Subject: Re: [PATCH bpf-next v5 17/17] selftests/bpf: Simple program to dump XDP RX metadata

From: Martin KaFai Lau <[email-masked]>
Date: Thu, 22 Dec 2022 16:53:03 -0800

On 12/20/22 2:20 PM, Stanislav Fomichev wrote:
> To be used for verification of driver implementations. Note that
> the skb path is gone from the series, but I'm still keeping the
> implementation for any possible future work.
> 
> $ xdp_hw_metadata <ifname>
> 
> On the other machine:
> 
> $ echo -n xdp | nc -u -q1 <target> 9091 # for AF_XDP
> $ echo -n skb | nc -u -q1 <target> 9092 # for skb
> 
> Sample output:
> 
>    # xdp
>    xsk_ring_cons__peek: 1
>    0x19f9090: rx_desc[0]->addr=100000000008000 addr=8100 comp_addr=8000
>    rx_timestamp_supported: 1
>    rx_timestamp: 1667850075063948829
>    0x19f9090: complete idx=8 addr=8000
> 
>    # skb
>    found skb hwtstamp = 1668314052.854274681
> 
> Decoding:
>    # xdp
>    rx_timestamp=1667850075.063948829
> 
>    $ date -d @1667850075
>    Mon Nov  7 11:41:15 AM PST 2022
>    $ date
>    Mon Nov  7 11:42:05 AM PST 2022
> 
>    # skb
>    $ date -d @1668314052
>    Sat Nov 12 08:34:12 PM PST 2022
>    $ date
>    Sat Nov 12 08:37:06 PM PST 2022
> 
> Cc: John Fastabend <[email-masked]>
> Cc: David Ahern <[email-masked]>
> Cc: Martin KaFai Lau <[email-masked]>
> Cc: Jakub Kicinski <[email-masked]>
> Cc: Willem de Bruijn <[email-masked]>
> Cc: Jesper Dangaard Brouer <[email-masked]>
> Cc: Anatoly Burakov <[email-masked]>
> Cc: Alexander Lobakin <[email-masked]>
> Cc: Magnus Karlsson <[email-masked]>
> Cc: Maryam Tahhan <[email-masked]>
> Cc: [email-masked]
> Cc: [email-masked]
> Signed-off-by: Stanislav Fomichev <[email-masked]>
> ---
>   tools/testing/selftests/bpf/.gitignore        |   1 +
>   tools/testing/selftests/bpf/Makefile          |   6 +-
>   .../selftests/bpf/progs/xdp_hw_metadata.c     |  81 ++++
>   tools/testing/selftests/bpf/xdp_hw_metadata.c | 405 ++++++++++++++++++
>   4 files changed, 492 insertions(+), 1 deletion(-)
>   create mode 100644 tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
>   create mode 100644 tools/testing/selftests/bpf/xdp_hw_metadata.c
> 
> diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
> index 07d2d0a8c5cb..01e3baeefd4f 100644
> --- a/tools/testing/selftests/bpf/.gitignore
> +++ b/tools/testing/selftests/bpf/.gitignore
> @@ -46,3 +46,4 @@ test_cpp
>   xskxceiver
>   xdp_redirect_multi
>   xdp_synproxy
> +xdp_hw_metadata
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index e6cbc04a7920..b7d5d3aa554e 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -83,7 +83,7 @@ TEST_PROGS_EXTENDED := with_addr.sh \
>   TEST_GEN_PROGS_EXTENDED = test_sock_addr test_skb_cgroup_id_user \
>   	flow_dissector_load test_flow_dissector test_tcp_check_syncookie_user \
>   	test_lirc_mode2_user xdping test_cpp runqslower bench bpf_testmod.ko \
> -	xskxceiver xdp_redirect_multi xdp_synproxy veristat
> +	xskxceiver xdp_redirect_multi xdp_synproxy veristat xdp_hw_metadata
>   
>   TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read $(OUTPUT)/sign-file
>   TEST_GEN_FILES += liburandom_read.so
> @@ -241,6 +241,9 @@ $(OUTPUT)/test_maps: $(TESTING_HELPERS)
>   $(OUTPUT)/test_verifier: $(TESTING_HELPERS) $(CAP_HELPERS)
>   $(OUTPUT)/xsk.o: $(BPFOBJ)
>   $(OUTPUT)/xskxceiver: $(OUTPUT)/xsk.o
> +$(OUTPUT)/xdp_hw_metadata: $(OUTPUT)/xsk.o $(OUTPUT)/xdp_hw_metadata.skel.h
> +$(OUTPUT)/xdp_hw_metadata: $(OUTPUT)/network_helpers.o
> +$(OUTPUT)/xdp_hw_metadata: LDFLAGS += -static

This test binary fails to build for llvm.  gcc looks fine though.  The CI tests 
cannot be run on this set because of this.  Please take a look:

https://github.com/kernel-patches/bpf/actions/runs/3745257032/jobs/6359527599#step:11:2202

I only have minor comments on the set.  Looking forward to v6.