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, 55 insertions, 0 deletions

diff --git a/drivers/hwmon/peci/common.h b/drivers/hwmon/peci/common.h
new file mode 100644
index 000000000..5eae9681e
--- /dev/null
+++ b/drivers/hwmon/peci/common.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright (c) 2021 Intel Corporation */
+
+#include <linux/types.h>
+
+#ifndef __PECI_HWMON_COMMON_H
+#define __PECI_HWMON_COMMON_H
+
+#define PECI_HWMON_UPDATE_INTERVAL	HZ
+
+/**
+ * struct peci_sensor_state - PECI state information
+ * @valid: flag to indicate the sensor value is valid
+ * @last_updated: time of the last update in jiffies
+ */
+struct peci_sensor_state {
+	bool valid;
+	unsigned long last_updated;
+};
+
+/**
+ * struct peci_sensor_data - PECI sensor information
+ * @value: sensor value in milli units
+ * @state: sensor update state
+ */
+
+struct peci_sensor_data {
+	s32 value;
+	struct peci_sensor_state state;
+};
+
+/**
+ * peci_sensor_need_update() - check whether sensor update is needed or not
+ * @state: pointer to sensor state struct
+ *
+ * Return: true if update is needed, false if not.
+ */
+
+static inline bool peci_sensor_need_update(struct peci_sensor_state *state)
+{
+	return !state->valid ||
+	       time_after(jiffies, state->last_updated + PECI_HWMON_UPDATE_INTERVAL);
+}
+
+/**
+ * peci_sensor_mark_updated() - mark the sensor is updated
+ * @state: pointer to sensor state struct
+ */
+static inline void peci_sensor_mark_updated(struct peci_sensor_state *state)
+{
+	state->valid = true;
+	state->last_updated = jiffies;
+}
+
+#endif /* __PECI_HWMON_COMMON_H */