linux-kernel - Re: [PATCH v2] docs: sysctl/kernel: document BPF entries

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Date:   Tue, 10 Mar 2020 10:47:15 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Stephen Kitt <steve@....org>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>, bpf <bpf@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] docs: sysctl/kernel: document BPF entries

On Mon, Mar 9, 2020 at 11:05 AM Stephen Kitt <steve@....org> wrote:
>
> Based on the implementation in kernel/bpf/syscall.c,
> kernel/bpf/trampoline.c, include/linux/filter.h, and the documentation
> in bpftool-prog.rst.
>
> The section style doesn't match the surrounding sections; it matches
> the style of the reworked kernel.rst queued up in docs-next.
>
> Signed-off-by: Stephen Kitt <steve@....org>
> ---
>
> Notes:
>     Changes since v1:
>     - rebased on bpf-next instead of docs-next.
>
>  Documentation/admin-guide/sysctl/kernel.rst | 24 +++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>
> diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
> index def074807cee..eea7afd509ac 100644
> --- a/Documentation/admin-guide/sysctl/kernel.rst
> +++ b/Documentation/admin-guide/sysctl/kernel.rst
> @@ -174,6 +174,20 @@ See the type_of_loader and ext_loader_ver fields in
>  Documentation/x86/boot.rst for additional information.
>
>
> +bpf_stats_enabled
> +=================
> +
> +Controls whether the kernel should collect statistics on BPF programs
> +(total time spent running, number of times run...). Enabling
> +statistics causes a slight reduction in performance on each program
> +run. The statistics can be seen using ``bpftool``.
> +
> += ===================================
> +0 Don't collect statistics (default).
> +1 Collect statistics.
> += ===================================
> +
> +
>  cap_last_cap:
>  =============
>
> @@ -1123,6 +1137,16 @@ NMI switch that most IA32 servers have fires unknown NMI up, for
>  example.  If a system hangs up, try pressing the NMI switch.
>
>
> +unprivileged_bpf_disabled
> +=========================
> +
> +Writing 1 to this entry will disabled unprivileged calls to ``bpf()``;

same typo as was pointed out earlier.