LCOV - code coverage report
Current view: top level - src - eh-frame.h (source / functions) Hit Total Coverage
Test: app.info Lines: 10 10 100.0 %
Date: 2017-04-26 Functions: 0 0 -

          Line data    Source code
       1             : // Copyright 2016 the V8 project authors. All rights reserved.
       2             : // Use of this source code is governed by a BSD-style license that can be
       3             : // found in the LICENSE file.
       4             : 
       5             : #ifndef V8_EH_FRAME_H_
       6             : #define V8_EH_FRAME_H_
       7             : 
       8             : #include "src/base/compiler-specific.h"
       9             : #include "src/globals.h"
      10             : #include "src/macro-assembler.h"
      11             : #include "src/zone/zone-containers.h"
      12             : 
      13             : namespace v8 {
      14             : namespace internal {
      15             : 
      16             : class V8_EXPORT_PRIVATE EhFrameConstants final
      17             :     : public NON_EXPORTED_BASE(AllStatic) {
      18             :  public:
      19             :   enum class DwarfOpcodes : byte {
      20             :     kNop = 0x00,
      21             :     kAdvanceLoc1 = 0x02,
      22             :     kAdvanceLoc2 = 0x03,
      23             :     kAdvanceLoc4 = 0x04,
      24             :     kSameValue = 0x08,
      25             :     kDefCfa = 0x0c,
      26             :     kDefCfaRegister = 0x0d,
      27             :     kDefCfaOffset = 0x0e,
      28             :     kOffsetExtendedSf = 0x11,
      29             :   };
      30             : 
      31             :   enum DwarfEncodingSpecifiers : byte {
      32             :     kUData4 = 0x03,
      33             :     kSData4 = 0x0b,
      34             :     kPcRel = 0x10,
      35             :     kDataRel = 0x30,
      36             :     kOmit = 0xff,
      37             :   };
      38             : 
      39             :   static const int kLocationTag = 1;
      40             :   static const int kLocationMask = 0x3f;
      41             :   static const int kLocationMaskSize = 6;
      42             : 
      43             :   static const int kSavedRegisterTag = 2;
      44             :   static const int kSavedRegisterMask = 0x3f;
      45             :   static const int kSavedRegisterMaskSize = 6;
      46             : 
      47             :   static const int kFollowInitialRuleTag = 3;
      48             :   static const int kFollowInitialRuleMask = 0x3f;
      49             :   static const int kFollowInitialRuleMaskSize = 6;
      50             : 
      51             :   static const int kProcedureAddressOffsetInFde = 2 * kInt32Size;
      52             :   static const int kProcedureSizeOffsetInFde = 3 * kInt32Size;
      53             : 
      54             :   static const int kInitialStateOffsetInCie = 19;
      55             :   static const int kEhFrameTerminatorSize = 4;
      56             : 
      57             :   // Defined in eh-writer-<arch>.cc
      58             :   static const int kCodeAlignmentFactor;
      59             :   static const int kDataAlignmentFactor;
      60             : 
      61             :   static const int kFdeVersionSize = 1;
      62             :   static const int kFdeEncodingSpecifiersSize = 3;
      63             : 
      64             :   static const int kEhFrameHdrVersion = 1;
      65             :   static const int kEhFrameHdrSize = 20;
      66             : };
      67             : 
      68             : class V8_EXPORT_PRIVATE EhFrameWriter {
      69             :  public:
      70             :   explicit EhFrameWriter(Zone* zone);
      71             : 
      72             :   // The empty frame is a hack to trigger fp-based unwinding in Linux perf
      73             :   // compiled with libunwind support when processing DWARF-based call graphs.
      74             :   //
      75             :   // It is effectively a valid eh_frame_hdr with an empty look up table.
      76             :   //
      77             :   static void WriteEmptyEhFrame(std::ostream& stream);  // NOLINT
      78             : 
      79             :   // Write the CIE and FDE header. Call it before any other method.
      80             :   void Initialize();
      81             : 
      82             :   void AdvanceLocation(int pc_offset);
      83             : 
      84             :   // The <base_address> is the one to which all <offset>s in SaveRegisterToStack
      85             :   // directives are relative. It is given by <base_register> + <base_offset>.
      86             :   //
      87             :   // The <base_offset> must be positive or 0.
      88             :   //
      89             :   void SetBaseAddressRegister(Register base_register);
      90             :   void SetBaseAddressOffset(int base_offset);
      91             :   void IncreaseBaseAddressOffset(int base_delta) {
      92          46 :     SetBaseAddressOffset(base_offset_ + base_delta);
      93             :   }
      94             :   void SetBaseAddressRegisterAndOffset(Register base_register, int base_offset);
      95             : 
      96             :   // Register saved at location <base_address> + <offset>.
      97             :   // The <offset> must be a multiple of EhFrameConstants::kDataAlignment.
      98             :   void RecordRegisterSavedToStack(Register name, int offset) {
      99          23 :     RecordRegisterSavedToStack(RegisterToDwarfCode(name), offset);
     100             :   }
     101             : 
     102             :   // The register has not been modified from the previous frame.
     103             :   void RecordRegisterNotModified(Register name);
     104             : 
     105             :   // The register follows the rule defined in the CIE.
     106             :   void RecordRegisterFollowsInitialRule(Register name);
     107             : 
     108             :   void Finish(int code_size);
     109             : 
     110             :   // Remember to call Finish() before GetEhFrame().
     111             :   //
     112             :   // The EhFrameWriter instance owns the buffer pointed by
     113             :   // CodeDesc::unwinding_info, and must outlive any use of the CodeDesc.
     114             :   //
     115             :   void GetEhFrame(CodeDesc* desc);
     116             : 
     117             :   int last_pc_offset() const { return last_pc_offset_; }
     118             :   Register base_register() const { return base_register_; }
     119             :   int base_offset() const { return base_offset_; }
     120             : 
     121             :  private:
     122             :   enum class InternalState { kUndefined, kInitialized, kFinalized };
     123             : 
     124             :   static const uint32_t kInt32Placeholder = 0xdeadc0de;
     125             : 
     126             :   void WriteSLeb128(int32_t value);
     127             :   void WriteULeb128(uint32_t value);
     128             : 
     129         881 :   void WriteByte(byte value) { eh_frame_buffer_.push_back(value); }
     130             :   void WriteOpcode(EhFrameConstants::DwarfOpcodes opcode) {
     131             :     WriteByte(static_cast<byte>(opcode));
     132             :   }
     133             :   void WriteBytes(const byte* start, int size) {
     134         259 :     eh_frame_buffer_.insert(eh_frame_buffer_.end(), start, start + size);
     135             :   }
     136             :   void WriteInt16(uint16_t value) {
     137             :     WriteBytes(reinterpret_cast<const byte*>(&value), sizeof(value));
     138             :   }
     139             :   void WriteInt32(uint32_t value) {
     140             :     WriteBytes(reinterpret_cast<const byte*>(&value), sizeof(value));
     141             :   }
     142             :   void PatchInt32(int base_offset, uint32_t value) {
     143             :     DCHECK_EQ(ReadUnalignedUInt32(eh_frame_buffer_.data() + base_offset),
     144             :               kInt32Placeholder);
     145             :     DCHECK_LT(base_offset + kInt32Size, eh_frame_offset());
     146         148 :     WriteUnalignedUInt32(eh_frame_buffer_.data() + base_offset, value);
     147             :   }
     148             : 
     149             :   // Write the common information entry, which includes encoding specifiers,
     150             :   // alignment factors, the return address (pseudo) register code and the
     151             :   // directives to construct the initial state of the unwinding table.
     152             :   void WriteCie();
     153             : 
     154             :   // Write the header of the function data entry, containing a pointer to the
     155             :   // correspondent CIE and the position and size of the associated routine.
     156             :   void WriteFdeHeader();
     157             : 
     158             :   // Write the contents of the .eh_frame_hdr section, including encoding
     159             :   // specifiers and the routine => FDE lookup table.
     160             :   void WriteEhFrameHdr(int code_size);
     161             : 
     162             :   // Write nops until the size reaches a multiple of 8 bytes.
     163             :   void WritePaddingToAlignedSize(int unpadded_size);
     164             : 
     165             :   // Internal version that directly accepts a DWARF register code, needed for
     166             :   // handling pseudo-registers on some platforms.
     167             :   void RecordRegisterSavedToStack(int register_code, int offset);
     168             : 
     169          37 :   int GetProcedureAddressOffset() const {
     170          37 :     return fde_offset() + EhFrameConstants::kProcedureAddressOffsetInFde;
     171             :   }
     172             : 
     173          37 :   int GetProcedureSizeOffset() const {
     174          37 :     return fde_offset() + EhFrameConstants::kProcedureSizeOffsetInFde;
     175             :   }
     176             : 
     177             :   int eh_frame_offset() const {
     178         518 :     return static_cast<int>(eh_frame_buffer_.size());
     179             :   }
     180             : 
     181             :   int fde_offset() const { return cie_size_; }
     182             : 
     183             :   // Platform specific functions implemented in eh-frame-<arch>.cc
     184             : 
     185             :   static int RegisterToDwarfCode(Register name);
     186             : 
     187             :   // Write directives to build the initial state in the CIE.
     188             :   void WriteInitialStateInCie();
     189             : 
     190             :   // Write the return address (pseudo) register code.
     191             :   void WriteReturnAddressRegisterCode();
     192             : 
     193             :   int cie_size_;
     194             :   int last_pc_offset_;
     195             :   InternalState writer_state_;
     196             :   Register base_register_;
     197             :   int base_offset_;
     198             :   ZoneVector<byte> eh_frame_buffer_;
     199             : 
     200             :   DISALLOW_COPY_AND_ASSIGN(EhFrameWriter);
     201             : };
     202             : 
     203             : class V8_EXPORT_PRIVATE EhFrameIterator {
     204             :  public:
     205             :   EhFrameIterator(const byte* start, const byte* end)
     206             :       : start_(start), next_(start), end_(end) {
     207             :     DCHECK_LE(start, end);
     208             :   }
     209             : 
     210             :   void SkipCie() {
     211             :     DCHECK_EQ(next_, start_);
     212             :     next_ += ReadUnalignedUInt32(next_) + kInt32Size;
     213             :   }
     214             : 
     215             :   void SkipToFdeDirectives() {
     216             :     SkipCie();
     217             :     // Skip the FDE header.
     218             :     Skip(kDirectivesOffsetInFde);
     219             :   }
     220             : 
     221             :   void Skip(int how_many) {
     222             :     DCHECK_GE(how_many, 0);
     223             :     next_ += how_many;
     224             :     DCHECK_LE(next_, end_);
     225             :   }
     226             : 
     227             :   uint32_t GetNextUInt32() { return GetNextValue<uint32_t>(); }
     228             :   uint16_t GetNextUInt16() { return GetNextValue<uint16_t>(); }
     229             :   byte GetNextByte() { return GetNextValue<byte>(); }
     230             :   EhFrameConstants::DwarfOpcodes GetNextOpcode() {
     231             :     return static_cast<EhFrameConstants::DwarfOpcodes>(GetNextByte());
     232             :   }
     233             : 
     234             :   uint32_t GetNextULeb128();
     235             :   int32_t GetNextSLeb128();
     236             : 
     237             :   bool Done() const {
     238             :     DCHECK_LE(next_, end_);
     239             :     return next_ == end_;
     240             :   }
     241             : 
     242             :   int GetCurrentOffset() const {
     243             :     DCHECK_GE(next_, start_);
     244             :     return static_cast<int>(next_ - start_);
     245             :   }
     246             : 
     247             :   int GetBufferSize() { return static_cast<int>(end_ - start_); }
     248             : 
     249             :   const void* current_address() const {
     250             :     return reinterpret_cast<const void*>(next_);
     251             :   }
     252             : 
     253             :  private:
     254             :   static const int kDirectivesOffsetInFde = 4 * kInt32Size + 1;
     255             : 
     256             :   static uint32_t DecodeULeb128(const byte* encoded, int* encoded_size);
     257             :   static int32_t DecodeSLeb128(const byte* encoded, int* encoded_size);
     258             : 
     259             :   template <typename T>
     260             :   T GetNextValue() {
     261             :     T result;
     262             :     DCHECK_LE(next_ + sizeof(result), end_);
     263             :     result = ReadUnalignedValue<T>(next_);
     264             :     next_ += sizeof(result);
     265             :     return result;
     266             :   }
     267             : 
     268             :   const byte* start_;
     269             :   const byte* next_;
     270             :   const byte* end_;
     271             : };
     272             : 
     273             : #ifdef ENABLE_DISASSEMBLER
     274             : 
     275             : class EhFrameDisassembler final {
     276             :  public:
     277             :   EhFrameDisassembler(const byte* start, const byte* end)
     278             :       : start_(start), end_(end) {
     279             :     DCHECK_LT(start, end);
     280             :   }
     281             : 
     282             :   void DisassembleToStream(std::ostream& stream);  // NOLINT
     283             : 
     284             :  private:
     285             :   static void DumpDwarfDirectives(std::ostream& stream,  // NOLINT
     286             :                                   const byte* start, const byte* end);
     287             : 
     288             :   static const char* DwarfRegisterCodeToString(int code);
     289             : 
     290             :   const byte* start_;
     291             :   const byte* end_;
     292             : 
     293             :   DISALLOW_COPY_AND_ASSIGN(EhFrameDisassembler);
     294             : };
     295             : 
     296             : #endif
     297             : 
     298             : }  // namespace internal
     299             : }  // namespace v8
     300             : 
     301             : #endif

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