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, 310 insertions, 0 deletions

diff --git a/drivers/mfd/qcom-spmi-pmic.c b/drivers/mfd/qcom-spmi-pmic.c
new file mode 100644
index 000000000..b4b178caf
--- /dev/null
+++ b/drivers/mfd/qcom-spmi-pmic.c
@@ -0,0 +1,310 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/gfp.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/spmi.h>
+#include <linux/types.h>
+#include <linux/regmap.h>
+#include <soc/qcom/qcom-spmi-pmic.h>
+
+#define PMIC_REV2		0x101
+#define PMIC_REV3		0x102
+#define PMIC_REV4		0x103
+#define PMIC_TYPE		0x104
+#define PMIC_SUBTYPE		0x105
+#define PMIC_FAB_ID		0x1f2
+
+#define PMIC_TYPE_VALUE		0x51
+
+#define PMIC_REV4_V2		0x02
+
+struct qcom_spmi_dev {
+	int num_usids;
+	struct qcom_spmi_pmic pmic;
+};
+
+static DEFINE_MUTEX(pmic_spmi_revid_lock);
+
+#define N_USIDS(n)		((void *)n)
+
+static const struct of_device_id pmic_spmi_id_table[] = {
+	{ .compatible = "qcom,pm660", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm660l", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8004", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8005", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8019", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8028", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8110", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8150", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8150b", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8150c", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8150l", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8226", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8841", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8901", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8909", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8916", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8937", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8941", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8950", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8994", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pm8998", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pma8084", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pmd9635", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pmi8950", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pmi8962", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pmi8994", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pmi8998", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pmk8002", .data = N_USIDS(2) },
+	{ .compatible = "qcom,pmp8074", .data = N_USIDS(2) },
+	{ .compatible = "qcom,smb2351", .data = N_USIDS(2) },
+	{ .compatible = "qcom,spmi-pmic", .data = N_USIDS(1) },
+	{ }
+};
+
+/*
+ * A PMIC can be represented by multiple SPMI devices, but
+ * only the base PMIC device will contain a reference to
+ * the revision information.
+ *
+ * This function takes a pointer to a pmic device and
+ * returns a pointer to the base PMIC device.
+ *
+ * This only supports PMICs with 1 or 2 USIDs.
+ */
+static struct spmi_device *qcom_pmic_get_base_usid(struct spmi_device *sdev, struct qcom_spmi_dev *ctx)
+{
+	struct device_node *spmi_bus;
+	int function_parent_usid, ret;
+	u32 pmic_addr;
+
+	/*
+	 * Quick return if the function device is already in the base
+	 * USID. This will always be hit for PMICs with only 1 USID.
+	 */
+	if (sdev->usid % ctx->num_usids == 0) {
+		get_device(&sdev->dev);
+		return sdev;
+	}
+
+	function_parent_usid = sdev->usid;
+
+	/*
+	 * Walk through the list of PMICs until we find the sibling USID.
+	 * The goal is to find the first USID which is less than the
+	 * number of USIDs in the PMIC array, e.g. for a PMIC with 2 USIDs
+	 * where the function device is under USID 3, we want to find the
+	 * device for USID 2.
+	 */
+	spmi_bus = of_get_parent(sdev->dev.of_node);
+	sdev = ERR_PTR(-ENODATA);
+	for_each_child_of_node_scoped(spmi_bus, child) {
+		ret = of_property_read_u32_index(child, "reg", 0, &pmic_addr);
+		if (ret) {
+			sdev = ERR_PTR(ret);
+			break;
+		}
+
+		if (pmic_addr == function_parent_usid - (ctx->num_usids - 1)) {
+			sdev = spmi_find_device_by_of_node(child);
+			if (!sdev) {
+				/*
+				 * If the base USID for this PMIC hasn't been
+				 * registered yet then we need to defer.
+				 */
+				sdev = ERR_PTR(-EPROBE_DEFER);
+			}
+			break;
+		}
+	}
+
+	of_node_put(spmi_bus);
+
+	return sdev;
+}
+
+static int pmic_spmi_get_base_revid(struct spmi_device *sdev, struct qcom_spmi_dev *ctx)
+{
+	struct qcom_spmi_dev *base_ctx;
+	struct spmi_device *base;
+	int ret = 0;
+
+	base = qcom_pmic_get_base_usid(sdev, ctx);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	/*
+	 * Copy revid info from base device if it has probed and is still
+	 * bound to its driver.
+	 */
+	mutex_lock(&pmic_spmi_revid_lock);
+	base_ctx = spmi_device_get_drvdata(base);
+	if (!base_ctx) {
+		ret = -EPROBE_DEFER;
+		goto out_unlock;
+	}
+	memcpy(&ctx->pmic, &base_ctx->pmic, sizeof(ctx->pmic));
+out_unlock:
+	mutex_unlock(&pmic_spmi_revid_lock);
+
+	put_device(&base->dev);
+
+	return ret;
+}
+
+static int pmic_spmi_load_revid(struct regmap *map, struct device *dev,
+				 struct qcom_spmi_pmic *pmic)
+{
+	int ret;
+
+	ret = regmap_read(map, PMIC_TYPE, &pmic->type);
+	if (ret < 0)
+		return ret;
+
+	if (pmic->type != PMIC_TYPE_VALUE)
+		return ret;
+
+	ret = regmap_read(map, PMIC_SUBTYPE, &pmic->subtype);
+	if (ret < 0)
+		return ret;
+
+	pmic->name = of_match_device(pmic_spmi_id_table, dev)->compatible;
+
+	ret = regmap_read(map, PMIC_REV2, &pmic->rev2);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_read(map, PMIC_REV3, &pmic->minor);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_read(map, PMIC_REV4, &pmic->major);
+	if (ret < 0)
+		return ret;
+
+	if (pmic->subtype == PMI8998_SUBTYPE || pmic->subtype == PM660_SUBTYPE) {
+		ret = regmap_read(map, PMIC_FAB_ID, &pmic->fab_id);
+		if (ret < 0)
+			return ret;
+	}
+
+	/*
+	 * In early versions of PM8941 and PM8226, the major revision number
+	 * started incrementing from 0 (eg 0 = v1.0, 1 = v2.0).
+	 * Increment the major revision number here if the chip is an early
+	 * version of PM8941 or PM8226.
+	 */
+	if ((pmic->subtype == PM8941_SUBTYPE || pmic->subtype == PM8226_SUBTYPE) &&
+	    pmic->major < PMIC_REV4_V2)
+		pmic->major++;
+
+	if (pmic->subtype == PM8110_SUBTYPE)
+		pmic->minor = pmic->rev2;
+
+	dev_dbg(dev, "%x: %s v%d.%d\n",
+		pmic->subtype, pmic->name, pmic->major, pmic->minor);
+
+	return 0;
+}
+
+/**
+ * qcom_pmic_get() - Get a pointer to the base PMIC device
+ *
+ * This function takes a struct device for a driver which is a child of a PMIC.
+ * And locates the PMIC revision information for it.
+ *
+ * @dev: the pmic function device
+ * @return: the struct qcom_spmi_pmic* pointer associated with the function device
+ */
+const struct qcom_spmi_pmic *qcom_pmic_get(struct device *dev)
+{
+	struct spmi_device *sdev;
+	struct qcom_spmi_dev *spmi;
+
+	/*
+	 * Make sure the device is actually a child of a PMIC
+	 */
+	if (!of_match_device(pmic_spmi_id_table, dev->parent))
+		return ERR_PTR(-EINVAL);
+
+	sdev = to_spmi_device(dev->parent);
+	spmi = dev_get_drvdata(&sdev->dev);
+
+	return &spmi->pmic;
+}
+EXPORT_SYMBOL_GPL(qcom_pmic_get);
+
+static const struct regmap_config spmi_regmap_config = {
+	.reg_bits	= 16,
+	.val_bits	= 8,
+	.max_register	= 0xffff,
+	.fast_io	= true,
+};
+
+static int pmic_spmi_probe(struct spmi_device *sdev)
+{
+	struct regmap *regmap;
+	struct qcom_spmi_dev *ctx;
+	int ret;
+
+	regmap = devm_regmap_init_spmi_ext(sdev, &spmi_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	ctx = devm_kzalloc(&sdev->dev, sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+
+	ctx->num_usids = (uintptr_t)device_get_match_data(&sdev->dev);
+
+	/* Only the first slave id for a PMIC contains this information */
+	if (sdev->usid % ctx->num_usids == 0) {
+		ret = pmic_spmi_load_revid(regmap, &sdev->dev, &ctx->pmic);
+		if (ret < 0)
+			return ret;
+	} else {
+		ret = pmic_spmi_get_base_revid(sdev, ctx);
+		if (ret)
+			return ret;
+	}
+
+	mutex_lock(&pmic_spmi_revid_lock);
+	spmi_device_set_drvdata(sdev, ctx);
+	mutex_unlock(&pmic_spmi_revid_lock);
+
+	return devm_of_platform_populate(&sdev->dev);
+}
+
+static void pmic_spmi_remove(struct spmi_device *sdev)
+{
+	mutex_lock(&pmic_spmi_revid_lock);
+	spmi_device_set_drvdata(sdev, NULL);
+	mutex_unlock(&pmic_spmi_revid_lock);
+}
+
+MODULE_DEVICE_TABLE(of, pmic_spmi_id_table);
+
+static struct spmi_driver pmic_spmi_driver = {
+	.probe = pmic_spmi_probe,
+	.remove = pmic_spmi_remove,
+	.driver = {
+		.name = "pmic-spmi",
+		.of_match_table = pmic_spmi_id_table,
+	},
+};
+module_spmi_driver(pmic_spmi_driver);
+
+MODULE_DESCRIPTION("Qualcomm SPMI PMIC driver");
+MODULE_ALIAS("spmi:spmi-pmic");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Josh Cartwright <joshc@codeaurora.org>");
+MODULE_AUTHOR("Stanimir Varbanov <svarbanov@mm-sol.com>");