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, 197 insertions, 0 deletions

diff --git a/drivers/clk/at91/pmc.c b/drivers/clk/at91/pmc.c
new file mode 100644
index 000000000..03a6c31d6
--- /dev/null
+++ b/drivers/clk/at91/pmc.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/clk/at91_pmc.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/mfd/syscon.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/syscore_ops.h>
+
+#include <asm/proc-fns.h>
+
+#include "pmc.h"
+
+#define PMC_MAX_IDS 128
+#define PMC_MAX_PCKS 8
+
+int of_at91_get_clk_range(struct device_node *np, const char *propname,
+			  struct clk_range *range)
+{
+	u32 min, max;
+	int ret;
+
+	ret = of_property_read_u32_index(np, propname, 0, &min);
+	if (ret)
+		return ret;
+
+	ret = of_property_read_u32_index(np, propname, 1, &max);
+	if (ret)
+		return ret;
+
+	if (range) {
+		range->min = min;
+		range->max = max;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_at91_get_clk_range);
+
+struct clk_hw *of_clk_hw_pmc_get(struct of_phandle_args *clkspec, void *data)
+{
+	unsigned int type = clkspec->args[0];
+	unsigned int idx = clkspec->args[1];
+	struct pmc_data *pmc_data = data;
+
+	switch (type) {
+	case PMC_TYPE_CORE:
+		if (idx < pmc_data->ncore)
+			return pmc_data->chws[idx];
+		break;
+	case PMC_TYPE_SYSTEM:
+		if (idx < pmc_data->nsystem)
+			return pmc_data->shws[idx];
+		break;
+	case PMC_TYPE_PERIPHERAL:
+		if (idx < pmc_data->nperiph)
+			return pmc_data->phws[idx];
+		break;
+	case PMC_TYPE_GCK:
+		if (idx < pmc_data->ngck)
+			return pmc_data->ghws[idx];
+		break;
+	case PMC_TYPE_PROGRAMMABLE:
+		if (idx < pmc_data->npck)
+			return pmc_data->pchws[idx];
+		break;
+	default:
+		break;
+	}
+
+	pr_err("%s: invalid type (%u) or index (%u)\n", __func__, type, idx);
+
+	return ERR_PTR(-EINVAL);
+}
+
+struct pmc_data *pmc_data_allocate(unsigned int ncore, unsigned int nsystem,
+				   unsigned int nperiph, unsigned int ngck,
+				   unsigned int npck)
+{
+	unsigned int num_clks = ncore + nsystem + nperiph + ngck + npck;
+	struct pmc_data *pmc_data;
+
+	pmc_data = kzalloc_flex(*pmc_data, hwtable, num_clks);
+	if (!pmc_data)
+		return NULL;
+
+	pmc_data->ncore = ncore;
+	pmc_data->chws = pmc_data->hwtable;
+
+	pmc_data->nsystem = nsystem;
+	pmc_data->shws = pmc_data->chws + ncore;
+
+	pmc_data->nperiph = nperiph;
+	pmc_data->phws = pmc_data->shws + nsystem;
+
+	pmc_data->ngck = ngck;
+	pmc_data->ghws = pmc_data->phws + nperiph;
+
+	pmc_data->npck = npck;
+	pmc_data->pchws = pmc_data->ghws + ngck;
+
+	return pmc_data;
+}
+
+#ifdef CONFIG_PM
+
+/* Address in SECURAM that say if we suspend to backup mode. */
+static void __iomem *at91_pmc_backup_suspend;
+
+static int at91_pmc_suspend(void *data)
+{
+	unsigned int backup;
+
+	if (!at91_pmc_backup_suspend)
+		return 0;
+
+	backup = readl_relaxed(at91_pmc_backup_suspend);
+	if (!backup)
+		return 0;
+
+	return clk_save_context();
+}
+
+static void at91_pmc_resume(void *data)
+{
+	unsigned int backup;
+
+	if (!at91_pmc_backup_suspend)
+		return;
+
+	backup = readl_relaxed(at91_pmc_backup_suspend);
+	if (!backup)
+		return;
+
+	clk_restore_context();
+}
+
+static const struct syscore_ops pmc_syscore_ops = {
+	.suspend = at91_pmc_suspend,
+	.resume = at91_pmc_resume,
+};
+
+static struct syscore pmc_syscore = {
+	.ops = &pmc_syscore_ops,
+};
+
+static const struct of_device_id pmc_dt_ids[] = {
+	{ .compatible = "atmel,sama5d2-pmc" },
+	{ .compatible = "microchip,sama7g5-pmc", },
+	{ .compatible = "microchip,sama7d65-pmc", },
+	{ /* sentinel */ }
+};
+
+static int __init pmc_register_ops(void)
+{
+	struct device_node *np;
+
+	np = of_find_matching_node(NULL, pmc_dt_ids);
+	if (!np)
+		return -ENODEV;
+
+	if (!of_device_is_available(np)) {
+		of_node_put(np);
+		return -ENODEV;
+	}
+	of_node_put(np);
+
+	np = of_find_compatible_node(NULL, NULL, "atmel,sama5d2-securam");
+	if (!np)
+		return -ENODEV;
+
+	if (!of_device_is_available(np)) {
+		of_node_put(np);
+		return -ENODEV;
+	}
+
+	at91_pmc_backup_suspend = of_iomap(np, 0);
+	of_node_put(np);
+	if (!at91_pmc_backup_suspend) {
+		pr_warn("%s(): unable to map securam\n", __func__);
+		return -ENOMEM;
+	}
+
+	register_syscore(&pmc_syscore);
+
+	return 0;
+}
+/* This has to happen before arch_initcall because of the tcb_clksrc driver */
+postcore_initcall(pmc_register_ops);
+#endif