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, 99 insertions, 0 deletions

diff --git a/drivers/clk/clk-fixed-mmio.c b/drivers/clk/clk-fixed-mmio.c
new file mode 100644
index 000000000..3bfcf4cd9
--- /dev/null
+++ b/drivers/clk/clk-fixed-mmio.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Memory Mapped IO Fixed clock driver
+ *
+ * Copyright (C) 2018 Cadence Design Systems, Inc.
+ *
+ * Authors:
+ *	Jan Kotas <jank@cadence.com>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+
+static struct clk_hw *fixed_mmio_clk_setup(struct device_node *node)
+{
+	struct clk_hw *clk;
+	const char *clk_name = node->name;
+	void __iomem *base;
+	u32 freq;
+	int ret;
+
+	base = of_iomap(node, 0);
+	if (!base) {
+		pr_err("%pOFn: failed to map address\n", node);
+		return ERR_PTR(-EIO);
+	}
+
+	freq = readl(base);
+	iounmap(base);
+	of_property_read_string(node, "clock-output-names", &clk_name);
+
+	clk = clk_hw_register_fixed_rate(NULL, clk_name, NULL, 0, freq);
+	if (IS_ERR(clk)) {
+		pr_err("%pOFn: failed to register fixed rate clock\n", node);
+		return clk;
+	}
+
+	ret = of_clk_add_hw_provider(node, of_clk_hw_simple_get, clk);
+	if (ret) {
+		pr_err("%pOFn: failed to add clock provider\n", node);
+		clk_hw_unregister(clk);
+		clk = ERR_PTR(ret);
+	}
+
+	return clk;
+}
+
+static void __init of_fixed_mmio_clk_setup(struct device_node *node)
+{
+	fixed_mmio_clk_setup(node);
+}
+CLK_OF_DECLARE(fixed_mmio_clk, "fixed-mmio-clock", of_fixed_mmio_clk_setup);
+
+/*
+ * This is not executed when of_fixed_mmio_clk_setup succeeded.
+ */
+static int of_fixed_mmio_clk_probe(struct platform_device *pdev)
+{
+	struct clk_hw *clk;
+
+	clk = fixed_mmio_clk_setup(pdev->dev.of_node);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	platform_set_drvdata(pdev, clk);
+
+	return 0;
+}
+
+static void of_fixed_mmio_clk_remove(struct platform_device *pdev)
+{
+	struct clk_hw *clk = platform_get_drvdata(pdev);
+
+	of_clk_del_provider(pdev->dev.of_node);
+	clk_hw_unregister_fixed_rate(clk);
+}
+
+static const struct of_device_id of_fixed_mmio_clk_ids[] = {
+	{ .compatible = "fixed-mmio-clock" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, of_fixed_mmio_clk_ids);
+
+static struct platform_driver of_fixed_mmio_clk_driver = {
+	.driver = {
+		.name = "of_fixed_mmio_clk",
+		.of_match_table = of_fixed_mmio_clk_ids,
+	},
+	.probe = of_fixed_mmio_clk_probe,
+	.remove = of_fixed_mmio_clk_remove,
+};
+module_platform_driver(of_fixed_mmio_clk_driver);
+
+MODULE_AUTHOR("Jan Kotas <jank@cadence.com>");
+MODULE_DESCRIPTION("Memory Mapped IO Fixed clock driver");