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/*
* Copyright (c) 2022, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Format.h>
#include <Kernel/Memory/AnonymousVMObject.h>
#include <Kernel/Memory/MemoryManager.h>
#include <Kernel/Memory/RegionTree.h>
#include <Kernel/Random.h>
namespace Kernel::Memory {
RegionTree::~RegionTree()
{
delete_all_regions_assuming_they_are_unmapped();
}
void RegionTree::delete_all_regions_assuming_they_are_unmapped()
{
// FIXME: This could definitely be done in a more efficient manner.
while (!m_regions.is_empty()) {
auto& region = *m_regions.begin();
m_regions.remove(region.vaddr().get());
delete ®ion;
}
}
ErrorOr<VirtualRange> RegionTree::allocate_range_anywhere(size_t size, size_t alignment)
{
if (!size)
return EINVAL;
VERIFY((size % PAGE_SIZE) == 0);
VERIFY((alignment % PAGE_SIZE) == 0);
if (Checked<size_t>::addition_would_overflow(size, alignment))
return EOVERFLOW;
VirtualAddress window_start = m_total_range.base();
auto allocate_from_window = [&](VirtualRange const& window) -> Optional<VirtualRange> {
// FIXME: This check is probably excluding some valid candidates when using a large alignment.
if (window.size() < (size + alignment))
return {};
FlatPtr initial_base = window.base().get();
FlatPtr aligned_base = round_up_to_power_of_two(initial_base, alignment);
VERIFY(size);
return VirtualRange { VirtualAddress(aligned_base), size };
};
for (auto it = m_regions.begin(); !it.is_end(); ++it) {
auto& region = *it;
if (window_start == region.vaddr()) {
window_start = region.range().end();
continue;
}
VirtualRange window { window_start, region.vaddr().get() - window_start.get() };
window_start = region.range().end();
if (auto maybe_range = allocate_from_window(window); maybe_range.has_value())
return maybe_range.release_value();
}
VirtualRange window { window_start, m_total_range.end().get() - window_start.get() };
if (m_total_range.contains(window)) {
if (auto maybe_range = allocate_from_window(window); maybe_range.has_value())
return maybe_range.release_value();
}
dmesgln("RegionTree: Failed to allocate anywhere: size={}, alignment={}", size, alignment);
return ENOMEM;
}
ErrorOr<VirtualRange> RegionTree::allocate_range_specific(VirtualAddress base, size_t size)
{
if (!size)
return EINVAL;
VERIFY(base.is_page_aligned());
VERIFY((size % PAGE_SIZE) == 0);
VirtualRange const range { base, size };
if (!m_total_range.contains(range))
return ENOMEM;
auto* region = m_regions.find_largest_not_above(base.offset(size - 1).get());
if (!region) {
// The range can be accommodated below the current lowest range.
return range;
}
if (region->range().intersects(range)) {
// Requested range overlaps an existing range.
return ENOMEM;
}
// Requested range fits between first region and its next neighbor.
return range;
}
ErrorOr<VirtualRange> RegionTree::allocate_range_randomized(size_t size, size_t alignment)
{
if (!size)
return EINVAL;
VERIFY((size % PAGE_SIZE) == 0);
VERIFY((alignment % PAGE_SIZE) == 0);
// FIXME: I'm sure there's a smarter way to do this.
constexpr size_t maximum_randomization_attempts = 1000;
for (size_t i = 0; i < maximum_randomization_attempts; ++i) {
VirtualAddress random_address { round_up_to_power_of_two(get_fast_random<FlatPtr>() % m_total_range.end().get(), alignment) };
if (!m_total_range.contains(random_address, size))
continue;
auto range_or_error = allocate_range_specific(random_address, size);
if (!range_or_error.is_error())
return range_or_error.release_value();
}
return allocate_range_anywhere(size, alignment);
}
ErrorOr<void> RegionTree::place_anywhere(Region& region, RandomizeVirtualAddress randomize_virtual_address, size_t size, size_t alignment)
{
auto range = TRY(randomize_virtual_address == RandomizeVirtualAddress::Yes ? allocate_range_randomized(size, alignment) : allocate_range_anywhere(size, alignment));
region.m_range = range;
m_regions.insert(region.vaddr().get(), region);
return {};
}
ErrorOr<void> RegionTree::place_specifically(Region& region, VirtualRange const& range)
{
auto allocated_range = TRY(allocate_range_specific(range.base(), range.size()));
region.m_range = allocated_range;
m_regions.insert(region.vaddr().get(), region);
return {};
}
bool RegionTree::remove(Region& region)
{
return m_regions.remove(region.range().base().get());
}
Region* RegionTree::find_region_containing(VirtualAddress address)
{
auto* region = m_regions.find_largest_not_above(address.get());
if (!region || !region->contains(address))
return nullptr;
return region;
}
Region* RegionTree::find_region_containing(VirtualRange range)
{
auto* region = m_regions.find_largest_not_above(range.base().get());
if (!region || !region->contains(range))
return nullptr;
return region;
}
}
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