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>

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;
	struct key_t tmp_key;
	__u64 *val = ctx->value;
	__u64 tmp_val = 0;
	int ret;

	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;

		/* update the value and then delete the <key, value> pair.
		 * it should not impact the existing 'val' which is still
		 * accessible under rcu.
		 */
		__builtin_memcpy(&tmp_key, key, sizeof(struct key_t));
		ret = bpf_map_update_elem(&hashmap1, &tmp_key, &tmp_val, 0);
		if (ret)
			return 0;
		ret = bpf_map_delete_elem(&hashmap1, &tmp_key);
		if (ret)
			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;
}