linux-kernel - Re: [PATCH 03/10] bpf: Add bpf_get_func_ip kprobe helper for multi kprobe link

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Message-ID: <CAEf4BzaKbMd=fFeqD3MhewtD3eXw81-_FfdfKUOUH5wJsF6D_Q@mail.gmail.com>
Date:   Fri, 4 Mar 2022 15:11:05 -0800
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH 03/10] bpf: Add bpf_get_func_ip kprobe helper for multi
 kprobe link

On Tue, Feb 22, 2022 at 9:06 AM Jiri Olsa <jolsa@...nel.org> wrote:
>
> Adding support to call bpf_get_func_ip helper from kprobe
> programs attached by multi kprobe link.
>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---

LGTM.

Acked-by: Andrii Nakryiko <andrii@...nel.org>


>  kernel/trace/bpf_trace.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index df3771bfd6e5..64891b7b0885 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1037,6 +1037,18 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
>         .arg1_type      = ARG_PTR_TO_CTX,
>  };
>
> +BPF_CALL_1(bpf_get_func_ip_kprobe_multi, struct pt_regs *, regs)
> +{
> +       return instruction_pointer(regs);
> +}
> +
> +static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe_multi = {
> +       .func           = bpf_get_func_ip_kprobe_multi,
> +       .gpl_only       = false,
> +       .ret_type       = RET_INTEGER,
> +       .arg1_type      = ARG_PTR_TO_CTX,
> +};
> +
>  BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
>  {
>         struct bpf_trace_run_ctx *run_ctx;
> @@ -1280,7 +1292,9 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
>                 return &bpf_override_return_proto;
>  #endif
>         case BPF_FUNC_get_func_ip:
> -               return &bpf_get_func_ip_proto_kprobe;
> +               return prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI ?
> +                       &bpf_get_func_ip_proto_kprobe_multi :
> +                       &bpf_get_func_ip_proto_kprobe;
>         case BPF_FUNC_get_attach_cookie:
>                 return &bpf_get_attach_cookie_proto_trace;
>         default:
> --
> 2.35.1
>