> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -12041,7 +12041,15 @@ struct kprobe_multi_resolve res = {
> if (addrs && syms)
> return libbpf_err_ptr(-EINVAL);
>
> - if (pattern) {
> + /*
> + * Exact function name (no wildcards): bypass kallsyms parsing
> + * and pass the symbol directly to the kernel via syms[] array.
> + * The kernel's ftrace_lookup_symbols() resolves it efficiently.
> + */
> + if (pattern && !strpbrk(pattern, "*?")) {
> + syms = &pattern;
> + cnt = 1;
> + } else if (pattern) {
When the fast path is taken here, unique_match is never checked.
The unique_match validation is inside the "else if (pattern)"
branch:
if (unique_match && res.cnt != 1) {
pr_warn("prog '%s': failed to find a unique match ...");
err = -EINVAL;
goto error;
}
Before this change, a caller passing an exact function name with
unique_match = true would go through kallsyms parsing, which could
find multiple addresses for same-named static functions across
different translation units, and the unique_match check would
correctly return an error.
With the fast path, the name goes directly to the kernel's
ftrace_lookup_symbols(), which resolves only the first match via
kallsyms_callback() skipping duplicates:
if (args->addrs[idx])
return 0;
Should the fast path condition also check unique_match, for
example:
if (pattern && !strpbrk(pattern, "*?") && !unique_match) {
This would preserve the optimization for the common case while
falling back to the slow path when unique_match is explicitly
requested.
> [ ... ]
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/22503275616
AI-authorship-score: medium
AI-authorship-explanation: Comments are unusually verbose for a simple
optimization, and the commit message is well-structured with distinct sections,
but the iterative v1-v3 refinement following reviewer feedback is typical of
human development.
issues-found: 1
issue-severity-score: low
issue-severity-explanation: The fast path bypasses the unique_match check,
which could silently attach to the wrong function among same-named statics, but
requires the uncommon combination of unique_match=true with an exact name
matching multiple kernel functions.
