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//===- SectionMemoryManager.h - Memory manager for MCJIT/RtDyld -*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the declaration of a section-based memory manager used by
// the MCJIT execution engine and RuntimeDyld.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_EXECUTIONENGINE_SECTIONMEMORYMANAGER_H
#define LLVM_EXECUTIONENGINE_SECTIONMEMORYMANAGER_H
#include "llvm/ADT/SmallVector.h"
#include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Memory.h"
namespace llvm {
/// This is a simple memory manager which implements the methods called by
/// the RuntimeDyld class to allocate memory for section-based loading of
/// objects, usually those generated by the MCJIT execution engine.
///
/// This memory manager allocates all section memory as read-write. The
/// RuntimeDyld will copy JITed section memory into these allocated blocks
/// and perform any necessary linking and relocations.
///
/// Any client using this memory manager MUST ensure that section-specific
/// page permissions have been applied before attempting to execute functions
/// in the JITed object. Permissions can be applied either by calling
/// MCJIT::finalizeObject or by calling SectionMemoryManager::finalizeMemory
/// directly. Clients of MCJIT should call MCJIT::finalizeObject.
class SectionMemoryManager : public RTDyldMemoryManager {
SectionMemoryManager(const SectionMemoryManager&) = delete;
void operator=(const SectionMemoryManager&) = delete;
public:
SectionMemoryManager() { }
~SectionMemoryManager() override;
/// \brief Allocates a memory block of (at least) the given size suitable for
/// executable code.
///
/// The value of \p Alignment must be a power of two. If \p Alignment is zero
/// a default alignment of 16 will be used.
uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
unsigned SectionID,
StringRef SectionName) override;
/// \brief Allocates a memory block of (at least) the given size suitable for
/// executable code.
///
/// The value of \p Alignment must be a power of two. If \p Alignment is zero
/// a default alignment of 16 will be used.
uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
unsigned SectionID, StringRef SectionName,
bool isReadOnly) override;
/// \brief Update section-specific memory permissions and other attributes.
///
/// 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.
bool finalizeMemory(std::string *ErrMsg = nullptr) override;
/// \brief Invalidate instruction cache for code sections.
///
/// Some platforms with separate data cache and instruction cache require
/// explicit cache flush, otherwise JIT code manipulations (like resolved
/// relocations) will get to the data cache but not to the instruction cache.
///
/// This method is called from finalizeMemory.
virtual void invalidateInstructionCache();
private:
struct FreeMemBlock {
// The actual block of free memory
sys::MemoryBlock Free;
// If there is a pending allocation from the same reservation right before
// this block, store it's index in PendingMem, to be able to update the
// pending region if part of this block is allocated, rather than having to
// create a new one
unsigned PendingPrefixIndex;
};
struct MemoryGroup {
// PendingMem contains all blocks of memory (subblocks of AllocatedMem)
// which have not yet had their permissions applied, but have been given
// out to the user. FreeMem contains all block of memory, which have
// neither had their permissions applied, nor been given out to the user.
SmallVector<sys::MemoryBlock, 16> PendingMem;
SmallVector<FreeMemBlock, 16> FreeMem;
// All memory blocks that have been requested from the system
SmallVector<sys::MemoryBlock, 16> AllocatedMem;
sys::MemoryBlock Near;
};
uint8_t *allocateSection(MemoryGroup &MemGroup, uintptr_t Size,
unsigned Alignment);
std::error_code applyMemoryGroupPermissions(MemoryGroup &MemGroup,
unsigned Permissions);
MemoryGroup CodeMem;
MemoryGroup RWDataMem;
MemoryGroup RODataMem;
};
}
#endif // LLVM_EXECUTION_ENGINE_SECTION_MEMORY_MANAGER_H
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