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118 lines
3.5 KiB
C++
118 lines
3.5 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <AK/Bitmap.h>
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#include <AK/NonnullRefPtr.h>
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#include <AK/RefPtr.h>
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#include <Kernel/Assertions.h>
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#include <Kernel/VM/PhysicalPage.h>
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#include <Kernel/VM/PhysicalRegion.h>
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namespace Kernel {
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NonnullRefPtr<PhysicalRegion> PhysicalRegion::create(PhysicalAddress lower, PhysicalAddress upper)
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{
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return adopt(*new PhysicalRegion(lower, upper));
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}
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PhysicalRegion::PhysicalRegion(PhysicalAddress lower, PhysicalAddress upper)
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: m_lower(lower)
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, m_upper(upper)
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, m_bitmap(Bitmap::create())
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{
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}
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void PhysicalRegion::expand(PhysicalAddress lower, PhysicalAddress upper)
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{
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ASSERT(!m_pages);
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m_lower = lower;
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m_upper = upper;
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}
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unsigned PhysicalRegion::finalize_capacity()
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{
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ASSERT(!m_pages);
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m_pages = (m_upper.get() - m_lower.get()) / PAGE_SIZE;
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m_bitmap.grow(m_pages, false);
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return size();
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}
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RefPtr<PhysicalPage> PhysicalRegion::take_free_page(bool supervisor)
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{
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ASSERT(m_pages);
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if (m_used == m_pages)
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return nullptr;
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// search from the last page we allocated
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for (unsigned page = m_last; page < m_pages; page++) {
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if (!m_bitmap.get(page)) {
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m_bitmap.set(page, true);
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m_used++;
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m_last = page + 1;
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return PhysicalPage::create(m_lower.offset(page * PAGE_SIZE), supervisor);
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}
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}
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// wrap back around to the start in case we missed something
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for (unsigned page = 0; page < m_last; page++) {
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if (!m_bitmap.get(page)) {
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m_bitmap.set(page, true);
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m_used++;
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m_last = page + 1;
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return PhysicalPage::create(m_lower.offset(page * PAGE_SIZE), supervisor);
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}
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}
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ASSERT_NOT_REACHED();
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return nullptr;
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}
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void PhysicalRegion::return_page_at(PhysicalAddress addr)
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{
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ASSERT(m_pages);
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if (m_used == 0) {
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ASSERT_NOT_REACHED();
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}
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ptrdiff_t local_offset = addr.get() - m_lower.get();
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ASSERT(local_offset >= 0);
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ASSERT((uintptr_t)local_offset < (uintptr_t)(m_pages * PAGE_SIZE));
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auto page = (uintptr_t)local_offset / PAGE_SIZE;
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if (page < m_last)
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m_last = page;
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m_bitmap.set(page, false);
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m_used--;
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}
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}
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