Commit 58650cc4 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

bpftool: use libbpf's btf__parse_elf API 



Use btf__parse_elf() API, provided by libbpf, instead of implementing
ELF parsing by itself.

Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent e6c64855

tools/bpf/bpftool/btf.c

+8 −109
Original line number Diff line number Diff line
@@ -8,8 +8,8 @@ 
#include <stdio.h>

#include <string.h>

#include <unistd.h>

#include <gelf.h>

#include <bpf.h>

#include <libbpf.h>

#include <linux/btf.h>



#include "btf.h"
@@ -340,112 +340,6 @@ static int dump_btf_raw(const struct btf *btf, 
	return 0;

}



static bool check_btf_endianness(GElf_Ehdr *ehdr)

{

	static unsigned int const endian = 1;



	switch (ehdr->e_ident[EI_DATA]) {

	case ELFDATA2LSB:

		return *(unsigned char const *)&endian == 1;

	case ELFDATA2MSB:

		return *(unsigned char const *)&endian == 0;

	default:

		return 0;

	}

}



static int btf_load_from_elf(const char *path, struct btf **btf)

{

	int err = -1, fd = -1, idx = 0;

	Elf_Data *btf_data = NULL;

	Elf_Scn *scn = NULL;

	Elf *elf = NULL;

	GElf_Ehdr ehdr;



	if (elf_version(EV_CURRENT) == EV_NONE) {

		p_err("failed to init libelf for %s", path);

		return -1;

	}



	fd = open(path, O_RDONLY);

	if (fd < 0) {

		p_err("failed to open %s: %s", path, strerror(errno));

		return -1;

	}



	elf = elf_begin(fd, ELF_C_READ, NULL);

	if (!elf) {

		p_err("failed to open %s as ELF file", path);

		goto done;

	}

	if (!gelf_getehdr(elf, &ehdr)) {

		p_err("failed to get EHDR from %s", path);

		goto done;

	}

	if (!check_btf_endianness(&ehdr)) {

		p_err("non-native ELF endianness is not supported");

		goto done;

	}

	if (!elf_rawdata(elf_getscn(elf, ehdr.e_shstrndx), NULL)) {

		p_err("failed to get e_shstrndx from %s\n", path);

		goto done;

	}



	while ((scn = elf_nextscn(elf, scn)) != NULL) {

		GElf_Shdr sh;

		char *name;



		idx++;

		if (gelf_getshdr(scn, &sh) != &sh) {

			p_err("failed to get section(%d) header from %s",

			      idx, path);

			goto done;

		}

		name = elf_strptr(elf, ehdr.e_shstrndx, sh.sh_name);

		if (!name) {

			p_err("failed to get section(%d) name from %s",

			      idx, path);

			goto done;

		}

		if (strcmp(name, BTF_ELF_SEC) == 0) {

			btf_data = elf_getdata(scn, 0);

			if (!btf_data) {

				p_err("failed to get section(%d, %s) data from %s",

				      idx, name, path);

				goto done;

			}

			break;

		}

	}



	if (!btf_data) {

		p_err("%s ELF section not found in %s", BTF_ELF_SEC, path);

		goto done;

	}



	*btf = btf__new(btf_data->d_buf, btf_data->d_size);

	if (IS_ERR(*btf)) {

		err = PTR_ERR(*btf);

		*btf = NULL;

		p_err("failed to load BTF data from %s: %s",

		      path, strerror(err));

		goto done;

	}



	err = 0;

done:

	if (err) {

		if (*btf) {

			btf__free(*btf);

			*btf = NULL;

		}

	}

	if (elf)

		elf_end(elf);

	close(fd);

	return err;

}



static int do_dump(int argc, char **argv)

{

	struct btf *btf = NULL;
@@ -522,9 +416,14 @@ static int do_dump(int argc, char **argv) 
		}

		NEXT_ARG();

	} else if (is_prefix(src, "file")) {

		err = btf_load_from_elf(*argv, &btf);

		if (err)

		btf = btf__parse_elf(*argv, NULL);

		if (IS_ERR(btf)) {

			err = PTR_ERR(btf);

			btf = NULL;

			p_err("failed to load BTF from %s: %s", 

			      *argv, strerror(err));

			goto done;

		}

		NEXT_ARG();

	} else {

		err = -1;