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, 52 insertions, 0 deletions

diff --git a/drivers/char/xillybus/Kconfig b/drivers/char/xillybus/Kconfig
new file mode 100644
index 000000000..f51d53339
--- /dev/null
+++ b/drivers/char/xillybus/Kconfig
@@ -0,0 +1,52 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Xillybus devices
+#
+
+config XILLYBUS_CLASS
+	tristate
+
+config XILLYBUS
+	tristate "Xillybus generic FPGA interface"
+	depends on PCI || OF
+	select CRC32
+	select XILLYBUS_CLASS
+	help
+	  Xillybus is a generic interface for peripherals designed on
+	  programmable logic (FPGA). The driver probes the hardware for
+	  its capabilities, and creates device files accordingly.
+
+	  If unsure, say N.
+
+if XILLYBUS
+
+config XILLYBUS_PCIE
+	tristate "Xillybus over PCIe"
+	depends on PCI_MSI
+	help
+	  Set to M if you want Xillybus to use PCI Express for communicating
+	  with the FPGA. The module will be called xillybus_pcie.
+
+config XILLYBUS_OF
+	tristate "Xillybus over Device Tree"
+	depends on OF && HAS_DMA && HAS_IOMEM
+	help
+	  Set to M if you want Xillybus to find its resources from the
+	  Open Firmware Flattened Device Tree. If the target is an embedded
+	  system, say M. The module will be called xillybus_of.
+
+endif # if XILLYBUS
+
+# XILLYUSB doesn't depend on XILLYBUS
+
+config XILLYUSB
+	tristate "XillyUSB: Xillybus generic FPGA interface for USB"
+	depends on USB
+	select CRC32
+	select XILLYBUS_CLASS
+	help
+	  XillyUSB is the Xillybus variant which uses USB for communicating
+	  with the FPGA.
+
+	  Set to M if you want Xillybus to use USB for communicating with
+	  the FPGA. The module will be called xillyusb.