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, 20 insertions, 0 deletions

diff --git a/scripts/mkuboot.sh b/scripts/mkuboot.sh
new file mode 100755
index 000000000..4b1fe09e9
--- /dev/null
+++ b/scripts/mkuboot.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+#
+# Build U-Boot image when `mkimage' tool is available.
+#
+
+MKIMAGE=$(type -path "${CROSS_COMPILE}mkimage")
+
+if [ -z "${MKIMAGE}" ]; then
+	MKIMAGE=$(type -path mkimage)
+	if [ -z "${MKIMAGE}" ]; then
+		# Doesn't exist
+		echo '"mkimage" command not found - U-Boot images will not be built' >&2
+		exit 1;
+	fi
+fi
+
+# Call "mkimage" to create U-Boot image
+${MKIMAGE} "$@"