From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 18CA3A0505; Thu, 7 Apr 2022 17:32:50 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 007E14068B; Thu, 7 Apr 2022 17:32:49 +0200 (CEST) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by mails.dpdk.org (Postfix) with ESMTP id 554D740689 for ; Thu, 7 Apr 2022 17:32:48 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1649345567; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ROGag/Uni9Rd+MWCSBcCNSAVbPss9Peg0R3v1m//rMs=; b=I+6Yu20lpnCSwJNypZjLAzv1/Mu4yJUc8yWes3CJA2wU4AYVeyGQz9s1D30mLMlO13ujO2 6LDad1sPo0RzVCnjKLF+RqiaF9k0o5kxEjvRixu5E+JmoxlS5nQkZHL+Q6ykv8V3MpbsoA 64ZD+yHEZFVdskepNEjEcohyMwFjKAM= Received: from mail-lj1-f197.google.com (mail-lj1-f197.google.com [209.85.208.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-319-tp3mWocyPGmj-DEI61--wQ-1; Thu, 07 Apr 2022 11:32:46 -0400 X-MC-Unique: tp3mWocyPGmj-DEI61--wQ-1 Received: by mail-lj1-f197.google.com with SMTP id h26-20020a2e3a1a000000b0024b109c3ef0so2280325lja.3 for ; Thu, 07 Apr 2022 08:32:46 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=ROGag/Uni9Rd+MWCSBcCNSAVbPss9Peg0R3v1m//rMs=; b=D2/6QtASWAB6vJk4TNAqGO6Lua66GZxrY1gm6pBQl/P8vu2LFnuw6aBnFHtWIb6btc 3oVhLc412I+e10fkjfoP0u/De7hx+mfVAk2LKzPbazuIi8o/GEA4LzKjKf1kE0BFPetg zCBAISIebMHyDsaLfeoD02jw2AeeIPnWegBOhY74ZmbtkoERbYmIjM661ymIqIexzLoc 7bRQl9SmwY6AFE5COmMGTiWGZdIX+kuTBLwqnP6BRXdPj9hcS3bpmtFlQdZzHQRA9BZV EjOj5T11QiakpmtaETq1fVEazdJkjrmX8jql9Hg+K5X6O5tqQrAfVMHiovGADO3njIpn QrNg== X-Gm-Message-State: AOAM531KH91BU94GtjO8Q2Rk2i2fndNzVTBtvyfh0Vk0JHeeSs1yEEEB aTfypyZELILWcxnei0VOCBdVVgU0mBL/nyZhySTqmSUAd425Cge9fep+nzONq8Wkw6nLNTWqx1Z cvquwJv/OG3Zq17wrCQ4= X-Received: by 2002:a05:6512:398a:b0:44a:56b9:c03e with SMTP id j10-20020a056512398a00b0044a56b9c03emr9618994lfu.553.1649345565230; Thu, 07 Apr 2022 08:32:45 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwRsXua89LYuxBL1W06y53JwMg2tuFJn2rau0bfoGf+PdhOeGaTn2SyXaCDS02bHxQgu3VvT+5/DPYDD8T3d5Y= X-Received: by 2002:a05:6512:398a:b0:44a:56b9:c03e with SMTP id j10-20020a056512398a00b0044a56b9c03emr9618979lfu.553.1649345565025; Thu, 07 Apr 2022 08:32:45 -0700 (PDT) MIME-Version: 1.0 References: <20220115194102.444140-1-lucp.at.work@gmail.com> <20220225163804.506142-1-lucp.at.work@gmail.com> In-Reply-To: From: David Marchand Date: Thu, 7 Apr 2022 17:32:33 +0200 Message-ID: Subject: Re: [PATCH v7] eal: fix rte_memcpy strict aliasing/alignment bugs To: "Ananyev, Konstantin" , Luc Pelletier Cc: "Richardson, Bruce" , "dev@dpdk.org" , "Li, Xiaoyun" , "stable@dpdk.org" , Aaron Conole , Owen Hilyard Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dmarchan@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On Thu, Apr 7, 2022 at 5:24 PM David Marchand wrote: > > On Thu, Mar 10, 2022 at 3:55 PM Ananyev, Konstantin > wrote: > > > Calls to rte_memcpy for 1 < n < 16 could result in unaligned > > > loads/stores, which is undefined behaviour according to the C > > > standard, and strict aliasing violations. > > > > > > The code was changed to use a packed structure that allows aliasing > > > (using the __may_alias__ attribute) to perform the load/store > > > operations. This results in code that has the same performance as the > > > original code and that is also C standards-compliant. > > > > > > Fixes: d35cc1fe6a7a ("eal/x86: revert select optimized memcpy at run-time") Actually, looking again at the history, it fixes: Fixes: f5472703c0bd ("eal: optimize aligned memcpy on x86") I'll change before pushing. -- David Marchand