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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:
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 *
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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
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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.
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 */
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/**
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 * @file    backend_elf.c
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 * @brief   Backend for address space areas backed by an ELF image.
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 */
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#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 41
#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 44
#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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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 51
static void elf_share(as_area_t *area);
1424 jermar 52
 
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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 56
    .share = elf_share
1424 jermar 57
};
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59
/** Service a page fault in the ELF backend address space area.
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 *
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 * 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).
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 */
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int elf_page_fault(as_area_t *area, __address addr, pf_access_t access)
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{
1425 jermar 71
    elf_header_t *elf = area->backend_data.elf;
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    elf_segment_header_t *entry = area->backend_data.segment;
1426 jermar 73
    btree_node_t *leaf;
1424 jermar 74
    __address base, frame;
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    index_t i;
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    if (!as_area_check_access(area, access))
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        return AS_PF_FAULT;
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80
    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 84
 
85
    if (area->sh_info) {
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        bool found = false;
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88
        /*
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         * The address space area is shared.
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         */
91
 
92
        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) {
96
            int i;
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98
            /*
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             * Workaround for valid NULL address.
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             */
101
 
102
            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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                }
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            }
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        }
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        if (frame || found) {
1546 jermar 110
            frame_reference_add(ADDR2PFN(frame));
1426 jermar 111
            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;
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        }
117
    }
1424 jermar 118
 
1426 jermar 119
    /*
120
     * The area is either not shared or the pagemap does not contain the mapping.
121
     */
122
 
1424 jermar 123
    if (ALIGN_DOWN(addr, PAGE_SIZE) + PAGE_SIZE < entry->p_vaddr + entry->p_filesz) {
124
        /*
125
         * Initialized portion of the segment. The memory is backed
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         * directly by the content of the ELF image. Pages are
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         * only copied if the segment is writable so that there
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         * 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
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         * as COW.
131
         */
132
        if (entry->p_flags & PF_W) {
133
            frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
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            memcpy((void *) PA2KA(frame), (void *) (base + i*FRAME_SIZE), FRAME_SIZE);
1426 jermar 135
 
136
            if (area->sh_info) {
1546 jermar 137
                frame_reference_add(ADDR2PFN(frame));
1426 jermar 138
                btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
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                    (void *) frame, leaf);
140
            }
141
 
1424 jermar 142
        } else {
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            frame = KA2PA(base + i*FRAME_SIZE);
144
        }  
145
    } else if (ALIGN_DOWN(addr, PAGE_SIZE) >= ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
146
        /*
147
         * This is the uninitialized portion of the segment.
148
         * It is not physically present in the ELF image.
149
         * To resolve the situation, a frame must be allocated
150
         * and cleared.
151
         */
152
        frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
153
        memsetb(PA2KA(frame), FRAME_SIZE, 0);
1426 jermar 154
 
155
        if (area->sh_info) {
1546 jermar 156
            frame_reference_add(ADDR2PFN(frame));
1426 jermar 157
            btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
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                (void *) frame, leaf);
159
        }
160
 
1424 jermar 161
    } else {
162
        size_t size;
163
        /*
164
         * The mixed case.
165
         * The lower part is backed by the ELF image and
166
         * the upper part is anonymous memory.
167
         */
168
        size = entry->p_filesz - (i<<PAGE_WIDTH);
169
        frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
170
        memsetb(PA2KA(frame) + size, FRAME_SIZE - size, 0);
171
        memcpy((void *) PA2KA(frame), (void *) (base + i*FRAME_SIZE), size);
1426 jermar 172
 
173
        if (area->sh_info) {
1546 jermar 174
            frame_reference_add(ADDR2PFN(frame));
1426 jermar 175
            btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
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                (void *) frame, leaf);
177
        }
178
 
1424 jermar 179
    }
180
 
1426 jermar 181
    if (area->sh_info)
182
        mutex_unlock(&area->sh_info->lock);
183
 
1424 jermar 184
    page_mapping_insert(AS, addr, frame, as_area_get_flags(area));
1426 jermar 185
    if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
186
        panic("Could not insert used space.\n");
1424 jermar 187
 
188
    return AS_PF_OK;
189
}
190
 
191
/** Free a frame that is backed by the ELF backend.
192
 *
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 * The address space area and page tables must be already locked.
194
 *
195
 * @param area Pointer to the address space area.
196
 * @param page Page that is mapped to frame. Must be aligned to PAGE_SIZE.
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 * @param frame Frame to be released.
198
 *
199
 */
200
void elf_frame_free(as_area_t *area, __address page, __address frame)
201
{
1425 jermar 202
    elf_header_t *elf = area->backend_data.elf;
203
    elf_segment_header_t *entry = area->backend_data.segment;
1424 jermar 204
    __address base;
205
    index_t i;
206
 
207
    ASSERT((page >= entry->p_vaddr) && (page < entry->p_vaddr + entry->p_memsz));
208
    i = (page - entry->p_vaddr) >> PAGE_WIDTH;
209
    base = (__address) (((void *) elf) + entry->p_offset);
210
    ASSERT(ALIGN_UP(base, FRAME_SIZE) == base);
211
 
212
    if (page + PAGE_SIZE < ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
213
        if (entry->p_flags & PF_W) {
214
            /*
215
             * Free the frame with the copy of writable segment data.
216
             */
217
            frame_free(ADDR2PFN(frame));
218
        }
219
    } else {
220
        /*
221
         * The frame is either anonymous memory or the mixed case (i.e. lower
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         * part is backed by the ELF image and the upper is anonymous).
223
         * In any case, a frame needs to be freed.
224
         */
225
        frame_free(ADDR2PFN(frame));
226
    }
227
}
1426 jermar 228
 
229
/** Share ELF image backed address space area.
230
 *
231
 * If the area is writable, then all mapped pages are duplicated in the pagemap.
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 * Otherwise only portions of the area that are not backed by the ELF image
233
 * are put into the pagemap.
234
 *
235
 * The address space and address space area must be locked prior to the call.
236
 *
237
 * @param area Address space area.
238
 */
239
void elf_share(as_area_t *area)
240
{
241
    elf_segment_header_t *entry = area->backend_data.segment;
242
    link_t *cur;
243
    btree_node_t *leaf, *node;
244
    __address start_anon = entry->p_vaddr + entry->p_filesz;
245
 
246
    /*
247
     * Find the node in which to start linear search.
248
     */
249
    if (area->flags & AS_AREA_WRITE) {
250
        node = list_get_instance(area->used_space.leaf_head.next, btree_node_t, leaf_link);
251
    } else {
252
        (void) btree_search(&area->sh_info->pagemap, start_anon, &leaf);
253
        node = btree_leaf_node_left_neighbour(&area->sh_info->pagemap, leaf);
254
        if (!node)
255
            node = leaf;
256
    }
257
 
258
    /*
259
     * Copy used anonymous portions of the area to sh_info's page map.
260
     */
261
    mutex_lock(&area->sh_info->lock);
262
    for (cur = &node->leaf_link; cur != &area->used_space.leaf_head; cur = cur->next) {
263
        int i;
264
 
265
        node = list_get_instance(cur, btree_node_t, leaf_link);
266
 
267
        for (i = 0; i < node->keys; i++) {
268
            __address base = node->key[i];
269
            count_t count = (count_t) node->value[i];
270
            int j;
271
 
272
            /*
273
             * Skip read-only areas of used space that are backed
274
             * by the ELF image.
275
             */
276
            if (!(area->flags & AS_AREA_WRITE))
277
                if (base + count*PAGE_SIZE <= start_anon)
278
                    continue;
279
 
280
            for (j = 0; j < count; j++) {
281
                pte_t *pte;
282
 
283
                /*
284
                 * Skip read-only pages that are backed by the ELF image.
285
                 */
286
                if (!(area->flags & AS_AREA_WRITE))
287
                    if (base + (j + 1)*PAGE_SIZE <= start_anon)
288
                        continue;
289
 
290
                page_table_lock(area->as, false);
291
                pte = page_mapping_find(area->as, base + j*PAGE_SIZE);
292
                ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));
293
                btree_insert(&area->sh_info->pagemap, (base + j*PAGE_SIZE) - area->base,
294
                    (void *) PTE_GET_FRAME(pte), NULL);
295
                page_table_unlock(area->as, false);
1546 jermar 296
                frame_reference_add(ADDR2PFN(PTE_GET_FRAME(pte)));
1426 jermar 297
            }
298
 
299
        }
300
    }
301
    mutex_unlock(&area->sh_info->lock);
302
}