Re: [PATCH perf-tools-next v4 4/4] perf tests: Add shell test for kernel symbol beautifier

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] The test script erroneously fails on uniprocessor (UP) kernels due to a missing SMP-only tracepoint.
- [Medium] The test script can hang the test suite indefinitely on quiescent systems due to unbounded system-wide waits.
--

--- Patch [4]: [PATCH perf-tools-next v4 4/4] perf tests: Add shell test for kernel symbol beautifier ---
commit c9c4a1b0dcd918dc4702b41032200c74d4363a15
Author: Aaron Tomlin <[email protected]>

perf tests: Add shell test for kernel symbol beautifier

This commit adds a dedicated shell test script to verify that perf trace
properly symbolises kernel virtual addresses and function pointers using
both the default kallsyms beautifier and BTF type routing.

> diff --git a/tools/perf/tests/shell/trace_ksym_beautifier.sh b/tools/perf/tests/shell/trace_ksym_beautifier.sh
> new file mode 100755
> index 0000000000000..c030b03e2b662
> --- /dev/null
> +++ b/tools/perf/tests/shell/trace_ksym_beautifier.sh
> @@ -0,0 +1,43 @@
[ ... ]
> +test_ksym_kallsyms() {
> +  echo "Testing perf trace kernel symbol beautifier (default kallsyms)"
> +  output="$(perf trace -e kmem:kmalloc --max-events=1 2>&1)"

[Severity: Medium]
Could this wait indefinitely on a completely quiescent system?

Because it waits system-wide for the kmem:kmalloc event without a timeout or
a deterministic workload to trigger it, it might stall the test suite if the
event takes too long to fire.

> +  if ! echo "$output" | grep -q -E "call_site: [a-zA-Z_][a-zA-Z0-9_]*" || echo "$output" | grep -q -E "call_site: 0x[0-9a-fA-F]+"
> +  then
> +    printf "Default kallsyms function symbolization failed, output:\n%s\n" "$output"
> +    err=1
> +  fi
> +}
> +
> +test_ksym_btf() {
> +  echo "Testing perf trace kernel symbol beautifier (BTF)"
> +  if [ ! -f /sys/kernel/btf/vmlinux ]; then
> +    echo "Skipping BTF test due to missing vmlinux BTF"
> +    return
> +  fi
> +
> +  output="$(perf trace -e csd:csd_function_entry --force-btf --max-events=1 2>&1)"

[Severity: Medium]
Will this test fail erroneously on uniprocessor (UP) kernels?

The csd:csd_function_entry tracepoint is defined in kernel/smp.c, which is
only available when CONFIG_SMP is enabled. On a UP kernel, perf trace will
fail with an unknown tracepoint error, which the script would parse as a
symbolization failure.

[Severity: Medium]
Additionally, can this cause an indefinite hang on idle SMP systems?

The csd:csd_function_entry event relies on SMP cross-calls (IPIs). On an idle
or isolated test VM, this event might not occur organically for extended
periods, potentially causing perf trace to block forever without a timeout or
a triggering workload.

> +  if ! echo "$output" | grep -q -E "func: [a-zA-Z_][a-zA-Z0-9_]*" || echo "$output" | grep -q -E "func: 0x[0-9a-fA-F]+"
[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=4