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From:   Song Liu <song@kernel.org>
Date:   Mon, 21 Feb 2022 18:01:05 -0800
Message-ID: <CAPhsuW6bkhcDXb5k-46G_f4L+ot2QJwbY_-Urd+BEfrPWdmf+Q@mail.gmail.com>
Subject: Re: [PATCH bpf-next v2 1/2] bpf: Add some description about
 BPF_JIT_ALWAYS_ON in Kconfig
To:     Tiezhu Yang <yangtiezhu@loongson.cn>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Xuefeng Li <lixuefeng@loongson.cn>,
        Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
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On Fri, Feb 18, 2022 at 7:15 PM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>
> When CONFIG_BPF_JIT_ALWAYS_ON is enabled, /proc/sys/net/core/bpf_jit_enable
> is permanently set to 1 and setting any other value than that will return
> in failure.
>
> Add the above description in the help text of config BPF_JIT_ALWAYS_ON, and
> then we can distinguish between BPF_JIT_ALWAYS_ON and BPF_JIT_DEFAULT_ON.
>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
>  kernel/bpf/Kconfig | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig
> index d24d518..cbf3f65 100644
> --- a/kernel/bpf/Kconfig
> +++ b/kernel/bpf/Kconfig
> @@ -58,6 +58,10 @@ config BPF_JIT_ALWAYS_ON
>           Enables BPF JIT and removes BPF interpreter to avoid speculative
>           execution of BPF instructions by the interpreter.
>
> +         When CONFIG_BPF_JIT_ALWAYS_ON is enabled, /proc/sys/net/core/bpf_jit_enable
> +         is permanently set to 1 and setting any other value than that will return
> +         in failure.

nit: "return failure" (no "in").

Other than this,

Acked-by: Song Liu <songliubraving@fb.com>

> +
>  config BPF_JIT_DEFAULT_ON
>         def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON
>         depends on HAVE_EBPF_JIT && BPF_JIT
> --
> 2.1.0
>