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 Align getStubAlignment() override { return Align(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 report_fatal_error("IMAGE_REL_AMD64_ADDR32NB relocation requires an " 118 "ordered section layout"); 119 else { 120 write32BitOffset(Target, RE.Addend, Value - ImageBase); 121 } 122 break; 123 } 124 125 case COFF::IMAGE_REL_AMD64_ADDR64: { 126 writeBytesUnaligned(Value + RE.Addend, Target, 8); 127 break; 128 } 129 130 case COFF::IMAGE_REL_AMD64_SECREL: { 131 assert(static_cast<int64_t>(RE.Addend) <= INT32_MAX && "Relocation overflow"); 132 assert(static_cast<int64_t>(RE.Addend) >= INT32_MIN && "Relocation underflow"); 133 writeBytesUnaligned(RE.Addend, Target, 4); 134 break; 135 } 136 137 default: 138 llvm_unreachable("Relocation type not implemented yet!"); 139 break; 140 } 141 } 142 143 std::tuple<uint64_t, uint64_t, uint64_t> 144 generateRelocationStub(unsigned SectionID, StringRef TargetName, 145 uint64_t Offset, uint64_t RelType, uint64_t Addend, 146 StubMap &Stubs) { 147 uintptr_t StubOffset; 148 SectionEntry &Section = Sections[SectionID]; 149 150 RelocationValueRef OriginalRelValueRef; 151 OriginalRelValueRef.SectionID = SectionID; 152 OriginalRelValueRef.Offset = Offset; 153 OriginalRelValueRef.Addend = Addend; 154 OriginalRelValueRef.SymbolName = TargetName.data(); 155 156 auto Stub = Stubs.find(OriginalRelValueRef); 157 if (Stub == Stubs.end()) { 158 LLVM_DEBUG(dbgs() << " Create a new stub function for " 159 << TargetName.data() << "\n"); 160 161 StubOffset = Section.getStubOffset(); 162 Stubs[OriginalRelValueRef] = StubOffset; 163 createStubFunction(Section.getAddressWithOffset(StubOffset)); 164 Section.advanceStubOffset(getMaxStubSize()); 165 } else { 166 LLVM_DEBUG(dbgs() << " Stub function found for " << TargetName.data() 167 << "\n"); 168 StubOffset = Stub->second; 169 } 170 171 // FIXME: If RelType == COFF::IMAGE_REL_AMD64_ADDR32NB we should be able 172 // to ignore the __ImageBase requirement and just forward to the stub 173 // directly as an offset of this section: 174 // write32BitOffset(Section.getAddressWithOffset(Offset), 0, StubOffset); 175 // .xdata exception handler's aren't having this though. 176 177 // Resolve original relocation to stub function. 178 const RelocationEntry RE(SectionID, Offset, RelType, Addend); 179 resolveRelocation(RE, Section.getLoadAddressWithOffset(StubOffset)); 180 181 // adjust relocation info so resolution writes to the stub function 182 Addend = 0; 183 Offset = StubOffset + 6; 184 RelType = COFF::IMAGE_REL_AMD64_ADDR64; 185 186 return std::make_tuple(Offset, RelType, Addend); 187 } 188 189 Expected<object::relocation_iterator> 190 processRelocationRef(unsigned SectionID, 191 object::relocation_iterator RelI, 192 const object::ObjectFile &Obj, 193 ObjSectionToIDMap &ObjSectionToID, 194 StubMap &Stubs) override { 195 // If possible, find the symbol referred to in the relocation, 196 // and the section that contains it. 197 object::symbol_iterator Symbol = RelI->getSymbol(); 198 if (Symbol == Obj.symbol_end()) 199 report_fatal_error("Unknown symbol in relocation"); 200 auto SectionOrError = Symbol->getSection(); 201 if (!SectionOrError) 202 return SectionOrError.takeError(); 203 object::section_iterator SecI = *SectionOrError; 204 // If there is no section, this must be an external reference. 205 bool IsExtern = SecI == Obj.section_end(); 206 207 // Determine the Addend used to adjust the relocation value. 208 uint64_t RelType = RelI->getType(); 209 uint64_t Offset = RelI->getOffset(); 210 uint64_t Addend = 0; 211 SectionEntry &Section = Sections[SectionID]; 212 uintptr_t ObjTarget = Section.getObjAddress() + Offset; 213 214 Expected<StringRef> TargetNameOrErr = Symbol->getName(); 215 if (!TargetNameOrErr) 216 return TargetNameOrErr.takeError(); 217 218 StringRef TargetName = *TargetNameOrErr; 219 unsigned TargetSectionID = 0; 220 uint64_t TargetOffset = 0; 221 222 if (TargetName.startswith(getImportSymbolPrefix())) { 223 assert(IsExtern && "DLLImport not marked extern?"); 224 TargetSectionID = SectionID; 225 TargetOffset = getDLLImportOffset(SectionID, Stubs, TargetName); 226 TargetName = StringRef(); 227 IsExtern = false; 228 } else if (!IsExtern) { 229 if (auto TargetSectionIDOrErr = 230 findOrEmitSection(Obj, *SecI, SecI->isText(), ObjSectionToID)) 231 TargetSectionID = *TargetSectionIDOrErr; 232 else 233 return TargetSectionIDOrErr.takeError(); 234 TargetOffset = getSymbolOffset(*Symbol); 235 } 236 237 switch (RelType) { 238 239 case COFF::IMAGE_REL_AMD64_REL32: 240 case COFF::IMAGE_REL_AMD64_REL32_1: 241 case COFF::IMAGE_REL_AMD64_REL32_2: 242 case COFF::IMAGE_REL_AMD64_REL32_3: 243 case COFF::IMAGE_REL_AMD64_REL32_4: 244 case COFF::IMAGE_REL_AMD64_REL32_5: 245 case COFF::IMAGE_REL_AMD64_ADDR32NB: { 246 uint8_t *Displacement = (uint8_t *)ObjTarget; 247 Addend = readBytesUnaligned(Displacement, 4); 248 249 if (IsExtern) 250 std::tie(Offset, RelType, Addend) = generateRelocationStub( 251 SectionID, TargetName, Offset, RelType, Addend, Stubs); 252 253 break; 254 } 255 256 case COFF::IMAGE_REL_AMD64_ADDR64: { 257 uint8_t *Displacement = (uint8_t *)ObjTarget; 258 Addend = readBytesUnaligned(Displacement, 8); 259 break; 260 } 261 262 default: 263 break; 264 } 265 266 LLVM_DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset 267 << " RelType: " << RelType << " TargetName: " 268 << TargetName << " Addend " << Addend << "\n"); 269 270 if (IsExtern) { 271 RelocationEntry RE(SectionID, Offset, RelType, Addend); 272 addRelocationForSymbol(RE, TargetName); 273 } else { 274 RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend); 275 addRelocationForSection(RE, TargetSectionID); 276 } 277 278 return ++RelI; 279 } 280 281 void registerEHFrames() override { 282 for (auto const &EHFrameSID : UnregisteredEHFrameSections) { 283 uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress(); 284 uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress(); 285 size_t EHFrameSize = Sections[EHFrameSID].getSize(); 286 MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize); 287 RegisteredEHFrameSections.push_back(EHFrameSID); 288 } 289 UnregisteredEHFrameSections.clear(); 290 } 291 292 Error finalizeLoad(const object::ObjectFile &Obj, 293 ObjSectionToIDMap &SectionMap) override { 294 // Look for and record the EH frame section IDs. 295 for (const auto &SectionPair : SectionMap) { 296 const object::SectionRef &Section = SectionPair.first; 297 Expected<StringRef> NameOrErr = Section.getName(); 298 if (!NameOrErr) 299 return NameOrErr.takeError(); 300 301 // Note unwind info is stored in .pdata but often points to .xdata 302 // with an IMAGE_REL_AMD64_ADDR32NB relocation. Using a memory manager 303 // that keeps sections ordered in relation to __ImageBase is necessary. 304 if ((*NameOrErr) == ".pdata") 305 UnregisteredEHFrameSections.push_back(SectionPair.second); 306 } 307 return Error::success(); 308 } 309 }; 310 311 } // end namespace llvm 312 313 #undef DEBUG_TYPE 314 315 #endif 316