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, 298 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/88pm860x-ts.c b/drivers/input/touchscreen/88pm860x-ts.c
new file mode 100644
index 000000000..0468ce2b2
--- /dev/null
+++ b/drivers/input/touchscreen/88pm860x-ts.c
@@ -0,0 +1,298 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Touchscreen driver for Marvell 88PM860x
+ *
+ * Copyright (C) 2009 Marvell International Ltd.
+ * 	Haojian Zhuang <haojian.zhuang@marvell.com>
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/mfd/88pm860x.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+
+#define MEAS_LEN		(8)
+#define ACCURATE_BIT		(12)
+
+/* touch register */
+#define MEAS_EN3		(0x52)
+
+#define MEAS_TSIX_1		(0x8D)
+#define MEAS_TSIX_2		(0x8E)
+#define MEAS_TSIY_1		(0x8F)
+#define MEAS_TSIY_2		(0x90)
+#define MEAS_TSIZ1_1		(0x91)
+#define MEAS_TSIZ1_2		(0x92)
+#define MEAS_TSIZ2_1		(0x93)
+#define MEAS_TSIZ2_2		(0x94)
+
+/* bit definitions of touch */
+#define MEAS_PD_EN		(1 << 3)
+#define MEAS_TSIX_EN		(1 << 4)
+#define MEAS_TSIY_EN		(1 << 5)
+#define MEAS_TSIZ1_EN		(1 << 6)
+#define MEAS_TSIZ2_EN		(1 << 7)
+
+struct pm860x_touch {
+	struct input_dev *idev;
+	struct i2c_client *i2c;
+	struct pm860x_chip *chip;
+	int irq;
+	int res_x;		/* resistor of Xplate */
+};
+
+static irqreturn_t pm860x_touch_handler(int irq, void *data)
+{
+	struct pm860x_touch *touch = data;
+	struct pm860x_chip *chip = touch->chip;
+	unsigned char buf[MEAS_LEN];
+	int x, y, pen_down;
+	int z1, z2, rt = 0;
+	int ret;
+
+	ret = pm860x_bulk_read(touch->i2c, MEAS_TSIX_1, MEAS_LEN, buf);
+	if (ret < 0)
+		goto out;
+
+	pen_down = buf[1] & (1 << 6);
+	x = ((buf[0] & 0xFF) << 4) | (buf[1] & 0x0F);
+	y = ((buf[2] & 0xFF) << 4) | (buf[3] & 0x0F);
+	z1 = ((buf[4] & 0xFF) << 4) | (buf[5] & 0x0F);
+	z2 = ((buf[6] & 0xFF) << 4) | (buf[7] & 0x0F);
+
+	if (pen_down) {
+		if ((x != 0) && (z1 != 0) && (touch->res_x != 0)) {
+			rt = z2 / z1 - 1;
+			rt = (rt * touch->res_x * x) >> ACCURATE_BIT;
+			dev_dbg(chip->dev, "z1:%d, z2:%d, rt:%d\n",
+				z1, z2, rt);
+		}
+		input_report_abs(touch->idev, ABS_X, x);
+		input_report_abs(touch->idev, ABS_Y, y);
+		input_report_abs(touch->idev, ABS_PRESSURE, rt);
+		input_report_key(touch->idev, BTN_TOUCH, 1);
+		dev_dbg(chip->dev, "pen down at [%d, %d].\n", x, y);
+	} else {
+		input_report_abs(touch->idev, ABS_PRESSURE, 0);
+		input_report_key(touch->idev, BTN_TOUCH, 0);
+		dev_dbg(chip->dev, "pen release\n");
+	}
+	input_sync(touch->idev);
+
+out:
+	return IRQ_HANDLED;
+}
+
+static int pm860x_touch_open(struct input_dev *dev)
+{
+	struct pm860x_touch *touch = input_get_drvdata(dev);
+	int data, ret;
+
+	data = MEAS_PD_EN | MEAS_TSIX_EN | MEAS_TSIY_EN
+		| MEAS_TSIZ1_EN | MEAS_TSIZ2_EN;
+	ret = pm860x_set_bits(touch->i2c, MEAS_EN3, data, data);
+	if (ret < 0)
+		goto out;
+	return 0;
+out:
+	return ret;
+}
+
+static void pm860x_touch_close(struct input_dev *dev)
+{
+	struct pm860x_touch *touch = input_get_drvdata(dev);
+	int data;
+
+	data = MEAS_PD_EN | MEAS_TSIX_EN | MEAS_TSIY_EN
+		| MEAS_TSIZ1_EN | MEAS_TSIZ2_EN;
+	pm860x_set_bits(touch->i2c, MEAS_EN3, data, 0);
+}
+
+#ifdef CONFIG_OF
+static int pm860x_touch_dt_init(struct platform_device *pdev,
+					  struct pm860x_chip *chip,
+					  int *res_x)
+{
+	struct i2c_client *i2c = (chip->id == CHIP_PM8607) ? chip->client \
+				 : chip->companion;
+	int data, n, ret;
+	if (!pdev->dev.parent->of_node)
+		return -ENODEV;
+
+	struct device_node *np __free(device_node) =
+		of_get_child_by_name(pdev->dev.parent->of_node, "touch");
+	if (!np) {
+		dev_err(&pdev->dev, "Can't find touch node\n");
+		return -EINVAL;
+	}
+	/* set GPADC MISC1 register */
+	data = 0;
+	if (!of_property_read_u32(np, "marvell,88pm860x-gpadc-prebias", &n))
+		data |= (n << 1) & PM8607_GPADC_PREBIAS_MASK;
+	if (!of_property_read_u32(np, "marvell,88pm860x-gpadc-slot-cycle", &n))
+		data |= (n << 3) & PM8607_GPADC_SLOT_CYCLE_MASK;
+	if (!of_property_read_u32(np, "marvell,88pm860x-gpadc-off-scale", &n))
+		data |= (n << 5) & PM8607_GPADC_OFF_SCALE_MASK;
+	if (!of_property_read_u32(np, "marvell,88pm860x-gpadc-sw-cal", &n))
+		data |= (n << 7) & PM8607_GPADC_SW_CAL_MASK;
+	if (data) {
+		ret = pm860x_reg_write(i2c, PM8607_GPADC_MISC1, data);
+		if (ret < 0)
+			return -EINVAL;
+	}
+	/* set tsi prebias time */
+	if (!of_property_read_u32(np, "marvell,88pm860x-tsi-prebias", &data)) {
+		ret = pm860x_reg_write(i2c, PM8607_TSI_PREBIAS, data);
+		if (ret < 0)
+			return -EINVAL;
+	}
+	/* set prebias & prechg time of pen detect */
+	data = 0;
+	if (!of_property_read_u32(np, "marvell,88pm860x-pen-prebias", &n))
+		data |= n & PM8607_PD_PREBIAS_MASK;
+	if (!of_property_read_u32(np, "marvell,88pm860x-pen-prechg", &n))
+		data |= n & PM8607_PD_PRECHG_MASK;
+	if (data) {
+		ret = pm860x_reg_write(i2c, PM8607_PD_PREBIAS, data);
+		if (ret < 0)
+			return -EINVAL;
+	}
+	of_property_read_u32(np, "marvell,88pm860x-resistor-X", res_x);
+
+	return 0;
+}
+#else
+#define pm860x_touch_dt_init(x, y, z)	(-1)
+#endif
+
+static int pm860x_touch_probe(struct platform_device *pdev)
+{
+	struct pm860x_chip *chip = dev_get_drvdata(pdev->dev.parent);
+	struct pm860x_touch_pdata *pdata = dev_get_platdata(&pdev->dev);
+	struct pm860x_touch *touch;
+	struct i2c_client *i2c = (chip->id == CHIP_PM8607) ? chip->client \
+				 : chip->companion;
+	int irq, ret, res_x = 0, data = 0;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return -EINVAL;
+
+	if (pm860x_touch_dt_init(pdev, chip, &res_x)) {
+		if (pdata) {
+			/* set GPADC MISC1 register */
+			data = 0;
+			data |= (pdata->gpadc_prebias << 1)
+				& PM8607_GPADC_PREBIAS_MASK;
+			data |= (pdata->slot_cycle << 3)
+				& PM8607_GPADC_SLOT_CYCLE_MASK;
+			data |= (pdata->off_scale << 5)
+				& PM8607_GPADC_OFF_SCALE_MASK;
+			data |= (pdata->sw_cal << 7)
+				& PM8607_GPADC_SW_CAL_MASK;
+			if (data) {
+				ret = pm860x_reg_write(i2c,
+					PM8607_GPADC_MISC1, data);
+				if (ret < 0)
+					return -EINVAL;
+			}
+			/* set tsi prebias time */
+			if (pdata->tsi_prebias) {
+				data = pdata->tsi_prebias;
+				ret = pm860x_reg_write(i2c,
+					PM8607_TSI_PREBIAS, data);
+				if (ret < 0)
+					return -EINVAL;
+			}
+			/* set prebias & prechg time of pen detect */
+			data = 0;
+			data |= pdata->pen_prebias
+				& PM8607_PD_PREBIAS_MASK;
+			data |= (pdata->pen_prechg << 5)
+				& PM8607_PD_PRECHG_MASK;
+			if (data) {
+				ret = pm860x_reg_write(i2c,
+					PM8607_PD_PREBIAS, data);
+				if (ret < 0)
+					return -EINVAL;
+			}
+			res_x = pdata->res_x;
+		} else {
+			dev_err(&pdev->dev, "failed to get platform data\n");
+			return -EINVAL;
+		}
+	}
+	/* enable GPADC */
+	ret = pm860x_set_bits(i2c, PM8607_GPADC_MISC1, PM8607_GPADC_EN,
+			      PM8607_GPADC_EN);
+	if (ret)
+		return ret;
+
+	touch = devm_kzalloc(&pdev->dev, sizeof(struct pm860x_touch),
+			     GFP_KERNEL);
+	if (!touch)
+		return -ENOMEM;
+
+	touch->idev = devm_input_allocate_device(&pdev->dev);
+	if (!touch->idev) {
+		dev_err(&pdev->dev, "Failed to allocate input device!\n");
+		return -ENOMEM;
+	}
+
+	touch->idev->name = "88pm860x-touch";
+	touch->idev->phys = "88pm860x/input0";
+	touch->idev->id.bustype = BUS_I2C;
+	touch->idev->dev.parent = &pdev->dev;
+	touch->idev->open = pm860x_touch_open;
+	touch->idev->close = pm860x_touch_close;
+	touch->chip = chip;
+	touch->i2c = i2c;
+	touch->irq = irq;
+	touch->res_x = res_x;
+	input_set_drvdata(touch->idev, touch);
+
+	ret = devm_request_threaded_irq(&pdev->dev, touch->irq, NULL,
+					pm860x_touch_handler, IRQF_ONESHOT,
+					"touch", touch);
+	if (ret < 0)
+		return ret;
+
+	__set_bit(EV_ABS, touch->idev->evbit);
+	__set_bit(ABS_X, touch->idev->absbit);
+	__set_bit(ABS_Y, touch->idev->absbit);
+	__set_bit(ABS_PRESSURE, touch->idev->absbit);
+	__set_bit(EV_SYN, touch->idev->evbit);
+	__set_bit(EV_KEY, touch->idev->evbit);
+	__set_bit(BTN_TOUCH, touch->idev->keybit);
+
+	input_set_abs_params(touch->idev, ABS_X, 0, 1 << ACCURATE_BIT, 0, 0);
+	input_set_abs_params(touch->idev, ABS_Y, 0, 1 << ACCURATE_BIT, 0, 0);
+	input_set_abs_params(touch->idev, ABS_PRESSURE, 0, 1 << ACCURATE_BIT,
+				0, 0);
+
+	ret = input_register_device(touch->idev);
+	if (ret < 0) {
+		dev_err(chip->dev, "Failed to register touch!\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static struct platform_driver pm860x_touch_driver = {
+	.driver	= {
+		.name	= "88pm860x-touch",
+	},
+	.probe	= pm860x_touch_probe,
+};
+module_platform_driver(pm860x_touch_driver);
+
+MODULE_DESCRIPTION("Touchscreen driver for Marvell Semiconductor 88PM860x");
+MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:88pm860x-touch");
+