tools/testing/selftests/bpf/prog_tests/mmap.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/bpf/prog_tests/mmap.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/bpf/prog_tests/mmap.c
Extension
.c
Size
9357 bytes
Lines
305
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

struct map_data {
	__u64 val[512 * 4];
};

static size_t roundup_page(size_t sz)
{
	long page_size = sysconf(_SC_PAGE_SIZE);
	return (sz + page_size - 1) / page_size * page_size;
}

void test_mmap(void)
{
	const size_t bss_sz = roundup_page(sizeof(struct test_mmap__bss));
	const size_t map_sz = roundup_page(sizeof(struct map_data));
	const int zero = 0, one = 1, two = 2, far = 1500;
	const long page_size = sysconf(_SC_PAGE_SIZE);
	int err, duration = 0, i, data_map_fd, data_map_id, tmp_fd, rdmap_fd;
	struct bpf_map *data_map, *bss_map;
	void *bss_mmaped = NULL, *map_mmaped = NULL, *tmp0, *tmp1, *tmp2;
	struct test_mmap__bss *bss_data;
	struct bpf_map_info map_info;
	__u32 map_info_sz = sizeof(map_info);
	struct map_data *map_data;
	struct test_mmap *skel;
	__u64 val = 0;

	skel = test_mmap__open();
	if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
		return;

	err = bpf_map__set_max_entries(skel->maps.rdonly_map, page_size);
	if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
		goto cleanup;

	/* at least 4 pages of data */
	err = bpf_map__set_max_entries(skel->maps.data_map,
				       4 * (page_size / sizeof(u64)));
	if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
		goto cleanup;

	err = test_mmap__load(skel);
	if (CHECK(err != 0, "skel_load", "skeleton load failed\n"))
		goto cleanup;

	bss_map = skel->maps.bss;
	data_map = skel->maps.data_map;
	data_map_fd = bpf_map__fd(data_map);

	rdmap_fd = bpf_map__fd(skel->maps.rdonly_map);
	tmp1 = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, rdmap_fd, 0);
	if (CHECK(tmp1 != MAP_FAILED, "rdonly_write_mmap", "unexpected success\n")) {
		munmap(tmp1, page_size);
		goto cleanup;
	}
	/* now double-check if it's mmap()'able at all */
	tmp1 = mmap(NULL, page_size, PROT_READ, MAP_SHARED, rdmap_fd, 0);
	if (CHECK(tmp1 == MAP_FAILED, "rdonly_read_mmap", "failed: %d\n", errno))
		goto cleanup;

	/* get map's ID */
	memset(&map_info, 0, map_info_sz);
	err = bpf_map_get_info_by_fd(data_map_fd, &map_info, &map_info_sz);
	if (CHECK(err, "map_get_info", "failed %d\n", errno))
		goto cleanup;
	data_map_id = map_info.id;

	/* mmap BSS map */
	bss_mmaped = mmap(NULL, bss_sz, PROT_READ | PROT_WRITE, MAP_SHARED,
			  bpf_map__fd(bss_map), 0);
	if (CHECK(bss_mmaped == MAP_FAILED, "bss_mmap",
		  ".bss mmap failed: %d\n", errno)) {
		bss_mmaped = NULL;
		goto cleanup;
	}
	/* map as R/W first */
	map_mmaped = mmap(NULL, map_sz, PROT_READ | PROT_WRITE, MAP_SHARED,
			  data_map_fd, 0);
	if (CHECK(map_mmaped == MAP_FAILED, "data_mmap",
		  "data_map mmap failed: %d\n", errno)) {
		map_mmaped = NULL;
		goto cleanup;
	}

	bss_data = bss_mmaped;
	map_data = map_mmaped;

	CHECK_FAIL(bss_data->in_val);
	CHECK_FAIL(bss_data->out_val);
	CHECK_FAIL(skel->bss->in_val);
	CHECK_FAIL(skel->bss->out_val);

Annotation

Implementation Notes