ladybird/Kernel/VM/RangeAllocator.h

/*
 * 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.
 */

#pragma once

#include <AK/String.h>
#include <AK/Traits.h>
#include <AK/Vector.h>
#include <Kernel/SpinLock.h>
#include <Kernel/VirtualAddress.h>

namespace Kernel {

class Range {
    friend class RangeAllocator;

public:
    Range() = delete;
    Range(VirtualAddress base, size_t size)
        : m_base(base)
        , m_size(size)
    {
    }

    VirtualAddress base() const { return m_base; }
    size_t size() const { return m_size; }
    bool is_valid() const { return !m_base.is_null(); }

    bool contains(VirtualAddress vaddr) const { return vaddr >= base() && vaddr < end(); }

    VirtualAddress end() const { return m_base.offset(m_size); }

    bool operator==(const Range& other) const
    {
        return m_base == other.m_base && m_size == other.m_size;
    }

    bool contains(VirtualAddress base, size_t size) const
    {
        if (base.offset(size) < base)
            return false;
        return base >= m_base && base.offset(size) <= end();
    }

    bool contains(const Range& other) const
    {
        return contains(other.base(), other.size());
    }

    Vector<Range, 2> carve(const Range&);

private:
    VirtualAddress m_base;
    size_t m_size { 0 };
};

class RangeAllocator {
public:
    RangeAllocator();
    ~RangeAllocator();

    void initialize_with_range(VirtualAddress, size_t);
    void initialize_from_parent(const RangeAllocator&);

    Optional<Range> allocate_anywhere(size_t, size_t alignment = PAGE_SIZE);
    Optional<Range> allocate_specific(VirtualAddress, size_t);
    Optional<Range> allocate_randomized(size_t, size_t alignment);
    void deallocate(const Range&);

    void dump() const;

    bool contains(const Range& range) const
    {
        ScopedSpinLock lock(m_lock);
        return m_total_range.contains(range);
    }

private:
    void carve_at_index(int, const Range&);

    Vector<Range> m_available_ranges;
    Range m_total_range;
    mutable SpinLock<u8> m_lock;
};

inline const LogStream& operator<<(const LogStream& stream, const Range& value)
{
    return stream << String::formatted("Range({:08x}-{:08x})", value.base().get(), value.end().get() - 1);
}

}

namespace AK {
template<>
struct Traits<Kernel::Range> : public GenericTraits<Kernel::Range> {
    static constexpr bool is_trivial() { return true; }
};
}