
			/*
277
			 * Skip read-only areas of used space that are backed
278
			 * by the ELF image.
279
			 */
280
			if (!(area->flags & AS_AREA_WRITE))
281
				if (base + count*PAGE_SIZE <= start_anon)
282
					continue;
283
 
284
			for (j = 0; j < count; j++) {
285
				pte_t *pte;
286
 
287
				/*
288
				 * Skip read-only pages that are backed by the ELF image.
289
				 */
290
				if (!(area->flags & AS_AREA_WRITE))
291
					if (base + (j + 1)*PAGE_SIZE <= start_anon)
292
						continue;
293
 
294
				page_table_lock(area->as, false);
295
				pte = page_mapping_find(area->as, base + j*PAGE_SIZE);
296
				ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));
297
				btree_insert(&area->sh_info->pagemap, (base + j*PAGE_SIZE) - area->base,
298
					(void *) PTE_GET_FRAME(pte), NULL);
299
				page_table_unlock(area->as, false);
1546 jermar 300
				frame_reference_add(ADDR2PFN(PTE_GET_FRAME(pte)));
1426 jermar 301
			}
302
 
303
		}
304
	}
305
	mutex_unlock(&area->sh_info->lock);
306
}
1702 cejka 307
 
308
 /** @}
309
 */
310