1 //===- SectionMemoryManager.h - Memory manager for MCJIT/RtDyld -*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the declaration of a section-based memory manager used by
11 // the MCJIT execution engine and RuntimeDyld.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_EXECUTIONENGINE_SECTIONMEMORYMANAGER_H
16 #define LLVM_EXECUTIONENGINE_SECTIONMEMORYMANAGER_H
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
20 #include "llvm/Support/ErrorHandling.h"
21 #include "llvm/Support/Memory.h"
24 /// This is a simple memory manager which implements the methods called by
25 /// the RuntimeDyld class to allocate memory for section-based loading of
26 /// objects, usually those generated by the MCJIT execution engine.
28 /// This memory manager allocates all section memory as read-write. The
29 /// RuntimeDyld will copy JITed section memory into these allocated blocks
30 /// and perform any necessary linking and relocations.
32 /// Any client using this memory manager MUST ensure that section-specific
33 /// page permissions have been applied before attempting to execute functions
34 /// in the JITed object. Permissions can be applied either by calling
35 /// MCJIT::finalizeObject or by calling SectionMemoryManager::finalizeMemory
36 /// directly. Clients of MCJIT should call MCJIT::finalizeObject.
37 class SectionMemoryManager : public RTDyldMemoryManager {
38 SectionMemoryManager(const SectionMemoryManager&) = delete;
39 void operator=(const SectionMemoryManager&) = delete;
42 SectionMemoryManager() { }
43 ~SectionMemoryManager() override;
45 /// \brief Allocates a memory block of (at least) the given size suitable for
48 /// The value of \p Alignment must be a power of two. If \p Alignment is zero
49 /// a default alignment of 16 will be used.
50 uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
52 StringRef SectionName) override;
54 /// \brief Allocates a memory block of (at least) the given size suitable for
57 /// The value of \p Alignment must be a power of two. If \p Alignment is zero
58 /// a default alignment of 16 will be used.
59 uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
60 unsigned SectionID, StringRef SectionName,
61 bool isReadOnly) override;
63 /// \brief Update section-specific memory permissions and other attributes.
65 /// This method is called when object loading is complete and section page
66 /// permissions can be applied. It is up to the memory manager implementation
67 /// to decide whether or not to act on this method. The memory manager will
68 /// typically allocate all sections as read-write and then apply specific
69 /// permissions when this method is called. Code sections cannot be executed
70 /// until this function has been called. In addition, any cache coherency
71 /// operations needed to reliably use the memory are also performed.
73 /// \returns true if an error occurred, false otherwise.
74 bool finalizeMemory(std::string *ErrMsg = nullptr) override;
76 /// \brief Invalidate instruction cache for code sections.
78 /// Some platforms with separate data cache and instruction cache require
79 /// explicit cache flush, otherwise JIT code manipulations (like resolved
80 /// relocations) will get to the data cache but not to the instruction cache.
82 /// This method is called from finalizeMemory.
83 virtual void invalidateInstructionCache();
87 // PendingMem contains all allocated memory blocks
88 // which have not yet had their permissions set. Note
89 // that this tracks memory blocks that have been given to
90 // this memory manager by the system, not those
91 // given out to the user. In particular, the memory manager
92 // will give out subblocks of these MemoryBlocks in response
93 // to user requests. We track which subblocks have not beeen
94 // given out yet in `FreeMem`.
95 SmallVector<sys::MemoryBlock, 16> PendingMem;
96 SmallVector<sys::MemoryBlock, 16> FreeMem;
98 // All allocated memory blocks that have had their permissions
99 // set (i.e. that have been finalized). Because of this, we may
100 // not give out subblocks of this memory to the user anymore,
101 // even if those subblocks have not been previously given out.
102 SmallVector<sys::MemoryBlock, 16> AllocatedMem;
104 sys::MemoryBlock Near;
107 uint8_t *allocateSection(MemoryGroup &MemGroup, uintptr_t Size,
110 std::error_code applyMemoryGroupPermissions(MemoryGroup &MemGroup,
111 unsigned Permissions);
114 MemoryGroup RWDataMem;
115 MemoryGroup RODataMem;
120 #endif // LLVM_EXECUTION_ENGINE_SECTION_MEMORY_MANAGER_H