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, 242 insertions, 0 deletions

diff --git a/drivers/input/keyboard/amikbd.c b/drivers/input/keyboard/amikbd.c
new file mode 100644
index 000000000..ecfae0b0b
--- /dev/null
+++ b/drivers/input/keyboard/amikbd.c
@@ -0,0 +1,242 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (c) 2000-2001 Vojtech Pavlik
+ *
+ *  Based on the work of:
+ *	Hamish Macdonald
+ */
+
+/*
+ * Amiga keyboard driver for Linux/m68k
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/keyboard.h>
+#include <linux/platform_device.h>
+
+#include <asm/amigaints.h>
+#include <asm/amigahw.h>
+#include <asm/irq.h>
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION("Amiga keyboard driver");
+MODULE_LICENSE("GPL");
+
+#ifdef CONFIG_VT
+static unsigned char amikbd_keycode[0x78] __initdata = {
+	[0]	 = KEY_GRAVE,
+	[1]	 = KEY_1,
+	[2]	 = KEY_2,
+	[3]	 = KEY_3,
+	[4]	 = KEY_4,
+	[5]	 = KEY_5,
+	[6]	 = KEY_6,
+	[7]	 = KEY_7,
+	[8]	 = KEY_8,
+	[9]	 = KEY_9,
+	[10]	 = KEY_0,
+	[11]	 = KEY_MINUS,
+	[12]	 = KEY_EQUAL,
+	[13]	 = KEY_BACKSLASH,
+	[15]	 = KEY_KP0,
+	[16]	 = KEY_Q,
+	[17]	 = KEY_W,
+	[18]	 = KEY_E,
+	[19]	 = KEY_R,
+	[20]	 = KEY_T,
+	[21]	 = KEY_Y,
+	[22]	 = KEY_U,
+	[23]	 = KEY_I,
+	[24]	 = KEY_O,
+	[25]	 = KEY_P,
+	[26]	 = KEY_LEFTBRACE,
+	[27]	 = KEY_RIGHTBRACE,
+	[29]	 = KEY_KP1,
+	[30]	 = KEY_KP2,
+	[31]	 = KEY_KP3,
+	[32]	 = KEY_A,
+	[33]	 = KEY_S,
+	[34]	 = KEY_D,
+	[35]	 = KEY_F,
+	[36]	 = KEY_G,
+	[37]	 = KEY_H,
+	[38]	 = KEY_J,
+	[39]	 = KEY_K,
+	[40]	 = KEY_L,
+	[41]	 = KEY_SEMICOLON,
+	[42]	 = KEY_APOSTROPHE,
+	[43]	 = KEY_BACKSLASH,
+	[45]	 = KEY_KP4,
+	[46]	 = KEY_KP5,
+	[47]	 = KEY_KP6,
+	[48]	 = KEY_102ND,
+	[49]	 = KEY_Z,
+	[50]	 = KEY_X,
+	[51]	 = KEY_C,
+	[52]	 = KEY_V,
+	[53]	 = KEY_B,
+	[54]	 = KEY_N,
+	[55]	 = KEY_M,
+	[56]	 = KEY_COMMA,
+	[57]	 = KEY_DOT,
+	[58]	 = KEY_SLASH,
+	[60]	 = KEY_KPDOT,
+	[61]	 = KEY_KP7,
+	[62]	 = KEY_KP8,
+	[63]	 = KEY_KP9,
+	[64]	 = KEY_SPACE,
+	[65]	 = KEY_BACKSPACE,
+	[66]	 = KEY_TAB,
+	[67]	 = KEY_KPENTER,
+	[68]	 = KEY_ENTER,
+	[69]	 = KEY_ESC,
+	[70]	 = KEY_DELETE,
+	[74]	 = KEY_KPMINUS,
+	[76]	 = KEY_UP,
+	[77]	 = KEY_DOWN,
+	[78]	 = KEY_RIGHT,
+	[79]	 = KEY_LEFT,
+	[80]	 = KEY_F1,
+	[81]	 = KEY_F2,
+	[82]	 = KEY_F3,
+	[83]	 = KEY_F4,
+	[84]	 = KEY_F5,
+	[85]	 = KEY_F6,
+	[86]	 = KEY_F7,
+	[87]	 = KEY_F8,
+	[88]	 = KEY_F9,
+	[89]	 = KEY_F10,
+	[90]	 = KEY_KPLEFTPAREN,
+	[91]	 = KEY_KPRIGHTPAREN,
+	[92]	 = KEY_KPSLASH,
+	[93]	 = KEY_KPASTERISK,
+	[94]	 = KEY_KPPLUS,
+	[95]	 = KEY_HELP,
+	[96]	 = KEY_LEFTSHIFT,
+	[97]	 = KEY_RIGHTSHIFT,
+	[98]	 = KEY_CAPSLOCK,
+	[99]	 = KEY_LEFTCTRL,
+	[100]	 = KEY_LEFTALT,
+	[101]	 = KEY_RIGHTALT,
+	[102]	 = KEY_LEFTMETA,
+	[103]	 = KEY_RIGHTMETA
+};
+
+static void __init amikbd_init_console_keymaps(void)
+{
+	/* We can spare 512 bytes on stack for temp_map in init path. */
+	unsigned short temp_map[NR_KEYS];
+	int i, j;
+
+	for (i = 0; i < MAX_NR_KEYMAPS; i++) {
+		if (!key_maps[i])
+			continue;
+		memset(temp_map, 0, sizeof(temp_map));
+		for (j = 0; j < 0x78; j++) {
+			if (!amikbd_keycode[j])
+				continue;
+			temp_map[j] = key_maps[i][amikbd_keycode[j]];
+		}
+		for (j = 0; j < NR_KEYS; j++) {
+			if (!temp_map[j])
+				temp_map[j] = 0xf200;
+		}
+		memcpy(key_maps[i], temp_map, sizeof(temp_map));
+	}
+}
+#else /* !CONFIG_VT */
+static inline void amikbd_init_console_keymaps(void) {}
+#endif /* !CONFIG_VT */
+
+static const char *amikbd_messages[8] = {
+	[0] = KERN_ALERT "amikbd: Ctrl-Amiga-Amiga reset warning!!\n",
+	[1] = KERN_WARNING "amikbd: keyboard lost sync\n",
+	[2] = KERN_WARNING "amikbd: keyboard buffer overflow\n",
+	[3] = KERN_WARNING "amikbd: keyboard controller failure\n",
+	[4] = KERN_ERR "amikbd: keyboard selftest failure\n",
+	[5] = KERN_INFO "amikbd: initiate power-up key stream\n",
+	[6] = KERN_INFO "amikbd: terminate power-up key stream\n",
+	[7] = KERN_WARNING "amikbd: keyboard interrupt\n"
+};
+
+static irqreturn_t amikbd_interrupt(int irq, void *data)
+{
+	struct input_dev *dev = data;
+	unsigned char scancode, down;
+
+	scancode = ~ciaa.sdr;		/* get and invert scancode (keyboard is active low) */
+	ciaa.cra |= 0x40;		/* switch SP pin to output for handshake */
+	udelay(85);			/* wait until 85 us have expired */
+	ciaa.cra &= ~0x40;		/* switch CIA serial port to input mode */
+
+	down = !(scancode & 1);		/* lowest bit is release bit */
+	scancode >>= 1;
+
+	if (scancode < 0x78) {		/* scancodes < 0x78 are keys */
+		if (scancode == 98) {	/* CapsLock is a toggle switch key on Amiga */
+			input_report_key(dev, scancode, 1);
+			input_report_key(dev, scancode, 0);
+		} else {
+			input_report_key(dev, scancode, down);
+		}
+
+		input_sync(dev);
+	} else				/* scancodes >= 0x78 are error codes */
+		printk(amikbd_messages[scancode - 0x78]);
+
+	return IRQ_HANDLED;
+}
+
+static int __init amikbd_probe(struct platform_device *pdev)
+{
+	struct input_dev *dev;
+	int i, err;
+
+	dev = devm_input_allocate_device(&pdev->dev);
+	if (!dev) {
+		dev_err(&pdev->dev, "Not enough memory for input device\n");
+		return -ENOMEM;
+	}
+
+	dev->name = pdev->name;
+	dev->phys = "amikbd/input0";
+	dev->id.bustype = BUS_AMIGA;
+	dev->id.vendor = 0x0001;
+	dev->id.product = 0x0001;
+	dev->id.version = 0x0100;
+
+	dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);
+
+	for (i = 0; i < 0x78; i++)
+		set_bit(i, dev->keybit);
+
+	amikbd_init_console_keymaps();
+
+	ciaa.cra &= ~0x41;	 /* serial data in, turn off TA */
+	err = devm_request_irq(&pdev->dev, IRQ_AMIGA_CIAA_SP, amikbd_interrupt,
+			       0, "amikbd", dev);
+	if (err)
+		return err;
+
+	err = input_register_device(dev);
+	if (err)
+		return err;
+
+	platform_set_drvdata(pdev, dev);
+
+	return 0;
+}
+
+static struct platform_driver amikbd_driver = {
+	.driver   = {
+		.name	= "amiga-keyboard",
+	},
+};
+
+module_platform_driver_probe(amikbd_driver, amikbd_probe);
+
+MODULE_ALIAS("platform:amiga-keyboard");