runtime/elf_file_impl.h - platform/art - Gitiles

 /*
  * Copyright (C) 2012 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #ifndef ART_RUNTIME_ELF_FILE_IMPL_H_
 #define ART_RUNTIME_ELF_FILE_IMPL_H_

 #include <map>
 #include <memory>
 #include <type_traits>
 #include <vector>

 // Explicitly include our own elf.h to avoid Linux and other dependencies.
 #include "./elf.h"
 #include "mem_map.h"

 namespace art {

 extern "C" {
   struct JITCodeEntry;
 }

 template <typename ElfTypes>
 class ElfFileImpl {
  public:
   using Elf_Addr = typename ElfTypes::Addr;
   using Elf_Off = typename ElfTypes::Off;
   using Elf_Half = typename ElfTypes::Half;
   using Elf_Word = typename ElfTypes::Word;
   using Elf_Sword = typename ElfTypes::Sword;
   using Elf_Ehdr = typename ElfTypes::Ehdr;
   using Elf_Shdr = typename ElfTypes::Shdr;
   using Elf_Sym = typename ElfTypes::Sym;
   using Elf_Rel = typename ElfTypes::Rel;
   using Elf_Rela = typename ElfTypes::Rela;
   using Elf_Phdr = typename ElfTypes::Phdr;
   using Elf_Dyn = typename ElfTypes::Dyn;

   static ElfFileImpl* Open(File* file, bool writable, bool program_header_only,
                            std::string* error_msg, uint8_t* requested_base = nullptr);
   static ElfFileImpl* Open(File* file, int mmap_prot, int mmap_flags, std::string* error_msg);
   ~ElfFileImpl();

   const File& GetFile() const {
     return *file_;
   }

   uint8_t* Begin() const {
     return map_->Begin();
   }

   uint8_t* End() const {
     return map_->End();
   }

   size_t Size() const {
     return map_->Size();
   }

   Elf_Ehdr& GetHeader() const;

   Elf_Word GetProgramHeaderNum() const;
   Elf_Phdr* GetProgramHeader(Elf_Word) const;

   Elf_Word GetSectionHeaderNum() const;
   Elf_Shdr* GetSectionHeader(Elf_Word) const;
   Elf_Shdr* FindSectionByType(Elf_Word type) const;
   Elf_Shdr* FindSectionByName(const std::string& name) const;

   Elf_Shdr* GetSectionNameStringSection() const;

   // Find .dynsym using .hash for more efficient lookup than FindSymbolAddress.
   const uint8_t* FindDynamicSymbolAddress(const std::string& symbol_name) const;

   static bool IsSymbolSectionType(Elf_Word section_type);
   Elf_Word GetSymbolNum(Elf_Shdr&) const;
   Elf_Sym* GetSymbol(Elf_Word section_type, Elf_Word i) const;

   // Find address of symbol in specified table, returning 0 if it is
   // not found. See FindSymbolByName for an explanation of build_map.
   Elf_Addr FindSymbolAddress(Elf_Word section_type,
                              const std::string& symbol_name,
                              bool build_map);

   // Lookup a string given string section and offset. Returns null for special 0 offset.
   const char* GetString(Elf_Shdr&, Elf_Word) const;

   Elf_Word GetDynamicNum() const;
   Elf_Dyn& GetDynamic(Elf_Word) const;

   Elf_Word GetRelNum(Elf_Shdr&) const;
   Elf_Rel& GetRel(Elf_Shdr&, Elf_Word) const;

   Elf_Word GetRelaNum(Elf_Shdr&) const;
   Elf_Rela& GetRela(Elf_Shdr&, Elf_Word) const;

   // Retrieves the expected size when the file is loaded at runtime. Returns true if successful.
   bool GetLoadedSize(size_t* size, std::string* error_msg) const;

   // Load segments into memory based on PT_LOAD program headers.
   // executable is true at run time, false at compile time.
   bool Load(bool executable, std::string* error_msg);

   bool Fixup(Elf_Addr base_address);
   bool FixupDynamic(Elf_Addr base_address);
   bool FixupSectionHeaders(Elf_Addr base_address);
   bool FixupProgramHeaders(Elf_Addr base_address);
   bool FixupSymbols(Elf_Addr base_address, bool dynamic);
   bool FixupRelocations(Elf_Addr base_address);
   bool FixupDebugSections(Elf_Addr base_address_delta);
   bool ApplyOatPatchesTo(const char* target_section_name, Elf_Addr base_address_delta);
   static void ApplyOatPatches(const uint8_t* patches, const uint8_t* patches_end, Elf_Addr delta,
                               uint8_t* to_patch, const uint8_t* to_patch_end);

   bool Strip(std::string* error_msg);

  private:
   ElfFileImpl(File* file, bool writable, bool program_header_only, uint8_t* requested_base);

   bool Setup(int prot, int flags, std::string* error_msg);

   bool SetMap(MemMap* map, std::string* error_msg);

   uint8_t* GetProgramHeadersStart() const;
   uint8_t* GetSectionHeadersStart() const;
   Elf_Phdr& GetDynamicProgramHeader() const;
   Elf_Dyn* GetDynamicSectionStart() const;
   Elf_Sym* GetSymbolSectionStart(Elf_Word section_type) const;
   const char* GetStringSectionStart(Elf_Word section_type) const;
   Elf_Rel* GetRelSectionStart(Elf_Shdr&) const;
   Elf_Rela* GetRelaSectionStart(Elf_Shdr&) const;
   Elf_Word* GetHashSectionStart() const;
   Elf_Word GetHashBucketNum() const;
   Elf_Word GetHashChainNum() const;
   Elf_Word GetHashBucket(size_t i, bool* ok) const;
   Elf_Word GetHashChain(size_t i, bool* ok) const;

   typedef std::map<std::string, Elf_Sym*> SymbolTable;
   SymbolTable** GetSymbolTable(Elf_Word section_type);

   bool ValidPointer(const uint8_t* start) const;

   const Elf_Sym* FindDynamicSymbol(const std::string& symbol_name) const;

   // Check that certain sections and their dependencies exist.
   bool CheckSectionsExist(std::string* error_msg) const;

   // Check that the link of the first section links to the second section.
   bool CheckSectionsLinked(const uint8_t* source, const uint8_t* target) const;

   // Check whether the offset is in range, and set to target to Begin() + offset if OK.
   bool CheckAndSet(Elf32_Off offset, const char* label, uint8_t** target, std::string* error_msg);

   // Find symbol in specified table, returning null if it is not found.
   //
   // If build_map is true, builds a map to speed repeated access. The
   // map does not included untyped symbol values (aka STT_NOTYPE)
   // since they can contain duplicates. If build_map is false, the map
   // will be used if it was already created. Typically build_map
   // should be set unless only a small number of symbols will be
   // looked up.
   Elf_Sym* FindSymbolByName(Elf_Word section_type,
                             const std::string& symbol_name,
                             bool build_map);

   Elf_Phdr* FindProgamHeaderByType(Elf_Word type) const;

   Elf_Dyn* FindDynamicByType(Elf_Sword type) const;
   Elf_Word FindDynamicValueByType(Elf_Sword type) const;

   // Lookup a string by section type. Returns null for special 0 offset.
   const char* GetString(Elf_Word section_type, Elf_Word) const;

   const File* const file_;
   const bool writable_;
   const bool program_header_only_;

   // ELF header mapping. If program_header_only_ is false, will
   // actually point to the entire elf file.
   std::unique_ptr<MemMap> map_;
   Elf_Ehdr* header_;
   std::vector<MemMap*> segments_;

   // Pointer to start of first PT_LOAD program segment after Load()
   // when program_header_only_ is true.
   uint8_t* base_address_;

   // The program header should always available but use GetProgramHeadersStart() to be sure.
   uint8_t* program_headers_start_;

   // Conditionally available values. Use accessors to ensure they exist if they are required.
   uint8_t* section_headers_start_;
   Elf_Phdr* dynamic_program_header_;
   Elf_Dyn* dynamic_section_start_;
   Elf_Sym* symtab_section_start_;
   Elf_Sym* dynsym_section_start_;
   char* strtab_section_start_;
   char* dynstr_section_start_;
   Elf_Word* hash_section_start_;

   SymbolTable* symtab_symbol_table_;
   SymbolTable* dynsym_symbol_table_;

   // Support for GDB JIT
   uint8_t* jit_elf_image_;
   JITCodeEntry* jit_gdb_entry_;
   std::unique_ptr<ElfFileImpl<ElfTypes>> gdb_file_mapping_;
   void GdbJITSupport();

   // Override the 'base' p_vaddr in the first LOAD segment with this value (if non-null).
   uint8_t* requested_base_;

   DISALLOW_COPY_AND_ASSIGN(ElfFileImpl);
 };

 }  // namespace art

 #endif  // ART_RUNTIME_ELF_FILE_IMPL_H_
	/*
	* Copyright (C) 2012 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#ifndef ART_RUNTIME_ELF_FILE_IMPL_H_
	#define ART_RUNTIME_ELF_FILE_IMPL_H_

	#include <map>
	#include <memory>
	#include <type_traits>
	#include <vector>

	// Explicitly include our own elf.h to avoid Linux and other dependencies.
	#include "./elf.h"
	#include "mem_map.h"

	namespace art {

	extern "C" {
	struct JITCodeEntry;
	}

	template <typename ElfTypes>
	class ElfFileImpl {
	public:
	using Elf_Addr = typename ElfTypes::Addr;
	using Elf_Off = typename ElfTypes::Off;
	using Elf_Half = typename ElfTypes::Half;
	using Elf_Word = typename ElfTypes::Word;
	using Elf_Sword = typename ElfTypes::Sword;
	using Elf_Ehdr = typename ElfTypes::Ehdr;
	using Elf_Shdr = typename ElfTypes::Shdr;
	using Elf_Sym = typename ElfTypes::Sym;
	using Elf_Rel = typename ElfTypes::Rel;
	using Elf_Rela = typename ElfTypes::Rela;
	using Elf_Phdr = typename ElfTypes::Phdr;
	using Elf_Dyn = typename ElfTypes::Dyn;

	static ElfFileImpl* Open(File* file, bool writable, bool program_header_only,
	std::string* error_msg, uint8_t* requested_base = nullptr);
	static ElfFileImpl* Open(File* file, int mmap_prot, int mmap_flags, std::string* error_msg);
	~ElfFileImpl();

	const File& GetFile() const {
	return *file_;
	}

	uint8_t* Begin() const {
	return map_->Begin();
	}

	uint8_t* End() const {
	return map_->End();
	}

	size_t Size() const {
	return map_->Size();
	}

	Elf_Ehdr& GetHeader() const;

	Elf_Word GetProgramHeaderNum() const;
	Elf_Phdr* GetProgramHeader(Elf_Word) const;

	Elf_Word GetSectionHeaderNum() const;
	Elf_Shdr* GetSectionHeader(Elf_Word) const;
	Elf_Shdr* FindSectionByType(Elf_Word type) const;
	Elf_Shdr* FindSectionByName(const std::string& name) const;

	Elf_Shdr* GetSectionNameStringSection() const;

	// Find .dynsym using .hash for more efficient lookup than FindSymbolAddress.
	const uint8_t* FindDynamicSymbolAddress(const std::string& symbol_name) const;

	static bool IsSymbolSectionType(Elf_Word section_type);
	Elf_Word GetSymbolNum(Elf_Shdr&) const;
	Elf_Sym* GetSymbol(Elf_Word section_type, Elf_Word i) const;

	// Find address of symbol in specified table, returning 0 if it is
	// not found. See FindSymbolByName for an explanation of build_map.
	Elf_Addr FindSymbolAddress(Elf_Word section_type,
	const std::string& symbol_name,
	bool build_map);

	// Lookup a string given string section and offset. Returns null for special 0 offset.
	const char* GetString(Elf_Shdr&, Elf_Word) const;

	Elf_Word GetDynamicNum() const;
	Elf_Dyn& GetDynamic(Elf_Word) const;

	Elf_Word GetRelNum(Elf_Shdr&) const;
	Elf_Rel& GetRel(Elf_Shdr&, Elf_Word) const;

	Elf_Word GetRelaNum(Elf_Shdr&) const;
	Elf_Rela& GetRela(Elf_Shdr&, Elf_Word) const;

	// Retrieves the expected size when the file is loaded at runtime. Returns true if successful.
	bool GetLoadedSize(size_t* size, std::string* error_msg) const;

	// Load segments into memory based on PT_LOAD program headers.
	// executable is true at run time, false at compile time.
	bool Load(bool executable, std::string* error_msg);

	bool Fixup(Elf_Addr base_address);
	bool FixupDynamic(Elf_Addr base_address);
	bool FixupSectionHeaders(Elf_Addr base_address);
	bool FixupProgramHeaders(Elf_Addr base_address);
	bool FixupSymbols(Elf_Addr base_address, bool dynamic);
	bool FixupRelocations(Elf_Addr base_address);
	bool FixupDebugSections(Elf_Addr base_address_delta);
	bool ApplyOatPatchesTo(const char* target_section_name, Elf_Addr base_address_delta);
	static void ApplyOatPatches(const uint8_t* patches, const uint8_t* patches_end, Elf_Addr delta,
	uint8_t* to_patch, const uint8_t* to_patch_end);

	bool Strip(std::string* error_msg);

	private:
	ElfFileImpl(File* file, bool writable, bool program_header_only, uint8_t* requested_base);

	bool Setup(int prot, int flags, std::string* error_msg);

	bool SetMap(MemMap* map, std::string* error_msg);

	uint8_t* GetProgramHeadersStart() const;
	uint8_t* GetSectionHeadersStart() const;
	Elf_Phdr& GetDynamicProgramHeader() const;
	Elf_Dyn* GetDynamicSectionStart() const;
	Elf_Sym* GetSymbolSectionStart(Elf_Word section_type) const;
	const char* GetStringSectionStart(Elf_Word section_type) const;
	Elf_Rel* GetRelSectionStart(Elf_Shdr&) const;
	Elf_Rela* GetRelaSectionStart(Elf_Shdr&) const;
	Elf_Word* GetHashSectionStart() const;
	Elf_Word GetHashBucketNum() const;
	Elf_Word GetHashChainNum() const;
	Elf_Word GetHashBucket(size_t i, bool* ok) const;
	Elf_Word GetHashChain(size_t i, bool* ok) const;

	typedef std::map<std::string, Elf_Sym*> SymbolTable;
	SymbolTable** GetSymbolTable(Elf_Word section_type);

	bool ValidPointer(const uint8_t* start) const;

	const Elf_Sym* FindDynamicSymbol(const std::string& symbol_name) const;

	// Check that certain sections and their dependencies exist.
	bool CheckSectionsExist(std::string* error_msg) const;

	// Check that the link of the first section links to the second section.
	bool CheckSectionsLinked(const uint8_t* source, const uint8_t* target) const;

	// Check whether the offset is in range, and set to target to Begin() + offset if OK.
	bool CheckAndSet(Elf32_Off offset, const char* label, uint8_t** target, std::string* error_msg);

	// Find symbol in specified table, returning null if it is not found.
	//
	// If build_map is true, builds a map to speed repeated access. The
	// map does not included untyped symbol values (aka STT_NOTYPE)
	// since they can contain duplicates. If build_map is false, the map
	// will be used if it was already created. Typically build_map
	// should be set unless only a small number of symbols will be
	// looked up.
	Elf_Sym* FindSymbolByName(Elf_Word section_type,
	const std::string& symbol_name,
	bool build_map);

	Elf_Phdr* FindProgamHeaderByType(Elf_Word type) const;

	Elf_Dyn* FindDynamicByType(Elf_Sword type) const;
	Elf_Word FindDynamicValueByType(Elf_Sword type) const;

	// Lookup a string by section type. Returns null for special 0 offset.
	const char* GetString(Elf_Word section_type, Elf_Word) const;

	const File* const file_;
	const bool writable_;
	const bool program_header_only_;

	// ELF header mapping. If program_header_only_ is false, will
	// actually point to the entire elf file.
	std::unique_ptr<MemMap> map_;
	Elf_Ehdr* header_;
	std::vector<MemMap*> segments_;

	// Pointer to start of first PT_LOAD program segment after Load()
	// when program_header_only_ is true.
	uint8_t* base_address_;

	// The program header should always available but use GetProgramHeadersStart() to be sure.
	uint8_t* program_headers_start_;

	// Conditionally available values. Use accessors to ensure they exist if they are required.
	uint8_t* section_headers_start_;
	Elf_Phdr* dynamic_program_header_;
	Elf_Dyn* dynamic_section_start_;
	Elf_Sym* symtab_section_start_;
	Elf_Sym* dynsym_section_start_;
	char* strtab_section_start_;
	char* dynstr_section_start_;
	Elf_Word* hash_section_start_;

	SymbolTable* symtab_symbol_table_;
	SymbolTable* dynsym_symbol_table_;

	// Support for GDB JIT
	uint8_t* jit_elf_image_;
	JITCodeEntry* jit_gdb_entry_;
	std::unique_ptr<ElfFileImpl<ElfTypes>> gdb_file_mapping_;
	void GdbJITSupport();

	// Override the 'base' p_vaddr in the first LOAD segment with this value (if non-null).
	uint8_t* requested_base_;

	DISALLOW_COPY_AND_ASSIGN(ElfFileImpl);
	};

	} // namespace art

	#endif // ART_RUNTIME_ELF_FILE_IMPL_H_