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
54 /// Name - section name.
57 /// Address - address in the linker's memory where the section resides.
60 /// Size - section size. Doesn't include the stubs.
63 /// LoadAddress - the address of the section in the target process's memory.
64 /// Used for situations in which JIT-ed code is being executed in the address
65 /// space of a separate process. If the code executes in the same address
66 /// space where it was JIT-ed, this just equals Address.
69 /// StubOffset - used for architectures with stub functions for far
70 /// relocations (like ARM).
73 /// ObjAddress - address of the section in the in-memory object file. Used
74 /// for calculating relocations in some object formats (like MachO).
77 SectionEntry(StringRef name, uint8_t *address, size_t size,
79 : Name(name), Address(address), Size(size),
80 LoadAddress(reinterpret_cast<uintptr_t>(address)), StubOffset(size),
81 ObjAddress(objAddress) {}
84 /// RelocationEntry - used to represent relocations internally in the dynamic
86 class RelocationEntry {
88 /// SectionID - the section this relocation points to.
91 /// Offset - offset into the section.
94 /// RelType - relocation type.
97 /// Addend - the relocation addend encoded in the instruction itself. Also
98 /// used to make a relocation section relative instead of symbol relative.
106 /// SymOffset - Section offset of the relocation entry's symbol (used for GOT
110 SectionPair Sections;
113 /// True if this is a PCRel relocation (MachO specific).
116 /// The size of this relocation (MachO specific).
119 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend)
120 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
121 SymOffset(0), IsPCRel(false), Size(0) {}
123 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
125 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
126 SymOffset(symoffset), IsPCRel(false), Size(0) {}
128 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
129 bool IsPCRel, unsigned Size)
130 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
131 SymOffset(0), IsPCRel(IsPCRel), Size(Size) {}
133 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
134 unsigned SectionA, uint64_t SectionAOffset, unsigned SectionB,
135 uint64_t SectionBOffset, bool IsPCRel, unsigned Size)
136 : SectionID(id), Offset(offset), RelType(type),
137 Addend(SectionAOffset - SectionBOffset + addend), IsPCRel(IsPCRel),
139 Sections.SectionA = SectionA;
140 Sections.SectionB = SectionB;
144 class RelocationValueRef {
149 const char *SymbolName;
150 RelocationValueRef() : SectionID(0), Offset(0), Addend(0),
151 SymbolName(nullptr) {}
153 inline bool operator==(const RelocationValueRef &Other) const {
154 return SectionID == Other.SectionID && Offset == Other.Offset &&
155 Addend == Other.Addend && SymbolName == Other.SymbolName;
157 inline bool operator<(const RelocationValueRef &Other) const {
158 if (SectionID != Other.SectionID)
159 return SectionID < Other.SectionID;
160 if (Offset != Other.Offset)
161 return Offset < Other.Offset;
162 if (Addend != Other.Addend)
163 return Addend < Other.Addend;
164 return SymbolName < Other.SymbolName;
168 /// @brief Symbol info for RuntimeDyld.
169 class SymbolTableEntry : public JITSymbolBase {
172 : JITSymbolBase(JITSymbolFlags::None), Offset(0), SectionID(0) {}
174 SymbolTableEntry(unsigned SectionID, uint64_t Offset, JITSymbolFlags Flags)
175 : JITSymbolBase(Flags), Offset(Offset), SectionID(SectionID) {}
177 unsigned getSectionID() const { return SectionID; }
178 uint64_t getOffset() const { return Offset; }
185 typedef StringMap<SymbolTableEntry> RTDyldSymbolTable;
187 class RuntimeDyldImpl {
188 friend class RuntimeDyld::LoadedObjectInfo;
189 friend class RuntimeDyldCheckerImpl;
191 static const unsigned AbsoluteSymbolSection = ~0U;
193 // The MemoryManager to load objects into.
194 RuntimeDyld::MemoryManager &MemMgr;
196 // The symbol resolver to use for external symbols.
197 RuntimeDyld::SymbolResolver &Resolver;
199 // Attached RuntimeDyldChecker instance. Null if no instance attached.
200 RuntimeDyldCheckerImpl *Checker;
202 // A list of all sections emitted by the dynamic linker. These sections are
203 // referenced in the code by means of their index in this list - SectionID.
204 typedef SmallVector<SectionEntry, 64> SectionList;
205 SectionList Sections;
207 typedef unsigned SID; // Type for SectionIDs
208 #define RTDYLD_INVALID_SECTION_ID ((RuntimeDyldImpl::SID)(-1))
210 // Keep a map of sections from object file to the SectionID which
212 typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
214 // A global symbol table for symbols from all loaded modules.
215 RTDyldSymbolTable GlobalSymbolTable;
217 // Keep a map of common symbols to their info pairs
218 typedef std::vector<SymbolRef> CommonSymbolList;
220 // For each symbol, keep a list of relocations based on it. Anytime
221 // its address is reassigned (the JIT re-compiled the function, e.g.),
222 // the relocations get re-resolved.
223 // The symbol (or section) the relocation is sourced from is the Key
224 // in the relocation list where it's stored.
225 typedef SmallVector<RelocationEntry, 64> RelocationList;
226 // Relocations to sections already loaded. Indexed by SectionID which is the
227 // source of the address. The target where the address will be written is
228 // SectionID/Offset in the relocation itself.
229 DenseMap<unsigned, RelocationList> Relocations;
231 // Relocations to external symbols that are not yet resolved. Symbols are
232 // external when they aren't found in the global symbol table of all loaded
233 // modules. This map is indexed by symbol name.
234 StringMap<RelocationList> ExternalSymbolRelocations;
237 typedef std::map<RelocationValueRef, uintptr_t> StubMap;
239 Triple::ArchType Arch;
240 bool IsTargetLittleEndian;
244 // True if all sections should be passed to the memory manager, false if only
245 // sections containing relocations should be. Defaults to 'false'.
246 bool ProcessAllSections;
248 // This mutex prevents simultaneously loading objects from two different
249 // threads. This keeps us from having to protect individual data structures
250 // and guarantees that section allocation requests to the memory manager
251 // won't be interleaved between modules. It is also used in mapSectionAddress
252 // and resolveRelocations to protect write access to internal data structures.
254 // loadObject may be called on the same thread during the handling of of
255 // processRelocations, and that's OK. The handling of the relocation lists
256 // is written in such a way as to work correctly if new elements are added to
257 // the end of the list while the list is being processed.
260 virtual unsigned getMaxStubSize() = 0;
261 virtual unsigned getStubAlignment() = 0;
264 std::string ErrorStr;
266 // Set the error state and record an error string.
267 bool Error(const Twine &Msg) {
268 ErrorStr = Msg.str();
273 uint64_t getSectionLoadAddress(unsigned SectionID) const {
274 return Sections[SectionID].LoadAddress;
277 uint8_t *getSectionAddress(unsigned SectionID) const {
278 return (uint8_t *)Sections[SectionID].Address;
281 void writeInt16BE(uint8_t *Addr, uint16_t Value) {
282 if (IsTargetLittleEndian)
283 sys::swapByteOrder(Value);
284 *Addr = (Value >> 8) & 0xFF;
285 *(Addr + 1) = Value & 0xFF;
288 void writeInt32BE(uint8_t *Addr, uint32_t Value) {
289 if (IsTargetLittleEndian)
290 sys::swapByteOrder(Value);
291 *Addr = (Value >> 24) & 0xFF;
292 *(Addr + 1) = (Value >> 16) & 0xFF;
293 *(Addr + 2) = (Value >> 8) & 0xFF;
294 *(Addr + 3) = Value & 0xFF;
297 void writeInt64BE(uint8_t *Addr, uint64_t Value) {
298 if (IsTargetLittleEndian)
299 sys::swapByteOrder(Value);
300 *Addr = (Value >> 56) & 0xFF;
301 *(Addr + 1) = (Value >> 48) & 0xFF;
302 *(Addr + 2) = (Value >> 40) & 0xFF;
303 *(Addr + 3) = (Value >> 32) & 0xFF;
304 *(Addr + 4) = (Value >> 24) & 0xFF;
305 *(Addr + 5) = (Value >> 16) & 0xFF;
306 *(Addr + 6) = (Value >> 8) & 0xFF;
307 *(Addr + 7) = Value & 0xFF;
310 virtual void setMipsABI(const ObjectFile &Obj) {
311 IsMipsO32ABI = false;
312 IsMipsN64ABI = false;
315 /// Endian-aware read Read the least significant Size bytes from Src.
316 uint64_t readBytesUnaligned(uint8_t *Src, unsigned Size) const;
318 /// Endian-aware write. Write the least significant Size bytes from Value to
320 void writeBytesUnaligned(uint64_t Value, uint8_t *Dst, unsigned Size) const;
322 /// \brief Given the common symbols discovered in the object file, emit a
323 /// new section for them and update the symbol mappings in the object and
325 void emitCommonSymbols(const ObjectFile &Obj, CommonSymbolList &CommonSymbols);
327 /// \brief Emits section data from the object file to the MemoryManager.
328 /// \param IsCode if it's true then allocateCodeSection() will be
329 /// used for emits, else allocateDataSection() will be used.
330 /// \return SectionID.
331 unsigned emitSection(const ObjectFile &Obj, const SectionRef &Section,
334 /// \brief Find Section in LocalSections. If the secton is not found - emit
335 /// it and store in LocalSections.
336 /// \param IsCode if it's true then allocateCodeSection() will be
337 /// used for emmits, else allocateDataSection() will be used.
338 /// \return SectionID.
339 unsigned findOrEmitSection(const ObjectFile &Obj, const SectionRef &Section,
340 bool IsCode, ObjSectionToIDMap &LocalSections);
342 // \brief Add a relocation entry that uses the given section.
343 void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID);
345 // \brief Add a relocation entry that uses the given symbol. This symbol may
346 // be found in the global symbol table, or it may be external.
347 void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName);
349 /// \brief Emits long jump instruction to Addr.
350 /// \return Pointer to the memory area for emitting target address.
351 uint8_t *createStubFunction(uint8_t *Addr, unsigned AbiVariant = 0);
353 /// \brief Resolves relocations from Relocs list with address from Value.
354 void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
356 /// \brief A object file specific relocation resolver
357 /// \param RE The relocation to be resolved
358 /// \param Value Target symbol address to apply the relocation action
359 virtual void resolveRelocation(const RelocationEntry &RE, uint64_t Value) = 0;
361 /// \brief Parses one or more object file relocations (some object files use
362 /// relocation pairs) and stores it to Relocations or SymbolRelocations
363 /// (this depends on the object file type).
364 /// \return Iterator to the next relocation that needs to be parsed.
365 virtual relocation_iterator
366 processRelocationRef(unsigned SectionID, relocation_iterator RelI,
367 const ObjectFile &Obj, ObjSectionToIDMap &ObjSectionToID,
370 /// \brief Resolve relocations to external symbols.
371 void resolveExternalSymbols();
373 // \brief Compute an upper bound of the memory that is required to load all
375 void computeTotalAllocSize(const ObjectFile &Obj, uint64_t &CodeSize,
376 uint64_t &DataSizeRO, uint64_t &DataSizeRW);
378 // \brief Compute the stub buffer size required for a section
379 unsigned computeSectionStubBufSize(const ObjectFile &Obj,
380 const SectionRef &Section);
382 // \brief Implementation of the generic part of the loadObject algorithm.
383 ObjSectionToIDMap loadObjectImpl(const object::ObjectFile &Obj);
386 RuntimeDyldImpl(RuntimeDyld::MemoryManager &MemMgr,
387 RuntimeDyld::SymbolResolver &Resolver)
388 : MemMgr(MemMgr), Resolver(Resolver), Checker(nullptr),
389 ProcessAllSections(false), HasError(false) {
392 virtual ~RuntimeDyldImpl();
394 void setProcessAllSections(bool ProcessAllSections) {
395 this->ProcessAllSections = ProcessAllSections;
398 void setRuntimeDyldChecker(RuntimeDyldCheckerImpl *Checker) {
399 this->Checker = Checker;
402 virtual std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
403 loadObject(const object::ObjectFile &Obj) = 0;
405 uint8_t* getSymbolLocalAddress(StringRef Name) const {
406 // FIXME: Just look up as a function for now. Overly simple of course.
408 RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
409 if (pos == GlobalSymbolTable.end())
411 const auto &SymInfo = pos->second;
412 // Absolute symbols do not have a local address.
413 if (SymInfo.getSectionID() == AbsoluteSymbolSection)
415 return getSectionAddress(SymInfo.getSectionID()) + SymInfo.getOffset();
418 RuntimeDyld::SymbolInfo getSymbol(StringRef Name) const {
419 // FIXME: Just look up as a function for now. Overly simple of course.
421 RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
422 if (pos == GlobalSymbolTable.end())
424 const auto &SymEntry = pos->second;
425 uint64_t SectionAddr = 0;
426 if (SymEntry.getSectionID() != AbsoluteSymbolSection)
427 SectionAddr = getSectionLoadAddress(SymEntry.getSectionID());
428 uint64_t TargetAddr = SectionAddr + SymEntry.getOffset();
429 return RuntimeDyld::SymbolInfo(TargetAddr, SymEntry.getFlags());
432 void resolveRelocations();
434 void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
436 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
438 // Is the linker in an error state?
439 bool hasError() { return HasError; }
441 // Mark the error condition as handled and continue.
442 void clearError() { HasError = false; }
444 // Get the error message.
445 StringRef getErrorString() { return ErrorStr; }
447 virtual bool isCompatibleFile(const ObjectFile &Obj) const = 0;
449 virtual void registerEHFrames();
451 virtual void deregisterEHFrames();
453 virtual void finalizeLoad(const ObjectFile &ObjImg,
454 ObjSectionToIDMap &SectionMap) {}
457 } // end namespace llvm