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, 127 insertions, 0 deletions

diff --git a/drivers/reset/reset-sky1-audss.c b/drivers/reset/reset-sky1-audss.c
new file mode 100644
index 000000000..d9735db68
--- /dev/null
+++ b/drivers/reset/reset-sky1-audss.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Cix Sky1 Audio Subsystem reset controller driver
+ *
+ * Copyright 2026 Cix Technology Group Co., Ltd.
+ */
+
+#include <dt-bindings/reset/cix,sky1-audss-cru.h>
+
+#include <linux/auxiliary_bus.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+
+#define SKY1_RESET_SLEEP_US			50
+
+#define AUDSS_SW_RST			0x78
+
+struct sky1_audss_reset_map {
+	unsigned int offset;
+	unsigned int mask;
+};
+
+struct sky1_audss_reset {
+	struct reset_controller_dev rcdev;
+	struct regmap *regmap;
+	const struct sky1_audss_reset_map *map;
+};
+
+static const struct sky1_audss_reset_map sky1_audss_reset_map[] = {
+	[AUDSS_I2S0_SW_RST]   = { AUDSS_SW_RST, BIT(0) },
+	[AUDSS_I2S1_SW_RST]   = { AUDSS_SW_RST, BIT(1) },
+	[AUDSS_I2S2_SW_RST]   = { AUDSS_SW_RST, BIT(2) },
+	[AUDSS_I2S3_SW_RST]   = { AUDSS_SW_RST, BIT(3) },
+	[AUDSS_I2S4_SW_RST]   = { AUDSS_SW_RST, BIT(4) },
+	[AUDSS_I2S5_SW_RST]   = { AUDSS_SW_RST, BIT(5) },
+	[AUDSS_I2S6_SW_RST]   = { AUDSS_SW_RST, BIT(6) },
+	[AUDSS_I2S7_SW_RST]   = { AUDSS_SW_RST, BIT(7) },
+	[AUDSS_I2S8_SW_RST]   = { AUDSS_SW_RST, BIT(8) },
+	[AUDSS_I2S9_SW_RST]   = { AUDSS_SW_RST, BIT(9) },
+	[AUDSS_WDT_SW_RST]    = { AUDSS_SW_RST, BIT(10) },
+	[AUDSS_TIMER_SW_RST]  = { AUDSS_SW_RST, BIT(11) },
+	[AUDSS_MB0_SW_RST]    = { AUDSS_SW_RST, BIT(12) },
+	[AUDSS_MB1_SW_RST]    = { AUDSS_SW_RST, BIT(13) },
+	[AUDSS_HDA_SW_RST]    = { AUDSS_SW_RST, BIT(14) },
+	[AUDSS_DMAC_SW_RST]   = { AUDSS_SW_RST, BIT(15) },
+};
+
+static struct sky1_audss_reset *to_sky1_audss_reset(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct sky1_audss_reset, rcdev);
+}
+
+static int sky1_audss_reset_set(struct reset_controller_dev *rcdev,
+				unsigned long id, bool assert)
+{
+	struct sky1_audss_reset *priv = to_sky1_audss_reset(rcdev);
+	const struct sky1_audss_reset_map *signal = &priv->map[id];
+	int ret;
+
+	ret = regmap_assign_bits(priv->regmap, signal->offset,
+				 signal->mask, !assert);
+	if (ret)
+		return ret;
+
+	fsleep(SKY1_RESET_SLEEP_US);
+	return 0;
+}
+
+static int sky1_audss_reset_assert(struct reset_controller_dev *rcdev,
+				   unsigned long id)
+{
+	return sky1_audss_reset_set(rcdev, id, true);
+}
+
+static int sky1_audss_reset_deassert(struct reset_controller_dev *rcdev,
+				     unsigned long id)
+{
+	return sky1_audss_reset_set(rcdev, id, false);
+}
+
+static const struct reset_control_ops sky1_audss_reset_ops = {
+	.assert   = sky1_audss_reset_assert,
+	.deassert = sky1_audss_reset_deassert,
+};
+
+static int sky1_audss_reset_probe(struct auxiliary_device *adev,
+				  const struct auxiliary_device_id *id)
+{
+	struct sky1_audss_reset *priv;
+	struct device *dev = &adev->dev;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->regmap = dev_get_regmap(dev->parent, NULL);
+	if (!priv->regmap)
+		return dev_err_probe(dev, -ENODEV, "failed to get parent regmap\n");
+
+	priv->map = sky1_audss_reset_map;
+	priv->rcdev.owner = THIS_MODULE;
+	priv->rcdev.nr_resets = ARRAY_SIZE(sky1_audss_reset_map);
+	priv->rcdev.ops = &sky1_audss_reset_ops;
+	priv->rcdev.of_node = dev->of_node;
+	priv->rcdev.dev = dev;
+
+	return devm_reset_controller_register(dev, &priv->rcdev);
+}
+
+static const struct auxiliary_device_id sky1_audss_reset_ids[] = {
+	{ .name = "clk_sky1_audss.reset" },
+	{ }
+};
+MODULE_DEVICE_TABLE(auxiliary, sky1_audss_reset_ids);
+
+static struct auxiliary_driver sky1_audss_reset_driver = {
+	.probe = sky1_audss_reset_probe,
+	.id_table = sky1_audss_reset_ids,
+};
+module_auxiliary_driver(sky1_audss_reset_driver);
+
+MODULE_AUTHOR("Joakim Zhang <joakim.zhang@cixtech.com>");
+MODULE_DESCRIPTION("Cix Sky1 Audio Subsystem reset driver");
+MODULE_LICENSE("GPL");