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, 232 insertions, 0 deletions

diff --git a/drivers/input/keyboard/atakbd.c b/drivers/input/keyboard/atakbd.c
new file mode 100644
index 000000000..07e17e563
--- /dev/null
+++ b/drivers/input/keyboard/atakbd.c
@@ -0,0 +1,232 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  atakbd.c
+ *
+ *  Copyright (c) 2005 Michael Schmitz
+ *
+ * Based on amikbd.c, which is
+ *
+ *  Copyright (c) 2000-2001 Vojtech Pavlik
+ *
+ *  Based on the work of:
+ *	Hamish Macdonald
+ */
+
+/*
+ * Atari keyboard driver for Linux/m68k
+ *
+ * The low level init and interrupt stuff is handled in arch/mm68k/atari/atakeyb.c
+ * (the keyboard ACIA also handles the mouse and joystick data, and the keyboard
+ * interrupt is shared with the MIDI ACIA so MIDI data also get handled there).
+ * This driver only deals with handing key events off to the input layer.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+
+#include <asm/atariints.h>
+#include <asm/atarihw.h>
+#include <asm/atarikb.h>
+#include <asm/irq.h>
+
+MODULE_AUTHOR("Michael Schmitz <schmitz@biophys.uni-duesseldorf.de>");
+MODULE_DESCRIPTION("Atari keyboard driver");
+MODULE_LICENSE("GPL");
+
+/*
+ 0x47: KP_7     71
+ 0x48: KP_8     72
+ 0x49: KP_9     73
+ 0x62: KP_/     98
+ 0x4b: KP_4     75
+ 0x4c: KP_5     76
+ 0x4d: KP_6     77
+ 0x37: KP_*     55
+ 0x4f: KP_1     79
+ 0x50: KP_2     80
+ 0x51: KP_3     81
+ 0x4a: KP_-     74
+ 0x52: KP_0     82
+ 0x53: KP_.     83
+ 0x4e: KP_+     78
+
+ 0x67: Up       103
+ 0x6c: Down     108
+ 0x69: Left     105
+ 0x6a: Right    106
+ */
+
+
+static unsigned char atakbd_keycode[0x73] = {	/* American layout */
+	[1]	 = KEY_ESC,
+	[2]	 = KEY_1,
+	[3]	 = KEY_2,
+	[4]	 = KEY_3,
+	[5]	 = KEY_4,
+	[6]	 = KEY_5,
+	[7]	 = KEY_6,
+	[8]	 = KEY_7,
+	[9]	 = KEY_8,
+	[10]	 = KEY_9,
+	[11]	 = KEY_0,
+	[12]	 = KEY_MINUS,
+	[13]	 = KEY_EQUAL,
+	[14]	 = KEY_BACKSPACE,
+	[15]	 = KEY_TAB,
+	[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,
+	[28]	 = KEY_ENTER,
+	[29]	 = KEY_LEFTCTRL,
+	[30]	 = KEY_A,
+	[31]	 = KEY_S,
+	[32]	 = KEY_D,
+	[33]	 = KEY_F,
+	[34]	 = KEY_G,
+	[35]	 = KEY_H,
+	[36]	 = KEY_J,
+	[37]	 = KEY_K,
+	[38]	 = KEY_L,
+	[39]	 = KEY_SEMICOLON,
+	[40]	 = KEY_APOSTROPHE,
+	[41]	 = KEY_GRAVE,
+	[42]	 = KEY_LEFTSHIFT,
+	[43]	 = KEY_BACKSLASH,
+	[44]	 = KEY_Z,
+	[45]	 = KEY_X,
+	[46]	 = KEY_C,
+	[47]	 = KEY_V,
+	[48]	 = KEY_B,
+	[49]	 = KEY_N,
+	[50]	 = KEY_M,
+	[51]	 = KEY_COMMA,
+	[52]	 = KEY_DOT,
+	[53]	 = KEY_SLASH,
+	[54]	 = KEY_RIGHTSHIFT,
+	[55]	 = KEY_KPASTERISK,
+	[56]	 = KEY_LEFTALT,
+	[57]	 = KEY_SPACE,
+	[58]	 = KEY_CAPSLOCK,
+	[59]	 = KEY_F1,
+	[60]	 = KEY_F2,
+	[61]	 = KEY_F3,
+	[62]	 = KEY_F4,
+	[63]	 = KEY_F5,
+	[64]	 = KEY_F6,
+	[65]	 = KEY_F7,
+	[66]	 = KEY_F8,
+	[67]	 = KEY_F9,
+	[68]	 = KEY_F10,
+	[71]	 = KEY_HOME,
+	[72]	 = KEY_UP,
+	[74]	 = KEY_KPMINUS,
+	[75]	 = KEY_LEFT,
+	[77]	 = KEY_RIGHT,
+	[78]	 = KEY_KPPLUS,
+	[80]	 = KEY_DOWN,
+	[82]	 = KEY_INSERT,
+	[83]	 = KEY_DELETE,
+	[96]	 = KEY_102ND,
+	[97]	 = KEY_UNDO,
+	[98]	 = KEY_HELP,
+	[99]	 = KEY_KPLEFTPAREN,
+	[100]	 = KEY_KPRIGHTPAREN,
+	[101]	 = KEY_KPSLASH,
+	[102]	 = KEY_KPASTERISK,
+	[103]	 = KEY_KP7,
+	[104]	 = KEY_KP8,
+	[105]	 = KEY_KP9,
+	[106]	 = KEY_KP4,
+	[107]	 = KEY_KP5,
+	[108]	 = KEY_KP6,
+	[109]	 = KEY_KP1,
+	[110]	 = KEY_KP2,
+	[111]	 = KEY_KP3,
+	[112]	 = KEY_KP0,
+	[113]	 = KEY_KPDOT,
+	[114]	 = KEY_KPENTER,
+};
+
+static struct input_dev *atakbd_dev;
+
+static void atakbd_interrupt(unsigned char scancode, char down)
+{
+
+	if (scancode < 0x73) {		/* scancodes < 0xf3 are keys */
+
+		// report raw events here?
+
+		scancode = atakbd_keycode[scancode];
+
+		input_report_key(atakbd_dev, scancode, down);
+		input_sync(atakbd_dev);
+	} else				/* scancodes >= 0xf3 are mouse data, most likely */
+		printk(KERN_INFO "atakbd: unhandled scancode %x\n", scancode);
+
+	return;
+}
+
+static int __init atakbd_init(void)
+{
+	int i, error;
+
+	if (!MACH_IS_ATARI || !ATARIHW_PRESENT(ST_MFP))
+		return -ENODEV;
+
+	// need to init core driver if not already done so
+	error = atari_keyb_init();
+	if (error)
+		return error;
+
+	atakbd_dev = input_allocate_device();
+	if (!atakbd_dev)
+		return -ENOMEM;
+
+	atakbd_dev->name = "Atari Keyboard";
+	atakbd_dev->phys = "atakbd/input0";
+	atakbd_dev->id.bustype = BUS_HOST;
+	atakbd_dev->id.vendor = 0x0001;
+	atakbd_dev->id.product = 0x0001;
+	atakbd_dev->id.version = 0x0100;
+
+	atakbd_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);
+	atakbd_dev->keycode = atakbd_keycode;
+	atakbd_dev->keycodesize = sizeof(unsigned char);
+	atakbd_dev->keycodemax = ARRAY_SIZE(atakbd_keycode);
+
+	for (i = 1; i < 0x72; i++) {
+		set_bit(atakbd_keycode[i], atakbd_dev->keybit);
+	}
+
+	/* error check */
+	error = input_register_device(atakbd_dev);
+	if (error) {
+		input_free_device(atakbd_dev);
+		return error;
+	}
+
+	atari_input_keyboard_interrupt_hook = atakbd_interrupt;
+
+	return 0;
+}
+
+static void __exit atakbd_exit(void)
+{
+	atari_input_keyboard_interrupt_hook = NULL;
+	input_unregister_device(atakbd_dev);
+}
+
+module_init(atakbd_init);
+module_exit(atakbd_exit);