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, 238 insertions, 0 deletions

diff --git a/drivers/clk/clk-fixed-rate.c b/drivers/clk/clk-fixed-rate.c
new file mode 100644
index 000000000..5dcb1bccf
--- /dev/null
+++ b/drivers/clk/clk-fixed-rate.c
@@ -0,0 +1,238 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
+ * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
+ *
+ * Fixed rate clock implementation
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+/*
+ * DOC: basic fixed-rate clock that cannot gate
+ *
+ * Traits of this clock:
+ * prepare - clk_(un)prepare only ensures parents are prepared
+ * enable - clk_enable only ensures parents are enabled
+ * rate - rate is always a fixed value.  No clk_set_rate support
+ * parent - fixed parent.  No clk_set_parent support
+ */
+
+#define to_clk_fixed_rate(_hw) container_of(_hw, struct clk_fixed_rate, hw)
+
+static unsigned long clk_fixed_rate_recalc_rate(struct clk_hw *hw,
+		unsigned long parent_rate)
+{
+	return to_clk_fixed_rate(hw)->fixed_rate;
+}
+
+static unsigned long clk_fixed_rate_recalc_accuracy(struct clk_hw *hw,
+		unsigned long parent_accuracy)
+{
+	struct clk_fixed_rate *fixed = to_clk_fixed_rate(hw);
+
+	if (fixed->flags & CLK_FIXED_RATE_PARENT_ACCURACY)
+		return parent_accuracy;
+
+	return fixed->fixed_accuracy;
+}
+
+const struct clk_ops clk_fixed_rate_ops = {
+	.recalc_rate = clk_fixed_rate_recalc_rate,
+	.recalc_accuracy = clk_fixed_rate_recalc_accuracy,
+};
+EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);
+
+static void devm_clk_hw_register_fixed_rate_release(struct device *dev, void *res)
+{
+	struct clk_fixed_rate *fix = res;
+
+	/*
+	 * We can not use clk_hw_unregister_fixed_rate, since it will kfree()
+	 * the hw, resulting in double free. Just unregister the hw and let
+	 * devres code kfree() it.
+	 */
+	clk_hw_unregister(&fix->hw);
+}
+
+struct clk_hw *__clk_hw_register_fixed_rate(struct device *dev,
+		struct device_node *np, const char *name,
+		const char *parent_name, const struct clk_hw *parent_hw,
+		const struct clk_parent_data *parent_data, unsigned long flags,
+		unsigned long fixed_rate, unsigned long fixed_accuracy,
+		unsigned long clk_fixed_flags, bool devm)
+{
+	struct clk_fixed_rate *fixed;
+	struct clk_hw *hw;
+	struct clk_init_data init = {};
+	int ret = -EINVAL;
+
+	/* allocate fixed-rate clock */
+	if (devm)
+		fixed = devres_alloc(devm_clk_hw_register_fixed_rate_release,
+				     sizeof(*fixed), GFP_KERNEL);
+	else
+		fixed = kzalloc_obj(*fixed);
+	if (!fixed)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &clk_fixed_rate_ops;
+	init.flags = flags;
+	init.parent_names = parent_name ? &parent_name : NULL;
+	init.parent_hws = parent_hw ? &parent_hw : NULL;
+	init.parent_data = parent_data;
+	if (parent_name || parent_hw || parent_data)
+		init.num_parents = 1;
+	else
+		init.num_parents = 0;
+
+	/* struct clk_fixed_rate assignments */
+	fixed->flags = clk_fixed_flags;
+	fixed->fixed_rate = fixed_rate;
+	fixed->fixed_accuracy = fixed_accuracy;
+	fixed->hw.init = &init;
+
+	/* register the clock */
+	hw = &fixed->hw;
+	if (dev || !np)
+		ret = clk_hw_register(dev, hw);
+	else
+		ret = of_clk_hw_register(np, hw);
+	if (ret) {
+		if (devm)
+			devres_free(fixed);
+		else
+			kfree(fixed);
+		hw = ERR_PTR(ret);
+	} else if (devm)
+		devres_add(dev, fixed);
+
+	return hw;
+}
+EXPORT_SYMBOL_GPL(__clk_hw_register_fixed_rate);
+
+struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
+		const char *parent_name, unsigned long flags,
+		unsigned long fixed_rate)
+{
+	struct clk_hw *hw;
+
+	hw = clk_hw_register_fixed_rate_with_accuracy(dev, name, parent_name,
+						      flags, fixed_rate, 0);
+	if (IS_ERR(hw))
+		return ERR_CAST(hw);
+	return hw->clk;
+}
+EXPORT_SYMBOL_GPL(clk_register_fixed_rate);
+
+void clk_unregister_fixed_rate(struct clk *clk)
+{
+	struct clk_hw *hw;
+
+	hw = __clk_get_hw(clk);
+	if (!hw)
+		return;
+
+	clk_unregister(clk);
+	kfree(to_clk_fixed_rate(hw));
+}
+EXPORT_SYMBOL_GPL(clk_unregister_fixed_rate);
+
+void clk_hw_unregister_fixed_rate(struct clk_hw *hw)
+{
+	struct clk_fixed_rate *fixed;
+
+	fixed = to_clk_fixed_rate(hw);
+
+	clk_hw_unregister(hw);
+	kfree(fixed);
+}
+EXPORT_SYMBOL_GPL(clk_hw_unregister_fixed_rate);
+
+#ifdef CONFIG_OF
+static struct clk_hw *_of_fixed_clk_setup(struct device_node *node)
+{
+	struct clk_hw *hw;
+	const char *clk_name = node->name;
+	u32 rate;
+	u32 accuracy = 0;
+	int ret;
+
+	if (of_property_read_u32(node, "clock-frequency", &rate))
+		return ERR_PTR(-EIO);
+
+	of_property_read_u32(node, "clock-accuracy", &accuracy);
+
+	of_property_read_string(node, "clock-output-names", &clk_name);
+
+	hw = clk_hw_register_fixed_rate_with_accuracy(NULL, clk_name, NULL,
+						    0, rate, accuracy);
+	if (IS_ERR(hw))
+		return hw;
+
+	ret = of_clk_add_hw_provider(node, of_clk_hw_simple_get, hw);
+	if (ret) {
+		clk_hw_unregister_fixed_rate(hw);
+		return ERR_PTR(ret);
+	}
+
+	return hw;
+}
+
+/**
+ * of_fixed_clk_setup() - Setup function for simple fixed rate clock
+ * @node:	device node for the clock
+ */
+void __init of_fixed_clk_setup(struct device_node *node)
+{
+	_of_fixed_clk_setup(node);
+}
+CLK_OF_DECLARE(fixed_clk, "fixed-clock", of_fixed_clk_setup);
+
+static void of_fixed_clk_remove(struct platform_device *pdev)
+{
+	struct clk_hw *hw = platform_get_drvdata(pdev);
+
+	of_clk_del_provider(pdev->dev.of_node);
+	clk_hw_unregister_fixed_rate(hw);
+}
+
+static int of_fixed_clk_probe(struct platform_device *pdev)
+{
+	struct clk_hw *hw;
+
+	/*
+	 * This function is not executed when of_fixed_clk_setup
+	 * succeeded.
+	 */
+	hw = _of_fixed_clk_setup(pdev->dev.of_node);
+	if (IS_ERR(hw))
+		return PTR_ERR(hw);
+
+	platform_set_drvdata(pdev, hw);
+
+	return 0;
+}
+
+static const struct of_device_id of_fixed_clk_ids[] = {
+	{ .compatible = "fixed-clock" },
+	{ }
+};
+
+static struct platform_driver of_fixed_clk_driver = {
+	.driver = {
+		.name = "of_fixed_clk",
+		.of_match_table = of_fixed_clk_ids,
+	},
+	.probe = of_fixed_clk_probe,
+	.remove = of_fixed_clk_remove,
+};
+builtin_platform_driver(of_fixed_clk_driver);
+#endif