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, 88 insertions, 0 deletions

diff --git a/tools/perf/util/maps.h b/tools/perf/util/maps.h
new file mode 100644
index 000000000..4ec9b7453
--- /dev/null
+++ b/tools/perf/util/maps.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_MAPS_H
+#define __PERF_MAPS_H
+
+#include <linux/refcount.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <linux/types.h>
+
+struct ref_reloc_sym;
+struct machine;
+struct map;
+struct maps;
+
+#define KMAP_NAME_LEN 256
+
+struct kmap {
+	struct ref_reloc_sym *ref_reloc_sym;
+	struct maps	     *kmaps;
+	char		     name[KMAP_NAME_LEN];
+};
+
+struct maps *maps__new(struct machine *machine);
+bool maps__empty(struct maps *maps);
+int maps__copy_from(struct maps *maps, struct maps *parent);
+
+struct maps *maps__get(struct maps *maps);
+void maps__put(struct maps *maps);
+
+static inline void __maps__zput(struct maps **map)
+{
+	maps__put(*map);
+	*map = NULL;
+}
+
+#define maps__zput(map) __maps__zput(&map)
+
+bool maps__equal(struct maps *a, struct maps *b);
+
+/* Iterate over map calling cb for each entry. */
+int maps__for_each_map(struct maps *maps, int (*cb)(struct map *map, void *data), void *data);
+/* Iterate over map removing an entry if cb returns true. */
+void maps__remove_maps(struct maps *maps, bool (*cb)(struct map *map, void *data), void *data);
+
+struct machine *maps__machine(const struct maps *maps);
+unsigned int maps__nr_maps(const struct maps *maps); /* Test only. */
+refcount_t *maps__refcnt(struct maps *maps); /* Test only. */
+
+#ifdef HAVE_LIBUNWIND_SUPPORT
+void *maps__addr_space(const struct maps *maps);
+void maps__set_addr_space(struct maps *maps, void *addr_space);
+uint16_t maps__e_machine(const struct maps *maps);
+void maps__set_e_machine(struct maps *maps, uint16_t e_machine);
+#endif
+#ifdef HAVE_LIBDW_SUPPORT
+void *maps__libdw_addr_space_dwfl(const struct maps *maps);
+void maps__set_libdw_addr_space_dwfl(struct maps *maps, void *dwfl);
+#endif
+
+size_t maps__fprintf(struct maps *maps, FILE *fp);
+
+int maps__load_maps(struct maps *maps);
+int maps__insert(struct maps *maps, struct map *map);
+void maps__remove(struct maps *maps, struct map *map);
+int maps__mutate_mapping(struct maps *maps, struct map *map,
+			 int (*mutate_cb)(struct map *map, void *data), void *data);
+
+struct map *maps__find(struct maps *maps, u64 addr);
+struct symbol *maps__find_symbol(struct maps *maps, u64 addr, struct map **mapp);
+struct symbol *maps__find_symbol_by_name(struct maps *maps, const char *name, struct map **mapp);
+
+struct addr_map_symbol;
+
+int maps__find_ams(struct maps *maps, struct addr_map_symbol *ams);
+
+int maps__fixup_overlap_and_insert(struct maps *maps, struct map *new);
+
+struct map *maps__find_by_name(struct maps *maps, const char *name);
+
+struct map *maps__find_next_entry(struct maps *maps, struct map *map);
+
+int maps__merge_in(struct maps *kmaps, struct map *new_map);
+
+void maps__fixup_end(struct maps *maps);
+
+void maps__load_first(struct maps *maps);
+
+#endif // __PERF_MAPS_H