bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 73 insertions, 0 deletions

diff --git a/tools/perf/util/bpf-event.h b/tools/perf/util/bpf-event.h
new file mode 100644
index 000000000..da4eeb4a1
--- /dev/null
+++ b/tools/perf/util/bpf-event.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_BPF_EVENT_H
+#define __PERF_BPF_EVENT_H
+
+#include <linux/compiler.h>
+#include <linux/rbtree.h>
+#include <api/fd/array.h>
+#include <stdio.h>
+
+struct bpf_prog_info;
+struct machine;
+union perf_event;
+struct perf_env;
+struct perf_sample;
+struct perf_session;
+struct record_opts;
+struct evlist;
+struct target;
+
+struct bpf_metadata {
+	union perf_event *event;
+	char		 **prog_names;
+	__u64		 nr_prog_names;
+};
+
+struct bpf_prog_info_node {
+	struct perf_bpil		*info_linear;
+	struct bpf_metadata		*metadata;
+	struct rb_node			rb_node;
+};
+
+struct btf_node {
+	struct rb_node	rb_node;
+	u32		id;
+	u32		data_size;
+	char		data[];
+};
+
+#ifdef HAVE_LIBBPF_SUPPORT
+int machine__process_bpf(struct machine *machine, union perf_event *event,
+			 struct perf_sample *sample);
+int evlist__add_bpf_sb_event(struct evlist *evlist, struct perf_env *env);
+void __bpf_event__print_bpf_prog_info(struct perf_bpil *info_linear,
+				      struct perf_env *env,
+				      FILE *fp);
+void bpf_metadata_free(struct bpf_metadata *metadata);
+#else
+static inline int machine__process_bpf(struct machine *machine __maybe_unused,
+				       union perf_event *event __maybe_unused,
+				       struct perf_sample *sample __maybe_unused)
+{
+	return 0;
+}
+
+static inline int evlist__add_bpf_sb_event(struct evlist *evlist __maybe_unused,
+					   struct perf_env *env __maybe_unused)
+{
+	return 0;
+}
+
+static inline void __bpf_event__print_bpf_prog_info(struct perf_bpil *info_linear __maybe_unused,
+						    struct perf_env *env __maybe_unused,
+						    FILE *fp __maybe_unused)
+{
+
+}
+
+static inline void bpf_metadata_free(struct bpf_metadata *metadata __maybe_unused)
+{
+
+}
+#endif // HAVE_LIBBPF_SUPPORT
+#endif