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, 205 insertions, 0 deletions

diff --git a/drivers/macintosh/ans-lcd.c b/drivers/macintosh/ans-lcd.c
new file mode 100644
index 000000000..fa904b24a
--- /dev/null
+++ b/drivers/macintosh/ans-lcd.c
@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * /dev/lcd driver for Apple Network Servers.
+ */
+
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/fcntl.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/fs.h>
+#include <linux/of.h>
+
+#include <linux/uaccess.h>
+#include <asm/sections.h>
+#include <asm/io.h>
+
+#include "ans-lcd.h"
+
+#define ANSLCD_ADDR		0xf301c000
+#define ANSLCD_CTRL_IX 0x00
+#define ANSLCD_DATA_IX 0x10
+
+static unsigned long anslcd_short_delay = 80;
+static unsigned long anslcd_long_delay = 3280;
+static volatile unsigned char __iomem *anslcd_ptr;
+static DEFINE_MUTEX(anslcd_mutex);
+
+#undef DEBUG
+
+static void
+anslcd_write_byte_ctrl ( unsigned char c )
+{
+#ifdef DEBUG
+	printk(KERN_DEBUG "LCD: CTRL byte: %02x\n",c);
+#endif
+	out_8(anslcd_ptr + ANSLCD_CTRL_IX, c);
+	switch(c) {
+		case 1:
+		case 2:
+		case 3:
+			udelay(anslcd_long_delay); break;
+		default: udelay(anslcd_short_delay);
+	}
+}
+
+static void
+anslcd_write_byte_data ( unsigned char c )
+{
+	out_8(anslcd_ptr + ANSLCD_DATA_IX, c);
+	udelay(anslcd_short_delay);
+}
+
+static ssize_t
+anslcd_write( struct file * file, const char __user * buf, 
+				size_t count, loff_t *ppos )
+{
+	const char __user *p = buf;
+	int i;
+
+#ifdef DEBUG
+	printk(KERN_DEBUG "LCD: write\n");
+#endif
+
+	if (!access_ok(buf, count))
+		return -EFAULT;
+
+	mutex_lock(&anslcd_mutex);
+	for ( i = *ppos; count > 0; ++i, ++p, --count ) 
+	{
+		char c;
+		__get_user(c, p);
+		anslcd_write_byte_data( c );
+	}
+	mutex_unlock(&anslcd_mutex);
+	*ppos = i;
+	return p - buf;
+}
+
+static long
+anslcd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	char ch, __user *temp;
+	long ret = 0;
+
+#ifdef DEBUG
+	printk(KERN_DEBUG "LCD: ioctl(%d,%d)\n",cmd,arg);
+#endif
+
+	mutex_lock(&anslcd_mutex);
+
+	switch ( cmd )
+	{
+	case ANSLCD_CLEAR:
+		anslcd_write_byte_ctrl ( 0x38 );
+		anslcd_write_byte_ctrl ( 0x0f );
+		anslcd_write_byte_ctrl ( 0x06 );
+		anslcd_write_byte_ctrl ( 0x01 );
+		anslcd_write_byte_ctrl ( 0x02 );
+		break;
+	case ANSLCD_SENDCTRL:
+		temp = (char __user *) arg;
+		__get_user(ch, temp);
+		for (; ch; temp++) { /* FIXME: This is ugly, but should work, as a \0 byte is not a valid command code */
+			anslcd_write_byte_ctrl ( ch );
+			__get_user(ch, temp);
+		}
+		break;
+	case ANSLCD_SETSHORTDELAY:
+		if (!capable(CAP_SYS_ADMIN))
+			ret =-EACCES;
+		else
+			anslcd_short_delay=arg;
+		break;
+	case ANSLCD_SETLONGDELAY:
+		if (!capable(CAP_SYS_ADMIN))
+			ret = -EACCES;
+		else
+			anslcd_long_delay=arg;
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	mutex_unlock(&anslcd_mutex);
+	return ret;
+}
+
+static int
+anslcd_open( struct inode * inode, struct file * file )
+{
+	return 0;
+}
+
+const struct file_operations anslcd_fops = {
+	.write		= anslcd_write,
+	.unlocked_ioctl	= anslcd_ioctl,
+	.open		= anslcd_open,
+	.llseek		= default_llseek,
+};
+
+static struct miscdevice anslcd_dev = {
+	LCD_MINOR,
+	"anslcd",
+	&anslcd_fops
+};
+
+static const char anslcd_logo[] __initconst =
+				"********************"  /* Line #1 */
+				"*      LINUX!      *"  /* Line #3 */
+				"*    Welcome to    *"  /* Line #2 */
+				"********************"; /* Line #4 */
+
+static int __init
+anslcd_init(void)
+{
+	int a;
+	int retval;
+	struct device_node* node;
+
+	node = of_find_node_by_name(NULL, "lcd");
+	if (!node || !of_node_name_eq(node->parent, "gc")) {
+		of_node_put(node);
+		return -ENODEV;
+	}
+	of_node_put(node);
+
+	anslcd_ptr = ioremap(ANSLCD_ADDR, 0x20);
+	
+	retval = misc_register(&anslcd_dev);
+	if(retval < 0){
+		printk(KERN_INFO "LCD: misc_register failed\n");
+		iounmap(anslcd_ptr);
+		return retval;
+	}
+
+#ifdef DEBUG
+	printk(KERN_DEBUG "LCD: init\n");
+#endif
+
+	mutex_lock(&anslcd_mutex);
+	anslcd_write_byte_ctrl ( 0x38 );
+	anslcd_write_byte_ctrl ( 0x0c );
+	anslcd_write_byte_ctrl ( 0x06 );
+	anslcd_write_byte_ctrl ( 0x01 );
+	anslcd_write_byte_ctrl ( 0x02 );
+	for(a=0;a<80;a++) {
+		anslcd_write_byte_data(anslcd_logo[a]);
+	}
+	mutex_unlock(&anslcd_mutex);
+	return 0;
+}
+
+static void __exit
+anslcd_exit(void)
+{
+	misc_deregister(&anslcd_dev);
+	iounmap(anslcd_ptr);
+}
+
+module_init(anslcd_init);
+module_exit(anslcd_exit);
+MODULE_LICENSE("GPL v2");