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