Commit 4cb4897b authored by Andrii Nakryiko's avatar Andrii Nakryiko
Browse files

Merge branch 'multi-split-btf-fixes-and-test' 

Alan Maguire says:

====================
Multi-split BTF fixes and test

This small series consists of a fix to multi-split BTF parsing
(patch 1) and a test which exercises (multi-)split BTF parsing
(patch 2).

Changes since v3 [1]
- add asserts to ensure number of types in original and parsed
  BTF are identical, and the calls to btf__type_by_id() return
  valid pointers (code review bot, patch 2)

Changes since v2 [2]

- fix Fixes: tag formatting (Andrii, patch 1)
- BPF code-review bot saw we were doing ASSERT_OK_PTR() on wrong
  BTF (not multisplit) in patch 2
- ensure cleanup is correctly handled for BTF, unlink in split
  tests (Andrii, patch 2)

Changes since v1 [3]

- BPF code-review bot spotted another place that the string offset
needed to be adjusted based upon base start string offset + header
string offset.
- added selftests to extend split BTF testing to parsing

[1] https://lore.kernel.org/bpf/20251028225544.1312356-1-alan.maguire@oracle.com/
[2] https://lore.kernel.org/bpf/20251028155709.1265445-1-alan.maguire@oracle.com/
[3] https://lore.kernel.org/bpf/20251023142812.258870-1-alan.maguire@oracle.com/
====================

Link: https://patch.msgid.link/20251104203309.318429-1-alan.maguire@oracle.com


Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
parents b3387b31 cc77a203

tools/lib/bpf/btf.c

+2 −2
Original line number Diff line number Diff line
@@ -1061,7 +1061,7 @@ static struct btf *btf_new(const void *data, __u32 size, struct btf *base_btf, b 
	if (base_btf) {

		btf->base_btf = base_btf;

		btf->start_id = btf__type_cnt(base_btf);

		btf->start_str_off = base_btf->hdr->str_len;

		btf->start_str_off = base_btf->hdr->str_len + base_btf->start_str_off;

	}



	if (is_mmap) {
@@ -5818,7 +5818,7 @@ void btf_set_base_btf(struct btf *btf, const struct btf *base_btf) 
{

	btf->base_btf = (struct btf *)base_btf;

	btf->start_id = btf__type_cnt(base_btf);

	btf->start_str_off = base_btf->hdr->str_len;

	btf->start_str_off = base_btf->hdr->str_len + base_btf->start_str_off;

}



int btf__relocate(struct btf *btf, const struct btf *base_btf)

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

+85 −2
Original line number Diff line number Diff line
@@ -12,11 +12,45 @@ static void btf_dump_printf(void *ctx, const char *fmt, va_list args) 
	vfprintf(ctx, fmt, args);

}



/* Write raw BTF to file, return number of bytes written or negative errno */

static ssize_t btf_raw_write(struct btf *btf, char *file)

{

	ssize_t written = 0;

	const void *data;

	__u32 size = 0;

	int fd, ret;



	fd = mkstemp(file);

	if (!ASSERT_GE(fd, 0, "create_file"))

		return -errno;



	data = btf__raw_data(btf, &size);

	if (!ASSERT_OK_PTR(data, "btf__raw_data")) {

		close(fd);

		return -EINVAL;

	}

	while (written < size) {

		ret = write(fd, data + written, size - written);

		if (!ASSERT_GE(ret, 0, "write succeeded")) {

			close(fd);

			return -errno;

		}

		written += ret;

	}

	close(fd);

	return written;

}



static void __test_btf_split(bool multi)

{

	char multisplit_btf_file[] = "/tmp/test_btf_multisplit.XXXXXX";

	char split_btf_file[] = "/tmp/test_btf_split.XXXXXX";

	char base_btf_file[] = "/tmp/test_btf_base.XXXXXX";

	ssize_t multisplit_btf_sz = 0, split_btf_sz = 0, base_btf_sz = 0;

	struct btf_dump *d = NULL;

	const struct btf_type *t;

	struct btf *btf1, *btf2, *btf3 = NULL;

	const struct btf_type *t, *ot;

	struct btf *btf1 = NULL, *btf2 = NULL, *btf3 = NULL;

	struct btf *btf4 = NULL, *btf5 = NULL, *btf6 = NULL;

	int str_off, i, err;



	btf1 = btf__new_empty();
@@ -123,6 +157,45 @@ static void __test_btf_split(bool multi) 
"	int uf2;\n"

"};\n\n", "c_dump");



	/* write base, split BTFs to files and ensure parsing succeeds */

	base_btf_sz = btf_raw_write(btf1, base_btf_file);

	if (base_btf_sz < 0)

		goto cleanup;

	split_btf_sz = btf_raw_write(btf2, split_btf_file);

	if (split_btf_sz < 0)

		goto cleanup;

	btf4 = btf__parse(base_btf_file, NULL);

	if (!ASSERT_OK_PTR(btf4, "parse_base"))

		goto cleanup;

	btf5 = btf__parse_split(split_btf_file, btf4);

	if (!ASSERT_OK_PTR(btf5, "parse_split"))

		goto cleanup;

	if (multi) {

		multisplit_btf_sz = btf_raw_write(btf3, multisplit_btf_file);

		if (multisplit_btf_sz < 0)

			goto cleanup;

		btf6 = btf__parse_split(multisplit_btf_file, btf5);

		if (!ASSERT_OK_PTR(btf6, "parse_multisplit"))

			goto cleanup;

	} else {

		btf6 = btf5;

	}



	if (!ASSERT_EQ(btf__type_cnt(btf3), btf__type_cnt(btf6), "cmp_type_cnt"))

		goto cleanup;



	/* compare parsed to original BTF */

	for (i = 1; i < btf__type_cnt(btf6); i++) {

		t = btf__type_by_id(btf6, i);

		if (!ASSERT_OK_PTR(t, "type_in_parsed_btf"))

			goto cleanup;

		ot = btf__type_by_id(btf3, i);

		if (!ASSERT_OK_PTR(ot, "type_in_orig_btf"))

			goto cleanup;

		if (!ASSERT_EQ(memcmp(t, ot, sizeof(*ot)), 0, "cmp_parsed_orig_btf"))

			goto cleanup;

	}



cleanup:

	if (dump_buf_file)

		fclose(dump_buf_file);
@@ -132,6 +205,16 @@ static void __test_btf_split(bool multi) 
	btf__free(btf2);

	if (btf2 != btf3)

		btf__free(btf3);

	btf__free(btf4);

	btf__free(btf5);

	if (btf5 != btf6)

		btf__free(btf6);

	if (base_btf_sz > 0)

		unlink(base_btf_file);

	if (split_btf_sz > 0)

		unlink(split_btf_file);

	if (multisplit_btf_sz > 0)

		unlink(multisplit_btf_file);

}



void test_btf_split(void)