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, 18 insertions, 0 deletions

diff --git a/arch/mips/lib/Makefile b/arch/mips/lib/Makefile
new file mode 100644
index 000000000..5d5b993cb
--- /dev/null
+++ b/arch/mips/lib/Makefile
@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for MIPS-specific library files..
+#
+
+lib-y	+= bitops.o csum_partial.o delay.o memcpy.o memset.o \
+	   mips-atomic.o strncpy_user.o \
+	   strnlen_user.o uncached.o
+
+obj-y			+= iomap_copy.o
+obj-$(CONFIG_PCI)	+= iomap-pci.o
+lib-$(CONFIG_GENERIC_CSUM)	:= $(filter-out csum_partial.o, $(lib-y))
+
+obj-$(CONFIG_CPU_GENERIC_DUMP_TLB) += dump_tlb.o
+obj-$(CONFIG_CPU_R3000)		+= r3k_dump_tlb.o
+
+# libgcc-style stuff needed in the kernel
+obj-y += bswapsi.o bswapdi.o multi3.o