selftests: Add test for overriding global data value before load

// SPDX-License-Identifier: GPL-2.0

#include <test_progs.h>

void test_global_data_init(void)

{

	const char *file = "./test_global_data.o";

	int err = -ENOMEM, map_fd, zero = 0;

	__u8 *buff = NULL, *newval = NULL;

	struct bpf_object *obj;

	struct bpf_map *map;

        __u32 duration = 0;

	size_t sz;

	obj = bpf_object__open_file(file, NULL);

	if (CHECK_FAIL(!obj))

		return;

	map = bpf_object__find_map_by_name(obj, "test_glo.rodata");

	if (CHECK_FAIL(!map || !bpf_map__is_internal(map)))

		goto out;

	sz = bpf_map__def(map)->value_size;

	newval = malloc(sz);

	if (CHECK_FAIL(!newval))

		goto out;

	memset(newval, 0, sz);

	/* wrong size, should fail */

	err = bpf_map__set_initial_value(map, newval, sz - 1);

	if (CHECK(!err, "reject set initial value wrong size", "err %d\n", err))

		goto out;

	err = bpf_map__set_initial_value(map, newval, sz);

	if (CHECK(err, "set initial value", "err %d\n", err))

		goto out;

	err = bpf_object__load(obj);

	if (CHECK_FAIL(err))

		goto out;

	map_fd = bpf_map__fd(map);

	if (CHECK_FAIL(map_fd < 0))

		goto out;

	buff = malloc(sz);

	if (buff)

		err = bpf_map_lookup_elem(map_fd, &zero, buff);

	if (CHECK(!buff || err || memcmp(buff, newval, sz),

		  "compare .rodata map data override",

		  "err %d errno %d\n", err, errno))

		goto out;

	memset(newval, 1, sz);

	/* object loaded - should fail */

	err = bpf_map__set_initial_value(map, newval, sz);

	CHECK(!err, "reject set initial value after load", "err %d\n", err);

out:

	free(buff);

	free(newval);

	bpf_object__close(obj);

}

		bpf_map_update_elem(&result_##map, &key, var, 0);	\

	} while (0)

SEC("static_data_load")

SEC("classifier/static_data_load")

int load_static_data(struct __sk_buff *skb)

{

	static const __u64 bar = ~0;