selftests/bpf: Add selftests validating the user ringbuf

cgroup_hierarchical_stats                # JIT does not support calling kernel function                                (kfunc)

htab_update                              # failed to attach: ERROR: strerror_r(-524)=22                                (trampoline)

tracing_struct                           # failed to auto-attach: -524                                                 (trampoline)

user_ringbuf                             # failed to find kernel BTF type ID of '__s390x_sys_prctl': -3                (?)

/* SPDX-License-Identifier: GPL-2.0 */

/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */

#ifndef _TEST_USER_RINGBUF_H

#define _TEST_USER_RINGBUF_H

#define TEST_OP_64 4

#define TEST_OP_32 2

enum test_msg_op {

	TEST_MSG_OP_INC64,

	TEST_MSG_OP_INC32,

	TEST_MSG_OP_MUL64,

	TEST_MSG_OP_MUL32,

	// Must come last.

	TEST_MSG_OP_NUM_OPS,

};

struct test_msg {

	enum test_msg_op msg_op;

	union {

		__s64 operand_64;

		__s32 operand_32;

	};

};

struct sample {

	int pid;

	int seq;

	long value;

	char comm[16];

};

#endif /* _TEST_USER_RINGBUF_H */