Parsing the CSV or text output of perf stat can be problematic when
new output is added (columns in CSV format). JSON names values and
simplifies the job of parsing. Add a JSON output option to perf-stat
then add unit test that parses and validates the output.

This is a resend of two v2 patches:
https://lore.kernel.org/lkml/20210813220754.2104922-1-cjense@google.com/
https://lore.kernel.org/lkml/20210813220936.2105426-1-cjense@google.com/
with a few formatting changes and improvements to the linter.

v2. Fixes the system wide no aggregation test to not run if the
    paranoia is wrong. It also makes the counter-value check handle
    the "<not counted>" and "<not supported>" cases.

Claire Jensen (2):
  perf stat: Add JSON output option
  perf test: Json format checking

 tools/perf/Documentation/perf-stat.txt        |  21 +
 tools/perf/builtin-stat.c                     |   2 +
 .../tests/shell/lib/perf_json_output_lint.py  |  92 +++++
 tools/perf/tests/shell/stat+json_output.sh    | 147 +++++++
 tools/perf/util/stat-display.c                | 365 +++++++++++++-----
 tools/perf/util/stat.h                        |   1 +
 6 files changed, 542 insertions(+), 86 deletions(-)
 create mode 100644 tools/perf/tests/shell/lib/perf_json_output_lint.py
 create mode 100755 tools/perf/tests/shell/stat+json_output.sh

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2.36.0.550.gb090851708-goog