| //===- SectionMemoryManager.cpp - 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 implements the section-based memory manager used by the MCJIT |
| // execution engine and RuntimeDyld |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/ExecutionEngine/SectionMemoryManager.h" |
| #include "llvm/Config/config.h" |
| #include "llvm/Support/MathExtras.h" |
| #include "llvm/Support/Process.h" |
| |
| namespace llvm { |
| |
| uint8_t *SectionMemoryManager::allocateDataSection(uintptr_t Size, |
| unsigned Alignment, |
| unsigned SectionID, |
| StringRef SectionName, |
| bool IsReadOnly) { |
| if (IsReadOnly) |
| return allocateSection(SectionMemoryManager::AllocationPurpose::ROData, |
| Size, Alignment); |
| return allocateSection(SectionMemoryManager::AllocationPurpose::RWData, Size, |
| Alignment); |
| } |
| |
| uint8_t *SectionMemoryManager::allocateCodeSection(uintptr_t Size, |
| unsigned Alignment, |
| unsigned SectionID, |
| StringRef SectionName) { |
| return allocateSection(SectionMemoryManager::AllocationPurpose::Code, Size, |
| Alignment); |
| } |
| |
| uint8_t *SectionMemoryManager::allocateSection( |
| SectionMemoryManager::AllocationPurpose Purpose, 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; |
| |
| MemoryGroup &MemGroup = [&]() -> MemoryGroup & { |
| switch (Purpose) { |
| case AllocationPurpose::Code: |
| return CodeMem; |
| case AllocationPurpose::ROData: |
| return RODataMem; |
| case AllocationPurpose::RWData: |
| return RWDataMem; |
| } |
| llvm_unreachable("Unknown SectionMemoryManager::AllocationPurpose"); |
| }(); |
| |
| // Look in the list of free memory regions and use a block there if one |
| // is available. |
| for (FreeMemBlock &FreeMB : MemGroup.FreeMem) { |
| if (FreeMB.Free.allocatedSize() >= RequiredSize) { |
| Addr = (uintptr_t)FreeMB.Free.base(); |
| uintptr_t EndOfBlock = Addr + FreeMB.Free.allocatedSize(); |
| // Align the address. |
| Addr = (Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1); |
| |
| if (FreeMB.PendingPrefixIndex == (unsigned)-1) { |
| // The part of the block we're giving out to the user is now pending |
| MemGroup.PendingMem.push_back(sys::MemoryBlock((void *)Addr, Size)); |
| |
| // Remember this pending block, such that future allocations can just |
| // modify it rather than creating a new one |
| FreeMB.PendingPrefixIndex = MemGroup.PendingMem.size() - 1; |
| } else { |
| sys::MemoryBlock &PendingMB = |
| MemGroup.PendingMem[FreeMB.PendingPrefixIndex]; |
| PendingMB = sys::MemoryBlock(PendingMB.base(), |
| Addr + Size - (uintptr_t)PendingMB.base()); |
| } |
| |
| // Remember how much free space is now left in this block |
| FreeMB.Free = |
| 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 = MMapper.allocateMappedMemory( |
| Purpose, 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; |
| |
| // Copy the address to all the other groups, if they have not |
| // been initialized. |
| if (CodeMem.Near.base() == nullptr) |
| CodeMem.Near = MB; |
| if (RODataMem.Near.base() == nullptr) |
| RODataMem.Near = MB; |
| if (RWDataMem.Near.base() == nullptr) |
| RWDataMem.Near = MB; |
| |
| // Remember that we allocated this memory |
| MemGroup.AllocatedMem.push_back(MB); |
| Addr = (uintptr_t)MB.base(); |
| uintptr_t EndOfBlock = Addr + MB.allocatedSize(); |
| |
| // Align the address. |
| Addr = (Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1); |
| |
| // The part of the block we're giving out to the user is now pending |
| MemGroup.PendingMem.push_back(sys::MemoryBlock((void *)Addr, Size)); |
| |
| // 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) { |
| FreeMemBlock FreeMB; |
| FreeMB.Free = sys::MemoryBlock((void *)(Addr + Size), FreeSize); |
| FreeMB.PendingPrefixIndex = (unsigned)-1; |
| MemGroup.FreeMem.push_back(FreeMB); |
| } |
| |
| // 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; |
| |
| // Make code memory executable. |
| ec = applyMemoryGroupPermissions(CodeMem, |
| sys::Memory::MF_READ | sys::Memory::MF_EXEC); |
| if (ec) { |
| if (ErrMsg) { |
| *ErrMsg = ec.message(); |
| } |
| return true; |
| } |
| |
| // Make read-only data memory read-only. |
| ec = applyMemoryGroupPermissions(RODataMem, sys::Memory::MF_READ); |
| 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; |
| } |
| |
| static sys::MemoryBlock trimBlockToPageSize(sys::MemoryBlock M) { |
| static const size_t PageSize = sys::Process::getPageSizeEstimate(); |
| |
| size_t StartOverlap = |
| (PageSize - ((uintptr_t)M.base() % PageSize)) % PageSize; |
| |
| size_t TrimmedSize = M.allocatedSize(); |
| TrimmedSize -= StartOverlap; |
| TrimmedSize -= TrimmedSize % PageSize; |
| |
| sys::MemoryBlock Trimmed((void *)((uintptr_t)M.base() + StartOverlap), |
| TrimmedSize); |
| |
| assert(((uintptr_t)Trimmed.base() % PageSize) == 0); |
| assert((Trimmed.allocatedSize() % PageSize) == 0); |
| assert(M.base() <= Trimmed.base() && |
| Trimmed.allocatedSize() <= M.allocatedSize()); |
| |
| return Trimmed; |
| } |
| |
| std::error_code |
| SectionMemoryManager::applyMemoryGroupPermissions(MemoryGroup &MemGroup, |
| unsigned Permissions) { |
| for (sys::MemoryBlock &MB : MemGroup.PendingMem) |
| if (std::error_code EC = MMapper.protectMappedMemory(MB, Permissions)) |
| return EC; |
| |
| MemGroup.PendingMem.clear(); |
| |
| // Now go through free blocks and trim any of them that don't span the entire |
| // page because one of the pending blocks may have overlapped it. |
| for (FreeMemBlock &FreeMB : MemGroup.FreeMem) { |
| FreeMB.Free = trimBlockToPageSize(FreeMB.Free); |
| // We cleared the PendingMem list, so all these pointers are now invalid |
| FreeMB.PendingPrefixIndex = (unsigned)-1; |
| } |
| |
| // Remove all blocks which are now empty |
| erase_if(MemGroup.FreeMem, [](FreeMemBlock &FreeMB) { |
| return FreeMB.Free.allocatedSize() == 0; |
| }); |
| |
| return std::error_code(); |
| } |
| |
| void SectionMemoryManager::invalidateInstructionCache() { |
| for (sys::MemoryBlock &Block : CodeMem.PendingMem) |
| sys::Memory::InvalidateInstructionCache(Block.base(), |
| Block.allocatedSize()); |
| } |
| |
| SectionMemoryManager::~SectionMemoryManager() { |
| for (MemoryGroup *Group : {&CodeMem, &RWDataMem, &RODataMem}) { |
| for (sys::MemoryBlock &Block : Group->AllocatedMem) |
| MMapper.releaseMappedMemory(Block); |
| } |
| } |
| |
| SectionMemoryManager::MemoryMapper::~MemoryMapper() = default; |
| |
| void SectionMemoryManager::anchor() {} |
| |
| namespace { |
| // Trivial implementation of SectionMemoryManager::MemoryMapper that just calls |
| // into sys::Memory. |
| class DefaultMMapper final : public SectionMemoryManager::MemoryMapper { |
| public: |
| sys::MemoryBlock |
| allocateMappedMemory(SectionMemoryManager::AllocationPurpose Purpose, |
| size_t NumBytes, const sys::MemoryBlock *const NearBlock, |
| unsigned Flags, std::error_code &EC) override { |
| return sys::Memory::allocateMappedMemory(NumBytes, NearBlock, Flags, EC); |
| } |
| |
| std::error_code protectMappedMemory(const sys::MemoryBlock &Block, |
| unsigned Flags) override { |
| return sys::Memory::protectMappedMemory(Block, Flags); |
| } |
| |
| std::error_code releaseMappedMemory(sys::MemoryBlock &M) override { |
| return sys::Memory::releaseMappedMemory(M); |
| } |
| }; |
| |
| DefaultMMapper DefaultMMapperInstance; |
| } // namespace |
| |
| SectionMemoryManager::SectionMemoryManager(MemoryMapper *MM) |
| : MMapper(MM ? *MM : DefaultMMapperInstance) {} |
| |
| } // namespace llvm |
