netdev - Re: [PATCH bpf-next 4/8] bpf: add initial poke descriptor table for jit images

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Date:   Wed, 20 Nov 2019 10:34:52 -0800
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        john fastabend <john.fastabend@...il.com>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        Andrii Nakryiko <andriin@...com>
Subject: Re: [PATCH bpf-next 4/8] bpf: add initial poke descriptor table for
 jit images

On Mon, Nov 18, 2019 at 5:38 PM Daniel Borkmann <daniel@...earbox.net> wrote:
>
> Add initial poke table data structures and management to the BPF
> prog that can later be used by JITs. Also add an instance of poke
> specific data for tail call maps; plan for later work is to extend
> this also for BPF static keys.
>
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> Acked-by: Andrii Nakryiko <andriin@...com>
> ---
>  include/linux/bpf.h    | 20 ++++++++++++++++++++
>  include/linux/filter.h | 10 ++++++++++
>  kernel/bpf/core.c      | 34 ++++++++++++++++++++++++++++++++++
>  3 files changed, 64 insertions(+)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 836e49855bf9..cad4382c1265 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -488,6 +488,24 @@ struct bpf_func_info_aux {
>         bool unreliable;
>  };
>
> +enum bpf_jit_poke_reason {
> +       BPF_POKE_REASON_TAIL_CALL,
> +};
> +
> +/* Descriptor of pokes pointing /into/ the JITed image. */
> +struct bpf_jit_poke_descriptor {
> +       void *ip;
> +       union {
> +               struct {
> +                       struct bpf_map *map;
> +                       u32 key;
> +               } tail_call;
> +       };
> +       u8 ip_stable;

this one is bool, any reason you used u8 instead?

> +       u8 adj_off;
> +       u16 reason;
> +};
> +

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