perf tests: Robustness and performance improvements

This patch series introduces several robustness and performance
improvements to the perf test suite, alongside fixes for long-standing
flakiness.

Key changes across the series:
- Introduces robust retry logic (`perf_record_with_retry`) to prevent
  spurious test failures due to transient `EPERM` issues during
  system-wide background profiling, safely extracting error messages from
  the PERF_RECORD_LOGS array.
- Significantly speeds up test execution across multiple scripts (such as
  kvm, record, trace, off-cpu, and lock contention) by supporting
  sub-second durations in the `noploop` and `thloop` workloads, reducing
  unnecessary wait times.
- Fixes flakiness in the BPF counters hybrid test by parsing `taskset` to
  determine valid CPUs rather than relying on `shuf`, which can fail under
  cgroups or missing binaries.
- Fixes JIT dump file leaks and TOCTOU vulnerabilities by securely staging
  with `mktemp -d` to guarantee cleanup.
- Decouples format alignments in `builtin-test.c` to gracefully truncate
  test descriptions without losing alignment or failing under non-TTY
  environments.
- Restricts uncore PMU bypass in event parsing strictly to `--cputype` to
  prevent unintended metric evaluation impacts.
- Injects trace output into JUnit XML `<skipped>` blocks to aid debugging.

Changes in v4:
- Rebased on top of latest `ptn/perf-tools-next` branch.
- Resolved merge conflicts in `util/metricgroup.c`, `util/parse-events.c`,
  and `util/python.c` from upstream `evlist` reference counting changes.
- Fixed a ShellCheck error in `trace_record_replay.sh` where `local` was
  used outside of a function.
- Cleaned up line length warnings from `checkpatch.pl` in
  `test_brstack.sh`.
- Simplified the `perf kvm record` test loop in `kvm.sh` to run `sleep`
  directly as a workload (instead of running in the background and
  killing), using `-e cpu-clock` explicitly to bypass the `perf kvm` option
  handling bug on x86/PowerPC platforms while remaining portable to
  architectures lacking a hardware cycles event (e.g. s390x).

Changes in v3:
- Fix line length warnings in checkpatch.pl.
- Fix wrap commit descriptions in checkpatch.pl.
- Re-aligned parse_events_state struct initializations.
- Added explanatory comment for the 10000 magic number in get_term_width().
- Added inline comments (e.g. /*cputype_filter=*/false) to boolean
  literal arguments.
- Fixed patch 4 to securely read from PERF_RECORD_LOGS array instead of
  unsafe wildcard cleanup.
- Fixed patch 6 TOCTOU vulnerability via mktemp -d staging directory.
- Implemented patch 13 to inject trace output into JUnit XML <skipped>
  blocks for debugging.
- Add Assisted-by tags to all commits.

Changes in v2:
- Drop the sleep 0 patch from v1.
- Introduce 'perf_record_with_retry' helper to encapsulate the retry logic
  and cleanly output error messages (patch 4).
- Fix issue with `perf record` lacking sufficient permissions on some
  setups (patch 5).
- Improve subsecond duration support in noploop/thloop (patch 3).
- Reduce test durations to avoid excessive overall runtimes.

Ian Rogers (13):
  perf parse-events: Restrict core PMU bypass to --cputype option
  perf test: Truncate test description to fit terminal width
  perf tests workloads: Support sub-second durations in noploop and
    thloop
  perf tests: Add robust record retry helper and use subsecond workloads
  perf tests: Skip metrics validation if system-wide recording lacks
    permission
  perf tests: Fix Python JIT dump profiling test failure
  perf tests: Fix flakiness in trace record and replay test
  perf tests: Fix flakiness in BPF counters test on hybrid systems
  perf tests: Fix flakiness in branch stack sampling tests
  perf tests: Speed up off-cpu profiling tests
  perf tests: Speed up lock contention analysis shell test
  perf tests: Speed up metrics checking shell tests
  perf tests: Include error output for skipped tests in JUnit XML

 tools/perf/builtin-script.c                   |   1 +
 tools/perf/builtin-stat.c                     |  20 +-
 tools/perf/tests/builtin-test.c               | 173 ++++++++++--------
 tools/perf/tests/expand-cgroup.c              |   3 +-
 tools/perf/tests/parse-events.c               |  11 +-
 tools/perf/tests/parse-metric.c               |   3 +-
 tools/perf/tests/pmu-events.c                 |  10 +-
 tools/perf/tests/shell/jitdump-python.sh      |  79 +++++---
 tools/perf/tests/shell/kvm.sh                 |  61 +++---
 .../tests/shell/lib/perf_metric_validation.py |  11 +-
 tools/perf/tests/shell/lib/perf_record.sh     |  58 ++++++
 tools/perf/tests/shell/lock_contention.sh     |  32 ++--
 tools/perf/tests/shell/pipe_test.sh           |   4 +-
 tools/perf/tests/shell/record.sh              | 173 +++++++++---------
 tools/perf/tests/shell/record_lbr.sh          |  50 +++--
 tools/perf/tests/shell/record_offcpu.sh       |  14 +-
 tools/perf/tests/shell/stat_all_metrics.sh    |  77 +++++---
 tools/perf/tests/shell/stat_bpf_counters.sh   |  28 ++-
 tools/perf/tests/shell/stat_metrics_values.sh |   9 +-
 tools/perf/tests/shell/test_brstack.sh        | 107 ++++++-----
 tools/perf/tests/shell/trace_record_replay.sh |  38 +++-
 tools/perf/tests/workloads/noploop.c          |  17 +-
 tools/perf/tests/workloads/thloop.c           |  16 +-
 tools/perf/util/metricgroup.c                 |  26 ++-
 tools/perf/util/metricgroup.h                 |   4 +-
 tools/perf/util/parse-events.c                |  32 ++--
 tools/perf/util/parse-events.h                |  17 +-
 tools/perf/util/python.c                      |   3 +-
 28 files changed, 687 insertions(+), 390 deletions(-)
 create mode 100644 tools/perf/tests/shell/lib/perf_record.sh

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2.55.0.rc0.786.g65d90a0328-goog