// dwarf_reader.cc -- parse dwarf2/3 debug information // Copyright (C) 2007-2019 Free Software Foundation, Inc. // Written by Ian Lance Taylor <iant@google.com>. // This file is part of gold. // This program is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 3 of the License, or // (at your option) any later version. // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // You should have received a copy of the GNU General Public License // along with this program; if not, write to the Free Software // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, // MA 02110-1301, USA. #include "gold.h" #include <algorithm> #include <utility> #include <vector> #include "elfcpp_swap.h" #include "dwarf.h" #include "object.h" #include "reloc.h" #include "dwarf_reader.h" #include "int_encoding.h" #include "compressed_output.h" namespace gold { // Class Sized_elf_reloc_mapper // Initialize the relocation tracker for section RELOC_SHNDX. template<int size, bool big_endian> bool Sized_elf_reloc_mapper<size, big_endian>::do_initialize( unsigned int reloc_shndx, unsigned int reloc_type) { this->reloc_type_ = reloc_type; return this->track_relocs_.initialize(this->object_, reloc_shndx, reloc_type); } // Looks in the symtab to see what section a symbol is in. template<int size, bool big_endian> unsigned int Sized_elf_reloc_mapper<size, big_endian>::symbol_section( unsigned int symndx, Address* value, bool* is_ordinary) { const int symsize = elfcpp::Elf_sizes<size>::sym_size; gold_assert(static_cast<off_t>((symndx + 1) * symsize) <= this->symtab_size_); elfcpp::Sym<size, big_endian> elfsym(this->symtab_ + symndx * symsize); *value = elfsym.get_st_value(); return this->object_->adjust_sym_shndx(symndx, elfsym.get_st_shndx(), is_ordinary); } // Return the section index and offset within the section of // the target of the relocation for RELOC_OFFSET. template<int size, bool big_endian> unsigned int Sized_elf_reloc_mapper<size, big_endian>::do_get_reloc_target( off_t reloc_offset, off_t* target_offset) { this->track_relocs_.advance(reloc_offset); if (reloc_offset != this->track_relocs_.next_offset()) return 0; unsigned int symndx = this->track_relocs_.next_symndx(); typename elfcpp::Elf_types<size>::Elf_Addr value; bool is_ordinary; unsigned int target_shndx = this->symbol_section(symndx, &value, &is_ordinary); if (!is_ordinary) return 0; if (this->reloc_type_ == elfcpp::SHT_RELA) value += this->track_relocs_.next_addend(); *target_offset = value; return target_shndx; } static inline Elf_reloc_mapper* make_elf_reloc_mapper(Relobj* object, const unsigned char* symtab, off_t symtab_size) { if (object->elfsize() == 32) { if (object->is_big_endian()) { #ifdef HAVE_TARGET_32_BIG return new Sized_elf_reloc_mapper<32, true>(object, symtab, symtab_size); #else gold_unreachable(); #endif } else { #ifdef HAVE_TARGET_32_LITTLE return new Sized_elf_reloc_mapper<32, false>(object, symtab, symtab_size); #else gold_unreachable(); #endif } } else if (object->elfsize() == 64) { if (object->is_big_endian()) { #ifdef HAVE_TARGET_64_BIG return new Sized_elf_reloc_mapper<64, true>(object, symtab, symtab_size); #else gold_unreachable(); #endif } else { #ifdef HAVE_TARGET_64_LITTLE return new Sized_elf_reloc_mapper<64, false>(object, symtab, symtab_size); #else gold_unreachable(); #endif } } else gold_unreachable(); } // class Dwarf_abbrev_table void Dwarf_abbrev_table::clear_abbrev_codes() { for (unsigned int code = 0; code < this->low_abbrev_code_max_; ++code) { if (this->low_abbrev_codes_[code] != NULL) { delete this->low_abbrev_codes_[code]; this->low_abbrev_codes_[code] = NULL; } } for (Abbrev_code_table::iterator it = this->high_abbrev_codes_.begin(); it != this->high_abbrev_codes_.end(); ++it) { if (it->second != NULL) delete it->second; } this->high_abbrev_codes_.clear(); } // Read the abbrev table from an object file. bool Dwarf_abbrev_table::do_read_abbrevs( Relobj* object, unsigned int abbrev_shndx, off_t abbrev_offset) { this->clear_abbrev_codes(); // If we don't have relocations, abbrev_shndx will be 0, and // we'll have to hunt for the .debug_abbrev section. if (abbrev_shndx == 0 && this->abbrev_shndx_ > 0) abbrev_shndx = this->abbrev_shndx_; else if (abbrev_shndx == 0) { for (unsigned int i = 1; i < object->shnum(); ++i) { std::string name = object->section_name(i); if (name == ".debug_abbrev" || name == ".zdebug_abbrev") { abbrev_shndx = i; // Correct the offset. For incremental update links, we have a // relocated offset that is relative to the output section, but // here we need an offset relative to the input section. abbrev_offset -= object->output_section_offset(i); break; } } if (abbrev_shndx == 0) return false; } // Get the section contents and decompress if necessary. if (abbrev_shndx != this->abbrev_shndx_) { if (this->owns_buffer_ && this->buffer_ != NULL) { delete[] this->buffer_; this->owns_buffer_ = false; } section_size_type buffer_size; this->buffer_ = object->decompressed_section_contents(abbrev_shndx, &buffer_size, &this->owns_buffer_); this->buffer_end_ = this->buffer_ + buffer_size; this->abbrev_shndx_ = abbrev_shndx; } this->buffer_pos_ = this->buffer_ + abbrev_offset; return true; } // Lookup the abbrev code entry for CODE. This function is called // only when the abbrev code is not in the direct lookup table. // It may be in the hash table, it may not have been read yet, // or it may not exist in the abbrev table. const Dwarf_abbrev_table::Abbrev_code* Dwarf_abbrev_table::do_get_abbrev(unsigned int code) { // See if the abbrev code is already in the hash table. Abbrev_code_table::const_iterator it = this->high_abbrev_codes_.find(code); if (it != this->high_abbrev_codes_.end()) return it->second; // Read and store abbrev code definitions until we find the // one we're looking for. for (;;) { // Read the abbrev code. A zero here indicates the end of the // abbrev table. size_t len; if (this->buffer_pos_ >= this->buffer_end_) return NULL; uint64_t nextcode = read_unsigned_LEB_128(this->buffer_pos_, &len); if (nextcode == 0) { this->buffer_pos_ = this->buffer_end_; return NULL; } this->buffer_pos_ += len; // Read the tag. if (this->buffer_pos_ >= this->buffer_end_) return NULL; uint64_t tag = read_unsigned_LEB_128(this->buffer_pos_, &len); this->buffer_pos_ += len; // Read the has_children flag. if (this->buffer_pos_ >= this->buffer_end_) return NULL; bool has_children = *this->buffer_pos_ == elfcpp::DW_CHILDREN_yes; this->buffer_pos_ += 1; // Read the list of (attribute, form) pairs. Abbrev_code* entry = new Abbrev_code(tag, has_children); for (;;) { // Read the attribute. if (this->buffer_pos_ >= this->buffer_end_) return NULL; uint64_t attr = read_unsigned_LEB_128(this->buffer_pos_, &len); this->buffer_pos_ += len; // Read the form. if (this->buffer_pos_ >= this->buffer_end_) return NULL; uint64_t form = read_unsigned_LEB_128(this->buffer_pos_, &len); this->buffer_pos_ += len; // A (0,0) pair terminates the list. if (attr == 0 && form == 0) break; if (attr == elfcpp::DW_AT_sibling) entry->has_sibling_attribute = true; entry->add_attribute(attr, form); } this->store_abbrev(nextcode, entry); if (nextcode == code) return entry; } return NULL; } // class Dwarf_ranges_table // Read the ranges table from an object file. bool Dwarf_ranges_table::read_ranges_table( Relobj* object, const unsigned char* symtab, off_t symtab_size, unsigned int ranges_shndx) { // If we've already read this abbrev table, return immediately. if (this->ranges_shndx_ > 0 && this->ranges_shndx_ == ranges_shndx) return true; // If we don't have relocations, ranges_shndx will be 0, and // we'll have to hunt for the .debug_ranges section. if (ranges_shndx == 0 && this->ranges_shndx_ > 0) ranges_shndx = this->ranges_shndx_; else if (ranges_shndx == 0) { for (unsigned int i = 1; i < object->shnum(); ++i) { std::string name = object->section_name(i); if (name == ".debug_ranges" || name == ".zdebug_ranges") { ranges_shndx = i; this->output_section_offset_ = object->output_section_offset(i); break; } } if (ranges_shndx == 0) return false; } // Get the section contents and decompress if necessary. if (ranges_shndx != this->ranges_shndx_) { if (this->owns_ranges_buffer_ && this->ranges_buffer_ != NULL) { delete[] this->ranges_buffer_; this->owns_ranges_buffer_ = false; } section_size_type buffer_size; this->ranges_buffer_ = object->decompressed_section_contents(ranges_shndx, &buffer_size, &this->owns_ranges_buffer_); this->ranges_buffer_end_ = this->ranges_buffer_ + buffer_size; this->ranges_shndx_ = ranges_shndx; } if (this->ranges_reloc_mapper_ != NULL) { delete this->ranges_reloc_mapper_; this->ranges_reloc_mapper_ = NULL; } // For incremental objects, we have no relocations. if (object->is_incremental()) return true; // Find the relocation section for ".debug_ranges". unsigned int reloc_shndx = 0; unsigned int reloc_type = 0; for (unsigned int i = 0; i < object->shnum(); ++i) { reloc_type = object->section_type(i); if ((reloc_type == elfcpp::SHT_REL || reloc_type == elfcpp::SHT_RELA) && object->section_info(i) == ranges_shndx) { reloc_shndx = i; break; } } this->ranges_reloc_mapper_ = make_elf_reloc_mapper(object, symtab, symtab_size); this->ranges_reloc_mapper_->initialize(reloc_shndx, reloc_type); this->reloc_type_ = reloc_type; return true; } // Read a range list from section RANGES_SHNDX at offset RANGES_OFFSET. Dwarf_range_list* Dwarf_ranges_table::read_range_list( Relobj* object, const unsigned char* symtab, off_t symtab_size, unsigned int addr_size, unsigned int ranges_shndx, off_t offset) { Dwarf_range_list* ranges; if (!this->read_ranges_table(object, symtab, symtab_size, ranges_shndx)) return NULL; // Correct the offset. For incremental update links, we have a // relocated offset that is relative to the output section, but // here we need an offset relative to the input section. offset -= this->output_section_offset_; // Read the range list at OFFSET. ranges = new Dwarf_range_list(); off_t base = 0; for (; this->ranges_buffer_ + offset < this->ranges_buffer_end_; offset += 2 * addr_size) { off_t start; off_t end; // Read the raw contents of the section. if (addr_size == 4) { start = this->dwinfo_->read_from_pointer<32>(this->ranges_buffer_ + offset); end = this->dwinfo_->read_from_pointer<32>(this->ranges_buffer_ + offset + 4); } else { start = this->dwinfo_->read_from_pointer<64>(this->ranges_buffer_ + offset); end = this->dwinfo_->read_from_pointer<64>(this->ranges_buffer_ + offset + 8); } // Check for relocations and adjust the values. unsigned int shndx1 = 0; unsigned int shndx2 = 0; if (this->ranges_reloc_mapper_ != NULL) { shndx1 = this->lookup_reloc(offset, &start); shndx2 = this->lookup_reloc(offset + addr_size, &end); } // End of list is marked by a pair of zeroes. if (shndx1 == 0 && start == 0 && end == 0) break; // A "base address selection entry" is identified by // 0xffffffff for the first value of the pair. The second // value is used as a base for subsequent range list entries. if (shndx1 == 0 && start == -1) base = end; else if (shndx1 == shndx2) { if (shndx1 == 0 || object->is_section_included(shndx1)) ranges->add(shndx1, base + start, base + end); } else gold_warning(_("%s: DWARF info may be corrupt; offsets in a " "range list entry are in different sections"), object->name().c_str()); } return ranges; } // Look for a relocation at offset OFF in the range table, // and return the section index and offset of the target. unsigned int Dwarf_ranges_table::lookup_reloc(off_t off, off_t* target_off) { off_t value; unsigned int shndx = this->ranges_reloc_mapper_->get_reloc_target(off, &value); if (shndx == 0) return 0; if (this->reloc_type_ == elfcpp::SHT_REL) *target_off += value; else *target_off = value; return shndx; } // class Dwarf_pubnames_table // Read the pubnames section from the object file. bool Dwarf_pubnames_table::read_section(Relobj* object, const unsigned char* symtab, off_t symtab_size) { section_size_type buffer_size; unsigned int shndx = 0; const char* name = this->is_pubtypes_ ? "pubtypes" : "pubnames"; const char* gnu_name = (this->is_pubtypes_ ? "gnu_pubtypes" : "gnu_pubnames"); for (unsigned int i = 1; i < object->shnum(); ++i) { std::string section_name = object->section_name(i); const char* section_name_suffix = section_name.c_str(); if (is_prefix_of(".debug_", section_name_suffix)) section_name_suffix += 7; else if (is_prefix_of(".zdebug_", section_name_suffix)) section_name_suffix += 8; else continue; if (strcmp(section_name_suffix, name) == 0) { shndx = i; break; } else if (strcmp(section_name_suffix, gnu_name) == 0) { shndx = i; this->is_gnu_style_ = true; break; } } if (shndx == 0) return false; this->buffer_ = object->decompressed_section_contents(shndx, &buffer_size, &this->owns_buffer_); if (this->buffer_ == NULL) return false; this->buffer_end_ = this->buffer_ + buffer_size; // For incremental objects, we have no relocations. if (object->is_incremental()) return true; // Find the relocation section unsigned int reloc_shndx = 0; unsigned int reloc_type = 0; for (unsigned int i = 0; i < object->shnum(); ++i) { reloc_type = object->section_type(i); if ((reloc_type == elfcpp::SHT_REL || reloc_type == elfcpp::SHT_RELA) && object->section_info(i) == shndx) { reloc_shndx = i; break; } } this->reloc_mapper_ = make_elf_reloc_mapper(object, symtab, symtab_size); this->reloc_mapper_->initialize(reloc_shndx, reloc_type); this->reloc_type_ = reloc_type; return true; } // Read the header for the set at OFFSET. bool Dwarf_pubnames_table::read_header(off_t offset) { // Make sure we have actually read the section. gold_assert(this->buffer_ != NULL); if (offset < 0 || offset + 14 >= this->buffer_end_ - this->buffer_) return false; const unsigned char* pinfo = this->buffer_ + offset; // Read the unit_length field. uint64_t unit_length = this->dwinfo_->read_from_pointer<32>(pinfo); pinfo += 4; if (unit_length == 0xffffffff) { unit_length = this->dwinfo_->read_from_pointer<64>(pinfo); this->unit_length_ = unit_length + 12; pinfo += 8; this->offset_size_ = 8; } else { this->unit_length_ = unit_length + 4; this->offset_size_ = 4; } this->end_of_table_ = pinfo + unit_length; // If unit_length is too big, maybe we should reject the whole table, // but in cases we know about, it seems OK to assume that the table // is valid through the actual end of the section. if (this->end_of_table_ > this->buffer_end_) this->end_of_table_ = this->buffer_end_; // Check the version. unsigned int version = this->dwinfo_->read_from_pointer<16>(pinfo); pinfo += 2; if (version != 2) return false; this->reloc_mapper_->get_reloc_target(pinfo - this->buffer_, &this->cu_offset_); // Skip the debug_info_offset and debug_info_size fields. pinfo += 2 * this->offset_size_; if (pinfo >= this->buffer_end_) return false; this->pinfo_ = pinfo; return true; } // Read the next name from the set. const char* Dwarf_pubnames_table::next_name(uint8_t* flag_byte) { const unsigned char* pinfo = this->pinfo_; // Check for end of list. The table should be terminated by an // entry containing nothing but a DIE offset of 0. if (pinfo + this->offset_size_ >= this->end_of_table_) return NULL; // Skip the offset within the CU. If this is zero, but we're not // at the end of the table, then we have a real pubnames entry // whose DIE offset is 0 (likely to be a GCC bug). Since we // don't actually use the DIE offset in building .gdb_index, // it's harmless. pinfo += this->offset_size_; if (this->is_gnu_style_) *flag_byte = *pinfo++; else *flag_byte = 0; // Return a pointer to the string at the current location, // and advance the pointer to the next entry. const char* ret = reinterpret_cast<const char*>(pinfo); while (pinfo < this->buffer_end_ && *pinfo != '\0') ++pinfo; if (pinfo < this->buffer_end_) ++pinfo; this->pinfo_ = pinfo; return ret; } // class Dwarf_die Dwarf_die::Dwarf_die( Dwarf_info_reader* dwinfo, off_t die_offset, Dwarf_die* parent) : dwinfo_(dwinfo), parent_(parent), die_offset_(die_offset), child_offset_(0), sibling_offset_(0), abbrev_code_(NULL), attributes_(), attributes_read_(false), name_(NULL), name_off_(-1), linkage_name_(NULL), linkage_name_off_(-1), string_shndx_(0), specification_(0), abstract_origin_(0) { size_t len; const unsigned char* pdie = dwinfo->buffer_at_offset(die_offset); if (pdie == NULL) return; unsigned int code = read_unsigned_LEB_128(pdie, &len); if (code == 0) { if (parent != NULL) parent->set_sibling_offset(die_offset + len); return; } this->attr_offset_ = len; // Lookup the abbrev code in the abbrev table. this->abbrev_code_ = dwinfo->get_abbrev(code); } // Read all the attributes of the DIE. bool Dwarf_die::read_attributes() { if (this->attributes_read_) return true; gold_assert(this->abbrev_code_ != NULL); const unsigned char* pdie = this->dwinfo_->buffer_at_offset(this->die_offset_); if (pdie == NULL) return false; const unsigned char* pattr = pdie + this->attr_offset_; unsigned int nattr = this->abbrev_code_->attributes.size(); this->attributes_.reserve(nattr); for (unsigned int i = 0; i < nattr; ++i) { size_t len; unsigned int attr = this->abbrev_code_->attributes[i].attr; unsigned int form = this->abbrev_code_->attributes[i].form; if (form == elfcpp::DW_FORM_indirect) { form = read_unsigned_LEB_128(pattr, &len); pattr += len; } off_t attr_off = this->die_offset_ + (pattr - pdie); bool ref_form = false; Attribute_value attr_value; attr_value.attr = attr; attr_value.form = form; attr_value.aux.shndx = 0; switch(form) { case elfcpp::DW_FORM_flag_present: attr_value.val.intval = 1; break; case elfcpp::DW_FORM_strp: { off_t str_off; if (this->dwinfo_->offset_size() == 4) str_off = this->dwinfo_->read_from_pointer<32>(&pattr); else str_off = this->dwinfo_->read_from_pointer<64>(&pattr); unsigned int shndx = this->dwinfo_->lookup_reloc(attr_off, &str_off); attr_value.aux.shndx = shndx; attr_value.val.refval = str_off; break; } case elfcpp::DW_FORM_sec_offset: { off_t sec_off; if (this->dwinfo_->offset_size() == 4) sec_off = this->dwinfo_->read_from_pointer<32>(&pattr); else sec_off = this->dwinfo_->read_from_pointer<64>(&pattr); unsigned int shndx = this->dwinfo_->lookup_reloc(attr_off, &sec_off); attr_value.aux.shndx = shndx; attr_value.val.refval = sec_off; ref_form = true; break; } case elfcpp::DW_FORM_addr: { off_t sec_off; if (this->dwinfo_->address_size() == 4) sec_off = this->dwinfo_->read_from_pointer<32>(&pattr); else sec_off = this->dwinfo_->read_from_pointer<64>(&pattr); unsigned int shndx = this->dwinfo_->lookup_reloc(attr_off, &sec_off); attr_value.aux.shndx = shndx; attr_value.val.refval = sec_off; ref_form = true; break; } case elfcpp::DW_FORM_ref_addr: { off_t sec_off; if (this->dwinfo_->ref_addr_size() == 4) sec_off = this->dwinfo_->read_from_pointer<32>(&pattr); else sec_off = this->dwinfo_->read_from_pointer<64>(&pattr); unsigned int shndx = this->dwinfo_->lookup_reloc(attr_off, &sec_off); attr_value.aux.shndx = shndx; attr_value.val.refval = sec_off; ref_form = true; break; } case elfcpp::DW_FORM_block1: attr_value.aux.blocklen = *pattr++; attr_value.val.blockval = pattr; pattr += attr_value.aux.blocklen; break; case elfcpp::DW_FORM_block2: attr_value.aux.blocklen = this->dwinfo_->read_from_pointer<16>(&pattr); attr_value.val.blockval = pattr; pattr += attr_value.aux.blocklen; break; case elfcpp::DW_FORM_block4: attr_value.aux.blocklen = this->dwinfo_->read_from_pointer<32>(&pattr); attr_value.val.blockval = pattr; pattr += attr_value.aux.blocklen; break; case elfcpp::DW_FORM_block: case elfcpp::DW_FORM_exprloc: attr_value.aux.blocklen = read_unsigned_LEB_128(pattr, &len); attr_value.val.blockval = pattr + len; pattr += len + attr_value.aux.blocklen; break; case elfcpp::DW_FORM_data1: case elfcpp::DW_FORM_flag: attr_value.val.intval = *pattr++; break; case elfcpp::DW_FORM_ref1: attr_value.val.refval = *pattr++; ref_form = true; break; case elfcpp::DW_FORM_data2: attr_value.val.intval = this->dwinfo_->read_from_pointer<16>(&pattr); break; case elfcpp::DW_FORM_ref2: attr_value.val.refval = this->dwinfo_->read_from_pointer<16>(&pattr); ref_form = true; break; case elfcpp::DW_FORM_data4: { off_t sec_off; sec_off = this->dwinfo_->read_from_pointer<32>(&pattr); unsigned int shndx = this->dwinfo_->lookup_reloc(attr_off, &sec_off); attr_value.aux.shndx = shndx; attr_value.val.intval = sec_off; break; } case elfcpp::DW_FORM_ref4: { off_t sec_off; sec_off = this->dwinfo_->read_from_pointer<32>(&pattr); unsigned int shndx = this->dwinfo_->lookup_reloc(attr_off, &sec_off); attr_value.aux.shndx = shndx; attr_value.val.refval = sec_off; ref_form = true; break; } case elfcpp::DW_FORM_data8: { off_t sec_off; sec_off = this->dwinfo_->read_from_pointer<64>(&pattr); unsigned int shndx = this->dwinfo_->lookup_reloc(attr_off, &sec_off); attr_value.aux.shndx = shndx; attr_value.val.intval = sec_off; break; } case elfcpp::DW_FORM_ref_sig8: attr_value.val.uintval = this->dwinfo_->read_from_pointer<64>(&pattr); break; case elfcpp::DW_FORM_ref8: { off_t sec_off; sec_off = this->dwinfo_->read_from_pointer<64>(&pattr); unsigned int shndx = this->dwinfo_->lookup_reloc(attr_off, &sec_off); attr_value.aux.shndx = shndx; attr_value.val.refval = sec_off; ref_form = true; break; } case elfcpp::DW_FORM_ref_udata: attr_value.val.refval = read_unsigned_LEB_128(pattr, &len); ref_form = true; pattr += len; break; case elfcpp::DW_FORM_udata: case elfcpp::DW_FORM_GNU_addr_index: case elfcpp::DW_FORM_GNU_str_index: attr_value.val.uintval = read_unsigned_LEB_128(pattr, &len); pattr += len; break; case elfcpp::DW_FORM_sdata: attr_value.val.intval = read_signed_LEB_128(pattr, &len); pattr += len; break; case elfcpp::DW_FORM_string: attr_value.val.stringval = reinterpret_cast<const char*>(pattr); len = strlen(attr_value.val.stringval); pattr += len + 1; break; default: return false; } // Cache the most frequently-requested attributes. switch (attr) { case elfcpp::DW_AT_name: if (form == elfcpp::DW_FORM_string) this->name_ = attr_value.val.stringval; else if (form == elfcpp::DW_FORM_strp) { // All indirect strings should refer to the same // string section, so we just save the last one seen. this->string_shndx_ = attr_value.aux.shndx; this->name_off_ = attr_value.val.refval; } break; case elfcpp::DW_AT_linkage_name: case elfcpp::DW_AT_MIPS_linkage_name: if (form == elfcpp::DW_FORM_string) this->linkage_name_ = attr_value.val.stringval; else if (form == elfcpp::DW_FORM_strp) { // All indirect strings should refer to the same // string section, so we just save the last one seen. this->string_shndx_ = attr_value.aux.shndx; this->linkage_name_off_ = attr_value.val.refval; } break; case elfcpp::DW_AT_specification: if (ref_form) this->specification_ = attr_value.val.refval; break; case elfcpp::DW_AT_abstract_origin: if (ref_form) this->abstract_origin_ = attr_value.val.refval; break; case elfcpp::DW_AT_sibling: if (ref_form && attr_value.aux.shndx == 0) this->sibling_offset_ = attr_value.val.refval; default: break; } this->attributes_.push_back(attr_value); } // Now that we know where the next DIE begins, record the offset // to avoid later recalculation. if (this->has_children()) this->child_offset_ = this->die_offset_ + (pattr - pdie); else this->sibling_offset_ = this->die_offset_ + (pattr - pdie); this->attributes_read_ = true; return true; } // Skip all the attributes of the DIE and return the offset of the next DIE. off_t Dwarf_die::skip_attributes() { gold_assert(this->abbrev_code_ != NULL); const unsigned char* pdie = this->dwinfo_->buffer_at_offset(this->die_offset_); if (pdie == NULL) return 0; const unsigned char* pattr = pdie + this->attr_offset_; for (unsigned int i = 0; i < this->abbrev_code_->attributes.size(); ++i) { size_t len; unsigned int form = this->abbrev_code_->attributes[i].form; if (form == elfcpp::DW_FORM_indirect) { form = read_unsigned_LEB_128(pattr, &len); pattr += len; } switch(form) { case elfcpp::DW_FORM_flag_present: break; case elfcpp::DW_FORM_strp: case elfcpp::DW_FORM_sec_offset: pattr += this->dwinfo_->offset_size(); break; case elfcpp::DW_FORM_addr: pattr += this->dwinfo_->address_size(); break; case elfcpp::DW_FORM_ref_addr: pattr += this->dwinfo_->ref_addr_size(); break; case elfcpp::DW_FORM_block1: pattr += 1 + *pattr; break; case elfcpp::DW_FORM_block2: { uint16_t block_size; block_size = this->dwinfo_->read_from_pointer<16>(&pattr); pattr += block_size; break; } case elfcpp::DW_FORM_block4: { uint32_t block_size; block_size = this->dwinfo_->read_from_pointer<32>(&pattr); pattr += block_size; break; } case elfcpp::DW_FORM_block: case elfcpp::DW_FORM_exprloc: { uint64_t block_size; block_size = read_unsigned_LEB_128(pattr, &len); pattr += len + block_size; break; } case elfcpp::DW_FORM_data1: case elfcpp::DW_FORM_ref1: case elfcpp::DW_FORM_flag: pattr += 1; break; case elfcpp::DW_FORM_data2: case elfcpp::DW_FORM_ref2: pattr += 2; break; case elfcpp::DW_FORM_data4: case elfcpp::DW_FORM_ref4: pattr += 4; break; case elfcpp::DW_FORM_data8: case elfcpp::DW_FORM_ref8: case elfcpp::DW_FORM_ref_sig8: pattr += 8; break; case elfcpp::DW_FORM_ref_udata: case elfcpp::DW_FORM_udata: case elfcpp::DW_FORM_GNU_addr_index: case elfcpp::DW_FORM_GNU_str_index: read_unsigned_LEB_128(pattr, &len); pattr += len; break; case elfcpp::DW_FORM_sdata: read_signed_LEB_128(pattr, &len); pattr += len; break; case elfcpp::DW_FORM_string: len = strlen(reinterpret_cast<const char*>(pattr)); pattr += len + 1; break; default: return 0; } } return this->die_offset_ + (pattr - pdie); } // Get the name of the DIE and cache it. void Dwarf_die::set_name() { if (this->name_ != NULL || !this->read_attributes()) return; if (this->name_off_ != -1) this->name_ = this->dwinfo_->get_string(this->name_off_, this->string_shndx_); } // Get the linkage name of the DIE and cache it. void Dwarf_die::set_linkage_name() { if (this->linkage_name_ != NULL || !this->read_attributes()) return; if (this->linkage_name_off_ != -1) this->linkage_name_ = this->dwinfo_->get_string(this->linkage_name_off_, this->string_shndx_); } // Return the value of attribute ATTR. const Dwarf_die::Attribute_value* Dwarf_die::attribute(unsigned int attr) { if (!this->read_attributes()) return NULL; for (unsigned int i = 0; i < this->attributes_.size(); ++i) { if (this->attributes_[i].attr == attr) return &this->attributes_[i]; } return NULL; } const char* Dwarf_die::string_attribute(unsigned int attr) { const Attribute_value* attr_val = this->attribute(attr); if (attr_val == NULL) return NULL; switch (attr_val->form) { case elfcpp::DW_FORM_string: return attr_val->val.stringval; case elfcpp::DW_FORM_strp: return this->dwinfo_->get_string(attr_val->val.refval, attr_val->aux.shndx); default: return NULL; } } int64_t Dwarf_die::int_attribute(unsigned int attr) { const Attribute_value* attr_val = this->attribute(attr); if (attr_val == NULL) return 0; switch (attr_val->form) { case elfcpp::DW_FORM_flag_present: case elfcpp::DW_FORM_data1: case elfcpp::DW_FORM_flag: case elfcpp::DW_FORM_data2: case elfcpp::DW_FORM_data4: case elfcpp::DW_FORM_data8: case elfcpp::DW_FORM_sdata: return attr_val->val.intval; default: return 0; } } uint64_t Dwarf_die::uint_attribute(unsigned int attr) { const Attribute_value* attr_val = this->attribute(attr); if (attr_val == NULL) return 0; switch (attr_val->form) { case elfcpp::DW_FORM_flag_present: case elfcpp::DW_FORM_data1: case elfcpp::DW_FORM_flag: case elfcpp::DW_FORM_data4: case elfcpp::DW_FORM_data8: case elfcpp::DW_FORM_ref_sig8: case elfcpp::DW_FORM_udata: return attr_val->val.uintval; default: return 0; } } off_t Dwarf_die::ref_attribute(unsigned int attr, unsigned int* shndx) { const Attribute_value* attr_val = this->attribute(attr); if (attr_val == NULL) return -1; switch (attr_val->form) { case elfcpp::DW_FORM_sec_offset: case elfcpp::DW_FORM_addr: case elfcpp::DW_FORM_ref_addr: case elfcpp::DW_FORM_ref1: case elfcpp::DW_FORM_ref2: case elfcpp::DW_FORM_ref4: case elfcpp::DW_FORM_ref8: case elfcpp::DW_FORM_ref_udata: *shndx = attr_val->aux.shndx; return attr_val->val.refval; case elfcpp::DW_FORM_ref_sig8: *shndx = attr_val->aux.shndx; return attr_val->val.uintval; case elfcpp::DW_FORM_data4: case elfcpp::DW_FORM_data8: *shndx = attr_val->aux.shndx; return attr_val->val.intval; default: return -1; } } off_t Dwarf_die::address_attribute(unsigned int attr, unsigned int* shndx) { const Attribute_value* attr_val = this->attribute(attr); if (attr_val == NULL || attr_val->form != elfcpp::DW_FORM_addr) return -1; *shndx = attr_val->aux.shndx; return attr_val->val.refval; } // Return the offset of this DIE's first child. off_t Dwarf_die::child_offset() { gold_assert(this->abbrev_code_ != NULL); if (!this->has_children()) return 0; if (this->child_offset_ == 0) this->child_offset_ = this->skip_attributes(); return this->child_offset_; } // Return the offset of this DIE's next sibling. off_t Dwarf_die::sibling_offset() { gold_assert(this->abbrev_code_ != NULL); if (this->sibling_offset_ != 0) return this->sibling_offset_; if (!this->has_children()) { this->sibling_offset_ = this->skip_attributes(); return this->sibling_offset_; } if (this->has_sibling_attribute()) { if (!this->read_attributes()) return 0; if (this->sibling_offset_ != 0) return this->sibling_offset_; } // Skip over the children. off_t child_offset = this->child_offset(); while (child_offset > 0) { Dwarf_die die(this->dwinfo_, child_offset, this); // The Dwarf_die ctor will set this DIE's sibling offset // when it reads a zero abbrev code. if (die.tag() == 0) break; child_offset = die.sibling_offset(); } // This should be set by now. If not, there was a problem reading // the DWARF info, and we return 0. return this->sibling_offset_; } // class Dwarf_info_reader // Begin parsing the debug info. This calls visit_compilation_unit() // or visit_type_unit() for each compilation or type unit found in the // section, and visit_die() for each top-level DIE. void Dwarf_info_reader::parse() { if (this->object_->is_big_endian()) { #if defined(HAVE_TARGET_32_BIG) || defined(HAVE_TARGET_64_BIG) this->do_parse<true>(); #else gold_unreachable(); #endif } else { #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_64_LITTLE) this->do_parse<false>(); #else gold_unreachable(); #endif } } template<bool big_endian> void Dwarf_info_reader::do_parse() { // Get the section contents and decompress if necessary. section_size_type buffer_size; bool buffer_is_new; this->buffer_ = this->object_->decompressed_section_contents(this->shndx_, &buffer_size, &buffer_is_new); if (this->buffer_ == NULL || buffer_size == 0) return; this->buffer_end_ = this->buffer_ + buffer_size; // The offset of this input section in the output section. off_t section_offset = this->object_->output_section_offset(this->shndx_); // Start tracking relocations for this section. this->reloc_mapper_ = make_elf_reloc_mapper(this->object_, this->symtab_, this->symtab_size_); this->reloc_mapper_->initialize(this->reloc_shndx_, this->reloc_type_); // Loop over compilation units (or type units). unsigned int abbrev_shndx = this->abbrev_shndx_; off_t abbrev_offset = 0; const unsigned char* pinfo = this->buffer_; while (pinfo < this->buffer_end_) { // Read the compilation (or type) unit header. const unsigned char* cu_start = pinfo; this->cu_offset_ = cu_start - this->buffer_; this->cu_length_ = this->buffer_end_ - cu_start; // Read unit_length (4 or 12 bytes). if (!this->check_buffer(pinfo + 4)) break; uint32_t unit_length = elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo); pinfo += 4; if (unit_length == 0xffffffff) { if (!this->check_buffer(pinfo + 8)) break; unit_length = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo); pinfo += 8; this->offset_size_ = 8; } else this->offset_size_ = 4; if (!this->check_buffer(pinfo + unit_length)) break; const unsigned char* cu_end = pinfo + unit_length; this->cu_length_ = cu_end - cu_start; if (!this->check_buffer(pinfo + 2 + this->offset_size_ + 1)) break; // Read version (2 bytes). this->cu_version_ = elfcpp::Swap_unaligned<16, big_endian>::readval(pinfo); pinfo += 2; // Read debug_abbrev_offset (4 or 8 bytes). if (this->offset_size_ == 4) abbrev_offset = elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo); else abbrev_offset = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo); if (this->reloc_shndx_ > 0) { off_t reloc_offset = pinfo - this->buffer_; off_t value; abbrev_shndx = this->reloc_mapper_->get_reloc_target(reloc_offset, &value); if (abbrev_shndx == 0) return; if (this->reloc_type_ == elfcpp::SHT_REL) abbrev_offset += value; else abbrev_offset = value; } pinfo += this->offset_size_; // Read address_size (1 byte). this->address_size_ = *pinfo++; // For type units, read the two extra fields. uint64_t signature = 0; off_t type_offset = 0; if (this->is_type_unit_) { if (!this->check_buffer(pinfo + 8 + this->offset_size_)) break; // Read type_signature (8 bytes). signature = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo); pinfo += 8; // Read type_offset (4 or 8 bytes). if (this->offset_size_ == 4) type_offset = elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo); else type_offset = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo); pinfo += this->offset_size_; } // Read the .debug_abbrev table. this->abbrev_table_.read_abbrevs(this->object_, abbrev_shndx, abbrev_offset); // Visit the root DIE. Dwarf_die root_die(this, pinfo - (this->buffer_ + this->cu_offset_), NULL); if (root_die.tag() != 0) { // Visit the CU or TU. if (this->is_type_unit_) this->visit_type_unit(section_offset + this->cu_offset_, cu_end - cu_start, type_offset, signature, &root_die); else this->visit_compilation_unit(section_offset + this->cu_offset_, cu_end - cu_start, &root_die); } // Advance to the next CU. pinfo = cu_end; } if (buffer_is_new) { delete[] this->buffer_; this->buffer_ = NULL; } } // Read the DWARF string table. bool Dwarf_info_reader::do_read_string_table(unsigned int string_shndx) { Relobj* object = this->object_; // If we don't have relocations, string_shndx will be 0, and // we'll have to hunt for the .debug_str section. if (string_shndx == 0) { for (unsigned int i = 1; i < this->object_->shnum(); ++i) { std::string name = object->section_name(i); if (name == ".debug_str" || name == ".zdebug_str") { string_shndx = i; this->string_output_section_offset_ = object->output_section_offset(i); break; } } if (string_shndx == 0) return false; } if (this->owns_string_buffer_ && this->string_buffer_ != NULL) { delete[] this->string_buffer_; this->owns_string_buffer_ = false; } // Get the secton contents and decompress if necessary. section_size_type buffer_size; const unsigned char* buffer = object->decompressed_section_contents(string_shndx, &buffer_size, &this->owns_string_buffer_); this->string_buffer_ = reinterpret_cast<const char*>(buffer); this->string_buffer_end_ = this->string_buffer_ + buffer_size; this->string_shndx_ = string_shndx; return true; } // Read a possibly unaligned integer of SIZE. template <int valsize> inline typename elfcpp::Valtype_base<valsize>::Valtype Dwarf_info_reader::read_from_pointer(const unsigned char* source) { typename elfcpp::Valtype_base<valsize>::Valtype return_value; if (this->object_->is_big_endian()) return_value = elfcpp::Swap_unaligned<valsize, true>::readval(source); else return_value = elfcpp::Swap_unaligned<valsize, false>::readval(source); return return_value; } // Read a possibly unaligned integer of SIZE. Update SOURCE after read. template <int valsize> inline typename elfcpp::Valtype_base<valsize>::Valtype Dwarf_info_reader::read_from_pointer(const unsigned char** source) { typename elfcpp::Valtype_base<valsize>::Valtype return_value; if (this->object_->is_big_endian()) return_value = elfcpp::Swap_unaligned<valsize, true>::readval(*source); else return_value = elfcpp::Swap_unaligned<valsize, false>::readval(*source); *source += valsize / 8; return return_value; } // Look for a relocation at offset ATTR_OFF in the dwarf info, // and return the section index and offset of the target. unsigned int Dwarf_info_reader::lookup_reloc(off_t attr_off, off_t* target_off) { off_t value; attr_off += this->cu_offset_; unsigned int shndx = this->reloc_mapper_->get_reloc_target(attr_off, &value); if (shndx == 0) return 0; if (this->reloc_type_ == elfcpp::SHT_REL) *target_off += value; else *target_off = value; return shndx; } // Return a string from the DWARF string table. const char* Dwarf_info_reader::get_string(off_t str_off, unsigned int string_shndx) { if (!this->read_string_table(string_shndx)) return NULL; // Correct the offset. For incremental update links, we have a // relocated offset that is relative to the output section, but // here we need an offset relative to the input section. str_off -= this->string_output_section_offset_; const char* p = this->string_buffer_ + str_off; if (p < this->string_buffer_ || p >= this->string_buffer_end_) return NULL; return p; } // The following are default, do-nothing, implementations of the // hook methods normally provided by a derived class. We provide // default implementations rather than no implementation so that // a derived class needs to implement only the hooks that it needs // to use. // Process a compilation unit and parse its child DIE. void Dwarf_info_reader::visit_compilation_unit(off_t, off_t, Dwarf_die*) { } // Process a type unit and parse its child DIE. void Dwarf_info_reader::visit_type_unit(off_t, off_t, off_t, uint64_t, Dwarf_die*) { } // Print a warning about a corrupt debug section. void Dwarf_info_reader::warn_corrupt_debug_section() const { gold_warning(_("%s: corrupt debug info in %s"), this->object_->name().c_str(), this->object_->section_name(this->shndx_).c_str()); } // class Sized_dwarf_line_info struct LineStateMachine { int file_num; uint64_t address; int line_num; int column_num; unsigned int shndx; // the section address refers to bool is_stmt; // stmt means statement. bool basic_block; bool end_sequence; }; static void ResetLineStateMachine(struct LineStateMachine* lsm, bool default_is_stmt) { lsm->file_num = 1; lsm->address = 0; lsm->line_num = 1; lsm->column_num = 0; lsm->shndx = -1U; lsm->is_stmt = default_is_stmt; lsm->basic_block = false; lsm->end_sequence = false; } template<int size, bool big_endian> Sized_dwarf_line_info<size, big_endian>::Sized_dwarf_line_info( Object* object, unsigned int read_shndx) : data_valid_(false), buffer_(NULL), buffer_start_(NULL), reloc_mapper_(NULL), symtab_buffer_(NULL), directories_(), files_(), current_header_index_(-1) { unsigned int debug_shndx; for (debug_shndx = 1; debug_shndx < object->shnum(); ++debug_shndx) { // FIXME: do this more efficiently: section_name() isn't super-fast std::string name = object->section_name(debug_shndx); if (name == ".debug_line" || name == ".zdebug_line") { section_size_type buffer_size; bool is_new = false; this->buffer_ = object->decompressed_section_contents(debug_shndx, &buffer_size, &is_new); if (is_new) this->buffer_start_ = this->buffer_; this->buffer_end_ = this->buffer_ + buffer_size; break; } } if (this->buffer_ == NULL) return; // Find the relocation section for ".debug_line". // We expect these for relobjs (.o's) but not dynobjs (.so's). unsigned int reloc_shndx = 0; for (unsigned int i = 0; i < object->shnum(); ++i) { unsigned int reloc_sh_type = object->section_type(i); if ((reloc_sh_type == elfcpp::SHT_REL || reloc_sh_type == elfcpp::SHT_RELA) && object->section_info(i) == debug_shndx) { reloc_shndx = i; this->track_relocs_type_ = reloc_sh_type; break; } } // Finally, we need the symtab section to interpret the relocs. if (reloc_shndx != 0) { unsigned int symtab_shndx; for (symtab_shndx = 0; symtab_shndx < object->shnum(); ++symtab_shndx) if (object->section_type(symtab_shndx) == elfcpp::SHT_SYMTAB) { this->symtab_buffer_ = object->section_contents( symtab_shndx, &this->symtab_buffer_size_, false); break; } if (this->symtab_buffer_ == NULL) return; } this->reloc_mapper_ = new Sized_elf_reloc_mapper<size, big_endian>(object, this->symtab_buffer_, this->symtab_buffer_size_); if (!this->reloc_mapper_->initialize(reloc_shndx, this->track_relocs_type_)) return; // Now that we have successfully read all the data, parse the debug // info. this->data_valid_ = true; this->read_line_mappings(read_shndx); } // Read the DWARF header. template<int size, bool big_endian> const unsigned char* Sized_dwarf_line_info<size, big_endian>::read_header_prolog( const unsigned char* lineptr) { uint32_t initial_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr); lineptr += 4; // In DWARF2/3, if the initial length is all 1 bits, then the offset // size is 8 and we need to read the next 8 bytes for the real length. if (initial_length == 0xffffffff) { header_.offset_size = 8; initial_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr); lineptr += 8; } else header_.offset_size = 4; header_.total_length = initial_length; gold_assert(lineptr + header_.total_length <= buffer_end_); header_.version = elfcpp::Swap_unaligned<16, big_endian>::readval(lineptr); lineptr += 2; if (header_.offset_size == 4) header_.prologue_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr); else header_.prologue_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr); lineptr += header_.offset_size; header_.min_insn_length = *lineptr; lineptr += 1; if (header_.version < 4) header_.max_ops_per_insn = 1; else { // DWARF 4 added the maximum_operations_per_instruction field. header_.max_ops_per_insn = *lineptr; lineptr += 1; // TODO: Add support for values other than 1. gold_assert(header_.max_ops_per_insn == 1); } header_.default_is_stmt = *lineptr; lineptr += 1; header_.line_base = *reinterpret_cast<const signed char*>(lineptr); lineptr += 1; header_.line_range = *lineptr; lineptr += 1; header_.opcode_base = *lineptr; lineptr += 1; header_.std_opcode_lengths.resize(header_.opcode_base + 1); header_.std_opcode_lengths[0] = 0; for (int i = 1; i < header_.opcode_base; i++) { header_.std_opcode_lengths[i] = *lineptr; lineptr += 1; } return lineptr; } // The header for a debug_line section is mildly complicated, because // the line info is very tightly encoded. template<int size, bool big_endian> const unsigned char* Sized_dwarf_line_info<size, big_endian>::read_header_tables( const unsigned char* lineptr) { ++this->current_header_index_; // Create a new directories_ entry and a new files_ entry for our new // header. We initialize each with a single empty element, because // dwarf indexes directory and filenames starting at 1. gold_assert(static_cast<int>(this->directories_.size()) == this->current_header_index_); gold_assert(static_cast<int>(this->files_.size()) == this->current_header_index_); this->directories_.push_back(std::vector<std::string>(1)); this->files_.push_back(std::vector<std::pair<int, std::string> >(1)); // It is legal for the directory entry table to be empty. if (*lineptr) { int dirindex = 1; while (*lineptr) { const char* dirname = reinterpret_cast<const char*>(lineptr); gold_assert(dirindex == static_cast<int>(this->directories_.back().size())); this->directories_.back().push_back(dirname); lineptr += this->directories_.back().back().size() + 1; dirindex++; } } lineptr++; // It is also legal for the file entry table to be empty. if (*lineptr) { int fileindex = 1; size_t len; while (*lineptr) { const char* filename = reinterpret_cast<const char*>(lineptr); lineptr += strlen(filename) + 1; uint64_t dirindex = read_unsigned_LEB_128(lineptr, &len); lineptr += len; if (dirindex >= this->directories_.back().size()) dirindex = 0; int dirindexi = static_cast<int>(dirindex); read_unsigned_LEB_128(lineptr, &len); // mod_time lineptr += len; read_unsigned_LEB_128(lineptr, &len); // filelength lineptr += len; gold_assert(fileindex == static_cast<int>(this->files_.back().size())); this->files_.back().push_back(std::make_pair(dirindexi, filename)); fileindex++; } } lineptr++; return lineptr; } // Process a single opcode in the .debug.line structure. template<int size, bool big_endian> bool Sized_dwarf_line_info<size, big_endian>::process_one_opcode( const unsigned char* start, struct LineStateMachine* lsm, size_t* len) { size_t oplen = 0; size_t templen; unsigned char opcode = *start; oplen++; start++; // If the opcode is great than the opcode_base, it is a special // opcode. Most line programs consist mainly of special opcodes. if (opcode >= header_.opcode_base) { opcode -= header_.opcode_base; const int advance_address = ((opcode / header_.line_range) * header_.min_insn_length); lsm->address += advance_address; const int advance_line = ((opcode % header_.line_range) + header_.line_base); lsm->line_num += advance_line; lsm->basic_block = true; *len = oplen; return true; } // Otherwise, we have the regular opcodes switch (opcode) { case elfcpp::DW_LNS_copy: lsm->basic_block = false; *len = oplen; return true; case elfcpp::DW_LNS_advance_pc: { const uint64_t advance_address = read_unsigned_LEB_128(start, &templen); oplen += templen; lsm->address += header_.min_insn_length * advance_address; } break; case elfcpp::DW_LNS_advance_line: { const uint64_t advance_line = read_signed_LEB_128(start, &templen); oplen += templen; lsm->line_num += advance_line; } break; case elfcpp::DW_LNS_set_file: { const uint64_t fileno = read_unsigned_LEB_128(start, &templen); oplen += templen; lsm->file_num = fileno; } break; case elfcpp::DW_LNS_set_column: { const uint64_t colno = read_unsigned_LEB_128(start, &templen); oplen += templen; lsm->column_num = colno; } break; case elfcpp::DW_LNS_negate_stmt: lsm->is_stmt = !lsm->is_stmt; break; case elfcpp::DW_LNS_set_basic_block: lsm->basic_block = true; break; case elfcpp::DW_LNS_fixed_advance_pc: { int advance_address; advance_address = elfcpp::Swap_unaligned<16, big_endian>::readval(start); oplen += 2; lsm->address += advance_address; } break; case elfcpp::DW_LNS_const_add_pc: { const int advance_address = (header_.min_insn_length * ((255 - header_.opcode_base) / header_.line_range)); lsm->address += advance_address; } break; case elfcpp::DW_LNS_extended_op: { const uint64_t extended_op_len = read_unsigned_LEB_128(start, &templen); start += templen; oplen += templen + extended_op_len; const unsigned char extended_op = *start; start++; switch (extended_op) { case elfcpp::DW_LNE_end_sequence: // This means that the current byte is the one immediately // after a set of instructions. Record the current line // for up to one less than the current address. lsm->line_num = -1; lsm->end_sequence = true; *len = oplen; return true; case elfcpp::DW_LNE_set_address: { lsm->address = elfcpp::Swap_unaligned<size, big_endian>::readval(start); typename Reloc_map::const_iterator it = this->reloc_map_.find(start - this->buffer_); if (it != reloc_map_.end()) { // If this is a SHT_RELA section, then ignore the // section contents. This assumes that this is a // straight reloc which just uses the reloc addend. // The reloc addend has already been included in the // symbol value. if (this->track_relocs_type_ == elfcpp::SHT_RELA) lsm->address = 0; // Add in the symbol value. lsm->address += it->second.second; lsm->shndx = it->second.first; } else { // If we're a normal .o file, with relocs, every // set_address should have an associated relocation. if (this->input_is_relobj()) this->data_valid_ = false; } break; } case elfcpp::DW_LNE_define_file: { const char* filename = reinterpret_cast<const char*>(start); templen = strlen(filename) + 1; start += templen; uint64_t dirindex = read_unsigned_LEB_128(start, &templen); if (dirindex >= this->directories_.back().size()) dirindex = 0; int dirindexi = static_cast<int>(dirindex); // This opcode takes two additional ULEB128 parameters // (mod_time and filelength), but we don't use those // values. Because OPLEN already tells us how far to // skip to the next opcode, we don't need to read // them at all. this->files_.back().push_back(std::make_pair(dirindexi, filename)); } break; } } break; default: { // Ignore unknown opcode silently for (int i = 0; i < header_.std_opcode_lengths[opcode]; i++) { size_t templen; read_unsigned_LEB_128(start, &templen); start += templen; oplen += templen; } } break; } *len = oplen; return false; } // Read the debug information at LINEPTR and store it in the line // number map. template<int size, bool big_endian> unsigned const char* Sized_dwarf_line_info<size, big_endian>::read_lines(unsigned const char* lineptr, unsigned int shndx) { struct LineStateMachine lsm; // LENGTHSTART is the place the length field is based on. It is the // point in the header after the initial length field. const unsigned char* lengthstart = buffer_; // In 64 bit dwarf, the initial length is 12 bytes, because of the // 0xffffffff at the start. if (header_.offset_size == 8) lengthstart += 12; else lengthstart += 4; while (lineptr < lengthstart + header_.total_length) { ResetLineStateMachine(&lsm, header_.default_is_stmt); while (!lsm.end_sequence) { size_t oplength; bool add_line = this->process_one_opcode(lineptr, &lsm, &oplength); if (add_line && (shndx == -1U || lsm.shndx == -1U || shndx == lsm.shndx)) { Offset_to_lineno_entry entry = { static_cast<off_t>(lsm.address), this->current_header_index_, static_cast<unsigned int>(lsm.file_num), true, lsm.line_num }; std::vector<Offset_to_lineno_entry>& map(this->line_number_map_[lsm.shndx]); // If we see two consecutive entries with the same // offset and a real line number, then mark the first // one as non-canonical. if (!map.empty() && (map.back().offset == static_cast<off_t>(lsm.address)) && lsm.line_num != -1 && map.back().line_num != -1) map.back().last_line_for_offset = false; map.push_back(entry); } lineptr += oplength; } } return lengthstart + header_.total_length; } // Read the relocations into a Reloc_map. template<int size, bool big_endian> void Sized_dwarf_line_info<size, big_endian>::read_relocs() { if (this->symtab_buffer_ == NULL) return; off_t value; off_t reloc_offset; while ((reloc_offset = this->reloc_mapper_->next_offset()) != -1) { const unsigned int shndx = this->reloc_mapper_->get_reloc_target(reloc_offset, &value); // There is no reason to record non-ordinary section indexes, or // SHN_UNDEF, because they will never match the real section. if (shndx != 0) this->reloc_map_[reloc_offset] = std::make_pair(shndx, value); this->reloc_mapper_->advance(reloc_offset + 1); } } // Read the line number info. template<int size, bool big_endian> void Sized_dwarf_line_info<size, big_endian>::read_line_mappings(unsigned int shndx) { gold_assert(this->data_valid_ == true); this->read_relocs(); while (this->buffer_ < this->buffer_end_) { const unsigned char* lineptr = this->buffer_; lineptr = this->read_header_prolog(lineptr); lineptr = this->read_header_tables(lineptr); lineptr = this->read_lines(lineptr, shndx); this->buffer_ = lineptr; } // Sort the lines numbers, so addr2line can use binary search. for (typename Lineno_map::iterator it = line_number_map_.begin(); it != line_number_map_.end(); ++it) // Each vector needs to be sorted by offset. std::sort(it->second.begin(), it->second.end()); } // Some processing depends on whether the input is a .o file or not. // For instance, .o files have relocs, and have .debug_lines // information on a per section basis. .so files, on the other hand, // lack relocs, and offsets are unique, so we can ignore the section // information. template<int size, bool big_endian> bool Sized_dwarf_line_info<size, big_endian>::input_is_relobj() { // Only .o files have relocs and the symtab buffer that goes with them. return this->symtab_buffer_ != NULL; } // Given an Offset_to_lineno_entry vector, and an offset, figure out // if the offset points into a function according to the vector (see // comments below for the algorithm). If it does, return an iterator // into the vector that points to the line-number that contains that // offset. If not, it returns vector::end(). static std::vector<Offset_to_lineno_entry>::const_iterator offset_to_iterator(const std::vector<Offset_to_lineno_entry>* offsets, off_t offset) { const Offset_to_lineno_entry lookup_key = { offset, 0, 0, true, 0 }; // lower_bound() returns the smallest offset which is >= lookup_key. // If no offset in offsets is >= lookup_key, returns end(). std::vector<Offset_to_lineno_entry>::const_iterator it = std::lower_bound(offsets->begin(), offsets->end(), lookup_key); // This code is easiest to understand with a concrete example. // Here's a possible offsets array: // {{offset = 3211, header_num = 0, file_num = 1, last, line_num = 16}, // 0 // {offset = 3224, header_num = 0, file_num = 1, last, line_num = 20}, // 1 // {offset = 3226, header_num = 0, file_num = 1, last, line_num = 22}, // 2 // {offset = 3231, header_num = 0, file_num = 1, last, line_num = 25}, // 3 // {offset = 3232, header_num = 0, file_num = 1, last, line_num = -1}, // 4 // {offset = 3232, header_num = 0, file_num = 1, last, line_num = 65}, // 5 // {offset = 3235, header_num = 0, file_num = 1, last, line_num = 66}, // 6 // {offset = 3236, header_num = 0, file_num = 1, last, line_num = -1}, // 7 // {offset = 5764, header_num = 0, file_num = 1, last, line_num = 48}, // 8 // {offset = 5764, header_num = 0, file_num = 1,!last, line_num = 47}, // 9 // {offset = 5765, header_num = 0, file_num = 1, last, line_num = 49}, // 10 // {offset = 5767, header_num = 0, file_num = 1, last, line_num = 50}, // 11 // {offset = 5768, header_num = 0, file_num = 1, last, line_num = 51}, // 12 // {offset = 5773, header_num = 0, file_num = 1, last, line_num = -1}, // 13 // {offset = 5787, header_num = 1, file_num = 1, last, line_num = 19}, // 14 // {offset = 5790, header_num = 1, file_num = 1, last, line_num = 20}, // 15 // {offset = 5793, header_num = 1, file_num = 1, last, line_num = 67}, // 16 // {offset = 5793, header_num = 1, file_num = 1, last, line_num = -1}, // 17 // {offset = 5793, header_num = 1, file_num = 1,!last, line_num = 66}, // 18 // {offset = 5795, header_num = 1, file_num = 1, last, line_num = 68}, // 19 // {offset = 5798, header_num = 1, file_num = 1, last, line_num = -1}, // 20 // The entries with line_num == -1 mark the end of a function: the // associated offset is one past the last instruction in the // function. This can correspond to the beginning of the next // function (as is true for offset 3232); alternately, there can be // a gap between the end of one function and the start of the next // (as is true for some others, most obviously from 3236->5764). // // Case 1: lookup_key has offset == 10. lower_bound returns // offsets[0]. Since it's not an exact match and we're // at the beginning of offsets, we return end() (invalid). // Case 2: lookup_key has offset 10000. lower_bound returns // offset[21] (end()). We return end() (invalid). // Case 3: lookup_key has offset == 3211. lower_bound matches // offsets[0] exactly, and that's the entry we return. // Case 4: lookup_key has offset == 3232. lower_bound returns // offsets[4]. That's an exact match, but indicates // end-of-function. We check if offsets[5] is also an // exact match but not end-of-function. It is, so we // return offsets[5]. // Case 5: lookup_key has offset == 3214. lower_bound returns // offsets[1]. Since it's not an exact match, we back // up to the offset that's < lookup_key, offsets[0]. // We note offsets[0] is a valid entry (not end-of-function), // so that's the entry we return. // Case 6: lookup_key has offset == 4000. lower_bound returns // offsets[8]. Since it's not an exact match, we back // up to offsets[7]. Since offsets[7] indicates // end-of-function, we know lookup_key is between // functions, so we return end() (not a valid offset). // Case 7: lookup_key has offset == 5794. lower_bound returns // offsets[19]. Since it's not an exact match, we back // up to offsets[16]. Note we back up to the *first* // entry with offset 5793, not just offsets[19-1]. // We note offsets[16] is a valid entry, so we return it. // If offsets[16] had had line_num == -1, we would have // checked offsets[17]. The reason for this is that // 16 and 17 can be in an arbitrary order, since we sort // only by offset and last_line_for_offset. (Note it // doesn't help to use line_number as a tertiary sort key, // since sometimes we want the -1 to be first and sometimes // we want it to be last.) // This deals with cases (1) and (2). if ((it == offsets->begin() && offset < it->offset) || it == offsets->end()) return offsets->end(); // This deals with cases (3) and (4). if (offset == it->offset) { while (it != offsets->end() && it->offset == offset && it->line_num == -1) ++it; if (it == offsets->end() || it->offset != offset) return offsets->end(); else return it; } // This handles the first part of case (7) -- we back up to the // *first* entry that has the offset that's behind us. gold_assert(it != offsets->begin()); std::vector<Offset_to_lineno_entry>::const_iterator range_end = it; --it; const off_t range_value = it->offset; while (it != offsets->begin() && (it-1)->offset == range_value) --it; // This handles cases (5), (6), and (7): if any entry in the // equal_range [it, range_end) has a line_num != -1, it's a valid // match. If not, we're not in a function. The line number we saw // last for an offset will be sorted first, so it'll get returned if // it's present. for (; it != range_end; ++it) if (it->line_num != -1) return it; return offsets->end(); } // Returns the canonical filename:lineno for the address passed in. // If other_lines is not NULL, appends the non-canonical lines // assigned to the same address. template<int size, bool big_endian> std::string Sized_dwarf_line_info<size, big_endian>::do_addr2line( unsigned int shndx, off_t offset, std::vector<std::string>* other_lines) { if (this->data_valid_ == false) return ""; const std::vector<Offset_to_lineno_entry>* offsets; // If we do not have reloc information, then our input is a .so or // some similar data structure where all the information is held in // the offset. In that case, we ignore the input shndx. if (this->input_is_relobj()) offsets = &this->line_number_map_[shndx]; else offsets = &this->line_number_map_[-1U]; if (offsets->empty()) return ""; typename std::vector<Offset_to_lineno_entry>::const_iterator it = offset_to_iterator(offsets, offset); if (it == offsets->end()) return ""; std::string result = this->format_file_lineno(*it); gold_debug(DEBUG_LOCATION, "do_addr2line: canonical result: %s", result.c_str()); if (other_lines != NULL) { unsigned int last_file_num = it->file_num; int last_line_num = it->line_num; // Return up to 4 more locations from the beginning of the function // for fuzzy matching. for (++it; it != offsets->end(); ++it) { if (it->offset == offset && it->line_num == -1) continue; // The end of a previous function. if (it->line_num == -1) break; // The end of the current function. if (it->file_num != last_file_num || it->line_num != last_line_num) { other_lines->push_back(this->format_file_lineno(*it)); gold_debug(DEBUG_LOCATION, "do_addr2line: other: %s", other_lines->back().c_str()); last_file_num = it->file_num; last_line_num = it->line_num; } if (it->offset > offset && other_lines->size() >= 4) break; } } return result; } // Convert the file_num + line_num into a string. template<int size, bool big_endian> std::string Sized_dwarf_line_info<size, big_endian>::format_file_lineno( const Offset_to_lineno_entry& loc) const { std::string ret; gold_assert(loc.header_num < static_cast<int>(this->files_.size())); gold_assert(loc.file_num < static_cast<unsigned int>(this->files_[loc.header_num].size())); const std::pair<int, std::string>& filename_pair = this->files_[loc.header_num][loc.file_num]; const std::string& filename = filename_pair.second; gold_assert(loc.header_num < static_cast<int>(this->directories_.size())); gold_assert(filename_pair.first < static_cast<int>(this->directories_[loc.header_num].size())); const std::string& dirname = this->directories_[loc.header_num][filename_pair.first]; if (!dirname.empty()) { ret += dirname; ret += "/"; } ret += filename; if (ret.empty()) ret = "(unknown)"; char buffer[64]; // enough to hold a line number snprintf(buffer, sizeof(buffer), "%d", loc.line_num); ret += ":"; ret += buffer; return ret; } // Dwarf_line_info routines. static unsigned int next_generation_count = 0; struct Addr2line_cache_entry { Object* object; unsigned int shndx; Dwarf_line_info* dwarf_line_info; unsigned int generation_count; unsigned int access_count; Addr2line_cache_entry(Object* o, unsigned int s, Dwarf_line_info* d) : object(o), shndx(s), dwarf_line_info(d), generation_count(next_generation_count), access_count(0) { if (next_generation_count < (1U << 31)) ++next_generation_count; } }; // We expect this cache to be small, so don't bother with a hashtable // or priority queue or anything: just use a simple vector. static std::vector<Addr2line_cache_entry> addr2line_cache; std::string Dwarf_line_info::one_addr2line(Object* object, unsigned int shndx, off_t offset, size_t cache_size, std::vector<std::string>* other_lines) { Dwarf_line_info* lineinfo = NULL; std::vector<Addr2line_cache_entry>::iterator it; // First, check the cache. If we hit, update the counts. for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it) { if (it->object == object && it->shndx == shndx) { lineinfo = it->dwarf_line_info; it->generation_count = next_generation_count; // We cap generation_count at 2^31 -1 to avoid overflow. if (next_generation_count < (1U << 31)) ++next_generation_count; // We cap access_count at 31 so 2^access_count doesn't overflow if (it->access_count < 31) ++it->access_count; break; } } // If we don't hit the cache, create a new object and insert into the // cache. if (lineinfo == NULL) { switch (parameters->size_and_endianness()) { #ifdef HAVE_TARGET_32_LITTLE case Parameters::TARGET_32_LITTLE: lineinfo = new Sized_dwarf_line_info<32, false>(object, shndx); break; #endif #ifdef HAVE_TARGET_32_BIG case Parameters::TARGET_32_BIG: lineinfo = new Sized_dwarf_line_info<32, true>(object, shndx); break; #endif #ifdef HAVE_TARGET_64_LITTLE case Parameters::TARGET_64_LITTLE: lineinfo = new Sized_dwarf_line_info<64, false>(object, shndx); break; #endif #ifdef HAVE_TARGET_64_BIG case Parameters::TARGET_64_BIG: lineinfo = new Sized_dwarf_line_info<64, true>(object, shndx); break; #endif default: gold_unreachable(); } addr2line_cache.push_back(Addr2line_cache_entry(object, shndx, lineinfo)); } // Now that we have our object, figure out the answer std::string retval = lineinfo->addr2line(shndx, offset, other_lines); // Finally, if our cache has grown too big, delete old objects. We // assume the common (probably only) case is deleting only one object. // We use a pretty simple scheme to evict: function of LRU and MFU. while (addr2line_cache.size() > cache_size) { unsigned int lowest_score = ~0U; std::vector<Addr2line_cache_entry>::iterator lowest = addr2line_cache.end(); for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it) { const unsigned int score = (it->generation_count + (1U << it->access_count)); if (score < lowest_score) { lowest_score = score; lowest = it; } } if (lowest != addr2line_cache.end()) { delete lowest->dwarf_line_info; addr2line_cache.erase(lowest); } } return retval; } void Dwarf_line_info::clear_addr2line_cache() { for (std::vector<Addr2line_cache_entry>::iterator it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it) delete it->dwarf_line_info; addr2line_cache.clear(); } #ifdef HAVE_TARGET_32_LITTLE template class Sized_dwarf_line_info<32, false>; #endif #ifdef HAVE_TARGET_32_BIG template class Sized_dwarf_line_info<32, true>; #endif #ifdef HAVE_TARGET_64_LITTLE template class Sized_dwarf_line_info<64, false>; #endif #ifdef HAVE_TARGET_64_BIG template class Sized_dwarf_line_info<64, true>; #endif } // End namespace gold.