PlDebugSupportIa32.c

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#include "PlDebugSupport.h"
 
IA32_IDT_GATE_DESCRIPTOR  NullDesc = {
  { 0 }
};
 
UINTN
GetInterruptHandleFromIdt (
  IN IA32_IDT_GATE_DESCRIPTOR  *IdtGateDescriptor
  )
{
  UINTN  InterruptHandle;
 
  //
  // InterruptHandle  0-15 : OffsetLow
  // InterruptHandle 16-31 : OffsetHigh
  //
  ((UINT16 *)&InterruptHandle)[0] = (UINT16)IdtGateDescriptor->Bits.OffsetLow;
  ((UINT16 *)&InterruptHandle)[1] = (UINT16)IdtGateDescriptor->Bits.OffsetHigh;
 
  return InterruptHandle;
}
 
VOID
CreateEntryStub (
  IN EFI_EXCEPTION_TYPE  ExceptionType,
  OUT VOID               **Stub
  )
{
  UINT8  *StubCopy;
 
  StubCopy = *Stub;
 
  //
  // Fixup the stub code for this vector
  //
 
  // The stub code looks like this:
  //
  //    00000000  89 25 00000004 R  mov     AppEsp, esp             ; save stack top
  //    00000006  BC 00008014 R     mov     esp, offset DbgStkBot   ; switch to debugger stack
  //    0000000B  6A 00             push    0                       ; push vector number - will be modified before installed
  //    0000000D  E9                db      0e9h                    ; jump rel32
  //    0000000E  00000000          dd      0                       ; fixed up to relative address of CommonIdtEntry
  //
 
  //
  // poke in the exception type so the second push pushes the exception type
  //
  StubCopy[0x0c] = (UINT8)ExceptionType;
 
  //
  // fixup the jump target to point to the common entry
  //
  *(UINT32 *)&StubCopy[0x0e] = (UINT32)CommonIdtEntry - (UINT32)&StubCopy[StubSize];
 
  return;
}
 
EFI_STATUS
ManageIdtEntryTable (
  CALLBACK_FUNC       NewCallback,
  EFI_EXCEPTION_TYPE  ExceptionType
  )
{
  EFI_STATUS  Status;
 
  Status = EFI_SUCCESS;
 
  if (CompareMem (&IdtEntryTable[ExceptionType].NewDesc, &NullDesc, sizeof (IA32_IDT_GATE_DESCRIPTOR)) != 0) {
    //
    // we've already installed to this vector
    //
    if (NewCallback != NULL) {
      //
      // if the input handler is non-null, error
      //
      Status = EFI_ALREADY_STARTED;
    } else {
      UnhookEntry (ExceptionType);
    }
  } else {
    //
    // no user handler installed on this vector
    //
    if (NewCallback == NULL) {
      //
      // if the input handler is null, error
      //
      Status = EFI_INVALID_PARAMETER;
    } else {
      HookEntry (ExceptionType, NewCallback);
    }
  }
 
  return Status;
}