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1424 | jermar | 1 | /* |
2 | * Copyright (C) 2006 Jakub Jermar |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
29 | /** |
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30 | * @file backend_elf.c |
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31 | * @brief Backend for address space areas backed by an ELF image. |
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32 | */ |
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33 | |||
34 | #include <elf.h> |
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35 | #include <debug.h> |
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36 | #include <arch/types.h> |
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37 | #include <typedefs.h> |
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38 | #include <mm/as.h> |
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39 | #include <mm/frame.h> |
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40 | #include <mm/slab.h> |
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1426 | jermar | 41 | #include <mm/page.h> |
42 | #include <genarch/mm/page_pt.h> |
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43 | #include <genarch/mm/page_ht.h> |
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1424 | jermar | 44 | #include <align.h> |
45 | #include <memstr.h> |
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46 | #include <macros.h> |
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47 | #include <arch.h> |
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48 | |||
49 | static int elf_page_fault(as_area_t *area, __address addr, pf_access_t access); |
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50 | static void elf_frame_free(as_area_t *area, __address page, __address frame); |
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1426 | jermar | 51 | static void elf_share(as_area_t *area); |
1424 | jermar | 52 | |
53 | mem_backend_t elf_backend = { |
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54 | .page_fault = elf_page_fault, |
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55 | .frame_free = elf_frame_free, |
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1426 | jermar | 56 | .share = elf_share |
1424 | jermar | 57 | }; |
58 | |||
59 | /** Service a page fault in the ELF backend address space area. |
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60 | * |
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61 | * The address space area and page tables must be already locked. |
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62 | * |
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63 | * @param area Pointer to the address space area. |
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64 | * @param addr Faulting virtual address. |
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65 | * @param access Access mode that caused the fault (i.e. read/write/exec). |
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66 | * |
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67 | * @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e. serviced). |
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68 | */ |
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69 | int elf_page_fault(as_area_t *area, __address addr, pf_access_t access) |
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70 | { |
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1425 | jermar | 71 | elf_header_t *elf = area->backend_data.elf; |
72 | elf_segment_header_t *entry = area->backend_data.segment; |
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1426 | jermar | 73 | btree_node_t *leaf; |
1424 | jermar | 74 | __address base, frame; |
75 | index_t i; |
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76 | |||
77 | if (!as_area_check_access(area, access)) |
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78 | return AS_PF_FAULT; |
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79 | |||
80 | ASSERT((addr >= entry->p_vaddr) && (addr < entry->p_vaddr + entry->p_memsz)); |
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81 | i = (addr - entry->p_vaddr) >> PAGE_WIDTH; |
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82 | base = (__address) (((void *) elf) + entry->p_offset); |
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83 | ASSERT(ALIGN_UP(base, FRAME_SIZE) == base); |
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1426 | jermar | 84 | |
85 | if (area->sh_info) { |
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86 | bool found = false; |
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87 | |||
88 | /* |
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89 | * The address space area is shared. |
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90 | */ |
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91 | |||
92 | mutex_lock(&area->sh_info->lock); |
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93 | frame = (__address) btree_search(&area->sh_info->pagemap, |
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94 | ALIGN_DOWN(addr, PAGE_SIZE) - area->base, &leaf); |
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95 | if (!frame) { |
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96 | int i; |
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97 | |||
98 | /* |
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99 | * Workaround for valid NULL address. |
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100 | */ |
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101 | |||
102 | for (i = 0; i < leaf->keys; i++) { |
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103 | if (leaf->key[i] == ALIGN_DOWN(addr, PAGE_SIZE)) { |
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104 | found = true; |
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105 | break; |
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106 | } |
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107 | } |
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108 | } |
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109 | if (frame || found) { |
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1546 | jermar | 110 | frame_reference_add(ADDR2PFN(frame)); |
1426 | jermar | 111 | page_mapping_insert(AS, addr, frame, as_area_get_flags(area)); |
112 | if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1)) |
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113 | panic("Could not insert used space.\n"); |
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114 | mutex_unlock(&area->sh_info->lock); |
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115 | return AS_PF_OK; |
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116 | } |
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117 | } |
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1424 | jermar | 118 | |
1426 | jermar | 119 | /* |
120 | * The area is either not shared or the pagemap does not contain the mapping. |
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121 | */ |
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122 | |||
1424 | jermar | 123 | if (ALIGN_DOWN(addr, PAGE_SIZE) + PAGE_SIZE < entry->p_vaddr + entry->p_filesz) { |
124 | /* |
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125 | * Initialized portion of the segment. The memory is backed |
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126 | * directly by the content of the ELF image. Pages are |
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127 | * only copied if the segment is writable so that there |
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128 | * can be more instantions of the same memory ELF image |
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129 | * used at a time. Note that this could be later done |
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130 | * as COW. |
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131 | */ |
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132 | if (entry->p_flags & PF_W) { |
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133 | frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0)); |
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134 | memcpy((void *) PA2KA(frame), (void *) (base + i*FRAME_SIZE), FRAME_SIZE); |
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1426 | jermar | 135 | |
136 | if (area->sh_info) { |
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1546 | jermar | 137 | frame_reference_add(ADDR2PFN(frame)); |
1426 | jermar | 138 | btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base, |
139 | (void *) frame, leaf); |
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140 | } |
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141 | |||
1424 | jermar | 142 | } else { |
143 | frame = KA2PA(base + i*FRAME_SIZE); |
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144 | } |
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145 | } else if (ALIGN_DOWN(addr, PAGE_SIZE) >= ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) { |
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146 | /* |
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147 | * This is the uninitialized portion of the segment. |
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148 | * It is not physically present in the ELF image. |
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149 | * To resolve the situation, a frame must be allocated |
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150 | * and cleared. |
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151 | */ |
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152 | frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0)); |
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153 | memsetb(PA2KA(frame), FRAME_SIZE, 0); |
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1426 | jermar | 154 | |
155 | if (area->sh_info) { |
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1546 | jermar | 156 | frame_reference_add(ADDR2PFN(frame)); |
1426 | jermar | 157 | btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base, |
158 | (void *) frame, leaf); |
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159 | } |
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160 | |||
1424 | jermar | 161 | } else { |
162 | size_t size; |
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163 | /* |
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164 | * The mixed case. |
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165 | * The lower part is backed by the ELF image and |
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166 | * the upper part is anonymous memory. |
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167 | */ |
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168 | size = entry->p_filesz - (i<<PAGE_WIDTH); |
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169 | frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0)); |
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170 | memsetb(PA2KA(frame) + size, FRAME_SIZE - size, 0); |
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171 | memcpy((void *) PA2KA(frame), (void *) (base + i*FRAME_SIZE), size); |
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1426 | jermar | 172 | |
173 | if (area->sh_info) { |
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1546 | jermar | 174 | frame_reference_add(ADDR2PFN(frame)); |
1426 | jermar | 175 | btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base, |
176 | (void *) frame, leaf); |
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177 | } |
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178 | |||
1424 | jermar | 179 | } |
180 | |||
1426 | jermar | 181 | if (area->sh_info) |
182 | mutex_unlock(&area->sh_info->lock); |
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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"); |
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1424 | jermar | 187 | |
188 | return AS_PF_OK; |
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189 | } |
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190 | |||
191 | /** Free a frame that is backed by the ELF backend. |
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192 | * |
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193 | * The address space area and page tables must be already locked. |
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194 | * |
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195 | * @param area Pointer to the address space area. |
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196 | * @param page Page that is mapped to frame. Must be aligned to PAGE_SIZE. |
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197 | * @param frame Frame to be released. |
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198 | * |
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199 | */ |
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200 | void elf_frame_free(as_area_t *area, __address page, __address frame) |
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201 | { |
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1425 | jermar | 202 | elf_header_t *elf = area->backend_data.elf; |
203 | elf_segment_header_t *entry = area->backend_data.segment; |
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1424 | jermar | 204 | __address base; |
205 | index_t i; |
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206 | |||
207 | ASSERT((page >= entry->p_vaddr) && (page < entry->p_vaddr + entry->p_memsz)); |
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208 | i = (page - entry->p_vaddr) >> PAGE_WIDTH; |
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209 | base = (__address) (((void *) elf) + entry->p_offset); |
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210 | ASSERT(ALIGN_UP(base, FRAME_SIZE) == base); |
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211 | |||
212 | if (page + PAGE_SIZE < ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) { |
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213 | if (entry->p_flags & PF_W) { |
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214 | /* |
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215 | * Free the frame with the copy of writable segment data. |
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216 | */ |
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217 | frame_free(ADDR2PFN(frame)); |
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218 | } |
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219 | } else { |
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220 | /* |
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221 | * The frame is either anonymous memory or the mixed case (i.e. lower |
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222 | * part is backed by the ELF image and the upper is anonymous). |
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223 | * In any case, a frame needs to be freed. |
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224 | */ |
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225 | frame_free(ADDR2PFN(frame)); |
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226 | } |
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227 | } |
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1426 | jermar | 228 | |
229 | /** Share ELF image backed address space area. |
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230 | * |
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231 | * If the area is writable, then all mapped pages are duplicated in the pagemap. |
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232 | * Otherwise only portions of the area that are not backed by the ELF image |
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233 | * are put into the pagemap. |
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234 | * |
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235 | * The address space and address space area must be locked prior to the call. |
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236 | * |
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237 | * @param area Address space area. |
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238 | */ |
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239 | void elf_share(as_area_t *area) |
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240 | { |
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241 | elf_segment_header_t *entry = area->backend_data.segment; |
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242 | link_t *cur; |
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243 | btree_node_t *leaf, *node; |
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244 | __address start_anon = entry->p_vaddr + entry->p_filesz; |
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245 | |||
246 | /* |
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247 | * Find the node in which to start linear search. |
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248 | */ |
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249 | if (area->flags & AS_AREA_WRITE) { |
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250 | node = list_get_instance(area->used_space.leaf_head.next, btree_node_t, leaf_link); |
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251 | } else { |
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252 | (void) btree_search(&area->sh_info->pagemap, start_anon, &leaf); |
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253 | node = btree_leaf_node_left_neighbour(&area->sh_info->pagemap, leaf); |
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254 | if (!node) |
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255 | node = leaf; |
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256 | } |
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257 | |||
258 | /* |
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259 | * Copy used anonymous portions of the area to sh_info's page map. |
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260 | */ |
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261 | mutex_lock(&area->sh_info->lock); |
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262 | for (cur = &node->leaf_link; cur != &area->used_space.leaf_head; cur = cur->next) { |
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263 | int i; |
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264 | |||
265 | node = list_get_instance(cur, btree_node_t, leaf_link); |
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266 | |||
267 | for (i = 0; i < node->keys; i++) { |
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268 | __address base = node->key[i]; |
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269 | count_t count = (count_t) node->value[i]; |
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270 | int j; |
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271 | |||
272 | /* |
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273 | * Skip read-only areas of used space that are backed |
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274 | * by the ELF image. |
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275 | */ |
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276 | if (!(area->flags & AS_AREA_WRITE)) |
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277 | if (base + count*PAGE_SIZE <= start_anon) |
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278 | continue; |
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279 | |||
280 | for (j = 0; j < count; j++) { |
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281 | pte_t *pte; |
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282 | |||
283 | /* |
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284 | * Skip read-only pages that are backed by the ELF image. |
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285 | */ |
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286 | if (!(area->flags & AS_AREA_WRITE)) |
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287 | if (base + (j + 1)*PAGE_SIZE <= start_anon) |
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288 | continue; |
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289 | |||
290 | page_table_lock(area->as, false); |
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291 | pte = page_mapping_find(area->as, base + j*PAGE_SIZE); |
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292 | ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte)); |
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293 | btree_insert(&area->sh_info->pagemap, (base + j*PAGE_SIZE) - area->base, |
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294 | (void *) PTE_GET_FRAME(pte), NULL); |
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295 | page_table_unlock(area->as, false); |
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1546 | jermar | 296 | frame_reference_add(ADDR2PFN(PTE_GET_FRAME(pte))); |
1426 | jermar | 297 | } |
298 | |||
299 | } |
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300 | } |
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301 | mutex_unlock(&area->sh_info->lock); |
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302 | } |