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, 71 insertions, 0 deletions

diff --git a/tools/perf/util/counts.c b/tools/perf/util/counts.c
new file mode 100644
index 000000000..11cd85b27
--- /dev/null
+++ b/tools/perf/util/counts.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include "evsel.h"
+#include "counts.h"
+#include <perf/threadmap.h>
+#include <linux/zalloc.h>
+
+struct perf_counts *perf_counts__new(int ncpus, int nthreads)
+{
+	struct perf_counts *counts = zalloc(sizeof(*counts));
+
+	if (counts) {
+		struct xyarray *values;
+
+		values = xyarray__new(ncpus, nthreads, sizeof(struct perf_counts_values));
+		if (!values) {
+			free(counts);
+			return NULL;
+		}
+
+		counts->values = values;
+
+		values = xyarray__new(ncpus, nthreads, sizeof(bool));
+		if (!values) {
+			xyarray__delete(counts->values);
+			free(counts);
+			return NULL;
+		}
+
+		counts->loaded = values;
+	}
+
+	return counts;
+}
+
+void perf_counts__delete(struct perf_counts *counts)
+{
+	if (counts) {
+		xyarray__delete(counts->loaded);
+		xyarray__delete(counts->values);
+		free(counts);
+	}
+}
+
+void perf_counts__reset(struct perf_counts *counts)
+{
+	xyarray__reset(counts->loaded);
+	xyarray__reset(counts->values);
+}
+
+void evsel__reset_counts(struct evsel *evsel)
+{
+	perf_counts__reset(evsel->counts);
+}
+
+int evsel__alloc_counts(struct evsel *evsel)
+{
+	struct perf_cpu_map *cpus = evsel__cpus(evsel);
+	int nthreads = perf_thread_map__nr(evsel->core.threads);
+
+	evsel->counts = perf_counts__new(perf_cpu_map__nr(cpus), nthreads);
+	return evsel->counts != NULL ? 0 : -ENOMEM;
+}
+
+void evsel__free_counts(struct evsel *evsel)
+{
+	perf_counts__delete(evsel->counts);
+	evsel->counts = NULL;
+}