1 //===-- RuntimeDyld.cpp - Run-time dynamic linker for MC-JIT ----*- 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 // Implementation of the MC-JIT runtime dynamic linker.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/ExecutionEngine/RuntimeDyld.h"
15 #include "RuntimeDyldCheckerImpl.h"
16 #include "RuntimeDyldCOFF.h"
17 #include "RuntimeDyldELF.h"
18 #include "RuntimeDyldImpl.h"
19 #include "RuntimeDyldMachO.h"
20 #include "llvm/Object/ELFObjectFile.h"
21 #include "llvm/Object/COFF.h"
22 #include "llvm/Support/MathExtras.h"
23 #include "llvm/Support/MutexGuard.h"
26 using namespace llvm::object;
28 #define DEBUG_TYPE "dyld"
30 // Empty out-of-line virtual destructor as the key function.
31 RuntimeDyldImpl::~RuntimeDyldImpl() {}
33 // Pin LoadedObjectInfo's vtables to this file.
34 void RuntimeDyld::LoadedObjectInfo::anchor() {}
38 void RuntimeDyldImpl::registerEHFrames() {}
40 void RuntimeDyldImpl::deregisterEHFrames() {}
43 static void dumpSectionMemory(const SectionEntry &S, StringRef State) {
44 dbgs() << "----- Contents of section " << S.Name << " " << State << " -----";
46 if (S.Address == nullptr) {
47 dbgs() << "\n <section not emitted>\n";
51 const unsigned ColsPerRow = 16;
53 uint8_t *DataAddr = S.Address;
54 uint64_t LoadAddr = S.LoadAddress;
56 unsigned StartPadding = LoadAddr & (ColsPerRow - 1);
57 unsigned BytesRemaining = S.Size;
60 dbgs() << "\n" << format("0x%016" PRIx64,
61 LoadAddr & ~(uint64_t)(ColsPerRow - 1)) << ":";
62 while (StartPadding--)
66 while (BytesRemaining > 0) {
67 if ((LoadAddr & (ColsPerRow - 1)) == 0)
68 dbgs() << "\n" << format("0x%016" PRIx64, LoadAddr) << ":";
70 dbgs() << " " << format("%02x", *DataAddr);
81 // Resolve the relocations for all symbols we currently know about.
82 void RuntimeDyldImpl::resolveRelocations() {
83 MutexGuard locked(lock);
85 // Print out the sections prior to relocation.
87 for (int i = 0, e = Sections.size(); i != e; ++i)
88 dumpSectionMemory(Sections[i], "before relocations");
91 // First, resolve relocations associated with external symbols.
92 resolveExternalSymbols();
94 // Iterate over all outstanding relocations
95 for (auto it = Relocations.begin(), e = Relocations.end(); it != e; ++it) {
96 // The Section here (Sections[i]) refers to the section in which the
97 // symbol for the relocation is located. The SectionID in the relocation
98 // entry provides the section to which the relocation will be applied.
99 int Idx = it->getFirst();
100 uint64_t Addr = Sections[Idx].LoadAddress;
101 DEBUG(dbgs() << "Resolving relocations Section #" << Idx << "\t"
102 << format("%p", (uintptr_t)Addr) << "\n");
103 resolveRelocationList(it->getSecond(), Addr);
107 // Print out sections after relocation.
109 for (int i = 0, e = Sections.size(); i != e; ++i)
110 dumpSectionMemory(Sections[i], "after relocations");
115 void RuntimeDyldImpl::mapSectionAddress(const void *LocalAddress,
116 uint64_t TargetAddress) {
117 MutexGuard locked(lock);
118 for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
119 if (Sections[i].Address == LocalAddress) {
120 reassignSectionAddress(i, TargetAddress);
124 llvm_unreachable("Attempting to remap address of unknown section!");
127 static std::error_code getOffset(const SymbolRef &Sym, SectionRef Sec,
129 ErrorOr<uint64_t> AddressOrErr = Sym.getAddress();
130 if (std::error_code EC = AddressOrErr.getError())
132 Result = *AddressOrErr - Sec.getAddress();
133 return std::error_code();
136 RuntimeDyldImpl::ObjSectionToIDMap
137 RuntimeDyldImpl::loadObjectImpl(const object::ObjectFile &Obj) {
138 MutexGuard locked(lock);
140 // Save information about our target
141 Arch = (Triple::ArchType)Obj.getArch();
142 IsTargetLittleEndian = Obj.isLittleEndian();
145 // Compute the memory size required to load all sections to be loaded
146 // and pass this information to the memory manager
147 if (MemMgr.needsToReserveAllocationSpace()) {
148 uint64_t CodeSize = 0, DataSizeRO = 0, DataSizeRW = 0;
149 computeTotalAllocSize(Obj, CodeSize, DataSizeRO, DataSizeRW);
150 MemMgr.reserveAllocationSpace(CodeSize, DataSizeRO, DataSizeRW);
153 // Used sections from the object file
154 ObjSectionToIDMap LocalSections;
156 // Common symbols requiring allocation, with their sizes and alignments
157 CommonSymbolList CommonSymbols;
160 DEBUG(dbgs() << "Parse symbols:\n");
161 for (symbol_iterator I = Obj.symbol_begin(), E = Obj.symbol_end(); I != E;
163 uint32_t Flags = I->getFlags();
165 if (Flags & SymbolRef::SF_Common)
166 CommonSymbols.push_back(*I);
168 object::SymbolRef::Type SymType = I->getType();
171 ErrorOr<StringRef> NameOrErr = I->getName();
172 Check(NameOrErr.getError());
173 StringRef Name = *NameOrErr;
175 // Compute JIT symbol flags.
176 JITSymbolFlags RTDyldSymFlags = JITSymbolFlags::None;
177 if (Flags & SymbolRef::SF_Weak)
178 RTDyldSymFlags |= JITSymbolFlags::Weak;
179 if (Flags & SymbolRef::SF_Exported)
180 RTDyldSymFlags |= JITSymbolFlags::Exported;
182 if (Flags & SymbolRef::SF_Absolute) {
183 auto Addr = I->getAddress();
184 Check(Addr.getError());
185 uint64_t SectOffset = *Addr;
186 unsigned SectionID = AbsoluteSymbolSection;
188 DEBUG(dbgs() << "\tType: " << SymType << " (absolute) Name: " << Name
189 << " SID: " << SectionID << " Offset: "
190 << format("%p", (uintptr_t)SectOffset)
191 << " flags: " << Flags << "\n");
192 GlobalSymbolTable[Name] =
193 SymbolTableEntry(SectionID, SectOffset, RTDyldSymFlags);
194 } else if (SymType == object::SymbolRef::ST_Function ||
195 SymType == object::SymbolRef::ST_Data ||
196 SymType == object::SymbolRef::ST_Unknown ||
197 SymType == object::SymbolRef::ST_Other) {
199 ErrorOr<section_iterator> SIOrErr = I->getSection();
200 Check(SIOrErr.getError());
201 section_iterator SI = *SIOrErr;
202 if (SI == Obj.section_end())
204 // Get symbol offset.
206 Check(getOffset(*I, *SI, SectOffset));
207 bool IsCode = SI->isText();
208 unsigned SectionID = findOrEmitSection(Obj, *SI, IsCode, LocalSections);
210 DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name
211 << " SID: " << SectionID << " Offset: "
212 << format("%p", (uintptr_t)SectOffset)
213 << " flags: " << Flags << "\n");
214 GlobalSymbolTable[Name] =
215 SymbolTableEntry(SectionID, SectOffset, RTDyldSymFlags);
220 // Allocate common symbols
221 emitCommonSymbols(Obj, CommonSymbols);
223 // Parse and process relocations
224 DEBUG(dbgs() << "Parse relocations:\n");
225 for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
227 unsigned SectionID = 0;
229 section_iterator RelocatedSection = SI->getRelocatedSection();
231 if (RelocatedSection == SE)
234 relocation_iterator I = SI->relocation_begin();
235 relocation_iterator E = SI->relocation_end();
237 if (I == E && !ProcessAllSections)
240 bool IsCode = RelocatedSection->isText();
242 findOrEmitSection(Obj, *RelocatedSection, IsCode, LocalSections);
243 DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
246 I = processRelocationRef(SectionID, I, Obj, LocalSections, Stubs);
248 // If there is an attached checker, notify it about the stubs for this
249 // section so that they can be verified.
251 Checker->registerStubMap(Obj.getFileName(), SectionID, Stubs);
254 // Give the subclasses a chance to tie-up any loose ends.
255 finalizeLoad(Obj, LocalSections);
257 // for (auto E : LocalSections)
258 // llvm::dbgs() << "Added: " << E.first.getRawDataRefImpl() << " -> " << E.second << "\n";
260 return LocalSections;
263 // A helper method for computeTotalAllocSize.
264 // Computes the memory size required to allocate sections with the given sizes,
265 // assuming that all sections are allocated with the given alignment
267 computeAllocationSizeForSections(std::vector<uint64_t> &SectionSizes,
268 uint64_t Alignment) {
269 uint64_t TotalSize = 0;
270 for (size_t Idx = 0, Cnt = SectionSizes.size(); Idx < Cnt; Idx++) {
271 uint64_t AlignedSize =
272 (SectionSizes[Idx] + Alignment - 1) / Alignment * Alignment;
273 TotalSize += AlignedSize;
278 static bool isRequiredForExecution(const SectionRef Section) {
279 const ObjectFile *Obj = Section.getObject();
280 if (isa<object::ELFObjectFileBase>(Obj))
281 return ELFSectionRef(Section).getFlags() & ELF::SHF_ALLOC;
282 if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj)) {
283 const coff_section *CoffSection = COFFObj->getCOFFSection(Section);
284 // Avoid loading zero-sized COFF sections.
285 // In PE files, VirtualSize gives the section size, and SizeOfRawData
286 // may be zero for sections with content. In Obj files, SizeOfRawData
287 // gives the section size, and VirtualSize is always zero. Hence
288 // the need to check for both cases below.
289 bool HasContent = (CoffSection->VirtualSize > 0)
290 || (CoffSection->SizeOfRawData > 0);
291 bool IsDiscardable = CoffSection->Characteristics &
292 (COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_LNK_INFO);
293 return HasContent && !IsDiscardable;
296 assert(isa<MachOObjectFile>(Obj));
300 static bool isReadOnlyData(const SectionRef Section) {
301 const ObjectFile *Obj = Section.getObject();
302 if (isa<object::ELFObjectFileBase>(Obj))
303 return !(ELFSectionRef(Section).getFlags() &
304 (ELF::SHF_WRITE | ELF::SHF_EXECINSTR));
305 if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj))
306 return ((COFFObj->getCOFFSection(Section)->Characteristics &
307 (COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
308 | COFF::IMAGE_SCN_MEM_READ
309 | COFF::IMAGE_SCN_MEM_WRITE))
311 (COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
312 | COFF::IMAGE_SCN_MEM_READ));
314 assert(isa<MachOObjectFile>(Obj));
318 static bool isZeroInit(const SectionRef Section) {
319 const ObjectFile *Obj = Section.getObject();
320 if (isa<object::ELFObjectFileBase>(Obj))
321 return ELFSectionRef(Section).getType() == ELF::SHT_NOBITS;
322 if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj))
323 return COFFObj->getCOFFSection(Section)->Characteristics &
324 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA;
326 auto *MachO = cast<MachOObjectFile>(Obj);
327 unsigned SectionType = MachO->getSectionType(Section);
328 return SectionType == MachO::S_ZEROFILL ||
329 SectionType == MachO::S_GB_ZEROFILL;
332 // Compute an upper bound of the memory size that is required to load all
334 void RuntimeDyldImpl::computeTotalAllocSize(const ObjectFile &Obj,
336 uint64_t &DataSizeRO,
337 uint64_t &DataSizeRW) {
338 // Compute the size of all sections required for execution
339 std::vector<uint64_t> CodeSectionSizes;
340 std::vector<uint64_t> ROSectionSizes;
341 std::vector<uint64_t> RWSectionSizes;
342 uint64_t MaxAlignment = sizeof(void *);
344 // Collect sizes of all sections to be loaded;
345 // also determine the max alignment of all sections
346 for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
348 const SectionRef &Section = *SI;
350 bool IsRequired = isRequiredForExecution(Section);
352 // Consider only the sections that are required to be loaded for execution
355 uint64_t DataSize = Section.getSize();
356 uint64_t Alignment64 = Section.getAlignment();
357 bool IsCode = Section.isText();
358 bool IsReadOnly = isReadOnlyData(Section);
359 Check(Section.getName(Name));
360 unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
362 uint64_t StubBufSize = computeSectionStubBufSize(Obj, Section);
363 uint64_t SectionSize = DataSize + StubBufSize;
365 // The .eh_frame section (at least on Linux) needs an extra four bytes
367 // with zeroes added at the end. For MachO objects, this section has a
368 // slightly different name, so this won't have any effect for MachO
370 if (Name == ".eh_frame")
377 CodeSectionSizes.push_back(SectionSize);
378 } else if (IsReadOnly) {
379 ROSectionSizes.push_back(SectionSize);
381 RWSectionSizes.push_back(SectionSize);
384 // update the max alignment
385 if (Alignment > MaxAlignment) {
386 MaxAlignment = Alignment;
391 // Compute the size of all common symbols
392 uint64_t CommonSize = 0;
393 for (symbol_iterator I = Obj.symbol_begin(), E = Obj.symbol_end(); I != E;
395 uint32_t Flags = I->getFlags();
396 if (Flags & SymbolRef::SF_Common) {
397 // Add the common symbols to a list. We'll allocate them all below.
398 uint64_t Size = I->getCommonSize();
402 if (CommonSize != 0) {
403 RWSectionSizes.push_back(CommonSize);
406 // Compute the required allocation space for each different type of sections
407 // (code, read-only data, read-write data) assuming that all sections are
408 // allocated with the max alignment. Note that we cannot compute with the
409 // individual alignments of the sections, because then the required size
410 // depends on the order, in which the sections are allocated.
411 CodeSize = computeAllocationSizeForSections(CodeSectionSizes, MaxAlignment);
412 DataSizeRO = computeAllocationSizeForSections(ROSectionSizes, MaxAlignment);
413 DataSizeRW = computeAllocationSizeForSections(RWSectionSizes, MaxAlignment);
416 // compute stub buffer size for the given section
417 unsigned RuntimeDyldImpl::computeSectionStubBufSize(const ObjectFile &Obj,
418 const SectionRef &Section) {
419 unsigned StubSize = getMaxStubSize();
423 // FIXME: this is an inefficient way to handle this. We should computed the
424 // necessary section allocation size in loadObject by walking all the sections
426 unsigned StubBufSize = 0;
427 for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
429 section_iterator RelSecI = SI->getRelocatedSection();
430 if (!(RelSecI == Section))
433 for (const RelocationRef &Reloc : SI->relocations()) {
435 StubBufSize += StubSize;
439 // Get section data size and alignment
440 uint64_t DataSize = Section.getSize();
441 uint64_t Alignment64 = Section.getAlignment();
443 // Add stubbuf size alignment
444 unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
445 unsigned StubAlignment = getStubAlignment();
446 unsigned EndAlignment = (DataSize | Alignment) & -(DataSize | Alignment);
447 if (StubAlignment > EndAlignment)
448 StubBufSize += StubAlignment - EndAlignment;
452 uint64_t RuntimeDyldImpl::readBytesUnaligned(uint8_t *Src,
453 unsigned Size) const {
455 if (IsTargetLittleEndian) {
458 Result = (Result << 8) | *Src--;
461 Result = (Result << 8) | *Src++;
466 void RuntimeDyldImpl::writeBytesUnaligned(uint64_t Value, uint8_t *Dst,
467 unsigned Size) const {
468 if (IsTargetLittleEndian) {
470 *Dst++ = Value & 0xFF;
476 *Dst-- = Value & 0xFF;
482 void RuntimeDyldImpl::emitCommonSymbols(const ObjectFile &Obj,
483 CommonSymbolList &CommonSymbols) {
484 if (CommonSymbols.empty())
487 uint64_t CommonSize = 0;
488 CommonSymbolList SymbolsToAllocate;
490 DEBUG(dbgs() << "Processing common symbols...\n");
492 for (const auto &Sym : CommonSymbols) {
493 ErrorOr<StringRef> NameOrErr = Sym.getName();
494 Check(NameOrErr.getError());
495 StringRef Name = *NameOrErr;
497 // Skip common symbols already elsewhere.
498 if (GlobalSymbolTable.count(Name) ||
499 Resolver.findSymbolInLogicalDylib(Name)) {
500 DEBUG(dbgs() << "\tSkipping already emitted common symbol '" << Name
505 uint32_t Align = Sym.getAlignment();
506 uint64_t Size = Sym.getCommonSize();
508 CommonSize += Align + Size;
509 SymbolsToAllocate.push_back(Sym);
512 // Allocate memory for the section
513 unsigned SectionID = Sections.size();
514 uint8_t *Addr = MemMgr.allocateDataSection(CommonSize, sizeof(void *),
515 SectionID, StringRef(), false);
517 report_fatal_error("Unable to allocate memory for common symbols!");
519 Sections.push_back(SectionEntry("<common symbols>", Addr, CommonSize, 0));
520 memset(Addr, 0, CommonSize);
522 DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID << " new addr: "
523 << format("%p", Addr) << " DataSize: " << CommonSize << "\n");
525 // Assign the address of each symbol
526 for (auto &Sym : SymbolsToAllocate) {
527 uint32_t Align = Sym.getAlignment();
528 uint64_t Size = Sym.getCommonSize();
529 ErrorOr<StringRef> NameOrErr = Sym.getName();
530 Check(NameOrErr.getError());
531 StringRef Name = *NameOrErr;
533 // This symbol has an alignment requirement.
534 uint64_t AlignOffset = OffsetToAlignment((uint64_t)Addr, Align);
536 Offset += AlignOffset;
538 uint32_t Flags = Sym.getFlags();
539 JITSymbolFlags RTDyldSymFlags = JITSymbolFlags::None;
540 if (Flags & SymbolRef::SF_Weak)
541 RTDyldSymFlags |= JITSymbolFlags::Weak;
542 if (Flags & SymbolRef::SF_Exported)
543 RTDyldSymFlags |= JITSymbolFlags::Exported;
544 DEBUG(dbgs() << "Allocating common symbol " << Name << " address "
545 << format("%p", Addr) << "\n");
546 GlobalSymbolTable[Name] =
547 SymbolTableEntry(SectionID, Offset, RTDyldSymFlags);
553 Checker->registerSection(Obj.getFileName(), SectionID);
556 unsigned RuntimeDyldImpl::emitSection(const ObjectFile &Obj,
557 const SectionRef &Section, bool IsCode) {
560 uint64_t Alignment64 = Section.getAlignment();
562 unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
563 unsigned PaddingSize = 0;
564 unsigned StubBufSize = 0;
566 bool IsRequired = isRequiredForExecution(Section);
567 bool IsVirtual = Section.isVirtual();
568 bool IsZeroInit = isZeroInit(Section);
569 bool IsReadOnly = isReadOnlyData(Section);
570 uint64_t DataSize = Section.getSize();
571 Check(Section.getName(Name));
573 StubBufSize = computeSectionStubBufSize(Obj, Section);
575 // The .eh_frame section (at least on Linux) needs an extra four bytes padded
576 // with zeroes added at the end. For MachO objects, this section has a
577 // slightly different name, so this won't have any effect for MachO objects.
578 if (Name == ".eh_frame")
582 unsigned SectionID = Sections.size();
584 const char *pData = nullptr;
586 // If this section contains any bits (i.e. isn't a virtual or bss section),
587 // grab a reference to them.
588 if (!IsVirtual && !IsZeroInit) {
589 // In either case, set the location of the unrelocated section in memory,
590 // since we still process relocations for it even if we're not applying them.
591 Check(Section.getContents(data));
595 // Code section alignment needs to be at least as high as stub alignment or
596 // padding calculations may by incorrect when the section is remapped to a
599 Alignment = std::max(Alignment, getStubAlignment());
601 // Some sections, such as debug info, don't need to be loaded for execution.
602 // Leave those where they are.
604 Allocate = DataSize + PaddingSize + StubBufSize;
607 Addr = IsCode ? MemMgr.allocateCodeSection(Allocate, Alignment, SectionID,
609 : MemMgr.allocateDataSection(Allocate, Alignment, SectionID,
612 report_fatal_error("Unable to allocate section memory!");
614 // Zero-initialize or copy the data from the image
615 if (IsZeroInit || IsVirtual)
616 memset(Addr, 0, DataSize);
618 memcpy(Addr, pData, DataSize);
620 // Fill in any extra bytes we allocated for padding
621 if (PaddingSize != 0) {
622 memset(Addr + DataSize, 0, PaddingSize);
623 // Update the DataSize variable so that the stub offset is set correctly.
624 DataSize += PaddingSize;
627 DEBUG(dbgs() << "emitSection SectionID: " << SectionID << " Name: " << Name
628 << " obj addr: " << format("%p", pData)
629 << " new addr: " << format("%p", Addr)
630 << " DataSize: " << DataSize << " StubBufSize: " << StubBufSize
631 << " Allocate: " << Allocate << "\n");
633 // Even if we didn't load the section, we need to record an entry for it
634 // to handle later processing (and by 'handle' I mean don't do anything
635 // with these sections).
638 DEBUG(dbgs() << "emitSection SectionID: " << SectionID << " Name: " << Name
639 << " obj addr: " << format("%p", data.data()) << " new addr: 0"
640 << " DataSize: " << DataSize << " StubBufSize: " << StubBufSize
641 << " Allocate: " << Allocate << "\n");
644 Sections.push_back(SectionEntry(Name, Addr, DataSize, (uintptr_t)pData));
647 Checker->registerSection(Obj.getFileName(), SectionID);
652 unsigned RuntimeDyldImpl::findOrEmitSection(const ObjectFile &Obj,
653 const SectionRef &Section,
655 ObjSectionToIDMap &LocalSections) {
657 unsigned SectionID = 0;
658 ObjSectionToIDMap::iterator i = LocalSections.find(Section);
659 if (i != LocalSections.end())
660 SectionID = i->second;
662 SectionID = emitSection(Obj, Section, IsCode);
663 LocalSections[Section] = SectionID;
668 void RuntimeDyldImpl::addRelocationForSection(const RelocationEntry &RE,
669 unsigned SectionID) {
670 Relocations[SectionID].push_back(RE);
673 void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
674 StringRef SymbolName) {
675 // Relocation by symbol. If the symbol is found in the global symbol table,
676 // create an appropriate section relocation. Otherwise, add it to
677 // ExternalSymbolRelocations.
678 RTDyldSymbolTable::const_iterator Loc = GlobalSymbolTable.find(SymbolName);
679 if (Loc == GlobalSymbolTable.end()) {
680 ExternalSymbolRelocations[SymbolName].push_back(RE);
682 // Copy the RE since we want to modify its addend.
683 RelocationEntry RECopy = RE;
684 const auto &SymInfo = Loc->second;
685 RECopy.Addend += SymInfo.getOffset();
686 Relocations[SymInfo.getSectionID()].push_back(RECopy);
690 uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr,
691 unsigned AbiVariant) {
692 if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be) {
693 // This stub has to be able to access the full address space,
694 // since symbol lookup won't necessarily find a handy, in-range,
695 // PLT stub for functions which could be anywhere.
696 // Stub can use ip0 (== x16) to calculate address
697 writeBytesUnaligned(0xd2e00010, Addr, 4); // movz ip0, #:abs_g3:<addr>
698 writeBytesUnaligned(0xf2c00010, Addr+4, 4); // movk ip0, #:abs_g2_nc:<addr>
699 writeBytesUnaligned(0xf2a00010, Addr+8, 4); // movk ip0, #:abs_g1_nc:<addr>
700 writeBytesUnaligned(0xf2800010, Addr+12, 4); // movk ip0, #:abs_g0_nc:<addr>
701 writeBytesUnaligned(0xd61f0200, Addr+16, 4); // br ip0
704 } else if (Arch == Triple::arm || Arch == Triple::armeb) {
705 // TODO: There is only ARM far stub now. We should add the Thumb stub,
706 // and stubs for branches Thumb - ARM and ARM - Thumb.
707 writeBytesUnaligned(0xe51ff004, Addr, 4); // ldr pc,<label>
709 } else if (IsMipsO32ABI) {
710 // 0: 3c190000 lui t9,%hi(addr).
711 // 4: 27390000 addiu t9,t9,%lo(addr).
712 // 8: 03200008 jr t9.
714 const unsigned LuiT9Instr = 0x3c190000, AdduiT9Instr = 0x27390000;
715 const unsigned JrT9Instr = 0x03200008, NopInstr = 0x0;
717 writeBytesUnaligned(LuiT9Instr, Addr, 4);
718 writeBytesUnaligned(AdduiT9Instr, Addr+4, 4);
719 writeBytesUnaligned(JrT9Instr, Addr+8, 4);
720 writeBytesUnaligned(NopInstr, Addr+12, 4);
722 } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
723 // Depending on which version of the ELF ABI is in use, we need to
724 // generate one of two variants of the stub. They both start with
725 // the same sequence to load the target address into r12.
726 writeInt32BE(Addr, 0x3D800000); // lis r12, highest(addr)
727 writeInt32BE(Addr+4, 0x618C0000); // ori r12, higher(addr)
728 writeInt32BE(Addr+8, 0x798C07C6); // sldi r12, r12, 32
729 writeInt32BE(Addr+12, 0x658C0000); // oris r12, r12, h(addr)
730 writeInt32BE(Addr+16, 0x618C0000); // ori r12, r12, l(addr)
731 if (AbiVariant == 2) {
732 // PowerPC64 stub ELFv2 ABI: The address points to the function itself.
733 // The address is already in r12 as required by the ABI. Branch to it.
734 writeInt32BE(Addr+20, 0xF8410018); // std r2, 24(r1)
735 writeInt32BE(Addr+24, 0x7D8903A6); // mtctr r12
736 writeInt32BE(Addr+28, 0x4E800420); // bctr
738 // PowerPC64 stub ELFv1 ABI: The address points to a function descriptor.
739 // Load the function address on r11 and sets it to control register. Also
740 // loads the function TOC in r2 and environment pointer to r11.
741 writeInt32BE(Addr+20, 0xF8410028); // std r2, 40(r1)
742 writeInt32BE(Addr+24, 0xE96C0000); // ld r11, 0(r12)
743 writeInt32BE(Addr+28, 0xE84C0008); // ld r2, 0(r12)
744 writeInt32BE(Addr+32, 0x7D6903A6); // mtctr r11
745 writeInt32BE(Addr+36, 0xE96C0010); // ld r11, 16(r2)
746 writeInt32BE(Addr+40, 0x4E800420); // bctr
749 } else if (Arch == Triple::systemz) {
750 writeInt16BE(Addr, 0xC418); // lgrl %r1,.+8
751 writeInt16BE(Addr+2, 0x0000);
752 writeInt16BE(Addr+4, 0x0004);
753 writeInt16BE(Addr+6, 0x07F1); // brc 15,%r1
754 // 8-byte address stored at Addr + 8
756 } else if (Arch == Triple::x86_64) {
758 *(Addr+1) = 0x25; // rip
759 // 32-bit PC-relative address of the GOT entry will be stored at Addr+2
760 } else if (Arch == Triple::x86) {
761 *Addr = 0xE9; // 32-bit pc-relative jump.
766 // Assign an address to a symbol name and resolve all the relocations
767 // associated with it.
768 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
770 // The address to use for relocation resolution is not
771 // the address of the local section buffer. We must be doing
772 // a remote execution environment of some sort. Relocations can't
773 // be applied until all the sections have been moved. The client must
774 // trigger this with a call to MCJIT::finalize() or
775 // RuntimeDyld::resolveRelocations().
777 // Addr is a uint64_t because we can't assume the pointer width
778 // of the target is the same as that of the host. Just use a generic
779 // "big enough" type.
780 DEBUG(dbgs() << "Reassigning address for section "
781 << SectionID << " (" << Sections[SectionID].Name << "): "
782 << format("0x%016" PRIx64, Sections[SectionID].LoadAddress) << " -> "
783 << format("0x%016" PRIx64, Addr) << "\n");
784 Sections[SectionID].LoadAddress = Addr;
787 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
789 for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
790 const RelocationEntry &RE = Relocs[i];
791 // Ignore relocations for sections that were not loaded
792 if (Sections[RE.SectionID].Address == nullptr)
794 resolveRelocation(RE, Value);
798 void RuntimeDyldImpl::resolveExternalSymbols() {
799 while (!ExternalSymbolRelocations.empty()) {
800 StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin();
802 StringRef Name = i->first();
803 if (Name.size() == 0) {
804 // This is an absolute symbol, use an address of zero.
805 DEBUG(dbgs() << "Resolving absolute relocations."
807 RelocationList &Relocs = i->second;
808 resolveRelocationList(Relocs, 0);
811 RTDyldSymbolTable::const_iterator Loc = GlobalSymbolTable.find(Name);
812 if (Loc == GlobalSymbolTable.end()) {
813 // This is an external symbol, try to get its address from the symbol
815 Addr = Resolver.findSymbol(Name.data()).getAddress();
816 // The call to getSymbolAddress may have caused additional modules to
817 // be loaded, which may have added new entries to the
818 // ExternalSymbolRelocations map. Consquently, we need to update our
819 // iterator. This is also why retrieval of the relocation list
820 // associated with this symbol is deferred until below this point.
821 // New entries may have been added to the relocation list.
822 i = ExternalSymbolRelocations.find(Name);
824 // We found the symbol in our global table. It was probably in a
825 // Module that we loaded previously.
826 const auto &SymInfo = Loc->second;
827 Addr = getSectionLoadAddress(SymInfo.getSectionID()) +
831 // FIXME: Implement error handling that doesn't kill the host program!
833 report_fatal_error("Program used external function '" + Name +
834 "' which could not be resolved!");
836 // If Resolver returned UINT64_MAX, the client wants to handle this symbol
837 // manually and we shouldn't resolve its relocations.
838 if (Addr != UINT64_MAX) {
839 DEBUG(dbgs() << "Resolving relocations Name: " << Name << "\t"
840 << format("0x%lx", Addr) << "\n");
841 // This list may have been updated when we called getSymbolAddress, so
842 // don't change this code to get the list earlier.
843 RelocationList &Relocs = i->second;
844 resolveRelocationList(Relocs, Addr);
848 ExternalSymbolRelocations.erase(i);
852 //===----------------------------------------------------------------------===//
853 // RuntimeDyld class implementation
855 uint64_t RuntimeDyld::LoadedObjectInfo::getSectionLoadAddress(
856 const object::SectionRef &Sec) const {
858 // llvm::dbgs() << "Searching for " << Sec.getRawDataRefImpl() << " in:\n";
859 // for (auto E : ObjSecToIDMap)
860 // llvm::dbgs() << "Added: " << E.first.getRawDataRefImpl() << " -> " << E.second << "\n";
862 auto I = ObjSecToIDMap.find(Sec);
863 if (I != ObjSecToIDMap.end()) {
864 // llvm::dbgs() << "Found ID " << I->second << " for Sec: " << Sec.getRawDataRefImpl() << ", LoadAddress = " << RTDyld.Sections[I->second].LoadAddress << "\n";
865 return RTDyld.Sections[I->second].LoadAddress;
867 // llvm::dbgs() << "Not found.\n";
873 void RuntimeDyld::MemoryManager::anchor() {}
874 void RuntimeDyld::SymbolResolver::anchor() {}
876 RuntimeDyld::RuntimeDyld(RuntimeDyld::MemoryManager &MemMgr,
877 RuntimeDyld::SymbolResolver &Resolver)
878 : MemMgr(MemMgr), Resolver(Resolver) {
879 // FIXME: There's a potential issue lurking here if a single instance of
880 // RuntimeDyld is used to load multiple objects. The current implementation
881 // associates a single memory manager with a RuntimeDyld instance. Even
882 // though the public class spawns a new 'impl' instance for each load,
883 // they share a single memory manager. This can become a problem when page
884 // permissions are applied.
886 ProcessAllSections = false;
890 RuntimeDyld::~RuntimeDyld() {}
892 static std::unique_ptr<RuntimeDyldCOFF>
893 createRuntimeDyldCOFF(Triple::ArchType Arch, RuntimeDyld::MemoryManager &MM,
894 RuntimeDyld::SymbolResolver &Resolver,
895 bool ProcessAllSections, RuntimeDyldCheckerImpl *Checker) {
896 std::unique_ptr<RuntimeDyldCOFF> Dyld =
897 RuntimeDyldCOFF::create(Arch, MM, Resolver);
898 Dyld->setProcessAllSections(ProcessAllSections);
899 Dyld->setRuntimeDyldChecker(Checker);
903 static std::unique_ptr<RuntimeDyldELF>
904 createRuntimeDyldELF(RuntimeDyld::MemoryManager &MM,
905 RuntimeDyld::SymbolResolver &Resolver,
906 bool ProcessAllSections, RuntimeDyldCheckerImpl *Checker) {
907 std::unique_ptr<RuntimeDyldELF> Dyld(new RuntimeDyldELF(MM, Resolver));
908 Dyld->setProcessAllSections(ProcessAllSections);
909 Dyld->setRuntimeDyldChecker(Checker);
913 static std::unique_ptr<RuntimeDyldMachO>
914 createRuntimeDyldMachO(Triple::ArchType Arch, RuntimeDyld::MemoryManager &MM,
915 RuntimeDyld::SymbolResolver &Resolver,
916 bool ProcessAllSections,
917 RuntimeDyldCheckerImpl *Checker) {
918 std::unique_ptr<RuntimeDyldMachO> Dyld =
919 RuntimeDyldMachO::create(Arch, MM, Resolver);
920 Dyld->setProcessAllSections(ProcessAllSections);
921 Dyld->setRuntimeDyldChecker(Checker);
925 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
926 RuntimeDyld::loadObject(const ObjectFile &Obj) {
929 Dyld = createRuntimeDyldELF(MemMgr, Resolver, ProcessAllSections, Checker);
930 else if (Obj.isMachO())
931 Dyld = createRuntimeDyldMachO(
932 static_cast<Triple::ArchType>(Obj.getArch()), MemMgr, Resolver,
933 ProcessAllSections, Checker);
934 else if (Obj.isCOFF())
935 Dyld = createRuntimeDyldCOFF(
936 static_cast<Triple::ArchType>(Obj.getArch()), MemMgr, Resolver,
937 ProcessAllSections, Checker);
939 report_fatal_error("Incompatible object format!");
942 if (!Dyld->isCompatibleFile(Obj))
943 report_fatal_error("Incompatible object format!");
945 return Dyld->loadObject(Obj);
948 void *RuntimeDyld::getSymbolLocalAddress(StringRef Name) const {
951 return Dyld->getSymbolLocalAddress(Name);
954 RuntimeDyld::SymbolInfo RuntimeDyld::getSymbol(StringRef Name) const {
957 return Dyld->getSymbol(Name);
960 void RuntimeDyld::resolveRelocations() { Dyld->resolveRelocations(); }
962 void RuntimeDyld::reassignSectionAddress(unsigned SectionID, uint64_t Addr) {
963 Dyld->reassignSectionAddress(SectionID, Addr);
966 void RuntimeDyld::mapSectionAddress(const void *LocalAddress,
967 uint64_t TargetAddress) {
968 Dyld->mapSectionAddress(LocalAddress, TargetAddress);
971 bool RuntimeDyld::hasError() { return Dyld->hasError(); }
973 StringRef RuntimeDyld::getErrorString() { return Dyld->getErrorString(); }
975 void RuntimeDyld::registerEHFrames() {
977 Dyld->registerEHFrames();
980 void RuntimeDyld::deregisterEHFrames() {
982 Dyld->deregisterEHFrames();
985 } // end namespace llvm