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 <[e-mail]>
Signed-off-by: Alexei Starovoitov <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/testing/selftests/bpf/prog_tests/bpf_iter.c

···
 #include "bpf_iter_test_kern2.skel.h"
 #include "bpf_iter_test_kern3.skel.h"
 #include "bpf_iter_test_kern4.skel.h"
+#include "bpf_iter_bpf_hash_map.skel.h"
+#include "bpf_iter_bpf_percpu_hash_map.skel.h"
 
 static int duration;
 
···
 	bpf_iter_test_kern4__destroy(skel);
 }
 
+static void test_bpf_hash_map(void)
+{
+	__u32 expected_key_a = 0, expected_key_b = 0, expected_key_c = 0;
+	DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);
+	struct bpf_iter_bpf_hash_map *skel;
+	int err, i, len, map_fd, iter_fd;
+	__u64 val, expected_val = 0;
+	struct bpf_link *link;
+	struct key_t {
+		int a;
+		int b;
+		int c;
+	} key;
+	char buf[64];
+
+	skel = bpf_iter_bpf_hash_map__open();
+	if (CHECK(!skel, "bpf_iter_bpf_hash_map__open",
+		  "skeleton open failed\n"))
+		return;
+
+	skel->bss->in_test_mode = true;
+
+	err = bpf_iter_bpf_hash_map__load(skel);
+	if (CHECK(!skel, "bpf_iter_bpf_hash_map__load",
+		  "skeleton load failed\n"))
+		goto out;
+
+	/* iterator with hashmap2 and hashmap3 should fail */
+	opts.map_fd = bpf_map__fd(skel->maps.hashmap2);
+	link = bpf_program__attach_iter(skel->progs.dump_bpf_hash_map, &opts);
+	if (CHECK(!IS_ERR(link), "attach_iter",
+		  "attach_iter for hashmap2 unexpected succeeded\n"))
+		goto out;
+
+	opts.map_fd = bpf_map__fd(skel->maps.hashmap3);
+	link = bpf_program__attach_iter(skel->progs.dump_bpf_hash_map, &opts);
+	if (CHECK(!IS_ERR(link), "attach_iter",
+		  "attach_iter for hashmap3 unexpected succeeded\n"))
+		goto out;
+
+	/* hashmap1 should be good, update map values here */
+	map_fd = bpf_map__fd(skel->maps.hashmap1);
+	for (i = 0; i < bpf_map__max_entries(skel->maps.hashmap1); i++) {
+		key.a = i + 1;
+		key.b = i + 2;
+		key.c = i + 3;
+		val = i + 4;
+		expected_key_a += key.a;
+		expected_key_b += key.b;
+		expected_key_c += key.c;
+		expected_val += val;
+
+		err = bpf_map_update_elem(map_fd, &key, &val, BPF_ANY);
+		if (CHECK(err, "map_update", "map_update failed\n"))
+			goto out;
+	}
+
+	opts.map_fd = map_fd;
+	link = bpf_program__attach_iter(skel->progs.dump_bpf_hash_map, &opts);
+	if (CHECK(IS_ERR(link), "attach_iter", "attach_iter failed\n"))
+		goto out;
+
+	iter_fd = bpf_iter_create(bpf_link__fd(link));
+	if (CHECK(iter_fd < 0, "create_iter", "create_iter failed\n"))
+		goto free_link;
+
+	/* do some tests */
+	while ((len = read(iter_fd, buf, sizeof(buf))) > 0)
+		;
+	if (CHECK(len < 0, "read", "read failed: %s\n", strerror(errno)))
+		goto close_iter;
+
+	/* test results */
+	if (CHECK(skel->bss->key_sum_a != expected_key_a,
+		  "key_sum_a", "got %u expected %u\n",
+		  skel->bss->key_sum_a, expected_key_a))
+		goto close_iter;
+	if (CHECK(skel->bss->key_sum_b != expected_key_b,
+		  "key_sum_b", "got %u expected %u\n",
+		  skel->bss->key_sum_b, expected_key_b))
+		goto close_iter;
+	if (CHECK(skel->bss->val_sum != expected_val,
+		  "val_sum", "got %llu expected %llu\n",
+		  skel->bss->val_sum, expected_val))
+		goto close_iter;
+
+close_iter:
+	close(iter_fd);
+free_link:
+	bpf_link__destroy(link);
+out:
+	bpf_iter_bpf_hash_map__destroy(skel);
+}
+
+static void test_bpf_percpu_hash_map(void)
+{
+	__u32 expected_key_a = 0, expected_key_b = 0, expected_key_c = 0;
+	DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);
+	struct bpf_iter_bpf_percpu_hash_map *skel;
+	int err, i, j, len, map_fd, iter_fd;
+	__u32 expected_val = 0;
+	struct bpf_link *link;
+	struct key_t {
+		int a;
+		int b;
+		int c;
+	} key;
+	char buf[64];
+	void *val;
+
+	val = malloc(8 * bpf_num_possible_cpus());
+
+	skel = bpf_iter_bpf_percpu_hash_map__open();
+	if (CHECK(!skel, "bpf_iter_bpf_percpu_hash_map__open",
+		  "skeleton open failed\n"))
+		return;
+
+	skel->rodata->num_cpus = bpf_num_possible_cpus();
+
+	err = bpf_iter_bpf_percpu_hash_map__load(skel);
+	if (CHECK(!skel, "bpf_iter_bpf_percpu_hash_map__load",
+		  "skeleton load failed\n"))
+		goto out;
+
+	/* update map values here */
+	map_fd = bpf_map__fd(skel->maps.hashmap1);
+	for (i = 0; i < bpf_map__max_entries(skel->maps.hashmap1); i++) {
+		key.a = i + 1;
+		key.b = i + 2;
+		key.c = i + 3;
+		expected_key_a += key.a;
+		expected_key_b += key.b;
+		expected_key_c += key.c;
+
+		for (j = 0; j < bpf_num_possible_cpus(); j++) {
+			*(__u32 *)(val + j * 8) = i + j;
+			expected_val += i + j;
+		}
+
+		err = bpf_map_update_elem(map_fd, &key, val, BPF_ANY);
+		if (CHECK(err, "map_update", "map_update failed\n"))
+			goto out;
+	}
+
+	opts.map_fd = map_fd;
+	link = bpf_program__attach_iter(skel->progs.dump_bpf_percpu_hash_map, &opts);
+	if (CHECK(IS_ERR(link), "attach_iter", "attach_iter failed\n"))
+		goto out;
+
+	iter_fd = bpf_iter_create(bpf_link__fd(link));
+	if (CHECK(iter_fd < 0, "create_iter", "create_iter failed\n"))
+		goto free_link;
+
+	/* do some tests */
+	while ((len = read(iter_fd, buf, sizeof(buf))) > 0)
+		;
+	if (CHECK(len < 0, "read", "read failed: %s\n", strerror(errno)))
+		goto close_iter;
+
+	/* test results */
+	if (CHECK(skel->bss->key_sum_a != expected_key_a,
+		  "key_sum_a", "got %u expected %u\n",
+		  skel->bss->key_sum_a, expected_key_a))
+		goto close_iter;
+	if (CHECK(skel->bss->key_sum_b != expected_key_b,
+		  "key_sum_b", "got %u expected %u\n",
+		  skel->bss->key_sum_b, expected_key_b))
+		goto close_iter;
+	if (CHECK(skel->bss->val_sum != expected_val,
+		  "val_sum", "got %u expected %u\n",
+		  skel->bss->val_sum, expected_val))
+		goto close_iter;
+
+close_iter:
+	close(iter_fd);
+free_link:
+	bpf_link__destroy(link);
+out:
+	bpf_iter_bpf_percpu_hash_map__destroy(skel);
+}
+
 void test_bpf_iter(void)
 {
 	if (test__start_subtest("btf_id_or_null"))
···
 		test_overflow(true, false);
 	if (test__start_subtest("prog-ret-1"))
 		test_overflow(false, true);
+	if (test__start_subtest("bpf_hash_map"))
+		test_bpf_hash_map();
+	if (test__start_subtest("bpf_percpu_hash_map"))
+		test_bpf_percpu_hash_map();
 }

tools/testing/selftests/bpf/progs/bpf_iter_bpf_hash_map.c

···
+// 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_HASH);
+	__uint(max_entries, 3);
+	__type(key, struct key_t);
+	__type(value, __u64);
+} hashmap1 SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(max_entries, 3);
+	__type(key, __u64);
+	__type(value, __u64);
+} hashmap2 SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(max_entries, 3);
+	__type(key, struct key_t);
+	__type(value, __u32);
+} hashmap3 SEC(".maps");
+
+/* will set before prog run */
+bool in_test_mode = 0;
+
+/* will collect results during prog run */
+__u32 key_sum_a = 0, key_sum_b = 0, key_sum_c = 0;
+__u64 val_sum = 0;
+
+SEC("iter/bpf_map_elem")
+int dump_bpf_hash_map(struct bpf_iter__bpf_map_elem *ctx)
+{
+	struct seq_file *seq = ctx->meta->seq;
+	__u32 seq_num = ctx->meta->seq_num;
+	struct bpf_map *map = ctx->map;
+	struct key_t *key = ctx->key;
+	__u64 *val = ctx->value;
+
+	if (in_test_mode) {
+		/* test mode is used by selftests to
+		 * test functionality of bpf_hash_map iter.
+		 *
+		 * the above hashmap1 will have correct size
+		 * and will be accepted, hashmap2 and hashmap3
+		 * should be rejected due to smaller key/value
+		 * size.
+		 */
+		if (key == (void *)0 || val == (void *)0)
+			return 0;
+
+		key_sum_a += key->a;
+		key_sum_b += key->b;
+		key_sum_c += key->c;
+		val_sum += *val;
+		return 0;
+	}
+
+	/* non-test mode, the map is prepared with the
+	 * below bpftool command sequence:
+	 *   bpftool map create /sys/fs/bpf/m1 type hash \
+	 *   	key 12 value 8 entries 3 name map1
+	 *   bpftool map update id 77 key 0 0 0 1 0 0 0 0 0 0 0 1 \
+	 *   	value 0 0 0 1 0 0 0 1
+	 *   bpftool map update id 77 key 0 0 0 1 0 0 0 0 0 0 0 2 \
+	 *   	value 0 0 0 1 0 0 0 2
+	 * The bpftool iter command line:
+	 *   bpftool iter pin ./bpf_iter_bpf_hash_map.o /sys/fs/bpf/p1 \
+	 *   	map id 77
+	 * The below output will be:
+	 *   map dump starts
+	 *   77: (1000000 0 2000000) (200000001000000)
+	 *   77: (1000000 0 1000000) (100000001000000)
+	 *   map dump ends
+	 */
+	if (seq_num == 0)
+		BPF_SEQ_PRINTF(seq, "map dump starts\n");
+
+	if (key == (void *)0 || val == (void *)0) {
+		BPF_SEQ_PRINTF(seq, "map dump ends\n");
+		return 0;
+	}
+
+	BPF_SEQ_PRINTF(seq, "%d: (%x %d %x) (%llx)\n", map->id,
+		       key->a, key->b, key->c, *val);
+
+	return 0;
+}

tools/testing/selftests/bpf/progs/bpf_iter_bpf_percpu_hash_map.c

···
+// 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;
+}