Merge branch 'bpf-stacktrace-map-next-key-support'

Yonghong Song says:

====================
The patch set implements bpf syscall command BPF_MAP_GET_NEXT_KEY
for stacktrace map. Patch #1 is the core implementation
and Patch #2 implements a bpf test at tools/testing/selftests/bpf
directory. Please see individual patch comments for details.

Changelog:
  v1 -> v2:
   - For invalid key (key pointer is non-NULL), sets next_key to be the first valid key.
====================

Signed-off-by: Daniel Borkmann <[email protected]>

1 files changed, 26 insertions, 2 deletions

diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index a15bc636cc98..6c63c2222ea8 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -226,9 +226,33 @@ int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value)
 	return 0;
 }
 
-static int stack_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
+static int stack_map_get_next_key(struct bpf_map *map, void *key,
+				  void *next_key)
 {
-	return -EINVAL;
+	struct bpf_stack_map *smap = container_of(map,
+						  struct bpf_stack_map, map);
+	u32 id;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	if (!key) {
+		id = 0;
+	} else {
+		id = *(u32 *)key;
+		if (id >= smap->n_buckets || !smap->buckets[id])
+			id = 0;
+		else
+			id++;
+	}
+
+	while (id < smap->n_buckets && !smap->buckets[id])
+		id++;
+
+	if (id >= smap->n_buckets)
+		return -ENOENT;
+
+	*(u32 *)next_key = id;
+	return 0;
 }
 
 static int stack_map_update_elem(struct bpf_map *map, void *key, void *value,