1 //===-- RuntimeDyldImpl.h - 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 // Interface for the implementations of runtime dynamic linker facilities.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDIMPL_H
15 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_RUNTIMEDYLDIMPL_H
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/StringMap.h"
20 #include "llvm/ADT/Triple.h"
21 #include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
22 #include "llvm/ExecutionEngine/RuntimeDyld.h"
23 #include "llvm/ExecutionEngine/RuntimeDyldChecker.h"
24 #include "llvm/Object/ObjectFile.h"
25 #include "llvm/Support/Debug.h"
26 #include "llvm/Support/ErrorHandling.h"
27 #include "llvm/Support/Format.h"
28 #include "llvm/Support/Host.h"
29 #include "llvm/Support/Mutex.h"
30 #include "llvm/Support/SwapByteOrder.h"
31 #include "llvm/Support/raw_ostream.h"
33 #include <system_error>
36 using namespace llvm::object;
40 // Helper for extensive error checking in debug builds.
41 inline std::error_code Check(std::error_code Err) {
43 report_fatal_error(Err.message());
50 /// SectionEntry - represents a section emitted into memory by the dynamic
53 /// Name - section name.
56 /// Address - address in the linker's memory where the section resides.
59 /// Size - section size. Doesn't include the stubs.
62 /// LoadAddress - the address of the section in the target process's memory.
63 /// Used for situations in which JIT-ed code is being executed in the address
64 /// space of a separate process. If the code executes in the same address
65 /// space where it was JIT-ed, this just equals Address.
68 /// StubOffset - used for architectures with stub functions for far
69 /// relocations (like ARM).
72 /// The total amount of space allocated for this section. This includes the
73 /// section size and the maximum amount of space that the stubs can occupy.
74 size_t AllocationSize;
76 /// ObjAddress - address of the section in the in-memory object file. Used
77 /// for calculating relocations in some object formats (like MachO).
81 SectionEntry(StringRef name, uint8_t *address, size_t size,
82 size_t allocationSize, uintptr_t objAddress)
83 : Name(name), Address(address), Size(size),
84 LoadAddress(reinterpret_cast<uintptr_t>(address)), StubOffset(size),
85 AllocationSize(allocationSize), ObjAddress(objAddress) {}
87 StringRef getName() const { return Name; }
89 uint8_t *getAddress() const { return Address; }
91 /// \brief Return the address of this section with an offset.
92 uint8_t *getAddressWithOffset(unsigned OffsetBytes) const {
93 assert(OffsetBytes <= AllocationSize && "Offset out of bounds!");
94 return Address + OffsetBytes;
97 size_t getSize() const { return Size; }
99 uint64_t getLoadAddress() const { return LoadAddress; }
100 void setLoadAddress(uint64_t LA) { LoadAddress = LA; }
102 /// \brief Return the load address of this section with an offset.
103 uint64_t getLoadAddressWithOffset(unsigned OffsetBytes) const {
104 assert(OffsetBytes <= AllocationSize && "Offset out of bounds!");
105 return LoadAddress + OffsetBytes;
108 uintptr_t getStubOffset() const { return StubOffset; }
110 void advanceStubOffset(unsigned StubSize) {
111 StubOffset += StubSize;
112 assert(StubOffset <= AllocationSize && "Not enough space allocated!");
115 uintptr_t getObjAddress() const { return ObjAddress; }
118 /// RelocationEntry - used to represent relocations internally in the dynamic
120 class RelocationEntry {
122 /// SectionID - the section this relocation points to.
125 /// Offset - offset into the section.
128 /// RelType - relocation type.
131 /// Addend - the relocation addend encoded in the instruction itself. Also
132 /// used to make a relocation section relative instead of symbol relative.
140 /// SymOffset - Section offset of the relocation entry's symbol (used for GOT
144 SectionPair Sections;
147 /// True if this is a PCRel relocation (MachO specific).
150 /// The size of this relocation (MachO specific).
153 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend)
154 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
155 SymOffset(0), IsPCRel(false), Size(0) {}
157 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
159 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
160 SymOffset(symoffset), IsPCRel(false), Size(0) {}
162 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
163 bool IsPCRel, unsigned Size)
164 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
165 SymOffset(0), IsPCRel(IsPCRel), Size(Size) {}
167 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
168 unsigned SectionA, uint64_t SectionAOffset, unsigned SectionB,
169 uint64_t SectionBOffset, bool IsPCRel, unsigned Size)
170 : SectionID(id), Offset(offset), RelType(type),
171 Addend(SectionAOffset - SectionBOffset + addend), IsPCRel(IsPCRel),
173 Sections.SectionA = SectionA;
174 Sections.SectionB = SectionB;
178 class RelocationValueRef {
183 const char *SymbolName;
184 RelocationValueRef() : SectionID(0), Offset(0), Addend(0),
185 SymbolName(nullptr) {}
187 inline bool operator==(const RelocationValueRef &Other) const {
188 return SectionID == Other.SectionID && Offset == Other.Offset &&
189 Addend == Other.Addend && SymbolName == Other.SymbolName;
191 inline bool operator<(const RelocationValueRef &Other) const {
192 if (SectionID != Other.SectionID)
193 return SectionID < Other.SectionID;
194 if (Offset != Other.Offset)
195 return Offset < Other.Offset;
196 if (Addend != Other.Addend)
197 return Addend < Other.Addend;
198 return SymbolName < Other.SymbolName;
202 /// @brief Symbol info for RuntimeDyld.
203 class SymbolTableEntry : public JITSymbolBase {
206 : JITSymbolBase(JITSymbolFlags::None), Offset(0), SectionID(0) {}
208 SymbolTableEntry(unsigned SectionID, uint64_t Offset, JITSymbolFlags Flags)
209 : JITSymbolBase(Flags), Offset(Offset), SectionID(SectionID) {}
211 unsigned getSectionID() const { return SectionID; }
212 uint64_t getOffset() const { return Offset; }
219 typedef StringMap<SymbolTableEntry> RTDyldSymbolTable;
221 class RuntimeDyldImpl {
222 friend class RuntimeDyld::LoadedObjectInfo;
223 friend class RuntimeDyldCheckerImpl;
225 static const unsigned AbsoluteSymbolSection = ~0U;
227 // The MemoryManager to load objects into.
228 RuntimeDyld::MemoryManager &MemMgr;
230 // The symbol resolver to use for external symbols.
231 RuntimeDyld::SymbolResolver &Resolver;
233 // Attached RuntimeDyldChecker instance. Null if no instance attached.
234 RuntimeDyldCheckerImpl *Checker;
236 // A list of all sections emitted by the dynamic linker. These sections are
237 // referenced in the code by means of their index in this list - SectionID.
238 typedef SmallVector<SectionEntry, 64> SectionList;
239 SectionList Sections;
241 typedef unsigned SID; // Type for SectionIDs
242 #define RTDYLD_INVALID_SECTION_ID ((RuntimeDyldImpl::SID)(-1))
244 // Keep a map of sections from object file to the SectionID which
246 typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
248 // A global symbol table for symbols from all loaded modules.
249 RTDyldSymbolTable GlobalSymbolTable;
251 // Keep a map of common symbols to their info pairs
252 typedef std::vector<SymbolRef> CommonSymbolList;
254 // For each symbol, keep a list of relocations based on it. Anytime
255 // its address is reassigned (the JIT re-compiled the function, e.g.),
256 // the relocations get re-resolved.
257 // The symbol (or section) the relocation is sourced from is the Key
258 // in the relocation list where it's stored.
259 typedef SmallVector<RelocationEntry, 64> RelocationList;
260 // Relocations to sections already loaded. Indexed by SectionID which is the
261 // source of the address. The target where the address will be written is
262 // SectionID/Offset in the relocation itself.
263 DenseMap<unsigned, RelocationList> Relocations;
265 // Relocations to external symbols that are not yet resolved. Symbols are
266 // external when they aren't found in the global symbol table of all loaded
267 // modules. This map is indexed by symbol name.
268 StringMap<RelocationList> ExternalSymbolRelocations;
271 typedef std::map<RelocationValueRef, uintptr_t> StubMap;
273 Triple::ArchType Arch;
274 bool IsTargetLittleEndian;
278 // True if all sections should be passed to the memory manager, false if only
279 // sections containing relocations should be. Defaults to 'false'.
280 bool ProcessAllSections;
282 // This mutex prevents simultaneously loading objects from two different
283 // threads. This keeps us from having to protect individual data structures
284 // and guarantees that section allocation requests to the memory manager
285 // won't be interleaved between modules. It is also used in mapSectionAddress
286 // and resolveRelocations to protect write access to internal data structures.
288 // loadObject may be called on the same thread during the handling of of
289 // processRelocations, and that's OK. The handling of the relocation lists
290 // is written in such a way as to work correctly if new elements are added to
291 // the end of the list while the list is being processed.
294 virtual unsigned getMaxStubSize() = 0;
295 virtual unsigned getStubAlignment() = 0;
298 std::string ErrorStr;
300 // Set the error state and record an error string.
301 bool Error(const Twine &Msg) {
302 ErrorStr = Msg.str();
307 uint64_t getSectionLoadAddress(unsigned SectionID) const {
308 return Sections[SectionID].getLoadAddress();
311 uint8_t *getSectionAddress(unsigned SectionID) const {
312 return Sections[SectionID].getAddress();
315 void writeInt16BE(uint8_t *Addr, uint16_t Value) {
316 if (IsTargetLittleEndian)
317 sys::swapByteOrder(Value);
318 *Addr = (Value >> 8) & 0xFF;
319 *(Addr + 1) = Value & 0xFF;
322 void writeInt32BE(uint8_t *Addr, uint32_t Value) {
323 if (IsTargetLittleEndian)
324 sys::swapByteOrder(Value);
325 *Addr = (Value >> 24) & 0xFF;
326 *(Addr + 1) = (Value >> 16) & 0xFF;
327 *(Addr + 2) = (Value >> 8) & 0xFF;
328 *(Addr + 3) = Value & 0xFF;
331 void writeInt64BE(uint8_t *Addr, uint64_t Value) {
332 if (IsTargetLittleEndian)
333 sys::swapByteOrder(Value);
334 *Addr = (Value >> 56) & 0xFF;
335 *(Addr + 1) = (Value >> 48) & 0xFF;
336 *(Addr + 2) = (Value >> 40) & 0xFF;
337 *(Addr + 3) = (Value >> 32) & 0xFF;
338 *(Addr + 4) = (Value >> 24) & 0xFF;
339 *(Addr + 5) = (Value >> 16) & 0xFF;
340 *(Addr + 6) = (Value >> 8) & 0xFF;
341 *(Addr + 7) = Value & 0xFF;
344 virtual void setMipsABI(const ObjectFile &Obj) {
345 IsMipsO32ABI = false;
346 IsMipsN64ABI = false;
349 /// Endian-aware read Read the least significant Size bytes from Src.
350 uint64_t readBytesUnaligned(uint8_t *Src, unsigned Size) const;
352 /// Endian-aware write. Write the least significant Size bytes from Value to
354 void writeBytesUnaligned(uint64_t Value, uint8_t *Dst, unsigned Size) const;
356 /// \brief Given the common symbols discovered in the object file, emit a
357 /// new section for them and update the symbol mappings in the object and
359 void emitCommonSymbols(const ObjectFile &Obj, CommonSymbolList &CommonSymbols);
361 /// \brief Emits section data from the object file to the MemoryManager.
362 /// \param IsCode if it's true then allocateCodeSection() will be
363 /// used for emits, else allocateDataSection() will be used.
364 /// \return SectionID.
365 unsigned emitSection(const ObjectFile &Obj, const SectionRef &Section,
368 /// \brief Find Section in LocalSections. If the secton is not found - emit
369 /// it and store in LocalSections.
370 /// \param IsCode if it's true then allocateCodeSection() will be
371 /// used for emmits, else allocateDataSection() will be used.
372 /// \return SectionID.
373 unsigned findOrEmitSection(const ObjectFile &Obj, const SectionRef &Section,
374 bool IsCode, ObjSectionToIDMap &LocalSections);
376 // \brief Add a relocation entry that uses the given section.
377 void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID);
379 // \brief Add a relocation entry that uses the given symbol. This symbol may
380 // be found in the global symbol table, or it may be external.
381 void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName);
383 /// \brief Emits long jump instruction to Addr.
384 /// \return Pointer to the memory area for emitting target address.
385 uint8_t *createStubFunction(uint8_t *Addr, unsigned AbiVariant = 0);
387 /// \brief Resolves relocations from Relocs list with address from Value.
388 void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
390 /// \brief A object file specific relocation resolver
391 /// \param RE The relocation to be resolved
392 /// \param Value Target symbol address to apply the relocation action
393 virtual void resolveRelocation(const RelocationEntry &RE, uint64_t Value) = 0;
395 /// \brief Parses one or more object file relocations (some object files use
396 /// relocation pairs) and stores it to Relocations or SymbolRelocations
397 /// (this depends on the object file type).
398 /// \return Iterator to the next relocation that needs to be parsed.
399 virtual relocation_iterator
400 processRelocationRef(unsigned SectionID, relocation_iterator RelI,
401 const ObjectFile &Obj, ObjSectionToIDMap &ObjSectionToID,
404 /// \brief Resolve relocations to external symbols.
405 void resolveExternalSymbols();
407 // \brief Compute an upper bound of the memory that is required to load all
409 void computeTotalAllocSize(const ObjectFile &Obj, uint64_t &CodeSize,
410 uint64_t &DataSizeRO, uint64_t &DataSizeRW);
412 // \brief Compute the stub buffer size required for a section
413 unsigned computeSectionStubBufSize(const ObjectFile &Obj,
414 const SectionRef &Section);
416 // \brief Implementation of the generic part of the loadObject algorithm.
417 ObjSectionToIDMap loadObjectImpl(const object::ObjectFile &Obj);
419 // \brief Return true if the relocation R may require allocating a stub.
420 virtual bool relocationNeedsStub(const RelocationRef &R) const {
421 return true; // Conservative answer
425 RuntimeDyldImpl(RuntimeDyld::MemoryManager &MemMgr,
426 RuntimeDyld::SymbolResolver &Resolver)
427 : MemMgr(MemMgr), Resolver(Resolver), Checker(nullptr),
428 ProcessAllSections(false), HasError(false) {
431 virtual ~RuntimeDyldImpl();
433 void setProcessAllSections(bool ProcessAllSections) {
434 this->ProcessAllSections = ProcessAllSections;
437 void setRuntimeDyldChecker(RuntimeDyldCheckerImpl *Checker) {
438 this->Checker = Checker;
441 virtual std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
442 loadObject(const object::ObjectFile &Obj) = 0;
444 uint8_t* getSymbolLocalAddress(StringRef Name) const {
445 // FIXME: Just look up as a function for now. Overly simple of course.
447 RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
448 if (pos == GlobalSymbolTable.end())
450 const auto &SymInfo = pos->second;
451 // Absolute symbols do not have a local address.
452 if (SymInfo.getSectionID() == AbsoluteSymbolSection)
454 return getSectionAddress(SymInfo.getSectionID()) + SymInfo.getOffset();
457 RuntimeDyld::SymbolInfo getSymbol(StringRef Name) const {
458 // FIXME: Just look up as a function for now. Overly simple of course.
460 RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
461 if (pos == GlobalSymbolTable.end())
463 const auto &SymEntry = pos->second;
464 uint64_t SectionAddr = 0;
465 if (SymEntry.getSectionID() != AbsoluteSymbolSection)
466 SectionAddr = getSectionLoadAddress(SymEntry.getSectionID());
467 uint64_t TargetAddr = SectionAddr + SymEntry.getOffset();
468 return RuntimeDyld::SymbolInfo(TargetAddr, SymEntry.getFlags());
471 void resolveRelocations();
473 void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
475 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
477 // Is the linker in an error state?
478 bool hasError() { return HasError; }
480 // Mark the error condition as handled and continue.
481 void clearError() { HasError = false; }
483 // Get the error message.
484 StringRef getErrorString() { return ErrorStr; }
486 virtual bool isCompatibleFile(const ObjectFile &Obj) const = 0;
488 virtual void registerEHFrames();
490 virtual void deregisterEHFrames();
492 virtual void finalizeLoad(const ObjectFile &ObjImg,
493 ObjSectionToIDMap &SectionMap) {}
496 } // end namespace llvm