Commit 230e7d7d authored by Donglin Peng's avatar Donglin Peng Committed by Andrii Nakryiko
Browse files

tools/resolve_btfids: Support BTF sorting feature 



This introduces a new BTF sorting phase that specifically sorts
BTF types by name in ascending order, so that the binary search
can be used to look up types.

Signed-off-by: default avatarDonglin Peng <pengdonglin@xiaomi.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20260109130003.3313716-4-dolinux.peng@gmail.com
parent a3acd7d4

tools/bpf/resolve_btfids/main.c

+64 −0
Original line number Diff line number Diff line
@@ -850,6 +850,67 @@ static int dump_raw_btf(struct btf *btf, const char *out_path) 
	return 0;

}



/*

 * Sort types by name in ascending order resulting in all

 * anonymous types being placed before named types.

 */

static int cmp_type_names(const void *a, const void *b, void *priv)

{

	struct btf *btf = (struct btf *)priv;

	const struct btf_type *ta = btf__type_by_id(btf, *(__u32 *)a);

	const struct btf_type *tb = btf__type_by_id(btf, *(__u32 *)b);

	const char *na, *nb;



	na = btf__str_by_offset(btf, ta->name_off);

	nb = btf__str_by_offset(btf, tb->name_off);

	return strcmp(na, nb);

}



static int sort_btf_by_name(struct btf *btf)

{

	__u32 *permute_ids = NULL, *id_map = NULL;

	int nr_types, i, err = 0;

	__u32 start_id = 0, start_offs = 1, id;



	if (btf__base_btf(btf)) {

		start_id = btf__type_cnt(btf__base_btf(btf));

		start_offs = 0;

	}

	nr_types = btf__type_cnt(btf) - start_id;



	permute_ids = calloc(nr_types, sizeof(*permute_ids));

	if (!permute_ids) {

		err = -ENOMEM;

		goto out;

	}



	id_map = calloc(nr_types, sizeof(*id_map));

	if (!id_map) {

		err = -ENOMEM;

		goto out;

	}



	for (i = 0, id = start_id; i < nr_types; i++, id++)

		permute_ids[i] = id;



	qsort_r(permute_ids + start_offs, nr_types - start_offs,

		sizeof(*permute_ids), cmp_type_names, btf);



	for (i = 0; i < nr_types; i++) {

		id = permute_ids[i] - start_id;

		id_map[id] = i + start_id;

	}



	err = btf__permute(btf, id_map, nr_types, NULL);

	if (err)

		pr_err("FAILED: btf permute: %s\n", strerror(-err));



out:

	free(permute_ids);

	free(id_map);

	return err;

}



static inline int make_out_path(char *buf, u32 buf_sz, const char *in_path, const char *suffix)

{

	int len = snprintf(buf, buf_sz, "%s%s", in_path, suffix);
@@ -1025,6 +1086,9 @@ int main(int argc, const char **argv) 
	if (load_btf(&obj))

		goto out;



	if (sort_btf_by_name(obj.btf))

		goto out;



	if (elf_collect(&obj))

		goto out;