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