[PATCH v6 2/4] perf jevents: Add python converter script

[Ian Rogers]

jevents.c is large, has a dependency on an old forked version of jsmn,
and is challenging to work upon. A lot of jevents.c's complexity comes
from needing to write json and csv parsing from first principles. In
contrast python has this functionality in standard libraries and is
already a build pre-requisite for tools like asciidoc (that builds all
of the perf man pages).

Introduce jevents.py that produces identical output to jevents.c. Add a
test that runs both converter tools and validates there are no output
differences. The test can be invoked with a phony build target like:

make -C tools/perf jevents-py-test

The python code deliberately tries to replicate the behavior of
jevents.c so that the output matches and transitioning tools shouldn't
introduce regressions. In some cases the code isn't as elegant as hoped,
but fixing this can be done as follow up.

Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
 tools/perf/Makefile.perf              |   6 +
 tools/perf/pmu-events/jevents-test.sh |  33 +++
 tools/perf/pmu-events/jevents.py      | 409 ++++++++++++++++++++++++++
 3 files changed, 448 insertions(+)
 create mode 100755 tools/perf/pmu-events/jevents-test.sh
 create mode 100755 tools/perf/pmu-events/jevents.py

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 8f738e11356d..1e29c8936f71 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -669,6 +669,12 @@ $(JEVENTS_IN): FORCE
 $(JEVENTS): $(JEVENTS_IN)
 	$(QUIET_LINK)$(HOSTCC) $(JEVENTS_IN) -o $@
 
+JEVENTS_PY	:=  pmu-events/jevents.py
+JEVENTS_PY_TEST	:=  pmu-events/jevents-test.sh
+.PHONY: jevents-py-test
+jevents-py-test: $(JEVENTS)
+	$(Q)$(call echo-cmd,gen)$(JEVENTS_PY_TEST) $(JEVENTS) $(JEVENTS_PY) pmu-events/arch
+
 $(PMU_EVENTS_IN): $(JEVENTS) FORCE
 	$(Q)$(MAKE) -f $(srctree)/tools/build/Makefile.build dir=pmu-events obj=pmu-events
 
diff --git a/tools/perf/pmu-events/jevents-test.sh b/tools/perf/pmu-events/jevents-test.sh
new file mode 100755
index 000000000000..9ae852292576
--- /dev/null
+++ b/tools/perf/pmu-events/jevents-test.sh
@@ -0,0 +1,33 @@
+#!/bin/sh
+# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+# Validate that the legacy jevents and jevents.py produce identical output.
+set -e
+
+JEVENTS="$1"
+JEVENTS_PY="$2"
+ARCH_PATH="$3"
+JEVENTS_C_GENERATED=$(mktemp /tmp/jevents_c.XXXXX.c)
+JEVENTS_PY_GENERATED=$(mktemp /tmp/jevents_py.XXXXX.c)
+
+cleanup() {
+  rm "$JEVENTS_C_GENERATED" "$JEVENTS_PY_GENERATED"
+  trap - exit term int
+}
+trap cleanup exit term int
+
+for path in "$ARCH_PATH"/*
+do
+  arch=$(basename $path)
+  if [ "$arch" = "test" ]
+  then
+    continue
+  fi
+  echo "Checking architecture: $arch"
+  echo "Generating using jevents.c"
+  "$JEVENTS" "$arch" "$ARCH_PATH" "$JEVENTS_C_GENERATED"
+  echo "Generating using jevents.py"
+  "$JEVENTS_PY" "$arch" "$ARCH_PATH" "$JEVENTS_PY_GENERATED"
+  echo "Diffing"
+  diff -u "$JEVENTS_C_GENERATED" "$JEVENTS_PY_GENERATED"
+done
+cleanup
diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jevents.py
new file mode 100755
index 000000000000..83e0dcbeac9a
--- /dev/null
+++ b/tools/perf/pmu-events/jevents.py
@@ -0,0 +1,409 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+"""Convert directories of JSON events to C code."""
+import argparse
+import csv
+import json
+import os
+import sys
+from typing import Callable
+from typing import Sequence
+
+# Global command line arguments.
+_args = None
+# List of event tables generated from "/sys" directories.
+_sys_event_tables = []
+# Map from an event name to an architecture standard
+# JsonEvent. Architecture standard events are in json files in the top
+# f'{_args.starting_dir}/{_args.arch}' directory.
+_arch_std_events = {}
+# Track whether an events table is currently being defined and needs closing.
+_close_table = False
+
+
+def removesuffix(s: str, suffix: str) -> str:
+  """Remove the suffix from a string
+
+  The removesuffix function is added to str in Python 3.9. We aim for 3.6
+  compatibility and so provide our own function here.
+  """
+  return s[0:-len(suffix)] if s.endswith(suffix) else s
+
+
+def file_name_to_table_name(parents: Sequence[str], dirname: str) -> str:
+  """Generate a C table name from directory names."""
+  tblname = 'pme'
+  for p in parents:
+    tblname += '_' + p
+  tblname += '_' + dirname
+  return tblname.replace('-', '_')
+
+
+class JsonEvent:
+  """Representation of an event loaded from a json file dictionary."""
+
+  def __init__(self, jd: dict):
+    """Constructor passed the dictionary of parsed json values."""
+
+    def llx(x: int) -> str:
+      """Convert an int to a string similar to a printf modifier of %#llx."""
+      return '0' if x == 0 else hex(x)
+
+    def fixdesc(s: str) -> str:
+      """Fix formatting issue for the desc string."""
+      if s is None:
+        return None
+      return removesuffix(removesuffix(removesuffix(s, '.  '),
+                                       '. '), '.').replace('\n', '\\n').replace(
+                                           '\"', '\\"').replace('\r', '\\r')
+
+    def convert_aggr_mode(aggr_mode: str) -> str:
+      """Returns the aggr_mode_class enum value associated with the JSON string."""
+      if not aggr_mode:
+        return None
+      aggr_mode_to_enum = {
+          'PerChip': '1',
+          'PerCore': '2',
+      }
+      return aggr_mode_to_enum[aggr_mode]
+
+    def lookup_msr(num: str) -> str:
+      """Converts the msr number, or first in a list to the appropriate event field."""
+      if not num:
+        return None
+      msrmap = {
+          0x3F6: 'ldlat=',
+          0x1A6: 'offcore_rsp=',
+          0x1A7: 'offcore_rsp=',
+          0x3F7: 'frontend=',
+      }
+      return msrmap[int(num.split(',', 1)[0], 0)]
+
+    def real_event(name: str, event: str) -> str:
+      """Convert well known event names to an event string otherwise use the event argument."""
+      fixed = {
+          'inst_retired.any': 'event=0xc0,period=2000003',
+          'inst_retired.any_p': 'event=0xc0,period=2000003',
+          'cpu_clk_unhalted.ref': 'event=0x0,umask=0x03,period=2000003',
+          'cpu_clk_unhalted.thread': 'event=0x3c,period=2000003',
+          'cpu_clk_unhalted.core': 'event=0x3c,period=2000003',
+          'cpu_clk_unhalted.thread_any': 'event=0x3c,any=1,period=2000003',
+      }
+      if not name:
+        return None
+      if name.lower() in fixed:
+        return fixed[name.lower()]
+      return event
+
+    def unit_to_pmu(unit: str) -> str:
+      """Convert a JSON Unit to Linux PMU name."""
+      if not unit:
+        return None
+      # Comment brought over from jevents.c:
+      # it's not realistic to keep adding these, we need something more scalable ...
+      table = {
+          'CBO': 'uncore_cbox',
+          'QPI LL': 'uncore_qpi',
+          'SBO': 'uncore_sbox',
+          'iMPH-U': 'uncore_arb',
+          'CPU-M-CF': 'cpum_cf',
+          'CPU-M-SF': 'cpum_sf',
+          'UPI LL': 'uncore_upi',
+          'hisi_sicl,cpa': 'hisi_sicl,cpa',
+          'hisi_sccl,ddrc': 'hisi_sccl,ddrc',
+          'hisi_sccl,hha': 'hisi_sccl,hha',
+          'hisi_sccl,l3c': 'hisi_sccl,l3c',
+          'imx8_ddr': 'imx8_ddr',
+          'L3PMC': 'amd_l3',
+          'DFPMC': 'amd_df',
+          'cpu_core': 'cpu_core',
+          'cpu_atom': 'cpu_atom',
+      }
+      return table[unit] if unit in table else f'uncore_{unit.lower()}'
+
+    eventcode = 0
+    if 'EventCode' in jd:
+      eventcode = int(jd['EventCode'].split(',', 1)[0], 0)
+    if 'ExtSel' in jd:
+      eventcode |= int(jd['ExtSel']) << 8
+    configcode = int(jd['ConfigCode'], 0) if 'ConfigCode' in jd else None
+    self.name = jd['EventName'].lower() if 'EventName' in jd else None
+    self.compat = jd.get('Compat')
+    self.desc = fixdesc(jd.get('BriefDescription'))
+    self.long_desc = fixdesc(jd.get('PublicDescription'))
+    precise = jd.get('PEBS')
+    msr = lookup_msr(jd.get('MSRIndex'))
+    msrval = jd.get('MSRValue')
+    extra_desc = ''
+    if 'Data_LA' in jd:
+      extra_desc += '  Supports address when precise'
+      if 'Errata' in jd:
+        extra_desc += '.'
+    if 'Errata' in jd:
+      extra_desc += '  Spec update: ' + jd['Errata']
+    self.pmu = unit_to_pmu(jd.get('Unit'))
+    filter = jd.get('Filter')
+    self.unit = jd.get('ScaleUnit')
+    self.perpkg = jd.get('PerPkg')
+    self.aggr_mode = convert_aggr_mode(jd.get('AggregationMode'))
+    self.deprecated = jd.get('Deprecated')
+    self.metric_name = jd.get('MetricName')
+    self.metric_group = jd.get('MetricGroup')
+    self.metric_constraint = jd.get('MetricConstraint')
+    self.metric_expr = jd.get('MetricExpr')
+    if self.metric_expr:
+      self.metric_expr = self.metric_expr.replace('\\', '\\\\')
+    arch_std = jd.get('ArchStdEvent')
+    if precise and self.desc and not '(Precise Event)' in self.desc:
+      extra_desc += ' (Must be precise)' if precise == '2' else (' (Precise '
+                                                                 'event)')
+    event = f'config={llx(configcode)}' if configcode is not None else f'event={llx(eventcode)}'
+    event_fields = [
+        ('AnyThread', 'any='),
+        ('PortMask', 'ch_mask='),
+        ('CounterMask', 'cmask='),
+        ('EdgeDetect', 'edge='),
+        ('FCMask', 'fc_mask='),
+        ('Invert', 'inv='),
+        ('SampleAfterValue', 'period='),
+        ('UMask', 'umask='),
+    ]
+    for key, value in event_fields:
+      if key in jd and jd[key] != '0':
+        event += ',' + value + jd[key]
+    if filter:
+      event += f',{filter}'
+    if msr:
+      event += f',{msr}{msrval}'
+    if self.desc and extra_desc:
+      self.desc += extra_desc
+    if self.long_desc and extra_desc:
+      self.long_desc += extra_desc
+    if self.pmu:
+      if self.desc and not self.desc.endswith('. '):
+        self.desc += '. '
+      self.desc = (self.desc if self.desc else '') + ('Unit: ' + self.pmu + ' ')
+    if arch_std and arch_std.lower() in _arch_std_events:
+      event = _arch_std_events[arch_std.lower()].event
+      # Copy from the architecture standard event to self for undefined fields.
+      for attr, value in _arch_std_events[arch_std.lower()].__dict__.items():
+        if hasattr(self, attr) and not getattr(self, attr):
+          setattr(self, attr, value)
+
+    self.event = real_event(self.name, event)
+
+  def __repr__(self) -> str:
+    """String representation primarily for debugging."""
+    s = '{\n'
+    for attr, value in self.__dict__.items():
+      if value:
+        s += f'\t{attr} = {value},\n'
+    return s + '}'
+
+  def to_c_string(self, topic_local: str) -> str:
+    """Representation of the event as a C struct initializer."""
+
+    def attr_string(attr: str, value: str) -> str:
+      return '\t.%s = \"%s\",\n' % (attr, value)
+
+    def str_if_present(self, attr: str) -> str:
+      if not getattr(self, attr):
+        return ''
+      return attr_string(attr, getattr(self, attr))
+
+    s = '{\n'
+    for attr in ['name', 'event']:
+      s += str_if_present(self, attr)
+    if self.desc is not None:
+      s += attr_string('desc', self.desc)
+    else:
+      s += attr_string('desc', '(null)')
+    s += str_if_present(self, 'compat')
+    s += f'\t.topic = "{topic_local}",\n'
+    for attr in [
+        'long_desc', 'pmu', 'unit', 'perpkg', 'aggr_mode', 'metric_expr',
+        'metric_name', 'metric_group', 'deprecated', 'metric_constraint'
+    ]:
+      s += str_if_present(self, attr)
+    s += '},\n'
+    return s
+
+
+def read_json_events(path: str) -> Sequence[JsonEvent]:
+  """Read json events from the specified file."""
+  return json.load(open(path), object_hook=lambda d: JsonEvent(d))
+
+
+def preprocess_arch_std_files(archpath: str) -> None:
+  """Read in all architecture standard events."""
+  global _arch_std_events
+  for item in os.scandir(archpath):
+    if item.is_file() and item.name.endswith('.json'):
+      for event in read_json_events(item.path):
+        if event.name:
+          _arch_std_events[event.name.lower()] = event
+
+
+def print_events_table_prefix(tblname: str) -> None:
+  """Called when a new events table is started."""
+  global _close_table
+  if _close_table:
+    raise IOError('Printing table prefix but last table has no suffix')
+  _args.output_file.write(f'static const struct pmu_event {tblname}[] = {{\n')
+  _close_table = True
+
+
+def print_events_table_entries(item: os.DirEntry, topic: str) -> None:
+  """Create contents of an events table."""
+  if not _close_table:
+    raise IOError('Table entries missing prefix')
+  for event in read_json_events(item.path):
+    _args.output_file.write(event.to_c_string(topic))
+
+
+def print_events_table_suffix() -> None:
+  """Optionally close events table."""
+  global _close_table
+  if _close_table:
+    _args.output_file.write("""{
+\t.name = 0,
+\t.event = 0,
+\t.desc = 0,
+},
+};
+""")
+  _close_table = False
+
+
+def process_one_file(parents: Sequence[str], item: os.DirEntry) -> None:
+  """Process a JSON file during the main walk."""
+  global _sys_event_tables
+
+  def get_topic(topic: str) -> str:
+    return removesuffix(topic, '.json').replace('-', ' ')
+
+  def is_leaf_dir(path: str) -> bool:
+    for item in os.scandir(path):
+      if item.is_dir():
+        return False
+    return True
+
+  # model directory, reset topic
+  if item.is_dir() and is_leaf_dir(item.path):
+    print_events_table_suffix()
+
+    tblname = file_name_to_table_name(parents, item.name)
+    if item.name == 'sys':
+      _sys_event_tables.append(tblname)
+    print_events_table_prefix(tblname)
+    return
+
+  # base dir or too deep
+  level = len(parents)
+  if level == 0 or level > 4:
+    return
+
+  # Ignore other directories. If the file name does not have a .json
+  # extension, ignore it. It could be a readme.txt for instance.
+  if not item.is_file() or not item.name.endswith('.json'):
+    return
+
+  print_events_table_entries(item, get_topic(item.name))
+
+
+def print_mapping_table() -> None:
+  """Read the mapfile and generate the struct from cpuid string to event table."""
+  with open(f'{_args.starting_dir}/{_args.arch}/mapfile.csv') as csvfile:
+    table = csv.reader(csvfile)
+    _args.output_file.write(
+        'const struct pmu_events_map pmu_events_map[] = {\n')
+    first = True
+    for row in table:
+      # Skip the first row or any row beginning with #.
+      if not first and len(row) > 0 and not row[0].startswith('#'):
+        tblname = file_name_to_table_name([], row[2].replace('/', '_'))
+        _args.output_file.write("""{
+\t.cpuid = \"%s\",
+\t.version = \"%s\",
+\t.type = \"%s\",
+\t.table = %s
+},
+""" % (row[0].replace('\\', '\\\\'), row[1], row[3], tblname))
+      first = False
+
+  _args.output_file.write("""{
+\t.cpuid = "testcpu",
+\t.version = "v1",
+\t.type = "core",
+\t.table = pme_test_soc_cpu,
+},
+{
+\t.cpuid = 0,
+\t.version = 0,
+\t.type = 0,
+\t.table = 0,
+},
+};
+""")
+
+
+def print_system_mapping_table() -> None:
+  """C struct mapping table array for tables from /sys directories."""
+  _args.output_file.write(
+      '\nconst struct pmu_sys_events pmu_sys_event_tables[] = {\n')
+  for tblname in _sys_event_tables:
+    _args.output_file.write(f"""\t{{
+\t\t.table = {tblname},
+\t\t.name = \"{tblname}\",
+\t}},
+""")
+  _args.output_file.write("""\t{
+\t\t.table = 0
+\t},
+};
+""")
+
+
+def main() -> None:
+  global _args
+
+  def dir_path(path: str) -> str:
+    """Validate path is a directory for argparse."""
+    if os.path.isdir(path):
+      return path
+    raise argparse.ArgumentTypeError(f'\'{path}\' is not a valid directory')
+
+  def ftw(path: str, parents: Sequence[str],
+          action: Callable[[Sequence[str], os.DirEntry], None]) -> None:
+    """Replicate the directory/file walking behavior of C's file tree walk."""
+    for item in os.scandir(path):
+      action(parents, item)
+      if item.is_dir():
+        ftw(item.path, parents + [item.name], action)
+
+  ap = argparse.ArgumentParser()
+  ap.add_argument('arch', help='Architecture name like x86')
+  ap.add_argument(
+      'starting_dir',
+      type=dir_path,
+      help='Root of tree containing architecture directories containing json files'
+  )
+  ap.add_argument(
+      'output_file', type=argparse.FileType('w'), nargs='?', default=sys.stdout)
+  _args = ap.parse_args()
+
+  _args.output_file.write("#include \"pmu-events/pmu-events.h\"\n")
+  for path in [_args.arch, 'test']:
+    arch_path = f'{_args.starting_dir}/{path}'
+    if not os.path.isdir(arch_path):
+      raise IOError(f'Missing architecture directory in \'{arch_path}\'')
+    preprocess_arch_std_files(arch_path)
+    ftw(arch_path, [], process_one_file)
+    print_events_table_suffix()
+
+  print_mapping_table()
+  print_system_mapping_table()
+
+
+if __name__ == '__main__':
+  main()
-- 
2.36.1.476.g0c4daa206d-goog