| // layout.cc -- lay out output file sections for gold |
| |
| // Copyright 2006, 2007 Free Software Foundation, Inc. |
| // Written by Ian Lance Taylor <iant@google.com>. |
| |
| // This file is part of gold. |
| |
| // This program is free software; you can redistribute it and/or modify |
| // it under the terms of the GNU General Public License as published by |
| // the Free Software Foundation; either version 3 of the License, or |
| // (at your option) any later version. |
| |
| // This program is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| |
| // You should have received a copy of the GNU General Public License |
| // along with this program; if not, write to the Free Software |
| // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| // MA 02110-1301, USA. |
| |
| #include "gold.h" |
| |
| #include <cstring> |
| #include <algorithm> |
| #include <iostream> |
| #include <utility> |
| |
| #include "parameters.h" |
| #include "output.h" |
| #include "symtab.h" |
| #include "dynobj.h" |
| #include "ehframe.h" |
| #include "layout.h" |
| |
| namespace gold |
| { |
| |
| // Layout_task_runner methods. |
| |
| // Lay out the sections. This is called after all the input objects |
| // have been read. |
| |
| void |
| Layout_task_runner::run(Workqueue* workqueue) |
| { |
| off_t file_size = this->layout_->finalize(this->input_objects_, |
| this->symtab_); |
| |
| // Now we know the final size of the output file and we know where |
| // each piece of information goes. |
| Output_file* of = new Output_file(this->options_, |
| this->input_objects_->target()); |
| of->open(file_size); |
| |
| // Queue up the final set of tasks. |
| gold::queue_final_tasks(this->options_, this->input_objects_, |
| this->symtab_, this->layout_, workqueue, of); |
| } |
| |
| // Layout methods. |
| |
| Layout::Layout(const General_options& options) |
| : options_(options), namepool_(), sympool_(), dynpool_(), signatures_(), |
| section_name_map_(), segment_list_(), section_list_(), |
| unattached_section_list_(), special_output_list_(), |
| tls_segment_(NULL), symtab_section_(NULL), |
| dynsym_section_(NULL), dynamic_section_(NULL), dynamic_data_(NULL), |
| eh_frame_section_(NULL), output_file_size_(-1), |
| input_requires_executable_stack_(false), |
| input_with_gnu_stack_note_(false), |
| input_without_gnu_stack_note_(false) |
| { |
| // Make space for more than enough segments for a typical file. |
| // This is just for efficiency--it's OK if we wind up needing more. |
| this->segment_list_.reserve(12); |
| |
| // We expect three unattached Output_data objects: the file header, |
| // the segment headers, and the section headers. |
| this->special_output_list_.reserve(3); |
| } |
| |
| // Hash a key we use to look up an output section mapping. |
| |
| size_t |
| Layout::Hash_key::operator()(const Layout::Key& k) const |
| { |
| return k.first + k.second.first + k.second.second; |
| } |
| |
| // Return whether PREFIX is a prefix of STR. |
| |
| static inline bool |
| is_prefix_of(const char* prefix, const char* str) |
| { |
| return strncmp(prefix, str, strlen(prefix)) == 0; |
| } |
| |
| // Whether to include this section in the link. |
| |
| template<int size, bool big_endian> |
| bool |
| Layout::include_section(Object*, const char* name, |
| const elfcpp::Shdr<size, big_endian>& shdr) |
| { |
| // Some section types are never linked. Some are only linked when |
| // doing a relocateable link. |
| switch (shdr.get_sh_type()) |
| { |
| case elfcpp::SHT_NULL: |
| case elfcpp::SHT_SYMTAB: |
| case elfcpp::SHT_DYNSYM: |
| case elfcpp::SHT_STRTAB: |
| case elfcpp::SHT_HASH: |
| case elfcpp::SHT_DYNAMIC: |
| case elfcpp::SHT_SYMTAB_SHNDX: |
| return false; |
| |
| case elfcpp::SHT_RELA: |
| case elfcpp::SHT_REL: |
| case elfcpp::SHT_GROUP: |
| return parameters->output_is_object(); |
| |
| case elfcpp::SHT_PROGBITS: |
| if (parameters->strip_debug() |
| && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) |
| { |
| // Debugging sections can only be recognized by name. |
| if (is_prefix_of(".debug", name) |
| || is_prefix_of(".gnu.linkonce.wi.", name) |
| || is_prefix_of(".line", name) |
| || is_prefix_of(".stab", name)) |
| return false; |
| } |
| return true; |
| |
| default: |
| return true; |
| } |
| } |
| |
| // Return an output section named NAME, or NULL if there is none. |
| |
| Output_section* |
| Layout::find_output_section(const char* name) const |
| { |
| for (Section_name_map::const_iterator p = this->section_name_map_.begin(); |
| p != this->section_name_map_.end(); |
| ++p) |
| if (strcmp(p->second->name(), name) == 0) |
| return p->second; |
| return NULL; |
| } |
| |
| // Return an output segment of type TYPE, with segment flags SET set |
| // and segment flags CLEAR clear. Return NULL if there is none. |
| |
| Output_segment* |
| Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set, |
| elfcpp::Elf_Word clear) const |
| { |
| for (Segment_list::const_iterator p = this->segment_list_.begin(); |
| p != this->segment_list_.end(); |
| ++p) |
| if (static_cast<elfcpp::PT>((*p)->type()) == type |
| && ((*p)->flags() & set) == set |
| && ((*p)->flags() & clear) == 0) |
| return *p; |
| return NULL; |
| } |
| |
| // Return the output section to use for section NAME with type TYPE |
| // and section flags FLAGS. |
| |
| Output_section* |
| Layout::get_output_section(const char* name, Stringpool::Key name_key, |
| elfcpp::Elf_Word type, elfcpp::Elf_Xword flags) |
| { |
| // We should ignore some flags. |
| flags &= ~ (elfcpp::SHF_INFO_LINK |
| | elfcpp::SHF_LINK_ORDER |
| | elfcpp::SHF_GROUP |
| | elfcpp::SHF_MERGE |
| | elfcpp::SHF_STRINGS); |
| |
| const Key key(name_key, std::make_pair(type, flags)); |
| const std::pair<Key, Output_section*> v(key, NULL); |
| std::pair<Section_name_map::iterator, bool> ins( |
| this->section_name_map_.insert(v)); |
| |
| if (!ins.second) |
| return ins.first->second; |
| else |
| { |
| // This is the first time we've seen this name/type/flags |
| // combination. |
| Output_section* os = this->make_output_section(name, type, flags); |
| ins.first->second = os; |
| return os; |
| } |
| } |
| |
| // Return the output section to use for input section SHNDX, with name |
| // NAME, with header HEADER, from object OBJECT. Set *OFF to the |
| // offset of this input section without the output section. |
| |
| template<int size, bool big_endian> |
| Output_section* |
| Layout::layout(Relobj* object, unsigned int shndx, const char* name, |
| const elfcpp::Shdr<size, big_endian>& shdr, off_t* off) |
| { |
| if (!this->include_section(object, name, shdr)) |
| return NULL; |
| |
| // If we are not doing a relocateable link, choose the name to use |
| // for the output section. |
| size_t len = strlen(name); |
| if (!parameters->output_is_object()) |
| name = Layout::output_section_name(name, &len); |
| |
| // FIXME: Handle SHF_OS_NONCONFORMING here. |
| |
| // Canonicalize the section name. |
| Stringpool::Key name_key; |
| name = this->namepool_.add_prefix(name, len, &name_key); |
| |
| // Find the output section. The output section is selected based on |
| // the section name, type, and flags. |
| Output_section* os = this->get_output_section(name, name_key, |
| shdr.get_sh_type(), |
| shdr.get_sh_flags()); |
| |
| // Special GNU handling of sections named .eh_frame. |
| if (!parameters->output_is_object() |
| && strcmp(name, ".eh_frame") == 0 |
| && shdr.get_sh_size() > 0 |
| && shdr.get_sh_type() == elfcpp::SHT_PROGBITS |
| && shdr.get_sh_flags() == elfcpp::SHF_ALLOC) |
| { |
| this->layout_eh_frame(object, shndx, name, shdr, os, off); |
| return os; |
| } |
| |
| // FIXME: Handle SHF_LINK_ORDER somewhere. |
| |
| *off = os->add_input_section(object, shndx, name, shdr); |
| |
| return os; |
| } |
| |
| // Special GNU handling of sections named .eh_frame. They will |
| // normally hold exception frame data. |
| |
| template<int size, bool big_endian> |
| void |
| Layout::layout_eh_frame(Relobj* object, |
| unsigned int shndx, |
| const char* name, |
| const elfcpp::Shdr<size, big_endian>& shdr, |
| Output_section* os, off_t* off) |
| { |
| if (this->eh_frame_section_ == NULL) |
| { |
| this->eh_frame_section_ = os; |
| |
| if (this->options_.create_eh_frame_hdr()) |
| { |
| Stringpool::Key hdr_name_key; |
| const char* hdr_name = this->namepool_.add(".eh_frame_hdr", |
| false, |
| &hdr_name_key); |
| Output_section* hdr_os = |
| this->get_output_section(hdr_name, hdr_name_key, |
| elfcpp::SHT_PROGBITS, |
| elfcpp::SHF_ALLOC); |
| |
| Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os); |
| hdr_os->add_output_section_data(hdr_posd); |
| |
| Output_segment* hdr_oseg = |
| new Output_segment(elfcpp::PT_GNU_EH_FRAME, elfcpp::PF_R); |
| this->segment_list_.push_back(hdr_oseg); |
| hdr_oseg->add_output_section(hdr_os, elfcpp::PF_R); |
| } |
| } |
| |
| gold_assert(this->eh_frame_section_ == os); |
| |
| *off = os->add_input_section(object, shndx, name, shdr); |
| } |
| |
| // Add POSD to an output section using NAME, TYPE, and FLAGS. |
| |
| void |
| Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type, |
| elfcpp::Elf_Xword flags, |
| Output_section_data* posd) |
| { |
| // Canonicalize the name. |
| Stringpool::Key name_key; |
| name = this->namepool_.add(name, true, &name_key); |
| |
| Output_section* os = this->get_output_section(name, name_key, type, flags); |
| os->add_output_section_data(posd); |
| } |
| |
| // Map section flags to segment flags. |
| |
| elfcpp::Elf_Word |
| Layout::section_flags_to_segment(elfcpp::Elf_Xword flags) |
| { |
| elfcpp::Elf_Word ret = elfcpp::PF_R; |
| if ((flags & elfcpp::SHF_WRITE) != 0) |
| ret |= elfcpp::PF_W; |
| if ((flags & elfcpp::SHF_EXECINSTR) != 0) |
| ret |= elfcpp::PF_X; |
| return ret; |
| } |
| |
| // Make a new Output_section, and attach it to segments as |
| // appropriate. |
| |
| Output_section* |
| Layout::make_output_section(const char* name, elfcpp::Elf_Word type, |
| elfcpp::Elf_Xword flags) |
| { |
| Output_section* os = new Output_section(name, type, flags); |
| this->section_list_.push_back(os); |
| |
| if ((flags & elfcpp::SHF_ALLOC) == 0) |
| this->unattached_section_list_.push_back(os); |
| else |
| { |
| // This output section goes into a PT_LOAD segment. |
| |
| elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags); |
| |
| // The only thing we really care about for PT_LOAD segments is |
| // whether or not they are writable, so that is how we search |
| // for them. People who need segments sorted on some other |
| // basis will have to wait until we implement a mechanism for |
| // them to describe the segments they want. |
| |
| Segment_list::const_iterator p; |
| for (p = this->segment_list_.begin(); |
| p != this->segment_list_.end(); |
| ++p) |
| { |
| if ((*p)->type() == elfcpp::PT_LOAD |
| && ((*p)->flags() & elfcpp::PF_W) == (seg_flags & elfcpp::PF_W)) |
| { |
| (*p)->add_output_section(os, seg_flags); |
| break; |
| } |
| } |
| |
| if (p == this->segment_list_.end()) |
| { |
| Output_segment* oseg = new Output_segment(elfcpp::PT_LOAD, |
| seg_flags); |
| this->segment_list_.push_back(oseg); |
| oseg->add_output_section(os, seg_flags); |
| } |
| |
| // If we see a loadable SHT_NOTE section, we create a PT_NOTE |
| // segment. |
| if (type == elfcpp::SHT_NOTE) |
| { |
| // See if we already have an equivalent PT_NOTE segment. |
| for (p = this->segment_list_.begin(); |
| p != segment_list_.end(); |
| ++p) |
| { |
| if ((*p)->type() == elfcpp::PT_NOTE |
| && (((*p)->flags() & elfcpp::PF_W) |
| == (seg_flags & elfcpp::PF_W))) |
| { |
| (*p)->add_output_section(os, seg_flags); |
| break; |
| } |
| } |
| |
| if (p == this->segment_list_.end()) |
| { |
| Output_segment* oseg = new Output_segment(elfcpp::PT_NOTE, |
| seg_flags); |
| this->segment_list_.push_back(oseg); |
| oseg->add_output_section(os, seg_flags); |
| } |
| } |
| |
| // If we see a loadable SHF_TLS section, we create a PT_TLS |
| // segment. There can only be one such segment. |
| if ((flags & elfcpp::SHF_TLS) != 0) |
| { |
| if (this->tls_segment_ == NULL) |
| { |
| this->tls_segment_ = new Output_segment(elfcpp::PT_TLS, |
| seg_flags); |
| this->segment_list_.push_back(this->tls_segment_); |
| } |
| this->tls_segment_->add_output_section(os, seg_flags); |
| } |
| } |
| |
| return os; |
| } |
| |
| // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK |
| // is whether we saw a .note.GNU-stack section in the object file. |
| // GNU_STACK_FLAGS is the section flags. The flags give the |
| // protection required for stack memory. We record this in an |
| // executable as a PT_GNU_STACK segment. If an object file does not |
| // have a .note.GNU-stack segment, we must assume that it is an old |
| // object. On some targets that will force an executable stack. |
| |
| void |
| Layout::layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags) |
| { |
| if (!seen_gnu_stack) |
| this->input_without_gnu_stack_note_ = true; |
| else |
| { |
| this->input_with_gnu_stack_note_ = true; |
| if ((gnu_stack_flags & elfcpp::SHF_EXECINSTR) != 0) |
| this->input_requires_executable_stack_ = true; |
| } |
| } |
| |
| // Create the dynamic sections which are needed before we read the |
| // relocs. |
| |
| void |
| Layout::create_initial_dynamic_sections(const Input_objects* input_objects, |
| Symbol_table* symtab) |
| { |
| if (parameters->doing_static_link()) |
| return; |
| |
| const char* dynamic_name = this->namepool_.add(".dynamic", false, NULL); |
| this->dynamic_section_ = this->make_output_section(dynamic_name, |
| elfcpp::SHT_DYNAMIC, |
| (elfcpp::SHF_ALLOC |
| | elfcpp::SHF_WRITE)); |
| |
| symtab->define_in_output_data(input_objects->target(), "_DYNAMIC", NULL, |
| this->dynamic_section_, 0, 0, |
| elfcpp::STT_OBJECT, elfcpp::STB_LOCAL, |
| elfcpp::STV_HIDDEN, 0, false, false); |
| |
| this->dynamic_data_ = new Output_data_dynamic(&this->dynpool_); |
| |
| this->dynamic_section_->add_output_section_data(this->dynamic_data_); |
| } |
| |
| // For each output section whose name can be represented as C symbol, |
| // define __start and __stop symbols for the section. This is a GNU |
| // extension. |
| |
| void |
| Layout::define_section_symbols(Symbol_table* symtab, const Target* target) |
| { |
| for (Section_list::const_iterator p = this->section_list_.begin(); |
| p != this->section_list_.end(); |
| ++p) |
| { |
| const char* const name = (*p)->name(); |
| if (name[strspn(name, |
| ("0123456789" |
| "ABCDEFGHIJKLMNOPWRSTUVWXYZ" |
| "abcdefghijklmnopqrstuvwxyz" |
| "_"))] |
| == '\0') |
| { |
| const std::string name_string(name); |
| const std::string start_name("__start_" + name_string); |
| const std::string stop_name("__stop_" + name_string); |
| |
| symtab->define_in_output_data(target, |
| start_name.c_str(), |
| NULL, // version |
| *p, |
| 0, // value |
| 0, // symsize |
| elfcpp::STT_NOTYPE, |
| elfcpp::STB_GLOBAL, |
| elfcpp::STV_DEFAULT, |
| 0, // nonvis |
| false, // offset_is_from_end |
| false); // only_if_ref |
| |
| symtab->define_in_output_data(target, |
| stop_name.c_str(), |
| NULL, // version |
| *p, |
| 0, // value |
| 0, // symsize |
| elfcpp::STT_NOTYPE, |
| elfcpp::STB_GLOBAL, |
| elfcpp::STV_DEFAULT, |
| 0, // nonvis |
| true, // offset_is_from_end |
| false); // only_if_ref |
| } |
| } |
| } |
| |
| // Find the first read-only PT_LOAD segment, creating one if |
| // necessary. |
| |
| Output_segment* |
| Layout::find_first_load_seg() |
| { |
| for (Segment_list::const_iterator p = this->segment_list_.begin(); |
| p != this->segment_list_.end(); |
| ++p) |
| { |
| if ((*p)->type() == elfcpp::PT_LOAD |
| && ((*p)->flags() & elfcpp::PF_R) != 0 |
| && ((*p)->flags() & elfcpp::PF_W) == 0) |
| return *p; |
| } |
| |
| Output_segment* load_seg = new Output_segment(elfcpp::PT_LOAD, elfcpp::PF_R); |
| this->segment_list_.push_back(load_seg); |
| return load_seg; |
| } |
| |
| // Finalize the layout. When this is called, we have created all the |
| // output sections and all the output segments which are based on |
| // input sections. We have several things to do, and we have to do |
| // them in the right order, so that we get the right results correctly |
| // and efficiently. |
| |
| // 1) Finalize the list of output segments and create the segment |
| // table header. |
| |
| // 2) Finalize the dynamic symbol table and associated sections. |
| |
| // 3) Determine the final file offset of all the output segments. |
| |
| // 4) Determine the final file offset of all the SHF_ALLOC output |
| // sections. |
| |
| // 5) Create the symbol table sections and the section name table |
| // section. |
| |
| // 6) Finalize the symbol table: set symbol values to their final |
| // value and make a final determination of which symbols are going |
| // into the output symbol table. |
| |
| // 7) Create the section table header. |
| |
| // 8) Determine the final file offset of all the output sections which |
| // are not SHF_ALLOC, including the section table header. |
| |
| // 9) Finalize the ELF file header. |
| |
| // This function returns the size of the output file. |
| |
| off_t |
| Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab) |
| { |
| Target* const target = input_objects->target(); |
| |
| target->finalize_sections(this); |
| |
| this->create_gold_note(); |
| this->create_executable_stack_info(target); |
| |
| Output_segment* phdr_seg = NULL; |
| if (!parameters->doing_static_link()) |
| { |
| // There was a dynamic object in the link. We need to create |
| // some information for the dynamic linker. |
| |
| // Create the PT_PHDR segment which will hold the program |
| // headers. |
| phdr_seg = new Output_segment(elfcpp::PT_PHDR, elfcpp::PF_R); |
| this->segment_list_.push_back(phdr_seg); |
| |
| // Create the dynamic symbol table, including the hash table. |
| Output_section* dynstr; |
| std::vector<Symbol*> dynamic_symbols; |
| unsigned int local_dynamic_count; |
| Versions versions; |
| this->create_dynamic_symtab(target, symtab, &dynstr, |
| &local_dynamic_count, &dynamic_symbols, |
| &versions); |
| |
| // Create the .interp section to hold the name of the |
| // interpreter, and put it in a PT_INTERP segment. |
| if (!parameters->output_is_shared()) |
| this->create_interp(target); |
| |
| // Finish the .dynamic section to hold the dynamic data, and put |
| // it in a PT_DYNAMIC segment. |
| this->finish_dynamic_section(input_objects, symtab); |
| |
| // We should have added everything we need to the dynamic string |
| // table. |
| this->dynpool_.set_string_offsets(); |
| |
| // Create the version sections. We can't do this until the |
| // dynamic string table is complete. |
| this->create_version_sections(&versions, symtab, local_dynamic_count, |
| dynamic_symbols, dynstr); |
| } |
| |
| // FIXME: Handle PT_GNU_STACK. |
| |
| Output_segment* load_seg = this->find_first_load_seg(); |
| |
| // Lay out the segment headers. |
| Output_segment_headers* segment_headers; |
| segment_headers = new Output_segment_headers(this->segment_list_); |
| load_seg->add_initial_output_data(segment_headers); |
| this->special_output_list_.push_back(segment_headers); |
| if (phdr_seg != NULL) |
| phdr_seg->add_initial_output_data(segment_headers); |
| |
| // Lay out the file header. |
| Output_file_header* file_header; |
| file_header = new Output_file_header(target, symtab, segment_headers); |
| load_seg->add_initial_output_data(file_header); |
| this->special_output_list_.push_back(file_header); |
| |
| // We set the output section indexes in set_segment_offsets and |
| // set_section_offsets. |
| unsigned int shndx = 1; |
| |
| // Set the file offsets of all the segments, and all the sections |
| // they contain. |
| off_t off = this->set_segment_offsets(target, load_seg, &shndx); |
| |
| // Set the file offsets of all the data sections not associated with |
| // segments. This makes sure that debug sections have their offsets |
| // before symbols are finalized. |
| off = this->set_section_offsets(off, &shndx, true); |
| |
| // Create the symbol table sections. |
| this->create_symtab_sections(input_objects, symtab, &off); |
| |
| // Create the .shstrtab section. |
| Output_section* shstrtab_section = this->create_shstrtab(); |
| |
| // Set the file offsets of all the non-data sections not associated with |
| // segments. |
| off = this->set_section_offsets(off, &shndx, false); |
| |
| // Create the section table header. |
| Output_section_headers* oshdrs = this->create_shdrs(&off); |
| |
| file_header->set_section_info(oshdrs, shstrtab_section); |
| |
| // Now we know exactly where everything goes in the output file. |
| Output_data::layout_complete(); |
| |
| this->output_file_size_ = off; |
| |
| return off; |
| } |
| |
| // Create a .note section for an executable or shared library. This |
| // records the version of gold used to create the binary. |
| |
| void |
| Layout::create_gold_note() |
| { |
| if (parameters->output_is_object()) |
| return; |
| |
| // Authorities all agree that the values in a .note field should |
| // be aligned on 4-byte boundaries for 32-bit binaries. However, |
| // they differ on what the alignment is for 64-bit binaries. |
| // The GABI says unambiguously they take 8-byte alignment: |
| // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section |
| // Other documentation says alignment should always be 4 bytes: |
| // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format |
| // GNU ld and GNU readelf both support the latter (at least as of |
| // version 2.16.91), and glibc always generates the latter for |
| // .note.ABI-tag (as of version 1.6), so that's the one we go with |
| // here. |
| #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default. |
| const int size = parameters->get_size(); |
| #else |
| const int size = 32; |
| #endif |
| |
| // The contents of the .note section. |
| const char* name = "GNU"; |
| std::string desc(std::string("gold ") + gold::get_version_string()); |
| size_t namesz = strlen(name) + 1; |
| size_t aligned_namesz = align_address(namesz, size / 8); |
| size_t descsz = desc.length() + 1; |
| size_t aligned_descsz = align_address(descsz, size / 8); |
| const int note_type = 4; |
| |
| size_t notesz = 3 * (size / 8) + aligned_namesz + aligned_descsz; |
| |
| unsigned char buffer[128]; |
| gold_assert(sizeof buffer >= notesz); |
| memset(buffer, 0, notesz); |
| |
| bool is_big_endian = parameters->is_big_endian(); |
| |
| if (size == 32) |
| { |
| if (!is_big_endian) |
| { |
| elfcpp::Swap<32, false>::writeval(buffer, namesz); |
| elfcpp::Swap<32, false>::writeval(buffer + 4, descsz); |
| elfcpp::Swap<32, false>::writeval(buffer + 8, note_type); |
| } |
| else |
| { |
| elfcpp::Swap<32, true>::writeval(buffer, namesz); |
| elfcpp::Swap<32, true>::writeval(buffer + 4, descsz); |
| elfcpp::Swap<32, true>::writeval(buffer + 8, note_type); |
| } |
| } |
| else if (size == 64) |
| { |
| if (!is_big_endian) |
| { |
| elfcpp::Swap<64, false>::writeval(buffer, namesz); |
| elfcpp::Swap<64, false>::writeval(buffer + 8, descsz); |
| elfcpp::Swap<64, false>::writeval(buffer + 16, note_type); |
| } |
| else |
| { |
| elfcpp::Swap<64, true>::writeval(buffer, namesz); |
| elfcpp::Swap<64, true>::writeval(buffer + 8, descsz); |
| elfcpp::Swap<64, true>::writeval(buffer + 16, note_type); |
| } |
| } |
| else |
| gold_unreachable(); |
| |
| memcpy(buffer + 3 * (size / 8), name, namesz); |
| memcpy(buffer + 3 * (size / 8) + aligned_namesz, desc.data(), descsz); |
| |
| const char* note_name = this->namepool_.add(".note", false, NULL); |
| Output_section* os = this->make_output_section(note_name, |
| elfcpp::SHT_NOTE, |
| 0); |
| Output_section_data* posd = new Output_data_const(buffer, notesz, |
| size / 8); |
| os->add_output_section_data(posd); |
| } |
| |
| // Record whether the stack should be executable. This can be set |
| // from the command line using the -z execstack or -z noexecstack |
| // options. Otherwise, if any input file has a .note.GNU-stack |
| // section with the SHF_EXECINSTR flag set, the stack should be |
| // executable. Otherwise, if at least one input file a |
| // .note.GNU-stack section, and some input file has no .note.GNU-stack |
| // section, we use the target default for whether the stack should be |
| // executable. Otherwise, we don't generate a stack note. When |
| // generating a object file, we create a .note.GNU-stack section with |
| // the appropriate marking. When generating an executable or shared |
| // library, we create a PT_GNU_STACK segment. |
| |
| void |
| Layout::create_executable_stack_info(const Target* target) |
| { |
| bool is_stack_executable; |
| if (this->options_.is_execstack_set()) |
| is_stack_executable = this->options_.is_stack_executable(); |
| else if (!this->input_with_gnu_stack_note_) |
| return; |
| else |
| { |
| if (this->input_requires_executable_stack_) |
| is_stack_executable = true; |
| else if (this->input_without_gnu_stack_note_) |
| is_stack_executable = target->is_default_stack_executable(); |
| else |
| is_stack_executable = false; |
| } |
| |
| if (parameters->output_is_object()) |
| { |
| const char* name = this->namepool_.add(".note.GNU-stack", false, NULL); |
| elfcpp::Elf_Xword flags = 0; |
| if (is_stack_executable) |
| flags |= elfcpp::SHF_EXECINSTR; |
| this->make_output_section(name, elfcpp::SHT_PROGBITS, flags); |
| } |
| else |
| { |
| int flags = elfcpp::PF_R | elfcpp::PF_W; |
| if (is_stack_executable) |
| flags |= elfcpp::PF_X; |
| Output_segment* oseg = new Output_segment(elfcpp::PT_GNU_STACK, flags); |
| this->segment_list_.push_back(oseg); |
| } |
| } |
| |
| // Return whether SEG1 should be before SEG2 in the output file. This |
| // is based entirely on the segment type and flags. When this is |
| // called the segment addresses has normally not yet been set. |
| |
| bool |
| Layout::segment_precedes(const Output_segment* seg1, |
| const Output_segment* seg2) |
| { |
| elfcpp::Elf_Word type1 = seg1->type(); |
| elfcpp::Elf_Word type2 = seg2->type(); |
| |
| // The single PT_PHDR segment is required to precede any loadable |
| // segment. We simply make it always first. |
| if (type1 == elfcpp::PT_PHDR) |
| { |
| gold_assert(type2 != elfcpp::PT_PHDR); |
| return true; |
| } |
| if (type2 == elfcpp::PT_PHDR) |
| return false; |
| |
| // The single PT_INTERP segment is required to precede any loadable |
| // segment. We simply make it always second. |
| if (type1 == elfcpp::PT_INTERP) |
| { |
| gold_assert(type2 != elfcpp::PT_INTERP); |
| return true; |
| } |
| if (type2 == elfcpp::PT_INTERP) |
| return false; |
| |
| // We then put PT_LOAD segments before any other segments. |
| if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD) |
| return true; |
| if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD) |
| return false; |
| |
| // We put the PT_TLS segment last, because that is where the dynamic |
| // linker expects to find it (this is just for efficiency; other |
| // positions would also work correctly). |
| if (type1 == elfcpp::PT_TLS && type2 != elfcpp::PT_TLS) |
| return false; |
| if (type2 == elfcpp::PT_TLS && type1 != elfcpp::PT_TLS) |
| return true; |
| |
| const elfcpp::Elf_Word flags1 = seg1->flags(); |
| const elfcpp::Elf_Word flags2 = seg2->flags(); |
| |
| // The order of non-PT_LOAD segments is unimportant. We simply sort |
| // by the numeric segment type and flags values. There should not |
| // be more than one segment with the same type and flags. |
| if (type1 != elfcpp::PT_LOAD) |
| { |
| if (type1 != type2) |
| return type1 < type2; |
| gold_assert(flags1 != flags2); |
| return flags1 < flags2; |
| } |
| |
| // We sort PT_LOAD segments based on the flags. Readonly segments |
| // come before writable segments. Then executable segments come |
| // before non-executable segments. Then the unlikely case of a |
| // non-readable segment comes before the normal case of a readable |
| // segment. If there are multiple segments with the same type and |
| // flags, we require that the address be set, and we sort by |
| // virtual address and then physical address. |
| if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W)) |
| return (flags1 & elfcpp::PF_W) == 0; |
| if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X)) |
| return (flags1 & elfcpp::PF_X) != 0; |
| if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R)) |
| return (flags1 & elfcpp::PF_R) == 0; |
| |
| uint64_t vaddr1 = seg1->vaddr(); |
| uint64_t vaddr2 = seg2->vaddr(); |
| if (vaddr1 != vaddr2) |
| return vaddr1 < vaddr2; |
| |
| uint64_t paddr1 = seg1->paddr(); |
| uint64_t paddr2 = seg2->paddr(); |
| gold_assert(paddr1 != paddr2); |
| return paddr1 < paddr2; |
| } |
| |
| // Set the file offsets of all the segments, and all the sections they |
| // contain. They have all been created. LOAD_SEG must be be laid out |
| // first. Return the offset of the data to follow. |
| |
| off_t |
| Layout::set_segment_offsets(const Target* target, Output_segment* load_seg, |
| unsigned int *pshndx) |
| { |
| // Sort them into the final order. |
| std::sort(this->segment_list_.begin(), this->segment_list_.end(), |
| Layout::Compare_segments()); |
| |
| // Find the PT_LOAD segments, and set their addresses and offsets |
| // and their section's addresses and offsets. |
| uint64_t addr; |
| if (options_.user_set_text_segment_address()) |
| addr = options_.text_segment_address(); |
| else |
| addr = target->default_text_segment_address(); |
| off_t off = 0; |
| bool was_readonly = false; |
| for (Segment_list::iterator p = this->segment_list_.begin(); |
| p != this->segment_list_.end(); |
| ++p) |
| { |
| if ((*p)->type() == elfcpp::PT_LOAD) |
| { |
| if (load_seg != NULL && load_seg != *p) |
| gold_unreachable(); |
| load_seg = NULL; |
| |
| // If the last segment was readonly, and this one is not, |
| // then skip the address forward one page, maintaining the |
| // same position within the page. This lets us store both |
| // segments overlapping on a single page in the file, but |
| // the loader will put them on different pages in memory. |
| |
| uint64_t orig_addr = addr; |
| uint64_t orig_off = off; |
| |
| uint64_t aligned_addr = addr; |
| uint64_t abi_pagesize = target->abi_pagesize(); |
| |
| // FIXME: This should depend on the -n and -N options. |
| (*p)->set_minimum_addralign(target->common_pagesize()); |
| |
| if (was_readonly && ((*p)->flags() & elfcpp::PF_W) != 0) |
| { |
| uint64_t align = (*p)->addralign(); |
| |
| addr = align_address(addr, align); |
| aligned_addr = addr; |
| if ((addr & (abi_pagesize - 1)) != 0) |
| addr = addr + abi_pagesize; |
| } |
| |
| unsigned int shndx_hold = *pshndx; |
| off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); |
| uint64_t new_addr = (*p)->set_section_addresses(addr, &off, pshndx); |
| |
| // Now that we know the size of this segment, we may be able |
| // to save a page in memory, at the cost of wasting some |
| // file space, by instead aligning to the start of a new |
| // page. Here we use the real machine page size rather than |
| // the ABI mandated page size. |
| |
| if (aligned_addr != addr) |
| { |
| uint64_t common_pagesize = target->common_pagesize(); |
| uint64_t first_off = (common_pagesize |
| - (aligned_addr |
| & (common_pagesize - 1))); |
| uint64_t last_off = new_addr & (common_pagesize - 1); |
| if (first_off > 0 |
| && last_off > 0 |
| && ((aligned_addr & ~ (common_pagesize - 1)) |
| != (new_addr & ~ (common_pagesize - 1))) |
| && first_off + last_off <= common_pagesize) |
| { |
| *pshndx = shndx_hold; |
| addr = align_address(aligned_addr, common_pagesize); |
| off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); |
| new_addr = (*p)->set_section_addresses(addr, &off, pshndx); |
| } |
| } |
| |
| addr = new_addr; |
| |
| if (((*p)->flags() & elfcpp::PF_W) == 0) |
| was_readonly = true; |
| } |
| } |
| |
| // Handle the non-PT_LOAD segments, setting their offsets from their |
| // section's offsets. |
| for (Segment_list::iterator p = this->segment_list_.begin(); |
| p != this->segment_list_.end(); |
| ++p) |
| { |
| if ((*p)->type() != elfcpp::PT_LOAD) |
| (*p)->set_offset(); |
| } |
| |
| return off; |
| } |
| |
| // Set the file offset of all the sections not associated with a |
| // segment. |
| |
| off_t |
| Layout::set_section_offsets(off_t off, |
| unsigned int* pshndx, |
| bool do_bits_sections) |
| { |
| for (Section_list::iterator p = this->unattached_section_list_.begin(); |
| p != this->unattached_section_list_.end(); |
| ++p) |
| { |
| bool is_bits_section = ((*p)->type() == elfcpp::SHT_PROGBITS |
| || (*p)->type() == elfcpp::SHT_NOBITS); |
| if (is_bits_section != do_bits_sections) |
| continue; |
| (*p)->set_out_shndx(*pshndx); |
| ++*pshndx; |
| if ((*p)->offset() != -1) |
| continue; |
| off = align_address(off, (*p)->addralign()); |
| (*p)->set_address(0, off); |
| off += (*p)->data_size(); |
| } |
| return off; |
| } |
| |
| // Create the symbol table sections. Here we also set the final |
| // values of the symbols. At this point all the loadable sections are |
| // fully laid out. |
| |
| void |
| Layout::create_symtab_sections(const Input_objects* input_objects, |
| Symbol_table* symtab, |
| off_t* poff) |
| { |
| int symsize; |
| unsigned int align; |
| if (parameters->get_size() == 32) |
| { |
| symsize = elfcpp::Elf_sizes<32>::sym_size; |
| align = 4; |
| } |
| else if (parameters->get_size() == 64) |
| { |
| symsize = elfcpp::Elf_sizes<64>::sym_size; |
| align = 8; |
| } |
| else |
| gold_unreachable(); |
| |
| off_t off = *poff; |
| off = align_address(off, align); |
| off_t startoff = off; |
| |
| // Save space for the dummy symbol at the start of the section. We |
| // never bother to write this out--it will just be left as zero. |
| off += symsize; |
| unsigned int local_symbol_index = 1; |
| |
| // Add STT_SECTION symbols for each Output section which needs one. |
| for (Section_list::iterator p = this->section_list_.begin(); |
| p != this->section_list_.end(); |
| ++p) |
| { |
| if (!(*p)->needs_symtab_index()) |
| (*p)->set_symtab_index(-1U); |
| else |
| { |
| (*p)->set_symtab_index(local_symbol_index); |
| ++local_symbol_index; |
| off += symsize; |
| } |
| } |
| |
| for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); |
| p != input_objects->relobj_end(); |
| ++p) |
| { |
| Task_lock_obj<Object> tlo(**p); |
| unsigned int index = (*p)->finalize_local_symbols(local_symbol_index, |
| off, |
| &this->sympool_); |
| off += (index - local_symbol_index) * symsize; |
| local_symbol_index = index; |
| } |
| |
| unsigned int local_symcount = local_symbol_index; |
| gold_assert(local_symcount * symsize == off - startoff); |
| |
| off_t dynoff; |
| size_t dyn_global_index; |
| size_t dyncount; |
| if (this->dynsym_section_ == NULL) |
| { |
| dynoff = 0; |
| dyn_global_index = 0; |
| dyncount = 0; |
| } |
| else |
| { |
| dyn_global_index = this->dynsym_section_->info(); |
| off_t locsize = dyn_global_index * this->dynsym_section_->entsize(); |
| dynoff = this->dynsym_section_->offset() + locsize; |
| dyncount = (this->dynsym_section_->data_size() - locsize) / symsize; |
| gold_assert(static_cast<off_t>(dyncount * symsize) |
| == this->dynsym_section_->data_size() - locsize); |
| } |
| |
| off = symtab->finalize(local_symcount, off, dynoff, dyn_global_index, |
| dyncount, &this->sympool_); |
| |
| if (!parameters->strip_all()) |
| { |
| this->sympool_.set_string_offsets(); |
| |
| const char* symtab_name = this->namepool_.add(".symtab", false, NULL); |
| Output_section* osymtab = this->make_output_section(symtab_name, |
| elfcpp::SHT_SYMTAB, |
| 0); |
| this->symtab_section_ = osymtab; |
| |
| Output_section_data* pos = new Output_data_space(off - startoff, |
| align); |
| osymtab->add_output_section_data(pos); |
| |
| const char* strtab_name = this->namepool_.add(".strtab", false, NULL); |
| Output_section* ostrtab = this->make_output_section(strtab_name, |
| elfcpp::SHT_STRTAB, |
| 0); |
| |
| Output_section_data* pstr = new Output_data_strtab(&this->sympool_); |
| ostrtab->add_output_section_data(pstr); |
| |
| osymtab->set_address(0, startoff); |
| osymtab->set_link_section(ostrtab); |
| osymtab->set_info(local_symcount); |
| osymtab->set_entsize(symsize); |
| |
| *poff = off; |
| } |
| } |
| |
| // Create the .shstrtab section, which holds the names of the |
| // sections. At the time this is called, we have created all the |
| // output sections except .shstrtab itself. |
| |
| Output_section* |
| Layout::create_shstrtab() |
| { |
| // FIXME: We don't need to create a .shstrtab section if we are |
| // stripping everything. |
| |
| const char* name = this->namepool_.add(".shstrtab", false, NULL); |
| |
| this->namepool_.set_string_offsets(); |
| |
| Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0); |
| |
| Output_section_data* posd = new Output_data_strtab(&this->namepool_); |
| os->add_output_section_data(posd); |
| |
| return os; |
| } |
| |
| // Create the section headers. SIZE is 32 or 64. OFF is the file |
| // offset. |
| |
| Output_section_headers* |
| Layout::create_shdrs(off_t* poff) |
| { |
| Output_section_headers* oshdrs; |
| oshdrs = new Output_section_headers(this, |
| &this->segment_list_, |
| &this->unattached_section_list_, |
| &this->namepool_); |
| off_t off = align_address(*poff, oshdrs->addralign()); |
| oshdrs->set_address(0, off); |
| off += oshdrs->data_size(); |
| *poff = off; |
| this->special_output_list_.push_back(oshdrs); |
| return oshdrs; |
| } |
| |
| // Create the dynamic symbol table. |
| |
| void |
| Layout::create_dynamic_symtab(const Target* target, Symbol_table* symtab, |
| Output_section **pdynstr, |
| unsigned int* plocal_dynamic_count, |
| std::vector<Symbol*>* pdynamic_symbols, |
| Versions* pversions) |
| { |
| // Count all the symbols in the dynamic symbol table, and set the |
| // dynamic symbol indexes. |
| |
| // Skip symbol 0, which is always all zeroes. |
| unsigned int index = 1; |
| |
| // Add STT_SECTION symbols for each Output section which needs one. |
| for (Section_list::iterator p = this->section_list_.begin(); |
| p != this->section_list_.end(); |
| ++p) |
| { |
| if (!(*p)->needs_dynsym_index()) |
| (*p)->set_dynsym_index(-1U); |
| else |
| { |
| (*p)->set_dynsym_index(index); |
| ++index; |
| } |
| } |
| |
| // FIXME: Some targets apparently require local symbols in the |
| // dynamic symbol table. Here is where we will have to count them, |
| // and set the dynamic symbol indexes, and add the names to |
| // this->dynpool_. |
| |
| unsigned int local_symcount = index; |
| *plocal_dynamic_count = local_symcount; |
| |
| // FIXME: We have to tell set_dynsym_indexes whether the |
| // -E/--export-dynamic option was used. |
| index = symtab->set_dynsym_indexes(target, index, pdynamic_symbols, |
| &this->dynpool_, pversions); |
| |
| int symsize; |
| unsigned int align; |
| const int size = parameters->get_size(); |
| if (size == 32) |
| { |
| symsize = elfcpp::Elf_sizes<32>::sym_size; |
| align = 4; |
| } |
| else if (size == 64) |
| { |
| symsize = elfcpp::Elf_sizes<64>::sym_size; |
| align = 8; |
| } |
| else |
| gold_unreachable(); |
| |
| // Create the dynamic symbol table section. |
| |
| const char* dynsym_name = this->namepool_.add(".dynsym", false, NULL); |
| Output_section* dynsym = this->make_output_section(dynsym_name, |
| elfcpp::SHT_DYNSYM, |
| elfcpp::SHF_ALLOC); |
| |
| Output_section_data* odata = new Output_data_space(index * symsize, |
| align); |
| dynsym->add_output_section_data(odata); |
| |
| dynsym->set_info(local_symcount); |
| dynsym->set_entsize(symsize); |
| dynsym->set_addralign(align); |
| |
| this->dynsym_section_ = dynsym; |
| |
| Output_data_dynamic* const odyn = this->dynamic_data_; |
| odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym); |
| odyn->add_constant(elfcpp::DT_SYMENT, symsize); |
| |
| // Create the dynamic string table section. |
| |
| const char* dynstr_name = this->namepool_.add(".dynstr", false, NULL); |
| Output_section* dynstr = this->make_output_section(dynstr_name, |
| elfcpp::SHT_STRTAB, |
| elfcpp::SHF_ALLOC); |
| |
| Output_section_data* strdata = new Output_data_strtab(&this->dynpool_); |
| dynstr->add_output_section_data(strdata); |
| |
| dynsym->set_link_section(dynstr); |
| this->dynamic_section_->set_link_section(dynstr); |
| |
| odyn->add_section_address(elfcpp::DT_STRTAB, dynstr); |
| odyn->add_section_size(elfcpp::DT_STRSZ, dynstr); |
| |
| *pdynstr = dynstr; |
| |
| // Create the hash tables. |
| |
| // FIXME: We need an option to create a GNU hash table. |
| |
| unsigned char* phash; |
| unsigned int hashlen; |
| Dynobj::create_elf_hash_table(*pdynamic_symbols, local_symcount, |
| &phash, &hashlen); |
| |
| const char* hash_name = this->namepool_.add(".hash", false, NULL); |
| Output_section* hashsec = this->make_output_section(hash_name, |
| elfcpp::SHT_HASH, |
| elfcpp::SHF_ALLOC); |
| |
| Output_section_data* hashdata = new Output_data_const_buffer(phash, |
| hashlen, |
| align); |
| hashsec->add_output_section_data(hashdata); |
| |
| hashsec->set_link_section(dynsym); |
| hashsec->set_entsize(4); |
| |
| odyn->add_section_address(elfcpp::DT_HASH, hashsec); |
| } |
| |
| // Create the version sections. |
| |
| void |
| Layout::create_version_sections(const Versions* versions, |
| const Symbol_table* symtab, |
| unsigned int local_symcount, |
| const std::vector<Symbol*>& dynamic_symbols, |
| const Output_section* dynstr) |
| { |
| if (!versions->any_defs() && !versions->any_needs()) |
| return; |
| |
| if (parameters->get_size() == 32) |
| { |
| if (parameters->is_big_endian()) |
| { |
| #ifdef HAVE_TARGET_32_BIG |
| this->sized_create_version_sections |
| SELECT_SIZE_ENDIAN_NAME(32, true)( |
| versions, symtab, local_symcount, dynamic_symbols, dynstr |
| SELECT_SIZE_ENDIAN(32, true)); |
| #else |
| gold_unreachable(); |
| #endif |
| } |
| else |
| { |
| #ifdef HAVE_TARGET_32_LITTLE |
| this->sized_create_version_sections |
| SELECT_SIZE_ENDIAN_NAME(32, false)( |
| versions, symtab, local_symcount, dynamic_symbols, dynstr |
| SELECT_SIZE_ENDIAN(32, false)); |
| #else |
| gold_unreachable(); |
| #endif |
| } |
| } |
| else if (parameters->get_size() == 64) |
| { |
| if (parameters->is_big_endian()) |
| { |
| #ifdef HAVE_TARGET_64_BIG |
| this->sized_create_version_sections |
| SELECT_SIZE_ENDIAN_NAME(64, true)( |
| versions, symtab, local_symcount, dynamic_symbols, dynstr |
| SELECT_SIZE_ENDIAN(64, true)); |
| #else |
| gold_unreachable(); |
| #endif |
| } |
| else |
| { |
| #ifdef HAVE_TARGET_64_LITTLE |
| this->sized_create_version_sections |
| SELECT_SIZE_ENDIAN_NAME(64, false)( |
| versions, symtab, local_symcount, dynamic_symbols, dynstr |
| SELECT_SIZE_ENDIAN(64, false)); |
| #else |
| gold_unreachable(); |
| #endif |
| } |
| } |
| else |
| gold_unreachable(); |
| } |
| |
| // Create the version sections, sized version. |
| |
| template<int size, bool big_endian> |
| void |
| Layout::sized_create_version_sections( |
| const Versions* versions, |
| const Symbol_table* symtab, |
| unsigned int local_symcount, |
| const std::vector<Symbol*>& dynamic_symbols, |
| const Output_section* dynstr |
| ACCEPT_SIZE_ENDIAN) |
| { |
| const char* vname = this->namepool_.add(".gnu.version", false, NULL); |
| Output_section* vsec = this->make_output_section(vname, |
| elfcpp::SHT_GNU_versym, |
| elfcpp::SHF_ALLOC); |
| |
| unsigned char* vbuf; |
| unsigned int vsize; |
| versions->symbol_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian)( |
| symtab, &this->dynpool_, local_symcount, dynamic_symbols, &vbuf, &vsize |
| SELECT_SIZE_ENDIAN(size, big_endian)); |
| |
| Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2); |
| |
| vsec->add_output_section_data(vdata); |
| vsec->set_entsize(2); |
| vsec->set_link_section(this->dynsym_section_); |
| |
| Output_data_dynamic* const odyn = this->dynamic_data_; |
| odyn->add_section_address(elfcpp::DT_VERSYM, vsec); |
| |
| if (versions->any_defs()) |
| { |
| const char* vdname = this->namepool_.add(".gnu.version_d", false, NULL); |
| Output_section *vdsec; |
| vdsec = this->make_output_section(vdname, elfcpp::SHT_GNU_verdef, |
| elfcpp::SHF_ALLOC); |
| |
| unsigned char* vdbuf; |
| unsigned int vdsize; |
| unsigned int vdentries; |
| versions->def_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian)( |
| &this->dynpool_, &vdbuf, &vdsize, &vdentries |
| SELECT_SIZE_ENDIAN(size, big_endian)); |
| |
| Output_section_data* vddata = new Output_data_const_buffer(vdbuf, |
| vdsize, |
| 4); |
| |
| vdsec->add_output_section_data(vddata); |
| vdsec->set_link_section(dynstr); |
| vdsec->set_info(vdentries); |
| |
| odyn->add_section_address(elfcpp::DT_VERDEF, vdsec); |
| odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries); |
| } |
| |
| if (versions->any_needs()) |
| { |
| const char* vnname = this->namepool_.add(".gnu.version_r", false, NULL); |
| Output_section* vnsec; |
| vnsec = this->make_output_section(vnname, elfcpp::SHT_GNU_verneed, |
| elfcpp::SHF_ALLOC); |
| |
| unsigned char* vnbuf; |
| unsigned int vnsize; |
| unsigned int vnentries; |
| versions->need_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian) |
| (&this->dynpool_, &vnbuf, &vnsize, &vnentries |
| SELECT_SIZE_ENDIAN(size, big_endian)); |
| |
| Output_section_data* vndata = new Output_data_const_buffer(vnbuf, |
| vnsize, |
| 4); |
| |
| vnsec->add_output_section_data(vndata); |
| vnsec->set_link_section(dynstr); |
| vnsec->set_info(vnentries); |
| |
| odyn->add_section_address(elfcpp::DT_VERNEED, vnsec); |
| odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries); |
| } |
| } |
| |
| // Create the .interp section and PT_INTERP segment. |
| |
| void |
| Layout::create_interp(const Target* target) |
| { |
| const char* interp = this->options_.dynamic_linker(); |
| if (interp == NULL) |
| { |
| interp = target->dynamic_linker(); |
| gold_assert(interp != NULL); |
| } |
| |
| size_t len = strlen(interp) + 1; |
| |
| Output_section_data* odata = new Output_data_const(interp, len, 1); |
| |
| const char* interp_name = this->namepool_.add(".interp", false, NULL); |
| Output_section* osec = this->make_output_section(interp_name, |
| elfcpp::SHT_PROGBITS, |
| elfcpp::SHF_ALLOC); |
| osec->add_output_section_data(odata); |
| |
| Output_segment* oseg = new Output_segment(elfcpp::PT_INTERP, elfcpp::PF_R); |
| this->segment_list_.push_back(oseg); |
| oseg->add_initial_output_section(osec, elfcpp::PF_R); |
| } |
| |
| // Finish the .dynamic section and PT_DYNAMIC segment. |
| |
| void |
| Layout::finish_dynamic_section(const Input_objects* input_objects, |
| const Symbol_table* symtab) |
| { |
| Output_segment* oseg = new Output_segment(elfcpp::PT_DYNAMIC, |
| elfcpp::PF_R | elfcpp::PF_W); |
| this->segment_list_.push_back(oseg); |
| oseg->add_initial_output_section(this->dynamic_section_, |
| elfcpp::PF_R | elfcpp::PF_W); |
| |
| Output_data_dynamic* const odyn = this->dynamic_data_; |
| |
| for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin(); |
| p != input_objects->dynobj_end(); |
| ++p) |
| { |
| // FIXME: Handle --as-needed. |
| odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname()); |
| } |
| |
| // FIXME: Support --init and --fini. |
| Symbol* sym = symtab->lookup("_init"); |
| if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) |
| odyn->add_symbol(elfcpp::DT_INIT, sym); |
| |
| sym = symtab->lookup("_fini"); |
| if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) |
| odyn->add_symbol(elfcpp::DT_FINI, sym); |
| |
| // FIXME: Support DT_INIT_ARRAY and DT_FINI_ARRAY. |
| |
| // Add a DT_RPATH entry if needed. |
| const General_options::Dir_list& rpath(this->options_.rpath()); |
| if (!rpath.empty()) |
| { |
| std::string rpath_val; |
| for (General_options::Dir_list::const_iterator p = rpath.begin(); |
| p != rpath.end(); |
| ++p) |
| { |
| if (rpath_val.empty()) |
| rpath_val = p->name(); |
| else |
| { |
| // Eliminate duplicates. |
| General_options::Dir_list::const_iterator q; |
| for (q = rpath.begin(); q != p; ++q) |
| if (q->name() == p->name()) |
| break; |
| if (q == p) |
| { |
| rpath_val += ':'; |
| rpath_val += p->name(); |
| } |
| } |
| } |
| |
| odyn->add_string(elfcpp::DT_RPATH, rpath_val); |
| } |
| } |
| |
| // The mapping of .gnu.linkonce section names to real section names. |
| |
| #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 } |
| const Layout::Linkonce_mapping Layout::linkonce_mapping[] = |
| { |
| MAPPING_INIT("d.rel.ro", ".data.rel.ro"), // Must be before "d". |
| MAPPING_INIT("t", ".text"), |
| MAPPING_INIT("r", ".rodata"), |
| MAPPING_INIT("d", ".data"), |
| MAPPING_INIT("b", ".bss"), |
| MAPPING_INIT("s", ".sdata"), |
| MAPPING_INIT("sb", ".sbss"), |
| MAPPING_INIT("s2", ".sdata2"), |
| MAPPING_INIT("sb2", ".sbss2"), |
| MAPPING_INIT("wi", ".debug_info"), |
| MAPPING_INIT("td", ".tdata"), |
| MAPPING_INIT("tb", ".tbss"), |
| MAPPING_INIT("lr", ".lrodata"), |
| MAPPING_INIT("l", ".ldata"), |
| MAPPING_INIT("lb", ".lbss"), |
| }; |
| #undef MAPPING_INIT |
| |
| const int Layout::linkonce_mapping_count = |
| sizeof(Layout::linkonce_mapping) / sizeof(Layout::linkonce_mapping[0]); |
| |
| // Return the name of the output section to use for a .gnu.linkonce |
| // section. This is based on the default ELF linker script of the old |
| // GNU linker. For example, we map a name like ".gnu.linkonce.t.foo" |
| // to ".text". Set *PLEN to the length of the name. *PLEN is |
| // initialized to the length of NAME. |
| |
| const char* |
| Layout::linkonce_output_name(const char* name, size_t *plen) |
| { |
| const char* s = name + sizeof(".gnu.linkonce") - 1; |
| if (*s != '.') |
| return name; |
| ++s; |
| const Linkonce_mapping* plm = linkonce_mapping; |
| for (int i = 0; i < linkonce_mapping_count; ++i, ++plm) |
| { |
| if (strncmp(s, plm->from, plm->fromlen) == 0 && s[plm->fromlen] == '.') |
| { |
| *plen = plm->tolen; |
| return plm->to; |
| } |
| } |
| return name; |
| } |
| |
| // Choose the output section name to use given an input section name. |
| // Set *PLEN to the length of the name. *PLEN is initialized to the |
| // length of NAME. |
| |
| const char* |
| Layout::output_section_name(const char* name, size_t* plen) |
| { |
| if (Layout::is_linkonce(name)) |
| { |
| // .gnu.linkonce sections are laid out as though they were named |
| // for the sections are placed into. |
| return Layout::linkonce_output_name(name, plen); |
| } |
| |
| // gcc 4.3 generates the following sorts of section names when it |
| // needs a section name specific to a function: |
| // .text.FN |
| // .rodata.FN |
| // .sdata2.FN |
| // .data.FN |
| // .data.rel.FN |
| // .data.rel.local.FN |
| // .data.rel.ro.FN |
| // .data.rel.ro.local.FN |
| // .sdata.FN |
| // .bss.FN |
| // .sbss.FN |
| // .tdata.FN |
| // .tbss.FN |
| |
| // The GNU linker maps all of those to the part before the .FN, |
| // except that .data.rel.local.FN is mapped to .data, and |
| // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections |
| // beginning with .data.rel.ro.local are grouped together. |
| |
| // For an anonymous namespace, the string FN can contain a '.'. |
| |
| // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the |
| // GNU linker maps to .rodata. |
| |
| // The .data.rel.ro sections enable a security feature triggered by |
| // the -z relro option. Section which need to be relocated at |
| // program startup time but which may be readonly after startup are |
| // grouped into .data.rel.ro. They are then put into a PT_GNU_RELRO |
| // segment. The dynamic linker will make that segment writable, |
| // perform relocations, and then make it read-only. FIXME: We do |
| // not yet implement this optimization. |
| |
| // It is hard to handle this in a principled way. |
| |
| // These are the rules we follow: |
| |
| // If the section name has no initial '.', or no dot other than an |
| // initial '.', we use the name unchanged (i.e., "mysection" and |
| // ".text" are unchanged). |
| |
| // If the name starts with ".data.rel.ro" we use ".data.rel.ro". |
| |
| // Otherwise, we drop the second '.' and everything that comes after |
| // it (i.e., ".text.XXX" becomes ".text"). |
| |
| const char* s = name; |
| if (*s != '.') |
| return name; |
| ++s; |
| const char* sdot = strchr(s, '.'); |
| if (sdot == NULL) |
| return name; |
| |
| const char* const data_rel_ro = ".data.rel.ro"; |
| if (strncmp(name, data_rel_ro, strlen(data_rel_ro)) == 0) |
| { |
| *plen = strlen(data_rel_ro); |
| return data_rel_ro; |
| } |
| |
| *plen = sdot - name; |
| return name; |
| } |
| |
| // Record the signature of a comdat section, and return whether to |
| // include it in the link. If GROUP is true, this is a regular |
| // section group. If GROUP is false, this is a group signature |
| // derived from the name of a linkonce section. We want linkonce |
| // signatures and group signatures to block each other, but we don't |
| // want a linkonce signature to block another linkonce signature. |
| |
| bool |
| Layout::add_comdat(const char* signature, bool group) |
| { |
| std::string sig(signature); |
| std::pair<Signatures::iterator, bool> ins( |
| this->signatures_.insert(std::make_pair(sig, group))); |
| |
| if (ins.second) |
| { |
| // This is the first time we've seen this signature. |
| return true; |
| } |
| |
| if (ins.first->second) |
| { |
| // We've already seen a real section group with this signature. |
| return false; |
| } |
| else if (group) |
| { |
| // This is a real section group, and we've already seen a |
| // linkonce section with this signature. Record that we've seen |
| // a section group, and don't include this section group. |
| ins.first->second = true; |
| return false; |
| } |
| else |
| { |
| // We've already seen a linkonce section and this is a linkonce |
| // section. These don't block each other--this may be the same |
| // symbol name with different section types. |
| return true; |
| } |
| } |
| |
| // Write out data not associated with a section or the symbol table. |
| |
| void |
| Layout::write_data(const Symbol_table* symtab, Output_file* of) const |
| { |
| if (!parameters->strip_all()) |
| { |
| const Output_section* symtab_section = this->symtab_section_; |
| for (Section_list::const_iterator p = this->section_list_.begin(); |
| p != this->section_list_.end(); |
| ++p) |
| { |
| if ((*p)->needs_symtab_index()) |
| { |
| gold_assert(symtab_section != NULL); |
| unsigned int index = (*p)->symtab_index(); |
| gold_assert(index > 0 && index != -1U); |
| off_t off = (symtab_section->offset() |
| + index * symtab_section->entsize()); |
| symtab->write_section_symbol(*p, of, off); |
| } |
| } |
| } |
| |
| const Output_section* dynsym_section = this->dynsym_section_; |
| for (Section_list::const_iterator p = this->section_list_.begin(); |
| p != this->section_list_.end(); |
| ++p) |
| { |
| if ((*p)->needs_dynsym_index()) |
| { |
| gold_assert(dynsym_section != NULL); |
| unsigned int index = (*p)->dynsym_index(); |
| gold_assert(index > 0 && index != -1U); |
| off_t off = (dynsym_section->offset() |
| + index * dynsym_section->entsize()); |
| symtab->write_section_symbol(*p, of, off); |
| } |
| } |
| |
| // Write out the Output_sections. Most won't have anything to |
| // write, since most of the data will come from input sections which |
| // are handled elsewhere. But some Output_sections do have |
| // Output_data. |
| for (Section_list::const_iterator p = this->section_list_.begin(); |
| p != this->section_list_.end(); |
| ++p) |
| (*p)->write(of); |
| |
| // Write out the Output_data which are not in an Output_section. |
| for (Data_list::const_iterator p = this->special_output_list_.begin(); |
| p != this->special_output_list_.end(); |
| ++p) |
| (*p)->write(of); |
| } |
| |
| // Write_data_task methods. |
| |
| // We can always run this task. |
| |
| Task::Is_runnable_type |
| Write_data_task::is_runnable(Workqueue*) |
| { |
| return IS_RUNNABLE; |
| } |
| |
| // We need to unlock FINAL_BLOCKER when finished. |
| |
| Task_locker* |
| Write_data_task::locks(Workqueue* workqueue) |
| { |
| return new Task_locker_block(*this->final_blocker_, workqueue); |
| } |
| |
| // Run the task--write out the data. |
| |
| void |
| Write_data_task::run(Workqueue*) |
| { |
| this->layout_->write_data(this->symtab_, this->of_); |
| } |
| |
| // Write_symbols_task methods. |
| |
| // We can always run this task. |
| |
| Task::Is_runnable_type |
| Write_symbols_task::is_runnable(Workqueue*) |
| { |
| return IS_RUNNABLE; |
| } |
| |
| // We need to unlock FINAL_BLOCKER when finished. |
| |
| Task_locker* |
| Write_symbols_task::locks(Workqueue* workqueue) |
| { |
| return new Task_locker_block(*this->final_blocker_, workqueue); |
| } |
| |
| // Run the task--write out the symbols. |
| |
| void |
| Write_symbols_task::run(Workqueue*) |
| { |
| this->symtab_->write_globals(this->target_, this->sympool_, this->dynpool_, |
| this->of_); |
| } |
| |
| // Close_task_runner methods. |
| |
| // Run the task--close the file. |
| |
| void |
| Close_task_runner::run(Workqueue*) |
| { |
| this->of_->close(); |
| } |
| |
| // Instantiate the templates we need. We could use the configure |
| // script to restrict this to only the ones for implemented targets. |
| |
| #ifdef HAVE_TARGET_32_LITTLE |
| template |
| Output_section* |
| Layout::layout<32, false>(Relobj* object, unsigned int shndx, const char* name, |
| const elfcpp::Shdr<32, false>& shdr, off_t*); |
| #endif |
| |
| #ifdef HAVE_TARGET_32_BIG |
| template |
| Output_section* |
| Layout::layout<32, true>(Relobj* object, unsigned int shndx, const char* name, |
| const elfcpp::Shdr<32, true>& shdr, off_t*); |
| #endif |
| |
| #ifdef HAVE_TARGET_64_LITTLE |
| template |
| Output_section* |
| Layout::layout<64, false>(Relobj* object, unsigned int shndx, const char* name, |
| const elfcpp::Shdr<64, false>& shdr, off_t*); |
| #endif |
| |
| #ifdef HAVE_TARGET_64_BIG |
| template |
| Output_section* |
| Layout::layout<64, true>(Relobj* object, unsigned int shndx, const char* name, |
| const elfcpp::Shdr<64, true>& shdr, off_t*); |
| #endif |
| |
| |
| } // End namespace gold. |