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, 144 insertions, 0 deletions

diff --git a/drivers/clk/meson/vclk.c b/drivers/clk/meson/vclk.c
new file mode 100644
index 000000000..009bd1193
--- /dev/null
+++ b/drivers/clk/meson/vclk.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2024 Neil Armstrong <neil.armstrong@linaro.org>
+ */
+
+#include <linux/module.h>
+#include "vclk.h"
+
+/* The VCLK gate has a supplementary reset bit to pulse after ungating */
+
+static inline struct meson_vclk_gate_data *
+clk_get_meson_vclk_gate_data(struct clk_regmap *clk)
+{
+	return (struct meson_vclk_gate_data *)clk->data;
+}
+
+static int meson_vclk_gate_enable(struct clk_hw *hw)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_vclk_gate_data *vclk = clk_get_meson_vclk_gate_data(clk);
+
+	meson_parm_write(clk->map, &vclk->enable, 1);
+
+	/* Do a reset pulse */
+	meson_parm_write(clk->map, &vclk->reset, 1);
+	meson_parm_write(clk->map, &vclk->reset, 0);
+
+	return 0;
+}
+
+static void meson_vclk_gate_disable(struct clk_hw *hw)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_vclk_gate_data *vclk = clk_get_meson_vclk_gate_data(clk);
+
+	meson_parm_write(clk->map, &vclk->enable, 0);
+}
+
+static int meson_vclk_gate_is_enabled(struct clk_hw *hw)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_vclk_gate_data *vclk = clk_get_meson_vclk_gate_data(clk);
+
+	return meson_parm_read(clk->map, &vclk->enable);
+}
+
+const struct clk_ops meson_vclk_gate_ops = {
+	.init = clk_regmap_init,
+	.enable = meson_vclk_gate_enable,
+	.disable = meson_vclk_gate_disable,
+	.is_enabled = meson_vclk_gate_is_enabled,
+};
+EXPORT_SYMBOL_NS_GPL(meson_vclk_gate_ops, "CLK_MESON");
+
+/* The VCLK Divider has supplementary reset & enable bits */
+
+static inline struct meson_vclk_div_data *
+clk_get_meson_vclk_div_data(struct clk_regmap *clk)
+{
+	return (struct meson_vclk_div_data *)clk->data;
+}
+
+static unsigned long meson_vclk_div_recalc_rate(struct clk_hw *hw,
+						unsigned long prate)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_vclk_div_data *vclk = clk_get_meson_vclk_div_data(clk);
+
+	return divider_recalc_rate(hw, prate, meson_parm_read(clk->map, &vclk->div),
+				   vclk->table, vclk->flags, vclk->div.width);
+}
+
+static int meson_vclk_div_determine_rate(struct clk_hw *hw,
+					 struct clk_rate_request *req)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_vclk_div_data *vclk = clk_get_meson_vclk_div_data(clk);
+
+	return divider_determine_rate(hw, req, vclk->table, vclk->div.width,
+				      vclk->flags);
+}
+
+static int meson_vclk_div_set_rate(struct clk_hw *hw, unsigned long rate,
+				   unsigned long parent_rate)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_vclk_div_data *vclk = clk_get_meson_vclk_div_data(clk);
+	int ret;
+
+	ret = divider_get_val(rate, parent_rate, vclk->table, vclk->div.width,
+			      vclk->flags);
+	if (ret < 0)
+		return ret;
+
+	meson_parm_write(clk->map, &vclk->div, ret);
+
+	return 0;
+};
+
+static int meson_vclk_div_enable(struct clk_hw *hw)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_vclk_div_data *vclk = clk_get_meson_vclk_div_data(clk);
+
+	/* Unreset the divider when ungating */
+	meson_parm_write(clk->map, &vclk->reset, 0);
+	meson_parm_write(clk->map, &vclk->enable, 1);
+
+	return 0;
+}
+
+static void meson_vclk_div_disable(struct clk_hw *hw)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_vclk_div_data *vclk = clk_get_meson_vclk_div_data(clk);
+
+	/* Reset the divider when gating */
+	meson_parm_write(clk->map, &vclk->enable, 0);
+	meson_parm_write(clk->map, &vclk->reset, 1);
+}
+
+static int meson_vclk_div_is_enabled(struct clk_hw *hw)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_vclk_div_data *vclk = clk_get_meson_vclk_div_data(clk);
+
+	return meson_parm_read(clk->map, &vclk->enable);
+}
+
+const struct clk_ops meson_vclk_div_ops = {
+	.init = clk_regmap_init,
+	.recalc_rate = meson_vclk_div_recalc_rate,
+	.determine_rate = meson_vclk_div_determine_rate,
+	.set_rate = meson_vclk_div_set_rate,
+	.enable = meson_vclk_div_enable,
+	.disable = meson_vclk_div_disable,
+	.is_enabled = meson_vclk_div_is_enabled,
+};
+EXPORT_SYMBOL_NS_GPL(meson_vclk_div_ops, "CLK_MESON");
+
+MODULE_DESCRIPTION("Amlogic vclk clock driver");
+MODULE_AUTHOR("Neil Armstrong <neil.armstrong@linaro.org>");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("CLK_MESON");