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, 195 insertions, 0 deletions

diff --git a/drivers/gpu/host1x/mipi.c b/drivers/gpu/host1x/mipi.c
new file mode 100644
index 000000000..988681423
--- /dev/null
+++ b/drivers/gpu/host1x/mipi.c
@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2013 NVIDIA Corporation
+ * Copyright (C) 2025 Svyatoslav Ryhel <clamor95@gmail.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/tegra-mipi-cal.h>
+
+/* only need to support one provider */
+static struct {
+	struct device_node *np;
+	const struct tegra_mipi_ops *ops;
+} provider;
+
+/**
+ * tegra_mipi_enable - Enable the Tegra MIPI calibration device.
+ * @device: Handle to the Tegra MIPI calibration device.
+ *
+ * This calls the enable sequence for the Tegra MIPI calibration device.
+ *
+ * Returns 0 on success or a negative error code on failure.
+ */
+int tegra_mipi_enable(struct tegra_mipi_device *device)
+{
+	if (device->ops->enable)
+		return device->ops->enable(device);
+
+	return 0;
+}
+EXPORT_SYMBOL(tegra_mipi_enable);
+
+/**
+ * tegra_mipi_disable - Disable the Tegra MIPI calibration device.
+ * @device: Handle to the Tegra MIPI calibration device.
+ *
+ * This calls the disable sequence for the Tegra MIPI calibration device.
+ *
+ * Returns 0 on success or a negative error code on failure.
+ */
+int tegra_mipi_disable(struct tegra_mipi_device *device)
+{
+	if (device->ops->disable)
+		return device->ops->disable(device);
+
+	return 0;
+}
+EXPORT_SYMBOL(tegra_mipi_disable);
+
+/**
+ * tegra_mipi_start_calibration - Start the Tegra MIPI calibration sequence.
+ * @device: Handle to the Tegra MIPI calibration device.
+ *
+ * This initiates the calibration of CSI/DSI interfaces via the Tegra MIPI
+ * calibration device.
+ *
+ * Returns 0 on success or a negative error code on failure.
+ */
+int tegra_mipi_start_calibration(struct tegra_mipi_device *device)
+{
+	if (device->ops->start_calibration)
+		return device->ops->start_calibration(device);
+
+	return 0;
+}
+EXPORT_SYMBOL(tegra_mipi_start_calibration);
+
+/**
+ * tegra_mipi_finish_calibration - Finish the Tegra MIPI calibration sequence.
+ * @device: Handle to the Tegra MIPI calibration device.
+ *
+ * This completes the calibration of CSI/DSI interfaces via the Tegra MIPI
+ * calibration device.
+ *
+ * Returns 0 on success or a negative error code on failure.
+ */
+int tegra_mipi_finish_calibration(struct tegra_mipi_device *device)
+{
+	if (device->ops->finish_calibration)
+		return device->ops->finish_calibration(device);
+
+	return 0;
+}
+EXPORT_SYMBOL(tegra_mipi_finish_calibration);
+
+/**
+ * tegra_mipi_request - Request a Tegra MIPI calibration device.
+ * @device: Handle of the device requesting the MIPI calibration function.
+ * @np: Device node pointer of the device requesting the MIPI calibration
+ *	function.
+ *
+ * This function requests a reference to a Tegra MIPI calibration device.
+ *
+ * Returns a pointer to the Tegra MIPI calibration device on success,
+ * or an ERR_PTR-encoded error code on failure.
+ */
+struct tegra_mipi_device *tegra_mipi_request(struct device *device,
+					     struct device_node *np)
+{
+	struct tegra_mipi_device *mipidev;
+	struct of_phandle_args args;
+	int err;
+
+	err = of_parse_phandle_with_args(np, "nvidia,mipi-calibrate",
+					 "#nvidia,mipi-calibrate-cells", 0,
+					 &args);
+	if (err < 0)
+		return ERR_PTR(err);
+
+	if (provider.np != args.np) {
+		err = -ENODEV;
+		goto out;
+	}
+
+	mipidev = kzalloc_obj(*mipidev);
+	if (!mipidev) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	mipidev->pdev = of_find_device_by_node(args.np);
+	if (!mipidev->pdev) {
+		err = -ENODEV;
+		goto free;
+	}
+
+	of_node_put(args.np);
+
+	mipidev->ops = provider.ops;
+	mipidev->pads = args.args[0];
+
+	return mipidev;
+
+free:
+	kfree(mipidev);
+out:
+	of_node_put(args.np);
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL(tegra_mipi_request);
+
+/**
+ * tegra_mipi_free - Free a Tegra MIPI calibration device.
+ * @mipidev: Handle to the Tegra MIPI calibration device.
+ *
+ * This function releases a reference to a Tegra MIPI calibration device
+ * previously requested by tegra_mipi_request().
+ */
+void tegra_mipi_free(struct tegra_mipi_device *mipidev)
+{
+	platform_device_put(mipidev->pdev);
+	kfree(mipidev);
+}
+EXPORT_SYMBOL(tegra_mipi_free);
+
+static void tegra_mipi_remove_provider(void *data)
+{
+	provider.np = NULL;
+	provider.ops = NULL;
+}
+
+/**
+ * devm_tegra_mipi_add_provider - Managed registration of a Tegra MIPI
+ *				  calibration function provider.
+ * @device: Handle to the device providing the MIPI calibration function.
+ * @np: Device node pointer of the device providing the MIPI calibration
+ *	function.
+ * @ops: Operations supported by the MIPI calibration device.
+ *
+ * This registers a device that provides MIPI calibration functions.
+ * For Tegra20 and Tegra30, this is the CSI block, while Tegra114 and
+ * newer SoC generations have a dedicated hardware block for these
+ * functions.
+ *
+ * Returns 0 on success or a negative error code on failure.
+ */
+int devm_tegra_mipi_add_provider(struct device *device, struct device_node *np,
+				 const struct tegra_mipi_ops *ops)
+{
+	if (provider.np)
+		return -EBUSY;
+
+	provider.np = np;
+	provider.ops = ops;
+
+	return devm_add_action_or_reset(device, tegra_mipi_remove_provider, NULL);
+}
+EXPORT_SYMBOL(devm_tegra_mipi_add_provider);