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// Copyright (c) 2007-2009 Nokia Corporation and/or its subsidiary(-ies).
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// All rights reserved.
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// This component and the accompanying materials are made available
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// under the terms of the License "Eclipse Public License v1.0"
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// which accompanies this distribution, and is available
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// at the URL "http://www.eclipse.org/legal/epl-v10.html".
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//
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// Initial Contributors:
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// Nokia Corporation - initial contribution.
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//
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// Contributors:
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//
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// Description:
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//
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/**
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@file
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@internalComponent
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*/
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#ifndef MPTALLOC_H
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#define MPTALLOC_H
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#include "mcleanup.h"
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/**
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Number of #SPageTableInfo structures which will fit into a page of RAM.
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*/
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const TUint KPageTableInfosPerPage = KPageSize/sizeof(SPageTableInfo);
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/**
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Number of pages of page tables which correspond to a page of page infos.
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*/
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const TUint KPageTableGroupSize = KPageTableInfosPerPage/KPtClusterSize;
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/**
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Max number of RAM pages which can be used for page tables.
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*/
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const TUint KMaxPageTablePages = (KPageTableEnd-KPageTableBase)/KPageSize;
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/**
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The maximum number of pages required to pin a single page table.
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*/
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const TUint KNumPagesToPinOnePageTable = 2; // 1 page table page + 1 page table info page
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/**
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Class for allocating MMU page tables.
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*/
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class PageTableAllocator
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{
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public:
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void Init2(DMutex* aLock);
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void Init2B();
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/**
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Allocate a page table.
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@param aDemandPaged True if the page table will be used to map demand paged memory;
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false, otherwise.
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@return Virtual address of the allocated page table,
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or the null-pointer if there was insufficient memory.
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@pre #PageTablesLockIsHeld, i.e. current thread has called #Lock()
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*/
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TPte* Alloc(TBool aDemandPaged);
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/**
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Free a page table previously aquired with #Alloc.
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@param aPageTable Virtual address of the page table,
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@pre #PageTablesLockIsHeld, i.e. current thread has called #Lock()
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*/
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void Free(TPte* aPageTable);
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/**
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Acquire the mutex used to protect page table allocation.
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*/
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void Lock();
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/**
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Release the mutex used to protect page table allocation.
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*/
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void Unlock();
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/**
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Return true if the current thread has acquired the mutex used to protect page table allocation.
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I.e. has called #Lock().
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*/
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TBool LockIsHeld();
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/**
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Steal a RAM page which is currently being used to store demand paged page tables
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or page table infos.
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This removes the page tables contained in the RAM from any objects which own
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them and then returns the RAM to the demand paging system as a free page. This
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will not ever return KErrNone indicating that the page has been successfully
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stolen.
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This is only intended for use by DPageTableMemoryManager::StealPage.
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@param aPageInfo The page information structure of the page to be stolen.
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@return KErrCompletion to indicate that the page was stolen but has been
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returned to the demand paging live list as a free page.
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Otherwise, KErrInUse if the page was not able to be freed.
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@pre #PageTablesLockIsHeld, i.e. current thread has called #Lock()
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@pre MmuLock held.
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*/
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TInt StealPage(SPageInfo* aPageInfo);
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/**
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Discards a page of page tables or page table infos but only if it is demand paged.
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This will only be invoked on page table info pages or pinned paged tables
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as they aren't on the live list and so M::MovePage() will not know the pager
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can discard them.
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@param aMemory This should always be the page table info memory object.
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@param aOldPageInfo The page info of the page to discard.
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@param aBlockZoneId The ID of any RAM zone not to be allocated into.
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@param aBlockRest ETrue when any allocations should stop if blocked zone hit.
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@return KErrNone if the page could be successfully discarded and its RAM page freed.
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*/
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TInt MovePage( DMemoryObject* aMemory, SPageInfo* aOldPageInfo,
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TUint aBlockZoneId, TBool aBlockRest);
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#ifdef _DEBUG
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/**
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Debug function for use by DPager::RemovePage() to allow it to remove
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pages with paged state == EUnpaged.
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A page table page may be stolen when it is unpaged as it has been
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allocated via DMemoryMapping::AllocatePageTable() but not yet rejuvenated
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by Mmu::PageInPages() as the MmuLock is released between these stages.
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A page table info page is never added to the live list so it will always
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be unpaged but it can be stolen so allow it to be removed.
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@param aPageInfo The page info of the page.
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@return ETrue if the page is a page table info page, EFalse otherwise.
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*/
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TBool IsPageTableUnpagedRemoveAllowed(SPageInfo* aPageInfo);
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#endif
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/**
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Pin the RAM page containing a page table, as well as the RAM page
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containing its #SPageTableInfo structure.
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@param aPageTable Virtual address of the page table,
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@param aPinArgs The resources to use for pinning. This must have
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at least #KNumPagesToPinOnePageTable replacement
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pages available.
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*/
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static void PinPageTable(TPte* aPageTable, TPinArgs& aPinArgs);
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/**
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Unpin the RAM page containing a page table, as well as the RAM page
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containing its #SPageTableInfo structure.
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This reverses the action of #PinPageTable.
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@param aPageTable Virtual address of the page table,
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@param aPinArgs The resources to use for pinning. The replacement
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pages count in this will be incremented for each
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completely unpinned, e.g. those which can be reused
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as new replacement pages or freed.
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*/
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static void UnpinPageTable(TPte* aPageTable, TPinArgs& aPinArgs);
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private:
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/**
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Sub-allocator used for managing page tables of a given 'pagedness' (paged/not-paged).
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Each allocator maintains a list free page tables (#iFreeList) from which it can allocate.
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As well as a separate list of RAM pages which have no allocated page tables, #iCleanupList.
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Page tables in the RAM on #iCleanupList do not appear in #iFreeList.
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*/
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class TSubAllocator
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{
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public:
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void Init2(PageTableAllocator* iAllocator, TUint aReserveCount, TBool aDemandPaged);
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/**
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Allocate a page table from this sub-allocator.
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@return The #SPageTableInfo structure of the page table,
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or the null-pointer if none could be allocated.
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*/
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SPageTableInfo* Alloc();
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/**
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Free a page table back to this sub-allocator.
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@param aPageTableInfo The #SPageTableInfo structure of the page table.
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*/
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void Free(SPageTableInfo* aPageTableInfo);
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/**
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Add a single page of page tables to this allocator for management.
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@param aPageTableInfo The #SPageTableInfo structure of the first page table
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contained in the page.
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*/
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void AllocPage(SPageTableInfo* aPageTableInfo);
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/**
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Attempt to remove a single unused page of page tables from this allocator.
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@return The #SPageTableInfo structure of the first page table contained
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in the removed page. Or the null-pointer if there were no unused
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memory to be freed.
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*/
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SPageTableInfo* FreePage();
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/**
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Move a page of RAM containing page tables to #iCleanupList.
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All page tables in the page must be currently unused.
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@param aPageTableInfo The #SPageTableInfo structure of the first page table
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contained in the page.
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*/
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void MoveToCleanup(SPageTableInfo* aPageTableInfo);
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/**
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Return true if there are whole RAM pages which can be freed from this
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sub-allocator without reducing #iFreeCount below #iReserveCount.
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*/
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TBool IsCleanupRequired();
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/**
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Debug check returning true if this objects lists are in a valid state.
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*/
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TBool CheckFreeList();
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public:
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SDblQue iFreeList; ///< List of unused page tables, linked by their SPageTableInfo::FreeLink.
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SDblQue iCleanupList; ///< List of unused pages, linked by the SPageTableInfo::FreeLink of the first page table in the page.
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TUint iFreeCount; ///< Total free page tables in pages on #iFreeList and #iCleanupList.
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TUint iReserveCount; ///< Minimum number of page tables to keep in reserve.
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TBool iDemandPaged; ///< True if this allocator id used for demand paged page tables.
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};
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/**
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Implementation of #Alloc.
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*/
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TPte* DoAlloc(TBool aDemandPaged);
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/**
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Implementation of #Free.
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*/
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void DoFree(TPte* aPageTable);
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/**
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Allocate resources for a pages worth of page tables owned by \a aSubAllocator.
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@return True if the resources were successfully allocated.
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@pre #PageTablesLockIsHeld, i.e. current thread has called #Lock()
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*/
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TBool AllocReserve(TSubAllocator& aSubAllocator);
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/**
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Free the resources taken up by a pages worth of unused page tables
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owned by \a aSubAllocator.
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@return True, if any resources were freed.
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False, if there are no more unused resources.
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@pre #PageTablesLockIsHeld, i.e. current thread has called #Lock()
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*/
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TBool FreeReserve(TSubAllocator& aSubAllocator);
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/**
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Steal a RAM page which is currently being used to store demand paged page
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table infos.
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This removes all the page tables references by the page table infos contained in
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the RAM from any objects which own them and then returns the RAM to the demand
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paging system as a free page. This will not ever return KErrNone indicating that
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the page has been successfully stolen.
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This is only intended for use by PageTableAllocator::StealPage.
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@param aPageInfo The page information structure of the page to be stolen.
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@return KErrCompletion to indicate that the page was stolen but has been
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returned to the demand paging live list as a free page.
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Otherwise, KErrInUse if the page was not able to be freed.
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@pre #PageTablesLockIsHeld, i.e. current thread has called #Lock()
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@pre MmuLock held.
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*/
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TInt StealPageTableInfo(SPageInfo* aPageInfo);
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/**
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Free all unused resources taken up for page table management.
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*/
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void Cleanup();
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/**
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Trampoline function for use with iCleanup which redirects to #Cleanup().
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*/
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static void CleanupTrampoline(TAny* aSelf);
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private:
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/**
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Sub-allocator for allocating unpaged page tables.
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*/
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TSubAllocator iUnpagedAllocator;
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/**
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Sub-allocator for allocating demand paged page tables.
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*/
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TSubAllocator iPagedAllocator;
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/**
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Object used for queueing cleanup callbacks to #CleanupTrampoline.
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*/
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TMemoryCleanup iCleanup;
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/**
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Recursion count for #Alloc.
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*/
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TUint iAllocating;
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/**
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The mutex used to protect page table allocation.
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*/
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DMutex* iLock;
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/**
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The memory object used to store the memory containing page tables.
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*/
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DMemoryObject* iPageTableMemory;
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/**
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The memory object used to store #SPageTableInfo structures.
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*/
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DMemoryObject* iPageTableInfoMemory;
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/**
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Helper class for allocating page index values within #iPageTableMemory.
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This wraps up to two bitmap allocators, one each used for paged and unpaged
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page tables.
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Page indexes are allocated in a way which ensures that there will not be
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any SPageTableInfo structures for unpaged page tables in the same RAM page
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as the structures for paged page tables.
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*/
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class TPtPageAllocator
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{
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public:
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void Init2(TUint aNumInitPages);
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TInt Alloc(TBool aDemandPaged);
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void Free(TUint aPageIndex, TBool aDemandPaged);
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TBool IsDemandPaged(SPageInfo* aPageInfo)
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{// Is the highest page table index this page table info page can reference
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// allocated within the demand paged region of the page table address space.
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TUint groupIndex = aPageInfo->Index();
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return ((groupIndex+1) * KPageTableGroupSize)-1 >= iUpperWaterMark;
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}
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private:
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TBitMapAllocator* iLowerAllocator; ///< Allocator for unpaged page tables
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TUint iLowerWaterMark; ///< Highest page index allocated by iLowerAllocator
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TBitMapAllocator* iUpperAllocator; ///< Allocator for demand paged page tables
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TUint iUpperWaterMark; ///< Lowest page index allocated by iUpperAllocator
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};
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/**
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Allocator for page indexes within #iPageTableMemory.
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*/
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TPtPageAllocator iPtPageAllocator;
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/**
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Array which contains usage for pages of #SPageTableInfo structures.
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When the count is zero, there are no structure in use in the corresponding
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page of memory in #iPageTableInfoMemory. Indicating that the memory may be
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freed.
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*/
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TUint16 iPageTableGroupCounts[KMaxPageTablePages/KPageTableGroupSize];
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friend class TSubAllocator;
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};
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/**
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The single instance of the #PageTableAllocator.
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*/
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extern PageTableAllocator PageTables;
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#endif
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