174 lines
3.5 KiB
NASM
174 lines
3.5 KiB
NASM
title "I386 PCR"
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;++
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;
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; Copyright (c) 1989 Microsoft Corporation
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;
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; Module Name:
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;
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; i386pcr.asm
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;
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; Abstract:
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;
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; This module implements routines for accessing and initing the pcr.
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;
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; Author:
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;
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; Bryan Willman (bryanwi) 20 Mar 90
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;
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; Environment:
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;
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; Kernel mode, early init of first processor.
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;
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; Revision History:
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;
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;--
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.386p
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.xlist
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include ks386.inc
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include callconv.inc ; calling convention macros
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.list
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;
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; NOTE - This definition of PCR gives us 2 instructions to get to some
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; variables that need to be addressable in one instruction. Any
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; such variable (such as current thread) must be accessed via its
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; own access procedure (see below), NOT by KeGetPcr()->PbCurrentThread.
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; (This is only an issue on MP machines.)
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;
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_TEXT$00 SEGMENT DWORD PUBLIC 'CODE'
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ASSUME DS:FLAT, ES:FLAT, SS:NOTHING, FS:NOTHING, GS:NOTHING
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;++
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;
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; PKTHREAD
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; KeGetCurrentThread()
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;
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; Return Value:
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;
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; Pointer to current Thread object.
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;
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;--
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cPublicProc ___KeGetCurrentThread ,0
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mov eax,PCR[PcPrcbData+PbCurrentThread]
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stdRET ___KeGetCurrentThread
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stdENDP ___KeGetCurrentThread
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;++
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;
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; KPROCESSOR_MODE
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; KeGetPreviousMode()
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;
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; Return Value:
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;
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; PreviousMode of current thread.
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;
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;--
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cPublicProc _KeGetPreviousMode
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mov eax,PCR[PcPrcbData+PbCurrentThread] ; (eax) -> Thread
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movzx eax,byte ptr [eax]+ThPreviousMode ; (eax) = PreviousMode
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stdRET _KeGetPreviousMode
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stdENDP _KeGetPreviousMode
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;++
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;
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; BOOLEAN
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; KeIsExecutingDpc(
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; VOID
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; );
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;
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; Return Value:
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;
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; Value of flag which indicates whether we're executing in DPC context
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;
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;--
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cPublicProc ___KeIsExecutingDpc ,0
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mov eax,PCR[PcPrcbData.PbDpcRoutineActive]
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stdRET ___KeIsExecutingDpc
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stdENDP ___KeIsExecutingDpc
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;++
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;
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; VOID
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; GetMachineBootPointers(
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; )
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;
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; Routine Description:
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;
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; This routine is called at system startup to extract the address of
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; the PCR and machine control values. It is useful only for the P0
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; case where the boot loader must already init the machine before it
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; turns on paging and calls us.
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;
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; Pcr address is extracted from the base of KGDT_R0_PCR.
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;
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; Gdt and Idt are extracted from the machine GDTR and IDTR.
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;
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; TSS is derived from the TSR and related descriptor.
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;
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; Arguments:
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;
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; None.
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;
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; Return Value:
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;
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;
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; (edi) -> gdt
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; (esi) -> pcr
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; (edx) -> tss
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; (eax) -> idt
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;
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;--
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cPublicProc GetMachineBootPointers
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push ebp
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mov ebp,esp
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sub esp,8
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sgdt fword ptr [ebp-8]
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mov edi,[ebp-6] ; (edi) = gdt address
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mov cx,fs
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and cx,(NOT RPL_MASK)
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movzx ecx,cx
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add ecx,edi ; (ecx) -> pcr descriptor
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mov dh,[ecx+KgdtBaseHi]
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mov dl,[ecx+KgdtBaseMid]
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shl edx,16
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mov dx,[ecx+KgdtBaseLow] ; (edx) -> pcr
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mov esi,edx ; (esi) -> pcr
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str cx
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movzx ecx,cx
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add ecx,edi ; (ecx) -> TSS descriptor
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mov dh,[ecx+KgdtBaseHi]
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mov dl,[ecx+KgdtBaseMid]
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shl edx,16
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mov dx,[ecx+KgdtBaseLow] ; (edx) -> TSS
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sidt fword ptr [ebp-8]
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mov eax,[ebp-6] ; (eax) -> Idt
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mov esp,ebp
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pop ebp
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stdRET GetMachineBootPointers
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stdENDP GetMachineBootPointers
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_TEXT$00 ENDS
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end
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