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

   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
   7 char _license[] SEC("license") = "GPL";
   8
   9 struct key_t {
  10         int a;
  11         int b;
  12         int c;
  13 };
  14
  15 struct {
  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
  22 struct {
  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
  29 struct {
  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 */
  37 bool 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
  43 SEC("iter/bpf_map_elem")
  44 int 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 }