From patchwork Thu Jan 21 11:35:20 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Giuliano Procida X-Patchwork-Id: 12035693 X-Patchwork-Delegate: bpf@iogearbox.net 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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 AF75FC433DB for ; Thu, 21 Jan 2021 11:36:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F045233EF for ; Thu, 21 Jan 2021 11:36:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728676AbhAULgr (ORCPT ); Thu, 21 Jan 2021 06:36:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43078 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730477AbhAULgN (ORCPT ); Thu, 21 Jan 2021 06:36:13 -0500 Received: from mail-wm1-x34a.google.com (mail-wm1-x34a.google.com [IPv6:2a00:1450:4864:20::34a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 664E8C061794 for ; Thu, 21 Jan 2021 03:35:31 -0800 (PST) Received: by mail-wm1-x34a.google.com with SMTP id q24so412523wmc.1 for ; Thu, 21 Jan 2021 03:35:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=tHm4aawgl4upxAANEu6km7IPT8qo7sF57UAGh5jcpEQ=; b=Ds0HNmp+7d57PEygc5eJeuDPMs2K36GpyTgvXuI+sYnvLHDRl4l47t84aX6pqaOUyN M0cqR7DNwQdUFHH+U7RNJYRbRfePFqBPHiKCBVXGiMUt1mPvM3LgLWVDcqqwiTKerhNV yYFLIRDLzcO7VtceJd29Dm1Kyi5aIytZjBpTfHkW+T1wyed2Gvueb08kJqPdQjaDqlHX gwE8jpy9C7X7QxUH2bqooA80qU3E+A3NdGgz15Tf5EKlqB9Hl+JgHnNHnN2XBHvtyaAx g3TiIHdXrlEDWjy8aLL5wdQWKGRWBHYS6XHEZbyrq3JseIowte/ev73FyiyQT1Oh5t0u Vn/w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=tHm4aawgl4upxAANEu6km7IPT8qo7sF57UAGh5jcpEQ=; b=rBy7gyQAK+dGt5yddKyg4v3fXUz1zW/o6hwN4m1BqDbDU3RYEvfnSjDO23krXJcVpl CBF9Bpcnh7h868GnM21nDfgFyPjmU1HhamE4t5FuowUe7lTnyt7YzvzBkEnleUgB4/6y JRKLmxoVYyQsmJGsER3qrpkgL+WkzQ3aMy8UYIU6qxdSn2S6qpMyn2nP8OEvbYTTfR0a Qlie6zNuClxpq/D7N6tX/jkI0/V8iyjK5cuRuSu4uBeK6vdaVUT9CeQ3lPRKlUQ0uqn7 VyF2P8ntgZ8MgAsu3DusNjjVLABmO/s/zbJiuWkc0z2lc2nO2ZTBjkCF+lSY9pXXx73t IIXQ== X-Gm-Message-State: AOAM532GbSuhuiqG9bLg6dqkKrpcvUskcFv3e4RX28JSbmi1y1vDClDD aqNbsv0clRU5FcgCkbj/tL1BarZS0stabw== X-Google-Smtp-Source: ABdhPJwkT3VH4D3ylEUPgDZEGZQ7ElFObJ8fc1L0AgD7z8Ml7WHUWCN/ZDwWYaaUpj/nBbu9yEwa89ciGUC+dA== Sender: "gprocida via sendgmr" X-Received: from tef.lon.corp.google.com ([2a00:79e0:d:110:a6ae:11ff:fe11:4f04]) (user=gprocida job=sendgmr) by 2002:a5d:4806:: with SMTP id l6mr11402294wrq.389.1611228930100; Thu, 21 Jan 2021 03:35:30 -0800 (PST) Date: Thu, 21 Jan 2021 11:35:20 +0000 In-Reply-To: <20210121113520.3603097-1-gprocida@google.com> Message-Id: <20210121113520.3603097-4-gprocida@google.com> Mime-Version: 1.0 References: <20210118160139.1971039-1-gprocida@google.com> <20210121113520.3603097-1-gprocida@google.com> X-Mailer: git-send-email 2.30.0.296.g2bfb1c46d8-goog Subject: [PATCH dwarves v2 3/3] btf_encoder: Set .BTF section alignment to 16 From: Giuliano Procida To: dwarves@vger.kernel.org Cc: kernel-team@android.com, maennich@google.com, ast@kernel.org, andrii@kernel.org, bpf@vger.kernel.org, kernel-team@fb.com, Giuliano Procida Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org NOTE: Do not apply. I will try to eliminate the dependency on objcopy instead and achieve what's needed directly using libelf. This is to avoid misaligned access when memory-mapping ELF sections. Signed-off-by: Giuliano Procida --- libbtf.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/libbtf.c b/libbtf.c index 7552d8e..2f12d53 100644 --- a/libbtf.c +++ b/libbtf.c @@ -797,6 +797,14 @@ static int btf_elf__write(const char *filename, struct btf *btf) goto unlink; } + snprintf(cmd, sizeof(cmd), "%s --set-section-alignment .BTF=16 %s", + llvm_objcopy, filename); + if (system(cmd)) { + /* non-fatal, this is a nice-to-have and it's only supported from LLVM 10 */ + fprintf(stderr, "%s: warning: failed to align .BTF section in '%s': %d!\n", + __func__, filename, errno); + } + err = 0; unlink: unlink(tmp_fn);