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, 108 insertions, 0 deletions

diff --git a/drivers/nvmem/layerscape-sfp.c b/drivers/nvmem/layerscape-sfp.c
new file mode 100644
index 000000000..c1521afd5
--- /dev/null
+++ b/drivers/nvmem/layerscape-sfp.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Layerscape SFP driver
+ *
+ * Copyright (c) 2022 Michael Walle <michael@walle.cc>
+ *
+ */
+
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+#define LAYERSCAPE_SFP_OTP_OFFSET	0x0200
+
+struct layerscape_sfp_priv {
+	struct regmap *regmap;
+};
+
+struct layerscape_sfp_data {
+	int size;
+	enum regmap_endian endian;
+};
+
+static int layerscape_sfp_read(void *context, unsigned int offset, void *val,
+			       size_t bytes)
+{
+	struct layerscape_sfp_priv *priv = context;
+
+	return regmap_bulk_read(priv->regmap,
+				LAYERSCAPE_SFP_OTP_OFFSET + offset, val,
+				bytes / 4);
+}
+
+static struct nvmem_config layerscape_sfp_nvmem_config = {
+	.name = "fsl-sfp",
+	.reg_read = layerscape_sfp_read,
+	.word_size = 4,
+	.stride = 4,
+};
+
+static int layerscape_sfp_probe(struct platform_device *pdev)
+{
+	const struct layerscape_sfp_data *data;
+	struct layerscape_sfp_priv *priv;
+	struct nvmem_device *nvmem;
+	struct regmap_config config = { 0 };
+	void __iomem *base;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	data = device_get_match_data(&pdev->dev);
+	config.reg_bits = 32;
+	config.reg_stride = 4;
+	config.val_bits = 32;
+	config.val_format_endian = data->endian;
+	config.max_register = LAYERSCAPE_SFP_OTP_OFFSET + data->size - 4;
+	priv->regmap = devm_regmap_init_mmio(&pdev->dev, base, &config);
+	if (IS_ERR(priv->regmap))
+		return PTR_ERR(priv->regmap);
+
+	layerscape_sfp_nvmem_config.size = data->size;
+	layerscape_sfp_nvmem_config.dev = &pdev->dev;
+	layerscape_sfp_nvmem_config.priv = priv;
+
+	nvmem = devm_nvmem_register(&pdev->dev, &layerscape_sfp_nvmem_config);
+
+	return PTR_ERR_OR_ZERO(nvmem);
+}
+
+static const struct layerscape_sfp_data ls1021a_data = {
+	.size = 0x88,
+	.endian = REGMAP_ENDIAN_BIG,
+};
+
+static const struct layerscape_sfp_data ls1028a_data = {
+	.size = 0x88,
+	.endian = REGMAP_ENDIAN_LITTLE,
+};
+
+static const struct of_device_id layerscape_sfp_dt_ids[] = {
+	{ .compatible = "fsl,ls1021a-sfp", .data = &ls1021a_data },
+	{ .compatible = "fsl,ls1028a-sfp", .data = &ls1028a_data },
+	{},
+};
+MODULE_DEVICE_TABLE(of, layerscape_sfp_dt_ids);
+
+static struct platform_driver layerscape_sfp_driver = {
+	.probe	= layerscape_sfp_probe,
+	.driver = {
+		.name	= "layerscape_sfp",
+		.of_match_table = layerscape_sfp_dt_ids,
+	},
+};
+module_platform_driver(layerscape_sfp_driver);
+
+MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
+MODULE_DESCRIPTION("Layerscape Security Fuse Processor driver");
+MODULE_LICENSE("GPL");