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

[sashiko-bot@kernel.org]

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
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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.

>  
>  	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;
>  }

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Sashiko AI review · https://sashiko.dev/#/patchset/20260929011139.53242-1-namhyung@kernel.org?part=3