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, 144 insertions, 0 deletions

diff --git a/drivers/base/physical_location.c b/drivers/base/physical_location.c
new file mode 100644
index 000000000..2e723fff6
--- /dev/null
+++ b/drivers/base/physical_location.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Device physical location support
+ *
+ * Author: Won Chung <wonchung@google.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/sysfs.h>
+#include <linux/string_choices.h>
+
+#include "physical_location.h"
+
+bool dev_add_physical_location(struct device *dev)
+{
+	struct acpi_pld_info *pld;
+
+	if (!has_acpi_companion(dev))
+		return false;
+
+	if (!acpi_get_physical_device_location(ACPI_HANDLE(dev), &pld))
+		return false;
+
+	dev->physical_location = kzalloc_obj(*dev->physical_location);
+	if (!dev->physical_location) {
+		ACPI_FREE(pld);
+		return false;
+	}
+
+	dev->physical_location->panel = pld->panel;
+	dev->physical_location->vertical_position = pld->vertical_position;
+	dev->physical_location->horizontal_position = pld->horizontal_position;
+	dev->physical_location->dock = pld->dock;
+	dev->physical_location->lid = pld->lid;
+
+	ACPI_FREE(pld);
+	return true;
+}
+
+static ssize_t panel_show(struct device *dev, struct device_attribute *attr,
+	char *buf)
+{
+	const char *panel;
+
+	switch (dev->physical_location->panel) {
+	case DEVICE_PANEL_TOP:
+		panel = "top";
+		break;
+	case DEVICE_PANEL_BOTTOM:
+		panel = "bottom";
+		break;
+	case DEVICE_PANEL_LEFT:
+		panel = "left";
+		break;
+	case DEVICE_PANEL_RIGHT:
+		panel = "right";
+		break;
+	case DEVICE_PANEL_FRONT:
+		panel = "front";
+		break;
+	case DEVICE_PANEL_BACK:
+		panel = "back";
+		break;
+	default:
+		panel = "unknown";
+	}
+	return sysfs_emit(buf, "%s\n", panel);
+}
+static DEVICE_ATTR_RO(panel);
+
+static ssize_t vertical_position_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	const char *vertical_position;
+
+	switch (dev->physical_location->vertical_position) {
+	case DEVICE_VERT_POS_UPPER:
+		vertical_position = "upper";
+		break;
+	case DEVICE_VERT_POS_CENTER:
+		vertical_position = "center";
+		break;
+	case DEVICE_VERT_POS_LOWER:
+		vertical_position = "lower";
+		break;
+	default:
+		vertical_position = "unknown";
+	}
+	return sysfs_emit(buf, "%s\n", vertical_position);
+}
+static DEVICE_ATTR_RO(vertical_position);
+
+static ssize_t horizontal_position_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	const char *horizontal_position;
+
+	switch (dev->physical_location->horizontal_position) {
+	case DEVICE_HORI_POS_LEFT:
+		horizontal_position = "left";
+		break;
+	case DEVICE_HORI_POS_CENTER:
+		horizontal_position = "center";
+		break;
+	case DEVICE_HORI_POS_RIGHT:
+		horizontal_position = "right";
+		break;
+	default:
+		horizontal_position = "unknown";
+	}
+	return sysfs_emit(buf, "%s\n", horizontal_position);
+}
+static DEVICE_ATTR_RO(horizontal_position);
+
+static ssize_t dock_show(struct device *dev, struct device_attribute *attr,
+	char *buf)
+{
+	return sysfs_emit(buf, "%s\n",
+		str_yes_no(dev->physical_location->dock));
+}
+static DEVICE_ATTR_RO(dock);
+
+static ssize_t lid_show(struct device *dev, struct device_attribute *attr,
+	char *buf)
+{
+	return sysfs_emit(buf, "%s\n",
+		str_yes_no(dev->physical_location->lid));
+}
+static DEVICE_ATTR_RO(lid);
+
+static struct attribute *dev_attr_physical_location[] = {
+	&dev_attr_panel.attr,
+	&dev_attr_vertical_position.attr,
+	&dev_attr_horizontal_position.attr,
+	&dev_attr_dock.attr,
+	&dev_attr_lid.attr,
+	NULL,
+};
+
+const struct attribute_group dev_attr_physical_location_group = {
+	.name = "physical_location",
+	.attrs = dev_attr_physical_location,
+};
+