On Mon, Feb 17, 2020 at 5:03 AM Eelco Chaudron <echaudro@xxxxxxxxxx> wrote:
>
> Use the new bpf_program__set_attach_target() API in the xdp_bpf2bpf
> selftest so it can be referenced as an example on how to use it.
>
>
nit: extra empty line?
> Acked-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
> Signed-off-by: Eelco Chaudron <echaudro@xxxxxxxxxx>
> ---
> .../testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c | 16 +++++++++++++---
> .../testing/selftests/bpf/progs/test_xdp_bpf2bpf.c | 4 ++--
> 2 files changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c
> index 6b56bdc73ebc..513fdbf02b81 100644
> --- a/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c
> +++ b/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c
> @@ -14,7 +14,7 @@ void test_xdp_bpf2bpf(void)
> struct test_xdp *pkt_skel = NULL;
> struct test_xdp_bpf2bpf *ftrace_skel = NULL;
> struct vip key4 = {.protocol = 6, .family = AF_INET};
> - DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
> + struct bpf_program *prog;
>
> /* Load XDP program to introspect */
> pkt_skel = test_xdp__open_and_load();
> @@ -27,11 +27,21 @@ void test_xdp_bpf2bpf(void)
> bpf_map_update_elem(map_fd, &key4, &value4, 0);
>
> /* Load trace program */
> - opts.attach_prog_fd = pkt_fd,
> - ftrace_skel = test_xdp_bpf2bpf__open_opts(&opts);
> + ftrace_skel = test_xdp_bpf2bpf__open();
> if (CHECK(!ftrace_skel, "__open", "ftrace skeleton failed\n"))
> goto out;
>
> + /* Demonstrate the bpf_program__set_attach_target() API rather than
> + * the load with options, i.e. opts.attach_prog_fd.
> + */
> + prog = *ftrace_skel->skeleton->progs[0].prog;
it took me a while to understand what's going on here... :) You are
not supposed to peek into ftrace_skel->skeleton, it's an "internal"
object that's passed into libbpf.
It's better to write it as a nice and short:
prog = ftrace_skel->progs.trace_on_entry;
> + bpf_program__set_expected_attach_type(prog, BPF_TRACE_FENTRY);
> + bpf_program__set_attach_target(prog, pkt_fd, "_xdp_tx_iptunnel");
> +
> + prog = *ftrace_skel->skeleton->progs[1].prog;
same as above: ftrace_skel->progs.trace_on_exit
> + bpf_program__set_expected_attach_type(prog, BPF_TRACE_FEXIT);
> + bpf_program__set_attach_target(prog, pkt_fd, "_xdp_tx_iptunnel");
> +
> err = test_xdp_bpf2bpf__load(ftrace_skel);
> if (CHECK(err, "__load", "ftrace skeleton failed\n"))
> goto out;
> diff --git a/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c b/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c
> index cb8a04ab7a78..b840fc9e3ed5 100644
> --- a/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c
> +++ b/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c
> @@ -28,7 +28,7 @@ struct xdp_buff {
> } __attribute__((preserve_access_index));
>
> __u64 test_result_fentry = 0;
> -SEC("fentry/_xdp_tx_iptunnel")
> +SEC("fentry/FUNC")
> int BPF_PROG(trace_on_entry, struct xdp_buff *xdp)
> {
> test_result_fentry = xdp->rxq->dev->ifindex;
> @@ -36,7 +36,7 @@ int BPF_PROG(trace_on_entry, struct xdp_buff *xdp)
> }
>
> __u64 test_result_fexit = 0;
> -SEC("fexit/_xdp_tx_iptunnel")
> +SEC("fexit/FUNC")
> int BPF_PROG(trace_on_exit, struct xdp_buff *xdp, int ret)
> {
> test_result_fexit = ret;
>
