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, 339 insertions, 0 deletions

diff --git a/drivers/misc/tps6594-pfsm.c b/drivers/misc/tps6594-pfsm.c
new file mode 100644
index 000000000..c3a0d6367
--- /dev/null
+++ b/drivers/misc/tps6594-pfsm.c
@@ -0,0 +1,339 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PFSM (Pre-configurable Finite State Machine) driver for the following
+ * PMICs:
+ * - LP8764
+ * - TPS65224
+ * - TPS652G1
+ * - TPS6594
+ * - TPS6593
+ *
+ * Copyright (C) 2023 BayLibre Incorporated - https://www.baylibre.com/
+ */
+
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/interrupt.h>
+#include <linux/ioctl.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include <linux/mfd/tps6594.h>
+
+#include <linux/tps6594_pfsm.h>
+
+#define TPS6594_STARTUP_DEST_MCU_ONLY_VAL 2
+#define TPS6594_STARTUP_DEST_ACTIVE_VAL   3
+#define TPS6594_STARTUP_DEST_SHIFT	  5
+#define TPS6594_STARTUP_DEST_MCU_ONLY	  (TPS6594_STARTUP_DEST_MCU_ONLY_VAL \
+					   << TPS6594_STARTUP_DEST_SHIFT)
+#define TPS6594_STARTUP_DEST_ACTIVE	  (TPS6594_STARTUP_DEST_ACTIVE_VAL \
+					   << TPS6594_STARTUP_DEST_SHIFT)
+
+/*
+ * To update the PMIC firmware, the user must be able to access
+ * page 0 (user registers) and page 1 (NVM control and configuration).
+ */
+#define TPS6594_PMIC_MAX_POS 0x200
+
+#define TPS6594_FILE_TO_PFSM(f) container_of((f)->private_data, struct tps6594_pfsm, miscdev)
+
+/**
+ * struct tps6594_pfsm - device private data structure
+ *
+ * @miscdev: misc device infos
+ * @regmap:  regmap for accessing the device registers
+ * @chip_id: chip identifier of the device
+ */
+struct tps6594_pfsm {
+	struct miscdevice miscdev;
+	struct regmap *regmap;
+	unsigned long chip_id;
+};
+
+static ssize_t tps6594_pfsm_read(struct file *f, char __user *buf,
+				 size_t count, loff_t *ppos)
+{
+	struct tps6594_pfsm *pfsm = TPS6594_FILE_TO_PFSM(f);
+	loff_t pos = *ppos;
+	unsigned int val;
+	int ret;
+	int i;
+
+	if (pos < 0)
+		return -EINVAL;
+	if (pos >= TPS6594_PMIC_MAX_POS)
+		return 0;
+	if (count > TPS6594_PMIC_MAX_POS - pos)
+		count = TPS6594_PMIC_MAX_POS - pos;
+
+	for (i = 0 ; i < count ; i++) {
+		ret = regmap_read(pfsm->regmap, pos + i, &val);
+		if (ret)
+			return ret;
+
+		if (put_user(val, buf + i))
+			return -EFAULT;
+	}
+
+	*ppos = pos + count;
+
+	return count;
+}
+
+static ssize_t tps6594_pfsm_write(struct file *f, const char __user *buf,
+				  size_t count, loff_t *ppos)
+{
+	struct tps6594_pfsm *pfsm = TPS6594_FILE_TO_PFSM(f);
+	loff_t pos = *ppos;
+	char val;
+	int ret;
+	int i;
+
+	if (pos < 0)
+		return -EINVAL;
+	if (pos >= TPS6594_PMIC_MAX_POS || !count)
+		return 0;
+	if (count > TPS6594_PMIC_MAX_POS - pos)
+		count = TPS6594_PMIC_MAX_POS - pos;
+
+	for (i = 0 ; i < count ; i++) {
+		if (get_user(val, buf + i))
+			return -EFAULT;
+
+		ret = regmap_write(pfsm->regmap, pos + i, val);
+		if (ret)
+			return ret;
+	}
+
+	*ppos = pos + count;
+
+	return count;
+}
+
+static int tps6594_pfsm_configure_ret_trig(struct regmap *regmap, u8 gpio_ret, u8 ddr_ret)
+{
+	int ret;
+
+	if (gpio_ret)
+		ret = regmap_set_bits(regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+				      TPS6594_BIT_TRIGGER_I2C(5) | TPS6594_BIT_TRIGGER_I2C(6));
+	else
+		ret = regmap_clear_bits(regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+					TPS6594_BIT_TRIGGER_I2C(5) | TPS6594_BIT_TRIGGER_I2C(6));
+	if (ret)
+		return ret;
+
+	if (ddr_ret)
+		ret = regmap_set_bits(regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+				      TPS6594_BIT_TRIGGER_I2C(7));
+	else
+		ret = regmap_clear_bits(regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+					TPS6594_BIT_TRIGGER_I2C(7));
+
+	return ret;
+}
+
+static long tps6594_pfsm_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
+{
+	struct tps6594_pfsm *pfsm = TPS6594_FILE_TO_PFSM(f);
+	struct pmic_state_opt state_opt;
+	void __user *argp = (void __user *)arg;
+	unsigned int regmap_reg, mask;
+	int ret = -ENOIOCTLCMD;
+
+	switch (cmd) {
+	case PMIC_GOTO_STANDBY:
+		/* Disable LP mode on TPS6594 Family PMIC */
+		if (pfsm->chip_id != TPS65224 && pfsm->chip_id != TPS652G1) {
+			ret = regmap_clear_bits(pfsm->regmap, TPS6594_REG_RTC_CTRL_2,
+						TPS6594_BIT_LP_STANDBY_SEL);
+
+			if (ret)
+				return ret;
+		}
+
+		/* Force trigger */
+		ret = regmap_write_bits(pfsm->regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+					TPS6594_BIT_TRIGGER_I2C(0), TPS6594_BIT_TRIGGER_I2C(0));
+		break;
+	case PMIC_GOTO_LP_STANDBY:
+		/* TPS65224/TPS652G1 does not support LP STANDBY */
+		if (pfsm->chip_id == TPS65224 || pfsm->chip_id == TPS652G1)
+			return ret;
+
+		/* Enable LP mode */
+		ret = regmap_set_bits(pfsm->regmap, TPS6594_REG_RTC_CTRL_2,
+				      TPS6594_BIT_LP_STANDBY_SEL);
+		if (ret)
+			return ret;
+
+		/* Force trigger */
+		ret = regmap_write_bits(pfsm->regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+					TPS6594_BIT_TRIGGER_I2C(0), TPS6594_BIT_TRIGGER_I2C(0));
+		break;
+	case PMIC_UPDATE_PGM:
+		/* Force trigger */
+		ret = regmap_write_bits(pfsm->regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+					TPS6594_BIT_TRIGGER_I2C(3), TPS6594_BIT_TRIGGER_I2C(3));
+		break;
+	case PMIC_SET_ACTIVE_STATE:
+		/* Modify NSLEEP1-2 bits */
+		ret = regmap_set_bits(pfsm->regmap, TPS6594_REG_FSM_NSLEEP_TRIGGERS,
+				      TPS6594_BIT_NSLEEP1B | TPS6594_BIT_NSLEEP2B);
+		break;
+	case PMIC_SET_MCU_ONLY_STATE:
+		/* TPS65224/TPS652G1 does not support MCU_ONLY_STATE */
+		if (pfsm->chip_id == TPS65224 || pfsm->chip_id == TPS652G1)
+			return ret;
+
+		if (copy_from_user(&state_opt, argp, sizeof(state_opt)))
+			return -EFAULT;
+
+		/* Configure retention triggers */
+		ret = tps6594_pfsm_configure_ret_trig(pfsm->regmap, state_opt.gpio_retention,
+						      state_opt.ddr_retention);
+		if (ret)
+			return ret;
+
+		/* Modify NSLEEP1-2 bits */
+		ret = regmap_clear_bits(pfsm->regmap, TPS6594_REG_FSM_NSLEEP_TRIGGERS,
+					TPS6594_BIT_NSLEEP1B);
+		if (ret)
+			return ret;
+
+		ret = regmap_set_bits(pfsm->regmap, TPS6594_REG_FSM_NSLEEP_TRIGGERS,
+				      TPS6594_BIT_NSLEEP2B);
+		break;
+	case PMIC_SET_RETENTION_STATE:
+		if (copy_from_user(&state_opt, argp, sizeof(state_opt)))
+			return -EFAULT;
+
+		/* Configure wake-up destination */
+		if (pfsm->chip_id == TPS65224 || pfsm->chip_id == TPS652G1) {
+			regmap_reg = TPS65224_REG_STARTUP_CTRL;
+			mask = TPS65224_MASK_STARTUP_DEST;
+		} else {
+			regmap_reg = TPS6594_REG_RTC_CTRL_2;
+			mask = TPS6594_MASK_STARTUP_DEST;
+		}
+
+		if (state_opt.mcu_only_startup_dest)
+			ret = regmap_write_bits(pfsm->regmap, regmap_reg,
+						mask, TPS6594_STARTUP_DEST_MCU_ONLY);
+		else
+			ret = regmap_write_bits(pfsm->regmap, regmap_reg,
+						mask, TPS6594_STARTUP_DEST_ACTIVE);
+		if (ret)
+			return ret;
+
+		/* Configure retention triggers */
+		ret = tps6594_pfsm_configure_ret_trig(pfsm->regmap, state_opt.gpio_retention,
+						      state_opt.ddr_retention);
+		if (ret)
+			return ret;
+
+		/* Modify NSLEEP1-2 bits */
+		if (pfsm->chip_id == TPS65224 || pfsm->chip_id == TPS652G1)
+			ret = regmap_clear_bits(pfsm->regmap,
+						TPS6594_REG_FSM_NSLEEP_TRIGGERS,
+						TPS6594_BIT_NSLEEP1B);
+		else
+			ret = regmap_clear_bits(pfsm->regmap,
+						TPS6594_REG_FSM_NSLEEP_TRIGGERS,
+						TPS6594_BIT_NSLEEP2B);
+		break;
+	}
+
+	return ret;
+}
+
+static const struct file_operations tps6594_pfsm_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= generic_file_llseek,
+	.read		= tps6594_pfsm_read,
+	.write		= tps6594_pfsm_write,
+	.unlocked_ioctl	= tps6594_pfsm_ioctl,
+	.compat_ioctl   = compat_ptr_ioctl,
+};
+
+static irqreturn_t tps6594_pfsm_isr(int irq, void *dev_id)
+{
+	struct platform_device *pdev = dev_id;
+	int i;
+
+	for (i = 0 ; i < pdev->num_resources ; i++) {
+		if (irq == platform_get_irq_byname(pdev, pdev->resource[i].name)) {
+			dev_err(pdev->dev.parent, "%s event detected\n", pdev->resource[i].name);
+			return IRQ_HANDLED;
+		}
+	}
+
+	return IRQ_NONE;
+}
+
+static int tps6594_pfsm_probe(struct platform_device *pdev)
+{
+	struct tps6594_pfsm *pfsm;
+	struct tps6594 *tps = dev_get_drvdata(pdev->dev.parent);
+	struct device *dev = &pdev->dev;
+	int irq;
+	int ret;
+	int i;
+
+	pfsm = devm_kzalloc(dev, sizeof(struct tps6594_pfsm), GFP_KERNEL);
+	if (!pfsm)
+		return -ENOMEM;
+
+	pfsm->regmap = tps->regmap;
+
+	pfsm->miscdev.minor = MISC_DYNAMIC_MINOR;
+	pfsm->miscdev.name = devm_kasprintf(dev, GFP_KERNEL, "pfsm-%ld-0x%02x",
+					    tps->chip_id, tps->reg);
+	if (!pfsm->miscdev.name)
+		return -ENOMEM;
+
+	pfsm->miscdev.fops = &tps6594_pfsm_fops;
+	pfsm->miscdev.parent = dev->parent;
+	pfsm->chip_id = tps->chip_id;
+
+	for (i = 0 ; i < pdev->num_resources ; i++) {
+		irq = platform_get_irq_byname(pdev, pdev->resource[i].name);
+		if (irq < 0)
+			return irq;
+
+		ret = devm_request_threaded_irq(dev, irq, NULL,
+						tps6594_pfsm_isr, IRQF_ONESHOT,
+						pdev->resource[i].name, pdev);
+		if (ret)
+			return ret;
+	}
+
+	platform_set_drvdata(pdev, pfsm);
+
+	return misc_register(&pfsm->miscdev);
+}
+
+static void tps6594_pfsm_remove(struct platform_device *pdev)
+{
+	struct tps6594_pfsm *pfsm = platform_get_drvdata(pdev);
+
+	misc_deregister(&pfsm->miscdev);
+}
+
+static struct platform_driver tps6594_pfsm_driver = {
+	.driver	= {
+		.name = "tps6594-pfsm",
+	},
+	.probe = tps6594_pfsm_probe,
+	.remove = tps6594_pfsm_remove,
+};
+
+module_platform_driver(tps6594_pfsm_driver);
+
+MODULE_ALIAS("platform:tps6594-pfsm");
+MODULE_AUTHOR("Julien Panis <jpanis@baylibre.com>");
+MODULE_DESCRIPTION("TPS6594 Pre-configurable Finite State Machine Driver");
+MODULE_LICENSE("GPL");