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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.
*/
#pragma once
#include <Kernel/PhysicalAddress.h>
#include <Kernel/VM/AllocationStrategy.h>
#include <Kernel/VM/PageFaultResponse.h>
#include <Kernel/VM/PurgeablePageRanges.h>
#include <Kernel/VM/VMObject.h>
namespace Kernel {
class AnonymousVMObject : public VMObject {
friend class PurgeablePageRanges;
public:
virtual ~AnonymousVMObject() override;
static RefPtr<AnonymousVMObject> create_with_size(size_t, AllocationStrategy);
static RefPtr<AnonymousVMObject> create_for_physical_range(PhysicalAddress paddr, size_t size);
static NonnullRefPtr<AnonymousVMObject> create_with_physical_page(PhysicalPage& page);
virtual RefPtr<VMObject> clone() override;
RefPtr<PhysicalPage> allocate_committed_page(size_t);
PageFaultResponse handle_cow_fault(size_t, VirtualAddress);
size_t cow_pages() const;
bool should_cow(size_t page_index, bool) const;
void set_should_cow(size_t page_index, bool);
void register_purgeable_page_ranges(PurgeablePageRanges&);
void unregister_purgeable_page_ranges(PurgeablePageRanges&);
int purge();
int purge_with_interrupts_disabled(Badge<MemoryManager>);
bool is_any_volatile() const;
template<typename F>
IterationDecision for_each_volatile_range(F f) const
{
VERIFY(m_lock.is_locked());
// This is a little ugly. Basically, we're trying to find the
// volatile ranges that all share, because those are the only
// pages we can actually purge
for (auto* purgeable_range : m_purgeable_ranges) {
ScopedSpinLock purgeable_lock(purgeable_range->m_volatile_ranges_lock);
for (auto& r1 : purgeable_range->volatile_ranges().ranges()) {
VolatilePageRange range(r1);
for (auto* purgeable_range2 : m_purgeable_ranges) {
if (purgeable_range2 == purgeable_range)
continue;
ScopedSpinLock purgeable2_lock(purgeable_range2->m_volatile_ranges_lock);
if (purgeable_range2->is_empty()) {
// If just one doesn't allow any purging, we can
// immediately bail
return IterationDecision::Continue;
}
for (const auto& r2 : purgeable_range2->volatile_ranges().ranges()) {
range = range.intersected(r2);
if (range.is_empty())
break;
}
if (range.is_empty())
break;
}
if (range.is_empty())
continue;
IterationDecision decision = f(range);
if (decision != IterationDecision::Continue)
return decision;
}
}
return IterationDecision::Continue;
}
template<typename F>
IterationDecision for_each_nonvolatile_range(F f) const
{
size_t base = 0;
for_each_volatile_range([&](const VolatilePageRange& volatile_range) {
if (volatile_range.base == base)
return IterationDecision::Continue;
IterationDecision decision = f({ base, volatile_range.base - base });
if (decision != IterationDecision::Continue)
return decision;
base = volatile_range.base + volatile_range.count;
return IterationDecision::Continue;
});
if (base < page_count())
return f({ base, page_count() - base });
return IterationDecision::Continue;
}
private:
explicit AnonymousVMObject(size_t, AllocationStrategy);
explicit AnonymousVMObject(PhysicalAddress, size_t);
explicit AnonymousVMObject(PhysicalPage&);
explicit AnonymousVMObject(const AnonymousVMObject&);
virtual const char* class_name() const override { return "AnonymousVMObject"; }
int purge_impl();
void update_volatile_cache();
void set_was_purged(const VolatilePageRange&);
size_t remove_lazy_commit_pages(const VolatilePageRange&);
void range_made_volatile(const VolatilePageRange&);
void range_made_nonvolatile(const VolatilePageRange&);
size_t count_needed_commit_pages_for_nonvolatile_range(const VolatilePageRange&);
size_t mark_committed_pages_for_nonvolatile_range(const VolatilePageRange&, size_t);
bool is_nonvolatile(size_t page_index);
AnonymousVMObject& operator=(const AnonymousVMObject&) = delete;
AnonymousVMObject& operator=(AnonymousVMObject&&) = delete;
AnonymousVMObject(AnonymousVMObject&&) = delete;
virtual bool is_anonymous() const override { return true; }
Bitmap& ensure_cow_map();
void ensure_or_reset_cow_map();
VolatilePageRanges m_volatile_ranges_cache;
bool m_volatile_ranges_cache_dirty { true };
Vector<PurgeablePageRanges*> m_purgeable_ranges;
size_t m_unused_committed_pages { 0 };
mutable OwnPtr<Bitmap> m_cow_map;
// We share a pool of committed cow-pages with clones
RefPtr<CommittedCowPages> m_shared_committed_cow_pages;
};
}
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