But CET should not be enabled in the kernel, it may break the Kprobes and bpf.
-Consequently, CET is disabled since v.11.
+Consequently, CET is disabled since v5.11.
To guarantee the manual symbol lookup worked, we only use up to v5.4.
Unfortunately, since Linux v5.7 \cpp|kallsyms_lookup_name| is also unexported, it needs certain trick to get the address of \cpp|kallsyms_lookup_name|.