On Thu, 2023-12-07 at 18:09 +0000, Sergei Trofimovich wrote:
> Before the change on `i686-linux` `systemd` build failed as:
>
> $ bpftool gen object src/core/bpf/socket_bind/socket-bind.bpf.o src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
> Error: failed to link 'src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o': Invalid argument (22)
>
> After the change it fails as:
>
> $ bpftool gen object src/core/bpf/socket_bind/socket-bind.bpf.o src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
> libbpf: ELF section #9 has inconsistent alignment in src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o
> Error: failed to link 'src/core/bpf/socket_bind/socket-bind.bpf.unstripped.o': Invalid argument (22)
>
> Now it's slightly easier to figure out what is wrong with an ELF file.
Hi Sergei,
Thank you for adding these prints.
Could you please make a few adjustments, as noted below.
Also, please add "libbpf:" prefix in subject and mention
linker_sanity_check_elf in it, e.g.:
libbpf: add pr_warn() for EINVAL cases in linker_sanity_check_elf
or something like that.
[...]
> diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
> index 5ced96d99f8c..71bb4916b762 100644
> --- a/tools/lib/bpf/linker.c
> +++ b/tools/lib/bpf/linker.c
> @@ -719,13 +719,22 @@ static int linker_sanity_check_elf(struct src_obj *obj)
> return -EINVAL;
> }
>
> - if (sec->shdr->sh_addralign && !is_pow_of_2(sec->shdr->sh_addralign))
> + if (sec->shdr->sh_addralign && !is_pow_of_2(sec->shdr->sh_addralign)) {
> + pr_warn("ELF section #%zu alignment is non pow-of-2 alignment in %s\n",
> + sec->sec_idx, obj->filename);
Could you please also print values for shdr->sh_addralign here?
And also print shdr->sh_addralign/data->d_align, shdr->sh_size/data->d_size
in corresponding pr_warn() calls below.
> return -EINVAL;
> - if (sec->shdr->sh_addralign != sec->data->d_align)
> + }
> + if (sec->shdr->sh_addralign != sec->data->d_align) {
> + pr_warn("ELF section #%zu has inconsistent alignment in %s\n",
> + sec->sec_idx, obj->filename);
> return -EINVAL;
> + }
>
> - if (sec->shdr->sh_size != sec->data->d_size)
> + if (sec->shdr->sh_size != sec->data->d_size) {
> + pr_warn("ELF section #%zu has inconsistent section size in %s\n",
> + sec->sec_idx, obj->filename);
> return -EINVAL;
> + }
>
> switch (sec->shdr->sh_type) {
> case SHT_SYMTAB:
A few lines below this one there is:
case SHT_PROGBITS:
if (sec->shdr->sh_flags & SHF_EXECINSTR) {
if (sec->shdr->sh_size % sizeof(struct bpf_insn) != 0)
return -EINVAL;
}
break;
Could you please add pr_warn() there as well?
