From: Brian Gerst <bgerst@didntduck.org>
To: Frank Cornelis <Frank.Cornelis@rug.ac.be>
Cc: linux-kernel@vger.kernel.org
Subject: Re: ptrace on i386
Date: Sat, 01 Dec 2001 08:56:38 -0500 [thread overview]
Message-ID: <3C08E196.51F22885@didntduck.org> (raw)
In-Reply-To: <Pine.GSO.4.31.0112011106410.4313-100000@eduserv.rug.ac.be>
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
next prev parent reply other threads:[~2001-12-01 14:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-12-01 10:17 ptrace on i386 Frank Cornelis
2001-12-01 13:56 ` Brian Gerst [this message]
-- strict thread matches above, loose matches on Subject: below --
2001-12-01 10:46 Manfred Spraul
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