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      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 
     17 namespace mcld {
     18 
     19 /** \class ARMRelocator
     20  *  \brief ARMRelocator creates and destroys the ARM relocations.
     21  *
     22  */
     23 class 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