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, 143 insertions, 0 deletions

diff --git a/drivers/nvmem/imx-iim.c b/drivers/nvmem/imx-iim.c
new file mode 100644
index 000000000..8cfbe55a5
--- /dev/null
+++ b/drivers/nvmem/imx-iim.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * i.MX IIM driver
+ *
+ * Copyright (c) 2017 Pengutronix, Michael Grzeschik <m.grzeschik@pengutronix.de>
+ *
+ * Based on the barebox iim driver,
+ * Copyright (c) 2010 Baruch Siach <baruch@tkos.co.il>,
+ *	Orex Computed Radiography
+ */
+
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/clk.h>
+
+#define IIM_BANK_BASE(n)	(0x800 + 0x400 * (n))
+
+struct imx_iim_drvdata {
+	unsigned int nregs;
+};
+
+struct iim_priv {
+	void __iomem *base;
+	struct clk *clk;
+};
+
+static int imx_iim_read(void *context, unsigned int offset,
+			  void *buf, size_t bytes)
+{
+	struct iim_priv *iim = context;
+	int i, ret;
+	u8 *buf8 = buf;
+
+	ret = clk_prepare_enable(iim->clk);
+	if (ret)
+		return ret;
+
+	for (i = offset; i < offset + bytes; i++) {
+		int bank = i >> 5;
+		int reg = i & 0x1f;
+
+		*buf8++ = readl(iim->base + IIM_BANK_BASE(bank) + reg * 4);
+	}
+
+	clk_disable_unprepare(iim->clk);
+
+	return 0;
+}
+
+static struct imx_iim_drvdata imx27_drvdata = {
+	.nregs = 2 * 32,
+};
+
+static struct imx_iim_drvdata imx25_imx31_imx35_drvdata = {
+	.nregs = 3 * 32,
+};
+
+static struct imx_iim_drvdata imx51_drvdata = {
+	.nregs = 4 * 32,
+};
+
+static struct imx_iim_drvdata imx53_drvdata = {
+	.nregs = 4 * 32 + 16,
+};
+
+static const struct of_device_id imx_iim_dt_ids[] = {
+	{
+		.compatible = "fsl,imx25-iim",
+		.data = &imx25_imx31_imx35_drvdata,
+	}, {
+		.compatible = "fsl,imx27-iim",
+		.data = &imx27_drvdata,
+	}, {
+		.compatible = "fsl,imx31-iim",
+		.data = &imx25_imx31_imx35_drvdata,
+	}, {
+		.compatible = "fsl,imx35-iim",
+		.data = &imx25_imx31_imx35_drvdata,
+	}, {
+		.compatible = "fsl,imx51-iim",
+		.data = &imx51_drvdata,
+	}, {
+		.compatible = "fsl,imx53-iim",
+		.data = &imx53_drvdata,
+	}, {
+		/* sentinel */
+	},
+};
+MODULE_DEVICE_TABLE(of, imx_iim_dt_ids);
+
+static int imx_iim_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct iim_priv *iim;
+	struct nvmem_device *nvmem;
+	struct nvmem_config cfg = {};
+	const struct imx_iim_drvdata *drvdata = NULL;
+
+	iim = devm_kzalloc(dev, sizeof(*iim), GFP_KERNEL);
+	if (!iim)
+		return -ENOMEM;
+
+	iim->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(iim->base))
+		return PTR_ERR(iim->base);
+
+	drvdata = of_device_get_match_data(&pdev->dev);
+
+	iim->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(iim->clk))
+		return PTR_ERR(iim->clk);
+
+	cfg.name = "imx-iim";
+	cfg.read_only = true;
+	cfg.word_size = 1;
+	cfg.stride = 1;
+	cfg.reg_read = imx_iim_read;
+	cfg.dev = dev;
+	cfg.size = drvdata->nregs;
+	cfg.priv = iim;
+
+	nvmem = devm_nvmem_register(dev, &cfg);
+
+	return PTR_ERR_OR_ZERO(nvmem);
+}
+
+static struct platform_driver imx_iim_driver = {
+	.probe	= imx_iim_probe,
+	.driver = {
+		.name	= "imx-iim",
+		.of_match_table = imx_iim_dt_ids,
+	},
+};
+module_platform_driver(imx_iim_driver);
+
+MODULE_AUTHOR("Michael Grzeschik <m.grzeschik@pengutronix.de>");
+MODULE_DESCRIPTION("i.MX IIM driver");
+MODULE_LICENSE("GPL v2");