1 //===-- RuntimeDyldCOFFX86_64.h --- COFF/X86_64 specific code ---*- 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 // COFF x86_x64 support for MC-JIT runtime dynamic linker. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFF86_64_H 14 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFF86_64_H 15 16 #include "../RuntimeDyldCOFF.h" 17 #include "llvm/BinaryFormat/COFF.h" 18 #include "llvm/Object/COFF.h" 19 20 #define DEBUG_TYPE "dyld" 21 22 namespace llvm { 23 24 class RuntimeDyldCOFFX86_64 : public RuntimeDyldCOFF { 25 26 private: 27 // When a module is loaded we save the SectionID of the unwind 28 // sections in a table until we receive a request to register all 29 // unregisteredEH frame sections with the memory manager. 30 SmallVector<SID, 2> UnregisteredEHFrameSections; 31 SmallVector<SID, 2> RegisteredEHFrameSections; 32 uint64_t ImageBase; 33 34 // Fake an __ImageBase pointer by returning the section with the lowest adress 35 uint64_t getImageBase() { 36 if (!ImageBase) { 37 ImageBase = std::numeric_limits<uint64_t>::max(); 38 for (const SectionEntry &Section : Sections) 39 // The Sections list may contain sections that weren't loaded for 40 // whatever reason: they may be debug sections, and ProcessAllSections 41 // is false, or they may be sections that contain 0 bytes. If the 42 // section isn't loaded, the load address will be 0, and it should not 43 // be included in the ImageBase calculation. 44 if (Section.getLoadAddress() != 0) 45 ImageBase = std::min(ImageBase, Section.getLoadAddress()); 46 } 47 return ImageBase; 48 } 49 50 void write32BitOffset(uint8_t *Target, int64_t Addend, uint64_t Delta) { 51 uint64_t Result = Addend + Delta; 52 assert(Result <= UINT32_MAX && "Relocation overflow"); 53 writeBytesUnaligned(Result, Target, 4); 54 } 55 56 public: 57 RuntimeDyldCOFFX86_64(RuntimeDyld::MemoryManager &MM, 58 JITSymbolResolver &Resolver) 59 : RuntimeDyldCOFF(MM, Resolver, 8, COFF::IMAGE_REL_AMD64_ADDR64), 60 ImageBase(0) {} 61 62 unsigned getStubAlignment() override { return 1; } 63 64 // 2-byte jmp instruction + 32-bit relative address + 64-bit absolute jump 65 unsigned getMaxStubSize() const override { return 14; } 66 67 // The target location for the relocation is described by RE.SectionID and 68 // RE.Offset. RE.SectionID can be used to find the SectionEntry. Each 69 // SectionEntry has three members describing its location. 70 // SectionEntry::Address is the address at which the section has been loaded 71 // into memory in the current (host) process. SectionEntry::LoadAddress is 72 // the address that the section will have in the target process. 73 // SectionEntry::ObjAddress is the address of the bits for this section in the 74 // original emitted object image (also in the current address space). 75 // 76 // Relocations will be applied as if the section were loaded at 77 // SectionEntry::LoadAddress, but they will be applied at an address based 78 // on SectionEntry::Address. SectionEntry::ObjAddress will be used to refer 79 // to Target memory contents if they are required for value calculations. 80 // 81 // The Value parameter here is the load address of the symbol for the 82 // relocation to be applied. For relocations which refer to symbols in the 83 // current object Value will be the LoadAddress of the section in which 84 // the symbol resides (RE.Addend provides additional information about the 85 // symbol location). For external symbols, Value will be the address of the 86 // symbol in the target address space. 87 void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override { 88 const SectionEntry &Section = Sections[RE.SectionID]; 89 uint8_t *Target = Section.getAddressWithOffset(RE.Offset); 90 91 switch (RE.RelType) { 92 93 case COFF::IMAGE_REL_AMD64_REL32: 94 case COFF::IMAGE_REL_AMD64_REL32_1: 95 case COFF::IMAGE_REL_AMD64_REL32_2: 96 case COFF::IMAGE_REL_AMD64_REL32_3: 97 case COFF::IMAGE_REL_AMD64_REL32_4: 98 case COFF::IMAGE_REL_AMD64_REL32_5: { 99 uint64_t FinalAddress = Section.getLoadAddressWithOffset(RE.Offset); 100 // Delta is the distance from the start of the reloc to the end of the 101 // instruction with the reloc. 102 uint64_t Delta = 4 + (RE.RelType - COFF::IMAGE_REL_AMD64_REL32); 103 Value -= FinalAddress + Delta; 104 uint64_t Result = Value + RE.Addend; 105 assert(((int64_t)Result <= INT32_MAX) && "Relocation overflow"); 106 assert(((int64_t)Result >= INT32_MIN) && "Relocation underflow"); 107 writeBytesUnaligned(Result, Target, 4); 108 break; 109 } 110 111 case COFF::IMAGE_REL_AMD64_ADDR32NB: { 112 // ADDR32NB requires an offset less than 2GB from 'ImageBase'. 113 // The MemoryManager can make sure this is always true by forcing the 114 // memory layout to be: CodeSection < ReadOnlySection < ReadWriteSection. 115 const uint64_t ImageBase = getImageBase(); 116 if (Value < ImageBase || ((Value - ImageBase) > UINT32_MAX)) { 117 llvm::errs() << "IMAGE_REL_AMD64_ADDR32NB relocation requires an" 118 << "ordered section layout.\n"; 119 write32BitOffset(Target, 0, 0); 120 } else { 121 write32BitOffset(Target, RE.Addend, Value - ImageBase); 122 } 123 break; 124 } 125 126 case COFF::IMAGE_REL_AMD64_ADDR64: { 127 writeBytesUnaligned(Value + RE.Addend, Target, 8); 128 break; 129 } 130 131 case COFF::IMAGE_REL_AMD64_SECREL: { 132 assert(static_cast<int64_t>(RE.Addend) <= INT32_MAX && "Relocation overflow"); 133 assert(static_cast<int64_t>(RE.Addend) >= INT32_MIN && "Relocation underflow"); 134 writeBytesUnaligned(RE.Addend, Target, 4); 135 break; 136 } 137 138 default: 139 llvm_unreachable("Relocation type not implemented yet!"); 140 break; 141 } 142 } 143 144 std::tuple<uint64_t, uint64_t, uint64_t> 145 generateRelocationStub(unsigned SectionID, StringRef TargetName, 146 uint64_t Offset, uint64_t RelType, uint64_t Addend, 147 StubMap &Stubs) { 148 uintptr_t StubOffset; 149 SectionEntry &Section = Sections[SectionID]; 150 151 RelocationValueRef OriginalRelValueRef; 152 OriginalRelValueRef.SectionID = SectionID; 153 OriginalRelValueRef.Offset = Offset; 154 OriginalRelValueRef.Addend = Addend; 155 OriginalRelValueRef.SymbolName = TargetName.data(); 156 157 auto Stub = Stubs.find(OriginalRelValueRef); 158 if (Stub == Stubs.end()) { 159 LLVM_DEBUG(dbgs() << " Create a new stub function for " 160 << TargetName.data() << "\n"); 161 162 StubOffset = Section.getStubOffset(); 163 Stubs[OriginalRelValueRef] = StubOffset; 164 createStubFunction(Section.getAddressWithOffset(StubOffset)); 165 Section.advanceStubOffset(getMaxStubSize()); 166 } else { 167 LLVM_DEBUG(dbgs() << " Stub function found for " << TargetName.data() 168 << "\n"); 169 StubOffset = Stub->second; 170 } 171 172 // FIXME: If RelType == COFF::IMAGE_REL_AMD64_ADDR32NB we should be able 173 // to ignore the __ImageBase requirement and just forward to the stub 174 // directly as an offset of this section: 175 // write32BitOffset(Section.getAddressWithOffset(Offset), 0, StubOffset); 176 // .xdata exception handler's aren't having this though. 177 178 // Resolve original relocation to stub function. 179 const RelocationEntry RE(SectionID, Offset, RelType, Addend); 180 resolveRelocation(RE, Section.getLoadAddressWithOffset(StubOffset)); 181 182 // adjust relocation info so resolution writes to the stub function 183 Addend = 0; 184 Offset = StubOffset + 6; 185 RelType = COFF::IMAGE_REL_AMD64_ADDR64; 186 187 return std::make_tuple(Offset, RelType, Addend); 188 } 189 190 Expected<object::relocation_iterator> 191 processRelocationRef(unsigned SectionID, 192 object::relocation_iterator RelI, 193 const object::ObjectFile &Obj, 194 ObjSectionToIDMap &ObjSectionToID, 195 StubMap &Stubs) override { 196 // If possible, find the symbol referred to in the relocation, 197 // and the section that contains it. 198 object::symbol_iterator Symbol = RelI->getSymbol(); 199 if (Symbol == Obj.symbol_end()) 200 report_fatal_error("Unknown symbol in relocation"); 201 auto SectionOrError = Symbol->getSection(); 202 if (!SectionOrError) 203 return SectionOrError.takeError(); 204 object::section_iterator SecI = *SectionOrError; 205 // If there is no section, this must be an external reference. 206 bool IsExtern = SecI == Obj.section_end(); 207 208 // Determine the Addend used to adjust the relocation value. 209 uint64_t RelType = RelI->getType(); 210 uint64_t Offset = RelI->getOffset(); 211 uint64_t Addend = 0; 212 SectionEntry &Section = Sections[SectionID]; 213 uintptr_t ObjTarget = Section.getObjAddress() + Offset; 214 215 Expected<StringRef> TargetNameOrErr = Symbol->getName(); 216 if (!TargetNameOrErr) 217 return TargetNameOrErr.takeError(); 218 219 StringRef TargetName = *TargetNameOrErr; 220 unsigned TargetSectionID = 0; 221 uint64_t TargetOffset = 0; 222 223 if (TargetName.startswith(getImportSymbolPrefix())) { 224 assert(IsExtern && "DLLImport not marked extern?"); 225 TargetSectionID = SectionID; 226 TargetOffset = getDLLImportOffset(SectionID, Stubs, TargetName); 227 TargetName = StringRef(); 228 IsExtern = false; 229 } else if (!IsExtern) { 230 if (auto TargetSectionIDOrErr = 231 findOrEmitSection(Obj, *SecI, SecI->isText(), ObjSectionToID)) 232 TargetSectionID = *TargetSectionIDOrErr; 233 else 234 return TargetSectionIDOrErr.takeError(); 235 TargetOffset = getSymbolOffset(*Symbol); 236 } 237 238 switch (RelType) { 239 240 case COFF::IMAGE_REL_AMD64_REL32: 241 case COFF::IMAGE_REL_AMD64_REL32_1: 242 case COFF::IMAGE_REL_AMD64_REL32_2: 243 case COFF::IMAGE_REL_AMD64_REL32_3: 244 case COFF::IMAGE_REL_AMD64_REL32_4: 245 case COFF::IMAGE_REL_AMD64_REL32_5: 246 case COFF::IMAGE_REL_AMD64_ADDR32NB: { 247 uint8_t *Displacement = (uint8_t *)ObjTarget; 248 Addend = readBytesUnaligned(Displacement, 4); 249 250 if (IsExtern) 251 std::tie(Offset, RelType, Addend) = generateRelocationStub( 252 SectionID, TargetName, Offset, RelType, Addend, Stubs); 253 254 break; 255 } 256 257 case COFF::IMAGE_REL_AMD64_ADDR64: { 258 uint8_t *Displacement = (uint8_t *)ObjTarget; 259 Addend = readBytesUnaligned(Displacement, 8); 260 break; 261 } 262 263 default: 264 break; 265 } 266 267 LLVM_DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset 268 << " RelType: " << RelType << " TargetName: " 269 << TargetName << " Addend " << Addend << "\n"); 270 271 if (IsExtern) { 272 RelocationEntry RE(SectionID, Offset, RelType, Addend); 273 addRelocationForSymbol(RE, TargetName); 274 } else { 275 RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend); 276 addRelocationForSection(RE, TargetSectionID); 277 } 278 279 return ++RelI; 280 } 281 282 void registerEHFrames() override { 283 for (auto const &EHFrameSID : UnregisteredEHFrameSections) { 284 uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress(); 285 uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress(); 286 size_t EHFrameSize = Sections[EHFrameSID].getSize(); 287 MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize); 288 RegisteredEHFrameSections.push_back(EHFrameSID); 289 } 290 UnregisteredEHFrameSections.clear(); 291 } 292 293 Error finalizeLoad(const object::ObjectFile &Obj, 294 ObjSectionToIDMap &SectionMap) override { 295 // Look for and record the EH frame section IDs. 296 for (const auto &SectionPair : SectionMap) { 297 const object::SectionRef &Section = SectionPair.first; 298 Expected<StringRef> NameOrErr = Section.getName(); 299 if (!NameOrErr) 300 return NameOrErr.takeError(); 301 302 // Note unwind info is stored in .pdata but often points to .xdata 303 // with an IMAGE_REL_AMD64_ADDR32NB relocation. Using a memory manager 304 // that keeps sections ordered in relation to __ImageBase is necessary. 305 if ((*NameOrErr) == ".pdata") 306 UnregisteredEHFrameSections.push_back(SectionPair.second); 307 } 308 return Error::success(); 309 } 310 }; 311 312 } // end namespace llvm 313 314 #undef DEBUG_TYPE 315 316 #endif 317