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, 168 insertions, 0 deletions

diff --git a/drivers/cpufreq/sh-cpufreq.c b/drivers/cpufreq/sh-cpufreq.c
new file mode 100644
index 000000000..3c99d7009
--- /dev/null
+++ b/drivers/cpufreq/sh-cpufreq.c
@@ -0,0 +1,168 @@
+/*
+ * cpufreq driver for the SuperH processors.
+ *
+ * Copyright (C) 2002 - 2012 Paul Mundt
+ * Copyright (C) 2002 M. R. Brown
+ *
+ * Clock framework bits from arch/avr32/mach-at32ap/cpufreq.c
+ *
+ *   Copyright (C) 2004-2007 Atmel Corporation
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#define pr_fmt(fmt) "cpufreq: " fmt
+
+#include <linux/types.h>
+#include <linux/cpufreq.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/cpumask.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+#include <linux/clk.h>
+#include <linux/percpu.h>
+#include <linux/sh_clk.h>
+
+static DEFINE_PER_CPU(struct clk, sh_cpuclk);
+
+struct cpufreq_target {
+	struct cpufreq_policy	*policy;
+	unsigned int		freq;
+};
+
+static unsigned int sh_cpufreq_get(unsigned int cpu)
+{
+	return (clk_get_rate(&per_cpu(sh_cpuclk, cpu)) + 500) / 1000;
+}
+
+static long __sh_cpufreq_target(void *arg)
+{
+	struct cpufreq_target *target = arg;
+	struct cpufreq_policy *policy = target->policy;
+	int cpu = policy->cpu;
+	struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
+	struct cpufreq_freqs freqs;
+	struct device *dev;
+	long freq;
+
+	if (smp_processor_id() != cpu)
+		return -ENODEV;
+
+	dev = get_cpu_device(cpu);
+
+	/* Convert target_freq from kHz to Hz */
+	freq = clk_round_rate(cpuclk, target->freq * 1000);
+
+	if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
+		return -EINVAL;
+
+	dev_dbg(dev, "requested frequency %u Hz\n", target->freq * 1000);
+
+	freqs.old	= sh_cpufreq_get(cpu);
+	freqs.new	= (freq + 500) / 1000;
+	freqs.flags	= 0;
+
+	cpufreq_freq_transition_begin(target->policy, &freqs);
+	clk_set_rate(cpuclk, freq);
+	cpufreq_freq_transition_end(target->policy, &freqs, 0);
+
+	dev_dbg(dev, "set frequency %lu Hz\n", freq);
+	return 0;
+}
+
+/*
+ * Here we notify other drivers of the proposed change and the final change.
+ */
+static int sh_cpufreq_target(struct cpufreq_policy *policy,
+			     unsigned int target_freq,
+			     unsigned int relation)
+{
+	struct cpufreq_target data = { .policy = policy, .freq = target_freq };
+
+	return work_on_cpu(policy->cpu, __sh_cpufreq_target, &data);
+}
+
+static int sh_cpufreq_verify(struct cpufreq_policy_data *policy)
+{
+	struct clk *cpuclk = &per_cpu(sh_cpuclk, policy->cpu);
+
+	if (policy->freq_table)
+		return cpufreq_frequency_table_verify(policy);
+
+	cpufreq_verify_within_cpu_limits(policy);
+
+	policy->min = (clk_round_rate(cpuclk, 1) + 500) / 1000;
+	policy->max = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
+
+	cpufreq_verify_within_cpu_limits(policy);
+	return 0;
+}
+
+static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
+{
+	unsigned int cpu = policy->cpu;
+	struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
+	struct cpufreq_frequency_table *freq_table;
+	struct device *dev;
+
+	dev = get_cpu_device(cpu);
+
+	cpuclk = clk_get(dev, "cpu_clk");
+	if (IS_ERR(cpuclk)) {
+		dev_err(dev, "couldn't get CPU clk\n");
+		return PTR_ERR(cpuclk);
+	}
+
+	freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
+	if (freq_table) {
+		policy->freq_table = freq_table;
+	} else {
+		dev_notice(dev, "no frequency table found, falling back "
+			   "to rate rounding.\n");
+
+		policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
+		policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
+	}
+
+	return 0;
+}
+
+static void sh_cpufreq_cpu_exit(struct cpufreq_policy *policy)
+{
+	unsigned int cpu = policy->cpu;
+	struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
+
+	clk_put(cpuclk);
+}
+
+static struct cpufreq_driver sh_cpufreq_driver = {
+	.name		= "sh",
+	.flags		= CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
+	.get		= sh_cpufreq_get,
+	.target		= sh_cpufreq_target,
+	.verify		= sh_cpufreq_verify,
+	.init		= sh_cpufreq_cpu_init,
+	.exit		= sh_cpufreq_cpu_exit,
+};
+
+static int __init sh_cpufreq_module_init(void)
+{
+	pr_notice("SuperH CPU frequency driver.\n");
+	return cpufreq_register_driver(&sh_cpufreq_driver);
+}
+
+static void __exit sh_cpufreq_module_exit(void)
+{
+	cpufreq_unregister_driver(&sh_cpufreq_driver);
+}
+
+module_init(sh_cpufreq_module_init);
+module_exit(sh_cpufreq_module_exit);
+
+MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
+MODULE_DESCRIPTION("cpufreq driver for SuperH");
+MODULE_LICENSE("GPL");