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, 23 insertions, 0 deletions

diff --git a/arch/arm64/tools/gen-kernel-hwcaps.sh b/arch/arm64/tools/gen-kernel-hwcaps.sh
new file mode 100644
index 000000000..e7cdcf428
--- /dev/null
+++ b/arch/arm64/tools/gen-kernel-hwcaps.sh
@@ -0,0 +1,23 @@
+#!/bin/sh -e
+# SPDX-License-Identifier: GPL-2.0
+#
+# gen-kernel-hwcap.sh - Generate kernel internal hwcap.h definitions
+#
+# Copyright 2026 Arm, Ltd.
+
+if [ "$1" = "" ]; then
+	echo "$0: no filename specified"
+	exit 1
+fi
+
+echo "#ifndef __ASM_KERNEL_HWCAPS_H"
+echo "#define __ASM_KERNEL_HWCAPS_H"
+echo ""
+echo "/* Generated file - do not edit */"
+echo ""
+
+grep -E '^#define HWCAP[0-9]*_[A-Z0-9_]+' $1 | \
+	sed 's/.*HWCAP\([0-9]*\)_\([A-Z0-9_]\+\).*/#define KERNEL_HWCAP_\2\t__khwcap\1_feature(\2)/'
+
+echo ""
+echo "#endif /* __ASM_KERNEL_HWCAPS_H */"