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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.
39 lines
1.3 KiB
C++
39 lines
1.3 KiB
C++
/*
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* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <Kernel/FileSystem/File.h>
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#include <Kernel/VM/AnonymousVMObject.h>
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namespace Kernel {
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class AnonymousFile final : public File {
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public:
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static RefPtr<AnonymousFile> create(NonnullRefPtr<AnonymousVMObject> vmobject)
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{
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return adopt_ref_if_nonnull(new (nothrow) AnonymousFile(move(vmobject)));
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}
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virtual ~AnonymousFile() override;
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virtual KResultOr<Region*> mmap(Process&, FileDescription&, const Range&, u64 offset, int prot, bool shared) override;
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private:
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virtual StringView class_name() const override { return "AnonymousFile"; }
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virtual String absolute_path(const FileDescription&) const override { return ":anonymous-file:"; }
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virtual bool can_read(const FileDescription&, size_t) const override { return false; }
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virtual bool can_write(const FileDescription&, size_t) const override { return false; }
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virtual KResultOr<size_t> read(FileDescription&, u64, UserOrKernelBuffer&, size_t) override { return ENOTSUP; }
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virtual KResultOr<size_t> write(FileDescription&, u64, const UserOrKernelBuffer&, size_t) override { return ENOTSUP; }
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explicit AnonymousFile(NonnullRefPtr<AnonymousVMObject>);
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NonnullRefPtr<AnonymousVMObject> m_vmobject;
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};
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}
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