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, 120 insertions, 0 deletions

diff --git a/arch/mips/ralink/of.c b/arch/mips/ralink/of.c
new file mode 100644
index 000000000..7f90068c6
--- /dev/null
+++ b/arch/mips/ralink/of.c
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
+ * Copyright (C) 2008-2009 Gabor Juhos <juhosg@openwrt.org>
+ * Copyright (C) 2013 John Crispin <john@phrozen.org>
+ */
+
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/sizes.h>
+#include <linux/of_fdt.h>
+#include <linux/kernel.h>
+#include <linux/memblock.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+#include <asm/reboot.h>
+#include <asm/bootinfo.h>
+#include <asm/addrspace.h>
+#include <asm/prom.h>
+#include <asm/mach-ralink/ralink_regs.h>
+
+#include "common.h"
+
+__iomem void *rt_sysc_membase;
+__iomem void *rt_memc_membase;
+EXPORT_SYMBOL_GPL(rt_sysc_membase);
+
+static const struct of_device_id mtmips_memc_match[] = {
+	{ .compatible = "mediatek,mt7621-memc" },
+	{ .compatible = "ralink,mt7620a-memc" },
+	{ .compatible = "ralink,rt2880-memc" },
+	{ .compatible = "ralink,rt3050-memc" },
+	{ .compatible = "ralink,rt3883-memc" },
+	{}
+};
+
+static const struct of_device_id mtmips_sysc_match[] = {
+	{ .compatible = "mediatek,mt7621-sysc" },
+	{ .compatible = "ralink,mt7620-sysc" },
+	{ .compatible = "ralink,mt7628-sysc" },
+	{ .compatible = "ralink,mt7688-sysc" },
+	{ .compatible = "ralink,rt2880-sysc" },
+	{ .compatible = "ralink,rt3050-sysc" },
+	{ .compatible = "ralink,rt3052-sysc" },
+	{ .compatible = "ralink,rt3352-sysc" },
+	{ .compatible = "ralink,rt3883-sysc" },
+	{ .compatible = "ralink,rt5350-sysc" },
+	{}
+};
+
+static __iomem void *
+mtmips_of_remap_node(const struct of_device_id *match, const char *type)
+{
+	struct resource res;
+	struct device_node *np;
+
+	np = of_find_matching_node(NULL, match);
+	if (!np)
+		panic("Failed to find %s controller node", type);
+
+	if (of_address_to_resource(np, 0, &res))
+		panic("Failed to get resource for %s node", np->name);
+
+	if (!request_mem_region(res.start,
+				resource_size(&res),
+				res.name))
+		panic("Failed to request resources for %s node", np->name);
+
+	of_node_put(np);
+
+	return ioremap(res.start, resource_size(&res));
+}
+
+void __init ralink_of_remap(void)
+{
+	rt_sysc_membase = mtmips_of_remap_node(mtmips_sysc_match, "system");
+	rt_memc_membase = mtmips_of_remap_node(mtmips_memc_match, "memory");
+
+	if (!rt_sysc_membase || !rt_memc_membase)
+		panic("Failed to remap core resources");
+}
+
+void __init plat_mem_setup(void)
+{
+	void *dtb;
+
+	set_io_port_base(KSEG1);
+
+	/*
+	 * Load the builtin devicetree. This causes the chosen node to be
+	 * parsed resulting in our memory appearing.
+	 */
+	dtb = get_fdt();
+	__dt_setup_arch(dtb);
+
+	if (early_init_dt_scan_memory())
+		return;
+
+	if (soc_info.mem_detect)
+		soc_info.mem_detect();
+	else if (soc_info.mem_size)
+		memblock_add(soc_info.mem_base, soc_info.mem_size * SZ_1M);
+	else
+		detect_memory_region(soc_info.mem_base,
+				     soc_info.mem_size_min * SZ_1M,
+				     soc_info.mem_size_max * SZ_1M);
+}
+
+static int __init plat_of_setup(void)
+{
+	__dt_register_buses(soc_info.compatible, "palmbus");
+
+	return 0;
+}
+
+arch_initcall(plat_of_setup);