NTSTATUS NTAPI MiCreatePagingFileMap	(	OUT PSEGMENT *	Segment,
		IN PSIZE_T	MaximumSize,
		IN ULONG	ProtectionMask,
		IN ULONG	AllocationAttributes
	)
Definition at line 1119 of file section.c.
Referenced by MmCreateArm3Section().
{
    SIZE_T SizeLimit;
    PFN_COUNT PteCount;
    PMMPTE PointerPte;
    MMPTE TempPte;
    PCONTROL_AREA ControlArea;
    PSEGMENT NewSegment;
    PSUBSECTION Subsection;
    PAGED_CODE();

    /* No large pages in ARM3 yet */
    ASSERT((AllocationAttributes & SEC_LARGE_PAGES) == 0);

    /* Pagefile-backed sections need a known size */
    if (!(*MaximumSize)) return STATUS_INVALID_PARAMETER_4;

    /* Calculate the maximum size possible, given the Prototype PTEs we'll need */
    SizeLimit = MAXULONG_PTR - sizeof(SEGMENT);
    SizeLimit /= sizeof(MMPTE);
    SizeLimit <<= PAGE_SHIFT;

    /* Fail if this size is too big */
    if (*MaximumSize > SizeLimit) return STATUS_SECTION_TOO_BIG;

    /* Calculate how many Prototype PTEs will be needed */
    PteCount = (PFN_COUNT)((*MaximumSize + PAGE_SIZE - 1) >> PAGE_SHIFT);

    /* For commited memory, we must have a valid protection mask */
    if (AllocationAttributes & SEC_COMMIT) ASSERT(ProtectionMask != 0);

    /* The segment contains all the Prototype PTEs, allocate it in paged pool */
    NewSegment = ExAllocatePoolWithTag(PagedPool,
                                       sizeof(SEGMENT) +
                                       sizeof(MMPTE) * (PteCount - 1),
                                       'tSmM');
    ASSERT(NewSegment);
    *Segment = NewSegment;

    /* Now allocate the control area, which has the subsection structure */
    ControlArea = ExAllocatePoolWithTag(NonPagedPool,
                                        sizeof(CONTROL_AREA) + sizeof(SUBSECTION),
                                        'tCmM');
    ASSERT(ControlArea);

    /* And zero it out, filling the basic segmnet pointer and reference fields */
    RtlZeroMemory(ControlArea, sizeof(CONTROL_AREA) + sizeof(SUBSECTION));
    ControlArea->Segment = NewSegment;
    ControlArea->NumberOfSectionReferences = 1;
    ControlArea->NumberOfUserReferences = 1;

    /* Convert allocation attributes to control area flags */
    if (AllocationAttributes & SEC_BASED) ControlArea->u.Flags.Based = 1;
    if (AllocationAttributes & SEC_RESERVE) ControlArea->u.Flags.Reserve = 1;
    if (AllocationAttributes & SEC_COMMIT) ControlArea->u.Flags.Commit = 1;

    /* The subsection follows, write the mask, PTE count and point back to the CA */
    Subsection = (PSUBSECTION)(ControlArea + 1);
    Subsection->ControlArea = ControlArea;
    Subsection->PtesInSubsection = PteCount;
    Subsection->u.SubsectionFlags.Protection = ProtectionMask;

    /* Zero out the segment's prototype PTEs, and link it with the control area */
    PointerPte = &NewSegment->ThePtes[0];
    RtlZeroMemory(NewSegment, sizeof(SEGMENT));
    NewSegment->PrototypePte = PointerPte;
    NewSegment->ControlArea = ControlArea;

    /* Save some extra accounting data for the segment as well */
    NewSegment->u1.CreatingProcess = PsGetCurrentProcess();
    NewSegment->SizeOfSegment = PteCount * PAGE_SIZE;
    NewSegment->TotalNumberOfPtes = PteCount;
    NewSegment->NonExtendedPtes = PteCount;

    /* The subsection's base address is the first Prototype PTE in the segment */
    Subsection->SubsectionBase = PointerPte;

    /* Start with an empty PTE, unless this is a commit operation */
    TempPte.u.Long = 0;
    if (AllocationAttributes & SEC_COMMIT)
    {
        /* In which case, write down the protection mask in the Prototype PTEs */
        TempPte.u.Soft.Protection = ProtectionMask;

        /* For accounting, also mark these pages as being committed */
        NewSegment->NumberOfCommittedPages = PteCount;
    }

    /* The template PTE itself for the segment should also have the mask set */
    NewSegment->SegmentPteTemplate.u.Soft.Protection = ProtectionMask;

    /* Write out the prototype PTEs, for now they're simply demand zero */
#ifdef _WIN64
    RtlFillMemoryUlonglong(PointerPte, PteCount * sizeof(MMPTE), TempPte.u.Long);
#else
    RtlFillMemoryUlong(PointerPte, PteCount * sizeof(MMPTE), TempPte.u.Long);
#endif
    return STATUS_SUCCESS;
}
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