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, 29 insertions, 0 deletions

diff --git a/drivers/pmdomain/renesas/r8a7794-sysc.c b/drivers/pmdomain/renesas/r8a7794-sysc.c
new file mode 100644
index 000000000..72ef4e854
--- /dev/null
+++ b/drivers/pmdomain/renesas/r8a7794-sysc.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Renesas R-Car E2 System Controller
+ *
+ * Copyright (C) 2016 Glider bvba
+ */
+
+#include <linux/kernel.h>
+
+#include <dt-bindings/power/r8a7794-sysc.h>
+
+#include "rcar-sysc.h"
+
+static const struct rcar_sysc_area r8a7794_areas[] __initconst = {
+	{ "always-on",	    0, 0, R8A7794_PD_ALWAYS_ON,	-1, PD_ALWAYS_ON },
+	{ "ca7-scu",	0x100, 0, R8A7794_PD_CA7_SCU,	R8A7794_PD_ALWAYS_ON,
+	  PD_SCU },
+	{ "ca7-cpu0",	0x1c0, 0, R8A7794_PD_CA7_CPU0,	R8A7794_PD_CA7_SCU,
+	  PD_CPU_NOCR },
+	{ "ca7-cpu1",	0x1c0, 1, R8A7794_PD_CA7_CPU1,	R8A7794_PD_CA7_SCU,
+	  PD_CPU_NOCR },
+	{ "sh-4a",	 0x80, 0, R8A7794_PD_SH_4A,	R8A7794_PD_ALWAYS_ON },
+	{ "sgx",	 0xc0, 0, R8A7794_PD_SGX,	R8A7794_PD_ALWAYS_ON },
+};
+
+const struct rcar_sysc_info r8a7794_sysc_info __initconst = {
+	.areas = r8a7794_areas,
+	.num_areas = ARRAY_SIZE(r8a7794_areas),
+};