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, 294 insertions, 0 deletions

diff --git a/drivers/input/sparse-keymap.c b/drivers/input/sparse-keymap.c
new file mode 100644
index 000000000..164f8fcfd
--- /dev/null
+++ b/drivers/input/sparse-keymap.c
@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Generic support for sparse keymaps
+ *
+ * Copyright (c) 2009 Dmitry Torokhov
+ *
+ * Derived from wistron button driver:
+ * Copyright (C) 2005 Miloslav Trmac <mitr@volny.cz>
+ * Copyright (C) 2005 Bernhard Rosenkraenzer <bero@arklinux.org>
+ * Copyright (C) 2005 Dmitry Torokhov <dtor@mail.ru>
+ */
+
+#include <linux/export.h>
+#include <linux/input.h>
+#include <linux/input/sparse-keymap.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
+MODULE_DESCRIPTION("Generic support for sparse keymaps");
+MODULE_LICENSE("GPL v2");
+
+static unsigned int sparse_keymap_get_key_index(struct input_dev *dev,
+						const struct key_entry *k)
+{
+	struct key_entry *key;
+	unsigned int idx = 0;
+
+	for (key = dev->keycode; key->type != KE_END; key++) {
+		if (key->type == KE_KEY) {
+			if (key == k)
+				break;
+			idx++;
+		}
+	}
+
+	return idx;
+}
+
+static struct key_entry *sparse_keymap_entry_by_index(struct input_dev *dev,
+						      unsigned int index)
+{
+	struct key_entry *key;
+	unsigned int key_cnt = 0;
+
+	for (key = dev->keycode; key->type != KE_END; key++)
+		if (key->type == KE_KEY)
+			if (key_cnt++ == index)
+				return key;
+
+	return NULL;
+}
+
+/**
+ * sparse_keymap_entry_from_scancode - perform sparse keymap lookup
+ * @dev: Input device using sparse keymap
+ * @code: Scan code
+ *
+ * This function is used to perform &struct key_entry lookup in an
+ * input device using sparse keymap.
+ */
+struct key_entry *sparse_keymap_entry_from_scancode(struct input_dev *dev,
+						    unsigned int code)
+{
+	struct key_entry *key;
+
+	for (key = dev->keycode; key->type != KE_END; key++)
+		if (code == key->code)
+			return key;
+
+	return NULL;
+}
+EXPORT_SYMBOL(sparse_keymap_entry_from_scancode);
+
+/**
+ * sparse_keymap_entry_from_keycode - perform sparse keymap lookup
+ * @dev: Input device using sparse keymap
+ * @keycode: Key code
+ *
+ * This function is used to perform &struct key_entry lookup in an
+ * input device using sparse keymap.
+ */
+struct key_entry *sparse_keymap_entry_from_keycode(struct input_dev *dev,
+						   unsigned int keycode)
+{
+	struct key_entry *key;
+
+	for (key = dev->keycode; key->type != KE_END; key++)
+		if (key->type == KE_KEY && keycode == key->keycode)
+			return key;
+
+	return NULL;
+}
+EXPORT_SYMBOL(sparse_keymap_entry_from_keycode);
+
+static struct key_entry *sparse_keymap_locate(struct input_dev *dev,
+					const struct input_keymap_entry *ke)
+{
+	struct key_entry *key;
+	unsigned int scancode;
+
+	if (ke->flags & INPUT_KEYMAP_BY_INDEX)
+		key = sparse_keymap_entry_by_index(dev, ke->index);
+	else if (input_scancode_to_scalar(ke, &scancode) == 0)
+		key = sparse_keymap_entry_from_scancode(dev, scancode);
+	else
+		key = NULL;
+
+	return key;
+}
+
+static int sparse_keymap_getkeycode(struct input_dev *dev,
+				    struct input_keymap_entry *ke)
+{
+	const struct key_entry *key;
+
+	if (dev->keycode) {
+		key = sparse_keymap_locate(dev, ke);
+		if (key && key->type == KE_KEY) {
+			ke->keycode = key->keycode;
+			if (!(ke->flags & INPUT_KEYMAP_BY_INDEX))
+				ke->index =
+					sparse_keymap_get_key_index(dev, key);
+			ke->len = sizeof(key->code);
+			memcpy(ke->scancode, &key->code, sizeof(key->code));
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int sparse_keymap_setkeycode(struct input_dev *dev,
+				    const struct input_keymap_entry *ke,
+				    unsigned int *old_keycode)
+{
+	struct key_entry *key;
+
+	if (dev->keycode) {
+		key = sparse_keymap_locate(dev, ke);
+		if (key && key->type == KE_KEY) {
+			*old_keycode = key->keycode;
+			key->keycode = ke->keycode;
+			set_bit(ke->keycode, dev->keybit);
+			if (!sparse_keymap_entry_from_keycode(dev, *old_keycode))
+				clear_bit(*old_keycode, dev->keybit);
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+/**
+ * sparse_keymap_setup - set up sparse keymap for an input device
+ * @dev: Input device
+ * @keymap: Keymap in form of array of &key_entry structures ending
+ *	with %KE_END type entry
+ * @setup: Function that can be used to adjust keymap entries
+ *	depending on device's needs, may be %NULL
+ *
+ * The function calculates size and allocates copy of the original
+ * keymap after which sets up input device event bits appropriately.
+ * The allocated copy of the keymap is automatically freed when it
+ * is no longer needed.
+ */
+int sparse_keymap_setup(struct input_dev *dev,
+			const struct key_entry *keymap,
+			int (*setup)(struct input_dev *, struct key_entry *))
+{
+	size_t map_size = 1; /* to account for the last KE_END entry */
+	const struct key_entry *e;
+	struct key_entry *map, *entry;
+	int i;
+	int error;
+
+	for (e = keymap; e->type != KE_END; e++)
+		map_size++;
+
+	map = devm_kmemdup_array(&dev->dev, keymap, map_size, sizeof(*keymap), GFP_KERNEL);
+	if (!map)
+		return -ENOMEM;
+
+	for (i = 0; i < map_size; i++) {
+		entry = &map[i];
+
+		if (setup) {
+			error = setup(dev, entry);
+			if (error)
+				return error;
+		}
+
+		switch (entry->type) {
+		case KE_KEY:
+			__set_bit(EV_KEY, dev->evbit);
+			__set_bit(entry->keycode, dev->keybit);
+			break;
+
+		case KE_SW:
+		case KE_VSW:
+			__set_bit(EV_SW, dev->evbit);
+			__set_bit(entry->sw.code, dev->swbit);
+			break;
+		}
+	}
+
+	if (test_bit(EV_KEY, dev->evbit)) {
+		__set_bit(KEY_UNKNOWN, dev->keybit);
+		__set_bit(EV_MSC, dev->evbit);
+		__set_bit(MSC_SCAN, dev->mscbit);
+	}
+
+	dev->keycode = map;
+	dev->keycodemax = map_size;
+	dev->getkeycode = sparse_keymap_getkeycode;
+	dev->setkeycode = sparse_keymap_setkeycode;
+
+	return 0;
+}
+EXPORT_SYMBOL(sparse_keymap_setup);
+
+/**
+ * sparse_keymap_report_entry - report event corresponding to given key entry
+ * @dev: Input device for which event should be reported
+ * @ke: key entry describing event
+ * @value: Value that should be reported (ignored by %KE_SW entries)
+ * @autorelease: Signals whether release event should be emitted for %KE_KEY
+ *	entries right after reporting press event, ignored by all other
+ *	entries
+ *
+ * This function is used to report input event described by given
+ * &struct key_entry.
+ */
+void sparse_keymap_report_entry(struct input_dev *dev, const struct key_entry *ke,
+				unsigned int value, bool autorelease)
+{
+	switch (ke->type) {
+	case KE_KEY:
+		input_event(dev, EV_MSC, MSC_SCAN, ke->code);
+		input_report_key(dev, ke->keycode, value);
+		input_sync(dev);
+		if (value && autorelease) {
+			input_report_key(dev, ke->keycode, 0);
+			input_sync(dev);
+		}
+		break;
+
+	case KE_SW:
+		value = ke->sw.value;
+		fallthrough;
+
+	case KE_VSW:
+		input_report_switch(dev, ke->sw.code, value);
+		input_sync(dev);
+		break;
+	}
+}
+EXPORT_SYMBOL(sparse_keymap_report_entry);
+
+/**
+ * sparse_keymap_report_event - report event corresponding to given scancode
+ * @dev: Input device using sparse keymap
+ * @code: Scan code
+ * @value: Value that should be reported (ignored by %KE_SW entries)
+ * @autorelease: Signals whether release event should be emitted for %KE_KEY
+ *	entries right after reporting press event, ignored by all other
+ *	entries
+ *
+ * This function is used to perform lookup in an input device using sparse
+ * keymap and report corresponding event. Returns %true if lookup was
+ * successful and %false otherwise.
+ */
+bool sparse_keymap_report_event(struct input_dev *dev, unsigned int code,
+				unsigned int value, bool autorelease)
+{
+	const struct key_entry *ke =
+		sparse_keymap_entry_from_scancode(dev, code);
+	struct key_entry unknown_ke;
+
+	if (ke) {
+		sparse_keymap_report_entry(dev, ke, value, autorelease);
+		return true;
+	}
+
+	/* Report an unknown key event as a debugging aid */
+	unknown_ke.type = KE_KEY;
+	unknown_ke.code = code;
+	unknown_ke.keycode = KEY_UNKNOWN;
+	sparse_keymap_report_entry(dev, &unknown_ke, value, true);
+
+	return false;
+}
+EXPORT_SYMBOL(sparse_keymap_report_event);
+