netdev - Re: [PATCH bpf-next v2 11/12] selftests/bpf: Convert test_flow

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Date:   Mon, 1 Jun 2020 15:42:04 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Jakub Sitnicki <jakub@...udflare.com>
Cc:     bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
        kernel-team@...udflare.com
Subject: Re: [PATCH bpf-next v2 11/12] selftests/bpf: Convert
 test_flow_dissector to use BPF skeleton

On Sun, May 31, 2020 at 1:29 AM Jakub Sitnicki <jakub@...udflare.com> wrote:
>
> Switch flow dissector test setup from custom BPF object loader to BPF
> skeleton to save boilerplate and prepare for testing higher-level API for
> attaching flow dissector with bpf_link.
>
> To avoid depending on program order in the BPF object when populating the
> flow dissector PROG_ARRAY map, change the program section names to contain
> the program index into the map. This follows the example set by tailcall
> tests.
>
> Signed-off-by: Jakub Sitnicki <jakub@...udflare.com>
> ---
>  .../selftests/bpf/prog_tests/flow_dissector.c | 50 +++++++++++++++++--
>  tools/testing/selftests/bpf/progs/bpf_flow.c  | 20 ++++----
>  2 files changed, 55 insertions(+), 15 deletions(-)
>

[...]

> diff --git a/tools/testing/selftests/bpf/progs/bpf_flow.c b/tools/testing/selftests/bpf/progs/bpf_flow.c
> index 9941f0ba471e..de6de9221518 100644
> --- a/tools/testing/selftests/bpf/progs/bpf_flow.c
> +++ b/tools/testing/selftests/bpf/progs/bpf_flow.c
> @@ -20,20 +20,20 @@
>  #include <bpf/bpf_endian.h>
>
>  int _version SEC("version") = 1;
> -#define PROG(F) SEC(#F) int bpf_func_##F
> +#define PROG(F) PROG_(F, _##F)
> +#define PROG_(NUM, NAME) SEC("flow_dissector/"#NUM) int bpf_func##NAME
>
>  /* These are the identifiers of the BPF programs that will be used in tail
>   * calls. Name is limited to 16 characters, with the terminating character and
>   * bpf_func_ above, we have only 6 to work with, anything after will be cropped.
>   */
> -enum {
> -       IP,
> -       IPV6,
> -       IPV6OP, /* Destination/Hop-by-Hop Options IPv6 Extension header */
> -       IPV6FR, /* Fragmentation IPv6 Extension Header */
> -       MPLS,
> -       VLAN,
> -};

not clear why? just add MAX_PROG after VLAN?

> +#define IP             0
> +#define IPV6           1
> +#define IPV6OP         2 /* Destination/Hop-by-Hop Options IPv6 Ext. Header */
> +#define IPV6FR         3 /* Fragmentation IPv6 Extension Header */
> +#define MPLS           4
> +#define VLAN           5
> +#define MAX_PROG       6
>
>  #define IP_MF          0x2000
>  #define IP_OFFSET      0x1FFF
> @@ -59,7 +59,7 @@ struct frag_hdr {
>
>  struct {
>         __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
> -       __uint(max_entries, 8);
> +       __uint(max_entries, MAX_PROG);
>         __uint(key_size, sizeof(__u32));
>         __uint(value_size, sizeof(__u32));
>  } jmp_table SEC(".maps");
> --
> 2.25.4
>