x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 526 insertions, 0 deletions

diff --git a/drivers/regulator/fp9931.c b/drivers/regulator/fp9931.c
new file mode 100644
index 000000000..ff743a8b0
--- /dev/null
+++ b/drivers/regulator/fp9931.c
@@ -0,0 +1,526 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (C) 2025 Andreas Kemnade
+
+/* Datasheet: https://www.fitipower.com/dl/file/flXa6hIchVeu0W3K */
+
+#include <linux/cleanup.h>
+#include <linux/completion.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/hwmon.h>
+#include <linux/pm_runtime.h>
+#include <linux/property.h>
+#include <linux/regulator/consumer.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regmap.h>
+
+#define FP9931_REG_TMST_VALUE 0
+#define FP9931_REG_VCOM_SETTING 1
+#define FP9931_REG_VPOSNEG_SETTING 2
+#define FP9931_REG_PWRON_DELAY 3
+#define FP9931_REG_CONTROL_REG1 11
+
+#define PGOOD_TIMEOUT_MSECS 200
+
+struct fp9931_data {
+	struct device *dev;
+	struct regmap *regmap;
+	struct regulator *vin_reg;
+	struct gpio_desc *pgood_gpio;
+	struct gpio_desc *en_gpio;
+	struct gpio_desc *en_ts_gpio;
+	struct completion pgood_completion;
+	int pgood_irq;
+};
+
+static const unsigned int VPOSNEG_table[] = {
+	7040000,  7040000,  7040000,  7040000,  7040000,            /* 00h-04h */
+	7260000,  7490000,  7710000,  7930000,  8150000,  8380000,  /* 05h-0Ah */
+	8600000,  8820000,  9040000,  9270000,  9490000,  9710000,  /* 0Bh-10h */
+	9940000,  10160000, 10380000, 10600000, 10830000, 11050000, /* 11h-16h */
+	11270000, 11490000, 11720000, 11940000, 12160000, 12380000, /* 17h-1Ch */
+	12610000, 12830000, 13050000, 13280000, 13500000, 13720000, /* 1Dh-22h */
+	13940000, 14170000, 14390000, 14610000, 14830000, 15060000, /* 23h-28h */
+	/* 29h-3Fh: clamped to 15.06V per datasheet */
+	15060000, 15060000, 15060000, 15060000, 15060000, 15060000,
+	15060000, 15060000, 15060000, 15060000, 15060000, 15060000,
+	15060000, 15060000, 15060000, 15060000, 15060000, 15060000,
+	15060000, 15060000, 15060000, 15060000, 15060000,
+};
+
+static const struct hwmon_channel_info *fp9931_info[] = {
+	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
+	NULL
+};
+
+static int setup_timings(struct fp9931_data *data)
+{
+	u32 tdly[4];
+	u8 tdlys = 0;
+	int i;
+	int ret;
+
+	ret = device_property_count_u32(data->dev, "fitipower,tdly-ms");
+	if (ret == -EINVAL) /* property is optional */
+		return 0;
+
+	if (ret < 0)
+		return ret;
+
+	if (ret != ARRAY_SIZE(tdly)) {
+		dev_err(data->dev, "invalid delay specification");
+		return -EINVAL;
+	}
+
+	ret = device_property_read_u32_array(data->dev, "fitipower,tdly-ms",
+					     tdly, ARRAY_SIZE(tdly));
+	if (ret)
+		return ret;
+
+	for (i = ARRAY_SIZE(tdly) - 1; i >= 0; i--) {
+		if (tdly[i] > 4 || tdly[i] == 3)
+			return -EINVAL;
+
+		if (tdly[i] == 4) /* convert from ms */
+			tdly[i] = 3;
+
+		tdlys <<= 2;
+		tdlys |= tdly[i];
+	}
+
+	ret = pm_runtime_resume_and_get(data->dev);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_write(data->regmap, FP9931_REG_PWRON_DELAY, tdlys);
+	pm_runtime_put_autosuspend(data->dev);
+
+	return ret;
+}
+
+static int fp9931_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+			     u32 attr, int channel, long *temp)
+{
+	struct fp9931_data *data = dev_get_drvdata(dev);
+	unsigned int val;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(data->dev);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_read(data->regmap, FP9931_REG_TMST_VALUE, &val);
+	if (!ret)
+		*temp = (s8)val * 1000;
+
+	pm_runtime_put_autosuspend(data->dev);
+
+	return ret;
+}
+
+static umode_t fp9931_hwmon_is_visible(const void *data,
+				       enum hwmon_sensor_types type,
+				       u32 attr, int channel)
+{
+	return 0444;
+}
+
+static const struct hwmon_ops fp9931_hwmon_ops = {
+	.is_visible = fp9931_hwmon_is_visible,
+	.read = fp9931_hwmon_read,
+};
+
+static const struct hwmon_chip_info fp9931_chip_info = {
+	.ops = &fp9931_hwmon_ops,
+	.info = fp9931_info,
+};
+
+static int fp9931_runtime_suspend(struct device *dev)
+{
+	int ret = 0;
+	struct fp9931_data *data = dev_get_drvdata(dev);
+
+	if (data->en_ts_gpio)
+		gpiod_set_value_cansleep(data->en_ts_gpio, 0);
+
+	if (data->vin_reg) {
+		ret = regulator_disable(data->vin_reg);
+		regcache_mark_dirty(data->regmap);
+	}
+
+	return ret;
+}
+
+static int fp9931_runtime_resume(struct device *dev)
+{
+	int ret = 0;
+	struct fp9931_data *data = dev_get_drvdata(dev);
+
+	if (data->vin_reg)
+		ret = regulator_enable(data->vin_reg);
+
+	if (ret)
+		return ret;
+
+	if (data->en_ts_gpio) {
+		gpiod_set_value_cansleep(data->en_ts_gpio, 1);
+		/* wait for one ADC conversion to have sane temperature */
+		usleep_range(10000, 15000);
+	}
+
+	ret = regcache_sync(data->regmap);
+
+	return ret;
+}
+
+static bool fp9931_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return reg == FP9931_REG_TMST_VALUE;
+}
+
+static const struct reg_default fp9931_reg_default = {
+	.reg = FP9931_REG_VCOM_SETTING,
+	.def = 0x80,
+};
+
+static const struct regmap_config regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = 12,
+	.cache_type = REGCACHE_FLAT,
+	.volatile_reg = fp9931_volatile_reg,
+	.reg_defaults = &fp9931_reg_default,
+	.num_reg_defaults = 1,
+};
+
+static void disable_nopm(void *d)
+{
+	struct fp9931_data *data = d;
+
+	fp9931_runtime_suspend(data->dev);
+}
+
+static int fp9931_v3p3_enable(struct regulator_dev *rdev)
+{
+	struct fp9931_data *data = rdev_get_drvdata(rdev);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(data->dev);
+	if (ret < 0)
+		return ret;
+
+	ret = regulator_enable_regmap(rdev);
+	if (ret < 0)
+		pm_runtime_put_autosuspend(data->dev);
+
+	return ret;
+}
+
+static int fp9931_v3p3_disable(struct regulator_dev *rdev)
+{
+	struct fp9931_data *data = rdev_get_drvdata(rdev);
+	int ret;
+
+	ret = regulator_disable_regmap(rdev);
+	pm_runtime_put_autosuspend(data->dev);
+
+	return ret;
+}
+
+static int fp9931_v3p3_is_enabled(struct regulator_dev *rdev)
+{
+	struct fp9931_data *data = rdev_get_drvdata(rdev);
+	int ret;
+
+	if (pm_runtime_status_suspended(data->dev))
+		return 0;
+
+	ret = pm_runtime_resume_and_get(data->dev);
+	if (ret < 0)
+		return 0;
+
+	ret = regulator_is_enabled_regmap(rdev);
+
+	pm_runtime_put_autosuspend(data->dev);
+	return ret;
+}
+
+static const struct regulator_ops fp9931_v3p3ops = {
+	.list_voltage = regulator_list_voltage_linear,
+	.enable = fp9931_v3p3_enable,
+	.disable = fp9931_v3p3_disable,
+	.is_enabled = fp9931_v3p3_is_enabled,
+};
+
+static int fp9931_check_powergood(struct regulator_dev *rdev)
+{
+	struct fp9931_data *data = rdev_get_drvdata(rdev);
+
+	if (pm_runtime_status_suspended(data->dev))
+		return 0;
+
+	return gpiod_get_value_cansleep(data->pgood_gpio);
+}
+
+static int fp9931_get_voltage_sel(struct regulator_dev *rdev)
+{
+	struct fp9931_data *data = rdev_get_drvdata(rdev);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(data->dev);
+	if (ret < 0)
+		return ret;
+
+	ret = regulator_get_voltage_sel_regmap(rdev);
+	pm_runtime_put_autosuspend(data->dev);
+
+	return ret;
+}
+
+static int fp9931_set_voltage_sel(struct regulator_dev *rdev, unsigned int selector)
+{
+	struct fp9931_data *data = rdev_get_drvdata(rdev);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(data->dev);
+	if (ret < 0)
+		return ret;
+
+	ret = regulator_set_voltage_sel_regmap(rdev, selector);
+	pm_runtime_put_autosuspend(data->dev);
+
+	return ret;
+}
+
+static irqreturn_t pgood_handler(int irq, void *dev_id)
+{
+	struct fp9931_data *data = dev_id;
+
+	complete(&data->pgood_completion);
+
+	return IRQ_HANDLED;
+}
+
+static int fp9931_set_enable(struct regulator_dev *rdev)
+{
+	struct fp9931_data *data = rdev_get_drvdata(rdev);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(data->dev);
+	if (ret < 0)
+		return ret;
+
+	reinit_completion(&data->pgood_completion);
+	gpiod_set_value_cansleep(data->en_gpio, 1);
+	dev_dbg(data->dev, "turning on...");
+	wait_for_completion_timeout(&data->pgood_completion,
+				    msecs_to_jiffies(PGOOD_TIMEOUT_MSECS));
+	dev_dbg(data->dev, "turned on");
+	if (gpiod_get_value_cansleep(data->pgood_gpio) != 1) {
+		pm_runtime_put_autosuspend(data->dev);
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static int fp9931_clear_enable(struct regulator_dev *rdev)
+{
+	struct fp9931_data *data = rdev_get_drvdata(rdev);
+
+	gpiod_set_value_cansleep(data->en_gpio, 0);
+	pm_runtime_put_autosuspend(data->dev);
+	return 0;
+}
+
+static const struct regulator_ops fp9931_vcom_ops = {
+	.list_voltage = regulator_list_voltage_linear,
+	.map_voltage = regulator_map_voltage_linear,
+	.enable = fp9931_set_enable,
+	.disable = fp9931_clear_enable,
+	.is_enabled = fp9931_check_powergood,
+	.set_voltage_sel = fp9931_set_voltage_sel,
+	.get_voltage_sel = fp9931_get_voltage_sel,
+};
+
+static const struct regulator_ops fp9931_vposneg_ops = {
+	.list_voltage = regulator_list_voltage_table,
+	.map_voltage = regulator_map_voltage_ascend,
+	/* gets enabled by enabling vcom, too */
+	.is_enabled = fp9931_check_powergood,
+	.set_voltage_sel = fp9931_set_voltage_sel,
+	.get_voltage_sel = fp9931_get_voltage_sel,
+};
+
+static const struct regulator_desc regulators[] = {
+	{
+		.name = "v3p3",
+		.of_match = of_match_ptr("v3p3"),
+		.regulators_node = of_match_ptr("regulators"),
+		.id = 0,
+		.ops = &fp9931_v3p3ops,
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+		.enable_reg = FP9931_REG_CONTROL_REG1,
+		.enable_mask = BIT(1),
+		.n_voltages = 1,
+		.min_uV = 3300000
+	},
+	{
+		.name = "vposneg",
+		.of_match = of_match_ptr("vposneg"),
+		.regulators_node = of_match_ptr("regulators"),
+		.id = 1,
+		.ops = &fp9931_vposneg_ops,
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+		.n_voltages = ARRAY_SIZE(VPOSNEG_table),
+		.vsel_reg = FP9931_REG_VPOSNEG_SETTING,
+		.vsel_mask = 0x3F,
+		.volt_table = VPOSNEG_table,
+	},
+	{
+		.name = "vcom",
+		.of_match = of_match_ptr("vcom"),
+		.regulators_node = of_match_ptr("regulators"),
+		.id = 2,
+		.ops = &fp9931_vcom_ops,
+		.type = REGULATOR_VOLTAGE,
+		.owner = THIS_MODULE,
+		.n_voltages = 255,
+		.min_uV = 0,
+		.uV_step = 5000000 / 255,
+		.vsel_reg = FP9931_REG_VCOM_SETTING,
+		.vsel_mask = 0xFF
+	},
+};
+
+static int fp9931_probe(struct i2c_client *client)
+{
+	struct fp9931_data *data;
+	struct regulator_config config = { };
+	struct regulator_dev *rdev;
+	int ret = 0;
+	int i;
+
+	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->regmap = devm_regmap_init_i2c(client, &regmap_config);
+	if (IS_ERR(data->regmap))
+		return dev_err_probe(&client->dev, PTR_ERR(data->regmap),
+				     "failed to allocate regmap!\n");
+
+	data->vin_reg = devm_regulator_get(&client->dev, "vin");
+	if (IS_ERR(data->vin_reg))
+		return dev_err_probe(&client->dev, PTR_ERR(data->vin_reg),
+				     "failed to get vin regulator\n");
+
+	data->pgood_gpio = devm_gpiod_get(&client->dev, "pg", GPIOD_IN);
+	if (IS_ERR(data->pgood_gpio))
+		return dev_err_probe(&client->dev,
+				     PTR_ERR(data->pgood_gpio),
+				     "failed to get power good gpio\n");
+
+	data->pgood_irq = gpiod_to_irq(data->pgood_gpio);
+	if (data->pgood_irq < 0)
+		return data->pgood_irq;
+
+	data->en_gpio = devm_gpiod_get(&client->dev, "enable", GPIOD_OUT_LOW);
+	if (IS_ERR(data->en_gpio))
+		return dev_err_probe(&client->dev, PTR_ERR(data->en_gpio),
+				     "failed to get en gpio\n");
+
+	data->en_ts_gpio = devm_gpiod_get_optional(&client->dev, "en-ts", GPIOD_OUT_LOW);
+	if (IS_ERR(data->en_ts_gpio))
+		return dev_err_probe(&client->dev,
+				     PTR_ERR(data->en_ts_gpio),
+				     "failed to get en gpio\n");
+
+	data->dev = &client->dev;
+	i2c_set_clientdata(client, data);
+
+	init_completion(&data->pgood_completion);
+
+	ret = devm_request_threaded_irq(&client->dev, data->pgood_irq, NULL,
+					pgood_handler,
+					IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+					"PGOOD", data);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "failed to request irq\n");
+
+	if (IS_ENABLED(CONFIG_PM)) {
+		devm_pm_runtime_enable(&client->dev);
+		pm_runtime_set_autosuspend_delay(&client->dev, 4000);
+		pm_runtime_use_autosuspend(&client->dev);
+	} else {
+		ret = fp9931_runtime_resume(&client->dev);
+		if (ret < 0)
+			return ret;
+
+		devm_add_action_or_reset(&client->dev, disable_nopm, data);
+	}
+
+	ret = setup_timings(data);
+	if (ret)
+		return dev_err_probe(&client->dev, ret, "failed to setup timings\n");
+
+	config.driver_data = data;
+	config.dev = &client->dev;
+	config.regmap = data->regmap;
+
+	for (i = 0; i < ARRAY_SIZE(regulators); i++) {
+		rdev = devm_regulator_register(&client->dev, &regulators[i],
+					       &config);
+		if (IS_ERR(rdev))
+			return dev_err_probe(&client->dev, PTR_ERR(rdev),
+					     "failed to register %s regulator\n",
+					     regulators[i].name);
+	}
+
+	if (IS_REACHABLE(CONFIG_HWMON)) {
+		struct device *hwmon_dev;
+
+		hwmon_dev = devm_hwmon_device_register_with_info(&client->dev, "fp9931", data,
+								 &fp9931_chip_info, NULL);
+		if (IS_ERR(hwmon_dev))
+			dev_notice(&client->dev, "failed to register hwmon\n");
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops fp9931_pm_ops = {
+	SET_RUNTIME_PM_OPS(fp9931_runtime_suspend, fp9931_runtime_resume, NULL)
+};
+
+static const struct of_device_id fp9931_dt_ids[] = {
+	{
+		.compatible = "fitipower,fp9931",
+	}, {
+		/* sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(of, fp9931_dt_ids);
+
+static struct i2c_driver fp9931_i2c_driver = {
+	.driver = {
+		   .name = "fp9931",
+		   .of_match_table = fp9931_dt_ids,
+		   .pm = &fp9931_pm_ops,
+	},
+	.probe = fp9931_probe,
+};
+
+module_i2c_driver(fp9931_i2c_driver);
+
+/* Module information */
+MODULE_DESCRIPTION("FP9931 regulator driver");
+MODULE_LICENSE("GPL");
+