1 //===------------------- FaultMaps.h - The "FaultMaps" section --*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #ifndef LLVM_CODEGEN_FAULTMAPS_H
11 #define LLVM_CODEGEN_FAULTMAPS_H
12 
13 #include "llvm/ADT/DenseMap.h"
14 #include "llvm/MC/MCSymbol.h"
15 #include "llvm/Support/Endian.h"
16 #include "llvm/Support/Format.h"
17 
18 #include <vector>
19 #include <map>
20 
21 namespace llvm {
22 
23 class AsmPrinter;
24 class MCExpr;
25 class MCSymbol;
26 class MCStreamer;
27 
28 class FaultMaps {
29 public:
30   enum FaultKind { FaultingLoad = 1, FaultKindMax };
31 
32   static const char *faultTypeToString(FaultKind);
33 
34   explicit FaultMaps(AsmPrinter &AP);
35 
36   void recordFaultingOp(FaultKind FaultTy, const MCSymbol *HandlerLabel);
37   void serializeToFaultMapSection();
38 
39 private:
40   static const char *WFMP;
41 
42   struct FaultInfo {
43     FaultKind Kind;
44     const MCExpr *FaultingOffsetExpr;
45     const MCExpr *HandlerOffsetExpr;
46 
FaultInfoFaultInfo47     FaultInfo()
48         : Kind(FaultKindMax), FaultingOffsetExpr(nullptr),
49           HandlerOffsetExpr(nullptr) {}
50 
FaultInfoFaultInfo51     explicit FaultInfo(FaultMaps::FaultKind Kind, const MCExpr *FaultingOffset,
52                        const MCExpr *HandlerOffset)
53         : Kind(Kind), FaultingOffsetExpr(FaultingOffset),
54           HandlerOffsetExpr(HandlerOffset) {}
55   };
56 
57   typedef std::vector<FaultInfo> FunctionFaultInfos;
58 
59   // We'd like to keep a stable iteration order for FunctionInfos to help
60   // FileCheck based testing.
61   struct MCSymbolComparator {
operatorMCSymbolComparator62     bool operator()(const MCSymbol *LHS, const MCSymbol *RHS) const {
63       return LHS->getName() < RHS->getName();
64     }
65   };
66 
67   std::map<const MCSymbol *, FunctionFaultInfos, MCSymbolComparator>
68       FunctionInfos;
69   AsmPrinter &AP;
70 
71   void emitFunctionInfo(const MCSymbol *FnLabel, const FunctionFaultInfos &FFI);
72 };
73 
74 /// A parser for the __llvm_faultmaps section generated by the FaultMaps class
75 /// above.  This parser is version locked with with the __llvm_faultmaps section
76 /// generated by the version of LLVM that includes it.  No guarantees are made
77 /// with respect to forward or backward compatibility.
78 class FaultMapParser {
79   typedef uint8_t FaultMapVersionType;
80   static const size_t FaultMapVersionOffset = 0;
81 
82   typedef uint8_t Reserved0Type;
83   static const size_t Reserved0Offset =
84       FaultMapVersionOffset + sizeof(FaultMapVersionType);
85 
86   typedef uint16_t Reserved1Type;
87   static const size_t Reserved1Offset = Reserved0Offset + sizeof(Reserved0Type);
88 
89   typedef uint32_t NumFunctionsType;
90   static const size_t NumFunctionsOffset =
91       Reserved1Offset + sizeof(Reserved1Type);
92 
93   static const size_t FunctionInfosOffset =
94       NumFunctionsOffset + sizeof(NumFunctionsType);
95 
96   const uint8_t *P;
97   const uint8_t *E;
98 
read(const uint8_t * P,const uint8_t * E)99   template <typename T> static T read(const uint8_t *P, const uint8_t *E) {
100     assert(P + sizeof(T) <= E && "out of bounds read!");
101     return support::endian::read<T, support::little, 1>(P);
102   }
103 
104 public:
105   class FunctionFaultInfoAccessor {
106     typedef uint32_t FaultKindType;
107     static const size_t FaultKindOffset = 0;
108 
109     typedef uint32_t FaultingPCOffsetType;
110     static const size_t FaultingPCOffsetOffset =
111         FaultKindOffset + sizeof(FaultKindType);
112 
113     typedef uint32_t HandlerPCOffsetType;
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 
FunctionFaultInfoAccessor(const uint8_t * P,const uint8_t * E)124     explicit FunctionFaultInfoAccessor(const uint8_t *P, const uint8_t *E)
125         : P(P), E(E) {}
126 
getFaultKind()127     FaultKindType getFaultKind() const {
128       return read<FaultKindType>(P + FaultKindOffset, E);
129     }
130 
getFaultingPCOffset()131     FaultingPCOffsetType getFaultingPCOffset() const {
132       return read<FaultingPCOffsetType>(P + FaultingPCOffsetOffset, E);
133     }
134 
getHandlerPCOffset()135     HandlerPCOffsetType getHandlerPCOffset() const {
136       return read<HandlerPCOffsetType>(P + HandlerPCOffsetOffset, E);
137     }
138   };
139 
140   class FunctionInfoAccessor {
141     typedef uint64_t FunctionAddrType;
142     static const size_t FunctionAddrOffset = 0;
143 
144     typedef uint32_t NumFaultingPCsType;
145     static const size_t NumFaultingPCsOffset =
146         FunctionAddrOffset + sizeof(FunctionAddrType);
147 
148     typedef uint32_t ReservedType;
149     static const size_t ReservedOffset =
150         NumFaultingPCsOffset + sizeof(NumFaultingPCsType);
151 
152     static const size_t FunctionFaultInfosOffset =
153         ReservedOffset + sizeof(ReservedType);
154 
155     static const size_t FunctionInfoHeaderSize = FunctionFaultInfosOffset;
156 
157     const uint8_t *P;
158     const uint8_t *E;
159 
160   public:
FunctionInfoAccessor()161     FunctionInfoAccessor() : P(nullptr), E(nullptr) {}
162 
FunctionInfoAccessor(const uint8_t * P,const uint8_t * E)163     explicit FunctionInfoAccessor(const uint8_t *P, const uint8_t *E)
164         : P(P), E(E) {}
165 
getFunctionAddr()166     FunctionAddrType getFunctionAddr() const {
167       return read<FunctionAddrType>(P + FunctionAddrOffset, E);
168     }
169 
getNumFaultingPCs()170     NumFaultingPCsType getNumFaultingPCs() const {
171       return read<NumFaultingPCsType>(P + NumFaultingPCsOffset, E);
172     }
173 
getFunctionFaultInfoAt(uint32_t Index)174     FunctionFaultInfoAccessor getFunctionFaultInfoAt(uint32_t Index) const {
175       assert(Index < getNumFaultingPCs() && "index out of bounds!");
176       const uint8_t *Begin = P + FunctionFaultInfosOffset +
177                              FunctionFaultInfoAccessor::Size * Index;
178       return FunctionFaultInfoAccessor(Begin, E);
179     }
180 
getNextFunctionInfo()181     FunctionInfoAccessor getNextFunctionInfo() const {
182       size_t MySize = FunctionInfoHeaderSize +
183                       getNumFaultingPCs() * FunctionFaultInfoAccessor::Size;
184 
185       const uint8_t *Begin = P + MySize;
186       assert(Begin < E && "out of bounds!");
187       return FunctionInfoAccessor(Begin, E);
188     }
189   };
190 
FaultMapParser(const uint8_t * Begin,const uint8_t * End)191   explicit FaultMapParser(const uint8_t *Begin, const uint8_t *End)
192       : P(Begin), E(End) {}
193 
getFaultMapVersion()194   FaultMapVersionType getFaultMapVersion() const {
195     auto Version = read<FaultMapVersionType>(P + FaultMapVersionOffset, E);
196     assert(Version == 1 && "only version 1 supported!");
197     return Version;
198   }
199 
getNumFunctions()200   NumFunctionsType getNumFunctions() const {
201     return read<NumFunctionsType>(P + NumFunctionsOffset, E);
202   }
203 
getFirstFunctionInfo()204   FunctionInfoAccessor getFirstFunctionInfo() const {
205     const uint8_t *Begin = P + FunctionInfosOffset;
206     return FunctionInfoAccessor(Begin, E);
207   }
208 };
209 
210 raw_ostream &
211 operator<<(raw_ostream &OS, const FaultMapParser::FunctionFaultInfoAccessor &);
212 
213 raw_ostream &operator<<(raw_ostream &OS,
214                         const FaultMapParser::FunctionInfoAccessor &);
215 
216 raw_ostream &operator<<(raw_ostream &OS, const FaultMapParser &);
217 
218 } // namespace llvm
219 
220 #endif
221