| //===- SectionMemoryManager.h - Memory manager for MCJIT/RtDyld -*- 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 |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // 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/ADT/StringRef.h" |
| #include "llvm/ExecutionEngine/RTDyldMemoryManager.h" |
| #include "llvm/Support/Memory.h" |
| #include <cstdint> |
| #include <string> |
| #include <system_error> |
| |
| 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 { |
| public: |
| /// This enum describes the various reasons to allocate pages from |
| /// allocateMappedMemory. |
| enum class AllocationPurpose { |
| Code, |
| ROData, |
| RWData, |
| }; |
| |
| /// Implementations of this interface are used by SectionMemoryManager to |
| /// request pages from the operating system. |
| class MemoryMapper { |
| public: |
| /// This method attempts to allocate \p NumBytes bytes of virtual memory for |
| /// \p Purpose. \p NearBlock may point to an existing allocation, in which |
| /// case an attempt is made to allocate more memory near the existing block. |
| /// The actual allocated address is not guaranteed to be near the requested |
| /// address. \p Flags is used to set the initial protection flags for the |
| /// block of the memory. \p EC [out] returns an object describing any error |
| /// that occurs. |
| /// |
| /// This method may allocate more than the number of bytes requested. The |
| /// actual number of bytes allocated is indicated in the returned |
| /// MemoryBlock. |
| /// |
| /// The start of the allocated block must be aligned with the system |
| /// allocation granularity (64K on Windows, page size on Linux). If the |
| /// address following \p NearBlock is not so aligned, it will be rounded up |
| /// to the next allocation granularity boundary. |
| /// |
| /// \r a non-null MemoryBlock if the function was successful, otherwise a |
| /// null MemoryBlock with \p EC describing the error. |
| virtual sys::MemoryBlock |
| allocateMappedMemory(AllocationPurpose Purpose, size_t NumBytes, |
| const sys::MemoryBlock *const NearBlock, |
| unsigned Flags, std::error_code &EC) = 0; |
| |
| /// This method sets the protection flags for a block of memory to the state |
| /// specified by \p Flags. The behavior is not specified if the memory was |
| /// not allocated using the allocateMappedMemory method. |
| /// \p Block describes the memory block to be protected. |
| /// \p Flags specifies the new protection state to be assigned to the block. |
| /// |
| /// If \p Flags is MF_WRITE, the actual behavior varies with the operating |
| /// system (i.e. MF_READ | MF_WRITE on Windows) and the target architecture |
| /// (i.e. MF_WRITE -> MF_READ | MF_WRITE on i386). |
| /// |
| /// \r error_success if the function was successful, or an error_code |
| /// describing the failure if an error occurred. |
| virtual std::error_code protectMappedMemory(const sys::MemoryBlock &Block, |
| unsigned Flags) = 0; |
| |
| /// This method releases a block of memory that was allocated with the |
| /// allocateMappedMemory method. It should not be used to release any memory |
| /// block allocated any other way. |
| /// \p Block describes the memory to be released. |
| /// |
| /// \r error_success if the function was successful, or an error_code |
| /// describing the failure if an error occurred. |
| virtual std::error_code releaseMappedMemory(sys::MemoryBlock &M) = 0; |
| |
| virtual ~MemoryMapper(); |
| }; |
| |
| /// Creates a SectionMemoryManager instance with \p MM as the associated |
| /// memory mapper. If \p MM is nullptr then a default memory mapper is used |
| /// that directly calls into the operating system. |
| SectionMemoryManager(MemoryMapper *MM = nullptr); |
| SectionMemoryManager(const SectionMemoryManager &) = delete; |
| void operator=(const SectionMemoryManager &) = delete; |
| ~SectionMemoryManager() override; |
| |
| /// 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; |
| |
| /// 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; |
| |
| /// 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; |
| |
| /// 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(AllocationPurpose Purpose, uintptr_t Size, |
| unsigned Alignment); |
| |
| std::error_code applyMemoryGroupPermissions(MemoryGroup &MemGroup, |
| unsigned Permissions); |
| |
| void anchor() override; |
| |
| MemoryGroup CodeMem; |
| MemoryGroup RWDataMem; |
| MemoryGroup RODataMem; |
| MemoryMapper &MMapper; |
| }; |
| |
| } // end namespace llvm |
| |
| #endif // LLVM_EXECUTION_ENGINE_SECTION_MEMORY_MANAGER_H |