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, 134 insertions, 0 deletions

diff --git a/lib/uuid.c b/lib/uuid.c
new file mode 100644
index 000000000..128a51f18
--- /dev/null
+++ b/lib/uuid.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Unified UUID/GUID definition
+ *
+ * Copyright (C) 2009, 2016 Intel Corp.
+ *	Huang Ying <ying.huang@intel.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/ctype.h>
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/hex.h>
+#include <linux/uuid.h>
+#include <linux/random.h>
+
+const guid_t guid_null;
+EXPORT_SYMBOL(guid_null);
+const uuid_t uuid_null;
+EXPORT_SYMBOL(uuid_null);
+
+const u8 guid_index[16] = {3,2,1,0,5,4,7,6,8,9,10,11,12,13,14,15};
+const u8 uuid_index[16] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
+
+/**
+ * generate_random_uuid - generate a random UUID
+ * @uuid: where to put the generated UUID
+ *
+ * Random UUID interface
+ *
+ * Used to create a Boot ID or a filesystem UUID/GUID, but can be
+ * useful for other kernel drivers.
+ */
+void generate_random_uuid(unsigned char uuid[16])
+{
+	get_random_bytes(uuid, 16);
+	/* Set UUID version to 4 --- truly random generation */
+	uuid[6] = (uuid[6] & 0x0F) | 0x40;
+	/* Set the UUID variant to DCE */
+	uuid[8] = (uuid[8] & 0x3F) | 0x80;
+}
+EXPORT_SYMBOL(generate_random_uuid);
+
+void generate_random_guid(unsigned char guid[16])
+{
+	get_random_bytes(guid, 16);
+	/* Set GUID version to 4 --- truly random generation */
+	guid[7] = (guid[7] & 0x0F) | 0x40;
+	/* Set the GUID variant to DCE */
+	guid[8] = (guid[8] & 0x3F) | 0x80;
+}
+EXPORT_SYMBOL(generate_random_guid);
+
+static void __uuid_gen_common(__u8 b[16])
+{
+	get_random_bytes(b, 16);
+	/* revision 0b10 */
+	b[8] = (b[8] & 0x3F) | 0x80;
+}
+
+void guid_gen(guid_t *lu)
+{
+	__uuid_gen_common(lu->b);
+	/* version 4 : random generation */
+	lu->b[7] = (lu->b[7] & 0x0F) | 0x40;
+}
+EXPORT_SYMBOL_GPL(guid_gen);
+
+void uuid_gen(uuid_t *bu)
+{
+	__uuid_gen_common(bu->b);
+	/* version 4 : random generation */
+	bu->b[6] = (bu->b[6] & 0x0F) | 0x40;
+}
+EXPORT_SYMBOL_GPL(uuid_gen);
+
+/**
+ * uuid_is_valid - checks if a UUID string is valid
+ * @uuid:	UUID string to check
+ *
+ * Description:
+ * It checks if the UUID string is following the format:
+ *	xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
+ *
+ * where x is a hex digit.
+ *
+ * Return: true if input is valid UUID string.
+ */
+bool uuid_is_valid(const char *uuid)
+{
+	unsigned int i;
+
+	for (i = 0; i < UUID_STRING_LEN; i++) {
+		if (i == 8 || i == 13 || i == 18 || i == 23) {
+			if (uuid[i] != '-')
+				return false;
+		} else if (!isxdigit(uuid[i])) {
+			return false;
+		}
+	}
+
+	return true;
+}
+EXPORT_SYMBOL(uuid_is_valid);
+
+static int __uuid_parse(const char *uuid, __u8 b[16], const u8 ei[16])
+{
+	static const u8 si[16] = {0,2,4,6,9,11,14,16,19,21,24,26,28,30,32,34};
+	unsigned int i;
+
+	if (!uuid_is_valid(uuid))
+		return -EINVAL;
+
+	for (i = 0; i < 16; i++) {
+		int hi = hex_to_bin(uuid[si[i] + 0]);
+		int lo = hex_to_bin(uuid[si[i] + 1]);
+
+		b[ei[i]] = (hi << 4) | lo;
+	}
+
+	return 0;
+}
+
+int guid_parse(const char *uuid, guid_t *u)
+{
+	return __uuid_parse(uuid, u->b, guid_index);
+}
+EXPORT_SYMBOL(guid_parse);
+
+int uuid_parse(const char *uuid, uuid_t *u)
+{
+	return __uuid_parse(uuid, u->b, uuid_index);
+}
+EXPORT_SYMBOL(uuid_parse);