Re: [PATCH v2 12/14] perf tests: Check CoreSight syscall entry and exit

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] perf/tests: spurious test failure via masked skip code
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commit 9f0a06a503d95652f0f88ac67977ecbfd36fc578
Author: Leo Yan <leo.yan@arm.com>

perf tests: Check CoreSight syscall entry and exit

Record the existing callchain workload, which issues gettid() through
SVC. The test requires syscall/sysret pairs to advance the PC by four
bytes.

> diff --git a/tools/perf/tests/shell/coresight/syscall_entry_exit.sh b/tools/perf/tests/shell/coresight/syscall_entry_exit.sh
> new file mode 100755
> index 0000000000000..bf61b1fdf6f15
> --- /dev/null
> +++ b/tools/perf/tests/shell/coresight/syscall_entry_exit.sh
> @@ -0,0 +1,21 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# CoreSight syscall entry and exit (exclusive)
> +
> +# shellcheck source=../lib/coresight_exception.sh
> +. "$(dirname "$0")/../lib/coresight_exception.sh"
> +
> +test_syscall_entry_exit()
> +{
> +	# callchain() invokes gettid() through SVC, which returns to PC + 4.
> +	if ! record_trace callchain; then
> +		cat "$tmpdir/record.log"
> +		echo "Failed to record the callchain workload"
> +		return 1
> +	fi
> +	decode_trace || return 1
> +	check_exception_pairs "syscall" "sysret" 4 || return 1

[Severity: Medium]
When check_exception_pairs() returns 2 (SKIP) due to trace gaps eliminating all
complete entry/exit pairs, does this statement incorrectly translate that return
code into a hard failure?

Since the test workload recognizes this as a non-fatal condition, using
|| return 1 here triggers the short-circuit fallback because 2 is non-zero.
This forces a return status of 1 (FAIL), causing legitimate trace gaps under
load to produce test failures instead of graceful skips.

Additionally, returning FAIL here causes the cleanup() trap to leak temporary
directory artifacts into /tmp.

> +}
> +
> +setup_exception_test || exit $?
> +test_syscall_entry_exit

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Sashiko AI review · https://sashiko.dev/#/patchset/20260923-perf_cs_etm_fix_non_taken-v2-0-6ab8c07a5455@arm.com?part=12