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, 82 insertions, 0 deletions

diff --git a/drivers/clk/qcom/clk-regmap-divider.c b/drivers/clk/qcom/clk-regmap-divider.c
new file mode 100644
index 000000000..672e82caf
--- /dev/null
+++ b/drivers/clk/qcom/clk-regmap-divider.c
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/regmap.h>
+#include <linux/export.h>
+
+#include "clk-regmap-divider.h"
+
+static inline struct clk_regmap_div *to_clk_regmap_div(struct clk_hw *hw)
+{
+	return container_of(to_clk_regmap(hw), struct clk_regmap_div, clkr);
+}
+
+static int div_ro_determine_rate(struct clk_hw *hw,
+				 struct clk_rate_request *req)
+{
+	struct clk_regmap_div *divider = to_clk_regmap_div(hw);
+	struct clk_regmap *clkr = &divider->clkr;
+	u32 val;
+
+	regmap_read(clkr->regmap, divider->reg, &val);
+	val >>= divider->shift;
+	val &= BIT(divider->width) - 1;
+
+	return divider_ro_determine_rate(hw, req, NULL, divider->width,
+					 CLK_DIVIDER_ROUND_CLOSEST, val);
+}
+
+static int div_determine_rate(struct clk_hw *hw, struct clk_rate_request *req)
+{
+	struct clk_regmap_div *divider = to_clk_regmap_div(hw);
+
+	return divider_determine_rate(hw, req, NULL, divider->width,
+				      CLK_DIVIDER_ROUND_CLOSEST);
+}
+
+static int div_set_rate(struct clk_hw *hw, unsigned long rate,
+			unsigned long parent_rate)
+{
+	struct clk_regmap_div *divider = to_clk_regmap_div(hw);
+	struct clk_regmap *clkr = &divider->clkr;
+	u32 div;
+
+	div = divider_get_val(rate, parent_rate, NULL, divider->width,
+			      CLK_DIVIDER_ROUND_CLOSEST);
+
+	return regmap_update_bits(clkr->regmap, divider->reg,
+				  (BIT(divider->width) - 1) << divider->shift,
+				  div << divider->shift);
+}
+
+static unsigned long div_recalc_rate(struct clk_hw *hw,
+				     unsigned long parent_rate)
+{
+	struct clk_regmap_div *divider = to_clk_regmap_div(hw);
+	struct clk_regmap *clkr = &divider->clkr;
+	u32 div;
+
+	regmap_read(clkr->regmap, divider->reg, &div);
+	div >>= divider->shift;
+	div &= BIT(divider->width) - 1;
+
+	return divider_recalc_rate(hw, parent_rate, div, NULL,
+				   CLK_DIVIDER_ROUND_CLOSEST, divider->width);
+}
+
+const struct clk_ops clk_regmap_div_ops = {
+	.determine_rate = div_determine_rate,
+	.set_rate = div_set_rate,
+	.recalc_rate = div_recalc_rate,
+};
+EXPORT_SYMBOL_GPL(clk_regmap_div_ops);
+
+const struct clk_ops clk_regmap_div_ro_ops = {
+	.determine_rate = div_ro_determine_rate,
+	.recalc_rate = div_recalc_rate,
+};
+EXPORT_SYMBOL_GPL(clk_regmap_div_ro_ops);