[PATCH v7 1/1] perf jevents: Check the keys of the JSON tables

[TAKANO Mitsuhiro <takano32@gmail.com>]

jevents.py takes the fields it wants out of each JSON object by name and
ignores the rest, so a key that is spelled differently is dropped without
a word and the object is built without whatever that field held.  Two of
those are in the tree: "PublicDescrition" in 16 entries of an Arm table,
and "BriefDescript6ion" in one entry each of three AMD tables.

A table may carry 51 keys; 47 of them jevents.py reads, one more metric.py
reads, and three are read by nothing although the tables hold them
(Counter, CountersNumFixed, CountersNumGeneric).  A key outside that list
is reported with the file that carries it.  There is no cut-off, no
similarity and nothing that depends on what a run of the generator
happened to read.

The check is not a JSON schema because perf's build would then require
jsonschema, which it does not use today and which is not in every
builder's python.  It runs as a perf test, not as part of the build.

On the tree today it reports 19 keys in four tables.

Signed-off-by: TAKANO Mitsuhiro <takano32@gmail.com>
---
v7: one patch instead of three.  Patches 1 and 2 are dropped with the
    Makefile target, the arch filter, the summary line and the handling
    of tables that hold a single object; what is left is the walk, the
    set difference against the list, and the file the object is in.

 tools/perf/pmu-events/jevents.py        | 38 +++++++++++++++++++++++++
 tools/perf/tests/shell/jevents_check.sh | 24 ++++++++++++++++
 2 files changed, 62 insertions(+)
 create mode 100755 tools/perf/tests/shell/jevents_check.sh

diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jevents.py
index 080e04b51b8c..397b4fc97749 100755
--- a/tools/perf/pmu-events/jevents.py
+++ b/tools/perf/pmu-events/jevents.py
@@ -7,6 +7,7 @@ import json
 import metric
 import os
 import sys
+from pathlib import Path
 from typing import (Callable, Dict, Optional, Sequence, Set, Tuple)
 import collections
 
@@ -1450,6 +1451,38 @@ def _init_worker(std_events: dict) -> None:
   global _arch_std_events
   _arch_std_events = std_events
 
+# The keys a json object under arch/ may carry.  jevents.py takes the fields it
+# wants by name and ignores the rest, so a key that is spelled differently is
+# dropped without a word; this is the list a table is allowed to contain.
+_TABLE_KEYS: Set[str] = {
+    'AggregationMode', 'AnyThread', 'ArchStdEvent', 'BriefDescription',
+    'Compat', 'ConfigCode', 'Counter', 'CounterMask',
+    'CountersNumFixed', 'CountersNumGeneric', 'Data_LA', 'DefaultMetricgroupName',
+    'DefaultShowEvents', 'Deprecated', 'EdgeDetect', 'EnAllCores',
+    'EnAllSlices', 'Errata', 'EventCode', 'EventidCode',
+    'EventName', 'Experimental', 'ExtSel', 'FCMask',
+    'Filter', 'Invert', 'LegacyCacheCode', 'LegacyConfigCode',
+    'MetricConstraint', 'MetricExpr', 'MetricGroup', 'MetricgroupNoGroup',
+    'MetricName', 'MetricThreshold', 'MSRIndex', 'MSRValue',
+    'NodeType', 'PEBS', 'PerPkg', 'PortMask',
+    'PublicDescription', 'RdWrMask', 'RetirementLatencyMax', 'RetirementLatencyMean',
+    'RetirementLatencyMin', 'SampleAfterValue', 'ScaleUnit', 'SliceId',
+    'ThreadMask', 'UMask', 'Unit',
+}
+
+def _check_tables(root: str) -> int:
+  """Report the keys in the tables under root that a table may not carry."""
+  bad = 0
+  for path in sorted(Path(root).rglob('*.json')):
+    if path.name.endswith('metricgroups.json'):
+      # A dictionary keyed by metric group name, not a list of events.
+      continue
+    for obj in json.loads(path.read_text(encoding='utf-8')):
+      if extra := set(obj) - _TABLE_KEYS:
+        print(f'{path}: {sorted(extra)}')
+        bad += 1
+  return 1 if bad else 0
+
 def main() -> None:
   global _args
 
@@ -1494,8 +1527,13 @@ such as "arm/cortex-a34".''',
       'output_file', type=argparse.FileType('w', encoding='utf-8'), nargs='?', default=sys.stdout)
   ap.add_argument(
       'output_string_file', type=argparse.FileType('w', encoding='utf-8'), nargs='?', default=None)
+  ap.add_argument('--check', action='store_true',
+                  help='check the keys of the tables under starting_dir and exit')
   _args = ap.parse_args()
 
+  if _args.check:
+    sys.exit(_check_tables(_args.starting_dir))
+
   _args.output_file.write(f"""/* SPDX-License-Identifier: GPL-2.0 */
 /* THIS FILE WAS AUTOGENERATED BY `jevents.py arch={_args.arch} model={_args.model}` ! */
 """)
diff --git a/tools/perf/tests/shell/jevents_check.sh b/tools/perf/tests/shell/jevents_check.sh
new file mode 100755
index 000000000000..eb3125e1486a
--- /dev/null
+++ b/tools/perf/tests/shell/jevents_check.sh
@@ -0,0 +1,24 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# jevents_check: an unknown key in a table is reported (no_mlock)
+#
+# A key that is spelled differently is dropped without a word, so the keys of
+# the tables are checked against the list jevents.py reads.
+
+jevents=$(dirname "$0")/../../pmu-events/jevents.py
+[ -r "${jevents}" ] || exit 2
+
+tmp=$(mktemp -d)
+trap 'rm -rf "${tmp}"' EXIT
+tables="${tmp}/arch/x86/model"
+mkdir -p "${tables}"
+
+# Known keys pass.
+printf '[{"EventName": "a", "EventCode": "0x1"}]\n' > "${tables}/events.json"
+python3 "${jevents}" x86 all "${tmp}/arch" --check > /dev/null || exit 1
+
+# A key the generator does not read is reported.
+printf '[{"EventName": "a", "NotAKey": "x"}]\n' > "${tables}/events.json"
+python3 "${jevents}" x86 all "${tmp}/arch" --check > /dev/null && exit 1
+
+exit 0
-- 
2.53.0