294 lines
7.0 KiB
C
294 lines
7.0 KiB
C
/*++
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Copyright (c) 1989 Microsoft Corporation
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Module Name:
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pfndec.c
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Abstract:
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This module contains the routines to decrement the share count and
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the reference counts within the Page Frame Database.
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Author:
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Lou Perazzoli (loup) 5-Apr-1989
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Landy Wang (landyw) 2-Jun-1997
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Revision History:
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--*/
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#include "mi.h"
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ULONG MmFrontOfList;
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VOID
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FASTCALL
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MiDecrementShareCount (
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IN PFN_NUMBER PageFrameIndex
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)
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/*++
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Routine Description:
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This routine decrements the share count within the PFN element
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for the specified physical page. If the share count becomes
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zero the corresponding PTE is converted to the transition state
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and the reference count is decremented and the ValidPte count
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of the PTEframe is decremented.
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Arguments:
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PageFrameIndex - Supplies the physical page number of which to decrement
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the share count.
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Return Value:
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None.
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Environment:
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Must be holding the PFN database mutex with APCs disabled.
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--*/
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{
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MMPTE TempPte;
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PMMPTE PointerPte;
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PMMPFN Pfn1;
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KIRQL OldIrql;
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ASSERT ((PageFrameIndex <= MmHighestPhysicalPage) &&
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(PageFrameIndex > 0));
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Pfn1 = MI_PFN_ELEMENT (PageFrameIndex);
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if (Pfn1->u3.e1.PageLocation != ActiveAndValid &&
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Pfn1->u3.e1.PageLocation != StandbyPageList) {
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KeBugCheckEx (PFN_LIST_CORRUPT,
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0x99,
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PageFrameIndex,
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Pfn1->u3.e1.PageLocation,
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0);
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}
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#if PFN_CONSISTENCY
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if (Pfn1->u3.e1.PageTablePage == 1) {
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// Need to run the page and see if the number of transition & valid
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// pages + 1 matches up to the share count.
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// For the page being freed (share == 1), need to snap the caller here
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}
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#endif
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Pfn1->u2.ShareCount -= 1;
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PERFINFO_DECREFCNT(Pfn1, PERFINFO_LOG_WSCHANGE, PERFINFO_LOG_TYPE_DECSHARCNT)
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ASSERT (Pfn1->u2.ShareCount < 0xF000000);
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if (Pfn1->u2.ShareCount == 0) {
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PERFINFO_DECREFCNT(Pfn1, PERFINFO_LOG_EMPTYQ, PERFINFO_LOG_TYPE_ZEROSHARECOUNT)
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// The share count is now zero, decrement the reference count
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// for the PFN element and turn the referenced PTE into
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// the transition state if it refers to a prototype PTE.
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// PTEs which are not prototype PTEs do not need to be placed
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// into transition as they are placed in transition when
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// they are removed from the working set (working set free routine).
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// If the PTE referenced by this PFN element is actually
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// a prototype PTE, it must be mapped into hyperspace and
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// then operated on.
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if (Pfn1->u3.e1.PrototypePte == 1) {
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OldIrql = 99;
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if (MmIsAddressValid (Pfn1->PteAddress)) {
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PointerPte = Pfn1->PteAddress;
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} else {
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// The address is not valid in this process, map it into
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// hyperspace so it can be operated upon.
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PointerPte = (PMMPTE)MiMapPageInHyperSpace(Pfn1->PteFrame,
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&OldIrql);
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PointerPte = (PMMPTE)((PCHAR)PointerPte +
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MiGetByteOffset(Pfn1->PteAddress));
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}
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TempPte = *PointerPte;
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MI_MAKE_VALID_PTE_TRANSITION (TempPte,
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Pfn1->OriginalPte.u.Soft.Protection);
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MI_WRITE_INVALID_PTE (PointerPte, TempPte);
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if (OldIrql != 99) {
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MiUnmapPageInHyperSpace (OldIrql);
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}
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// There is no need to flush the translation buffer at this
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// time as we only invalidated a prototype PTE.
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}
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// Change the page location to inactive (from active and valid).
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Pfn1->u3.e1.PageLocation = TransitionPage;
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// Decrement the reference count as the share count is now zero.
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MiDecrementReferenceCount (PageFrameIndex);
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}
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return;
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}
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VOID
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FASTCALL
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MiDecrementReferenceCount (
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IN PFN_NUMBER PageFrameIndex
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)
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/*++
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Routine Description:
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This routine decrements the reference count for the specified page.
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If the reference count becomes zero, the page is placed on the
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appropriate list (free, modified, standby or bad). If the page
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is placed on the free or standby list, the number of available
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pages is incremented and if it transitions from zero to one, the
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available page event is set.
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Arguments:
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PageFrameIndex - Supplies the physical page number of which to
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decrement the reference count.
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Return Value:
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none.
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Environment:
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Must be holding the PFN database mutex with APCs disabled.
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--*/
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{
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PMMPFN Pfn1;
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MM_PFN_LOCK_ASSERT();
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ASSERT (PageFrameIndex <= MmHighestPhysicalPage);
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Pfn1 = MI_PFN_ELEMENT (PageFrameIndex);
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ASSERT (Pfn1->u3.e2.ReferenceCount != 0);
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Pfn1->u3.e2.ReferenceCount -= 1;
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if (Pfn1->u3.e2.ReferenceCount != 0) {
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// The reference count is not zero, return.
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return;
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}
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// The reference count is now zero, put the page on some
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// list.
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if (Pfn1->u2.ShareCount != 0) {
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KeBugCheckEx (PFN_LIST_CORRUPT,
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7,
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PageFrameIndex,
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Pfn1->u2.ShareCount,
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0);
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return;
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}
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ASSERT (Pfn1->u3.e1.PageLocation != ActiveAndValid);
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if (MI_IS_PFN_DELETED (Pfn1)) {
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// There is no referenced PTE for this page, delete the page file
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// space (if any), and place the page on the free list.
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MiReleasePageFileSpace (Pfn1->OriginalPte);
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if (Pfn1->u3.e1.RemovalRequested == 1) {
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MiInsertPageInList (MmPageLocationList[BadPageList],
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PageFrameIndex);
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}
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else {
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MiInsertPageInList (MmPageLocationList[FreePageList],
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PageFrameIndex);
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}
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return;
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}
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// Place the page on the modified or standby list depending
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// on the state of the modify bit in the PFN element.
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if (Pfn1->u3.e1.Modified == 1) {
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MiInsertPageInList (MmPageLocationList[ModifiedPageList], PageFrameIndex);
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} else {
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if (Pfn1->u3.e1.RemovalRequested == 1) {
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// The page may still be marked as on the modified list if the
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// current thread is the modified writer completing the write.
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// Mark it as standby so restoration of the transition PTE
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// doesn't flag this as illegal.
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Pfn1->u3.e1.PageLocation = StandbyPageList;
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MiRestoreTransitionPte (PageFrameIndex);
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MiInsertPageInList (MmPageLocationList[BadPageList],
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PageFrameIndex);
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return;
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}
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if (!MmFrontOfList) {
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MiInsertPageInList (MmPageLocationList[StandbyPageList],
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PageFrameIndex);
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} else {
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MiInsertStandbyListAtFront (PageFrameIndex);
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}
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}
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return;
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}
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