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//===- RuntimeDyld.h - Run-time dynamic linker for MC-JIT -------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// Interface for the runtime dynamic linker facilities of the MC-JIT.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H

#define LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H

#include "llvm/ADT/FunctionExtras.h"

#include "llvm/ADT/STLExtras.h"

#include "llvm/ADT/StringRef.h"

#include "llvm/DebugInfo/DIContext.h"

#include "llvm/ExecutionEngine/JITSymbol.h"

#include "llvm/Object/ObjectFile.h"

#include "llvm/Support/Error.h"

#include <algorithm>

#include <cassert>

#include <cstddef>

#include <cstdint>

#include <map>

#include <memory>

#include <string>

#include <system_error>

namespace llvm {

namespace object {

template <typename T> class OwningBinary;

} // end namespace object

/// Base class for errors originating in RuntimeDyld, e.g. missing relocation

/// support.

class RuntimeDyldError : public ErrorInfo<RuntimeDyldError> {

public:

  static char ID;

  RuntimeDyldError(std::string ErrMsg) : ErrMsg(std::move(ErrMsg)) {}

  void log(raw_ostream &OS) const override;

  const std::string &getErrorMessage() const { return ErrMsg; }

  std::error_code convertToErrorCode() const override;

private:

  std::string ErrMsg;

};

class RuntimeDyldImpl;

class RuntimeDyld {

public:

  // Change the address associated with a section when resolving relocations.

  // Any relocations already associated with the symbol will be re-resolved.

  void reassignSectionAddress(unsigned SectionID, uint64_t Addr);

  using NotifyStubEmittedFunction = std::function<void(

      StringRef FileName, StringRef SectionName, StringRef SymbolName,

      unsigned SectionID, uint32_t StubOffset)>;

  /// Information about the loaded object.

  class LoadedObjectInfo : public llvm::LoadedObjectInfo {

    friend class RuntimeDyldImpl;

  public:

    using ObjSectionToIDMap = std::map<object::SectionRef, unsigned>;

    LoadedObjectInfo(RuntimeDyldImpl &RTDyld, ObjSectionToIDMap ObjSecToIDMap)

        : RTDyld(RTDyld), ObjSecToIDMap(std::move(ObjSecToIDMap)) {}

    virtual object::OwningBinary<object::ObjectFile>

    getObjectForDebug(const object::ObjectFile &Obj) const = 0;

    uint64_t

    getSectionLoadAddress(const object::SectionRef &Sec) const override;

  protected:

    virtual void anchor();

    RuntimeDyldImpl &RTDyld;

    ObjSectionToIDMap ObjSecToIDMap;

  };

  /// Memory Management.

  class MemoryManager {

    friend class RuntimeDyld;

  public:

    MemoryManager() = default;

    virtual ~MemoryManager() = default;

    /// Allocate a memory block of (at least) the given size suitable for

    /// executable code. The SectionID is a unique identifier assigned by the

    /// RuntimeDyld instance, and optionally recorded by the memory manager to

    /// access a loaded section.

    virtual uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,

                                         unsigned SectionID,

                                         StringRef SectionName) = 0;

    /// Allocate a memory block of (at least) the given size suitable for data.

    /// The SectionID is a unique identifier assigned by the JIT engine, and

    /// optionally recorded by the memory manager to access a loaded section.

    virtual uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,

                                         unsigned SectionID,

                                         StringRef SectionName,

                                         bool IsReadOnly) = 0;

    /// An allocated TLS section

    struct TLSSection {

      /// The pointer to the initialization image

      uint8_t *InitializationImage;

      /// The TLS offset

      intptr_t Offset;

    };

    /// Allocate a memory block of (at least) the given size to be used for

    /// thread-local storage (TLS).

    virtual TLSSection allocateTLSSection(uintptr_t Size, unsigned Alignment,

                                          unsigned SectionID,

                                          StringRef SectionName);

    /// Inform the memory manager about the total amount of memory required to

    /// allocate all sections to be loaded:

    /// \p CodeSize - the total size of all code sections

    /// \p DataSizeRO - the total size of all read-only data sections

    /// \p DataSizeRW - the total size of all read-write data sections

    ///

    /// Note that by default the callback is disabled. To enable it

    /// redefine the method needsToReserveAllocationSpace to return true.

    virtual void reserveAllocationSpace(uintptr_t CodeSize, Align CodeAlign,

                                        uintptr_t RODataSize, Align RODataAlign,

                                        uintptr_t RWDataSize,

                                        Align RWDataAlign) {}

    /// Override to return true to enable the reserveAllocationSpace callback.

    virtual bool needsToReserveAllocationSpace() { return false; }

    /// Override to return false to tell LLVM no stub space will be needed.

    /// This requires some guarantees depending on architecuture, but when

    /// you know what you are doing it saves allocated space.

    virtual bool allowStubAllocation() const { return true; }

    /// Register the EH frames with the runtime so that c++ exceptions work.

    ///

    /// \p Addr parameter provides the local address of the EH frame section

    /// data, while \p LoadAddr provides the address of the data in the target

    /// address space.  If the section has not been remapped (which will usually

    /// be the case for local execution) these two values will be the same.

    virtual void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr,

                                  size_t Size) = 0;

    virtual void deregisterEHFrames() = 0;

    /// This method is called when object loading is complete and section page

    /// permissions can be applied.  It is up to the memory manager implementation

    /// to decide whether or not to act on this method.  The memory manager will

    /// typically allocate all sections as read-write and then apply specific

    /// permissions when this method is called.  Code sections cannot be executed

    /// until this function has been called.  In addition, any cache coherency

    /// operations needed to reliably use the memory are also performed.

    ///

    /// Returns true if an error occurred, false otherwise.

    virtual bool finalizeMemory(std::string *ErrMsg = nullptr) = 0;

    /// This method is called after an object has been loaded into memory but

    /// before relocations are applied to the loaded sections.

    ///

    /// Memory managers which are preparing code for execution in an external

    /// address space can use this call to remap the section addresses for the

    /// newly loaded object.

    ///

    /// For clients that do not need access to an ExecutionEngine instance this

    /// method should be preferred to its cousin

    /// MCJITMemoryManager::notifyObjectLoaded as this method is compatible with

    /// ORC JIT stacks.

    virtual void notifyObjectLoaded(RuntimeDyld &RTDyld,

                                    const object::ObjectFile &Obj) {}

  private:

    virtual void anchor();

    bool FinalizationLocked = false;

  };

  /// Construct a RuntimeDyld instance.

  RuntimeDyld(MemoryManager &MemMgr, JITSymbolResolver &Resolver);

  RuntimeDyld(const RuntimeDyld &) = delete;

  RuntimeDyld &operator=(const RuntimeDyld &) = delete;

  ~RuntimeDyld();

  /// Add the referenced object file to the list of objects to be loaded and

  /// relocated.

  std::unique_ptr<LoadedObjectInfo> loadObject(const object::ObjectFile &O);

  /// Get the address of our local copy of the symbol. This may or may not

  /// be the address used for relocation (clients can copy the data around

  /// and resolve relocatons based on where they put it).

  void *getSymbolLocalAddress(StringRef Name) const;

  /// Get the section ID for the section containing the given symbol.

  unsigned getSymbolSectionID(StringRef Name) const;

  /// Get the target address and flags for the named symbol.

  /// This address is the one used for relocation.

  JITEvaluatedSymbol getSymbol(StringRef Name) const;

  /// Returns a copy of the symbol table. This can be used by on-finalized

  /// callbacks to extract the symbol table before throwing away the

  /// RuntimeDyld instance. Because the map keys (StringRefs) are backed by

  /// strings inside the RuntimeDyld instance, the map should be processed

  /// before the RuntimeDyld instance is discarded.

  std::map<StringRef, JITEvaluatedSymbol> getSymbolTable() const;

  /// Resolve the relocations for all symbols we currently know about.

  void resolveRelocations();

  /// Map a section to its target address space value.

  /// Map the address of a JIT section as returned from the memory manager

  /// to the address in the target process as the running code will see it.

  /// This is the address which will be used for relocation resolution.

  void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);

  /// Returns the section's working memory.

  StringRef getSectionContent(unsigned SectionID) const;

  /// If the section was loaded, return the section's load address,

  /// otherwise return std::nullopt.

  uint64_t getSectionLoadAddress(unsigned SectionID) const;

  /// Set the NotifyStubEmitted callback. This is used for debugging

  /// purposes. A callback is made for each stub that is generated.

  void setNotifyStubEmitted(NotifyStubEmittedFunction NotifyStubEmitted) {

    this->NotifyStubEmitted = std::move(NotifyStubEmitted);

  }

  /// Register any EH frame sections that have been loaded but not previously

  /// registered with the memory manager.  Note, RuntimeDyld is responsible

  /// for identifying the EH frame and calling the memory manager with the

  /// EH frame section data.  However, the memory manager itself will handle

  /// the actual target-specific EH frame registration.

  void registerEHFrames();

  void deregisterEHFrames();

  bool hasError();

  StringRef getErrorString();

  /// By default, only sections that are "required for execution" are passed to

  /// the RTDyldMemoryManager, and other sections are discarded. Passing 'true'

  /// to this method will cause RuntimeDyld to pass all sections to its

  /// memory manager regardless of whether they are "required to execute" in the

  /// usual sense. This is useful for inspecting metadata sections that may not

  /// contain relocations, E.g. Debug info, stackmaps.

  ///

  /// Must be called before the first object file is loaded.

  void setProcessAllSections(bool ProcessAllSections) {

    assert(!Dyld && "setProcessAllSections must be called before loadObject.");

    this->ProcessAllSections = ProcessAllSections;

  }

  /// Perform all actions needed to make the code owned by this RuntimeDyld

  /// instance executable:

  ///

  /// 1) Apply relocations.

  /// 2) Register EH frames.

  /// 3) Update memory permissions*.

  ///

  /// * Finalization is potentially recursive**, and the 3rd step will only be

  ///   applied by the outermost call to finalize. This allows different

  ///   RuntimeDyld instances to share a memory manager without the innermost

  ///   finalization locking the memory and causing relocation fixup errors in

  ///   outer instances.

  ///

  /// ** Recursive finalization occurs when one RuntimeDyld instances needs the

  ///   address of a symbol owned by some other instance in order to apply

  ///   relocations.

  ///

  void finalizeWithMemoryManagerLocking();

private:

  friend void jitLinkForORC(

      object::OwningBinary<object::ObjectFile> O,

      RuntimeDyld::MemoryManager &MemMgr, JITSymbolResolver &Resolver,

      bool ProcessAllSections,

      unique_function<Error(const object::ObjectFile &Obj, LoadedObjectInfo &,

                            std::map<StringRef, JITEvaluatedSymbol>)>

          OnLoaded,

      unique_function<void(object::OwningBinary<object::ObjectFile> O,

                           std::unique_ptr<LoadedObjectInfo>, Error)>

          OnEmitted);

  // RuntimeDyldImpl is the actual class. RuntimeDyld is just the public

  // interface.

  std::unique_ptr<RuntimeDyldImpl> Dyld;

  MemoryManager &MemMgr;

  JITSymbolResolver &Resolver;

  bool ProcessAllSections;

  NotifyStubEmittedFunction NotifyStubEmitted;

};

// Asynchronous JIT link for ORC.

//

// Warning: This API is experimental and probably should not be used by anyone

// but ORC's RTDyldObjectLinkingLayer2. Internally it constructs a RuntimeDyld

// instance and uses continuation passing to perform the fix-up and finalize

// steps asynchronously.

void jitLinkForORC(

    object::OwningBinary<object::ObjectFile> O,

    RuntimeDyld::MemoryManager &MemMgr, JITSymbolResolver &Resolver,

    bool ProcessAllSections,

    unique_function<Error(const object::ObjectFile &Obj,

                          RuntimeDyld::LoadedObjectInfo &,

                          std::map<StringRef, JITEvaluatedSymbol>)>

        OnLoaded,

    unique_function<void(object::OwningBinary<object::ObjectFile>,

                         std::unique_ptr<RuntimeDyld::LoadedObjectInfo>, Error)>

        OnEmitted);

} // end namespace llvm

#endif // LLVM_EXECUTIONENGINE_RUNTIMEDYLD_H