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SubjectRe: [RFC,PATCH 1/2] seccomp_filters: system call filtering using BPF
On 01/12, Will Drewry wrote:
>
> On Thu, Jan 12, 2012 at 10:22 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> >> +      */
> >> +     regs = seccomp_get_regs(regs_tmp, &regs_size);
> >
> > Stupid question. I am sure you know what are you doing ;) and I know
> > 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) regsets?
>
> So on x86 32, it would work since user_regs_struct == task_pt_regs
> (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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