On 2023/6/16 16:11, Leizhen (ThunderTown) wrote: > > > On 2023/6/16 13:01, Song Liu wrote: >> >> >>> On Jun 15, 2023, at 7:19 PM, Leizhen (ThunderTown) <thunder.leizhen@xxxxxxxxxx> wrote: >>> >>> On 2023/6/16 1:00, Song Liu wrote: >>>> With CONFIG_LTO_CLANG, kallsyms.c:cleanup_symbol_name() removes symbols >>>> suffixes during comparison. This is problematic for livepatch, as >>>> kallsyms_on_each_match_symbol may find multiple matches for the same >>>> symbol, and fail with: >>>> >>>> livepatch: unresolvable ambiguity for symbol 'xxx' in object 'yyy' >>> >>> Did you forget to specify 'old_sympos'? When there are multiple symbols with >>> the same name, we need to specify the sequence number of the symbols to be >>> matched. >> >> >> old_sympos is indeed 0 here. However, the issue with CONFIG_LTO_CLANG >> is different. Here is an example: >> >> $ grep bpf_verifier_vlog /proc/kallsyms >> ffffffff81549f60 t bpf_verifier_vlog >> ffffffff8268b430 d bpf_verifier_vlog._entry >> ffffffff8282a958 d bpf_verifier_vlog._entry_ptr >> ffffffff82e12a1f d bpf_verifier_vlog.__already_done >> >> kallsyms_on_each_match_symbol matches "bpf_verifier_vlog" to all of >> these because of cleanup_symbol_name(). IOW, we only have one >> function called bpf_verifier_vlog, but kallsyms_on_each_match_symbol() >> matches it to bpf_verifier_vlog.*. >> >> Does this make sense? > > Sorry. I mistakenly thought you were operating a static function. > > These suffixes are not mentioned in the comments in the function > cleanup_symbol_name(). So I didn't notice it. We can keep these three suffixes on the kallsyms tool end. > >> >> Thanks, >> Song >> >> >> . >> > -- Regards, Zhen Lei
