selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 49 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/pps/pps-gpio.yaml b/Documentation/devicetree/bindings/pps/pps-gpio.yaml
new file mode 100644
index 000000000..383a83874
--- /dev/null
+++ b/Documentation/devicetree/bindings/pps/pps-gpio.yaml
@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pps/pps-gpio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: PPS Signal via GPIO
+
+maintainers:
+  - Fabio Estevam <festevam@gmail.com>
+
+properties:
+  compatible:
+    const: pps-gpio
+
+  gpios:
+    description: The GPIO that provides the PPS signal.
+    maxItems: 1
+
+  echo-gpios:
+    description: The GPIO that provides the PPS ECHO signal.
+    maxItems: 1
+
+  echo-active-ms:
+    description: Duration in ms of the active portion of the echo pulse.
+
+  assert-falling-edge:
+    description: Indicates a falling edge assert, when present. Rising edge if absent.
+    type: boolean
+
+required:
+  - compatible
+  - gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    pps {
+        compatible = "pps-gpio";
+        pinctrl-names = "default";
+        pinctrl-0 = <&pinctrl_pps>;
+        gpios = <&gpio1 26 GPIO_ACTIVE_HIGH>;
+        assert-falling-edge;
+        echo-gpios = <&gpio1 27 GPIO_ACTIVE_HIGH>;
+        echo-active-ms = <100>;
+    };