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			393 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			393 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| //===-- DWARFDebugFrame.h - Parsing of .debug_frame -------------*- C++ -*-===//
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| //
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| //                     The LLVM Compiler Infrastructure
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| //
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| // This file is distributed under the University of Illinois Open Source
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| // License. See LICENSE.TXT for details.
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| //
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| //===----------------------------------------------------------------------===//
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| 
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| #include "DWARFDebugFrame.h"
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| #include "llvm/ADT/SmallString.h"
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| #include "llvm/Support/DataTypes.h"
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| #include "llvm/Support/Dwarf.h"
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| #include "llvm/Support/ErrorHandling.h"
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| #include "llvm/Support/Format.h"
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| #include "llvm/Support/raw_ostream.h"
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| #include <string>
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| #include <vector>
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| 
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| using namespace llvm;
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| using namespace dwarf;
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| 
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| 
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| /// \brief Abstract frame entry defining the common interface concrete
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| /// entries implement.
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| class llvm::FrameEntry {
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| public:
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|   enum FrameKind {FK_CIE, FK_FDE};
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|   FrameEntry(FrameKind K, DataExtractor D, uint64_t Offset, uint64_t Length)
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|     : Kind(K), Data(D), Offset(Offset), Length(Length) {}
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| 
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|   virtual ~FrameEntry() {
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|   }
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| 
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|   FrameKind getKind() const { return Kind; }
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|   virtual uint64_t getOffset() const { return Offset; }
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| 
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|   /// \brief Parse and store a sequence of CFI instructions from our data
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|   /// stream, starting at *Offset and ending at EndOffset. If everything
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|   /// goes well, *Offset should be equal to EndOffset when this method
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|   /// returns. Otherwise, an error occurred.
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|   virtual void parseInstructions(uint32_t *Offset, uint32_t EndOffset);
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| 
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|   /// \brief Dump the entry header to the given output stream.
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|   virtual void dumpHeader(raw_ostream &OS) const = 0;
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| 
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|   /// \brief Dump the entry's instructions to the given output stream.
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|   virtual void dumpInstructions(raw_ostream &OS) const;
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| 
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| protected:
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|   const FrameKind Kind;
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| 
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|   /// \brief The data stream holding the section from which the entry was
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|   /// parsed.
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|   DataExtractor Data;
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| 
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|   /// \brief Offset of this entry in the section.
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|   uint64_t Offset;
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| 
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|   /// \brief Entry length as specified in DWARF.
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|   uint64_t Length;
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| 
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|   /// An entry may contain CFI instructions. An instruction consists of an
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|   /// opcode and an optional sequence of operands.
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|   typedef std::vector<uint64_t> Operands;
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|   struct Instruction {
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|     Instruction(uint8_t Opcode)
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|       : Opcode(Opcode)
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|     {}
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| 
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|     uint8_t Opcode;
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|     Operands Ops;
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|   };
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| 
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|   std::vector<Instruction> Instructions;
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| 
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|   /// Convenience methods to add a new instruction with the given opcode and
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|   /// operands to the Instructions vector.
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|   void addInstruction(uint8_t Opcode) {
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|     Instructions.push_back(Instruction(Opcode));
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|   }
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| 
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|   void addInstruction(uint8_t Opcode, uint64_t Operand1) {
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|     Instructions.push_back(Instruction(Opcode));
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|     Instructions.back().Ops.push_back(Operand1);
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|   }
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| 
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|   void addInstruction(uint8_t Opcode, uint64_t Operand1, uint64_t Operand2) {
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|     Instructions.push_back(Instruction(Opcode));
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|     Instructions.back().Ops.push_back(Operand1);
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|     Instructions.back().Ops.push_back(Operand2);
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|   }
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| };
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| 
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| 
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| // See DWARF standard v3, section 7.23
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| const uint8_t DWARF_CFI_PRIMARY_OPCODE_MASK = 0xc0;
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| const uint8_t DWARF_CFI_PRIMARY_OPERAND_MASK = 0x3f;
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| 
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| 
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| void FrameEntry::parseInstructions(uint32_t *Offset, uint32_t EndOffset) {
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|   while (*Offset < EndOffset) {
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|     uint8_t Opcode = Data.getU8(Offset);
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|     // Some instructions have a primary opcode encoded in the top bits.
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|     uint8_t Primary = Opcode & DWARF_CFI_PRIMARY_OPCODE_MASK;
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| 
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|     if (Primary) {
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|       // If it's a primary opcode, the first operand is encoded in the bottom
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|       // bits of the opcode itself.
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|       uint64_t Op1 = Opcode & DWARF_CFI_PRIMARY_OPERAND_MASK;
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|       switch (Primary) {
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|         default: llvm_unreachable("Impossible primary CFI opcode");
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|         case DW_CFA_advance_loc:
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|         case DW_CFA_restore:
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|           addInstruction(Primary, Op1);
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|           break;
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|         case DW_CFA_offset:
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|           addInstruction(Primary, Op1, Data.getULEB128(Offset));
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|           break;
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|       }
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|     } else {
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|       // Extended opcode - its value is Opcode itself.
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|       switch (Opcode) {
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|         default: llvm_unreachable("Invalid extended CFI opcode");
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|         case DW_CFA_nop:
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|         case DW_CFA_remember_state:
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|         case DW_CFA_restore_state:
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|         case DW_CFA_GNU_window_save:
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|           // No operands
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|           addInstruction(Opcode);
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|           break;
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|         case DW_CFA_set_loc:
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|           // Operands: Address
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|           addInstruction(Opcode, Data.getAddress(Offset));
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|           break;
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|         case DW_CFA_advance_loc1:
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|           // Operands: 1-byte delta
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|           addInstruction(Opcode, Data.getU8(Offset));
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|           break;
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|         case DW_CFA_advance_loc2:
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|           // Operands: 2-byte delta
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|           addInstruction(Opcode, Data.getU16(Offset));
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|           break;
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|         case DW_CFA_advance_loc4:
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|           // Operands: 4-byte delta
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|           addInstruction(Opcode, Data.getU32(Offset));
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|           break;
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|         case DW_CFA_restore_extended:
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|         case DW_CFA_undefined:
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|         case DW_CFA_same_value:
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|         case DW_CFA_def_cfa_register:
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|         case DW_CFA_def_cfa_offset:
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|           // Operands: ULEB128
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|           addInstruction(Opcode, Data.getULEB128(Offset));
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|           break;
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|         case DW_CFA_def_cfa_offset_sf:
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|           // Operands: SLEB128
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|           addInstruction(Opcode, Data.getSLEB128(Offset));
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|           break;
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|         case DW_CFA_offset_extended:
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|         case DW_CFA_register:
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|         case DW_CFA_def_cfa:
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|         case DW_CFA_val_offset:
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|           // Operands: ULEB128, ULEB128
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|           addInstruction(Opcode, Data.getULEB128(Offset),
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|                                  Data.getULEB128(Offset));
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|           break;
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|         case DW_CFA_offset_extended_sf:
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|         case DW_CFA_def_cfa_sf:
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|         case DW_CFA_val_offset_sf:
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|           // Operands: ULEB128, SLEB128
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|           addInstruction(Opcode, Data.getULEB128(Offset),
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|                                  Data.getSLEB128(Offset));
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|           break;
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|         case DW_CFA_def_cfa_expression:
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|         case DW_CFA_expression:
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|         case DW_CFA_val_expression:
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|           // TODO: implement this
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|           report_fatal_error("Values with expressions not implemented yet!");
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|       }
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|     }
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|   }
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| }
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| 
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| 
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| void FrameEntry::dumpInstructions(raw_ostream &OS) const {
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|   // TODO: at the moment only instruction names are dumped. Expand this to
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|   // dump operands as well.
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|   for (std::vector<Instruction>::const_iterator I = Instructions.begin(),
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|                                                 E = Instructions.end();
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|        I != E; ++I) {
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|     uint8_t Opcode = I->Opcode;
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|     if (Opcode & DWARF_CFI_PRIMARY_OPCODE_MASK)
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|       Opcode &= DWARF_CFI_PRIMARY_OPCODE_MASK;
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|     OS << "  " << CallFrameString(Opcode) << ":\n";
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|   }
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| }
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| 
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| 
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| namespace {
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| /// \brief DWARF Common Information Entry (CIE)
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| class CIE : public FrameEntry {
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| public:
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|   // CIEs (and FDEs) are simply container classes, so the only sensible way to
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|   // create them is by providing the full parsed contents in the constructor.
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|   CIE(DataExtractor D, uint64_t Offset, uint64_t Length, uint8_t Version,
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|       SmallString<8> Augmentation, uint64_t CodeAlignmentFactor,
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|       int64_t DataAlignmentFactor, uint64_t ReturnAddressRegister)
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|    : FrameEntry(FK_CIE, D, Offset, Length), Version(Version),
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|      Augmentation(Augmentation), CodeAlignmentFactor(CodeAlignmentFactor),
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|      DataAlignmentFactor(DataAlignmentFactor),
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|      ReturnAddressRegister(ReturnAddressRegister) {}
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| 
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|   ~CIE() {
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|   }
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| 
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|   void dumpHeader(raw_ostream &OS) const {
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|     OS << format("%08x %08x %08x CIE",
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|                  (uint32_t)Offset, (uint32_t)Length, DW_CIE_ID)
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|        << "\n";
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|     OS << format("  Version:               %d\n", Version);
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|     OS << "  Augmentation:          \"" << Augmentation << "\"\n";
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|     OS << format("  Code alignment factor: %u\n",
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|                  (uint32_t)CodeAlignmentFactor);
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|     OS << format("  Data alignment factor: %d\n",
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|                  (int32_t)DataAlignmentFactor);
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|     OS << format("  Return address column: %d\n",
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|                  (int32_t)ReturnAddressRegister);
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|     OS << "\n";
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|   }
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| 
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|   static bool classof(const FrameEntry *FE) {
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|     return FE->getKind() == FK_CIE;
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|   } 
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| 
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| private:
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|   /// The following fields are defined in section 6.4.1 of the DWARF standard v3
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|   uint8_t Version;
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|   SmallString<8> Augmentation;
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|   uint64_t CodeAlignmentFactor;
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|   int64_t DataAlignmentFactor;
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|   uint64_t ReturnAddressRegister;
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| };
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| 
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| 
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| /// \brief DWARF Frame Description Entry (FDE)
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| class FDE : public FrameEntry {
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| public:
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|   // Each FDE has a CIE it's "linked to". Our FDE contains is constructed with
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|   // an offset to the CIE (provided by parsing the FDE header). The CIE itself
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|   // is obtained lazily once it's actually required.
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|   FDE(DataExtractor D, uint64_t Offset, uint64_t Length,
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|       int64_t LinkedCIEOffset, uint64_t InitialLocation, uint64_t AddressRange)
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|    : FrameEntry(FK_FDE, D, Offset, Length), LinkedCIEOffset(LinkedCIEOffset),
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|      InitialLocation(InitialLocation), AddressRange(AddressRange),
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|      LinkedCIE(NULL) {}
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| 
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|   ~FDE() {
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|   }
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| 
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|   void dumpHeader(raw_ostream &OS) const {
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|     OS << format("%08x %08x %08x FDE ",
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|                  (uint32_t)Offset, (uint32_t)Length, (int32_t)LinkedCIEOffset);
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|     OS << format("cie=%08x pc=%08x...%08x\n",
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|                  (int32_t)LinkedCIEOffset,
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|                  (uint32_t)InitialLocation,
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|                  (uint32_t)InitialLocation + (uint32_t)AddressRange);
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|     if (LinkedCIE) {
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|       OS << format("%p\n", LinkedCIE);
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|     }
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|   }
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| 
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|   static bool classof(const FrameEntry *FE) {
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|     return FE->getKind() == FK_FDE;
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|   } 
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| private:
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| 
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|   /// The following fields are defined in section 6.4.1 of the DWARF standard v3
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|   uint64_t LinkedCIEOffset;
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|   uint64_t InitialLocation;
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|   uint64_t AddressRange;
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|   CIE *LinkedCIE;
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| };
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| } // end anonymous namespace
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| 
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| 
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| DWARFDebugFrame::DWARFDebugFrame() {
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| }
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| 
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| 
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| DWARFDebugFrame::~DWARFDebugFrame() {
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|   for (EntryVector::iterator I = Entries.begin(), E = Entries.end();
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|        I != E; ++I) {
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|     delete *I;
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|   }
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| }
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| 
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| 
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| static void LLVM_ATTRIBUTE_UNUSED dumpDataAux(DataExtractor Data,
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|                                               uint32_t Offset, int Length) {
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|   errs() << "DUMP: ";
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|   for (int i = 0; i < Length; ++i) {
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|     uint8_t c = Data.getU8(&Offset);
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|     errs().write_hex(c); errs() << " ";
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|   }
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|   errs() << "\n";
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| }
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| 
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| 
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| void DWARFDebugFrame::parse(DataExtractor Data) {
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|   uint32_t Offset = 0;
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| 
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|   while (Data.isValidOffset(Offset)) {
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|     uint32_t StartOffset = Offset;
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| 
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|     bool IsDWARF64 = false;
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|     uint64_t Length = Data.getU32(&Offset);
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|     uint64_t Id;
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| 
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|     if (Length == UINT32_MAX) {
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|       // DWARF-64 is distinguished by the first 32 bits of the initial length
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|       // field being 0xffffffff. Then, the next 64 bits are the actual entry
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|       // length.
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|       IsDWARF64 = true;
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|       Length = Data.getU64(&Offset);
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|     }
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| 
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|     // At this point, Offset points to the next field after Length.
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|     // Length is the structure size excluding itself. Compute an offset one
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|     // past the end of the structure (needed to know how many instructions to
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|     // read).
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|     // TODO: For honest DWARF64 support, DataExtractor will have to treat
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|     //       offset_ptr as uint64_t*
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|     uint32_t EndStructureOffset = Offset + static_cast<uint32_t>(Length);
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| 
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|     // The Id field's size depends on the DWARF format
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|     Id = Data.getUnsigned(&Offset, IsDWARF64 ? 8 : 4);
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|     bool IsCIE = ((IsDWARF64 && Id == DW64_CIE_ID) || Id == DW_CIE_ID);
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| 
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|     FrameEntry *Entry = 0;
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|     if (IsCIE) {
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|       // Note: this is specifically DWARFv3 CIE header structure. It was
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|       // changed in DWARFv4. We currently don't support reading DWARFv4
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|       // here because LLVM itself does not emit it (and LLDB doesn't
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|       // support it either).
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|       uint8_t Version = Data.getU8(&Offset);
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|       const char *Augmentation = Data.getCStr(&Offset);
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|       uint64_t CodeAlignmentFactor = Data.getULEB128(&Offset);
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|       int64_t DataAlignmentFactor = Data.getSLEB128(&Offset);
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|       uint64_t ReturnAddressRegister = Data.getULEB128(&Offset);
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| 
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|       Entry = new CIE(Data, StartOffset, Length, Version,
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|                       StringRef(Augmentation), CodeAlignmentFactor,
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|                       DataAlignmentFactor, ReturnAddressRegister);
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|     } else {
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|       // FDE
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|       uint64_t CIEPointer = Id;
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|       uint64_t InitialLocation = Data.getAddress(&Offset);
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|       uint64_t AddressRange = Data.getAddress(&Offset);
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| 
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|       Entry = new FDE(Data, StartOffset, Length, CIEPointer,
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|                       InitialLocation, AddressRange);
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|     }
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| 
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|     assert(Entry && "Expected Entry to be populated with CIE or FDE");
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|     Entry->parseInstructions(&Offset, EndStructureOffset);
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| 
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|     if (Offset == EndStructureOffset) {
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|       // Entry instrucitons parsed successfully.
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|       Entries.push_back(Entry);
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|     } else {
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|       std::string Str;
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|       raw_string_ostream OS(Str);
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|       OS << format("Parsing entry instructions at %lx failed",
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|                    Entry->getOffset());
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|       report_fatal_error(Str);
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|     }
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|   }
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| }
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| 
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| 
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| void DWARFDebugFrame::dump(raw_ostream &OS) const {
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|   OS << "\n";
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|   for (EntryVector::const_iterator I = Entries.begin(), E = Entries.end();
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|        I != E; ++I) {
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|     FrameEntry *Entry = *I;
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|     Entry->dumpHeader(OS);
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|     Entry->dumpInstructions(OS);
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|     OS << "\n";
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|   }
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| }
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| 
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