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, 426 insertions, 0 deletions

diff --git a/drivers/clk/clk-gpio.c b/drivers/clk/clk-gpio.c
new file mode 100644
index 000000000..9099c57e2
--- /dev/null
+++ b/drivers/clk/clk-gpio.c
@@ -0,0 +1,426 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2013 - 2014 Texas Instruments Incorporated - https://www.ti.com
+ *
+ * Authors:
+ *    Jyri Sarha <jsarha@ti.com>
+ *    Sergej Sawazki <ce3a@gmx.de>
+ *
+ * Gpio controlled clock implementation
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/gpio/consumer.h>
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+
+/**
+ * DOC: basic gpio gated clock which can be enabled and disabled
+ *      with gpio output
+ * Traits of this clock:
+ * prepare - clk_(un)prepare are functional and control a gpio that can sleep
+ * enable - clk_enable and clk_disable are functional & control
+ *          non-sleeping gpio
+ * rate - inherits rate from parent.  No clk_set_rate support
+ * parent - fixed parent.  No clk_set_parent support
+ */
+
+/**
+ * struct clk_gpio - gpio gated clock
+ *
+ * @hw:		handle between common and hardware-specific interfaces
+ * @gpiod:	gpio descriptor
+ *
+ * Clock with a gpio control for enabling and disabling the parent clock
+ * or switching between two parents by asserting or deasserting the gpio.
+ *
+ * Implements .enable, .disable and .is_enabled or
+ * .get_parent, .set_parent and .determine_rate depending on which clk_ops
+ * is used.
+ */
+struct clk_gpio {
+	struct clk_hw	hw;
+	struct gpio_desc *gpiod;
+};
+
+#define to_clk_gpio(_hw) container_of(_hw, struct clk_gpio, hw)
+
+static int clk_gpio_gate_enable(struct clk_hw *hw)
+{
+	struct clk_gpio *clk = to_clk_gpio(hw);
+
+	gpiod_set_value(clk->gpiod, 1);
+
+	return 0;
+}
+
+static void clk_gpio_gate_disable(struct clk_hw *hw)
+{
+	struct clk_gpio *clk = to_clk_gpio(hw);
+
+	gpiod_set_value(clk->gpiod, 0);
+}
+
+static int clk_gpio_gate_is_enabled(struct clk_hw *hw)
+{
+	struct clk_gpio *clk = to_clk_gpio(hw);
+
+	return gpiod_get_value(clk->gpiod);
+}
+
+static const struct clk_ops clk_gpio_gate_ops = {
+	.enable = clk_gpio_gate_enable,
+	.disable = clk_gpio_gate_disable,
+	.is_enabled = clk_gpio_gate_is_enabled,
+};
+
+static int clk_sleeping_gpio_gate_prepare(struct clk_hw *hw)
+{
+	struct clk_gpio *clk = to_clk_gpio(hw);
+
+	gpiod_set_value_cansleep(clk->gpiod, 1);
+
+	return 0;
+}
+
+static void clk_sleeping_gpio_gate_unprepare(struct clk_hw *hw)
+{
+	struct clk_gpio *clk = to_clk_gpio(hw);
+
+	gpiod_set_value_cansleep(clk->gpiod, 0);
+}
+
+static int clk_sleeping_gpio_gate_is_prepared(struct clk_hw *hw)
+{
+	struct clk_gpio *clk = to_clk_gpio(hw);
+
+	return gpiod_get_value_cansleep(clk->gpiod);
+}
+
+static const struct clk_ops clk_sleeping_gpio_gate_ops = {
+	.prepare = clk_sleeping_gpio_gate_prepare,
+	.unprepare = clk_sleeping_gpio_gate_unprepare,
+	.is_prepared = clk_sleeping_gpio_gate_is_prepared,
+};
+
+/**
+ * DOC: basic clock multiplexer which can be controlled with a gpio output
+ * Traits of this clock:
+ * prepare - clk_prepare only ensures that parents are prepared
+ * rate - rate is only affected by parent switching.  No clk_set_rate support
+ * parent - parent is adjustable through clk_set_parent
+ */
+
+static u8 clk_gpio_mux_get_parent(struct clk_hw *hw)
+{
+	struct clk_gpio *clk = to_clk_gpio(hw);
+
+	return gpiod_get_value_cansleep(clk->gpiod);
+}
+
+static int clk_gpio_mux_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct clk_gpio *clk = to_clk_gpio(hw);
+
+	gpiod_set_value_cansleep(clk->gpiod, index);
+
+	return 0;
+}
+
+static const struct clk_ops clk_gpio_mux_ops = {
+	.get_parent = clk_gpio_mux_get_parent,
+	.set_parent = clk_gpio_mux_set_parent,
+	.determine_rate = __clk_mux_determine_rate,
+};
+
+static struct clk_hw *clk_register_gpio(struct device *dev, u8 num_parents,
+					struct gpio_desc *gpiod,
+					const struct clk_ops *clk_gpio_ops)
+{
+	struct clk_gpio *clk_gpio;
+	struct clk_hw *hw;
+	struct clk_init_data init = {};
+	int err;
+	const struct clk_parent_data gpio_parent_data[] = {
+		{ .index = 0 },
+		{ .index = 1 },
+	};
+
+	clk_gpio = devm_kzalloc(dev, sizeof(*clk_gpio),	GFP_KERNEL);
+	if (!clk_gpio)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = dev->of_node->name;
+	init.ops = clk_gpio_ops;
+	init.parent_data = gpio_parent_data;
+	init.num_parents = num_parents;
+	init.flags = CLK_SET_RATE_PARENT;
+
+	clk_gpio->gpiod = gpiod;
+	clk_gpio->hw.init = &init;
+
+	hw = &clk_gpio->hw;
+	err = devm_clk_hw_register(dev, hw);
+	if (err)
+		return ERR_PTR(err);
+
+	return hw;
+}
+
+static struct clk_hw *clk_hw_register_gpio_gate(struct device *dev,
+						int num_parents,
+						struct gpio_desc *gpiod)
+{
+	const struct clk_ops *ops;
+
+	if (gpiod_cansleep(gpiod))
+		ops = &clk_sleeping_gpio_gate_ops;
+	else
+		ops = &clk_gpio_gate_ops;
+
+	return clk_register_gpio(dev, num_parents, gpiod, ops);
+}
+
+static struct clk_hw *clk_hw_register_gpio_mux(struct device *dev,
+					       struct gpio_desc *gpiod)
+{
+	return clk_register_gpio(dev, 2, gpiod, &clk_gpio_mux_ops);
+}
+
+static int gpio_clk_driver_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node;
+	const char *gpio_name;
+	unsigned int num_parents;
+	struct gpio_desc *gpiod;
+	struct clk_hw *hw;
+	bool is_mux;
+
+	is_mux = of_device_is_compatible(node, "gpio-mux-clock");
+
+	num_parents = of_clk_get_parent_count(node);
+	if (is_mux && num_parents != 2) {
+		dev_err(dev, "mux-clock must have 2 parents\n");
+		return -EINVAL;
+	}
+
+	gpio_name = is_mux ? "select" : "enable";
+	gpiod = devm_gpiod_get(dev, gpio_name, GPIOD_OUT_LOW);
+	if (IS_ERR(gpiod))
+		return dev_err_probe(dev, PTR_ERR(gpiod),
+				     "Can't get '%s' named GPIO property\n", gpio_name);
+
+	if (is_mux)
+		hw = clk_hw_register_gpio_mux(dev, gpiod);
+	else
+		hw = clk_hw_register_gpio_gate(dev, num_parents, gpiod);
+	if (IS_ERR(hw))
+		return PTR_ERR(hw);
+
+	return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw);
+}
+
+static const struct of_device_id gpio_clk_match_table[] = {
+	{ .compatible = "gpio-mux-clock" },
+	{ .compatible = "gpio-gate-clock" },
+	{ }
+};
+
+static struct platform_driver gpio_clk_driver = {
+	.probe		= gpio_clk_driver_probe,
+	.driver		= {
+		.name	= "gpio-clk",
+		.of_match_table = gpio_clk_match_table,
+	},
+};
+builtin_platform_driver(gpio_clk_driver);
+
+/**
+ * DOC: gated fixed clock, controlled with a gpio output and a regulator
+ * Traits of this clock:
+ * prepare - clk_prepare and clk_unprepare are function & control regulator
+ *           optionally a gpio that can sleep
+ * enable - clk_enable and clk_disable are functional & control gpio
+ * rate - rate is fixed and set on clock registration
+ * parent - fixed clock is a root clock and has no parent
+ */
+
+/**
+ * struct clk_gated_fixed - Gateable fixed rate clock
+ * @clk_gpio:	instance of clk_gpio for gate-gpio
+ * @supply:	supply regulator
+ * @rate:	fixed rate
+ */
+struct clk_gated_fixed {
+	struct clk_gpio clk_gpio;
+	struct regulator *supply;
+	unsigned long rate;
+};
+
+#define to_clk_gated_fixed(_clk_gpio) container_of(_clk_gpio, struct clk_gated_fixed, clk_gpio)
+
+static unsigned long clk_gated_fixed_recalc_rate(struct clk_hw *hw,
+						 unsigned long parent_rate)
+{
+	return to_clk_gated_fixed(to_clk_gpio(hw))->rate;
+}
+
+static int clk_gated_fixed_prepare(struct clk_hw *hw)
+{
+	struct clk_gated_fixed *clk = to_clk_gated_fixed(to_clk_gpio(hw));
+
+	if (!clk->supply)
+		return 0;
+
+	return regulator_enable(clk->supply);
+}
+
+static void clk_gated_fixed_unprepare(struct clk_hw *hw)
+{
+	struct clk_gated_fixed *clk = to_clk_gated_fixed(to_clk_gpio(hw));
+
+	if (!clk->supply)
+		return;
+
+	regulator_disable(clk->supply);
+}
+
+static int clk_gated_fixed_is_prepared(struct clk_hw *hw)
+{
+	struct clk_gated_fixed *clk = to_clk_gated_fixed(to_clk_gpio(hw));
+
+	if (!clk->supply)
+		return true;
+
+	return regulator_is_enabled(clk->supply);
+}
+
+/*
+ * Fixed gated clock with non-sleeping gpio.
+ *
+ * Prepare operation turns on the supply regulator
+ * and the enable operation switches the enable-gpio.
+ */
+static const struct clk_ops clk_gated_fixed_ops = {
+	.prepare = clk_gated_fixed_prepare,
+	.unprepare = clk_gated_fixed_unprepare,
+	.is_prepared = clk_gated_fixed_is_prepared,
+	.enable = clk_gpio_gate_enable,
+	.disable = clk_gpio_gate_disable,
+	.is_enabled = clk_gpio_gate_is_enabled,
+	.recalc_rate = clk_gated_fixed_recalc_rate,
+};
+
+static int clk_sleeping_gated_fixed_prepare(struct clk_hw *hw)
+{
+	int ret;
+
+	ret = clk_gated_fixed_prepare(hw);
+	if (ret)
+		return ret;
+
+	ret = clk_sleeping_gpio_gate_prepare(hw);
+	if (ret)
+		clk_gated_fixed_unprepare(hw);
+
+	return ret;
+}
+
+static void clk_sleeping_gated_fixed_unprepare(struct clk_hw *hw)
+{
+	clk_gated_fixed_unprepare(hw);
+	clk_sleeping_gpio_gate_unprepare(hw);
+}
+
+/*
+ * Fixed gated clock with non-sleeping gpio.
+ *
+ * Enabling the supply regulator and switching the enable-gpio happens
+ * both in the prepare step.
+ * is_prepared only needs to check the gpio state, as toggling the
+ * gpio is the last step when preparing.
+ */
+static const struct clk_ops clk_sleeping_gated_fixed_ops = {
+	.prepare = clk_sleeping_gated_fixed_prepare,
+	.unprepare = clk_sleeping_gated_fixed_unprepare,
+	.is_prepared = clk_sleeping_gpio_gate_is_prepared,
+	.recalc_rate = clk_gated_fixed_recalc_rate,
+};
+
+static int clk_gated_fixed_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct clk_gated_fixed *clk;
+	const struct clk_ops *ops;
+	const char *clk_name;
+	u32 rate;
+	int ret;
+
+	clk = devm_kzalloc(dev, sizeof(*clk), GFP_KERNEL);
+	if (!clk)
+		return -ENOMEM;
+
+	ret = device_property_read_u32(dev, "clock-frequency", &rate);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to get clock-frequency\n");
+	clk->rate = rate;
+
+	ret = device_property_read_string(dev, "clock-output-names", &clk_name);
+	if (ret)
+		clk_name = fwnode_get_name(dev->fwnode);
+
+	clk->supply = devm_regulator_get_optional(dev, "vdd");
+	if (IS_ERR(clk->supply)) {
+		if (PTR_ERR(clk->supply) != -ENODEV)
+			return dev_err_probe(dev, PTR_ERR(clk->supply),
+					     "Failed to get regulator\n");
+		clk->supply = NULL;
+	}
+
+	clk->clk_gpio.gpiod = devm_gpiod_get_optional(dev, "enable",
+						      GPIOD_OUT_LOW);
+	if (IS_ERR(clk->clk_gpio.gpiod))
+		return dev_err_probe(dev, PTR_ERR(clk->clk_gpio.gpiod),
+				     "Failed to get gpio\n");
+
+	if (gpiod_cansleep(clk->clk_gpio.gpiod))
+		ops = &clk_sleeping_gated_fixed_ops;
+	else
+		ops = &clk_gated_fixed_ops;
+
+	clk->clk_gpio.hw.init = CLK_HW_INIT_NO_PARENT(clk_name, ops, 0);
+
+	/* register the clock */
+	ret = devm_clk_hw_register(dev, &clk->clk_gpio.hw);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to register clock\n");
+
+	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
+					  &clk->clk_gpio.hw);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to register clock provider\n");
+
+	return 0;
+}
+
+static const struct of_device_id gated_fixed_clk_match_table[] = {
+	{ .compatible = "gated-fixed-clock" },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver gated_fixed_clk_driver = {
+	.probe		= clk_gated_fixed_probe,
+	.driver		= {
+		.name	= "gated-fixed-clk",
+		.of_match_table = gated_fixed_clk_match_table,
+	},
+};
+builtin_platform_driver(gated_fixed_clk_driver);