VOID
NTAPI
HalpBorrowTss(VOID)
{
USHORT Tss;
PKGDTENTRY TssGdt;
ULONG_PTR TssLimit;
PKTSS TssBase;
//
// Get the current TSS and its GDT entry
//
Tss = Ke386GetTr();
TssGdt = &((PKIPCR)KeGetPcr())->GDT[Tss / sizeof(KGDTENTRY)];
//
// Get the KTSS limit and check if it has IOPM space
//
TssLimit = TssGdt->LimitLow | TssGdt->HighWord.Bits.LimitHi << 16;
//
// If the KTSS doesn't have enough space this is probably an NMI or DF
//
if (TssLimit > IOPM_SIZE)
{
//
// We are good to go
//
HalpSavedTss = 0;
return;
}
//
// Get the "real" TSS
//
TssGdt = &((PKIPCR)KeGetPcr())->GDT[KGDT_TSS / sizeof(KGDTENTRY)];
TssBase = (PKTSS)(ULONG_PTR)(TssGdt->BaseLow |
TssGdt->HighWord.Bytes.BaseMid << 16 |
TssGdt->HighWord.Bytes.BaseHi << 24);
//
// Switch to it
//
KeGetPcr()->TSS = TssBase;
//
// Set it up
//
TssGdt->HighWord.Bits.Type = I386_TSS;
TssGdt->HighWord.Bits.Pres = 1;
TssGdt->HighWord.Bits.Dpl = 0;
//
// Load new TSS and return old one
//
Ke386SetTr(KGDT_TSS);
HalpSavedTss = Tss;
}
VOID
FASTCALL
INIT_FUNCTION
KiGetMachineBootPointers(IN PKGDTENTRY *Gdt,
IN PKIDTENTRY *Idt,
IN PKIPCR *Pcr,
IN PKTSS *Tss)
{
KDESCRIPTOR GdtDescriptor, IdtDescriptor;
KGDTENTRY TssSelector, PcrSelector;
USHORT Tr, Fs;
/* Get GDT and IDT descriptors */
Ke386GetGlobalDescriptorTable(&GdtDescriptor.Limit);
__sidt(&IdtDescriptor.Limit);
/* Save IDT and GDT */
*Gdt = (PKGDTENTRY)GdtDescriptor.Base;
*Idt = (PKIDTENTRY)IdtDescriptor.Base;
/* Get TSS and FS Selectors */
Tr = Ke386GetTr();
Fs = Ke386GetFs();
/* Get PCR Selector, mask it and get its GDT Entry */
PcrSelector = *(PKGDTENTRY)((ULONG_PTR)*Gdt + (Fs & ~RPL_MASK));
/* Get the KPCR itself */
*Pcr = (PKIPCR)(ULONG_PTR)(PcrSelector.BaseLow |
PcrSelector.HighWord.Bytes.BaseMid << 16 |
PcrSelector.HighWord.Bytes.BaseHi << 24);
/* Get TSS Selector, mask it and get its GDT Entry */
TssSelector = *(PKGDTENTRY)((ULONG_PTR)*Gdt + (Tr & ~RPL_MASK));
/* Get the KTSS itself */
*Tss = (PKTSS)(ULONG_PTR)(TssSelector.BaseLow |
TssSelector.HighWord.Bytes.BaseMid << 16 |
TssSelector.HighWord.Bytes.BaseHi << 24);
}
