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, 260 insertions, 0 deletions

diff --git a/drivers/hwspinlock/qcom_hwspinlock.c b/drivers/hwspinlock/qcom_hwspinlock.c
new file mode 100644
index 000000000..712003a46
--- /dev/null
+++ b/drivers/hwspinlock/qcom_hwspinlock.c
@@ -0,0 +1,260 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2013, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2015, Sony Mobile Communications AB
+ */
+
+#include <linux/hwspinlock.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include "hwspinlock_internal.h"
+
+#define QCOM_MUTEX_APPS_PROC_ID	1
+#define QCOM_MUTEX_NUM_LOCKS	32
+
+struct qcom_hwspinlock_of_data {
+	u32 offset;
+	u32 stride;
+	const struct regmap_config *regmap_config;
+};
+
+static int qcom_hwspinlock_trylock(struct hwspinlock *lock)
+{
+	struct regmap_field *field = lock->priv;
+	u32 lock_owner;
+	int ret;
+
+	ret = regmap_field_write(field, QCOM_MUTEX_APPS_PROC_ID);
+	if (ret)
+		return ret;
+
+	ret = regmap_field_read(field, &lock_owner);
+	if (ret)
+		return ret;
+
+	return lock_owner == QCOM_MUTEX_APPS_PROC_ID;
+}
+
+static void qcom_hwspinlock_unlock(struct hwspinlock *lock)
+{
+	struct regmap_field *field = lock->priv;
+	u32 lock_owner;
+	int ret;
+
+	ret = regmap_field_read(field, &lock_owner);
+	if (ret) {
+		pr_err("%s: unable to query spinlock owner\n", __func__);
+		return;
+	}
+
+	if (lock_owner != QCOM_MUTEX_APPS_PROC_ID) {
+		pr_err("%s: spinlock not owned by us (actual owner is %d)\n",
+				__func__, lock_owner);
+	}
+
+	ret = regmap_field_write(field, 0);
+	if (ret)
+		pr_err("%s: failed to unlock spinlock\n", __func__);
+}
+
+static int qcom_hwspinlock_bust(struct hwspinlock *lock, unsigned int id)
+{
+	struct regmap_field *field = lock->priv;
+	u32 owner;
+	int ret;
+
+	ret = regmap_field_read(field, &owner);
+	if (ret) {
+		dev_err(lock->bank->dev, "unable to query spinlock owner\n");
+		return ret;
+	}
+
+	if (owner != id)
+		return 0;
+
+	ret = regmap_field_write(field, 0);
+	if (ret) {
+		dev_err(lock->bank->dev, "failed to bust spinlock\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct hwspinlock_ops qcom_hwspinlock_ops = {
+	.trylock	= qcom_hwspinlock_trylock,
+	.unlock		= qcom_hwspinlock_unlock,
+	.bust		= qcom_hwspinlock_bust,
+};
+
+static const struct regmap_config sfpb_mutex_config = {
+	.reg_bits		= 32,
+	.reg_stride		= 4,
+	.val_bits		= 32,
+	.max_register		= 0x100,
+	.fast_io		= true,
+};
+
+static const struct qcom_hwspinlock_of_data of_sfpb_mutex = {
+	.offset = 0x4,
+	.stride = 0x4,
+	.regmap_config = &sfpb_mutex_config,
+};
+
+static const struct regmap_config tcsr_msm8226_mutex_config = {
+	.reg_bits		= 32,
+	.reg_stride		= 4,
+	.val_bits		= 32,
+	.max_register		= 0x1000,
+	.fast_io		= true,
+};
+
+static const struct qcom_hwspinlock_of_data of_msm8226_tcsr_mutex = {
+	.offset = 0,
+	.stride = 0x80,
+	.regmap_config = &tcsr_msm8226_mutex_config,
+};
+
+static const struct regmap_config tcsr_mutex_config = {
+	.reg_bits		= 32,
+	.reg_stride		= 4,
+	.val_bits		= 32,
+	.max_register		= 0x20000,
+	.fast_io		= true,
+};
+
+static const struct qcom_hwspinlock_of_data of_tcsr_mutex = {
+	.offset = 0,
+	.stride = 0x1000,
+	.regmap_config = &tcsr_mutex_config,
+};
+
+static const struct of_device_id qcom_hwspinlock_of_match[] = {
+	{ .compatible = "qcom,sfpb-mutex", .data = &of_sfpb_mutex },
+	{ .compatible = "qcom,tcsr-mutex", .data = &of_tcsr_mutex },
+	{ .compatible = "qcom,apq8084-tcsr-mutex", .data = &of_msm8226_tcsr_mutex },
+	{ .compatible = "qcom,msm8226-tcsr-mutex", .data = &of_msm8226_tcsr_mutex },
+	{ .compatible = "qcom,msm8974-tcsr-mutex", .data = &of_msm8226_tcsr_mutex },
+	{ .compatible = "qcom,msm8994-tcsr-mutex", .data = &of_msm8226_tcsr_mutex },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, qcom_hwspinlock_of_match);
+
+static struct regmap *qcom_hwspinlock_probe_syscon(struct platform_device *pdev,
+						   u32 *base, u32 *stride)
+{
+	struct device_node *syscon;
+	struct regmap *regmap;
+	int ret;
+
+	syscon = of_parse_phandle(pdev->dev.of_node, "syscon", 0);
+	if (!syscon)
+		return ERR_PTR(-ENODEV);
+
+	regmap = syscon_node_to_regmap(syscon);
+	of_node_put(syscon);
+	if (IS_ERR(regmap))
+		return regmap;
+
+	ret = of_property_read_u32_index(pdev->dev.of_node, "syscon", 1, base);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "no offset in syscon\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	ret = of_property_read_u32_index(pdev->dev.of_node, "syscon", 2, stride);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "no stride syscon\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	return regmap;
+}
+
+static struct regmap *qcom_hwspinlock_probe_mmio(struct platform_device *pdev,
+						 u32 *offset, u32 *stride)
+{
+	const struct qcom_hwspinlock_of_data *data;
+	struct device *dev = &pdev->dev;
+	void __iomem *base;
+
+	data = of_device_get_match_data(dev);
+	if (!data->regmap_config)
+		return ERR_PTR(-EINVAL);
+
+	*offset = data->offset;
+	*stride = data->stride;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return ERR_CAST(base);
+
+	return devm_regmap_init_mmio(dev, base, data->regmap_config);
+}
+
+static int qcom_hwspinlock_probe(struct platform_device *pdev)
+{
+	struct hwspinlock_device *bank;
+	struct regmap *regmap;
+	size_t array_size;
+	u32 stride;
+	u32 base;
+	int i;
+
+	regmap = qcom_hwspinlock_probe_syscon(pdev, &base, &stride);
+	if (IS_ERR(regmap) && PTR_ERR(regmap) == -ENODEV)
+		regmap = qcom_hwspinlock_probe_mmio(pdev, &base, &stride);
+
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	array_size = QCOM_MUTEX_NUM_LOCKS * sizeof(struct hwspinlock);
+	bank = devm_kzalloc(&pdev->dev, sizeof(*bank) + array_size, GFP_KERNEL);
+	if (!bank)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, bank);
+
+	for (i = 0; i < QCOM_MUTEX_NUM_LOCKS; i++) {
+		struct reg_field field = REG_FIELD(base + i * stride, 0, 31);
+
+		bank->lock[i].priv = devm_regmap_field_alloc(&pdev->dev,
+							     regmap, field);
+		if (IS_ERR(bank->lock[i].priv))
+			return PTR_ERR(bank->lock[i].priv);
+	}
+
+	return devm_hwspin_lock_register(&pdev->dev, bank, &qcom_hwspinlock_ops,
+					 0, QCOM_MUTEX_NUM_LOCKS);
+}
+
+static struct platform_driver qcom_hwspinlock_driver = {
+	.probe		= qcom_hwspinlock_probe,
+	.driver		= {
+		.name	= "qcom_hwspinlock",
+		.of_match_table = qcom_hwspinlock_of_match,
+	},
+};
+
+static int __init qcom_hwspinlock_init(void)
+{
+	return platform_driver_register(&qcom_hwspinlock_driver);
+}
+/* board init code might need to reserve hwspinlocks for predefined purposes */
+postcore_initcall(qcom_hwspinlock_init);
+
+static void __exit qcom_hwspinlock_exit(void)
+{
+	platform_driver_unregister(&qcom_hwspinlock_driver);
+}
+module_exit(qcom_hwspinlock_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Hardware spinlock driver for Qualcomm SoCs");