1 //===-- RuntimeDyldCOFFX86_64.h --- COFF/X86_64 specific code ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // COFF x86_x64 support for MC-JIT runtime dynamic linker.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFF86_64_H
15 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDCOFF86_64_H
17 #include "../RuntimeDyldCOFF.h"
18 #include "llvm/BinaryFormat/COFF.h"
19 #include "llvm/Object/COFF.h"
21 #define DEBUG_TYPE "dyld"
25 class RuntimeDyldCOFFX86_64 : public RuntimeDyldCOFF {
28 // When a module is loaded we save the SectionID of the unwind
29 // sections in a table until we receive a request to register all
30 // unregisteredEH frame sections with the memory manager.
31 SmallVector<SID, 2> UnregisteredEHFrameSections;
32 SmallVector<SID, 2> RegisteredEHFrameSections;
35 // Fake an __ImageBase pointer by returning the section with the lowest adress
36 uint64_t getImageBase() {
38 ImageBase = std::numeric_limits<uint64_t>::max();
39 for (const SectionEntry &Section : Sections)
40 ImageBase = std::min(ImageBase, Section.getLoadAddress());
45 void write32BitOffset(uint8_t *Target, int64_t Addend, uint64_t Delta) {
46 uint64_t Result = Addend + Delta;
47 assert(Result <= UINT32_MAX && "Relocation overflow");
48 writeBytesUnaligned(Result, Target, 4);
52 RuntimeDyldCOFFX86_64(RuntimeDyld::MemoryManager &MM,
53 JITSymbolResolver &Resolver)
54 : RuntimeDyldCOFF(MM, Resolver), ImageBase(0) {}
56 unsigned getStubAlignment() override { return 1; }
58 // 2-byte jmp instruction + 32-bit relative address + 64-bit absolute jump
59 unsigned getMaxStubSize() override { return 14; }
61 // The target location for the relocation is described by RE.SectionID and
62 // RE.Offset. RE.SectionID can be used to find the SectionEntry. Each
63 // SectionEntry has three members describing its location.
64 // SectionEntry::Address is the address at which the section has been loaded
65 // into memory in the current (host) process. SectionEntry::LoadAddress is
66 // the address that the section will have in the target process.
67 // SectionEntry::ObjAddress is the address of the bits for this section in the
68 // original emitted object image (also in the current address space).
70 // Relocations will be applied as if the section were loaded at
71 // SectionEntry::LoadAddress, but they will be applied at an address based
72 // on SectionEntry::Address. SectionEntry::ObjAddress will be used to refer
73 // to Target memory contents if they are required for value calculations.
75 // The Value parameter here is the load address of the symbol for the
76 // relocation to be applied. For relocations which refer to symbols in the
77 // current object Value will be the LoadAddress of the section in which
78 // the symbol resides (RE.Addend provides additional information about the
79 // symbol location). For external symbols, Value will be the address of the
80 // symbol in the target address space.
81 void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
82 const SectionEntry &Section = Sections[RE.SectionID];
83 uint8_t *Target = Section.getAddressWithOffset(RE.Offset);
87 case COFF::IMAGE_REL_AMD64_REL32:
88 case COFF::IMAGE_REL_AMD64_REL32_1:
89 case COFF::IMAGE_REL_AMD64_REL32_2:
90 case COFF::IMAGE_REL_AMD64_REL32_3:
91 case COFF::IMAGE_REL_AMD64_REL32_4:
92 case COFF::IMAGE_REL_AMD64_REL32_5: {
93 uint64_t FinalAddress = Section.getLoadAddressWithOffset(RE.Offset);
94 // Delta is the distance from the start of the reloc to the end of the
95 // instruction with the reloc.
96 uint64_t Delta = 4 + (RE.RelType - COFF::IMAGE_REL_AMD64_REL32);
97 Value -= FinalAddress + Delta;
98 uint64_t Result = Value + RE.Addend;
99 assert(((int64_t)Result <= INT32_MAX) && "Relocation overflow");
100 assert(((int64_t)Result >= INT32_MIN) && "Relocation underflow");
101 writeBytesUnaligned(Result, Target, 4);
105 case COFF::IMAGE_REL_AMD64_ADDR32NB: {
106 // ADDR32NB requires an offset less than 2GB from 'ImageBase'.
107 // The MemoryManager can make sure this is always true by forcing the
108 // memory layout to be: CodeSection < ReadOnlySection < ReadWriteSection.
109 const uint64_t ImageBase = getImageBase();
110 if (Value < ImageBase || ((Value - ImageBase) > UINT32_MAX)) {
111 llvm::errs() << "IMAGE_REL_AMD64_ADDR32NB relocation requires an"
112 << "ordered section layout.\n";
113 write32BitOffset(Target, 0, 0);
115 write32BitOffset(Target, RE.Addend, Value - ImageBase);
120 case COFF::IMAGE_REL_AMD64_ADDR64: {
121 writeBytesUnaligned(Value + RE.Addend, Target, 8);
126 llvm_unreachable("Relocation type not implemented yet!");
131 std::tuple<uint64_t, uint64_t, uint64_t>
132 generateRelocationStub(unsigned SectionID, StringRef TargetName,
133 uint64_t Offset, uint64_t RelType, uint64_t Addend,
135 uintptr_t StubOffset;
136 SectionEntry &Section = Sections[SectionID];
138 RelocationValueRef OriginalRelValueRef;
139 OriginalRelValueRef.SectionID = SectionID;
140 OriginalRelValueRef.Offset = Offset;
141 OriginalRelValueRef.Addend = Addend;
142 OriginalRelValueRef.SymbolName = TargetName.data();
144 auto Stub = Stubs.find(OriginalRelValueRef);
145 if (Stub == Stubs.end()) {
146 LLVM_DEBUG(dbgs() << " Create a new stub function for "
147 << TargetName.data() << "\n");
149 StubOffset = Section.getStubOffset();
150 Stubs[OriginalRelValueRef] = StubOffset;
151 createStubFunction(Section.getAddressWithOffset(StubOffset));
152 Section.advanceStubOffset(getMaxStubSize());
154 LLVM_DEBUG(dbgs() << " Stub function found for " << TargetName.data()
156 StubOffset = Stub->second;
159 // FIXME: If RelType == COFF::IMAGE_REL_AMD64_ADDR32NB we should be able
160 // to ignore the __ImageBase requirement and just forward to the stub
161 // directly as an offset of this section:
162 // write32BitOffset(Section.getAddressWithOffset(Offset), 0, StubOffset);
163 // .xdata exception handler's aren't having this though.
165 // Resolve original relocation to stub function.
166 const RelocationEntry RE(SectionID, Offset, RelType, Addend);
167 resolveRelocation(RE, Section.getLoadAddressWithOffset(StubOffset));
169 // adjust relocation info so resolution writes to the stub function
171 Offset = StubOffset + 6;
172 RelType = COFF::IMAGE_REL_AMD64_ADDR64;
174 return std::make_tuple(Offset, RelType, Addend);
177 Expected<relocation_iterator>
178 processRelocationRef(unsigned SectionID,
179 relocation_iterator RelI,
180 const ObjectFile &Obj,
181 ObjSectionToIDMap &ObjSectionToID,
182 StubMap &Stubs) override {
183 // If possible, find the symbol referred to in the relocation,
184 // and the section that contains it.
185 symbol_iterator Symbol = RelI->getSymbol();
186 if (Symbol == Obj.symbol_end())
187 report_fatal_error("Unknown symbol in relocation");
188 auto SectionOrError = Symbol->getSection();
190 return SectionOrError.takeError();
191 section_iterator SecI = *SectionOrError;
192 // If there is no section, this must be an external reference.
193 const bool IsExtern = SecI == Obj.section_end();
195 // Determine the Addend used to adjust the relocation value.
196 uint64_t RelType = RelI->getType();
197 uint64_t Offset = RelI->getOffset();
199 SectionEntry &Section = Sections[SectionID];
200 uintptr_t ObjTarget = Section.getObjAddress() + Offset;
202 Expected<StringRef> TargetNameOrErr = Symbol->getName();
203 if (!TargetNameOrErr)
204 return TargetNameOrErr.takeError();
205 StringRef TargetName = *TargetNameOrErr;
209 case COFF::IMAGE_REL_AMD64_REL32:
210 case COFF::IMAGE_REL_AMD64_REL32_1:
211 case COFF::IMAGE_REL_AMD64_REL32_2:
212 case COFF::IMAGE_REL_AMD64_REL32_3:
213 case COFF::IMAGE_REL_AMD64_REL32_4:
214 case COFF::IMAGE_REL_AMD64_REL32_5:
215 case COFF::IMAGE_REL_AMD64_ADDR32NB: {
216 uint8_t *Displacement = (uint8_t *)ObjTarget;
217 Addend = readBytesUnaligned(Displacement, 4);
220 std::tie(Offset, RelType, Addend) = generateRelocationStub(
221 SectionID, TargetName, Offset, RelType, Addend, Stubs);
226 case COFF::IMAGE_REL_AMD64_ADDR64: {
227 uint8_t *Displacement = (uint8_t *)ObjTarget;
228 Addend = readBytesUnaligned(Displacement, 8);
236 LLVM_DEBUG(dbgs() << "\t\tIn Section " << SectionID << " Offset " << Offset
237 << " RelType: " << RelType << " TargetName: "
238 << TargetName << " Addend " << Addend << "\n");
241 RelocationEntry RE(SectionID, Offset, RelType, Addend);
242 addRelocationForSymbol(RE, TargetName);
244 bool IsCode = SecI->isText();
245 unsigned TargetSectionID;
246 if (auto TargetSectionIDOrErr =
247 findOrEmitSection(Obj, *SecI, IsCode, ObjSectionToID))
248 TargetSectionID = *TargetSectionIDOrErr;
250 return TargetSectionIDOrErr.takeError();
251 uint64_t TargetOffset = getSymbolOffset(*Symbol);
252 RelocationEntry RE(SectionID, Offset, RelType, TargetOffset + Addend);
253 addRelocationForSection(RE, TargetSectionID);
259 void registerEHFrames() override {
260 for (auto const &EHFrameSID : UnregisteredEHFrameSections) {
261 uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress();
262 uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress();
263 size_t EHFrameSize = Sections[EHFrameSID].getSize();
264 MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
265 RegisteredEHFrameSections.push_back(EHFrameSID);
267 UnregisteredEHFrameSections.clear();
270 Error finalizeLoad(const ObjectFile &Obj,
271 ObjSectionToIDMap &SectionMap) override {
272 // Look for and record the EH frame section IDs.
273 for (const auto &SectionPair : SectionMap) {
274 const SectionRef &Section = SectionPair.first;
276 if (auto EC = Section.getName(Name))
277 return errorCodeToError(EC);
279 // Note unwind info is stored in .pdata but often points to .xdata
280 // with an IMAGE_REL_AMD64_ADDR32NB relocation. Using a memory manager
281 // that keeps sections ordered in relation to __ImageBase is necessary.
282 if (Name == ".pdata")
283 UnregisteredEHFrameSections.push_back(SectionPair.second);
285 return Error::success();
289 } // end namespace llvm