Commit 25b6d5de authored by Andrii Nakryiko's avatar Andrii Nakryiko
Browse files

Merge branch 'libbpf-support-multi-split-btf' 

Alan Maguire says:

====================
libbpf: support multi-split BTF

In discussing handling of inlines in BTF [1], one area which we may need
support for in the future is multiple split BTF, where split BTF sits
atop another split BTF which sits atop base BTF.  This two-patch series
fixes one issue discovered when testing multi-split BTF and extends the
split BTF test to cover multi-split BTF also.

[1] https://lore.kernel.org/dwarves/20250416-btf_inline-v1-0-e4bd2f8adae5@meta.com/
====================

Link: https://patch.msgid.link/20250519165935.261614-1-alan.maguire@oracle.com


Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
parents b615ce5f 02f5e7c1

tools/lib/bpf/btf.c

+1 −1
Original line number Diff line number Diff line
@@ -996,7 +996,7 @@ static struct btf *btf_new_empty(struct btf *base_btf) 
	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;

		btf->swapped_endian = base_btf->swapped_endian;

	}

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

+52 −6
Original line number Diff line number Diff line
@@ -12,10 +12,11 @@ static void btf_dump_printf(void *ctx, const char *fmt, va_list args) 
	vfprintf(ctx, fmt, args);

}



void test_btf_split() {

static void __test_btf_split(bool multi)

{

	struct btf_dump *d = NULL;

	const struct btf_type *t;

	struct btf *btf1, *btf2;

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

	int str_off, i, err;



	btf1 = btf__new_empty();
@@ -63,14 +64,46 @@ void test_btf_split() { 
	ASSERT_EQ(btf_vlen(t), 3, "split_struct_vlen");

	ASSERT_STREQ(btf__str_by_offset(btf2, t->name_off), "s2", "split_struct_name");



	if (multi) {

		btf3 = btf__new_empty_split(btf2);

		if (!ASSERT_OK_PTR(btf3, "multi_split_btf"))

			goto cleanup;

	} else {

		btf3 = btf2;

	}



	btf__add_union(btf3, "u1", 16);			/* [5] union u1 {	*/

	btf__add_field(btf3, "f1", 4, 0, 0);		/*	struct s2 f1;	*/

	btf__add_field(btf3, "uf2", 1, 0, 0);		/*	int f2;		*/

							/* } */



	if (multi) {

		t = btf__type_by_id(btf2, 5);

		ASSERT_NULL(t, "multisplit_type_in_first_split");

	}



	t = btf__type_by_id(btf3, 5);

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

		goto cleanup;

	ASSERT_EQ(btf_is_union(t), true, "split_union_kind");

	ASSERT_EQ(btf_vlen(t), 2, "split_union_vlen");

	ASSERT_STREQ(btf__str_by_offset(btf3, t->name_off), "u1", "split_union_name");

	ASSERT_EQ(btf__type_cnt(btf3), 6, "split_type_cnt");



	t = btf__type_by_id(btf3, 1);

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

		goto cleanup;

	ASSERT_EQ(btf_is_int(t), true, "split_base_int");

	ASSERT_STREQ(btf__str_by_offset(btf3, t->name_off), "int", "split_base_type_name");



	/* BTF-to-C dump of split BTF */

	dump_buf_file = open_memstream(&dump_buf, &dump_buf_sz);

	if (!ASSERT_OK_PTR(dump_buf_file, "dump_memstream"))

		return;

	d = btf_dump__new(btf2, btf_dump_printf, dump_buf_file, NULL);

	d = btf_dump__new(btf3, btf_dump_printf, dump_buf_file, NULL);

	if (!ASSERT_OK_PTR(d, "btf_dump__new"))

		goto cleanup;

	for (i = 1; i < btf__type_cnt(btf2); i++) {

	for (i = 1; i < btf__type_cnt(btf3); i++) {

		err = btf_dump__dump_type(d, i);

		ASSERT_OK(err, "dump_type_ok");

	}
@@ -79,12 +112,15 @@ void test_btf_split() { 
	ASSERT_STREQ(dump_buf,

"struct s1 {\n"

"	int f1;\n"

"};\n"

"\n"

"};\n\n"

"struct s2 {\n"

"	struct s1 f1;\n"

"	int f2;\n"

"	int *f3;\n"

"};\n\n"

"union u1 {\n"

"	struct s2 f1;\n"

"	int uf2;\n"

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



cleanup:
@@ -94,4 +130,14 @@ void test_btf_split() { 
	btf_dump__free(d);

	btf__free(btf1);

	btf__free(btf2);

	if (btf2 != btf3)

		btf__free(btf3);

}



void test_btf_split(void)

{

	if (test__start_subtest("single_split"))

		__test_btf_split(false);

	if (test__start_subtest("multi_split"))

		__test_btf_split(true);

}