dblflt.c

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/*++

Copyright (c) 1998-2001 Klaus P. Gerlicher

Module Name:

    dblflt.c

Abstract:

    handle double faults on x86

Environment:

    LINUX 2.2.X
    Kernel mode only

Author:

    Klaus P. Gerlicher

Revision History:

    13-Nov-1999:    created
    15-Nov-2000:    general cleanup of source files

Copyright notice:

  This file may be distributed under the terms of the GNU Public License.

--*/

// INCLUDES
#include "remods.h"
#include "precomp.h"

// GLOBALS
ULONG OldDblFltHandler = 0;

// FUNCTIONS

//*************************************************************************
// HandleDoubleFault()
//
//*************************************************************************
void HandleDoubleFault(FRAME* ptr)
{
    DPRINT((0,"HandleDoubleFault(): ptr = %x\n",ptr));
}


//*************************************************************************
// NewDblFltHandler()
//
//*************************************************************************
__asm__ (" \
NewDblFltHandler:\n\t \
        pushfl\n\t \
        cli;\n\t \
        cld;\n\t \
        pushal;\n\t \
        pushl %ds;\n\t \
\n\t \
        // setup default data selectors\n\t \
        movw %ss,%ax\n\t \
        movw %ax,%ds\n\t \
\n\t \
        // get frame ptr\n\t \
        lea 40(%esp),%eax\n\t \
        pushl %eax\n\t \
        call _HandleDoubleFault\n\t \
        addl $4,%esp\n\t \
\n\t \
        popl %ds\n\t \
        popal\n\t \
        popfl\n\t \
        // remove error code from stack and replace with reason code\n\t \
        movl $" STR(REASON_DOUBLE_FAULT) ",(%esp)\n\t \
        // call debugger loop\n\t \
        jmp NewInt31Handler\n\t");


//*************************************************************************
// InstallDblFltHook()
//
//*************************************************************************
void InstallDblFltHook(void)
{
    ULONG LocalDblFltHandler;

    ENTER_FUNC();

    MaskIrqs();
    if(!OldDblFltHandler)
    {
        __asm__("mov $NewDblFltHandler,%0"
            :"=r" (LocalDblFltHandler)
            :
            :"eax");
        OldDblFltHandler=SetGlobalInt(0x08,(ULONG)LocalDblFltHandler);
    }
    UnmaskIrqs();

    LEAVE_FUNC();
}

//*************************************************************************
// DeInstallDblFltHook()
//
//*************************************************************************
void DeInstallDblFltHook(void)
{
    ENTER_FUNC();

    MaskIrqs();
    if(OldDblFltHandler)
    {
        RemoveAllSWBreakpoints(TRUE);
        SetGlobalInt(0x08,(ULONG)OldDblFltHandler);
        OldDblFltHandler=0;
    }
    UnmaskIrqs();

    LEAVE_FUNC();
}

// EOF