1 /* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef ART_RUNTIME_OAT_ELF_FILE_IMPL_H_ 18 #define ART_RUNTIME_OAT_ELF_FILE_IMPL_H_ 19 20 #include <map> 21 #include <memory> 22 #include <type_traits> 23 #include <vector> 24 25 #include "base/macros.h" 26 #include "base/mem_map.h" 27 #include "elf/elf_utils.h" 28 29 namespace art HIDDEN { 30 31 template <typename ElfTypes> 32 class ElfFileImpl { 33 public: 34 using Elf_Addr = typename ElfTypes::Addr; 35 using Elf_Off = typename ElfTypes::Off; 36 using Elf_Half = typename ElfTypes::Half; 37 using Elf_Word = typename ElfTypes::Word; 38 using Elf_Sword = typename ElfTypes::Sword; 39 using Elf_Ehdr = typename ElfTypes::Ehdr; 40 using Elf_Shdr = typename ElfTypes::Shdr; 41 using Elf_Sym = typename ElfTypes::Sym; 42 using Elf_Rel = typename ElfTypes::Rel; 43 using Elf_Rela = typename ElfTypes::Rela; 44 using Elf_Phdr = typename ElfTypes::Phdr; 45 using Elf_Dyn = typename ElfTypes::Dyn; 46 47 static ElfFileImpl* Open(File* file, 48 bool writable, 49 bool program_header_only, 50 bool low_4gb, 51 /*out*/std::string* error_msg); 52 static ElfFileImpl* Open(File* file, 53 int mmap_prot, 54 int mmap_flags, 55 bool low_4gb, 56 /*out*/std::string* error_msg); 57 ~ElfFileImpl(); 58 GetFilePath()59 const std::string& GetFilePath() const { 60 return file_path_; 61 } 62 GetBaseAddress()63 uint8_t* GetBaseAddress() const { 64 return base_address_; 65 } 66 Begin()67 uint8_t* Begin() const { 68 return map_.Begin(); 69 } 70 End()71 uint8_t* End() const { 72 return map_.End(); 73 } 74 Size()75 size_t Size() const { 76 return map_.Size(); 77 } 78 79 Elf_Ehdr& GetHeader() const; 80 81 Elf_Word GetProgramHeaderNum() const; 82 Elf_Phdr* GetProgramHeader(Elf_Word) const; 83 84 Elf_Word GetSectionHeaderNum() const; 85 Elf_Shdr* GetSectionHeader(Elf_Word) const; 86 Elf_Shdr* FindSectionByType(Elf_Word type) const; 87 Elf_Shdr* FindSectionByName(const std::string& name) const; 88 89 Elf_Shdr* GetSectionNameStringSection() const; 90 91 // Find .dynsym using .hash for more efficient lookup than FindSymbolAddress. 92 const uint8_t* FindDynamicSymbolAddress(const std::string& symbol_name) const; 93 94 static bool IsSymbolSectionType(Elf_Word section_type); 95 Elf_Word GetSymbolNum(Elf_Shdr&) const; 96 Elf_Sym* GetSymbol(Elf_Word section_type, Elf_Word i) const; 97 98 // Find address of symbol in specified table, returning 0 if it is 99 // not found. See FindSymbolByName for an explanation of build_map. 100 Elf_Addr FindSymbolAddress(Elf_Word section_type, 101 const std::string& symbol_name, 102 bool build_map); 103 104 // Lookup a string given string section and offset. Returns null for special 0 offset. 105 const char* GetString(Elf_Shdr&, Elf_Word) const; 106 107 Elf_Word GetDynamicNum() const; 108 Elf_Dyn& GetDynamic(Elf_Word) const; 109 110 Elf_Word GetRelNum(Elf_Shdr&) const; 111 Elf_Rel& GetRel(Elf_Shdr&, Elf_Word) const; 112 113 Elf_Word GetRelaNum(Elf_Shdr&) const; 114 Elf_Rela& GetRela(Elf_Shdr&, Elf_Word) const; 115 116 // Retrieves the expected size when the file is loaded at runtime. Returns true if successful. 117 bool GetLoadedSize(size_t* size, std::string* error_msg) const; 118 119 // Get the alignment of the first loadable program segment. Return 0 if no loadable segment found. 120 size_t GetElfSegmentAlignmentFromFile() const; 121 122 // Load segments into memory based on PT_LOAD program headers. 123 // executable is true at run time, false at compile time. 124 bool Load(File* file, 125 bool executable, 126 bool low_4gb, 127 /*inout*/MemMap* reservation, 128 /*out*/std::string* error_msg); 129 130 bool Strip(File* file, std::string* error_msg); 131 132 private: 133 ElfFileImpl(File* file, bool writable, bool program_header_only); 134 135 bool GetLoadedAddressRange(/*out*/uint8_t** vaddr_begin, 136 /*out*/size_t* vaddr_size, 137 /*out*/std::string* error_msg) const; 138 139 bool Setup(File* file, int prot, int flags, bool low_4gb, std::string* error_msg); 140 141 bool SetMap(File* file, MemMap&& map, std::string* error_msg); 142 143 uint8_t* GetProgramHeadersStart() const; 144 uint8_t* GetSectionHeadersStart() const; 145 Elf_Phdr& GetDynamicProgramHeader() const; 146 Elf_Dyn* GetDynamicSectionStart() const; 147 Elf_Sym* GetSymbolSectionStart(Elf_Word section_type) const; 148 const char* GetStringSectionStart(Elf_Word section_type) const; 149 Elf_Rel* GetRelSectionStart(Elf_Shdr&) const; 150 Elf_Rela* GetRelaSectionStart(Elf_Shdr&) const; 151 Elf_Word* GetHashSectionStart() const; 152 Elf_Word GetHashBucketNum() const; 153 Elf_Word GetHashChainNum() const; 154 Elf_Word GetHashBucket(size_t i, bool* ok) const; 155 Elf_Word GetHashChain(size_t i, bool* ok) const; 156 157 using SymbolTable = std::map<std::string, Elf_Sym*>; 158 SymbolTable** GetSymbolTable(Elf_Word section_type); 159 160 bool ValidPointer(const uint8_t* start) const; 161 162 const Elf_Sym* FindDynamicSymbol(const std::string& symbol_name) const; 163 164 // Check that certain sections and their dependencies exist. 165 bool CheckSectionsExist(File* file, std::string* error_msg) const; 166 167 // Check that the link of the first section links to the second section. 168 bool CheckSectionsLinked(const uint8_t* source, const uint8_t* target) const; 169 170 // Check whether the offset is in range, and set to target to Begin() + offset if OK. 171 bool CheckAndSet(Elf32_Off offset, const char* label, uint8_t** target, std::string* error_msg); 172 173 // Find symbol in specified table, returning null if it is not found. 174 // 175 // If build_map is true, builds a map to speed repeated access. The 176 // map does not included untyped symbol values (aka STT_NOTYPE) 177 // since they can contain duplicates. If build_map is false, the map 178 // will be used if it was already created. Typically build_map 179 // should be set unless only a small number of symbols will be 180 // looked up. 181 Elf_Sym* FindSymbolByName(Elf_Word section_type, 182 const std::string& symbol_name, 183 bool build_map); 184 185 Elf_Phdr* FindProgamHeaderByType(Elf_Word type) const; 186 187 Elf_Dyn* FindDynamicByType(Elf_Sword type) const; 188 Elf_Word FindDynamicValueByType(Elf_Sword type) const; 189 190 // Lookup a string by section type. Returns null for special 0 offset. 191 const char* GetString(Elf_Word section_type, Elf_Word) const; 192 193 const std::string file_path_; 194 const bool writable_; 195 const bool program_header_only_; 196 197 // ELF header mapping. If program_header_only_ is false, will 198 // actually point to the entire elf file. 199 MemMap map_; 200 Elf_Ehdr* header_; 201 std::vector<MemMap> segments_; 202 203 // Pointer to start of first PT_LOAD program segment after Load() 204 // when program_header_only_ is true. 205 uint8_t* base_address_; 206 207 // The program header should always available but use GetProgramHeadersStart() to be sure. 208 uint8_t* program_headers_start_; 209 210 // Conditionally available values. Use accessors to ensure they exist if they are required. 211 uint8_t* section_headers_start_; 212 Elf_Phdr* dynamic_program_header_; 213 Elf_Dyn* dynamic_section_start_; 214 Elf_Sym* symtab_section_start_; 215 Elf_Sym* dynsym_section_start_; 216 char* strtab_section_start_; 217 char* dynstr_section_start_; 218 Elf_Word* hash_section_start_; 219 220 SymbolTable* symtab_symbol_table_; 221 SymbolTable* dynsym_symbol_table_; 222 223 DISALLOW_COPY_AND_ASSIGN(ElfFileImpl); 224 }; 225 226 } // namespace art 227 228 #endif // ART_RUNTIME_OAT_ELF_FILE_IMPL_H_ 229