1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
|
#pragma once
#ifdef __GNUC__
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-parameter"
#endif
//===- 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/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
#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif
|
