From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Borkmann <dborkman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: Edited seccomp.2 man page for review [v2]
Date: Wed, 07 Jan 2015 13:23:37 +0100
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To: "Michael Kerrisk (man-pages)" <mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, Linux API <linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, "linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, lkml <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Will Drewry <wad-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org
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On 01/07/2015 12:53 PM, Michael Kerrisk (man-pages) wrote:
...
> Still hoping to hear from Will Drewy regarding this FIXME in the
> page source:
>
> .\" FIXME What is the significance of the line
> .\"           ftest->code = BPF_LDX | BPF_W | BPF_ABS;
> .\"       in kernel/seccomp.c::seccomp_check_filter()?

This came in from our rework via commit bd4cf0ed331a ("net: filter:
rework/optimize internal BPF interpreter's instruction set"), and
is kernel-internal only, and unused in classic BPF. It translates
into A = *(u32 *) (ctx + K) and will basically load an offset from
the populated seccomp_data (= ctx) to A. For the man-page itself
it has therefore no relevance, hope that clarifies it.

Cheers,
Daniel