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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/BinarySearch.h>
#include <AK/QuickSort.h>
#include <Kernel/Random.h>
#include <Kernel/Thread.h>
#include <Kernel/VM/RangeAllocator.h>
//#define VRA_DEBUG
#define VM_GUARD_PAGES
namespace Kernel {
RangeAllocator::RangeAllocator()
{
}
void RangeAllocator::initialize_with_range(VirtualAddress base, size_t size)
{
m_total_range = { base, size };
m_available_ranges.append({ base, size });
#ifdef VRA_DEBUG
dump();
#endif
}
void RangeAllocator::initialize_from_parent(const RangeAllocator& parent_allocator)
{
m_total_range = parent_allocator.m_total_range;
m_available_ranges = parent_allocator.m_available_ranges;
}
RangeAllocator::~RangeAllocator()
{
}
void RangeAllocator::dump() const
{
dbg() << "RangeAllocator{" << this << "}";
for (auto& range : m_available_ranges) {
dbg() << " " << String::format("%x", range.base().get()) << " -> " << String::format("%x", range.end().get() - 1);
}
}
Vector<Range, 2> Range::carve(const Range& taken)
{
Vector<Range, 2> parts;
if (taken == *this)
return {};
if (taken.base() > base())
parts.append({ base(), taken.base().get() - base().get() });
if (taken.end() < end())
parts.append({ taken.end(), end().get() - taken.end().get() });
#ifdef VRA_DEBUG
dbg() << "VRA: carve: take " << String::format("%x", taken.base().get()) << "-" << String::format("%x", taken.end().get() - 1) << " from " << String::format("%x", base().get()) << "-" << String::format("%x", end().get() - 1);
for (int i = 0; i < parts.size(); ++i)
dbg() << " " << String::format("%x", parts[i].base().get()) << "-" << String::format("%x", parts[i].end().get() - 1);
#endif
return parts;
}
void RangeAllocator::carve_at_index(int index, const Range& range)
{
auto remaining_parts = m_available_ranges[index].carve(range);
ASSERT(remaining_parts.size() >= 1);
m_available_ranges[index] = remaining_parts[0];
if (remaining_parts.size() == 2)
m_available_ranges.insert(index + 1, move(remaining_parts[1]));
}
Range RangeAllocator::allocate_anywhere(size_t size, size_t alignment)
{
if (!size)
return {};
#ifdef VM_GUARD_PAGES
// NOTE: We pad VM allocations with a guard page on each side.
size_t effective_size = size + PAGE_SIZE * 2;
size_t offset_from_effective_base = PAGE_SIZE;
#else
size_t effective_size = size;
size_t offset_from_effective_base = 0;
#endif
for (size_t i = 0; i < m_available_ranges.size(); ++i) {
auto& available_range = m_available_ranges[i];
// FIXME: This check is probably excluding some valid candidates when using a large alignment.
if (available_range.size() < (effective_size + alignment))
continue;
FlatPtr initial_base = available_range.base().offset(offset_from_effective_base).get();
FlatPtr aligned_base = round_up_to_power_of_two(initial_base, alignment);
Range allocated_range(VirtualAddress(aligned_base), size);
if (available_range == allocated_range) {
#ifdef VRA_DEBUG
dbg() << "VRA: Allocated perfect-fit anywhere(" << String::format("%zu", size) << ", " << String::format("%zu", alignment) << "): " << String::format("%x", allocated_range.base().get());
#endif
m_available_ranges.remove(i);
return allocated_range;
}
carve_at_index(i, allocated_range);
#ifdef VRA_DEBUG
dbg() << "VRA: Allocated anywhere(" << String::format("%zu", size) << ", " << String::format("%zu", alignment) << "): " << String::format("%x", allocated_range.base().get());
dump();
#endif
return allocated_range;
}
klog() << "VRA: Failed to allocate anywhere: " << size << ", " << alignment;
return {};
}
Range RangeAllocator::allocate_specific(VirtualAddress base, size_t size)
{
if (!size)
return {};
Range allocated_range(base, size);
for (size_t i = 0; i < m_available_ranges.size(); ++i) {
auto& available_range = m_available_ranges[i];
if (!available_range.contains(base, size))
continue;
if (available_range == allocated_range) {
m_available_ranges.remove(i);
return allocated_range;
}
carve_at_index(i, allocated_range);
#ifdef VRA_DEBUG
dbg() << "VRA: Allocated specific(" << size << "): " << String::format("%x", available_range.base().get());
dump();
#endif
return allocated_range;
}
dbg() << "VRA: Failed to allocate specific range: " << base << "(" << size << ")";
return {};
}
void RangeAllocator::deallocate(Range range)
{
ASSERT(m_total_range.contains(range));
ASSERT(range.size());
ASSERT(range.base() < range.end());
#ifdef VRA_DEBUG
dbg() << "VRA: Deallocate: " << String::format("%x", range.base().get()) << "(" << range.size() << ")";
dump();
#endif
ASSERT(!m_available_ranges.is_empty());
int nearby_index = 0;
auto* existing_range = binary_search(
m_available_ranges.data(), m_available_ranges.size(), range, [](auto& a, auto& b) {
return a.base().get() - b.end().get();
},
&nearby_index);
size_t inserted_index = 0;
if (existing_range) {
existing_range->m_size += range.size();
inserted_index = nearby_index;
} else {
m_available_ranges.insert_before_matching(
Range(range), [&](auto& entry) {
return entry.base() >= range.end();
},
nearby_index, &inserted_index);
}
if (inserted_index < (m_available_ranges.size() - 1)) {
// We already merged with previous. Try to merge with next.
auto& inserted_range = m_available_ranges[inserted_index];
auto& next_range = m_available_ranges[inserted_index + 1];
if (inserted_range.end() == next_range.base()) {
inserted_range.m_size += next_range.size();
m_available_ranges.remove(inserted_index + 1);
return;
}
}
#ifdef VRA_DEBUG
dbg() << "VRA: After deallocate";
dump();
#endif
}
}
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