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, 203 insertions, 0 deletions

diff --git a/drivers/mfd/altera-sysmgr.c b/drivers/mfd/altera-sysmgr.c
new file mode 100644
index 000000000..90c6902d5
--- /dev/null
+++ b/drivers/mfd/altera-sysmgr.c
@@ -0,0 +1,203 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 2018-2019, Intel Corporation.
+ *  Copyright (C) 2012 Freescale Semiconductor, Inc.
+ *  Copyright (C) 2012 Linaro Ltd.
+ *
+ *  Based on syscon driver.
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/mfd/altera-sysmgr.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+/**
+ * struct altr_sysmgr - Altera SOCFPGA System Manager
+ * @regmap: the regmap used for System Manager accesses.
+ */
+struct altr_sysmgr {
+	struct regmap   *regmap;
+};
+
+static struct platform_driver altr_sysmgr_driver;
+
+/**
+ * s10_protected_reg_write
+ * Write to a protected SMC register.
+ * @base: Base address of System Manager
+ * @reg:  Address offset of register
+ * @val:  Value to write
+ * Return: INTEL_SIP_SMC_STATUS_OK (0) on success
+ *	   INTEL_SIP_SMC_REG_ERROR on error
+ *	   INTEL_SIP_SMC_RETURN_UNKNOWN_FUNCTION if not supported
+ */
+static int s10_protected_reg_write(void *base,
+				   unsigned int reg, unsigned int val)
+{
+	struct arm_smccc_res result;
+	unsigned long sysmgr_base = (unsigned long)base;
+
+	arm_smccc_smc(INTEL_SIP_SMC_REG_WRITE, sysmgr_base + reg,
+		      val, 0, 0, 0, 0, 0, &result);
+
+	return (int)result.a0;
+}
+
+/**
+ * s10_protected_reg_read
+ * Read the status of a protected SMC register
+ * @base: Base address of System Manager.
+ * @reg:  Address of register
+ * @val:  Value read.
+ * Return: INTEL_SIP_SMC_STATUS_OK (0) on success
+ *	   INTEL_SIP_SMC_REG_ERROR on error
+ *	   INTEL_SIP_SMC_RETURN_UNKNOWN_FUNCTION if not supported
+ */
+static int s10_protected_reg_read(void *base,
+				  unsigned int reg, unsigned int *val)
+{
+	struct arm_smccc_res result;
+	unsigned long sysmgr_base = (unsigned long)base;
+
+	arm_smccc_smc(INTEL_SIP_SMC_REG_READ, sysmgr_base + reg,
+		      0, 0, 0, 0, 0, 0, &result);
+
+	*val = (unsigned int)result.a1;
+
+	return (int)result.a0;
+}
+
+static struct regmap_config altr_sysmgr_regmap_cfg = {
+	.name = "altr_sysmgr",
+	.reg_bits = 32,
+	.reg_stride = 4,
+	.val_bits = 32,
+	.fast_io = true,
+	.use_single_read = true,
+	.use_single_write = true,
+};
+
+/**
+ * altr_sysmgr_regmap_lookup_by_phandle
+ * Find the sysmgr previous configured in probe() and return regmap property.
+ * Return: regmap if found or error if not found.
+ *
+ * @np: Pointer to device's Device Tree node
+ * @property: Device Tree property name which references the sysmgr
+ */
+struct regmap *altr_sysmgr_regmap_lookup_by_phandle(struct device_node *np,
+						    const char *property)
+{
+	struct device *dev;
+	struct altr_sysmgr *sysmgr;
+	struct device_node *sysmgr_np;
+
+	if (property)
+		sysmgr_np = of_parse_phandle(np, property, 0);
+	else
+		sysmgr_np = np;
+
+	if (!sysmgr_np)
+		return ERR_PTR(-ENODEV);
+
+	dev = driver_find_device_by_of_node(&altr_sysmgr_driver.driver,
+					    (void *)sysmgr_np);
+	if (property)
+		of_node_put(sysmgr_np);
+
+	if (!dev)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	sysmgr = dev_get_drvdata(dev);
+
+	put_device(dev);
+
+	return sysmgr->regmap;
+}
+EXPORT_SYMBOL_GPL(altr_sysmgr_regmap_lookup_by_phandle);
+
+static int sysmgr_probe(struct platform_device *pdev)
+{
+	struct altr_sysmgr *sysmgr;
+	struct regmap *regmap;
+	struct resource *res;
+	struct regmap_config sysmgr_config = altr_sysmgr_regmap_cfg;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	void __iomem *base;
+
+	sysmgr = devm_kzalloc(dev, sizeof(*sysmgr), GFP_KERNEL);
+	if (!sysmgr)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENOENT;
+
+	sysmgr_config.max_register = resource_size(res) -
+				     sysmgr_config.reg_stride;
+	if (of_device_is_compatible(np, "altr,sys-mgr-s10")) {
+		sysmgr_config.reg_read = s10_protected_reg_read;
+		sysmgr_config.reg_write = s10_protected_reg_write;
+
+		/* Need physical address for SMCC call */
+		regmap = devm_regmap_init(dev, NULL,
+					  (void *)(uintptr_t)res->start,
+					  &sysmgr_config);
+	} else {
+		base = devm_ioremap(dev, res->start, resource_size(res));
+		if (!base)
+			return -ENOMEM;
+
+		sysmgr_config.max_register = resource_size(res) - 4;
+		regmap = devm_regmap_init_mmio(dev, base, &sysmgr_config);
+	}
+
+	if (IS_ERR(regmap)) {
+		pr_err("regmap init failed\n");
+		return PTR_ERR(regmap);
+	}
+
+	sysmgr->regmap = regmap;
+
+	platform_set_drvdata(pdev, sysmgr);
+
+	return 0;
+}
+
+static const struct of_device_id altr_sysmgr_of_match[] = {
+	{ .compatible = "altr,sys-mgr" },
+	{ .compatible = "altr,sys-mgr-s10" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, altr_sysmgr_of_match);
+
+static struct platform_driver altr_sysmgr_driver = {
+	.probe =  sysmgr_probe,
+	.driver = {
+		.name = "altr,system_manager",
+		.of_match_table = altr_sysmgr_of_match,
+	},
+};
+
+static int __init altr_sysmgr_init(void)
+{
+	return platform_driver_register(&altr_sysmgr_driver);
+}
+core_initcall(altr_sysmgr_init);
+
+static void __exit altr_sysmgr_exit(void)
+{
+	platform_driver_unregister(&altr_sysmgr_driver);
+}
+module_exit(altr_sysmgr_exit);
+
+MODULE_AUTHOR("Thor Thayer <>");
+MODULE_DESCRIPTION("SOCFPGA System Manager driver");