ARMRelocator.h revision 37b74a387bb3993387029859c2d9d051c41c724e 
1//===-  ARMRelocator.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 TARGET_ARM_ARMRELOCATOR_H_
10#define TARGET_ARM_ARMRELOCATOR_H_
11
12#include "mcld/LD/Relocator.h"
13#include "mcld/Target/GOT.h"
14#include "mcld/Target/KeyEntryMap.h"
15#include "ARMLDBackend.h"
16
17namespace mcld {
18
19/** \class ARMRelocator
20 *  \brief ARMRelocator creates and destroys the ARM relocations.
21 *
22 */
23class ARMRelocator : public Relocator {
24 public:
25  typedef KeyEntryMap<ResolveInfo, ARMGOTEntry> SymGOTMap;
26  typedef KeyEntryMap<ResolveInfo, ARMPLT1> SymPLTMap;
27
28  /** \enum ReservedEntryType
29   *  \brief The reserved entry type of reserved space in ResolveInfo.
30   *
31   *  This is used for sacnRelocation to record what kinds of entries are
32   *  reserved for this resolved symbol In ARM, there are three kinds of
33   *  entries, GOT, PLT, and dynamic reloction.
34   *
35   *  bit:  3     2     1     0
36   *   |    | PLT | GOT | Rel |
37   *
38   *  value    Name         - Description
39   *
40   *  0000     None         - no reserved entry
41   *  0001     ReserveRel   - reserve an dynamic relocation entry
42   *  0010     ReserveGOT   - reserve an GOT entry
43   *  0100     ReservePLT   - reserve an PLT entry and the corresponding GOT,
44   *
45   */
46  enum ReservedEntryType {
47    None = 0,
48    ReserveRel = 1,
49    ReserveGOT = 2,
50    ReservePLT = 4,
51  };
52
53  /** \enum EntryValue
54   *  \brief The value of the entries. The symbol value will be decided at after
55   *  layout, so we mark the entry during scanRelocation and fill up the actual
56   *  value when applying relocations.
57   */
58  enum EntryValue { Default = 0, SymVal = 1 };
59
60 public:
61  ARMRelocator(ARMGNULDBackend& pParent, const LinkerConfig& pConfig);
62  ~ARMRelocator();
63
64  Result applyRelocation(Relocation& pRelocation);
65
66  ARMGNULDBackend& getTarget() { return m_Target; }
67
68  const ARMGNULDBackend& getTarget() const { return m_Target; }
69
70  const char* getName(Relocation::Type pType) const;
71
72  Size getSize(Relocation::Type pType) const;
73
74  const SymGOTMap& getSymGOTMap() const { return m_SymGOTMap; }
75  SymGOTMap& getSymGOTMap() { return m_SymGOTMap; }
76
77  const SymPLTMap& getSymPLTMap() const { return m_SymPLTMap; }
78  SymPLTMap& getSymPLTMap() { return m_SymPLTMap; }
79
80  const SymGOTMap& getSymGOTPLTMap() const { return m_SymGOTPLTMap; }
81  SymGOTMap& getSymGOTPLTMap() { return m_SymGOTPLTMap; }
82
83  /// scanRelocation - determine the empty entries are needed or not and create
84  /// the empty entries if needed.
85  /// For ARM, following entries are check to create:
86  /// - GOT entry (for .got section)
87  /// - PLT entry (for .plt section)
88  /// - dynamin relocation entries (for .rel.plt and .rel.dyn sections)
89  void scanRelocation(Relocation& pReloc,
90                      IRBuilder& pBuilder,
91                      Module& pModule,
92                      LDSection& pSection,
93                      Input& pInput);
94
95  /// mayHaveFunctionPointerAccess - check if the given reloc would possibly
96  /// access a function pointer.
97  virtual bool mayHaveFunctionPointerAccess(const Relocation& pReloc) const;
98
99  /// getDebugStringOffset - get the offset from the relocation target. This is
100  /// used to get the debug string offset.
101  uint32_t getDebugStringOffset(Relocation& pReloc) const;
102
103  /// applyDebugStringOffset - apply the relocation target to specific offset.
104  /// This is used to set the debug string offset.
105  void applyDebugStringOffset(Relocation& pReloc, uint32_t pOffset);
106
107 private:
108  void scanLocalReloc(Relocation& pReloc, const LDSection& pSection);
109
110  void scanGlobalReloc(Relocation& pReloc,
111                       IRBuilder& pBuilder,
112                       const LDSection& pSection);
113
114  void checkValidReloc(Relocation& pReloc) const;
115
116  /// addCopyReloc - add a copy relocation into .rel.dyn for pSym
117  /// @param pSym - A resolved copy symbol that defined in BSS section
118  void addCopyReloc(ResolveInfo& pSym);
119
120  /// defineSymbolforCopyReloc - allocate a space in BSS section and
121  /// and force define the copy of pSym to BSS section
122  /// @return the output LDSymbol of the copy symbol
123  LDSymbol& defineSymbolforCopyReloc(IRBuilder& pLinker,
124                                     const ResolveInfo& pSym);
125
126 private:
127  ARMGNULDBackend& m_Target;
128  SymGOTMap m_SymGOTMap;
129  SymPLTMap m_SymPLTMap;
130  SymGOTMap m_SymGOTPLTMap;
131};
132
133}  // namespace mcld
134
135#endif  // TARGET_ARM_ARMRELOCATOR_H_
136