compiler/elf_writer_quick.cc - platform/art - Git at Google

 /*
  * Copyright (C) 2012 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.
  */

 #include "elf_writer_quick.h"

 #include <unordered_map>
 #include <unordered_set>

 #include "base/logging.h"
 #include "base/unix_file/fd_file.h"
 #include "buffered_output_stream.h"
 #include "compiled_method.h"
 #include "dex_file-inl.h"
 #include "driver/compiler_driver.h"
 #include "driver/compiler_options.h"
 #include "elf_builder.h"
 #include "elf_file.h"
 #include "elf_utils.h"
 #include "elf_writer_debug.h"
 #include "file_output_stream.h"
 #include "globals.h"
 #include "leb128.h"
 #include "oat.h"
 #include "oat_writer.h"
 #include "utils.h"

 namespace art {

 template <typename ElfTypes>
 bool ElfWriterQuick<ElfTypes>::Create(File* elf_file,
                                       OatWriter* oat_writer,
                                       const std::vector<const DexFile*>& dex_files,
                                       const std::string& android_root,
                                       bool is_host,
                                       const CompilerDriver& driver) {
   ElfWriterQuick elf_writer(driver, elf_file);
   return elf_writer.Write(oat_writer, dex_files, android_root, is_host);
 }

 class OatWriterWrapper FINAL : public CodeOutput {
  public:
   explicit OatWriterWrapper(OatWriter* oat_writer) : oat_writer_(oat_writer) {}

   void SetCodeOffset(size_t offset) {
     oat_writer_->SetOatDataOffset(offset);
   }
   bool Write(OutputStream* out) OVERRIDE {
     return oat_writer_->Write(out);
   }
  private:
   OatWriter* const oat_writer_;
 };

 template <typename ElfTypes>
 static void WriteDebugSymbols(ElfBuilder<ElfTypes>* builder, OatWriter* oat_writer);

 // Encode patch locations in .oat_patches format.
 template <typename ElfTypes>
 void ElfWriterQuick<ElfTypes>::EncodeOatPatches(
     const OatWriter::PatchLocationsMap& sections,
     std::vector<uint8_t>* buffer) {
   for (const auto& section : sections) {
     const std::string& name = section.first;
     std::vector<uintptr_t>* locations = section.second.get();
     DCHECK(!name.empty());
     std::sort(locations->begin(), locations->end());
     // Reserve buffer space - guess 2 bytes per ULEB128.
     buffer->reserve(buffer->size() + name.size() + locations->size() * 2);
     // Write null-terminated section name.
     const uint8_t* name_data = reinterpret_cast<const uint8_t*>(name.c_str());
     buffer->insert(buffer->end(), name_data, name_data + name.size() + 1);
     // Write placeholder for data length.
     size_t length_pos = buffer->size();
     EncodeUnsignedLeb128(buffer, UINT32_MAX);
     // Write LEB128 encoded list of advances (deltas between consequtive addresses).
     size_t data_pos = buffer->size();
     uintptr_t address = 0;  // relative to start of section.
     for (uintptr_t location : *locations) {
       DCHECK_LT(location - address, UINT32_MAX) << "Large gap between patch locations";
       EncodeUnsignedLeb128(buffer, location - address);
       address = location;
     }
     // Update length.
     UpdateUnsignedLeb128(buffer->data() + length_pos, buffer->size() - data_pos);
   }
   buffer->push_back(0);  // End of sections.
 }

 template<typename AddressType, bool SubtractPatchLocation = false>
 static void PatchAddresses(const std::vector<uintptr_t>* patch_locations,
                            AddressType delta, std::vector<uint8_t>* buffer) {
   // Addresses in .debug_* sections are unaligned.
   typedef __attribute__((__aligned__(1))) AddressType UnalignedAddressType;
   if (patch_locations != nullptr) {
     for (uintptr_t patch_location : *patch_locations) {
       *reinterpret_cast<UnalignedAddressType*>(buffer->data() + patch_location) +=
           delta - (SubtractPatchLocation ? patch_location : 0);
     }
   }
 }

 template <typename ElfTypes>
 bool ElfWriterQuick<ElfTypes>::Write(
     OatWriter* oat_writer,
     const std::vector<const DexFile*>& dex_files_unused ATTRIBUTE_UNUSED,
     const std::string& android_root_unused ATTRIBUTE_UNUSED,
     bool is_host_unused ATTRIBUTE_UNUSED) {
   constexpr bool debug = false;
   const OatHeader& oat_header = oat_writer->GetOatHeader();
   typename ElfTypes::Word oat_data_size = oat_header.GetExecutableOffset();
   uint32_t oat_exec_size = oat_writer->GetSize() - oat_data_size;
   uint32_t oat_bss_size = oat_writer->GetBssSize();

   OatWriterWrapper wrapper(oat_writer);

   std::unique_ptr<ElfBuilder<ElfTypes>> builder(new ElfBuilder<ElfTypes>(
       &wrapper,
       elf_file_,
       compiler_driver_->GetInstructionSet(),
       0,
       oat_data_size,
       oat_data_size,
       oat_exec_size,
       RoundUp(oat_data_size + oat_exec_size, kPageSize),
       oat_bss_size,
       compiler_driver_->GetCompilerOptions().GetIncludeDebugSymbols(),
       debug));

   InstructionSet isa = compiler_driver_->GetInstructionSet();
   int alignment = GetInstructionSetPointerSize(isa);
   typedef ElfRawSectionBuilder<ElfTypes> RawSection;
   RawSection eh_frame(".eh_frame", SHT_PROGBITS, SHF_ALLOC, nullptr, 0, alignment, 0);
   RawSection eh_frame_hdr(".eh_frame_hdr", SHT_PROGBITS, SHF_ALLOC, nullptr, 0, 4, 0);
   RawSection debug_info(".debug_info", SHT_PROGBITS, 0, nullptr, 0, 1, 0);
   RawSection debug_abbrev(".debug_abbrev", SHT_PROGBITS, 0, nullptr, 0, 1, 0);
   RawSection debug_str(".debug_str", SHT_PROGBITS, 0, nullptr, 0, 1, 0);
   RawSection debug_line(".debug_line", SHT_PROGBITS, 0, nullptr, 0, 1, 0);
   RawSection oat_patches(".oat_patches", SHT_OAT_PATCH, 0, nullptr, 0, 1, 0);

   // Do not add to .oat_patches since we will make the addresses relative.
   std::vector<uintptr_t> eh_frame_patches;
   if (compiler_driver_->GetCompilerOptions().GetIncludeCFI() &&
       !oat_writer->GetMethodDebugInfo().empty()) {
     dwarf::WriteEhFrame(compiler_driver_, oat_writer,
                         dwarf::DW_EH_PE_pcrel,
                         eh_frame.GetBuffer(), &eh_frame_patches,
                         eh_frame_hdr.GetBuffer());
     builder->RegisterRawSection(&eh_frame);
     builder->RegisterRawSection(&eh_frame_hdr);
   }

   // Must be done after .eh_frame is created since it is used in the Elf layout.
   if (!builder->Init()) {
     return false;
   }

   std::vector<uintptr_t>* debug_info_patches = nullptr;
   std::vector<uintptr_t>* debug_line_patches = nullptr;
   if (compiler_driver_->GetCompilerOptions().GetIncludeDebugSymbols() &&
       !oat_writer->GetMethodDebugInfo().empty()) {
     // Add methods to .symtab.
     WriteDebugSymbols(builder.get(), oat_writer);
     // Generate DWARF .debug_* sections.
     debug_info_patches = oat_writer->GetAbsolutePatchLocationsFor(".debug_info");
     debug_line_patches = oat_writer->GetAbsolutePatchLocationsFor(".debug_line");
     dwarf::WriteDebugSections(compiler_driver_, oat_writer,
                               debug_info.GetBuffer(), debug_info_patches,
                               debug_abbrev.GetBuffer(),
                               debug_str.GetBuffer(),
                               debug_line.GetBuffer(), debug_line_patches);
     builder->RegisterRawSection(&debug_info);
     builder->RegisterRawSection(&debug_abbrev);
     builder->RegisterRawSection(&debug_str);
     builder->RegisterRawSection(&debug_line);
   }

   if (compiler_driver_->GetCompilerOptions().GetIncludePatchInformation() ||
       // ElfWriter::Fixup will be called regardless and it needs to be able
       // to patch debug sections so we have to include patches for them.
       compiler_driver_->GetCompilerOptions().GetIncludeDebugSymbols()) {
     EncodeOatPatches(oat_writer->GetAbsolutePatchLocations(), oat_patches.GetBuffer());
     builder->RegisterRawSection(&oat_patches);
   }

   // We know where .text and .eh_frame will be located, so patch the addresses.
   typename ElfTypes::Addr text_addr = builder->GetTextBuilder().GetSection()->sh_addr;
   // TODO: Simplify once we use Elf64 - we can use ElfTypes::Addr instead of branching.
   if (Is64BitInstructionSet(compiler_driver_->GetInstructionSet())) {
     // relative_address = (text_addr + address) - (eh_frame_addr + patch_location);
     PatchAddresses<uint64_t, true>(&eh_frame_patches,
         text_addr - eh_frame.GetSection()->sh_addr, eh_frame.GetBuffer());
     PatchAddresses<uint64_t>(debug_info_patches, text_addr, debug_info.GetBuffer());
     PatchAddresses<uint64_t>(debug_line_patches, text_addr, debug_line.GetBuffer());
   } else {
     // relative_address = (text_addr + address) - (eh_frame_addr + patch_location);
     PatchAddresses<uint32_t, true>(&eh_frame_patches,
         text_addr - eh_frame.GetSection()->sh_addr, eh_frame.GetBuffer());
     PatchAddresses<uint32_t>(debug_info_patches, text_addr, debug_info.GetBuffer());
     PatchAddresses<uint32_t>(debug_line_patches, text_addr, debug_line.GetBuffer());
   }

   return builder->Write();
 }

 template <typename ElfTypes>
 // Do not inline to avoid Clang stack frame problems. b/18738594
 NO_INLINE
 static void WriteDebugSymbols(ElfBuilder<ElfTypes>* builder, OatWriter* oat_writer) {
   const std::vector<OatWriter::DebugInfo>& method_info = oat_writer->GetMethodDebugInfo();

   // Find all addresses (low_pc) which contain deduped methods.
   // The first instance of method is not marked deduped_, but the rest is.
   std::unordered_set<uint32_t> deduped_addresses;
   for (auto it = method_info.begin(); it != method_info.end(); ++it) {
     if (it->deduped_) {
       deduped_addresses.insert(it->low_pc_);
     }
   }

   ElfSymtabBuilder<ElfTypes>* symtab = builder->GetSymtabBuilder();
   for (auto it = method_info.begin(); it != method_info.end(); ++it) {
     std::string name = PrettyMethod(it->dex_method_index_, *it->dex_file_, true);
     if (deduped_addresses.find(it->low_pc_) != deduped_addresses.end()) {
       name += " [DEDUPED]";
     }

     uint32_t low_pc = it->low_pc_;
     // Add in code delta, e.g., thumb bit 0 for Thumb2 code.
     low_pc += it->compiled_method_->CodeDelta();
     symtab->AddSymbol(name, &builder->GetTextBuilder(), low_pc,
                       true, it->high_pc_ - it->low_pc_, STB_GLOBAL, STT_FUNC);

     // Conforming to aaelf, add $t mapping symbol to indicate start of a sequence of thumb2
     // instructions, so that disassembler tools can correctly disassemble.
     if (it->compiled_method_->GetInstructionSet() == kThumb2) {
       symtab->AddSymbol("$t", &builder->GetTextBuilder(), it->low_pc_ & ~1, true,
                         0, STB_LOCAL, STT_NOTYPE);
     }
   }
 }

 // Explicit instantiations
 template class ElfWriterQuick<ElfTypes32>;
 template class ElfWriterQuick<ElfTypes64>;

 }  // namespace art
	/*
	* Copyright (C) 2012 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.
	*/

	#include "elf_writer_quick.h"

	#include <unordered_map>
	#include <unordered_set>

	#include "base/logging.h"
	#include "base/unix_file/fd_file.h"
	#include "buffered_output_stream.h"
	#include "compiled_method.h"
	#include "dex_file-inl.h"
	#include "driver/compiler_driver.h"
	#include "driver/compiler_options.h"
	#include "elf_builder.h"
	#include "elf_file.h"
	#include "elf_utils.h"
	#include "elf_writer_debug.h"
	#include "file_output_stream.h"
	#include "globals.h"
	#include "leb128.h"
	#include "oat.h"
	#include "oat_writer.h"
	#include "utils.h"

	namespace art {

	template <typename ElfTypes>
	bool ElfWriterQuick<ElfTypes>::Create(File* elf_file,
	OatWriter* oat_writer,
	const std::vector<const DexFile*>& dex_files,
	const std::string& android_root,
	bool is_host,
	const CompilerDriver& driver) {
	ElfWriterQuick elf_writer(driver, elf_file);
	return elf_writer.Write(oat_writer, dex_files, android_root, is_host);
	}

	class OatWriterWrapper FINAL : public CodeOutput {
	public:
	explicit OatWriterWrapper(OatWriter* oat_writer) : oat_writer_(oat_writer) {}

	void SetCodeOffset(size_t offset) {
	oat_writer_->SetOatDataOffset(offset);
	}
	bool Write(OutputStream* out) OVERRIDE {
	return oat_writer_->Write(out);
	}
	private:
	OatWriter* const oat_writer_;
	};

	template <typename ElfTypes>
	static void WriteDebugSymbols(ElfBuilder<ElfTypes>* builder, OatWriter* oat_writer);

	// Encode patch locations in .oat_patches format.
	template <typename ElfTypes>
	void ElfWriterQuick<ElfTypes>::EncodeOatPatches(
	const OatWriter::PatchLocationsMap& sections,
	std::vector<uint8_t>* buffer) {
	for (const auto& section : sections) {
	const std::string& name = section.first;
	std::vector<uintptr_t>* locations = section.second.get();
	DCHECK(!name.empty());
	std::sort(locations->begin(), locations->end());
	// Reserve buffer space - guess 2 bytes per ULEB128.
	buffer->reserve(buffer->size() + name.size() + locations->size() * 2);
	// Write null-terminated section name.
	const uint8_t* name_data = reinterpret_cast<const uint8_t*>(name.c_str());
	buffer->insert(buffer->end(), name_data, name_data + name.size() + 1);
	// Write placeholder for data length.
	size_t length_pos = buffer->size();
	EncodeUnsignedLeb128(buffer, UINT32_MAX);
	// Write LEB128 encoded list of advances (deltas between consequtive addresses).
	size_t data_pos = buffer->size();
	uintptr_t address = 0; // relative to start of section.
	for (uintptr_t location : *locations) {
	DCHECK_LT(location - address, UINT32_MAX) << "Large gap between patch locations";
	EncodeUnsignedLeb128(buffer, location - address);
	address = location;
	}
	// Update length.
	UpdateUnsignedLeb128(buffer->data() + length_pos, buffer->size() - data_pos);
	}
	buffer->push_back(0); // End of sections.
	}

	template<typename AddressType, bool SubtractPatchLocation = false>
	static void PatchAddresses(const std::vector<uintptr_t>* patch_locations,
	AddressType delta, std::vector<uint8_t>* buffer) {
	// Addresses in .debug_* sections are unaligned.
	typedef __attribute__((__aligned__(1))) AddressType UnalignedAddressType;
	if (patch_locations != nullptr) {
	for (uintptr_t patch_location : *patch_locations) {
	reinterpret_cast<UnalignedAddressType>(buffer->data() + patch_location) +=
	delta - (SubtractPatchLocation ? patch_location : 0);
	}
	}
	}

	template <typename ElfTypes>
	bool ElfWriterQuick<ElfTypes>::Write(
	OatWriter* oat_writer,
	const std::vector<const DexFile*>& dex_files_unused ATTRIBUTE_UNUSED,
	const std::string& android_root_unused ATTRIBUTE_UNUSED,
	bool is_host_unused ATTRIBUTE_UNUSED) {
	constexpr bool debug = false;
	const OatHeader& oat_header = oat_writer->GetOatHeader();
	typename ElfTypes::Word oat_data_size = oat_header.GetExecutableOffset();
	uint32_t oat_exec_size = oat_writer->GetSize() - oat_data_size;
	uint32_t oat_bss_size = oat_writer->GetBssSize();

	OatWriterWrapper wrapper(oat_writer);

	std::unique_ptr<ElfBuilder<ElfTypes>> builder(new ElfBuilder<ElfTypes>(
	&wrapper,
	elf_file_,
	compiler_driver_->GetInstructionSet(),
	0,
	oat_data_size,
	oat_data_size,
	oat_exec_size,
	RoundUp(oat_data_size + oat_exec_size, kPageSize),
	oat_bss_size,
	compiler_driver_->GetCompilerOptions().GetIncludeDebugSymbols(),
	debug));

	InstructionSet isa = compiler_driver_->GetInstructionSet();
	int alignment = GetInstructionSetPointerSize(isa);
	typedef ElfRawSectionBuilder<ElfTypes> RawSection;
	RawSection eh_frame(".eh_frame", SHT_PROGBITS, SHF_ALLOC, nullptr, 0, alignment, 0);
	RawSection eh_frame_hdr(".eh_frame_hdr", SHT_PROGBITS, SHF_ALLOC, nullptr, 0, 4, 0);
	RawSection debug_info(".debug_info", SHT_PROGBITS, 0, nullptr, 0, 1, 0);
	RawSection debug_abbrev(".debug_abbrev", SHT_PROGBITS, 0, nullptr, 0, 1, 0);
	RawSection debug_str(".debug_str", SHT_PROGBITS, 0, nullptr, 0, 1, 0);
	RawSection debug_line(".debug_line", SHT_PROGBITS, 0, nullptr, 0, 1, 0);
	RawSection oat_patches(".oat_patches", SHT_OAT_PATCH, 0, nullptr, 0, 1, 0);

	// Do not add to .oat_patches since we will make the addresses relative.
	std::vector<uintptr_t> eh_frame_patches;
	if (compiler_driver_->GetCompilerOptions().GetIncludeCFI() &&
	!oat_writer->GetMethodDebugInfo().empty()) {
	dwarf::WriteEhFrame(compiler_driver_, oat_writer,
	dwarf::DW_EH_PE_pcrel,
	eh_frame.GetBuffer(), &eh_frame_patches,
	eh_frame_hdr.GetBuffer());
	builder->RegisterRawSection(&eh_frame);
	builder->RegisterRawSection(&eh_frame_hdr);
	}

	// Must be done after .eh_frame is created since it is used in the Elf layout.
	if (!builder->Init()) {
	return false;
	}

	std::vector<uintptr_t>* debug_info_patches = nullptr;
	std::vector<uintptr_t>* debug_line_patches = nullptr;
	if (compiler_driver_->GetCompilerOptions().GetIncludeDebugSymbols() &&
	!oat_writer->GetMethodDebugInfo().empty()) {
	// Add methods to .symtab.
	WriteDebugSymbols(builder.get(), oat_writer);
	// Generate DWARF .debug_* sections.
	debug_info_patches = oat_writer->GetAbsolutePatchLocationsFor(".debug_info");
	debug_line_patches = oat_writer->GetAbsolutePatchLocationsFor(".debug_line");
	dwarf::WriteDebugSections(compiler_driver_, oat_writer,
	debug_info.GetBuffer(), debug_info_patches,
	debug_abbrev.GetBuffer(),
	debug_str.GetBuffer(),
	debug_line.GetBuffer(), debug_line_patches);
	builder->RegisterRawSection(&debug_info);
	builder->RegisterRawSection(&debug_abbrev);
	builder->RegisterRawSection(&debug_str);
	builder->RegisterRawSection(&debug_line);
	}

	if (compiler_driver_->GetCompilerOptions().GetIncludePatchInformation() \|\|
	// ElfWriter::Fixup will be called regardless and it needs to be able
	// to patch debug sections so we have to include patches for them.
	compiler_driver_->GetCompilerOptions().GetIncludeDebugSymbols()) {
	EncodeOatPatches(oat_writer->GetAbsolutePatchLocations(), oat_patches.GetBuffer());
	builder->RegisterRawSection(&oat_patches);
	}

	// We know where .text and .eh_frame will be located, so patch the addresses.
	typename ElfTypes::Addr text_addr = builder->GetTextBuilder().GetSection()->sh_addr;
	// TODO: Simplify once we use Elf64 - we can use ElfTypes::Addr instead of branching.
	if (Is64BitInstructionSet(compiler_driver_->GetInstructionSet())) {
	// relative_address = (text_addr + address) - (eh_frame_addr + patch_location);
	PatchAddresses<uint64_t, true>(&eh_frame_patches,
	text_addr - eh_frame.GetSection()->sh_addr, eh_frame.GetBuffer());
	PatchAddresses<uint64_t>(debug_info_patches, text_addr, debug_info.GetBuffer());
	PatchAddresses<uint64_t>(debug_line_patches, text_addr, debug_line.GetBuffer());
	} else {
	// relative_address = (text_addr + address) - (eh_frame_addr + patch_location);
	PatchAddresses<uint32_t, true>(&eh_frame_patches,
	text_addr - eh_frame.GetSection()->sh_addr, eh_frame.GetBuffer());
	PatchAddresses<uint32_t>(debug_info_patches, text_addr, debug_info.GetBuffer());
	PatchAddresses<uint32_t>(debug_line_patches, text_addr, debug_line.GetBuffer());
	}

	return builder->Write();
	}

	template <typename ElfTypes>
	// Do not inline to avoid Clang stack frame problems. b/18738594
	NO_INLINE
	static void WriteDebugSymbols(ElfBuilder<ElfTypes>* builder, OatWriter* oat_writer) {
	const std::vector<OatWriter::DebugInfo>& method_info = oat_writer->GetMethodDebugInfo();

	// Find all addresses (low_pc) which contain deduped methods.
	// The first instance of method is not marked deduped_, but the rest is.
	std::unordered_set<uint32_t> deduped_addresses;
	for (auto it = method_info.begin(); it != method_info.end(); ++it) {
	if (it->deduped_) {
	deduped_addresses.insert(it->low_pc_);
	}
	}

	ElfSymtabBuilder<ElfTypes>* symtab = builder->GetSymtabBuilder();
	for (auto it = method_info.begin(); it != method_info.end(); ++it) {
	std::string name = PrettyMethod(it->dex_method_index_, *it->dex_file_, true);
	if (deduped_addresses.find(it->low_pc_) != deduped_addresses.end()) {
	name += " [DEDUPED]";
	}

	uint32_t low_pc = it->low_pc_;
	// Add in code delta, e.g., thumb bit 0 for Thumb2 code.
	low_pc += it->compiled_method_->CodeDelta();
	symtab->AddSymbol(name, &builder->GetTextBuilder(), low_pc,
	true, it->high_pc_ - it->low_pc_, STB_GLOBAL, STT_FUNC);

	// Conforming to aaelf, add $t mapping symbol to indicate start of a sequence of thumb2
	// instructions, so that disassembler tools can correctly disassemble.
	if (it->compiled_method_->GetInstructionSet() == kThumb2) {
	symtab->AddSymbol("$t", &builder->GetTextBuilder(), it->low_pc_ & ~1, true,
	0, STB_LOCAL, STT_NOTYPE);
	}
	}
	}

	// Explicit instantiations
	template class ElfWriterQuick<ElfTypes32>;
	template class ElfWriterQuick<ElfTypes64>;

	} // namespace art