Re: [PATCH v14 4/5] perf test: Add inject ASLR test

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The kernel workload for sampling (`dd if=/dev/zero of=/dev/null bs=1M count=500`) executes too quickly on modern systems, risking 0 kernel samples and causing flaky test failures.
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commit d9af52a5de1d8869d352d74aa99a8ba4f6d3011b
Author: Ian Rogers <irogers@google.com>

perf test: Add inject ASLR test

This commit adds a new shell test inject_aslr.sh to verify ASLR address
remapping. The test validates sample generation and address remapping
across basic operations, pipe modes, callchains, and kernel sampling.

> diff --git a/tools/perf/tests/shell/inject_aslr.sh b/tools/perf/tests/shell/inject_aslr.sh
> new file mode 100755
> index 0000000000000..d8ded16ba9052
> --- /dev/null
> +++ b/tools/perf/tests/shell/inject_aslr.sh
> @@ -0,0 +1,464 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# perf inject --aslr test
> +
> +set -e
> +set -o pipefail
> +
> +shelldir=$(dirname "$0")
> +# shellcheck source=lib/perf_has_symbol.sh
> +. "${shelldir}"/lib/perf_has_symbol.sh
> +
> +sym="noploop"
> +
> +skip_test_missing_symbol ${sym}
> +
> +# Create global temp directory
> +temp_dir=$(mktemp -d /tmp/perf-test-aslr.XXXXXXXXXX)
> +
> +prog="perf test -w noploop"
> +[ "$(uname -m)" = "s390x" ] && prog="$prog 3"
> +err=0
> +kprog="dd if=/dev/zero of=/dev/null bs=1M count=500"

[Severity: Medium]
Will this workload execute too quickly on modern systems?

The command transfers 500MB in 1MB chunks, resulting in only 1000 syscalls
which could complete in just a few milliseconds.

With perf record defaulting to a ~4000Hz sampling rate, a workload completing
this fast might generate very few or exactly 0 task-clock:k samples,
potentially causing flaky test failures.

Could we replace this with a syscall-bound workload, like using the default
512B block size with a larger count, to ensure consistent kernel execution
time irrespective of memory bandwidth?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260605205649.2566948-1-irogers@google.com?part=4