include/llvm/ExecutionEngine/RuntimeDyld.h

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