SourceLevelDebugPkg/Library/PeCoffExtraActionLibDebug/Ia32/IntHandlerFuncs.c

   1 /** @file
   2   Ia32 arch functions to access IDT vector.
   3
   4   Copyright (c) 2013 - 2018, Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include <PeCoffExtraActionLib.h>
  10
  11 /**
  12   Read IDT entry to check if IDT entries are setup by Debug Agent.
  13
  14   @param[in]  IdtDescriptor      Pointer to IDT Descriptor.
  15   @param[in]  InterruptType      Interrupt type.
  16
  17   @retval  TRUE     IDT entries were setup by Debug Agent.
  18   @retval  FALSE    IDT entries were not setuo by Debug Agent.
  19
  20 **/
  21 BOOLEAN
  22 CheckDebugAgentHandler (
  23   IN  IA32_DESCRIPTOR            *IdtDescriptor,
  24   IN  UINTN                      InterruptType
  25   )
  26 {
  27   IA32_IDT_GATE_DESCRIPTOR   *IdtEntry;
  28   UINTN                      InterruptHandler;
  29
  30   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor->Base;
  31   if (IdtEntry == NULL) {
  32     return FALSE;
  33   }
  34
  35   InterruptHandler = IdtEntry[InterruptType].Bits.OffsetLow +
  36                     (IdtEntry[InterruptType].Bits.OffsetHigh << 16);
  37   if (InterruptHandler >= sizeof (UINT32) &&  *(UINT32 *)(InterruptHandler - sizeof (UINT32)) == AGENT_HANDLER_SIGNATURE) {
  38     return TRUE;
  39   } else {
  40     return FALSE;
  41   }
  42 }
  43
  44 /**
  45   Save IDT entry for INT1 and update it.
  46
  47   @param[in]  IdtDescriptor      Pointer to IDT Descriptor.
  48   @param[out] SavedIdtEntry      Original IDT entry returned.
  49
  50 **/
  51 VOID
  52 SaveAndUpdateIdtEntry1 (
  53   IN  IA32_DESCRIPTOR            *IdtDescriptor,
  54   OUT IA32_IDT_GATE_DESCRIPTOR   *SavedIdtEntry
  55   )
  56 {
  57   IA32_IDT_GATE_DESCRIPTOR   *IdtEntry;
  58   UINT16                     CodeSegment;
  59   UINTN                      InterruptHandler;
  60
  61   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor->Base;
  62   CopyMem (SavedIdtEntry, &IdtEntry[1], sizeof (IA32_IDT_GATE_DESCRIPTOR));
  63
  64     //
  65   // Use current CS as the segment selector of interrupt gate in IDT
  66   //
  67   CodeSegment = AsmReadCs ();
  68
  69   InterruptHandler = (UINTN) &AsmInterruptHandle;
  70   IdtEntry[1].Bits.OffsetLow  = (UINT16)(UINTN)InterruptHandler;
  71   IdtEntry[1].Bits.OffsetHigh = (UINT16)((UINTN)InterruptHandler >> 16);
  72   IdtEntry[1].Bits.Selector   = CodeSegment;
  73   IdtEntry[1].Bits.GateType   = IA32_IDT_GATE_TYPE_INTERRUPT_32;
  74 }
  75
  76 /**
  77   Restore IDT entry for INT1.
  78
  79   @param[in]  IdtDescriptor      Pointer to IDT Descriptor.
  80   @param[in]  RestoredIdtEntry   IDT entry to be restored.
  81
  82 **/
  83 VOID
  84 RestoreIdtEntry1 (
  85   IN  IA32_DESCRIPTOR            *IdtDescriptor,
  86   IN  IA32_IDT_GATE_DESCRIPTOR   *RestoredIdtEntry
  87   )
  88 {
  89   IA32_IDT_GATE_DESCRIPTOR   *IdtEntry;
  90
  91   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor->Base;
  92   CopyMem (&IdtEntry[1], RestoredIdtEntry, sizeof (IA32_IDT_GATE_DESCRIPTOR));
  93 }