1 //===-- RuntimeDyld.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 runtime dynamic linker facilities of the MC-JIT.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H
15 #define LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H
17 #include "JITSymbolFlags.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/Object/ObjectFile.h"
21 #include "llvm/Support/Memory.h"
22 #include "llvm/DebugInfo/DIContext.h"
30 template <typename T> class OwningBinary;
33 class RuntimeDyldImpl;
34 class RuntimeDyldCheckerImpl;
37 friend class RuntimeDyldCheckerImpl;
39 RuntimeDyld(const RuntimeDyld &) = delete;
40 void operator=(const RuntimeDyld &) = delete;
43 // Change the address associated with a section when resolving relocations.
44 // Any relocations already associated with the symbol will be re-resolved.
45 void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
48 /// \brief Information about a named symbol.
49 class SymbolInfo : public JITSymbolBase {
51 SymbolInfo(std::nullptr_t) : JITSymbolBase(JITSymbolFlags::None), Address(0) {}
52 SymbolInfo(uint64_t Address, JITSymbolFlags Flags)
53 : JITSymbolBase(Flags), Address(Address) {}
54 explicit operator bool() const { return Address != 0; }
55 uint64_t getAddress() const { return Address; }
60 /// \brief Information about the loaded object.
61 class LoadedObjectInfo : public llvm::LoadedObjectInfo {
62 friend class RuntimeDyldImpl;
64 typedef std::map<object::SectionRef, unsigned> ObjSectionToIDMap;
66 LoadedObjectInfo(RuntimeDyldImpl &RTDyld, ObjSectionToIDMap ObjSecToIDMap)
67 : RTDyld(RTDyld), ObjSecToIDMap(ObjSecToIDMap) { }
69 virtual object::OwningBinary<object::ObjectFile>
70 getObjectForDebug(const object::ObjectFile &Obj) const = 0;
73 getSectionLoadAddress(const object::SectionRef &Sec) const override;
76 virtual void anchor();
78 RuntimeDyldImpl &RTDyld;
79 ObjSectionToIDMap ObjSecToIDMap;
82 template <typename Derived> struct LoadedObjectInfoHelper : LoadedObjectInfo {
84 LoadedObjectInfoHelper(const LoadedObjectInfoHelper &) = default;
85 LoadedObjectInfoHelper() = default;
88 LoadedObjectInfoHelper(RuntimeDyldImpl &RTDyld,
89 LoadedObjectInfo::ObjSectionToIDMap ObjSecToIDMap)
90 : LoadedObjectInfo(RTDyld, std::move(ObjSecToIDMap)) {}
91 std::unique_ptr<llvm::LoadedObjectInfo> clone() const override {
92 return llvm::make_unique<Derived>(static_cast<const Derived &>(*this));
96 /// \brief Memory Management.
98 friend class RuntimeDyld;
100 MemoryManager() : FinalizationLocked(false) {}
101 virtual ~MemoryManager() {}
103 /// Allocate a memory block of (at least) the given size suitable for
104 /// executable code. The SectionID is a unique identifier assigned by the
105 /// RuntimeDyld instance, and optionally recorded by the memory manager to
106 /// access a loaded section.
107 virtual uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
109 StringRef SectionName) = 0;
111 /// Allocate a memory block of (at least) the given size suitable for data.
112 /// The SectionID is a unique identifier assigned by the JIT engine, and
113 /// optionally recorded by the memory manager to access a loaded section.
114 virtual uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
116 StringRef SectionName,
117 bool IsReadOnly) = 0;
119 /// Inform the memory manager about the total amount of memory required to
120 /// allocate all sections to be loaded:
121 /// \p CodeSize - the total size of all code sections
122 /// \p DataSizeRO - the total size of all read-only data sections
123 /// \p DataSizeRW - the total size of all read-write data sections
125 /// Note that by default the callback is disabled. To enable it
126 /// redefine the method needsToReserveAllocationSpace to return true.
127 virtual void reserveAllocationSpace(uintptr_t CodeSize,
128 uintptr_t DataSizeRO,
129 uintptr_t DataSizeRW) {}
131 /// Override to return true to enable the reserveAllocationSpace callback.
132 virtual bool needsToReserveAllocationSpace() { return false; }
134 /// Register the EH frames with the runtime so that c++ exceptions work.
136 /// \p Addr parameter provides the local address of the EH frame section
137 /// data, while \p LoadAddr provides the address of the data in the target
138 /// address space. If the section has not been remapped (which will usually
139 /// be the case for local execution) these two values will be the same.
140 virtual void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr,
142 virtual void deregisterEHFrames(uint8_t *addr, uint64_t LoadAddr,
145 /// This method is called when object loading is complete and section page
146 /// permissions can be applied. It is up to the memory manager implementation
147 /// to decide whether or not to act on this method. The memory manager will
148 /// typically allocate all sections as read-write and then apply specific
149 /// permissions when this method is called. Code sections cannot be executed
150 /// until this function has been called. In addition, any cache coherency
151 /// operations needed to reliably use the memory are also performed.
153 /// Returns true if an error occurred, false otherwise.
154 virtual bool finalizeMemory(std::string *ErrMsg = nullptr) = 0;
157 virtual void anchor();
158 bool FinalizationLocked;
161 /// \brief Symbol resolution.
162 class SymbolResolver {
164 virtual ~SymbolResolver() {}
166 /// This method returns the address of the specified function or variable.
167 /// It is used to resolve symbols during module linking.
169 /// If the returned symbol's address is equal to ~0ULL then RuntimeDyld will
170 /// skip all relocations for that symbol, and the client will be responsible
171 /// for handling them manually.
172 virtual SymbolInfo findSymbol(const std::string &Name) = 0;
174 /// This method returns the address of the specified symbol if it exists
175 /// within the logical dynamic library represented by this
176 /// RTDyldMemoryManager. Unlike getSymbolAddress, queries through this
177 /// interface should return addresses for hidden symbols.
179 /// This is of particular importance for the Orc JIT APIs, which support lazy
180 /// compilation by breaking up modules: Each of those broken out modules
181 /// must be able to resolve hidden symbols provided by the others. Clients
182 /// writing memory managers for MCJIT can usually ignore this method.
184 /// This method will be queried by RuntimeDyld when checking for previous
185 /// definitions of common symbols. It will *not* be queried by default when
186 /// resolving external symbols (this minimises the link-time overhead for
187 /// MCJIT clients who don't care about Orc features). If you are writing a
188 /// RTDyldMemoryManager for Orc and want "external" symbol resolution to
189 /// search the logical dylib, you should override your getSymbolAddress
190 /// method call this method directly.
191 virtual SymbolInfo findSymbolInLogicalDylib(const std::string &Name) = 0;
193 virtual void anchor();
196 /// \brief Construct a RuntimeDyld instance.
197 RuntimeDyld(MemoryManager &MemMgr, SymbolResolver &Resolver);
200 /// Add the referenced object file to the list of objects to be loaded and
202 std::unique_ptr<LoadedObjectInfo> loadObject(const object::ObjectFile &O);
204 /// Get the address of our local copy of the symbol. This may or may not
205 /// be the address used for relocation (clients can copy the data around
206 /// and resolve relocatons based on where they put it).
207 void *getSymbolLocalAddress(StringRef Name) const;
209 /// Get the target address and flags for the named symbol.
210 /// This address is the one used for relocation.
211 SymbolInfo getSymbol(StringRef Name) const;
213 /// Resolve the relocations for all symbols we currently know about.
214 void resolveRelocations();
216 /// Map a section to its target address space value.
217 /// Map the address of a JIT section as returned from the memory manager
218 /// to the address in the target process as the running code will see it.
219 /// This is the address which will be used for relocation resolution.
220 void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
222 /// Register any EH frame sections that have been loaded but not previously
223 /// registered with the memory manager. Note, RuntimeDyld is responsible
224 /// for identifying the EH frame and calling the memory manager with the
225 /// EH frame section data. However, the memory manager itself will handle
226 /// the actual target-specific EH frame registration.
227 void registerEHFrames();
229 void deregisterEHFrames();
232 StringRef getErrorString();
234 /// By default, only sections that are "required for execution" are passed to
235 /// the RTDyldMemoryManager, and other sections are discarded. Passing 'true'
236 /// to this method will cause RuntimeDyld to pass all sections to its
237 /// memory manager regardless of whether they are "required to execute" in the
238 /// usual sense. This is useful for inspecting metadata sections that may not
239 /// contain relocations, E.g. Debug info, stackmaps.
241 /// Must be called before the first object file is loaded.
242 void setProcessAllSections(bool ProcessAllSections) {
243 assert(!Dyld && "setProcessAllSections must be called before loadObject.");
244 this->ProcessAllSections = ProcessAllSections;
247 /// Perform all actions needed to make the code owned by this RuntimeDyld
248 /// instance executable:
250 /// 1) Apply relocations.
251 /// 2) Register EH frames.
252 /// 3) Update memory permissions*.
254 /// * Finalization is potentially recursive**, and the 3rd step will only be
255 /// applied by the outermost call to finalize. This allows different
256 /// RuntimeDyld instances to share a memory manager without the innermost
257 /// finalization locking the memory and causing relocation fixup errors in
260 /// ** Recursive finalization occurs when one RuntimeDyld instances needs the
261 /// address of a symbol owned by some other instance in order to apply
264 void finalizeWithMemoryManagerLocking();
267 // RuntimeDyldImpl is the actual class. RuntimeDyld is just the public
269 std::unique_ptr<RuntimeDyldImpl> Dyld;
270 MemoryManager &MemMgr;
271 SymbolResolver &Resolver;
272 bool ProcessAllSections;
273 RuntimeDyldCheckerImpl *Checker;
276 } // end namespace llvm
278 #endif // LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H