1 //===-- RuntimeDyldELF.h - Run-time dynamic linker for MC-JIT ---*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // ELF support for MC-JIT runtime dynamic linker. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDELF_H 14 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDELF_H 15 16 #include "RuntimeDyldImpl.h" 17 #include "llvm/ADT/DenseMap.h" 18 19 using namespace llvm; 20 21 namespace llvm { 22 namespace object { 23 class ELFObjectFileBase; 24 } 25 26 class RuntimeDyldELF : public RuntimeDyldImpl { 27 28 void resolveRelocation(const SectionEntry &Section, uint64_t Offset, 29 uint64_t Value, uint32_t Type, int64_t Addend, 30 uint64_t SymOffset = 0, SID SectionID = 0); 31 32 void resolveX86_64Relocation(const SectionEntry &Section, uint64_t Offset, 33 uint64_t Value, uint32_t Type, int64_t Addend, 34 uint64_t SymOffset); 35 36 void resolveX86Relocation(const SectionEntry &Section, uint64_t Offset, 37 uint32_t Value, uint32_t Type, int32_t Addend); 38 39 void resolveAArch64Relocation(const SectionEntry &Section, uint64_t Offset, 40 uint64_t Value, uint32_t Type, int64_t Addend); 41 42 bool resolveAArch64ShortBranch(unsigned SectionID, relocation_iterator RelI, 43 const RelocationValueRef &Value); 44 45 void resolveAArch64Branch(unsigned SectionID, const RelocationValueRef &Value, 46 relocation_iterator RelI, StubMap &Stubs); 47 48 void resolveARMRelocation(const SectionEntry &Section, uint64_t Offset, 49 uint32_t Value, uint32_t Type, int32_t Addend); 50 51 void resolvePPC32Relocation(const SectionEntry &Section, uint64_t Offset, 52 uint64_t Value, uint32_t Type, int64_t Addend); 53 54 void resolvePPC64Relocation(const SectionEntry &Section, uint64_t Offset, 55 uint64_t Value, uint32_t Type, int64_t Addend); 56 57 void resolveSystemZRelocation(const SectionEntry &Section, uint64_t Offset, 58 uint64_t Value, uint32_t Type, int64_t Addend); 59 60 void resolveBPFRelocation(const SectionEntry &Section, uint64_t Offset, 61 uint64_t Value, uint32_t Type, int64_t Addend); 62 63 unsigned getMaxStubSize() const override { 64 if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be) 65 return 20; // movz; movk; movk; movk; br 66 if (Arch == Triple::arm || Arch == Triple::thumb) 67 return 8; // 32-bit instruction and 32-bit address 68 else if (IsMipsO32ABI || IsMipsN32ABI) 69 return 16; 70 else if (IsMipsN64ABI) 71 return 32; 72 else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) 73 return 44; 74 else if (Arch == Triple::x86_64) 75 return 6; // 2-byte jmp instruction + 32-bit relative address 76 else if (Arch == Triple::systemz) 77 return 16; 78 else 79 return 0; 80 } 81 82 Align getStubAlignment() override { 83 if (Arch == Triple::systemz) 84 return Align(8); 85 else 86 return Align(1); 87 } 88 89 void setMipsABI(const ObjectFile &Obj) override; 90 91 Error findPPC64TOCSection(const object::ELFObjectFileBase &Obj, 92 ObjSectionToIDMap &LocalSections, 93 RelocationValueRef &Rel); 94 Error findOPDEntrySection(const object::ELFObjectFileBase &Obj, 95 ObjSectionToIDMap &LocalSections, 96 RelocationValueRef &Rel); 97 98 protected: 99 size_t getGOTEntrySize() override; 100 101 private: 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 no); 106 107 // Find GOT entry corresponding to relocation or create new one. 108 uint64_t findOrAllocGOTEntry(const RelocationValueRef &Value, 109 unsigned GOTRelType); 110 111 // Resolve the relvative address of GOTOffset in Section ID and place 112 // it at the given Offset 113 void resolveGOTOffsetRelocation(unsigned SectionID, uint64_t Offset, 114 uint64_t GOTOffset, uint32_t Type); 115 116 // For a GOT entry referenced from SectionID, compute a relocation entry 117 // that will place the final resolved value in the GOT slot 118 RelocationEntry computeGOTOffsetRE(uint64_t GOTOffset, uint64_t SymbolOffset, 119 unsigned Type); 120 121 // Compute the address in memory where we can find the placeholder 122 void *computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const; 123 124 // Split out common case for createing the RelocationEntry for when the relocation requires 125 // no particular advanced processing. 126 void processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value); 127 128 // Return matching *LO16 relocation (Mips specific) 129 uint32_t getMatchingLoRelocation(uint32_t RelType, 130 bool IsLocal = false) const; 131 132 // The tentative ID for the GOT section 133 unsigned GOTSectionID; 134 135 // Records the current number of allocated slots in the GOT 136 // (This would be equivalent to GOTEntries.size() were it not for relocations 137 // that consume more than one slot) 138 unsigned CurrentGOTIndex; 139 140 protected: 141 // A map from section to a GOT section that has entries for section's GOT 142 // relocations. (Mips64 specific) 143 DenseMap<SID, SID> SectionToGOTMap; 144 145 private: 146 // A map to avoid duplicate got entries (Mips64 specific) 147 StringMap<uint64_t> GOTSymbolOffsets; 148 149 // *HI16 relocations will be added for resolving when we find matching 150 // *LO16 part. (Mips specific) 151 SmallVector<std::pair<RelocationValueRef, RelocationEntry>, 8> PendingRelocs; 152 153 // When a module is loaded we save the SectionID of the EH frame section 154 // in a table until we receive a request to register all unregistered 155 // EH frame sections with the memory manager. 156 SmallVector<SID, 2> UnregisteredEHFrameSections; 157 158 // Map between GOT relocation value and corresponding GOT offset 159 std::map<RelocationValueRef, uint64_t> GOTOffsetMap; 160 161 /// The ID of the current IFunc stub section 162 unsigned IFuncStubSectionID = 0; 163 /// The current offset into the IFunc stub section 164 uint64_t IFuncStubOffset = 0; 165 166 /// A IFunc stub and its original symbol 167 struct IFuncStub { 168 /// The offset of this stub in the IFunc stub section 169 uint64_t StubOffset; 170 /// The symbol table entry of the original symbol 171 SymbolTableEntry OriginalSymbol; 172 }; 173 174 /// The IFunc stubs 175 SmallVector<IFuncStub, 2> IFuncStubs; 176 177 /// Create the code for the IFunc resolver at the given address. This code 178 /// works together with the stubs created in createIFuncStub() to call the 179 /// resolver function and then jump to the real function address. 180 /// It must not be larger than 64B. 181 void createIFuncResolver(uint8_t *Addr) const; 182 /// Create the code for an IFunc stub for the IFunc that is defined in 183 /// section IFuncSectionID at offset IFuncOffset. The IFunc resolver created 184 /// by createIFuncResolver() is defined in the section IFuncStubSectionID at 185 /// offset IFuncResolverOffset. The code should be written into the section 186 /// with the id IFuncStubSectionID at the offset IFuncStubOffset. 187 void createIFuncStub(unsigned IFuncStubSectionID, 188 uint64_t IFuncResolverOffset, uint64_t IFuncStubOffset, 189 unsigned IFuncSectionID, uint64_t IFuncOffset); 190 /// Return the maximum size of a stub created by createIFuncStub() 191 unsigned getMaxIFuncStubSize() const; 192 193 void processNewSymbol(const SymbolRef &ObjSymbol, 194 SymbolTableEntry &Entry) override; 195 bool relocationNeedsGot(const RelocationRef &R) const override; 196 bool relocationNeedsStub(const RelocationRef &R) const override; 197 198 // Process a GOTTPOFF TLS relocation for x86-64 199 // NOLINTNEXTLINE(readability-identifier-naming) 200 void processX86_64GOTTPOFFRelocation(unsigned SectionID, uint64_t Offset, 201 RelocationValueRef Value, 202 int64_t Addend); 203 // Process a TLSLD/TLSGD relocation for x86-64 204 // NOLINTNEXTLINE(readability-identifier-naming) 205 void processX86_64TLSRelocation(unsigned SectionID, uint64_t Offset, 206 uint64_t RelType, RelocationValueRef Value, 207 int64_t Addend, 208 const RelocationRef &GetAddrRelocation); 209 210 public: 211 RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr, 212 JITSymbolResolver &Resolver); 213 ~RuntimeDyldELF() override; 214 215 static std::unique_ptr<RuntimeDyldELF> 216 create(Triple::ArchType Arch, RuntimeDyld::MemoryManager &MemMgr, 217 JITSymbolResolver &Resolver); 218 219 std::unique_ptr<RuntimeDyld::LoadedObjectInfo> 220 loadObject(const object::ObjectFile &O) override; 221 222 void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override; 223 Expected<relocation_iterator> 224 processRelocationRef(unsigned SectionID, relocation_iterator RelI, 225 const ObjectFile &Obj, 226 ObjSectionToIDMap &ObjSectionToID, 227 StubMap &Stubs) override; 228 bool isCompatibleFile(const object::ObjectFile &Obj) const override; 229 void registerEHFrames() override; 230 Error finalizeLoad(const ObjectFile &Obj, 231 ObjSectionToIDMap &SectionMap) override; 232 }; 233 234 } // end namespace llvm 235 236 #endif 237