reproduce:
        # https://github.com/xinli-intel/linux-fred-public/commit/4b2842c656154e388824e16959e0981ab3bb71ac
        git remote add xinli-intel-fred-public https://github.com/xinli-intel/linux-fred-public.git
        git fetch --no-tags xinli-intel-fred-public fix_sp_calculation
        git checkout 4b2842c656154e388824e16959e0981ab3bb71ac
        make W=1 O=/tmp/kselftest headers
        make W=1 O=/tmp/kselftest -C tools/testing/selftests
        make W=1 O=/tmp/kselftest -C tools/testing/selftests/bpf