Commit a871b043 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

libbpf: Add btf__new_empty() to create an empty BTF object 



Add an ability to create an empty BTF object from scratch. This is going to be
used by pahole for BTF encoding. And also by selftest for convenient creation
of BTF objects.

Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200926011357.2366158-7-andriin@fb.com
parent 919d2b1d

tools/lib/bpf/btf.c

+30 −0
Original line number Diff line number Diff line
@@ -565,6 +565,36 @@ void btf__free(struct btf *btf) 
	free(btf);

}



struct btf *btf__new_empty(void)

{

	struct btf *btf;



	btf = calloc(1, sizeof(*btf));

	if (!btf)

		return ERR_PTR(-ENOMEM);

	btf->fd = -1;

	btf->ptr_sz = sizeof(void *);



	/* +1 for empty string at offset 0 */

	btf->raw_size = sizeof(struct btf_header) + 1;

	btf->raw_data = calloc(1, btf->raw_size);

	if (!btf->raw_data) {

		free(btf);

		return ERR_PTR(-ENOMEM);

	}



	btf->hdr = btf->raw_data;

	btf->hdr->hdr_len = sizeof(struct btf_header);

	btf->hdr->magic = BTF_MAGIC;

	btf->hdr->version = BTF_VERSION;



	btf->types_data = btf->raw_data + btf->hdr->hdr_len;

	btf->strs_data = btf->raw_data + btf->hdr->hdr_len;

	btf->hdr->str_len = 1; /* empty string at offset 0 */



	return btf;

}



struct btf *btf__new(const void *data, __u32 size)

{

	struct btf *btf;

tools/lib/bpf/btf.h

+1 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ struct bpf_object; 


LIBBPF_API void btf__free(struct btf *btf);

LIBBPF_API struct btf *btf__new(const void *data, __u32 size);

LIBBPF_API struct btf *btf__new_empty(void);

LIBBPF_API struct btf *btf__parse(const char *path, struct btf_ext **btf_ext);

LIBBPF_API struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext);

LIBBPF_API struct btf *btf__parse_raw(const char *path);

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -307,6 +307,7 @@ LIBBPF_0.2.0 { 
		bpf_program__section_name;

		btf__add_str;

		btf__find_str;

		btf__new_empty;

		perf_buffer__buffer_cnt;

		perf_buffer__buffer_fd;

		perf_buffer__epoll_fd;