Re: intercepting an exception handler.

[Angelo Dell'Aera <buffer@users.sourceforge.net>]

On Thu, 5 Sep 2002 19:41:22 +0200
Angelo Dell'Aera <buffer@users.sourceforge.net> wrote:


>        pushl %esi 		# push the error code
>        pushl %edx 		# push the pt_regs pointer
>        movl $(__KERNEL_DS),%edx
>        movl %edx,%ds
>        movl %edx,%es
>        GET_CURRENT(%ebx) <- current process descriptor stored in %ebx
>
>        call *%edi <- here handler (whose address is in %esi) is called  
>			but  look  at  the stack!
>			In the  stack handler finds :
>			-return address of the instruction to be
>			 executed after C handler
>			-error hardware code
>			-SYMBOL_NAME
>			-registers saved
>			-the  stack address  of the saved User Mode
>                         registers
>			-error hardware code
>					<---%esp points here

That's completely wrong!
The correct stack layout at this moment is this one :

-registers saved by CPU control unit (%eflags, %cs and %eip)
-error hardware code
-SYMBOL_NAME
-registers saved (in error_code)
-error hardware code
-the stack address of the saved User Mode registers
-return address of the instruction to be executed after C handler
			<- %esp points here

Now everything should appear clear!

Regards,

Angelo Dell'Aera 'buffer' 
<buffer@users.sourceforge.net>
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