X-Git-Url: https://oss.titaniummirror.com/gitweb?p=msp430-binutils.git;a=blobdiff_plain;f=gold%2Flayout.cc;fp=gold%2Flayout.cc;h=028703ae1cec80a774f157a39c79ea88d4bda1be;hp=0000000000000000000000000000000000000000;hb=88750007d7869f178f0ba528f41efd3b74c424cf;hpb=6df9443a374e2b81278c61b8afc0a1eef7db280b diff --git a/gold/layout.cc b/gold/layout.cc new file mode 100644 index 0000000..028703a --- /dev/null +++ b/gold/layout.cc @@ -0,0 +1,4015 @@ +// layout.cc -- lay out output file sections for gold + +// Copyright 2006, 2007, 2008, 2009 Free Software Foundation, Inc. +// Written by Ian Lance Taylor . + +// 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 +#include +#include +#include +#include +#include +#include +#include "libiberty.h" +#include "md5.h" +#include "sha1.h" + +#include "parameters.h" +#include "options.h" +#include "mapfile.h" +#include "script.h" +#include "script-sections.h" +#include "output.h" +#include "symtab.h" +#include "dynobj.h" +#include "ehframe.h" +#include "compressed_output.h" +#include "reduced_debug_output.h" +#include "reloc.h" +#include "descriptors.h" +#include "plugin.h" +#include "incremental.h" +#include "layout.h" + +namespace gold +{ + +// Layout::Relaxation_debug_check methods. + +// Check that sections and special data are in reset states. +// We do not save states for Output_sections and special Output_data. +// So we check that they have not assigned any addresses or offsets. +// clean_up_after_relaxation simply resets their addresses and offsets. +void +Layout::Relaxation_debug_check::check_output_data_for_reset_values( + const Layout::Section_list& sections, + const Layout::Data_list& special_outputs) +{ + for(Layout::Section_list::const_iterator p = sections.begin(); + p != sections.end(); + ++p) + gold_assert((*p)->address_and_file_offset_have_reset_values()); + + for(Layout::Data_list::const_iterator p = special_outputs.begin(); + p != special_outputs.end(); + ++p) + gold_assert((*p)->address_and_file_offset_have_reset_values()); +} + +// Save information of SECTIONS for checking later. + +void +Layout::Relaxation_debug_check::read_sections( + const Layout::Section_list& sections) +{ + for(Layout::Section_list::const_iterator p = sections.begin(); + p != sections.end(); + ++p) + { + Output_section* os = *p; + Section_info info; + info.output_section = os; + info.address = os->is_address_valid() ? os->address() : 0; + info.data_size = os->is_data_size_valid() ? os->data_size() : -1; + info.offset = os->is_offset_valid()? os->offset() : -1 ; + this->section_infos_.push_back(info); + } +} + +// Verify SECTIONS using previously recorded information. + +void +Layout::Relaxation_debug_check::verify_sections( + const Layout::Section_list& sections) +{ + size_t i = 0; + for(Layout::Section_list::const_iterator p = sections.begin(); + p != sections.end(); + ++p, ++i) + { + Output_section* os = *p; + uint64_t address = os->is_address_valid() ? os->address() : 0; + off_t data_size = os->is_data_size_valid() ? os->data_size() : -1; + off_t offset = os->is_offset_valid()? os->offset() : -1 ; + + if (i >= this->section_infos_.size()) + { + gold_fatal("Section_info of %s missing.\n", os->name()); + } + const Section_info& info = this->section_infos_[i]; + if (os != info.output_section) + gold_fatal("Section order changed. Expecting %s but see %s\n", + info.output_section->name(), os->name()); + if (address != info.address + || data_size != info.data_size + || offset != info.offset) + gold_fatal("Section %s changed.\n", os->name()); + } +} + +// 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, const Task* task) +{ + off_t file_size = this->layout_->finalize(this->input_objects_, + this->symtab_, + this->target_, + task); + + // Now we know the final size of the output file and we know where + // each piece of information goes. + + if (this->mapfile_ != NULL) + { + this->mapfile_->print_discarded_sections(this->input_objects_); + this->layout_->print_to_mapfile(this->mapfile_); + } + + Output_file* of = new Output_file(parameters->options().output_file_name()); + if (this->options_.oformat_enum() != General_options::OBJECT_FORMAT_ELF) + of->set_is_temporary(); + 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(int number_of_input_files, Script_options* script_options) + : number_of_input_files_(number_of_input_files), + script_options_(script_options), + namepool_(), + sympool_(), + dynpool_(), + signatures_(), + section_name_map_(), + segment_list_(), + section_list_(), + unattached_section_list_(), + special_output_list_(), + section_headers_(NULL), + tls_segment_(NULL), + relro_segment_(NULL), + symtab_section_(NULL), + symtab_xindex_(NULL), + dynsym_section_(NULL), + dynsym_xindex_(NULL), + dynamic_section_(NULL), + dynamic_data_(NULL), + eh_frame_section_(NULL), + eh_frame_data_(NULL), + added_eh_frame_data_(false), + eh_frame_hdr_section_(NULL), + build_id_note_(NULL), + debug_abbrev_(NULL), + debug_info_(NULL), + group_signatures_(), + output_file_size_(-1), + sections_are_attached_(false), + input_requires_executable_stack_(false), + input_with_gnu_stack_note_(false), + input_without_gnu_stack_note_(false), + has_static_tls_(false), + any_postprocessing_sections_(false), + resized_signatures_(false), + have_stabstr_section_(false), + incremental_inputs_(NULL), + record_output_section_data_from_script_(false), + script_output_section_data_list_(), + segment_states_(NULL), + relaxation_debug_check_(NULL) +{ + // 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 two unattached Output_data objects: the file header and + // the segment headers. + this->special_output_list_.reserve(2); + + // Initialize structure needed for an incremental build. + if (parameters->options().incremental()) + this->incremental_inputs_ = new Incremental_inputs; + + // The section name pool is worth optimizing in all cases, because + // it is small, but there are often overlaps due to .rel sections. + this->namepool_.set_optimize(); +} + +// 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; +} + +// Returns whether the given section is in the list of +// debug-sections-used-by-some-version-of-gdb. Currently, +// we've checked versions of gdb up to and including 6.7.1. + +static const char* gdb_sections[] = +{ ".debug_abbrev", + // ".debug_aranges", // not used by gdb as of 6.7.1 + ".debug_frame", + ".debug_info", + ".debug_line", + ".debug_loc", + ".debug_macinfo", + // ".debug_pubnames", // not used by gdb as of 6.7.1 + ".debug_ranges", + ".debug_str", +}; + +static const char* lines_only_debug_sections[] = +{ ".debug_abbrev", + // ".debug_aranges", // not used by gdb as of 6.7.1 + // ".debug_frame", + ".debug_info", + ".debug_line", + // ".debug_loc", + // ".debug_macinfo", + // ".debug_pubnames", // not used by gdb as of 6.7.1 + // ".debug_ranges", + ".debug_str", +}; + +static inline bool +is_gdb_debug_section(const char* str) +{ + // We can do this faster: binary search or a hashtable. But why bother? + for (size_t i = 0; i < sizeof(gdb_sections)/sizeof(*gdb_sections); ++i) + if (strcmp(str, gdb_sections[i]) == 0) + return true; + return false; +} + +static inline bool +is_lines_only_debug_section(const char* str) +{ + // We can do this faster: binary search or a hashtable. But why bother? + for (size_t i = 0; + i < sizeof(lines_only_debug_sections)/sizeof(*lines_only_debug_sections); + ++i) + if (strcmp(str, lines_only_debug_sections[i]) == 0) + return true; + return false; +} + +// Whether to include this section in the link. + +template +bool +Layout::include_section(Sized_relobj*, const char* name, + const elfcpp::Shdr& shdr) +{ + if (shdr.get_sh_flags() & elfcpp::SHF_EXCLUDE) + return false; + + switch (shdr.get_sh_type()) + { + case elfcpp::SHT_NULL: + case elfcpp::SHT_SYMTAB: + case elfcpp::SHT_DYNSYM: + case elfcpp::SHT_HASH: + case elfcpp::SHT_DYNAMIC: + case elfcpp::SHT_SYMTAB_SHNDX: + return false; + + case elfcpp::SHT_STRTAB: + // Discard the sections which have special meanings in the ELF + // ABI. Keep others (e.g., .stabstr). We could also do this by + // checking the sh_link fields of the appropriate sections. + return (strcmp(name, ".dynstr") != 0 + && strcmp(name, ".strtab") != 0 + && strcmp(name, ".shstrtab") != 0); + + case elfcpp::SHT_RELA: + case elfcpp::SHT_REL: + case elfcpp::SHT_GROUP: + // If we are emitting relocations these should be handled + // elsewhere. + gold_assert(!parameters->options().relocatable() + && !parameters->options().emit_relocs()); + return false; + + case elfcpp::SHT_PROGBITS: + if (parameters->options().strip_debug() + && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) + { + if (is_debug_info_section(name)) + return false; + } + if (parameters->options().strip_debug_non_line() + && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) + { + // Debugging sections can only be recognized by name. + if (is_prefix_of(".debug", name) + && !is_lines_only_debug_section(name)) + return false; + } + if (parameters->options().strip_debug_gdb() + && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) + { + // Debugging sections can only be recognized by name. + if (is_prefix_of(".debug", name) + && !is_gdb_debug_section(name)) + return false; + } + if (parameters->options().strip_lto_sections() + && !parameters->options().relocatable() + && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) + { + // Ignore LTO sections containing intermediate code. + if (is_prefix_of(".gnu.lto_", 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_list::const_iterator p = this->section_list_.begin(); + p != this->section_list_.end(); + ++p) + if (strcmp((*p)->name(), name) == 0) + return *p; + 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((*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. NAME must be canonicalized in the string +// pool, and NAME_KEY is the key. + +Output_section* +Layout::get_output_section(const char* name, Stringpool::Key name_key, + elfcpp::Elf_Word type, elfcpp::Elf_Xword flags) +{ + elfcpp::Elf_Xword lookup_flags = flags; + + // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine + // read-write with read-only sections. Some other ELF linkers do + // not do this. FIXME: Perhaps there should be an option + // controlling this. + lookup_flags &= ~(elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR); + + const Key key(name_key, std::make_pair(type, lookup_flags)); + const std::pair v(key, NULL); + std::pair 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. For compatibility with the GNU linker, we + // combine sections with contents and zero flags with sections + // with non-zero flags. This is a workaround for cases where + // assembler code forgets to set section flags. FIXME: Perhaps + // there should be an option to control this. + Output_section* os = NULL; + + if (type == elfcpp::SHT_PROGBITS) + { + if (flags == 0) + { + Output_section* same_name = this->find_output_section(name); + if (same_name != NULL + && same_name->type() == elfcpp::SHT_PROGBITS + && (same_name->flags() & elfcpp::SHF_TLS) == 0) + os = same_name; + } + else if ((flags & elfcpp::SHF_TLS) == 0) + { + elfcpp::Elf_Xword zero_flags = 0; + const Key zero_key(name_key, std::make_pair(type, zero_flags)); + Section_name_map::iterator p = + this->section_name_map_.find(zero_key); + if (p != this->section_name_map_.end()) + os = p->second; + } + } + + if (os == NULL) + os = this->make_output_section(name, type, flags); + ins.first->second = os; + return os; + } +} + +// Pick the output section to use for section NAME, in input file +// RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a +// linker created section. IS_INPUT_SECTION is true if we are +// choosing an output section for an input section found in a input +// file. This will return NULL if the input section should be +// discarded. + +Output_section* +Layout::choose_output_section(const Relobj* relobj, const char* name, + elfcpp::Elf_Word type, elfcpp::Elf_Xword flags, + bool is_input_section) +{ + // We should not see any input sections after we have attached + // sections to segments. + gold_assert(!is_input_section || !this->sections_are_attached_); + + // Some flags in the input section should not be automatically + // copied to the output section. + flags &= ~ (elfcpp::SHF_INFO_LINK + | elfcpp::SHF_LINK_ORDER + | elfcpp::SHF_GROUP + | elfcpp::SHF_MERGE + | elfcpp::SHF_STRINGS); + + if (this->script_options_->saw_sections_clause()) + { + // We are using a SECTIONS clause, so the output section is + // chosen based only on the name. + + Script_sections* ss = this->script_options_->script_sections(); + const char* file_name = relobj == NULL ? NULL : relobj->name().c_str(); + Output_section** output_section_slot; + name = ss->output_section_name(file_name, name, &output_section_slot); + if (name == NULL) + { + // The SECTIONS clause says to discard this input section. + return NULL; + } + + // If this is an orphan section--one not mentioned in the linker + // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the + // default processing below. + + if (output_section_slot != NULL) + { + if (*output_section_slot != NULL) + { + (*output_section_slot)->update_flags_for_input_section(flags); + return *output_section_slot; + } + + // We don't put sections found in the linker script into + // SECTION_NAME_MAP_. That keeps us from getting confused + // if an orphan section is mapped to a section with the same + // name as one in the linker script. + + name = this->namepool_.add(name, false, NULL); + + Output_section* os = this->make_output_section(name, type, flags); + os->set_found_in_sections_clause(); + *output_section_slot = os; + return os; + } + } + + // FIXME: Handle SHF_OS_NONCONFORMING somewhere. + + // Turn NAME from the name of the input section into the name of the + // output section. + + size_t len = strlen(name); + if (is_input_section + && !this->script_options_->saw_sections_clause() + && !parameters->options().relocatable()) + name = Layout::output_section_name(name, &len); + + Stringpool::Key name_key; + name = this->namepool_.add_with_length(name, len, true, &name_key); + + // Find or make the output section. The output section is selected + // based on the section name, type, and flags. + return this->get_output_section(name, name_key, type, flags); +} + +// Return the output section to use for input section SHNDX, with name +// NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the +// index of a relocation section which applies to this section, or 0 +// if none, or -1U if more than one. RELOC_TYPE is the type of the +// relocation section if there is one. Set *OFF to the offset of this +// input section without the output section. Return NULL if the +// section should be discarded. Set *OFF to -1 if the section +// contents should not be written directly to the output file, but +// will instead receive special handling. + +template +Output_section* +Layout::layout(Sized_relobj* object, unsigned int shndx, + const char* name, const elfcpp::Shdr& shdr, + unsigned int reloc_shndx, unsigned int, off_t* off) +{ + *off = 0; + + if (!this->include_section(object, name, shdr)) + return NULL; + + Output_section* os; + + // In a relocatable link a grouped section must not be combined with + // any other sections. + if (parameters->options().relocatable() + && (shdr.get_sh_flags() & elfcpp::SHF_GROUP) != 0) + { + name = this->namepool_.add(name, true, NULL); + os = this->make_output_section(name, shdr.get_sh_type(), + shdr.get_sh_flags()); + } + else + { + os = this->choose_output_section(object, name, shdr.get_sh_type(), + shdr.get_sh_flags(), true); + if (os == NULL) + return NULL; + } + + // By default the GNU linker sorts input sections whose names match + // .ctor.*, .dtor.*, .init_array.*, or .fini_array.*. The sections + // are sorted by name. This is used to implement constructor + // priority ordering. We are compatible. + if (!this->script_options_->saw_sections_clause() + && (is_prefix_of(".ctors.", name) + || is_prefix_of(".dtors.", name) + || is_prefix_of(".init_array.", name) + || is_prefix_of(".fini_array.", name))) + os->set_must_sort_attached_input_sections(); + + // FIXME: Handle SHF_LINK_ORDER somewhere. + + *off = os->add_input_section(object, shndx, name, shdr, reloc_shndx, + this->script_options_->saw_sections_clause()); + + return os; +} + +// Handle a relocation section when doing a relocatable link. + +template +Output_section* +Layout::layout_reloc(Sized_relobj* object, + unsigned int, + const elfcpp::Shdr& shdr, + Output_section* data_section, + Relocatable_relocs* rr) +{ + gold_assert(parameters->options().relocatable() + || parameters->options().emit_relocs()); + + int sh_type = shdr.get_sh_type(); + + std::string name; + if (sh_type == elfcpp::SHT_REL) + name = ".rel"; + else if (sh_type == elfcpp::SHT_RELA) + name = ".rela"; + else + gold_unreachable(); + name += data_section->name(); + + Output_section* os = this->choose_output_section(object, name.c_str(), + sh_type, + shdr.get_sh_flags(), + false); + + os->set_should_link_to_symtab(); + os->set_info_section(data_section); + + Output_section_data* posd; + if (sh_type == elfcpp::SHT_REL) + { + os->set_entsize(elfcpp::Elf_sizes::rel_size); + posd = new Output_relocatable_relocs(rr); + } + else if (sh_type == elfcpp::SHT_RELA) + { + os->set_entsize(elfcpp::Elf_sizes::rela_size); + posd = new Output_relocatable_relocs(rr); + } + else + gold_unreachable(); + + os->add_output_section_data(posd); + rr->set_output_data(posd); + + return os; +} + +// Handle a group section when doing a relocatable link. + +template +void +Layout::layout_group(Symbol_table* symtab, + Sized_relobj* object, + unsigned int, + const char* group_section_name, + const char* signature, + const elfcpp::Shdr& shdr, + elfcpp::Elf_Word flags, + std::vector* shndxes) +{ + gold_assert(parameters->options().relocatable()); + gold_assert(shdr.get_sh_type() == elfcpp::SHT_GROUP); + group_section_name = this->namepool_.add(group_section_name, true, NULL); + Output_section* os = this->make_output_section(group_section_name, + elfcpp::SHT_GROUP, + shdr.get_sh_flags()); + + // We need to find a symbol with the signature in the symbol table. + // If we don't find one now, we need to look again later. + Symbol* sym = symtab->lookup(signature, NULL); + if (sym != NULL) + os->set_info_symndx(sym); + else + { + // Reserve some space to minimize reallocations. + if (this->group_signatures_.empty()) + this->group_signatures_.reserve(this->number_of_input_files_ * 16); + + // We will wind up using a symbol whose name is the signature. + // So just put the signature in the symbol name pool to save it. + signature = symtab->canonicalize_name(signature); + this->group_signatures_.push_back(Group_signature(os, signature)); + } + + os->set_should_link_to_symtab(); + os->set_entsize(4); + + section_size_type entry_count = + convert_to_section_size_type(shdr.get_sh_size() / 4); + Output_section_data* posd = + new Output_data_group(object, entry_count, flags, + shndxes); + os->add_output_section_data(posd); +} + +// Special GNU handling of sections name .eh_frame. They will +// normally hold exception frame data as defined by the C++ ABI +// (http://codesourcery.com/cxx-abi/). + +template +Output_section* +Layout::layout_eh_frame(Sized_relobj* object, + const unsigned char* symbols, + off_t symbols_size, + const unsigned char* symbol_names, + off_t symbol_names_size, + unsigned int shndx, + const elfcpp::Shdr& shdr, + unsigned int reloc_shndx, unsigned int reloc_type, + off_t* off) +{ + gold_assert(shdr.get_sh_type() == elfcpp::SHT_PROGBITS); + gold_assert((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0); + + const char* const name = ".eh_frame"; + Output_section* os = this->choose_output_section(object, + name, + elfcpp::SHT_PROGBITS, + elfcpp::SHF_ALLOC, + false); + if (os == NULL) + return NULL; + + if (this->eh_frame_section_ == NULL) + { + this->eh_frame_section_ = os; + this->eh_frame_data_ = new Eh_frame(); + + if (parameters->options().eh_frame_hdr()) + { + Output_section* hdr_os = + this->choose_output_section(NULL, + ".eh_frame_hdr", + elfcpp::SHT_PROGBITS, + elfcpp::SHF_ALLOC, + false); + + if (hdr_os != NULL) + { + Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os, + this->eh_frame_data_); + hdr_os->add_output_section_data(hdr_posd); + + hdr_os->set_after_input_sections(); + + if (!this->script_options_->saw_phdrs_clause()) + { + Output_segment* hdr_oseg; + hdr_oseg = this->make_output_segment(elfcpp::PT_GNU_EH_FRAME, + elfcpp::PF_R); + hdr_oseg->add_output_section(hdr_os, elfcpp::PF_R); + } + + this->eh_frame_data_->set_eh_frame_hdr(hdr_posd); + } + } + } + + gold_assert(this->eh_frame_section_ == os); + + if (this->eh_frame_data_->add_ehframe_input_section(object, + symbols, + symbols_size, + symbol_names, + symbol_names_size, + shndx, + reloc_shndx, + reloc_type)) + { + os->update_flags_for_input_section(shdr.get_sh_flags()); + + // We found a .eh_frame section we are going to optimize, so now + // we can add the set of optimized sections to the output + // section. We need to postpone adding this until we've found a + // section we can optimize so that the .eh_frame section in + // crtbegin.o winds up at the start of the output section. + if (!this->added_eh_frame_data_) + { + os->add_output_section_data(this->eh_frame_data_); + this->added_eh_frame_data_ = true; + } + *off = -1; + } + else + { + // We couldn't handle this .eh_frame section for some reason. + // Add it as a normal section. + bool saw_sections_clause = this->script_options_->saw_sections_clause(); + *off = os->add_input_section(object, shndx, name, shdr, reloc_shndx, + saw_sections_clause); + } + + return os; +} + +// Add POSD to an output section using NAME, TYPE, and FLAGS. Return +// the output section. + +Output_section* +Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type, + elfcpp::Elf_Xword flags, + Output_section_data* posd) +{ + Output_section* os = this->choose_output_section(NULL, name, type, flags, + false); + if (os != NULL) + os->add_output_section_data(posd); + return os; +} + +// 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; +} + +// Sometimes we compress sections. This is typically done for +// sections that are not part of normal program execution (such as +// .debug_* sections), and where the readers of these sections know +// how to deal with compressed sections. This routine doesn't say for +// certain whether we'll compress -- it depends on commandline options +// as well -- just whether this section is a candidate for compression. +// (The Output_compressed_section class decides whether to compress +// a given section, and picks the name of the compressed section.) + +static bool +is_compressible_debug_section(const char* secname) +{ + return (strncmp(secname, ".debug", sizeof(".debug") - 1) == 0); +} + +// 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; + if ((flags & elfcpp::SHF_ALLOC) == 0 + && strcmp(parameters->options().compress_debug_sections(), "none") != 0 + && is_compressible_debug_section(name)) + os = new Output_compressed_section(¶meters->options(), name, type, + flags); + + else if ((flags & elfcpp::SHF_ALLOC) == 0 + && parameters->options().strip_debug_non_line() + && strcmp(".debug_abbrev", name) == 0) + { + os = this->debug_abbrev_ = new Output_reduced_debug_abbrev_section( + name, type, flags); + if (this->debug_info_) + this->debug_info_->set_abbreviations(this->debug_abbrev_); + } + else if ((flags & elfcpp::SHF_ALLOC) == 0 + && parameters->options().strip_debug_non_line() + && strcmp(".debug_info", name) == 0) + { + os = this->debug_info_ = new Output_reduced_debug_info_section( + name, type, flags); + if (this->debug_abbrev_) + this->debug_info_->set_abbreviations(this->debug_abbrev_); + } + else + { + // FIXME: const_cast is ugly. + Target* target = const_cast(¶meters->target()); + os = target->make_output_section(name, type, flags); + } + + parameters->target().new_output_section(os); + + this->section_list_.push_back(os); + + // The GNU linker by default sorts some sections by priority, so we + // do the same. We need to know that this might happen before we + // attach any input sections. + if (!this->script_options_->saw_sections_clause() + && (strcmp(name, ".ctors") == 0 + || strcmp(name, ".dtors") == 0 + || strcmp(name, ".init_array") == 0 + || strcmp(name, ".fini_array") == 0)) + os->set_may_sort_attached_input_sections(); + + // With -z relro, we have to recognize the special sections by name. + // There is no other way. + if (!this->script_options_->saw_sections_clause() + && parameters->options().relro() + && type == elfcpp::SHT_PROGBITS + && (flags & elfcpp::SHF_ALLOC) != 0 + && (flags & elfcpp::SHF_WRITE) != 0) + { + if (strcmp(name, ".data.rel.ro") == 0) + os->set_is_relro(); + else if (strcmp(name, ".data.rel.ro.local") == 0) + { + os->set_is_relro(); + os->set_is_relro_local(); + } + } + + // Check for .stab*str sections, as .stab* sections need to link to + // them. + if (type == elfcpp::SHT_STRTAB + && !this->have_stabstr_section_ + && strncmp(name, ".stab", 5) == 0 + && strcmp(name + strlen(name) - 3, "str") == 0) + this->have_stabstr_section_ = true; + + // If we have already attached the sections to segments, then we + // need to attach this one now. This happens for sections created + // directly by the linker. + if (this->sections_are_attached_) + this->attach_section_to_segment(os); + + return os; +} + +// Attach output sections to segments. This is called after we have +// seen all the input sections. + +void +Layout::attach_sections_to_segments() +{ + for (Section_list::iterator p = this->section_list_.begin(); + p != this->section_list_.end(); + ++p) + this->attach_section_to_segment(*p); + + this->sections_are_attached_ = true; +} + +// Attach an output section to a segment. + +void +Layout::attach_section_to_segment(Output_section* os) +{ + if ((os->flags() & elfcpp::SHF_ALLOC) == 0) + this->unattached_section_list_.push_back(os); + else + this->attach_allocated_section_to_segment(os); +} + +// Attach an allocated output section to a segment. + +void +Layout::attach_allocated_section_to_segment(Output_section* os) +{ + elfcpp::Elf_Xword flags = os->flags(); + gold_assert((flags & elfcpp::SHF_ALLOC) != 0); + + if (parameters->options().relocatable()) + return; + + // If we have a SECTIONS clause, we can't handle the attachment to + // segments until after we've seen all the sections. + if (this->script_options_->saw_sections_clause()) + return; + + gold_assert(!this->script_options_->saw_phdrs_clause()); + + // This output section goes into a PT_LOAD segment. + + elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags); + + // In general 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. Large data sections also go into their own + // PT_LOAD segment. People who need segments sorted on some other + // basis will have to use a linker script. + + Segment_list::const_iterator p; + for (p = this->segment_list_.begin(); + p != this->segment_list_.end(); + ++p) + { + if ((*p)->type() != elfcpp::PT_LOAD) + continue; + if (!parameters->options().omagic() + && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W)) + continue; + // If -Tbss was specified, we need to separate the data and BSS + // segments. + if (parameters->options().user_set_Tbss()) + { + if ((os->type() == elfcpp::SHT_NOBITS) + == (*p)->has_any_data_sections()) + continue; + } + if (os->is_large_data_section() && !(*p)->is_large_data_segment()) + continue; + + (*p)->add_output_section(os, seg_flags); + break; + } + + if (p == this->segment_list_.end()) + { + Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD, + seg_flags); + if (os->is_large_data_section()) + oseg->set_is_large_data_segment(); + oseg->add_output_section(os, seg_flags); + } + + // If we see a loadable SHT_NOTE section, we create a PT_NOTE + // segment. + if (os->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 = this->make_output_segment(elfcpp::PT_NOTE, + seg_flags); + 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->make_output_segment(elfcpp::PT_TLS, seg_flags); + this->tls_segment_->add_output_section(os, seg_flags); + } + + // If -z relro is in effect, and we see a relro section, we create a + // PT_GNU_RELRO segment. There can only be one such segment. + if (os->is_relro() && parameters->options().relro()) + { + gold_assert(seg_flags == (elfcpp::PF_R | elfcpp::PF_W)); + if (this->relro_segment_ == NULL) + this->make_output_segment(elfcpp::PT_GNU_RELRO, seg_flags); + this->relro_segment_->add_output_section(os, seg_flags); + } +} + +// Make an output section for a script. + +Output_section* +Layout::make_output_section_for_script(const char* name) +{ + name = this->namepool_.add(name, false, NULL); + Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS, + elfcpp::SHF_ALLOC); + os->set_found_in_sections_clause(); + return os; +} + +// Return the number of segments we expect to see. + +size_t +Layout::expected_segment_count() const +{ + size_t ret = this->segment_list_.size(); + + // If we didn't see a SECTIONS clause in a linker script, we should + // already have the complete list of segments. Otherwise we ask the + // SECTIONS clause how many segments it expects, and add in the ones + // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.) + + if (!this->script_options_->saw_sections_clause()) + return ret; + else + { + const Script_sections* ss = this->script_options_->script_sections(); + return ret + ss->expected_segment_count(this); + } +} + +// 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 automatic note sections. + +void +Layout::create_notes() +{ + this->create_gold_note(); + this->create_executable_stack_info(); + this->create_build_id(); +} + +// Create the dynamic sections which are needed before we read the +// relocs. + +void +Layout::create_initial_dynamic_sections(Symbol_table* symtab) +{ + if (parameters->doing_static_link()) + return; + + this->dynamic_section_ = this->choose_output_section(NULL, ".dynamic", + elfcpp::SHT_DYNAMIC, + (elfcpp::SHF_ALLOC + | elfcpp::SHF_WRITE), + false); + this->dynamic_section_->set_is_relro(); + + symtab->define_in_output_data("_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) +{ + 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(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 + true); // only_if_ref + + symtab->define_in_output_data(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 + true); // only_if_ref + } + } +} + +// Define symbols for group signatures. + +void +Layout::define_group_signatures(Symbol_table* symtab) +{ + for (Group_signatures::iterator p = this->group_signatures_.begin(); + p != this->group_signatures_.end(); + ++p) + { + Symbol* sym = symtab->lookup(p->signature, NULL); + if (sym != NULL) + p->section->set_info_symndx(sym); + else + { + // Force the name of the group section to the group + // signature, and use the group's section symbol as the + // signature symbol. + if (strcmp(p->section->name(), p->signature) != 0) + { + const char* name = this->namepool_.add(p->signature, + true, NULL); + p->section->set_name(name); + } + p->section->set_needs_symtab_index(); + p->section->set_info_section_symndx(p->section); + } + } + + this->group_signatures_.clear(); +} + +// 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 + && (parameters->options().omagic() + || ((*p)->flags() & elfcpp::PF_W) == 0)) + return *p; + } + + gold_assert(!this->script_options_->saw_phdrs_clause()); + + Output_segment* load_seg = this->make_output_segment(elfcpp::PT_LOAD, + elfcpp::PF_R); + return load_seg; +} + +// Save states of all current output segments. Store saved states +// in SEGMENT_STATES. + +void +Layout::save_segments(Segment_states* segment_states) +{ + for (Segment_list::const_iterator p = this->segment_list_.begin(); + p != this->segment_list_.end(); + ++p) + { + Output_segment* segment = *p; + // Shallow copy. + Output_segment* copy = new Output_segment(*segment); + (*segment_states)[segment] = copy; + } +} + +// Restore states of output segments and delete any segment not found in +// SEGMENT_STATES. + +void +Layout::restore_segments(const Segment_states* segment_states) +{ + // Go through the segment list and remove any segment added in the + // relaxation loop. + this->tls_segment_ = NULL; + this->relro_segment_ = NULL; + Segment_list::iterator list_iter = this->segment_list_.begin(); + while (list_iter != this->segment_list_.end()) + { + Output_segment* segment = *list_iter; + Segment_states::const_iterator states_iter = + segment_states->find(segment); + if (states_iter != segment_states->end()) + { + const Output_segment* copy = states_iter->second; + // Shallow copy to restore states. + *segment = *copy; + + // Also fix up TLS and RELRO segment pointers as appropriate. + if (segment->type() == elfcpp::PT_TLS) + this->tls_segment_ = segment; + else if (segment->type() == elfcpp::PT_GNU_RELRO) + this->relro_segment_ = segment; + + ++list_iter; + } + else + { + list_iter = this->segment_list_.erase(list_iter); + // This is a segment created during section layout. It should be + // safe to remove it since we should have removed all pointers to it. + delete segment; + } + } +} + +// Clean up after relaxation so that sections can be laid out again. + +void +Layout::clean_up_after_relaxation() +{ + // Restore the segments to point state just prior to the relaxation loop. + Script_sections* script_section = this->script_options_->script_sections(); + script_section->release_segments(); + this->restore_segments(this->segment_states_); + + // Reset section addresses and file offsets + for (Section_list::iterator p = this->section_list_.begin(); + p != this->section_list_.end(); + ++p) + { + (*p)->reset_address_and_file_offset(); + (*p)->restore_states(); + } + + // Reset special output object address and file offsets. + for (Data_list::iterator p = this->special_output_list_.begin(); + p != this->special_output_list_.end(); + ++p) + (*p)->reset_address_and_file_offset(); + + // A linker script may have created some output section data objects. + // They are useless now. + for (Output_section_data_list::const_iterator p = + this->script_output_section_data_list_.begin(); + p != this->script_output_section_data_list_.end(); + ++p) + delete *p; + this->script_output_section_data_list_.clear(); +} + +// Prepare for relaxation. + +void +Layout::prepare_for_relaxation() +{ + // Create an relaxation debug check if in debugging mode. + if (is_debugging_enabled(DEBUG_RELAXATION)) + this->relaxation_debug_check_ = new Relaxation_debug_check(); + + // Save segment states. + this->segment_states_ = new Segment_states(); + this->save_segments(this->segment_states_); + + for(Section_list::const_iterator p = this->section_list_.begin(); + p != this->section_list_.end(); + ++p) + (*p)->save_states(); + + if (is_debugging_enabled(DEBUG_RELAXATION)) + this->relaxation_debug_check_->check_output_data_for_reset_values( + this->section_list_, this->special_output_list_); + + // Also enable recording of output section data from scripts. + this->record_output_section_data_from_script_ = true; +} + +// Relaxation loop body: If target has no relaxation, this runs only once +// Otherwise, the target relaxation hook is called at the end of +// each iteration. If the hook returns true, it means re-layout of +// section is required. +// +// The number of segments created by a linking script without a PHDRS +// clause may be affected by section sizes and alignments. There is +// a remote chance that relaxation causes different number of PT_LOAD +// segments are created and sections are attached to different segments. +// Therefore, we always throw away all segments created during section +// layout. In order to be able to restart the section layout, we keep +// a copy of the segment list right before the relaxation loop and use +// that to restore the segments. +// +// PASS is the current relaxation pass number. +// SYMTAB is a symbol table. +// PLOAD_SEG is the address of a pointer for the load segment. +// PHDR_SEG is a pointer to the PHDR segment. +// SEGMENT_HEADERS points to the output segment header. +// FILE_HEADER points to the output file header. +// PSHNDX is the address to store the output section index. + +off_t inline +Layout::relaxation_loop_body( + int pass, + Target* target, + Symbol_table* symtab, + Output_segment** pload_seg, + Output_segment* phdr_seg, + Output_segment_headers* segment_headers, + Output_file_header* file_header, + unsigned int* pshndx) +{ + // If this is not the first iteration, we need to clean up after + // relaxation so that we can lay out the sections again. + if (pass != 0) + this->clean_up_after_relaxation(); + + // If there is a SECTIONS clause, put all the input sections into + // the required order. + Output_segment* load_seg; + if (this->script_options_->saw_sections_clause()) + load_seg = this->set_section_addresses_from_script(symtab); + else if (parameters->options().relocatable()) + load_seg = NULL; + else + load_seg = this->find_first_load_seg(); + + if (parameters->options().oformat_enum() + != General_options::OBJECT_FORMAT_ELF) + load_seg = NULL; + + gold_assert(phdr_seg == NULL + || load_seg != NULL + || this->script_options_->saw_sections_clause()); + + // Lay out the segment headers. + if (!parameters->options().relocatable()) + { + gold_assert(segment_headers != NULL); + if (load_seg != NULL) + load_seg->add_initial_output_data(segment_headers); + if (phdr_seg != NULL) + phdr_seg->add_initial_output_data(segment_headers); + } + + // Lay out the file header. + if (load_seg != NULL) + load_seg->add_initial_output_data(file_header); + + if (this->script_options_->saw_phdrs_clause() + && !parameters->options().relocatable()) + { + // Support use of FILEHDRS and PHDRS attachments in a PHDRS + // clause in a linker script. + Script_sections* ss = this->script_options_->script_sections(); + ss->put_headers_in_phdrs(file_header, segment_headers); + } + + // We set the output section indexes in set_segment_offsets and + // set_section_indexes. + *pshndx = 1; + + // Set the file offsets of all the segments, and all the sections + // they contain. + off_t off; + if (!parameters->options().relocatable()) + off = this->set_segment_offsets(target, load_seg, pshndx); + else + off = this->set_relocatable_section_offsets(file_header, pshndx); + + // Verify that the dummy relaxation does not change anything. + if (is_debugging_enabled(DEBUG_RELAXATION)) + { + if (pass == 0) + this->relaxation_debug_check_->read_sections(this->section_list_); + else + this->relaxation_debug_check_->verify_sections(this->section_list_); + } + + *pload_seg = load_seg; + return off; +} + +// 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* target, const Task* task) +{ + target->finalize_sections(this); + + this->count_local_symbols(task, input_objects); + + this->link_stabs_sections(); + + Output_segment* phdr_seg = NULL; + if (!parameters->options().relocatable() && !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. + if (!this->script_options_->saw_phdrs_clause()) + phdr_seg = this->make_output_segment(elfcpp::PT_PHDR, elfcpp::PF_R); + + // Create the dynamic symbol table, including the hash table. + Output_section* dynstr; + std::vector dynamic_symbols; + unsigned int local_dynamic_count; + Versions versions(*this->script_options()->version_script_info(), + &this->dynpool_); + this->create_dynamic_symtab(input_objects, 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->options().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); + } + + if (this->incremental_inputs_) + { + this->incremental_inputs_->finalize(); + this->create_incremental_info_sections(); + } + + // Create segment headers. + Output_segment_headers* segment_headers = + (parameters->options().relocatable() + ? NULL + : new Output_segment_headers(this->segment_list_)); + + // Lay out the file header. + Output_file_header* file_header + = new Output_file_header(target, symtab, segment_headers, + parameters->options().entry()); + + this->special_output_list_.push_back(file_header); + if (segment_headers != NULL) + this->special_output_list_.push_back(segment_headers); + + // Find approriate places for orphan output sections if we are using + // a linker script. + if (this->script_options_->saw_sections_clause()) + this->place_orphan_sections_in_script(); + + Output_segment* load_seg; + off_t off; + unsigned int shndx; + int pass = 0; + + // Take a snapshot of the section layout as needed. + if (target->may_relax()) + this->prepare_for_relaxation(); + + // Run the relaxation loop to lay out sections. + do + { + off = this->relaxation_loop_body(pass, target, symtab, &load_seg, + phdr_seg, segment_headers, file_header, + &shndx); + pass++; + } + while (target->may_relax() + && target->relax(pass, input_objects, symtab, this)); + + // Set the file offsets of all the non-data sections we've seen so + // far which don't have to wait for the input sections. We need + // this in order to finalize local symbols in non-allocated + // sections. + off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS); + + // Set the section indexes of all unallocated sections seen so far, + // in case any of them are somehow referenced by a symbol. + shndx = this->set_section_indexes(shndx); + + // Create the symbol table sections. + this->create_symtab_sections(input_objects, symtab, shndx, &off); + if (!parameters->doing_static_link()) + this->assign_local_dynsym_offsets(input_objects); + + // Process any symbol assignments from a linker script. This must + // be called after the symbol table has been finalized. + this->script_options_->finalize_symbols(symtab, this); + + // Create the .shstrtab section. + Output_section* shstrtab_section = this->create_shstrtab(); + + // Set the file offsets of the rest of the non-data sections which + // don't have to wait for the input sections. + off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS); + + // Now that all sections have been created, set the section indexes + // for any sections which haven't been done yet. + shndx = this->set_section_indexes(shndx); + + // Create the section table header. + this->create_shdrs(shstrtab_section, &off); + + // If there are no sections which require postprocessing, we can + // handle the section names now, and avoid a resize later. + if (!this->any_postprocessing_sections_) + off = this->set_section_offsets(off, + STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS); + + file_header->set_section_info(this->section_headers_, shstrtab_section); + + // Now we know exactly where everything goes in the output file + // (except for non-allocated sections which require postprocessing). + Output_data::layout_complete(); + + this->output_file_size_ = off; + + return off; +} + +// Create a note header following the format defined in the ELF ABI. +// NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name +// of the section to create, DESCSZ is the size of the descriptor. +// ALLOCATE is true if the section should be allocated in memory. +// This returns the new note section. It sets *TRAILING_PADDING to +// the number of trailing zero bytes required. + +Output_section* +Layout::create_note(const char* name, int note_type, + const char* section_name, size_t descsz, + bool allocate, size_t* trailing_padding) +{ + // 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->target().get_size(); +#else + const int size = 32; +#endif + + // The contents of the .note section. + size_t namesz = strlen(name) + 1; + size_t aligned_namesz = align_address(namesz, size / 8); + size_t aligned_descsz = align_address(descsz, size / 8); + + size_t notehdrsz = 3 * (size / 8) + aligned_namesz; + + unsigned char* buffer = new unsigned char[notehdrsz]; + memset(buffer, 0, notehdrsz); + + bool is_big_endian = parameters->target().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); + + elfcpp::Elf_Xword flags = 0; + if (allocate) + flags = elfcpp::SHF_ALLOC; + Output_section* os = this->choose_output_section(NULL, section_name, + elfcpp::SHT_NOTE, + flags, false); + if (os == NULL) + return NULL; + + Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz, + size / 8, + "** note header"); + os->add_output_section_data(posd); + + *trailing_padding = aligned_descsz - descsz; + + return os; +} + +// For an executable or shared library, create a note to record the +// version of gold used to create the binary. + +void +Layout::create_gold_note() +{ + if (parameters->options().relocatable()) + return; + + std::string desc = std::string("gold ") + gold::get_version_string(); + + size_t trailing_padding; + Output_section *os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION, + ".note.gnu.gold-version", desc.size(), + false, &trailing_padding); + if (os == NULL) + return; + + Output_section_data* posd = new Output_data_const(desc, 4); + os->add_output_section_data(posd); + + if (trailing_padding > 0) + { + posd = new Output_data_zero_fill(trailing_padding, 0); + 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() +{ + bool is_stack_executable; + if (parameters->options().is_execstack_set()) + is_stack_executable = parameters->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 = + parameters->target().is_default_stack_executable(); + else + is_stack_executable = false; + } + + if (parameters->options().relocatable()) + { + 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 + { + if (this->script_options_->saw_phdrs_clause()) + return; + int flags = elfcpp::PF_R | elfcpp::PF_W; + if (is_stack_executable) + flags |= elfcpp::PF_X; + this->make_output_segment(elfcpp::PT_GNU_STACK, flags); + } +} + +// If --build-id was used, set up the build ID note. + +void +Layout::create_build_id() +{ + if (!parameters->options().user_set_build_id()) + return; + + const char* style = parameters->options().build_id(); + if (strcmp(style, "none") == 0) + return; + + // Set DESCSZ to the size of the note descriptor. When possible, + // set DESC to the note descriptor contents. + size_t descsz; + std::string desc; + if (strcmp(style, "md5") == 0) + descsz = 128 / 8; + else if (strcmp(style, "sha1") == 0) + descsz = 160 / 8; + else if (strcmp(style, "uuid") == 0) + { + const size_t uuidsz = 128 / 8; + + char buffer[uuidsz]; + memset(buffer, 0, uuidsz); + + int descriptor = open_descriptor(-1, "/dev/urandom", O_RDONLY); + if (descriptor < 0) + gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"), + strerror(errno)); + else + { + ssize_t got = ::read(descriptor, buffer, uuidsz); + release_descriptor(descriptor, true); + if (got < 0) + gold_error(_("/dev/urandom: read failed: %s"), strerror(errno)); + else if (static_cast(got) != uuidsz) + gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"), + uuidsz, got); + } + + desc.assign(buffer, uuidsz); + descsz = uuidsz; + } + else if (strncmp(style, "0x", 2) == 0) + { + hex_init(); + const char* p = style + 2; + while (*p != '\0') + { + if (hex_p(p[0]) && hex_p(p[1])) + { + char c = (hex_value(p[0]) << 4) | hex_value(p[1]); + desc += c; + p += 2; + } + else if (*p == '-' || *p == ':') + ++p; + else + gold_fatal(_("--build-id argument '%s' not a valid hex number"), + style); + } + descsz = desc.size(); + } + else + gold_fatal(_("unrecognized --build-id argument '%s'"), style); + + // Create the note. + size_t trailing_padding; + Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID, + ".note.gnu.build-id", descsz, true, + &trailing_padding); + if (os == NULL) + return; + + if (!desc.empty()) + { + // We know the value already, so we fill it in now. + gold_assert(desc.size() == descsz); + + Output_section_data* posd = new Output_data_const(desc, 4); + os->add_output_section_data(posd); + + if (trailing_padding != 0) + { + posd = new Output_data_zero_fill(trailing_padding, 0); + os->add_output_section_data(posd); + } + } + else + { + // We need to compute a checksum after we have completed the + // link. + gold_assert(trailing_padding == 0); + this->build_id_note_ = new Output_data_zero_fill(descsz, 4); + os->add_output_section_data(this->build_id_note_); + } +} + +// If we have both .stabXX and .stabXXstr sections, then the sh_link +// field of the former should point to the latter. I'm not sure who +// started this, but the GNU linker does it, and some tools depend +// upon it. + +void +Layout::link_stabs_sections() +{ + if (!this->have_stabstr_section_) + return; + + for (Section_list::iterator p = this->section_list_.begin(); + p != this->section_list_.end(); + ++p) + { + if ((*p)->type() != elfcpp::SHT_STRTAB) + continue; + + const char* name = (*p)->name(); + if (strncmp(name, ".stab", 5) != 0) + continue; + + size_t len = strlen(name); + if (strcmp(name + len - 3, "str") != 0) + continue; + + std::string stab_name(name, len - 3); + Output_section* stab_sec; + stab_sec = this->find_output_section(stab_name.c_str()); + if (stab_sec != NULL) + stab_sec->set_link_section(*p); + } +} + +// Create .gnu_incremental_inputs and .gnu_incremental_strtab sections needed +// for the next run of incremental linking to check what has changed. + +void +Layout::create_incremental_info_sections() +{ + gold_assert(this->incremental_inputs_ != NULL); + + // Add the .gnu_incremental_inputs section. + const char *incremental_inputs_name = + this->namepool_.add(".gnu_incremental_inputs", false, NULL); + Output_section* inputs_os = + this->make_output_section(incremental_inputs_name, + elfcpp::SHT_GNU_INCREMENTAL_INPUTS, 0); + Output_section_data* posd = + this->incremental_inputs_->create_incremental_inputs_section_data(); + inputs_os->add_output_section_data(posd); + + // Add the .gnu_incremental_strtab section. + const char *incremental_strtab_name = + this->namepool_.add(".gnu_incremental_strtab", false, NULL); + Output_section* strtab_os = this->make_output_section(incremental_strtab_name, + elfcpp::SHT_STRTAB, + 0); + Output_data_strtab* strtab_data = + new Output_data_strtab(this->incremental_inputs_->get_stringpool()); + strtab_os->add_output_section_data(strtab_data); + + inputs_os->set_link_section(strtab_data); +} + +// 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 except for the PT_GNU_RELRO + // segment, 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 + && type2 != elfcpp::PT_GNU_RELRO) + return false; + if (type2 == elfcpp::PT_TLS + && type1 != elfcpp::PT_TLS + && type1 != elfcpp::PT_GNU_RELRO) + return true; + + // We put the PT_GNU_RELRO segment last, because that is where the + // dynamic linker expects to find it (as with PT_TLS, this is just + // for efficiency). + if (type1 == elfcpp::PT_GNU_RELRO && type2 != elfcpp::PT_GNU_RELRO) + return false; + if (type2 == elfcpp::PT_GNU_RELRO && type1 != elfcpp::PT_GNU_RELRO) + 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; + } + + // If the addresses are set already, sort by load address. + if (seg1->are_addresses_set()) + { + if (!seg2->are_addresses_set()) + return true; + + unsigned int section_count1 = seg1->output_section_count(); + unsigned int section_count2 = seg2->output_section_count(); + if (section_count1 == 0 && section_count2 > 0) + return true; + if (section_count1 > 0 && section_count2 == 0) + return false; + + uint64_t paddr1 = seg1->first_section_load_address(); + uint64_t paddr2 = seg2->first_section_load_address(); + if (paddr1 != paddr2) + return paddr1 < paddr2; + } + else if (seg2->are_addresses_set()) + return false; + + // A segment which holds large data comes after a segment which does + // not hold large data. + if (seg1->is_large_data_segment()) + { + if (!seg2->is_large_data_segment()) + return false; + } + else if (seg2->is_large_data_segment()) + return true; + + // Otherwise, we sort PT_LOAD segments based on the flags. Readonly + // segments come before writable segments. Then writable segments + // with data come before writable segments without data. 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_W) != 0 + && seg1->has_any_data_sections() != seg2->has_any_data_sections()) + return seg1->has_any_data_sections(); + 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; + + // We shouldn't get here--we shouldn't create segments which we + // can't distinguish. + gold_unreachable(); +} + +// Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE. + +static off_t +align_file_offset(off_t off, uint64_t addr, uint64_t abi_pagesize) +{ + uint64_t unsigned_off = off; + uint64_t aligned_off = ((unsigned_off & ~(abi_pagesize - 1)) + | (addr & (abi_pagesize - 1))); + if (aligned_off < unsigned_off) + aligned_off += abi_pagesize; + return aligned_off; +} + +// 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 (parameters->options().user_set_Ttext()) + addr = parameters->options().Ttext(); + else if (parameters->options().output_is_position_independent()) + addr = 0; + else + addr = target->default_text_segment_address(); + off_t off = 0; + + // If LOAD_SEG is NULL, then the file header and segment headers + // will not be loadable. But they still need to be at offset 0 in + // the file. Set their offsets now. + if (load_seg == NULL) + { + for (Data_list::iterator p = this->special_output_list_.begin(); + p != this->special_output_list_.end(); + ++p) + { + off = align_address(off, (*p)->addralign()); + (*p)->set_address_and_file_offset(0, off); + off += (*p)->data_size(); + } + } + + const bool check_sections = parameters->options().check_sections(); + Output_segment* last_load_segment = NULL; + + 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; + + bool are_addresses_set = (*p)->are_addresses_set(); + if (are_addresses_set) + { + // When it comes to setting file offsets, we care about + // the physical address. + addr = (*p)->paddr(); + } + else if (parameters->options().user_set_Tdata() + && ((*p)->flags() & elfcpp::PF_W) != 0 + && (!parameters->options().user_set_Tbss() + || (*p)->has_any_data_sections())) + { + addr = parameters->options().Tdata(); + are_addresses_set = true; + } + else if (parameters->options().user_set_Tbss() + && ((*p)->flags() & elfcpp::PF_W) != 0 + && !(*p)->has_any_data_sections()) + { + addr = parameters->options().Tbss(); + are_addresses_set = true; + } + + uint64_t orig_addr = addr; + uint64_t orig_off = off; + + uint64_t aligned_addr = 0; + uint64_t abi_pagesize = target->abi_pagesize(); + uint64_t common_pagesize = target->common_pagesize(); + + if (!parameters->options().nmagic() + && !parameters->options().omagic()) + (*p)->set_minimum_p_align(common_pagesize); + + if (!are_addresses_set) + { + // 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. + + addr = align_address(addr, (*p)->maximum_alignment()); + aligned_addr = addr; + + if (was_readonly && ((*p)->flags() & elfcpp::PF_W) != 0) + { + if ((addr & (abi_pagesize - 1)) != 0) + addr = addr + abi_pagesize; + } + + off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); + } + + if (!parameters->options().nmagic() + && !parameters->options().omagic()) + off = align_file_offset(off, addr, abi_pagesize); + else if (load_seg == NULL) + { + // This is -N or -n with a section script which prevents + // us from using a load segment. We need to ensure that + // the file offset is aligned to the alignment of the + // segment. This is because the linker script + // implicitly assumed a zero offset. If we don't align + // here, then the alignment of the sections in the + // linker script may not match the alignment of the + // sections in the set_section_addresses call below, + // causing an error about dot moving backward. + off = align_address(off, (*p)->maximum_alignment()); + } + + unsigned int shndx_hold = *pshndx; + uint64_t new_addr = (*p)->set_section_addresses(this, false, 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 (!are_addresses_set && aligned_addr != addr) + { + 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); + addr = align_address(addr, (*p)->maximum_alignment()); + off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); + off = align_file_offset(off, addr, abi_pagesize); + new_addr = (*p)->set_section_addresses(this, true, addr, + &off, pshndx); + } + } + + addr = new_addr; + + if (((*p)->flags() & elfcpp::PF_W) == 0) + was_readonly = true; + + // Implement --check-sections. We know that the segments + // are sorted by LMA. + if (check_sections && last_load_segment != NULL) + { + gold_assert(last_load_segment->paddr() <= (*p)->paddr()); + if (last_load_segment->paddr() + last_load_segment->memsz() + > (*p)->paddr()) + { + unsigned long long lb1 = last_load_segment->paddr(); + unsigned long long le1 = lb1 + last_load_segment->memsz(); + unsigned long long lb2 = (*p)->paddr(); + unsigned long long le2 = lb2 + (*p)->memsz(); + gold_error(_("load segment overlap [0x%llx -> 0x%llx] and " + "[0x%llx -> 0x%llx]"), + lb1, le1, lb2, le2); + } + } + last_load_segment = *p; + } + } + + // 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(); + } + + // Set the TLS offsets for each section in the PT_TLS segment. + if (this->tls_segment_ != NULL) + this->tls_segment_->set_tls_offsets(); + + return off; +} + +// Set the offsets of all the allocated sections when doing a +// relocatable link. This does the same jobs as set_segment_offsets, +// only for a relocatable link. + +off_t +Layout::set_relocatable_section_offsets(Output_data* file_header, + unsigned int *pshndx) +{ + off_t off = 0; + + file_header->set_address_and_file_offset(0, 0); + off += file_header->data_size(); + + for (Section_list::iterator p = this->section_list_.begin(); + p != this->section_list_.end(); + ++p) + { + // We skip unallocated sections here, except that group sections + // have to come first. + if (((*p)->flags() & elfcpp::SHF_ALLOC) == 0 + && (*p)->type() != elfcpp::SHT_GROUP) + continue; + + off = align_address(off, (*p)->addralign()); + + // The linker script might have set the address. + if (!(*p)->is_address_valid()) + (*p)->set_address(0); + (*p)->set_file_offset(off); + (*p)->finalize_data_size(); + off += (*p)->data_size(); + + (*p)->set_out_shndx(*pshndx); + ++*pshndx; + } + + return off; +} + +// Set the file offset of all the sections not associated with a +// segment. + +off_t +Layout::set_section_offsets(off_t off, Layout::Section_offset_pass pass) +{ + for (Section_list::iterator p = this->unattached_section_list_.begin(); + p != this->unattached_section_list_.end(); + ++p) + { + // The symtab section is handled in create_symtab_sections. + if (*p == this->symtab_section_) + continue; + + // If we've already set the data size, don't set it again. + if ((*p)->is_offset_valid() && (*p)->is_data_size_valid()) + continue; + + if (pass == BEFORE_INPUT_SECTIONS_PASS + && (*p)->requires_postprocessing()) + { + (*p)->create_postprocessing_buffer(); + this->any_postprocessing_sections_ = true; + } + + if (pass == BEFORE_INPUT_SECTIONS_PASS + && (*p)->after_input_sections()) + continue; + else if (pass == POSTPROCESSING_SECTIONS_PASS + && (!(*p)->after_input_sections() + || (*p)->type() == elfcpp::SHT_STRTAB)) + continue; + else if (pass == STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS + && (!(*p)->after_input_sections() + || (*p)->type() != elfcpp::SHT_STRTAB)) + continue; + + off = align_address(off, (*p)->addralign()); + (*p)->set_file_offset(off); + (*p)->finalize_data_size(); + off += (*p)->data_size(); + + // At this point the name must be set. + if (pass != STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS) + this->namepool_.add((*p)->name(), false, NULL); + } + return off; +} + +// Set the section indexes of all the sections not associated with a +// segment. + +unsigned int +Layout::set_section_indexes(unsigned int shndx) +{ + for (Section_list::iterator p = this->unattached_section_list_.begin(); + p != this->unattached_section_list_.end(); + ++p) + { + if (!(*p)->has_out_shndx()) + { + (*p)->set_out_shndx(shndx); + ++shndx; + } + } + return shndx; +} + +// Set the section addresses according to the linker script. This is +// only called when we see a SECTIONS clause. This returns the +// program segment which should hold the file header and segment +// headers, if any. It will return NULL if they should not be in a +// segment. + +Output_segment* +Layout::set_section_addresses_from_script(Symbol_table* symtab) +{ + Script_sections* ss = this->script_options_->script_sections(); + gold_assert(ss->saw_sections_clause()); + return this->script_options_->set_section_addresses(symtab, this); +} + +// Place the orphan sections in the linker script. + +void +Layout::place_orphan_sections_in_script() +{ + Script_sections* ss = this->script_options_->script_sections(); + gold_assert(ss->saw_sections_clause()); + + // Place each orphaned output section in the script. + for (Section_list::iterator p = this->section_list_.begin(); + p != this->section_list_.end(); + ++p) + { + if (!(*p)->found_in_sections_clause()) + ss->place_orphan(*p); + } +} + +// Count the local symbols in the regular symbol table and the dynamic +// symbol table, and build the respective string pools. + +void +Layout::count_local_symbols(const Task* task, + const Input_objects* input_objects) +{ + // First, figure out an upper bound on the number of symbols we'll + // be inserting into each pool. This helps us create the pools with + // the right size, to avoid unnecessary hashtable resizing. + unsigned int symbol_count = 0; + for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); + p != input_objects->relobj_end(); + ++p) + symbol_count += (*p)->local_symbol_count(); + + // Go from "upper bound" to "estimate." We overcount for two + // reasons: we double-count symbols that occur in more than one + // object file, and we count symbols that are dropped from the + // output. Add it all together and assume we overcount by 100%. + symbol_count /= 2; + + // We assume all symbols will go into both the sympool and dynpool. + this->sympool_.reserve(symbol_count); + this->dynpool_.reserve(symbol_count); + + for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); + p != input_objects->relobj_end(); + ++p) + { + Task_lock_obj tlo(task, *p); + (*p)->count_local_symbols(&this->sympool_, &this->dynpool_); + } +} + +// 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. SHNUM is the number of sections so far. + +void +Layout::create_symtab_sections(const Input_objects* input_objects, + Symbol_table* symtab, + unsigned int shnum, + off_t* poff) +{ + int symsize; + unsigned int align; + if (parameters->target().get_size() == 32) + { + symsize = elfcpp::Elf_sizes<32>::sym_size; + align = 4; + } + else if (parameters->target().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) + { + unsigned int index = (*p)->finalize_local_symbols(local_symbol_index, + off, symtab); + off += (index - local_symbol_index) * symsize; + local_symbol_index = index; + } + + unsigned int local_symcount = local_symbol_index; + gold_assert(static_cast(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(dyncount * symsize) + == this->dynsym_section_->data_size() - locsize); + } + + off = symtab->finalize(off, dynoff, dyn_global_index, dyncount, + &this->sympool_, &local_symcount); + + if (!parameters->options().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_fixed_space(off - startoff, + align, + "** symtab"); + osymtab->add_output_section_data(pos); + + // We generate a .symtab_shndx section if we have more than + // SHN_LORESERVE sections. Technically it is possible that we + // don't need one, because it is possible that there are no + // symbols in any of sections with indexes larger than + // SHN_LORESERVE. That is probably unusual, though, and it is + // easier to always create one than to compute section indexes + // twice (once here, once when writing out the symbols). + if (shnum >= elfcpp::SHN_LORESERVE) + { + const char* symtab_xindex_name = this->namepool_.add(".symtab_shndx", + false, NULL); + Output_section* osymtab_xindex = + this->make_output_section(symtab_xindex_name, + elfcpp::SHT_SYMTAB_SHNDX, 0); + + size_t symcount = (off - startoff) / symsize; + this->symtab_xindex_ = new Output_symtab_xindex(symcount); + + osymtab_xindex->add_output_section_data(this->symtab_xindex_); + + osymtab_xindex->set_link_section(osymtab); + osymtab_xindex->set_addralign(4); + osymtab_xindex->set_entsize(4); + + osymtab_xindex->set_after_input_sections(); + + // This tells the driver code to wait until the symbol table + // has written out before writing out the postprocessing + // sections, including the .symtab_shndx section. + this->any_postprocessing_sections_ = true; + } + + 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_file_offset(startoff); + osymtab->finalize_data_size(); + 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); + + Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0); + + // We can't write out this section until we've set all the section + // names, and we don't set the names of compressed output sections + // until relocations are complete. + os->set_after_input_sections(); + + 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. + +void +Layout::create_shdrs(const Output_section* shstrtab_section, off_t* poff) +{ + Output_section_headers* oshdrs; + oshdrs = new Output_section_headers(this, + &this->segment_list_, + &this->section_list_, + &this->unattached_section_list_, + &this->namepool_, + shstrtab_section); + off_t off = align_address(*poff, oshdrs->addralign()); + oshdrs->set_address_and_file_offset(0, off); + off += oshdrs->data_size(); + *poff = off; + this->section_headers_ = oshdrs; +} + +// Count the allocated sections. + +size_t +Layout::allocated_output_section_count() const +{ + size_t section_count = 0; + for (Segment_list::const_iterator p = this->segment_list_.begin(); + p != this->segment_list_.end(); + ++p) + section_count += (*p)->output_section_count(); + return section_count; +} + +// Create the dynamic symbol table. + +void +Layout::create_dynamic_symtab(const Input_objects* input_objects, + Symbol_table* symtab, + Output_section **pdynstr, + unsigned int* plocal_dynamic_count, + std::vector* 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; + } + } + + // Count the local symbols that need to go in the dynamic symbol table, + // and set the dynamic symbol indexes. + for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); + p != input_objects->relobj_end(); + ++p) + { + unsigned int new_index = (*p)->set_local_dynsym_indexes(index); + index = new_index; + } + + unsigned int local_symcount = index; + *plocal_dynamic_count = local_symcount; + + index = symtab->set_dynsym_indexes(index, pdynamic_symbols, + &this->dynpool_, pversions); + + int symsize; + unsigned int align; + const int size = parameters->target().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. + + Output_section* dynsym = this->choose_output_section(NULL, ".dynsym", + elfcpp::SHT_DYNSYM, + elfcpp::SHF_ALLOC, + false); + + Output_section_data* odata = new Output_data_fixed_space(index * symsize, + align, + "** dynsym"); + 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); + + // If there are more than SHN_LORESERVE allocated sections, we + // create a .dynsym_shndx section. It is possible that we don't + // need one, because it is possible that there are no dynamic + // symbols in any of the sections with indexes larger than + // SHN_LORESERVE. This is probably unusual, though, and at this + // time we don't know the actual section indexes so it is + // inconvenient to check. + if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE) + { + Output_section* dynsym_xindex = + this->choose_output_section(NULL, ".dynsym_shndx", + elfcpp::SHT_SYMTAB_SHNDX, + elfcpp::SHF_ALLOC, + false); + + this->dynsym_xindex_ = new Output_symtab_xindex(index); + + dynsym_xindex->add_output_section_data(this->dynsym_xindex_); + + dynsym_xindex->set_link_section(dynsym); + dynsym_xindex->set_addralign(4); + dynsym_xindex->set_entsize(4); + + dynsym_xindex->set_after_input_sections(); + + // This tells the driver code to wait until the symbol table has + // written out before writing out the postprocessing sections, + // including the .dynsym_shndx section. + this->any_postprocessing_sections_ = true; + } + + // Create the dynamic string table section. + + Output_section* dynstr = this->choose_output_section(NULL, ".dynstr", + elfcpp::SHT_STRTAB, + elfcpp::SHF_ALLOC, + false); + + 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. + + if (strcmp(parameters->options().hash_style(), "sysv") == 0 + || strcmp(parameters->options().hash_style(), "both") == 0) + { + unsigned char* phash; + unsigned int hashlen; + Dynobj::create_elf_hash_table(*pdynamic_symbols, local_symcount, + &phash, &hashlen); + + Output_section* hashsec = this->choose_output_section(NULL, ".hash", + elfcpp::SHT_HASH, + elfcpp::SHF_ALLOC, + false); + + Output_section_data* hashdata = new Output_data_const_buffer(phash, + hashlen, + align, + "** hash"); + hashsec->add_output_section_data(hashdata); + + hashsec->set_link_section(dynsym); + hashsec->set_entsize(4); + + odyn->add_section_address(elfcpp::DT_HASH, hashsec); + } + + if (strcmp(parameters->options().hash_style(), "gnu") == 0 + || strcmp(parameters->options().hash_style(), "both") == 0) + { + unsigned char* phash; + unsigned int hashlen; + Dynobj::create_gnu_hash_table(*pdynamic_symbols, local_symcount, + &phash, &hashlen); + + Output_section* hashsec = this->choose_output_section(NULL, ".gnu.hash", + elfcpp::SHT_GNU_HASH, + elfcpp::SHF_ALLOC, + false); + + Output_section_data* hashdata = new Output_data_const_buffer(phash, + hashlen, + align, + "** hash"); + hashsec->add_output_section_data(hashdata); + + hashsec->set_link_section(dynsym); + hashsec->set_entsize(4); + + odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec); + } +} + +// Assign offsets to each local portion of the dynamic symbol table. + +void +Layout::assign_local_dynsym_offsets(const Input_objects* input_objects) +{ + Output_section* dynsym = this->dynsym_section_; + gold_assert(dynsym != NULL); + + off_t off = dynsym->offset(); + + // Skip the dummy symbol at the start of the section. + off += dynsym->entsize(); + + for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); + p != input_objects->relobj_end(); + ++p) + { + unsigned int count = (*p)->set_local_dynsym_offset(off); + off += count * dynsym->entsize(); + } +} + +// Create the version sections. + +void +Layout::create_version_sections(const Versions* versions, + const Symbol_table* symtab, + unsigned int local_symcount, + const std::vector& dynamic_symbols, + const Output_section* dynstr) +{ + if (!versions->any_defs() && !versions->any_needs()) + return; + + switch (parameters->size_and_endianness()) + { +#ifdef HAVE_TARGET_32_LITTLE + case Parameters::TARGET_32_LITTLE: + this->sized_create_version_sections<32, false>(versions, symtab, + local_symcount, + dynamic_symbols, dynstr); + break; +#endif +#ifdef HAVE_TARGET_32_BIG + case Parameters::TARGET_32_BIG: + this->sized_create_version_sections<32, true>(versions, symtab, + local_symcount, + dynamic_symbols, dynstr); + break; +#endif +#ifdef HAVE_TARGET_64_LITTLE + case Parameters::TARGET_64_LITTLE: + this->sized_create_version_sections<64, false>(versions, symtab, + local_symcount, + dynamic_symbols, dynstr); + break; +#endif +#ifdef HAVE_TARGET_64_BIG + case Parameters::TARGET_64_BIG: + this->sized_create_version_sections<64, true>(versions, symtab, + local_symcount, + dynamic_symbols, dynstr); + break; +#endif + default: + gold_unreachable(); + } +} + +// Create the version sections, sized version. + +template +void +Layout::sized_create_version_sections( + const Versions* versions, + const Symbol_table* symtab, + unsigned int local_symcount, + const std::vector& dynamic_symbols, + const Output_section* dynstr) +{ + Output_section* vsec = this->choose_output_section(NULL, ".gnu.version", + elfcpp::SHT_GNU_versym, + elfcpp::SHF_ALLOC, + false); + + unsigned char* vbuf; + unsigned int vsize; + versions->symbol_section_contents(symtab, &this->dynpool_, + local_symcount, + dynamic_symbols, + &vbuf, &vsize); + + Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2, + "** versions"); + + 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()) + { + Output_section* vdsec; + vdsec= this->choose_output_section(NULL, ".gnu.version_d", + elfcpp::SHT_GNU_verdef, + elfcpp::SHF_ALLOC, + false); + + unsigned char* vdbuf; + unsigned int vdsize; + unsigned int vdentries; + versions->def_section_contents(&this->dynpool_, &vdbuf, + &vdsize, &vdentries); + + Output_section_data* vddata = + new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs"); + + 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()) + { + Output_section* vnsec; + vnsec = this->choose_output_section(NULL, ".gnu.version_r", + elfcpp::SHT_GNU_verneed, + elfcpp::SHF_ALLOC, + false); + + unsigned char* vnbuf; + unsigned int vnsize; + unsigned int vnentries; + versions->need_section_contents(&this->dynpool_, + &vnbuf, &vnsize, + &vnentries); + + Output_section_data* vndata = + new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs"); + + 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 = parameters->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); + + Output_section* osec = this->choose_output_section(NULL, ".interp", + elfcpp::SHT_PROGBITS, + elfcpp::SHF_ALLOC, + false); + osec->add_output_section_data(odata); + + if (!this->script_options_->saw_phdrs_clause()) + { + Output_segment* oseg = this->make_output_segment(elfcpp::PT_INTERP, + elfcpp::PF_R); + oseg->add_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) +{ + if (!this->script_options_->saw_phdrs_clause()) + { + Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC, + (elfcpp::PF_R + | elfcpp::PF_W)); + oseg->add_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()); + } + + if (parameters->options().shared()) + { + const char* soname = parameters->options().soname(); + if (soname != NULL) + odyn->add_string(elfcpp::DT_SONAME, soname); + } + + Symbol* sym = symtab->lookup(parameters->options().init()); + if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) + odyn->add_symbol(elfcpp::DT_INIT, sym); + + sym = symtab->lookup(parameters->options().fini()); + if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) + odyn->add_symbol(elfcpp::DT_FINI, sym); + + // Look for .init_array, .preinit_array and .fini_array by checking + // section types. + for(Layout::Section_list::const_iterator p = this->section_list_.begin(); + p != this->section_list_.end(); + ++p) + switch((*p)->type()) + { + case elfcpp::SHT_FINI_ARRAY: + odyn->add_section_address(elfcpp::DT_FINI_ARRAY, *p); + odyn->add_section_size(elfcpp::DT_FINI_ARRAYSZ, *p); + break; + case elfcpp::SHT_INIT_ARRAY: + odyn->add_section_address(elfcpp::DT_INIT_ARRAY, *p); + odyn->add_section_size(elfcpp::DT_INIT_ARRAYSZ, *p); + break; + case elfcpp::SHT_PREINIT_ARRAY: + odyn->add_section_address(elfcpp::DT_PREINIT_ARRAY, *p); + odyn->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ, *p); + break; + default: + break; + } + + // Add a DT_RPATH entry if needed. + const General_options::Dir_list& rpath(parameters->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); + if (parameters->options().enable_new_dtags()) + odyn->add_string(elfcpp::DT_RUNPATH, rpath_val); + } + + // Look for text segments that have dynamic relocations. + bool have_textrel = false; + if (!this->script_options_->saw_sections_clause()) + { + for (Segment_list::const_iterator p = this->segment_list_.begin(); + p != this->segment_list_.end(); + ++p) + { + if (((*p)->flags() & elfcpp::PF_W) == 0 + && (*p)->dynamic_reloc_count() > 0) + { + have_textrel = true; + break; + } + } + } + else + { + // We don't know the section -> segment mapping, so we are + // conservative and just look for readonly sections with + // relocations. If those sections wind up in writable segments, + // then we have created an unnecessary DT_TEXTREL entry. + for (Section_list::const_iterator p = this->section_list_.begin(); + p != this->section_list_.end(); + ++p) + { + if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0 + && ((*p)->flags() & elfcpp::SHF_WRITE) == 0 + && ((*p)->dynamic_reloc_count() > 0)) + { + have_textrel = true; + break; + } + } + } + + // Add a DT_FLAGS entry. We add it even if no flags are set so that + // post-link tools can easily modify these flags if desired. + unsigned int flags = 0; + if (have_textrel) + { + // Add a DT_TEXTREL for compatibility with older loaders. + odyn->add_constant(elfcpp::DT_TEXTREL, 0); + flags |= elfcpp::DF_TEXTREL; + } + if (parameters->options().shared() && this->has_static_tls()) + flags |= elfcpp::DF_STATIC_TLS; + if (parameters->options().origin()) + flags |= elfcpp::DF_ORIGIN; + if (parameters->options().Bsymbolic()) + { + flags |= elfcpp::DF_SYMBOLIC; + // Add DT_SYMBOLIC for compatibility with older loaders. + odyn->add_constant(elfcpp::DT_SYMBOLIC, 0); + } + if (parameters->options().now()) + flags |= elfcpp::DF_BIND_NOW; + odyn->add_constant(elfcpp::DT_FLAGS, flags); + + flags = 0; + if (parameters->options().initfirst()) + flags |= elfcpp::DF_1_INITFIRST; + if (parameters->options().interpose()) + flags |= elfcpp::DF_1_INTERPOSE; + if (parameters->options().loadfltr()) + flags |= elfcpp::DF_1_LOADFLTR; + if (parameters->options().nodefaultlib()) + flags |= elfcpp::DF_1_NODEFLIB; + if (parameters->options().nodelete()) + flags |= elfcpp::DF_1_NODELETE; + if (parameters->options().nodlopen()) + flags |= elfcpp::DF_1_NOOPEN; + if (parameters->options().nodump()) + flags |= elfcpp::DF_1_NODUMP; + if (!parameters->options().shared()) + flags &= ~(elfcpp::DF_1_INITFIRST + | elfcpp::DF_1_NODELETE + | elfcpp::DF_1_NOOPEN); + if (parameters->options().origin()) + flags |= elfcpp::DF_1_ORIGIN; + if (parameters->options().now()) + flags |= elfcpp::DF_1_NOW; + if (flags) + odyn->add_constant(elfcpp::DT_FLAGS_1, flags); +} + +// The mapping of input section name prefixes to output section names. +// In some cases one prefix is itself a prefix of another prefix; in +// such a case the longer prefix must come first. These prefixes are +// based on the GNU linker default ELF linker script. + +#define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 } +const Layout::Section_name_mapping Layout::section_name_mapping[] = +{ + MAPPING_INIT(".text.", ".text"), + MAPPING_INIT(".ctors.", ".ctors"), + MAPPING_INIT(".dtors.", ".dtors"), + MAPPING_INIT(".rodata.", ".rodata"), + MAPPING_INIT(".data.rel.ro.local", ".data.rel.ro.local"), + MAPPING_INIT(".data.rel.ro", ".data.rel.ro"), + MAPPING_INIT(".data.", ".data"), + MAPPING_INIT(".bss.", ".bss"), + MAPPING_INIT(".tdata.", ".tdata"), + MAPPING_INIT(".tbss.", ".tbss"), + MAPPING_INIT(".init_array.", ".init_array"), + MAPPING_INIT(".fini_array.", ".fini_array"), + MAPPING_INIT(".sdata.", ".sdata"), + MAPPING_INIT(".sbss.", ".sbss"), + // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled + // differently depending on whether it is creating a shared library. + MAPPING_INIT(".sdata2.", ".sdata"), + MAPPING_INIT(".sbss2.", ".sbss"), + MAPPING_INIT(".lrodata.", ".lrodata"), + MAPPING_INIT(".ldata.", ".ldata"), + MAPPING_INIT(".lbss.", ".lbss"), + MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"), + MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"), + MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"), + MAPPING_INIT(".gnu.linkonce.t.", ".text"), + MAPPING_INIT(".gnu.linkonce.r.", ".rodata"), + MAPPING_INIT(".gnu.linkonce.d.", ".data"), + MAPPING_INIT(".gnu.linkonce.b.", ".bss"), + MAPPING_INIT(".gnu.linkonce.s.", ".sdata"), + MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"), + MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"), + MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"), + MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"), + MAPPING_INIT(".gnu.linkonce.td.", ".tdata"), + MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"), + MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"), + MAPPING_INIT(".gnu.linkonce.l.", ".ldata"), + MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"), + MAPPING_INIT(".ARM.extab.", ".ARM.extab"), + MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"), + MAPPING_INIT(".ARM.exidx.", ".ARM.exidx"), + MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"), +}; +#undef MAPPING_INIT + +const int Layout::section_name_mapping_count = + (sizeof(Layout::section_name_mapping) + / sizeof(Layout::section_name_mapping[0])); + +// 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) +{ + // 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 are used with -z relro. The sections + // are recognized by name. We use the same names that the GNU + // linker does for these sections. + + // It is hard to handle this in a principled way, so we don't even + // try. We use a table of mappings. If the input section name is + // not found in the table, we simply use it as the output section + // name. + + const Section_name_mapping* psnm = section_name_mapping; + for (int i = 0; i < section_name_mapping_count; ++i, ++psnm) + { + if (strncmp(name, psnm->from, psnm->fromlen) == 0) + { + *plen = psnm->tolen; + return psnm->to; + } + } + + return name; +} + +// Check if a comdat group or .gnu.linkonce section with the given +// NAME is selected for the link. If there is already a section, +// *KEPT_SECTION is set to point to the existing section and the +// function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and +// IS_GROUP_NAME are recorded for this NAME in the layout object, +// *KEPT_SECTION is set to the internal copy and the function returns +// true. + +bool +Layout::find_or_add_kept_section(const std::string& name, + Relobj* object, + unsigned int shndx, + bool is_comdat, + bool is_group_name, + Kept_section** kept_section) +{ + // It's normal to see a couple of entries here, for the x86 thunk + // sections. If we see more than a few, we're linking a C++ + // program, and we resize to get more space to minimize rehashing. + if (this->signatures_.size() > 4 + && !this->resized_signatures_) + { + reserve_unordered_map(&this->signatures_, + this->number_of_input_files_ * 64); + this->resized_signatures_ = true; + } + + Kept_section candidate; + std::pair ins = + this->signatures_.insert(std::make_pair(name, candidate)); + + if (kept_section != NULL) + *kept_section = &ins.first->second; + if (ins.second) + { + // This is the first time we've seen this signature. + ins.first->second.set_object(object); + ins.first->second.set_shndx(shndx); + if (is_comdat) + ins.first->second.set_is_comdat(); + if (is_group_name) + ins.first->second.set_is_group_name(); + return true; + } + + // We have already seen this signature. + + if (ins.first->second.is_group_name()) + { + // We've already seen a real section group with this signature. + // If the kept group is from a plugin object, and we're in the + // replacement phase, accept the new one as a replacement. + if (ins.first->second.object() == NULL + && parameters->options().plugins()->in_replacement_phase()) + { + ins.first->second.set_object(object); + ins.first->second.set_shndx(shndx); + return true; + } + return false; + } + else if (is_group_name) + { + // 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.set_is_group_name(); + 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; + } +} + +// Store the allocated sections into the section list. + +void +Layout::get_allocated_sections(Section_list* section_list) const +{ + for (Section_list::const_iterator p = this->section_list_.begin(); + p != this->section_list_.end(); + ++p) + if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0) + section_list->push_back(*p); +} + +// Create an output segment. + +Output_segment* +Layout::make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags) +{ + gold_assert(!parameters->options().relocatable()); + Output_segment* oseg = new Output_segment(type, flags); + this->segment_list_.push_back(oseg); + + if (type == elfcpp::PT_TLS) + this->tls_segment_ = oseg; + else if (type == elfcpp::PT_GNU_RELRO) + this->relro_segment_ = oseg; + + return oseg; +} + +// 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. + +void +Layout::write_output_sections(Output_file* of) const +{ + for (Section_list::const_iterator p = this->section_list_.begin(); + p != this->section_list_.end(); + ++p) + { + if (!(*p)->after_input_sections()) + (*p)->write(of); + } +} + +// 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->options().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, this->symtab_xindex_, 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, this->dynsym_xindex_, of, off); + } + } + + // 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 out the Output_sections which can only be written after the +// input sections are complete. + +void +Layout::write_sections_after_input_sections(Output_file* of) +{ + // Determine the final section offsets, and thus the final output + // file size. Note we finalize the .shstrab last, to allow the + // after_input_section sections to modify their section-names before + // writing. + if (this->any_postprocessing_sections_) + { + off_t off = this->output_file_size_; + off = this->set_section_offsets(off, POSTPROCESSING_SECTIONS_PASS); + + // Now that we've finalized the names, we can finalize the shstrab. + off = + this->set_section_offsets(off, + STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS); + + if (off > this->output_file_size_) + { + of->resize(off); + this->output_file_size_ = off; + } + } + + for (Section_list::const_iterator p = this->section_list_.begin(); + p != this->section_list_.end(); + ++p) + { + if ((*p)->after_input_sections()) + (*p)->write(of); + } + + this->section_headers_->write(of); +} + +// If the build ID requires computing a checksum, do so here, and +// write it out. We compute a checksum over the entire file because +// that is simplest. + +void +Layout::write_build_id(Output_file* of) const +{ + if (this->build_id_note_ == NULL) + return; + + const unsigned char* iv = of->get_input_view(0, this->output_file_size_); + + unsigned char* ov = of->get_output_view(this->build_id_note_->offset(), + this->build_id_note_->data_size()); + + const char* style = parameters->options().build_id(); + if (strcmp(style, "sha1") == 0) + { + sha1_ctx ctx; + sha1_init_ctx(&ctx); + sha1_process_bytes(iv, this->output_file_size_, &ctx); + sha1_finish_ctx(&ctx, ov); + } + else if (strcmp(style, "md5") == 0) + { + md5_ctx ctx; + md5_init_ctx(&ctx); + md5_process_bytes(iv, this->output_file_size_, &ctx); + md5_finish_ctx(&ctx, ov); + } + else + gold_unreachable(); + + of->write_output_view(this->build_id_note_->offset(), + this->build_id_note_->data_size(), + ov); + + of->free_input_view(0, this->output_file_size_, iv); +} + +// Write out a binary file. This is called after the link is +// complete. IN is the temporary output file we used to generate the +// ELF code. We simply walk through the segments, read them from +// their file offset in IN, and write them to their load address in +// the output file. FIXME: with a bit more work, we could support +// S-records and/or Intel hex format here. + +void +Layout::write_binary(Output_file* in) const +{ + gold_assert(parameters->options().oformat_enum() + == General_options::OBJECT_FORMAT_BINARY); + + // Get the size of the binary file. + uint64_t max_load_address = 0; + for (Segment_list::const_iterator p = this->segment_list_.begin(); + p != this->segment_list_.end(); + ++p) + { + if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0) + { + uint64_t max_paddr = (*p)->paddr() + (*p)->filesz(); + if (max_paddr > max_load_address) + max_load_address = max_paddr; + } + } + + Output_file out(parameters->options().output_file_name()); + out.open(max_load_address); + + for (Segment_list::const_iterator p = this->segment_list_.begin(); + p != this->segment_list_.end(); + ++p) + { + if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0) + { + const unsigned char* vin = in->get_input_view((*p)->offset(), + (*p)->filesz()); + unsigned char* vout = out.get_output_view((*p)->paddr(), + (*p)->filesz()); + memcpy(vout, vin, (*p)->filesz()); + out.write_output_view((*p)->paddr(), (*p)->filesz(), vout); + in->free_input_view((*p)->offset(), (*p)->filesz(), vin); + } + } + + out.close(); +} + +// Print the output sections to the map file. + +void +Layout::print_to_mapfile(Mapfile* mapfile) const +{ + for (Segment_list::const_iterator p = this->segment_list_.begin(); + p != this->segment_list_.end(); + ++p) + (*p)->print_sections_to_mapfile(mapfile); +} + +// Print statistical information to stderr. This is used for --stats. + +void +Layout::print_stats() const +{ + this->namepool_.print_stats("section name pool"); + this->sympool_.print_stats("output symbol name pool"); + this->dynpool_.print_stats("dynamic name pool"); + + for (Section_list::const_iterator p = this->section_list_.begin(); + p != this->section_list_.end(); + ++p) + (*p)->print_merge_stats(); +} + +// Write_sections_task methods. + +// We can always run this task. + +Task_token* +Write_sections_task::is_runnable() +{ + return NULL; +} + +// We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER +// when finished. + +void +Write_sections_task::locks(Task_locker* tl) +{ + tl->add(this, this->output_sections_blocker_); + tl->add(this, this->final_blocker_); +} + +// Run the task--write out the data. + +void +Write_sections_task::run(Workqueue*) +{ + this->layout_->write_output_sections(this->of_); +} + +// Write_data_task methods. + +// We can always run this task. + +Task_token* +Write_data_task::is_runnable() +{ + return NULL; +} + +// We need to unlock FINAL_BLOCKER when finished. + +void +Write_data_task::locks(Task_locker* tl) +{ + tl->add(this, this->final_blocker_); +} + +// 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_token* +Write_symbols_task::is_runnable() +{ + return NULL; +} + +// We need to unlock FINAL_BLOCKER when finished. + +void +Write_symbols_task::locks(Task_locker* tl) +{ + tl->add(this, this->final_blocker_); +} + +// Run the task--write out the symbols. + +void +Write_symbols_task::run(Workqueue*) +{ + this->symtab_->write_globals(this->sympool_, this->dynpool_, + this->layout_->symtab_xindex(), + this->layout_->dynsym_xindex(), this->of_); +} + +// Write_after_input_sections_task methods. + +// We can only run this task after the input sections have completed. + +Task_token* +Write_after_input_sections_task::is_runnable() +{ + if (this->input_sections_blocker_->is_blocked()) + return this->input_sections_blocker_; + return NULL; +} + +// We need to unlock FINAL_BLOCKER when finished. + +void +Write_after_input_sections_task::locks(Task_locker* tl) +{ + tl->add(this, this->final_blocker_); +} + +// Run the task. + +void +Write_after_input_sections_task::run(Workqueue*) +{ + this->layout_->write_sections_after_input_sections(this->of_); +} + +// Close_task_runner methods. + +// Run the task--close the file. + +void +Close_task_runner::run(Workqueue*, const Task*) +{ + // If we need to compute a checksum for the BUILD if, we do so here. + this->layout_->write_build_id(this->of_); + + // If we've been asked to create a binary file, we do so here. + if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF) + this->layout_->write_binary(this->of_); + + 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>(Sized_relobj<32, false>* object, unsigned int shndx, + const char* name, + const elfcpp::Shdr<32, false>& shdr, + unsigned int, unsigned int, off_t*); +#endif + +#ifdef HAVE_TARGET_32_BIG +template +Output_section* +Layout::layout<32, true>(Sized_relobj<32, true>* object, unsigned int shndx, + const char* name, + const elfcpp::Shdr<32, true>& shdr, + unsigned int, unsigned int, off_t*); +#endif + +#ifdef HAVE_TARGET_64_LITTLE +template +Output_section* +Layout::layout<64, false>(Sized_relobj<64, false>* object, unsigned int shndx, + const char* name, + const elfcpp::Shdr<64, false>& shdr, + unsigned int, unsigned int, off_t*); +#endif + +#ifdef HAVE_TARGET_64_BIG +template +Output_section* +Layout::layout<64, true>(Sized_relobj<64, true>* object, unsigned int shndx, + const char* name, + const elfcpp::Shdr<64, true>& shdr, + unsigned int, unsigned int, off_t*); +#endif + +#ifdef HAVE_TARGET_32_LITTLE +template +Output_section* +Layout::layout_reloc<32, false>(Sized_relobj<32, false>* object, + unsigned int reloc_shndx, + const elfcpp::Shdr<32, false>& shdr, + Output_section* data_section, + Relocatable_relocs* rr); +#endif + +#ifdef HAVE_TARGET_32_BIG +template +Output_section* +Layout::layout_reloc<32, true>(Sized_relobj<32, true>* object, + unsigned int reloc_shndx, + const elfcpp::Shdr<32, true>& shdr, + Output_section* data_section, + Relocatable_relocs* rr); +#endif + +#ifdef HAVE_TARGET_64_LITTLE +template +Output_section* +Layout::layout_reloc<64, false>(Sized_relobj<64, false>* object, + unsigned int reloc_shndx, + const elfcpp::Shdr<64, false>& shdr, + Output_section* data_section, + Relocatable_relocs* rr); +#endif + +#ifdef HAVE_TARGET_64_BIG +template +Output_section* +Layout::layout_reloc<64, true>(Sized_relobj<64, true>* object, + unsigned int reloc_shndx, + const elfcpp::Shdr<64, true>& shdr, + Output_section* data_section, + Relocatable_relocs* rr); +#endif + +#ifdef HAVE_TARGET_32_LITTLE +template +void +Layout::layout_group<32, false>(Symbol_table* symtab, + Sized_relobj<32, false>* object, + unsigned int, + const char* group_section_name, + const char* signature, + const elfcpp::Shdr<32, false>& shdr, + elfcpp::Elf_Word flags, + std::vector* shndxes); +#endif + +#ifdef HAVE_TARGET_32_BIG +template +void +Layout::layout_group<32, true>(Symbol_table* symtab, + Sized_relobj<32, true>* object, + unsigned int, + const char* group_section_name, + const char* signature, + const elfcpp::Shdr<32, true>& shdr, + elfcpp::Elf_Word flags, + std::vector* shndxes); +#endif + +#ifdef HAVE_TARGET_64_LITTLE +template +void +Layout::layout_group<64, false>(Symbol_table* symtab, + Sized_relobj<64, false>* object, + unsigned int, + const char* group_section_name, + const char* signature, + const elfcpp::Shdr<64, false>& shdr, + elfcpp::Elf_Word flags, + std::vector* shndxes); +#endif + +#ifdef HAVE_TARGET_64_BIG +template +void +Layout::layout_group<64, true>(Symbol_table* symtab, + Sized_relobj<64, true>* object, + unsigned int, + const char* group_section_name, + const char* signature, + const elfcpp::Shdr<64, true>& shdr, + elfcpp::Elf_Word flags, + std::vector* shndxes); +#endif + +#ifdef HAVE_TARGET_32_LITTLE +template +Output_section* +Layout::layout_eh_frame<32, false>(Sized_relobj<32, false>* object, + const unsigned char* symbols, + off_t symbols_size, + const unsigned char* symbol_names, + off_t symbol_names_size, + unsigned int shndx, + const elfcpp::Shdr<32, false>& shdr, + unsigned int reloc_shndx, + unsigned int reloc_type, + off_t* off); +#endif + +#ifdef HAVE_TARGET_32_BIG +template +Output_section* +Layout::layout_eh_frame<32, true>(Sized_relobj<32, true>* object, + const unsigned char* symbols, + off_t symbols_size, + const unsigned char* symbol_names, + off_t symbol_names_size, + unsigned int shndx, + const elfcpp::Shdr<32, true>& shdr, + unsigned int reloc_shndx, + unsigned int reloc_type, + off_t* off); +#endif + +#ifdef HAVE_TARGET_64_LITTLE +template +Output_section* +Layout::layout_eh_frame<64, false>(Sized_relobj<64, false>* object, + const unsigned char* symbols, + off_t symbols_size, + const unsigned char* symbol_names, + off_t symbol_names_size, + unsigned int shndx, + const elfcpp::Shdr<64, false>& shdr, + unsigned int reloc_shndx, + unsigned int reloc_type, + off_t* off); +#endif + +#ifdef HAVE_TARGET_64_BIG +template +Output_section* +Layout::layout_eh_frame<64, true>(Sized_relobj<64, true>* object, + const unsigned char* symbols, + off_t symbols_size, + const unsigned char* symbol_names, + off_t symbol_names_size, + unsigned int shndx, + const elfcpp::Shdr<64, true>& shdr, + unsigned int reloc_shndx, + unsigned int reloc_type, + off_t* off); +#endif + +} // End namespace gold.