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, 142 insertions, 0 deletions

diff --git a/drivers/nvmem/rcar-efuse.c b/drivers/nvmem/rcar-efuse.c
new file mode 100644
index 000000000..b94ff83b7
--- /dev/null
+++ b/drivers/nvmem/rcar-efuse.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Renesas R-Car E-FUSE/OTP Driver
+ *
+ * Copyright (C) 2024 Glider bv
+ */
+
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/io.h>
+#include <linux/nvmem-provider.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/property.h>
+
+struct rcar_fuse {
+	struct nvmem_keepout keepouts[2];
+	struct nvmem_device *nvmem;
+	struct device *dev;
+	void __iomem *base;
+};
+
+struct rcar_fuse_data {
+	unsigned int bank;	/* 0: PFC + E-FUSE, 1: OPT_MEM + E-FUSE */
+	unsigned int start;	/* inclusive */
+	unsigned int end;	/* exclusive */
+};
+
+static int rcar_fuse_reg_read(void *priv, unsigned int offset, void *val,
+			      size_t bytes)
+{
+	struct rcar_fuse *fuse = priv;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(fuse->dev);
+	if (ret < 0)
+		return ret;
+
+	__ioread32_copy(val, fuse->base + offset, bytes / 4);
+
+	pm_runtime_put(fuse->dev);
+
+	return 0;
+}
+
+static int rcar_fuse_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct rcar_fuse_data *data = device_get_match_data(dev);
+	struct nvmem_config config = {
+		.dev = dev,
+		.name = "rcar-fuse",
+		.id = NVMEM_DEVID_NONE,
+		.owner = THIS_MODULE,
+		.type = NVMEM_TYPE_OTP,
+		.read_only = true,
+		.root_only = true,
+		.reg_read = rcar_fuse_reg_read,
+		.word_size = 4,
+		.stride = 4,
+	};
+	struct rcar_fuse *fuse;
+	struct resource *res;
+	int ret;
+
+	ret = devm_pm_runtime_enable(dev);
+	if (ret < 0)
+		return ret;
+
+	fuse = devm_kzalloc(dev, sizeof(*fuse), GFP_KERNEL);
+	if (!fuse)
+		return -ENOMEM;
+
+	fuse->base = devm_platform_get_and_ioremap_resource(pdev, data->bank,
+							    &res);
+	if (IS_ERR(fuse->base))
+		return PTR_ERR(fuse->base);
+
+	fuse->dev = dev;
+	fuse->keepouts[0].start = 0;
+	fuse->keepouts[0].end = data->start;
+	fuse->keepouts[1].start = data->end;
+	fuse->keepouts[1].end = resource_size(res);
+
+	config.keepout = fuse->keepouts;
+	config.nkeepout = ARRAY_SIZE(fuse->keepouts);
+	config.size = resource_size(res);
+	config.priv = fuse;
+
+	fuse->nvmem = devm_nvmem_register(dev, &config);
+	if (IS_ERR(fuse->nvmem))
+		return dev_err_probe(dev, PTR_ERR(fuse->nvmem),
+				     "Failed to register NVMEM device\n");
+
+	return 0;
+}
+
+static const struct rcar_fuse_data rcar_fuse_v3u = {
+	.bank = 0,
+	.start = 0x0c0,
+	.end = 0x0e8,
+};
+
+static const struct rcar_fuse_data rcar_fuse_s4 = {
+	.bank = 0,
+	.start = 0x0c0,
+	.end = 0x14c,
+};
+
+static const struct rcar_fuse_data rcar_fuse_v4h = {
+	.bank = 1,
+	.start = 0x100,
+	.end = 0x1a0,
+};
+
+static const struct rcar_fuse_data rcar_fuse_v4m = {
+	.bank = 1,
+	.start = 0x100,
+	.end = 0x110,
+};
+
+static const struct of_device_id rcar_fuse_match[] = {
+	{ .compatible = "renesas,r8a779a0-efuse", .data = &rcar_fuse_v3u },
+	{ .compatible = "renesas,r8a779f0-efuse", .data = &rcar_fuse_s4 },
+	{ .compatible = "renesas,r8a779g0-otp", .data = &rcar_fuse_v4h },
+	{ .compatible = "renesas,r8a779h0-otp", .data = &rcar_fuse_v4m },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rcar_fuse_match);
+
+static struct platform_driver rcar_fuse_driver = {
+	.probe = rcar_fuse_probe,
+	.driver = {
+		.name = "rcar_fuse",
+		.of_match_table = rcar_fuse_match,
+	},
+};
+module_platform_driver(rcar_fuse_driver);
+
+MODULE_DESCRIPTION("Renesas R-Car E-FUSE/OTP driver");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Geert Uytterhoeven");