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

3 files changed, 272 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/dpll/dpll-device.yaml b/Documentation/devicetree/bindings/dpll/dpll-device.yaml
new file mode 100644
index 000000000..fb8d7a9a3
--- /dev/null
+++ b/Documentation/devicetree/bindings/dpll/dpll-device.yaml
@@ -0,0 +1,76 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/dpll/dpll-device.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Digital Phase-Locked Loop (DPLL) Device
+
+maintainers:
+  - Ivan Vecera <ivecera@redhat.com>
+
+description:
+  Digital Phase-Locked Loop (DPLL) device is used for precise clock
+  synchronization in networking and telecom hardware. The device can
+  have one or more channels (DPLLs) and one or more physical input and
+  output pins. Each DPLL channel can either produce pulse-per-clock signal
+  or drive ethernet equipment clock. The type of each channel can be
+  indicated by dpll-types property.
+
+properties:
+  $nodename:
+    pattern: "^dpll(@.*)?$"
+
+  "#address-cells":
+    const: 0
+
+  "#size-cells":
+    const: 0
+
+  dpll-types:
+    description: List of DPLL channel types, one per DPLL instance.
+    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
+    items:
+      enum: [pps, eec]
+
+  input-pins:
+    type: object
+    description: DPLL input pins
+    unevaluatedProperties: false
+
+    properties:
+      "#address-cells":
+        const: 1
+      "#size-cells":
+        const: 0
+
+    patternProperties:
+      "^pin@[0-9a-f]+$":
+        $ref: /schemas/dpll/dpll-pin.yaml
+        unevaluatedProperties: false
+
+    required:
+      - "#address-cells"
+      - "#size-cells"
+
+  output-pins:
+    type: object
+    description: DPLL output pins
+    unevaluatedProperties: false
+
+    properties:
+      "#address-cells":
+        const: 1
+      "#size-cells":
+        const: 0
+
+    patternProperties:
+      "^pin@[0-9]+$":
+        $ref: /schemas/dpll/dpll-pin.yaml
+        unevaluatedProperties: false
+
+    required:
+      - "#address-cells"
+      - "#size-cells"
+
+additionalProperties: true
diff --git a/Documentation/devicetree/bindings/dpll/dpll-pin.yaml b/Documentation/devicetree/bindings/dpll/dpll-pin.yaml
new file mode 100644
index 000000000..1287a472f
--- /dev/null
+++ b/Documentation/devicetree/bindings/dpll/dpll-pin.yaml
@@ -0,0 +1,58 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/dpll/dpll-pin.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: DPLL Pin
+
+maintainers:
+  - Ivan Vecera <ivecera@redhat.com>
+
+description: |
+  The DPLL pin is either a physical input or output pin that is provided
+  by a DPLL( Digital Phase-Locked Loop) device. The pin is identified by
+  its physical order number that is stored in reg property and can have
+  an additional set of properties like supported (allowed) frequencies,
+  label, type and may support embedded sync.
+
+  Note that the pin in this context has nothing to do with pinctrl.
+
+properties:
+  reg:
+    description: Hardware index of the DPLL pin.
+    maxItems: 1
+
+  connection-type:
+    description: Connection type of the pin
+    $ref: /schemas/types.yaml#/definitions/string
+    enum: [ext, gnss, int, mux, synce]
+
+  esync-control:
+    description: Indicates whether the pin supports embedded sync functionality.
+    type: boolean
+
+  label:
+    description: String exposed as the pin board label
+    $ref: /schemas/types.yaml#/definitions/string
+
+  ref-sync-sources:
+    description: |
+      List of phandles to input pins that can serve as the sync source
+      in a Reference-Sync pair with this pin acting as the clock source.
+      A Ref-Sync pair consists of a clock reference and a low-frequency
+      sync signal.  The DPLL locks to the clock reference but
+      phase-aligns to the sync reference.
+      Only valid for input pins.  Each referenced pin must be a
+      different input pin on the same device.
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    items:
+      maxItems: 1
+
+  supported-frequencies-hz:
+    description: List of supported frequencies for this pin, expressed in Hz.
+
+required:
+  - reg
+
+additionalProperties: false
diff --git a/Documentation/devicetree/bindings/dpll/microchip,zl30731.yaml b/Documentation/devicetree/bindings/dpll/microchip,zl30731.yaml
new file mode 100644
index 000000000..17983e6c3
--- /dev/null
+++ b/Documentation/devicetree/bindings/dpll/microchip,zl30731.yaml
@@ -0,0 +1,138 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/dpll/microchip,zl30731.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip Azurite DPLL device
+
+maintainers:
+  - Ivan Vecera <ivecera@redhat.com>
+
+description:
+  Microchip Azurite DPLL (ZL3073x) is a family of DPLL devices that
+  provides up to 5 independent DPLL channels, up to 10 differential or
+  single-ended inputs and 10 differential or 20 single-ended outputs.
+  These devices support both I2C and SPI interfaces.
+  The ZL3064x line card timing ICs  share the ZL3073x register map
+  and are described with a fallback to the register equivalent ZL3073x
+  part.
+
+properties:
+  compatible:
+    oneOf:
+      - enum:
+          - microchip,zl30731
+          - microchip,zl30732
+          - microchip,zl30733
+          - microchip,zl30734
+          - microchip,zl30735
+      - items:
+          - const: microchip,zl30643
+          - const: microchip,zl30733
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+allOf:
+  - $ref: /schemas/dpll/dpll-device.yaml#
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      dpll@70 {
+        compatible = "microchip,zl30732";
+        reg = <0x70>;
+        dpll-types = "pps", "eec";
+
+        input-pins {
+          #address-cells = <1>;
+          #size-cells = <0>;
+
+          sync0: pin@0 { /* REF0P - 1 PPS sync source */
+            reg = <0>;
+            connection-type = "ext";
+            label = "SMA1";
+            supported-frequencies-hz = /bits/ 64 <1>;
+          };
+
+          pin@1 { /* REF0N - clock source, can pair with sync0 */
+            reg = <1>;
+            connection-type = "ext";
+            label = "SMA2";
+            supported-frequencies-hz = /bits/ 64 <10000 10000000>;
+            ref-sync-sources = <&sync0>;
+          };
+        };
+
+        output-pins {
+          #address-cells = <1>;
+          #size-cells = <0>;
+
+          pin@3 { /* OUT1N */
+            reg = <3>;
+            connection-type = "gnss";
+            esync-control;
+            label = "Output 1";
+            supported-frequencies-hz = /bits/ 64 <1 10000>;
+          };
+        };
+      };
+    };
+  - |
+    spi {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      dpll@70 {
+        compatible = "microchip,zl30731";
+        reg = <0x70>;
+        spi-max-frequency = <12500000>;
+
+        dpll-types = "pps";
+
+        input-pins {
+          #address-cells = <1>;
+          #size-cells = <0>;
+
+          sync1: pin@0 { /* REF0P - 1 PPS sync source */
+            reg = <0>;
+            connection-type = "gnss";
+            label = "GNSS_1PPS_IN";
+            supported-frequencies-hz = /bits/ 64 <1>;
+          };
+
+          pin@1 { /* REF0N - clock source */
+            reg = <1>;
+            connection-type = "gnss";
+            label = "GNSS_10M_IN";
+            supported-frequencies-hz = /bits/ 64 <10000000>;
+            ref-sync-sources = <&sync1>;
+          };
+        };
+
+        output-pins {
+          #address-cells = <1>;
+          #size-cells = <0>;
+
+          pin@3 { /* OUT1N */
+            reg = <3>;
+            connection-type = "gnss";
+            esync-control;
+            label = "Output 1";
+            supported-frequencies-hz = /bits/ 64 <1 10000>;
+          };
+        };
+      };
+    };
+...