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, 42 insertions, 0 deletions

diff --git a/arch/mips/bmips/irq.c b/arch/mips/bmips/irq.c
new file mode 100644
index 000000000..c4daa590b
--- /dev/null
+++ b/arch/mips/bmips/irq.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright (C) 2014 Broadcom Corporation
+ * Author: Kevin Cernekee <cernekee@gmail.com>
+ */
+
+#include <linux/of.h>
+#include <linux/irqchip.h>
+
+#include <asm/bmips.h>
+#include <asm/irq.h>
+#include <asm/irq_cpu.h>
+#include <asm/time.h>
+
+static const struct of_device_id smp_intc_dt_match[] = {
+	{ .compatible = "brcm,bcm7038-l1-intc" },
+	{ .compatible = "brcm,bcm6345-l1-intc" },
+	{}
+};
+
+unsigned int get_c0_compare_int(void)
+{
+	return CP0_LEGACY_COMPARE_IRQ;
+}
+
+void __init arch_init_irq(void)
+{
+	struct device_node *dn;
+
+	/* Only these controllers support SMP IRQ affinity */
+	dn = of_find_matching_node(NULL, smp_intc_dt_match);
+	if (dn)
+		of_node_put(dn);
+	else
+		bmips_tp1_irqs = 0;
+
+	irqchip_init();
+}
+
+IRQCHIP_DECLARE(mips_cpu_intc, "mti,cpu-interrupt-controller",
+	     mips_cpu_irq_of_init);