reactos/ntoskrnl/ke/i386/v86vdm.c

   1 /*
   2  * PROJECT:         ReactOS Kernel
   3  * LICENSE:         GPL - See COPYING in the top level directory
   4  * FILE:            ntoskrnl/ke/i386/v86vdm.c
   5  * PURPOSE:         Manages the Kernel's support for Virtual-8086 Mode (V86)
   6  *                  used by Video Drivers to access ROM BIOS functions, as well
   7  *                  as the kernel architecture part of generic VDM support.
   8  * PROGRAMMERS:     Alex Ionescu (alex.ionescu@reactos.org)
   9  */
  10
  11 /* INCLUDES ******************************************************************/
  12
  13 #include <ntoskrnl.h>
  14 #define NDEBUG
  15 #include <debug.h>
  16
  17 /* GLOBALS *******************************************************************/
  18
  19 ULONG KeI386EFlagsAndMaskV86 = EFLAGS_USER_SANITIZE;
  20 ULONG KeI386EFlagsOrMaskV86 = EFLAGS_INTERRUPT_MASK;
  21 PVOID Ki386IopmSaveArea;
  22 BOOLEAN KeI386VirtualIntExtensions = FALSE;
  23
  24 /* PRIVATE FUNCTIONS *********************************************************/
  25
  26 /* PUBLIC FUNCTIONS **********************************************************/
  27
  28 /*
  29  * @implemented
  30  */
  31 NTSTATUS
  32 NTAPI
  33 Ke386CallBios(IN ULONG Int,
  34               OUT PCONTEXT Context)
  35 {
  36     PUCHAR Trampoline = (PUCHAR)TRAMPOLINE_BASE;
  37     PTEB VdmTeb = (PTEB)TRAMPOLINE_TEB;
  38     PVDM_TIB VdmTib = (PVDM_TIB)TRAMPOLINE_TIB;
  39     ULONG ContextSize = FIELD_OFFSET(CONTEXT, ExtendedRegisters);
  40     PKTHREAD Thread = KeGetCurrentThread();
  41     PKTSS Tss = KeGetPcr()->TSS;
  42     PKPROCESS Process = Thread->ApcState.Process;
  43     PVDM_PROCESS_OBJECTS VdmProcessObjects;
  44     USHORT OldOffset, OldBase;
  45
  46     /* Start with a clean TEB */
  47     RtlZeroMemory(VdmTeb, sizeof(TEB));
  48
  49     /* Write the interrupt and bop */
  50     *Trampoline++ = 0xCD;
  51     *Trampoline++ = (UCHAR)Int;
  52     *(PULONG)Trampoline = TRAMPOLINE_BOP;
  53
  54     /* Setup the VDM TEB and TIB */
  55     VdmTeb->Vdm = (PVOID)TRAMPOLINE_TIB;
  56     RtlZeroMemory(VdmTib, sizeof(VDM_TIB));
  57     VdmTib->Size = sizeof(VDM_TIB);
  58
  59     /* Set a blank VDM state */
  60     *VdmState = 0;
  61
  62     /* Copy the context */
  63     RtlCopyMemory(&VdmTib->VdmContext, Context, ContextSize);
  64     VdmTib->VdmContext.SegCs = (ULONG_PTR)Trampoline >> 4;
  65     VdmTib->VdmContext.SegSs = (ULONG_PTR)Trampoline >> 4;
  66     VdmTib->VdmContext.Eip = 0;
  67     VdmTib->VdmContext.Esp = 2 * PAGE_SIZE - sizeof(ULONG_PTR);
  68     VdmTib->VdmContext.EFlags |= EFLAGS_V86_MASK | EFLAGS_INTERRUPT_MASK;
  69     VdmTib->VdmContext.ContextFlags = CONTEXT_FULL;
  70
  71     /* This can't be a real VDM process */
  72     ASSERT(PsGetCurrentProcess()->VdmObjects == NULL);
  73
  74     /* Allocate VDM structure */
  75     VdmProcessObjects = ExAllocatePoolWithTag(NonPagedPool,
  76                                               sizeof(VDM_PROCESS_OBJECTS),
  77                                               TAG('K', 'e', ' ', ' '));
  78     if (!VdmProcessObjects) return STATUS_NO_MEMORY;
  79
  80     /* Set it up */
  81     RtlZeroMemory(VdmProcessObjects, sizeof(VDM_PROCESS_OBJECTS));
  82     VdmProcessObjects->VdmTib = VdmTib;
  83     PsGetCurrentProcess()->VdmObjects = VdmProcessObjects;
  84
  85     /* Set the system affinity for the current thread */
  86     KeSetSystemAffinityThread(1);
  87
  88     /* Make sure there's space for two IOPMs, then copy & clear the current */
  89     ASSERT(((PKIPCR)KeGetPcr())->GDT[KGDT_TSS / 8].LimitLow >=
  90             (0x2000 + IOPM_OFFSET - 1));
  91     RtlCopyMemory(Ki386IopmSaveArea, &Tss->IoMaps[0].IoMap, PAGE_SIZE * 2);
  92     RtlZeroMemory(&Tss->IoMaps[0].IoMap, PAGE_SIZE * 2);
  93
  94     /* Save the old offset and base, and set the new ones */
  95     OldOffset = Process->IopmOffset;
  96     OldBase = Tss->IoMapBase;
  97     Process->IopmOffset = (USHORT)IOPM_OFFSET;
  98     Tss->IoMapBase = (USHORT)IOPM_OFFSET;
  99
 100     /* Switch stacks and work the magic */
 101     Ki386SetupAndExitToV86Mode(VdmTeb);
 102
 103     /* Restore IOPM */
 104     RtlCopyMemory(&Tss->IoMaps[0].IoMap, Ki386IopmSaveArea, PAGE_SIZE * 2);
 105     Process->IopmOffset = OldOffset;
 106     Tss->IoMapBase = OldBase;
 107
 108     /* Restore affinity */
 109     KeRevertToUserAffinityThread();
 110
 111     /* Restore context */
 112     RtlCopyMemory(Context, &VdmTib->VdmContext, ContextSize);
 113     Context->ContextFlags = CONTEXT_FULL;
 114
 115     /* Free VDM objects */
 116     ExFreePool(PsGetCurrentProcess()->VdmObjects);
 117     PsGetCurrentProcess()->VdmObjects = NULL;
 118
 119     /* Return status */
 120     return STATUS_SUCCESS;
 121 }
 122
 123 /* EOF */