1 //===- SectionMemoryManager.cpp - Memory manager for MCJIT/RtDyld *- C++ -*-==//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the section-based memory manager used by the MCJIT
11 // execution engine and RuntimeDyld
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/Config/config.h"
16 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
17 #include "llvm/Support/MathExtras.h"
18
19 namespace llvm {
20
allocateDataSection(uintptr_t Size,unsigned Alignment,unsigned SectionID,bool IsReadOnly)21 uint8_t *SectionMemoryManager::allocateDataSection(uintptr_t Size,
22 unsigned Alignment,
23 unsigned SectionID,
24 bool IsReadOnly) {
25 if (IsReadOnly)
26 return allocateSection(RODataMem, Size, Alignment);
27 return allocateSection(RWDataMem, Size, Alignment);
28 }
29
allocateCodeSection(uintptr_t Size,unsigned Alignment,unsigned SectionID)30 uint8_t *SectionMemoryManager::allocateCodeSection(uintptr_t Size,
31 unsigned Alignment,
32 unsigned SectionID) {
33 return allocateSection(CodeMem, Size, Alignment);
34 }
35
allocateSection(MemoryGroup & MemGroup,uintptr_t Size,unsigned Alignment)36 uint8_t *SectionMemoryManager::allocateSection(MemoryGroup &MemGroup,
37 uintptr_t Size,
38 unsigned Alignment) {
39 if (!Alignment)
40 Alignment = 16;
41
42 assert(!(Alignment & (Alignment - 1)) && "Alignment must be a power of two.");
43
44 uintptr_t RequiredSize = Alignment * ((Size + Alignment - 1)/Alignment + 1);
45 uintptr_t Addr = 0;
46
47 // Look in the list of free memory regions and use a block there if one
48 // is available.
49 for (int i = 0, e = MemGroup.FreeMem.size(); i != e; ++i) {
50 sys::MemoryBlock &MB = MemGroup.FreeMem[i];
51 if (MB.size() >= RequiredSize) {
52 Addr = (uintptr_t)MB.base();
53 uintptr_t EndOfBlock = Addr + MB.size();
54 // Align the address.
55 Addr = (Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1);
56 // Store cutted free memory block.
57 MemGroup.FreeMem[i] = sys::MemoryBlock((void*)(Addr + Size),
58 EndOfBlock - Addr - Size);
59 return (uint8_t*)Addr;
60 }
61 }
62
63 // No pre-allocated free block was large enough. Allocate a new memory region.
64 // Note that all sections get allocated as read-write. The permissions will
65 // be updated later based on memory group.
66 //
67 // FIXME: It would be useful to define a default allocation size (or add
68 // it as a constructor parameter) to minimize the number of allocations.
69 //
70 // FIXME: Initialize the Near member for each memory group to avoid
71 // interleaving.
72 error_code ec;
73 sys::MemoryBlock MB = sys::Memory::allocateMappedMemory(RequiredSize,
74 &MemGroup.Near,
75 sys::Memory::MF_READ |
76 sys::Memory::MF_WRITE,
77 ec);
78 if (ec) {
79 // FIXME: Add error propogation to the interface.
80 return NULL;
81 }
82
83 // Save this address as the basis for our next request
84 MemGroup.Near = MB;
85
86 MemGroup.AllocatedMem.push_back(MB);
87 Addr = (uintptr_t)MB.base();
88 uintptr_t EndOfBlock = Addr + MB.size();
89
90 // Align the address.
91 Addr = (Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1);
92
93 // The allocateMappedMemory may allocate much more memory than we need. In
94 // this case, we store the unused memory as a free memory block.
95 unsigned FreeSize = EndOfBlock-Addr-Size;
96 if (FreeSize > 16)
97 MemGroup.FreeMem.push_back(sys::MemoryBlock((void*)(Addr + Size), FreeSize));
98
99 // Return aligned address
100 return (uint8_t*)Addr;
101 }
102
finalizeMemory(std::string * ErrMsg)103 bool SectionMemoryManager::finalizeMemory(std::string *ErrMsg)
104 {
105 // FIXME: Should in-progress permissions be reverted if an error occurs?
106 error_code ec;
107
108 // Make code memory executable.
109 ec = applyMemoryGroupPermissions(CodeMem,
110 sys::Memory::MF_READ | sys::Memory::MF_EXEC);
111 if (ec) {
112 if (ErrMsg) {
113 *ErrMsg = ec.message();
114 }
115 return true;
116 }
117
118 // Make read-only data memory read-only.
119 ec = applyMemoryGroupPermissions(RODataMem,
120 sys::Memory::MF_READ | sys::Memory::MF_EXEC);
121 if (ec) {
122 if (ErrMsg) {
123 *ErrMsg = ec.message();
124 }
125 return true;
126 }
127
128 // Read-write data memory already has the correct permissions
129
130 // Some platforms with separate data cache and instruction cache require
131 // explicit cache flush, otherwise JIT code manipulations (like resolved
132 // relocations) will get to the data cache but not to the instruction cache.
133 invalidateInstructionCache();
134
135 return false;
136 }
137
applyMemoryGroupPermissions(MemoryGroup & MemGroup,unsigned Permissions)138 error_code SectionMemoryManager::applyMemoryGroupPermissions(MemoryGroup &MemGroup,
139 unsigned Permissions) {
140
141 for (int i = 0, e = MemGroup.AllocatedMem.size(); i != e; ++i) {
142 error_code ec;
143 ec = sys::Memory::protectMappedMemory(MemGroup.AllocatedMem[i],
144 Permissions);
145 if (ec) {
146 return ec;
147 }
148 }
149
150 return error_code::success();
151 }
152
invalidateInstructionCache()153 void SectionMemoryManager::invalidateInstructionCache() {
154 for (int i = 0, e = CodeMem.AllocatedMem.size(); i != e; ++i)
155 sys::Memory::InvalidateInstructionCache(CodeMem.AllocatedMem[i].base(),
156 CodeMem.AllocatedMem[i].size());
157 }
158
~SectionMemoryManager()159 SectionMemoryManager::~SectionMemoryManager() {
160 for (unsigned i = 0, e = CodeMem.AllocatedMem.size(); i != e; ++i)
161 sys::Memory::releaseMappedMemory(CodeMem.AllocatedMem[i]);
162 for (unsigned i = 0, e = RWDataMem.AllocatedMem.size(); i != e; ++i)
163 sys::Memory::releaseMappedMemory(RWDataMem.AllocatedMem[i]);
164 for (unsigned i = 0, e = RODataMem.AllocatedMem.size(); i != e; ++i)
165 sys::Memory::releaseMappedMemory(RODataMem.AllocatedMem[i]);
166 }
167
168 } // namespace llvm
169
170