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      1 /** @file
      2   SMM STM support functions
      3 
      4   Copyright (c) 2015 - 2016, Intel Corporation. All rights reserved.<BR>
      5   This program and the accompanying materials
      6   are licensed and made available under the terms and conditions of the BSD License
      7   which accompanies this distribution.  The full text of the license may be found at
      8   http://opensource.org/licenses/bsd-license.php.
      9 
     10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
     11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
     12 
     13 **/
     14 
     15 #include <PiSmm.h>
     16 #include <Library/DebugLib.h>
     17 
     18 #include "SmmStm.h"
     19 
     20 ///
     21 /// Page Table Entry
     22 ///
     23 #define IA32_PG_P                   BIT0
     24 #define IA32_PG_RW                  BIT1
     25 #define IA32_PG_PS                  BIT7
     26 
     27 /**
     28 
     29   Create 4G page table for STM.
     30   4M Non-PAE page table in IA32 version.
     31 
     32   @param PageTableBase        The page table base in MSEG
     33 
     34 **/
     35 VOID
     36 StmGen4GPageTable (
     37   IN UINTN              PageTableBase
     38   )
     39 {
     40   UINTN                             Index;
     41   UINT32                            *Pte;
     42   UINT32                            Address;
     43 
     44   Pte = (UINT32*)(UINTN)PageTableBase;
     45 
     46   Address = 0;
     47   for (Index = 0; Index < SIZE_4KB / sizeof (*Pte); Index++) {
     48     *Pte = Address | IA32_PG_PS | IA32_PG_RW | IA32_PG_P;
     49     Pte++;
     50     Address += SIZE_4MB;
     51   }
     52 }
     53 
     54 /**
     55   This is SMM exception handle.
     56   Consumed by STM when exception happen.
     57 
     58   @param Context  STM protection exception stack frame
     59 
     60   @return the EBX value for STM reference.
     61           EBX = 0: resume SMM guest using register state found on exception stack.
     62           EBX = 1 to 0x0F: EBX contains a BIOS error code which the STM must record in the
     63                            TXT.ERRORCODE register and subsequently reset the system via
     64                            TXT.CMD.SYS_RESET. The value of the TXT.ERRORCODE register is calculated as
     65                            follows: TXT.ERRORCODE = (EBX & 0x0F) | STM_CRASH_BIOS_PANIC
     66           EBX = 0x10 to 0xFFFFFFFF - reserved, do not use.
     67 
     68 **/
     69 UINT32
     70 EFIAPI
     71 SmmStmExceptionHandler (
     72   IN OUT STM_PROTECTION_EXCEPTION_STACK_FRAME Context
     73   )
     74 {
     75   // TBD - SmmStmExceptionHandler, record information
     76   DEBUG ((DEBUG_ERROR, "SmmStmExceptionHandler ...\n"));
     77   //
     78   // Skip this instruction and continue;
     79   //
     80   Context.Ia32StackFrame->Rip += Context.Ia32StackFrame->VmcsExitInstructionLength;
     81 
     82   return 0;
     83 }
     84