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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/BuiltinWrappers.h>
#include <AK/NonnullRefPtr.h>
#include <AK/RefPtr.h>
#include <Kernel/Assertions.h>
#include <Kernel/Memory/MemoryManager.h>
#include <Kernel/Memory/PhysicalRegion.h>
#include <Kernel/Memory/PhysicalZone.h>
#include <Kernel/Random.h>
namespace Kernel::Memory {
static constexpr u32 next_power_of_two(u32 value)
{
value--;
value |= value >> 1;
value |= value >> 2;
value |= value >> 4;
value |= value >> 8;
value |= value >> 16;
value++;
return value;
}
PhysicalRegion::~PhysicalRegion()
{
}
PhysicalRegion::PhysicalRegion(PhysicalAddress lower, PhysicalAddress upper)
: m_lower(lower)
, m_upper(upper)
{
m_pages = (m_upper.get() - m_lower.get()) / PAGE_SIZE;
}
void PhysicalRegion::initialize_zones()
{
size_t remaining_pages = m_pages;
auto base_address = m_lower;
auto make_zones = [&](size_t zone_size) -> size_t {
size_t pages_per_zone = zone_size / PAGE_SIZE;
size_t zone_count = 0;
auto first_address = base_address;
while (remaining_pages >= pages_per_zone) {
m_zones.append(make<PhysicalZone>(base_address, pages_per_zone));
base_address = base_address.offset(pages_per_zone * PAGE_SIZE);
m_usable_zones.append(m_zones.last());
remaining_pages -= pages_per_zone;
++zone_count;
}
if (zone_count)
dmesgln(" * {}x PhysicalZone ({} MiB) @ {:016x}-{:016x}", zone_count, pages_per_zone / 256, first_address.get(), base_address.get() - pages_per_zone * PAGE_SIZE - 1);
return zone_count;
};
// First make 16 MiB zones (with 4096 pages each)
m_large_zones = make_zones(large_zone_size);
// Then divide any remaining space into 1 MiB zones (with 256 pages each)
make_zones(small_zone_size);
}
OwnPtr<PhysicalRegion> PhysicalRegion::try_take_pages_from_beginning(unsigned page_count)
{
VERIFY(page_count > 0);
VERIFY(page_count < m_pages);
auto taken_lower = m_lower;
auto taken_upper = taken_lower.offset((PhysicalPtr)page_count * PAGE_SIZE);
m_lower = m_lower.offset((PhysicalPtr)page_count * PAGE_SIZE);
m_pages = (m_upper.get() - m_lower.get()) / PAGE_SIZE;
return try_create(taken_lower, taken_upper);
}
NonnullRefPtrVector<PhysicalPage> PhysicalRegion::take_contiguous_free_pages(size_t count)
{
auto rounded_page_count = next_power_of_two(count);
auto order = count_trailing_zeroes(rounded_page_count);
Optional<PhysicalAddress> page_base;
for (auto& zone : m_usable_zones) {
page_base = zone.allocate_block(order);
if (page_base.has_value()) {
if (zone.is_empty()) {
// We've exhausted this zone, move it to the full zones list.
m_full_zones.append(zone);
}
break;
}
}
if (!page_base.has_value())
return {};
NonnullRefPtrVector<PhysicalPage> physical_pages;
physical_pages.ensure_capacity(count);
for (size_t i = 0; i < count; ++i)
physical_pages.append(PhysicalPage::create(page_base.value().offset(i * PAGE_SIZE)));
return physical_pages;
}
RefPtr<PhysicalPage> PhysicalRegion::take_free_page()
{
if (m_usable_zones.is_empty())
return nullptr;
auto& zone = *m_usable_zones.first();
auto page = zone.allocate_block(0);
VERIFY(page.has_value());
if (zone.is_empty()) {
// We've exhausted this zone, move it to the full zones list.
m_full_zones.append(zone);
}
return PhysicalPage::create(page.value());
}
void PhysicalRegion::return_page(PhysicalAddress paddr)
{
auto large_zone_base = lower().get();
auto small_zone_base = lower().get() + (m_large_zones * large_zone_size);
size_t zone_index;
if (paddr.get() < small_zone_base)
zone_index = (paddr.get() - large_zone_base) / large_zone_size;
else
zone_index = m_large_zones + (paddr.get() - small_zone_base) / small_zone_size;
auto& zone = m_zones[zone_index];
VERIFY(zone.contains(paddr));
zone.deallocate_block(paddr, 0);
if (m_full_zones.contains(zone))
m_usable_zones.append(zone);
}
}
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