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   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 <PeCoffExtraActionLib.h>
  16
  17 /**
  18   Read IDT entry to check if IDT entries are setup by Debug Agent.
  19
  20   @param[in]  IdtDescriptor      Pointer to IDT Descriptor.
  21   @param[in]  InterruptType      Interrupt type.
  22
  23   @retval  TRUE     IDT entries were setup by Debug Agent.
  24   @retval  FALSE    IDT entries were not setuo by Debug Agent.
  25
  26 **/
  27 BOOLEAN
  28 CheckDebugAgentHandler (
  29   IN  IA32_DESCRIPTOR            *IdtDescriptor,
  30   IN  UINTN                      InterruptType
  31   )
  32 {
  33   IA32_IDT_GATE_DESCRIPTOR   *IdtEntry;
  34   UINTN                      InterruptHandler;
  35
  36   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor->Base;
  37   if (IdtEntry == NULL) {
  38     return FALSE;
  39   }
  40
  41   InterruptHandler = IdtEntry[InterruptType].Bits.OffsetLow +
  42                     (IdtEntry[InterruptType].Bits.OffsetHigh << 16);
  43   if (InterruptHandler >= sizeof (UINT32) &&  *(UINT32 *)(InterruptHandler - sizeof (UINT32)) == AGENT_HANDLER_SIGNATURE) {
  44     return TRUE;
  45   } else {
  46     return FALSE;
  47   }
  48 }
  49
  50 /**
  51   Save IDT entry for INT1 and update it.
  52
  53   @param[in]  IdtDescriptor      Pointer to IDT Descriptor.
  54   @param[out] SavedIdtEntry      Original IDT entry returned.
  55
  56 **/
  57 VOID
  58 SaveAndUpdateIdtEntry1 (
  59   IN  IA32_DESCRIPTOR            *IdtDescriptor,
  60   OUT IA32_IDT_GATE_DESCRIPTOR   *SavedIdtEntry
  61   )
  62 {
  63   IA32_IDT_GATE_DESCRIPTOR   *IdtEntry;
  64   UINT16                     CodeSegment;
  65   UINTN                      InterruptHandler;
  66
  67   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor->Base;
  68   CopyMem (SavedIdtEntry, &IdtEntry[1], sizeof (IA32_IDT_GATE_DESCRIPTOR));
  69
  70     //
  71   // Use current CS as the segment selector of interrupt gate in IDT
  72   //
  73   CodeSegment = AsmReadCs ();
  74
  75   InterruptHandler = (UINTN) &AsmInterruptHandle;
  76   IdtEntry[1].Bits.OffsetLow  = (UINT16)(UINTN)InterruptHandler;
  77   IdtEntry[1].Bits.OffsetHigh = (UINT16)((UINTN)InterruptHandler >> 16);
  78   IdtEntry[1].Bits.Selector   = CodeSegment;
  79   IdtEntry[1].Bits.GateType   = IA32_IDT_GATE_TYPE_INTERRUPT_32;
  80 }
  81
  82 /**
  83   Restore IDT entry for INT1.
  84
  85   @param[in]  IdtDescriptor      Pointer to IDT Descriptor.
  86   @param[in]  RestoredIdtEntry   IDT entry to be restored.
  87
  88 **/
  89 VOID
  90 RestoreIdtEntry1 (
  91   IN  IA32_DESCRIPTOR            *IdtDescriptor,
  92   IN  IA32_IDT_GATE_DESCRIPTOR   *RestoredIdtEntry
  93   )
  94 {
  95   IA32_IDT_GATE_DESCRIPTOR   *IdtEntry;
  96
  97   IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor->Base;
  98   CopyMem (&IdtEntry[1], RestoredIdtEntry, sizeof (IA32_IDT_GATE_DESCRIPTOR));
  99 }