linux-stable/tools/testing/selftests/bpf/progs/recursion.c
Alexei Starovoitov 406c557edc selftest/bpf: Add a recursion test
Add recursive non-sleepable fentry program as a test.
All attach points where sleepable progs can execute are non recursive so far.
The recursion protection mechanism for sleepable cannot be activated yet.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210210033634.62081-6-alexei.starovoitov@gmail.com
2021-02-11 16:19:16 +01:00

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C

// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2021 Facebook */
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
char _license[] SEC("license") = "GPL";
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 1);
__type(key, int);
__type(value, long);
} hash1 SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 1);
__type(key, int);
__type(value, long);
} hash2 SEC(".maps");
int pass1 = 0;
int pass2 = 0;
SEC("fentry/__htab_map_lookup_elem")
int BPF_PROG(on_lookup, struct bpf_map *map)
{
int key = 0;
if (map == (void *)&hash1) {
pass1++;
return 0;
}
if (map == (void *)&hash2) {
pass2++;
/* htab_map_gen_lookup() will inline below call
* into direct call to __htab_map_lookup_elem()
*/
bpf_map_lookup_elem(&hash2, &key);
return 0;
}
return 0;
}