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/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Assertions.h>
#include <AK/NonnullOwnPtr.h>
#include <AK/Platform.h>
#include <LibJS/Heap/Heap.h>
#include <LibJS/Heap/HeapBlock.h>
#include <stdio.h>
#include <sys/mman.h>
#ifdef HAS_ADDRESS_SANITIZER
# include <sanitizer/asan_interface.h>
#endif
namespace JS {
NonnullOwnPtr<HeapBlock> HeapBlock::create_with_cell_size(Heap& heap, size_t cell_size)
{
#ifdef AK_OS_SERENITY
char name[64];
snprintf(name, sizeof(name), "LibJS: HeapBlock(%zu)", cell_size);
#else
char const* name = nullptr;
#endif
auto* block = static_cast<HeapBlock*>(heap.block_allocator().allocate_block(name));
new (block) HeapBlock(heap, cell_size);
return NonnullOwnPtr<HeapBlock>(NonnullOwnPtr<HeapBlock>::Adopt, *block);
}
HeapBlock::HeapBlock(Heap& heap, size_t cell_size)
: m_heap(heap)
, m_cell_size(cell_size)
{
VERIFY(cell_size >= sizeof(FreelistEntry));
ASAN_POISON_MEMORY_REGION(m_storage, block_size - sizeof(HeapBlock));
}
void HeapBlock::deallocate(Cell* cell)
{
VERIFY(is_valid_cell_pointer(cell));
VERIFY(!m_freelist || is_valid_cell_pointer(m_freelist));
VERIFY(cell->state() == Cell::State::Live);
VERIFY(!cell->is_marked());
cell->~Cell();
auto* freelist_entry = new (cell) FreelistEntry();
freelist_entry->set_state(Cell::State::Dead);
freelist_entry->next = m_freelist;
m_freelist = freelist_entry;
#ifdef HAS_ADDRESS_SANITIZER
auto dword_after_freelist = round_up_to_power_of_two(reinterpret_cast<uintptr_t>(freelist_entry) + sizeof(FreelistEntry), 8);
VERIFY((dword_after_freelist - reinterpret_cast<uintptr_t>(freelist_entry)) <= m_cell_size);
VERIFY(m_cell_size >= sizeof(FreelistEntry));
// We can't poision the cell tracking data, nor the FreeListEntry's vtable or next pointer
// This means there's sizeof(FreelistEntry) data at the front of each cell that is always read/write
// On x86_64, this ends up being 24 bytes due to the size of the FreeListEntry's vtable, while on x86, it's only 12 bytes.
ASAN_POISON_MEMORY_REGION(reinterpret_cast<void*>(dword_after_freelist), m_cell_size - sizeof(FreelistEntry));
#endif
}
}
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