linux_kernel/tools/testing/selftests/bpf/test_pkt_md_access.c

/* Copyright (c) 2017 Facebook
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 */
#include <stddef.h>
#include <string.h>
#include <linux/bpf.h>
#include <linux/pkt_cls.h>
#include "bpf_helpers.h"

int _version SEC("version") = 1;

#define TEST_FIELD(TYPE, FIELD, MASK)					\
	{								\
		TYPE tmp = *(volatile TYPE *)&skb->FIELD;		\
		if (tmp != ((*(volatile __u32 *)&skb->FIELD) & MASK))	\
			return TC_ACT_SHOT;				\
	}

SEC("test1")
int process(struct __sk_buff *skb)
{
	TEST_FIELD(__u8,  len, 0xFF);
	TEST_FIELD(__u16, len, 0xFFFF);
	TEST_FIELD(__u32, len, 0xFFFFFFFF);
	TEST_FIELD(__u16, protocol, 0xFFFF);
	TEST_FIELD(__u32, protocol, 0xFFFFFFFF);
	TEST_FIELD(__u8,  hash, 0xFF);
	TEST_FIELD(__u16, hash, 0xFFFF);
	TEST_FIELD(__u32, hash, 0xFFFFFFFF);

	return TC_ACT_OK;
}