Re: [PATCH v3 17/21] objtool/klp: Don't correlate arm64 mapping symbols

On Fri, May 15, 2026 at 01:19:47AM +0000, [email protected] wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] The `is_mapping_sym()` function relies on an overly broad substring match (`strchr(sym->name, '$')`), which risks falsely classifying any unannotated (`STT_NOTYPE`) symbol containing a `$` as an ARM64 mapping symbol.
> --
> 
> commit fb925cb10f7a9c6ab8ecefca87d3cd3b4e4da879
> Author: Josh Poimboeuf <[email protected]>
> 
> objtool/klp: Don't correlate arm64 mapping symbols
> 
> This commit updates the livepatch diff tool to skip the correlation of arm64
> mapping symbols. These symbols mark transitions between code and data but are
> not standard symbols that require correlation.
> 
> > diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
> > index eb21f3bf3120b..e1d4d94c9d77c 100644
> > --- a/tools/objtool/klp-diff.c
> > +++ b/tools/objtool/klp-diff.c
> > @@ -501,6 +501,7 @@ static bool dont_correlate(struct symbol *sym)
> >  	       is_prefix_func(sym) ||
> >  	       is_uncorrelated_static_local(sym) ||
> >  	       is_local_label(sym) ||
> > +	       is_mapping_sym(sym) ||
> 
> Does this code risk falsely classifying user-defined or macro-generated
> assembly labels as mapping symbols?
> 
> Looking at the definition:
> 
> tools/objtool/include/objtool/elf.h:is_mapping_sym() {
>         return is_notype_sym(sym) && strchr(sym->name, '$');
> }
> 
> Because it relies on a broad substring match, could this exclude valid
> unannotated STT_NOTYPE symbols containing a $ from correlation across all
> architectures?
> 
> Triggering a livepatching failure would require an unusual edge case, but
> would it be safer to use a stricter match for standard arm64 mapping symbol
> formats like $x or $d?

Not realistic.

-- 
Josh