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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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// Classes which implement a circular doubly linked list of DMemoryMappingBase objects.
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//
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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 MMAPPINGLIST_H
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#define MMAPPINGLIST_H
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#include <kernel.h>
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#include <nk_priv.h>
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class DMemoryMappingBase;
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//
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// TMappingListBase
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//
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/**
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Base class implementing basic list insertion and removal functionality for memory mapping lists.
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*/
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class TMappingListBase
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{
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#ifdef _DEBUG
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public:
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/**
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Debug check returning true if iSpinLock is held by the current thread.
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In reality this just checks that interrupts are currently disabled as spinlocks
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do not support identifying the thread which holds it.
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*/
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FORCE_INLINE TBool LockIsHeld()
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{
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return InterruptsStatus(false);
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}
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#endif
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protected:
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/** Class type id of this object, this is stored in iType. */
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enum TType
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{
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EHead = 1, ///< This object is a TMappingList object
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ELink, ///< This object is a TMappingListLink object
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EIter ///< This object is a TMappingListIter object
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};
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FORCE_INLINE TMappingListBase(TType aType)
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: iType(aType)
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{
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KillLink();
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}
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/** Remove this link from the list it is in. */
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FORCE_INLINE void Remove()
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{
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__NK_ASSERT_DEBUG(!IsLinkDead());
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TMappingListBase* next = iNext;
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TMappingListBase* prev = iPrev;
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next->iPrev=prev;
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prev->iNext=next;
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KillLink();
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}
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/** Insert this link after \a aPrev */
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FORCE_INLINE void InsertAfter(TMappingListBase* aPrev)
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{
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__NK_ASSERT_DEBUG(IsLinkDead());
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TMappingListBase* next = aPrev->iNext;
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iPrev = aPrev;
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iNext = next;
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next->iPrev = this;
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aPrev->iNext = this;
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}
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/** Insert this link before \a aNext */
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FORCE_INLINE void InsertBefore(TMappingListBase* aNext)
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{
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__NK_ASSERT_DEBUG(IsLinkDead());
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TMappingListBase* prev = aNext->iPrev;
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iNext = aNext;
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iPrev = prev;
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aNext->iPrev = this;
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prev->iNext = this;
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}
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/**
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In debug builds, munge the iNext and iPrev link values so that if
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they are used an exception is likely.
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*/
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FORCE_INLINE void KillLink()
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{
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#ifdef _DEBUG
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iNext = (TMappingListBase*)KILL_LINK_VALUE;
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iPrev = (TMappingListBase*)KILL_LINK_VALUE;
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#endif
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}
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#ifdef _DEBUG
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/** Debug check returning true if this link is 'dead', i.e. been killed with KillLink. */
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FORCE_INLINE TBool IsLinkDead()
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{
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// we don't check iNext here because that may have been set to null by
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// TMappingListLink as a non-debug indicator of a link not in a list.
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return iPrev==(TMappingListBase*)KILL_LINK_VALUE;
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}
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#endif
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protected:
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TMappingListBase* iNext; ///< Next item in list.
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TMappingListBase* iPrev; ///< Previous item in list.
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TUint8 iType; ///< Value from enum TType which identifies this object's derived type.
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public:
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TUint8 iSpare1; ///< Unused storage available for any purpose.
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TUint8 iSpare2; ///< Unused storage available for any purpose.
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TUint8 iSpare3; ///< Unused storage available for any purpose.
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protected:
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static TSpinLock iSpinLock; ///< Global spinlock used for manipulating all lists.
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friend class TMappingListIter;
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};
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//
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// TMappingList
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//
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/**
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Head of a circular doubly linked list of DMemoryMappingBase objects.
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*/
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class TMappingList : public TMappingListBase
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{
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public:
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/** Construct an empty list. */
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FORCE_INLINE TMappingList()
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: TMappingListBase(EHead)
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{
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iNext = this;
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iPrev = this;
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}
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/** Destructor which asserts in debug builds that this list is empty. */
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FORCE_INLINE ~TMappingList()
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{
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__NK_ASSERT_DEBUG(IsEmpty());
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}
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/**
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Add \a aMapping to the end of this list.
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@pre The list must be locked with #Lock.
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*/
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void Add(DMemoryMappingBase* aMapping);
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/**
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Remove \a aMapping from this list.
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@pre The list must be locked with #Lock.
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*/
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void Remove(DMemoryMappingBase* aMapping);
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/**
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Lock the list to prevent other threads changing it.
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This is a spinlock so all operations with the lock held must be very sort.
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@see Unlock
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*/
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FORCE_INLINE void Lock()
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{
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__NK_ASSERT_DEBUG(!LockIsHeld());
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__SPIN_LOCK_IRQ(iSpinLock);
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}
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/**
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Reverse the action of #Lock.
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*/
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FORCE_INLINE void Unlock()
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{
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__NK_ASSERT_DEBUG(LockIsHeld());
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__SPIN_UNLOCK_IRQ(iSpinLock);
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}
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/** Return true if this list is empty */
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FORCE_INLINE TBool IsEmpty() const
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{
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return iNext==(TMappingListBase*)this;
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}
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// Utility methods to call a method on every element of a list
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/**
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Update the page table entry for a specified page in all mappings in the list that contain it.
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@param aPages The page array entry of the page in a memory object.
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Only array entries which have a target state of
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RPageArray::ECommitted should be mapped into the
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mapping's page tables.
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@param aIndex The index of the page in the memory object.
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@param aMapInstanceCount The instance of this mapping which is to be updated.
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Whenever this no longer matches the current #MapInstanceCount
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the function must not update any more of the mapping's
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page table entries, (but must still return KErrNone).
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@param aInvalidateTLB Set to ETrue when the TLB entries associated with this page
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should be invalidated. This must be done when there is
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already a valid pte for this page, i.e. if the page is still
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mapped.
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@see #DMemoryMappingBase::RemapPage
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*/
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void RemapPage(TPhysAddr& aPageArray, TUint aIndex, TBool aInvalidateTLB);
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};
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//
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// TMappingListLink
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//
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/**
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A link in a circular doubly linked list of DMemoryMappingBase objects.
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This object is the member DMemoryMappingBase::iLink.
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*/
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class TMappingListLink : public TMappingListBase
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{
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public:
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/** Construct a link which is not part of any list. */
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FORCE_INLINE TMappingListLink()
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: TMappingListBase(ELink)
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{
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// iNext is the null pointer when link is not on list...
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iNext = 0;
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}
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/** Destructor which asserts in debug builds that this link isn't in a list. */
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FORCE_INLINE ~TMappingListLink()
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{
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__NK_ASSERT_DEBUG(!IsLinked());
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}
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/** Return true if link is in any list. */
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FORCE_INLINE TBool IsLinked()
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{
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return iNext!=0;
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}
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private:
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/**
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Remove this link from the list it is in.
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This is for use by class TMappingList.
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*/
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FORCE_INLINE void Remove()
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{
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__NK_ASSERT_DEBUG(LockIsHeld());
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__NK_ASSERT_DEBUG(iNext);
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TMappingListBase::Remove();
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iNext = 0;
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}
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friend class TMappingList;
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};
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//
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// TMappingListIter
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//
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/**
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An iterator for visiting all memory mappings in a list.
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The iterator object itself is linked into the list so that mappings can safely
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be removed and added to the list whilst it is being iterated. As new mappings
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are only ever added to the end of the list, this ensures that once the iterator
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reaches the end of the list it has found all mappings currently present.
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As the spinlock used to guard lists disables interrupts it is very important
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to only hold the lock for a very short and bounded time. Specifically, as the
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Next() function doesn't necessarily release the lock, any loop iterating over
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a list must take care to Unlock() then Lock() again sufficiently often to avoid
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adversely impacting interrupt latency.
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Example usage...
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@code
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DMemoryObject* memory;
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memory->iMappings.Lock();
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TMappingListIter iter;
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DMemoryMappingBase* mapping = iter.Start(memory->iMappings);
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while(mapping)
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{
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mapping->Open();
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memory->iMappings.Unlock();
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// mapping may now be used without risk of it being deleted;
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// however, it may still be removed from the list and updated/reused
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// therefore caution must be exercised
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mapping->Close();
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memory->iMappings.Lock();
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mapping = iter.Next();
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}
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iter.Finish();
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memory->iMappings.Unlock();
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@endcode
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*/
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class TMappingListIter : public TMappingListBase
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{
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public:
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FORCE_INLINE TMappingListIter()
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: TMappingListBase(EIter)
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{
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}
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/** Destructor which asserts in debug builds that this iterator isn't attached to a list. */
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FORCE_INLINE ~TMappingListIter()
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{
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// check that this isn't still linked into a list...
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__NK_ASSERT_DEBUG(IsLinkDead());
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}
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/**
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Attach this iterator to list \a aList and return the first mapping in that list.
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The null pointer is returned if the list is empty.
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Must only be called on a newly constructed iterator object, or after #Finish
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has removed this iterator from a list.
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@pre The list must be locked with TMappingList::Lock
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*/
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DMemoryMappingBase* Start(TMappingList& aList);
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/**
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Return the next mapping in the list after the previous one returned by either
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#Start or #Next. The null pointer is returned if the list end has been reached.
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During its operation, this function may or may not have unlocked the list using
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TMappingList::Unlock. Therefore, when using Next() in a loop, care care must be
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taken to unlock the list sufficiently often to avoid adversely impacting interrupt
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latency.
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@pre The list must be locked with TMappingList::Lock.
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@pre The iterator must have been previously attached to a list with #Start and not
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since been removed with #Finish.
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@post The list will be locked with TMappingList::Lock but this lock may have been
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released for a period of time by the function during its operation.
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*/
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DMemoryMappingBase* Next();
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/**
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Remove this iterator from the list it has been attached to.
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@pre The list must be locked with TMappingList::Lock
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@pre The iterator must have been previously attached to a list with #Start and not
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since been removed with #Finish.
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*/
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void Finish();
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private:
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/** Implementation factor for #Start and #Next() */
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DMemoryMappingBase* Next(TMappingListBase* aPrev);
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};
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#endif
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