Commit ae4ab4b4 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

btf: expose API to work with raw btf_ext data 



This patch changes struct btf_ext to retain original data in sequential
block of memory, which makes it possible to expose
btf_ext__get_raw_data() interface similar to btf__get_raw_data(), allowing
users of libbpf to get access to raw representation of .BTF.ext section.

Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 02c87446

tools/lib/bpf/btf.c

+54 −48
Original line number Diff line number Diff line
@@ -42,9 +42,8 @@ struct btf { 


struct btf_ext_info {

	/*

	 * info points to a deep copy of the individual info section

	 * (e.g. func_info and line_info) from the .BTF.ext.

	 * It does not include the __u32 rec_size.

	 * info points to the individual info section (e.g. func_info and

	 * line_info) from the .BTF.ext. It does not include the __u32 rec_size.

	 */

	void *info;

	__u32 rec_size;
@@ -52,8 +51,13 @@ struct btf_ext_info { 
};



struct btf_ext {

	union {

		struct btf_ext_header *hdr;

		void *data;

	};

	struct btf_ext_info func_info;

	struct btf_ext_info line_info;

	__u32 data_size;

};



struct btf_ext_info_sec {
@@ -596,7 +600,7 @@ int btf__get_map_kv_tids(const struct btf *btf, const char *map_name, 
	return 0;

}



struct btf_ext_sec_copy_param {

struct btf_ext_sec_setup_param {

	__u32 off;

	__u32 len;

	__u32 min_rec_size;
@@ -604,20 +608,14 @@ struct btf_ext_sec_copy_param { 
	const char *desc;

};



static int btf_ext_copy_info(struct btf_ext *btf_ext,

			     __u8 *data, __u32 data_size,

			     struct btf_ext_sec_copy_param *ext_sec)

static int btf_ext_setup_info(struct btf_ext *btf_ext,

			      struct btf_ext_sec_setup_param *ext_sec)

{

	const struct btf_ext_header *hdr = (struct btf_ext_header *)data;

	const struct btf_ext_info_sec *sinfo;

	struct btf_ext_info *ext_info;

	__u32 info_left, record_size;

	/* The start of the info sec (including the __u32 record_size). */

	const void *info;



	/* data and data_size do not include btf_ext_header from now on */

	data = data + hdr->hdr_len;

	data_size -= hdr->hdr_len;

	void *info;



	if (ext_sec->off & 0x03) {

		pr_debug(".BTF.ext %s section is not aligned to 4 bytes\n",
@@ -625,16 +623,15 @@ static int btf_ext_copy_info(struct btf_ext *btf_ext, 
		return -EINVAL;

	}



	if (data_size < ext_sec->off ||

	    ext_sec->len > data_size - ext_sec->off) {

	info = btf_ext->data + btf_ext->hdr->hdr_len + ext_sec->off;

	info_left = ext_sec->len;



	if (btf_ext->data + btf_ext->data_size < info + ext_sec->len) {

		pr_debug("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",

			 ext_sec->desc, ext_sec->off, ext_sec->len);

		return -EINVAL;

	}



	info = data + ext_sec->off;

	info_left = ext_sec->len;



	/* At least a record size */

	if (info_left < sizeof(__u32)) {

		pr_debug(".BTF.ext %s record size not found\n", ext_sec->desc);
@@ -692,42 +689,35 @@ static int btf_ext_copy_info(struct btf_ext *btf_ext, 
	ext_info = ext_sec->ext_info;

	ext_info->len = ext_sec->len - sizeof(__u32);

	ext_info->rec_size = record_size;

	ext_info->info = malloc(ext_info->len);

	if (!ext_info->info)

		return -ENOMEM;

	memcpy(ext_info->info, info + sizeof(__u32), ext_info->len);

	ext_info->info = info + sizeof(__u32);



	return 0;

}



static int btf_ext_copy_func_info(struct btf_ext *btf_ext,

				  __u8 *data, __u32 data_size)

static int btf_ext_setup_func_info(struct btf_ext *btf_ext)

{

	const struct btf_ext_header *hdr = (struct btf_ext_header *)data;

	struct btf_ext_sec_copy_param param = {

		.off = hdr->func_info_off,

		.len = hdr->func_info_len,

	struct btf_ext_sec_setup_param param = {

		.off = btf_ext->hdr->func_info_off,

		.len = btf_ext->hdr->func_info_len,

		.min_rec_size = sizeof(struct bpf_func_info_min),

		.ext_info = &btf_ext->func_info,

		.desc = "func_info"

	};



	return btf_ext_copy_info(btf_ext, data, data_size, &param);

	return btf_ext_setup_info(btf_ext, &param);

}



static int btf_ext_copy_line_info(struct btf_ext *btf_ext,

				  __u8 *data, __u32 data_size)

static int btf_ext_setup_line_info(struct btf_ext *btf_ext)

{

	const struct btf_ext_header *hdr = (struct btf_ext_header *)data;

	struct btf_ext_sec_copy_param param = {

		.off = hdr->line_info_off,

		.len = hdr->line_info_len,

	struct btf_ext_sec_setup_param param = {

		.off = btf_ext->hdr->line_info_off,

		.len = btf_ext->hdr->line_info_len,

		.min_rec_size = sizeof(struct bpf_line_info_min),

		.ext_info = &btf_ext->line_info,

		.desc = "line_info",

	};



	return btf_ext_copy_info(btf_ext, data, data_size, &param);

	return btf_ext_setup_info(btf_ext, &param);

}



static int btf_ext_parse_hdr(__u8 *data, __u32 data_size)
@@ -767,9 +757,7 @@ void btf_ext__free(struct btf_ext *btf_ext) 
{

	if (!btf_ext)

		return;



	free(btf_ext->func_info.info);

	free(btf_ext->line_info.info);

	free(btf_ext->data);

	free(btf_ext);

}
@@ -786,13 +774,23 @@ struct btf_ext *btf_ext__new(__u8 *data, __u32 size) 
	if (!btf_ext)

		return ERR_PTR(-ENOMEM);



	err = btf_ext_copy_func_info(btf_ext, data, size);

	if (err) {

		btf_ext__free(btf_ext);

		return ERR_PTR(err);

	btf_ext->data_size = size;

	btf_ext->data = malloc(size);

	if (!btf_ext->data) {

		err = -ENOMEM;

		goto done;

	}

	memcpy(btf_ext->data, data, size);



	err = btf_ext_setup_func_info(btf_ext);

	if (err)

		goto done;



	err = btf_ext_copy_line_info(btf_ext, data, size);

	err = btf_ext_setup_line_info(btf_ext);

	if (err)

		goto done;



done:

	if (err) {

		btf_ext__free(btf_ext);

		return ERR_PTR(err);
@@ -801,6 +799,12 @@ struct btf_ext *btf_ext__new(__u8 *data, __u32 size) 
	return btf_ext;

}



const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size)

{

	*size = btf_ext->data_size;

	return btf_ext->data;

}



static int btf_ext_reloc_info(const struct btf *btf,

			      const struct btf_ext_info *ext_info,

			      const char *sec_name, __u32 insns_cnt,
@@ -849,7 +853,8 @@ static int btf_ext_reloc_info(const struct btf *btf, 
	return -ENOENT;

}



int btf_ext__reloc_func_info(const struct btf *btf, const struct btf_ext *btf_ext,

int btf_ext__reloc_func_info(const struct btf *btf,

			     const struct btf_ext *btf_ext,

			     const char *sec_name, __u32 insns_cnt,

			     void **func_info, __u32 *cnt)

{
@@ -857,7 +862,8 @@ int btf_ext__reloc_func_info(const struct btf *btf, const struct btf_ext *btf_ex 
				  insns_cnt, func_info, cnt);

}



int btf_ext__reloc_line_info(const struct btf *btf, const struct btf_ext *btf_ext,

int btf_ext__reloc_line_info(const struct btf *btf,

			     const struct btf_ext *btf_ext,

			     const char *sec_name, __u32 insns_cnt,

			     void **line_info, __u32 *cnt)

{

tools/lib/bpf/btf.h

+2 −0
Original line number Diff line number Diff line
@@ -78,6 +78,8 @@ LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name, 


LIBBPF_API struct btf_ext *btf_ext__new(__u8 *data, __u32 size);

LIBBPF_API void btf_ext__free(struct btf_ext *btf_ext);

LIBBPF_API const void *btf_ext__get_raw_data(const struct btf_ext* btf_ext,

					     __u32 *size);

LIBBPF_API int btf_ext__reloc_func_info(const struct btf *btf,

					const struct btf_ext *btf_ext,

					const char *sec_name, __u32 insns_cnt,

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -141,6 +141,7 @@ LIBBPF_0.0.2 { 
		btf__load;

		btf_ext__free;

		btf_ext__func_info_rec_size;

		btf_ext__get_raw_data;

		btf_ext__line_info_rec_size;

		btf_ext__new;

		btf_ext__reloc_func_info;

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