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;
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), LoadAddress((uintptr_t)address),
73 StubOffset(size), 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), SymbolName(0) {}
126 inline bool operator==(const RelocationValueRef &Other) const {
127 return SectionID == Other.SectionID && Offset == Other.Offset &&
128 Addend == Other.Addend && SymbolName == Other.SymbolName;
130 inline bool operator <(const RelocationValueRef &Other) const {
131 if (SectionID != Other.SectionID)
132 return SectionID < Other.SectionID;
133 if (Offset != Other.Offset)
134 return Offset < Other.Offset;
135 if (Addend != Other.Addend)
136 return Addend < Other.Addend;
137 return SymbolName < Other.SymbolName;
141 class RuntimeDyldImpl {
143 // The MemoryManager to load objects into.
144 RTDyldMemoryManager *MemMgr;
146 // A list of all sections emitted by the dynamic linker. These sections are
147 // referenced in the code by means of their index in this list - SectionID.
148 typedef SmallVector<SectionEntry, 64> SectionList;
149 SectionList Sections;
151 typedef unsigned SID; // Type for SectionIDs
152 #define RTDYLD_INVALID_SECTION_ID ((SID)(-1))
154 // Keep a map of sections from object file to the SectionID which
156 typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
158 // A global symbol table for symbols from all loaded modules. Maps the
159 // symbol name to a (SectionID, offset in section) pair.
160 typedef std::pair<unsigned, uintptr_t> SymbolLoc;
161 typedef StringMap<SymbolLoc> SymbolTableMap;
162 SymbolTableMap GlobalSymbolTable;
164 // Pair representing the size and alignment requirement for a common symbol.
165 typedef std::pair<unsigned, unsigned> CommonSymbolInfo;
166 // Keep a map of common symbols to their info pairs
167 typedef std::map<SymbolRef, CommonSymbolInfo> CommonSymbolMap;
169 // For each symbol, keep a list of relocations based on it. Anytime
170 // its address is reassigned (the JIT re-compiled the function, e.g.),
171 // the relocations get re-resolved.
172 // The symbol (or section) the relocation is sourced from is the Key
173 // in the relocation list where it's stored.
174 typedef SmallVector<RelocationEntry, 64> RelocationList;
175 // Relocations to sections already loaded. Indexed by SectionID which is the
176 // source of the address. The target where the address will be written is
177 // SectionID/Offset in the relocation itself.
178 DenseMap<unsigned, RelocationList> Relocations;
180 // Relocations to external symbols that are not yet resolved. Symbols are
181 // external when they aren't found in the global symbol table of all loaded
182 // modules. This map is indexed by symbol name.
183 StringMap<RelocationList> ExternalSymbolRelocations;
185 typedef std::map<RelocationValueRef, uintptr_t> StubMap;
187 Triple::ArchType Arch;
188 bool IsTargetLittleEndian;
190 // This mutex prevents simultaneously loading objects from two different
191 // threads. This keeps us from having to protect individual data structures
192 // and guarantees that section allocation requests to the memory manager
193 // won't be interleaved between modules. It is also used in mapSectionAddress
194 // and resolveRelocations to protect write access to internal data structures.
196 // loadObject may be called on the same thread during the handling of of
197 // processRelocations, and that's OK. The handling of the relocation lists
198 // is written in such a way as to work correctly if new elements are added to
199 // the end of the list while the list is being processed.
202 virtual unsigned getMaxStubSize() = 0;
203 virtual unsigned getStubAlignment() = 0;
206 std::string ErrorStr;
208 // Set the error state and record an error string.
209 bool Error(const Twine &Msg) {
210 ErrorStr = Msg.str();
215 uint64_t getSectionLoadAddress(unsigned SectionID) {
216 return Sections[SectionID].LoadAddress;
219 uint8_t *getSectionAddress(unsigned SectionID) {
220 return (uint8_t*)Sections[SectionID].Address;
223 void writeInt16BE(uint8_t *Addr, uint16_t Value) {
224 if (IsTargetLittleEndian)
225 Value = sys::SwapByteOrder(Value);
226 *Addr = (Value >> 8) & 0xFF;
227 *(Addr+1) = Value & 0xFF;
230 void writeInt32BE(uint8_t *Addr, uint32_t Value) {
231 if (IsTargetLittleEndian)
232 Value = sys::SwapByteOrder(Value);
233 *Addr = (Value >> 24) & 0xFF;
234 *(Addr+1) = (Value >> 16) & 0xFF;
235 *(Addr+2) = (Value >> 8) & 0xFF;
236 *(Addr+3) = Value & 0xFF;
239 void writeInt64BE(uint8_t *Addr, uint64_t Value) {
240 if (IsTargetLittleEndian)
241 Value = sys::SwapByteOrder(Value);
242 *Addr = (Value >> 56) & 0xFF;
243 *(Addr+1) = (Value >> 48) & 0xFF;
244 *(Addr+2) = (Value >> 40) & 0xFF;
245 *(Addr+3) = (Value >> 32) & 0xFF;
246 *(Addr+4) = (Value >> 24) & 0xFF;
247 *(Addr+5) = (Value >> 16) & 0xFF;
248 *(Addr+6) = (Value >> 8) & 0xFF;
249 *(Addr+7) = Value & 0xFF;
252 /// \brief Given the common symbols discovered in the object file, emit a
253 /// new section for them and update the symbol mappings in the object and
255 void emitCommonSymbols(ObjectImage &Obj,
256 const CommonSymbolMap &CommonSymbols,
258 SymbolTableMap &SymbolTable);
260 /// \brief Emits section data from the object file to the MemoryManager.
261 /// \param IsCode if it's true then allocateCodeSection() will be
262 /// used for emits, else allocateDataSection() will be used.
263 /// \return SectionID.
264 unsigned emitSection(ObjectImage &Obj,
265 const SectionRef &Section,
268 /// \brief Find Section in LocalSections. If the secton is not found - emit
269 /// it and store in LocalSections.
270 /// \param IsCode if it's true then allocateCodeSection() will be
271 /// used for emmits, else allocateDataSection() will be used.
272 /// \return SectionID.
273 unsigned findOrEmitSection(ObjectImage &Obj,
274 const SectionRef &Section,
276 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 the object file relocation and stores it to Relocations
298 /// or SymbolRelocations (this depends on the object file type).
299 virtual void processRelocationRef(unsigned SectionID,
302 ObjSectionToIDMap &ObjSectionToID,
303 const SymbolTableMap &Symbols,
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 virtual ObjectImage *createObjectImage(ObjectBuffer *InputBuffer);
315 RuntimeDyldImpl(RTDyldMemoryManager *mm) : MemMgr(mm), HasError(false) {}
317 virtual ~RuntimeDyldImpl();
319 ObjectImage *loadObject(ObjectBuffer *InputBuffer);
321 void *getSymbolAddress(StringRef Name) {
322 // FIXME: Just look up as a function for now. Overly simple of course.
324 SymbolTableMap::const_iterator pos = GlobalSymbolTable.find(Name);
325 if (pos == GlobalSymbolTable.end())
327 SymbolLoc Loc = pos->second;
328 return getSectionAddress(Loc.first) + Loc.second;
331 uint64_t getSymbolLoadAddress(StringRef Name) {
332 // FIXME: Just look up as a function for now. Overly simple of course.
334 SymbolTableMap::const_iterator pos = GlobalSymbolTable.find(Name);
335 if (pos == GlobalSymbolTable.end())
337 SymbolLoc Loc = pos->second;
338 return getSectionLoadAddress(Loc.first) + Loc.second;
341 void resolveRelocations();
343 void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
345 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
347 // Is the linker in an error state?
348 bool hasError() { return HasError; }
350 // Mark the error condition as handled and continue.
351 void clearError() { HasError = false; }
353 // Get the error message.
354 StringRef getErrorString() { return ErrorStr; }
356 virtual bool isCompatibleFormat(const ObjectBuffer *Buffer) const = 0;
358 virtual void registerEHFrames();
360 virtual void deregisterEHFrames();
362 virtual void finalizeLoad(ObjSectionToIDMap &SectionMap) {}
365 } // end namespace llvm