netdev - Re: [PATCH v4 bpf-next 3/4] bpf: Add kernel module with user mode driver that populates bpffs.

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Message-ID: <cbf754f2-714f-1493-09c9-b01cc4c3f70d@iogearbox.net>
Date:   Thu, 30 Jul 2020 01:06:17 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        davem@...emloft.net
Cc:     torvalds@...ux-foundation.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, kernel-team@...com
Subject: Re: [PATCH v4 bpf-next 3/4] bpf: Add kernel module with user mode
 driver that populates bpffs.

On 7/24/20 10:38 PM, Alexei Starovoitov wrote:
> From: Alexei Starovoitov <ast@...nel.org>
> 
> Add kernel module with user mode driver that populates bpffs with
> BPF iterators.
> 
> $ mount bpffs /my/bpffs/ -t bpf
> $ ls -la /my/bpffs/
> total 4
> drwxrwxrwt  2 root root    0 Jul  2 00:27 .
> drwxr-xr-x 19 root root 4096 Jul  2 00:09 ..
> -rw-------  1 root root    0 Jul  2 00:27 maps.debug
> -rw-------  1 root root    0 Jul  2 00:27 progs.debug
> 
> The user mode driver will load BPF Type Formats, create BPF maps, populate BPF
> maps, load two BPF programs, attach them to BPF iterators, and finally send two
> bpf_link IDs back to the kernel.
> The kernel will pin two bpf_links into newly mounted bpffs instance under
> names "progs.debug" and "maps.debug". These two files become human readable.
> 
> $ cat /my/bpffs/progs.debug
>    id name            attached
>    11 dump_bpf_map    bpf_iter_bpf_map
>    12 dump_bpf_prog   bpf_iter_bpf_prog
>    27 test_pkt_access
>    32 test_main       test_pkt_access test_pkt_access
>    33 test_subprog1   test_pkt_access_subprog1 test_pkt_access
>    34 test_subprog2   test_pkt_access_subprog2 test_pkt_access
>    35 test_subprog3   test_pkt_access_subprog3 test_pkt_access
>    36 new_get_skb_len get_skb_len test_pkt_access
>    37 new_get_skb_ifindex get_skb_ifindex test_pkt_access
>    38 new_get_constant get_constant test_pkt_access
> 
> The BPF program dump_bpf_prog() in iterators.bpf.c is printing this data about
> all BPF programs currently loaded in the system. This information is unstable
> and will change from kernel to kernel as ".debug" suffix conveys.
> 
> Signed-off-by: Alexei Starovoitov <ast@...nel.org>

Looks like this needs one last respin, but either way the module handling looks much
cleaner now, Ack.

Thanks,
Daniel