netdev - Re: [PATCH bpf-next 3/3] selftests/bpf: add tests for user- and non-CO-RE BPF_CORE

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Message-ID: <20210107200014.ijpg3n7mjqdrrrvo@ast-mbp>
Date:   Thu, 7 Jan 2021 12:00:14 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Gilad Reti <gilad.reti@...il.com>,
        Andrii Nakryiko <andrii@...nel.org>, bpf <bpf@...r.kernel.org>,
        Networking <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH bpf-next 3/3] selftests/bpf: add tests for user- and
 non-CO-RE BPF_CORE_READ() variants

On Wed, Jan 06, 2021 at 03:25:30PM -0800, Andrii Nakryiko wrote:
> >
> > If I am not mistaken (which is completely possible), I think that
> > providing such a macro will
> > not cause any more confusion than the bpf_probe_read_{,user}
> > distinction already does,
> > since BPF_CORE_READ_USER to BPF_CORE_READ is the same as bpf_probe_read_user
> > to bpf_probe_read.
> 
> I think the biggest source of confusion is that USER part in
> BPF_CORE_READ_USER refers to reading data from user address space, not
> really user structs (which is kind of natural instinct here). CO-RE
> *always* works only with kernel types, which is obvious if you have a
> lot of experience with using CO-RE, but not initially, unfortunately.

Please send a patch to add such clarifying comment.