selftests/bpf: Add test for bpf hash map iterators

Two subtests are added.
  $ ./test_progs -n 4
  ...
  #4/18 bpf_hash_map:OK
  #4/19 bpf_percpu_hash_map:OK
  ...

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200723184120.590916-1-yhs@fb.com

1 files changed, 50 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_bpf_percpu_hash_map.c b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_percpu_hash_map.c
new file mode 100644
index 000000000000..feaaa2b89c57
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_percpu_hash_map.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include "bpf_iter.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+struct key_t {
+	int a;
+	int b;
+	int c;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_HASH);
+	__uint(max_entries, 3);
+	__type(key, struct key_t);
+	__type(value, __u32);
+} hashmap1 SEC(".maps");
+
+/* will set before prog run */
+volatile const __u32 num_cpus = 0;
+
+/* will collect results during prog run */
+__u32 key_sum_a = 0, key_sum_b = 0, key_sum_c = 0;
+__u32 val_sum = 0;
+
+SEC("iter/bpf_map_elem")
+int dump_bpf_percpu_hash_map(struct bpf_iter__bpf_map_elem *ctx)
+{
+	struct key_t *key = ctx->key;
+	void *pptr = ctx->value;
+	__u32 step;
+	int i;
+
+	if (key == (void *)0 || pptr == (void *)0)
+		return 0;
+
+	key_sum_a += key->a;
+	key_sum_b += key->b;
+	key_sum_c += key->c;
+
+	step = 8;
+	for (i = 0; i < num_cpus; i++) {
+		val_sum += *(__u32 *)pptr;
+		pptr += step;
+	}
+	return 0;
+}