716e5f72f2
Before this change, we'd use the system page size as the HeapBlock size. This caused it to vary on different platforms, going as low as 4 KiB on most Linux systems. To make this work, we now use posix_memalign() to ensure we get size-aligned allocations on every platform. Also nice: HeapBlock::BLOCK_SIZE is now a constant.
94 lines
2.5 KiB
C++
94 lines
2.5 KiB
C++
/*
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* Copyright (c) 2021-2023, Andreas Kling <andreas@ladybird.org>
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* Copyright (c) 2025, Ryszard Goc <ryszardgoc@gmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Assertions.h>
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#include <AK/Format.h>
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#include <AK/Platform.h>
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#include <AK/Random.h>
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#include <AK/Vector.h>
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#include <LibGC/BlockAllocator.h>
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#include <LibGC/HeapBlock.h>
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#include <sys/mman.h>
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#ifdef HAS_ADDRESS_SANITIZER
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# include <sanitizer/asan_interface.h>
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# include <sanitizer/lsan_interface.h>
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#endif
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#if defined(AK_OS_WINDOWS)
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# include <AK/Windows.h>
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# include <memoryapi.h>
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#endif
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namespace GC {
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BlockAllocator::~BlockAllocator()
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{
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for (auto* block : m_blocks) {
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ASAN_UNPOISON_MEMORY_REGION(block, HeapBlock::BLOCK_SIZE);
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#if !defined(AK_OS_WINDOWS)
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free(block);
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#else
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if (!VirtualFree(block, 0, MEM_RELEASE)) {
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warnln("{}", Error::from_windows_error());
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VERIFY_NOT_REACHED();
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}
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#endif
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}
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}
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void* BlockAllocator::allocate_block([[maybe_unused]] char const* name)
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{
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if (!m_blocks.is_empty()) {
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// To reduce predictability, take a random block from the cache.
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size_t random_index = get_random_uniform(m_blocks.size());
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auto* block = m_blocks.unstable_take(random_index);
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ASAN_UNPOISON_MEMORY_REGION(block, HeapBlock::BLOCK_SIZE);
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LSAN_REGISTER_ROOT_REGION(block, HeapBlock::BLOCK_SIZE);
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return block;
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}
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#if !defined(AK_OS_WINDOWS)
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void* block = nullptr;
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auto rc = posix_memalign(&block, HeapBlock::BLOCK_SIZE, HeapBlock::BLOCK_SIZE);
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VERIFY(rc == 0);
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#else
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auto* block = VirtualAlloc(NULL, HeapBlock::BLOCK_SIZE, MEM_COMMIT, PAGE_READWRITE);
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VERIFY(block);
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#endif
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LSAN_REGISTER_ROOT_REGION(block, HeapBlock::BLOCK_SIZE);
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return block;
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}
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void BlockAllocator::deallocate_block(void* block)
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{
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VERIFY(block);
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#if defined(AK_OS_WINDOWS)
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DWORD ret = DiscardVirtualMemory(block, HeapBlock::BLOCK_SIZE);
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if (ret != ERROR_SUCCESS) {
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warnln("{}", Error::from_windows_error(ret));
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VERIFY_NOT_REACHED();
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}
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#elif defined(MADV_FREE)
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if (madvise(block, HeapBlock::BLOCK_SIZE, MADV_FREE) < 0) {
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perror("madvise(MADV_FREE)");
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VERIFY_NOT_REACHED();
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}
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#elif defined(MADV_DONTNEED)
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if (madvise(block, HeapBlock::BLOCK_SIZE, MADV_DONTNEED) < 0) {
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perror("madvise(MADV_DONTNEED)");
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VERIFY_NOT_REACHED();
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}
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#endif
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ASAN_POISON_MEMORY_REGION(block, HeapBlock::BLOCK_SIZE);
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LSAN_UNREGISTER_ROOT_REGION(block, HeapBlock::BLOCK_SIZE);
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m_blocks.append(block);
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}
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}
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