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, 47 insertions, 0 deletions

diff --git a/arch/microblaze/lib/mulsi3.S b/arch/microblaze/lib/mulsi3.S
new file mode 100644
index 000000000..d6703a4d9
--- /dev/null
+++ b/arch/microblaze/lib/mulsi3.S
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/linkage.h>
+
+/*
+ * Multiply operation for 32 bit integers.
+ *	Input :	Operand1 in Reg r5
+ *		Operand2 in Reg r6
+ *	Output: Result [op1 * op2] in Reg r3
+ */
+	.text
+	.globl	__mulsi3
+	.type __mulsi3,  @function
+	.ent __mulsi3
+
+__mulsi3:
+	.frame	r1, 0, r15
+	add	r3, r0, r0
+	beqi	r5, result_is_zero /* multiply by zero */
+	beqi	r6, result_is_zero /* multiply by zero */
+	bgeid	r5, r5_pos
+	xor	r4, r5, r6 /* get the sign of the result */
+	rsubi	r5, r5, 0 /* make r5 positive */
+r5_pos:
+	bgei	r6, r6_pos
+	rsubi	r6, r6, 0 /* make r6 positive */
+r6_pos:
+	bri	l1
+l2:
+	add	r5, r5, r5
+l1:
+	srl	r6, r6
+	addc	r7, r0, r0
+	beqi	r7, l2
+	bneid	r6, l2
+	add	r3, r3, r5
+	blti	r4, negateresult
+	rtsd	r15, 8
+	nop
+negateresult:
+	rtsd	r15, 8
+	rsub	r3, r3, r0
+result_is_zero:
+	rtsd	r15, 8
+	addi	r3, r0, 0
+
+.size __mulsi3,  . - __mulsi3
+.end __mulsi3