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, 55 insertions, 0 deletions

diff --git a/arch/arm/mach-tegra/io.c b/arch/arm/mach-tegra/io.c
new file mode 100644
index 000000000..afdeb3205
--- /dev/null
+++ b/arch/arm/mach-tegra/io.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * arch/arm/mach-tegra/io.c
+ *
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * Author:
+ *	Colin Cross <ccross@google.com>
+ *	Erik Gilling <konkers@google.com>
+ */
+
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+
+#include <asm/mach/map.h>
+#include <asm/page.h>
+
+#include "board.h"
+#include "iomap.h"
+
+static struct map_desc tegra_io_desc[] __initdata = {
+	{
+		.virtual = (unsigned long)IO_PPSB_VIRT,
+		.pfn = __phys_to_pfn(IO_PPSB_PHYS),
+		.length = IO_PPSB_SIZE,
+		.type = MT_DEVICE,
+	},
+	{
+		.virtual = (unsigned long)IO_APB_VIRT,
+		.pfn = __phys_to_pfn(IO_APB_PHYS),
+		.length = IO_APB_SIZE,
+		.type = MT_DEVICE,
+	},
+	{
+		.virtual = (unsigned long)IO_CPU_VIRT,
+		.pfn = __phys_to_pfn(IO_CPU_PHYS),
+		.length = IO_CPU_SIZE,
+		.type = MT_DEVICE,
+	},
+	{
+		.virtual = (unsigned long)IO_IRAM_VIRT,
+		.pfn = __phys_to_pfn(IO_IRAM_PHYS),
+		.length = IO_IRAM_SIZE,
+		.type = MT_DEVICE,
+	},
+};
+
+void __init tegra_map_common_io(void)
+{
+	debug_ll_io_init();
+	iotable_init(tegra_io_desc, ARRAY_SIZE(tegra_io_desc));
+}