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, 49 insertions, 0 deletions

diff --git a/drivers/clk/ingenic/pm.c b/drivers/clk/ingenic/pm.c
new file mode 100644
index 000000000..206d5cf28
--- /dev/null
+++ b/drivers/clk/ingenic/pm.c
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Paul Cercueil <paul@crapouillou.net>
+ */
+
+#include "cgu.h"
+#include "pm.h"
+
+#include <linux/io.h>
+#include <linux/syscore_ops.h>
+
+#define CGU_REG_LCR		0x04
+
+#define LCR_LOW_POWER_MODE	BIT(0)
+
+static void __iomem * __maybe_unused ingenic_cgu_base;
+
+static int __maybe_unused ingenic_cgu_pm_suspend(void *data)
+{
+	u32 val = readl(ingenic_cgu_base + CGU_REG_LCR);
+
+	writel(val | LCR_LOW_POWER_MODE, ingenic_cgu_base + CGU_REG_LCR);
+
+	return 0;
+}
+
+static void __maybe_unused ingenic_cgu_pm_resume(void *data)
+{
+	u32 val = readl(ingenic_cgu_base + CGU_REG_LCR);
+
+	writel(val & ~LCR_LOW_POWER_MODE, ingenic_cgu_base + CGU_REG_LCR);
+}
+
+static const struct syscore_ops __maybe_unused ingenic_cgu_pm_ops = {
+	.suspend = ingenic_cgu_pm_suspend,
+	.resume = ingenic_cgu_pm_resume,
+};
+
+static struct syscore __maybe_unused ingenic_cgu_pm = {
+	.ops = &ingenic_cgu_pm_ops,
+};
+
+void ingenic_cgu_register_syscore(struct ingenic_cgu *cgu)
+{
+	if (IS_ENABLED(CONFIG_PM_SLEEP)) {
+		ingenic_cgu_base = cgu->base;
+		register_syscore(&ingenic_cgu_pm);
+	}
+}