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bpf, libbpf: refactor relocation handling

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Adjust the code for relocations slightly with no functional changes,
so that upcoming patches that will introduce support for relocations
into the .data, .rodata and .bss sections can be added independent
of these changes.

Signed-off-by: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Joe Stringer 2019-04-09 23:20:12 +02:00 committed by Alexei Starovoitov
parent c83fef6bc5
commit f8c7a4d4dc
1 changed files with 31 additions and 29 deletions
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60
tools/lib/bpf/libbpf.c
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@ -871,20 +871,20 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
obj->efile.symbols = data;
obj->efile.strtabidx = sh.sh_link;
}
} else if ((sh.sh_type == SHT_PROGBITS) &&
(sh.sh_flags & SHF_EXECINSTR) &&
(data->d_size > 0)) {
if (strcmp(name, ".text") == 0)
obj->efile.text_shndx = idx;
err = bpf_object__add_program(obj, data->d_buf,
data->d_size, name, idx);
if (err) {
char errmsg[STRERR_BUFSIZE];
char *cp = libbpf_strerror_r(-err, errmsg,
sizeof(errmsg));
} else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) {
if (sh.sh_flags & SHF_EXECINSTR) {
if (strcmp(name, ".text") == 0)
obj->efile.text_shndx = idx;
err = bpf_object__add_program(obj, data->d_buf,
data->d_size, name, idx);
if (err) {
char errmsg[STRERR_BUFSIZE];
char *cp = libbpf_strerror_r(-err, errmsg,
sizeof(errmsg));
pr_warning("failed to alloc program %s (%s): %s",
name, obj->path, cp);
pr_warning("failed to alloc program %s (%s): %s",
name, obj->path, cp);
}
}
} else if (sh.sh_type == SHT_REL) {
void *reloc = obj->efile.reloc;
@ -1046,24 +1046,26 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
return -LIBBPF_ERRNO__RELOC;
}
/* TODO: 'maps' is sorted. We can use bsearch to make it faster. */
for (map_idx = 0; map_idx < nr_maps; map_idx++) {
if (maps[map_idx].offset == sym.st_value) {
pr_debug("relocation: find map %zd (%s) for insn %u\n",
map_idx, maps[map_idx].name, insn_idx);
break;
if (sym.st_shndx == maps_shndx) {
/* TODO: 'maps' is sorted. We can use bsearch to make it faster. */
for (map_idx = 0; map_idx < nr_maps; map_idx++) {
if (maps[map_idx].offset == sym.st_value) {
pr_debug("relocation: find map %zd (%s) for insn %u\n",
map_idx, maps[map_idx].name, insn_idx);
break;
}
}
}
if (map_idx >= nr_maps) {
pr_warning("bpf relocation: map_idx %d large than %d\n",
(int)map_idx, (int)nr_maps - 1);
return -LIBBPF_ERRNO__RELOC;
}
if (map_idx >= nr_maps) {
pr_warning("bpf relocation: map_idx %d large than %d\n",
(int)map_idx, (int)nr_maps - 1);
return -LIBBPF_ERRNO__RELOC;
}
prog->reloc_desc[i].type = RELO_LD64;
prog->reloc_desc[i].insn_idx = insn_idx;
prog->reloc_desc[i].map_idx = map_idx;
prog->reloc_desc[i].type = RELO_LD64;
prog->reloc_desc[i].insn_idx = insn_idx;
prog->reloc_desc[i].map_idx = map_idx;
}
}
return 0;
}
@ -1425,7 +1427,7 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
}
insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
insns[insn_idx].imm = obj->maps[map_idx].fd;
} else {
} else if (prog->reloc_desc[i].type == RELO_CALL) {
err = bpf_program__reloc_text(prog, obj,
&prog->reloc_desc[i]);
if (err)