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https://github.com/RGBCube/serenity
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bc5d6992a4
This adds the ability for a Region to define volatile/nonvolatile areas within mapped memory using madvise(). This also means that memory purging takes into account all views of the PurgeableVMObject and only purges memory that is not needed by all of them. When calling madvise() to change an area to nonvolatile memory, return whether memory from that area was purged. At that time also try to remap all memory that is requested to be nonvolatile, and if insufficient pages are available notify the caller of that fact.
100 lines
3.3 KiB
C++
100 lines
3.3 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <AK/OwnPtr.h>
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#include <AK/WeakPtr.h>
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#include <Kernel/VM/MemoryManager.h>
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#include <Kernel/VM/PurgeableVMObject.h>
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namespace Kernel {
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class SharedBuffer {
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private:
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struct Reference {
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Reference(ProcessID pid, unsigned count = 0)
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: pid(pid)
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, count(count)
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{
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}
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ProcessID pid;
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unsigned count { 0 };
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WeakPtr<Region> region;
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};
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public:
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SharedBuffer(int id, int size)
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: m_shbuf_id(id)
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, m_vmobject(PurgeableVMObject::create_with_size(size))
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{
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#ifdef SHARED_BUFFER_DEBUG
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dbg() << "Created shared buffer " << m_shbuf_id << " of size " << size;
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#endif
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}
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~SharedBuffer()
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{
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#ifdef SHARED_BUFFER_DEBUG
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dbg() << "Destroyed shared buffer " << m_shbuf_id << " of size " << size();
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#endif
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}
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void sanity_check(const char* what);
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bool is_shared_with(ProcessID peer_pid) const;
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void* ref_for_process_and_get_address(Process& process);
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void share_with(ProcessID peer_pid);
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void share_globally() { m_global = true; }
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void deref_for_process(Process& process);
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bool disown(ProcessID pid);
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static void share_all_shared_buffers(Process& from_process, Process& with_process);
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size_t size() const { return m_vmobject->size(); }
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void destroy_if_unused();
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void seal();
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enum class SetVolatileError {
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Success = 0,
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NotPurgeable,
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OutOfMemory,
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NotMapped
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};
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SetVolatileError set_volatile_all(bool is_volatile, bool& was_purged);
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PurgeableVMObject& vmobject() { return m_vmobject; }
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const PurgeableVMObject& vmobject() const { return m_vmobject; }
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int id() const { return m_shbuf_id; }
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private:
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int m_shbuf_id { -1 };
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bool m_writable { true };
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bool m_global { false };
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NonnullRefPtr<PurgeableVMObject> m_vmobject;
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Vector<Reference, 2> m_refs;
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unsigned m_total_refs { 0 };
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};
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Lockable<HashMap<int, NonnullOwnPtr<SharedBuffer>>>& shared_buffers();
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}
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