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, 60 insertions, 0 deletions

diff --git a/drivers/clk/tegra/cvb.h b/drivers/clk/tegra/cvb.h
new file mode 100644
index 000000000..750095fe9
--- /dev/null
+++ b/drivers/clk/tegra/cvb.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Utility functions for parsing Tegra CVB voltage tables
+ */
+
+#ifndef __DRIVERS_CLK_TEGRA_CVB_H
+#define __DRIVERS_CLK_TEGRA_CVB_H
+
+#include <linux/types.h>
+
+struct device;
+
+#define MAX_DVFS_FREQS	40
+
+struct rail_alignment {
+	int offset_uv;
+	int step_uv;
+};
+
+struct cvb_coefficients {
+	int c0;
+	int c1;
+	int c2;
+};
+
+struct cvb_table_freq_entry {
+	unsigned long freq;
+	struct cvb_coefficients coefficients;
+};
+
+struct cvb_cpu_dfll_data {
+	u32 tune0_low;
+	u32 tune0_high;
+	u32 tune1;
+	unsigned int tune_high_min_millivolts;
+};
+
+struct cvb_table {
+	int speedo_id;
+	int process_id;
+
+	int min_millivolts;
+	int max_millivolts;
+
+	int speedo_scale;
+	int voltage_scale;
+	struct cvb_table_freq_entry entries[MAX_DVFS_FREQS];
+	struct cvb_cpu_dfll_data cpu_dfll_data;
+};
+
+const struct cvb_table *
+tegra_cvb_add_opp_table(struct device *dev, const struct cvb_table *cvb_tables,
+			size_t count, struct rail_alignment *align,
+			int process_id, int speedo_id, int speedo_value,
+			unsigned long max_freq);
+void tegra_cvb_remove_opp_table(struct device *dev,
+				const struct cvb_table *table,
+				unsigned long max_freq);
+
+#endif