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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/NonnullRefPtr.h>
#include <AK/RefPtr.h>
#include <Kernel/Assertions.h>
#include <Kernel/Random.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/VM/PhysicalRegion.h>
#include <Kernel/VM/PhysicalZone.h>
namespace Kernel {
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)
{
}
void PhysicalRegion::initialize_zones()
{
size_t remaining_pages = m_pages;
auto base_address = m_lower;
auto make_zones = [&](size_t zone_size) {
while (remaining_pages >= zone_size) {
m_zones.append(make<PhysicalZone>(base_address, zone_size));
dmesgln(" * Zone {:016x}-{:016x} ({} bytes)", base_address.get(), base_address.get() + zone_size * PAGE_SIZE - 1, zone_size * PAGE_SIZE);
base_address = base_address.offset(zone_size * PAGE_SIZE);
remaining_pages -= zone_size;
}
};
make_zones(4096);
make_zones(256);
}
unsigned PhysicalRegion::finalize_capacity()
{
VERIFY(!m_pages);
m_pages = (m_upper.get() - m_lower.get()) / PAGE_SIZE;
return 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);
// TODO: find a more elegant way to re-init the existing region
m_pages = 0;
finalize_capacity();
auto taken_region = try_create(taken_lower, taken_upper);
if (!taken_region)
return {};
taken_region->finalize_capacity();
return taken_region;
}
NonnullRefPtrVector<PhysicalPage> PhysicalRegion::take_contiguous_free_pages(size_t count)
{
auto rounded_page_count = next_power_of_two(count);
auto order = __builtin_ctz(rounded_page_count);
Optional<PhysicalAddress> page_base;
for (auto& zone : m_zones) {
page_base = zone.allocate_block(order);
if (page_base.has_value())
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()
{
for (auto& zone : m_zones) {
auto page = zone.allocate_block(0);
if (page.has_value())
return PhysicalPage::create(page.value());
}
dbgln("PhysicalRegion::take_free_page: No free physical pages");
return nullptr;
}
void PhysicalRegion::return_page(PhysicalAddress paddr)
{
for (auto& zone : m_zones) {
if (zone.contains(paddr)) {
zone.deallocate_block(paddr, 0);
return;
}
}
VERIFY_NOT_REACHED();
}
}
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