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, 126 insertions, 0 deletions

diff --git a/drivers/input/misc/tps6594-pwrbutton.c b/drivers/input/misc/tps6594-pwrbutton.c
new file mode 100644
index 000000000..cd039b386
--- /dev/null
+++ b/drivers/input/misc/tps6594-pwrbutton.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * power button driver for TI TPS6594 PMICs
+ *
+ * Copyright (C) 2025 Critical Link LLC - https://www.criticallink.com/
+ */
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mfd/tps6594.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+struct tps6594_pwrbutton {
+	struct device *dev;
+	struct input_dev *idev;
+	char phys[32];
+};
+
+static irqreturn_t tps6594_pb_push_irq(int irq, void *_pwr)
+{
+	struct tps6594_pwrbutton *pwr = _pwr;
+
+	input_report_key(pwr->idev, KEY_POWER, 1);
+	pm_wakeup_event(pwr->dev, 0);
+	input_sync(pwr->idev);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t tps6594_pb_release_irq(int irq, void *_pwr)
+{
+	struct tps6594_pwrbutton *pwr = _pwr;
+
+	input_report_key(pwr->idev, KEY_POWER, 0);
+	input_sync(pwr->idev);
+
+	return IRQ_HANDLED;
+}
+
+static int tps6594_pb_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct tps6594_pwrbutton *pwr;
+	struct input_dev *idev;
+	int error;
+	int push_irq;
+	int release_irq;
+
+	pwr = devm_kzalloc(dev, sizeof(*pwr), GFP_KERNEL);
+	if (!pwr)
+		return -ENOMEM;
+
+	idev = devm_input_allocate_device(dev);
+	if (!idev)
+		return -ENOMEM;
+
+	idev->name = pdev->name;
+	snprintf(pwr->phys, sizeof(pwr->phys), "%s/input0",
+		 pdev->name);
+	idev->phys = pwr->phys;
+	idev->id.bustype = BUS_I2C;
+
+	input_set_capability(idev, EV_KEY, KEY_POWER);
+
+	pwr->dev = dev;
+	pwr->idev = idev;
+	device_init_wakeup(dev, true);
+
+	push_irq = platform_get_irq(pdev, 0);
+	if (push_irq < 0)
+		return -EINVAL;
+
+	release_irq = platform_get_irq(pdev, 1);
+	if (release_irq < 0)
+		return -EINVAL;
+
+	error = devm_request_threaded_irq(dev, push_irq, NULL,
+					  tps6594_pb_push_irq,
+					  IRQF_ONESHOT,
+					  pdev->resource[0].name, pwr);
+	if (error) {
+		dev_err(dev, "failed to request push IRQ #%d: %d\n", push_irq,
+			error);
+		return error;
+	}
+
+	error = devm_request_threaded_irq(dev, release_irq, NULL,
+					  tps6594_pb_release_irq,
+					  IRQF_ONESHOT,
+					  pdev->resource[1].name, pwr);
+	if (error) {
+		dev_err(dev, "failed to request release IRQ #%d: %d\n",
+			release_irq, error);
+		return error;
+	}
+
+	error = input_register_device(idev);
+	if (error) {
+		dev_err(dev, "Can't register power button: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct platform_device_id tps6594_pwrbtn_id_table[] = {
+	{ "tps6594-pwrbutton", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, tps6594_pwrbtn_id_table);
+
+static struct platform_driver tps6594_pb_driver = {
+	.probe = tps6594_pb_probe,
+	.driver = {
+		.name = "tps6594_pwrbutton",
+	},
+	.id_table = tps6594_pwrbtn_id_table,
+};
+module_platform_driver(tps6594_pb_driver);
+
+MODULE_DESCRIPTION("TPS6594 Power Button");
+MODULE_LICENSE("GPL");