compiler/debug/elf_debug_frame_writer.h - LeafOS-Project/android_art - Gitiles

 /*
  * 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_DEBUG_FRAME_WRITER_H_
 #define ART_COMPILER_DEBUG_ELF_DEBUG_FRAME_WRITER_H_

 #include <vector>

 #include "arch/instruction_set.h"
 #include "base/macros.h"
 #include "debug/method_debug_info.h"
 #include "dwarf/debug_frame_opcode_writer.h"
 #include "dwarf/dwarf_constants.h"
 #include "dwarf/headers.h"
 #include "elf/elf_builder.h"

 namespace art HIDDEN {
 namespace debug {

 static constexpr bool kWriteDebugFrameHdr = false;

 // Binary search table is not useful if the number of entries is small.
 // In particular, this avoids it for the in-memory JIT mini-debug-info.
 static constexpr size_t kMinDebugFrameHdrEntries = 100;

 static void WriteCIE(InstructionSet isa, /*inout*/ std::vector<uint8_t>* buffer) {
   using Reg = dwarf::Reg;
   // Scratch registers should be marked as undefined.  This tells the
   // debugger that its value in the previous frame is not recoverable.
   bool is64bit = Is64BitInstructionSet(isa);
   switch (isa) {
     case InstructionSet::kArm:
     case InstructionSet::kThumb2: {
       dwarf::DebugFrameOpCodeWriter<> opcodes;
       opcodes.DefCFA(Reg::ArmCore(13), 0);  // R13(SP).
       // core registers.
       for (int reg = 0; reg < 13; reg++) {
         if (reg < 4 || reg == 12) {
           opcodes.Undefined(Reg::ArmCore(reg));
         } else {
           opcodes.SameValue(Reg::ArmCore(reg));
         }
       }
       // fp registers.
       for (int reg = 0; reg < 32; reg++) {
         if (reg < 16) {
           opcodes.Undefined(Reg::ArmFp(reg));
         } else {
           opcodes.SameValue(Reg::ArmFp(reg));
         }
       }
       auto return_reg = Reg::ArmCore(14);  // R14(LR).
       WriteCIE(is64bit, return_reg, opcodes, buffer);
       return;
     }
     case InstructionSet::kArm64: {
       dwarf::DebugFrameOpCodeWriter<> opcodes;
       opcodes.DefCFA(Reg::Arm64Core(31), 0);  // R31(SP).
       // core registers.
       for (int reg = 0; reg < 30; reg++) {
         if (reg < 8 || reg == 16 || reg == 17) {
           opcodes.Undefined(Reg::Arm64Core(reg));
         } else {
           opcodes.SameValue(Reg::Arm64Core(reg));
         }
       }
       // fp registers.
       for (int reg = 0; reg < 32; reg++) {
         if (reg < 8 || reg >= 16) {
           opcodes.Undefined(Reg::Arm64Fp(reg));
         } else {
           opcodes.SameValue(Reg::Arm64Fp(reg));
         }
       }
       auto return_reg = Reg::Arm64Core(30);  // R30(LR).
       WriteCIE(is64bit, return_reg, opcodes, buffer);
       return;
     }
     case InstructionSet::kRiscv64: {
       UNIMPLEMENTED(FATAL);
       return;
     }
     case InstructionSet::kX86: {
       // FIXME: Add fp registers once libunwind adds support for them. Bug: 20491296
       constexpr bool generate_opcodes_for_x86_fp = false;
       dwarf::DebugFrameOpCodeWriter<> opcodes;
       opcodes.DefCFA(Reg::X86Core(4), 4);   // R4(ESP).
       opcodes.Offset(Reg::X86Core(8), -4);  // R8(EIP).
       // core registers.
       for (int reg = 0; reg < 8; reg++) {
         if (reg <= 3) {
           opcodes.Undefined(Reg::X86Core(reg));
         } else if (reg == 4) {
           // Stack pointer.
         } else {
           opcodes.SameValue(Reg::X86Core(reg));
         }
       }
       // fp registers.
       if (generate_opcodes_for_x86_fp) {
         for (int reg = 0; reg < 8; reg++) {
           opcodes.Undefined(Reg::X86Fp(reg));
         }
       }
       auto return_reg = Reg::X86Core(8);  // R8(EIP).
       WriteCIE(is64bit, return_reg, opcodes, buffer);
       return;
     }
     case InstructionSet::kX86_64: {
       dwarf::DebugFrameOpCodeWriter<> opcodes;
       opcodes.DefCFA(Reg::X86_64Core(4), 8);  // R4(RSP).
       opcodes.Offset(Reg::X86_64Core(16), -8);  // R16(RIP).
       // core registers.
       for (int reg = 0; reg < 16; reg++) {
         if (reg == 4) {
           // Stack pointer.
         } else if (reg < 12 && reg != 3 && reg != 5) {  // except EBX and EBP.
           opcodes.Undefined(Reg::X86_64Core(reg));
         } else {
           opcodes.SameValue(Reg::X86_64Core(reg));
         }
       }
       // fp registers.
       for (int reg = 0; reg < 16; reg++) {
         if (reg < 12) {
           opcodes.Undefined(Reg::X86_64Fp(reg));
         } else {
           opcodes.SameValue(Reg::X86_64Fp(reg));
         }
       }
       auto return_reg = Reg::X86_64Core(16);  // R16(RIP).
       WriteCIE(is64bit, return_reg, opcodes, buffer);
       return;
     }
     case InstructionSet::kNone:
       break;
   }
   LOG(FATAL) << "Cannot write CIE frame for ISA " << isa;
   UNREACHABLE();
 }

 template<typename ElfTypes>
 void WriteCFISection(ElfBuilder<ElfTypes>* builder,
                      const ArrayRef<const MethodDebugInfo>& method_infos) {
   // The methods can be written in any order.
   // Let's therefore sort them in the lexicographical order of the opcodes.
   // This has no effect on its own. However, if the final .debug_frame section is
   // compressed it reduces the size since similar opcodes sequences are grouped.
   std::vector<const MethodDebugInfo*> sorted_method_infos;
   sorted_method_infos.reserve(method_infos.size());
   for (size_t i = 0; i < method_infos.size(); i++) {
     if (!method_infos[i].cfi.empty() && !method_infos[i].deduped) {
       sorted_method_infos.push_back(&method_infos[i]);
     }
   }
   if (sorted_method_infos.empty()) {
     return;
   }
   std::stable_sort(
       sorted_method_infos.begin(),
       sorted_method_infos.end(),
       [](const MethodDebugInfo* lhs, const MethodDebugInfo* rhs) {
         ArrayRef<const uint8_t> l = lhs->cfi;
         ArrayRef<const uint8_t> r = rhs->cfi;
         return std::lexicographical_compare(l.begin(), l.end(), r.begin(), r.end());
       });

   std::vector<uint32_t> binary_search_table;
   bool binary_search_table_is_valid = kWriteDebugFrameHdr;
   if (binary_search_table_is_valid) {
     binary_search_table.reserve(2 * sorted_method_infos.size());
   }

   // Write .debug_frame section.
   auto* cfi_section = builder->GetDebugFrame();
   {
     cfi_section->Start();
     const bool is64bit = Is64BitInstructionSet(builder->GetIsa());
     std::vector<uint8_t> buffer;  // Small temporary buffer.
     WriteCIE(builder->GetIsa(), &buffer);
     cfi_section->WriteFully(buffer.data(), buffer.size());
     buffer.clear();
     for (const MethodDebugInfo* mi : sorted_method_infos) {
       DCHECK(!mi->deduped);
       DCHECK(!mi->cfi.empty());
       uint64_t code_address = mi->code_address +
           (mi->is_code_address_text_relative ? builder->GetText()->GetAddress() : 0);
       if (kWriteDebugFrameHdr) {
         // Defensively check that the code address really fits.
         DCHECK_LE(code_address, std::numeric_limits<uint32_t>::max());
         binary_search_table_is_valid &= code_address <= std::numeric_limits<uint32_t>::max();
         binary_search_table.push_back(static_cast<uint32_t>(code_address));
         binary_search_table.push_back(cfi_section->GetPosition());
       }
       dwarf::WriteFDE(is64bit,
                       /* cie_pointer= */ 0,
                       code_address,
                       mi->code_size,
                       mi->cfi,
                       &buffer);
       cfi_section->WriteFully(buffer.data(), buffer.size());
       buffer.clear();
     }
     cfi_section->End();
   }

   if (binary_search_table_is_valid && method_infos.size() >= kMinDebugFrameHdrEntries) {
     std::sort(binary_search_table.begin(), binary_search_table.end());

     // Custom Android section. It is very similar to the official .eh_frame_hdr format.
     std::vector<uint8_t> header_buffer;
     dwarf::Writer<> header(&header_buffer);
     header.PushUint8(1);  // Version.
     header.PushUint8(dwarf::DW_EH_PE_omit);    // Encoding of .eh_frame pointer - none.
     header.PushUint8(dwarf::DW_EH_PE_udata4);  // Encoding of binary search table size.
     header.PushUint8(dwarf::DW_EH_PE_udata4);  // Encoding of binary search table data.
     header.PushUint32(dchecked_integral_cast<uint32_t>(binary_search_table.size()/2));

     auto* header_section = builder->GetDebugFrameHdr();
     header_section->Start();
     header_section->WriteFully(header_buffer.data(), header_buffer.size());
     header_section->WriteFully(binary_search_table.data(),
                                binary_search_table.size() * sizeof(binary_search_table[0]));
     header_section->End();
   }
 }

 }  // namespace debug
 }  // namespace art

 #endif  // ART_COMPILER_DEBUG_ELF_DEBUG_FRAME_WRITER_H_
	/*
	* 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_DEBUG_FRAME_WRITER_H_
	#define ART_COMPILER_DEBUG_ELF_DEBUG_FRAME_WRITER_H_

	#include <vector>

	#include "arch/instruction_set.h"
	#include "base/macros.h"
	#include "debug/method_debug_info.h"
	#include "dwarf/debug_frame_opcode_writer.h"
	#include "dwarf/dwarf_constants.h"
	#include "dwarf/headers.h"
	#include "elf/elf_builder.h"

	namespace art HIDDEN {
	namespace debug {

	static constexpr bool kWriteDebugFrameHdr = false;

	// Binary search table is not useful if the number of entries is small.
	// In particular, this avoids it for the in-memory JIT mini-debug-info.
	static constexpr size_t kMinDebugFrameHdrEntries = 100;

	static void WriteCIE(InstructionSet isa, /inout/ std::vector<uint8_t>* buffer) {
	using Reg = dwarf::Reg;
	// Scratch registers should be marked as undefined. This tells the
	// debugger that its value in the previous frame is not recoverable.
	bool is64bit = Is64BitInstructionSet(isa);
	switch (isa) {
	case InstructionSet::kArm:
	case InstructionSet::kThumb2: {
	dwarf::DebugFrameOpCodeWriter<> opcodes;
	opcodes.DefCFA(Reg::ArmCore(13), 0); // R13(SP).
	// core registers.
	for (int reg = 0; reg < 13; reg++) {
	if (reg < 4 \|\| reg == 12) {
	opcodes.Undefined(Reg::ArmCore(reg));
	} else {
	opcodes.SameValue(Reg::ArmCore(reg));
	}
	}
	// fp registers.
	for (int reg = 0; reg < 32; reg++) {
	if (reg < 16) {
	opcodes.Undefined(Reg::ArmFp(reg));
	} else {
	opcodes.SameValue(Reg::ArmFp(reg));
	}
	}
	auto return_reg = Reg::ArmCore(14); // R14(LR).
	WriteCIE(is64bit, return_reg, opcodes, buffer);
	return;
	}
	case InstructionSet::kArm64: {
	dwarf::DebugFrameOpCodeWriter<> opcodes;
	opcodes.DefCFA(Reg::Arm64Core(31), 0); // R31(SP).
	// core registers.
	for (int reg = 0; reg < 30; reg++) {
	if (reg < 8 \|\| reg == 16 \|\| reg == 17) {
	opcodes.Undefined(Reg::Arm64Core(reg));
	} else {
	opcodes.SameValue(Reg::Arm64Core(reg));
	}
	}
	// fp registers.
	for (int reg = 0; reg < 32; reg++) {
	if (reg < 8 \|\| reg >= 16) {
	opcodes.Undefined(Reg::Arm64Fp(reg));
	} else {
	opcodes.SameValue(Reg::Arm64Fp(reg));
	}
	}
	auto return_reg = Reg::Arm64Core(30); // R30(LR).
	WriteCIE(is64bit, return_reg, opcodes, buffer);
	return;
	}
	case InstructionSet::kRiscv64: {
	UNIMPLEMENTED(FATAL);
	return;
	}
	case InstructionSet::kX86: {
	// FIXME: Add fp registers once libunwind adds support for them. Bug: 20491296
	constexpr bool generate_opcodes_for_x86_fp = false;
	dwarf::DebugFrameOpCodeWriter<> opcodes;
	opcodes.DefCFA(Reg::X86Core(4), 4); // R4(ESP).
	opcodes.Offset(Reg::X86Core(8), -4); // R8(EIP).
	// core registers.
	for (int reg = 0; reg < 8; reg++) {
	if (reg <= 3) {
	opcodes.Undefined(Reg::X86Core(reg));
	} else if (reg == 4) {
	// Stack pointer.
	} else {
	opcodes.SameValue(Reg::X86Core(reg));
	}
	}
	// fp registers.
	if (generate_opcodes_for_x86_fp) {
	for (int reg = 0; reg < 8; reg++) {
	opcodes.Undefined(Reg::X86Fp(reg));
	}
	}
	auto return_reg = Reg::X86Core(8); // R8(EIP).
	WriteCIE(is64bit, return_reg, opcodes, buffer);
	return;
	}
	case InstructionSet::kX86_64: {
	dwarf::DebugFrameOpCodeWriter<> opcodes;
	opcodes.DefCFA(Reg::X86_64Core(4), 8); // R4(RSP).
	opcodes.Offset(Reg::X86_64Core(16), -8); // R16(RIP).
	// core registers.
	for (int reg = 0; reg < 16; reg++) {
	if (reg == 4) {
	// Stack pointer.
	} else if (reg < 12 && reg != 3 && reg != 5) { // except EBX and EBP.
	opcodes.Undefined(Reg::X86_64Core(reg));
	} else {
	opcodes.SameValue(Reg::X86_64Core(reg));
	}
	}
	// fp registers.
	for (int reg = 0; reg < 16; reg++) {
	if (reg < 12) {
	opcodes.Undefined(Reg::X86_64Fp(reg));
	} else {
	opcodes.SameValue(Reg::X86_64Fp(reg));
	}
	}
	auto return_reg = Reg::X86_64Core(16); // R16(RIP).
	WriteCIE(is64bit, return_reg, opcodes, buffer);
	return;
	}
	case InstructionSet::kNone:
	break;
	}
	LOG(FATAL) << "Cannot write CIE frame for ISA " << isa;
	UNREACHABLE();
	}

	template<typename ElfTypes>
	void WriteCFISection(ElfBuilder<ElfTypes>* builder,
	const ArrayRef<const MethodDebugInfo>& method_infos) {
	// The methods can be written in any order.
	// Let's therefore sort them in the lexicographical order of the opcodes.
	// This has no effect on its own. However, if the final .debug_frame section is
	// compressed it reduces the size since similar opcodes sequences are grouped.
	std::vector<const MethodDebugInfo*> sorted_method_infos;
	sorted_method_infos.reserve(method_infos.size());
	for (size_t i = 0; i < method_infos.size(); i++) {
	if (!method_infos[i].cfi.empty() && !method_infos[i].deduped) {
	sorted_method_infos.push_back(&method_infos[i]);
	}
	}
	if (sorted_method_infos.empty()) {
	return;
	}
	std::stable_sort(
	sorted_method_infos.begin(),
	sorted_method_infos.end(),
	[](const MethodDebugInfo* lhs, const MethodDebugInfo* rhs) {
	ArrayRef<const uint8_t> l = lhs->cfi;
	ArrayRef<const uint8_t> r = rhs->cfi;
	return std::lexicographical_compare(l.begin(), l.end(), r.begin(), r.end());
	});

	std::vector<uint32_t> binary_search_table;
	bool binary_search_table_is_valid = kWriteDebugFrameHdr;
	if (binary_search_table_is_valid) {
	binary_search_table.reserve(2 * sorted_method_infos.size());
	}

	// Write .debug_frame section.
	auto* cfi_section = builder->GetDebugFrame();
	{
	cfi_section->Start();
	const bool is64bit = Is64BitInstructionSet(builder->GetIsa());
	std::vector<uint8_t> buffer; // Small temporary buffer.
	WriteCIE(builder->GetIsa(), &buffer);
	cfi_section->WriteFully(buffer.data(), buffer.size());
	buffer.clear();
	for (const MethodDebugInfo* mi : sorted_method_infos) {
	DCHECK(!mi->deduped);
	DCHECK(!mi->cfi.empty());
	uint64_t code_address = mi->code_address +
	(mi->is_code_address_text_relative ? builder->GetText()->GetAddress() : 0);
	if (kWriteDebugFrameHdr) {
	// Defensively check that the code address really fits.
	DCHECK_LE(code_address, std::numeric_limits<uint32_t>::max());
	binary_search_table_is_valid &= code_address <= std::numeric_limits<uint32_t>::max();
	binary_search_table.push_back(static_cast<uint32_t>(code_address));
	binary_search_table.push_back(cfi_section->GetPosition());
	}
	dwarf::WriteFDE(is64bit,
	/* cie_pointer= */ 0,
	code_address,
	mi->code_size,
	mi->cfi,
	&buffer);
	cfi_section->WriteFully(buffer.data(), buffer.size());
	buffer.clear();
	}
	cfi_section->End();
	}

	if (binary_search_table_is_valid && method_infos.size() >= kMinDebugFrameHdrEntries) {
	std::sort(binary_search_table.begin(), binary_search_table.end());

	// Custom Android section. It is very similar to the official .eh_frame_hdr format.
	std::vector<uint8_t> header_buffer;
	dwarf::Writer<> header(&header_buffer);
	header.PushUint8(1); // Version.
	header.PushUint8(dwarf::DW_EH_PE_omit); // Encoding of .eh_frame pointer - none.
	header.PushUint8(dwarf::DW_EH_PE_udata4); // Encoding of binary search table size.
	header.PushUint8(dwarf::DW_EH_PE_udata4); // Encoding of binary search table data.
	header.PushUint32(dchecked_integral_cast<uint32_t>(binary_search_table.size()/2));

	auto* header_section = builder->GetDebugFrameHdr();
	header_section->Start();
	header_section->WriteFully(header_buffer.data(), header_buffer.size());
	header_section->WriteFully(binary_search_table.data(),
	binary_search_table.size() * sizeof(binary_search_table[0]));
	header_section->End();
	}
	}

	} // namespace debug
	} // namespace art

	#endif // ART_COMPILER_DEBUG_ELF_DEBUG_FRAME_WRITER_H_