1//===-- llvm/MC/MCObjectDisassembler.h --------------------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file contains the declaration of the MCObjectDisassembler class, which 11// can be used to construct an MCModule and an MC CFG from an ObjectFile. 12// 13//===----------------------------------------------------------------------===// 14 15#ifndef LLVM_MC_MCOBJECTDISASSEMBLER_H 16#define LLVM_MC_MCOBJECTDISASSEMBLER_H 17 18#include "llvm/ADT/ArrayRef.h" 19#include "llvm/ADT/StringRef.h" 20#include "llvm/Support/DataTypes.h" 21#include "llvm/Support/MemoryObject.h" 22#include <vector> 23 24namespace llvm { 25 26namespace object { 27 class ObjectFile; 28 class MachOObjectFile; 29} 30 31class MCBasicBlock; 32class MCDisassembler; 33class MCFunction; 34class MCInstrAnalysis; 35class MCModule; 36class MCObjectSymbolizer; 37 38/// \brief Disassemble an ObjectFile to an MCModule and MCFunctions. 39/// This class builds on MCDisassembler to disassemble whole sections, creating 40/// MCAtom (MCTextAtom for disassembled sections and MCDataAtom for raw data). 41/// It can also be used to create a control flow graph consisting of MCFunctions 42/// and MCBasicBlocks. 43class MCObjectDisassembler { 44public: 45 MCObjectDisassembler(const object::ObjectFile &Obj, 46 const MCDisassembler &Dis, 47 const MCInstrAnalysis &MIA); 48 virtual ~MCObjectDisassembler() {} 49 50 /// \brief Build an MCModule, creating atoms and optionally functions. 51 /// \param withCFG Also build a CFG by adding MCFunctions to the Module. 52 /// If withCFG is false, the MCModule built only contains atoms, representing 53 /// what was found in the object file. If withCFG is true, MCFunctions are 54 /// created, containing MCBasicBlocks. All text atoms are split to form basic 55 /// block atoms, which then each back an MCBasicBlock. 56 MCModule *buildModule(bool withCFG = false); 57 58 MCModule *buildEmptyModule(); 59 60 typedef std::vector<uint64_t> AddressSetTy; 61 /// \name Create a new MCFunction. 62 MCFunction *createFunction(MCModule *Module, uint64_t BeginAddr, 63 AddressSetTy &CallTargets, 64 AddressSetTy &TailCallTargets); 65 66 /// \brief Set the region on which to fallback if disassembly was requested 67 /// somewhere not accessible in the object file. 68 /// This is used for dynamic disassembly (see RawMemoryObject). 69 void setFallbackRegion(std::unique_ptr<MemoryObject> &Region) { 70 FallbackRegion.reset(Region.release()); 71 } 72 73 /// \brief Set the symbolizer to use to get information on external functions. 74 /// Note that this isn't used to do instruction-level symbolization (that is, 75 /// plugged into MCDisassembler), but to symbolize function call targets. 76 void setSymbolizer(MCObjectSymbolizer *ObjectSymbolizer) { 77 MOS = ObjectSymbolizer; 78 } 79 80 /// \brief Get the effective address of the entrypoint, or 0 if there is none. 81 virtual uint64_t getEntrypoint(); 82 83 /// \name Get the addresses of static constructors/destructors in the object. 84 /// The caller is expected to know how to interpret the addresses; 85 /// for example, Mach-O init functions expect 5 arguments, not for ELF. 86 /// The addresses are original object file load addresses, not effective. 87 /// @{ 88 virtual ArrayRef<uint64_t> getStaticInitFunctions(); 89 virtual ArrayRef<uint64_t> getStaticExitFunctions(); 90 /// @} 91 92 /// \name Translation between effective and objectfile load address. 93 /// @{ 94 /// \brief Compute the effective load address, from an objectfile virtual 95 /// address. This is implemented in a format-specific way, to take into 96 /// account things like PIE/ASLR when doing dynamic disassembly. 97 /// For example, on Mach-O this would be done by adding the VM addr slide, 98 /// on glibc ELF by keeping a map between segment load addresses, filled 99 /// using dl_iterate_phdr, etc.. 100 /// In most static situations and in the default impl., this returns \p Addr. 101 virtual uint64_t getEffectiveLoadAddr(uint64_t Addr); 102 103 /// \brief Compute the original load address, as specified in the objectfile. 104 /// This is the inverse of getEffectiveLoadAddr. 105 virtual uint64_t getOriginalLoadAddr(uint64_t EffectiveAddr); 106 /// @} 107 108protected: 109 const object::ObjectFile &Obj; 110 const MCDisassembler &Dis; 111 const MCInstrAnalysis &MIA; 112 MCObjectSymbolizer *MOS; 113 114 /// \brief The fallback memory region, outside the object file. 115 std::unique_ptr<MemoryObject> FallbackRegion; 116 117 /// \brief Return a memory region suitable for reading starting at \p Addr. 118 /// In most cases, this returns a StringRefMemoryObject backed by the 119 /// containing section. When no section was found, this returns the 120 /// FallbackRegion, if it is suitable. 121 /// If it is not, or if there is no fallback region, this returns 0. 122 MemoryObject *getRegionFor(uint64_t Addr); 123 124private: 125 /// \brief Fill \p Module by creating an atom for each section. 126 /// This could be made much smarter, using information like symbols, but also 127 /// format-specific features, like mach-o function_start or data_in_code LCs. 128 void buildSectionAtoms(MCModule *Module); 129 130 /// \brief Enrich \p Module with a CFG consisting of MCFunctions. 131 /// \param Module An MCModule returned by buildModule, with no CFG. 132 /// NOTE: Each MCBasicBlock in a MCFunction is backed by a single MCTextAtom. 133 /// When the CFG is built, contiguous instructions that were previously in a 134 /// single MCTextAtom will be split in multiple basic block atoms. 135 void buildCFG(MCModule *Module); 136 137 MCBasicBlock *getBBAt(MCModule *Module, MCFunction *MCFN, uint64_t BeginAddr, 138 AddressSetTy &CallTargets, 139 AddressSetTy &TailCallTargets); 140}; 141 142class MCMachOObjectDisassembler : public MCObjectDisassembler { 143 const object::MachOObjectFile &MOOF; 144 145 uint64_t VMAddrSlide; 146 uint64_t HeaderLoadAddress; 147 148 // __DATA;__mod_init_func support. 149 llvm::StringRef ModInitContents; 150 // __DATA;__mod_exit_func support. 151 llvm::StringRef ModExitContents; 152 153public: 154 /// \brief Construct a Mach-O specific object disassembler. 155 /// \param VMAddrSlide The virtual address slide applied by dyld. 156 /// \param HeaderLoadAddress The load address of the mach_header for this 157 /// object. 158 MCMachOObjectDisassembler(const object::MachOObjectFile &MOOF, 159 const MCDisassembler &Dis, 160 const MCInstrAnalysis &MIA, uint64_t VMAddrSlide, 161 uint64_t HeaderLoadAddress); 162 163protected: 164 uint64_t getEffectiveLoadAddr(uint64_t Addr) override; 165 uint64_t getOriginalLoadAddr(uint64_t EffectiveAddr) override; 166 uint64_t getEntrypoint() override; 167 168 ArrayRef<uint64_t> getStaticInitFunctions() override; 169 ArrayRef<uint64_t> getStaticExitFunctions() override; 170}; 171 172} 173 174#endif 175