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, 27 insertions, 0 deletions

diff --git a/arch/arm/mach-shmobile/setup-emev2.c b/arch/arm/mach-shmobile/setup-emev2.c
new file mode 100644
index 000000000..ed82d6429
--- /dev/null
+++ b/arch/arm/mach-shmobile/setup-emev2.c
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Emma Mobile EV2 processor support
+ *
+ * Copyright (C) 2012  Magnus Damm
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <asm/mach-types.h>
+#include <asm/mach/arch.h>
+#include <asm/mach/map.h>
+
+#include "common.h"
+#include "emev2.h"
+
+static const char *const emev2_boards_compat_dt[] __initconst = {
+	"renesas,emev2",
+	NULL
+};
+
+DT_MACHINE_START(EMEV2_DT, "Generic Emma Mobile EV2 (Flattened Device Tree)")
+	.smp		= smp_ops(emev2_smp_ops),
+	.init_early	= shmobile_init_delay,
+	.init_late	= shmobile_init_late,
+	.dt_compat	= emev2_boards_compat_dt,
+MACHINE_END