| // Copyright 2013 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef COURGETTE_DISASSEMBLER_ELF_32_H_ |
| #define COURGETTE_DISASSEMBLER_ELF_32_H_ |
| |
| #include <stddef.h> |
| #include <stdint.h> |
| |
| #include "base/macros.h" |
| #include "base/memory/scoped_vector.h" |
| #include "courgette/assembly_program.h" |
| #include "courgette/disassembler.h" |
| #include "courgette/memory_allocator.h" |
| #include "courgette/types_elf.h" |
| |
| namespace courgette { |
| |
| class AssemblyProgram; |
| |
| // A courgette disassembler for 32-bit ELF files. This class is only a |
| // partial implementation. Subclasses implement the |
| // architecture-specific parts of processing 32-bit ELF files. Specifically, |
| // RelToRVA processes entries in ELF relocation table, |
| // ParseRelocationSection verifies the organization of the ELF |
| // relocation table, and ParseRel32RelocsFromSection finds branch |
| // targets by looking for relative jump/call opcodes in the particular |
| // architecture's machine code. |
| class DisassemblerElf32 : public Disassembler { |
| public: |
| // Different instructions encode the target rva differently. This |
| // class encapsulates this behavior. public for use in unit tests. |
| class TypedRVA { |
| public: |
| explicit TypedRVA(RVA rva) : rva_(rva), offset_(static_cast<size_t>(-1)) { |
| } |
| |
| virtual ~TypedRVA() { }; |
| |
| RVA rva() { |
| return rva_; |
| } |
| |
| RVA relative_target() { |
| return relative_target_; |
| } |
| |
| void set_relative_target(RVA relative_target) { |
| relative_target_ = relative_target; |
| } |
| |
| size_t get_offset() { |
| return offset_; |
| } |
| |
| void set_offset(size_t offset) { |
| offset_ = offset; |
| } |
| |
| // Computes the relative jump's offset from the op in p. |
| virtual CheckBool ComputeRelativeTarget(const uint8_t* op_pointer) = 0; |
| |
| // Emits the courgette instruction corresponding to the RVA type. |
| virtual CheckBool EmitInstruction(AssemblyProgram* program, |
| RVA target_rva) = 0; |
| |
| virtual uint16_t op_size() const = 0; |
| |
| static bool IsLessThan(TypedRVA *a, TypedRVA *b) { |
| return a->rva() < b->rva(); |
| } |
| |
| private: |
| const RVA rva_; |
| RVA relative_target_; |
| size_t offset_; |
| }; |
| |
| public: |
| explicit DisassemblerElf32(const void* start, size_t length); |
| |
| virtual ~DisassemblerElf32() { }; |
| |
| virtual ExecutableType kind() = 0; |
| |
| virtual e_machine_values ElfEM() = 0; |
| |
| // Returns 'true' if the buffer appears to point to a valid ELF executable |
| // for 32 bit. If ParseHeader() succeeds, other member |
| // functions may be called. |
| virtual bool ParseHeader(); |
| |
| virtual bool Disassemble(AssemblyProgram* target); |
| |
| // Public for unittests only |
| std::vector<RVA> &Abs32Locations() { return abs32_locations_; } |
| ScopedVector<TypedRVA> &Rel32Locations() { return rel32_locations_; } |
| |
| protected: |
| |
| bool UpdateLength(); |
| |
| // Misc Section Helpers |
| |
| Elf32_Half SectionHeaderCount() const { |
| return section_header_table_size_; |
| } |
| |
| const Elf32_Shdr *SectionHeader(int id) const { |
| assert(id >= 0 && id < SectionHeaderCount()); |
| return section_header_table_ + id; |
| } |
| |
| const uint8_t* SectionBody(int id) const { |
| return OffsetToPointer(SectionHeader(id)->sh_offset); |
| } |
| |
| // Misc Segment Helpers |
| |
| Elf32_Half ProgramSegmentHeaderCount() const { |
| return program_header_table_size_; |
| } |
| |
| const Elf32_Phdr *ProgramSegmentHeader(int id) const { |
| assert(id >= 0 && id < ProgramSegmentHeaderCount()); |
| return program_header_table_ + id; |
| } |
| |
| // Misc address space helpers |
| |
| CheckBool IsValidRVA(RVA rva) const WARN_UNUSED_RESULT; |
| |
| // Convert an ELF relocation struction into an RVA |
| virtual CheckBool RelToRVA(Elf32_Rel rel, RVA* result) |
| const WARN_UNUSED_RESULT = 0; |
| |
| // Returns kNoOffset if there is no file offset corresponding to 'rva'. |
| CheckBool RVAToFileOffset(RVA rva, size_t* result) const WARN_UNUSED_RESULT; |
| |
| RVA FileOffsetToRVA(size_t offset) const WARN_UNUSED_RESULT; |
| |
| CheckBool RVAsToOffsets(std::vector<RVA>* rvas /*in*/, |
| std::vector<size_t>* offsets /*out*/); |
| |
| CheckBool RVAsToOffsets(ScopedVector<TypedRVA>* rvas /*in and out*/); |
| |
| // Parsing Code used to really implement Disassemble |
| |
| CheckBool ParseFile(AssemblyProgram* target) WARN_UNUSED_RESULT; |
| virtual CheckBool ParseRelocationSection( |
| const Elf32_Shdr *section_header, |
| AssemblyProgram* program) WARN_UNUSED_RESULT = 0; |
| CheckBool ParseProgbitsSection( |
| const Elf32_Shdr *section_header, |
| std::vector<size_t>::iterator* current_abs_offset, |
| std::vector<size_t>::iterator end_abs_offset, |
| ScopedVector<TypedRVA>::iterator* current_rel, |
| ScopedVector<TypedRVA>::iterator end_rel, |
| AssemblyProgram* program) WARN_UNUSED_RESULT; |
| CheckBool ParseSimpleRegion(size_t start_file_offset, |
| size_t end_file_offset, |
| AssemblyProgram* program) WARN_UNUSED_RESULT; |
| |
| CheckBool ParseAbs32Relocs() WARN_UNUSED_RESULT; |
| CheckBool CheckSection(RVA rva) WARN_UNUSED_RESULT; |
| CheckBool ParseRel32RelocsFromSections() WARN_UNUSED_RESULT; |
| virtual CheckBool ParseRel32RelocsFromSection( |
| const Elf32_Shdr* section) WARN_UNUSED_RESULT = 0; |
| |
| Elf32_Ehdr *header_; |
| Elf32_Shdr *section_header_table_; |
| Elf32_Half section_header_table_size_; |
| |
| Elf32_Phdr *program_header_table_; |
| Elf32_Half program_header_table_size_; |
| |
| // Section header for default |
| const char *default_string_section_; |
| |
| std::vector<RVA> abs32_locations_; |
| ScopedVector<TypedRVA> rel32_locations_; |
| |
| DISALLOW_COPY_AND_ASSIGN(DisassemblerElf32); |
| }; |
| |
| } // namespace courgette |
| |
| #endif // COURGETTE_DISASSEMBLER_ELF_32_H_ |