X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=gold%2Fehframe.h;h=4fd8f3e2f68885c3fc7325788c0e01d4c53dca5c;hb=f65fe5704af56aca58fd5547d0841a9512e540af;hp=1f6c022a95ee4a3ff24ee7c8dc81c7ff2eb808cd;hpb=3151305a47fc17a35bc76cc50578b3e8f9b93d9d;p=deliverable%2Fbinutils-gdb.git diff --git a/gold/ehframe.h b/gold/ehframe.h index 1f6c022a95..4fd8f3e2f6 100644 --- a/gold/ehframe.h +++ b/gold/ehframe.h @@ -1,6 +1,6 @@ // ehframe.h -- handle exception frame sections for gold -*- C++ -*- -// Copyright 2006, 2007 Free Software Foundation, Inc. +// Copyright (C) 2006-2019 Free Software Foundation, Inc. // Written by Ian Lance Taylor . // This file is part of gold. @@ -23,11 +23,21 @@ #ifndef GOLD_EHFRAME_H #define GOLD_EHFRAME_H +#include +#include +#include + #include "output.h" +#include "merge.h" namespace gold { +template +class Track_relocs; + +class Eh_frame; + // This class manages the .eh_frame_hdr section, which holds the data // for the PT_GNU_EH_FRAME segment. gcc's unwind support code uses // the PT_GNU_EH_FRAME segment to find the list of FDEs. This saves @@ -35,28 +45,500 @@ namespace gold // time and when a shared object is loaded, and the time required to // deregister the exception handlers when a shared object is unloaded. -// FIXME: gcc supports using storing a sorted lookup table for the -// FDEs in the PT_GNU_EH_FRAME segment, but we do not yet generate -// that. - class Eh_frame_hdr : public Output_section_data { public: - Eh_frame_hdr(const Target*, Output_section* eh_frame_section); + Eh_frame_hdr(Output_section* eh_frame_section, const Eh_frame*); + // Record that we found an unrecognized .eh_frame section. + void + found_unrecognized_eh_frame_section() + { this->any_unrecognized_eh_frame_sections_ = true; } + + // Record an FDE. + void + record_fde(section_offset_type fde_offset, unsigned char fde_encoding) + { + if (!this->any_unrecognized_eh_frame_sections_) + this->fde_offsets_.push_back(std::make_pair(fde_offset, fde_encoding)); + } + + protected: // Set the final data size. void - do_set_address(uint64_t address, off_t offset); + set_final_data_size(); // Write the data to the file. void do_write(Output_file*); + // Write to a map file. + void + do_print_to_mapfile(Mapfile* mapfile) const + { mapfile->print_output_data(this, _("** eh_frame_hdr")); } + private: - // The output target. - const Target* target_; + // Write the data to the file with the right endianness. + template + void + do_sized_write(Output_file*); + + // The data we record for one FDE: the offset of the FDE within the + // .eh_frame section, and the FDE encoding. + typedef std::pair Fde_offset; + + // The list of information we record for an FDE. + typedef std::vector Fde_offsets; + + // When writing out the header, we convert the FDE offsets into FDE + // addresses. This is a list of pairs of the offset from the header + // to the FDE PC and to the FDE itself. + template + class Fde_addresses + { + public: + typedef typename elfcpp::Elf_types::Elf_Addr Address; + typedef typename std::pair Fde_address; + typedef typename std::vector Fde_address_list; + typedef typename Fde_address_list::iterator iterator; + + Fde_addresses(unsigned int reserve) + : fde_addresses_() + { this->fde_addresses_.reserve(reserve); } + + void + push_back(Address pc_address, Address fde_address) + { + this->fde_addresses_.push_back(std::make_pair(pc_address, fde_address)); + } + + iterator + begin() + { return this->fde_addresses_.begin(); } + + iterator + end() + { return this->fde_addresses_.end(); } + + private: + Fde_address_list fde_addresses_; + }; + + // Compare Fde_address objects. + template + struct Fde_address_compare + { + bool + operator()(const typename Fde_addresses::Fde_address& f1, + const typename Fde_addresses::Fde_address& f2) const + { return f1.first < f2.first; } + }; + + // Return the PC to which an FDE refers. + template + typename elfcpp::Elf_types::Elf_Addr + get_fde_pc(typename elfcpp::Elf_types::Elf_Addr eh_frame_address, + const unsigned char* eh_frame_contents, + section_offset_type fde_offset, unsigned char fde_encoding); + + // Convert Fde_offsets to Fde_addresses. + template + void + get_fde_addresses(Output_file* of, + const Fde_offsets* fde_offsets, + Fde_addresses* fde_addresses); + // The .eh_frame section. Output_section* eh_frame_section_; + // The .eh_frame section data. + const Eh_frame* eh_frame_data_; + // Data from the FDEs in the .eh_frame sections. + Fde_offsets fde_offsets_; + // Whether we found any .eh_frame sections which we could not + // process. + bool any_unrecognized_eh_frame_sections_; +}; + +// This class holds an FDE. + +class Fde +{ + public: + Fde(Relobj* object, unsigned int shndx, section_offset_type input_offset, + const unsigned char* contents, size_t length) + : object_(object), + contents_(reinterpret_cast(contents), length) + { + this->u_.from_object.shndx = shndx; + this->u_.from_object.input_offset = input_offset; + } + + // Create an FDE associated with a PLT. + Fde(Output_data* plt, const unsigned char* contents, size_t length, + bool post_map) + : object_(NULL), + contents_(reinterpret_cast(contents), length) + { + this->u_.from_linker.plt = plt; + this->u_.from_linker.post_map = post_map; + } + + // Return the length of this FDE. Add 4 for the length and 4 for + // the offset to the CIE. + size_t + length() const + { return this->contents_.length() + 8; } + + // Add a mapping for this FDE to MERGE_MAP, so that relocations + // against the FDE are applied to right part of the output file. + void + add_mapping(section_offset_type output_offset, + Output_section_data* output_data) const + { + if (this->object_ != NULL) + this->object_->add_merge_mapping(output_data, this->u_.from_object.shndx, + this->u_.from_object.input_offset, this->length(), + output_offset); + } + + // Return whether this FDE was added after merge mapping. + bool + post_map() const + { return this->object_ == NULL && this->u_.from_linker.post_map; } + + // Return whether this FDE was added for the PLT after merge mapping. + bool + post_map(const Output_data* plt) const + { return this->post_map() && this->u_.from_linker.plt == plt; } + + // Write the FDE to OVIEW starting at OFFSET. FDE_ENCODING is the + // encoding, from the CIE. Round up the bytes to ADDRALIGN if + // necessary. ADDRESS is the virtual address of OVIEW. Record the + // FDE in EH_FRAME_HDR. Return the new offset. + template + section_offset_type + write(unsigned char* oview, section_offset_type output_section_offset, + section_offset_type offset, uint64_t address, unsigned int addralign, + section_offset_type cie_offset, unsigned char fde_encoding, + Eh_frame_hdr* eh_frame_hdr); + + private: + // The object in which this FDE was seen. This will be NULL for a + // linker generated FDE. + Relobj* object_; + union + { + // These fields are used if the FDE is from an input object (the + // object_ field is not NULL). + struct + { + // Input section index for this FDE. + unsigned int shndx; + // Offset within the input section for this FDE. + section_offset_type input_offset; + } from_object; + // This field is used if the FDE is generated by the linker (the + // object_ field is NULL). + struct + { + // The only linker generated FDEs are for PLT sections, and this + // points to the PLT section. + Output_data* plt; + // Set if the FDE was added after merge mapping. + bool post_map; + } from_linker; + } u_; + // FDE data. + std::string contents_; +}; + +// A FDE plus some info from a CIE to allow later writing of the FDE. + +struct Post_fde +{ + Post_fde(Fde* f, section_offset_type cie_off, unsigned char encoding) + : fde(f), cie_offset(cie_off), fde_encoding(encoding) + { } + + Fde* fde; + section_offset_type cie_offset; + unsigned char fde_encoding; +}; + +typedef std::vector Post_fdes; + +// This class holds a CIE. + +class Cie +{ + public: + Cie(Relobj* object, unsigned int shndx, section_offset_type input_offset, + unsigned char fde_encoding, const char* personality_name, + const unsigned char* contents, size_t length) + : object_(object), + shndx_(shndx), + input_offset_(input_offset), + fde_encoding_(fde_encoding), + personality_name_(personality_name), + fdes_(), + contents_(reinterpret_cast(contents), length) + { } + + ~Cie(); + + // We permit copying a CIE when there are no FDEs. This is + // convenient in the code which creates them. + Cie(const Cie& cie) + : object_(cie.object_), + shndx_(cie.shndx_), + input_offset_(cie.input_offset_), + fde_encoding_(cie.fde_encoding_), + personality_name_(cie.personality_name_), + fdes_(), + contents_(cie.contents_) + { gold_assert(cie.fdes_.empty()); } + + // Add an FDE associated with this CIE. + void + add_fde(Fde* fde) + { this->fdes_.push_back(fde); } + + // Remove the last FDE associated with this CIE. + void + remove_fde() + { this->fdes_.pop_back(); } + + // Access the last FDE associated with this CIE. + const Fde* + last_fde() const + { return this->fdes_.back(); } + + // Return the number of FDEs. + unsigned int + fde_count() const + { return this->fdes_.size(); } + + // Set the output offset of this CIE to OUTPUT_OFFSET. It will be + // followed by all its FDEs. ADDRALIGN is the required address + // alignment, typically 4 or 8. This updates MERGE_MAP with the + // mapping. It returns the new output offset. + section_offset_type + set_output_offset(section_offset_type output_offset, unsigned int addralign, + Output_section_data*); + + // Write the CIE to OVIEW starting at OFFSET. Round up the bytes to + // ADDRALIGN. ADDRESS is the virtual address of OVIEW. + // EH_FRAME_HDR is the exception frame header for FDE recording. + // POST_FDES stashes FDEs created after mappings were done, for later + // writing. Return the new offset. + template + section_offset_type + write(unsigned char* oview, section_offset_type output_section_offset, + section_offset_type offset, uint64_t address, + unsigned int addralign, Eh_frame_hdr* eh_frame_hdr, + Post_fdes* post_fdes); + + // Return the FDE encoding. + unsigned char + fde_encoding() const + { return this->fde_encoding_; } + + friend bool operator<(const Cie&, const Cie&); + friend bool operator==(const Cie&, const Cie&); + + private: + // The class is not assignable. + Cie& operator=(const Cie&); + + // The object in which this CIE was first seen. This will be NULL + // for a linker generated CIE. + Relobj* object_; + // Input section index for this CIE. This will be 0 for a linker + // generated CIE. + unsigned int shndx_; + // Offset within the input section for this CIE. This will be 0 for + // a linker generated CIE. + section_offset_type input_offset_; + // The encoding of the FDE. This is a DW_EH_PE code. + unsigned char fde_encoding_; + // The name of the personality routine. This will be the name of a + // global symbol, or will be the empty string. + std::string personality_name_; + // List of FDEs. + std::vector fdes_; + // CIE data. + std::string contents_; +}; + +extern bool operator<(const Cie&, const Cie&); +extern bool operator==(const Cie&, const Cie&); + +// This class manages .eh_frame sections. It discards duplicate +// exception information. + +class Eh_frame : public Output_section_data +{ + public: + enum Eh_frame_section_disposition + { + EH_EMPTY_SECTION, + EH_UNRECOGNIZED_SECTION, + EH_OPTIMIZABLE_SECTION, + EH_END_MARKER_SECTION + }; + + Eh_frame(); + + // Record the associated Eh_frame_hdr, if any. + void + set_eh_frame_hdr(Eh_frame_hdr* hdr) + { this->eh_frame_hdr_ = hdr; } + + // Add the input section SHNDX in OBJECT. SYMBOLS is the contents + // of the symbol table section (size SYMBOLS_SIZE), SYMBOL_NAMES is + // the symbol names section (size SYMBOL_NAMES_SIZE). RELOC_SHNDX + // is the relocation section if any (0 for none, -1U for multiple). + // RELOC_TYPE is the type of the relocation section if any. This + // returns whether the section was incorporated into the .eh_frame + // data. + template + Eh_frame_section_disposition + add_ehframe_input_section(Sized_relobj_file* object, + const unsigned char* symbols, + section_size_type symbols_size, + const unsigned char* symbol_names, + section_size_type symbol_names_size, + unsigned int shndx, unsigned int reloc_shndx, + unsigned int reloc_type); + + // Add a CIE and an FDE for a PLT section, to permit unwinding + // through a PLT. The FDE data should start with 8 bytes of zero, + // which will be replaced by a 4 byte PC relative reference to the + // address of PLT and a 4 byte size of PLT. + void + add_ehframe_for_plt(Output_data* plt, const unsigned char* cie_data, + size_t cie_length, const unsigned char* fde_data, + size_t fde_length); + + // Remove all post-map unwind information for a PLT. + void + remove_ehframe_for_plt(Output_data* plt, const unsigned char* cie_data, + size_t cie_length); + + // Return the number of FDEs. + unsigned int + fde_count() const; + + protected: + // Set the final data size. + void + set_final_data_size(); + + // Return the output address for an input address. + bool + do_output_offset(const Relobj*, unsigned int shndx, + section_offset_type offset, + section_offset_type* poutput) const; + + // Write the data to the file. + void + do_write(Output_file*); + + // Write to a map file. + void + do_print_to_mapfile(Mapfile* mapfile) const + { mapfile->print_output_data(this, _("** eh_frame")); } + + private: + // The comparison routine for the CIE map. + struct Cie_less + { + bool + operator()(const Cie* cie1, const Cie* cie2) const + { return *cie1 < *cie2; } + }; + + // A set of unique CIEs. + typedef std::set Cie_offsets; + + // A list of unmergeable CIEs. + typedef std::vector Unmergeable_cie_offsets; + + // A mapping from offsets to CIEs. This is used while reading an + // input section. + typedef std::map Offsets_to_cie; + + // A list of CIEs, and a bool indicating whether the CIE is + // mergeable. + typedef std::vector > New_cies; + + // Skip an LEB128. + static bool + skip_leb128(const unsigned char**, const unsigned char*); + + // The implementation of add_ehframe_input_section. + template + bool + do_add_ehframe_input_section(Sized_relobj_file* object, + const unsigned char* symbols, + section_size_type symbols_size, + const unsigned char* symbol_names, + section_size_type symbol_names_size, + unsigned int shndx, + unsigned int reloc_shndx, + unsigned int reloc_type, + const unsigned char* pcontents, + section_size_type contents_len, + New_cies*); + + // Read a CIE. + template + bool + read_cie(Sized_relobj_file* object, + unsigned int shndx, + const unsigned char* symbols, + section_size_type symbols_size, + const unsigned char* symbol_names, + section_size_type symbol_names_size, + const unsigned char* pcontents, + const unsigned char* pcie, + const unsigned char* pcieend, + Track_relocs* relocs, + Offsets_to_cie* cies, + New_cies* new_cies); + + // Read an FDE. + template + bool + read_fde(Sized_relobj_file* object, + unsigned int shndx, + const unsigned char* symbols, + section_size_type symbols_size, + const unsigned char* pcontents, + unsigned int offset, + const unsigned char* pfde, + const unsigned char* pfdeend, + Track_relocs* relocs, + Offsets_to_cie* cies); + + // Template version of write function. + template + void + do_sized_write(unsigned char* oview); + + // The exception frame header, if any. + Eh_frame_hdr* eh_frame_hdr_; + // A mapping from all unique CIEs to their offset in the output + // file. + Cie_offsets cie_offsets_; + // A mapping from unmergeable CIEs to their offset in the output + // file. + Unmergeable_cie_offsets unmergeable_cie_offsets_; + // Whether we have created the mappings to the output section. + bool mappings_are_done_; + // The final data size. This is only set if mappings_are_done_ is + // true. + section_size_type final_data_size_; }; } // End namespace gold.