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;
187 bool IsTargetLittleEndian;
189 inline unsigned getMaxStubSize() {
190 if (Arch == Triple::aarch64)
191 return 20; // movz; movk; movk; movk; br
192 if (Arch == Triple::arm || Arch == Triple::thumb)
193 return 8; // 32-bit instruction and 32-bit address
194 else if (Arch == Triple::mipsel || Arch == Triple::mips)
196 else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le)
198 else if (Arch == Triple::x86_64)
199 return 6; // 2-byte jmp instruction + 32-bit relative address
200 else if (Arch == Triple::systemz)
206 inline unsigned getStubAlignment() {
207 if (Arch == Triple::systemz)
214 std::string ErrorStr;
216 // Set the error state and record an error string.
217 bool Error(const Twine &Msg) {
218 ErrorStr = Msg.str();
223 uint64_t getSectionLoadAddress(unsigned SectionID) {
224 return Sections[SectionID].LoadAddress;
227 uint8_t *getSectionAddress(unsigned SectionID) {
228 return (uint8_t*)Sections[SectionID].Address;
231 void writeInt16BE(uint8_t *Addr, uint16_t Value) {
232 if (IsTargetLittleEndian)
233 Value = sys::SwapByteOrder(Value);
234 *Addr = (Value >> 8) & 0xFF;
235 *(Addr+1) = Value & 0xFF;
238 void writeInt32BE(uint8_t *Addr, uint32_t Value) {
239 if (IsTargetLittleEndian)
240 Value = sys::SwapByteOrder(Value);
241 *Addr = (Value >> 24) & 0xFF;
242 *(Addr+1) = (Value >> 16) & 0xFF;
243 *(Addr+2) = (Value >> 8) & 0xFF;
244 *(Addr+3) = Value & 0xFF;
247 void writeInt64BE(uint8_t *Addr, uint64_t Value) {
248 if (IsTargetLittleEndian)
249 Value = sys::SwapByteOrder(Value);
250 *Addr = (Value >> 56) & 0xFF;
251 *(Addr+1) = (Value >> 48) & 0xFF;
252 *(Addr+2) = (Value >> 40) & 0xFF;
253 *(Addr+3) = (Value >> 32) & 0xFF;
254 *(Addr+4) = (Value >> 24) & 0xFF;
255 *(Addr+5) = (Value >> 16) & 0xFF;
256 *(Addr+6) = (Value >> 8) & 0xFF;
257 *(Addr+7) = Value & 0xFF;
260 /// \brief Given the common symbols discovered in the object file, emit a
261 /// new section for them and update the symbol mappings in the object and
263 void emitCommonSymbols(ObjectImage &Obj,
264 const CommonSymbolMap &CommonSymbols,
266 SymbolTableMap &SymbolTable);
268 /// \brief Emits section data from the object file to the MemoryManager.
269 /// \param IsCode if it's true then allocateCodeSection() will be
270 /// used for emits, else allocateDataSection() will be used.
271 /// \return SectionID.
272 unsigned emitSection(ObjectImage &Obj,
273 const SectionRef &Section,
276 /// \brief Find Section in LocalSections. If the secton is not found - emit
277 /// it and store in LocalSections.
278 /// \param IsCode if it's true then allocateCodeSection() will be
279 /// used for emmits, else allocateDataSection() will be used.
280 /// \return SectionID.
281 unsigned findOrEmitSection(ObjectImage &Obj,
282 const SectionRef &Section,
284 ObjSectionToIDMap &LocalSections);
286 // \brief Add a relocation entry that uses the given section.
287 void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID);
289 // \brief Add a relocation entry that uses the given symbol. This symbol may
290 // be found in the global symbol table, or it may be external.
291 void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName);
293 /// \brief Emits long jump instruction to Addr.
294 /// \return Pointer to the memory area for emitting target address.
295 uint8_t* createStubFunction(uint8_t *Addr);
297 /// \brief Resolves relocations from Relocs list with address from Value.
298 void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
300 /// \brief A object file specific relocation resolver
301 /// \param RE The relocation to be resolved
302 /// \param Value Target symbol address to apply the relocation action
303 virtual void resolveRelocation(const RelocationEntry &RE, uint64_t Value) = 0;
305 /// \brief Parses the object file relocation and stores it to Relocations
306 /// or SymbolRelocations (this depends on the object file type).
307 virtual void processRelocationRef(unsigned SectionID,
310 ObjSectionToIDMap &ObjSectionToID,
311 const SymbolTableMap &Symbols,
314 /// \brief Resolve relocations to external symbols.
315 void resolveExternalSymbols();
317 /// \brief Update GOT entries for external symbols.
318 // The base class does nothing. ELF overrides this.
319 virtual void updateGOTEntries(StringRef Name, uint64_t Addr) {}
321 virtual ObjectImage *createObjectImage(ObjectBuffer *InputBuffer);
323 RuntimeDyldImpl(RTDyldMemoryManager *mm) : MemMgr(mm), HasError(false) {}
325 virtual ~RuntimeDyldImpl();
327 ObjectImage *loadObject(ObjectBuffer *InputBuffer);
329 void *getSymbolAddress(StringRef Name) {
330 // FIXME: Just look up as a function for now. Overly simple of course.
332 if (GlobalSymbolTable.find(Name) == GlobalSymbolTable.end())
334 SymbolLoc Loc = GlobalSymbolTable.lookup(Name);
335 return getSectionAddress(Loc.first) + Loc.second;
338 uint64_t getSymbolLoadAddress(StringRef Name) {
339 // FIXME: Just look up as a function for now. Overly simple of course.
341 if (GlobalSymbolTable.find(Name) == GlobalSymbolTable.end())
343 SymbolLoc Loc = GlobalSymbolTable.lookup(Name);
344 return getSectionLoadAddress(Loc.first) + Loc.second;
347 void resolveRelocations();
349 void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
351 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
353 // Is the linker in an error state?
354 bool hasError() { return HasError; }
356 // Mark the error condition as handled and continue.
357 void clearError() { HasError = false; }
359 // Get the error message.
360 StringRef getErrorString() { return ErrorStr; }
362 virtual bool isCompatibleFormat(const ObjectBuffer *Buffer) const = 0;
364 virtual void registerEHFrames();
366 virtual void finalizeLoad(ObjSectionToIDMap &SectionMap) {}
369 } // end namespace llvm