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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER 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.
*/
#include <AK/Bitmap.h>
#include <AK/NonnullRefPtr.h>
#include <AK/RefPtr.h>
#include <Kernel/Assertions.h>
#include <Kernel/VM/PhysicalPage.h>
#include <Kernel/VM/PhysicalRegion.h>
NonnullRefPtr<PhysicalRegion> PhysicalRegion::create(PhysicalAddress lower, PhysicalAddress upper)
{
return adopt(*new PhysicalRegion(lower, upper));
}
PhysicalRegion::PhysicalRegion(PhysicalAddress lower, PhysicalAddress upper)
: m_lower(lower)
, m_upper(upper)
, m_bitmap(Bitmap::create())
{
}
void PhysicalRegion::expand(PhysicalAddress lower, PhysicalAddress upper)
{
ASSERT(!m_pages);
m_lower = lower;
m_upper = upper;
}
unsigned PhysicalRegion::finalize_capacity()
{
ASSERT(!m_pages);
m_pages = (m_upper.get() - m_lower.get()) / PAGE_SIZE;
m_bitmap.grow(m_pages, false);
return size();
}
RefPtr<PhysicalPage> PhysicalRegion::take_free_page(bool supervisor)
{
ASSERT(m_pages);
if (m_used == m_pages)
return nullptr;
// search from the last page we allocated
for (unsigned page = m_last; page < m_pages; page++) {
if (!m_bitmap.get(page)) {
m_bitmap.set(page, true);
m_used++;
m_last = page + 1;
return PhysicalPage::create(m_lower.offset(page * PAGE_SIZE), supervisor);
}
}
// wrap back around to the start in case we missed something
for (unsigned page = 0; page < m_last; page++) {
if (!m_bitmap.get(page)) {
m_bitmap.set(page, true);
m_used++;
m_last = page + 1;
return PhysicalPage::create(m_lower.offset(page * PAGE_SIZE), supervisor);
}
}
ASSERT_NOT_REACHED();
return nullptr;
}
void PhysicalRegion::return_page_at(PhysicalAddress addr)
{
ASSERT(m_pages);
if (m_used == 0) {
ASSERT_NOT_REACHED();
}
ptrdiff_t local_offset = addr.get() - m_lower.get();
ASSERT(local_offset >= 0);
ASSERT((uintptr_t)local_offset < (uintptr_t)(m_pages * PAGE_SIZE));
auto page = (uintptr_t)local_offset / PAGE_SIZE;
if (page < m_last)
m_last = page;
m_bitmap.set(page, false);
m_used--;
}
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