Discussion with Thomas Richter in:
https://lore.kernel.org/lkml/20260306071002.2526085-1-tmricht@linux.ibm.com/
showed that the evsel__fallback wasn't working for s390. These patches
avoid the problematic frame pointer callchain on s390 and fix
evsel__fallback from a range of problems when falling back to a
software event. I simulated failures when developing the patches but
they are untested other than that.

v3: Incorporate feedback about event and callchain behavior for s390:
https://lore.kernel.org/lkml/20260312061628.1593105-1-irogers@google.com/

v2: try exclude_callchain_user for s390 rather than fully disabling
    the callchain. Fix a missed clearing of is_pmu_core if the
    software event fallback.
https://lore.kernel.org/lkml/20260312061628.1593105-1-irogers@google.com/

v1: https://lore.kernel.org/lkml/20260312031928.1494864-1-irogers@google.com/

Ian Rogers (3):
  perf evsel: Improve falling back from cycles
  perf target: Constify simple check functions
  perf evlist: Improve default event for s390

 tools/perf/builtin-record.c      |  3 +-
 tools/perf/builtin-top.c         |  2 +-
 tools/perf/tests/event_update.c  |  4 ++-
 tools/perf/tests/expand-cgroup.c |  4 ++-
 tools/perf/tests/perf-record.c   |  7 ++--
 tools/perf/tests/topology.c      |  4 ++-
 tools/perf/util/evlist.c         | 37 ++++++++++++---------
 tools/perf/util/evlist.h         |  2 +-
 tools/perf/util/evsel.c          | 56 +++++++++++++++++++++++---------
 tools/perf/util/evsel.h          |  2 ++
 tools/perf/util/target.h         | 12 +++----
 11 files changed, 88 insertions(+), 45 deletions(-)

-- 
2.53.0.851.ga537e3e6e9-goog