> On Jun 16, 2023, at 1:52 AM, Leizhen (ThunderTown) <thunder.leizhen@xxxxxxxxxx> wrote: > > > > 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. I think livepatch should match symbols exactly anyway, so it is not necessary to expose more details in cleanup_symbol_name()? Thanks, Song
