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/MC/MCSymbol.h"
14 #include "llvm/Support/Endian.h"
15 #include "llvm/Support/Format.h"
16 
17 #include <vector>
18 #include <map>
19 
20 namespace llvm {
21 
22 class AsmPrinter;
23 class MCExpr;
24 class MCSymbol;
25 class MCStreamer;
26 
27 class FaultMaps {
28 public:
29   enum FaultKind { FaultingLoad = 1, FaultKindMax };
30 
31   static const char *faultTypeToString(FaultKind);
32 
33   explicit FaultMaps(AsmPrinter &AP);
34 
35   void recordFaultingOp(FaultKind FaultTy, const MCSymbol *HandlerLabel);
36   void serializeToFaultMapSection();
37 
38 private:
39   static const char *WFMP;
40 
41   struct FaultInfo {
42     FaultKind Kind;
43     const MCExpr *FaultingOffsetExpr;
44     const MCExpr *HandlerOffsetExpr;
45 
FaultInfoFaultInfo46     FaultInfo()
47         : Kind(FaultKindMax), FaultingOffsetExpr(nullptr),
48           HandlerOffsetExpr(nullptr) {}
49 
FaultInfoFaultInfo50     explicit FaultInfo(FaultMaps::FaultKind Kind, const MCExpr *FaultingOffset,
51                        const MCExpr *HandlerOffset)
52         : Kind(Kind), FaultingOffsetExpr(FaultingOffset),
53           HandlerOffsetExpr(HandlerOffset) {}
54   };
55 
56   typedef std::vector<FaultInfo> FunctionFaultInfos;
57 
58   // We'd like to keep a stable iteration order for FunctionInfos to help
59   // FileCheck based testing.
60   struct MCSymbolComparator {
operatorMCSymbolComparator61     bool operator()(const MCSymbol *LHS, const MCSymbol *RHS) const {
62       return LHS->getName() < RHS->getName();
63     }
64   };
65 
66   std::map<const MCSymbol *, FunctionFaultInfos, MCSymbolComparator>
67       FunctionInfos;
68   AsmPrinter &AP;
69 
70   void emitFunctionInfo(const MCSymbol *FnLabel, const FunctionFaultInfos &FFI);
71 };
72 
73 /// A parser for the __llvm_faultmaps section generated by the FaultMaps class
74 /// above.  This parser is version locked with with the __llvm_faultmaps section
75 /// generated by the version of LLVM that includes it.  No guarantees are made
76 /// with respect to forward or backward compatibility.
77 class FaultMapParser {
78   typedef uint8_t FaultMapVersionType;
79   static const size_t FaultMapVersionOffset = 0;
80 
81   typedef uint8_t Reserved0Type;
82   static const size_t Reserved0Offset =
83       FaultMapVersionOffset + sizeof(FaultMapVersionType);
84 
85   typedef uint16_t Reserved1Type;
86   static const size_t Reserved1Offset = Reserved0Offset + sizeof(Reserved0Type);
87 
88   typedef uint32_t NumFunctionsType;
89   static const size_t NumFunctionsOffset =
90       Reserved1Offset + sizeof(Reserved1Type);
91 
92   static const size_t FunctionInfosOffset =
93       NumFunctionsOffset + sizeof(NumFunctionsType);
94 
95   const uint8_t *P;
96   const uint8_t *E;
97 
read(const uint8_t * P,const uint8_t * E)98   template <typename T> static T read(const uint8_t *P, const uint8_t *E) {
99     assert(P + sizeof(T) <= E && "out of bounds read!");
100     return support::endian::read<T, support::little, 1>(P);
101   }
102 
103 public:
104   class FunctionFaultInfoAccessor {
105     typedef uint32_t FaultKindType;
106     static const size_t FaultKindOffset = 0;
107 
108     typedef uint32_t FaultingPCOffsetType;
109     static const size_t FaultingPCOffsetOffset =
110         FaultKindOffset + sizeof(FaultKindType);
111 
112     typedef uint32_t HandlerPCOffsetType;
113     static const size_t HandlerPCOffsetOffset =
114         FaultingPCOffsetOffset + sizeof(FaultingPCOffsetType);
115 
116     const uint8_t *P;
117     const uint8_t *E;
118 
119   public:
120     static const size_t Size =
121         HandlerPCOffsetOffset + sizeof(HandlerPCOffsetType);
122 
FunctionFaultInfoAccessor(const uint8_t * P,const uint8_t * E)123     explicit FunctionFaultInfoAccessor(const uint8_t *P, const uint8_t *E)
124         : P(P), E(E) {}
125 
getFaultKind()126     FaultKindType getFaultKind() const {
127       return read<FaultKindType>(P + FaultKindOffset, E);
128     }
129 
getFaultingPCOffset()130     FaultingPCOffsetType getFaultingPCOffset() const {
131       return read<FaultingPCOffsetType>(P + FaultingPCOffsetOffset, E);
132     }
133 
getHandlerPCOffset()134     HandlerPCOffsetType getHandlerPCOffset() const {
135       return read<HandlerPCOffsetType>(P + HandlerPCOffsetOffset, E);
136     }
137   };
138 
139   class FunctionInfoAccessor {
140     typedef uint64_t FunctionAddrType;
141     static const size_t FunctionAddrOffset = 0;
142 
143     typedef uint32_t NumFaultingPCsType;
144     static const size_t NumFaultingPCsOffset =
145         FunctionAddrOffset + sizeof(FunctionAddrType);
146 
147     typedef uint32_t ReservedType;
148     static const size_t ReservedOffset =
149         NumFaultingPCsOffset + sizeof(NumFaultingPCsType);
150 
151     static const size_t FunctionFaultInfosOffset =
152         ReservedOffset + sizeof(ReservedType);
153 
154     static const size_t FunctionInfoHeaderSize = FunctionFaultInfosOffset;
155 
156     const uint8_t *P;
157     const uint8_t *E;
158 
159   public:
FunctionInfoAccessor()160     FunctionInfoAccessor() : P(nullptr), E(nullptr) {}
161 
FunctionInfoAccessor(const uint8_t * P,const uint8_t * E)162     explicit FunctionInfoAccessor(const uint8_t *P, const uint8_t *E)
163         : P(P), E(E) {}
164 
getFunctionAddr()165     FunctionAddrType getFunctionAddr() const {
166       return read<FunctionAddrType>(P + FunctionAddrOffset, E);
167     }
168 
getNumFaultingPCs()169     NumFaultingPCsType getNumFaultingPCs() const {
170       return read<NumFaultingPCsType>(P + NumFaultingPCsOffset, E);
171     }
172 
getFunctionFaultInfoAt(uint32_t Index)173     FunctionFaultInfoAccessor getFunctionFaultInfoAt(uint32_t Index) const {
174       assert(Index < getNumFaultingPCs() && "index out of bounds!");
175       const uint8_t *Begin = P + FunctionFaultInfosOffset +
176                              FunctionFaultInfoAccessor::Size * Index;
177       return FunctionFaultInfoAccessor(Begin, E);
178     }
179 
getNextFunctionInfo()180     FunctionInfoAccessor getNextFunctionInfo() const {
181       size_t MySize = FunctionInfoHeaderSize +
182                       getNumFaultingPCs() * FunctionFaultInfoAccessor::Size;
183 
184       const uint8_t *Begin = P + MySize;
185       assert(Begin < E && "out of bounds!");
186       return FunctionInfoAccessor(Begin, E);
187     }
188   };
189 
FaultMapParser(const uint8_t * Begin,const uint8_t * End)190   explicit FaultMapParser(const uint8_t *Begin, const uint8_t *End)
191       : P(Begin), E(End) {}
192 
getFaultMapVersion()193   FaultMapVersionType getFaultMapVersion() const {
194     auto Version = read<FaultMapVersionType>(P + FaultMapVersionOffset, E);
195     assert(Version == 1 && "only version 1 supported!");
196     return Version;
197   }
198 
getNumFunctions()199   NumFunctionsType getNumFunctions() const {
200     return read<NumFunctionsType>(P + NumFunctionsOffset, E);
201   }
202 
getFirstFunctionInfo()203   FunctionInfoAccessor getFirstFunctionInfo() const {
204     const uint8_t *Begin = P + FunctionInfosOffset;
205     return FunctionInfoAccessor(Begin, E);
206   }
207 };
208 
209 raw_ostream &
210 operator<<(raw_ostream &OS, const FaultMapParser::FunctionFaultInfoAccessor &);
211 
212 raw_ostream &operator<<(raw_ostream &OS,
213                         const FaultMapParser::FunctionInfoAccessor &);
214 
215 raw_ostream &operator<<(raw_ostream &OS, const FaultMapParser &);
216 
217 } // namespace llvm
218 
219 #endif
220