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=-7.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no 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 1E135C4727F for ; Sun, 27 Sep 2020 09:25:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B935821D95 for ; Sun, 27 Sep 2020 09:25:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="Etk/NQgN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726328AbgI0JZj (ORCPT ); Sun, 27 Sep 2020 05:25:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54412 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726239AbgI0JZi (ORCPT ); Sun, 27 Sep 2020 05:25:38 -0400 Received: from mail-lf1-x143.google.com (mail-lf1-x143.google.com [IPv6:2a00:1450:4864:20::143]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 601E3C0613D3 for ; Sun, 27 Sep 2020 02:25:38 -0700 (PDT) Received: by mail-lf1-x143.google.com with SMTP id z19so7667658lfr.4 for ; Sun, 27 Sep 2020 02:25:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=YmrerxLsDYMh/bkqTtdxYf9dKZLk+BUPlAAIqmKW+Kg=; b=Etk/NQgNueNG3pCn1cP9EiA81EAhV0eo3ir1H8266fAVMeDikRtqsl9O8MVaWrmQK1 NX1+GgKlMFfd6IzlcAX85tsNL1fa9+WCXPQBnES+bZsPazw47PtGx823CsMoUaz7aw2u VbmGSNykeEKeVlkK0yaO/ERmFh2T0BO0reB11t7sVS0RuIQKZVeOwAFHPHMH6ikSA0eu aD0HAeG8M5nX7xMOFGFGdX0BU+gQRV2lKlGKpKGjT4o60Xa9IAZ6DGeKHoYK5Nya0f0d MhwG9nPq0m2f4QwyJVd/0+uz7BdwE7VDxvkapzLyMTfRkGaHqw4IjQybuVyiIyTegfJx wuXg== 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=YmrerxLsDYMh/bkqTtdxYf9dKZLk+BUPlAAIqmKW+Kg=; b=HmJSZ1+LqsoNR95f4fqMCofi0f6aGp0D+KdTB2YYp0J4umH/rvPI3tHpaiCXbSySTt DixZ0P9OLtteUSKtcFoVfrd5bo8rmMSGGIo9C1FCaRJttgkjiJA1VmD7QRN7Xy/ng4V/ jtOp6YOZ9EnZykV0l1qvr9aI1Bg+Khi0nvrtxxDu3dyx4NO3kydyNKtj7vzUzdpUUuNz p91QpBrirt+jAN78jw1lMuSVEgH3s1r+WZq/5taDXpDIm/ZwE2Hd3V10OwgPomETOLUL ThGQqkHBICqiTK214AMWdvYMyAOU9FjPj6tgQ6RPxg3MsqaexJlKd9J+7HyEdclaDMEP h6zA== X-Gm-Message-State: AOAM530euMCcDZ0vPlrPtkAZRRWyHEXysj/Yv6GmPk5SXCp85VLoux0F E5witHsSxu2OvR4a8fpmIPRyIaaAaF25v9xr3nuLBA== X-Google-Smtp-Source: ABdhPJwJULgLjHe/a2sr/LvdH+5pKVGkZaiqS6R8otrTEm/iiiez/V7cPU39RQZ4WnDSRaLXAtulB/9BJtYtlSMuz1Q= X-Received: by 2002:a19:6c2:: with SMTP id 185mr2074813lfg.441.1601198736857; Sun, 27 Sep 2020 02:25:36 -0700 (PDT) MIME-Version: 1.0 References: <20200907153701.2981205-1-arnd@arndb.de> <20200907153701.2981205-2-arnd@arndb.de> In-Reply-To: <20200907153701.2981205-2-arnd@arndb.de> From: Linus Walleij Date: Sun, 27 Sep 2020 11:25:25 +0200 Message-ID: Subject: Re: [PATCH 1/9] mm/maccess: fix unaligned copy_{from,to}_kernel_nofault To: Arnd Bergmann Cc: Christoph Hellwig , Russell King , Alexander Viro , "linux-kernel@vger.kernel.org" , linux-arch@vger.kernel.org, Linux ARM , Andrew Morton , Daniel Borkmann , Alexei Starovoitov , linux-mm@kvack.org, "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 7, 2020 at 5:37 PM Arnd Bergmann wrote: > On machines such as ARMv5 that trap unaligned accesses, these > two functions can be slow when each access needs to be emulated, > or they might not work at all. > > Change them so that each loop is only used when both the src > and dst pointers are naturally aligned. > > Signed-off-by: Arnd Bergmann That's a clever optimization idea, nice! Reviewed-by: Linus Walleij Yours, Linus Walleij