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, 204 insertions, 0 deletions

diff --git a/drivers/input/serio/maceps2.c b/drivers/input/serio/maceps2.c
new file mode 100644
index 000000000..fb41e7f5a
--- /dev/null
+++ b/drivers/input/serio/maceps2.c
@@ -0,0 +1,204 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SGI O2 MACE PS2 controller driver for linux
+ *
+ * Copyright (C) 2002 Vivien Chappelier
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/serio.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/err.h>
+
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/ip32/mace.h>
+#include <asm/ip32/ip32_ints.h>
+
+MODULE_AUTHOR("Vivien Chappelier <vivien.chappelier@linux-mips.org");
+MODULE_DESCRIPTION("SGI O2 MACE PS2 controller driver");
+MODULE_LICENSE("GPL");
+
+#define MACE_PS2_TIMEOUT 10000 /* in 50us unit */
+
+#define PS2_STATUS_CLOCK_SIGNAL  BIT(0) /* external clock signal */
+#define PS2_STATUS_CLOCK_INHIBIT BIT(1) /* clken output signal */
+#define PS2_STATUS_TX_INPROGRESS BIT(2) /* transmission in progress */
+#define PS2_STATUS_TX_EMPTY      BIT(3) /* empty transmit buffer */
+#define PS2_STATUS_RX_FULL       BIT(4) /* full receive buffer */
+#define PS2_STATUS_RX_INPROGRESS BIT(5) /* reception in progress */
+#define PS2_STATUS_ERROR_PARITY  BIT(6) /* parity error */
+#define PS2_STATUS_ERROR_FRAMING BIT(7) /* framing error */
+
+#define PS2_CONTROL_TX_CLOCK_DISABLE BIT(0) /* inhibit clock signal after TX */
+#define PS2_CONTROL_TX_ENABLE        BIT(1) /* transmit enable */
+#define PS2_CONTROL_TX_INT_ENABLE    BIT(2) /* enable transmit interrupt */
+#define PS2_CONTROL_RX_INT_ENABLE    BIT(3) /* enable receive interrupt */
+#define PS2_CONTROL_RX_CLOCK_ENABLE  BIT(4) /* pause reception if set to 0 */
+#define PS2_CONTROL_RESET            BIT(5) /* reset */
+
+struct maceps2_data {
+	struct mace_ps2port *port;
+	int irq;
+};
+
+static struct maceps2_data port_data[2];
+static struct serio *maceps2_port[2];
+static struct platform_device *maceps2_device;
+
+static int maceps2_write(struct serio *dev, unsigned char val)
+{
+	struct mace_ps2port *port = ((struct maceps2_data *)dev->port_data)->port;
+	unsigned int timeout = MACE_PS2_TIMEOUT;
+
+	do {
+		if (port->status & PS2_STATUS_TX_EMPTY) {
+			port->tx = val;
+			return 0;
+		}
+		udelay(50);
+	} while (timeout--);
+
+	return -1;
+}
+
+static irqreturn_t maceps2_interrupt(int irq, void *dev_id)
+{
+	struct serio *dev = dev_id;
+	struct mace_ps2port *port = ((struct maceps2_data *)dev->port_data)->port;
+	unsigned long byte;
+
+	if (port->status & PS2_STATUS_RX_FULL) {
+		byte = port->rx;
+		serio_interrupt(dev, byte & 0xff, 0);
+        }
+
+	return IRQ_HANDLED;
+}
+
+static int maceps2_open(struct serio *dev)
+{
+	struct maceps2_data *data = (struct maceps2_data *)dev->port_data;
+
+	if (request_irq(data->irq, maceps2_interrupt, 0, "PS2 port", dev)) {
+		printk(KERN_ERR "Could not allocate PS/2 IRQ\n");
+		return -EBUSY;
+	}
+
+	/* Reset port */
+	data->port->control = PS2_CONTROL_TX_CLOCK_DISABLE | PS2_CONTROL_RESET;
+	udelay(100);
+
+        /* Enable interrupts */
+	data->port->control = PS2_CONTROL_RX_CLOCK_ENABLE |
+			      PS2_CONTROL_TX_ENABLE |
+			      PS2_CONTROL_RX_INT_ENABLE;
+
+	return 0;
+}
+
+static void maceps2_close(struct serio *dev)
+{
+	struct maceps2_data *data = (struct maceps2_data *)dev->port_data;
+
+	data->port->control = PS2_CONTROL_TX_CLOCK_DISABLE | PS2_CONTROL_RESET;
+	udelay(100);
+	free_irq(data->irq, dev);
+}
+
+
+static struct serio *maceps2_allocate_port(int idx)
+{
+	struct serio *serio;
+
+	serio = kzalloc_obj(*serio);
+	if (serio) {
+		serio->id.type		= SERIO_8042;
+		serio->write		= maceps2_write;
+		serio->open		= maceps2_open;
+		serio->close		= maceps2_close;
+		snprintf(serio->name, sizeof(serio->name), "MACE PS/2 port%d", idx);
+		snprintf(serio->phys, sizeof(serio->phys), "mace/serio%d", idx);
+		serio->port_data	= &port_data[idx];
+		serio->dev.parent	= &maceps2_device->dev;
+	}
+
+	return serio;
+}
+
+static int maceps2_probe(struct platform_device *dev)
+{
+	maceps2_port[0] = maceps2_allocate_port(0);
+	maceps2_port[1] = maceps2_allocate_port(1);
+	if (!maceps2_port[0] || !maceps2_port[1]) {
+		kfree(maceps2_port[0]);
+		kfree(maceps2_port[1]);
+		return -ENOMEM;
+	}
+
+	serio_register_port(maceps2_port[0]);
+	serio_register_port(maceps2_port[1]);
+
+	return 0;
+}
+
+static void maceps2_remove(struct platform_device *dev)
+{
+	serio_unregister_port(maceps2_port[0]);
+	serio_unregister_port(maceps2_port[1]);
+}
+
+static struct platform_driver maceps2_driver = {
+	.driver		= {
+		.name	= "maceps2",
+	},
+	.probe		= maceps2_probe,
+	.remove		= maceps2_remove,
+};
+
+static int __init maceps2_init(void)
+{
+	int error;
+
+	error = platform_driver_register(&maceps2_driver);
+	if (error)
+		return error;
+
+	maceps2_device = platform_device_alloc("maceps2", -1);
+	if (!maceps2_device) {
+		error = -ENOMEM;
+		goto err_unregister_driver;
+	}
+
+	port_data[0].port = &mace->perif.ps2.keyb;
+	port_data[0].irq  = MACEISA_KEYB_IRQ;
+	port_data[1].port = &mace->perif.ps2.mouse;
+	port_data[1].irq  = MACEISA_MOUSE_IRQ;
+
+	error = platform_device_add(maceps2_device);
+	if (error)
+		goto err_free_device;
+
+	return 0;
+
+ err_free_device:
+	platform_device_put(maceps2_device);
+ err_unregister_driver:
+	platform_driver_unregister(&maceps2_driver);
+	return error;
+}
+
+static void __exit maceps2_exit(void)
+{
+	platform_device_unregister(maceps2_device);
+	platform_driver_unregister(&maceps2_driver);
+}
+
+module_init(maceps2_init);
+module_exit(maceps2_exit);