mirror of
https://github.com/LadybirdBrowser/ladybird.git
synced 2025-05-20 18:12:53 +00:00
2d1a651e0a
This patch changes the semantics of purgeable memory. - AnonymousVMObject now has a "purgeable" flag. It can only be set when constructing the object. (Previously, all anonymous memory was effectively purgeable.) - AnonymousVMObject now has a "volatile" flag. It covers the entire range of physical pages. (Previously, we tracked ranges of volatile pages, effectively making it a page-level concept.) - Non-volatile objects maintain a physical page reservation via the committed pages mechanism, to ensure full coverage for page faults. - When an object is made volatile, it relinquishes any unused committed pages immediately. If later made non-volatile again, we then attempt to make a new committed pages reservation. If this fails, we return ENOMEM to userspace. mmap() now creates purgeable objects if passed the MAP_PURGEABLE option together with MAP_ANONYMOUS. anon_create() memory is always purgeable.
84 lines
2.6 KiB
C++
84 lines
2.6 KiB
C++
/*
|
|
* 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/VMObject.h>
|
|
|
|
namespace Kernel {
|
|
|
|
class CommittedCowPages : public RefCounted<CommittedCowPages> {
|
|
AK_MAKE_NONCOPYABLE(CommittedCowPages);
|
|
|
|
public:
|
|
CommittedCowPages() = delete;
|
|
|
|
CommittedCowPages(size_t);
|
|
~CommittedCowPages();
|
|
|
|
NonnullRefPtr<PhysicalPage> allocate_one();
|
|
bool return_one();
|
|
|
|
private:
|
|
size_t m_committed_pages;
|
|
};
|
|
|
|
class AnonymousVMObject final : public VMObject {
|
|
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>>);
|
|
static RefPtr<AnonymousVMObject> try_create_purgeable_with_size(size_t, AllocationStrategy);
|
|
virtual RefPtr<VMObject> try_clone() override;
|
|
|
|
[[nodiscard]] NonnullRefPtr<PhysicalPage> allocate_committed_page(Badge<Region>);
|
|
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);
|
|
|
|
bool is_purgeable() const { return m_purgeable; }
|
|
bool is_volatile() const { return m_volatile; }
|
|
|
|
KResult set_volatile(bool is_volatile, bool& was_purged);
|
|
|
|
size_t purge();
|
|
|
|
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; }
|
|
|
|
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();
|
|
|
|
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;
|
|
|
|
bool m_purgeable { false };
|
|
bool m_volatile { false };
|
|
bool m_was_purged { false };
|
|
};
|
|
|
|
}
|