Re: [PATCH bpf-next 2/2] selftests: bpf: Add a new test for bare tracepoints

On Wed, Jan 13, 2021 at 10:21:31AM +0000, Qais Yousef wrote:

On 01/12/21 12:07, Andrii Nakryiko wrote:

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        $ sudo ./test_progs -v -t module_attach

use -vv when debugging stuff like that with test_progs, it will output
libbpf detailed logs, that often are very helpful

I tried that but it didn't help me. Full output is here

        https://paste.debian.net/1180846

It did help a bit for me to make sure that you have bpf_testmod
properly loaded and its BTF was found, so the problem is somewhere
else. Also, given load succeeded and attach failed with OPNOTSUPP, I
suspect you are missing some of FTRACE configs, which seems to be
missing from selftests's config as well. Check that you have
CONFIG_FTRACE=y and CONFIG_DYNAMIC_FTRACE=y, and you might need some
more. See [0] for a real config we are using to run all tests in
libbpf CI. If you figure out what you were missing, please also
contribute a patch to selftests' config.

  [0] https://github.com/libbpf/libbpf/blob/master/travis-ci/vmtest/configs/latest.config

Yeah that occurred to me too. I do have all necessary FTRACE options enabled,
including DYNAMIC_FTRACE. I think I did try enabling fault injection too just
in case. I have CONFIG_FAULT_INJECTION=y and CONFIG_FUNCTION_ERROR_INJECTION=y.

Could it come from lack of fentry support on arm64 (or are you testing on
x86?) Since the arm64 JIT doesn't have trampoline support at the moment, a
lot of bpf selftests fail with ENOTSUPP.

Thanks,
Jean