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, 60 insertions, 0 deletions

diff --git a/drivers/crypto/caam/dpseci-debugfs.c b/drivers/crypto/caam/dpseci-debugfs.c
new file mode 100644
index 000000000..020a9d8a8
--- /dev/null
+++ b/drivers/crypto/caam/dpseci-debugfs.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
+/* Copyright 2019 NXP */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/debugfs.h>
+#include "dpseci-debugfs.h"
+
+static int dpseci_dbg_fqs_show(struct seq_file *file, void *offset)
+{
+	struct dpaa2_caam_priv *priv = file->private;
+	u32 fqid, fcnt, bcnt;
+	int i, err;
+
+	seq_printf(file, "FQ stats for %s:\n", dev_name(priv->dev));
+	seq_printf(file, "%s%16s%16s\n",
+		   "Rx-VFQID",
+		   "Pending frames",
+		   "Pending bytes");
+
+	for (i = 0; i <  priv->num_pairs; i++) {
+		fqid = priv->rx_queue_attr[i].fqid;
+		err = dpaa2_io_query_fq_count(NULL, fqid, &fcnt, &bcnt);
+		if (err)
+			continue;
+
+		seq_printf(file, "%5d%16u%16u\n", fqid, fcnt, bcnt);
+	}
+
+	seq_printf(file, "%s%16s%16s\n",
+		   "Tx-VFQID",
+		   "Pending frames",
+		   "Pending bytes");
+
+	for (i = 0; i <  priv->num_pairs; i++) {
+		fqid = priv->tx_queue_attr[i].fqid;
+		err = dpaa2_io_query_fq_count(NULL, fqid, &fcnt, &bcnt);
+		if (err)
+			continue;
+
+		seq_printf(file, "%5d%16u%16u\n", fqid, fcnt, bcnt);
+	}
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(dpseci_dbg_fqs);
+
+void dpaa2_dpseci_debugfs_init(struct dpaa2_caam_priv *priv)
+{
+	priv->dfs_root = debugfs_create_dir(dev_name(priv->dev), NULL);
+
+	debugfs_create_file("fq_stats", 0444, priv->dfs_root, priv,
+			    &dpseci_dbg_fqs_fops);
+}
+
+void dpaa2_dpseci_debugfs_exit(struct dpaa2_caam_priv *priv)
+{
+	debugfs_remove_recursive(priv->dfs_root);
+}