ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

3 files changed, 207 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/virtio/mmio.yaml b/Documentation/devicetree/bindings/virtio/mmio.yaml
new file mode 100644
index 000000000..0aa8433f0
--- /dev/null
+++ b/Documentation/devicetree/bindings/virtio/mmio.yaml
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/virtio/mmio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: virtio memory mapped devices
+
+maintainers:
+  - Jean-Philippe Brucker <jean-philippe@linaro.org>
+
+description:
+  See https://www.oasis-open.org/committees/tc_home.php?wg_abbrev=virtio for
+  more details.
+
+properties:
+  compatible:
+    const: virtio,mmio
+
+  reg:
+    maxItems: 1
+
+  dma-coherent: true
+
+  interrupts:
+    maxItems: 1
+
+  '#iommu-cells':
+    description: Required when the node corresponds to a virtio-iommu device.
+    const: 1
+
+  iommus:
+    description: Required for devices making accesses thru an IOMMU.
+    maxItems: 1
+
+  wakeup-source:
+    type: boolean
+    description: Required for setting irq of a virtio_mmio device as wakeup source.
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+additionalProperties:
+  type: object
+
+examples:
+  - |
+    virtio@3000 {
+        compatible = "virtio,mmio";
+        reg = <0x3000 0x100>;
+        interrupts = <41>;
+
+        /* Device has endpoint ID 23 */
+        iommus = <&viommu 23>;
+    };
+
+    viommu: iommu@3100 {
+        compatible = "virtio,mmio";
+        reg = <0x3100 0x100>;
+        interrupts = <42>;
+
+        #iommu-cells = <1>;
+    };
+
+...
diff --git a/Documentation/devicetree/bindings/virtio/pci-iommu.yaml b/Documentation/devicetree/bindings/virtio/pci-iommu.yaml
new file mode 100644
index 000000000..8bd6ad72a
--- /dev/null
+++ b/Documentation/devicetree/bindings/virtio/pci-iommu.yaml
@@ -0,0 +1,99 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/virtio/pci-iommu.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: virtio-iommu device using the virtio-pci transport
+
+maintainers:
+  - Jean-Philippe Brucker <jean-philippe@linaro.org>
+
+description: |
+  When virtio-iommu uses the PCI transport, its programming interface is
+  discovered dynamically by the PCI probing infrastructure. However the
+  device tree statically describes the relation between IOMMU and DMA
+  masters. Therefore, the PCI root complex that hosts the virtio-iommu
+  contains a child node representing the IOMMU device explicitly.
+
+  DMA from the IOMMU device isn't managed by another IOMMU. Therefore the
+  virtio-iommu node doesn't have an "iommus" property, and is omitted from
+  the iommu-map property of the root complex.
+
+allOf:
+  - $ref: /schemas/pci/pci-device.yaml#
+
+properties:
+  # If compatible is present, it should contain the vendor and device ID
+  # according to the PCI Bus Binding specification. Since PCI provides
+  # built-in identification methods, compatible is not actually required.
+  compatible:
+    oneOf:
+      - items:
+          - const: virtio,pci-iommu
+          - const: pci1af4,1057
+      - items:
+          - const: pci1af4,1057
+
+  reg:
+    maxItems: 1
+
+  '#iommu-cells':
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - '#iommu-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    bus {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        pcie@40000000 {
+            device_type = "pci";
+            #address-cells = <3>;
+            #size-cells = <2>;
+            reg = <0x0 0x40000000  0x0 0x1000000>;
+            ranges = <0x02000000 0x0 0x41000000  0x0 0x41000000  0x0 0x0f000000>;
+
+            /*
+             * The IOMMU manages all functions in this PCI domain except
+             * itself. Omit BDF 00:01.0.
+             */
+            iommu-map = <0x0 &iommu0 0x0 0x8
+                         0x9 &iommu0 0x9 0xfff7>;
+
+            /* The IOMMU programming interface uses slot 00:01.0 */
+            iommu0: iommu@1,0 {
+                compatible = "pci1af4,1057";
+                reg = <0x800 0 0 0 0>;
+                #iommu-cells = <1>;
+            };
+        };
+
+        pcie@50000000 {
+            device_type = "pci";
+            #address-cells = <3>;
+            #size-cells = <2>;
+            reg = <0x0 0x50000000  0x0 0x1000000>;
+            ranges = <0x02000000 0x0 0x51000000  0x0 0x51000000  0x0 0x0f000000>;
+
+            /*
+             * The IOMMU also manages all functions from this domain,
+             * with endpoint IDs 0x10000 - 0x1ffff
+             */
+            iommu-map = <0x0 &iommu0 0x10000 0x10000>;
+        };
+
+        ethernet {
+            /* The IOMMU manages this platform device with endpoint ID 0x20000 */
+            iommus = <&iommu0 0x20000>;
+        };
+    };
+
+...
diff --git a/Documentation/devicetree/bindings/virtio/virtio-device.yaml b/Documentation/devicetree/bindings/virtio/virtio-device.yaml
new file mode 100644
index 000000000..8c6919ba9
--- /dev/null
+++ b/Documentation/devicetree/bindings/virtio/virtio-device.yaml
@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/virtio/virtio-device.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Virtio device
+
+maintainers:
+  - Viresh Kumar <viresh.kumar@linaro.org>
+
+description:
+  These bindings are applicable to virtio devices irrespective of the bus they
+  are bound to, like mmio or pci.
+
+# We need a select here so we don't match all nodes with 'virtio,mmio'
+properties:
+  compatible:
+    pattern: "^virtio,device[0-9a-f]{1,8}$"
+    description: Virtio device nodes.
+      "virtio,deviceID", where ID is the virtio device id. The textual
+      representation of ID shall be in lower case hexadecimal with leading
+      zeroes suppressed.
+
+required:
+  - compatible
+
+additionalProperties: true
+
+examples:
+  - |
+    virtio@3000 {
+        compatible = "virtio,mmio";
+        reg = <0x3000 0x100>;
+        interrupts = <43>;
+
+        i2c {
+            compatible = "virtio,device22";
+        };
+    };
+...