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/arch/powerpc/boot/ep8248e.c b/arch/powerpc/boot/ep8248e.c
new file mode 100644
index 000000000..2ab9e0d8c
--- /dev/null
+++ b/arch/powerpc/boot/ep8248e.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Embedded Planet EP8248E with PlanetCore firmware
+ *
+ * Author: Scott Wood <scottwood@freescale.com>
+ *
+ * Copyright (c) 2007 Freescale Semiconductor, Inc.
+ */
+
+#include "ops.h"
+#include "stdio.h"
+#include "planetcore.h"
+#include "pq2.h"
+
+static char *table;
+static u64 mem_size;
+
+#include <io.h>
+
+static void platform_fixups(void)
+{
+	u64 val;
+
+	dt_fixup_memory(0, mem_size);
+	planetcore_set_mac_addrs(table);
+
+	if (!planetcore_get_decimal(table, PLANETCORE_KEY_CRYSTAL_HZ, &val)) {
+		printf("No PlanetCore crystal frequency key.\r\n");
+		return;
+	}
+
+	pq2_fixup_clocks(val);
+}
+
+void platform_init(unsigned long r3, unsigned long r4, unsigned long r5,
+                   unsigned long r6, unsigned long r7)
+{
+	table = (char *)r3;
+	planetcore_prepare_table(table);
+
+	if (!planetcore_get_decimal(table, PLANETCORE_KEY_MB_RAM, &mem_size))
+		return;
+
+	mem_size *= 1024 * 1024;
+	simple_alloc_init(_end, mem_size - (unsigned long)_end, 32, 64);
+
+	fdt_init(_dtb_start);
+
+	planetcore_set_stdout_path(table);
+	serial_console_init();
+	platform_ops.fixups = platform_fixups;
+}