1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2020 Facebook */
3 #include "bpf_iter.h"
4 #include <bpf/bpf_helpers.h>
5 
6 char _license[] SEC("license") = "GPL";
7 
8 struct key_t {
9 	int a;
10 	int b;
11 	int c;
12 };
13 
14 struct {
15 	__uint(type, BPF_MAP_TYPE_HASH);
16 	__uint(max_entries, 3);
17 	__type(key, struct key_t);
18 	__type(value, __u64);
19 } hashmap1 SEC(".maps");
20 
21 struct {
22 	__uint(type, BPF_MAP_TYPE_HASH);
23 	__uint(max_entries, 3);
24 	__type(key, __u64);
25 	__type(value, __u64);
26 } hashmap2 SEC(".maps");
27 
28 struct {
29 	__uint(type, BPF_MAP_TYPE_HASH);
30 	__uint(max_entries, 3);
31 	__type(key, struct key_t);
32 	__type(value, __u32);
33 } hashmap3 SEC(".maps");
34 
35 /* will set before prog run */
36 bool in_test_mode = 0;
37 
38 /* will collect results during prog run */
39 __u32 key_sum_a = 0, key_sum_b = 0, key_sum_c = 0;
40 __u64 val_sum = 0;
41 
42 SEC("iter/bpf_map_elem")
dump_bpf_hash_map(struct bpf_iter__bpf_map_elem * ctx)43 int dump_bpf_hash_map(struct bpf_iter__bpf_map_elem *ctx)
44 {
45 	struct seq_file *seq = ctx->meta->seq;
46 	__u32 seq_num = ctx->meta->seq_num;
47 	struct bpf_map *map = ctx->map;
48 	struct key_t *key = ctx->key;
49 	struct key_t tmp_key;
50 	__u64 *val = ctx->value;
51 	__u64 tmp_val = 0;
52 	int ret;
53 
54 	if (in_test_mode) {
55 		/* test mode is used by selftests to
56 		 * test functionality of bpf_hash_map iter.
57 		 *
58 		 * the above hashmap1 will have correct size
59 		 * and will be accepted, hashmap2 and hashmap3
60 		 * should be rejected due to smaller key/value
61 		 * size.
62 		 */
63 		if (key == (void *)0 || val == (void *)0)
64 			return 0;
65 
66 		/* update the value and then delete the <key, value> pair.
67 		 * it should not impact the existing 'val' which is still
68 		 * accessible under rcu.
69 		 */
70 		__builtin_memcpy(&tmp_key, key, sizeof(struct key_t));
71 		ret = bpf_map_update_elem(&hashmap1, &tmp_key, &tmp_val, 0);
72 		if (ret)
73 			return 0;
74 		ret = bpf_map_delete_elem(&hashmap1, &tmp_key);
75 		if (ret)
76 			return 0;
77 
78 		key_sum_a += key->a;
79 		key_sum_b += key->b;
80 		key_sum_c += key->c;
81 		val_sum += *val;
82 		return 0;
83 	}
84 
85 	/* non-test mode, the map is prepared with the
86 	 * below bpftool command sequence:
87 	 *   bpftool map create /sys/fs/bpf/m1 type hash \
88 	 *   	key 12 value 8 entries 3 name map1
89 	 *   bpftool map update id 77 key 0 0 0 1 0 0 0 0 0 0 0 1 \
90 	 *   	value 0 0 0 1 0 0 0 1
91 	 *   bpftool map update id 77 key 0 0 0 1 0 0 0 0 0 0 0 2 \
92 	 *   	value 0 0 0 1 0 0 0 2
93 	 * The bpftool iter command line:
94 	 *   bpftool iter pin ./bpf_iter_bpf_hash_map.o /sys/fs/bpf/p1 \
95 	 *   	map id 77
96 	 * The below output will be:
97 	 *   map dump starts
98 	 *   77: (1000000 0 2000000) (200000001000000)
99 	 *   77: (1000000 0 1000000) (100000001000000)
100 	 *   map dump ends
101 	 */
102 	if (seq_num == 0)
103 		BPF_SEQ_PRINTF(seq, "map dump starts\n");
104 
105 	if (key == (void *)0 || val == (void *)0) {
106 		BPF_SEQ_PRINTF(seq, "map dump ends\n");
107 		return 0;
108 	}
109 
110 	BPF_SEQ_PRINTF(seq, "%d: (%x %d %x) (%llx)\n", map->id,
111 		       key->a, key->b, key->c, *val);
112 
113 	return 0;
114 }
115