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, 239 insertions, 0 deletions

diff --git a/drivers/hid/hid-icade.c b/drivers/hid/hid-icade.c
new file mode 100644
index 000000000..f3716cfac
--- /dev/null
+++ b/drivers/hid/hid-icade.c
@@ -0,0 +1,239 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  ION iCade input driver
+ *
+ *  Copyright (c) 2012 Bastien Nocera <hadess@hadess.net>
+ *  Copyright (c) 2012 Benjamin Tissoires <benjamin.tissoires@gmail.com>
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+/*
+ *   ↑      A C Y L
+ *  ← →
+ *   ↓      B X Z R
+ *
+ *
+ *  UP ON,OFF  = w,e
+ *  RT ON,OFF  = d,c
+ *  DN ON,OFF  = x,z
+ *  LT ON,OFF  = a,q
+ *  A  ON,OFF  = y,t
+ *  B  ON,OFF  = h,r
+ *  C  ON,OFF  = u,f
+ *  X  ON,OFF  = j,n
+ *  Y  ON,OFF  = i,m
+ *  Z  ON,OFF  = k,p
+ *  L  ON,OFF  = o,g
+ *  R  ON,OFF  = l,v
+ */
+
+/* The translation code uses HID usage instead of input layer
+ * keys. This code generates a lookup table that makes
+ * translation quick.
+ *
+ * #include <linux/input.h>
+ * #include <stdio.h>
+ * #include <assert.h>
+ *
+ * #define unk     KEY_UNKNOWN
+ *
+ * < copy of hid_keyboard[] from hid-input.c >
+ *
+ * struct icade_key_translation {
+ *     int         from;
+ *     const char *to;
+ *     int         press;
+ * };
+ *
+ * static const struct icade_key_translation icade_keys[] = {
+ *    { KEY_W,        "KEY_UP",         1 },
+ *    { KEY_E,        "KEY_UP",         0 },
+ *    { KEY_D,        "KEY_RIGHT",      1 },
+ *    { KEY_C,        "KEY_RIGHT",      0 },
+ *    { KEY_X,        "KEY_DOWN",       1 },
+ *    { KEY_Z,        "KEY_DOWN",       0 },
+ *    { KEY_A,        "KEY_LEFT",       1 },
+ *    { KEY_Q,        "KEY_LEFT",       0 },
+ *    { KEY_Y,        "BTN_A",          1 },
+ *    { KEY_T,        "BTN_A",          0 },
+ *    { KEY_H,        "BTN_B",          1 },
+ *    { KEY_R,        "BTN_B",          0 },
+ *    { KEY_U,        "BTN_C",          1 },
+ *    { KEY_F,        "BTN_C",          0 },
+ *    { KEY_J,        "BTN_X",          1 },
+ *    { KEY_N,        "BTN_X",          0 },
+ *    { KEY_I,        "BTN_Y",          1 },
+ *    { KEY_M,        "BTN_Y",          0 },
+ *    { KEY_K,        "BTN_Z",          1 },
+ *    { KEY_P,        "BTN_Z",          0 },
+ *    { KEY_O,        "BTN_THUMBL",     1 },
+ *    { KEY_G,        "BTN_THUMBL",     0 },
+ *    { KEY_L,        "BTN_THUMBR",     1 },
+ *    { KEY_V,        "BTN_THUMBR",     0 },
+ *
+ *    { }
+ * };
+ *
+ * static int
+ * usage_for_key (int key)
+ * {
+ *     int i;
+ *     for (i = 0; i < 256; i++) {
+ *     if (hid_keyboard[i] == key)
+ *         return i;
+ *     }
+ *     assert(0);
+ * }
+ *
+ * int main (int argc, char **argv)
+ * {
+ *     const struct icade_key_translation *trans;
+ *     int max_usage = 0;
+ *
+ *     for (trans = icade_keys; trans->from; trans++) {
+ *         int usage = usage_for_key (trans->from);
+ *         max_usage = usage > max_usage ? usage : max_usage;
+ *     }
+ *
+ *     printf ("#define ICADE_MAX_USAGE %d\n\n", max_usage);
+ *     printf ("struct icade_key {\n");
+ *     printf ("\tu16 to;\n");
+ *     printf ("\tu8 press:1;\n");
+ *     printf ("};\n\n");
+ *     printf ("static const struct icade_key "
+ *             "icade_usage_table[%d] = {\n", max_usage + 1);
+ *     for (trans = icade_keys; trans->from; trans++) {
+ *         printf ("\t[%d] = { %s, %d },\n",
+ *                 usage_for_key (trans->from), trans->to, trans->press);
+ *     }
+ *     printf ("};\n");
+ *
+ *     return 0;
+ * }
+ */
+
+#define ICADE_MAX_USAGE 29
+
+struct icade_key {
+	u16 to;
+	u8 press:1;
+};
+
+static const struct icade_key icade_usage_table[30] = {
+	[26] = { KEY_UP, 1 },
+	[8] = { KEY_UP, 0 },
+	[7] = { KEY_RIGHT, 1 },
+	[6] = { KEY_RIGHT, 0 },
+	[27] = { KEY_DOWN, 1 },
+	[29] = { KEY_DOWN, 0 },
+	[4] = { KEY_LEFT, 1 },
+	[20] = { KEY_LEFT, 0 },
+	[28] = { BTN_A, 1 },
+	[23] = { BTN_A, 0 },
+	[11] = { BTN_B, 1 },
+	[21] = { BTN_B, 0 },
+	[24] = { BTN_C, 1 },
+	[9] = { BTN_C, 0 },
+	[13] = { BTN_X, 1 },
+	[17] = { BTN_X, 0 },
+	[12] = { BTN_Y, 1 },
+	[16] = { BTN_Y, 0 },
+	[14] = { BTN_Z, 1 },
+	[19] = { BTN_Z, 0 },
+	[18] = { BTN_THUMBL, 1 },
+	[10] = { BTN_THUMBL, 0 },
+	[15] = { BTN_THUMBR, 1 },
+	[25] = { BTN_THUMBR, 0 },
+};
+
+static const struct icade_key *icade_find_translation(u16 from)
+{
+	if (from > ICADE_MAX_USAGE)
+		return NULL;
+	return &icade_usage_table[from];
+}
+
+static int icade_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	const struct icade_key *trans;
+
+	if (!(hdev->claimed & HID_CLAIMED_INPUT) || !field->hidinput ||
+			!usage->type)
+		return 0;
+
+	/* We ignore the fake key up, and act only on key down */
+	if (!value)
+		return 1;
+
+	trans = icade_find_translation(usage->hid & HID_USAGE);
+
+	if (!trans)
+		return 1;
+
+	input_event(field->hidinput->input, usage->type,
+			trans->to, trans->press);
+
+	return 1;
+}
+
+static int icade_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	const struct icade_key *trans;
+
+	if ((usage->hid & HID_USAGE_PAGE) == HID_UP_KEYBOARD) {
+		trans = icade_find_translation(usage->hid & HID_USAGE);
+
+		if (!trans)
+			return -1;
+
+		hid_map_usage(hi, usage, bit, max, EV_KEY, trans->to);
+		set_bit(trans->to, hi->input->keybit);
+
+		return 1;
+	}
+
+	/* ignore others */
+	return -1;
+
+}
+
+static int icade_input_mapped(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	if (usage->type == EV_KEY)
+		set_bit(usage->type, hi->input->evbit);
+
+	return -1;
+}
+
+static const struct hid_device_id icade_devices[] = {
+	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_ION, USB_DEVICE_ID_ICADE) },
+
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, icade_devices);
+
+static struct hid_driver icade_driver = {
+	.name = "icade",
+	.id_table = icade_devices,
+	.event = icade_event,
+	.input_mapped = icade_input_mapped,
+	.input_mapping = icade_input_mapping,
+};
+module_hid_driver(icade_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Bastien Nocera <hadess@hadess.net>");
+MODULE_DESCRIPTION("ION iCade input driver");