From mboxrd@z Thu Jan  1 00:00:00 1970
From: Oleg Nesterov <oleg@redhat.com>
Subject: Re: [RFC,PATCH 1/2] seccomp_filters: system call filtering using
	BPF
Date: Thu, 12 Jan 2012 18:23:15 +0100
Message-ID: <20120112172315.GA26295@redhat.com>
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To: Will Drewry <wad@chromium.org>
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On 01/12, Will Drewry wrote:
>
> On Thu, Jan 12, 2012 at 10:22 AM, Oleg Nesterov <oleg@redhat.com> wro=
te:
> >> + =A0 =A0 =A0*/
> >> + =A0 =A0 regs =3D seccomp_get_regs(regs_tmp, &regs_size);
> >
> > Stupid question. I am sure you know what are you doing ;) and I kno=
w
> > nothing about !x86 arches.
> >
> > But could you explain why it is designed to use user_regs_struct ?
> > Why we can't simply use task_pt_regs() and avoid the (costly) regse=
ts?
>
> So on x86 32, it would work since user_regs_struct =3D=3D task_pt_reg=
s
> (iirc), but on x86-64
> and others, that's not true.

Yes sure, I meant that userpace should use pt_regs too.

> If it would be appropriate to expose pt_regs to userspace, then I'd
> happily do so :)

Ah, so that was the reason. But it is already exported? At least I see
the "#ifndef __KERNEL__" definition in arch/x86/include/asm/ptrace.h.

Once again, I am not arguing, just trying to understand. And I do not
know if this definition is part of abi.

Oleg.

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