| /* |
| * Copyright (C) 2016 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef ART_COMPILER_DEBUG_ELF_SYMTAB_WRITER_H_ |
| #define ART_COMPILER_DEBUG_ELF_SYMTAB_WRITER_H_ |
| |
| #include <map> |
| #include <unordered_set> |
| |
| #include "base/utils.h" |
| #include "debug/debug_info.h" |
| #include "debug/method_debug_info.h" |
| #include "dex/dex_file-inl.h" |
| #include "dex/code_item_accessors.h" |
| #include "linker/elf_builder.h" |
| |
| namespace art { |
| namespace debug { |
| |
| // The ARM specification defines three special mapping symbols |
| // $a, $t and $d which mark ARM, Thumb and data ranges respectively. |
| // These symbols can be used by tools, for example, to pretty |
| // print instructions correctly. Objdump will use them if they |
| // exist, but it will still work well without them. |
| // However, these extra symbols take space, so let's just generate |
| // one symbol which marks the whole .text section as code. |
| // Note that ARM's Streamline requires it to match function symbol. |
| constexpr bool kGenerateArmMappingSymbol = true; |
| |
| // Magic name for .symtab symbols which enumerate dex files used |
| // by this ELF file (currently mmapped inside the .dex section). |
| constexpr const char* kDexFileSymbolName = "$dexfile"; |
| |
| template <typename ElfTypes> |
| static void WriteDebugSymbols(linker::ElfBuilder<ElfTypes>* builder, |
| bool mini_debug_info, |
| const DebugInfo& debug_info) { |
| uint64_t mapping_symbol_address = std::numeric_limits<uint64_t>::max(); |
| const auto* text = builder->GetText(); |
| auto* strtab = builder->GetStrTab(); |
| auto* symtab = builder->GetSymTab(); |
| |
| if (debug_info.Empty()) { |
| return; |
| } |
| |
| // Find all addresses which contain deduped methods. |
| // The first instance of method is not marked deduped_, but the rest is. |
| std::unordered_set<uint64_t> deduped_addresses; |
| for (const MethodDebugInfo& info : debug_info.compiled_methods) { |
| if (info.deduped) { |
| deduped_addresses.insert(info.code_address); |
| } |
| if (kGenerateArmMappingSymbol && info.isa == InstructionSet::kThumb2) { |
| uint64_t address = info.code_address; |
| address += info.is_code_address_text_relative ? text->GetAddress() : 0; |
| mapping_symbol_address = std::min(mapping_symbol_address, address); |
| } |
| } |
| |
| strtab->Start(); |
| strtab->Write(""); // strtab should start with empty string. |
| // Generate ARM mapping symbols. ELF local symbols must be added first. |
| if (mapping_symbol_address != std::numeric_limits<uint64_t>::max()) { |
| symtab->Add(strtab->Write("$t"), text, mapping_symbol_address, 0, STB_LOCAL, STT_NOTYPE); |
| } |
| // Add symbols for compiled methods. |
| for (const MethodDebugInfo& info : debug_info.compiled_methods) { |
| if (info.deduped) { |
| continue; // Add symbol only for the first instance. |
| } |
| size_t name_offset; |
| if (!info.custom_name.empty()) { |
| name_offset = strtab->Write(info.custom_name); |
| } else { |
| DCHECK(info.dex_file != nullptr); |
| std::string name = info.dex_file->PrettyMethod(info.dex_method_index, !mini_debug_info); |
| if (deduped_addresses.find(info.code_address) != deduped_addresses.end()) { |
| name += " [DEDUPED]"; |
| } |
| name_offset = strtab->Write(name); |
| } |
| |
| uint64_t address = info.code_address; |
| address += info.is_code_address_text_relative ? text->GetAddress() : 0; |
| // Add in code delta, e.g., thumb bit 0 for Thumb2 code. |
| address += CompiledMethod::CodeDelta(info.isa); |
| symtab->Add(name_offset, text, address, info.code_size, STB_GLOBAL, STT_FUNC); |
| } |
| // Add symbols for dex files. |
| if (!debug_info.dex_files.empty() && builder->GetDex()->Exists()) { |
| auto dex = builder->GetDex(); |
| for (auto it : debug_info.dex_files) { |
| uint64_t dex_address = dex->GetAddress() + it.first /* offset within the section */; |
| const DexFile* dex_file = it.second; |
| typename ElfTypes::Word dex_name = strtab->Write(kDexFileSymbolName); |
| symtab->Add(dex_name, dex, dex_address, dex_file->Size(), STB_GLOBAL, STT_FUNC); |
| } |
| } |
| strtab->End(); |
| |
| // Symbols are buffered and written after names (because they are smaller). |
| symtab->WriteCachedSection(); |
| } |
| |
| } // namespace debug |
| } // namespace art |
| |
| #endif // ART_COMPILER_DEBUG_ELF_SYMTAB_WRITER_H_ |
| |