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, 142 insertions, 0 deletions

diff --git a/arch/m68k/lib/uaccess.c b/arch/m68k/lib/uaccess.c
new file mode 100644
index 000000000..7646e461a
--- /dev/null
+++ b/arch/m68k/lib/uaccess.c
@@ -0,0 +1,142 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file COPYING in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/uaccess.h>
+
+unsigned long __generic_copy_from_user(void *to, const void __user *from,
+				       unsigned long n)
+{
+	unsigned long tmp, res;
+
+	asm volatile ("\n"
+		"	tst.l	%0\n"
+		"	jeq	2f\n"
+		"1:	"MOVES".l	(%1)+,%3\n"
+		"	move.l	%3,(%2)+\n"
+		"	subq.l	#1,%0\n"
+		"	jne	1b\n"
+		"2:	btst	#1,%5\n"
+		"	jeq	4f\n"
+		"3:	"MOVES".w	(%1)+,%3\n"
+		"	move.w	%3,(%2)+\n"
+		"4:	btst	#0,%5\n"
+		"	jeq	6f\n"
+		"5:	"MOVES".b	(%1)+,%3\n"
+		"	move.b  %3,(%2)+\n"
+		"6:\n"
+		"	.section .fixup,\"ax\"\n"
+		"	.even\n"
+		"10:	lsl.l	#2,%0\n"
+		"	btst	#1,%5\n"
+		"	jeq	8f\n"
+		"30:	addq.l	#2,%0\n"
+		"8:	btst	#0,%5\n"
+		"	jeq	6b\n"
+		"50:	addq.l	#1,%0\n"
+		"	jra	6b\n"
+		"	.previous\n"
+		"\n"
+		"	.section __ex_table,\"a\"\n"
+		"	.align	4\n"
+		"	.long	1b,10b\n"
+		"	.long	3b,30b\n"
+		"	.long	5b,50b\n"
+		"	.previous"
+		: "=d" (res), "+a" (from), "+a" (to), "=&d" (tmp)
+		: "0" (n / 4), "d" (n & 3));
+
+	return res;
+}
+EXPORT_SYMBOL(__generic_copy_from_user);
+
+unsigned long __generic_copy_to_user(void __user *to, const void *from,
+				     unsigned long n)
+{
+	unsigned long tmp, res;
+
+	asm volatile ("\n"
+		"	tst.l	%0\n"
+		"	jeq	4f\n"
+		"1:	move.l	(%1)+,%3\n"
+		"2:	"MOVES".l	%3,(%2)+\n"
+		"3:	subq.l	#1,%0\n"
+		"	jne	1b\n"
+		"4:	btst	#1,%5\n"
+		"	jeq	6f\n"
+		"	move.w	(%1)+,%3\n"
+		"5:	"MOVES".w	%3,(%2)+\n"
+		"6:	btst	#0,%5\n"
+		"	jeq	8f\n"
+		"	move.b	(%1)+,%3\n"
+		"7:	"MOVES".b  %3,(%2)+\n"
+		"8:\n"
+		"	.section .fixup,\"ax\"\n"
+		"	.even\n"
+		"20:	lsl.l	#2,%0\n"
+		"50:	add.l	%5,%0\n"
+		"	jra	8b\n"
+		"	.previous\n"
+		"\n"
+		"	.section __ex_table,\"a\"\n"
+		"	.align	4\n"
+		"	.long	2b,20b\n"
+		"	.long	3b,20b\n"
+		"	.long	5b,50b\n"
+		"	.long	6b,50b\n"
+		"	.long	7b,50b\n"
+		"	.long	8b,50b\n"
+		"	.previous"
+		: "=d" (res), "+a" (from), "+a" (to), "=&d" (tmp)
+		: "0" (n / 4), "d" (n & 3));
+
+	return res;
+}
+EXPORT_SYMBOL(__generic_copy_to_user);
+
+/*
+ * Zero Userspace
+ */
+
+unsigned long __clear_user(void __user *to, unsigned long n)
+{
+	unsigned long res;
+
+	asm volatile ("\n"
+		"	tst.l	%0\n"
+		"	jeq	3f\n"
+		"1:	"MOVES".l	%2,(%1)+\n"
+		"2:	subq.l	#1,%0\n"
+		"	jne	1b\n"
+		"3:	btst	#1,%4\n"
+		"	jeq	5f\n"
+		"4:	"MOVES".w	%2,(%1)+\n"
+		"5:	btst	#0,%4\n"
+		"	jeq	7f\n"
+		"6:	"MOVES".b	%2,(%1)\n"
+		"7:\n"
+		"	.section .fixup,\"ax\"\n"
+		"	.even\n"
+		"10:	lsl.l	#2,%0\n"
+		"40:	add.l	%4,%0\n"
+		"	jra	7b\n"
+		"	.previous\n"
+		"\n"
+		"	.section __ex_table,\"a\"\n"
+		"	.align	4\n"
+		"	.long	1b,10b\n"
+		"	.long	2b,10b\n"
+		"	.long	4b,40b\n"
+		"	.long	5b,40b\n"
+		"	.long	6b,40b\n"
+		"	.long	7b,40b\n"
+		"	.previous"
+		: "=d" (res), "+a" (to)
+		: "d" (0), "0" (n / 4), "d" (n & 3));
+
+    return res;
+}
+EXPORT_SYMBOL(__clear_user);