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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-exception6//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_H14#define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFF86_64_H15 16#include "../RuntimeDyldCOFF.h"17#include "llvm/BinaryFormat/COFF.h"18#include "llvm/Object/COFF.h"19 20#define DEBUG_TYPE "dyld"21 22namespace llvm {23 24class RuntimeDyldCOFFX86_64 : public RuntimeDyldCOFF {25 26private:27 // When a module is loaded we save the SectionID of the unwind28 // sections in a table until we receive a request to register all29 // 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 adress35 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 for40 // whatever reason: they may be debug sections, and ProcessAllSections41 // is false, or they may be sections that contain 0 bytes. If the42 // section isn't loaded, the load address will be 0, and it should not43 // 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 56public: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 jump65 unsigned getMaxStubSize() const override { return 14; }66 67 // The target location for the relocation is described by RE.SectionID and68 // RE.Offset. RE.SectionID can be used to find the SectionEntry. Each69 // SectionEntry has three members describing its location.70 // SectionEntry::Address is the address at which the section has been loaded71 // into memory in the current (host) process. SectionEntry::LoadAddress is72 // the address that the section will have in the target process.73 // SectionEntry::ObjAddress is the address of the bits for this section in the74 // original emitted object image (also in the current address space).75 //76 // Relocations will be applied as if the section were loaded at77 // SectionEntry::LoadAddress, but they will be applied at an address based78 // on SectionEntry::Address. SectionEntry::ObjAddress will be used to refer79 // 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 the82 // relocation to be applied. For relocations which refer to symbols in the83 // current object Value will be the LoadAddress of the section in which84 // the symbol resides (RE.Addend provides additional information about the85 // symbol location). For external symbols, Value will be the address of the86 // 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 the101 // 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 the114 // 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 case COFF::IMAGE_REL_AMD64_SECTION: {138 assert(static_cast<int16_t>(RE.SectionID) <= INT16_MAX && "Relocation overflow");139 assert(static_cast<int16_t>(RE.SectionID) >= INT16_MIN && "Relocation underflow");140 writeBytesUnaligned(RE.SectionID, Target, 2);141 break;142 }143 144 default:145 llvm_unreachable("Relocation type not implemented yet!");146 break;147 }148 }149 150 std::tuple<uint64_t, uint64_t, uint64_t>151 generateRelocationStub(unsigned SectionID, StringRef TargetName,152 uint64_t Offset, uint64_t RelType, uint64_t Addend,153 StubMap &Stubs) {154 uintptr_t StubOffset;155 SectionEntry &Section = Sections[SectionID];156 157 RelocationValueRef OriginalRelValueRef;158 OriginalRelValueRef.SectionID = SectionID;159 OriginalRelValueRef.Offset = Offset;160 OriginalRelValueRef.Addend = Addend;161 OriginalRelValueRef.SymbolName = TargetName.data();162 163 auto [Stub, Inserted] = Stubs.try_emplace(OriginalRelValueRef);164 if (Inserted) {165 LLVM_DEBUG(dbgs() << " Create a new stub function for "166 << TargetName.data() << "\n");167 168 StubOffset = Section.getStubOffset();169 Stub->second = StubOffset;170 createStubFunction(Section.getAddressWithOffset(StubOffset));171 Section.advanceStubOffset(getMaxStubSize());172 } else {173 LLVM_DEBUG(dbgs() << " Stub function found for " << TargetName.data()174 << "\n");175 StubOffset = Stub->second;176 }177 178 // FIXME: If RelType == COFF::IMAGE_REL_AMD64_ADDR32NB we should be able179 // to ignore the __ImageBase requirement and just forward to the stub180 // directly as an offset of this section:181 // write32BitOffset(Section.getAddressWithOffset(Offset), 0, StubOffset);182 // .xdata exception handler's aren't having this though.183 184 // Resolve original relocation to stub function.185 const RelocationEntry RE(SectionID, Offset, RelType, Addend);186 resolveRelocation(RE, Section.getLoadAddressWithOffset(StubOffset));187 188 // adjust relocation info so resolution writes to the stub function189 Addend = 0;190 Offset = StubOffset + 6;191 RelType = COFF::IMAGE_REL_AMD64_ADDR64;192 193 return std::make_tuple(Offset, RelType, Addend);194 }195 196 Expected<object::relocation_iterator>197 processRelocationRef(unsigned SectionID,198 object::relocation_iterator RelI,199 const object::ObjectFile &Obj,200 ObjSectionToIDMap &ObjSectionToID,201 StubMap &Stubs) override {202 // If possible, find the symbol referred to in the relocation,203 // and the section that contains it.204 object::symbol_iterator Symbol = RelI->getSymbol();205 if (Symbol == Obj.symbol_end())206 report_fatal_error("Unknown symbol in relocation");207 auto SectionOrError = Symbol->getSection();208 if (!SectionOrError)209 return SectionOrError.takeError();210 object::section_iterator SecI = *SectionOrError;211 // If there is no section, this must be an external reference.212 bool IsExtern = SecI == Obj.section_end();213 214 // Determine the Addend used to adjust the relocation value.215 uint64_t RelType = RelI->getType();216 uint64_t Offset = RelI->getOffset();217 uint64_t Addend = 0;218 SectionEntry &Section = Sections[SectionID];219 uintptr_t ObjTarget = Section.getObjAddress() + Offset;220 221 Expected<StringRef> TargetNameOrErr = Symbol->getName();222 if (!TargetNameOrErr)223 return TargetNameOrErr.takeError();224 225 StringRef TargetName = *TargetNameOrErr;226 unsigned TargetSectionID = 0;227 uint64_t TargetOffset = 0;228 229 if (TargetName.starts_with(getImportSymbolPrefix())) {230 assert(IsExtern && "DLLImport not marked extern?");231 TargetSectionID = SectionID;232 TargetOffset = getDLLImportOffset(SectionID, Stubs, TargetName);233 TargetName = StringRef();234 IsExtern = false;235 } else if (!IsExtern) {236 if (auto TargetSectionIDOrErr =237 findOrEmitSection(Obj, *SecI, SecI->isText(), ObjSectionToID))238 TargetSectionID = *TargetSectionIDOrErr;239 else240 return TargetSectionIDOrErr.takeError();241 TargetOffset = getSymbolOffset(*Symbol);242 }243 244 switch (RelType) {245 246 case COFF::IMAGE_REL_AMD64_REL32:247 case COFF::IMAGE_REL_AMD64_REL32_1:248 case COFF::IMAGE_REL_AMD64_REL32_2:249 case COFF::IMAGE_REL_AMD64_REL32_3:250 case COFF::IMAGE_REL_AMD64_REL32_4:251 case COFF::IMAGE_REL_AMD64_REL32_5:252 case COFF::IMAGE_REL_AMD64_ADDR32NB: {253 uint8_t *Displacement = (uint8_t *)ObjTarget;254 Addend = readBytesUnaligned(Displacement, 4);255 256 if (IsExtern)257 std::tie(Offset, RelType, Addend) = generateRelocationStub(258 SectionID, TargetName, Offset, RelType, Addend, Stubs);259 260 break;261 }262 263 case COFF::IMAGE_REL_AMD64_ADDR64: {264 uint8_t *Displacement = (uint8_t *)ObjTarget;265 Addend = readBytesUnaligned(Displacement, 8);266 break;267 }268 269 default:270 break;271 }272 273 LLVM_DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset274 << " RelType: " << RelType << " TargetName: "275 << TargetName << " Addend " << Addend << "\n");276 277 if (IsExtern) {278 RelocationEntry RE(SectionID, Offset, RelType, Addend);279 addRelocationForSymbol(RE, TargetName);280 } else {281 RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend);282 addRelocationForSection(RE, TargetSectionID);283 }284 285 return ++RelI;286 }287 288 void registerEHFrames() override {289 for (auto const &EHFrameSID : UnregisteredEHFrameSections) {290 uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress();291 uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress();292 size_t EHFrameSize = Sections[EHFrameSID].getSize();293 MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);294 RegisteredEHFrameSections.push_back(EHFrameSID);295 }296 UnregisteredEHFrameSections.clear();297 }298 299 Error finalizeLoad(const object::ObjectFile &Obj,300 ObjSectionToIDMap &SectionMap) override {301 // Look for and record the EH frame section IDs.302 for (const auto &SectionPair : SectionMap) {303 const object::SectionRef &Section = SectionPair.first;304 Expected<StringRef> NameOrErr = Section.getName();305 if (!NameOrErr)306 return NameOrErr.takeError();307 308 // Note unwind info is stored in .pdata but often points to .xdata309 // with an IMAGE_REL_AMD64_ADDR32NB relocation. Using a memory manager310 // that keeps sections ordered in relation to __ImageBase is necessary.311 if ((*NameOrErr) == ".pdata")312 UnregisteredEHFrameSections.push_back(SectionPair.second);313 }314 return Error::success();315 }316};317 318} // end namespace llvm319 320#undef DEBUG_TYPE321 322#endif323