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, 103 insertions, 0 deletions

diff --git a/arch/m68k/sun3x/time.c b/arch/m68k/sun3x/time.c
new file mode 100644
index 000000000..a2c97821f
--- /dev/null
+++ b/arch/m68k/sun3x/time.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/arch/m68k/sun3x/time.c
+ *
+ *  Sun3x-specific time handling
+ */
+
+#include <linux/types.h>
+#include <linux/kd.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/kernel_stat.h>
+#include <linux/interrupt.h>
+#include <linux/rtc.h>
+#include <linux/bcd.h>
+
+#include <asm/irq.h>
+#include <asm/io.h>
+#include <asm/machdep.h>
+#include <asm/traps.h>
+#include <asm/sun3x.h>
+#include <asm/sun3ints.h>
+
+#include "time.h"
+
+#define M_CONTROL 0xf8
+#define M_SEC     0xf9
+#define M_MIN     0xfa
+#define M_HOUR    0xfb
+#define M_DAY     0xfc
+#define M_DATE    0xfd
+#define M_MONTH   0xfe
+#define M_YEAR    0xff
+
+#define C_WRITE   0x80
+#define C_READ    0x40
+#define C_SIGN    0x20
+#define C_CALIB   0x1f
+
+int sun3x_hwclk(int set, struct rtc_time *t)
+{
+	volatile struct mostek_dt *h =
+		(struct mostek_dt *)(SUN3X_EEPROM+M_CONTROL);
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	if(set) {
+		h->csr |= C_WRITE;
+		h->sec = bin2bcd(t->tm_sec);
+		h->min = bin2bcd(t->tm_min);
+		h->hour = bin2bcd(t->tm_hour);
+		h->wday = bin2bcd(t->tm_wday);
+		h->mday = bin2bcd(t->tm_mday);
+		h->month = bin2bcd(t->tm_mon + 1);
+		h->year = bin2bcd(t->tm_year % 100);
+		h->csr &= ~C_WRITE;
+	} else {
+		h->csr |= C_READ;
+		t->tm_sec = bcd2bin(h->sec);
+		t->tm_min = bcd2bin(h->min);
+		t->tm_hour = bcd2bin(h->hour);
+		t->tm_wday = bcd2bin(h->wday);
+		t->tm_mday = bcd2bin(h->mday);
+		t->tm_mon = bcd2bin(h->month) - 1;
+		t->tm_year = bcd2bin(h->year);
+		h->csr &= ~C_READ;
+		if (t->tm_year < 70)
+			t->tm_year += 100;
+	}
+
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+#if 0
+static irqreturn_t sun3x_timer_tick(int irq, void *dev_id)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	/* Clear the pending interrupt - pulse the enable line low */
+	disable_irq(5);
+	enable_irq(5);
+	legacy_timer_tick(1);
+	local_irq_restore(flags);
+
+	return IRQ_HANDLED;
+}
+#endif
+
+void __init sun3x_sched_init(void)
+{
+
+	sun3_disable_interrupts();
+
+
+    /* Pulse enable low to get the clock started */
+	sun3_disable_irq(5);
+	sun3_enable_irq(5);
+	sun3_enable_interrupts();
+}