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/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"
31 #include "llvm/Support/system_error.h"
35 using namespace llvm::object;
42 /// SectionEntry - represents a section emitted into memory by the dynamic
46 /// Name - section name.
49 /// Address - address in the linker's memory where the section resides.
52 /// Size - section size. Doesn't include the stubs.
55 /// LoadAddress - the address of the section in the target process's memory.
56 /// Used for situations in which JIT-ed code is being executed in the address
57 /// space of a separate process. If the code executes in the same address
58 /// space where it was JIT-ed, this just equals Address.
61 /// StubOffset - used for architectures with stub functions for far
62 /// relocations (like ARM).
65 /// ObjAddress - address of the section in the in-memory object file. Used
66 /// for calculating relocations in some object formats (like MachO).
69 SectionEntry(StringRef name, uint8_t *address, size_t size,
71 : Name(name), Address(address), Size(size),
72 LoadAddress((uintptr_t)address), StubOffset(size),
73 ObjAddress(objAddress) {}
76 /// RelocationEntry - used to represent relocations internally in the dynamic
78 class RelocationEntry {
80 /// SectionID - the section this relocation points to.
83 /// Offset - offset into the section.
86 /// RelType - relocation type.
89 /// Addend - the relocation addend encoded in the instruction itself. Also
90 /// used to make a relocation section relative instead of symbol relative.
93 /// SymOffset - Section offset of the relocation entry's symbol (used for GOT
97 /// True if this is a PCRel relocation (MachO specific).
100 /// The size of this relocation (MachO specific).
103 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend)
104 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
105 SymOffset(0), IsPCRel(false), Size(0) {}
107 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
109 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
110 SymOffset(symoffset), IsPCRel(false), Size(0) {}
112 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
113 bool IsPCRel, unsigned Size)
114 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
115 SymOffset(0), IsPCRel(IsPCRel), Size(Size) {}
118 class RelocationValueRef {
123 const char *SymbolName;
124 RelocationValueRef() : SectionID(0), Offset(0), Addend(0),
125 SymbolName(nullptr) {}
127 inline bool operator==(const RelocationValueRef &Other) const {
128 return SectionID == Other.SectionID && Offset == Other.Offset &&
129 Addend == Other.Addend && SymbolName == Other.SymbolName;
131 inline bool operator<(const RelocationValueRef &Other) const {
132 if (SectionID != Other.SectionID)
133 return SectionID < Other.SectionID;
134 if (Offset != Other.Offset)
135 return Offset < Other.Offset;
136 if (Addend != Other.Addend)
137 return Addend < Other.Addend;
138 return SymbolName < Other.SymbolName;
142 class RuntimeDyldImpl {
144 // The MemoryManager to load objects into.
145 RTDyldMemoryManager *MemMgr;
147 // A list of all sections emitted by the dynamic linker. These sections are
148 // referenced in the code by means of their index in this list - SectionID.
149 typedef SmallVector<SectionEntry, 64> SectionList;
150 SectionList Sections;
152 typedef unsigned SID; // Type for SectionIDs
153 #define RTDYLD_INVALID_SECTION_ID ((SID)(-1))
155 // Keep a map of sections from object file to the SectionID which
157 typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
159 // A global symbol table for symbols from all loaded modules. Maps the
160 // symbol name to a (SectionID, offset in section) pair.
161 typedef std::pair<unsigned, uintptr_t> SymbolLoc;
162 typedef StringMap<SymbolLoc> SymbolTableMap;
163 SymbolTableMap GlobalSymbolTable;
165 // Pair representing the size and alignment requirement for a common symbol.
166 typedef std::pair<unsigned, unsigned> CommonSymbolInfo;
167 // Keep a map of common symbols to their info pairs
168 typedef std::map<SymbolRef, CommonSymbolInfo> CommonSymbolMap;
170 // For each symbol, keep a list of relocations based on it. Anytime
171 // its address is reassigned (the JIT re-compiled the function, e.g.),
172 // the relocations get re-resolved.
173 // The symbol (or section) the relocation is sourced from is the Key
174 // in the relocation list where it's stored.
175 typedef SmallVector<RelocationEntry, 64> RelocationList;
176 // Relocations to sections already loaded. Indexed by SectionID which is the
177 // source of the address. The target where the address will be written is
178 // SectionID/Offset in the relocation itself.
179 DenseMap<unsigned, RelocationList> Relocations;
181 // Relocations to external symbols that are not yet resolved. Symbols are
182 // external when they aren't found in the global symbol table of all loaded
183 // modules. This map is indexed by symbol name.
184 StringMap<RelocationList> ExternalSymbolRelocations;
186 typedef std::map<RelocationValueRef, uintptr_t> StubMap;
188 Triple::ArchType Arch;
189 bool IsTargetLittleEndian;
191 // True if all sections should be passed to the memory manager, false if only
192 // sections containing relocations should be. Defaults to 'false'.
193 bool ProcessAllSections;
195 // This mutex prevents simultaneously loading objects from two different
196 // threads. This keeps us from having to protect individual data structures
197 // and guarantees that section allocation requests to the memory manager
198 // won't be interleaved between modules. It is also used in mapSectionAddress
199 // and resolveRelocations to protect write access to internal data structures.
201 // loadObject may be called on the same thread during the handling of of
202 // processRelocations, and that's OK. The handling of the relocation lists
203 // is written in such a way as to work correctly if new elements are added to
204 // the end of the list while the list is being processed.
207 virtual unsigned getMaxStubSize() = 0;
208 virtual unsigned getStubAlignment() = 0;
211 std::string ErrorStr;
213 // Set the error state and record an error string.
214 bool Error(const Twine &Msg) {
215 ErrorStr = Msg.str();
220 uint64_t getSectionLoadAddress(unsigned SectionID) {
221 return Sections[SectionID].LoadAddress;
224 uint8_t *getSectionAddress(unsigned SectionID) {
225 return (uint8_t *)Sections[SectionID].Address;
228 void writeInt16BE(uint8_t *Addr, uint16_t Value) {
229 if (IsTargetLittleEndian)
230 Value = sys::SwapByteOrder(Value);
231 *Addr = (Value >> 8) & 0xFF;
232 *(Addr + 1) = Value & 0xFF;
235 void writeInt32BE(uint8_t *Addr, uint32_t Value) {
236 if (IsTargetLittleEndian)
237 Value = sys::SwapByteOrder(Value);
238 *Addr = (Value >> 24) & 0xFF;
239 *(Addr + 1) = (Value >> 16) & 0xFF;
240 *(Addr + 2) = (Value >> 8) & 0xFF;
241 *(Addr + 3) = Value & 0xFF;
244 void writeInt64BE(uint8_t *Addr, uint64_t Value) {
245 if (IsTargetLittleEndian)
246 Value = sys::SwapByteOrder(Value);
247 *Addr = (Value >> 56) & 0xFF;
248 *(Addr + 1) = (Value >> 48) & 0xFF;
249 *(Addr + 2) = (Value >> 40) & 0xFF;
250 *(Addr + 3) = (Value >> 32) & 0xFF;
251 *(Addr + 4) = (Value >> 24) & 0xFF;
252 *(Addr + 5) = (Value >> 16) & 0xFF;
253 *(Addr + 6) = (Value >> 8) & 0xFF;
254 *(Addr + 7) = Value & 0xFF;
257 /// \brief Given the common symbols discovered in the object file, emit a
258 /// new section for them and update the symbol mappings in the object and
260 void emitCommonSymbols(ObjectImage &Obj, const CommonSymbolMap &CommonSymbols,
261 uint64_t TotalSize, SymbolTableMap &SymbolTable);
263 /// \brief Emits section data from the object file to the MemoryManager.
264 /// \param IsCode if it's true then allocateCodeSection() will be
265 /// used for emits, else allocateDataSection() will be used.
266 /// \return SectionID.
267 unsigned emitSection(ObjectImage &Obj, const SectionRef &Section,
270 /// \brief Find Section in LocalSections. If the secton is not found - emit
271 /// it and store in LocalSections.
272 /// \param IsCode if it's true then allocateCodeSection() will be
273 /// used for emmits, else allocateDataSection() will be used.
274 /// \return SectionID.
275 unsigned findOrEmitSection(ObjectImage &Obj, const SectionRef &Section,
276 bool IsCode, ObjSectionToIDMap &LocalSections);
278 // \brief Add a relocation entry that uses the given section.
279 void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID);
281 // \brief Add a relocation entry that uses the given symbol. This symbol may
282 // be found in the global symbol table, or it may be external.
283 void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName);
285 /// \brief Emits long jump instruction to Addr.
286 /// \return Pointer to the memory area for emitting target address.
287 uint8_t *createStubFunction(uint8_t *Addr);
289 /// \brief Resolves relocations from Relocs list with address from Value.
290 void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
292 /// \brief A object file specific relocation resolver
293 /// \param RE The relocation to be resolved
294 /// \param Value Target symbol address to apply the relocation action
295 virtual void resolveRelocation(const RelocationEntry &RE, uint64_t Value) = 0;
297 /// \brief Parses one or more object file relocations (some object files use
298 /// relocation pairs) and stores it to Relocations or SymbolRelocations
299 /// (this depends on the object file type).
300 /// \return Iterator to the next relocation that needs to be parsed.
301 virtual relocation_iterator
302 processRelocationRef(unsigned SectionID, relocation_iterator RelI,
303 ObjectImage &Obj, ObjSectionToIDMap &ObjSectionToID,
304 const SymbolTableMap &Symbols, StubMap &Stubs) = 0;
306 /// \brief Resolve relocations to external symbols.
307 void resolveExternalSymbols();
309 /// \brief Update GOT entries for external symbols.
310 // The base class does nothing. ELF overrides this.
311 virtual void updateGOTEntries(StringRef Name, uint64_t Addr) {}
313 // \brief Compute an upper bound of the memory that is required to load all
315 void computeTotalAllocSize(ObjectImage &Obj, uint64_t &CodeSize,
316 uint64_t &DataSizeRO, uint64_t &DataSizeRW);
318 // \brief Compute the stub buffer size required for a section
319 unsigned computeSectionStubBufSize(ObjectImage &Obj,
320 const SectionRef &Section);
323 RuntimeDyldImpl(RTDyldMemoryManager *mm)
324 : MemMgr(mm), ProcessAllSections(false), HasError(false) {}
326 virtual ~RuntimeDyldImpl();
328 void setProcessAllSections(bool ProcessAllSections) {
329 this->ProcessAllSections = ProcessAllSections;
332 ObjectImage *loadObject(ObjectImage *InputObject);
334 void *getSymbolAddress(StringRef Name) {
335 // FIXME: Just look up as a function for now. Overly simple of course.
337 SymbolTableMap::const_iterator pos = GlobalSymbolTable.find(Name);
338 if (pos == GlobalSymbolTable.end())
340 SymbolLoc Loc = pos->second;
341 return getSectionAddress(Loc.first) + Loc.second;
344 uint64_t getSymbolLoadAddress(StringRef Name) {
345 // FIXME: Just look up as a function for now. Overly simple of course.
347 SymbolTableMap::const_iterator pos = GlobalSymbolTable.find(Name);
348 if (pos == GlobalSymbolTable.end())
350 SymbolLoc Loc = pos->second;
351 return getSectionLoadAddress(Loc.first) + Loc.second;
354 void resolveRelocations();
356 void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
358 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
360 // Is the linker in an error state?
361 bool hasError() { return HasError; }
363 // Mark the error condition as handled and continue.
364 void clearError() { HasError = false; }
366 // Get the error message.
367 StringRef getErrorString() { return ErrorStr; }
369 virtual bool isCompatibleFormat(const ObjectBuffer *Buffer) const = 0;
370 virtual bool isCompatibleFile(const ObjectFile *Obj) const = 0;
372 virtual void registerEHFrames();
374 virtual void deregisterEHFrames();
376 virtual void finalizeLoad(ObjSectionToIDMap &SectionMap) {}
379 } // end namespace llvm