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Diffstat (limited to 'lib/ExecutionEngine/SectionMemoryManager.cpp')
| -rw-r--r-- | lib/ExecutionEngine/SectionMemoryManager.cpp | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/lib/ExecutionEngine/SectionMemoryManager.cpp b/lib/ExecutionEngine/SectionMemoryManager.cpp new file mode 100644 index 0000000..5986084 --- /dev/null +++ b/lib/ExecutionEngine/SectionMemoryManager.cpp @@ -0,0 +1,178 @@ +//===- SectionMemoryManager.cpp - Memory manager for MCJIT/RtDyld *- C++ -*-==// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements the section-based memory manager used by the MCJIT +// execution engine and RuntimeDyld +// +//===----------------------------------------------------------------------===// + +#include "llvm/Config/config.h" +#include "llvm/ExecutionEngine/SectionMemoryManager.h" +#include "llvm/Support/MathExtras.h" + +namespace llvm { + +uint8_t *SectionMemoryManager::allocateDataSection(uintptr_t Size, + unsigned Alignment, + unsigned SectionID, + StringRef SectionName, + bool IsReadOnly) { + if (IsReadOnly) + return allocateSection(RODataMem, Size, Alignment); + return allocateSection(RWDataMem, Size, Alignment); +} + +uint8_t *SectionMemoryManager::allocateCodeSection(uintptr_t Size, + unsigned Alignment, + unsigned SectionID, + StringRef SectionName) { + return allocateSection(CodeMem, Size, Alignment); +} + +uint8_t *SectionMemoryManager::allocateSection(MemoryGroup &MemGroup, + uintptr_t Size, + unsigned Alignment) { + if (!Alignment) + Alignment = 16; + + assert(!(Alignment & (Alignment - 1)) && "Alignment must be a power of two."); + + uintptr_t RequiredSize = Alignment * ((Size + Alignment - 1)/Alignment + 1); + uintptr_t Addr = 0; + + // Look in the list of free memory regions and use a block there if one + // is available. + for (int i = 0, e = MemGroup.FreeMem.size(); i != e; ++i) { + sys::MemoryBlock &MB = MemGroup.FreeMem[i]; + if (MB.size() >= RequiredSize) { + Addr = (uintptr_t)MB.base(); + uintptr_t EndOfBlock = Addr + MB.size(); + // Align the address. + Addr = (Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1); + // Store cutted free memory block. + MemGroup.FreeMem[i] = sys::MemoryBlock((void*)(Addr + Size), + EndOfBlock - Addr - Size); + return (uint8_t*)Addr; + } + } + + // No pre-allocated free block was large enough. Allocate a new memory region. + // Note that all sections get allocated as read-write. The permissions will + // be updated later based on memory group. + // + // FIXME: It would be useful to define a default allocation size (or add + // it as a constructor parameter) to minimize the number of allocations. + // + // FIXME: Initialize the Near member for each memory group to avoid + // interleaving. + std::error_code ec; + sys::MemoryBlock MB = sys::Memory::allocateMappedMemory(RequiredSize, + &MemGroup.Near, + sys::Memory::MF_READ | + sys::Memory::MF_WRITE, + ec); + if (ec) { + // FIXME: Add error propagation to the interface. + return nullptr; + } + + // Save this address as the basis for our next request + MemGroup.Near = MB; + + MemGroup.AllocatedMem.push_back(MB); + Addr = (uintptr_t)MB.base(); + uintptr_t EndOfBlock = Addr + MB.size(); + + // Align the address. + Addr = (Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1); + + // The allocateMappedMemory may allocate much more memory than we need. In + // this case, we store the unused memory as a free memory block. + unsigned FreeSize = EndOfBlock-Addr-Size; + if (FreeSize > 16) + MemGroup.FreeMem.push_back(sys::MemoryBlock((void*)(Addr + Size), FreeSize)); + + // Return aligned address + return (uint8_t*)Addr; +} + +bool SectionMemoryManager::finalizeMemory(std::string *ErrMsg) +{ + // FIXME: Should in-progress permissions be reverted if an error occurs? + std::error_code ec; + + // Don't allow free memory blocks to be used after setting protection flags. + CodeMem.FreeMem.clear(); + + // Make code memory executable. + ec = applyMemoryGroupPermissions(CodeMem, + sys::Memory::MF_READ | sys::Memory::MF_EXEC); + if (ec) { + if (ErrMsg) { + *ErrMsg = ec.message(); + } + return true; + } + + // Don't allow free memory blocks to be used after setting protection flags. + RODataMem.FreeMem.clear(); + + // Make read-only data memory read-only. + ec = applyMemoryGroupPermissions(RODataMem, + sys::Memory::MF_READ | sys::Memory::MF_EXEC); + if (ec) { + if (ErrMsg) { + *ErrMsg = ec.message(); + } + return true; + } + + // Read-write data memory already has the correct permissions + + // 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. + invalidateInstructionCache(); + + return false; +} + +std::error_code +SectionMemoryManager::applyMemoryGroupPermissions(MemoryGroup &MemGroup, + unsigned Permissions) { + + for (int i = 0, e = MemGroup.AllocatedMem.size(); i != e; ++i) { + std::error_code ec; + ec = + sys::Memory::protectMappedMemory(MemGroup.AllocatedMem[i], Permissions); + if (ec) { + return ec; + } + } + + return std::error_code(); +} + +void SectionMemoryManager::invalidateInstructionCache() { + for (int i = 0, e = CodeMem.AllocatedMem.size(); i != e; ++i) + sys::Memory::InvalidateInstructionCache(CodeMem.AllocatedMem[i].base(), + CodeMem.AllocatedMem[i].size()); +} + +SectionMemoryManager::~SectionMemoryManager() { + for (unsigned i = 0, e = CodeMem.AllocatedMem.size(); i != e; ++i) + sys::Memory::releaseMappedMemory(CodeMem.AllocatedMem[i]); + for (unsigned i = 0, e = RWDataMem.AllocatedMem.size(); i != e; ++i) + sys::Memory::releaseMappedMemory(RWDataMem.AllocatedMem[i]); + for (unsigned i = 0, e = RODataMem.AllocatedMem.size(); i != e; ++i) + sys::Memory::releaseMappedMemory(RODataMem.AllocatedMem[i]); +} + +} // namespace llvm + |