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, 101 insertions, 0 deletions

diff --git a/tools/include/nolibc/getopt.h b/tools/include/nolibc/getopt.h
new file mode 100644
index 000000000..3ad140f69
--- /dev/null
+++ b/tools/include/nolibc/getopt.h
@@ -0,0 +1,101 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * getopt function definitions for NOLIBC, adapted from musl libc
+ * Copyright (C) 2005-2020 Rich Felker, et al.
+ * Copyright (C) 2025 Thomas Weißschuh <linux@weissschuh.net>
+ */
+
+/* make sure to include all global symbols */
+#include "nolibc.h"
+
+#ifndef _NOLIBC_GETOPT_H
+#define _NOLIBC_GETOPT_H
+
+struct FILE;
+static struct FILE *const stderr;
+static int fprintf(struct FILE *stream, const char *fmt, ...);
+
+__attribute__((weak,unused,section(".data.nolibc_getopt")))
+char *optarg;
+
+__attribute__((weak,unused,section(".data.nolibc_getopt")))
+int optind = 1, opterr = 1, optopt;
+
+static __attribute__((unused))
+int getopt(int argc, char * const argv[], const char *optstring)
+{
+	static int __optpos;
+	int i;
+	char c, d;
+	char *optchar;
+
+	if (!optind) {
+		__optpos = 0;
+		optind = 1;
+	}
+
+	if (optind >= argc || !argv[optind])
+		return -1;
+
+	if (argv[optind][0] != '-') {
+		if (optstring[0] == '-') {
+			optarg = argv[optind++];
+			return 1;
+		}
+		return -1;
+	}
+
+	if (!argv[optind][1])
+		return -1;
+
+	if (argv[optind][1] == '-' && !argv[optind][2])
+		return optind++, -1;
+
+	if (!__optpos)
+		__optpos++;
+	c = argv[optind][__optpos];
+	optchar = argv[optind] + __optpos;
+	__optpos++;
+
+	if (!argv[optind][__optpos]) {
+		optind++;
+		__optpos = 0;
+	}
+
+	if (optstring[0] == '-' || optstring[0] == '+')
+		optstring++;
+
+	i = 0;
+	d = 0;
+	do {
+		d = optstring[i++];
+	} while (d && d != c);
+
+	if (!d || d != c || c == ':') {
+		optopt = c;
+		if (optstring[0] != ':' && opterr)
+			fprintf(stderr, "%s: unrecognized option: %c\n", argv[0], *optchar);
+		return '?';
+	}
+	if (optstring[i] == ':') {
+		optarg = NULL;
+		if (optstring[i + 1] != ':' || __optpos) {
+			optarg = argv[optind++];
+			if (__optpos)
+				optarg += __optpos;
+			__optpos = 0;
+		}
+		if (optind > argc) {
+			optopt = c;
+			if (optstring[0] == ':')
+				return ':';
+			if (opterr)
+				fprintf(stderr, "%s: option requires argument: %c\n",
+					argv[0], *optchar);
+			return '?';
+		}
+	}
+	return c;
+}
+
+#endif /* _NOLIBC_GETOPT_H */