1 //===-- RuntimeDyldMachO.h - Run-time dynamic linker for MC-JIT ---*- C++ -*-=//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // MachO support for MC-JIT runtime dynamic linker.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDMACHO_H
15 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDMACHO_H
16 
17 #include "RuntimeDyldImpl.h"
18 #include "llvm/Object/MachO.h"
19 #include "llvm/Support/Format.h"
20 
21 #define DEBUG_TYPE "dyld"
22 
23 using namespace llvm;
24 using namespace llvm::object;
25 
26 namespace llvm {
27 class RuntimeDyldMachO : public RuntimeDyldImpl {
28 protected:
29   struct SectionOffsetPair {
30     unsigned SectionID;
31     uint64_t Offset;
32   };
33 
34   struct EHFrameRelatedSections {
EHFrameRelatedSectionsEHFrameRelatedSections35     EHFrameRelatedSections()
36         : EHFrameSID(RTDYLD_INVALID_SECTION_ID),
37           TextSID(RTDYLD_INVALID_SECTION_ID),
38           ExceptTabSID(RTDYLD_INVALID_SECTION_ID) {}
39 
EHFrameRelatedSectionsEHFrameRelatedSections40     EHFrameRelatedSections(SID EH, SID T, SID Ex)
41         : EHFrameSID(EH), TextSID(T), ExceptTabSID(Ex) {}
42     SID EHFrameSID;
43     SID TextSID;
44     SID ExceptTabSID;
45   };
46 
47   // When a module is loaded we save the SectionID of the EH frame section
48   // in a table until we receive a request to register all unregistered
49   // EH frame sections with the memory manager.
50   SmallVector<EHFrameRelatedSections, 2> UnregisteredEHFrameSections;
51 
RuntimeDyldMachO(RuntimeDyld::MemoryManager & MemMgr,RuntimeDyld::SymbolResolver & Resolver)52   RuntimeDyldMachO(RuntimeDyld::MemoryManager &MemMgr,
53                    RuntimeDyld::SymbolResolver &Resolver)
54       : RuntimeDyldImpl(MemMgr, Resolver) {}
55 
56   /// This convenience method uses memcpy to extract a contiguous addend (the
57   /// addend size and offset are taken from the corresponding fields of the RE).
58   int64_t memcpyAddend(const RelocationEntry &RE) const;
59 
60   /// Given a relocation_iterator for a non-scattered relocation, construct a
61   /// RelocationEntry and fill in the common fields. The 'Addend' field is *not*
62   /// filled in, since immediate encodings are highly target/opcode specific.
63   /// For targets/opcodes with simple, contiguous immediates (e.g. X86) the
64   /// memcpyAddend method can be used to read the immediate.
getRelocationEntry(unsigned SectionID,const ObjectFile & BaseTObj,const relocation_iterator & RI)65   RelocationEntry getRelocationEntry(unsigned SectionID,
66                                      const ObjectFile &BaseTObj,
67                                      const relocation_iterator &RI) const {
68     const MachOObjectFile &Obj =
69       static_cast<const MachOObjectFile &>(BaseTObj);
70     MachO::any_relocation_info RelInfo =
71       Obj.getRelocation(RI->getRawDataRefImpl());
72 
73     bool IsPCRel = Obj.getAnyRelocationPCRel(RelInfo);
74     unsigned Size = Obj.getAnyRelocationLength(RelInfo);
75     uint64_t Offset;
76     RI->getOffset(Offset);
77     MachO::RelocationInfoType RelType =
78       static_cast<MachO::RelocationInfoType>(Obj.getAnyRelocationType(RelInfo));
79 
80     return RelocationEntry(SectionID, Offset, RelType, 0, IsPCRel, Size);
81   }
82 
83   /// Construct a RelocationValueRef representing the relocation target.
84   /// For Symbols in known sections, this will return a RelocationValueRef
85   /// representing a (SectionID, Offset) pair.
86   /// For Symbols whose section is not known, this will return a
87   /// (SymbolName, Offset) pair, where the Offset is taken from the instruction
88   /// immediate (held in RE.Addend).
89   /// In both cases the Addend field is *NOT* fixed up to be PC-relative. That
90   /// should be done by the caller where appropriate by calling makePCRel on
91   /// the RelocationValueRef.
92   RelocationValueRef getRelocationValueRef(const ObjectFile &BaseTObj,
93                                            const relocation_iterator &RI,
94                                            const RelocationEntry &RE,
95                                            ObjSectionToIDMap &ObjSectionToID);
96 
97   /// Make the RelocationValueRef addend PC-relative.
98   void makeValueAddendPCRel(RelocationValueRef &Value,
99                             const ObjectFile &BaseTObj,
100                             const relocation_iterator &RI,
101                             unsigned OffsetToNextPC);
102 
103   /// Dump information about the relocation entry (RE) and resolved value.
104   void dumpRelocationToResolve(const RelocationEntry &RE, uint64_t Value) const;
105 
106   // Return a section iterator for the section containing the given address.
107   static section_iterator getSectionByAddress(const MachOObjectFile &Obj,
108                                               uint64_t Addr);
109 
110 
111   // Populate __pointers section.
112   void populateIndirectSymbolPointersSection(const MachOObjectFile &Obj,
113                                              const SectionRef &PTSection,
114                                              unsigned PTSectionID);
115 
116 public:
117 
118   /// Create a RuntimeDyldMachO instance for the given target architecture.
119   static std::unique_ptr<RuntimeDyldMachO>
120   create(Triple::ArchType Arch,
121          RuntimeDyld::MemoryManager &MemMgr,
122          RuntimeDyld::SymbolResolver &Resolver);
123 
124   std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
125   loadObject(const object::ObjectFile &O) override;
126 
getSection(unsigned SectionID)127   SectionEntry &getSection(unsigned SectionID) { return Sections[SectionID]; }
128 
129   bool isCompatibleFile(const object::ObjectFile &Obj) const override;
130 };
131 
132 /// RuntimeDyldMachOTarget - Templated base class for generic MachO linker
133 /// algorithms and data structures.
134 ///
135 /// Concrete, target specific sub-classes can be accessed via the impl()
136 /// methods. (i.e. the RuntimeDyldMachO hierarchy uses the Curiously
137 /// Recurring Template Idiom). Concrete subclasses for each target
138 /// can be found in ./Targets.
139 template <typename Impl>
140 class RuntimeDyldMachOCRTPBase : public RuntimeDyldMachO {
141 private:
impl()142   Impl &impl() { return static_cast<Impl &>(*this); }
impl()143   const Impl &impl() const { return static_cast<const Impl &>(*this); }
144 
145   unsigned char *processFDE(unsigned char *P, int64_t DeltaForText,
146                             int64_t DeltaForEH);
147 
148 public:
RuntimeDyldMachOCRTPBase(RuntimeDyld::MemoryManager & MemMgr,RuntimeDyld::SymbolResolver & Resolver)149   RuntimeDyldMachOCRTPBase(RuntimeDyld::MemoryManager &MemMgr,
150                            RuntimeDyld::SymbolResolver &Resolver)
151     : RuntimeDyldMachO(MemMgr, Resolver) {}
152 
153   void finalizeLoad(const ObjectFile &Obj,
154                     ObjSectionToIDMap &SectionMap) override;
155   void registerEHFrames() override;
156 };
157 
158 } // end namespace llvm
159 
160 #undef DEBUG_TYPE
161 
162 #endif
163