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/RuntimeDyld.h"
22 #include "llvm/ExecutionEngine/RuntimeDyldChecker.h"
23 #include "llvm/Object/ObjectFile.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/Format.h"
27 #include "llvm/Support/Host.h"
28 #include "llvm/Support/Mutex.h"
29 #include "llvm/Support/SwapByteOrder.h"
30 #include "llvm/Support/raw_ostream.h"
32 #include <system_error>
35 using namespace llvm::object;
40 // Helper for extensive error checking in debug builds.
41 std::error_code Check(std::error_code Err) {
43 report_fatal_error(Err.message());
47 } // end anonymous namespace
51 /// SectionEntry - represents a section emitted into memory by the dynamic
55 /// Name - section name.
58 /// Address - address in the linker's memory where the section resides.
61 /// Size - section size. Doesn't include the stubs.
64 /// LoadAddress - the address of the section in the target process's memory.
65 /// Used for situations in which JIT-ed code is being executed in the address
66 /// space of a separate process. If the code executes in the same address
67 /// space where it was JIT-ed, this just equals Address.
70 /// StubOffset - used for architectures with stub functions for far
71 /// relocations (like ARM).
74 /// ObjAddress - address of the section in the in-memory object file. Used
75 /// for calculating relocations in some object formats (like MachO).
78 SectionEntry(StringRef name, uint8_t *address, size_t size,
80 : Name(name), Address(address), Size(size),
81 LoadAddress(reinterpret_cast<uintptr_t>(address)), StubOffset(size),
82 ObjAddress(objAddress) {}
85 /// RelocationEntry - used to represent relocations internally in the dynamic
87 class RelocationEntry {
89 /// SectionID - the section this relocation points to.
92 /// Offset - offset into the section.
95 /// RelType - relocation type.
98 /// Addend - the relocation addend encoded in the instruction itself. Also
99 /// used to make a relocation section relative instead of symbol relative.
107 /// SymOffset - Section offset of the relocation entry's symbol (used for GOT
111 SectionPair Sections;
114 /// True if this is a PCRel relocation (MachO specific).
117 /// The size of this relocation (MachO specific).
120 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend)
121 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
122 SymOffset(0), IsPCRel(false), Size(0) {}
124 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
126 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
127 SymOffset(symoffset), IsPCRel(false), Size(0) {}
129 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
130 bool IsPCRel, unsigned Size)
131 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
132 SymOffset(0), IsPCRel(IsPCRel), Size(Size) {}
134 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
135 unsigned SectionA, uint64_t SectionAOffset, unsigned SectionB,
136 uint64_t SectionBOffset, bool IsPCRel, unsigned Size)
137 : SectionID(id), Offset(offset), RelType(type),
138 Addend(SectionAOffset - SectionBOffset + addend), IsPCRel(IsPCRel),
140 Sections.SectionA = SectionA;
141 Sections.SectionB = SectionB;
145 class RelocationValueRef {
150 const char *SymbolName;
151 RelocationValueRef() : SectionID(0), Offset(0), Addend(0),
152 SymbolName(nullptr) {}
154 inline bool operator==(const RelocationValueRef &Other) const {
155 return SectionID == Other.SectionID && Offset == Other.Offset &&
156 Addend == Other.Addend && SymbolName == Other.SymbolName;
158 inline bool operator<(const RelocationValueRef &Other) const {
159 if (SectionID != Other.SectionID)
160 return SectionID < Other.SectionID;
161 if (Offset != Other.Offset)
162 return Offset < Other.Offset;
163 if (Addend != Other.Addend)
164 return Addend < Other.Addend;
165 return SymbolName < Other.SymbolName;
169 /// @brief Symbol info for RuntimeDyld.
172 typedef enum { Hidden = 0, Default = 1 } Visibility;
174 SymbolInfo() : Offset(0), SectionID(0), Vis(Hidden) {}
176 SymbolInfo(unsigned SectionID, uint64_t Offset, Visibility Vis)
177 : Offset(Offset), SectionID(SectionID), Vis(Vis) {}
179 unsigned getSectionID() const { return SectionID; }
180 uint64_t getOffset() const { return Offset; }
181 Visibility getVisibility() const { return Vis; }
185 unsigned SectionID : 31;
189 typedef StringMap<SymbolInfo> RTDyldSymbolTable;
191 class RuntimeDyldImpl {
192 friend class RuntimeDyld::LoadedObjectInfo;
193 friend class RuntimeDyldCheckerImpl;
195 // The MemoryManager to load objects into.
196 RTDyldMemoryManager *MemMgr;
198 // Attached RuntimeDyldChecker instance. Null if no instance attached.
199 RuntimeDyldCheckerImpl *Checker;
201 // A list of all sections emitted by the dynamic linker. These sections are
202 // referenced in the code by means of their index in this list - SectionID.
203 typedef SmallVector<SectionEntry, 64> SectionList;
204 SectionList Sections;
206 typedef unsigned SID; // Type for SectionIDs
207 #define RTDYLD_INVALID_SECTION_ID ((SID)(-1))
209 // Keep a map of sections from object file to the SectionID which
211 typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
213 // A global symbol table for symbols from all loaded modules.
214 RTDyldSymbolTable GlobalSymbolTable;
216 // Keep a map of common symbols to their info pairs
217 typedef std::vector<SymbolRef> CommonSymbolList;
219 // For each symbol, keep a list of relocations based on it. Anytime
220 // its address is reassigned (the JIT re-compiled the function, e.g.),
221 // the relocations get re-resolved.
222 // The symbol (or section) the relocation is sourced from is the Key
223 // in the relocation list where it's stored.
224 typedef SmallVector<RelocationEntry, 64> RelocationList;
225 // Relocations to sections already loaded. Indexed by SectionID which is the
226 // source of the address. The target where the address will be written is
227 // SectionID/Offset in the relocation itself.
228 DenseMap<unsigned, RelocationList> Relocations;
230 // Relocations to external symbols that are not yet resolved. Symbols are
231 // external when they aren't found in the global symbol table of all loaded
232 // modules. This map is indexed by symbol name.
233 StringMap<RelocationList> ExternalSymbolRelocations;
236 typedef std::map<RelocationValueRef, uintptr_t> StubMap;
238 Triple::ArchType Arch;
239 bool IsTargetLittleEndian;
241 // True if all sections should be passed to the memory manager, false if only
242 // sections containing relocations should be. Defaults to 'false'.
243 bool ProcessAllSections;
245 // This mutex prevents simultaneously loading objects from two different
246 // threads. This keeps us from having to protect individual data structures
247 // and guarantees that section allocation requests to the memory manager
248 // won't be interleaved between modules. It is also used in mapSectionAddress
249 // and resolveRelocations to protect write access to internal data structures.
251 // loadObject may be called on the same thread during the handling of of
252 // processRelocations, and that's OK. The handling of the relocation lists
253 // is written in such a way as to work correctly if new elements are added to
254 // the end of the list while the list is being processed.
257 virtual unsigned getMaxStubSize() = 0;
258 virtual unsigned getStubAlignment() = 0;
261 std::string ErrorStr;
263 // Set the error state and record an error string.
264 bool Error(const Twine &Msg) {
265 ErrorStr = Msg.str();
270 uint64_t getSectionLoadAddress(unsigned SectionID) const {
271 return Sections[SectionID].LoadAddress;
274 uint8_t *getSectionAddress(unsigned SectionID) const {
275 return (uint8_t *)Sections[SectionID].Address;
278 void writeInt16BE(uint8_t *Addr, uint16_t Value) {
279 if (IsTargetLittleEndian)
280 sys::swapByteOrder(Value);
281 *Addr = (Value >> 8) & 0xFF;
282 *(Addr + 1) = Value & 0xFF;
285 void writeInt32BE(uint8_t *Addr, uint32_t Value) {
286 if (IsTargetLittleEndian)
287 sys::swapByteOrder(Value);
288 *Addr = (Value >> 24) & 0xFF;
289 *(Addr + 1) = (Value >> 16) & 0xFF;
290 *(Addr + 2) = (Value >> 8) & 0xFF;
291 *(Addr + 3) = Value & 0xFF;
294 void writeInt64BE(uint8_t *Addr, uint64_t Value) {
295 if (IsTargetLittleEndian)
296 sys::swapByteOrder(Value);
297 *Addr = (Value >> 56) & 0xFF;
298 *(Addr + 1) = (Value >> 48) & 0xFF;
299 *(Addr + 2) = (Value >> 40) & 0xFF;
300 *(Addr + 3) = (Value >> 32) & 0xFF;
301 *(Addr + 4) = (Value >> 24) & 0xFF;
302 *(Addr + 5) = (Value >> 16) & 0xFF;
303 *(Addr + 6) = (Value >> 8) & 0xFF;
304 *(Addr + 7) = Value & 0xFF;
307 /// Endian-aware read Read the least significant Size bytes from Src.
308 uint64_t readBytesUnaligned(uint8_t *Src, unsigned Size) const;
310 /// Endian-aware write. Write the least significant Size bytes from Value to
312 void writeBytesUnaligned(uint64_t Value, uint8_t *Dst, unsigned Size) const;
314 /// \brief Given the common symbols discovered in the object file, emit a
315 /// new section for them and update the symbol mappings in the object and
317 void emitCommonSymbols(const ObjectFile &Obj, CommonSymbolList &CommonSymbols);
319 /// \brief Emits section data from the object file to the MemoryManager.
320 /// \param IsCode if it's true then allocateCodeSection() will be
321 /// used for emits, else allocateDataSection() will be used.
322 /// \return SectionID.
323 unsigned emitSection(const ObjectFile &Obj, const SectionRef &Section,
326 /// \brief Find Section in LocalSections. If the secton is not found - emit
327 /// it and store in LocalSections.
328 /// \param IsCode if it's true then allocateCodeSection() will be
329 /// used for emmits, else allocateDataSection() will be used.
330 /// \return SectionID.
331 unsigned findOrEmitSection(const ObjectFile &Obj, const SectionRef &Section,
332 bool IsCode, ObjSectionToIDMap &LocalSections);
334 // \brief Add a relocation entry that uses the given section.
335 void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID);
337 // \brief Add a relocation entry that uses the given symbol. This symbol may
338 // be found in the global symbol table, or it may be external.
339 void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName);
341 /// \brief Emits long jump instruction to Addr.
342 /// \return Pointer to the memory area for emitting target address.
343 uint8_t *createStubFunction(uint8_t *Addr, unsigned AbiVariant = 0);
345 /// \brief Resolves relocations from Relocs list with address from Value.
346 void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
348 /// \brief A object file specific relocation resolver
349 /// \param RE The relocation to be resolved
350 /// \param Value Target symbol address to apply the relocation action
351 virtual void resolveRelocation(const RelocationEntry &RE, uint64_t Value) = 0;
353 /// \brief Parses one or more object file relocations (some object files use
354 /// relocation pairs) and stores it to Relocations or SymbolRelocations
355 /// (this depends on the object file type).
356 /// \return Iterator to the next relocation that needs to be parsed.
357 virtual relocation_iterator
358 processRelocationRef(unsigned SectionID, relocation_iterator RelI,
359 const ObjectFile &Obj, ObjSectionToIDMap &ObjSectionToID,
362 /// \brief Resolve relocations to external symbols.
363 void resolveExternalSymbols();
365 /// \brief Update GOT entries for external symbols.
366 // The base class does nothing. ELF overrides this.
367 virtual void updateGOTEntries(StringRef Name, uint64_t Addr) {}
369 // \brief Compute an upper bound of the memory that is required to load all
371 void computeTotalAllocSize(const ObjectFile &Obj, uint64_t &CodeSize,
372 uint64_t &DataSizeRO, uint64_t &DataSizeRW);
374 // \brief Compute the stub buffer size required for a section
375 unsigned computeSectionStubBufSize(const ObjectFile &Obj,
376 const SectionRef &Section);
378 // \brief Implementation of the generic part of the loadObject algorithm.
379 std::pair<unsigned, unsigned> loadObjectImpl(const object::ObjectFile &Obj);
382 RuntimeDyldImpl(RTDyldMemoryManager *mm)
383 : MemMgr(mm), Checker(nullptr), ProcessAllSections(false), HasError(false) {
386 virtual ~RuntimeDyldImpl();
388 void setProcessAllSections(bool ProcessAllSections) {
389 this->ProcessAllSections = ProcessAllSections;
392 void setRuntimeDyldChecker(RuntimeDyldCheckerImpl *Checker) {
393 this->Checker = Checker;
396 virtual std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
397 loadObject(const object::ObjectFile &Obj) = 0;
399 uint8_t* getSymbolAddress(StringRef Name) const {
400 // FIXME: Just look up as a function for now. Overly simple of course.
402 RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
403 if (pos == GlobalSymbolTable.end())
405 const auto &SymInfo = pos->second;
406 return getSectionAddress(SymInfo.getSectionID()) + SymInfo.getOffset();
409 uint64_t getSymbolLoadAddress(StringRef Name) const {
410 // FIXME: Just look up as a function for now. Overly simple of course.
412 RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
413 if (pos == GlobalSymbolTable.end())
415 const auto &SymInfo = pos->second;
416 return getSectionLoadAddress(SymInfo.getSectionID()) + SymInfo.getOffset();
419 uint64_t getExportedSymbolLoadAddress(StringRef Name) const {
420 RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
421 if (pos == GlobalSymbolTable.end())
423 const auto &SymInfo = pos->second;
424 if (SymInfo.getVisibility() == SymbolInfo::Hidden)
426 return getSectionLoadAddress(SymInfo.getSectionID()) + SymInfo.getOffset();
429 void resolveRelocations();
431 void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
433 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
435 // Is the linker in an error state?
436 bool hasError() { return HasError; }
438 // Mark the error condition as handled and continue.
439 void clearError() { HasError = false; }
441 // Get the error message.
442 StringRef getErrorString() { return ErrorStr; }
444 virtual bool isCompatibleFile(const ObjectFile &Obj) const = 0;
446 virtual void registerEHFrames();
448 virtual void deregisterEHFrames();
450 virtual void finalizeLoad(const ObjectFile &ObjImg,
451 ObjSectionToIDMap &SectionMap) {}
454 } // end namespace llvm