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) {
86 // AllocationSize is used only in asserts, prevent an "unused private field"
91 StringRef getName() const { return Name; }
93 uint8_t *getAddress() const { return Address; }
95 /// \brief Return the address of this section with an offset.
96 uint8_t *getAddressWithOffset(unsigned OffsetBytes) const {
97 assert(OffsetBytes <= AllocationSize && "Offset out of bounds!");
98 return Address + OffsetBytes;
101 size_t getSize() const { return Size; }
103 uint64_t getLoadAddress() const { return LoadAddress; }
104 void setLoadAddress(uint64_t LA) { LoadAddress = LA; }
106 /// \brief Return the load address of this section with an offset.
107 uint64_t getLoadAddressWithOffset(unsigned OffsetBytes) const {
108 assert(OffsetBytes <= AllocationSize && "Offset out of bounds!");
109 return LoadAddress + OffsetBytes;
112 uintptr_t getStubOffset() const { return StubOffset; }
114 void advanceStubOffset(unsigned StubSize) {
115 StubOffset += StubSize;
116 assert(StubOffset <= AllocationSize && "Not enough space allocated!");
119 uintptr_t getObjAddress() const { return ObjAddress; }
122 /// RelocationEntry - used to represent relocations internally in the dynamic
124 class RelocationEntry {
126 /// SectionID - the section this relocation points to.
129 /// Offset - offset into the section.
132 /// RelType - relocation type.
135 /// Addend - the relocation addend encoded in the instruction itself. Also
136 /// used to make a relocation section relative instead of symbol relative.
144 /// SymOffset - Section offset of the relocation entry's symbol (used for GOT
148 SectionPair Sections;
151 /// True if this is a PCRel relocation (MachO specific).
154 /// The size of this relocation (MachO specific).
157 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend)
158 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
159 SymOffset(0), IsPCRel(false), Size(0) {}
161 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
163 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
164 SymOffset(symoffset), IsPCRel(false), Size(0) {}
166 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
167 bool IsPCRel, unsigned Size)
168 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
169 SymOffset(0), IsPCRel(IsPCRel), Size(Size) {}
171 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
172 unsigned SectionA, uint64_t SectionAOffset, unsigned SectionB,
173 uint64_t SectionBOffset, bool IsPCRel, unsigned Size)
174 : SectionID(id), Offset(offset), RelType(type),
175 Addend(SectionAOffset - SectionBOffset + addend), IsPCRel(IsPCRel),
177 Sections.SectionA = SectionA;
178 Sections.SectionB = SectionB;
182 class RelocationValueRef {
187 const char *SymbolName;
188 RelocationValueRef() : SectionID(0), Offset(0), Addend(0),
189 SymbolName(nullptr) {}
191 inline bool operator==(const RelocationValueRef &Other) const {
192 return SectionID == Other.SectionID && Offset == Other.Offset &&
193 Addend == Other.Addend && SymbolName == Other.SymbolName;
195 inline bool operator<(const RelocationValueRef &Other) const {
196 if (SectionID != Other.SectionID)
197 return SectionID < Other.SectionID;
198 if (Offset != Other.Offset)
199 return Offset < Other.Offset;
200 if (Addend != Other.Addend)
201 return Addend < Other.Addend;
202 return SymbolName < Other.SymbolName;
206 /// @brief Symbol info for RuntimeDyld.
207 class SymbolTableEntry : public JITSymbolBase {
210 : JITSymbolBase(JITSymbolFlags::None), Offset(0), SectionID(0) {}
212 SymbolTableEntry(unsigned SectionID, uint64_t Offset, JITSymbolFlags Flags)
213 : JITSymbolBase(Flags), Offset(Offset), SectionID(SectionID) {}
215 unsigned getSectionID() const { return SectionID; }
216 uint64_t getOffset() const { return Offset; }
223 typedef StringMap<SymbolTableEntry> RTDyldSymbolTable;
225 class RuntimeDyldImpl {
226 friend class RuntimeDyld::LoadedObjectInfo;
227 friend class RuntimeDyldCheckerImpl;
229 static const unsigned AbsoluteSymbolSection = ~0U;
231 // The MemoryManager to load objects into.
232 RuntimeDyld::MemoryManager &MemMgr;
234 // The symbol resolver to use for external symbols.
235 RuntimeDyld::SymbolResolver &Resolver;
237 // Attached RuntimeDyldChecker instance. Null if no instance attached.
238 RuntimeDyldCheckerImpl *Checker;
240 // A list of all sections emitted by the dynamic linker. These sections are
241 // referenced in the code by means of their index in this list - SectionID.
242 typedef SmallVector<SectionEntry, 64> SectionList;
243 SectionList Sections;
245 typedef unsigned SID; // Type for SectionIDs
246 #define RTDYLD_INVALID_SECTION_ID ((RuntimeDyldImpl::SID)(-1))
248 // Keep a map of sections from object file to the SectionID which
250 typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
252 // A global symbol table for symbols from all loaded modules.
253 RTDyldSymbolTable GlobalSymbolTable;
255 // Keep a map of common symbols to their info pairs
256 typedef std::vector<SymbolRef> CommonSymbolList;
258 // For each symbol, keep a list of relocations based on it. Anytime
259 // its address is reassigned (the JIT re-compiled the function, e.g.),
260 // the relocations get re-resolved.
261 // The symbol (or section) the relocation is sourced from is the Key
262 // in the relocation list where it's stored.
263 typedef SmallVector<RelocationEntry, 64> RelocationList;
264 // Relocations to sections already loaded. Indexed by SectionID which is the
265 // source of the address. The target where the address will be written is
266 // SectionID/Offset in the relocation itself.
267 DenseMap<unsigned, RelocationList> Relocations;
269 // Relocations to external symbols that are not yet resolved. Symbols are
270 // external when they aren't found in the global symbol table of all loaded
271 // modules. This map is indexed by symbol name.
272 StringMap<RelocationList> ExternalSymbolRelocations;
275 typedef std::map<RelocationValueRef, uintptr_t> StubMap;
277 Triple::ArchType Arch;
278 bool IsTargetLittleEndian;
282 // True if all sections should be passed to the memory manager, false if only
283 // sections containing relocations should be. Defaults to 'false'.
284 bool ProcessAllSections;
286 // This mutex prevents simultaneously loading objects from two different
287 // threads. This keeps us from having to protect individual data structures
288 // and guarantees that section allocation requests to the memory manager
289 // won't be interleaved between modules. It is also used in mapSectionAddress
290 // and resolveRelocations to protect write access to internal data structures.
292 // loadObject may be called on the same thread during the handling of of
293 // processRelocations, and that's OK. The handling of the relocation lists
294 // is written in such a way as to work correctly if new elements are added to
295 // the end of the list while the list is being processed.
298 virtual unsigned getMaxStubSize() = 0;
299 virtual unsigned getStubAlignment() = 0;
302 std::string ErrorStr;
304 // Set the error state and record an error string.
305 bool Error(const Twine &Msg) {
306 ErrorStr = Msg.str();
311 uint64_t getSectionLoadAddress(unsigned SectionID) const {
312 return Sections[SectionID].getLoadAddress();
315 uint8_t *getSectionAddress(unsigned SectionID) const {
316 return Sections[SectionID].getAddress();
319 void writeInt16BE(uint8_t *Addr, uint16_t Value) {
320 if (IsTargetLittleEndian)
321 sys::swapByteOrder(Value);
322 *Addr = (Value >> 8) & 0xFF;
323 *(Addr + 1) = Value & 0xFF;
326 void writeInt32BE(uint8_t *Addr, uint32_t Value) {
327 if (IsTargetLittleEndian)
328 sys::swapByteOrder(Value);
329 *Addr = (Value >> 24) & 0xFF;
330 *(Addr + 1) = (Value >> 16) & 0xFF;
331 *(Addr + 2) = (Value >> 8) & 0xFF;
332 *(Addr + 3) = Value & 0xFF;
335 void writeInt64BE(uint8_t *Addr, uint64_t Value) {
336 if (IsTargetLittleEndian)
337 sys::swapByteOrder(Value);
338 *Addr = (Value >> 56) & 0xFF;
339 *(Addr + 1) = (Value >> 48) & 0xFF;
340 *(Addr + 2) = (Value >> 40) & 0xFF;
341 *(Addr + 3) = (Value >> 32) & 0xFF;
342 *(Addr + 4) = (Value >> 24) & 0xFF;
343 *(Addr + 5) = (Value >> 16) & 0xFF;
344 *(Addr + 6) = (Value >> 8) & 0xFF;
345 *(Addr + 7) = Value & 0xFF;
348 virtual void setMipsABI(const ObjectFile &Obj) {
349 IsMipsO32ABI = false;
350 IsMipsN64ABI = false;
353 /// Endian-aware read Read the least significant Size bytes from Src.
354 uint64_t readBytesUnaligned(uint8_t *Src, unsigned Size) const;
356 /// Endian-aware write. Write the least significant Size bytes from Value to
358 void writeBytesUnaligned(uint64_t Value, uint8_t *Dst, unsigned Size) const;
360 /// \brief Given the common symbols discovered in the object file, emit a
361 /// new section for them and update the symbol mappings in the object and
363 void emitCommonSymbols(const ObjectFile &Obj, CommonSymbolList &CommonSymbols);
365 /// \brief Emits section data from the object file to the MemoryManager.
366 /// \param IsCode if it's true then allocateCodeSection() will be
367 /// used for emits, else allocateDataSection() will be used.
368 /// \return SectionID.
369 unsigned emitSection(const ObjectFile &Obj, const SectionRef &Section,
372 /// \brief Find Section in LocalSections. If the secton is not found - emit
373 /// it and store in LocalSections.
374 /// \param IsCode if it's true then allocateCodeSection() will be
375 /// used for emmits, else allocateDataSection() will be used.
376 /// \return SectionID.
377 unsigned findOrEmitSection(const ObjectFile &Obj, const SectionRef &Section,
378 bool IsCode, ObjSectionToIDMap &LocalSections);
380 // \brief Add a relocation entry that uses the given section.
381 void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID);
383 // \brief Add a relocation entry that uses the given symbol. This symbol may
384 // be found in the global symbol table, or it may be external.
385 void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName);
387 /// \brief Emits long jump instruction to Addr.
388 /// \return Pointer to the memory area for emitting target address.
389 uint8_t *createStubFunction(uint8_t *Addr, unsigned AbiVariant = 0);
391 /// \brief Resolves relocations from Relocs list with address from Value.
392 void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
394 /// \brief A object file specific relocation resolver
395 /// \param RE The relocation to be resolved
396 /// \param Value Target symbol address to apply the relocation action
397 virtual void resolveRelocation(const RelocationEntry &RE, uint64_t Value) = 0;
399 /// \brief Parses one or more object file relocations (some object files use
400 /// relocation pairs) and stores it to Relocations or SymbolRelocations
401 /// (this depends on the object file type).
402 /// \return Iterator to the next relocation that needs to be parsed.
403 virtual relocation_iterator
404 processRelocationRef(unsigned SectionID, relocation_iterator RelI,
405 const ObjectFile &Obj, ObjSectionToIDMap &ObjSectionToID,
408 /// \brief Resolve relocations to external symbols.
409 void resolveExternalSymbols();
411 // \brief Compute an upper bound of the memory that is required to load all
413 void computeTotalAllocSize(const ObjectFile &Obj, uint64_t &CodeSize,
414 uint64_t &DataSizeRO, uint64_t &DataSizeRW);
416 // \brief Compute the stub buffer size required for a section
417 unsigned computeSectionStubBufSize(const ObjectFile &Obj,
418 const SectionRef &Section);
420 // \brief Implementation of the generic part of the loadObject algorithm.
421 ObjSectionToIDMap loadObjectImpl(const object::ObjectFile &Obj);
423 // \brief Return true if the relocation R may require allocating a stub.
424 virtual bool relocationNeedsStub(const RelocationRef &R) const {
425 return true; // Conservative answer
429 RuntimeDyldImpl(RuntimeDyld::MemoryManager &MemMgr,
430 RuntimeDyld::SymbolResolver &Resolver)
431 : MemMgr(MemMgr), Resolver(Resolver), Checker(nullptr),
432 ProcessAllSections(false), HasError(false) {
435 virtual ~RuntimeDyldImpl();
437 void setProcessAllSections(bool ProcessAllSections) {
438 this->ProcessAllSections = ProcessAllSections;
441 void setRuntimeDyldChecker(RuntimeDyldCheckerImpl *Checker) {
442 this->Checker = Checker;
445 virtual std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
446 loadObject(const object::ObjectFile &Obj) = 0;
448 uint8_t* getSymbolLocalAddress(StringRef Name) const {
449 // FIXME: Just look up as a function for now. Overly simple of course.
451 RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
452 if (pos == GlobalSymbolTable.end())
454 const auto &SymInfo = pos->second;
455 // Absolute symbols do not have a local address.
456 if (SymInfo.getSectionID() == AbsoluteSymbolSection)
458 return getSectionAddress(SymInfo.getSectionID()) + SymInfo.getOffset();
461 RuntimeDyld::SymbolInfo getSymbol(StringRef Name) const {
462 // FIXME: Just look up as a function for now. Overly simple of course.
464 RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
465 if (pos == GlobalSymbolTable.end())
467 const auto &SymEntry = pos->second;
468 uint64_t SectionAddr = 0;
469 if (SymEntry.getSectionID() != AbsoluteSymbolSection)
470 SectionAddr = getSectionLoadAddress(SymEntry.getSectionID());
471 uint64_t TargetAddr = SectionAddr + SymEntry.getOffset();
472 return RuntimeDyld::SymbolInfo(TargetAddr, SymEntry.getFlags());
475 void resolveRelocations();
477 void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
479 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
481 // Is the linker in an error state?
482 bool hasError() { return HasError; }
484 // Mark the error condition as handled and continue.
485 void clearError() { HasError = false; }
487 // Get the error message.
488 StringRef getErrorString() { return ErrorStr; }
490 virtual bool isCompatibleFile(const ObjectFile &Obj) const = 0;
492 virtual void registerEHFrames();
494 virtual void deregisterEHFrames();
496 virtual void finalizeLoad(const ObjectFile &ObjImg,
497 ObjSectionToIDMap &SectionMap) {}
500 } // end namespace llvm