/* Reading code for .debug_names Copyright (C) 2023-2024 Free Software Foundation, Inc. This file is part of GDB. 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, see . */ #include "read-debug-names.h" #include "dwarf2/aranges.h" #include "dwarf2/cooked-index.h" #include "complaints.h" #include "cp-support.h" #include "dwz.h" #include "mapped-index.h" #include "read.h" #include "stringify.h" /* This is just like cooked_index_functions, but overrides a single method so the test suite can distinguish the .debug_names case from the ordinary case. */ struct dwarf2_debug_names_index : public cooked_index_functions { /* This dumps minimal information about .debug_names. It is called via "mt print objfiles". The gdb.dwarf2/gdb-index.exp testcase uses this to verify that .debug_names has been loaded. */ void dump (struct objfile *objfile) override { gdb_printf (".debug_names: exists\n"); /* This could call the superclass method if that's useful. */ } }; /* This is like a cooked index, but as it has been ingested from .debug_names, it can't be used to write out an index. */ class debug_names_index : public cooked_index { public: using cooked_index::cooked_index; cooked_index *index_for_writing () override { return nullptr; } quick_symbol_functions_up make_quick_functions () const override { return quick_symbol_functions_up (new dwarf2_debug_names_index); } }; /* A description of the mapped .debug_names. */ struct mapped_debug_names_reader { const gdb_byte *scan_one_entry (const char *name, const gdb_byte *entry, cooked_index_entry **result, std::optional &parent); void scan_entries (uint32_t index, const char *name, const gdb_byte *entry); void scan_all_names (); dwarf2_per_objfile *per_objfile = nullptr; bfd *abfd = nullptr; bfd_endian dwarf5_byte_order {}; bool dwarf5_is_dwarf64 = false; bool augmentation_is_gdb = false; uint8_t offset_size = 0; uint32_t cu_count = 0; uint32_t tu_count = 0, bucket_count = 0, name_count = 0; const gdb_byte *cu_table_reordered = nullptr; const gdb_byte *tu_table_reordered = nullptr; const uint32_t *bucket_table_reordered = nullptr; const uint32_t *hash_table_reordered = nullptr; const gdb_byte *name_table_string_offs_reordered = nullptr; const gdb_byte *name_table_entry_offs_reordered = nullptr; const gdb_byte *entry_pool = nullptr; struct index_val { ULONGEST dwarf_tag; struct attr { /* Attribute name DW_IDX_*. */ ULONGEST dw_idx; /* Attribute form DW_FORM_*. */ ULONGEST form; /* Value if FORM is DW_FORM_implicit_const. */ LONGEST implicit_const; }; std::vector attr_vec; }; std::unordered_map abbrev_map; std::unique_ptr shard; std::vector> needs_parent; std::vector> all_entries; }; /* Scan a single entry from the entries table. Set *RESULT and PARENT (if needed) and return the updated pointer on success, or return nullptr on error, or at the end of the table. */ const gdb_byte * mapped_debug_names_reader::scan_one_entry (const char *name, const gdb_byte *entry, cooked_index_entry **result, std::optional &parent) { unsigned int bytes_read; const ULONGEST abbrev = read_unsigned_leb128 (abfd, entry, &bytes_read); entry += bytes_read; if (abbrev == 0) return nullptr; const auto indexval_it = abbrev_map.find (abbrev); if (indexval_it == abbrev_map.cend ()) { complaint (_("Wrong .debug_names undefined abbrev code %s " "[in module %s]"), pulongest (abbrev), bfd_get_filename (abfd)); return nullptr; } const auto &indexval = indexval_it->second; cooked_index_flag flags = 0; sect_offset die_offset {}; enum language lang = language_unknown; dwarf2_per_cu_data *per_cu = nullptr; for (const auto &attr : indexval.attr_vec) { ULONGEST ull; switch (attr.form) { case DW_FORM_implicit_const: ull = attr.implicit_const; break; case DW_FORM_flag_present: ull = 1; break; case DW_FORM_udata: ull = read_unsigned_leb128 (abfd, entry, &bytes_read); entry += bytes_read; break; case DW_FORM_ref_addr: ull = read_offset (abfd, entry, offset_size); entry += offset_size; break; case DW_FORM_ref4: ull = read_4_bytes (abfd, entry); entry += 4; break; case DW_FORM_ref8: ull = read_8_bytes (abfd, entry); entry += 8; break; case DW_FORM_ref_sig8: ull = read_8_bytes (abfd, entry); entry += 8; break; default: complaint (_("Unsupported .debug_names form %s [in module %s]"), dwarf_form_name (attr.form), bfd_get_filename (abfd)); return nullptr; } switch (attr.dw_idx) { case DW_IDX_compile_unit: { /* Don't crash on bad data. */ if (ull >= per_objfile->per_bfd->all_comp_units.size ()) { complaint (_(".debug_names entry has bad CU index %s" " [in module %s]"), pulongest (ull), bfd_get_filename (abfd)); continue; } } per_cu = per_objfile->per_bfd->get_cu (ull); break; case DW_IDX_type_unit: /* Don't crash on bad data. */ if (ull >= per_objfile->per_bfd->all_type_units.size ()) { complaint (_(".debug_names entry has bad TU index %s" " [in module %s]"), pulongest (ull), bfd_get_filename (abfd)); continue; } { int nr_cus = per_objfile->per_bfd->all_comp_units.size (); per_cu = per_objfile->per_bfd->get_cu (nr_cus + ull); } break; case DW_IDX_die_offset: die_offset = sect_offset (ull); /* In a per-CU index (as opposed to a per-module index), index entries without CU attribute implicitly refer to the single CU. */ if (per_cu == NULL) per_cu = per_objfile->per_bfd->get_cu (0); break; case DW_IDX_parent: parent = ull; break; case DW_IDX_GNU_internal: if (augmentation_is_gdb && ull != 0) flags |= IS_STATIC; break; case DW_IDX_GNU_main: if (augmentation_is_gdb && ull != 0) flags |= IS_MAIN; break; case DW_IDX_GNU_language: if (augmentation_is_gdb) lang = dwarf_lang_to_enum_language (ull); break; case DW_IDX_GNU_linkage_name: if (augmentation_is_gdb && ull != 0) flags |= IS_LINKAGE; break; } } /* Skip if we couldn't find a valid CU/TU index. */ if (per_cu != nullptr) *result = shard->add (die_offset, (dwarf_tag) indexval.dwarf_tag, flags, lang, name, nullptr, per_cu); return entry; } /* Scan all the entries for NAME, at name slot INDEX. */ void mapped_debug_names_reader::scan_entries (uint32_t index, const char *name, const gdb_byte *entry) { std::vector these_entries; while (true) { std::optional parent; cooked_index_entry *this_entry; entry = scan_one_entry (name, entry, &this_entry, parent); if (entry == nullptr) break; these_entries.push_back (this_entry); if (parent.has_value ()) needs_parent.emplace_back (this_entry, *parent); } all_entries[index] = std::move (these_entries); } /* Scan the name table and create all the entries. */ void mapped_debug_names_reader::scan_all_names () { all_entries.resize (name_count); /* In the first pass, create all the entries. */ for (uint32_t i = 0; i < name_count; ++i) { const ULONGEST namei_string_offs = extract_unsigned_integer ((name_table_string_offs_reordered + i * offset_size), offset_size, dwarf5_byte_order); const char *name = read_indirect_string_at_offset (per_objfile, namei_string_offs); const ULONGEST namei_entry_offs = extract_unsigned_integer ((name_table_entry_offs_reordered + i * offset_size), offset_size, dwarf5_byte_order); const gdb_byte *entry = entry_pool + namei_entry_offs; scan_entries (i, name, entry); } /* Now update the parent pointers for all entries. This has to be done in a funny way because DWARF specifies the parent entry to point to a name -- but we don't know which specific one. */ for (auto [entry, parent_idx] : needs_parent) { /* Name entries are indexed from 1 in DWARF. */ std::vector &entries = all_entries[parent_idx - 1]; for (const auto &parent : entries) if (parent->lang == entry->lang) { entry->set_parent (parent); break; } } } /* A reader for .debug_names. */ struct cooked_index_debug_names : public cooked_index_worker { cooked_index_debug_names (dwarf2_per_objfile *per_objfile, mapped_debug_names_reader &&map) : cooked_index_worker (per_objfile), m_map (std::move (map)) { } void do_reading () override; mapped_debug_names_reader m_map; }; void cooked_index_debug_names::do_reading () { complaint_interceptor complaint_handler; std::vector exceptions; try { m_map.scan_all_names (); } catch (const gdb_exception &exc) { exceptions.push_back (std::move (exc)); } dwarf2_per_bfd *per_bfd = m_per_objfile->per_bfd; per_bfd->quick_file_names_table = create_quick_file_names_table (per_bfd->all_units.size ()); m_results.emplace_back (nullptr, complaint_handler.release (), std::move (exceptions), parent_map ()); std::vector> indexes; indexes.push_back (std::move (m_map.shard)); cooked_index *table = (gdb::checked_static_cast (per_bfd->index_table.get ())); /* Note that this code never uses IS_PARENT_DEFERRED, so it is safe to pass nullptr here. */ table->set_contents (std::move (indexes), &m_warnings, nullptr); bfd_thread_cleanup (); } /* Check the signatured type hash table from .debug_names. */ static bool check_signatured_type_table_from_debug_names (dwarf2_per_objfile *per_objfile, const mapped_debug_names_reader &map, struct dwarf2_section_info *section) { struct objfile *objfile = per_objfile->objfile; dwarf2_per_bfd *per_bfd = per_objfile->per_bfd; int nr_cus = per_bfd->all_comp_units.size (); int nr_cus_tus = per_bfd->all_units.size (); section->read (objfile); uint32_t j = nr_cus; for (uint32_t i = 0; i < map.tu_count; ++i) { sect_offset sect_off = (sect_offset) (extract_unsigned_integer (map.tu_table_reordered + i * map.offset_size, map.offset_size, map.dwarf5_byte_order)); bool found = false; for (; j < nr_cus_tus; j++) if (per_bfd->get_cu (j)->sect_off == sect_off) { found = true; break; } if (!found) { warning (_("Section .debug_names has incorrect entry in TU table," " ignoring .debug_names.")); return false; } per_bfd->all_comp_units_index_tus.push_back (per_bfd->get_cu (j)); } return true; } /* DWARF-5 debug_names reader. */ /* The old, no-longer-supported GDB augmentation. */ static const gdb_byte old_gdb_augmentation[] = { 'G', 'D', 'B', 0 }; static_assert (sizeof (old_gdb_augmentation) % 4 == 0); /* DWARF-5 augmentation string for GDB's DW_IDX_GNU_* extension. This must have a size that is a multiple of 4. */ const gdb_byte dwarf5_augmentation[8] = { 'G', 'D', 'B', '2', 0, 0, 0, 0 }; static_assert (sizeof (dwarf5_augmentation) % 4 == 0); /* A helper function that reads the .debug_names section in SECTION and fills in MAP. FILENAME is the name of the file containing the section; it is used for error reporting. Returns true if all went well, false otherwise. */ static bool read_debug_names_from_section (dwarf2_per_objfile *per_objfile, const char *filename, struct dwarf2_section_info *section, mapped_debug_names_reader &map) { struct objfile *objfile = per_objfile->objfile; if (section->empty ()) return false; /* Older elfutils strip versions could keep the section in the main executable while splitting it for the separate debug info file. */ if ((section->get_flags () & SEC_HAS_CONTENTS) == 0) return false; section->read (objfile); map.per_objfile = per_objfile; map.dwarf5_byte_order = gdbarch_byte_order (objfile->arch ()); const gdb_byte *addr = section->buffer; bfd *abfd = section->get_bfd_owner (); map.abfd = abfd; unsigned int bytes_read; LONGEST length = read_initial_length (abfd, addr, &bytes_read); addr += bytes_read; map.dwarf5_is_dwarf64 = bytes_read != 4; map.offset_size = map.dwarf5_is_dwarf64 ? 8 : 4; if (bytes_read + length != section->size) { /* There may be multiple per-CU indices. */ warning (_("Section .debug_names in %s length %s does not match " "section length %s, ignoring .debug_names."), filename, plongest (bytes_read + length), pulongest (section->size)); return false; } /* The version number. */ uint16_t version = read_2_bytes (abfd, addr); addr += 2; if (version != 5) { warning (_("Section .debug_names in %s has unsupported version %d, " "ignoring .debug_names."), filename, version); return false; } /* Padding. */ uint16_t padding = read_2_bytes (abfd, addr); addr += 2; if (padding != 0) { warning (_("Section .debug_names in %s has unsupported padding %d, " "ignoring .debug_names."), filename, padding); return false; } /* comp_unit_count - The number of CUs in the CU list. */ map.cu_count = read_4_bytes (abfd, addr); addr += 4; /* local_type_unit_count - The number of TUs in the local TU list. */ map.tu_count = read_4_bytes (abfd, addr); addr += 4; /* foreign_type_unit_count - The number of TUs in the foreign TU list. */ uint32_t foreign_tu_count = read_4_bytes (abfd, addr); addr += 4; if (foreign_tu_count != 0) { warning (_("Section .debug_names in %s has unsupported %lu foreign TUs, " "ignoring .debug_names."), filename, static_cast (foreign_tu_count)); return false; } /* bucket_count - The number of hash buckets in the hash lookup table. */ map.bucket_count = read_4_bytes (abfd, addr); addr += 4; /* name_count - The number of unique names in the index. */ map.name_count = read_4_bytes (abfd, addr); addr += 4; /* abbrev_table_size - The size in bytes of the abbreviations table. */ uint32_t abbrev_table_size = read_4_bytes (abfd, addr); addr += 4; /* augmentation_string_size - The size in bytes of the augmentation string. This value is rounded up to a multiple of 4. */ uint32_t augmentation_string_size = read_4_bytes (abfd, addr); addr += 4; augmentation_string_size += (-augmentation_string_size) & 3; if (augmentation_string_size == sizeof (old_gdb_augmentation) && memcmp (addr, old_gdb_augmentation, sizeof (old_gdb_augmentation)) == 0) { warning (_(".debug_names created by an old version of gdb; ignoring")); return false; } map.augmentation_is_gdb = ((augmentation_string_size == sizeof (dwarf5_augmentation)) && memcmp (addr, dwarf5_augmentation, sizeof (dwarf5_augmentation)) == 0); if (!map.augmentation_is_gdb) { warning (_(".debug_names not created by gdb; ignoring")); return false; } addr += augmentation_string_size; /* List of CUs */ map.cu_table_reordered = addr; addr += map.cu_count * map.offset_size; /* List of Local TUs */ map.tu_table_reordered = addr; addr += map.tu_count * map.offset_size; /* Hash Lookup Table */ map.bucket_table_reordered = reinterpret_cast (addr); addr += map.bucket_count * 4; map.hash_table_reordered = reinterpret_cast (addr); if (map.bucket_count != 0) addr += map.name_count * 4; /* Name Table */ map.name_table_string_offs_reordered = addr; addr += map.name_count * map.offset_size; map.name_table_entry_offs_reordered = addr; addr += map.name_count * map.offset_size; const gdb_byte *abbrev_table_start = addr; for (;;) { const ULONGEST index_num = read_unsigned_leb128 (abfd, addr, &bytes_read); addr += bytes_read; if (index_num == 0) break; const auto insertpair = map.abbrev_map.emplace (index_num, mapped_debug_names_reader::index_val ()); if (!insertpair.second) { warning (_("Section .debug_names in %s has duplicate index %s, " "ignoring .debug_names."), filename, pulongest (index_num)); return false; } mapped_debug_names_reader::index_val &indexval = insertpair.first->second; indexval.dwarf_tag = read_unsigned_leb128 (abfd, addr, &bytes_read); addr += bytes_read; for (;;) { mapped_debug_names_reader::index_val::attr attr; attr.dw_idx = read_unsigned_leb128 (abfd, addr, &bytes_read); addr += bytes_read; attr.form = read_unsigned_leb128 (abfd, addr, &bytes_read); addr += bytes_read; if (attr.form == DW_FORM_implicit_const) { attr.implicit_const = read_signed_leb128 (abfd, addr, &bytes_read); addr += bytes_read; } if (attr.dw_idx == 0 && attr.form == 0) break; indexval.attr_vec.push_back (std::move (attr)); } } if (addr != abbrev_table_start + abbrev_table_size) { warning (_("Section .debug_names in %s has abbreviation_table " "of size %s vs. written as %u, ignoring .debug_names."), filename, plongest (addr - abbrev_table_start), abbrev_table_size); return false; } map.entry_pool = addr; return true; } /* A helper for check_cus_from_debug_names that handles the MAP's CU list. */ static bool check_cus_from_debug_names_list (dwarf2_per_bfd *per_bfd, const mapped_debug_names_reader &map, dwarf2_section_info §ion, bool is_dwz) { int nr_cus = per_bfd->all_comp_units.size (); if (!map.augmentation_is_gdb) { uint32_t j = 0; for (uint32_t i = 0; i < map.cu_count; ++i) { sect_offset sect_off = (sect_offset) (extract_unsigned_integer (map.cu_table_reordered + i * map.offset_size, map.offset_size, map.dwarf5_byte_order)); bool found = false; for (; j < nr_cus; j++) if (per_bfd->get_cu (j)->sect_off == sect_off) { found = true; break; } if (!found) { warning (_("Section .debug_names has incorrect entry in CU table," " ignoring .debug_names.")); return false; } per_bfd->all_comp_units_index_cus.push_back (per_bfd->get_cu (j)); } return true; } if (map.cu_count != nr_cus) { warning (_("Section .debug_names has incorrect number of CUs in CU table," " ignoring .debug_names.")); return false; } for (uint32_t i = 0; i < map.cu_count; ++i) { sect_offset sect_off = (sect_offset) (extract_unsigned_integer (map.cu_table_reordered + i * map.offset_size, map.offset_size, map.dwarf5_byte_order)); if (sect_off != per_bfd->get_cu (i)->sect_off) { warning (_("Section .debug_names has incorrect entry in CU table," " ignoring .debug_names.")); return false; } } return true; } /* Read the CU list from the mapped index, and use it to create all the CU objects for this dwarf2_per_objfile. */ static bool check_cus_from_debug_names (dwarf2_per_bfd *per_bfd, const mapped_debug_names_reader &map, const mapped_debug_names_reader &dwz_map) { if (!check_cus_from_debug_names_list (per_bfd, map, per_bfd->info, false /* is_dwz */)) return false; if (dwz_map.cu_count == 0) return true; dwz_file *dwz = dwarf2_get_dwz_file (per_bfd); return check_cus_from_debug_names_list (per_bfd, dwz_map, dwz->info, true /* is_dwz */); } /* This does all the work for dwarf2_read_debug_names, but putting it into a separate function makes some cleanup a bit simpler. */ static bool do_dwarf2_read_debug_names (dwarf2_per_objfile *per_objfile) { mapped_debug_names_reader map; mapped_debug_names_reader dwz_map; struct objfile *objfile = per_objfile->objfile; dwarf2_per_bfd *per_bfd = per_objfile->per_bfd; if (!read_debug_names_from_section (per_objfile, objfile_name (objfile), &per_bfd->debug_names, map)) return false; /* Don't use the index if it's empty. */ if (map.name_count == 0) return false; /* If there is a .dwz file, read it so we can get its CU list as well. */ dwz_file *dwz = dwarf2_get_dwz_file (per_bfd); if (dwz != NULL) { if (!read_debug_names_from_section (per_objfile, bfd_get_filename (dwz->dwz_bfd.get ()), &dwz->debug_names, dwz_map)) { warning (_("could not read '.debug_names' section from %s; skipping"), bfd_get_filename (dwz->dwz_bfd.get ())); return false; } } create_all_units (per_objfile); if (!check_cus_from_debug_names (per_bfd, map, dwz_map)) return false; if (map.tu_count != 0) { /* We can only handle a single .debug_types when we have an index. */ if (per_bfd->types.size () > 1) return false; dwarf2_section_info *section = (per_bfd->types.size () == 1 ? &per_bfd->types[0] : &per_bfd->info); if (!check_signatured_type_table_from_debug_names (per_objfile, map, section)) return false; } per_bfd->debug_aranges.read (per_objfile->objfile); addrmap_mutable addrmap; deferred_warnings warnings; read_addrmap_from_aranges (per_objfile, &per_bfd->debug_aranges, &addrmap, &warnings); warnings.emit (); map.shard = std::make_unique (); map.shard->install_addrmap (&addrmap); cooked_index *idx = new debug_names_index (per_objfile, (std::make_unique (per_objfile, std::move (map)))); per_bfd->index_table.reset (idx); idx->start_reading (); return true; } /* See read-debug-names.h. */ bool dwarf2_read_debug_names (dwarf2_per_objfile *per_objfile) { bool result = do_dwarf2_read_debug_names (per_objfile); if (!result) per_objfile->per_bfd->all_units.clear (); return result; }