Re: [PATCH v2 3/8] perf tools: Check system path when check debuginfo

[Namhyung Kim <namhyung@kernel.org>]

On Tue, Sep 29, 2026 at 01:23:02AM +0000, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [High] perf: skipping libdw fallback on stripped binaries breaks debuginfod
> --
> 
> commit b8cad86bb3e8eff20f4bbb18f568843350d829d9
> Author: Namhyung Kim <namhyung@kernel.org>
> 
> perf tools: Check system path when check debuginfo
> 
> This commit refactors debuginfo__new() to check the system path via
> dso__find_dbginfo_type() rather than using an explicit fallback. The new
> approach adds DSO_BINARY_TYPE__SYSTEM_PATH_DSO to the debuginfo types list
> and removes the fallback code in debuginfo__new().
> 
> > diff --git a/tools/perf/util/debuginfo.c b/tools/perf/util/debuginfo.c
> > index d6bd0fcc22648..2669d5f5ee612 100644
> > --- a/tools/perf/util/debuginfo.c
> > +++ b/tools/perf/util/debuginfo.c
> [ ... ]
> > @@ -114,18 +114,12 @@ struct debuginfo *debuginfo__new(const char *path)
> >  	dso__find_dbginfo_type(dso);
> >  	if (dso__read_binary_type_filename(dso, dso__dbginfo_type(dso), &nil,
> >  					   buf, PATH_MAX) < 0)
> > -		goto out;
> > +		return NULL;
> 
> [Severity: High]
> Does this skip the libdw fallback entirely for stripped binaries, which
> could break remote debuginfo resolution via debuginfod?
> 
> When running a tool like perf annotate on a stripped binary that lacks local
> debuginfo files, dso__find_dbginfo_type() checks for debug sections:
> 
> tools/perf/util/dso.c:dso__find_dbginfo_type() {
>     ...
> 		if (filename__has_section(buf, ".debug_info") ||
> 		    filename__has_section(buf, ".zdebug_info"))
> 			break;
>     ...
> }
> 
> Because stripped binaries fail this section check, their type is marked as
> DSO_BINARY_TYPE__NOT_FOUND even when DSO_BINARY_TYPE__SYSTEM_PATH_DSO is
> evaluated.
> 
> This causes the dso__read_binary_type_filename() check in debuginfo__new()
> to fail and return NULL early. By bypassing __debuginfo__new(), this
> prevents libdw from invoking dwfl_standard_find_debuginfo() to remotely
> resolve the debuginfo.

I think this is what Arnaldo wanted to add.  As we already have
debuginfod support, I think it's better to check it explicitly with
introducing DSO_BINARY_TYPE__DEBUGINFOD or so.

By checking sections, it would be independent from libdw support which
may be useful for minimal systems that only uses external tools like
addr2line.

Thanks,
Namhyung

> 
> >  
> >  	dinfo = __debuginfo__new(buf);
> >  	dso__put(dso);
> >  
> > -out:
> > -	if (dinfo)
> > -		return dinfo;
> > -
> > -	/* if failed to open all distro debuginfo, open given binary */
> > -	symbol__join_symfs(buf, path);
> > -	return __debuginfo__new(buf);
> > +	return dinfo;
> >  }
> 
> -- 
> Sashiko AI review · https://sashiko.dev/#/patchset/20260929011139.53242-1-namhyung@kernel.org?part=3