1 //===- RuntimeDyld.h - Run-time dynamic linker for MC-JIT -------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // Interface for the runtime dynamic linker facilities of the MC-JIT. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H 14 #define LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H 15 16 #include "llvm/ADT/STLExtras.h" 17 #include "llvm/ADT/StringRef.h" 18 #include "llvm/DebugInfo/DIContext.h" 19 #include "llvm/ExecutionEngine/JITSymbol.h" 20 #include "llvm/Object/ObjectFile.h" 21 #include "llvm/Support/Error.h" 22 #include <algorithm> 23 #include <cassert> 24 #include <cstddef> 25 #include <cstdint> 26 #include <map> 27 #include <memory> 28 #include <string> 29 #include <system_error> 30 31 namespace llvm { 32 33 namespace object { 34 35 template <typename T> class OwningBinary; 36 37 } // end namespace object 38 39 /// Base class for errors originating in RuntimeDyld, e.g. missing relocation 40 /// support. 41 class RuntimeDyldError : public ErrorInfo<RuntimeDyldError> { 42 public: 43 static char ID; 44 45 RuntimeDyldError(std::string ErrMsg) : ErrMsg(std::move(ErrMsg)) {} 46 47 void log(raw_ostream &OS) const override; 48 const std::string &getErrorMessage() const { return ErrMsg; } 49 std::error_code convertToErrorCode() const override; 50 51 private: 52 std::string ErrMsg; 53 }; 54 55 class RuntimeDyldImpl; 56 57 class RuntimeDyld { 58 protected: 59 // Change the address associated with a section when resolving relocations. 60 // Any relocations already associated with the symbol will be re-resolved. 61 void reassignSectionAddress(unsigned SectionID, uint64_t Addr); 62 63 public: 64 using NotifyStubEmittedFunction = std::function<void( 65 StringRef FileName, StringRef SectionName, StringRef SymbolName, 66 unsigned SectionID, uint32_t StubOffset)>; 67 68 /// Information about the loaded object. 69 class LoadedObjectInfo : public llvm::LoadedObjectInfo { 70 friend class RuntimeDyldImpl; 71 72 public: 73 using ObjSectionToIDMap = std::map<object::SectionRef, unsigned>; 74 75 LoadedObjectInfo(RuntimeDyldImpl &RTDyld, ObjSectionToIDMap ObjSecToIDMap) 76 : RTDyld(RTDyld), ObjSecToIDMap(std::move(ObjSecToIDMap)) {} 77 78 virtual object::OwningBinary<object::ObjectFile> 79 getObjectForDebug(const object::ObjectFile &Obj) const = 0; 80 81 uint64_t 82 getSectionLoadAddress(const object::SectionRef &Sec) const override; 83 84 protected: 85 virtual void anchor(); 86 87 RuntimeDyldImpl &RTDyld; 88 ObjSectionToIDMap ObjSecToIDMap; 89 }; 90 91 /// Memory Management. 92 class MemoryManager { 93 friend class RuntimeDyld; 94 95 public: 96 MemoryManager() = default; 97 virtual ~MemoryManager() = default; 98 99 /// Allocate a memory block of (at least) the given size suitable for 100 /// executable code. The SectionID is a unique identifier assigned by the 101 /// RuntimeDyld instance, and optionally recorded by the memory manager to 102 /// access a loaded section. 103 virtual uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment, 104 unsigned SectionID, 105 StringRef SectionName) = 0; 106 107 /// Allocate a memory block of (at least) the given size suitable for data. 108 /// The SectionID is a unique identifier assigned by the JIT engine, and 109 /// optionally recorded by the memory manager to access a loaded section. 110 virtual uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment, 111 unsigned SectionID, 112 StringRef SectionName, 113 bool IsReadOnly) = 0; 114 115 /// Inform the memory manager about the total amount of memory required to 116 /// allocate all sections to be loaded: 117 /// \p CodeSize - the total size of all code sections 118 /// \p DataSizeRO - the total size of all read-only data sections 119 /// \p DataSizeRW - the total size of all read-write data sections 120 /// 121 /// Note that by default the callback is disabled. To enable it 122 /// redefine the method needsToReserveAllocationSpace to return true. 123 virtual void reserveAllocationSpace(uintptr_t CodeSize, uint32_t CodeAlign, 124 uintptr_t RODataSize, 125 uint32_t RODataAlign, 126 uintptr_t RWDataSize, 127 uint32_t RWDataAlign) {} 128 129 /// Override to return true to enable the reserveAllocationSpace callback. 130 virtual bool needsToReserveAllocationSpace() { return false; } 131 132 /// Register the EH frames with the runtime so that c++ exceptions work. 133 /// 134 /// \p Addr parameter provides the local address of the EH frame section 135 /// data, while \p LoadAddr provides the address of the data in the target 136 /// address space. If the section has not been remapped (which will usually 137 /// be the case for local execution) these two values will be the same. 138 virtual void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr, 139 size_t Size) = 0; 140 virtual void deregisterEHFrames() = 0; 141 142 /// This method is called when object loading is complete and section page 143 /// permissions can be applied. It is up to the memory manager implementation 144 /// to decide whether or not to act on this method. The memory manager will 145 /// typically allocate all sections as read-write and then apply specific 146 /// permissions when this method is called. Code sections cannot be executed 147 /// until this function has been called. In addition, any cache coherency 148 /// operations needed to reliably use the memory are also performed. 149 /// 150 /// Returns true if an error occurred, false otherwise. 151 virtual bool finalizeMemory(std::string *ErrMsg = nullptr) = 0; 152 153 /// This method is called after an object has been loaded into memory but 154 /// before relocations are applied to the loaded sections. 155 /// 156 /// Memory managers which are preparing code for execution in an external 157 /// address space can use this call to remap the section addresses for the 158 /// newly loaded object. 159 /// 160 /// For clients that do not need access to an ExecutionEngine instance this 161 /// method should be preferred to its cousin 162 /// MCJITMemoryManager::notifyObjectLoaded as this method is compatible with 163 /// ORC JIT stacks. 164 virtual void notifyObjectLoaded(RuntimeDyld &RTDyld, 165 const object::ObjectFile &Obj) {} 166 167 private: 168 virtual void anchor(); 169 170 bool FinalizationLocked = false; 171 }; 172 173 /// Construct a RuntimeDyld instance. 174 RuntimeDyld(MemoryManager &MemMgr, JITSymbolResolver &Resolver); 175 RuntimeDyld(const RuntimeDyld &) = delete; 176 RuntimeDyld &operator=(const RuntimeDyld &) = delete; 177 ~RuntimeDyld(); 178 179 /// Add the referenced object file to the list of objects to be loaded and 180 /// relocated. 181 std::unique_ptr<LoadedObjectInfo> loadObject(const object::ObjectFile &O); 182 183 /// Get the address of our local copy of the symbol. This may or may not 184 /// be the address used for relocation (clients can copy the data around 185 /// and resolve relocatons based on where they put it). 186 void *getSymbolLocalAddress(StringRef Name) const; 187 188 /// Get the section ID for the section containing the given symbol. 189 unsigned getSymbolSectionID(StringRef Name) const; 190 191 /// Get the target address and flags for the named symbol. 192 /// This address is the one used for relocation. 193 JITEvaluatedSymbol getSymbol(StringRef Name) const; 194 195 /// Returns a copy of the symbol table. This can be used by on-finalized 196 /// callbacks to extract the symbol table before throwing away the 197 /// RuntimeDyld instance. Because the map keys (StringRefs) are backed by 198 /// strings inside the RuntimeDyld instance, the map should be processed 199 /// before the RuntimeDyld instance is discarded. 200 std::map<StringRef, JITEvaluatedSymbol> getSymbolTable() const; 201 202 /// Resolve the relocations for all symbols we currently know about. 203 void resolveRelocations(); 204 205 /// Map a section to its target address space value. 206 /// Map the address of a JIT section as returned from the memory manager 207 /// to the address in the target process as the running code will see it. 208 /// This is the address which will be used for relocation resolution. 209 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress); 210 211 /// Returns the section's working memory. 212 StringRef getSectionContent(unsigned SectionID) const; 213 214 /// If the section was loaded, return the section's load address, 215 /// otherwise return None. 216 uint64_t getSectionLoadAddress(unsigned SectionID) const; 217 218 /// Set the NotifyStubEmitted callback. This is used for debugging 219 /// purposes. A callback is made for each stub that is generated. 220 void setNotifyStubEmitted(NotifyStubEmittedFunction NotifyStubEmitted) { 221 this->NotifyStubEmitted = std::move(NotifyStubEmitted); 222 } 223 224 /// Register any EH frame sections that have been loaded but not previously 225 /// registered with the memory manager. Note, RuntimeDyld is responsible 226 /// for identifying the EH frame and calling the memory manager with the 227 /// EH frame section data. However, the memory manager itself will handle 228 /// the actual target-specific EH frame registration. 229 void registerEHFrames(); 230 231 void deregisterEHFrames(); 232 233 bool hasError(); 234 StringRef getErrorString(); 235 236 /// By default, only sections that are "required for execution" are passed to 237 /// the RTDyldMemoryManager, and other sections are discarded. Passing 'true' 238 /// to this method will cause RuntimeDyld to pass all sections to its 239 /// memory manager regardless of whether they are "required to execute" in the 240 /// usual sense. This is useful for inspecting metadata sections that may not 241 /// contain relocations, E.g. Debug info, stackmaps. 242 /// 243 /// Must be called before the first object file is loaded. 244 void setProcessAllSections(bool ProcessAllSections) { 245 assert(!Dyld && "setProcessAllSections must be called before loadObject."); 246 this->ProcessAllSections = ProcessAllSections; 247 } 248 249 /// Perform all actions needed to make the code owned by this RuntimeDyld 250 /// instance executable: 251 /// 252 /// 1) Apply relocations. 253 /// 2) Register EH frames. 254 /// 3) Update memory permissions*. 255 /// 256 /// * Finalization is potentially recursive**, and the 3rd step will only be 257 /// applied by the outermost call to finalize. This allows different 258 /// RuntimeDyld instances to share a memory manager without the innermost 259 /// finalization locking the memory and causing relocation fixup errors in 260 /// outer instances. 261 /// 262 /// ** Recursive finalization occurs when one RuntimeDyld instances needs the 263 /// address of a symbol owned by some other instance in order to apply 264 /// relocations. 265 /// 266 void finalizeWithMemoryManagerLocking(); 267 268 private: 269 friend void 270 jitLinkForORC(object::ObjectFile &Obj, 271 std::unique_ptr<MemoryBuffer> UnderlyingBuffer, 272 RuntimeDyld::MemoryManager &MemMgr, JITSymbolResolver &Resolver, 273 bool ProcessAllSections, 274 std::function<Error(std::unique_ptr<LoadedObjectInfo>, 275 std::map<StringRef, JITEvaluatedSymbol>)> 276 OnLoaded, 277 std::function<void(Error)> OnEmitted); 278 279 // RuntimeDyldImpl is the actual class. RuntimeDyld is just the public 280 // interface. 281 std::unique_ptr<RuntimeDyldImpl> Dyld; 282 MemoryManager &MemMgr; 283 JITSymbolResolver &Resolver; 284 bool ProcessAllSections; 285 NotifyStubEmittedFunction NotifyStubEmitted; 286 }; 287 288 // Asynchronous JIT link for ORC. 289 // 290 // Warning: This API is experimental and probably should not be used by anyone 291 // but ORC's RTDyldObjectLinkingLayer2. Internally it constructs a RuntimeDyld 292 // instance and uses continuation passing to perform the fix-up and finalize 293 // steps asynchronously. 294 void jitLinkForORC(object::ObjectFile &Obj, 295 std::unique_ptr<MemoryBuffer> UnderlyingBuffer, 296 RuntimeDyld::MemoryManager &MemMgr, 297 JITSymbolResolver &Resolver, bool ProcessAllSections, 298 std::function<Error(std::unique_ptr<LoadedObjectInfo>, 299 std::map<StringRef, JITEvaluatedSymbol>)> 300 OnLoaded, 301 std::function<void(Error)> OnEmitted); 302 303 } // end namespace llvm 304 305 #endif // LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H 306