reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/crng/random.git/commit/?id=31d9fc7a210b43f1c91871c994415652fe8eb3d8
        git remote add crng-random https://git.kernel.org/pub/scm/linux/kernel/git/crng/random.git
        git fetch --no-tags crng-random jd/vdso-test-harness
        git checkout 31d9fc7a210b43f1c91871c994415652fe8eb3d8
        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