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, 15 insertions, 0 deletions

diff --git a/drivers/dma/bestcomm/Makefile b/drivers/dma/bestcomm/Makefile
new file mode 100644
index 000000000..8d1b33a2f
--- /dev/null
+++ b/drivers/dma/bestcomm/Makefile
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for BestComm & co
+#
+
+bestcomm-core-objs	:= bestcomm.o sram.o
+bestcomm-ata-objs	:= ata.o bcom_ata_task.o
+bestcomm-fec-objs	:= fec.o bcom_fec_rx_task.o bcom_fec_tx_task.o
+bestcomm-gen-bd-objs	:= gen_bd.o bcom_gen_bd_rx_task.o bcom_gen_bd_tx_task.o
+
+obj-$(CONFIG_PPC_BESTCOMM)		+= bestcomm-core.o
+obj-$(CONFIG_PPC_BESTCOMM_ATA)		+= bestcomm-ata.o
+obj-$(CONFIG_PPC_BESTCOMM_FEC)		+= bestcomm-fec.o
+obj-$(CONFIG_PPC_BESTCOMM_GEN_BD)	+= bestcomm-gen-bd.o
+