netdev - Re: [PATCH] bpftool: Allow to read btf as raw data

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Date:   Fri, 25 Oct 2019 05:10:31 +0000
From:   Andrii Nakryiko <andriin@...com>
To:     Jiri Olsa <jolsa@...nel.org>, Alexei Starovoitov <ast@...nel.org>,
        "Daniel Borkmann" <daniel@...earbox.net>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        Yonghong Song <yhs@...com>, Martin Lau <kafai@...com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        "andrii.nakryiko@...il.com" <andrii.nakryiko@...il.com>
Subject: Re: [PATCH] bpftool: Allow to read btf as raw data

On 10/24/19 6:30 AM, Jiri Olsa wrote:
> The bpftool interface stays the same, but now it's possible
> to run it over BTF raw data, like:
> 
>    $ bpftool btf dump file /sys/kernel/btf/vmlinux
>    [1] INT '(anon)' size=4 bits_offset=0 nr_bits=32 encoding=(none)
>    [2] INT 'long unsigned int' size=8 bits_offset=0 nr_bits=64 encoding=(none)
>    [3] CONST '(anon)' type_id=2
> 
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
> v3 changes:
>   - fix title

The subject (by now) should be "[PATCH v3 bpf-next] ...". Include both 
version and intended tree (bpf-next usually).

> 
> v2 changes:
>   - added is_btf_raw to find out which btf__parse_* function to call
>   - changed labels and error propagation in btf__parse_raw
>   - drop the err initialization, which is not needed under this change
> 
>   tools/bpf/bpftool/btf.c | 57 ++++++++++++++++++++++++++++++++++++++++-
>   1 file changed, 56 insertions(+), 1 deletion(-)
> 


Overall looks good. It's kind of sad that we re-open that file twice, 
but we can optimize that later, if it ever is a problem. We should 
probably eventually implement btf__parse_raw as libbpf API with mmap2().
But perfect is the enemy of the good, so:

Acked-by: Andrii Nakryiko <andriin@...com>

> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
> index 9a9376d1d3df..a7b8bf233cf5 100644
> --- a/tools/bpf/bpftool/btf.c
> +++ b/tools/bpf/bpftool/btf.c
> @@ -12,6 +12,9 @@

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