1 //===-- RuntimeDyldELF.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 // ELF support for MC-JIT runtime dynamic linker.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDELF_H
15 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDELF_H
16 
17 #include "RuntimeDyldImpl.h"
18 #include "llvm/ADT/DenseMap.h"
19 
20 using namespace llvm;
21 
22 namespace llvm {
23 namespace object {
24 class ELFObjectFileBase;
25 }
26 
27 class RuntimeDyldELF : public RuntimeDyldImpl {
28 
29   void resolveRelocation(const SectionEntry &Section, uint64_t Offset,
30                          uint64_t Value, uint32_t Type, int64_t Addend,
31                          uint64_t SymOffset = 0, SID SectionID = 0);
32 
33   void resolveX86_64Relocation(const SectionEntry &Section, uint64_t Offset,
34                                uint64_t Value, uint32_t Type, int64_t Addend,
35                                uint64_t SymOffset);
36 
37   void resolveX86Relocation(const SectionEntry &Section, uint64_t Offset,
38                             uint32_t Value, uint32_t Type, int32_t Addend);
39 
40   void resolveAArch64Relocation(const SectionEntry &Section, uint64_t Offset,
41                                 uint64_t Value, uint32_t Type, int64_t Addend);
42 
43   bool resolveAArch64ShortBranch(unsigned SectionID, relocation_iterator RelI,
44                                  const RelocationValueRef &Value);
45 
46   void resolveARMRelocation(const SectionEntry &Section, uint64_t Offset,
47                             uint32_t Value, uint32_t Type, int32_t Addend);
48 
49   void resolvePPC32Relocation(const SectionEntry &Section, uint64_t Offset,
50                               uint64_t Value, uint32_t Type, int64_t Addend);
51 
52   void resolvePPC64Relocation(const SectionEntry &Section, uint64_t Offset,
53                               uint64_t Value, uint32_t Type, int64_t Addend);
54 
55   void resolveSystemZRelocation(const SectionEntry &Section, uint64_t Offset,
56                                 uint64_t Value, uint32_t Type, int64_t Addend);
57 
58   unsigned getMaxStubSize() override {
59     if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be)
60       return 20; // movz; movk; movk; movk; br
61     if (Arch == Triple::arm || Arch == Triple::thumb)
62       return 8; // 32-bit instruction and 32-bit address
63     else if (IsMipsO32ABI)
64       return 16;
65     else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le)
66       return 44;
67     else if (Arch == Triple::x86_64)
68       return 6; // 2-byte jmp instruction + 32-bit relative address
69     else if (Arch == Triple::systemz)
70       return 16;
71     else
72       return 0;
73   }
74 
75   unsigned getStubAlignment() override {
76     if (Arch == Triple::systemz)
77       return 8;
78     else
79       return 1;
80   }
81 
82   void setMipsABI(const ObjectFile &Obj) override;
83 
84   Error findPPC64TOCSection(const ELFObjectFileBase &Obj,
85                             ObjSectionToIDMap &LocalSections,
86                             RelocationValueRef &Rel);
87   Error findOPDEntrySection(const ELFObjectFileBase &Obj,
88                             ObjSectionToIDMap &LocalSections,
89                             RelocationValueRef &Rel);
90 protected:
91   size_t getGOTEntrySize();
92 
93 private:
94   SectionEntry &getSection(unsigned SectionID) { return Sections[SectionID]; }
95 
96   // Allocate no GOT entries for use in the given section.
97   uint64_t allocateGOTEntries(unsigned SectionID, unsigned no);
98 
99   // Resolve the relvative address of GOTOffset in Section ID and place
100   // it at the given Offset
101   void resolveGOTOffsetRelocation(unsigned SectionID, uint64_t Offset,
102                                   uint64_t GOTOffset);
103 
104   // For a GOT entry referenced from SectionID, compute a relocation entry
105   // that will place the final resolved value in the GOT slot
106   RelocationEntry computeGOTOffsetRE(unsigned SectionID,
107                                      uint64_t GOTOffset,
108                                      uint64_t SymbolOffset,
109                                      unsigned Type);
110 
111   // Compute the address in memory where we can find the placeholder
112   void *computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const;
113 
114   // Split out common case for createing the RelocationEntry for when the relocation requires
115   // no particular advanced processing.
116   void processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value);
117 
118   // Return matching *LO16 relocation (Mips specific)
119   uint32_t getMatchingLoRelocation(uint32_t RelType,
120                                    bool IsLocal = false) const;
121 
122   // The tentative ID for the GOT section
123   unsigned GOTSectionID;
124 
125   // Records the current number of allocated slots in the GOT
126   // (This would be equivalent to GOTEntries.size() were it not for relocations
127   // that consume more than one slot)
128   unsigned CurrentGOTIndex;
129 
130 protected:
131   // A map from section to a GOT section that has entries for section's GOT
132   // relocations. (Mips64 specific)
133   DenseMap<SID, SID> SectionToGOTMap;
134 
135 private:
136   // A map to avoid duplicate got entries (Mips64 specific)
137   StringMap<uint64_t> GOTSymbolOffsets;
138 
139   // *HI16 relocations will be added for resolving when we find matching
140   // *LO16 part. (Mips specific)
141   SmallVector<std::pair<RelocationValueRef, RelocationEntry>, 8> PendingRelocs;
142 
143   // When a module is loaded we save the SectionID of the EH frame section
144   // in a table until we receive a request to register all unregistered
145   // EH frame sections with the memory manager.
146   SmallVector<SID, 2> UnregisteredEHFrameSections;
147   SmallVector<SID, 2> RegisteredEHFrameSections;
148 
149   bool relocationNeedsStub(const RelocationRef &R) const override;
150 
151 public:
152   RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr,
153                  JITSymbolResolver &Resolver);
154   ~RuntimeDyldELF() override;
155 
156   static std::unique_ptr<RuntimeDyldELF>
157   create(Triple::ArchType Arch, RuntimeDyld::MemoryManager &MemMgr,
158          JITSymbolResolver &Resolver);
159 
160   std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
161   loadObject(const object::ObjectFile &O) override;
162 
163   void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override;
164   Expected<relocation_iterator>
165   processRelocationRef(unsigned SectionID, relocation_iterator RelI,
166                        const ObjectFile &Obj,
167                        ObjSectionToIDMap &ObjSectionToID,
168                        StubMap &Stubs) override;
169   bool isCompatibleFile(const object::ObjectFile &Obj) const override;
170   void registerEHFrames() override;
171   void deregisterEHFrames() override;
172   Error finalizeLoad(const ObjectFile &Obj,
173                      ObjSectionToIDMap &SectionMap) override;
174 };
175 
176 } // end namespace llvm
177 
178 #endif
179