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, 398 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/wm831x-ts.c b/drivers/input/touchscreen/wm831x-ts.c
new file mode 100644
index 000000000..98f8ec408
--- /dev/null
+++ b/drivers/input/touchscreen/wm831x-ts.c
@@ -0,0 +1,398 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Touchscreen driver for WM831x PMICs
+ *
+ * Copyright 2011 Wolfson Microelectronics plc.
+ * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/pm.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/mfd/wm831x/core.h>
+#include <linux/mfd/wm831x/irq.h>
+#include <linux/mfd/wm831x/pdata.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+/*
+ * R16424 (0x4028) - Touch Control 1
+ */
+#define WM831X_TCH_ENA                          0x8000  /* TCH_ENA */
+#define WM831X_TCH_CVT_ENA                      0x4000  /* TCH_CVT_ENA */
+#define WM831X_TCH_SLPENA                       0x1000  /* TCH_SLPENA */
+#define WM831X_TCH_Z_ENA                        0x0400  /* TCH_Z_ENA */
+#define WM831X_TCH_Y_ENA                        0x0200  /* TCH_Y_ENA */
+#define WM831X_TCH_X_ENA                        0x0100  /* TCH_X_ENA */
+#define WM831X_TCH_DELAY_MASK                   0x00E0  /* TCH_DELAY - [7:5] */
+#define WM831X_TCH_DELAY_SHIFT                       5  /* TCH_DELAY - [7:5] */
+#define WM831X_TCH_DELAY_WIDTH                       3  /* TCH_DELAY - [7:5] */
+#define WM831X_TCH_RATE_MASK                    0x001F  /* TCH_RATE - [4:0] */
+#define WM831X_TCH_RATE_SHIFT                        0  /* TCH_RATE - [4:0] */
+#define WM831X_TCH_RATE_WIDTH                        5  /* TCH_RATE - [4:0] */
+
+/*
+ * R16425 (0x4029) - Touch Control 2
+ */
+#define WM831X_TCH_PD_WK                        0x2000  /* TCH_PD_WK */
+#define WM831X_TCH_5WIRE                        0x1000  /* TCH_5WIRE */
+#define WM831X_TCH_PDONLY                       0x0800  /* TCH_PDONLY */
+#define WM831X_TCH_ISEL                         0x0100  /* TCH_ISEL */
+#define WM831X_TCH_RPU_MASK                     0x000F  /* TCH_RPU - [3:0] */
+#define WM831X_TCH_RPU_SHIFT                         0  /* TCH_RPU - [3:0] */
+#define WM831X_TCH_RPU_WIDTH                         4  /* TCH_RPU - [3:0] */
+
+/*
+ * R16426-8 (0x402A-C) - Touch Data X/Y/X
+ */
+#define WM831X_TCH_PD                           0x8000  /* TCH_PD1 */
+#define WM831X_TCH_DATA_MASK                    0x0FFF  /* TCH_DATA - [11:0] */
+#define WM831X_TCH_DATA_SHIFT                        0  /* TCH_DATA - [11:0] */
+#define WM831X_TCH_DATA_WIDTH                       12  /* TCH_DATA - [11:0] */
+
+struct wm831x_ts {
+	struct input_dev *input_dev;
+	struct wm831x *wm831x;
+	unsigned int data_irq;
+	unsigned int pd_irq;
+	bool pressure;
+	bool pen_down;
+	struct work_struct pd_data_work;
+};
+
+static void wm831x_pd_data_work(struct work_struct *work)
+{
+	struct wm831x_ts *wm831x_ts =
+		container_of(work, struct wm831x_ts, pd_data_work);
+
+	if (wm831x_ts->pen_down) {
+		enable_irq(wm831x_ts->data_irq);
+		dev_dbg(wm831x_ts->wm831x->dev, "IRQ PD->DATA done\n");
+	} else {
+		enable_irq(wm831x_ts->pd_irq);
+		dev_dbg(wm831x_ts->wm831x->dev, "IRQ DATA->PD done\n");
+	}
+}
+
+static irqreturn_t wm831x_ts_data_irq(int irq, void *irq_data)
+{
+	struct wm831x_ts *wm831x_ts = irq_data;
+	struct wm831x *wm831x = wm831x_ts->wm831x;
+	static int data_types[] = { ABS_X, ABS_Y, ABS_PRESSURE };
+	u16 data[3];
+	int count;
+	int i, ret;
+
+	if (wm831x_ts->pressure)
+		count = 3;
+	else
+		count = 2;
+
+	wm831x_set_bits(wm831x, WM831X_INTERRUPT_STATUS_1,
+			WM831X_TCHDATA_EINT, WM831X_TCHDATA_EINT);
+
+	ret = wm831x_bulk_read(wm831x, WM831X_TOUCH_DATA_X, count,
+			       data);
+	if (ret != 0) {
+		dev_err(wm831x->dev, "Failed to read touch data: %d\n",
+			ret);
+		return IRQ_NONE;
+	}
+
+	/*
+	 * We get a pen down reading on every reading, report pen up if any
+	 * individual reading does so.
+	 */
+	wm831x_ts->pen_down = true;
+	for (i = 0; i < count; i++) {
+		if (!(data[i] & WM831X_TCH_PD)) {
+			wm831x_ts->pen_down = false;
+			continue;
+		}
+		input_report_abs(wm831x_ts->input_dev, data_types[i],
+				 data[i] & WM831X_TCH_DATA_MASK);
+	}
+
+	if (!wm831x_ts->pen_down) {
+		/* Switch from data to pen down */
+		dev_dbg(wm831x->dev, "IRQ DATA->PD\n");
+
+		disable_irq_nosync(wm831x_ts->data_irq);
+
+		/* Don't need data any more */
+		wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_1,
+				WM831X_TCH_X_ENA | WM831X_TCH_Y_ENA |
+				WM831X_TCH_Z_ENA, 0);
+
+		/* Flush any final samples that arrived while reading */
+		wm831x_set_bits(wm831x, WM831X_INTERRUPT_STATUS_1,
+				WM831X_TCHDATA_EINT, WM831X_TCHDATA_EINT);
+
+		wm831x_bulk_read(wm831x, WM831X_TOUCH_DATA_X, count, data);
+
+		if (wm831x_ts->pressure)
+			input_report_abs(wm831x_ts->input_dev,
+					 ABS_PRESSURE, 0);
+
+		input_report_key(wm831x_ts->input_dev, BTN_TOUCH, 0);
+
+		schedule_work(&wm831x_ts->pd_data_work);
+	} else {
+		input_report_key(wm831x_ts->input_dev, BTN_TOUCH, 1);
+	}
+
+	input_sync(wm831x_ts->input_dev);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t wm831x_ts_pen_down_irq(int irq, void *irq_data)
+{
+	struct wm831x_ts *wm831x_ts = irq_data;
+	struct wm831x *wm831x = wm831x_ts->wm831x;
+	int ena = 0;
+
+	if (wm831x_ts->pen_down)
+		return IRQ_HANDLED;
+
+	disable_irq_nosync(wm831x_ts->pd_irq);
+
+	/* Start collecting data */
+	if (wm831x_ts->pressure)
+		ena |= WM831X_TCH_Z_ENA;
+
+	wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_1,
+			WM831X_TCH_X_ENA | WM831X_TCH_Y_ENA | WM831X_TCH_Z_ENA,
+			WM831X_TCH_X_ENA | WM831X_TCH_Y_ENA | ena);
+
+	wm831x_set_bits(wm831x, WM831X_INTERRUPT_STATUS_1,
+			WM831X_TCHPD_EINT, WM831X_TCHPD_EINT);
+
+	wm831x_ts->pen_down = true;
+
+	/* Switch from pen down to data */
+	dev_dbg(wm831x->dev, "IRQ PD->DATA\n");
+	schedule_work(&wm831x_ts->pd_data_work);
+
+	return IRQ_HANDLED;
+}
+
+static int wm831x_ts_input_open(struct input_dev *idev)
+{
+	struct wm831x_ts *wm831x_ts = input_get_drvdata(idev);
+	struct wm831x *wm831x = wm831x_ts->wm831x;
+
+	wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_1,
+			WM831X_TCH_ENA | WM831X_TCH_CVT_ENA |
+			WM831X_TCH_X_ENA | WM831X_TCH_Y_ENA |
+			WM831X_TCH_Z_ENA, WM831X_TCH_ENA);
+
+	wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_1,
+			WM831X_TCH_CVT_ENA, WM831X_TCH_CVT_ENA);
+
+	return 0;
+}
+
+static void wm831x_ts_input_close(struct input_dev *idev)
+{
+	struct wm831x_ts *wm831x_ts = input_get_drvdata(idev);
+	struct wm831x *wm831x = wm831x_ts->wm831x;
+
+	/* Shut the controller down, disabling all other functionality too */
+	wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_1,
+			WM831X_TCH_ENA | WM831X_TCH_X_ENA |
+			WM831X_TCH_Y_ENA | WM831X_TCH_Z_ENA, 0);
+
+	/* Make sure any pending IRQs are done, the above will prevent
+	 * new ones firing.
+	 */
+	synchronize_irq(wm831x_ts->data_irq);
+	synchronize_irq(wm831x_ts->pd_irq);
+
+	/* Make sure the IRQ completion work is quiesced */
+	flush_work(&wm831x_ts->pd_data_work);
+
+	/* If we ended up with the pen down then make sure we revert back
+	 * to pen detection state for the next time we start up.
+	 */
+	if (wm831x_ts->pen_down) {
+		disable_irq(wm831x_ts->data_irq);
+		enable_irq(wm831x_ts->pd_irq);
+		wm831x_ts->pen_down = false;
+	}
+}
+
+static int wm831x_ts_probe(struct platform_device *pdev)
+{
+	struct wm831x_ts *wm831x_ts;
+	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
+	struct wm831x_pdata *core_pdata = dev_get_platdata(pdev->dev.parent);
+	struct wm831x_touch_pdata *pdata = NULL;
+	struct input_dev *input_dev;
+	int error, irqf;
+
+	if (core_pdata)
+		pdata = core_pdata->touch;
+
+	wm831x_ts = devm_kzalloc(&pdev->dev, sizeof(struct wm831x_ts),
+				 GFP_KERNEL);
+	input_dev = devm_input_allocate_device(&pdev->dev);
+	if (!wm831x_ts || !input_dev) {
+		error = -ENOMEM;
+		goto err_alloc;
+	}
+
+	wm831x_ts->wm831x = wm831x;
+	wm831x_ts->input_dev = input_dev;
+	INIT_WORK(&wm831x_ts->pd_data_work, wm831x_pd_data_work);
+
+	/*
+	 * If we have a direct IRQ use it, otherwise use the interrupt
+	 * from the WM831x IRQ controller.
+	 */
+	wm831x_ts->data_irq = wm831x_irq(wm831x,
+					 platform_get_irq_byname(pdev,
+								 "TCHDATA"));
+	if (pdata && pdata->data_irq)
+		wm831x_ts->data_irq = pdata->data_irq;
+
+	wm831x_ts->pd_irq = wm831x_irq(wm831x,
+				       platform_get_irq_byname(pdev, "TCHPD"));
+	if (pdata && pdata->pd_irq)
+		wm831x_ts->pd_irq = pdata->pd_irq;
+
+	if (pdata)
+		wm831x_ts->pressure = pdata->pressure;
+	else
+		wm831x_ts->pressure = true;
+
+	/* Five wire touchscreens can't report pressure */
+	if (pdata && pdata->fivewire) {
+		wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_2,
+				WM831X_TCH_5WIRE, WM831X_TCH_5WIRE);
+
+		/* Pressure measurements are not possible for five wire mode */
+		WARN_ON(pdata->pressure && pdata->fivewire);
+		wm831x_ts->pressure = false;
+	} else {
+		wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_2,
+				WM831X_TCH_5WIRE, 0);
+	}
+
+	if (pdata) {
+		switch (pdata->isel) {
+		default:
+			dev_err(&pdev->dev, "Unsupported ISEL setting: %d\n",
+				pdata->isel);
+			fallthrough;
+		case 200:
+		case 0:
+			wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_2,
+					WM831X_TCH_ISEL, 0);
+			break;
+		case 400:
+			wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_2,
+					WM831X_TCH_ISEL, WM831X_TCH_ISEL);
+			break;
+		}
+	}
+
+	wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_2,
+			WM831X_TCH_PDONLY, 0);
+
+	/* Default to 96 samples/sec */
+	wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_1,
+			WM831X_TCH_RATE_MASK, 6);
+
+	if (pdata && pdata->data_irqf)
+		irqf = pdata->data_irqf;
+	else
+		irqf = IRQF_TRIGGER_HIGH;
+
+	error = request_threaded_irq(wm831x_ts->data_irq,
+				     NULL, wm831x_ts_data_irq,
+				     irqf | IRQF_ONESHOT | IRQF_NO_AUTOEN,
+				     "Touchscreen data", wm831x_ts);
+	if (error) {
+		dev_err(&pdev->dev, "Failed to request data IRQ %d: %d\n",
+			wm831x_ts->data_irq, error);
+		goto err_alloc;
+	}
+
+	if (pdata && pdata->pd_irqf)
+		irqf = pdata->pd_irqf;
+	else
+		irqf = IRQF_TRIGGER_HIGH;
+
+	error = request_threaded_irq(wm831x_ts->pd_irq,
+				     NULL, wm831x_ts_pen_down_irq,
+				     irqf | IRQF_ONESHOT,
+				     "Touchscreen pen down", wm831x_ts);
+	if (error) {
+		dev_err(&pdev->dev, "Failed to request pen down IRQ %d: %d\n",
+			wm831x_ts->pd_irq, error);
+		goto err_data_irq;
+	}
+
+	/* set up touch configuration */
+	input_dev->name = "WM831x touchscreen";
+	input_dev->phys = "wm831x";
+	input_dev->open = wm831x_ts_input_open;
+	input_dev->close = wm831x_ts_input_close;
+
+	__set_bit(EV_ABS, input_dev->evbit);
+	__set_bit(EV_KEY, input_dev->evbit);
+	__set_bit(BTN_TOUCH, input_dev->keybit);
+
+	input_set_abs_params(input_dev, ABS_X, 0, 4095, 5, 0);
+	input_set_abs_params(input_dev, ABS_Y, 0, 4095, 5, 0);
+	if (wm831x_ts->pressure)
+		input_set_abs_params(input_dev, ABS_PRESSURE, 0, 4095, 5, 0);
+
+	input_set_drvdata(input_dev, wm831x_ts);
+	input_dev->dev.parent = &pdev->dev;
+
+	error = input_register_device(input_dev);
+	if (error)
+		goto err_pd_irq;
+
+	platform_set_drvdata(pdev, wm831x_ts);
+	return 0;
+
+err_pd_irq:
+	free_irq(wm831x_ts->pd_irq, wm831x_ts);
+err_data_irq:
+	free_irq(wm831x_ts->data_irq, wm831x_ts);
+err_alloc:
+
+	return error;
+}
+
+static void wm831x_ts_remove(struct platform_device *pdev)
+{
+	struct wm831x_ts *wm831x_ts = platform_get_drvdata(pdev);
+
+	free_irq(wm831x_ts->pd_irq, wm831x_ts);
+	free_irq(wm831x_ts->data_irq, wm831x_ts);
+}
+
+static struct platform_driver wm831x_ts_driver = {
+	.driver = {
+		.name = "wm831x-touch",
+	},
+	.probe = wm831x_ts_probe,
+	.remove = wm831x_ts_remove,
+};
+module_platform_driver(wm831x_ts_driver);
+
+/* Module information */
+MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
+MODULE_DESCRIPTION("WM831x PMIC touchscreen driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:wm831x-touch");