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, 110 insertions, 0 deletions

diff --git a/drivers/dma/ti/k3-psil.c b/drivers/dma/ti/k3-psil.c
new file mode 100644
index 000000000..c4b6f0df4
--- /dev/null
+++ b/drivers/dma/ti/k3-psil.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com
+ *  Author: Peter Ujfalusi <peter.ujfalusi@ti.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/sys_soc.h>
+
+#include "k3-psil-priv.h"
+
+static DEFINE_MUTEX(ep_map_mutex);
+static const struct psil_ep_map *soc_ep_map;
+
+static const struct soc_device_attribute k3_soc_devices[] = {
+	{ .family = "AM65X", .data = &am654_ep_map },
+	{ .family = "J721E", .data = &j721e_ep_map },
+	{ .family = "J7200", .data = &j7200_ep_map },
+	{ .family = "AM64X", .data = &am64_ep_map },
+	{ .family = "J721S2", .data = &j721s2_ep_map },
+	{ .family = "AM62X", .data = &am62_ep_map },
+	{ .family = "AM62AX", .data = &am62a_ep_map },
+	{ .family = "J784S4", .data = &j784s4_ep_map },
+	{ .family = "AM62PX", .data = &am62p_ep_map },
+	{ .family = "J722S", .data = &am62p_ep_map },
+	{ /* sentinel */ }
+};
+
+struct psil_endpoint_config *psil_get_ep_config(u32 thread_id)
+{
+	int i;
+
+	mutex_lock(&ep_map_mutex);
+	if (!soc_ep_map) {
+		const struct soc_device_attribute *soc;
+
+		soc = soc_device_match(k3_soc_devices);
+		if (soc) {
+			soc_ep_map = soc->data;
+		} else {
+			pr_err("PSIL: No compatible machine found for map\n");
+			mutex_unlock(&ep_map_mutex);
+			return ERR_PTR(-ENOTSUPP);
+		}
+		pr_debug("%s: Using map for %s\n", __func__, soc_ep_map->name);
+	}
+	mutex_unlock(&ep_map_mutex);
+
+	if (thread_id & K3_PSIL_DST_THREAD_ID_OFFSET && soc_ep_map->dst) {
+		/* check in destination thread map */
+		for (i = 0; i < soc_ep_map->dst_count; i++) {
+			if (soc_ep_map->dst[i].thread_id == thread_id)
+				return &soc_ep_map->dst[i].ep_config;
+		}
+	}
+
+	thread_id &= ~K3_PSIL_DST_THREAD_ID_OFFSET;
+	if (soc_ep_map->src) {
+		for (i = 0; i < soc_ep_map->src_count; i++) {
+			if (soc_ep_map->src[i].thread_id == thread_id)
+				return &soc_ep_map->src[i].ep_config;
+		}
+	}
+
+	return ERR_PTR(-ENOENT);
+}
+EXPORT_SYMBOL_GPL(psil_get_ep_config);
+
+int psil_set_new_ep_config(struct device *dev, const char *name,
+			   struct psil_endpoint_config *ep_config)
+{
+	struct psil_endpoint_config *dst_ep_config;
+	struct of_phandle_args dma_spec;
+	u32 thread_id;
+	int index;
+
+	if (!dev || !dev->of_node)
+		return -EINVAL;
+
+	index = of_property_match_string(dev->of_node, "dma-names", name);
+	if (index < 0)
+		return index;
+
+	if (of_parse_phandle_with_args(dev->of_node, "dmas", "#dma-cells",
+				       index, &dma_spec))
+		return -ENOENT;
+
+	thread_id = dma_spec.args[0];
+
+	dst_ep_config = psil_get_ep_config(thread_id);
+	if (IS_ERR(dst_ep_config)) {
+		pr_err("PSIL: thread ID 0x%04x not defined in map\n",
+		       thread_id);
+		of_node_put(dma_spec.np);
+		return PTR_ERR(dst_ep_config);
+	}
+
+	memcpy(dst_ep_config, ep_config, sizeof(*dst_ep_config));
+
+	of_node_put(dma_spec.np);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(psil_set_new_ep_config);
+MODULE_DESCRIPTION("K3 PSI-L endpoint configuration");
+MODULE_LICENSE("GPL v2");