mirror of
https://github.com/RGBCube/serenity
synced 2025-05-20 11:55:08 +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.
55 lines
1.4 KiB
C++
55 lines
1.4 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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#include <Kernel/FileSystem/AnonymousFile.h>
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#include <Kernel/FileSystem/FileDescription.h>
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#include <Kernel/Process.h>
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#include <Kernel/VM/AnonymousVMObject.h>
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namespace Kernel {
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KResultOr<FlatPtr> Process::sys$anon_create(size_t size, int options)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
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REQUIRE_PROMISE(stdio);
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if (!size)
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return EINVAL;
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if (size % PAGE_SIZE)
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return EINVAL;
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if (size > NumericLimits<ssize_t>::max())
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return EINVAL;
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int new_fd = m_fds.allocate();
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if (new_fd < 0)
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return new_fd;
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auto vmobject = AnonymousVMObject::try_create_purgeable_with_size(size, AllocationStrategy::Reserve);
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if (!vmobject)
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return ENOMEM;
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auto anon_file = AnonymousFile::create(vmobject.release_nonnull());
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if (!anon_file)
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return ENOMEM;
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auto description_or_error = FileDescription::create(*anon_file);
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if (description_or_error.is_error())
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return description_or_error.error();
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auto description = description_or_error.release_value();
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description->set_writable(true);
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description->set_readable(true);
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u32 fd_flags = 0;
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if (options & O_CLOEXEC)
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fd_flags |= FD_CLOEXEC;
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m_fds[new_fd].set(move(description), fd_flags);
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return new_fd;
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}
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}
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