netdev - Re: [PATCH bpf-next v3 00/13] bpf: add btf func info support

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Message-ID: <20181018032359.q6fozep6xpkk6vs2@ast-mbp.dhcp.thefacebook.com>
Date:   Wed, 17 Oct 2018 20:24:01 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Yonghong Song <yhs@...com>
Cc:     ast@...com, kafai@...com, daniel@...earbox.net,
        netdev@...r.kernel.org, kernel-team@...com
Subject: Re: [PATCH bpf-next v3 00/13] bpf: add btf func info support

On Wed, Oct 17, 2018 at 04:30:22PM -0700, Yonghong Song wrote:
> 
> This patch added func info support to the kernel so we can
> get better ksym's for bpf function calls. Basically,
> pairs of bpf function calls and their corresponding types
> are passed to the kernel. Extracting function names from
> the types, the kernel is able to construct a ksym for
> each function call with embedded function name.
...
> Below is a demonstration from Patch #13.
>   $ bpftool prog dump jited id 1
>   int _dummy_tracepoint(struct dummy_tracepoint_args * ):
>   bpf_prog_b07ccb89267cf242__dummy_tracepoint:
>          0:   push   %rbp
>          1:   mov    %rsp,%rbp
>         ......
>         3c:   add    $0x28,%rbp
>         40:   leaveq
>         41:   retq
>   
>   int test_long_fname_1(struct dummy_tracepoint_args * ):
>   bpf_prog_2dcecc18072623fc_test_long_fname_1:
>          0:   push   %rbp
>          1:   mov    %rsp,%rbp

Considering we only had 16-byte names for main prog and
no names at all for subprogs, this is huge improvement
in BPF introspection.
Cannot wait for the followup patches with line info support.

For the set:
Acked-by: Alexei Starovoitov <ast@...nel.org>