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, 366 insertions, 0 deletions

diff --git a/drivers/input/keyboard/tm2-touchkey.c b/drivers/input/keyboard/tm2-touchkey.c
new file mode 100644
index 000000000..967bbe553
--- /dev/null
+++ b/drivers/input/keyboard/tm2-touchkey.c
@@ -0,0 +1,366 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TM2 touchkey device driver
+ *
+ * Copyright 2005 Phil Blundell
+ * Copyright 2016 Samsung Electronics Co., Ltd.
+ *
+ * Author: Beomho Seo <beomho.seo@samsung.com>
+ * Author: Jaechul Lee <jcsing.lee@samsung.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pm.h>
+#include <linux/regulator/consumer.h>
+
+#define TM2_TOUCHKEY_DEV_NAME		"tm2-touchkey"
+
+#define ARIES_TOUCHKEY_CMD_LED_ON	0x1
+#define ARIES_TOUCHKEY_CMD_LED_OFF	0x2
+#define TM2_TOUCHKEY_CMD_LED_ON		0x10
+#define TM2_TOUCHKEY_CMD_LED_OFF	0x20
+#define TM2_TOUCHKEY_BIT_PRESS_EV	BIT(3)
+#define TM2_TOUCHKEY_BIT_KEYCODE	GENMASK(2, 0)
+#define TM2_TOUCHKEY_LED_VOLTAGE_MIN	2500000
+#define TM2_TOUCHKEY_LED_VOLTAGE_MAX	3300000
+
+struct touchkey_variant {
+	u8 keycode_reg;
+	u8 base_reg;
+	u8 cmd_led_on;
+	u8 cmd_led_off;
+	bool no_reg;
+	bool fixed_regulator;
+};
+
+struct tm2_touchkey_data {
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	struct led_classdev led_dev;
+	struct regulator *vdd;
+	struct regulator_bulk_data regulators[3];
+	const struct touchkey_variant *variant;
+	u32 keycodes[4];
+	int num_keycodes;
+};
+
+static const struct touchkey_variant tm2_touchkey_variant = {
+	.keycode_reg = 0x03,
+	.base_reg = 0x00,
+	.cmd_led_on = TM2_TOUCHKEY_CMD_LED_ON,
+	.cmd_led_off = TM2_TOUCHKEY_CMD_LED_OFF,
+};
+
+static const struct touchkey_variant midas_touchkey_variant = {
+	.keycode_reg = 0x00,
+	.base_reg = 0x00,
+	.cmd_led_on = TM2_TOUCHKEY_CMD_LED_ON,
+	.cmd_led_off = TM2_TOUCHKEY_CMD_LED_OFF,
+};
+
+static struct touchkey_variant aries_touchkey_variant = {
+	.no_reg = true,
+	.fixed_regulator = true,
+	.cmd_led_on = ARIES_TOUCHKEY_CMD_LED_ON,
+	.cmd_led_off = ARIES_TOUCHKEY_CMD_LED_OFF,
+};
+
+static const struct touchkey_variant tc360_touchkey_variant = {
+	.keycode_reg = 0x00,
+	.base_reg = 0x00,
+	.fixed_regulator = true,
+	.cmd_led_on = TM2_TOUCHKEY_CMD_LED_ON,
+	.cmd_led_off = TM2_TOUCHKEY_CMD_LED_OFF,
+};
+
+static int tm2_touchkey_led_brightness_set(struct led_classdev *led_dev,
+					    enum led_brightness brightness)
+{
+	struct tm2_touchkey_data *touchkey =
+		container_of(led_dev, struct tm2_touchkey_data, led_dev);
+	u32 volt;
+	u8 data;
+
+	if (brightness == LED_OFF) {
+		volt = TM2_TOUCHKEY_LED_VOLTAGE_MIN;
+		data = touchkey->variant->cmd_led_off;
+	} else {
+		volt = TM2_TOUCHKEY_LED_VOLTAGE_MAX;
+		data = touchkey->variant->cmd_led_on;
+	}
+
+	if (!touchkey->variant->fixed_regulator)
+		regulator_set_voltage(touchkey->vdd, volt, volt);
+
+	return touchkey->variant->no_reg ?
+		i2c_smbus_write_byte(touchkey->client, data) :
+		i2c_smbus_write_byte_data(touchkey->client,
+					  touchkey->variant->base_reg, data);
+}
+
+static int tm2_touchkey_power_enable(struct tm2_touchkey_data *touchkey)
+{
+	int error;
+
+	error = regulator_bulk_enable(ARRAY_SIZE(touchkey->regulators),
+				      touchkey->regulators);
+	if (error)
+		return error;
+
+	/* waiting for device initialization, at least 150ms */
+	msleep(150);
+
+	return 0;
+}
+
+static void tm2_touchkey_power_disable(void *data)
+{
+	struct tm2_touchkey_data *touchkey = data;
+
+	regulator_bulk_disable(ARRAY_SIZE(touchkey->regulators),
+			       touchkey->regulators);
+}
+
+static irqreturn_t tm2_touchkey_irq_handler(int irq, void *devid)
+{
+	struct tm2_touchkey_data *touchkey = devid;
+	int data;
+	int index;
+	int i;
+
+	if (touchkey->variant->no_reg)
+		data = i2c_smbus_read_byte(touchkey->client);
+	else
+		data = i2c_smbus_read_byte_data(touchkey->client,
+						touchkey->variant->keycode_reg);
+	if (data < 0) {
+		dev_err(&touchkey->client->dev,
+			"failed to read i2c data: %d\n", data);
+		goto out;
+	}
+
+	index = (data & TM2_TOUCHKEY_BIT_KEYCODE) - 1;
+	if (index < 0 || index >= touchkey->num_keycodes) {
+		dev_warn(&touchkey->client->dev,
+			 "invalid keycode index %d\n", index);
+		goto out;
+	}
+
+	input_event(touchkey->input_dev, EV_MSC, MSC_SCAN, index);
+
+	if (data & TM2_TOUCHKEY_BIT_PRESS_EV) {
+		for (i = 0; i < touchkey->num_keycodes; i++)
+			input_report_key(touchkey->input_dev,
+					 touchkey->keycodes[i], 0);
+	} else {
+		input_report_key(touchkey->input_dev,
+				 touchkey->keycodes[index], 1);
+	}
+
+	input_sync(touchkey->input_dev);
+
+out:
+	if (touchkey->variant->fixed_regulator &&
+				data & TM2_TOUCHKEY_BIT_PRESS_EV) {
+		/* touch turns backlight on, so make sure we're in sync */
+		if (touchkey->led_dev.brightness == LED_OFF)
+			tm2_touchkey_led_brightness_set(&touchkey->led_dev,
+							LED_OFF);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int tm2_touchkey_probe(struct i2c_client *client)
+{
+	struct device_node *np = client->dev.of_node;
+	struct tm2_touchkey_data *touchkey;
+	int error;
+	int i;
+
+	if (!i2c_check_functionality(client->adapter,
+			I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA)) {
+		dev_err(&client->dev, "incompatible I2C adapter\n");
+		return -EIO;
+	}
+
+	touchkey = devm_kzalloc(&client->dev, sizeof(*touchkey), GFP_KERNEL);
+	if (!touchkey)
+		return -ENOMEM;
+
+	touchkey->client = client;
+	i2c_set_clientdata(client, touchkey);
+
+	touchkey->variant = of_device_get_match_data(&client->dev);
+
+	touchkey->regulators[0].supply = "vcc";
+	touchkey->regulators[1].supply = "vdd";
+	touchkey->regulators[2].supply = "vddio";
+	error = devm_regulator_bulk_get(&client->dev,
+					ARRAY_SIZE(touchkey->regulators),
+					touchkey->regulators);
+	if (error) {
+		dev_err(&client->dev, "failed to get regulators: %d\n", error);
+		return error;
+	}
+
+	/* Save VDD for easy access */
+	touchkey->vdd = touchkey->regulators[1].consumer;
+
+	touchkey->num_keycodes = of_property_read_variable_u32_array(np,
+					"linux,keycodes", touchkey->keycodes, 0,
+					ARRAY_SIZE(touchkey->keycodes));
+	if (touchkey->num_keycodes <= 0) {
+		/* default keycodes */
+		touchkey->keycodes[0] = KEY_PHONE;
+		touchkey->keycodes[1] = KEY_BACK;
+		touchkey->num_keycodes = 2;
+	}
+
+	error = tm2_touchkey_power_enable(touchkey);
+	if (error) {
+		dev_err(&client->dev, "failed to power up device: %d\n", error);
+		return error;
+	}
+
+	error = devm_add_action_or_reset(&client->dev,
+					 tm2_touchkey_power_disable, touchkey);
+	if (error) {
+		dev_err(&client->dev,
+			"failed to install poweroff handler: %d\n", error);
+		return error;
+	}
+
+	/* input device */
+	touchkey->input_dev = devm_input_allocate_device(&client->dev);
+	if (!touchkey->input_dev) {
+		dev_err(&client->dev, "failed to allocate input device\n");
+		return -ENOMEM;
+	}
+
+	touchkey->input_dev->name = TM2_TOUCHKEY_DEV_NAME;
+	touchkey->input_dev->id.bustype = BUS_I2C;
+
+	touchkey->input_dev->keycode = touchkey->keycodes;
+	touchkey->input_dev->keycodemax = touchkey->num_keycodes;
+	touchkey->input_dev->keycodesize = sizeof(touchkey->keycodes[0]);
+
+	input_set_capability(touchkey->input_dev, EV_MSC, MSC_SCAN);
+	for (i = 0; i < touchkey->num_keycodes; i++)
+		input_set_capability(touchkey->input_dev, EV_KEY,
+				     touchkey->keycodes[i]);
+
+	error = input_register_device(touchkey->input_dev);
+	if (error) {
+		dev_err(&client->dev,
+			"failed to register input device: %d\n", error);
+		return error;
+	}
+
+	error = devm_request_threaded_irq(&client->dev, client->irq,
+					  NULL, tm2_touchkey_irq_handler,
+					  IRQF_ONESHOT,
+					  TM2_TOUCHKEY_DEV_NAME, touchkey);
+	if (error) {
+		dev_err(&client->dev,
+			"failed to request threaded irq: %d\n", error);
+		return error;
+	}
+
+	/* led device */
+	touchkey->led_dev.name = TM2_TOUCHKEY_DEV_NAME;
+	touchkey->led_dev.brightness = LED_ON;
+	touchkey->led_dev.max_brightness = LED_ON;
+	touchkey->led_dev.brightness_set_blocking =
+					tm2_touchkey_led_brightness_set;
+
+	error = devm_led_classdev_register(&client->dev, &touchkey->led_dev);
+	if (error) {
+		dev_err(&client->dev,
+			"failed to register touchkey led: %d\n", error);
+		return error;
+	}
+
+	if (touchkey->variant->fixed_regulator)
+		tm2_touchkey_led_brightness_set(&touchkey->led_dev, LED_ON);
+
+	return 0;
+}
+
+static int tm2_touchkey_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct tm2_touchkey_data *touchkey = i2c_get_clientdata(client);
+
+	disable_irq(client->irq);
+	tm2_touchkey_power_disable(touchkey);
+
+	return 0;
+}
+
+static int tm2_touchkey_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct tm2_touchkey_data *touchkey = i2c_get_clientdata(client);
+	int ret;
+
+	enable_irq(client->irq);
+
+	ret = tm2_touchkey_power_enable(touchkey);
+	if (ret)
+		dev_err(dev, "failed to enable power: %d\n", ret);
+
+	return ret;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(tm2_touchkey_pm_ops,
+				tm2_touchkey_suspend, tm2_touchkey_resume);
+
+static const struct i2c_device_id tm2_touchkey_id_table[] = {
+	{ .name = TM2_TOUCHKEY_DEV_NAME },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tm2_touchkey_id_table);
+
+static const struct of_device_id tm2_touchkey_of_match[] = {
+	{
+		.compatible = "cypress,tm2-touchkey",
+		.data = &tm2_touchkey_variant,
+	}, {
+		.compatible = "cypress,midas-touchkey",
+		.data = &midas_touchkey_variant,
+	}, {
+		.compatible = "cypress,aries-touchkey",
+		.data = &aries_touchkey_variant,
+	}, {
+		.compatible = "coreriver,tc360-touchkey",
+		.data = &tc360_touchkey_variant,
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, tm2_touchkey_of_match);
+
+static struct i2c_driver tm2_touchkey_driver = {
+	.driver = {
+		.name = TM2_TOUCHKEY_DEV_NAME,
+		.pm = pm_sleep_ptr(&tm2_touchkey_pm_ops),
+		.of_match_table = tm2_touchkey_of_match,
+	},
+	.probe = tm2_touchkey_probe,
+	.id_table = tm2_touchkey_id_table,
+};
+module_i2c_driver(tm2_touchkey_driver);
+
+MODULE_AUTHOR("Beomho Seo <beomho.seo@samsung.com>");
+MODULE_AUTHOR("Jaechul Lee <jcsing.lee@samsung.com>");
+MODULE_DESCRIPTION("Samsung touchkey driver");
+MODULE_LICENSE("GPL v2");