include/llvm/CodeGen/FaultMaps.h

   1 //===- FaultMaps.h - The "FaultMaps" section --------------------*- 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 #ifndef LLVM_CODEGEN_FAULTMAPS_H
  10 #define LLVM_CODEGEN_FAULTMAPS_H
  11
  12 #include "llvm/MC/MCSymbol.h"
  13 #include "llvm/Support/Endian.h"
  14 #include <cassert>
  15 #include <cstddef>
  16 #include <cstdint>
  17 #include <map>
  18 #include <vector>
  19
  20 namespace llvm {
  21
  22 class AsmPrinter;
  23 class MCExpr;
  24 class raw_ostream;
  25
  26 class FaultMaps {
  27 public:
  28   enum FaultKind {
  29     FaultingLoad = 1,
  30     FaultingLoadStore,
  31     FaultingStore,
  32     FaultKindMax
  33   };
  34
  35   explicit FaultMaps(AsmPrinter &AP);
  36
  37   static const char *faultTypeToString(FaultKind);
  38
  39   void recordFaultingOp(FaultKind FaultTy, const MCSymbol *HandlerLabel);
  40   void serializeToFaultMapSection();
  41   void reset() {
  42     FunctionInfos.clear();
  43   }
  44
  45 private:
  46   static const char *WFMP;
  47
  48   struct FaultInfo {
  49     FaultKind Kind = FaultKindMax;
  50     const MCExpr *FaultingOffsetExpr = nullptr;
  51     const MCExpr *HandlerOffsetExpr = nullptr;
  52
  53     FaultInfo() = default;
  54
  55     explicit FaultInfo(FaultMaps::FaultKind Kind, const MCExpr *FaultingOffset,
  56                        const MCExpr *HandlerOffset)
  57         : Kind(Kind), FaultingOffsetExpr(FaultingOffset),
  58           HandlerOffsetExpr(HandlerOffset) {}
  59   };
  60
  61   using FunctionFaultInfos = std::vector<FaultInfo>;
  62
  63   // We'd like to keep a stable iteration order for FunctionInfos to help
  64   // FileCheck based testing.
  65   struct MCSymbolComparator {
  66     bool operator()(const MCSymbol *LHS, const MCSymbol *RHS) const {
  67       return LHS->getName() < RHS->getName();
  68     }
  69   };
  70
  71   std::map<const MCSymbol *, FunctionFaultInfos, MCSymbolComparator>
  72       FunctionInfos;
  73   AsmPrinter &AP;
  74
  75   void emitFunctionInfo(const MCSymbol *FnLabel, const FunctionFaultInfos &FFI);
  76 };
  77
  78 /// A parser for the __llvm_faultmaps section generated by the FaultMaps class
  79 /// above.  This parser is version locked with with the __llvm_faultmaps section
  80 /// generated by the version of LLVM that includes it.  No guarantees are made
  81 /// with respect to forward or backward compatibility.
  82 class FaultMapParser {
  83   using FaultMapVersionType = uint8_t;
  84   using Reserved0Type = uint8_t;
  85   using Reserved1Type = uint16_t;
  86   using NumFunctionsType = uint32_t;
  87
  88   static const size_t FaultMapVersionOffset = 0;
  89   static const size_t Reserved0Offset =
  90       FaultMapVersionOffset + sizeof(FaultMapVersionType);
  91   static const size_t Reserved1Offset = Reserved0Offset + sizeof(Reserved0Type);
  92   static const size_t NumFunctionsOffset =
  93       Reserved1Offset + sizeof(Reserved1Type);
  94   static const size_t FunctionInfosOffset =
  95       NumFunctionsOffset + sizeof(NumFunctionsType);
  96
  97   const uint8_t *P;
  98   const uint8_t *E;
  99
 100   template <typename T> static T read(const uint8_t *P, const uint8_t *E) {
 101     assert(P + sizeof(T) <= E && "out of bounds read!");
 102     return support::endian::read<T, support::little, 1>(P);
 103   }
 104
 105 public:
 106   class FunctionFaultInfoAccessor {
 107     using FaultKindType = uint32_t;
 108     using FaultingPCOffsetType = uint32_t;
 109     using HandlerPCOffsetType = uint32_t;
 110
 111     static const size_t FaultKindOffset = 0;
 112     static const size_t FaultingPCOffsetOffset =
 113         FaultKindOffset + sizeof(FaultKindType);
 114     static const size_t HandlerPCOffsetOffset =
 115         FaultingPCOffsetOffset + sizeof(FaultingPCOffsetType);
 116
 117     const uint8_t *P;
 118     const uint8_t *E;
 119
 120   public:
 121     static const size_t Size =
 122         HandlerPCOffsetOffset + sizeof(HandlerPCOffsetType);
 123
 124     explicit FunctionFaultInfoAccessor(const uint8_t *P, const uint8_t *E)
 125         : P(P), E(E) {}
 126
 127     FaultKindType getFaultKind() const {
 128       return read<FaultKindType>(P + FaultKindOffset, E);
 129     }
 130
 131     FaultingPCOffsetType getFaultingPCOffset() const {
 132       return read<FaultingPCOffsetType>(P + FaultingPCOffsetOffset, E);
 133     }
 134
 135     HandlerPCOffsetType getHandlerPCOffset() const {
 136       return read<HandlerPCOffsetType>(P + HandlerPCOffsetOffset, E);
 137     }
 138   };
 139
 140   class FunctionInfoAccessor {
 141     using FunctionAddrType = uint64_t;
 142     using NumFaultingPCsType = uint32_t;
 143     using ReservedType = uint32_t;
 144
 145     static const size_t FunctionAddrOffset = 0;
 146     static const size_t NumFaultingPCsOffset =
 147         FunctionAddrOffset + sizeof(FunctionAddrType);
 148     static const size_t ReservedOffset =
 149         NumFaultingPCsOffset + sizeof(NumFaultingPCsType);
 150     static const size_t FunctionFaultInfosOffset =
 151         ReservedOffset + sizeof(ReservedType);
 152     static const size_t FunctionInfoHeaderSize = FunctionFaultInfosOffset;
 153
 154     const uint8_t *P = nullptr;
 155     const uint8_t *E = nullptr;
 156
 157   public:
 158     FunctionInfoAccessor() = default;
 159
 160     explicit FunctionInfoAccessor(const uint8_t *P, const uint8_t *E)
 161         : P(P), E(E) {}
 162
 163     FunctionAddrType getFunctionAddr() const {
 164       return read<FunctionAddrType>(P + FunctionAddrOffset, E);
 165     }
 166
 167     NumFaultingPCsType getNumFaultingPCs() const {
 168       return read<NumFaultingPCsType>(P + NumFaultingPCsOffset, E);
 169     }
 170
 171     FunctionFaultInfoAccessor getFunctionFaultInfoAt(uint32_t Index) const {
 172       assert(Index < getNumFaultingPCs() && "index out of bounds!");
 173       const uint8_t *Begin = P + FunctionFaultInfosOffset +
 174                              FunctionFaultInfoAccessor::Size * Index;
 175       return FunctionFaultInfoAccessor(Begin, E);
 176     }
 177
 178     FunctionInfoAccessor getNextFunctionInfo() const {
 179       size_t MySize = FunctionInfoHeaderSize +
 180                       getNumFaultingPCs() * FunctionFaultInfoAccessor::Size;
 181
 182       const uint8_t *Begin = P + MySize;
 183       assert(Begin < E && "out of bounds!");
 184       return FunctionInfoAccessor(Begin, E);
 185     }
 186   };
 187
 188   explicit FaultMapParser(const uint8_t *Begin, const uint8_t *End)
 189       : P(Begin), E(End) {}
 190
 191   FaultMapVersionType getFaultMapVersion() const {
 192     auto Version = read<FaultMapVersionType>(P + FaultMapVersionOffset, E);
 193     assert(Version == 1 && "only version 1 supported!");
 194     return Version;
 195   }
 196
 197   NumFunctionsType getNumFunctions() const {
 198     return read<NumFunctionsType>(P + NumFunctionsOffset, E);
 199   }
 200
 201   FunctionInfoAccessor getFirstFunctionInfo() const {
 202     const uint8_t *Begin = P + FunctionInfosOffset;
 203     return FunctionInfoAccessor(Begin, E);
 204   }
 205 };
 206
 207 raw_ostream &
 208 operator<<(raw_ostream &OS, const FaultMapParser::FunctionFaultInfoAccessor &);
 209
 210 raw_ostream &operator<<(raw_ostream &OS,
 211                         const FaultMapParser::FunctionInfoAccessor &);
 212
 213 raw_ostream &operator<<(raw_ostream &OS, const FaultMapParser &);
 214
 215 } // end namespace llvm
 216
 217 #endif // LLVM_CODEGEN_FAULTMAPS_H