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, 347 insertions, 0 deletions

diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
new file mode 100644
index 000000000..7d5079fd1
--- /dev/null
+++ b/drivers/cpufreq/cpufreq-dt.c
@@ -0,0 +1,347 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2012 Freescale Semiconductor, Inc.
+ *
+ * Copyright (C) 2014 Linaro.
+ * Viresh Kumar <viresh.kumar@linaro.org>
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/clk.h>
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/cpumask.h>
+#include <linux/err.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pm_opp.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/thermal.h>
+
+#include "cpufreq-dt.h"
+
+struct private_data {
+	struct list_head node;
+
+	cpumask_var_t cpus;
+	struct device *cpu_dev;
+	struct cpufreq_frequency_table *freq_table;
+	bool have_static_opps;
+	int opp_token;
+};
+
+static LIST_HEAD(priv_list);
+
+static struct private_data *cpufreq_dt_find_data(int cpu)
+{
+	struct private_data *priv;
+
+	list_for_each_entry(priv, &priv_list, node) {
+		if (cpumask_test_cpu(cpu, priv->cpus))
+			return priv;
+	}
+
+	return NULL;
+}
+
+static int set_target(struct cpufreq_policy *policy, unsigned int index)
+{
+	struct private_data *priv = policy->driver_data;
+	unsigned long freq = policy->freq_table[index].frequency;
+
+	return dev_pm_opp_set_rate(priv->cpu_dev, freq * 1000);
+}
+
+/*
+ * An earlier version of opp-v1 bindings used to name the regulator
+ * "cpu0-supply", we still need to handle that for backwards compatibility.
+ */
+static const char *find_supply_name(struct device *dev)
+{
+	struct device_node *np __free(device_node) = of_node_get(dev->of_node);
+	int cpu = dev->id;
+
+	/* This must be valid for sure */
+	if (WARN_ON(!np))
+		return NULL;
+
+	/* Try "cpu0" for older DTs */
+	if (!cpu && of_property_present(np, "cpu0-supply"))
+		return "cpu0";
+
+	if (of_property_present(np, "cpu-supply"))
+		return "cpu";
+
+	dev_dbg(dev, "no regulator for cpu%d\n", cpu);
+	return NULL;
+}
+
+static int cpufreq_init(struct cpufreq_policy *policy)
+{
+	struct private_data *priv;
+	struct device *cpu_dev;
+	struct clk *cpu_clk;
+	unsigned int transition_latency;
+	int ret;
+
+	priv = cpufreq_dt_find_data(policy->cpu);
+	if (!priv) {
+		pr_err("failed to find data for cpu%d\n", policy->cpu);
+		return -ENODEV;
+	}
+	cpu_dev = priv->cpu_dev;
+
+	cpu_clk = clk_get(cpu_dev, NULL);
+	if (IS_ERR(cpu_clk)) {
+		ret = PTR_ERR(cpu_clk);
+		dev_err(cpu_dev, "%s: failed to get clk: %d\n", __func__, ret);
+		return ret;
+	}
+
+	transition_latency = dev_pm_opp_get_max_transition_latency(cpu_dev);
+	if (!transition_latency)
+		transition_latency = CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS;
+
+	cpumask_copy(policy->cpus, priv->cpus);
+	policy->driver_data = priv;
+	policy->clk = cpu_clk;
+	policy->freq_table = priv->freq_table;
+	policy->suspend_freq = dev_pm_opp_get_suspend_opp_freq(cpu_dev) / 1000;
+	policy->cpuinfo.transition_latency = transition_latency;
+	policy->dvfs_possible_from_any_cpu = true;
+
+	return 0;
+}
+
+static int cpufreq_online(struct cpufreq_policy *policy)
+{
+	/* We did light-weight tear down earlier, nothing to do here */
+	return 0;
+}
+
+static int cpufreq_offline(struct cpufreq_policy *policy)
+{
+	/*
+	 * Preserve policy->driver_data and don't free resources on light-weight
+	 * tear down.
+	 */
+	return 0;
+}
+
+static void cpufreq_exit(struct cpufreq_policy *policy)
+{
+	clk_put(policy->clk);
+}
+
+static struct cpufreq_driver dt_cpufreq_driver = {
+	.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK |
+		 CPUFREQ_IS_COOLING_DEV,
+	.verify = cpufreq_generic_frequency_table_verify,
+	.target_index = set_target,
+	.get = cpufreq_generic_get,
+	.init = cpufreq_init,
+	.exit = cpufreq_exit,
+	.online = cpufreq_online,
+	.offline = cpufreq_offline,
+	.register_em = cpufreq_register_em_with_opp,
+	.name = "cpufreq-dt",
+	.set_boost = cpufreq_boost_set_sw,
+	.suspend = cpufreq_generic_suspend,
+};
+
+static int dt_cpufreq_early_init(struct device *dev, int cpu)
+{
+	struct private_data *priv;
+	struct device *cpu_dev;
+	bool fallback = false;
+	const char *reg_name[] = { NULL, NULL };
+	int ret;
+
+	/* Check if this CPU is already covered by some other policy */
+	if (cpufreq_dt_find_data(cpu))
+		return 0;
+
+	cpu_dev = get_cpu_device(cpu);
+	if (!cpu_dev)
+		return -EPROBE_DEFER;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	if (!zalloc_cpumask_var(&priv->cpus, GFP_KERNEL))
+		return -ENOMEM;
+
+	cpumask_set_cpu(cpu, priv->cpus);
+	priv->cpu_dev = cpu_dev;
+
+	/*
+	 * OPP layer will be taking care of regulators now, but it needs to know
+	 * the name of the regulator first.
+	 */
+	reg_name[0] = find_supply_name(cpu_dev);
+	if (reg_name[0]) {
+		priv->opp_token = dev_pm_opp_set_regulators(cpu_dev, reg_name);
+		if (priv->opp_token < 0) {
+			ret = dev_err_probe(cpu_dev, priv->opp_token,
+					    "failed to set regulators\n");
+			goto free_cpumask;
+		}
+	}
+
+	/* Get OPP-sharing information from "operating-points-v2" bindings */
+	ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->cpus);
+	if (ret) {
+		if (ret != -ENOENT)
+			goto out;
+
+		/*
+		 * operating-points-v2 not supported, fallback to all CPUs share
+		 * OPP for backward compatibility if the platform hasn't set
+		 * sharing CPUs.
+		 */
+		if (dev_pm_opp_get_sharing_cpus(cpu_dev, priv->cpus))
+			fallback = true;
+	}
+
+	/*
+	 * Initialize OPP tables for all priv->cpus. They will be shared by
+	 * all CPUs which have marked their CPUs shared with OPP bindings.
+	 *
+	 * For platforms not using operating-points-v2 bindings, we do this
+	 * before updating priv->cpus. Otherwise, we will end up creating
+	 * duplicate OPPs for the CPUs.
+	 *
+	 * OPPs might be populated at runtime, don't fail for error here unless
+	 * it is -EPROBE_DEFER.
+	 */
+	ret = dev_pm_opp_of_cpumask_add_table(priv->cpus);
+	if (!ret) {
+		priv->have_static_opps = true;
+	} else if (ret == -EPROBE_DEFER) {
+		goto out;
+	}
+
+	/*
+	 * The OPP table must be initialized, statically or dynamically, by this
+	 * point.
+	 */
+	ret = dev_pm_opp_get_opp_count(cpu_dev);
+	if (ret <= 0) {
+		dev_err(cpu_dev, "OPP table can't be empty\n");
+		ret = -ENODEV;
+		goto out;
+	}
+
+	if (fallback) {
+		cpumask_setall(priv->cpus);
+		ret = dev_pm_opp_set_sharing_cpus(cpu_dev, priv->cpus);
+		if (ret)
+			dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
+				__func__, ret);
+	}
+
+	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &priv->freq_table);
+	if (ret) {
+		dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
+		goto out;
+	}
+
+	list_add(&priv->node, &priv_list);
+	return 0;
+
+out:
+	if (priv->have_static_opps)
+		dev_pm_opp_of_cpumask_remove_table(priv->cpus);
+	dev_pm_opp_put_regulators(priv->opp_token);
+free_cpumask:
+	free_cpumask_var(priv->cpus);
+	return ret;
+}
+
+static void dt_cpufreq_release(void)
+{
+	struct private_data *priv, *tmp;
+
+	list_for_each_entry_safe(priv, tmp, &priv_list, node) {
+		dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &priv->freq_table);
+		if (priv->have_static_opps)
+			dev_pm_opp_of_cpumask_remove_table(priv->cpus);
+		dev_pm_opp_put_regulators(priv->opp_token);
+		free_cpumask_var(priv->cpus);
+		list_del(&priv->node);
+	}
+}
+
+static int dt_cpufreq_probe(struct platform_device *pdev)
+{
+	struct cpufreq_dt_platform_data *data = dev_get_platdata(&pdev->dev);
+	int ret, cpu;
+
+	/* Request resources early so we can return in case of -EPROBE_DEFER */
+	for_each_present_cpu(cpu) {
+		ret = dt_cpufreq_early_init(&pdev->dev, cpu);
+		if (ret)
+			goto err;
+	}
+
+	if (data) {
+		if (data->have_governor_per_policy)
+			dt_cpufreq_driver.flags |= CPUFREQ_HAVE_GOVERNOR_PER_POLICY;
+
+		dt_cpufreq_driver.resume = data->resume;
+		if (data->suspend)
+			dt_cpufreq_driver.suspend = data->suspend;
+		if (data->get_intermediate) {
+			dt_cpufreq_driver.target_intermediate = data->target_intermediate;
+			dt_cpufreq_driver.get_intermediate = data->get_intermediate;
+		}
+	}
+
+	ret = cpufreq_register_driver(&dt_cpufreq_driver);
+	if (ret) {
+		dev_err(&pdev->dev, "failed register driver: %d\n", ret);
+		goto err;
+	}
+
+	return 0;
+err:
+	dt_cpufreq_release();
+	return ret;
+}
+
+static void dt_cpufreq_remove(struct platform_device *pdev)
+{
+	cpufreq_unregister_driver(&dt_cpufreq_driver);
+	dt_cpufreq_release();
+}
+
+static struct platform_driver dt_cpufreq_platdrv = {
+	.driver = {
+		.name	= "cpufreq-dt",
+	},
+	.probe		= dt_cpufreq_probe,
+	.remove		= dt_cpufreq_remove,
+};
+module_platform_driver(dt_cpufreq_platdrv);
+
+struct platform_device *cpufreq_dt_pdev_register(struct device *dev)
+{
+	struct platform_device_info cpufreq_dt_devinfo = {};
+
+	cpufreq_dt_devinfo.name = "cpufreq-dt";
+	cpufreq_dt_devinfo.parent = dev;
+
+	return platform_device_register_full(&cpufreq_dt_devinfo);
+}
+EXPORT_SYMBOL_GPL(cpufreq_dt_pdev_register);
+
+MODULE_ALIAS("platform:cpufreq-dt");
+MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
+MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
+MODULE_DESCRIPTION("Generic cpufreq driver");
+MODULE_LICENSE("GPL");