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, 243 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/htcpen.c b/drivers/input/touchscreen/htcpen.c
new file mode 100644
index 000000000..056ba7608
--- /dev/null
+++ b/drivers/input/touchscreen/htcpen.c
@@ -0,0 +1,243 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * HTC Shift touchscreen driver
+ *
+ * Copyright (C) 2008 Pau Oliva Fora <pof@eslack.org>
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/isa.h>
+#include <linux/ioport.h>
+#include <linux/dmi.h>
+
+MODULE_AUTHOR("Pau Oliva Fora <pau@eslack.org>");
+MODULE_DESCRIPTION("HTC Shift touchscreen driver");
+MODULE_LICENSE("GPL");
+
+#define HTCPEN_PORT_IRQ_CLEAR	0x068
+#define HTCPEN_PORT_INIT	0x06c
+#define HTCPEN_PORT_INDEX	0x0250
+#define HTCPEN_PORT_DATA	0x0251
+#define HTCPEN_IRQ		3
+
+#define DEVICE_ENABLE		0xa2
+#define DEVICE_DISABLE		0xa3
+
+#define X_INDEX			3
+#define Y_INDEX			5
+#define TOUCH_INDEX		0xb
+#define LSB_XY_INDEX		0xc
+#define X_AXIS_MAX		2040
+#define Y_AXIS_MAX		2040
+
+static bool invert_x;
+module_param(invert_x, bool, 0644);
+MODULE_PARM_DESC(invert_x, "If set, X axis is inverted");
+static bool invert_y;
+module_param(invert_y, bool, 0644);
+MODULE_PARM_DESC(invert_y, "If set, Y axis is inverted");
+
+static irqreturn_t htcpen_interrupt(int irq, void *handle)
+{
+	struct input_dev *htcpen_dev = handle;
+	unsigned short x, y, xy;
+
+	/* 0 = press; 1 = release */
+	outb_p(TOUCH_INDEX, HTCPEN_PORT_INDEX);
+
+	if (inb_p(HTCPEN_PORT_DATA)) {
+		input_report_key(htcpen_dev, BTN_TOUCH, 0);
+	} else {
+		outb_p(X_INDEX, HTCPEN_PORT_INDEX);
+		x = inb_p(HTCPEN_PORT_DATA);
+
+		outb_p(Y_INDEX, HTCPEN_PORT_INDEX);
+		y = inb_p(HTCPEN_PORT_DATA);
+
+		outb_p(LSB_XY_INDEX, HTCPEN_PORT_INDEX);
+		xy = inb_p(HTCPEN_PORT_DATA);
+
+		/* get high resolution value of X and Y using LSB */
+		x = X_AXIS_MAX - ((x * 8) + ((xy >> 4) & 0xf));
+		y = (y * 8) + (xy & 0xf);
+		if (invert_x)
+			x = X_AXIS_MAX - x;
+		if (invert_y)
+			y = Y_AXIS_MAX - y;
+
+		if (x != X_AXIS_MAX && x != 0) {
+			input_report_key(htcpen_dev, BTN_TOUCH, 1);
+			input_report_abs(htcpen_dev, ABS_X, x);
+			input_report_abs(htcpen_dev, ABS_Y, y);
+		}
+	}
+
+	input_sync(htcpen_dev);
+
+	inb_p(HTCPEN_PORT_IRQ_CLEAR);
+
+	return IRQ_HANDLED;
+}
+
+static int htcpen_open(struct input_dev *dev)
+{
+	outb_p(DEVICE_ENABLE, HTCPEN_PORT_INIT);
+
+	return 0;
+}
+
+static void htcpen_close(struct input_dev *dev)
+{
+	outb_p(DEVICE_DISABLE, HTCPEN_PORT_INIT);
+	synchronize_irq(HTCPEN_IRQ);
+}
+
+static int htcpen_isa_probe(struct device *dev, unsigned int id)
+{
+	struct input_dev *htcpen_dev;
+	int err = -EBUSY;
+
+	if (!request_region(HTCPEN_PORT_IRQ_CLEAR, 1, "htcpen")) {
+		printk(KERN_ERR "htcpen: unable to get IO region 0x%x\n",
+			HTCPEN_PORT_IRQ_CLEAR);
+		goto request_region1_failed;
+	}
+
+	if (!request_region(HTCPEN_PORT_INIT, 1, "htcpen")) {
+		printk(KERN_ERR "htcpen: unable to get IO region 0x%x\n",
+			HTCPEN_PORT_INIT);
+		goto request_region2_failed;
+	}
+
+	if (!request_region(HTCPEN_PORT_INDEX, 2, "htcpen")) {
+		printk(KERN_ERR "htcpen: unable to get IO region 0x%x\n",
+			HTCPEN_PORT_INDEX);
+		goto request_region3_failed;
+	}
+
+	htcpen_dev = input_allocate_device();
+	if (!htcpen_dev) {
+		printk(KERN_ERR "htcpen: can't allocate device\n");
+		err = -ENOMEM;
+		goto input_alloc_failed;
+	}
+
+	htcpen_dev->name = "HTC Shift EC TouchScreen";
+	htcpen_dev->id.bustype = BUS_ISA;
+
+	htcpen_dev->evbit[0] = BIT_MASK(EV_ABS) | BIT_MASK(EV_KEY);
+	htcpen_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
+	input_set_abs_params(htcpen_dev, ABS_X, 0, X_AXIS_MAX, 0, 0);
+	input_set_abs_params(htcpen_dev, ABS_Y, 0, Y_AXIS_MAX, 0, 0);
+
+	htcpen_dev->open = htcpen_open;
+	htcpen_dev->close = htcpen_close;
+
+	err = request_irq(HTCPEN_IRQ, htcpen_interrupt, 0, "htcpen",
+			htcpen_dev);
+	if (err) {
+		printk(KERN_ERR "htcpen: irq busy\n");
+		goto request_irq_failed;
+	}
+
+	inb_p(HTCPEN_PORT_IRQ_CLEAR);
+
+	err = input_register_device(htcpen_dev);
+	if (err)
+		goto input_register_failed;
+
+	dev_set_drvdata(dev, htcpen_dev);
+
+	return 0;
+
+ input_register_failed:
+	free_irq(HTCPEN_IRQ, htcpen_dev);
+ request_irq_failed:
+	input_free_device(htcpen_dev);
+ input_alloc_failed:
+	release_region(HTCPEN_PORT_INDEX, 2);
+ request_region3_failed:
+	release_region(HTCPEN_PORT_INIT, 1);
+ request_region2_failed:
+	release_region(HTCPEN_PORT_IRQ_CLEAR, 1);
+ request_region1_failed:
+	return err;
+}
+
+static void htcpen_isa_remove(struct device *dev, unsigned int id)
+{
+	struct input_dev *htcpen_dev = dev_get_drvdata(dev);
+
+	input_unregister_device(htcpen_dev);
+
+	free_irq(HTCPEN_IRQ, htcpen_dev);
+
+	release_region(HTCPEN_PORT_INDEX, 2);
+	release_region(HTCPEN_PORT_INIT, 1);
+	release_region(HTCPEN_PORT_IRQ_CLEAR, 1);
+}
+
+#ifdef CONFIG_PM
+static int htcpen_isa_suspend(struct device *dev, unsigned int n,
+				pm_message_t state)
+{
+	outb_p(DEVICE_DISABLE, HTCPEN_PORT_INIT);
+
+	return 0;
+}
+
+static int htcpen_isa_resume(struct device *dev, unsigned int n)
+{
+	outb_p(DEVICE_ENABLE, HTCPEN_PORT_INIT);
+
+	return 0;
+}
+#endif
+
+static struct isa_driver htcpen_isa_driver = {
+	.probe		= htcpen_isa_probe,
+	.remove		= htcpen_isa_remove,
+#ifdef CONFIG_PM
+	.suspend	= htcpen_isa_suspend,
+	.resume		= htcpen_isa_resume,
+#endif
+	.driver = {
+		.owner	= THIS_MODULE,
+		.name	= "htcpen",
+	}
+};
+
+static const struct dmi_system_id htcshift_dmi_table[] __initconst = {
+	{
+		.ident = "Shift",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "High Tech Computer Corp"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Shift"),
+		},
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(dmi, htcshift_dmi_table);
+
+static int __init htcpen_isa_init(void)
+{
+	if (!dmi_check_system(htcshift_dmi_table))
+		return -ENODEV;
+
+	return isa_register_driver(&htcpen_isa_driver, 1);
+}
+
+static void __exit htcpen_isa_exit(void)
+{
+	isa_unregister_driver(&htcpen_isa_driver);
+}
+
+module_init(htcpen_isa_init);
+module_exit(htcpen_isa_exit);