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, 101 insertions, 0 deletions

diff --git a/drivers/reset/reset-imx-scu.c b/drivers/reset/reset-imx-scu.c
new file mode 100644
index 000000000..919fc29f9
--- /dev/null
+++ b/drivers/reset/reset-imx-scu.c
@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2025 NXP
+ * Frank Li <Frank.Li@nxp.com>
+ */
+#include <linux/firmware/imx/svc/misc.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+
+#include <dt-bindings/firmware/imx/rsrc.h>
+
+struct imx_scu_reset {
+	struct reset_controller_dev rc;
+	struct imx_sc_ipc *ipc_handle;
+};
+
+static struct imx_scu_reset *to_imx_scu(struct reset_controller_dev *rc)
+{
+	return container_of(rc, struct imx_scu_reset, rc);
+}
+
+struct imx_scu_id_map {
+	u32 resource_id;
+	u32 command_id;
+};
+
+static const struct imx_scu_id_map imx_scu_id_map[] = {
+	{ IMX_SC_R_CSI_0, IMX_SC_C_MIPI_RESET },
+	{ IMX_SC_R_CSI_1, IMX_SC_C_MIPI_RESET },
+};
+
+static int imx_scu_reset_assert(struct reset_controller_dev *rc, unsigned long id)
+{
+	struct imx_scu_reset *priv = to_imx_scu(rc);
+
+	return imx_sc_misc_set_control(priv->ipc_handle, imx_scu_id_map[id].resource_id,
+				       imx_scu_id_map[id].command_id, true);
+}
+
+static const struct reset_control_ops imx_scu_reset_ops = {
+	.assert = imx_scu_reset_assert,
+};
+
+static int imx_scu_xlate(struct reset_controller_dev *rc, const struct of_phandle_args *reset_spec)
+{
+	int i;
+
+	for (i = 0; i < rc->nr_resets; i++)
+		if (reset_spec->args[0] == imx_scu_id_map[i].resource_id)
+			return i;
+
+	return -EINVAL;
+}
+
+static int imx_scu_reset_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct imx_scu_reset *priv;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, &priv->rc);
+
+	ret = imx_scu_get_handle(&priv->ipc_handle);
+	if (ret)
+		return dev_err_probe(dev, ret, "sc_misc_MIPI get ipc handle failed!\n");
+
+	priv->rc.ops = &imx_scu_reset_ops;
+	priv->rc.owner = THIS_MODULE;
+	priv->rc.of_node = dev->of_node;
+	priv->rc.of_reset_n_cells = 1;
+	priv->rc.of_xlate = imx_scu_xlate;
+	priv->rc.nr_resets = ARRAY_SIZE(imx_scu_id_map);
+
+	return devm_reset_controller_register(dev, &priv->rc);
+}
+
+static const struct of_device_id imx_scu_reset_ids[] = {
+	{ .compatible = "fsl,imx-scu-reset", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, imx_scu_reset_ids);
+
+static struct platform_driver imx_scu_reset_driver = {
+	.probe          = imx_scu_reset_probe,
+	.driver = {
+		.name = "scu-reset",
+		.of_match_table = imx_scu_reset_ids,
+	},
+};
+module_platform_driver(imx_scu_reset_driver);
+
+MODULE_AUTHOR("Frank Li <Frank.Li@nxp.com>");
+MODULE_DESCRIPTION("i.MX scu reset driver");
+MODULE_LICENSE("GPL");