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, 48 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-s3c.h b/drivers/rtc/rtc-s3c.h
new file mode 100644
index 000000000..11d7a1255
--- /dev/null
+++ b/drivers/rtc/rtc-s3c.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2003 Simtec Electronics <linux@simtec.co.uk>
+ *		      http://www.simtec.co.uk/products/SWLINUX/
+ *
+ * S3C2410 Internal RTC register definition
+*/
+
+#ifndef __ASM_ARCH_REGS_RTC_H
+#define __ASM_ARCH_REGS_RTC_H __FILE__
+
+#define S3C2410_RTCREG(x) (x)
+#define S3C2410_INTP		S3C2410_RTCREG(0x30)
+#define S3C2410_INTP_ALM	(1 << 1)
+#define S3C2410_INTP_TIC	(1 << 0)
+
+#define S3C2410_RTCCON		S3C2410_RTCREG(0x40)
+#define S3C2410_RTCCON_RTCEN	(1 << 0)
+#define S3C2410_RTCCON_CNTSEL	(1 << 2)
+#define S3C2410_RTCCON_CLKRST	(1 << 3)
+#define S3C2443_RTCCON_TICSEL	(1 << 4)
+#define S3C64XX_RTCCON_TICEN	(1 << 8)
+
+#define S3C2410_RTCALM		S3C2410_RTCREG(0x50)
+#define S3C2410_RTCALM_ALMEN	(1 << 6)
+#define S3C2410_RTCALM_YEAREN	(1 << 5)
+#define S3C2410_RTCALM_MONEN	(1 << 4)
+#define S3C2410_RTCALM_DAYEN	(1 << 3)
+#define S3C2410_RTCALM_HOUREN	(1 << 2)
+#define S3C2410_RTCALM_MINEN	(1 << 1)
+#define S3C2410_RTCALM_SECEN	(1 << 0)
+
+#define S3C2410_ALMSEC		S3C2410_RTCREG(0x54)
+#define S3C2410_ALMMIN		S3C2410_RTCREG(0x58)
+#define S3C2410_ALMHOUR		S3C2410_RTCREG(0x5c)
+
+#define S3C2410_ALMDATE		S3C2410_RTCREG(0x60)
+#define S3C2410_ALMMON		S3C2410_RTCREG(0x64)
+#define S3C2410_ALMYEAR		S3C2410_RTCREG(0x68)
+
+#define S3C2410_RTCSEC		S3C2410_RTCREG(0x70)
+#define S3C2410_RTCMIN		S3C2410_RTCREG(0x74)
+#define S3C2410_RTCHOUR		S3C2410_RTCREG(0x78)
+#define S3C2410_RTCDATE		S3C2410_RTCREG(0x7c)
+#define S3C2410_RTCMON		S3C2410_RTCREG(0x84)
+#define S3C2410_RTCYEAR		S3C2410_RTCREG(0x88)
+
+#endif /* __ASM_ARCH_REGS_RTC_H */