ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 73 insertions, 0 deletions

diff --git a/tools/perf/pmu-events/models.py b/tools/perf/pmu-events/models.py
new file mode 100755
index 000000000..8f727d29c
--- /dev/null
+++ b/tools/perf/pmu-events/models.py
@@ -0,0 +1,73 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+"""List model names from mapfile.csv files."""
+import argparse
+import csv
+import os
+import re
+from typing import List
+
+def main() -> None:
+    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 find_archs(start_dir: str, arch: str) -> List[str]:
+        archs = []
+        for item in os.scandir(start_dir):
+            if not item.is_dir():
+                continue
+            if arch in (item.name, 'all'):
+                archs.append(item.name)
+
+        if len(archs) < 1:
+            raise IOError(f'Missing architecture directory \'{arch}\'')
+
+        return archs
+
+    def find_mapfiles(start_dir: str, archs: List[str]) -> List[str]:
+        result = []
+        for arch in archs:
+            for item in os.scandir(f'{start_dir}/{arch}'):
+                if item.is_dir():
+                    continue
+                if item.name == 'mapfile.csv':
+                    result.append(f'{start_dir}/{arch}/mapfile.csv')
+        return result
+
+    def find_cpuids(mapfiles: List[str], cpuids: str) -> List[str]:
+        result = []
+        for mapfile in mapfiles:
+            with open(mapfile, encoding='utf-8') as csvfile:
+                first = False
+                table = csv.reader(csvfile)
+                for row in table:
+                    if not first or len(row) == 0 or row[0].startswith('#'):
+                        first = True
+                        continue
+                    # Python regular expressions don't handle xdigit.
+                    regex = row[0].replace('[[:xdigit:]]', '[0-9a-fA-F]')
+                    for cpuid in cpuids.split(','):
+                        if re.match(regex, cpuid):
+                            result.append(row[2])
+        return result
+
+    ap = argparse.ArgumentParser()
+    ap.add_argument('arch', help='Architecture name like x86')
+    ap.add_argument('cpuid', default='all', help='List of cpuids to convert to model names')
+    ap.add_argument(
+        'starting_dir',
+        type=dir_path,
+        help='Root of tree containing architecture directories containing json files'
+    )
+    args = ap.parse_args()
+
+    archs = find_archs(args.starting_dir, args.arch)
+    mapfiles = find_mapfiles(args.starting_dir, archs)
+    models = find_cpuids(mapfiles, args.cpuid)
+    print(','.join(models))
+
+if __name__ == '__main__':
+    main()