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, 67 insertions, 0 deletions

diff --git a/drivers/hwmon/pmbus/mp5023.c b/drivers/hwmon/pmbus/mp5023.c
new file mode 100644
index 000000000..c466d67e9
--- /dev/null
+++ b/drivers/hwmon/pmbus/mp5023.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for MPS MP5023 Hot-Swap Controller
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include "pmbus.h"
+
+static struct pmbus_driver_info mp5023_info = {
+	.pages = 1,
+
+	.format[PSC_VOLTAGE_IN] = direct,
+	.format[PSC_VOLTAGE_OUT] = direct,
+	.format[PSC_CURRENT_OUT] = direct,
+	.format[PSC_POWER] = direct,
+	.format[PSC_TEMPERATURE] = direct,
+
+	.m[PSC_VOLTAGE_IN] = 32,
+	.b[PSC_VOLTAGE_IN] = 0,
+	.R[PSC_VOLTAGE_IN] = 0,
+	.m[PSC_VOLTAGE_OUT] = 32,
+	.b[PSC_VOLTAGE_OUT] = 0,
+	.R[PSC_VOLTAGE_OUT] = 0,
+	.m[PSC_CURRENT_OUT] = 16,
+	.b[PSC_CURRENT_OUT] = 0,
+	.R[PSC_CURRENT_OUT] = 0,
+	.m[PSC_POWER] = 1,
+	.b[PSC_POWER] = 0,
+	.R[PSC_POWER] = 0,
+	.m[PSC_TEMPERATURE] = 2,
+	.b[PSC_TEMPERATURE] = 0,
+	.R[PSC_TEMPERATURE] = 0,
+
+	.func[0] =
+		PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_PIN |
+		PMBUS_HAVE_TEMP | PMBUS_HAVE_IOUT |
+		PMBUS_HAVE_STATUS_INPUT | PMBUS_HAVE_STATUS_TEMP,
+};
+
+static int mp5023_probe(struct i2c_client *client)
+{
+	return pmbus_do_probe(client, &mp5023_info);
+}
+
+static const struct of_device_id __maybe_unused mp5023_of_match[] = {
+	{ .compatible = "mps,mp5023", },
+	{}
+};
+
+MODULE_DEVICE_TABLE(of, mp5023_of_match);
+
+static struct i2c_driver mp5023_driver = {
+	.driver = {
+		   .name = "mp5023",
+		   .of_match_table = of_match_ptr(mp5023_of_match),
+	},
+	.probe = mp5023_probe,
+};
+
+module_i2c_driver(mp5023_driver);
+
+MODULE_AUTHOR("Howard Chiu <howard.chiu@quantatw.com>");
+MODULE_DESCRIPTION("PMBus driver for MPS MP5023 HSC");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("PMBUS");