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, 155 insertions, 0 deletions

diff --git a/drivers/cpufreq/davinci-cpufreq.c b/drivers/cpufreq/davinci-cpufreq.c
new file mode 100644
index 000000000..2c277eb37
--- /dev/null
+++ b/drivers/cpufreq/davinci-cpufreq.c
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * CPU frequency scaling for DaVinci
+ *
+ * Copyright (C) 2009 Texas Instruments Incorporated - https://www.ti.com/
+ *
+ * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
+ *
+ *  Copyright (C) 2005 Nokia Corporation
+ *  Written by Tony Lindgren <tony@atomide.com>
+ *
+ *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
+ *
+ * Copyright (C) 2007-2008 Texas Instruments, Inc.
+ * Updated to support OMAP3
+ * Rajendra Nayak <rnayak@ti.com>
+ */
+#include <linux/types.h>
+#include <linux/cpufreq.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/platform_data/davinci-cpufreq.h>
+#include <linux/platform_device.h>
+#include <linux/export.h>
+
+struct davinci_cpufreq {
+	struct device *dev;
+	struct clk *armclk;
+	struct clk *asyncclk;
+	unsigned long asyncrate;
+};
+static struct davinci_cpufreq cpufreq;
+
+static int davinci_target(struct cpufreq_policy *policy, unsigned int idx)
+{
+	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
+	struct clk *armclk = cpufreq.armclk;
+	unsigned int old_freq, new_freq;
+	int ret = 0;
+
+	old_freq = policy->cur;
+	new_freq = pdata->freq_table[idx].frequency;
+
+	/* if moving to higher frequency, up the voltage beforehand */
+	if (pdata->set_voltage && new_freq > old_freq) {
+		ret = pdata->set_voltage(idx);
+		if (ret)
+			return ret;
+	}
+
+	ret = clk_set_rate(armclk, new_freq * 1000);
+	if (ret)
+		return ret;
+
+	if (cpufreq.asyncclk) {
+		ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
+		if (ret)
+			return ret;
+	}
+
+	/* if moving to lower freq, lower the voltage after lowering freq */
+	if (pdata->set_voltage && new_freq < old_freq)
+		pdata->set_voltage(idx);
+
+	return 0;
+}
+
+static int davinci_cpu_init(struct cpufreq_policy *policy)
+{
+	int result = 0;
+	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
+	struct cpufreq_frequency_table *freq_table = pdata->freq_table;
+
+	if (policy->cpu != 0)
+		return -EINVAL;
+
+	/* Finish platform specific initialization */
+	if (pdata->init) {
+		result = pdata->init();
+		if (result)
+			return result;
+	}
+
+	policy->clk = cpufreq.armclk;
+
+	/*
+	 * Time measurement across the target() function yields ~1500-1800us
+	 * time taken with no drivers on notification list.
+	 * Setting the latency to 2000 us to accommodate addition of drivers
+	 * to pre/post change notification list.
+	 */
+	cpufreq_generic_init(policy, freq_table, 2000 * 1000);
+	return 0;
+}
+
+static struct cpufreq_driver davinci_driver = {
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.verify		= cpufreq_generic_frequency_table_verify,
+	.target_index	= davinci_target,
+	.get		= cpufreq_generic_get,
+	.init		= davinci_cpu_init,
+	.name		= "davinci",
+};
+
+static int __init davinci_cpufreq_probe(struct platform_device *pdev)
+{
+	struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
+	struct clk *asyncclk;
+
+	if (!pdata)
+		return -EINVAL;
+	if (!pdata->freq_table)
+		return -EINVAL;
+
+	cpufreq.dev = &pdev->dev;
+
+	cpufreq.armclk = clk_get(NULL, "arm");
+	if (IS_ERR(cpufreq.armclk)) {
+		dev_err(cpufreq.dev, "Unable to get ARM clock\n");
+		return PTR_ERR(cpufreq.armclk);
+	}
+
+	asyncclk = clk_get(cpufreq.dev, "async");
+	if (!IS_ERR(asyncclk)) {
+		cpufreq.asyncclk = asyncclk;
+		cpufreq.asyncrate = clk_get_rate(asyncclk);
+	}
+
+	return cpufreq_register_driver(&davinci_driver);
+}
+
+static void __exit davinci_cpufreq_remove(struct platform_device *pdev)
+{
+	cpufreq_unregister_driver(&davinci_driver);
+
+	clk_put(cpufreq.armclk);
+
+	if (cpufreq.asyncclk)
+		clk_put(cpufreq.asyncclk);
+}
+
+static struct platform_driver davinci_cpufreq_driver = {
+	.driver = {
+		.name	 = "cpufreq-davinci",
+	},
+	.remove = __exit_p(davinci_cpufreq_remove),
+};
+
+int __init davinci_cpufreq_init(void)
+{
+	return platform_driver_probe(&davinci_cpufreq_driver,
+							davinci_cpufreq_probe);
+}
+