On Tue, Nov 23, 2021 at 10:02 PM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> From: Alexei Starovoitov <ast@xxxxxxxxxx>
>
> Without lskel the CO-RE relocations are processed by libbpf before any other
> work is done. Instead, when lskel is needed, remember relocation as RELO_CORE
> kind. Then when loader prog is generated for a given bpf program pass CO-RE
> relos of that program to gen loader via bpf_gen__record_relo_core(). The gen
> loader will remember them as-is and pass it later as-is into the kernel.
>
> The normal libbpf flow is to process CO-RE early before call relos happen. In
> case of gen_loader the core relos have to be added to other relos to be copied
> together when bpf static function is appended in different places to other main
> bpf progs. During the copy the append_subprog_relos() will adjust insn_idx for
> normal relos and for RELO_CORE kind too. When that is done each struct
> reloc_desc has good relos for specific main prog.
>
> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
> ---
> tools/lib/bpf/bpf_gen_internal.h | 3 +
> tools/lib/bpf/gen_loader.c | 41 +++++++++++-
> tools/lib/bpf/libbpf.c | 108 ++++++++++++++++++++++---------
> 3 files changed, 119 insertions(+), 33 deletions(-)
>
LGTM, minor styling nit, please address if/when resubmitting.
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
[...]
> @@ -6600,6 +6638,16 @@ static int bpf_program__record_externs(struct bpf_program *prog)
> ext->is_weak, false, BTF_KIND_FUNC,
> relo->insn_idx);
> break;
> + case RELO_CORE: {
> + struct bpf_core_relo cr = {
> + .insn_off = relo->insn_idx * 8,
> + .type_id = relo->core_relo->type_id,
> + .access_str_off = relo->core_relo->access_str_off,
> + .kind = relo->core_relo->kind,
> + };
nit: empty line between variable and statements
> + bpf_gen__record_relo_core(obj->gen_loader, &cr);
> + break;
> + }
> default:
> continue;
> }
> @@ -6639,7 +6687,7 @@ static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog
> prog->name, prog->instances.nr);
> }
> if (obj->gen_loader)
> - bpf_program__record_externs(prog);
> + bpf_program_record_relos(prog);
> err = bpf_object_load_prog_instance(obj, prog,
> prog->insns, prog->insns_cnt,
> license, kern_ver, &fd);
> --
> 2.30.2
>
