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, 207 insertions, 0 deletions

diff --git a/drivers/reset/reset-simple.c b/drivers/reset/reset-simple.c
new file mode 100644
index 000000000..79e94ecfe
--- /dev/null
+++ b/drivers/reset/reset-simple.c
@@ -0,0 +1,207 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Simple Reset Controller Driver
+ *
+ * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
+ *
+ * Based on Allwinner SoCs Reset Controller driver
+ *
+ * Copyright 2013 Maxime Ripard
+ *
+ * Maxime Ripard <maxime.ripard@free-electrons.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/reset/reset-simple.h>
+#include <linux/spinlock.h>
+
+static inline struct reset_simple_data *
+to_reset_simple_data(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct reset_simple_data, rcdev);
+}
+
+static int reset_simple_update(struct reset_controller_dev *rcdev,
+			       unsigned long id, bool assert)
+{
+	struct reset_simple_data *data = to_reset_simple_data(rcdev);
+	int reg_width = sizeof(u32);
+	int bank = id / (reg_width * BITS_PER_BYTE);
+	int offset = id % (reg_width * BITS_PER_BYTE);
+	unsigned long flags;
+	u32 reg;
+
+	spin_lock_irqsave(&data->lock, flags);
+
+	reg = readl(data->membase + (bank * reg_width));
+	if (assert ^ data->active_low)
+		reg |= BIT(offset);
+	else
+		reg &= ~BIT(offset);
+	writel(reg, data->membase + (bank * reg_width));
+
+	spin_unlock_irqrestore(&data->lock, flags);
+
+	return 0;
+}
+
+static int reset_simple_assert(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	return reset_simple_update(rcdev, id, true);
+}
+
+static int reset_simple_deassert(struct reset_controller_dev *rcdev,
+				 unsigned long id)
+{
+	return reset_simple_update(rcdev, id, false);
+}
+
+static int reset_simple_reset(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	struct reset_simple_data *data = to_reset_simple_data(rcdev);
+	int ret;
+
+	if (!data->reset_us)
+		return -ENOTSUPP;
+
+	ret = reset_simple_assert(rcdev, id);
+	if (ret)
+		return ret;
+
+	usleep_range(data->reset_us, data->reset_us * 2);
+
+	return reset_simple_deassert(rcdev, id);
+}
+
+static int reset_simple_status(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	struct reset_simple_data *data = to_reset_simple_data(rcdev);
+	int reg_width = sizeof(u32);
+	int bank = id / (reg_width * BITS_PER_BYTE);
+	int offset = id % (reg_width * BITS_PER_BYTE);
+	u32 reg;
+
+	reg = readl(data->membase + (bank * reg_width));
+
+	return !(reg & BIT(offset)) ^ !data->status_active_low;
+}
+
+const struct reset_control_ops reset_simple_ops = {
+	.assert		= reset_simple_assert,
+	.deassert	= reset_simple_deassert,
+	.reset		= reset_simple_reset,
+	.status		= reset_simple_status,
+};
+EXPORT_SYMBOL_GPL(reset_simple_ops);
+
+/**
+ * struct reset_simple_devdata - simple reset controller properties
+ * @reg_offset: offset between base address and first reset register.
+ * @nr_resets: number of resets. If not set, default to resource size in bits.
+ * @active_low: if true, bits are cleared to assert the reset. Otherwise, bits
+ *              are set to assert the reset.
+ * @status_active_low: if true, bits read back as cleared while the reset is
+ *                     asserted. Otherwise, bits read back as set while the
+ *                     reset is asserted.
+ */
+struct reset_simple_devdata {
+	u32 reg_offset;
+	u32 nr_resets;
+	bool active_low;
+	bool status_active_low;
+};
+
+#define SOCFPGA_NR_BANKS	8
+
+static const struct reset_simple_devdata reset_simple_socfpga = {
+	.reg_offset = 0x20,
+	.nr_resets = SOCFPGA_NR_BANKS * 32,
+	.status_active_low = true,
+};
+
+static const struct reset_simple_devdata reset_simple_active_low = {
+	.active_low = true,
+	.status_active_low = true,
+};
+
+static const struct of_device_id reset_simple_dt_ids[] = {
+	{ .compatible = "altr,stratix10-rst-mgr",
+		.data = &reset_simple_socfpga },
+	{ .compatible = "st,stm32-rcc", },
+	{ .compatible = "allwinner,sun6i-a31-clock-reset",
+		.data = &reset_simple_active_low },
+	{ .compatible = "zte,zx296718-reset",
+		.data = &reset_simple_active_low },
+	{ .compatible = "aspeed,ast2400-lpc-reset" },
+	{ .compatible = "aspeed,ast2500-lpc-reset" },
+	{ .compatible = "aspeed,ast2600-lpc-reset" },
+	{ .compatible = "bitmain,bm1880-reset",
+		.data = &reset_simple_active_low },
+	{ .compatible = "brcm,bcm4908-misc-pcie-reset",
+		.data = &reset_simple_active_low },
+	{ .compatible = "snps,dw-high-reset" },
+	{ .compatible = "snps,dw-low-reset",
+		.data = &reset_simple_active_low },
+	{ .compatible = "sophgo,cv1800b-reset",
+		.data = &reset_simple_active_low },
+	{ .compatible = "sophgo,sg2042-reset",
+		.data = &reset_simple_active_low },
+	{ /* sentinel */ },
+};
+
+static int reset_simple_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct reset_simple_devdata *devdata;
+	struct reset_simple_data *data;
+	void __iomem *membase;
+	struct resource *res;
+	u32 reg_offset = 0;
+
+	devdata = of_device_get_match_data(dev);
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	membase = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(membase))
+		return PTR_ERR(membase);
+
+	spin_lock_init(&data->lock);
+	data->membase = membase;
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.nr_resets = resource_size(res) * BITS_PER_BYTE;
+	data->rcdev.ops = &reset_simple_ops;
+	data->rcdev.of_node = dev->of_node;
+
+	if (devdata) {
+		reg_offset = devdata->reg_offset;
+		if (devdata->nr_resets)
+			data->rcdev.nr_resets = devdata->nr_resets;
+		data->active_low = devdata->active_low;
+		data->status_active_low = devdata->status_active_low;
+	}
+
+	data->membase += reg_offset;
+
+	return devm_reset_controller_register(dev, &data->rcdev);
+}
+
+static struct platform_driver reset_simple_driver = {
+	.probe	= reset_simple_probe,
+	.driver = {
+		.name		= "simple-reset",
+		.of_match_table	= reset_simple_dt_ids,
+	},
+};
+builtin_platform_driver(reset_simple_driver);