// output.h -- manage the output file for gold -*- C++ -*- #ifndef GOLD_OUTPUT_H #define GOLD_OUTPUT_H #include #include #include #include "elfcpp.h" #include "layout.h" namespace gold { class General_options; class Object; class Output_file; template class Sized_target; // An abtract class for data which has to go into the output file. class Output_data { public: explicit Output_data(off_t data_size = 0) : address_(0), data_size_(data_size), offset_(-1) { } virtual ~Output_data(); // Return the address. This is only valid after Layout::finalize is // finished. uint64_t address() const { return this->address_; } // Return the size of the data. This must be valid after // Layout::finalize calls set_address, but need not be valid before // then. off_t data_size() const { return this->data_size_; } // Return the file offset. This is only valid after // Layout::finalize is finished. off_t offset() const { return this->offset_; } // Return the required alignment. uint64_t addralign() const { return this->do_addralign(); } // Return whether this is an Output_section. bool is_section() const { return this->do_is_section(); } // Return whether this is an Output_section of the specified type. bool is_section_type(elfcpp::Elf_Word stt) const { return this->do_is_section_type(stt); } // Return whether this is an Output_section with the specified flag // set. bool is_section_flag_set(elfcpp::Elf_Xword shf) const { return this->do_is_section_flag_set(shf); } // Return the output section index, if there is an output section. unsigned int out_shndx() const { return this->do_out_shndx(); } // Set the output section index, if this is an output section. void set_out_shndx(unsigned int shndx) { this->do_set_out_shndx(shndx); } // Set the address and file offset of this data. This is called // during Layout::finalize. void set_address(uint64_t addr, off_t off); // Write the data to the output file. This is called after // Layout::finalize is complete. void write(Output_file* file) { this->do_write(file); } protected: // Functions that child classes may or in some cases must implement. // Write the data to the output file. virtual void do_write(Output_file*) = 0; // Return the required alignment. virtual uint64_t do_addralign() const = 0; // Return whether this is an Output_section. virtual bool do_is_section() const { return false; } // Return whether this is an Output_section of the specified type. // This only needs to be implement by Output_section. virtual bool do_is_section_type(elfcpp::Elf_Word) const { return false; } // Return whether this is an Output_section with the specific flag // set. This only needs to be implemented by Output_section. virtual bool do_is_section_flag_set(elfcpp::Elf_Xword) const { return false; } // Return the output section index, if there is an output section. virtual unsigned int do_out_shndx() const { abort(); } // Set the output section index, if this is an output section. virtual void do_set_out_shndx(unsigned int) { abort(); } // Set the address and file offset of the data. This only needs to // be implemented if the child needs to know. virtual void do_set_address(uint64_t, off_t) { } // Functions that child classes may call. // Set the size of the data. void set_data_size(off_t data_size) { this->data_size_ = data_size; } // Return default alignment for a size--32 or 64. static uint64_t default_alignment(int size); private: Output_data(const Output_data&); Output_data& operator=(const Output_data&); // Memory address in file (not always meaningful). uint64_t address_; // Size of data in file. off_t data_size_; // Offset within file. off_t offset_; }; // A simple case of Output_data in which we have constant data to // output. class Output_data_const : public Output_data { public: Output_data_const(const std::string& data, uint64_t addralign) : Output_data(data.size()), data_(data), addralign_(addralign) { } Output_data_const(const char* p, off_t len, uint64_t addralign) : Output_data(len), data_(p, len), addralign_(addralign) { } // Write the data to the file. void do_write(Output_file* output); // Return the required alignment. uint64_t do_addralign() const { return this->addralign_; } private: std::string data_; uint64_t addralign_; }; // Output the section headers. class Output_section_headers : public Output_data { public: Output_section_headers(int size, bool big_endian, const Layout::Segment_list&, const Layout::Section_list&, const Stringpool*); // Write the data to the file. void do_write(Output_file*); // Return the required alignment. uint64_t do_addralign() const { return Output_data::default_alignment(this->size_); } private: // Write the data to the file with the right size and endianness. template void do_sized_write(Output_file*); int size_; bool big_endian_; const Layout::Segment_list& segment_list_; const Layout::Section_list& section_list_; const Stringpool* secnamepool_; }; // Output the segment headers. class Output_segment_headers : public Output_data { public: Output_segment_headers(int size, bool big_endian, const Layout::Segment_list& segment_list); // Write the data to the file. void do_write(Output_file*); // Return the required alignment. uint64_t do_addralign() const { return Output_data::default_alignment(this->size_); } private: // Write the data to the file with the right size and endianness. template void do_sized_write(Output_file*); int size_; bool big_endian_; const Layout::Segment_list& segment_list_; }; // Output the ELF file header. class Output_file_header : public Output_data { public: Output_file_header(int size, bool big_endian, const General_options&, const Target*, const Symbol_table*, const Output_segment_headers*); // Add information about the section headers. We lay out the ELF // file header before we create the section headers. void set_section_info(const Output_section_headers*, const Output_section* shstrtab); // Write the data to the file. void do_write(Output_file*); // Return the required alignment. uint64_t do_addralign() const { return Output_data::default_alignment(this->size_); } // Set the address and offset--we only implement this for error // checking. void do_set_address(uint64_t, off_t off) const { assert(off == 0); } private: // Write the data to the file with the right size and endianness. template void do_sized_write(Output_file*); int size_; bool big_endian_; const General_options& options_; const Target* target_; const Symbol_table* symtab_; const Output_segment_headers* segment_header_; const Output_section_headers* section_header_; const Output_section* shstrtab_; }; // Output sections are mainly comprised of input sections. However, // there are cases where we have data to write out which is not in an // input section. Output_section_data is used in such cases. This is // an abstract base class. class Output_section_data : public Output_data { public: Output_section_data(off_t data_size, uint64_t addralign) : Output_data(data_size), output_section_(NULL), addralign_(addralign) { } Output_section_data(uint64_t addralign) : Output_data(0), output_section_(NULL), addralign_(addralign) { } // Record the output section. void set_output_section(Output_section* os) { assert(this->output_section_ == NULL); this->output_section_ = os; } protected: // The child class must implement do_write. // Return the required alignment. uint64_t do_addralign() const { return this->addralign_; } // Return the section index of the output section. unsigned int do_out_shndx() const; private: // The output section for this section. const Output_section* output_section_; // The required alignment. uint64_t addralign_; }; // Output_section_common is used to handle the common symbols. This // is quite simple. class Output_section_common : public Output_section_data { public: Output_section_common(uint64_t addralign) : Output_section_data(addralign) { } // Set the size. void set_common_size(off_t common_size) { this->set_data_size(common_size); } // Write out the data--there is nothing to do, as common symbols are // always zero and are stored in the BSS. void do_write(Output_file*) { } }; // Output_section_got is used to manage a GOT. Each entry in the GOT // is for one symbol--either a global symbol or a local symbol in an // object. The target specific code adds entries to the GOT as // needed. The GOT code is then responsible for writing out the data // and for generating relocs as required. template class Output_section_got : public Output_section_data { public: typedef typename elfcpp::Elf_types::Elf_Addr Valtype; Output_section_got() : Output_section_data(Output_data::default_alignment(size)), entries_() { } // Add an entry for a global symbol to the GOT. This returns the // offset of the new entry from the start of the GOT. unsigned int add_global(Symbol* gsym) { this->entries_.push_back(Got_entry(gsym)); this->set_got_size(); return this->last_got_offset(); } // Add an entry for a local symbol to the GOT. This returns the // offset of the new entry from the start of the GOT. unsigned int add_local(Object* object, unsigned int sym_index) { this->entries_.push_back(Got_entry(object, sym_index)); this->set_got_size(); return this->last_got_offset(); } // Add a constant to the GOT. This returns the offset of the new // entry from the start of the GOT. unsigned int add_constant(Valtype constant) { this->entries_.push_back(Got_entry(constant)); this->set_got_size(); return this->last_got_offset(); } // Write out the GOT table. void do_write(Output_file*); private: // This POD class holds a single GOT entry. class Got_entry { public: // Create a zero entry. Got_entry() : local_sym_index_(CONSTANT_CODE) { this->u_.constant = 0; } // Create a global symbol entry. Got_entry(Symbol* gsym) : local_sym_index_(GSYM_CODE) { this->u_.gsym = gsym; } // Create a local symbol entry. Got_entry(Object* object, unsigned int local_sym_index) : local_sym_index_(local_sym_index) { assert(local_sym_index != GSYM_CODE && local_sym_index != CONSTANT_CODE); this->u_.object = object; } // Create a constant entry. The constant is a host value--it will // be swapped, if necessary, when it is written out. Got_entry(Valtype constant) : local_sym_index_(CONSTANT_CODE) { this->u_.constant = constant; } // Write the GOT entry to an output view. void write(unsigned char* pov) const; private: enum { GSYM_CODE = -1U, CONSTANT_CODE = -2U }; union { // For a local symbol, the object. Object* object; // For a global symbol, the symbol. Symbol* gsym; // For a constant, the constant. Valtype constant; } u_; // For a local symbol, the local symbol index. This is -1U for a // global symbol, or -2U for a constant. unsigned int local_sym_index_; }; typedef std::vector Got_entries; // Return the offset into the GOT of GOT entry I. unsigned int got_offset(unsigned int i) const { return i * (size / 8); } // Return the offset into the GOT of the last entry added. unsigned int last_got_offset() const { return this->got_offset(this->entries_.size() - 1); } // Set the size of the section. void set_got_size() { this->set_data_size(this->got_offset(this->entries_.size())); } // The list of GOT entries. Got_entries entries_; }; // An output section. We don't expect to have too many output // sections, so we don't bother to do a template on the size. class Output_section : public Output_data { public: // Create an output section, giving the name, type, and flags. Output_section(const char* name, elfcpp::Elf_Word, elfcpp::Elf_Xword, bool may_add_data); virtual ~Output_section(); // Add a new input section SHNDX, named NAME, with header SHDR, from // object OBJECT. Return the offset within the output section. template off_t add_input_section(Relobj* object, unsigned int shndx, const char *name, const elfcpp::Shdr& shdr); // Add generated data ODATA to this output section. virtual void add_output_section_data(Output_section_data* posd); // Return the section name. const char* name() const { return this->name_; } // Return the section type. elfcpp::Elf_Word type() const { return this->type_; } // Return the section flags. elfcpp::Elf_Xword flags() const { return this->flags_; } // Return the section index in the output file. unsigned int do_out_shndx() const { return this->out_shndx_; } // Set the output section index. void do_set_out_shndx(unsigned int shndx) { this->out_shndx_ = shndx; } // Set the entsize field. void set_entsize(uint64_t v) { this->entsize_ = v; } // Set the link field. void set_link(unsigned int v) { this->link_ = v; } // Set the info field. void set_info(unsigned int v) { this->info_ = v; } // Set the addralign field. void set_addralign(uint64_t v) { this->addralign_ = v; } // Set the address of the Output_section. For a typical // Output_section, there is nothing to do, but if there are any // Output_section_data objects we need to set the final addresses // here. void do_set_address(uint64_t, off_t); // Write the data to the file. For a typical Output_section, this // does nothing: the data is written out by calling Object::Relocate // on each input object. But if there are any Output_section_data // objects we do need to write them out here. virtual void do_write(Output_file*); // Return the address alignment--function required by parent class. uint64_t do_addralign() const { return this->addralign_; } // Return whether this is an Output_section. bool do_is_section() const { return true; } // Return whether this is a section of the specified type. bool do_is_section_type(elfcpp::Elf_Word type) const { return this->type_ == type; } // Return whether the specified section flag is set. bool do_is_section_flag_set(elfcpp::Elf_Xword flag) const { return (this->flags_ & flag) != 0; } // Write the section header into *OPHDR. template void write_header(const Stringpool*, elfcpp::Shdr_write*) const; private: // In some cases we need to keep a list of the input sections // associated with this output section. We only need the list if we // might have to change the offsets of the input section within the // output section after we add the input section. The ordinary // input sections will be written out when we process the object // file, and as such we don't need to track them here. We do need // to track Output_section_data objects here. We store instances of // this structure in a std::vector, so it must be a POD. There can // be many instances of this structure, so we use a union to save // some space. class Input_section { public: Input_section() : shndx_(0), p2align_(0), data_size_(0) { this->u_.object = NULL; } Input_section(Relobj* object, unsigned int shndx, off_t data_size, uint64_t addralign) : shndx_(shndx), p2align_(ffsll(static_cast(addralign))), data_size_(data_size) { assert(shndx != -1U); this->u_.object = object; } Input_section(Output_section_data* posd) : shndx_(-1U), p2align_(ffsll(static_cast(posd->addralign()))), data_size_(0) { this->u_.posd = posd; } // The required alignment. uint64_t addralign() const { return static_cast(1) << this->p2align_; } // Return the required size. off_t data_size() const; // Set the address and file offset. This is called during // Layout::finalize. SECOFF is the file offset of the enclosing // section. void set_address(uint64_t addr, off_t off, off_t secoff); // Write out the data. This does nothing for an input section. void write(Output_file*); private: // Whether this is an input section. bool is_input_section() const { return this->shndx_ != -1U; } // For an ordinary input section, this is the section index in // the input file. For an Output_section_data, this is -1U. unsigned int shndx_; // The required alignment, stored as a power of 2. unsigned int p2align_; // For an ordinary input section, the section size. off_t data_size_; union { // If shndx_ != -1U, this points to the object which holds the // input section. Relobj* object; // If shndx_ == -1U, this is the data to write out. Output_section_data* posd; } u_; }; typedef std::vector Input_section_list; // Most of these fields are only valid after layout. // The name of the section. This will point into a Stringpool. const char* name_; // The section address is in the parent class. // The section alignment. uint64_t addralign_; // The section entry size. uint64_t entsize_; // The file offset is in the parent class. // The section link field. unsigned int link_; // The section info field. unsigned int info_; // The section type. elfcpp::Elf_Word type_; // The section flags. elfcpp::Elf_Xword flags_; // The section index. unsigned int out_shndx_; // The input sections. This will be empty in cases where we don't // need to keep track of them. Input_section_list input_sections_; // The offset of the first entry in input_sections_. off_t first_input_offset_; // Whether we permit adding data. bool may_add_data_; }; // A special Output_section which represents the symbol table // (SHT_SYMTAB). The actual data is written out by // Symbol_table::write_globals. class Output_section_symtab : public Output_section { public: Output_section_symtab(const char* name, off_t size); // The data is written out by Symbol_table::write_globals. We don't // do anything here. void do_write(Output_file*) { } // We don't expect to see any input sections or data here. void add_output_section_data(Output_section_data*) { abort(); } }; // A special Output_section which holds a string table. class Output_section_strtab : public Output_section { public: Output_section_strtab(const char* name, Stringpool* contents); // Write out the data. void do_write(Output_file*); // We don't expect to see any input sections or data here. void add_output_section_data(Output_section_data*) { abort(); } private: Stringpool* contents_; }; // An output segment. PT_LOAD segments are built from collections of // output sections. Other segments typically point within PT_LOAD // segments, and are built directly as needed. class Output_segment { public: // Create an output segment, specifying the type and flags. Output_segment(elfcpp::Elf_Word, elfcpp::Elf_Word); // Return the virtual address. uint64_t vaddr() const { return this->vaddr_; } // Return the physical address. uint64_t paddr() const { return this->paddr_; } // Return the segment type. elfcpp::Elf_Word type() const { return this->type_; } // Return the segment flags. elfcpp::Elf_Word flags() const { return this->flags_; } // Return the memory size. uint64_t memsz() const { return this->memsz_; } // Return the file size. off_t filesz() const { return this->filesz_; } // Return the maximum alignment of the Output_data. uint64_t addralign(); // Add an Output_section to this segment. void add_output_section(Output_section*, elfcpp::Elf_Word seg_flags); // Add an Output_data (which is not an Output_section) to the start // of this segment. void add_initial_output_data(Output_data*); // Set the address of the segment to ADDR and the offset to *POFF // (aligned if necessary), and set the addresses and offsets of all // contained output sections accordingly. Set the section indexes // of all contained output sections starting with *PSHNDX. Return // the address of the immediately following segment. Update *POFF // and *PSHNDX. This should only be called for a PT_LOAD segment. uint64_t set_section_addresses(uint64_t addr, off_t* poff, unsigned int* pshndx); // Set the offset of this segment based on the section. This should // only be called for a non-PT_LOAD segment. void set_offset(); // Return the number of output sections. unsigned int output_section_count() const; // Write the segment header into *OPHDR. template void write_header(elfcpp::Phdr_write*); // Write the section headers of associated sections into V. template unsigned char* write_section_headers(const Stringpool*, unsigned char* v, unsigned int* pshndx ACCEPT_SIZE_ENDIAN) const; private: Output_segment(const Output_segment&); Output_segment& operator=(const Output_segment&); typedef std::list Output_data_list; // Find the maximum alignment in an Output_data_list. static uint64_t maximum_alignment(const Output_data_list*); // Set the section addresses in an Output_data_list. uint64_t set_section_list_addresses(Output_data_list*, uint64_t addr, off_t* poff, unsigned int* pshndx); // Return the number of Output_sections in an Output_data_list. unsigned int output_section_count_list(const Output_data_list*) const; // Write the section headers in the list into V. template unsigned char* write_section_headers_list(const Stringpool*, const Output_data_list*, unsigned char* v, unsigned int* pshdx ACCEPT_SIZE_ENDIAN) const; // The list of output data with contents attached to this segment. Output_data_list output_data_; // The list of output data without contents attached to this segment. Output_data_list output_bss_; // The segment virtual address. uint64_t vaddr_; // The segment physical address. uint64_t paddr_; // The size of the segment in memory. uint64_t memsz_; // The segment alignment. uint64_t align_; // The offset of the segment data within the file. off_t offset_; // The size of the segment data in the file. off_t filesz_; // The segment type; elfcpp::Elf_Word type_; // The segment flags. elfcpp::Elf_Word flags_; // Whether we have set align_. bool is_align_known_; }; // This class represents the output file. class Output_file { public: Output_file(const General_options& options); // Open the output file. FILE_SIZE is the final size of the file. void open(off_t file_size); // Close the output file and make sure there are no error. void close(); // We currently always use mmap which makes the view handling quite // simple. In the future we may support other approaches. // Write data to the output file. void write(off_t offset, const void* data, off_t len) { memcpy(this->base_ + offset, data, len); } // Get a buffer to use to write to the file, given the offset into // the file and the size. unsigned char* get_output_view(off_t start, off_t size) { assert(start >= 0 && size >= 0 && start + size <= this->file_size_); return this->base_ + start; } // VIEW must have been returned by get_output_view. Write the // buffer to the file, passing in the offset and the size. void write_output_view(off_t, off_t, unsigned char*) { } private: // General options. const General_options& options_; // File name. const char* name_; // File descriptor. int o_; // File size. off_t file_size_; // Base of file mapped into memory. unsigned char* base_; }; } // End namespace gold. #endif // !defined(GOLD_OUTPUT_H)