On 2023/6/16 16:43, Leizhen (ThunderTown) wrote: > > > 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. And modify cleanup_symbol_name() not to cleanup these three suffixes. > >> >>> >>> Thanks, >>> Song >>> >>> >>> . >>> >> > -- Regards, Zhen Lei
