From 185cfe837fdbb1fcc0f6b8fbcf5fdd2d1fccd3ad Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 25 Apr 2022 17:45:07 -0700 Subject: libbpf: Record subprog-resolved CO-RE relocations unconditionally Previously, libbpf recorded CO-RE relocations with insns_idx resolved according to finalized subprog locations (which are appended at the end of entry BPF program) to simplify the job of light skeleton generator. This is necessary because once subprogs' instructions are appended to main entry BPF program all the subprog instruction indices are shifted and that shift is different for each entry (main) BPF program, so it's generally impossible to map final absolute insn_idx of the finalized BPF program to their original locations inside subprograms. This information is now going to be used not only during light skeleton generation, but also to map absolute instruction index to subprog's instruction and its corresponding CO-RE relocation. So start recording these relocations always, not just when obj->gen_loader is set. This information is going to be freed at the end of bpf_object__load() step, as before (but this can change in the future if there will be a need for this information post load step). Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20220426004511.2691730-7-andrii@kernel.org --- tools/lib/bpf/libbpf.c | 27 ++++++++++++--------------- 1 file changed, 12 insertions(+), 15 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 81f2b987fd77..109fc86335f6 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -5749,16 +5749,16 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path) return -EINVAL; insn = &prog->insns[insn_idx]; - if (prog->obj->gen_loader) { - err = record_relo_core(prog, rec, insn_idx); - if (err) { - pr_warn("prog '%s': relo #%d: failed to record relocation: %d\n", - prog->name, i, err); - goto out; - } - continue; + err = record_relo_core(prog, rec, insn_idx); + if (err) { + pr_warn("prog '%s': relo #%d: failed to record relocation: %d\n", + prog->name, i, err); + goto out; } + if (prog->obj->gen_loader) + continue; + err = bpf_core_resolve_relo(prog, rec, i, obj->btf, cand_cache, &targ_res); if (err) { pr_warn("prog '%s': relo #%d: failed to relocate: %d\n", @@ -6299,7 +6299,6 @@ bpf_object__relocate_calls(struct bpf_object *obj, struct bpf_program *prog) if (err) return err; - return 0; } @@ -6360,8 +6359,7 @@ bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path) err); return err; } - if (obj->gen_loader) - bpf_object__sort_relos(obj); + bpf_object__sort_relos(obj); } /* Before relocating calls pre-process relocations and mark @@ -6421,8 +6419,7 @@ bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path) return err; } } - if (!obj->gen_loader) - bpf_object__free_relocs(obj); + return 0; } @@ -7014,8 +7011,8 @@ bpf_object__load_progs(struct bpf_object *obj, int log_level) if (err) return err; } - if (obj->gen_loader) - bpf_object__free_relocs(obj); + + bpf_object__free_relocs(obj); return 0; } -- cgit v1.2.3-59-g8ed1b