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, 183 insertions, 0 deletions

diff --git a/drivers/clocksource/ingenic-ost.c b/drivers/clocksource/ingenic-ost.c
new file mode 100644
index 000000000..e0ec33307
--- /dev/null
+++ b/drivers/clocksource/ingenic-ost.c
@@ -0,0 +1,183 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * JZ47xx SoCs TCU Operating System Timer driver
+ *
+ * Copyright (C) 2016 Maarten ter Huurne <maarten@treewalker.org>
+ * Copyright (C) 2020 Paul Cercueil <paul@crapouillou.net>
+ */
+
+#include <linux/clk.h>
+#include <linux/clocksource.h>
+#include <linux/mfd/ingenic-tcu.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/regmap.h>
+#include <linux/sched_clock.h>
+
+#define TCU_OST_TCSR_MASK	0xffc0
+#define TCU_OST_TCSR_CNT_MD	BIT(15)
+
+#define TCU_OST_CHANNEL		15
+
+/*
+ * The TCU_REG_OST_CNT{L,R} from <linux/mfd/ingenic-tcu.h> are only for the
+ * regmap; these are for use with the __iomem pointer.
+ */
+#define OST_REG_CNTL		0x4
+#define OST_REG_CNTH		0x8
+
+struct ingenic_ost_soc_info {
+	bool is64bit;
+};
+
+struct ingenic_ost {
+	void __iomem *regs;
+	struct clk *clk;
+
+	struct clocksource cs;
+};
+
+static struct ingenic_ost *ingenic_ost;
+
+static u64 notrace ingenic_ost_read_cntl(void)
+{
+	/* Read using __iomem pointer instead of regmap to avoid locking */
+	return readl(ingenic_ost->regs + OST_REG_CNTL);
+}
+
+static u64 notrace ingenic_ost_read_cnth(void)
+{
+	/* Read using __iomem pointer instead of regmap to avoid locking */
+	return readl(ingenic_ost->regs + OST_REG_CNTH);
+}
+
+static u64 notrace ingenic_ost_clocksource_readl(struct clocksource *cs)
+{
+	return ingenic_ost_read_cntl();
+}
+
+static u64 notrace ingenic_ost_clocksource_readh(struct clocksource *cs)
+{
+	return ingenic_ost_read_cnth();
+}
+
+static int __init ingenic_ost_probe(struct platform_device *pdev)
+{
+	const struct ingenic_ost_soc_info *soc_info;
+	struct device *dev = &pdev->dev;
+	struct ingenic_ost *ost;
+	struct clocksource *cs;
+	struct regmap *map;
+	unsigned long rate;
+	int err;
+
+	soc_info = device_get_match_data(dev);
+	if (!soc_info)
+		return -EINVAL;
+
+	ost = devm_kzalloc(dev, sizeof(*ost), GFP_KERNEL);
+	if (!ost)
+		return -ENOMEM;
+
+	ingenic_ost = ost;
+
+	ost->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(ost->regs))
+		return PTR_ERR(ost->regs);
+
+	map = device_node_to_regmap(dev->parent->of_node);
+	if (IS_ERR(map)) {
+		dev_err(dev, "regmap not found");
+		return PTR_ERR(map);
+	}
+
+	ost->clk = devm_clk_get_enabled(dev, "ost");
+	if (IS_ERR(ost->clk))
+		return PTR_ERR(ost->clk);
+
+	/* Clear counter high/low registers */
+	if (soc_info->is64bit)
+		regmap_write(map, TCU_REG_OST_CNTL, 0);
+	regmap_write(map, TCU_REG_OST_CNTH, 0);
+
+	/* Don't reset counter at compare value. */
+	regmap_update_bits(map, TCU_REG_OST_TCSR,
+			   TCU_OST_TCSR_MASK, TCU_OST_TCSR_CNT_MD);
+
+	rate = clk_get_rate(ost->clk);
+
+	/* Enable OST TCU channel */
+	regmap_write(map, TCU_REG_TESR, BIT(TCU_OST_CHANNEL));
+
+	cs = &ost->cs;
+	cs->name	= "ingenic-ost";
+	cs->rating	= 320;
+	cs->flags	= CLOCK_SOURCE_IS_CONTINUOUS;
+	cs->mask	= CLOCKSOURCE_MASK(32);
+
+	if (soc_info->is64bit)
+		cs->read = ingenic_ost_clocksource_readl;
+	else
+		cs->read = ingenic_ost_clocksource_readh;
+
+	err = clocksource_register_hz(cs, rate);
+	if (err) {
+		dev_err(dev, "clocksource registration failed");
+		return err;
+	}
+
+	if (soc_info->is64bit)
+		sched_clock_register(ingenic_ost_read_cntl, 32, rate);
+	else
+		sched_clock_register(ingenic_ost_read_cnth, 32, rate);
+
+	return 0;
+}
+
+static int ingenic_ost_suspend(struct device *dev)
+{
+	struct ingenic_ost *ost = dev_get_drvdata(dev);
+
+	clk_disable(ost->clk);
+
+	return 0;
+}
+
+static int ingenic_ost_resume(struct device *dev)
+{
+	struct ingenic_ost *ost = dev_get_drvdata(dev);
+
+	return clk_enable(ost->clk);
+}
+
+static const struct dev_pm_ops ingenic_ost_pm_ops = {
+	/* _noirq: We want the OST clock to be gated last / ungated first */
+	.suspend_noirq = ingenic_ost_suspend,
+	.resume_noirq  = ingenic_ost_resume,
+};
+
+static const struct ingenic_ost_soc_info jz4725b_ost_soc_info = {
+	.is64bit = false,
+};
+
+static const struct ingenic_ost_soc_info jz4760b_ost_soc_info = {
+	.is64bit = true,
+};
+
+static const struct of_device_id ingenic_ost_of_match[] = {
+	{ .compatible = "ingenic,jz4725b-ost", .data = &jz4725b_ost_soc_info, },
+	{ .compatible = "ingenic,jz4760b-ost", .data = &jz4760b_ost_soc_info, },
+	{ .compatible = "ingenic,jz4770-ost", .data = &jz4760b_ost_soc_info, },
+	{ }
+};
+
+static struct platform_driver ingenic_ost_driver = {
+	.driver = {
+		.name = "ingenic-ost",
+		.pm = pm_sleep_ptr(&ingenic_ost_pm_ops),
+		.of_match_table = ingenic_ost_of_match,
+	},
+};
+builtin_platform_driver_probe(ingenic_ost_driver, ingenic_ost_probe);