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, 47 insertions, 0 deletions

diff --git a/arch/mips/loongson64/time.c b/arch/mips/loongson64/time.c
new file mode 100644
index 000000000..f6d2c1e30
--- /dev/null
+++ b/arch/mips/loongson64/time.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2007 Lemote, Inc. & Institute of Computing Technology
+ * Author: Fuxin Zhang, zhangfx@lemote.com
+ *
+ * Copyright (C) 2009 Lemote Inc.
+ * Author: Wu Zhangjin, wuzhangjin@gmail.com
+ */
+
+#include <asm/time.h>
+#include <asm/hpet.h>
+
+#include <loongson.h>
+#include <linux/clk.h>
+#include <linux/of_clk.h>
+
+void __init plat_time_init(void)
+{
+	struct clk *clk;
+	struct device_node *np;
+
+	if (loongson_sysconf.fw_interface == LOONGSON_DTB) {
+		of_clk_init(NULL);
+
+		np = of_get_cpu_node(0, NULL);
+		if (!np) {
+			pr_err("Failed to get CPU node\n");
+			return;
+		}
+
+		clk = of_clk_get(np, 0);
+		if (IS_ERR(clk)) {
+			pr_err("Failed to get CPU clock: %ld\n", PTR_ERR(clk));
+			return;
+		}
+
+		cpu_clock_freq = clk_get_rate(clk);
+		clk_put(clk);
+	}
+
+	/* setup mips r4k timer */
+	mips_hpt_frequency = cpu_clock_freq / 2;
+
+#ifdef CONFIG_RS780_HPET
+	setup_hpet_timer();
+#endif
+}