1//===- MipsLDBackend.h ----------------------------------------------------===//
2//
3//                     The MCLinker Project
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9#ifndef MIPS_LDBACKEND_H
10#define MIPS_LDBACKEND_H
11#include "mcld/Target/GNULDBackend.h"
12#include "MipsELFDynamic.h"
13#include "MipsGOT.h"
14
15namespace mcld {
16
17class MCLinker;
18class OutputRelocSection;
19class SectionMap;
20
21//===----------------------------------------------------------------------===//
22/// MipsGNULDBackend - linker backend of Mips target of GNU ELF format
23///
24class MipsGNULDBackend : public GNULDBackend
25{
26public:
27  enum ReservedEntryType {
28    None          = 0,  // no reserved entry
29    ReserveRel    = 1,  // reserve a dynamic relocation entry
30    ReserveGot    = 2,  // reserve a GOT entry
31    ReserveGpDisp = 8   // reserve _gp_disp symbol
32  };
33
34public:
35  MipsGNULDBackend();
36  ~MipsGNULDBackend();
37
38public:
39  /// initTargetSectionMap - initialize target dependent section mapping.
40  bool initTargetSectionMap(SectionMap& pSectionMap);
41
42  /// initTargetSections - initialize target dependent sections in output
43  void initTargetSections(MCLinker& pLinker);
44
45  /// initTargetSymbols - initialize target dependent symbols in output.
46  void initTargetSymbols(MCLinker& pLinker, const Output& pOutput);
47
48  /// initRelocFactory - create and initialize RelocationFactory.
49  bool initRelocFactory(const MCLinker& pLinker);
50
51  /// getRelocFactory - return relocation factory.
52  RelocationFactory* getRelocFactory();
53
54  /// scanRelocation - determine the empty entries are needed or not and
55  /// create the empty entries if needed.
56  /// For Mips, the GOT, GP, and dynamic relocation entries are check to create.
57  void scanRelocation(Relocation& pReloc,
58                      const LDSymbol& pInputSym,
59                      MCLinker& pLinker,
60                      const MCLDInfo& pLDInfo,
61                      const Output& pOutput,
62                      const LDSection& pSection);
63
64  uint32_t machine() const;
65
66  /// OSABI - the value of e_ident[EI_OSABI]
67  uint8_t OSABI() const;
68
69  /// ABIVersion - the value of e_ident[EI_ABIVRESION]
70  uint8_t ABIVersion() const;
71
72  /// flags - the value of ElfXX_Ehdr::e_flags
73  uint64_t flags() const;
74
75  bool isLittleEndian() const;
76
77  unsigned int bitclass() const;
78
79  uint64_t defaultTextSegmentAddr() const;
80
81  /// abiPageSize - the abi page size of the target machine
82  uint64_t abiPageSize(const MCLDInfo& pInfo) const;
83
84  /// preLayout - Backend can do any needed modification before layout
85  void doPreLayout(const Output& pOutput,
86                   const MCLDInfo& pInfo,
87                   MCLinker& pLinker);
88
89  /// postLayout -Backend can do any needed modification after layout
90  void doPostLayout(const Output& pOutput,
91                    const MCLDInfo& pInfo,
92                    MCLinker& pLinker);
93
94  /// dynamic - the dynamic section of the target machine.
95  /// Use co-variant return type to return its own dynamic section.
96  MipsELFDynamic& dynamic();
97
98  /// dynamic - the dynamic section of the target machine.
99  /// Use co-variant return type to return its own dynamic section.
100  const MipsELFDynamic& dynamic() const;
101
102  /// emitSectionData - write out the section data into the memory region.
103  /// When writers get a LDSection whose kind is LDFileFormat::Target, writers
104  /// call back target backend to emit the data.
105  ///
106  /// Backends handle the target-special tables (plt, gp,...) by themselves.
107  /// Backend can put the data of the tables in SectionData directly
108  ///  - LDSection.getSectionData can get the section data.
109  /// Or, backend can put the data into special data structure
110  ///  - backend can maintain its own map<LDSection, table> to get the table
111  /// from given LDSection.
112  ///
113  /// @param pOutput - the output file
114  /// @param pSection - the given LDSection
115  /// @param pInfo - all options in the command line.
116  /// @param pLayout - for comouting the size of fragment
117  /// @param pRegion - the region to write out data
118  /// @return the size of the table in the file.
119  uint64_t emitSectionData(const Output& pOutput,
120                           const LDSection& pSection,
121                           const MCLDInfo& pInfo,
122                           const Layout& pLayout,
123                           MemoryRegion& pRegion) const;
124
125  /// emitNamePools - emit dynamic name pools - .dyntab, .dynstr, .hash
126  virtual void emitDynNamePools(Output& pOutput,
127                                SymbolCategory& pSymbols,
128                                const Layout& pLayout,
129                                const MCLDInfo& pLDInfo);
130
131  MipsGOT& getGOT();
132  const MipsGOT& getGOT() const;
133
134  OutputRelocSection& getRelDyn();
135  const OutputRelocSection& getRelDyn() const;
136
137  /// getTargetSectionOrder - compute the layout order of ARM target sections
138  unsigned int getTargetSectionOrder(const Output& pOutput,
139                                     const LDSection& pSectHdr,
140                                     const MCLDInfo& pInfo) const;
141
142  /// finalizeSymbol - finalize the symbol value
143  bool finalizeTargetSymbols(MCLinker& pLinker, const Output& pOutput);
144
145  /// allocateCommonSymbols - allocate common symbols in the corresponding
146  /// sections.
147  bool allocateCommonSymbols(const MCLDInfo& pLDInfo, MCLinker& pLinker) const;
148
149private:
150  void scanLocalReloc(Relocation& pReloc,
151                      const LDSymbol& pInputSym,
152                      MCLinker& pLinker,
153                      const MCLDInfo& pLDInfo,
154                      const Output& pOutput);
155
156  void scanGlobalReloc(Relocation& pReloc,
157                      const LDSymbol& pInputSym,
158                      MCLinker& pLinker,
159                      const MCLDInfo& pLDInfo,
160                      const Output& pOutput);
161
162  void createGOT(MCLinker& pLinker, const Output& pOutput);
163  void createRelDyn(MCLinker& pLinker, const Output& pOutput);
164
165  /// updateAddend - update addend value of the relocation if the
166  /// the target symbol is a section symbol. Addend is the offset
167  /// in the section. This value should be updated after section
168  /// merged.
169  void updateAddend(Relocation& pReloc,
170                    const LDSymbol& pInputSym,
171                    const Layout& pLayout) const;
172
173private:
174  RelocationFactory* m_pRelocFactory;
175
176  MipsGOT* m_pGOT;                      // .got
177  OutputRelocSection* m_pRelDyn;        // .rel.dyn
178
179  MipsELFDynamic* m_pDynamic;
180  LDSymbol* m_pGOTSymbol;
181  LDSymbol* m_pGpDispSymbol;
182
183  std::vector<LDSymbol*> m_GlobalGOTSyms;
184
185private:
186  /// isGlobalGOTSymbol - return true if the symbol is the global GOT entry.
187  bool isGlobalGOTSymbol(const LDSymbol& pSymbol) const;
188  /// emitDynamicSymbol - emit dynamic symbol.
189  void emitDynamicSymbol(llvm::ELF::Elf32_Sym& sym32,
190                         Output& pOutput,
191                         LDSymbol& pSymbol,
192                         const Layout& pLayout,
193                         char* strtab,
194                         size_t strtabsize,
195                         size_t symtabIdx);
196};
197
198} // namespace of mcld
199
200#endif
201
202