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, 272 insertions, 0 deletions

diff --git a/drivers/regulator/max8649.c b/drivers/regulator/max8649.c
new file mode 100644
index 000000000..2d1740524
--- /dev/null
+++ b/drivers/regulator/max8649.c
@@ -0,0 +1,272 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Regulators driver for Maxim max8649
+ *
+ * Copyright (C) 2009-2010 Marvell International Ltd.
+ *      Haojian Zhuang <haojian.zhuang@marvell.com>
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/driver.h>
+#include <linux/slab.h>
+#include <linux/regulator/max8649.h>
+#include <linux/regmap.h>
+
+#define MAX8649_DCDC_VMIN	750000		/* uV */
+#define MAX8649_DCDC_VMAX	1380000		/* uV */
+#define MAX8649_DCDC_STEP	10000		/* uV */
+#define MAX8649_VOL_MASK	0x3f
+
+/* Registers */
+#define MAX8649_MODE0		0x00
+#define MAX8649_MODE1		0x01
+#define MAX8649_MODE2		0x02
+#define MAX8649_MODE3		0x03
+#define MAX8649_CONTROL		0x04
+#define MAX8649_SYNC		0x05
+#define MAX8649_RAMP		0x06
+#define MAX8649_CHIP_ID1	0x08
+#define MAX8649_CHIP_ID2	0x09
+
+/* Bits */
+#define MAX8649_EN_PD		(1 << 7)
+#define MAX8649_VID0_PD		(1 << 6)
+#define MAX8649_VID1_PD		(1 << 5)
+#define MAX8649_VID_MASK	(3 << 5)
+
+#define MAX8649_FORCE_PWM	(1 << 7)
+#define MAX8649_SYNC_EXTCLK	(1 << 6)
+
+#define MAX8649_EXT_MASK	(3 << 6)
+
+#define MAX8649_RAMP_MASK	(7 << 5)
+#define MAX8649_RAMP_DOWN	(1 << 1)
+
+struct max8649_regulator_info {
+	struct device		*dev;
+	struct regmap		*regmap;
+
+	unsigned	mode:2;	/* bit[1:0] = VID1, VID0 */
+	unsigned	extclk_freq:2;
+	unsigned	extclk:1;
+	unsigned	ramp_timing:3;
+	unsigned	ramp_down:1;
+};
+
+static int max8649_enable_time(struct regulator_dev *rdev)
+{
+	struct max8649_regulator_info *info = rdev_get_drvdata(rdev);
+	int voltage, rate, ret;
+	unsigned int val;
+
+	/* get voltage */
+	ret = regmap_read(info->regmap, rdev->desc->vsel_reg, &val);
+	if (ret != 0)
+		return ret;
+	val &= MAX8649_VOL_MASK;
+	voltage = regulator_list_voltage_linear(rdev, (unsigned char)val);
+
+	/* get rate */
+	ret = regmap_read(info->regmap, MAX8649_RAMP, &val);
+	if (ret != 0)
+		return ret;
+	ret = (val & MAX8649_RAMP_MASK) >> 5;
+	rate = (32 * 1000) >> ret;	/* uV/uS */
+
+	return DIV_ROUND_UP(voltage, rate);
+}
+
+static int max8649_set_mode(struct regulator_dev *rdev, unsigned int mode)
+{
+	struct max8649_regulator_info *info = rdev_get_drvdata(rdev);
+
+	switch (mode) {
+	case REGULATOR_MODE_FAST:
+		regmap_update_bits(info->regmap, rdev->desc->vsel_reg,
+				   MAX8649_FORCE_PWM, MAX8649_FORCE_PWM);
+		break;
+	case REGULATOR_MODE_NORMAL:
+		regmap_update_bits(info->regmap, rdev->desc->vsel_reg,
+				   MAX8649_FORCE_PWM, 0);
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static unsigned int max8649_get_mode(struct regulator_dev *rdev)
+{
+	struct max8649_regulator_info *info = rdev_get_drvdata(rdev);
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(info->regmap, rdev->desc->vsel_reg, &val);
+	if (ret != 0)
+		return ret;
+	if (val & MAX8649_FORCE_PWM)
+		return REGULATOR_MODE_FAST;
+	return REGULATOR_MODE_NORMAL;
+}
+
+static const struct regulator_ops max8649_dcdc_ops = {
+	.set_voltage_sel = regulator_set_voltage_sel_regmap,
+	.get_voltage_sel = regulator_get_voltage_sel_regmap,
+	.list_voltage	= regulator_list_voltage_linear,
+	.map_voltage	= regulator_map_voltage_linear,
+	.enable		= regulator_enable_regmap,
+	.disable	= regulator_disable_regmap,
+	.is_enabled	= regulator_is_enabled_regmap,
+	.enable_time	= max8649_enable_time,
+	.set_mode	= max8649_set_mode,
+	.get_mode	= max8649_get_mode,
+
+};
+
+static struct regulator_desc dcdc_desc = {
+	.name		= "max8649",
+	.ops		= &max8649_dcdc_ops,
+	.type		= REGULATOR_VOLTAGE,
+	.n_voltages	= 1 << 6,
+	.owner		= THIS_MODULE,
+	.vsel_mask	= MAX8649_VOL_MASK,
+	.min_uV		= MAX8649_DCDC_VMIN,
+	.uV_step	= MAX8649_DCDC_STEP,
+	.enable_reg	= MAX8649_CONTROL,
+	.enable_mask	= MAX8649_EN_PD,
+	.enable_is_inverted = true,
+};
+
+static const struct regmap_config max8649_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static int max8649_regulator_probe(struct i2c_client *client)
+{
+	struct max8649_platform_data *pdata = dev_get_platdata(&client->dev);
+	struct max8649_regulator_info *info = NULL;
+	struct regulator_dev *regulator;
+	struct regulator_config config = { };
+	unsigned int val;
+	unsigned char data;
+	int ret;
+
+	info = devm_kzalloc(&client->dev, sizeof(struct max8649_regulator_info),
+			    GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	info->regmap = devm_regmap_init_i2c(client, &max8649_regmap_config);
+	if (IS_ERR(info->regmap)) {
+		ret = PTR_ERR(info->regmap);
+		dev_err(&client->dev, "Failed to allocate register map: %d\n", ret);
+		return ret;
+	}
+
+	info->dev = &client->dev;
+	i2c_set_clientdata(client, info);
+
+	info->mode = pdata->mode;
+	switch (info->mode) {
+	case 0:
+		dcdc_desc.vsel_reg = MAX8649_MODE0;
+		break;
+	case 1:
+		dcdc_desc.vsel_reg = MAX8649_MODE1;
+		break;
+	case 2:
+		dcdc_desc.vsel_reg = MAX8649_MODE2;
+		break;
+	case 3:
+		dcdc_desc.vsel_reg = MAX8649_MODE3;
+		break;
+	default:
+		break;
+	}
+
+	ret = regmap_read(info->regmap, MAX8649_CHIP_ID1, &val);
+	if (ret != 0) {
+		dev_err(info->dev, "Failed to detect ID of MAX8649:%d\n",
+			ret);
+		return ret;
+	}
+	dev_info(info->dev, "Detected MAX8649 (ID:%x)\n", val);
+
+	/* enable VID0 & VID1 */
+	regmap_update_bits(info->regmap, MAX8649_CONTROL, MAX8649_VID_MASK, 0);
+
+	/* enable/disable external clock synchronization */
+	info->extclk = pdata->extclk;
+	data = (info->extclk) ? MAX8649_SYNC_EXTCLK : 0;
+	regmap_update_bits(info->regmap, dcdc_desc.vsel_reg,
+			   MAX8649_SYNC_EXTCLK, data);
+	if (info->extclk) {
+		/* set external clock frequency */
+		info->extclk_freq = pdata->extclk_freq;
+		regmap_update_bits(info->regmap, MAX8649_SYNC, MAX8649_EXT_MASK,
+				   info->extclk_freq << 6);
+	}
+
+	if (pdata->ramp_timing) {
+		info->ramp_timing = pdata->ramp_timing;
+		regmap_update_bits(info->regmap, MAX8649_RAMP, MAX8649_RAMP_MASK,
+				   info->ramp_timing << 5);
+	}
+
+	info->ramp_down = pdata->ramp_down;
+	if (info->ramp_down) {
+		regmap_update_bits(info->regmap, MAX8649_RAMP, MAX8649_RAMP_DOWN,
+				   MAX8649_RAMP_DOWN);
+	}
+
+	config.dev = &client->dev;
+	config.init_data = pdata->regulator;
+	config.driver_data = info;
+	config.regmap = info->regmap;
+
+	regulator = devm_regulator_register(&client->dev, &dcdc_desc,
+						  &config);
+	if (IS_ERR(regulator)) {
+		dev_err(info->dev, "failed to register regulator %s\n",
+			dcdc_desc.name);
+		return PTR_ERR(regulator);
+	}
+
+	return 0;
+}
+
+static const struct i2c_device_id max8649_id[] = {
+	{ .name = "max8649" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max8649_id);
+
+static struct i2c_driver max8649_driver = {
+	.probe		= max8649_regulator_probe,
+	.driver		= {
+		.name	= "max8649",
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+	.id_table	= max8649_id,
+};
+
+static int __init max8649_init(void)
+{
+	return i2c_add_driver(&max8649_driver);
+}
+subsys_initcall(max8649_init);
+
+static void __exit max8649_exit(void)
+{
+	i2c_del_driver(&max8649_driver);
+}
+module_exit(max8649_exit);
+
+/* Module information */
+MODULE_DESCRIPTION("MAXIM 8649 voltage regulator driver");
+MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
+MODULE_LICENSE("GPL");