1 // Copyright (c) 2013 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef CRAZY_LINKER_ELF_RELOCATIONS_H 6 #define CRAZY_LINKER_ELF_RELOCATIONS_H 7 8 #include <string.h> 9 10 #include "elf_traits.h" 11 12 namespace crazy { 13 14 class ElfSymbols; 15 class ElfView; 16 class Error; 17 18 // An ElfRelocations instance holds information about relocations in a mapped 19 // ELF binary. 20 class ElfRelocations { 21 public: 22 ElfRelocations() { ::memset(this, 0, sizeof(*this)); } 23 ~ElfRelocations() {} 24 25 bool Init(const ElfView* view, Error* error); 26 27 // Abstract class used to resolve symbol names into addresses. 28 // Callers of ::ApplyAll() should pass the address of a derived class 29 // that properly implements the Lookup() method. 30 class SymbolResolver { 31 public: 32 SymbolResolver() {} 33 ~SymbolResolver() {} 34 virtual void* Lookup(const char* symbol_name) = 0; 35 }; 36 37 // Apply all relocations to the target mapped ELF binary. Must be called 38 // after Init(). 39 // |symbols| maps to the symbol entries for the target library only. 40 // |resolver| can resolve symbols out of the current library. 41 // On error, return false and set |error| message. 42 bool ApplyAll(const ElfSymbols* symbols, 43 SymbolResolver* resolver, 44 Error* error); 45 46 // This function is used to adjust relocated addresses in a copy of an 47 // existing section of an ELF binary. I.e. |src_addr|...|src_addr + size| 48 // must be inside the mapped ELF binary, this function will first copy its 49 // content into |dst_addr|...|dst_addr + size|, then adjust all relocated 50 // addresses inside the destination section as if it was loaded/mapped 51 // at |map_addr|...|map_addr + size|. Only relative relocations are processed, 52 // symbolic ones are ignored. 53 void CopyAndRelocate(size_t src_addr, 54 size_t dst_addr, 55 size_t map_addr, 56 size_t size); 57 58 private: 59 bool ResolveSymbol(unsigned rel_type, 60 unsigned rel_symbol, 61 const ElfSymbols* symbols, 62 SymbolResolver* resolver, 63 ELF::Addr reloc, 64 ELF::Addr* sym_addr, 65 Error* error); 66 bool ApplyRelaReloc(const ELF::Rela* rela, 67 ELF::Addr sym_addr, 68 bool resolved, 69 Error* error); 70 bool ApplyRelReloc(const ELF::Rel* rel, 71 ELF::Addr sym_addr, 72 bool resolved, 73 Error* error); 74 bool ApplyRelaRelocs(const ELF::Rela* relocs, 75 size_t relocs_count, 76 const ElfSymbols* symbols, 77 SymbolResolver* resolver, 78 Error* error); 79 bool ApplyRelRelocs(const ELF::Rel* relocs, 80 size_t relocs_count, 81 const ElfSymbols* symbols, 82 SymbolResolver* resolver, 83 Error* error); 84 void AdjustRelocation(ELF::Word rel_type, 85 ELF::Addr src_reloc, 86 size_t dst_delta, 87 size_t map_delta); 88 void RelocateRela(size_t src_addr, 89 size_t dst_addr, 90 size_t map_addr, 91 size_t size); 92 void RelocateRel(size_t src_addr, 93 size_t dst_addr, 94 size_t map_addr, 95 size_t size); 96 97 #if defined(__mips__) 98 bool RelocateMipsGot(const ElfSymbols* symbols, 99 SymbolResolver* resolver, 100 Error* error); 101 #endif 102 103 const ELF::Phdr* phdr_; 104 size_t phdr_count_; 105 size_t load_bias_; 106 107 ELF::Addr relocations_type_; 108 ELF::Addr plt_relocations_; 109 size_t plt_relocations_size_; 110 ELF::Addr* plt_got_; 111 112 ELF::Addr relocations_; 113 size_t relocations_size_; 114 115 #if defined(__mips__) 116 // MIPS-specific relocation fields. 117 ELF::Word mips_symtab_count_; 118 ELF::Word mips_local_got_count_; 119 ELF::Word mips_gotsym_; 120 #endif 121 122 bool has_text_relocations_; 123 bool has_symbolic_; 124 }; 125 126 } // namespace crazy 127 128 #endif // CRAZY_LINKER_ELF_RELOCATIONS_H 129
