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=-14.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 E6983C4338F for ; Mon, 26 Jul 2021 05:22:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF08F60F02 for ; Mon, 26 Jul 2021 05:22:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231455AbhGZEmQ (ORCPT ); Mon, 26 Jul 2021 00:42:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45380 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229580AbhGZEmQ (ORCPT ); Mon, 26 Jul 2021 00:42:16 -0400 Received: from mail-pl1-x633.google.com (mail-pl1-x633.google.com [IPv6:2607:f8b0:4864:20::633]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D379DC061757 for ; Sun, 25 Jul 2021 22:22:44 -0700 (PDT) Received: by mail-pl1-x633.google.com with SMTP id e14so10259372plh.8 for ; Sun, 25 Jul 2021 22:22:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=ig73Af08fuWuddTrX2Q0MR6gFbs0CGY/f7Ly0/R2xuE=; b=Ul6Ad2vyN5bVnuFNhfaTwn7/0/bm9vDbAdINLxxb2DfPjKwJYLBsZmWKpd07VAkSdC +jWy22gfK61TY8EUjL1FLadGu050+At2oAZXo+tfhdPWXEMTrgEW7rlGjMtzt1T2nkVg G90ZDBlaK1ymm/RkhVL8SLYiQCTZoijvE4licQvIn+V5xUUeSid4KBm0tW1lSztDzMdz jXJ4zfYQjCBp8byo+4nHwtoopiVedrDQ1jYuLHBC9ROwpTlYqO7sR4YCPTQ8T+3VJN+b qD2LUHUdX/BrmYcfM5shPrbYwcL1Zj8gMYr5mDzrl8m/HggwlpsgGv4qT3Ast0YbxxoS +MdQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=ig73Af08fuWuddTrX2Q0MR6gFbs0CGY/f7Ly0/R2xuE=; b=ohPBQv5Xffk+EXIOOO8I8hnbMc7Ncl270fJqAVAa2Qy2LFSSf+sXA5gE6wR8XYzE6O Ic+yul7eSEbRxIvUO3HBbTfink3zN//bUe+cq/XEdnXQ7DQ9tBgoAPt0Y+19WFKnl0oJ stFqYQPTx8sDHaL49kWnIo/qhgU6SwC9GvUZ6RpUuG2mfjd53s9wNr5XEb8JfqffWE2y 9FeoHfbQjfTmUyRcHaAHec7OGUCaUvPZ2QHIFULu48l26ADseqwjiQaMo940wjhc/tnZ HUrdTXu7vLAE2PiBBM3Sox3diHG8i6iFwCjJKBdQhxtoO5CiixbM1yDtHr+LvAsPuEGQ Af0Q== X-Gm-Message-State: AOAM532KoKSb268HUa+WublGtM9+/oci2j2O6LR6ThHguMs6RnBLlW5e 3eIstsYm3PmyVP77oyYMcfA= X-Google-Smtp-Source: ABdhPJzP6dBVduQcPBeo8W14kvnA1Y5I6okWbsB0siSbOXLQIs2eAvHXxaAVPq/bsp7xXrrIKZYbeg== X-Received: by 2002:a62:ab0a:0:b029:33b:6d08:2a45 with SMTP id p10-20020a62ab0a0000b029033b6d082a45mr15891926pff.38.1627276964285; Sun, 25 Jul 2021 22:22:44 -0700 (PDT) Received: from [192.168.255.10] ([203.205.141.119]) by smtp.gmail.com with ESMTPSA id i18sm41947522pgb.83.2021.07.25.22.22.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 25 Jul 2021 22:22:43 -0700 (PDT) Subject: Re: [PATCH bpf-next 1/2] tools/resolve_btfids: emit warnings and patch zero id for missing symbols To: Yonghong Song , bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, john.fastabend@gmail.com, jolsa@kernel.org, yanivagman@gmail.com References: <20210725141814.2000828-1-hengqi.chen@gmail.com> <20210725141814.2000828-2-hengqi.chen@gmail.com> <95d1c440-bb99-13ad-0227-f9ab20a001f2@gmail.com> From: Hengqi Chen Message-ID: Date: Mon, 26 Jul 2021 13:22:41 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 2021/7/26 12:56 PM, Yonghong Song wrote: > > > On 7/25/21 9:41 PM, Hengqi Chen wrote: >> >> >> On 2021/7/26 11:32 AM, Yonghong Song wrote: >>> >>> >>> On 7/25/21 7:18 AM, Hengqi Chen wrote: >>>> Kernel functions referenced by .BTF_ids may changed from global to static >>>> and get inlined and thus disappears from BTF. This causes kernel build >>> >>> the function could be renamed or removed too. >>> >>>> failure when resolve_btfids do id patch for symbols in .BTF_ids in vmlinux. >>>> Update resolve_btfids to emit warning messages and patch zero id for missing >>>> symbols instead of aborting kernel build process. >>>> >>>> Signed-off-by: Hengqi Chen >>> >>> LGTM with one minor comment below. >>> >>> Acked-by: Yonghong Song >>> >>>> --- >>>>    tools/bpf/resolve_btfids/main.c | 13 +++++++------ >>>>    1 file changed, 7 insertions(+), 6 deletions(-) >>>> >>>> diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c >>>> index 3ad9301b0f00..3ea19e33250d 100644 >>>> --- a/tools/bpf/resolve_btfids/main.c >>>> +++ b/tools/bpf/resolve_btfids/main.c >>>> @@ -291,7 +291,7 @@ static int compressed_section_fix(Elf *elf, Elf_Scn *scn, GElf_Shdr *sh) >>>>        sh->sh_addralign = expected; >>>> >>>>        if (gelf_update_shdr(scn, sh) == 0) { >>>> -        printf("FAILED cannot update section header: %s\n", >>>> +        pr_err("FAILED cannot update section header: %s\n", >>>>                elf_errmsg(-1)); >>>>            return -1; >>>>        } >>>> @@ -317,6 +317,7 @@ static int elf_collect(struct object *obj) >>>> >>>>        elf = elf_begin(fd, ELF_C_RDWR_MMAP, NULL); >>>>        if (!elf) { >>>> +        close(fd); >>>>            pr_err("FAILED cannot create ELF descriptor: %s\n", >>>>                elf_errmsg(-1)); >>>>            return -1; >>>> @@ -484,7 +485,7 @@ static int symbols_resolve(struct object *obj) >>>>        err = libbpf_get_error(btf); >>>>        if (err) { >>>>            pr_err("FAILED: load BTF from %s: %s\n", >>>> -            obj->path, strerror(-err)); >>>> +            obj->btf ?: obj->path, strerror(-err)); >>> >>> Why you change "obj->path" to "obj->btf ?: obj->path"? >>> Note that obj->path cannot be NULL. >> >> The diff didn't see the whole picture. Let me quote it here: >> ``` >> btf = btf__parse(obj->btf ?: obj->path, NULL); >> err = libbpf_get_error(btf); >> if (err) { >>          pr_err("FAILED: load BTF from %s: %s\n", >>                  obj->path, strerror(-err)); >>          return -1; >> } >> ``` >> >> Because btf__parse parses either obj->btf or obj->path, >> I think the error message should reveal this. > > Okay, I see, obj->btf may not be NULL due to >                 OPT_STRING(0, "btf", &obj.btf, "BTF data", >                            "BTF data"), > > How about >   obj->btf ? "input BTF data" : obj->path > > The error message like >   FAILED: load BTF from : > does not sound good. > Sorry, I am confused. If obj->btf is set, say, vmlinux.btf, the message should look like: FAILED: load BTF from vmlinux.btf: Otherwise, it should look like: FAILED: load BTF from vmlinux: Am I missing something ? >> >>> >>>>            return -1; >>>>        } >>>> >>> [...]