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;
41 /// SectionEntry - represents a section emitted into memory by the dynamic
45 /// Name - section name.
48 /// Address - address in the linker's memory where the section resides.
51 /// Size - section size. Doesn't include the stubs.
54 /// LoadAddress - the address of the section in the target process's memory.
55 /// Used for situations in which JIT-ed code is being executed in the address
56 /// space of a separate process. If the code executes in the same address
57 /// space where it was JIT-ed, this just equals Address.
60 /// StubOffset - used for architectures with stub functions for far
61 /// relocations (like ARM).
64 /// ObjAddress - address of the section in the in-memory object file. Used
65 /// for calculating relocations in some object formats (like MachO).
68 SectionEntry(StringRef name, uint8_t *address, size_t size,
70 : Name(name), Address(address), Size(size),
71 LoadAddress(reinterpret_cast<uintptr_t>(address)), StubOffset(size),
72 ObjAddress(objAddress) {}
75 /// RelocationEntry - used to represent relocations internally in the dynamic
77 class RelocationEntry {
79 /// SectionID - the section this relocation points to.
82 /// Offset - offset into the section.
85 /// RelType - relocation type.
88 /// Addend - the relocation addend encoded in the instruction itself. Also
89 /// used to make a relocation section relative instead of symbol relative.
97 /// SymOffset - Section offset of the relocation entry's symbol (used for GOT
101 SectionPair Sections;
104 /// True if this is a PCRel relocation (MachO specific).
107 /// The size of this relocation (MachO specific).
110 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend)
111 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
112 SymOffset(0), IsPCRel(false), Size(0) {}
114 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
116 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
117 SymOffset(symoffset), IsPCRel(false), Size(0) {}
119 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
120 bool IsPCRel, unsigned Size)
121 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
122 SymOffset(0), IsPCRel(IsPCRel), Size(Size) {}
124 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
125 unsigned SectionA, uint64_t SectionAOffset, unsigned SectionB,
126 uint64_t SectionBOffset, bool IsPCRel, unsigned Size)
127 : SectionID(id), Offset(offset), RelType(type),
128 Addend(SectionAOffset - SectionBOffset + addend), IsPCRel(IsPCRel),
130 Sections.SectionA = SectionA;
131 Sections.SectionB = SectionB;
135 class RelocationValueRef {
140 const char *SymbolName;
141 RelocationValueRef() : SectionID(0), Offset(0), Addend(0),
142 SymbolName(nullptr) {}
144 inline bool operator==(const RelocationValueRef &Other) const {
145 return SectionID == Other.SectionID && Offset == Other.Offset &&
146 Addend == Other.Addend && SymbolName == Other.SymbolName;
148 inline bool operator<(const RelocationValueRef &Other) const {
149 if (SectionID != Other.SectionID)
150 return SectionID < Other.SectionID;
151 if (Offset != Other.Offset)
152 return Offset < Other.Offset;
153 if (Addend != Other.Addend)
154 return Addend < Other.Addend;
155 return SymbolName < Other.SymbolName;
159 class RuntimeDyldImpl {
160 friend class RuntimeDyld::LoadedObjectInfo;
161 friend class RuntimeDyldCheckerImpl;
163 // The MemoryManager to load objects into.
164 RTDyldMemoryManager *MemMgr;
166 // Attached RuntimeDyldChecker instance. Null if no instance attached.
167 RuntimeDyldCheckerImpl *Checker;
169 // A list of all sections emitted by the dynamic linker. These sections are
170 // referenced in the code by means of their index in this list - SectionID.
171 typedef SmallVector<SectionEntry, 64> SectionList;
172 SectionList Sections;
174 typedef unsigned SID; // Type for SectionIDs
175 #define RTDYLD_INVALID_SECTION_ID ((SID)(-1))
177 // Keep a map of sections from object file to the SectionID which
179 typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
181 // A global symbol table for symbols from all loaded modules. Maps the
182 // symbol name to a (SectionID, offset in section) pair.
183 typedef std::pair<unsigned, uintptr_t> SymbolLoc;
184 typedef StringMap<SymbolLoc> SymbolTableMap;
185 SymbolTableMap GlobalSymbolTable;
187 // Pair representing the size and alignment requirement for a common symbol.
188 typedef std::pair<unsigned, unsigned> CommonSymbolInfo;
189 // Keep a map of common symbols to their info pairs
190 typedef std::map<SymbolRef, CommonSymbolInfo> CommonSymbolMap;
192 // For each symbol, keep a list of relocations based on it. Anytime
193 // its address is reassigned (the JIT re-compiled the function, e.g.),
194 // the relocations get re-resolved.
195 // The symbol (or section) the relocation is sourced from is the Key
196 // in the relocation list where it's stored.
197 typedef SmallVector<RelocationEntry, 64> RelocationList;
198 // Relocations to sections already loaded. Indexed by SectionID which is the
199 // source of the address. The target where the address will be written is
200 // SectionID/Offset in the relocation itself.
201 DenseMap<unsigned, RelocationList> Relocations;
203 // Relocations to external symbols that are not yet resolved. Symbols are
204 // external when they aren't found in the global symbol table of all loaded
205 // modules. This map is indexed by symbol name.
206 StringMap<RelocationList> ExternalSymbolRelocations;
209 typedef std::map<RelocationValueRef, uintptr_t> StubMap;
211 Triple::ArchType Arch;
212 bool IsTargetLittleEndian;
214 // True if all sections should be passed to the memory manager, false if only
215 // sections containing relocations should be. Defaults to 'false'.
216 bool ProcessAllSections;
218 // This mutex prevents simultaneously loading objects from two different
219 // threads. This keeps us from having to protect individual data structures
220 // and guarantees that section allocation requests to the memory manager
221 // won't be interleaved between modules. It is also used in mapSectionAddress
222 // and resolveRelocations to protect write access to internal data structures.
224 // loadObject may be called on the same thread during the handling of of
225 // processRelocations, and that's OK. The handling of the relocation lists
226 // is written in such a way as to work correctly if new elements are added to
227 // the end of the list while the list is being processed.
230 virtual unsigned getMaxStubSize() = 0;
231 virtual unsigned getStubAlignment() = 0;
234 std::string ErrorStr;
236 // Set the error state and record an error string.
237 bool Error(const Twine &Msg) {
238 ErrorStr = Msg.str();
243 uint64_t getSectionLoadAddress(unsigned SectionID) const {
244 return Sections[SectionID].LoadAddress;
247 uint8_t *getSectionAddress(unsigned SectionID) const {
248 return (uint8_t *)Sections[SectionID].Address;
251 void writeInt16BE(uint8_t *Addr, uint16_t Value) {
252 if (IsTargetLittleEndian)
253 sys::swapByteOrder(Value);
254 *Addr = (Value >> 8) & 0xFF;
255 *(Addr + 1) = Value & 0xFF;
258 void writeInt32BE(uint8_t *Addr, uint32_t Value) {
259 if (IsTargetLittleEndian)
260 sys::swapByteOrder(Value);
261 *Addr = (Value >> 24) & 0xFF;
262 *(Addr + 1) = (Value >> 16) & 0xFF;
263 *(Addr + 2) = (Value >> 8) & 0xFF;
264 *(Addr + 3) = Value & 0xFF;
267 void writeInt64BE(uint8_t *Addr, uint64_t Value) {
268 if (IsTargetLittleEndian)
269 sys::swapByteOrder(Value);
270 *Addr = (Value >> 56) & 0xFF;
271 *(Addr + 1) = (Value >> 48) & 0xFF;
272 *(Addr + 2) = (Value >> 40) & 0xFF;
273 *(Addr + 3) = (Value >> 32) & 0xFF;
274 *(Addr + 4) = (Value >> 24) & 0xFF;
275 *(Addr + 5) = (Value >> 16) & 0xFF;
276 *(Addr + 6) = (Value >> 8) & 0xFF;
277 *(Addr + 7) = Value & 0xFF;
280 /// Endian-aware read Read the least significant Size bytes from Src.
281 uint64_t readBytesUnaligned(uint8_t *Src, unsigned Size) const;
283 /// Endian-aware write. Write the least significant Size bytes from Value to
285 void writeBytesUnaligned(uint64_t Value, uint8_t *Dst, unsigned Size) const;
287 /// \brief Given the common symbols discovered in the object file, emit a
288 /// new section for them and update the symbol mappings in the object and
290 void emitCommonSymbols(const ObjectFile &Obj,
291 const CommonSymbolMap &CommonSymbols,
292 uint64_t TotalSize, SymbolTableMap &SymbolTable);
294 /// \brief Emits section data from the object file to the MemoryManager.
295 /// \param IsCode if it's true then allocateCodeSection() will be
296 /// used for emits, else allocateDataSection() will be used.
297 /// \return SectionID.
298 unsigned emitSection(const ObjectFile &Obj, const SectionRef &Section,
301 /// \brief Find Section in LocalSections. If the secton is not found - emit
302 /// it and store in LocalSections.
303 /// \param IsCode if it's true then allocateCodeSection() will be
304 /// used for emmits, else allocateDataSection() will be used.
305 /// \return SectionID.
306 unsigned findOrEmitSection(const ObjectFile &Obj, const SectionRef &Section,
307 bool IsCode, ObjSectionToIDMap &LocalSections);
309 // \brief Add a relocation entry that uses the given section.
310 void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID);
312 // \brief Add a relocation entry that uses the given symbol. This symbol may
313 // be found in the global symbol table, or it may be external.
314 void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName);
316 /// \brief Emits long jump instruction to Addr.
317 /// \return Pointer to the memory area for emitting target address.
318 uint8_t *createStubFunction(uint8_t *Addr, unsigned AbiVariant = 0);
320 /// \brief Resolves relocations from Relocs list with address from Value.
321 void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
323 /// \brief A object file specific relocation resolver
324 /// \param RE The relocation to be resolved
325 /// \param Value Target symbol address to apply the relocation action
326 virtual void resolveRelocation(const RelocationEntry &RE, uint64_t Value) = 0;
328 /// \brief Parses one or more object file relocations (some object files use
329 /// relocation pairs) and stores it to Relocations or SymbolRelocations
330 /// (this depends on the object file type).
331 /// \return Iterator to the next relocation that needs to be parsed.
332 virtual relocation_iterator
333 processRelocationRef(unsigned SectionID, relocation_iterator RelI,
334 const ObjectFile &Obj, ObjSectionToIDMap &ObjSectionToID,
335 const SymbolTableMap &Symbols, StubMap &Stubs) = 0;
337 /// \brief Resolve relocations to external symbols.
338 void resolveExternalSymbols();
340 /// \brief Update GOT entries for external symbols.
341 // The base class does nothing. ELF overrides this.
342 virtual void updateGOTEntries(StringRef Name, uint64_t Addr) {}
344 // \brief Compute an upper bound of the memory that is required to load all
346 void computeTotalAllocSize(const ObjectFile &Obj, uint64_t &CodeSize,
347 uint64_t &DataSizeRO, uint64_t &DataSizeRW);
349 // \brief Compute the stub buffer size required for a section
350 unsigned computeSectionStubBufSize(const ObjectFile &Obj,
351 const SectionRef &Section);
353 // \brief Implementation of the generic part of the loadObject algorithm.
354 std::pair<unsigned, unsigned> loadObjectImpl(const object::ObjectFile &Obj);
357 RuntimeDyldImpl(RTDyldMemoryManager *mm)
358 : MemMgr(mm), Checker(nullptr), ProcessAllSections(false), HasError(false) {
361 virtual ~RuntimeDyldImpl();
363 void setProcessAllSections(bool ProcessAllSections) {
364 this->ProcessAllSections = ProcessAllSections;
367 void setRuntimeDyldChecker(RuntimeDyldCheckerImpl *Checker) {
368 this->Checker = Checker;
371 virtual std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
372 loadObject(const object::ObjectFile &Obj) = 0;
374 uint8_t* getSymbolAddress(StringRef Name) const {
375 // FIXME: Just look up as a function for now. Overly simple of course.
377 SymbolTableMap::const_iterator pos = GlobalSymbolTable.find(Name);
378 if (pos == GlobalSymbolTable.end())
380 SymbolLoc Loc = pos->second;
381 return getSectionAddress(Loc.first) + Loc.second;
384 uint64_t getSymbolLoadAddress(StringRef Name) const {
385 // FIXME: Just look up as a function for now. Overly simple of course.
387 SymbolTableMap::const_iterator pos = GlobalSymbolTable.find(Name);
388 if (pos == GlobalSymbolTable.end())
390 SymbolLoc Loc = pos->second;
391 return getSectionLoadAddress(Loc.first) + Loc.second;
394 void resolveRelocations();
396 void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
398 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
400 // Is the linker in an error state?
401 bool hasError() { return HasError; }
403 // Mark the error condition as handled and continue.
404 void clearError() { HasError = false; }
406 // Get the error message.
407 StringRef getErrorString() { return ErrorStr; }
409 virtual bool isCompatibleFile(const ObjectFile &Obj) const = 0;
411 virtual void registerEHFrames();
413 virtual void deregisterEHFrames();
415 virtual void finalizeLoad(const ObjectFile &ObjImg,
416 ObjSectionToIDMap &SectionMap) {}
419 } // end namespace llvm