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_RUNTIME_DYLD_IMPL_H
15 #define LLVM_RUNTIME_DYLD_IMPL_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/ObjectImage.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;
43 /// SectionEntry - represents a section emitted into memory by the dynamic
47 /// Name - section name.
50 /// Address - address in the linker's memory where the section resides.
53 /// Size - section size. Doesn't include the stubs.
56 /// LoadAddress - the address of the section in the target process's memory.
57 /// Used for situations in which JIT-ed code is being executed in the address
58 /// space of a separate process. If the code executes in the same address
59 /// space where it was JIT-ed, this just equals Address.
62 /// StubOffset - used for architectures with stub functions for far
63 /// relocations (like ARM).
66 /// ObjAddress - address of the section in the in-memory object file. Used
67 /// for calculating relocations in some object formats (like MachO).
70 SectionEntry(StringRef name, uint8_t *address, size_t size,
72 : Name(name), Address(address), Size(size),
73 LoadAddress((uintptr_t)address), StubOffset(size),
74 ObjAddress(objAddress) {}
77 /// RelocationEntry - used to represent relocations internally in the dynamic
79 class RelocationEntry {
81 /// SectionID - the section this relocation points to.
84 /// Offset - offset into the section.
87 /// RelType - relocation type.
90 /// Addend - the relocation addend encoded in the instruction itself. Also
91 /// used to make a relocation section relative instead of symbol relative.
99 /// SymOffset - Section offset of the relocation entry's symbol (used for GOT
103 SectionPair Sections;
106 /// True if this is a PCRel relocation (MachO specific).
109 /// The size of this relocation (MachO specific).
112 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend)
113 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
114 SymOffset(0), IsPCRel(false), Size(0) {}
116 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
118 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
119 SymOffset(symoffset), IsPCRel(false), Size(0) {}
121 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
122 bool IsPCRel, unsigned Size)
123 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
124 SymOffset(0), IsPCRel(IsPCRel), Size(Size) {}
126 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
127 unsigned SectionA, uint64_t SectionAOffset, unsigned SectionB,
128 uint64_t SectionBOffset, bool IsPCRel, unsigned Size)
129 : SectionID(id), Offset(offset), RelType(type),
130 Addend(SectionAOffset - SectionBOffset + addend), IsPCRel(IsPCRel),
132 Sections.SectionA = SectionA;
133 Sections.SectionB = SectionB;
137 class RelocationValueRef {
142 const char *SymbolName;
143 RelocationValueRef() : SectionID(0), Offset(0), Addend(0),
144 SymbolName(nullptr) {}
146 inline bool operator==(const RelocationValueRef &Other) const {
147 return SectionID == Other.SectionID && Offset == Other.Offset &&
148 Addend == Other.Addend && SymbolName == Other.SymbolName;
150 inline bool operator<(const RelocationValueRef &Other) const {
151 if (SectionID != Other.SectionID)
152 return SectionID < Other.SectionID;
153 if (Offset != Other.Offset)
154 return Offset < Other.Offset;
155 if (Addend != Other.Addend)
156 return Addend < Other.Addend;
157 return SymbolName < Other.SymbolName;
161 class RuntimeDyldImpl {
162 friend class RuntimeDyldChecker;
165 uint64_t getAnySymbolRemoteAddress(StringRef Symbol) {
166 if (uint64_t InternalSymbolAddr = getSymbolLoadAddress(Symbol))
167 return InternalSymbolAddr;
168 return MemMgr->getSymbolAddress(Symbol);
172 // The MemoryManager to load objects into.
173 RTDyldMemoryManager *MemMgr;
175 // A list of all sections emitted by the dynamic linker. These sections are
176 // referenced in the code by means of their index in this list - SectionID.
177 typedef SmallVector<SectionEntry, 64> SectionList;
178 SectionList Sections;
180 typedef unsigned SID; // Type for SectionIDs
181 #define RTDYLD_INVALID_SECTION_ID ((SID)(-1))
183 // Keep a map of sections from object file to the SectionID which
185 typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
187 // A global symbol table for symbols from all loaded modules. Maps the
188 // symbol name to a (SectionID, offset in section) pair.
189 typedef std::pair<unsigned, uintptr_t> SymbolLoc;
190 typedef StringMap<SymbolLoc> SymbolTableMap;
191 SymbolTableMap GlobalSymbolTable;
193 // Pair representing the size and alignment requirement for a common symbol.
194 typedef std::pair<unsigned, unsigned> CommonSymbolInfo;
195 // Keep a map of common symbols to their info pairs
196 typedef std::map<SymbolRef, CommonSymbolInfo> CommonSymbolMap;
198 // For each symbol, keep a list of relocations based on it. Anytime
199 // its address is reassigned (the JIT re-compiled the function, e.g.),
200 // the relocations get re-resolved.
201 // The symbol (or section) the relocation is sourced from is the Key
202 // in the relocation list where it's stored.
203 typedef SmallVector<RelocationEntry, 64> RelocationList;
204 // Relocations to sections already loaded. Indexed by SectionID which is the
205 // source of the address. The target where the address will be written is
206 // SectionID/Offset in the relocation itself.
207 DenseMap<unsigned, RelocationList> Relocations;
209 // Relocations to external symbols that are not yet resolved. Symbols are
210 // external when they aren't found in the global symbol table of all loaded
211 // modules. This map is indexed by symbol name.
212 StringMap<RelocationList> ExternalSymbolRelocations;
214 typedef std::map<RelocationValueRef, uintptr_t> StubMap;
216 Triple::ArchType Arch;
217 bool IsTargetLittleEndian;
219 // True if all sections should be passed to the memory manager, false if only
220 // sections containing relocations should be. Defaults to 'false'.
221 bool ProcessAllSections;
223 // This mutex prevents simultaneously loading objects from two different
224 // threads. This keeps us from having to protect individual data structures
225 // and guarantees that section allocation requests to the memory manager
226 // won't be interleaved between modules. It is also used in mapSectionAddress
227 // and resolveRelocations to protect write access to internal data structures.
229 // loadObject may be called on the same thread during the handling of of
230 // processRelocations, and that's OK. The handling of the relocation lists
231 // is written in such a way as to work correctly if new elements are added to
232 // the end of the list while the list is being processed.
235 virtual unsigned getMaxStubSize() = 0;
236 virtual unsigned getStubAlignment() = 0;
239 std::string ErrorStr;
241 // Set the error state and record an error string.
242 bool Error(const Twine &Msg) {
243 ErrorStr = Msg.str();
248 uint64_t getSectionLoadAddress(unsigned SectionID) {
249 return Sections[SectionID].LoadAddress;
252 uint8_t *getSectionAddress(unsigned SectionID) {
253 return (uint8_t *)Sections[SectionID].Address;
256 void writeInt16BE(uint8_t *Addr, uint16_t Value) {
257 if (IsTargetLittleEndian)
258 sys::swapByteOrder(Value);
259 *Addr = (Value >> 8) & 0xFF;
260 *(Addr + 1) = Value & 0xFF;
263 void writeInt32BE(uint8_t *Addr, uint32_t Value) {
264 if (IsTargetLittleEndian)
265 sys::swapByteOrder(Value);
266 *Addr = (Value >> 24) & 0xFF;
267 *(Addr + 1) = (Value >> 16) & 0xFF;
268 *(Addr + 2) = (Value >> 8) & 0xFF;
269 *(Addr + 3) = Value & 0xFF;
272 void writeInt64BE(uint8_t *Addr, uint64_t Value) {
273 if (IsTargetLittleEndian)
274 sys::swapByteOrder(Value);
275 *Addr = (Value >> 56) & 0xFF;
276 *(Addr + 1) = (Value >> 48) & 0xFF;
277 *(Addr + 2) = (Value >> 40) & 0xFF;
278 *(Addr + 3) = (Value >> 32) & 0xFF;
279 *(Addr + 4) = (Value >> 24) & 0xFF;
280 *(Addr + 5) = (Value >> 16) & 0xFF;
281 *(Addr + 6) = (Value >> 8) & 0xFF;
282 *(Addr + 7) = Value & 0xFF;
285 /// \brief Given the common symbols discovered in the object file, emit a
286 /// new section for them and update the symbol mappings in the object and
288 void emitCommonSymbols(ObjectImage &Obj, const CommonSymbolMap &CommonSymbols,
289 uint64_t TotalSize, SymbolTableMap &SymbolTable);
291 /// \brief Emits section data from the object file to the MemoryManager.
292 /// \param IsCode if it's true then allocateCodeSection() will be
293 /// used for emits, else allocateDataSection() will be used.
294 /// \return SectionID.
295 unsigned emitSection(ObjectImage &Obj, const SectionRef &Section,
298 /// \brief Find Section in LocalSections. If the secton is not found - emit
299 /// it and store in LocalSections.
300 /// \param IsCode if it's true then allocateCodeSection() will be
301 /// used for emmits, else allocateDataSection() will be used.
302 /// \return SectionID.
303 unsigned findOrEmitSection(ObjectImage &Obj, const SectionRef &Section,
304 bool IsCode, ObjSectionToIDMap &LocalSections);
306 // \brief Add a relocation entry that uses the given section.
307 void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID);
309 // \brief Add a relocation entry that uses the given symbol. This symbol may
310 // be found in the global symbol table, or it may be external.
311 void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName);
313 /// \brief Emits long jump instruction to Addr.
314 /// \return Pointer to the memory area for emitting target address.
315 uint8_t *createStubFunction(uint8_t *Addr);
317 /// \brief Resolves relocations from Relocs list with address from Value.
318 void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
320 /// \brief A object file specific relocation resolver
321 /// \param RE The relocation to be resolved
322 /// \param Value Target symbol address to apply the relocation action
323 virtual void resolveRelocation(const RelocationEntry &RE, uint64_t Value) = 0;
325 /// \brief Parses one or more object file relocations (some object files use
326 /// relocation pairs) and stores it to Relocations or SymbolRelocations
327 /// (this depends on the object file type).
328 /// \return Iterator to the next relocation that needs to be parsed.
329 virtual relocation_iterator
330 processRelocationRef(unsigned SectionID, relocation_iterator RelI,
331 ObjectImage &Obj, ObjSectionToIDMap &ObjSectionToID,
332 const SymbolTableMap &Symbols, StubMap &Stubs) = 0;
334 /// \brief Resolve relocations to external symbols.
335 void resolveExternalSymbols();
337 /// \brief Update GOT entries for external symbols.
338 // The base class does nothing. ELF overrides this.
339 virtual void updateGOTEntries(StringRef Name, uint64_t Addr) {}
341 // \brief Compute an upper bound of the memory that is required to load all
343 void computeTotalAllocSize(ObjectImage &Obj, uint64_t &CodeSize,
344 uint64_t &DataSizeRO, uint64_t &DataSizeRW);
346 // \brief Compute the stub buffer size required for a section
347 unsigned computeSectionStubBufSize(ObjectImage &Obj,
348 const SectionRef &Section);
351 RuntimeDyldImpl(RTDyldMemoryManager *mm)
352 : MemMgr(mm), ProcessAllSections(false), HasError(false) {
355 virtual ~RuntimeDyldImpl();
357 void setProcessAllSections(bool ProcessAllSections) {
358 this->ProcessAllSections = ProcessAllSections;
361 ObjectImage *loadObject(ObjectImage *InputObject);
363 uint8_t* getSymbolAddress(StringRef Name) {
364 // FIXME: Just look up as a function for now. Overly simple of course.
366 SymbolTableMap::const_iterator pos = GlobalSymbolTable.find(Name);
367 if (pos == GlobalSymbolTable.end())
369 SymbolLoc Loc = pos->second;
370 return getSectionAddress(Loc.first) + Loc.second;
373 uint64_t getSymbolLoadAddress(StringRef Name) {
374 // FIXME: Just look up as a function for now. Overly simple of course.
376 SymbolTableMap::const_iterator pos = GlobalSymbolTable.find(Name);
377 if (pos == GlobalSymbolTable.end())
379 SymbolLoc Loc = pos->second;
380 return getSectionLoadAddress(Loc.first) + Loc.second;
383 void resolveRelocations();
385 void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
387 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
389 // Is the linker in an error state?
390 bool hasError() { return HasError; }
392 // Mark the error condition as handled and continue.
393 void clearError() { HasError = false; }
395 // Get the error message.
396 StringRef getErrorString() { return ErrorStr; }
398 virtual bool isCompatibleFormat(const ObjectBuffer *Buffer) const = 0;
399 virtual bool isCompatibleFile(const ObjectFile *Obj) const = 0;
401 virtual void registerEHFrames();
403 virtual void deregisterEHFrames();
405 virtual void finalizeLoad(ObjectImage &ObjImg, ObjSectionToIDMap &SectionMap) {}
408 } // end namespace llvm