194 lines
8.4 KiB
C
194 lines
8.4 KiB
C
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//===- SectionMemoryManager.h - Memory manager for MCJIT/RtDyld -*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the declaration of a section-based memory manager used by
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// the MCJIT execution engine and RuntimeDyld.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_EXECUTIONENGINE_SECTIONMEMORYMANAGER_H
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#define LLVM_EXECUTIONENGINE_SECTIONMEMORYMANAGER_H
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
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#include "llvm/Support/Memory.h"
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#include <cstdint>
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#include <string>
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#include <system_error>
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namespace llvm {
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/// This is a simple memory manager which implements the methods called by
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/// the RuntimeDyld class to allocate memory for section-based loading of
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/// objects, usually those generated by the MCJIT execution engine.
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///
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/// This memory manager allocates all section memory as read-write. The
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/// RuntimeDyld will copy JITed section memory into these allocated blocks
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/// and perform any necessary linking and relocations.
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///
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/// Any client using this memory manager MUST ensure that section-specific
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/// page permissions have been applied before attempting to execute functions
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/// in the JITed object. Permissions can be applied either by calling
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/// MCJIT::finalizeObject or by calling SectionMemoryManager::finalizeMemory
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/// directly. Clients of MCJIT should call MCJIT::finalizeObject.
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class SectionMemoryManager : public RTDyldMemoryManager {
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public:
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/// This enum describes the various reasons to allocate pages from
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/// allocateMappedMemory.
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enum class AllocationPurpose {
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Code,
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ROData,
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RWData,
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};
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/// Implementations of this interface are used by SectionMemoryManager to
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/// request pages from the operating system.
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class MemoryMapper {
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public:
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/// This method attempts to allocate \p NumBytes bytes of virtual memory for
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/// \p Purpose. \p NearBlock may point to an existing allocation, in which
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/// case an attempt is made to allocate more memory near the existing block.
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/// The actual allocated address is not guaranteed to be near the requested
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/// address. \p Flags is used to set the initial protection flags for the
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/// block of the memory. \p EC [out] returns an object describing any error
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/// that occurs.
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///
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/// This method may allocate more than the number of bytes requested. The
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/// actual number of bytes allocated is indicated in the returned
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/// MemoryBlock.
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///
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/// The start of the allocated block must be aligned with the system
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/// allocation granularity (64K on Windows, page size on Linux). If the
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/// address following \p NearBlock is not so aligned, it will be rounded up
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/// to the next allocation granularity boundary.
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///
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/// \r a non-null MemoryBlock if the function was successful, otherwise a
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/// null MemoryBlock with \p EC describing the error.
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virtual sys::MemoryBlock
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allocateMappedMemory(AllocationPurpose Purpose, size_t NumBytes,
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const sys::MemoryBlock *const NearBlock,
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unsigned Flags, std::error_code &EC) = 0;
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/// This method sets the protection flags for a block of memory to the state
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/// specified by \p Flags. The behavior is not specified if the memory was
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/// not allocated using the allocateMappedMemory method.
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/// \p Block describes the memory block to be protected.
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/// \p Flags specifies the new protection state to be assigned to the block.
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///
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/// If \p Flags is MF_WRITE, the actual behavior varies with the operating
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/// system (i.e. MF_READ | MF_WRITE on Windows) and the target architecture
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/// (i.e. MF_WRITE -> MF_READ | MF_WRITE on i386).
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///
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/// \r error_success if the function was successful, or an error_code
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/// describing the failure if an error occurred.
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virtual std::error_code protectMappedMemory(const sys::MemoryBlock &Block,
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unsigned Flags) = 0;
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/// This method releases a block of memory that was allocated with the
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/// allocateMappedMemory method. It should not be used to release any memory
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/// block allocated any other way.
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/// \p Block describes the memory to be released.
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///
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/// \r error_success if the function was successful, or an error_code
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/// describing the failure if an error occurred.
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virtual std::error_code releaseMappedMemory(sys::MemoryBlock &M) = 0;
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virtual ~MemoryMapper();
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};
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/// Creates a SectionMemoryManager instance with \p MM as the associated
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/// memory mapper. If \p MM is nullptr then a default memory mapper is used
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/// that directly calls into the operating system.
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SectionMemoryManager(MemoryMapper *MM = nullptr);
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SectionMemoryManager(const SectionMemoryManager &) = delete;
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void operator=(const SectionMemoryManager &) = delete;
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~SectionMemoryManager() override;
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/// Allocates a memory block of (at least) the given size suitable for
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/// executable code.
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///
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/// The value of \p Alignment must be a power of two. If \p Alignment is zero
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/// a default alignment of 16 will be used.
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uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
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unsigned SectionID,
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StringRef SectionName) override;
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/// Allocates a memory block of (at least) the given size suitable for
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/// executable code.
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///
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/// The value of \p Alignment must be a power of two. If \p Alignment is zero
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/// a default alignment of 16 will be used.
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uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
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unsigned SectionID, StringRef SectionName,
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bool isReadOnly) override;
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/// Update section-specific memory permissions and other attributes.
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///
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/// This method is called when object loading is complete and section page
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/// permissions can be applied. It is up to the memory manager implementation
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/// to decide whether or not to act on this method. The memory manager will
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/// typically allocate all sections as read-write and then apply specific
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/// permissions when this method is called. Code sections cannot be executed
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/// until this function has been called. In addition, any cache coherency
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/// operations needed to reliably use the memory are also performed.
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///
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/// \returns true if an error occurred, false otherwise.
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bool finalizeMemory(std::string *ErrMsg = nullptr) override;
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/// Invalidate instruction cache for code sections.
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///
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/// Some platforms with separate data cache and instruction cache require
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/// explicit cache flush, otherwise JIT code manipulations (like resolved
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/// relocations) will get to the data cache but not to the instruction cache.
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///
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/// This method is called from finalizeMemory.
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virtual void invalidateInstructionCache();
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private:
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struct FreeMemBlock {
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// The actual block of free memory
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sys::MemoryBlock Free;
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// If there is a pending allocation from the same reservation right before
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// this block, store it's index in PendingMem, to be able to update the
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// pending region if part of this block is allocated, rather than having to
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// create a new one
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unsigned PendingPrefixIndex;
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};
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struct MemoryGroup {
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// PendingMem contains all blocks of memory (subblocks of AllocatedMem)
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// which have not yet had their permissions applied, but have been given
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// out to the user. FreeMem contains all block of memory, which have
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// neither had their permissions applied, nor been given out to the user.
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SmallVector<sys::MemoryBlock, 16> PendingMem;
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SmallVector<FreeMemBlock, 16> FreeMem;
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// All memory blocks that have been requested from the system
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SmallVector<sys::MemoryBlock, 16> AllocatedMem;
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sys::MemoryBlock Near;
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};
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uint8_t *allocateSection(AllocationPurpose Purpose, uintptr_t Size,
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unsigned Alignment);
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std::error_code applyMemoryGroupPermissions(MemoryGroup &MemGroup,
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unsigned Permissions);
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void anchor() override;
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MemoryGroup CodeMem;
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MemoryGroup RWDataMem;
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MemoryGroup RODataMem;
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MemoryMapper &MMapper;
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};
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} // end namespace llvm
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#endif // LLVM_EXECUTION_ENGINE_SECTION_MEMORY_MANAGER_H
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