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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 for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// Interface for the runtime dynamic linker facilities of the MC-JIT.
#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> {
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;
std::string ErrMsg;
class RuntimeDyldImpl;
class RuntimeDyld {
// 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;
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;
getSectionLoadAddress(const object::SectionRef &Sec) const override;
virtual void anchor();
RuntimeDyldImpl &RTDyld;
ObjSectionToIDMap ObjSecToIDMap;
/// Memory Management.
class MemoryManager {
friend class RuntimeDyld;
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) {}
virtual void anchor();
bool FinalizationLocked = false;
/// Construct a RuntimeDyld instance.
RuntimeDyld(MemoryManager &MemMgr, JITSymbolResolver &Resolver);
RuntimeDyld(const RuntimeDyld &) = delete;
RuntimeDyld &operator=(const RuntimeDyld &) = delete;
/// 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();
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>)>
unique_function<void(object::OwningBinary<object::ObjectFile> O,
std::unique_ptr<LoadedObjectInfo>, Error)>
// 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>)>
std::unique_ptr<RuntimeDyld::LoadedObjectInfo>, Error)>
} // end namespace llvm