118 lines
2.3 KiB
C
118 lines
2.3 KiB
C
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/*++
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Copyright (c) 1991 Microsoft Corporation
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Module Name:
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gdtsup.c
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Abstract:
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This module implements interfaces that support manipulation of i386 Gdts.
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These entry points only exist on i386 machines.
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Author:
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Dave Hastings (daveh) 28 May 1991
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Environment:
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Kernel mode only.
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Revision History:
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Fred Yang (intel) 20 Aug 1996 - based on ../i386/gdtsup.c but stripped
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out the code we don't need. IA64 will never set an entry in the GDT
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at runtime, for example...
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--*/
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#include "ki.h"
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VOID
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KeIA32GetGdtEntryThread(
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IN PKTHREAD Thread,
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IN ULONG Offset,
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OUT PKGDTENTRY Descriptor
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)
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/*++
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Routine Description:
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This routine returns the contents of an entry in the Gdt. If the
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entry is thread specific, the entry for the specified thread is
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created and returned (KGDT_LDT, and KGDT_R3_TEB). If the selector
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is processor dependent, the entry for the current processor is
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returned (KGDT_R0_PCR).
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Arguments:
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Thread -- Supplies a pointer to the thread to return the entry for.
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Offset -- Supplies the offset in the Gdt. This value must be 0
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mod 8.
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Descriptor -- Returns the contents of the Gdt descriptor
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Return Value:
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None.
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--*/
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{
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#if 0
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PKGDTENTRY Gdt;
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PKPROCESS Process;
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// If the entry is out of range, don't return anything
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if (Offset >= GDT_TABLE_SIZE) {
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return ;
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}
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if (Offset == KGDT_LDT) {
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// Materialize Ldt selector
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Process = Thread->ApcState.Process;
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// Assume same process
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ASSERT (&(PsGetCurrentProcess()->Pcb) == Process);
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*Descriptor = Process->LdtDescriptor;
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} else {
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// Copy Selector from Gdt
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// N.B. We will change the base later, if it is KGDT_R3_TEB
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PTEB Teb = (PTEB)(Thread->Teb);
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*Descriptor = *((PKGDTENTRY)((PCHAR)(Teb->Gdt) + Offset));
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// if it is the TEB selector, fix the base
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if (Offset == KGDT_R3_TEB) {
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Descriptor->BaseLow = (USHORT)((ULONG_PTR)(Thread->Teb) & 0xFFFF);
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Descriptor->HighWord.Bytes.BaseMid =
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(UCHAR) ( ( (ULONG_PTR)(Thread->Teb) & ((ULONG_PTR)0xFF0000L)) >> 16);
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Descriptor->HighWord.Bytes.BaseHi =
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(CHAR) ( ( (ULONG_PTR)(Thread->Teb) & ((ULONG_PTR)0xFF000000L)) >> 24);
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}
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}
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return ;
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#endif
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}
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