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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <Kernel/PhysicalAddress.h>
#include <Kernel/VM/AllocationStrategy.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/VM/PageFaultResponse.h>
#include <Kernel/VM/PurgeablePageRanges.h>
#include <Kernel/VM/VMObject.h>
namespace Kernel {
class AnonymousVMObject final : public VMObject {
friend class PurgeablePageRanges;
public:
virtual ~AnonymousVMObject() override;
static RefPtr<AnonymousVMObject> try_create_with_size(size_t, AllocationStrategy);
static RefPtr<AnonymousVMObject> try_create_for_physical_range(PhysicalAddress paddr, size_t size);
static RefPtr<AnonymousVMObject> try_create_with_physical_pages(Span<NonnullRefPtr<PhysicalPage>>);
virtual RefPtr<VMObject> try_clone() override;
[[nodiscard]] NonnullRefPtr<PhysicalPage> allocate_committed_page(Badge<Region>, 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();
bool is_any_volatile() const;
template<IteratorFunction<VolatilePageRange const&> 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 (auto const& 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<IteratorFunction<VolatilePageRange const&> F>
IterationDecision for_each_nonvolatile_range(F f) const
{
size_t base = 0;
for_each_volatile_range([&](VolatilePageRange const& volatile_range) {
if (volatile_range.base == base)
return IterationDecision::Continue;
IterationDecision decision = f(VolatilePageRange { 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(VolatilePageRange { base, page_count() - base });
return IterationDecision::Continue;
}
template<VoidFunction<VolatilePageRange const&> F>
IterationDecision for_each_volatile_range(F f) const
{
return for_each_volatile_range([&](auto& range) {
f(range);
return IterationDecision::Continue;
});
}
template<VoidFunction<VolatilePageRange const&> F>
IterationDecision for_each_nonvolatile_range(F f) const
{
return for_each_nonvolatile_range([&](auto range) {
f(move(range));
return IterationDecision::Continue;
});
}
private:
explicit AnonymousVMObject(size_t, AllocationStrategy);
explicit AnonymousVMObject(PhysicalAddress, size_t);
explicit AnonymousVMObject(Span<NonnullRefPtr<PhysicalPage>>);
explicit AnonymousVMObject(AnonymousVMObject const&);
virtual StringView class_name() const override { return "AnonymousVMObject"sv; }
void update_volatile_cache();
void set_was_purged(VolatilePageRange const&);
size_t remove_lazy_commit_pages(VolatilePageRange const&);
void range_made_volatile(VolatilePageRange const&);
void range_made_nonvolatile(VolatilePageRange const&);
size_t count_needed_commit_pages_for_nonvolatile_range(VolatilePageRange const&);
size_t mark_committed_pages_for_nonvolatile_range(VolatilePageRange const&, size_t);
bool is_nonvolatile(size_t page_index);
AnonymousVMObject& operator=(AnonymousVMObject const&) = 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 };
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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