[yaml2obj/obj2yaml] - Add support for .stack_sizes sections.
[llvm-complete.git] / include / llvm / ExecutionEngine / SectionMemoryManager.h
blobd7316425da2f6556fd02b653baaa00664c65f54d
1 //===- SectionMemoryManager.h - Memory manager for MCJIT/RtDyld -*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains the declaration of a section-based memory manager used by
10 // the MCJIT execution engine and RuntimeDyld.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_EXECUTIONENGINE_SECTIONMEMORYMANAGER_H
15 #define LLVM_EXECUTIONENGINE_SECTIONMEMORYMANAGER_H
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/ADT/StringRef.h"
19 #include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
20 #include "llvm/Support/Memory.h"
21 #include <cstdint>
22 #include <string>
23 #include <system_error>
25 namespace llvm {
27 /// This is a simple memory manager which implements the methods called by
28 /// the RuntimeDyld class to allocate memory for section-based loading of
29 /// objects, usually those generated by the MCJIT execution engine.
30 ///
31 /// This memory manager allocates all section memory as read-write. The
32 /// RuntimeDyld will copy JITed section memory into these allocated blocks
33 /// and perform any necessary linking and relocations.
34 ///
35 /// Any client using this memory manager MUST ensure that section-specific
36 /// page permissions have been applied before attempting to execute functions
37 /// in the JITed object. Permissions can be applied either by calling
38 /// MCJIT::finalizeObject or by calling SectionMemoryManager::finalizeMemory
39 /// directly. Clients of MCJIT should call MCJIT::finalizeObject.
40 class SectionMemoryManager : public RTDyldMemoryManager {
41 public:
42 /// This enum describes the various reasons to allocate pages from
43 /// allocateMappedMemory.
44 enum class AllocationPurpose {
45 Code,
46 ROData,
47 RWData,
50 /// Implementations of this interface are used by SectionMemoryManager to
51 /// request pages from the operating system.
52 class MemoryMapper {
53 public:
54 /// This method attempts to allocate \p NumBytes bytes of virtual memory for
55 /// \p Purpose. \p NearBlock may point to an existing allocation, in which
56 /// case an attempt is made to allocate more memory near the existing block.
57 /// The actual allocated address is not guaranteed to be near the requested
58 /// address. \p Flags is used to set the initial protection flags for the
59 /// block of the memory. \p EC [out] returns an object describing any error
60 /// that occurs.
61 ///
62 /// This method may allocate more than the number of bytes requested. The
63 /// actual number of bytes allocated is indicated in the returned
64 /// MemoryBlock.
65 ///
66 /// The start of the allocated block must be aligned with the system
67 /// allocation granularity (64K on Windows, page size on Linux). If the
68 /// address following \p NearBlock is not so aligned, it will be rounded up
69 /// to the next allocation granularity boundary.
70 ///
71 /// \r a non-null MemoryBlock if the function was successful, otherwise a
72 /// null MemoryBlock with \p EC describing the error.
73 virtual sys::MemoryBlock
74 allocateMappedMemory(AllocationPurpose Purpose, size_t NumBytes,
75 const sys::MemoryBlock *const NearBlock,
76 unsigned Flags, std::error_code &EC) = 0;
78 /// This method sets the protection flags for a block of memory to the state
79 /// specified by \p Flags. The behavior is not specified if the memory was
80 /// not allocated using the allocateMappedMemory method.
81 /// \p Block describes the memory block to be protected.
82 /// \p Flags specifies the new protection state to be assigned to the block.
83 ///
84 /// If \p Flags is MF_WRITE, the actual behavior varies with the operating
85 /// system (i.e. MF_READ | MF_WRITE on Windows) and the target architecture
86 /// (i.e. MF_WRITE -> MF_READ | MF_WRITE on i386).
87 ///
88 /// \r error_success if the function was successful, or an error_code
89 /// describing the failure if an error occurred.
90 virtual std::error_code protectMappedMemory(const sys::MemoryBlock &Block,
91 unsigned Flags) = 0;
93 /// This method releases a block of memory that was allocated with the
94 /// allocateMappedMemory method. It should not be used to release any memory
95 /// block allocated any other way.
96 /// \p Block describes the memory to be released.
97 ///
98 /// \r error_success if the function was successful, or an error_code
99 /// describing the failure if an error occurred.
100 virtual std::error_code releaseMappedMemory(sys::MemoryBlock &M) = 0;
102 virtual ~MemoryMapper();
105 /// Creates a SectionMemoryManager instance with \p MM as the associated
106 /// memory mapper. If \p MM is nullptr then a default memory mapper is used
107 /// that directly calls into the operating system.
108 SectionMemoryManager(MemoryMapper *MM = nullptr);
109 SectionMemoryManager(const SectionMemoryManager &) = delete;
110 void operator=(const SectionMemoryManager &) = delete;
111 ~SectionMemoryManager() override;
113 /// Allocates a memory block of (at least) the given size suitable for
114 /// executable code.
116 /// The value of \p Alignment must be a power of two. If \p Alignment is zero
117 /// a default alignment of 16 will be used.
118 uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
119 unsigned SectionID,
120 StringRef SectionName) override;
122 /// Allocates a memory block of (at least) the given size suitable for
123 /// executable code.
125 /// The value of \p Alignment must be a power of two. If \p Alignment is zero
126 /// a default alignment of 16 will be used.
127 uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
128 unsigned SectionID, StringRef SectionName,
129 bool isReadOnly) override;
131 /// Update section-specific memory permissions and other attributes.
133 /// This method is called when object loading is complete and section page
134 /// permissions can be applied. It is up to the memory manager implementation
135 /// to decide whether or not to act on this method. The memory manager will
136 /// typically allocate all sections as read-write and then apply specific
137 /// permissions when this method is called. Code sections cannot be executed
138 /// until this function has been called. In addition, any cache coherency
139 /// operations needed to reliably use the memory are also performed.
141 /// \returns true if an error occurred, false otherwise.
142 bool finalizeMemory(std::string *ErrMsg = nullptr) override;
144 /// Invalidate instruction cache for code sections.
146 /// Some platforms with separate data cache and instruction cache require
147 /// explicit cache flush, otherwise JIT code manipulations (like resolved
148 /// relocations) will get to the data cache but not to the instruction cache.
150 /// This method is called from finalizeMemory.
151 virtual void invalidateInstructionCache();
153 private:
154 struct FreeMemBlock {
155 // The actual block of free memory
156 sys::MemoryBlock Free;
157 // If there is a pending allocation from the same reservation right before
158 // this block, store it's index in PendingMem, to be able to update the
159 // pending region if part of this block is allocated, rather than having to
160 // create a new one
161 unsigned PendingPrefixIndex;
164 struct MemoryGroup {
165 // PendingMem contains all blocks of memory (subblocks of AllocatedMem)
166 // which have not yet had their permissions applied, but have been given
167 // out to the user. FreeMem contains all block of memory, which have
168 // neither had their permissions applied, nor been given out to the user.
169 SmallVector<sys::MemoryBlock, 16> PendingMem;
170 SmallVector<FreeMemBlock, 16> FreeMem;
172 // All memory blocks that have been requested from the system
173 SmallVector<sys::MemoryBlock, 16> AllocatedMem;
175 sys::MemoryBlock Near;
178 uint8_t *allocateSection(AllocationPurpose Purpose, uintptr_t Size,
179 unsigned Alignment);
181 std::error_code applyMemoryGroupPermissions(MemoryGroup &MemGroup,
182 unsigned Permissions);
184 void anchor() override;
186 MemoryGroup CodeMem;
187 MemoryGroup RWDataMem;
188 MemoryGroup RODataMem;
189 MemoryMapper &MMapper;
192 } // end namespace llvm
194 #endif // LLVM_EXECUTION_ENGINE_SECTION_MEMORY_MANAGER_H