--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/kernel/eka/memmodel/epoc/flexible/mmu/x86/xmmu.cpp	Mon Oct 19 15:55:17 2009 +0100
@@ -0,0 +1,732 @@
+// Copyright (c) 1997-2009 Nokia Corporation and/or its subsidiary(-ies).
+// All rights reserved.
+// This component and the accompanying materials are made available
+// under the terms of the License "Eclipse Public License v1.0"
+// which accompanies this distribution, and is available
+// at the URL "http://www.eclipse.org/legal/epl-v10.html".
+//
+// Initial Contributors:
+// Nokia Corporation - initial contribution.
+//
+// Contributors:
+//
+// Description:
+//
+
+#include <x86_mem.h>
+#include "cache_maintenance.inl"
+#include "execs.h"
+#include "mm.h"
+#include "mmu.h"
+#include "mpager.h"
+#include "mpdalloc.h"
+
+
+TPte PteGlobal;	// =0x100 on processors which support global pages, 0 on processors which don't
+
+#if defined(KMMU)
+extern "C" void __DebugMsgFlushTLB()
+	{
+	__KTRACE_OPT(KMMU,Kern::Printf("FlushTLB"));
+	}
+
+extern "C" void __DebugMsgLocalFlushTLB()
+	{
+	__KTRACE_OPT(KMMU,Kern::Printf("FlushTLB"));
+	}
+
+extern "C" void __DebugMsgINVLPG(int a)
+	{
+	__KTRACE_OPT(KMMU,Kern::Printf("INVLPG(%08x)",a));
+	}
+#endif
+
+
+
+extern void DoLocalInvalidateTLB();
+
+
+#ifndef __SMP__
+
+
+FORCE_INLINE void LocalInvalidateTLB()
+	{
+	DoLocalInvalidateTLB();
+	}
+
+
+#else // __SMP__
+
+
+const TInt KMaxPages = 1;
+
+class TTLBIPI : public TGenericIPI
+	{
+public:
+	TTLBIPI();
+	static void InvalidateForPagesIsr(TGenericIPI*);
+	static void LocalInvalidateIsr(TGenericIPI*);
+	static void InvalidateIsr(TGenericIPI*);
+	static void WaitAndInvalidateIsr(TGenericIPI*);
+	void AddAddress(TLinAddr aAddr);
+	void InvalidateList();
+public:
+	volatile TInt	iFlag;
+	TInt			iCount;
+	TLinAddr		iAddr[KMaxPages];
+	};
+
+TTLBIPI::TTLBIPI()
+	:	iFlag(0), iCount(0)
+	{
+	}
+
+void TTLBIPI::LocalInvalidateIsr(TGenericIPI*)
+	{
+	TRACE2(("TLBLocInv"));
+	DoLocalInvalidateTLB();
+	}
+
+void TTLBIPI::InvalidateIsr(TGenericIPI*)
+	{
+	TRACE2(("TLBInv"));
+	DoInvalidateTLB();
+	}
+
+void TTLBIPI::WaitAndInvalidateIsr(TGenericIPI* aTLBIPI)
+	{
+	TRACE2(("TLBWtInv"));
+	TTLBIPI& a = *(TTLBIPI*)aTLBIPI;
+	while (!a.iFlag)
+		{}
+	if (a.iCount == 1)
+		DoInvalidateTLBForPage(a.iAddr[0]);
+	else
+		DoInvalidateTLB();
+	}
+
+void TTLBIPI::InvalidateForPagesIsr(TGenericIPI* aTLBIPI)
+	{
+	TTLBIPI& a = *(TTLBIPI*)aTLBIPI;
+	TInt i;
+	for (i=0; i<a.iCount; ++i)
+		{
+		TRACE2(("TLBInv %08x", a.iAddr[i]));
+		DoInvalidateTLBForPage(a.iAddr[i]);
+		}
+	}
+
+void TTLBIPI::AddAddress(TLinAddr aAddr)
+	{
+	iAddr[iCount] = aAddr;
+	if (++iCount == KMaxPages)
+		InvalidateList();
+	}
+
+void TTLBIPI::InvalidateList()
+	{
+	NKern::Lock();
+	InvalidateForPagesIsr(this);
+	QueueAllOther(&InvalidateForPagesIsr);
+	NKern::Unlock();
+	WaitCompletion();
+	iCount = 0;
+	}
+
+void LocalInvalidateTLB()
+	{
+	TTLBIPI ipi;
+	NKern::Lock();
+	DoLocalInvalidateTLB();
+	ipi.QueueAllOther(&TTLBIPI::LocalInvalidateIsr);
+	NKern::Unlock();
+	ipi.WaitCompletion();
+	}
+
+void InvalidateTLB()
+	{
+	TTLBIPI ipi;
+	NKern::Lock();
+	DoInvalidateTLB();
+	ipi.QueueAllOther(&TTLBIPI::InvalidateIsr);
+	NKern::Unlock();
+	ipi.WaitCompletion();
+	}
+
+void InvalidateTLBForPage(TLinAddr aAddr)
+	{
+	TTLBIPI ipi;
+	ipi.AddAddress(aAddr);
+	ipi.InvalidateList();
+	}
+
+
+#endif // __SMP__
+
+
+void InvalidateTLBForAsid(TUint aAsid)
+	{
+	if(aAsid==KKernelOsAsid)
+		InvalidateTLB();
+	else
+		LocalInvalidateTLB();
+	}
+
+
+void SinglePdeUpdated(TPde* aPde)
+	{
+	CacheMaintenance::SinglePdeUpdated((TLinAddr)aPde);
+	PageDirectories.GlobalPdeChanged(aPde);
+	}
+
+
+//
+// Functions for class Mmu
+//
+
+TPhysAddr Mmu::PtePhysAddr(TPte aPte, TUint /*aPteIndex*/)
+	{
+	if(aPte&KPdePtePresent)
+		return aPte & KPdePtePhysAddrMask;
+	return KPhysAddrInvalid;
+	}
+
+
+TPte* Mmu::PageTableFromPde(TPde aPde)
+	{
+	if((aPde&(KPdeLargePage|KPdePtePresent)) == KPdePtePresent)
+		{
+		SPageInfo* pi = SPageInfo::FromPhysAddr(aPde);
+		TInt id = (pi->Index()<<KPtClusterShift) | ((aPde>>KPageTableShift)&KPtClusterMask);
+		return (TPte*)(KPageTableBase+(id<<KPageTableShift));
+		}
+	return 0;
+	}
+
+
+TPte* Mmu::SafePageTableFromPde(TPde aPde)
+	{
+	if((aPde&(KPdeLargePage|KPdePtePresent)) == KPdePtePresent)
+		{
+		SPageInfo* pi = SPageInfo::SafeFromPhysAddr(aPde&~KPageMask);
+		if(pi)
+			{
+			TInt id = (pi->Index()<<KPtClusterShift) | ((aPde>>KPageTableShift)&KPtClusterMask);
+			return (TPte*)(KPageTableBase+(id<<KPageTableShift));
+			}
+		}
+	return 0;
+	}
+
+
+/**
+Return the base phsical address of the section table referenced by the given
+Page Directory Entry (PDE) \a aPde. If the PDE doesn't refer to a
+section then KPhysAddrInvalid is returned.
+
+@pre #MmuLock held.
+*/
+TPhysAddr Mmu::SectionBaseFromPde(TPde aPde)
+	{
+	if(PdeMapsSection(aPde))
+	   return aPde&KPdeLargePagePhysAddrMask;
+	return KPhysAddrInvalid;
+	}
+
+
+TPte* Mmu::PtePtrFromLinAddr(TLinAddr aAddress, TInt aOsAsid)
+	{
+	TPde pde = PageDirectory(aOsAsid)[aAddress>>KChunkShift];
+	SPageInfo* pi = SPageInfo::FromPhysAddr(pde);
+	TPte* pt = (TPte*)(KPageTableBase+(pi->Index()<<KPageShift)+(pde&(KPageMask&~KPageTableMask)));
+	pt += (aAddress>>KPageShift)&(KChunkMask>>KPageShift);
+	return pt;
+	}
+
+
+TPte* Mmu::SafePtePtrFromLinAddr(TLinAddr aAddress, TInt aOsAsid)
+	{
+	TPde pde = PageDirectory(aOsAsid)[aAddress>>KChunkShift];
+	TPte* pt = SafePageTableFromPde(pde);
+	if(pt)
+		pt += (aAddress>>KPageShift)&(KChunkMask>>KPageShift);
+	return pt;
+	}
+
+
+TPhysAddr Mmu::PageTablePhysAddr(TPte* aPt)
+	{
+	__NK_ASSERT_DEBUG(MmuLock::IsHeld() || PageTablesLockIsHeld());
+
+	TInt pdeIndex = ((TLinAddr)aPt)>>KChunkShift;
+	TPde pde = PageDirectory(KKernelOsAsid)[pdeIndex];
+	__NK_ASSERT_DEBUG((pde&(KPdePtePresent|KPdeLargePage))==KPdePtePresent);
+
+	SPageInfo* pi = SPageInfo::FromPhysAddr(pde);
+	TPte* pPte = (TPte*)(KPageTableBase+(pi->Index(true)<<KPageShift));
+	TPte pte = pPte[(((TLinAddr)aPt)&KChunkMask)>>KPageShift];
+	__NK_ASSERT_DEBUG(pte & KPdePtePresent);
+
+	return pte&KPdePtePhysAddrMask;
+	}
+
+
+TPhysAddr Mmu::UncheckedLinearToPhysical(TLinAddr aLinAddr, TInt aOsAsid)
+	{
+	TRACE2(("Mmu::UncheckedLinearToPhysical(%08x,%d)",aLinAddr,aOsAsid));
+	TInt pdeIndex = aLinAddr>>KChunkShift;
+	TPde pde = PageDirectory(aOsAsid)[pdeIndex];
+	TPhysAddr pa=KPhysAddrInvalid;
+	if (pde & KPdePtePresent)
+		{
+		if(pde&KPdeLargePage)
+			{
+			pa=(pde&KPdeLargePagePhysAddrMask)+(aLinAddr&~KPdeLargePagePhysAddrMask);
+			__KTRACE_OPT(KMMU,Kern::Printf("Mapped with large table - returning %08x",pa));
+			}
+		else
+			{
+			SPageInfo* pi = SPageInfo::FromPhysAddr(pde);
+			TInt id = (pi->Index(true)<<KPtClusterShift) | ((pde>>KPageTableShift)&KPtClusterMask);
+			TPte* pPte = (TPte*)(KPageTableBase+(id<<KPageTableShift));
+			TPte pte = pPte[(aLinAddr&KChunkMask)>>KPageShift];
+			if (pte & KPdePtePresent)
+				{
+				pa=(pte&KPdePtePhysAddrMask)+(aLinAddr&KPageMask);
+				__KTRACE_OPT(KMMU,Kern::Printf("Mapped with page table - returning %08x",pa));
+				}
+			}
+		}
+	return pa;
+	}
+
+
+void Mmu::Init1()
+	{
+	TRACEB(("Mmu::Init1"));
+
+	TUint pge = TheSuperPage().iCpuId & EX86Feat_PGE;
+	PteGlobal = pge ? KPdePteGlobal : 0;
+	X86_UseGlobalPTEs = pge!=0;
+
+#ifdef __SMP__
+	ApTrampolinePage = KApTrampolinePageLin;
+
+	TInt i;
+	for (i=0; i<KMaxCpus; ++i)
+		{
+		TSubScheduler& ss = TheSubSchedulers[i];
+		TLinAddr a = KIPCAlias + (i<<KChunkShift);
+		ss.i_AliasLinAddr = (TAny*)a;
+		ss.i_AliasPdePtr = (TAny*)(KPageDirectoryBase + (a>>KChunkShift)*sizeof(TPde));
+		}
+#endif
+
+	Init1Common();
+	}
+
+void Mmu::Init2()
+	{
+	TRACEB(("Mmu::Init2"));
+
+	Init2Common();
+	}
+
+void Mmu::Init2Final()
+	{
+	TRACEB(("Mmu::Init2Final"));
+
+	Init2FinalCommon();
+	}
+
+
+const TPde KPdeForBlankPageTable = KPdePtePresent|KPdePteWrite|KPdePteUser;
+
+TPde Mmu::BlankPde(TMemoryAttributes aAttributes)
+	{
+	(void)aAttributes;
+	TPde pde = KPdeForBlankPageTable;
+	TRACE2(("Mmu::BlankPde(%x) returns 0x%x",aAttributes,pde));
+	return pde;
+	}
+
+
+TPde Mmu::BlankSectionPde(TMemoryAttributes aAttributes, TUint aPteType)
+	{
+	return PageToSectionEntry(BlankPte(aAttributes, aPteType), KPdeForBlankPageTable);
+	}
+
+
+TPte Mmu::BlankPte(TMemoryAttributes aAttributes, TUint aPteType)
+	{
+	TPte pte = KPdePtePresent;
+	if(aPteType&EPteTypeUserAccess)
+		pte |= KPdePteUser;
+	if(aPteType&EPteTypeWritable)
+		pte |= KPdePteWrite;
+	if(aPteType&EPteTypeGlobal)
+		pte |= PteGlobal;
+
+	switch((TMemoryType)(aAttributes&EMemoryAttributeTypeMask))
+		{
+	case EMemAttStronglyOrdered:
+	case EMemAttDevice:
+	case EMemAttNormalUncached:
+		pte |= KPdePteUncached;
+		break;
+	case EMemAttNormalCached:
+		break;
+	default:
+		__NK_ASSERT_ALWAYS(0);
+		break;
+		}
+
+	TRACE2(("Mmu::BlankPte(%x,%x) returns 0x%x",aAttributes,aPteType,pte));
+	return pte;
+	}
+
+
+TPte Mmu::SectionToPageEntry(TPde& aPde)
+	{
+	TPte pte = aPde&~(KPdePtePhysAddrMask|KPdeLargePage);
+	aPde = KPdeForBlankPageTable;
+	return pte;
+	}
+
+
+TPde Mmu::PageToSectionEntry(TPte aPte, TPde /*aPde*/)
+	{
+	TPte pde = aPte&~KPdeLargePagePhysAddrMask;
+	pde |= KPdeLargePage;
+	return pde;
+	}
+
+
+TMemoryAttributes Mmu::CanonicalMemoryAttributes(TMemoryAttributes aAttr)
+	{
+	TUint attr = aAttr;
+	if(attr&EMemoryAttributeDefaultShareable)
+		{
+		// sharing not specified, use default...
+#if defined	(__CPU_USE_SHARED_MEMORY)
+		attr |= EMemoryAttributeShareable;
+#else
+		attr &= ~EMemoryAttributeShareable;
+#endif
+		}
+
+	// remove invalid attributes...
+	attr &= ~(EMemoryAttributeUseECC);
+
+	return (TMemoryAttributes)(attr&EMemoryAttributeMask);
+	}
+
+
+void Mmu::PagesAllocated(TPhysAddr* aPageList, TUint aCount, TRamAllocFlags aFlags, TBool aReallocate)
+	{
+	TRACE2(("Mmu::PagesAllocated(0x%08x,%d,0x%x,%d)",aPageList, aCount, aFlags, (bool)aReallocate));
+	__NK_ASSERT_DEBUG(RamAllocLock::IsHeld());
+
+	TBool wipe = !(aFlags&EAllocNoWipe); // do we need to wipe page contents?
+	TMemoryType newType = (TMemoryType)(aFlags&KMemoryTypeMask); // memory type that pages will be used for
+	TUint8 wipeByte = (aFlags&EAllocUseCustomWipeByte) ? (aFlags>>EAllocWipeByteShift)&0xff : 0x03; // value to wipe memory with
+
+	// process each page in turn...
+	while(aCount--)
+		{
+		// get physical address of next page...
+		TPhysAddr pagePhys;
+		if((TPhysAddr)aPageList&1)
+			{
+			// aPageList is actually the physical address to use...
+			pagePhys = (TPhysAddr)aPageList&~1;
+			*(TPhysAddr*)&aPageList += KPageSize;
+			}
+		else
+			pagePhys = *aPageList++;
+		__NK_ASSERT_DEBUG((pagePhys&KPageMask)==0);
+
+		// get info about page...
+		SPageInfo* pi = SPageInfo::FromPhysAddr(pagePhys);
+		TMemoryType oldType = (TMemoryType)(pi->Flags(true)&KMemoryTypeMask);
+
+		TRACE2(("Mmu::PagesAllocated page=0x%08x, oldType=%d, wipe=%d",pagePhys,oldType,wipe));
+		if(wipe)
+			{
+			// work out temporary mapping values...
+			TLinAddr tempLinAddr = iTempMap[0].iLinAddr;
+			TPte* tempPte = iTempMap[0].iPtePtr;
+
+			// temporarily map page...
+			*tempPte = pagePhys | iTempPteCached;
+			CacheMaintenance::SinglePteUpdated((TLinAddr)tempPte);
+			InvalidateTLBForPage(tempLinAddr|KKernelOsAsid);
+
+			// wipe contents of memory...
+			memset((TAny*)tempLinAddr, wipeByte, KPageSize);
+			__e32_io_completion_barrier();
+
+			// invalidate temporary mapping...
+			*tempPte = KPteUnallocatedEntry;
+			CacheMaintenance::SinglePteUpdated((TLinAddr)tempPte);
+			InvalidateTLBForPage(tempLinAddr|KKernelOsAsid);
+			}
+
+		// indicate page has been allocated...
+		if(aReallocate==false)
+			pi->SetAllocated();
+		}
+	}
+
+
+void Mmu::PageFreed(SPageInfo* aPageInfo)
+	{
+	__NK_ASSERT_DEBUG(MmuLock::IsHeld());
+
+	if(aPageInfo->Type()==SPageInfo::EUnused)
+		return;
+
+	aPageInfo->SetUnused();
+
+	TRACE2(("Mmu::PageFreed page=0x%08x type=%d colour=%d",aPageInfo->PhysAddr(),aPageInfo->Flags()&KMemoryTypeMask,aPageInfo->Index()&KPageColourMask));
+	}
+
+
+void Mmu::CleanAndInvalidatePages(TPhysAddr* aPages, TUint aCount, TMemoryAttributes aAttributes, TUint aColour)
+	{
+	TMemoryType type = (TMemoryType)(aAttributes&EMemoryAttributeTypeMask);
+	if(!CacheMaintenance::IsCached(type))
+		{
+		TRACE2(("Mmu::CleanAndInvalidatePages - nothing to do"));
+		return;
+		}
+
+	RamAllocLock::Lock();
+
+	while(aCount--)
+		{
+		TPhysAddr pagePhys = *aPages++;
+		TRACE2(("Mmu::CleanAndInvalidatePages 0x%08x",pagePhys));
+
+		// work out temporary mapping values...
+		TLinAddr tempLinAddr = iTempMap[0].iLinAddr;
+		TPte* tempPte = iTempMap[0].iPtePtr;
+
+		// temporarily map page...
+		*tempPte = pagePhys | iTempPteCached;
+		CacheMaintenance::SinglePteUpdated((TLinAddr)tempPte);
+		InvalidateTLBForPage(tempLinAddr|KKernelOsAsid);
+
+		// sort out cache for memory reuse...
+		CacheMaintenance::PageToPreserveAndReuse(tempLinAddr, type, KPageSize);
+
+		// invalidate temporary mapping...
+		*tempPte = KPteUnallocatedEntry;
+		CacheMaintenance::SinglePteUpdated((TLinAddr)tempPte);
+		InvalidateTLBForPage(tempLinAddr|KKernelOsAsid);
+
+		RamAllocLock::Flash();
+		}
+	RamAllocLock::Unlock();
+	}
+
+
+TInt DMemModelThread::Alias(TLinAddr aAddr, DMemModelProcess* aProcess, TInt aSize, TLinAddr& aAliasAddr, TUint& aAliasSize)
+//
+// Set up an alias mapping starting at address aAddr in specified process.
+// Note: Alias is removed if an exception is trapped by DThread::IpcExcHandler.
+//
+	{
+	TRACE2(("Thread %O Alias %08x+%x Process %O",this,aAddr,aSize,aProcess));
+	__NK_ASSERT_DEBUG(this==TheCurrentThread); // many bad things can happen if false
+	// If there is an existing alias it should be on the same process otherwise
+	// the os asid reference may be leaked.
+	__NK_ASSERT_DEBUG(!iAliasLinAddr || aProcess == iAliasProcess);
+
+	if(TUint(aAddr^KIPCAlias)<TUint(KIPCAliasAreaSize))
+		return KErrBadDescriptor; // prevent access to alias region
+
+	// Grab the mmu lock before opening a reference on os asid so that this thread 
+	// is in an implicit critical section and therefore can't leak the reference by
+	// dying before iAliasLinAddr is set.
+	MmuLock::Lock();
+
+	TInt osAsid;
+	if (!iAliasLinAddr)
+		{// There isn't any existing alias.
+		// Open a reference on the aProcess's os asid so that it is not freed and/or reused
+		// while we are aliasing an address belonging to it.
+		osAsid = aProcess->TryOpenOsAsid();
+		if (osAsid < 0)
+			{// Couldn't open os asid so aProcess is no longer running.
+			MmuLock::Unlock();
+			return KErrBadDescriptor;
+			}
+		}
+	else
+		{
+		// Just read the os asid of the process being aliased we already have a reference on it.
+		osAsid = aProcess->OsAsid();
+		}
+
+	// Now we have the os asid check access to kernel memory.
+	if(aAddr >= KUserMemoryLimit && osAsid != (TUint)KKernelOsAsid)
+		{
+		if (!iAliasLinAddr)
+			{// Close the new reference as RemoveAlias won't do as iAliasLinAddr is not set.
+			aProcess->AsyncCloseOsAsid();
+			}
+		MmuLock::Unlock();
+		return KErrBadDescriptor; // prevent access to supervisor only memory
+		}
+
+	// Now we know all accesses to global memory are safe so check if aAddr is global.
+	if(aAddr >= KGlobalMemoryBase)
+		{
+		// address is in global section, don't bother aliasing it...
+		if (!iAliasLinAddr)
+			{// Close the new reference as not required.
+			aProcess->AsyncCloseOsAsid();
+			}
+		else
+			{// Remove the existing alias as it is not required.
+			DoRemoveAlias(iAliasLinAddr);
+			}
+		MmuLock::Unlock();
+		aAliasAddr = aAddr;
+		TInt maxSize = KChunkSize-(aAddr&KChunkMask);
+		aAliasSize = aSize<maxSize ? aSize : maxSize;
+		TRACE2(("DMemModelThread::Alias() abandoned as memory is globally mapped"));
+		return KErrNone;
+		}
+
+	TPde* pd = Mmu::PageDirectory(osAsid);
+	TInt pdeIndex = aAddr>>KChunkShift;
+	TPde pde = pd[pdeIndex];
+#ifdef __SMP__
+	TLinAddr aliasAddr;
+#else
+	TLinAddr aliasAddr = KIPCAlias+(aAddr&(KChunkMask & ~KPageMask));
+#endif
+	if(pde==iAliasPde && iAliasLinAddr)
+		{
+		// pde already aliased, so just update linear address...
+#ifdef __SMP__
+		__NK_ASSERT_DEBUG(iCpuRestoreCookie>=0);
+		aliasAddr = iAliasLinAddr & ~KChunkMask;
+		aliasAddr |= (aAddr & (KChunkMask & ~KPageMask));
+#endif
+		iAliasLinAddr = aliasAddr;
+		}
+	else
+		{
+		// alias PDE changed...
+		if(!iAliasLinAddr)
+			{
+			TheMmu.iAliasList.Add(&iAliasLink); // add to list if not already aliased
+#ifdef __SMP__
+			__NK_ASSERT_DEBUG(iCpuRestoreCookie==-1);
+			iCpuRestoreCookie = NKern::FreezeCpu();	// temporarily lock current thread to this processor
+#endif
+			}
+		iAliasPde = pde;
+		iAliasProcess = aProcess;
+#ifdef __SMP__
+		TSubScheduler& ss = SubScheduler();		// OK since we are locked to this CPU
+		aliasAddr = TLinAddr(ss.i_AliasLinAddr) + (aAddr & (KChunkMask & ~KPageMask));
+		iAliasPdePtr = (TPde*)(TLinAddr(ss.i_AliasPdePtr) + (osAsid << KPageTableShift));
+#endif
+		iAliasLinAddr = aliasAddr;
+		*iAliasPdePtr = pde;
+		}
+	TRACE2(("DMemModelThread::Alias() PDEntry=%x, iAliasLinAddr=%x",pde, aliasAddr));
+	LocalInvalidateTLBForPage(aliasAddr);
+	TInt offset = aAddr&KPageMask;
+	aAliasAddr = aliasAddr | offset;
+	TInt maxSize = KPageSize - offset;
+	aAliasSize = aSize<maxSize ? aSize : maxSize;
+	iAliasTarget = aAddr & ~KPageMask;
+
+	MmuLock::Unlock();
+
+	return KErrNone;
+	}
+
+
+void DMemModelThread::RemoveAlias()
+//
+// Remove alias mapping (if present)
+//
+	{
+	TRACE2(("Thread %O RemoveAlias", this));
+	__NK_ASSERT_DEBUG(this==TheCurrentThread); // many bad things can happen if false
+
+	TLinAddr addr = iAliasLinAddr;
+	if(addr)
+		{
+		MmuLock::Lock();
+
+		DoRemoveAlias(addr);
+
+		MmuLock::Unlock();
+		}
+	}
+
+
+/**
+Remove the alias mapping.
+
+@pre Mmulock held
+*/
+void DMemModelThread::DoRemoveAlias(TLinAddr aAddr)
+	{
+	iAliasLinAddr = 0;
+	iAliasPde = KPdeUnallocatedEntry;
+	*iAliasPdePtr = KPdeUnallocatedEntry;
+	SinglePdeUpdated(iAliasPdePtr);
+	__NK_ASSERT_DEBUG((aAddr&KPageMask)==0);
+	LocalInvalidateTLBForPage(aAddr);
+	iAliasLink.Deque();
+#ifdef __SMP__
+	__NK_ASSERT_DEBUG(iCpuRestoreCookie>=0);
+	NKern::EndFreezeCpu(iCpuRestoreCookie);
+	iCpuRestoreCookie = -1;
+#endif
+	// Must close the os asid while the mmu lock is held to prevent it being 
+	// leaked, however this requires that it is closed asynchronously as can't
+	// delete os asid with mmu lock held.
+	iAliasProcess->AsyncCloseOsAsid();
+	}
+
+
+TInt M::DemandPagingFault(TAny* aExceptionInfo)
+	{
+	TX86ExcInfo& exc=*(TX86ExcInfo*)aExceptionInfo;
+	if(exc.iExcId!=EX86VectorPageFault)
+		return KErrAbort; // not a page fault
+
+	/*
+	Meanings of exc.iExcErrorCode when exception type is EX86VectorPageFault...
+
+	Bit 0	0 The fault was caused by a non-present page.
+			1 The fault was caused by a page-level protection violation.
+	Bit 1	0 The access causing the fault was a read.
+			1 The access causing the fault was a write.
+	Bit 2	0 The access causing the fault originated when the processor was executing in supervisor mode.
+			1 The access causing the fault originated when the processor was executing in user mode.   
+	Bit 3	0 The fault was not caused by reserved bit violation.
+			1 The fault was caused by reserved bits set to 1 in a page directory.
+	Bit 4	0 The fault was not caused by an instruction fetch.
+			1 The fault was caused by an instruction fetch.
+	*/
+
+	// check access type...
+	TUint accessPermissions = EUser; // we only allow paging of user memory
+	if(exc.iExcErrorCode&(1<<1))
+		accessPermissions |= EReadWrite;
+
+	// let TheMmu handle the fault...
+	return TheMmu.HandlePageFault(exc.iEip, exc.iFaultAddress, accessPermissions, aExceptionInfo);
+	}
+
+