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, 25 insertions, 0 deletions

diff --git a/arch/mips/Kbuild b/arch/mips/Kbuild
new file mode 100644
index 000000000..e901bf554
--- /dev/null
+++ b/arch/mips/Kbuild
@@ -0,0 +1,25 @@
+# SPDX-License-Identifier: GPL-2.0
+
+# platform specific definitions
+include $(srctree)/arch/mips/Kbuild.platforms
+obj-y := $(platform-y)
+
+# make clean traverses $(obj-) without having included .config, so
+# everything ends up here
+obj- := $(platform-y)
+
+# mips object files
+# The object files are linked as core-y files would be linked
+
+obj-y += generic/
+obj-y += kernel/
+obj-y += mm/
+obj-y += net/
+obj-y += vdso/
+
+ifdef CONFIG_KVM
+obj-y += kvm/
+endif
+
+# for cleaning
+subdir- += boot