1 //===-- llvm/MC/MCELFObjectWriter.h - ELF Object Writer ---------*- 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_MC_MCELFOBJECTWRITER_H
11 #define LLVM_MC_MCELFOBJECTWRITER_H
12 
13 #include "llvm/ADT/Triple.h"
14 #include "llvm/Support/DataTypes.h"
15 #include "llvm/Support/ELF.h"
16 #include <vector>
17 
18 namespace llvm {
19 class MCAssembler;
20 class MCFixup;
21 class MCFragment;
22 class MCObjectWriter;
23 class MCSymbol;
24 class MCSymbolELF;
25 class MCValue;
26 class raw_pwrite_stream;
27 
28 struct ELFRelocationEntry {
29   uint64_t Offset; // Where is the relocation.
30   const MCSymbolELF *Symbol; // The symbol to relocate with.
31   unsigned Type;   // The type of the relocation.
32   uint64_t Addend; // The addend to use.
33 
ELFRelocationEntryELFRelocationEntry34   ELFRelocationEntry(uint64_t Offset, const MCSymbolELF *Symbol, unsigned Type,
35                      uint64_t Addend)
36       : Offset(Offset), Symbol(Symbol), Type(Type), Addend(Addend) {}
37 };
38 
39 class MCELFObjectTargetWriter {
40   const uint8_t OSABI;
41   const uint16_t EMachine;
42   const unsigned HasRelocationAddend : 1;
43   const unsigned Is64Bit : 1;
44   const unsigned IsN64 : 1;
45 
46 protected:
47 
48   MCELFObjectTargetWriter(bool Is64Bit_, uint8_t OSABI_,
49                           uint16_t EMachine_,  bool HasRelocationAddend,
50                           bool IsN64=false);
51 
52 public:
getOSABI(Triple::OSType OSType)53   static uint8_t getOSABI(Triple::OSType OSType) {
54     switch (OSType) {
55       case Triple::CloudABI:
56         return ELF::ELFOSABI_CLOUDABI;
57       case Triple::PS4:
58       case Triple::FreeBSD:
59         return ELF::ELFOSABI_FREEBSD;
60       default:
61         return ELF::ELFOSABI_NONE;
62     }
63   }
64 
~MCELFObjectTargetWriter()65   virtual ~MCELFObjectTargetWriter() {}
66 
67   virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
68                                 bool IsPCRel) const = 0;
69 
70   virtual bool needsRelocateWithSymbol(const MCSymbol &Sym,
71                                        unsigned Type) const;
72 
73   virtual void sortRelocs(const MCAssembler &Asm,
74                           std::vector<ELFRelocationEntry> &Relocs);
75 
76   /// \name Accessors
77   /// @{
getOSABI()78   uint8_t getOSABI() const { return OSABI; }
getEMachine()79   uint16_t getEMachine() const { return EMachine; }
hasRelocationAddend()80   bool hasRelocationAddend() const { return HasRelocationAddend; }
is64Bit()81   bool is64Bit() const { return Is64Bit; }
isN64()82   bool isN64() const { return IsN64; }
83   /// @}
84 
85   // Instead of changing everyone's API we pack the N64 Type fields
86   // into the existing 32 bit data unsigned.
87 #define R_TYPE_SHIFT 0
88 #define R_TYPE_MASK 0xffffff00
89 #define R_TYPE2_SHIFT 8
90 #define R_TYPE2_MASK 0xffff00ff
91 #define R_TYPE3_SHIFT 16
92 #define R_TYPE3_MASK 0xff00ffff
93 #define R_SSYM_SHIFT 24
94 #define R_SSYM_MASK 0x00ffffff
95 
96   // N64 relocation type accessors
getRType(uint32_t Type)97   uint8_t getRType(uint32_t Type) const {
98     return (unsigned)((Type >> R_TYPE_SHIFT) & 0xff);
99   }
getRType2(uint32_t Type)100   uint8_t getRType2(uint32_t Type) const {
101     return (unsigned)((Type >> R_TYPE2_SHIFT) & 0xff);
102   }
getRType3(uint32_t Type)103   uint8_t getRType3(uint32_t Type) const {
104     return (unsigned)((Type >> R_TYPE3_SHIFT) & 0xff);
105   }
getRSsym(uint32_t Type)106   uint8_t getRSsym(uint32_t Type) const {
107     return (unsigned)((Type >> R_SSYM_SHIFT) & 0xff);
108   }
109 
110   // N64 relocation type setting
setRType(unsigned Value,unsigned Type)111   unsigned setRType(unsigned Value, unsigned Type) const {
112     return ((Type & R_TYPE_MASK) | ((Value & 0xff) << R_TYPE_SHIFT));
113   }
setRType2(unsigned Value,unsigned Type)114   unsigned setRType2(unsigned Value, unsigned Type) const {
115     return (Type & R_TYPE2_MASK) | ((Value & 0xff) << R_TYPE2_SHIFT);
116   }
setRType3(unsigned Value,unsigned Type)117   unsigned setRType3(unsigned Value, unsigned Type) const {
118     return (Type & R_TYPE3_MASK) | ((Value & 0xff) << R_TYPE3_SHIFT);
119   }
setRSsym(unsigned Value,unsigned Type)120   unsigned setRSsym(unsigned Value, unsigned Type) const {
121     return (Type & R_SSYM_MASK) | ((Value & 0xff) << R_SSYM_SHIFT);
122   }
123 };
124 
125 /// \brief Construct a new ELF writer instance.
126 ///
127 /// \param MOTW - The target specific ELF writer subclass.
128 /// \param OS - The stream to write to.
129 /// \returns The constructed object writer.
130 MCObjectWriter *createELFObjectWriter(MCELFObjectTargetWriter *MOTW,
131                                       raw_pwrite_stream &OS,
132                                       bool IsLittleEndian);
133 } // End llvm namespace
134 
135 #endif
136