SectionMemoryManager.cpp revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f
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 19namespace llvm { 20 21uint8_t *SectionMemoryManager::allocateDataSection(uintptr_t Size, 22 unsigned Alignment, 23 unsigned SectionID, 24 StringRef SectionName, 25 bool IsReadOnly) { 26 if (IsReadOnly) 27 return allocateSection(RODataMem, Size, Alignment); 28 return allocateSection(RWDataMem, Size, Alignment); 29} 30 31uint8_t *SectionMemoryManager::allocateCodeSection(uintptr_t Size, 32 unsigned Alignment, 33 unsigned SectionID, 34 StringRef SectionName) { 35 return allocateSection(CodeMem, Size, Alignment); 36} 37 38uint8_t *SectionMemoryManager::allocateSection(MemoryGroup &MemGroup, 39 uintptr_t Size, 40 unsigned Alignment) { 41 if (!Alignment) 42 Alignment = 16; 43 44 assert(!(Alignment & (Alignment - 1)) && "Alignment must be a power of two."); 45 46 uintptr_t RequiredSize = Alignment * ((Size + Alignment - 1)/Alignment + 1); 47 uintptr_t Addr = 0; 48 49 // Look in the list of free memory regions and use a block there if one 50 // is available. 51 for (int i = 0, e = MemGroup.FreeMem.size(); i != e; ++i) { 52 sys::MemoryBlock &MB = MemGroup.FreeMem[i]; 53 if (MB.size() >= RequiredSize) { 54 Addr = (uintptr_t)MB.base(); 55 uintptr_t EndOfBlock = Addr + MB.size(); 56 // Align the address. 57 Addr = (Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1); 58 // Store cutted free memory block. 59 MemGroup.FreeMem[i] = sys::MemoryBlock((void*)(Addr + Size), 60 EndOfBlock - Addr - Size); 61 return (uint8_t*)Addr; 62 } 63 } 64 65 // No pre-allocated free block was large enough. Allocate a new memory region. 66 // Note that all sections get allocated as read-write. The permissions will 67 // be updated later based on memory group. 68 // 69 // FIXME: It would be useful to define a default allocation size (or add 70 // it as a constructor parameter) to minimize the number of allocations. 71 // 72 // FIXME: Initialize the Near member for each memory group to avoid 73 // interleaving. 74 error_code ec; 75 sys::MemoryBlock MB = sys::Memory::allocateMappedMemory(RequiredSize, 76 &MemGroup.Near, 77 sys::Memory::MF_READ | 78 sys::Memory::MF_WRITE, 79 ec); 80 if (ec) { 81 // FIXME: Add error propagation to the interface. 82 return nullptr; 83 } 84 85 // Save this address as the basis for our next request 86 MemGroup.Near = MB; 87 88 MemGroup.AllocatedMem.push_back(MB); 89 Addr = (uintptr_t)MB.base(); 90 uintptr_t EndOfBlock = Addr + MB.size(); 91 92 // Align the address. 93 Addr = (Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1); 94 95 // The allocateMappedMemory may allocate much more memory than we need. In 96 // this case, we store the unused memory as a free memory block. 97 unsigned FreeSize = EndOfBlock-Addr-Size; 98 if (FreeSize > 16) 99 MemGroup.FreeMem.push_back(sys::MemoryBlock((void*)(Addr + Size), FreeSize)); 100 101 // Return aligned address 102 return (uint8_t*)Addr; 103} 104 105bool SectionMemoryManager::finalizeMemory(std::string *ErrMsg) 106{ 107 // FIXME: Should in-progress permissions be reverted if an error occurs? 108 error_code ec; 109 110 // Don't allow free memory blocks to be used after setting protection flags. 111 CodeMem.FreeMem.clear(); 112 113 // Make code memory executable. 114 ec = applyMemoryGroupPermissions(CodeMem, 115 sys::Memory::MF_READ | sys::Memory::MF_EXEC); 116 if (ec) { 117 if (ErrMsg) { 118 *ErrMsg = ec.message(); 119 } 120 return true; 121 } 122 123 // Don't allow free memory blocks to be used after setting protection flags. 124 RODataMem.FreeMem.clear(); 125 126 // Make read-only data memory read-only. 127 ec = applyMemoryGroupPermissions(RODataMem, 128 sys::Memory::MF_READ | sys::Memory::MF_EXEC); 129 if (ec) { 130 if (ErrMsg) { 131 *ErrMsg = ec.message(); 132 } 133 return true; 134 } 135 136 // Read-write data memory already has the correct permissions 137 138 // Some platforms with separate data cache and instruction cache require 139 // explicit cache flush, otherwise JIT code manipulations (like resolved 140 // relocations) will get to the data cache but not to the instruction cache. 141 invalidateInstructionCache(); 142 143 return false; 144} 145 146error_code SectionMemoryManager::applyMemoryGroupPermissions(MemoryGroup &MemGroup, 147 unsigned Permissions) { 148 149 for (int i = 0, e = MemGroup.AllocatedMem.size(); i != e; ++i) { 150 error_code ec; 151 ec = sys::Memory::protectMappedMemory(MemGroup.AllocatedMem[i], 152 Permissions); 153 if (ec) { 154 return ec; 155 } 156 } 157 158 return error_code::success(); 159} 160 161void SectionMemoryManager::invalidateInstructionCache() { 162 for (int i = 0, e = CodeMem.AllocatedMem.size(); i != e; ++i) 163 sys::Memory::InvalidateInstructionCache(CodeMem.AllocatedMem[i].base(), 164 CodeMem.AllocatedMem[i].size()); 165} 166 167SectionMemoryManager::~SectionMemoryManager() { 168 for (unsigned i = 0, e = CodeMem.AllocatedMem.size(); i != e; ++i) 169 sys::Memory::releaseMappedMemory(CodeMem.AllocatedMem[i]); 170 for (unsigned i = 0, e = RWDataMem.AllocatedMem.size(); i != e; ++i) 171 sys::Memory::releaseMappedMemory(RWDataMem.AllocatedMem[i]); 172 for (unsigned i = 0, e = RODataMem.AllocatedMem.size(); i != e; ++i) 173 sys::Memory::releaseMappedMemory(RODataMem.AllocatedMem[i]); 174} 175 176} // namespace llvm 177 178