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 autolearn=unavailable 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 37275C31E52 for ; Sat, 15 Jun 2019 20:28:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E90262184D for ; Sat, 15 Jun 2019 20:28:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="MNwKhhOl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727006AbfFOU2i (ORCPT ); Sat, 15 Jun 2019 16:28:38 -0400 Received: from mail-qt1-f193.google.com ([209.85.160.193]:40459 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726490AbfFOU2i (ORCPT ); Sat, 15 Jun 2019 16:28:38 -0400 Received: by mail-qt1-f193.google.com with SMTP id a15so6552858qtn.7; Sat, 15 Jun 2019 13:28:37 -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=AFXP8ArBgwuQMhnw6wU4tmFPigpMKj9TBA5brc9hfIA=; b=MNwKhhOlhWhepZiReL6nhIZvxSj36Qz1pFZeXHeMVBgWCd0ekk+mE+8/xx9H0KxkAB /Ra6HPHA2jjgCNi13srBnHz53ms6rEzR2HADOhXMVL1e6tCzTGzNjwh545yG+gCWvbbW 2R9IU2hiZX1djzxJKm8AUqt6mfuAfR+i9JojIn0ixoVEfbFRARD+yo8rzJShry4vH/Dy FetKc2L3PY6KDUMx2cB0+1Gjh/vcUnJdCciPY1Z/YiughdE7jDodKE66hcgUpEBxCEij xCwtwnaa7+i57xEkbBjTtN0Vy7OTOk5T0T3Utbt/oc6srE1p9Qfu3YzsZQLr7o2Jg2Va 0EcA== 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=AFXP8ArBgwuQMhnw6wU4tmFPigpMKj9TBA5brc9hfIA=; b=hRvdURbyom9orMqHQNVZSupfM7N1z24DM0kzzelZRhthu7epAkycc2K8dZEoJoVq/h cFfk3aztYDVPLShNwfSzird2MWHltkNQjExpjNVervBbvCCQhXSbGLNoGgWOAqXDBTYs paRhRgdzjn4kMQ7KT/+/Ugx/vCE39zYNOy9nYe8zhxXctTL9ARLnXg2aolfoC9f6OJ84 JxY8iX2AxjWzhGrUEFW4DZjgv3uJJ39C2Gauzt82migQfKXeOIKjx+/qkK3RRV14UhcE wEobNODM/hp6UFAHcu+VRhpVWt2QctXifeIyThKSbmfr+26XShI/K2S2dz0DjTui2sFm IfzQ== X-Gm-Message-State: APjAAAWttxXop5F4so95KRyR56/4++SCEjnbr8v0bI4wYfGawMqTB1JT nXFoS5i/UtsRySfZ4oI2ACii3N9tWvU7ckTeNZc= X-Google-Smtp-Source: APXvYqwlzKv7do6hIHpRYsqfYZr5Q0IgWk6JIYH9FQzEQtkqP8wEpi7O3BwCZhDukrbEqyd7QEoOlv7DMOD9x/FM2u4= X-Received: by 2002:ac8:1af4:: with SMTP id h49mr78106194qtk.183.1560630517248; Sat, 15 Jun 2019 13:28:37 -0700 (PDT) MIME-Version: 1.0 References: <20190611044747.44839-1-andriin@fb.com> <20190611044747.44839-3-andriin@fb.com> In-Reply-To: From: Song Liu Date: Sat, 15 Jun 2019 13:28:26 -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: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sat, Jun 15, 2019 at 1:25 PM Song Liu wrote: > > 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. Maybe separate bpf_object__load_btf() and other cleanup in two patches? (I won't complain if you keep them together) Thanks, Song > > > > 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 > >