llvm/lib/ExecutionEngine/JITLink/EHFrameSupportImpl.h

   1 //===------- EHFrameSupportImpl.h - JITLink eh-frame utils ------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // EHFrame registration support for JITLink.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef LLVM_LIB_EXECUTIONENGINE_JITLINK_EHFRAMESUPPORTIMPL_H
  14 #define LLVM_LIB_EXECUTIONENGINE_JITLINK_EHFRAMESUPPORTIMPL_H
  15
  16 #include "llvm/ExecutionEngine/JITLink/EHFrameSupport.h"
  17
  18 #include "llvm/ExecutionEngine/JITLink/JITLink.h"
  19 #include "llvm/Support/BinaryStreamReader.h"
  20
  21 namespace llvm {
  22 namespace jitlink {
  23
  24 /// A LinkGraph pass that splits blocks in an eh-frame section into sub-blocks
  25 /// representing individual eh-frames.
  26 /// EHFrameSplitter should not be run without EHFrameEdgeFixer, which is
  27 /// responsible for adding FDE-to-CIE edges.
  28 class EHFrameSplitter {
  29 public:
  30   EHFrameSplitter(StringRef EHFrameSectionName);
  31   Error operator()(LinkGraph &G);
  32
  33 private:
  34   Error processBlock(LinkGraph &G, Block &B, LinkGraph::SplitBlockCache &Cache);
  35
  36   StringRef EHFrameSectionName;
  37 };
  38
  39 /// A LinkGraph pass that adds missing FDE-to-CIE, FDE-to-PC and FDE-to-LSDA
  40 /// edges.
  41 class EHFrameEdgeFixer {
  42 public:
  43   EHFrameEdgeFixer(StringRef EHFrameSectionName, unsigned PointerSize,
  44                    Edge::Kind Delta64, Edge::Kind Delta32,
  45                    Edge::Kind NegDelta32);
  46   Error operator()(LinkGraph &G);
  47
  48 private:
  49
  50   struct AugmentationInfo {
  51     bool AugmentationDataPresent = false;
  52     bool EHDataFieldPresent = false;
  53     uint8_t Fields[4] = {0x0, 0x0, 0x0, 0x0};
  54   };
  55
  56   struct CIEInformation {
  57     CIEInformation() = default;
  58     CIEInformation(Symbol &CIESymbol) : CIESymbol(&CIESymbol) {}
  59     Symbol *CIESymbol = nullptr;
  60     bool FDEsHaveLSDAField = false;
  61     uint8_t FDEPointerEncoding = 0;
  62     uint8_t LSDAPointerEncoding = 0;
  63   };
  64
  65   struct EdgeTarget {
  66     EdgeTarget() = default;
  67     EdgeTarget(const Edge &E) : Target(&E.getTarget()), Addend(E.getAddend()) {}
  68
  69     Symbol *Target = nullptr;
  70     Edge::AddendT Addend = 0;
  71   };
  72
  73   using BlockEdgeMap = DenseMap<Edge::OffsetT, EdgeTarget>;
  74   using CIEInfosMap = DenseMap<JITTargetAddress, CIEInformation>;
  75
  76   struct ParseContext {
  77     ParseContext(LinkGraph &G) : G(G) {}
  78
  79     Expected<CIEInformation *> findCIEInfo(JITTargetAddress Address) {
  80       auto I = CIEInfos.find(Address);
  81       if (I == CIEInfos.end())
  82         return make_error<JITLinkError>("No CIE found at address " +
  83                                         formatv("{0:x16}", Address));
  84       return &I->second;
  85     }
  86
  87     LinkGraph &G;
  88     CIEInfosMap CIEInfos;
  89     BlockAddressMap AddrToBlock;
  90     SymbolAddressMap AddrToSyms;
  91   };
  92
  93   Error processBlock(ParseContext &PC, Block &B);
  94   Error processCIE(ParseContext &PC, Block &B, size_t RecordOffset,
  95                    size_t RecordLength, size_t CIEDeltaFieldOffset);
  96   Error processFDE(ParseContext &PC, Block &B, size_t RecordOffset,
  97                    size_t RecordLength, size_t CIEDeltaFieldOffset,
  98                    uint32_t CIEDelta, BlockEdgeMap &BlockEdges);
  99
 100   Expected<AugmentationInfo>
 101   parseAugmentationString(BinaryStreamReader &RecordReader);
 102
 103   static bool isSupportedPointerEncoding(uint8_t PointerEncoding);
 104   unsigned getPointerEncodingDataSize(uint8_t PointerEncoding);
 105   Expected<std::pair<JITTargetAddress, Edge::Kind>>
 106   readEncodedPointer(uint8_t PointerEncoding,
 107                      JITTargetAddress PointerFieldAddress,
 108                      BinaryStreamReader &RecordReader);
 109
 110   Expected<Symbol &> getOrCreateSymbol(ParseContext &PC, JITTargetAddress Addr);
 111
 112   StringRef EHFrameSectionName;
 113   unsigned PointerSize;
 114   Edge::Kind Delta64;
 115   Edge::Kind Delta32;
 116   Edge::Kind NegDelta32;
 117 };
 118
 119 /// Add a 32-bit null-terminator to the end of the eh-frame section.
 120 class EHFrameNullTerminator {
 121 public:
 122   EHFrameNullTerminator(StringRef EHFrameSectionName);
 123   Error operator()(LinkGraph &G);
 124
 125 private:
 126   static char NullTerminatorBlockContent[];
 127   StringRef EHFrameSectionName;
 128 };
 129
 130 } // end namespace jitlink
 131 } // end namespace llvm
 132
 133 #endif // LLVM_LIB_EXECUTIONENGINE_JITLINK_EHFRAMESUPPORTIMPL_H