From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A1A66C31E52 for ; Sat, 15 Jun 2019 20:26:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5D3792184D for ; Sat, 15 Jun 2019 20:26:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="HkuPypsy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726907AbfFOU0H (ORCPT ); Sat, 15 Jun 2019 16:26:07 -0400 Received: from mail-qt1-f194.google.com ([209.85.160.194]:37699 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726490AbfFOU0H (ORCPT ); Sat, 15 Jun 2019 16:26:07 -0400 Received: by mail-qt1-f194.google.com with SMTP id y57so6581688qtk.4; Sat, 15 Jun 2019 13:26:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=tztss1Atv+Qv/wnnZUDfxaVfbZCH7GTnWYFuwVOsx1o=; b=HkuPypsy9bzw0HTYQpkur8CbqO3h9mMXwqmb+kL0AnKP+DFhIfspOtT9uq2dew61+o /Lxen/sNUexp2Cw5KrcJLw9IG95KQRP0/oWuHvcQg2rKB3MNFqQSSMhC2+adkbEizW3h H/wERFRn/DcmxvG8Sh068iiUUJ/5014ipnCHPE4otfid7UEXT+dcV8KNRCiqwzXfYK/A pKAjVMtckFXN1L2VhJT0Fvtcr8/oIKIgGIS17Ykqi8fIUZRNuZA8mJHcejqw4VtECYVW GhxhJQkXHgpySJDMeBw4dCmJLjWV7pwYdh3o7xsXoqOiWEGyYtWgokL3ucUJro5lOvSB E+mQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=tztss1Atv+Qv/wnnZUDfxaVfbZCH7GTnWYFuwVOsx1o=; b=QKfG/NS8h1MMs99EXCs63SquTgeQCcQDtBlGFOuKcFZi8MO1AWtJUWhgZ6+id7tsiL YAVBr0PujGh4+QCVKAtP82tXkPHXdDtUyACwOgArZfwduuIRQ4NxBvg/fyhOBy9ersns 0K0ZAXj8HSDC7Ijnfyd8/sSgM38OHocxIHFNm6gRh4G9F3JtH6pnpPoAZGafUEvwq3Ok +O1F1DMyo1dNMbAjroWgr86YapMcGCnz8HBNjpoNoVWZRZDq1aHjem9zNefTfvvGI/1I pe5fETVA4HVdGKktBM8MuK/9p5f339loAleip0BgqD2H+NMBeZHd22/++163IC/GT5KV c87A== X-Gm-Message-State: APjAAAUXiCz8OsM8V0ZKelYdzMb+dqoZl50qxeIJEv/7+EavhDE4aJkK iVOrhgyM0DfhPudQNGc7qi9c7vxB1N7xuitIfhk= X-Google-Smtp-Source: APXvYqySo8VvdQwuHVD9Sk3pzgbLTqImqeVyXdsKz/AVJYfNMZdUtexXZUqM5TH43XSLg9YaCc2IYQEpPSPayS6cdNM= X-Received: by 2002:a0c:c68d:: with SMTP id d13mr14322637qvj.145.1560630365877; Sat, 15 Jun 2019 13:26:05 -0700 (PDT) MIME-Version: 1.0 References: <20190611044747.44839-1-andriin@fb.com> <20190611044747.44839-3-andriin@fb.com> In-Reply-To: <20190611044747.44839-3-andriin@fb.com> From: Song Liu Date: Sat, 15 Jun 2019 13:25:54 -0700 Message-ID: Subject: Re: [PATCH bpf-next 2/8] libbpf: extract BTF loading and simplify ELF parsing logic To: Andrii Nakryiko Cc: Andrii Nakryiko , bpf , Networking , Alexei Starovoitov , Daniel Borkmann , Kernel Team Content-Type: text/plain; charset="UTF-8" Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Mon, Jun 10, 2019 at 9:49 PM Andrii Nakryiko wrote: > > As a preparation for adding BTF-based BPF map loading, extract .BTF and > .BTF.ext loading logic. Also simplify error handling in > bpf_object__elf_collect() by returning early, as there is no common > clean up to be done. > > Signed-off-by: Andrii Nakryiko > --- > tools/lib/bpf/libbpf.c | 137 ++++++++++++++++++++++------------------- > 1 file changed, 75 insertions(+), 62 deletions(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index ba89d9727137..9e39a0a33aeb 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -1078,6 +1078,58 @@ static void bpf_object__sanitize_btf_ext(struct bpf_object *obj) > } > } > > +static int bpf_object__load_btf(struct bpf_object *obj, > + Elf_Data *btf_data, > + Elf_Data *btf_ext_data) > +{ > + int err = 0; > + > + if (btf_data) { > + obj->btf = btf__new(btf_data->d_buf, btf_data->d_size); > + if (IS_ERR(obj->btf)) { > + pr_warning("Error loading ELF section %s: %d.\n", > + BTF_ELF_SEC, err); > + goto out; If we goto out here, we will return 0. > + } > + err = btf__finalize_data(obj, obj->btf); > + if (err) { > + pr_warning("Error finalizing %s: %d.\n", > + BTF_ELF_SEC, err); > + goto out; > + } > + bpf_object__sanitize_btf(obj); > + err = btf__load(obj->btf); > + if (err) { > + pr_warning("Error loading %s into kernel: %d.\n", > + BTF_ELF_SEC, err); > + goto out; > + } > + } > + if (btf_ext_data) { > + if (!obj->btf) { > + pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n", > + BTF_EXT_ELF_SEC, BTF_ELF_SEC); > + goto out; We will also return 0 when goto out here. > + } > + obj->btf_ext = btf_ext__new(btf_ext_data->d_buf, > + btf_ext_data->d_size); > + if (IS_ERR(obj->btf_ext)) { > + pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n", > + BTF_EXT_ELF_SEC, PTR_ERR(obj->btf_ext)); > + obj->btf_ext = NULL; > + goto out; And, here. And we will not free obj->btf. > + } > + bpf_object__sanitize_btf_ext(obj); > + } > +out: > + if (err || IS_ERR(obj->btf)) { > + if (!IS_ERR_OR_NULL(obj->btf)) > + btf__free(obj->btf); > + obj->btf = NULL; > + } > + return 0; > +} > + > static int bpf_object__elf_collect(struct bpf_object *obj, int flags) > { > Elf *elf = obj->efile.elf; > @@ -1102,24 +1154,21 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags) > if (gelf_getshdr(scn, &sh) != &sh) { > pr_warning("failed to get section(%d) header from %s\n", > idx, obj->path); > - err = -LIBBPF_ERRNO__FORMAT; > - goto out; > + return -LIBBPF_ERRNO__FORMAT; > } > > name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name); > if (!name) { > pr_warning("failed to get section(%d) name from %s\n", > idx, obj->path); > - err = -LIBBPF_ERRNO__FORMAT; > - goto out; > + return -LIBBPF_ERRNO__FORMAT; > } > > data = elf_getdata(scn, 0); > if (!data) { > pr_warning("failed to get section(%d) data from %s(%s)\n", > idx, name, obj->path); > - err = -LIBBPF_ERRNO__FORMAT; > - goto out; > + return -LIBBPF_ERRNO__FORMAT; > } > pr_debug("section(%d) %s, size %ld, link %d, flags %lx, type=%d\n", > idx, name, (unsigned long)data->d_size, > @@ -1130,10 +1179,14 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags) > err = bpf_object__init_license(obj, > data->d_buf, > data->d_size); > + if (err) > + return err; > } else if (strcmp(name, "version") == 0) { > err = bpf_object__init_kversion(obj, > data->d_buf, > data->d_size); > + if (err) > + return err; > } else if (strcmp(name, "maps") == 0) { > obj->efile.maps_shndx = idx; > } else if (strcmp(name, BTF_ELF_SEC) == 0) { > @@ -1144,11 +1197,10 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags) > if (obj->efile.symbols) { > pr_warning("bpf: multiple SYMTAB in %s\n", > obj->path); > - err = -LIBBPF_ERRNO__FORMAT; > - } else { > - obj->efile.symbols = data; > - obj->efile.strtabidx = sh.sh_link; > + return -LIBBPF_ERRNO__FORMAT; > } > + obj->efile.symbols = data; > + obj->efile.strtabidx = sh.sh_link; > } else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) { > if (sh.sh_flags & SHF_EXECINSTR) { > if (strcmp(name, ".text") == 0) > @@ -1162,6 +1214,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags) > > pr_warning("failed to alloc program %s (%s): %s", > name, obj->path, cp); > + return err; > } > } else if (strcmp(name, ".data") == 0) { > obj->efile.data = data; > @@ -1173,8 +1226,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags) > pr_debug("skip section(%d) %s\n", idx, name); > } > } else if (sh.sh_type == SHT_REL) { > + int nr_reloc = obj->efile.nr_reloc; > void *reloc = obj->efile.reloc; > - int nr_reloc = obj->efile.nr_reloc + 1; > int sec = sh.sh_info; /* points to other section */ > > /* Only do relo for section with exec instructions */ > @@ -1184,79 +1237,39 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags) > continue; > } > > - reloc = reallocarray(reloc, nr_reloc, > + reloc = reallocarray(reloc, nr_reloc + 1, > sizeof(*obj->efile.reloc)); > if (!reloc) { > pr_warning("realloc failed\n"); > - err = -ENOMEM; > - } else { > - int n = nr_reloc - 1; > + return -ENOMEM; > + } > > - obj->efile.reloc = reloc; > - obj->efile.nr_reloc = nr_reloc; > + obj->efile.reloc = reloc; > + obj->efile.nr_reloc++; > > - obj->efile.reloc[n].shdr = sh; > - obj->efile.reloc[n].data = data; > - } > + obj->efile.reloc[nr_reloc].shdr = sh; > + obj->efile.reloc[nr_reloc].data = data; > } else if (sh.sh_type == SHT_NOBITS && strcmp(name, ".bss") == 0) { > obj->efile.bss = data; > obj->efile.bss_shndx = idx; > } else { > pr_debug("skip section(%d) %s\n", idx, name); > } > - if (err) > - goto out; > } > > if (!obj->efile.strtabidx || obj->efile.strtabidx >= idx) { > pr_warning("Corrupted ELF file: index of strtab invalid\n"); > return -LIBBPF_ERRNO__FORMAT; > } > - if (btf_data) { > - obj->btf = btf__new(btf_data->d_buf, btf_data->d_size); > - if (IS_ERR(obj->btf)) { > - pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n", > - BTF_ELF_SEC, PTR_ERR(obj->btf)); > - obj->btf = NULL; > - } else { > - err = btf__finalize_data(obj, obj->btf); > - if (!err) { > - bpf_object__sanitize_btf(obj); > - err = btf__load(obj->btf); > - } > - if (err) { > - pr_warning("Error finalizing and loading %s into kernel: %d. Ignored and continue.\n", > - BTF_ELF_SEC, err); > - btf__free(obj->btf); > - obj->btf = NULL; > - err = 0; > - } > - } > - } > - if (btf_ext_data) { > - if (!obj->btf) { > - pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n", > - BTF_EXT_ELF_SEC, BTF_ELF_SEC); > - } else { > - obj->btf_ext = btf_ext__new(btf_ext_data->d_buf, > - btf_ext_data->d_size); > - if (IS_ERR(obj->btf_ext)) { > - pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n", > - BTF_EXT_ELF_SEC, > - PTR_ERR(obj->btf_ext)); > - obj->btf_ext = NULL; > - } else { > - bpf_object__sanitize_btf_ext(obj); > - } > - } > - } > + err = bpf_object__load_btf(obj, btf_data, btf_ext_data); > + if (err) > + return err; > if (bpf_object__has_maps(obj)) { > err = bpf_object__init_maps(obj, flags); > if (err) > - goto out; > + return err; > } > err = bpf_object__init_prog_names(obj); > -out: > return err; > } > > -- > 2.17.1 >