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, 84 insertions, 0 deletions

diff --git a/drivers/clk/actions/owl-divider.c b/drivers/clk/actions/owl-divider.c
new file mode 100644
index 000000000..316ace80e
--- /dev/null
+++ b/drivers/clk/actions/owl-divider.c
@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// OWL divider clock driver
+//
+// Copyright (c) 2014 Actions Semi Inc.
+// Author: David Liu <liuwei@actions-semi.com>
+//
+// Copyright (c) 2018 Linaro Ltd.
+// Author: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
+
+#include <linux/clk-provider.h>
+#include <linux/regmap.h>
+
+#include "owl-divider.h"
+
+static int owl_divider_determine_rate(struct clk_hw *hw,
+				      struct clk_rate_request *req)
+{
+	struct owl_divider *div = hw_to_owl_divider(hw);
+
+	return divider_determine_rate(hw, req, div->div_hw.table,
+				      div->div_hw.width, div->div_hw.div_flags);
+}
+
+unsigned long owl_divider_helper_recalc_rate(struct owl_clk_common *common,
+					 const struct owl_divider_hw *div_hw,
+					 unsigned long parent_rate)
+{
+	unsigned long val;
+	unsigned int reg;
+
+	regmap_read(common->regmap, div_hw->reg, &reg);
+	val = reg >> div_hw->shift;
+	val &= (1 << div_hw->width) - 1;
+
+	return divider_recalc_rate(&common->hw, parent_rate,
+				   val, div_hw->table,
+				   div_hw->div_flags,
+				   div_hw->width);
+}
+
+static unsigned long owl_divider_recalc_rate(struct clk_hw *hw,
+					  unsigned long parent_rate)
+{
+	struct owl_divider *div = hw_to_owl_divider(hw);
+
+	return owl_divider_helper_recalc_rate(&div->common,
+					      &div->div_hw, parent_rate);
+}
+
+int owl_divider_helper_set_rate(const struct owl_clk_common *common,
+				const struct owl_divider_hw *div_hw,
+				unsigned long rate,
+				unsigned long parent_rate)
+{
+	unsigned long val;
+	unsigned int reg;
+
+	val = divider_get_val(rate, parent_rate, div_hw->table,
+			      div_hw->width, 0);
+
+	regmap_read(common->regmap, div_hw->reg, &reg);
+	reg &= ~GENMASK(div_hw->width + div_hw->shift - 1, div_hw->shift);
+
+	regmap_write(common->regmap, div_hw->reg,
+			  reg | (val << div_hw->shift));
+
+	return 0;
+}
+
+static int owl_divider_set_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long parent_rate)
+{
+	struct owl_divider *div = hw_to_owl_divider(hw);
+
+	return owl_divider_helper_set_rate(&div->common, &div->div_hw,
+					rate, parent_rate);
+}
+
+const struct clk_ops owl_divider_ops = {
+	.recalc_rate = owl_divider_recalc_rate,
+	.determine_rate = owl_divider_determine_rate,
+	.set_rate = owl_divider_set_rate,
+};