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      1 //===-  AArch64Relocator.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_AARCH64_AARCH64RELOCATOR_H_
     10 #define TARGET_AARCH64_AARCH64RELOCATOR_H_
     11 
     12 #include "mcld/LD/Relocator.h"
     13 #include "mcld/Target/GOT.h"
     14 #include "mcld/Target/KeyEntryMap.h"
     15 #include "AArch64LDBackend.h"
     16 
     17 namespace mcld {
     18 
     19 /** \class AArch64Relocator
     20  *  \brief AArch64Relocator creates and destroys the AArch64 relocations.
     21  *
     22  */
     23 class AArch64Relocator : public Relocator {
     24  public:
     25   typedef KeyEntryMap<ResolveInfo, AArch64GOTEntry> SymGOTMap;
     26   typedef KeyEntryMap<ResolveInfo, AArch64PLT1> SymPLTMap;
     27   typedef KeyEntryMap<Relocation, Relocation> RelRelMap;
     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 AArch64, 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 { Default = 0, SymVal = 1 };
     60 
     61   enum {
     62     // mcld internal relocation to rewrite an instruction.
     63     R_AARCH64_REWRITE_INSN = 1,
     64   };
     65 
     66  public:
     67   AArch64Relocator(AArch64GNULDBackend& pParent, const LinkerConfig& pConfig);
     68   ~AArch64Relocator();
     69 
     70   Result applyRelocation(Relocation& pRelocation);
     71 
     72   AArch64GNULDBackend& getTarget() { return m_Target; }
     73 
     74   const AArch64GNULDBackend& getTarget() const { 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   const RelRelMap& getRelRelMap() const { return m_RelRelMap; }
     90   RelRelMap& getRelRelMap() { return m_RelRelMap; }
     91 
     92   /// scanRelocation - determine the empty entries are needed or not and create
     93   /// the empty entries if needed.
     94   /// For AArch64, following entries are check to create:
     95   /// - GOT entry (for .got section)
     96   /// - PLT entry (for .plt section)
     97   /// - dynamin relocation entries (for .rel.plt and .rel.dyn sections)
     98   void scanRelocation(Relocation& pReloc,
     99                       IRBuilder& pBuilder,
    100                       Module& pModule,
    101                       LDSection& pSection,
    102                       Input& pInput);
    103 
    104   /// mayHaveFunctionPointerAccess - check if the given reloc would possibly
    105   /// access a function pointer.
    106   virtual bool mayHaveFunctionPointerAccess(const Relocation& pReloc) const;
    107 
    108   /// getDebugStringOffset - get the offset from the relocation target. This is
    109   /// used to get the debug string offset.
    110   uint32_t getDebugStringOffset(Relocation& pReloc) const;
    111 
    112   /// applyDebugStringOffset - apply the relocation target to specific offset.
    113   /// This is used to set the debug string offset.
    114   void applyDebugStringOffset(Relocation& pReloc, uint32_t pOffset);
    115 
    116  private:
    117   void scanLocalReloc(Relocation& pReloc, const LDSection& pSection);
    118 
    119   void scanGlobalReloc(Relocation& pReloc,
    120                        IRBuilder& pBuilder,
    121                        const LDSection& pSection);
    122 
    123   /// addCopyReloc - add a copy relocation into .rel.dyn for pSym
    124   /// @param pSym - A resolved copy symbol that defined in BSS section
    125   void addCopyReloc(ResolveInfo& pSym);
    126 
    127   /// defineSymbolforCopyReloc - allocate a space in BSS section and
    128   /// and force define the copy of pSym to BSS section
    129   /// @return the output LDSymbol of the copy symbol
    130   LDSymbol& defineSymbolforCopyReloc(IRBuilder& pLinker,
    131                                      const ResolveInfo& pSym);
    132 
    133  private:
    134   AArch64GNULDBackend& m_Target;
    135   SymGOTMap m_SymGOTMap;
    136   SymPLTMap m_SymPLTMap;
    137   SymGOTMap m_SymGOTPLTMap;
    138   RelRelMap m_RelRelMap;
    139 };
    140 
    141 }  // namespace mcld
    142 
    143 #endif  // TARGET_AARCH64_AARCH64RELOCATOR_H_
    144