//===-- RuntimeDyldCOFFX86_64.h --- COFF/X86_64 specific code ---*- C++ -*-===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // COFF x86_x64 support for MC-JIT runtime dynamic linker. // //===----------------------------------------------------------------------===// #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFF86_64_H #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFF86_64_H #include "../RuntimeDyldCOFF.h" #include "llvm/BinaryFormat/COFF.h" #include "llvm/Object/COFF.h" #define DEBUG_TYPE "dyld" namespace llvm { class RuntimeDyldCOFFX86_64 : public RuntimeDyldCOFF { private: // When a module is loaded we save the SectionID of the unwind // sections in a table until we receive a request to register all // unregisteredEH frame sections with the memory manager. SmallVector UnregisteredEHFrameSections; SmallVector RegisteredEHFrameSections; uint64_t ImageBase; // Fake an __ImageBase pointer by returning the section with the lowest adress uint64_t getImageBase() { if (!ImageBase) { ImageBase = std::numeric_limits::max(); for (const SectionEntry &Section : Sections) // The Sections list may contain sections that weren't loaded for // whatever reason: they may be debug sections, and ProcessAllSections // is false, or they may be sections that contain 0 bytes. If the // section isn't loaded, the load address will be 0, and it should not // be included in the ImageBase calculation. if (Section.getLoadAddress() != 0) ImageBase = std::min(ImageBase, Section.getLoadAddress()); } return ImageBase; } void write32BitOffset(uint8_t *Target, int64_t Addend, uint64_t Delta) { uint64_t Result = Addend + Delta; assert(Result <= UINT32_MAX && "Relocation overflow"); writeBytesUnaligned(Result, Target, 4); } public: RuntimeDyldCOFFX86_64(RuntimeDyld::MemoryManager &MM, JITSymbolResolver &Resolver) : RuntimeDyldCOFF(MM, Resolver, 8, COFF::IMAGE_REL_AMD64_ADDR64), ImageBase(0) {} unsigned getStubAlignment() override { return 1; } // 2-byte jmp instruction + 32-bit relative address + 64-bit absolute jump unsigned getMaxStubSize() const override { return 14; } // The target location for the relocation is described by RE.SectionID and // RE.Offset. RE.SectionID can be used to find the SectionEntry. Each // SectionEntry has three members describing its location. // SectionEntry::Address is the address at which the section has been loaded // into memory in the current (host) process. SectionEntry::LoadAddress is // the address that the section will have in the target process. // SectionEntry::ObjAddress is the address of the bits for this section in the // original emitted object image (also in the current address space). // // Relocations will be applied as if the section were loaded at // SectionEntry::LoadAddress, but they will be applied at an address based // on SectionEntry::Address. SectionEntry::ObjAddress will be used to refer // to Target memory contents if they are required for value calculations. // // The Value parameter here is the load address of the symbol for the // relocation to be applied. For relocations which refer to symbols in the // current object Value will be the LoadAddress of the section in which // the symbol resides (RE.Addend provides additional information about the // symbol location). For external symbols, Value will be the address of the // symbol in the target address space. void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override { const SectionEntry &Section = Sections[RE.SectionID]; uint8_t *Target = Section.getAddressWithOffset(RE.Offset); switch (RE.RelType) { case COFF::IMAGE_REL_AMD64_REL32: case COFF::IMAGE_REL_AMD64_REL32_1: case COFF::IMAGE_REL_AMD64_REL32_2: case COFF::IMAGE_REL_AMD64_REL32_3: case COFF::IMAGE_REL_AMD64_REL32_4: case COFF::IMAGE_REL_AMD64_REL32_5: { uint64_t FinalAddress = Section.getLoadAddressWithOffset(RE.Offset); // Delta is the distance from the start of the reloc to the end of the // instruction with the reloc. uint64_t Delta = 4 + (RE.RelType - COFF::IMAGE_REL_AMD64_REL32); Value -= FinalAddress + Delta; uint64_t Result = Value + RE.Addend; assert(((int64_t)Result <= INT32_MAX) && "Relocation overflow"); assert(((int64_t)Result >= INT32_MIN) && "Relocation underflow"); writeBytesUnaligned(Result, Target, 4); break; } case COFF::IMAGE_REL_AMD64_ADDR32NB: { // ADDR32NB requires an offset less than 2GB from 'ImageBase'. // The MemoryManager can make sure this is always true by forcing the // memory layout to be: CodeSection < ReadOnlySection < ReadWriteSection. const uint64_t ImageBase = getImageBase(); if (Value < ImageBase || ((Value - ImageBase) > UINT32_MAX)) report_fatal_error("IMAGE_REL_AMD64_ADDR32NB relocation requires an " "ordered section layout"); else { write32BitOffset(Target, RE.Addend, Value - ImageBase); } break; } case COFF::IMAGE_REL_AMD64_ADDR64: { writeBytesUnaligned(Value + RE.Addend, Target, 8); break; } case COFF::IMAGE_REL_AMD64_SECREL: { assert(static_cast(RE.Addend) <= INT32_MAX && "Relocation overflow"); assert(static_cast(RE.Addend) >= INT32_MIN && "Relocation underflow"); writeBytesUnaligned(RE.Addend, Target, 4); break; } default: llvm_unreachable("Relocation type not implemented yet!"); break; } } std::tuple generateRelocationStub(unsigned SectionID, StringRef TargetName, uint64_t Offset, uint64_t RelType, uint64_t Addend, StubMap &Stubs) { uintptr_t StubOffset; SectionEntry &Section = Sections[SectionID]; RelocationValueRef OriginalRelValueRef; OriginalRelValueRef.SectionID = SectionID; OriginalRelValueRef.Offset = Offset; OriginalRelValueRef.Addend = Addend; OriginalRelValueRef.SymbolName = TargetName.data(); auto Stub = Stubs.find(OriginalRelValueRef); if (Stub == Stubs.end()) { LLVM_DEBUG(dbgs() << " Create a new stub function for " << TargetName.data() << "\n"); StubOffset = Section.getStubOffset(); Stubs[OriginalRelValueRef] = StubOffset; createStubFunction(Section.getAddressWithOffset(StubOffset)); Section.advanceStubOffset(getMaxStubSize()); } else { LLVM_DEBUG(dbgs() << " Stub function found for " << TargetName.data() << "\n"); StubOffset = Stub->second; } // FIXME: If RelType == COFF::IMAGE_REL_AMD64_ADDR32NB we should be able // to ignore the __ImageBase requirement and just forward to the stub // directly as an offset of this section: // write32BitOffset(Section.getAddressWithOffset(Offset), 0, StubOffset); // .xdata exception handler's aren't having this though. // Resolve original relocation to stub function. const RelocationEntry RE(SectionID, Offset, RelType, Addend); resolveRelocation(RE, Section.getLoadAddressWithOffset(StubOffset)); // adjust relocation info so resolution writes to the stub function Addend = 0; Offset = StubOffset + 6; RelType = COFF::IMAGE_REL_AMD64_ADDR64; return std::make_tuple(Offset, RelType, Addend); } Expected processRelocationRef(unsigned SectionID, object::relocation_iterator RelI, const object::ObjectFile &Obj, ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) override { // If possible, find the symbol referred to in the relocation, // and the section that contains it. object::symbol_iterator Symbol = RelI->getSymbol(); if (Symbol == Obj.symbol_end()) report_fatal_error("Unknown symbol in relocation"); auto SectionOrError = Symbol->getSection(); if (!SectionOrError) return SectionOrError.takeError(); object::section_iterator SecI = *SectionOrError; // If there is no section, this must be an external reference. bool IsExtern = SecI == Obj.section_end(); // Determine the Addend used to adjust the relocation value. uint64_t RelType = RelI->getType(); uint64_t Offset = RelI->getOffset(); uint64_t Addend = 0; SectionEntry &Section = Sections[SectionID]; uintptr_t ObjTarget = Section.getObjAddress() + Offset; Expected TargetNameOrErr = Symbol->getName(); if (!TargetNameOrErr) return TargetNameOrErr.takeError(); StringRef TargetName = *TargetNameOrErr; unsigned TargetSectionID = 0; uint64_t TargetOffset = 0; if (TargetName.startswith(getImportSymbolPrefix())) { assert(IsExtern && "DLLImport not marked extern?"); TargetSectionID = SectionID; TargetOffset = getDLLImportOffset(SectionID, Stubs, TargetName); TargetName = StringRef(); IsExtern = false; } else if (!IsExtern) { if (auto TargetSectionIDOrErr = findOrEmitSection(Obj, *SecI, SecI->isText(), ObjSectionToID)) TargetSectionID = *TargetSectionIDOrErr; else return TargetSectionIDOrErr.takeError(); TargetOffset = getSymbolOffset(*Symbol); } switch (RelType) { case COFF::IMAGE_REL_AMD64_REL32: case COFF::IMAGE_REL_AMD64_REL32_1: case COFF::IMAGE_REL_AMD64_REL32_2: case COFF::IMAGE_REL_AMD64_REL32_3: case COFF::IMAGE_REL_AMD64_REL32_4: case COFF::IMAGE_REL_AMD64_REL32_5: case COFF::IMAGE_REL_AMD64_ADDR32NB: { uint8_t *Displacement = (uint8_t *)ObjTarget; Addend = readBytesUnaligned(Displacement, 4); if (IsExtern) std::tie(Offset, RelType, Addend) = generateRelocationStub( SectionID, TargetName, Offset, RelType, Addend, Stubs); break; } case COFF::IMAGE_REL_AMD64_ADDR64: { uint8_t *Displacement = (uint8_t *)ObjTarget; Addend = readBytesUnaligned(Displacement, 8); break; } default: break; } LLVM_DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset << " RelType: " << RelType << " TargetName: " << TargetName << " Addend " << Addend << "\n"); if (IsExtern) { RelocationEntry RE(SectionID, Offset, RelType, Addend); addRelocationForSymbol(RE, TargetName); } else { RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend); addRelocationForSection(RE, TargetSectionID); } return ++RelI; } void registerEHFrames() override { for (auto const &EHFrameSID : UnregisteredEHFrameSections) { uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress(); uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress(); size_t EHFrameSize = Sections[EHFrameSID].getSize(); MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize); RegisteredEHFrameSections.push_back(EHFrameSID); } UnregisteredEHFrameSections.clear(); } Error finalizeLoad(const object::ObjectFile &Obj, ObjSectionToIDMap &SectionMap) override { // Look for and record the EH frame section IDs. for (const auto &SectionPair : SectionMap) { const object::SectionRef &Section = SectionPair.first; Expected NameOrErr = Section.getName(); if (!NameOrErr) return NameOrErr.takeError(); // Note unwind info is stored in .pdata but often points to .xdata // with an IMAGE_REL_AMD64_ADDR32NB relocation. Using a memory manager // that keeps sections ordered in relation to __ImageBase is necessary. if ((*NameOrErr) == ".pdata") UnregisteredEHFrameSections.push_back(SectionPair.second); } return Error::success(); } }; } // end namespace llvm #undef DEBUG_TYPE #endif