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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 | |||
1702 | cejka | 29 | /** @addtogroup genericmm |
30 | * @{ |
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31 | */ |
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32 | |||
1424 | jermar | 33 | /** |
1702 | cejka | 34 | * @file |
1424 | jermar | 35 | * @brief Backend for anonymous memory address space areas. |
36 | * |
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37 | */ |
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38 | |||
39 | #include <mm/as.h> |
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40 | #include <mm/page.h> |
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41 | #include <genarch/mm/page_pt.h> |
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42 | #include <genarch/mm/page_ht.h> |
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43 | #include <mm/frame.h> |
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44 | #include <mm/slab.h> |
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45 | #include <synch/mutex.h> |
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46 | #include <adt/list.h> |
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47 | #include <adt/btree.h> |
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48 | #include <errno.h> |
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49 | #include <arch/types.h> |
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50 | #include <typedefs.h> |
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51 | #include <align.h> |
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52 | #include <arch.h> |
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53 | |||
54 | static int anon_page_fault(as_area_t *area, __address addr, pf_access_t access); |
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55 | static void anon_frame_free(as_area_t *area, __address page, __address frame); |
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56 | static void anon_share(as_area_t *area); |
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57 | |||
58 | mem_backend_t anon_backend = { |
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59 | .page_fault = anon_page_fault, |
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60 | .frame_free = anon_frame_free, |
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61 | .share = anon_share |
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62 | }; |
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63 | |||
64 | /** Service a page fault in the anonymous memory address space area. |
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65 | * |
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66 | * The address space area and page tables must be already locked. |
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67 | * |
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68 | * @param area Pointer to the address space area. |
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69 | * @param addr Faulting virtual address. |
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70 | * @param access Access mode that caused the fault (i.e. read/write/exec). |
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71 | * |
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72 | * @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e. serviced). |
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73 | */ |
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74 | int anon_page_fault(as_area_t *area, __address addr, pf_access_t access) |
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75 | { |
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76 | __address frame; |
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77 | |||
78 | if (!as_area_check_access(area, access)) |
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79 | return AS_PF_FAULT; |
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80 | |||
81 | if (area->sh_info) { |
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82 | btree_node_t *leaf; |
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83 | |||
84 | /* |
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85 | * The area is shared, chances are that the mapping can be found |
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86 | * in the pagemap of the address space area share info structure. |
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87 | * In the case that the pagemap does not contain the respective |
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88 | * mapping, a new frame is allocated and the mapping is created. |
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89 | */ |
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90 | mutex_lock(&area->sh_info->lock); |
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91 | frame = (__address) btree_search(&area->sh_info->pagemap, |
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92 | ALIGN_DOWN(addr, PAGE_SIZE) - area->base, &leaf); |
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93 | if (!frame) { |
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94 | bool allocate = true; |
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95 | int i; |
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96 | |||
97 | /* |
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98 | * Zero can be returned as a valid frame address. |
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99 | * Just a small workaround. |
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100 | */ |
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101 | for (i = 0; i < leaf->keys; i++) { |
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102 | if (leaf->key[i] == ALIGN_DOWN(addr, PAGE_SIZE)) { |
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103 | allocate = false; |
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104 | break; |
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105 | } |
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106 | } |
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107 | if (allocate) { |
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108 | frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0)); |
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109 | memsetb(PA2KA(frame), FRAME_SIZE, 0); |
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110 | |||
111 | /* |
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112 | * Insert the address of the newly allocated frame to the pagemap. |
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113 | */ |
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114 | btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base, (void *) frame, leaf); |
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115 | } |
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116 | } |
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1545 | jermar | 117 | frame_reference_add(ADDR2PFN(frame)); |
1424 | jermar | 118 | mutex_unlock(&area->sh_info->lock); |
119 | } else { |
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120 | |||
121 | /* |
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122 | * In general, there can be several reasons that |
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123 | * can have caused this fault. |
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124 | * |
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125 | * - non-existent mapping: the area is an anonymous |
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126 | * area (e.g. heap or stack) and so far has not been |
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127 | * allocated a frame for the faulting page |
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128 | * |
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129 | * - non-present mapping: another possibility, |
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130 | * currently not implemented, would be frame |
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131 | * reuse; when this becomes a possibility, |
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132 | * do not forget to distinguish between |
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133 | * the different causes |
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134 | */ |
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135 | frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0)); |
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136 | memsetb(PA2KA(frame), FRAME_SIZE, 0); |
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137 | } |
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138 | |||
139 | /* |
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140 | * Map 'page' to 'frame'. |
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141 | * Note that TLB shootdown is not attempted as only new information is being |
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142 | * inserted into page tables. |
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143 | */ |
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144 | page_mapping_insert(AS, addr, frame, as_area_get_flags(area)); |
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145 | if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1)) |
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146 | panic("Could not insert used space.\n"); |
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147 | |||
148 | return AS_PF_OK; |
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149 | } |
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150 | |||
151 | /** Free a frame that is backed by the anonymous memory backend. |
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152 | * |
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153 | * The address space area and page tables must be already locked. |
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154 | * |
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155 | * @param area Ignored. |
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156 | * @param page Ignored. |
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157 | * @param frame Frame to be released. |
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158 | */ |
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159 | void anon_frame_free(as_area_t *area, __address page, __address frame) |
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160 | { |
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161 | frame_free(ADDR2PFN(frame)); |
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162 | } |
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163 | |||
164 | /** Share the anonymous address space area. |
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165 | * |
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166 | * Sharing of anonymous area is done by duplicating its entire mapping |
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167 | * to the pagemap. Page faults will primarily search for frames there. |
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168 | * |
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1426 | jermar | 169 | * The address space and address space area must be already locked. |
1424 | jermar | 170 | * |
171 | * @param area Address space area to be shared. |
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172 | */ |
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173 | void anon_share(as_area_t *area) |
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174 | { |
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175 | link_t *cur; |
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176 | |||
177 | /* |
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178 | * Copy used portions of the area to sh_info's page map. |
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179 | */ |
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180 | mutex_lock(&area->sh_info->lock); |
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181 | for (cur = area->used_space.leaf_head.next; cur != &area->used_space.leaf_head; cur = cur->next) { |
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182 | btree_node_t *node; |
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183 | int i; |
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184 | |||
185 | node = list_get_instance(cur, btree_node_t, leaf_link); |
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186 | for (i = 0; i < node->keys; i++) { |
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187 | __address base = node->key[i]; |
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188 | count_t count = (count_t) node->value[i]; |
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189 | int j; |
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190 | |||
191 | for (j = 0; j < count; j++) { |
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192 | pte_t *pte; |
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193 | |||
194 | page_table_lock(area->as, false); |
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195 | pte = page_mapping_find(area->as, base + j*PAGE_SIZE); |
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196 | ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte)); |
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197 | btree_insert(&area->sh_info->pagemap, (base + j*PAGE_SIZE) - area->base, |
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198 | (void *) PTE_GET_FRAME(pte), NULL); |
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199 | page_table_unlock(area->as, false); |
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1545 | jermar | 200 | frame_reference_add(ADDR2PFN(PTE_GET_FRAME(pte))); |
1424 | jermar | 201 | } |
202 | |||
203 | } |
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204 | } |
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205 | mutex_unlock(&area->sh_info->lock); |
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206 | } |
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1702 | cejka | 207 | |
208 | /** @} |
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209 | */ |
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210 |