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, 41 insertions, 0 deletions

diff --git a/include/drm/intel/intel-gtt.h b/include/drm/intel/intel-gtt.h
new file mode 100644
index 000000000..f53bcff01
--- /dev/null
+++ b/include/drm/intel/intel-gtt.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Common header for intel-gtt.ko and i915.ko */
+
+#ifndef _DRM_INTEL_GTT_H
+#define	_DRM_INTEL_GTT_H
+
+#include <linux/types.h>
+
+struct agp_bridge_data;
+struct pci_dev;
+struct sg_table;
+
+void intel_gmch_gtt_get(u64 *gtt_total,
+			phys_addr_t *mappable_base,
+			resource_size_t *mappable_end);
+
+int intel_gmch_probe(struct pci_dev *bridge_pdev, struct pci_dev *gpu_pdev,
+		     struct agp_bridge_data *bridge);
+void intel_gmch_remove(void);
+
+bool intel_gmch_enable_gtt(void);
+
+void intel_gmch_gtt_flush(void);
+void intel_gmch_gtt_insert_page(dma_addr_t addr,
+				unsigned int pg,
+				unsigned int flags);
+void intel_gmch_gtt_insert_sg_entries(struct sg_table *st,
+				      unsigned int pg_start,
+				      unsigned int flags);
+void intel_gmch_gtt_clear_range(unsigned int first_entry, unsigned int num_entries);
+dma_addr_t intel_gmch_gtt_read_entry(unsigned int pg,
+				     bool *is_present, bool *is_local);
+
+/* Special gtt memory types */
+#define AGP_DCACHE_MEMORY	1
+#define AGP_PHYS_MEMORY		2
+
+/* flag for GFDT type */
+#define AGP_USER_CACHED_MEMORY_GFDT (1 << 3)
+
+#endif