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, 74 insertions, 0 deletions

diff --git a/drivers/clk/qcom/kpss-xcc.c b/drivers/clk/qcom/kpss-xcc.c
new file mode 100644
index 000000000..97bfb21a5
--- /dev/null
+++ b/drivers/clk/qcom/kpss-xcc.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018, The Linux Foundation. All rights reserved.
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+
+static const struct clk_parent_data aux_parents[] = {
+	{ .fw_name = "pll8_vote", .name = "pll8_vote" },
+	{ .fw_name = "pxo", .name = "pxo_board" },
+};
+
+static const u32 aux_parent_map[] = {
+	3,
+	0,
+};
+
+static const struct of_device_id kpss_xcc_match_table[] = {
+	{ .compatible = "qcom,kpss-acc-v1", .data = (void *)1UL },
+	{ .compatible = "qcom,kpss-gcc" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, kpss_xcc_match_table);
+
+static int kpss_xcc_driver_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	void __iomem *base;
+	struct clk_hw *hw;
+	const char *name;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	if (device_get_match_data(&pdev->dev)) {
+		if (of_property_read_string_index(dev->of_node,
+						  "clock-output-names",
+						  0, &name))
+			return -ENODEV;
+		base += 0x14;
+	} else {
+		name = "acpu_l2_aux";
+		base += 0x28;
+	}
+
+	hw = devm_clk_hw_register_mux_parent_data_table(dev, name, aux_parents,
+							ARRAY_SIZE(aux_parents), 0,
+							base, 0, 0x3,
+							0, aux_parent_map, NULL);
+	if (IS_ERR(hw))
+		return PTR_ERR(hw);
+
+	return of_clk_add_hw_provider(dev->of_node, of_clk_hw_simple_get, hw);
+}
+
+static struct platform_driver kpss_xcc_driver = {
+	.probe = kpss_xcc_driver_probe,
+	.driver = {
+		.name = "kpss-xcc",
+		.of_match_table = kpss_xcc_match_table,
+	},
+};
+module_platform_driver(kpss_xcc_driver);
+
+MODULE_DESCRIPTION("Krait Processor Sub System (KPSS) Clock Driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:kpss-xcc");