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