RuntimeDyldImpl.h revision b889e0cd2fea4afee623d5be603b912b955a2eca
1//===-- RuntimeDyldImpl.h - Run-time dynamic linker for MC-JIT --*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// Interface for the implementations of runtime dynamic linker facilities. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_RUNTIME_DYLD_IMPL_H 15#define LLVM_RUNTIME_DYLD_IMPL_H 16 17#include "ObjectImage.h" 18#include "llvm/ExecutionEngine/RuntimeDyld.h" 19#include "llvm/ADT/DenseMap.h" 20#include "llvm/ADT/SmallVector.h" 21#include "llvm/ADT/StringMap.h" 22#include "llvm/ADT/Triple.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/raw_ostream.h" 28#include "llvm/Support/system_error.h" 29#include <map> 30 31using namespace llvm; 32using namespace llvm::object; 33 34namespace llvm { 35 36class MemoryBuffer; 37class Twine; 38 39 40/// SectionEntry - represents a section emitted into memory by the dynamic 41/// linker. 42class SectionEntry { 43public: 44 /// Address - address in the linker's memory where the section resides. 45 uint8_t *Address; 46 47 /// Size - section size. 48 size_t Size; 49 50 /// LoadAddress - the address of the section in the target process's memory. 51 /// Used for situations in which JIT-ed code is being executed in the address 52 /// space of a separate process. If the code executes in the same address 53 /// space where it was JIT-ed, this just equals Address. 54 uint64_t LoadAddress; 55 56 /// StubOffset - used for architectures with stub functions for far 57 /// relocations (like ARM). 58 uintptr_t StubOffset; 59 60 /// ObjAddress - address of the section in the in-memory object file. Used 61 /// for calculating relocations in some object formats (like MachO). 62 uintptr_t ObjAddress; 63 64 SectionEntry(uint8_t *address, size_t size, uintptr_t stubOffset, 65 uintptr_t objAddress) 66 : Address(address), Size(size), LoadAddress((uintptr_t)address), 67 StubOffset(stubOffset), ObjAddress(objAddress) {} 68}; 69 70/// RelocationEntry - used to represent relocations internally in the dynamic 71/// linker. 72class RelocationEntry { 73public: 74 /// SectionID - the section this relocation points to. 75 unsigned SectionID; 76 77 /// Offset - offset into the section. 78 uintptr_t Offset; 79 80 /// RelType - relocation type. 81 uint32_t RelType; 82 83 /// Addend - the relocation addend encoded in the instruction itself. Also 84 /// used to make a relocation section relative instead of symbol relative. 85 intptr_t Addend; 86 87 RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend) 88 : SectionID(id), Offset(offset), RelType(type), Addend(addend) {} 89}; 90 91/// ObjRelocationInfo - relocation information as read from the object file. 92/// Used to pass around data taken from object::RelocationRef, together with 93/// the section to which the relocation points (represented by a SectionID). 94class ObjRelocationInfo { 95public: 96 unsigned SectionID; 97 uint64_t Offset; 98 SymbolRef Symbol; 99 uint64_t Type; 100 int64_t AdditionalInfo; 101}; 102 103class RelocationValueRef { 104public: 105 unsigned SectionID; 106 intptr_t Addend; 107 const char *SymbolName; 108 RelocationValueRef(): SectionID(0), Addend(0), SymbolName(0) {} 109 110 inline bool operator==(const RelocationValueRef &Other) const { 111 return std::memcmp(this, &Other, sizeof(RelocationValueRef)) == 0; 112 } 113 inline bool operator <(const RelocationValueRef &Other) const { 114 return std::memcmp(this, &Other, sizeof(RelocationValueRef)) < 0; 115 } 116}; 117 118class RuntimeDyldImpl { 119protected: 120 // The MemoryManager to load objects into. 121 RTDyldMemoryManager *MemMgr; 122 123 // A list of all sections emitted by the dynamic linker. These sections are 124 // referenced in the code by means of their index in this list - SectionID. 125 typedef SmallVector<SectionEntry, 64> SectionList; 126 SectionList Sections; 127 128 // Keep a map of sections from object file to the SectionID which 129 // references it. 130 typedef std::map<SectionRef, unsigned> ObjSectionToIDMap; 131 132 // A global symbol table for symbols from all loaded modules. Maps the 133 // symbol name to a (SectionID, offset in section) pair. 134 typedef std::pair<unsigned, uintptr_t> SymbolLoc; 135 typedef StringMap<SymbolLoc> SymbolTableMap; 136 SymbolTableMap GlobalSymbolTable; 137 138 // Keep a map of common symbols to their sizes 139 typedef std::map<SymbolRef, unsigned> CommonSymbolMap; 140 141 // For each symbol, keep a list of relocations based on it. Anytime 142 // its address is reassigned (the JIT re-compiled the function, e.g.), 143 // the relocations get re-resolved. 144 // The symbol (or section) the relocation is sourced from is the Key 145 // in the relocation list where it's stored. 146 typedef SmallVector<RelocationEntry, 64> RelocationList; 147 // Relocations to sections already loaded. Indexed by SectionID which is the 148 // source of the address. The target where the address will be written is 149 // SectionID/Offset in the relocation itself. 150 DenseMap<unsigned, RelocationList> Relocations; 151 152 // Relocations to external symbols that are not yet resolved. Symbols are 153 // external when they aren't found in the global symbol table of all loaded 154 // modules. This map is indexed by symbol name. 155 StringMap<RelocationList> ExternalSymbolRelocations; 156 157 typedef std::map<RelocationValueRef, uintptr_t> StubMap; 158 159 Triple::ArchType Arch; 160 161 inline unsigned getMaxStubSize() { 162 if (Arch == Triple::arm || Arch == Triple::thumb) 163 return 8; // 32-bit instruction and 32-bit address 164 else if (Arch == Triple::mipsel) 165 return 16; 166 else 167 return 0; 168 } 169 170 bool HasError; 171 std::string ErrorStr; 172 173 // Set the error state and record an error string. 174 bool Error(const Twine &Msg) { 175 ErrorStr = Msg.str(); 176 HasError = true; 177 return true; 178 } 179 180 uint8_t *getSectionAddress(unsigned SectionID) { 181 return (uint8_t*)Sections[SectionID].Address; 182 } 183 184 /// \brief Given the common symbols discovered in the object file, emit a 185 /// new section for them and update the symbol mappings in the object and 186 /// symbol table. 187 void emitCommonSymbols(ObjectImage &Obj, 188 const CommonSymbolMap &CommonSymbols, 189 uint64_t TotalSize, 190 SymbolTableMap &SymbolTable); 191 192 /// \brief Emits section data from the object file to the MemoryManager. 193 /// \param IsCode if it's true then allocateCodeSection() will be 194 /// used for emits, else allocateDataSection() will be used. 195 /// \return SectionID. 196 unsigned emitSection(ObjectImage &Obj, 197 const SectionRef &Section, 198 bool IsCode); 199 200 /// \brief Find Section in LocalSections. If the secton is not found - emit 201 /// it and store in LocalSections. 202 /// \param IsCode if it's true then allocateCodeSection() will be 203 /// used for emmits, else allocateDataSection() will be used. 204 /// \return SectionID. 205 unsigned findOrEmitSection(ObjectImage &Obj, 206 const SectionRef &Section, 207 bool IsCode, 208 ObjSectionToIDMap &LocalSections); 209 210 // \brief Add a relocation entry that uses the given section. 211 void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID); 212 213 // \brief Add a relocation entry that uses the given symbol. This symbol may 214 // be found in the global symbol table, or it may be external. 215 void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName); 216 217 /// \brief Emits long jump instruction to Addr. 218 /// \return Pointer to the memory area for emitting target address. 219 uint8_t* createStubFunction(uint8_t *Addr); 220 221 /// \brief Resolves relocations from Relocs list with address from Value. 222 void resolveRelocationList(const RelocationList &Relocs, uint64_t Value); 223 void resolveRelocationEntry(const RelocationEntry &RE, uint64_t Value); 224 225 /// \brief A object file specific relocation resolver 226 /// \param Address Address to apply the relocation action 227 /// \param Value Target symbol address to apply the relocation action 228 /// \param Type object file specific relocation type 229 /// \param Addend A constant addend used to compute the value to be stored 230 /// into the relocatable field 231 virtual void resolveRelocation(uint8_t *LocalAddress, 232 uint64_t FinalAddress, 233 uint64_t Value, 234 uint32_t Type, 235 int64_t Addend) = 0; 236 237 /// \brief Parses the object file relocation and stores it to Relocations 238 /// or SymbolRelocations (this depends on the object file type). 239 virtual void processRelocationRef(const ObjRelocationInfo &Rel, 240 ObjectImage &Obj, 241 ObjSectionToIDMap &ObjSectionToID, 242 const SymbolTableMap &Symbols, 243 StubMap &Stubs) = 0; 244 245 /// \brief Resolve relocations to external symbols. 246 void resolveExternalSymbols(); 247 virtual ObjectImage *createObjectImage(const MemoryBuffer *InputBuffer); 248 virtual void handleObjectLoaded(ObjectImage *Obj) 249 { 250 // Subclasses may choose to retain this image if they have a use for it 251 delete Obj; 252 } 253 254public: 255 RuntimeDyldImpl(RTDyldMemoryManager *mm) : MemMgr(mm), HasError(false) {} 256 257 virtual ~RuntimeDyldImpl(); 258 259 bool loadObject(const MemoryBuffer *InputBuffer); 260 261 void *getSymbolAddress(StringRef Name) { 262 // FIXME: Just look up as a function for now. Overly simple of course. 263 // Work in progress. 264 if (GlobalSymbolTable.find(Name) == GlobalSymbolTable.end()) 265 return 0; 266 SymbolLoc Loc = GlobalSymbolTable.lookup(Name); 267 return getSectionAddress(Loc.first) + Loc.second; 268 } 269 270 void resolveRelocations(); 271 272 void reassignSectionAddress(unsigned SectionID, uint64_t Addr); 273 274 void mapSectionAddress(void *LocalAddress, uint64_t TargetAddress); 275 276 // Is the linker in an error state? 277 bool hasError() { return HasError; } 278 279 // Mark the error condition as handled and continue. 280 void clearError() { HasError = false; } 281 282 // Get the error message. 283 StringRef getErrorString() { return ErrorStr; } 284 285 virtual bool isCompatibleFormat(const MemoryBuffer *InputBuffer) const = 0; 286 287}; 288 289} // end namespace llvm 290 291 292#endif 293