IntHandlerFuncs.c

Go to the documentation of this file.

 
#include <PeCoffExtraActionLib.h>
 
BOOLEAN
CheckDebugAgentHandler (
  IN  IA32_DESCRIPTOR  *IdtDescriptor,
  IN  UINTN            InterruptType
  )
{
  IA32_IDT_GATE_DESCRIPTOR  *IdtEntry;
  UINTN                     InterruptHandler;
 
  IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *)IdtDescriptor->Base;
  if (IdtEntry == NULL) {
    return FALSE;
  }
 
  InterruptHandler = IdtEntry[InterruptType].Bits.OffsetLow +
                     (IdtEntry[InterruptType].Bits.OffsetHigh << 16);
  if ((InterruptHandler >= sizeof (UINT32)) &&  (*(UINT32 *)(InterruptHandler - sizeof (UINT32)) == AGENT_HANDLER_SIGNATURE)) {
    return TRUE;
  } else {
    return FALSE;
  }
}
 
VOID
SaveAndUpdateIdtEntry1 (
  IN  IA32_DESCRIPTOR           *IdtDescriptor,
  OUT IA32_IDT_GATE_DESCRIPTOR  *SavedIdtEntry
  )
{
  IA32_IDT_GATE_DESCRIPTOR  *IdtEntry;
  UINT16                    CodeSegment;
  UINTN                     InterruptHandler;
 
  IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *)IdtDescriptor->Base;
  CopyMem (SavedIdtEntry, &IdtEntry[1], sizeof (IA32_IDT_GATE_DESCRIPTOR));
 
  //
  // Use current CS as the segment selector of interrupt gate in IDT
  //
  CodeSegment = AsmReadCs ();
 
  InterruptHandler            = (UINTN)&AsmInterruptHandle;
  IdtEntry[1].Bits.OffsetLow  = (UINT16)(UINTN)InterruptHandler;
  IdtEntry[1].Bits.OffsetHigh = (UINT16)((UINTN)InterruptHandler >> 16);
  IdtEntry[1].Bits.Selector   = CodeSegment;
  IdtEntry[1].Bits.GateType   = IA32_IDT_GATE_TYPE_INTERRUPT_32;
}
 
VOID
RestoreIdtEntry1 (
  IN  IA32_DESCRIPTOR           *IdtDescriptor,
  IN  IA32_IDT_GATE_DESCRIPTOR  *RestoredIdtEntry
  )
{
  IA32_IDT_GATE_DESCRIPTOR  *IdtEntry;
 
  IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *)IdtDescriptor->Base;
  CopyMem (&IdtEntry[1], RestoredIdtEntry, sizeof (IA32_IDT_GATE_DESCRIPTOR));
}