From mboxrd@z Thu Jan 1 00:00:00 1970
Return-Path: <dev-bounces@dpdk.org>
Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124])
by inbox.dpdk.org (Postfix) with ESMTP id 1FCFEA0505;
Thu, 7 Apr 2022 17:40:18 +0200 (CEST)
Received: from [217.70.189.124] (localhost [127.0.0.1])
by mails.dpdk.org (Postfix) with ESMTP id C48D94068B;
Thu, 7 Apr 2022 17:40:17 +0200 (CEST)
Received: from us-smtp-delivery-124.mimecast.com
(us-smtp-delivery-124.mimecast.com [170.10.133.124])
by mails.dpdk.org (Postfix) with ESMTP id BEB8640689
for <dev@dpdk.org>; Thu, 7 Apr 2022 17:40:16 +0200 (CEST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;
s=mimecast20190719; t=1649346016;
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=dbdmsdHpedEzfkRofOzcrfDbpEpJf8UuWtyyp60a99Y=;
b=XfZdkqWOu1OII5PeeGXdOSNYivLRjSFcMYHRVyZYSADCPOqGZs2DKr4FceAW/6Bz0lFvXs
lvtmlZsRJGJj31fROwvCsSGtHhoqhREOTRtJl1gu4mXK0xLxx6sv16oqkSV4ME4XFXZyxI
VTJwXP254UVL5Ie/4CiagaahLR21H9w=
Received: from mail-lf1-f70.google.com (mail-lf1-f70.google.com
[209.85.167.70]) by relay.mimecast.com with ESMTP with STARTTLS
(version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id
us-mta-278-nDfwReDdNrur4LoXsYVnbA-1; Thu, 07 Apr 2022 11:40:15 -0400
X-MC-Unique: nDfwReDdNrur4LoXsYVnbA-1
Received: by mail-lf1-f70.google.com with SMTP id
f39-20020a0565123b2700b0044f567f870dso1961453lfv.13
for <dev@dpdk.org>; Thu, 07 Apr 2022 08:40:14 -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=dbdmsdHpedEzfkRofOzcrfDbpEpJf8UuWtyyp60a99Y=;
b=ExMMO6h9MliLGJBs+qIPtyMJyazOHTmyCbs5VnDdToQF8QB6j3uNPiP96uUz1GlOCK
mh0TWiFIu868grqhQnyVX+JM6G/9SXt68vYd6VDGlJTkyIsfsV+bwmTvjlG1ag5q2B30
Hr7NRfM3nOJdj51RkSo1t/AfWLyVvrcrqoWqs/rdG3nV+s65GWlQlW4yCW422jLiqaBB
gk4XXz3L/xn/MUsf6mCQx6lx9NnvaCVcSowIWsloxZEx20WDCP/uQ9TfsD37c+MUDclH
QqKxrUuPzTrj5/BykMsyOR8UN6gwF6uR5zbo5U4zzU1sJaO5Xag0tBbdafgqkTYAhsFs
97Pw==
X-Gm-Message-State: AOAM531RvuAB089vx2HVO4n3dq8k+FkdwOyn3up6qRe9a8IrqNS51dWK
w4Ek1wjKxP7IdbZH5TONxYYKKfFfyC4NdTdpWcqqlr7BvaZm0GHy9UDEioWOp1DZLuuv909Fbnu
aXPpZxW4Fi9tTjaT/SUw=
X-Received: by 2002:a05:651c:1781:b0:247:daa7:4358 with SMTP id
bn1-20020a05651c178100b00247daa74358mr8869311ljb.477.1649346013548;
Thu, 07 Apr 2022 08:40:13 -0700 (PDT)
X-Google-Smtp-Source: ABdhPJxN7l4/3mCYErouw4Jv22MsVZ60hCXJAUFtwe7yhr/uHSFTvC8Pw/KUxSjq7/NEgT1B0bXH1TBwZkmpdpvnYOw=
X-Received: by 2002:a05:651c:1781:b0:247:daa7:4358 with SMTP id
bn1-20020a05651c178100b00247daa74358mr8869299ljb.477.1649346013372; Thu, 07
Apr 2022 08:40:13 -0700 (PDT)
MIME-Version: 1.0
References: <20220115194102.444140-1-lucp.at.work@gmail.com>
<20220225163804.506142-1-lucp.at.work@gmail.com>
<DM6PR11MB449118A6002204BEA83D1B7A9A0B9@DM6PR11MB4491.namprd11.prod.outlook.com>
<CAJFAV8yxK-qqQtNLrNFqyo1T+6qTSGfotSGufgR1SOY1muMzdg@mail.gmail.com>
<CAJFAV8zRAGR4L80xLjcmYXFi5nhTn8ioSkF-DZsnh1+ya-tzAg@mail.gmail.com>
In-Reply-To: <CAJFAV8zRAGR4L80xLjcmYXFi5nhTn8ioSkF-DZsnh1+ya-tzAg@mail.gmail.com>
From: David Marchand <david.marchand@redhat.com>
Date: Thu, 7 Apr 2022 17:40:02 +0200
Message-ID: <CAJFAV8zeOUm7ZC7nJ-fzqF19MwSqkQ+nKy9+niRW+QM3Zv8Ktg@mail.gmail.com>
Subject: Re: [PATCH v7] eal: fix rte_memcpy strict aliasing/alignment bugs
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
Luc Pelletier <lucp.at.work@gmail.com>
Cc: "Richardson, Bruce" <bruce.richardson@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>,
"Li, Xiaoyun" <xiaoyun.li@intel.com>, "stable@dpdk.org" <stable@dpdk.org>,
Aaron Conole <aconole@redhat.com>, Owen Hilyard <ohilyard@iol.unh.edu>
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 <dev.dpdk.org>
List-Unsubscribe: <https://mails.dpdk.org/options/dev>,
<mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://mails.dpdk.org/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <https://mails.dpdk.org/listinfo/dev>,
<mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
On Thu, Apr 7, 2022 at 5:32 PM David Marchand <david.marchand@redhat.com> wrote:
>
> On Thu, Apr 7, 2022 at 5:24 PM David Marchand <david.marchand@redhat.com> wrote:
> >
> > On Thu, Mar 10, 2022 at 3:55 PM Ananyev, Konstantin
> > <konstantin.ananyev@intel.com> 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")
Nop, that's probably even older, could you double check?
I'll hold on pushing this fix.
--
David Marchand