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 
24 class RuntimeDyldELF : public RuntimeDyldImpl {
25 
26   void resolveRelocation(const SectionEntry &Section, uint64_t Offset,
27                          uint64_t Value, uint32_t Type, int64_t Addend,
28                          uint64_t SymOffset = 0, SID SectionID = 0);
29 
30   void resolveX86_64Relocation(const SectionEntry &Section, uint64_t Offset,
31                                uint64_t Value, uint32_t Type, int64_t Addend,
32                                uint64_t SymOffset);
33 
34   void resolveX86Relocation(const SectionEntry &Section, uint64_t Offset,
35                             uint32_t Value, uint32_t Type, int32_t Addend);
36 
37   void resolveAArch64Relocation(const SectionEntry &Section, uint64_t Offset,
38                                 uint64_t Value, uint32_t Type, int64_t Addend);
39 
40   void resolveARMRelocation(const SectionEntry &Section, uint64_t Offset,
41                             uint32_t Value, uint32_t Type, int32_t Addend);
42 
43   void resolveMIPSRelocation(const SectionEntry &Section, uint64_t Offset,
44                              uint32_t Value, uint32_t Type, int32_t Addend);
45 
46   void resolvePPC32Relocation(const SectionEntry &Section, uint64_t Offset,
47                               uint64_t Value, uint32_t Type, int64_t Addend);
48 
49   void resolvePPC64Relocation(const SectionEntry &Section, uint64_t Offset,
50                               uint64_t Value, uint32_t Type, int64_t Addend);
51 
52   void resolveSystemZRelocation(const SectionEntry &Section, uint64_t Offset,
53                                 uint64_t Value, uint32_t Type, int64_t Addend);
54 
55   void resolveMIPS64Relocation(const SectionEntry &Section, uint64_t Offset,
56                                uint64_t Value, uint32_t Type, int64_t Addend,
57                                uint64_t SymOffset, SID SectionID);
58 
59   int64_t evaluateMIPS64Relocation(const SectionEntry &Section,
60                                    uint64_t Offset, uint64_t Value,
61                                    uint32_t Type,  int64_t Addend,
62                                    uint64_t SymOffset, SID SectionID);
63 
64   void applyMIPS64Relocation(uint8_t *TargetPtr, int64_t CalculatedValue,
65                              uint32_t Type);
66 
getMaxStubSize()67   unsigned getMaxStubSize() override {
68     if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be)
69       return 20; // movz; movk; movk; movk; br
70     if (Arch == Triple::arm || Arch == Triple::thumb)
71       return 8; // 32-bit instruction and 32-bit address
72     else if (IsMipsO32ABI)
73       return 16;
74     else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le)
75       return 44;
76     else if (Arch == Triple::x86_64)
77       return 6; // 2-byte jmp instruction + 32-bit relative address
78     else if (Arch == Triple::systemz)
79       return 16;
80     else
81       return 0;
82   }
83 
getStubAlignment()84   unsigned getStubAlignment() override {
85     if (Arch == Triple::systemz)
86       return 8;
87     else
88       return 1;
89   }
90 
91   void setMipsABI(const ObjectFile &Obj) override;
92 
93   void findPPC64TOCSection(const ELFObjectFileBase &Obj,
94                            ObjSectionToIDMap &LocalSections,
95                            RelocationValueRef &Rel);
96   void findOPDEntrySection(const ELFObjectFileBase &Obj,
97                            ObjSectionToIDMap &LocalSections,
98                            RelocationValueRef &Rel);
99 
100   size_t getGOTEntrySize();
101 
getSection(unsigned SectionID)102   SectionEntry &getSection(unsigned SectionID) { return Sections[SectionID]; }
103 
104   // Allocate no GOT entries for use in the given section.
105   uint64_t allocateGOTEntries(unsigned SectionID, unsigned no);
106 
107   // Resolve the relvative address of GOTOffset in Section ID and place
108   // it at the given Offset
109   void resolveGOTOffsetRelocation(unsigned SectionID, uint64_t Offset,
110                                   uint64_t GOTOffset);
111 
112   // For a GOT entry referenced from SectionID, compute a relocation entry
113   // that will place the final resolved value in the GOT slot
114   RelocationEntry computeGOTOffsetRE(unsigned SectionID,
115                                      uint64_t GOTOffset,
116                                      uint64_t SymbolOffset,
117                                      unsigned Type);
118 
119   // Compute the address in memory where we can find the placeholder
120   void *computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const;
121 
122   // Split out common case for createing the RelocationEntry for when the relocation requires
123   // no particular advanced processing.
124   void processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value);
125 
126   // Return matching *LO16 relocation (Mips specific)
127   uint32_t getMatchingLoRelocation(uint32_t RelType,
128                                    bool IsLocal = false) const;
129 
130   // The tentative ID for the GOT section
131   unsigned GOTSectionID;
132 
133   // Records the current number of allocated slots in the GOT
134   // (This would be equivalent to GOTEntries.size() were it not for relocations
135   // that consume more than one slot)
136   unsigned CurrentGOTIndex;
137 
138   // A map from section to a GOT section that has entries for section's GOT
139   // relocations. (Mips64 specific)
140   DenseMap<SID, SID> SectionToGOTMap;
141 
142   // A map to avoid duplicate got entries (Mips64 specific)
143   StringMap<uint64_t> GOTSymbolOffsets;
144 
145   // *HI16 relocations will be added for resolving when we find matching
146   // *LO16 part. (Mips specific)
147   SmallVector<std::pair<RelocationValueRef, RelocationEntry>, 8> PendingRelocs;
148 
149   // When a module is loaded we save the SectionID of the EH frame section
150   // in a table until we receive a request to register all unregistered
151   // EH frame sections with the memory manager.
152   SmallVector<SID, 2> UnregisteredEHFrameSections;
153   SmallVector<SID, 2> RegisteredEHFrameSections;
154 
155   bool relocationNeedsStub(const RelocationRef &R) const override;
156 
157 public:
158   RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr,
159                  RuntimeDyld::SymbolResolver &Resolver);
160   ~RuntimeDyldELF() override;
161 
162   std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
163   loadObject(const object::ObjectFile &O) override;
164 
165   void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override;
166   relocation_iterator
167   processRelocationRef(unsigned SectionID, relocation_iterator RelI,
168                        const ObjectFile &Obj,
169                        ObjSectionToIDMap &ObjSectionToID,
170                        StubMap &Stubs) override;
171   bool isCompatibleFile(const object::ObjectFile &Obj) const override;
172   void registerEHFrames() override;
173   void deregisterEHFrames() override;
174   void finalizeLoad(const ObjectFile &Obj,
175                     ObjSectionToIDMap &SectionMap) override;
176 };
177 
178 } // end namespace llvm
179 
180 #endif
181