mirror of
https://sourceware.org/git/binutils-gdb.git
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f0641a0b38
output regardless of randomize_va_space.
983 lines
28 KiB
C++
983 lines
28 KiB
C++
// layout.cc -- lay out output file sections for gold
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#include "gold.h"
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#include <cassert>
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#include <cstring>
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#include <algorithm>
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#include <iostream>
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#include <utility>
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#include "output.h"
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#include "symtab.h"
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#include "layout.h"
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namespace gold
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{
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// Layout_task_runner methods.
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// Lay out the sections. This is called after all the input objects
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// have been read.
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void
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Layout_task_runner::run(Workqueue* workqueue)
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{
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off_t file_size = this->layout_->finalize(this->input_objects_,
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this->symtab_);
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// Now we know the final size of the output file and we know where
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// each piece of information goes.
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Output_file* of = new Output_file(this->options_);
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of->open(file_size);
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// Queue up the final set of tasks.
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gold::queue_final_tasks(this->options_, this->input_objects_,
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this->symtab_, this->layout_, workqueue, of);
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}
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// Layout methods.
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Layout::Layout(const General_options& options)
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: options_(options), namepool_(), sympool_(), signatures_(),
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section_name_map_(), segment_list_(), section_list_(),
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special_output_list_(), tls_segment_(NULL)
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{
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// Make space for more than enough segments for a typical file.
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// This is just for efficiency--it's OK if we wind up needing more.
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segment_list_.reserve(12);
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}
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// Hash a key we use to look up an output section mapping.
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size_t
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Layout::Hash_key::operator()(const Layout::Key& k) const
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{
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return k.first + k.second.first + k.second.second;
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}
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// Whether to include this section in the link.
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template<int size, bool big_endian>
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bool
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Layout::include_section(Object*, const char*,
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const elfcpp::Shdr<size, big_endian>& shdr)
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{
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// Some section types are never linked. Some are only linked when
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// doing a relocateable link.
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switch (shdr.get_sh_type())
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{
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case elfcpp::SHT_NULL:
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case elfcpp::SHT_SYMTAB:
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case elfcpp::SHT_DYNSYM:
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case elfcpp::SHT_STRTAB:
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case elfcpp::SHT_HASH:
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case elfcpp::SHT_DYNAMIC:
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case elfcpp::SHT_SYMTAB_SHNDX:
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return false;
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case elfcpp::SHT_RELA:
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case elfcpp::SHT_REL:
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case elfcpp::SHT_GROUP:
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return this->options_.is_relocatable();
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default:
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// FIXME: Handle stripping debug sections here.
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return true;
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}
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}
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// Return an output section named NAME, or NULL if there is none.
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Output_section*
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Layout::find_output_section(const char* name) const
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{
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for (Section_name_map::const_iterator p = this->section_name_map_.begin();
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p != this->section_name_map_.end();
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++p)
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if (strcmp(p->second->name(), name) == 0)
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return p->second;
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return NULL;
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}
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// Return an output segment of type TYPE, with segment flags SET set
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// and segment flags CLEAR clear. Return NULL if there is none.
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Output_segment*
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Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
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elfcpp::Elf_Word clear) const
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{
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for (Segment_list::const_iterator p = this->segment_list_.begin();
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p != this->segment_list_.end();
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++p)
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if (static_cast<elfcpp::PT>((*p)->type()) == type
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&& ((*p)->flags() & set) == set
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&& ((*p)->flags() & clear) == 0)
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return *p;
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return NULL;
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}
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// Return the output section to use for section NAME with type TYPE
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// and section flags FLAGS.
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Output_section*
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Layout::get_output_section(const char* name, Stringpool::Key name_key,
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elfcpp::Elf_Word type, elfcpp::Elf_Xword flags)
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{
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// We should ignore some flags.
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flags &= ~ (elfcpp::SHF_INFO_LINK
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| elfcpp::SHF_LINK_ORDER
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| elfcpp::SHF_GROUP);
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const Key key(name_key, std::make_pair(type, flags));
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const std::pair<Key, Output_section*> v(key, NULL);
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std::pair<Section_name_map::iterator, bool> ins(
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this->section_name_map_.insert(v));
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if (!ins.second)
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return ins.first->second;
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else
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{
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// This is the first time we've seen this name/type/flags
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// combination.
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Output_section* os = this->make_output_section(name, type, flags);
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ins.first->second = os;
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return os;
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}
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}
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// Return the output section to use for input section SHNDX, with name
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// NAME, with header HEADER, from object OBJECT. Set *OFF to the
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// offset of this input section without the output section.
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template<int size, bool big_endian>
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Output_section*
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Layout::layout(Relobj* object, unsigned int shndx, const char* name,
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const elfcpp::Shdr<size, big_endian>& shdr, off_t* off)
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{
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if (!this->include_section(object, name, shdr))
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return NULL;
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// If we are not doing a relocateable link, choose the name to use
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// for the output section.
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size_t len = strlen(name);
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if (!this->options_.is_relocatable())
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name = Layout::output_section_name(name, &len);
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// FIXME: Handle SHF_OS_NONCONFORMING here.
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// Canonicalize the section name.
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Stringpool::Key name_key;
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name = this->namepool_.add(name, len, &name_key);
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// Find the output section. The output section is selected based on
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// the section name, type, and flags.
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Output_section* os = this->get_output_section(name, name_key,
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shdr.get_sh_type(),
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shdr.get_sh_flags());
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// FIXME: Handle SHF_LINK_ORDER somewhere.
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*off = os->add_input_section(object, shndx, name, shdr);
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return os;
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}
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// Add POSD to an output section using NAME, TYPE, and FLAGS.
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void
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Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type,
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elfcpp::Elf_Xword flags,
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Output_section_data* posd)
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{
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// Canonicalize the name.
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Stringpool::Key name_key;
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name = this->namepool_.add(name, &name_key);
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Output_section* os = this->get_output_section(name, name_key, type, flags);
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os->add_output_section_data(posd);
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}
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// Map section flags to segment flags.
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elfcpp::Elf_Word
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Layout::section_flags_to_segment(elfcpp::Elf_Xword flags)
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{
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elfcpp::Elf_Word ret = elfcpp::PF_R;
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if ((flags & elfcpp::SHF_WRITE) != 0)
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ret |= elfcpp::PF_W;
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if ((flags & elfcpp::SHF_EXECINSTR) != 0)
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ret |= elfcpp::PF_X;
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return ret;
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}
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// Make a new Output_section, and attach it to segments as
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// appropriate.
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Output_section*
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Layout::make_output_section(const char* name, elfcpp::Elf_Word type,
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elfcpp::Elf_Xword flags)
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{
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Output_section* os = new Output_section(name, type, flags, true);
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if ((flags & elfcpp::SHF_ALLOC) == 0)
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this->section_list_.push_back(os);
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else
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{
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// This output section goes into a PT_LOAD segment.
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elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
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// The only thing we really care about for PT_LOAD segments is
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// whether or not they are writable, so that is how we search
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// for them. People who need segments sorted on some other
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// basis will have to wait until we implement a mechanism for
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// them to describe the segments they want.
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Segment_list::const_iterator p;
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for (p = this->segment_list_.begin();
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p != this->segment_list_.end();
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++p)
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{
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if ((*p)->type() == elfcpp::PT_LOAD
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&& ((*p)->flags() & elfcpp::PF_W) == (seg_flags & elfcpp::PF_W))
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{
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(*p)->add_output_section(os, seg_flags);
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break;
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}
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}
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if (p == this->segment_list_.end())
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{
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Output_segment* oseg = new Output_segment(elfcpp::PT_LOAD,
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seg_flags);
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this->segment_list_.push_back(oseg);
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oseg->add_output_section(os, seg_flags);
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}
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// If we see a loadable SHT_NOTE section, we create a PT_NOTE
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// segment.
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if (type == elfcpp::SHT_NOTE)
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{
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// See if we already have an equivalent PT_NOTE segment.
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for (p = this->segment_list_.begin();
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p != segment_list_.end();
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++p)
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{
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if ((*p)->type() == elfcpp::PT_NOTE
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&& (((*p)->flags() & elfcpp::PF_W)
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== (seg_flags & elfcpp::PF_W)))
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{
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(*p)->add_output_section(os, seg_flags);
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break;
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}
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}
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if (p == this->segment_list_.end())
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{
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Output_segment* oseg = new Output_segment(elfcpp::PT_NOTE,
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seg_flags);
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this->segment_list_.push_back(oseg);
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oseg->add_output_section(os, seg_flags);
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}
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}
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// If we see a loadable SHF_TLS section, we create a PT_TLS
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// segment. There can only be one such segment.
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if ((flags & elfcpp::SHF_TLS) != 0)
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{
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if (this->tls_segment_ == NULL)
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{
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this->tls_segment_ = new Output_segment(elfcpp::PT_TLS,
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seg_flags);
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this->segment_list_.push_back(this->tls_segment_);
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}
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this->tls_segment_->add_output_section(os, seg_flags);
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}
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}
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return os;
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}
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// Find the first read-only PT_LOAD segment, creating one if
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// necessary.
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Output_segment*
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Layout::find_first_load_seg()
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{
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for (Segment_list::const_iterator p = this->segment_list_.begin();
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p != this->segment_list_.end();
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++p)
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{
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if ((*p)->type() == elfcpp::PT_LOAD
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&& ((*p)->flags() & elfcpp::PF_R) != 0
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&& ((*p)->flags() & elfcpp::PF_W) == 0)
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return *p;
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}
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Output_segment* load_seg = new Output_segment(elfcpp::PT_LOAD, elfcpp::PF_R);
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this->segment_list_.push_back(load_seg);
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return load_seg;
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}
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// Finalize the layout. When this is called, we have created all the
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// output sections and all the output segments which are based on
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// input sections. We have several things to do, and we have to do
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// them in the right order, so that we get the right results correctly
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// and efficiently.
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// 1) Finalize the list of output segments and create the segment
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// table header.
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// 2) Finalize the dynamic symbol table and associated sections.
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// 3) Determine the final file offset of all the output segments.
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// 4) Determine the final file offset of all the SHF_ALLOC output
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// sections.
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// 5) Create the symbol table sections and the section name table
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// section.
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// 6) Finalize the symbol table: set symbol values to their final
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// value and make a final determination of which symbols are going
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// into the output symbol table.
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// 7) Create the section table header.
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// 8) Determine the final file offset of all the output sections which
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// are not SHF_ALLOC, including the section table header.
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// 9) Finalize the ELF file header.
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// This function returns the size of the output file.
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off_t
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Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab)
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{
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if (input_objects->any_dynamic())
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{
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// If there are any dynamic objects in the link, then we need
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// some additional segments: PT_PHDRS, PT_INTERP, and
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// PT_DYNAMIC. We also need to finalize the dynamic symbol
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// table and create the dynamic hash table.
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abort();
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}
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// FIXME: Handle PT_GNU_STACK.
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Output_segment* load_seg = this->find_first_load_seg();
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// Lay out the segment headers.
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int size = input_objects->target()->get_size();
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bool big_endian = input_objects->target()->is_big_endian();
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Output_segment_headers* segment_headers;
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segment_headers = new Output_segment_headers(size, big_endian,
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this->segment_list_);
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load_seg->add_initial_output_data(segment_headers);
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this->special_output_list_.push_back(segment_headers);
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// FIXME: Attach them to PT_PHDRS if necessary.
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// Lay out the file header.
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Output_file_header* file_header;
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file_header = new Output_file_header(size,
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big_endian,
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this->options_,
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input_objects->target(),
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symtab,
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segment_headers);
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load_seg->add_initial_output_data(file_header);
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this->special_output_list_.push_back(file_header);
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// We set the output section indexes in set_segment_offsets and
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// set_section_offsets.
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unsigned int shndx = 1;
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// Set the file offsets of all the segments, and all the sections
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// they contain.
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off_t off = this->set_segment_offsets(input_objects->target(), load_seg,
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&shndx);
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// Create the symbol table sections.
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// FIXME: We don't need to do this if we are stripping symbols.
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Output_section* osymtab;
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Output_section* ostrtab;
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this->create_symtab_sections(size, input_objects, symtab, &off,
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&osymtab, &ostrtab);
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// Create the .shstrtab section.
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Output_section* shstrtab_section = this->create_shstrtab();
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// Set the file offsets of all the sections not associated with
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// segments.
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off = this->set_section_offsets(off, &shndx);
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// Now the section index of OSTRTAB is set.
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osymtab->set_link(ostrtab->out_shndx());
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// Create the section table header.
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Output_section_headers* oshdrs = this->create_shdrs(size, big_endian, &off);
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file_header->set_section_info(oshdrs, shstrtab_section);
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// Now we know exactly where everything goes in the output file.
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return off;
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}
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// Return whether SEG1 should be before SEG2 in the output file. This
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// is based entirely on the segment type and flags. When this is
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// called the segment addresses has normally not yet been set.
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bool
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Layout::segment_precedes(const Output_segment* seg1,
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const Output_segment* seg2)
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{
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elfcpp::Elf_Word type1 = seg1->type();
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elfcpp::Elf_Word type2 = seg2->type();
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// The single PT_PHDR segment is required to precede any loadable
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// segment. We simply make it always first.
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if (type1 == elfcpp::PT_PHDR)
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{
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assert(type2 != elfcpp::PT_PHDR);
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return true;
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}
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if (type2 == elfcpp::PT_PHDR)
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return false;
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// The single PT_INTERP segment is required to precede any loadable
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// segment. We simply make it always second.
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if (type1 == elfcpp::PT_INTERP)
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{
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assert(type2 != elfcpp::PT_INTERP);
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return true;
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}
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if (type2 == elfcpp::PT_INTERP)
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return false;
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// We then put PT_LOAD segments before any other segments.
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if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD)
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return true;
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if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD)
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return false;
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// We put the PT_TLS segment last, because that is where the dynamic
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// linker expects to find it (this is just for efficiency; other
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// positions would also work correctly).
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if (type1 == elfcpp::PT_TLS && type2 != elfcpp::PT_TLS)
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return false;
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if (type2 == elfcpp::PT_TLS && type1 != elfcpp::PT_TLS)
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return true;
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const elfcpp::Elf_Word flags1 = seg1->flags();
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const elfcpp::Elf_Word flags2 = seg2->flags();
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// The order of non-PT_LOAD segments is unimportant. We simply sort
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// by the numeric segment type and flags values. There should not
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// be more than one segment with the same type and flags.
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if (type1 != elfcpp::PT_LOAD)
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{
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if (type1 != type2)
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return type1 < type2;
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assert(flags1 != flags2);
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return flags1 < flags2;
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}
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// We sort PT_LOAD segments based on the flags. Readonly segments
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// come before writable segments. Then executable segments come
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// before non-executable segments. Then the unlikely case of a
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// non-readable segment comes before the normal case of a readable
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// segment. If there are multiple segments with the same type and
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// flags, we require that the address be set, and we sort by
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// virtual address and then physical address.
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if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W))
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return (flags1 & elfcpp::PF_W) == 0;
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if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X))
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return (flags1 & elfcpp::PF_X) != 0;
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if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R))
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return (flags1 & elfcpp::PF_R) == 0;
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uint64_t vaddr1 = seg1->vaddr();
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uint64_t vaddr2 = seg2->vaddr();
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if (vaddr1 != vaddr2)
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return vaddr1 < vaddr2;
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uint64_t paddr1 = seg1->paddr();
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uint64_t paddr2 = seg2->paddr();
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assert(paddr1 != paddr2);
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return paddr1 < paddr2;
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}
|
|
|
|
// 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 = target->text_segment_address();
|
|
off_t off = 0;
|
|
bool was_readonly = false;
|
|
for (Segment_list::iterator p = this->segment_list_.begin();
|
|
p != this->segment_list_.end();
|
|
++p)
|
|
{
|
|
if ((*p)->type() == elfcpp::PT_LOAD)
|
|
{
|
|
if (load_seg != NULL && load_seg != *p)
|
|
abort();
|
|
load_seg = NULL;
|
|
|
|
// If the last segment was readonly, and this one is not,
|
|
// then skip the address forward one page, maintaining the
|
|
// same position within the page. This lets us store both
|
|
// segments overlapping on a single page in the file, but
|
|
// the loader will put them on different pages in memory.
|
|
|
|
uint64_t orig_addr = addr;
|
|
uint64_t orig_off = off;
|
|
|
|
uint64_t aligned_addr = addr;
|
|
uint64_t abi_pagesize = target->abi_pagesize();
|
|
if (was_readonly && ((*p)->flags() & elfcpp::PF_W) != 0)
|
|
{
|
|
uint64_t align = (*p)->addralign();
|
|
|
|
addr = align_address(addr, align);
|
|
aligned_addr = addr;
|
|
if ((addr & (abi_pagesize - 1)) != 0)
|
|
addr = addr + abi_pagesize;
|
|
}
|
|
|
|
unsigned int shndx_hold = *pshndx;
|
|
off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
|
|
uint64_t new_addr = (*p)->set_section_addresses(addr, &off, pshndx);
|
|
|
|
// Now that we know the size of this segment, we may be able
|
|
// to save a page in memory, at the cost of wasting some
|
|
// file space, by instead aligning to the start of a new
|
|
// page. Here we use the real machine page size rather than
|
|
// the ABI mandated page size.
|
|
|
|
if (aligned_addr != addr)
|
|
{
|
|
uint64_t common_pagesize = target->common_pagesize();
|
|
uint64_t first_off = (common_pagesize
|
|
- (aligned_addr
|
|
& (common_pagesize - 1)));
|
|
uint64_t last_off = new_addr & (common_pagesize - 1);
|
|
if (first_off > 0
|
|
&& last_off > 0
|
|
&& ((aligned_addr & ~ (common_pagesize - 1))
|
|
!= (new_addr & ~ (common_pagesize - 1)))
|
|
&& first_off + last_off <= common_pagesize)
|
|
{
|
|
*pshndx = shndx_hold;
|
|
addr = align_address(aligned_addr, common_pagesize);
|
|
off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
|
|
new_addr = (*p)->set_section_addresses(addr, &off, pshndx);
|
|
}
|
|
}
|
|
|
|
addr = new_addr;
|
|
|
|
if (((*p)->flags() & elfcpp::PF_W) == 0)
|
|
was_readonly = true;
|
|
}
|
|
}
|
|
|
|
// Handle the non-PT_LOAD segments, setting their offsets from their
|
|
// section's offsets.
|
|
for (Segment_list::iterator p = this->segment_list_.begin();
|
|
p != this->segment_list_.end();
|
|
++p)
|
|
{
|
|
if ((*p)->type() != elfcpp::PT_LOAD)
|
|
(*p)->set_offset();
|
|
}
|
|
|
|
return off;
|
|
}
|
|
|
|
// Set the file offset of all the sections not associated with a
|
|
// segment.
|
|
|
|
off_t
|
|
Layout::set_section_offsets(off_t off, unsigned int* pshndx)
|
|
{
|
|
for (Layout::Section_list::iterator p = this->section_list_.begin();
|
|
p != this->section_list_.end();
|
|
++p)
|
|
{
|
|
(*p)->set_out_shndx(*pshndx);
|
|
++*pshndx;
|
|
if ((*p)->offset() != -1)
|
|
continue;
|
|
off = align_address(off, (*p)->addralign());
|
|
(*p)->set_address(0, off);
|
|
off += (*p)->data_size();
|
|
}
|
|
return off;
|
|
}
|
|
|
|
// Create the symbol table sections.
|
|
|
|
void
|
|
Layout::create_symtab_sections(int size, const Input_objects* input_objects,
|
|
Symbol_table* symtab,
|
|
off_t* poff,
|
|
Output_section** posymtab,
|
|
Output_section** postrtab)
|
|
{
|
|
int symsize;
|
|
unsigned int align;
|
|
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
|
|
abort();
|
|
|
|
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;
|
|
|
|
for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
|
|
p != input_objects->relobj_end();
|
|
++p)
|
|
{
|
|
Task_lock_obj<Object> tlo(**p);
|
|
off = (*p)->finalize_local_symbols(off, &this->sympool_);
|
|
}
|
|
|
|
unsigned int local_symcount = (off - startoff) / symsize;
|
|
assert(local_symcount * symsize == off - startoff);
|
|
|
|
off = symtab->finalize(off, &this->sympool_);
|
|
|
|
this->sympool_.set_string_offsets();
|
|
|
|
const char* symtab_name = this->namepool_.add(".symtab", NULL);
|
|
Output_section* osymtab = new Output_section_symtab(symtab_name,
|
|
off - startoff);
|
|
this->section_list_.push_back(osymtab);
|
|
|
|
const char* strtab_name = this->namepool_.add(".strtab", NULL);
|
|
Output_section *ostrtab = new Output_section_strtab(strtab_name,
|
|
&this->sympool_);
|
|
this->section_list_.push_back(ostrtab);
|
|
this->special_output_list_.push_back(ostrtab);
|
|
|
|
osymtab->set_address(0, startoff);
|
|
osymtab->set_info(local_symcount);
|
|
osymtab->set_entsize(symsize);
|
|
osymtab->set_addralign(align);
|
|
|
|
*poff = off;
|
|
*posymtab = osymtab;
|
|
*postrtab = ostrtab;
|
|
}
|
|
|
|
// 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", NULL);
|
|
|
|
this->namepool_.set_string_offsets();
|
|
|
|
Output_section* os = new Output_section_strtab(name, &this->namepool_);
|
|
|
|
this->section_list_.push_back(os);
|
|
this->special_output_list_.push_back(os);
|
|
|
|
return os;
|
|
}
|
|
|
|
// Create the section headers. SIZE is 32 or 64. OFF is the file
|
|
// offset.
|
|
|
|
Output_section_headers*
|
|
Layout::create_shdrs(int size, bool big_endian, off_t* poff)
|
|
{
|
|
Output_section_headers* oshdrs;
|
|
oshdrs = new Output_section_headers(size, big_endian, this->segment_list_,
|
|
this->section_list_,
|
|
&this->namepool_);
|
|
off_t off = align_address(*poff, oshdrs->addralign());
|
|
oshdrs->set_address(0, off);
|
|
off += oshdrs->data_size();
|
|
*poff = off;
|
|
this->special_output_list_.push_back(oshdrs);
|
|
return oshdrs;
|
|
}
|
|
|
|
// The mapping of .gnu.linkonce section names to real section names.
|
|
|
|
#define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 }
|
|
const Layout::Linkonce_mapping Layout::linkonce_mapping[] =
|
|
{
|
|
MAPPING_INIT("d.rel.ro", ".data.rel.ro"), // Must be before "d".
|
|
MAPPING_INIT("t", ".text"),
|
|
MAPPING_INIT("r", ".rodata"),
|
|
MAPPING_INIT("d", ".data"),
|
|
MAPPING_INIT("b", ".bss"),
|
|
MAPPING_INIT("s", ".sdata"),
|
|
MAPPING_INIT("sb", ".sbss"),
|
|
MAPPING_INIT("s2", ".sdata2"),
|
|
MAPPING_INIT("sb2", ".sbss2"),
|
|
MAPPING_INIT("wi", ".debug_info"),
|
|
MAPPING_INIT("td", ".tdata"),
|
|
MAPPING_INIT("tb", ".tbss"),
|
|
MAPPING_INIT("lr", ".lrodata"),
|
|
MAPPING_INIT("l", ".ldata"),
|
|
MAPPING_INIT("lb", ".lbss"),
|
|
};
|
|
#undef MAPPING_INIT
|
|
|
|
const int Layout::linkonce_mapping_count =
|
|
sizeof(Layout::linkonce_mapping) / sizeof(Layout::linkonce_mapping[0]);
|
|
|
|
// Return the name of the output section to use for a .gnu.linkonce
|
|
// section. This is based on the default ELF linker script of the old
|
|
// GNU linker. For example, we map a name like ".gnu.linkonce.t.foo"
|
|
// to ".text". Set *PLEN to the length of the name. *PLEN is
|
|
// initialized to the length of NAME.
|
|
|
|
const char*
|
|
Layout::linkonce_output_name(const char* name, size_t *plen)
|
|
{
|
|
const char* s = name + sizeof(".gnu.linkonce") - 1;
|
|
if (*s != '.')
|
|
return name;
|
|
++s;
|
|
const Linkonce_mapping* plm = linkonce_mapping;
|
|
for (int i = 0; i < linkonce_mapping_count; ++i, ++plm)
|
|
{
|
|
if (strncmp(s, plm->from, plm->fromlen) == 0 && s[plm->fromlen] == '.')
|
|
{
|
|
*plen = plm->tolen;
|
|
return plm->to;
|
|
}
|
|
}
|
|
return name;
|
|
}
|
|
|
|
// Choose the output section name to use given an input section name.
|
|
// Set *PLEN to the length of the name. *PLEN is initialized to the
|
|
// length of NAME.
|
|
|
|
const char*
|
|
Layout::output_section_name(const char* name, size_t* plen)
|
|
{
|
|
if (Layout::is_linkonce(name))
|
|
{
|
|
// .gnu.linkonce sections are laid out as though they were named
|
|
// for the sections are placed into.
|
|
return Layout::linkonce_output_name(name, plen);
|
|
}
|
|
|
|
// If the section name has no '.', or only an initial '.', we use
|
|
// the name unchanged (i.e., ".text" is unchanged).
|
|
|
|
// Otherwise, if the section name does not include ".rel", we drop
|
|
// the last '.' and everything that follows (i.e., ".text.XXX"
|
|
// becomes ".text").
|
|
|
|
// Otherwise, if the section name has zero or one '.' after the
|
|
// ".rel", we use the name unchanged (i.e., ".rel.text" is
|
|
// unchanged).
|
|
|
|
// Otherwise, we drop the last '.' and everything that follows
|
|
// (i.e., ".rel.text.XXX" becomes ".rel.text").
|
|
|
|
const char* s = name;
|
|
if (*s == '.')
|
|
++s;
|
|
const char* sdot = strchr(s, '.');
|
|
if (sdot == NULL)
|
|
return name;
|
|
|
|
const char* srel = strstr(s, ".rel");
|
|
if (srel == NULL)
|
|
{
|
|
*plen = sdot - name;
|
|
return name;
|
|
}
|
|
|
|
sdot = strchr(srel + 1, '.');
|
|
if (sdot == NULL)
|
|
return name;
|
|
sdot = strchr(sdot + 1, '.');
|
|
if (sdot == NULL)
|
|
return name;
|
|
|
|
*plen = sdot - name;
|
|
return name;
|
|
}
|
|
|
|
// Record the signature of a comdat section, and return whether to
|
|
// include it in the link. If GROUP is true, this is a regular
|
|
// section group. If GROUP is false, this is a group signature
|
|
// derived from the name of a linkonce section. We want linkonce
|
|
// signatures and group signatures to block each other, but we don't
|
|
// want a linkonce signature to block another linkonce signature.
|
|
|
|
bool
|
|
Layout::add_comdat(const char* signature, bool group)
|
|
{
|
|
std::string sig(signature);
|
|
std::pair<Signatures::iterator, bool> ins(
|
|
this->signatures_.insert(std::make_pair(sig, group)));
|
|
|
|
if (ins.second)
|
|
{
|
|
// This is the first time we've seen this signature.
|
|
return true;
|
|
}
|
|
|
|
if (ins.first->second)
|
|
{
|
|
// We've already seen a real section group with this signature.
|
|
return false;
|
|
}
|
|
else if (group)
|
|
{
|
|
// This is a real section group, and we've already seen a
|
|
// linkonce section with tihs signature. Record that we've seen
|
|
// a section group, and don't include this section group.
|
|
ins.first->second = true;
|
|
return false;
|
|
}
|
|
else
|
|
{
|
|
// We've already seen a linkonce section and this is a linkonce
|
|
// section. These don't block each other--this may be the same
|
|
// symbol name with different section types.
|
|
return true;
|
|
}
|
|
}
|
|
|
|
// Write out data not associated with a section or the symbol table.
|
|
|
|
void
|
|
Layout::write_data(Output_file* of) const
|
|
{
|
|
for (Data_list::const_iterator p = this->special_output_list_.begin();
|
|
p != this->special_output_list_.end();
|
|
++p)
|
|
(*p)->write(of);
|
|
}
|
|
|
|
// Write_data_task methods.
|
|
|
|
// We can always run this task.
|
|
|
|
Task::Is_runnable_type
|
|
Write_data_task::is_runnable(Workqueue*)
|
|
{
|
|
return IS_RUNNABLE;
|
|
}
|
|
|
|
// We need to unlock FINAL_BLOCKER when finished.
|
|
|
|
Task_locker*
|
|
Write_data_task::locks(Workqueue* workqueue)
|
|
{
|
|
return new Task_locker_block(*this->final_blocker_, workqueue);
|
|
}
|
|
|
|
// Run the task--write out the data.
|
|
|
|
void
|
|
Write_data_task::run(Workqueue*)
|
|
{
|
|
this->layout_->write_data(this->of_);
|
|
}
|
|
|
|
// Write_symbols_task methods.
|
|
|
|
// We can always run this task.
|
|
|
|
Task::Is_runnable_type
|
|
Write_symbols_task::is_runnable(Workqueue*)
|
|
{
|
|
return IS_RUNNABLE;
|
|
}
|
|
|
|
// We need to unlock FINAL_BLOCKER when finished.
|
|
|
|
Task_locker*
|
|
Write_symbols_task::locks(Workqueue* workqueue)
|
|
{
|
|
return new Task_locker_block(*this->final_blocker_, workqueue);
|
|
}
|
|
|
|
// Run the task--write out the symbols.
|
|
|
|
void
|
|
Write_symbols_task::run(Workqueue*)
|
|
{
|
|
this->symtab_->write_globals(this->target_, this->sympool_, this->of_);
|
|
}
|
|
|
|
// Close_task_runner methods.
|
|
|
|
// Run the task--close the file.
|
|
|
|
void
|
|
Close_task_runner::run(Workqueue*)
|
|
{
|
|
this->of_->close();
|
|
}
|
|
|
|
// Instantiate the templates we need. We could use the configure
|
|
// script to restrict this to only the ones for implemented targets.
|
|
|
|
template
|
|
Output_section*
|
|
Layout::layout<32, false>(Relobj* object, unsigned int shndx, const char* name,
|
|
const elfcpp::Shdr<32, false>& shdr, off_t*);
|
|
|
|
template
|
|
Output_section*
|
|
Layout::layout<32, true>(Relobj* object, unsigned int shndx, const char* name,
|
|
const elfcpp::Shdr<32, true>& shdr, off_t*);
|
|
|
|
template
|
|
Output_section*
|
|
Layout::layout<64, false>(Relobj* object, unsigned int shndx, const char* name,
|
|
const elfcpp::Shdr<64, false>& shdr, off_t*);
|
|
|
|
template
|
|
Output_section*
|
|
Layout::layout<64, true>(Relobj* object, unsigned int shndx, const char* name,
|
|
const elfcpp::Shdr<64, true>& shdr, off_t*);
|
|
|
|
|
|
} // End namespace gold.
|