| /* |
| * Copyright (C) 2019 Apple Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
| * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #pragma once |
| |
| #include "IsoPage.h" |
| #include "StdLibExtras.h" |
| #include "VMAllocate.h" |
| |
| namespace bmalloc { |
| |
| // IsoSharedPage never becomes empty state again after we allocate some cells from IsoSharedPage. This makes IsoSharedPage management super simple. |
| // This is because empty IsoSharedPage is still split into various different objects that should keep some part of virtual memory region dedicated. |
| // We cannot set up bump allocation for such a page. Not freeing IsoSharedPages are OK since IsoSharedPage is only used for the lower tier of IsoHeap. |
| template<typename Config, typename Type> |
| void IsoSharedPage::free(const std::lock_guard<Mutex>&, api::IsoHeap<Type>& handle, void* ptr) |
| { |
| auto& heapImpl = handle.impl(); |
| uint8_t index = *indexSlotFor<Config>(ptr) & IsoHeapImplBase::maxAllocationFromSharedMask; |
| // IsoDeallocator::deallocate is called from delete operator. This is dispatched by vtable if virtual destructor exists. |
| // If vptr is replaced to the other vptr, we may accidentally chain this pointer to the incorrect HeapImplBase, which totally breaks the IsoHeap's goal. |
| // To harden that, we validate that this pointer is actually allocated for a specific HeapImplBase here by checking whether this pointer is listed in HeapImplBase's shared cells. |
| RELEASE_BASSERT(heapImpl.m_sharedCells[index] == ptr); |
| heapImpl.m_availableShared |= (1U << index); |
| } |
| |
| inline VariadicBumpAllocator IsoSharedPage::startAllocating() |
| { |
| static constexpr bool verbose = false; |
| |
| if (verbose) { |
| fprintf(stderr, "%p: starting shared allocation.\n", this); |
| fprintf(stderr, "%p: preparing to shared bump.\n", this); |
| } |
| |
| char* payloadEnd = reinterpret_cast<char*>(this) + IsoSharedPage::pageSize; |
| unsigned remaining = static_cast<unsigned>(roundDownToMultipleOf<alignmentForIsoSharedAllocation>(static_cast<uintptr_t>(IsoSharedPage::pageSize - sizeof(IsoSharedPage)))); |
| |
| return VariadicBumpAllocator(payloadEnd, remaining); |
| } |
| |
| inline void IsoSharedPage::stopAllocating() |
| { |
| static constexpr bool verbose = false; |
| |
| if (verbose) |
| fprintf(stderr, "%p: stopping shared allocation.\n", this); |
| } |
| |
| } // namespace bmalloc |
| |