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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: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko 2019-05-24 11:58:58 -07:00 committed by Alexei Starovoitov
parent e6c64855fd
commit 58650cc473
1 changed files with 8 additions and 109 deletions
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117
tools/bpf/bpftool/btf.c
View File

@ -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;