Re: ptrace on i386

[Brian Gerst]

Frank Cornelis wrote:
> 
> Hi,
> 
> In linux/arch/i386/kernel/ptrace.c next code is being used in the xxxreg
> functions:
>         if (regno > GS*4)
>                 regno -= 2*4;
> Why this discontinuity? It doesn't prevent ORIG_EAX and EIP from being
> written and makes the defines CS, EIF, ... from linux/include/asm/ptrace.h
> useless. BTW: regno should really call reg_offset since it's no register
> number but an offset.

It's because the %fs and %gs segment registers are not saved on the
stack upon kernel entry anymore.  Thus, the following values have to be
shifted by 2 positions to maintain compatability with the ptrace
register structure.

-- 

						Brian Gerst