VOID
MmZeroPageThread (
VOID
)
/*++
Routine Description:
Implements the NT zeroing page thread. This thread runs
at priority zero and removes a page from the free list,
zeroes it, and places it on the zeroed page list.
Arguments:
StartContext - not used.
Return Value:
None.
Environment:
Kernel mode.
--*/
{
PVOID EndVa;
KIRQL OldIrql;
ULONG PageFrame;
PMMPFN Pfn1;
PVOID StartVa;
PKTHREAD Thread;
PVOID ZeroBase;
ULONG i;
//
// Before this becomes the zero page thread, free the kernel
// initialization code.
//
MiFindInitializationCode (&StartVa, &EndVa);
if (StartVa != NULL) {
MiFreeInitializationCode (StartVa, EndVa);
}
//
// The following code sets the current thread's base priority to zero
// and then sets its current priority to zero. This ensures that the
// thread always runs at a priority of zero.
//
Thread = KeGetCurrentThread();
Thread->BasePriority = 0;
KeSetPriorityThread (Thread, 0);
//
// Loop forever zeroing pages.
//
do {
//
// Wait until there are at least MmZeroPageMinimum pages
// on the free list.
//
KeWaitForSingleObject (&MmZeroingPageEvent,
WrFreePage,
KernelMode,
FALSE,
(PLARGE_INTEGER)NULL);
LOCK_PFN_WITH_TRY (OldIrql);
do {
if ((volatile)MmFreePageListHead.Total == 0) {
//
// No pages on the free list at this time, wait for
// some more.
//
MmZeroingPageThreadActive = FALSE;
UNLOCK_PFN (OldIrql);
break;
} else {
#if MM_MAXIMUM_NUMBER_OF_COLORS > 1
for (i = 0; i < MM_MAXIMUM_NUMBER_OF_COLORS; i++) {
PageFrame = MmFreePagesByPrimaryColor[FreePageList][i].Flink;
if (PageFrame != MM_EMPTY_LIST) {
break;
}
}
#else //MM_MAXIMUM_NUMBER_OF_COLORS > 1
PageFrame = MmFreePageListHead.Flink;
#endif //MM_MAXIMUM_NUMBER_OF_COLORS > 1
Pfn1 = MI_PFN_ELEMENT(PageFrame);
ASSERT (PageFrame != MM_EMPTY_LIST);
Pfn1 = MI_PFN_ELEMENT(PageFrame);
MiRemoveAnyPage (MI_GET_SECONDARY_COLOR (PageFrame, Pfn1));
//
// Zero the page using the last color used to map the page.
//
#if defined(_X86_)
ZeroBase = MiMapPageToZeroInHyperSpace (PageFrame);
UNLOCK_PFN (OldIrql);
RtlZeroMemory (ZeroBase, PAGE_SIZE);
#elif defined(_PPC_)
UNLOCK_PFN (OldIrql);
KeZeroPage(PageFrame);
#else
ZeroBase = (PVOID)(Pfn1->u3.e1.PageColor << PAGE_SHIFT);
UNLOCK_PFN (OldIrql);
HalZeroPage(ZeroBase, ZeroBase, PageFrame);
#endif //X86
LOCK_PFN_WITH_TRY (OldIrql);
MiInsertPageInList (MmPageLocationList[ZeroedPageList],
PageFrame);
}
} while(TRUE);
} while (TRUE);
}
VOID
NTAPI
MmZeroPageThread(VOID)
{
PKTHREAD Thread = KeGetCurrentThread();
PVOID StartAddress, EndAddress;
PVOID WaitObjects[2];
KIRQL OldIrql;
PVOID ZeroAddress;
PFN_NUMBER PageIndex, FreePage;
PMMPFN Pfn1;
/* Get the discardable sections to free them */
MiFindInitializationCode(&StartAddress, &EndAddress);
if (StartAddress) MiFreeInitializationCode(StartAddress, EndAddress);
DPRINT("Free non-cache pages: %lx\n", MmAvailablePages + MiMemoryConsumers[MC_CACHE].PagesUsed);
/* Set our priority to 0 */
Thread->BasePriority = 0;
KeSetPriorityThread(Thread, 0);
/* Setup the wait objects */
WaitObjects[0] = &MmZeroingPageEvent;
// WaitObjects[1] = &PoSystemIdleTimer; FIXME: Implement idle timer
while (TRUE)
{
KeWaitForMultipleObjects(1, // 2
WaitObjects,
WaitAny,
WrFreePage,
KernelMode,
FALSE,
NULL,
NULL);
OldIrql = KeAcquireQueuedSpinLock(LockQueuePfnLock);
while (TRUE)
{
if (!MmFreePageListHead.Total)
{
MmZeroingPageThreadActive = FALSE;
KeReleaseQueuedSpinLock(LockQueuePfnLock, OldIrql);
break;
}
PageIndex = MmFreePageListHead.Flink;
ASSERT(PageIndex != LIST_HEAD);
Pfn1 = MiGetPfnEntry(PageIndex);
MI_SET_USAGE(MI_USAGE_ZERO_LOOP);
MI_SET_PROCESS2("Kernel 0 Loop");
FreePage = MiRemoveAnyPage(MI_GET_PAGE_COLOR(PageIndex));
/* The first global free page should also be the first on its own list */
if (FreePage != PageIndex)
{
KeBugCheckEx(PFN_LIST_CORRUPT,
0x8F,
FreePage,
PageIndex,
0);
}
Pfn1->u1.Flink = LIST_HEAD;
KeReleaseQueuedSpinLock(LockQueuePfnLock, OldIrql);
ZeroAddress = MiMapPagesInZeroSpace(Pfn1, 1);
ASSERT(ZeroAddress);
RtlZeroMemory(ZeroAddress, PAGE_SIZE);
MiUnmapPagesInZeroSpace(ZeroAddress, 1);
OldIrql = KeAcquireQueuedSpinLock(LockQueuePfnLock);
MiInsertPageInList(&MmZeroedPageListHead, PageIndex);
}
}
}
