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, 340 insertions, 0 deletions

diff --git a/drivers/input/keyboard/locomokbd.c b/drivers/input/keyboard/locomokbd.c
new file mode 100644
index 000000000..6351562eb
--- /dev/null
+++ b/drivers/input/keyboard/locomokbd.c
@@ -0,0 +1,340 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * LoCoMo keyboard driver for Linux-based ARM PDAs:
+ * 	- SHARP Zaurus Collie (SL-5500)
+ * 	- SHARP Zaurus Poodle (SL-5600)
+ *
+ * Copyright (c) 2005 John Lenz
+ * Based on from xtkbd.c
+ */
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+
+#include <asm/hardware/locomo.h>
+#include <asm/irq.h>
+
+MODULE_AUTHOR("John Lenz <lenz@cs.wisc.edu>");
+MODULE_DESCRIPTION("LoCoMo keyboard driver");
+MODULE_LICENSE("GPL");
+
+#define LOCOMOKBD_NUMKEYS	128
+
+#define KEY_ACTIVITY		KEY_F16
+#define KEY_CONTACT		KEY_F18
+#define KEY_CENTER		KEY_F15
+
+static const unsigned char
+locomokbd_keycode[LOCOMOKBD_NUMKEYS] = {
+	0, KEY_ESC, KEY_ACTIVITY, 0, 0, 0, 0, 0, 0, 0,				/* 0 - 9 */
+	0, 0, 0, 0, 0, 0, 0, KEY_MENU, KEY_HOME, KEY_CONTACT,			/* 10 - 19 */
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0,						/* 20 - 29 */
+	0, 0, 0, KEY_CENTER, 0, KEY_MAIL, 0, 0, 0, 0,				/* 30 - 39 */
+	0, 0, 0, 0, 0, 0, 0, 0, 0, KEY_RIGHT,					/* 40 - 49 */
+	KEY_UP, KEY_LEFT, 0, 0, KEY_P, 0, KEY_O, KEY_I, KEY_Y, KEY_T,		/* 50 - 59 */
+	KEY_E, KEY_W, 0, 0, 0, 0, KEY_DOWN, KEY_ENTER, 0, 0,			/* 60 - 69 */
+	KEY_BACKSPACE, 0, KEY_L, KEY_U, KEY_H, KEY_R, KEY_D, KEY_Q, 0, 0,	/* 70 - 79 */
+	0, 0, 0, 0, 0, 0, KEY_ENTER, KEY_RIGHTSHIFT, KEY_K, KEY_J,		/* 80 - 89 */
+	KEY_G, KEY_F, KEY_X, KEY_S, 0, 0, 0, 0, 0, 0,				/* 90 - 99 */
+	0, 0, KEY_DOT, 0, KEY_COMMA, KEY_N, KEY_B, KEY_C, KEY_Z, KEY_A,		/* 100 - 109 */
+	KEY_LEFTSHIFT, KEY_TAB, KEY_LEFTCTRL, 0, 0, 0, 0, 0, 0, 0,		/* 110 - 119 */
+	KEY_M, KEY_SPACE, KEY_V, KEY_APOSTROPHE, KEY_SLASH, 0, 0, 0		/* 120 - 128 */
+};
+
+#define KB_ROWS			16
+#define KB_COLS			8
+#define KB_ROWMASK(r)		(1 << (r))
+#define SCANCODE(c,r)		( ((c)<<4) + (r) + 1 )
+
+#define KB_DELAY		8
+#define SCAN_INTERVAL		(HZ/10)
+
+struct locomokbd {
+	unsigned char keycode[LOCOMOKBD_NUMKEYS];
+	struct input_dev *input;
+	char phys[32];
+
+	unsigned long base;
+	spinlock_t lock;
+
+	struct timer_list timer;
+	unsigned long suspend_jiffies;
+	unsigned int count_cancel;
+};
+
+/* helper functions for reading the keyboard matrix */
+static inline void locomokbd_charge_all(unsigned long membase)
+{
+	locomo_writel(0x00FF, membase + LOCOMO_KSC);
+}
+
+static inline void locomokbd_activate_all(unsigned long membase)
+{
+	unsigned long r;
+
+	locomo_writel(0, membase + LOCOMO_KSC);
+	r = locomo_readl(membase + LOCOMO_KIC);
+	r &= 0xFEFF;
+	locomo_writel(r, membase + LOCOMO_KIC);
+}
+
+static inline void locomokbd_activate_col(unsigned long membase, int col)
+{
+	unsigned short nset;
+	unsigned short nbset;
+
+	nset = 0xFF & ~(1 << col);
+	nbset = (nset << 8) + nset;
+	locomo_writel(nbset, membase + LOCOMO_KSC);
+}
+
+static inline void locomokbd_reset_col(unsigned long membase, int col)
+{
+	unsigned short nbset;
+
+	nbset = ((0xFF & ~(1 << col)) << 8) + 0xFF;
+	locomo_writel(nbset, membase + LOCOMO_KSC);
+}
+
+/*
+ * The LoCoMo keyboard only generates interrupts when a key is pressed.
+ * So when a key is pressed, we enable a timer.  This timer scans the
+ * keyboard, and this is how we detect when the key is released.
+ */
+
+/* Scan the hardware keyboard and push any changes up through the input layer */
+static void locomokbd_scankeyboard(struct locomokbd *locomokbd)
+{
+	unsigned int row, col, rowd;
+	unsigned int num_pressed;
+	unsigned long membase = locomokbd->base;
+
+	guard(spinlock_irqsave)(&locomokbd->lock);
+
+	locomokbd_charge_all(membase);
+
+	num_pressed = 0;
+	for (col = 0; col < KB_COLS; col++) {
+
+		locomokbd_activate_col(membase, col);
+		udelay(KB_DELAY);
+
+		rowd = ~locomo_readl(membase + LOCOMO_KIB);
+		for (row = 0; row < KB_ROWS; row++) {
+			unsigned int scancode, pressed, key;
+
+			scancode = SCANCODE(col, row);
+			pressed = rowd & KB_ROWMASK(row);
+			key = locomokbd->keycode[scancode];
+
+			input_report_key(locomokbd->input, key, pressed);
+			if (likely(!pressed))
+				continue;
+
+			num_pressed++;
+
+			/* The "Cancel/ESC" key is labeled "On/Off" on
+			 * Collie and Poodle and should suspend the device
+			 * if it was pressed for more than a second. */
+			if (unlikely(key == KEY_ESC)) {
+				if (!time_after(jiffies,
+					locomokbd->suspend_jiffies + HZ))
+					continue;
+				if (locomokbd->count_cancel++
+					!= (HZ/SCAN_INTERVAL + 1))
+					continue;
+				input_event(locomokbd->input, EV_PWR,
+					KEY_SUSPEND, 1);
+				locomokbd->suspend_jiffies = jiffies;
+			} else
+				locomokbd->count_cancel = 0;
+		}
+		locomokbd_reset_col(membase, col);
+	}
+	locomokbd_activate_all(membase);
+
+	input_sync(locomokbd->input);
+
+	/* if any keys are pressed, enable the timer */
+	if (num_pressed)
+		mod_timer(&locomokbd->timer, jiffies + SCAN_INTERVAL);
+	else
+		locomokbd->count_cancel = 0;
+}
+
+/*
+ * LoCoMo keyboard interrupt handler.
+ */
+static irqreturn_t locomokbd_interrupt(int irq, void *dev_id)
+{
+	struct locomokbd *locomokbd = dev_id;
+	u16 r;
+
+	r = locomo_readl(locomokbd->base + LOCOMO_KIC);
+	if ((r & 0x0001) == 0)
+		return IRQ_HANDLED;
+
+	locomo_writel(r & ~0x0100, locomokbd->base + LOCOMO_KIC); /* Ack */
+
+	/** wait chattering delay **/
+	udelay(100);
+
+	locomokbd_scankeyboard(locomokbd);
+	return IRQ_HANDLED;
+}
+
+/*
+ * LoCoMo timer checking for released keys
+ */
+static void locomokbd_timer_callback(struct timer_list *t)
+{
+	struct locomokbd *locomokbd = timer_container_of(locomokbd, t, timer);
+
+	locomokbd_scankeyboard(locomokbd);
+}
+
+static int locomokbd_open(struct input_dev *dev)
+{
+	struct locomokbd *locomokbd = input_get_drvdata(dev);
+	u16 r;
+	
+	r = locomo_readl(locomokbd->base + LOCOMO_KIC) | 0x0010;
+	locomo_writel(r, locomokbd->base + LOCOMO_KIC);
+	return 0;
+}
+
+static void locomokbd_close(struct input_dev *dev)
+{
+	struct locomokbd *locomokbd = input_get_drvdata(dev);
+	u16 r;
+	
+	r = locomo_readl(locomokbd->base + LOCOMO_KIC) & ~0x0010;
+	locomo_writel(r, locomokbd->base + LOCOMO_KIC);
+}
+
+static int locomokbd_probe(struct locomo_dev *dev)
+{
+	struct locomokbd *locomokbd;
+	struct input_dev *input_dev;
+	int i, err;
+
+	locomokbd = kzalloc_obj(*locomokbd);
+	input_dev = input_allocate_device();
+	if (!locomokbd || !input_dev) {
+		err = -ENOMEM;
+		goto err_free_mem;
+	}
+
+	/* try and claim memory region */
+	if (!request_mem_region((unsigned long) dev->mapbase,
+				dev->length,
+				LOCOMO_DRIVER_NAME(dev))) {
+		err = -EBUSY;
+		printk(KERN_ERR "locomokbd: Can't acquire access to io memory for keyboard\n");
+		goto err_free_mem;
+	}
+
+	locomo_set_drvdata(dev, locomokbd);
+
+	locomokbd->base = (unsigned long) dev->mapbase;
+
+	spin_lock_init(&locomokbd->lock);
+
+	timer_setup(&locomokbd->timer, locomokbd_timer_callback, 0);
+
+	locomokbd->suspend_jiffies = jiffies;
+
+	locomokbd->input = input_dev;
+	strcpy(locomokbd->phys, "locomokbd/input0");
+
+	input_dev->name = "LoCoMo keyboard";
+	input_dev->phys = locomokbd->phys;
+	input_dev->id.bustype = BUS_HOST;
+	input_dev->id.vendor = 0x0001;
+	input_dev->id.product = 0x0001;
+	input_dev->id.version = 0x0100;
+	input_dev->open = locomokbd_open;
+	input_dev->close = locomokbd_close;
+	input_dev->dev.parent = &dev->dev;
+
+	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP) |
+				BIT_MASK(EV_PWR);
+	input_dev->keycode = locomokbd->keycode;
+	input_dev->keycodesize = sizeof(locomokbd_keycode[0]);
+	input_dev->keycodemax = ARRAY_SIZE(locomokbd_keycode);
+
+	input_set_drvdata(input_dev, locomokbd);
+
+	memcpy(locomokbd->keycode, locomokbd_keycode, sizeof(locomokbd->keycode));
+	for (i = 0; i < LOCOMOKBD_NUMKEYS; i++)
+		set_bit(locomokbd->keycode[i], input_dev->keybit);
+	clear_bit(0, input_dev->keybit);
+
+	/* attempt to get the interrupt */
+	err = request_irq(dev->irq[0], locomokbd_interrupt, 0, "locomokbd", locomokbd);
+	if (err) {
+		printk(KERN_ERR "locomokbd: Can't get irq for keyboard\n");
+		goto err_release_region;
+	}
+
+	err = input_register_device(locomokbd->input);
+	if (err)
+		goto err_free_irq;
+
+	return 0;
+
+ err_free_irq:
+	free_irq(dev->irq[0], locomokbd);
+ err_release_region:
+	release_mem_region((unsigned long) dev->mapbase, dev->length);
+	locomo_set_drvdata(dev, NULL);
+ err_free_mem:
+	input_free_device(input_dev);
+	kfree(locomokbd);
+
+	return err;
+}
+
+static void locomokbd_remove(struct locomo_dev *dev)
+{
+	struct locomokbd *locomokbd = locomo_get_drvdata(dev);
+
+	free_irq(dev->irq[0], locomokbd);
+
+	timer_shutdown_sync(&locomokbd->timer);
+
+	input_unregister_device(locomokbd->input);
+	locomo_set_drvdata(dev, NULL);
+
+	release_mem_region((unsigned long) dev->mapbase, dev->length);
+
+	kfree(locomokbd);
+}
+
+static struct locomo_driver keyboard_driver = {
+	.drv = {
+		.name = "locomokbd"
+	},
+	.devid	= LOCOMO_DEVID_KEYBOARD,
+	.probe	= locomokbd_probe,
+	.remove	= locomokbd_remove,
+};
+
+static int __init locomokbd_init(void)
+{
+	return locomo_driver_register(&keyboard_driver);
+}
+
+static void __exit locomokbd_exit(void)
+{
+	locomo_driver_unregister(&keyboard_driver);
+}
+
+module_init(locomokbd_init);
+module_exit(locomokbd_exit);