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/SwapByteOrder.h"
29 #include "llvm/Support/raw_ostream.h"
30 #include "llvm/Support/system_error.h"
34 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), LoadAddress((uintptr_t)address),
72 StubOffset(size), 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.
92 /// SymOffset - Section offset of the relocation entry's symbol (used for GOT
96 /// True if this is a PCRel relocation (MachO specific).
99 /// The size of this relocation (MachO specific).
102 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend)
103 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
104 SymOffset(0), IsPCRel(false), Size(0) {}
106 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
108 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
109 SymOffset(symoffset), IsPCRel(false), Size(0) {}
111 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
112 bool IsPCRel, unsigned Size)
113 : SectionID(id), Offset(offset), RelType(type), Addend(addend),
114 SymOffset(0), IsPCRel(IsPCRel), Size(Size) {}
117 class RelocationValueRef {
122 const char *SymbolName;
123 RelocationValueRef(): SectionID(0), Offset(0), Addend(0), SymbolName(0) {}
125 inline bool operator==(const RelocationValueRef &Other) const {
126 return SectionID == Other.SectionID && Offset == Other.Offset &&
127 Addend == Other.Addend && SymbolName == Other.SymbolName;
129 inline bool operator <(const RelocationValueRef &Other) const {
130 if (SectionID != Other.SectionID)
131 return SectionID < Other.SectionID;
132 if (Offset != Other.Offset)
133 return Offset < Other.Offset;
134 if (Addend != Other.Addend)
135 return Addend < Other.Addend;
136 return SymbolName < Other.SymbolName;
140 class RuntimeDyldImpl {
142 // The MemoryManager to load objects into.
143 RTDyldMemoryManager *MemMgr;
145 // A list of all sections emitted by the dynamic linker. These sections are
146 // referenced in the code by means of their index in this list - SectionID.
147 typedef SmallVector<SectionEntry, 64> SectionList;
148 SectionList Sections;
150 typedef unsigned SID; // Type for SectionIDs
151 #define RTDYLD_INVALID_SECTION_ID ((SID)(-1))
153 // Keep a map of sections from object file to the SectionID which
155 typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
157 // A global symbol table for symbols from all loaded modules. Maps the
158 // symbol name to a (SectionID, offset in section) pair.
159 typedef std::pair<unsigned, uintptr_t> SymbolLoc;
160 typedef StringMap<SymbolLoc> SymbolTableMap;
161 SymbolTableMap GlobalSymbolTable;
163 // Pair representing the size and alignment requirement for a common symbol.
164 typedef std::pair<unsigned, unsigned> CommonSymbolInfo;
165 // Keep a map of common symbols to their info pairs
166 typedef std::map<SymbolRef, CommonSymbolInfo> CommonSymbolMap;
168 // For each symbol, keep a list of relocations based on it. Anytime
169 // its address is reassigned (the JIT re-compiled the function, e.g.),
170 // the relocations get re-resolved.
171 // The symbol (or section) the relocation is sourced from is the Key
172 // in the relocation list where it's stored.
173 typedef SmallVector<RelocationEntry, 64> RelocationList;
174 // Relocations to sections already loaded. Indexed by SectionID which is the
175 // source of the address. The target where the address will be written is
176 // SectionID/Offset in the relocation itself.
177 DenseMap<unsigned, RelocationList> Relocations;
179 // Relocations to external symbols that are not yet resolved. Symbols are
180 // external when they aren't found in the global symbol table of all loaded
181 // modules. This map is indexed by symbol name.
182 StringMap<RelocationList> ExternalSymbolRelocations;
184 typedef std::map<RelocationValueRef, uintptr_t> StubMap;
186 Triple::ArchType Arch;
188 inline unsigned getMaxStubSize() {
189 if (Arch == Triple::aarch64)
190 return 20; // movz; movk; movk; movk; br
191 if (Arch == Triple::arm || Arch == Triple::thumb)
192 return 8; // 32-bit instruction and 32-bit address
193 else if (Arch == Triple::mipsel || Arch == Triple::mips)
195 else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le)
197 else if (Arch == Triple::x86_64)
198 return 6; // 2-byte jmp instruction + 32-bit relative address
199 else if (Arch == Triple::systemz)
205 inline unsigned getStubAlignment() {
206 if (Arch == Triple::systemz)
213 std::string ErrorStr;
215 // Set the error state and record an error string.
216 bool Error(const Twine &Msg) {
217 ErrorStr = Msg.str();
222 uint64_t getSectionLoadAddress(unsigned SectionID) {
223 return Sections[SectionID].LoadAddress;
226 uint8_t *getSectionAddress(unsigned SectionID) {
227 return (uint8_t*)Sections[SectionID].Address;
230 void writeInt16BE(uint8_t *Addr, uint16_t Value) {
231 if (sys::IsLittleEndianHost)
232 Value = sys::SwapByteOrder(Value);
233 *Addr = (Value >> 8) & 0xFF;
234 *(Addr+1) = Value & 0xFF;
237 void writeInt32BE(uint8_t *Addr, uint32_t Value) {
238 if (sys::IsLittleEndianHost)
239 Value = sys::SwapByteOrder(Value);
240 *Addr = (Value >> 24) & 0xFF;
241 *(Addr+1) = (Value >> 16) & 0xFF;
242 *(Addr+2) = (Value >> 8) & 0xFF;
243 *(Addr+3) = Value & 0xFF;
246 void writeInt64BE(uint8_t *Addr, uint64_t Value) {
247 if (sys::IsLittleEndianHost)
248 Value = sys::SwapByteOrder(Value);
249 *Addr = (Value >> 56) & 0xFF;
250 *(Addr+1) = (Value >> 48) & 0xFF;
251 *(Addr+2) = (Value >> 40) & 0xFF;
252 *(Addr+3) = (Value >> 32) & 0xFF;
253 *(Addr+4) = (Value >> 24) & 0xFF;
254 *(Addr+5) = (Value >> 16) & 0xFF;
255 *(Addr+6) = (Value >> 8) & 0xFF;
256 *(Addr+7) = Value & 0xFF;
259 /// \brief Given the common symbols discovered in the object file, emit a
260 /// new section for them and update the symbol mappings in the object and
262 void emitCommonSymbols(ObjectImage &Obj,
263 const CommonSymbolMap &CommonSymbols,
265 SymbolTableMap &SymbolTable);
267 /// \brief Emits section data from the object file to the MemoryManager.
268 /// \param IsCode if it's true then allocateCodeSection() will be
269 /// used for emits, else allocateDataSection() will be used.
270 /// \return SectionID.
271 unsigned emitSection(ObjectImage &Obj,
272 const SectionRef &Section,
275 /// \brief Find Section in LocalSections. If the secton is not found - emit
276 /// it and store in LocalSections.
277 /// \param IsCode if it's true then allocateCodeSection() will be
278 /// used for emmits, else allocateDataSection() will be used.
279 /// \return SectionID.
280 unsigned findOrEmitSection(ObjectImage &Obj,
281 const SectionRef &Section,
283 ObjSectionToIDMap &LocalSections);
285 // \brief Add a relocation entry that uses the given section.
286 void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID);
288 // \brief Add a relocation entry that uses the given symbol. This symbol may
289 // be found in the global symbol table, or it may be external.
290 void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName);
292 /// \brief Emits long jump instruction to Addr.
293 /// \return Pointer to the memory area for emitting target address.
294 uint8_t* createStubFunction(uint8_t *Addr);
296 /// \brief Resolves relocations from Relocs list with address from Value.
297 void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
299 /// \brief A object file specific relocation resolver
300 /// \param RE The relocation to be resolved
301 /// \param Value Target symbol address to apply the relocation action
302 virtual void resolveRelocation(const RelocationEntry &RE, uint64_t Value) = 0;
304 /// \brief Parses the object file relocation and stores it to Relocations
305 /// or SymbolRelocations (this depends on the object file type).
306 virtual void processRelocationRef(unsigned SectionID,
309 ObjSectionToIDMap &ObjSectionToID,
310 const SymbolTableMap &Symbols,
313 /// \brief Resolve relocations to external symbols.
314 void resolveExternalSymbols();
316 /// \brief Update GOT entries for external symbols.
317 // The base class does nothing. ELF overrides this.
318 virtual void updateGOTEntries(StringRef Name, uint64_t Addr) {}
320 virtual ObjectImage *createObjectImage(ObjectBuffer *InputBuffer);
322 RuntimeDyldImpl(RTDyldMemoryManager *mm) : MemMgr(mm), HasError(false) {}
324 virtual ~RuntimeDyldImpl();
326 ObjectImage *loadObject(ObjectBuffer *InputBuffer);
328 void *getSymbolAddress(StringRef Name) {
329 // FIXME: Just look up as a function for now. Overly simple of course.
331 if (GlobalSymbolTable.find(Name) == GlobalSymbolTable.end())
333 SymbolLoc Loc = GlobalSymbolTable.lookup(Name);
334 return getSectionAddress(Loc.first) + Loc.second;
337 uint64_t getSymbolLoadAddress(StringRef Name) {
338 // FIXME: Just look up as a function for now. Overly simple of course.
340 if (GlobalSymbolTable.find(Name) == GlobalSymbolTable.end())
342 SymbolLoc Loc = GlobalSymbolTable.lookup(Name);
343 return getSectionLoadAddress(Loc.first) + Loc.second;
346 void resolveRelocations();
348 void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
350 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
352 // Is the linker in an error state?
353 bool hasError() { return HasError; }
355 // Mark the error condition as handled and continue.
356 void clearError() { HasError = false; }
358 // Get the error message.
359 StringRef getErrorString() { return ErrorStr; }
361 virtual bool isCompatibleFormat(const ObjectBuffer *Buffer) const = 0;
363 virtual void registerEHFrames();
365 virtual void finalizeLoad(ObjSectionToIDMap &SectionMap) {}
368 } // end namespace llvm