NTSTATUS NTAPI VdmpStartExecution ( VOID )
Definition at line 171 of file vdmexec.c.
{
    PETHREAD Thread = PsGetCurrentThread();
    PKTRAP_FRAME VdmFrame;
    NTSTATUS Status;
    PVDM_TIB VdmTib;
    BOOLEAN Interrupts;
    KIRQL OldIrql;
    CONTEXT VdmContext;
    PAGED_CODE();

    /* Get the thread's VDM frame and TIB */
    VdmFrame = (PVOID)((ULONG_PTR)Thread->Tcb.InitialStack -
                                  sizeof(FX_SAVE_AREA) -
                                  sizeof(KTRAP_FRAME));
    Status = VdmpGetVdmTib(&VdmTib);
    if (!NT_SUCCESS(Status)) return STATUS_INVALID_SYSTEM_SERVICE;

    /* Go to APC level */
    KeRaiseIrql(APC_LEVEL, &OldIrql);

    /* Check if interrupts are enabled */
    Interrupts = (BOOLEAN)(VdmTib->VdmContext.EFlags & EFLAGS_INTERRUPT_MASK);

    /* We don't support full VDM yet, this shouldn't happen */
    ASSERT(*VdmState == 0);
    ASSERT(VdmTib->VdmContext.EFlags & EFLAGS_V86_MASK);

    /* Check if VME is supported and V86 mode was enabled */
    if ((KeI386VirtualIntExtensions) &&
        (VdmTib->VdmContext.EFlags & EFLAGS_V86_MASK))
    {
        /* Check if interrupts are enabled */
        if (Interrupts)
        {
            /* Set fake IF flag */
            VdmTib->VdmContext.EFlags |= EFLAGS_VIF;
        }
        else
        {
            /* Remove fake IF flag, turn on real IF flag */
            VdmTib->VdmContext.EFlags &= ~EFLAGS_VIF;
            VdmTib->VdmContext.EFlags |= EFLAGS_INTERRUPT_MASK;
        }
    }
    else
    {
        /* Set interrupt state in the VDM State */
        if (VdmTib->VdmContext.EFlags & EFLAGS_INTERRUPT_MASK)
        {
            /* Enable them as well */
            InterlockedOr((PLONG)VdmState, EFLAGS_INTERRUPT_MASK);
        }
        else
        {
            /* Disable them */
            InterlockedAnd((PLONG)VdmState, ~EFLAGS_INTERRUPT_MASK);
        }

        /* Enable the interrupt flag */
        VdmTib->VdmContext.EFlags |= EFLAGS_INTERRUPT_MASK;
    }

    /*  Get the VDM context and make sure it's not an edited frame */
    VdmContext = VdmTib->VdmContext;
    if (!(VdmContext.SegCs & FRAME_EDITED))
    {
        /* Fail */
        KeLowerIrql(OldIrql);
        return STATUS_INVALID_SYSTEM_SERVICE;
    }
    
    /* Now do the VDM Swap */
    VdmSwapContext(VdmFrame, &VdmTib->MonitorContext, &VdmContext);

    /* Lower the IRQL and return EAX */
    KeLowerIrql(OldIrql);
    return VdmFrame->Eax;
}
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