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, 111 insertions, 0 deletions

diff --git a/drivers/clk/meson/meson-clkc-utils.c b/drivers/clk/meson/meson-clkc-utils.c
new file mode 100644
index 000000000..870f50548
--- /dev/null
+++ b/drivers/clk/meson/meson-clkc-utils.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2023 Neil Armstrong <neil.armstrong@linaro.org>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include "meson-clkc-utils.h"
+
+struct clk_hw *meson_clk_hw_get(struct of_phandle_args *clkspec, void *clk_hw_data)
+{
+	const struct meson_clk_hw_data *data = clk_hw_data;
+	unsigned int idx = clkspec->args[0];
+
+	if (idx >= data->num) {
+		pr_err("%s: invalid index %u\n", __func__, idx);
+		return ERR_PTR(-EINVAL);
+	}
+
+	return data->hws[idx];
+}
+EXPORT_SYMBOL_NS_GPL(meson_clk_hw_get, "CLK_MESON");
+
+static int meson_clkc_init(struct device *dev, struct regmap *map)
+{
+	const struct meson_clkc_data *data;
+	struct clk_hw *hw;
+	int ret, i;
+
+	data = of_device_get_match_data(dev);
+	if (!data)
+		return -EINVAL;
+
+	if (data->init_count)
+		regmap_multi_reg_write(map, data->init_regs, data->init_count);
+
+	for (i = 0; i < data->hw_clks.num; i++) {
+		hw = data->hw_clks.hws[i];
+
+		/* array might be sparse */
+		if (!hw)
+			continue;
+
+		ret = devm_clk_hw_register(dev, hw);
+		if (ret) {
+			dev_err(dev, "registering %s clock failed\n",
+				hw->init->name);
+			return ret;
+		}
+	}
+
+	return devm_of_clk_add_hw_provider(dev, meson_clk_hw_get, (void *)&data->hw_clks);
+}
+
+int meson_clkc_syscon_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np;
+	struct regmap *map;
+
+	np = of_get_parent(dev->of_node);
+	map = syscon_node_to_regmap(np);
+	of_node_put(np);
+	if (IS_ERR(map)) {
+		dev_err(dev, "failed to get parent syscon regmap\n");
+		return PTR_ERR(map);
+	}
+
+	return meson_clkc_init(dev, map);
+}
+EXPORT_SYMBOL_NS_GPL(meson_clkc_syscon_probe, "CLK_MESON");
+
+int meson_clkc_mmio_probe(struct platform_device *pdev)
+{
+	const struct meson_clkc_data *data;
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	void __iomem *base;
+	struct regmap *map;
+	struct regmap_config regmap_cfg = {
+			.reg_bits	= 32,
+			.val_bits	= 32,
+			.reg_stride	= 4,
+	};
+
+	data = of_device_get_match_data(dev);
+	if (!data)
+		return -EINVAL;
+
+	base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	regmap_cfg.max_register = resource_size(res) - regmap_cfg.reg_stride;
+
+	map = devm_regmap_init_mmio(dev, base, &regmap_cfg);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+
+	return meson_clkc_init(dev, map);
+}
+EXPORT_SYMBOL_NS_GPL(meson_clkc_mmio_probe, "CLK_MESON");
+
+MODULE_DESCRIPTION("Amlogic Clock Controller Utilities");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("CLK_MESON");