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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED 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 4D063C5CFEB for ; Mon, 9 Jul 2018 18:04:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0C2642087C for ; Mon, 9 Jul 2018 18:04:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="fl+2CkLR" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0C2642087C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934006AbeGISEm (ORCPT ); Mon, 9 Jul 2018 14:04:42 -0400 Received: from mail-io0-f194.google.com ([209.85.223.194]:45216 "EHLO mail-io0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933775AbeGISEk (ORCPT ); Mon, 9 Jul 2018 14:04:40 -0400 Received: by mail-io0-f194.google.com with SMTP id l25-v6so17862626ioh.12; Mon, 09 Jul 2018 11:04:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=wa1xusVboXCkqCacRrAsaOCtihfIK5/GT3tCUm4CBtk=; b=fl+2CkLR+MuSH3bnmIWWHygAuODBNKPx5rCOa7MX+eoKms9AuCeoRGNwY7sjcNxD3D 093IoMUlFHQCTCKp3NK1BpXtkzTRyXSIL3pJEpkfu7gIzgwcasV+Qh46bhoAK1F4aiEx oVaTZhMuOWU2WMrQ7k0YAMGCxEoFnhyRHvBMI= 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=wa1xusVboXCkqCacRrAsaOCtihfIK5/GT3tCUm4CBtk=; b=AnEXmQyMSZlECo3bCbWtWgZTMb0FjOSgo/c1ZKJsU0W5oE0tMRNfzT8JWu5wafwysn ooKGPK4MReDqjdYq+C9aVe7Cb5Dsn7rqo4YiXYmEzMMLx+OL9JpJChmtLv2l3LyqTG9J ti3oP4UQv0ASDRpN8HAmfEMOELkkI4IoXt+cHr2k/Tv8kJQmHwpi56jbOF2okL5lx34G weihbUmEQChhvHqXGc94+2qwFQIBQirF9asDKYEzxTS8ioWeNJmO+A34huTD3IOjk2od pquIzC+iHLs9c11ED6i5MHoCjBhp2fiAf7QFn+b7r8vmU0+ErvTXUrXQF73Wkmyt6fS7 /ElA== X-Gm-Message-State: APt69E32V9rSel6RZ6kCovuPtWlfZP5XPUS7Eh19z28lIDGsCBdz25eg +sdueV+HC0JzlrkQBZjC3lQTD1Ml/C7MOZiozBM= X-Google-Smtp-Source: AAOMgpeaN5JmUqqlH4zQuLTrEci9bK8NoSW/ZDmNOsJ/AU0cRIS1ECGu3XSgHdFsVAD/zxnjj8jTgK6CKbRYg5unfAA= X-Received: by 2002:a6b:7a05:: with SMTP id h5-v6mr2743478iom.238.1531159479667; Mon, 09 Jul 2018 11:04:39 -0700 (PDT) MIME-Version: 1.0 References: <20180708210330.27324-1-mathieu.desnoyers@efficios.com> <20180708210330.27324-3-mathieu.desnoyers@efficios.com> <854203778.2272.1531157327328.JavaMail.zimbra@efficios.com> In-Reply-To: <854203778.2272.1531157327328.JavaMail.zimbra@efficios.com> From: Linus Torvalds Date: Mon, 9 Jul 2018 11:04:28 -0700 Message-ID: Subject: Re: [PATCH for 4.18 2/6] rseq: use get_user/put_user rather than __get_user/__put_user To: Mathieu Desnoyers Cc: Thomas Gleixner , Linux Kernel Mailing List , Linux API , Peter Zijlstra , Paul McKenney , Boqun Feng , Andy Lutomirski , Dave Watson , Paul Turner , Andrew Morton , Russell King - ARM Linux , Ingo Molnar , Peter Anvin , Andi Kleen , Christoph Lameter , Ben Maurer , Steven Rostedt , Josh Triplett , Catalin Marinas , Will Deacon , Michael Kerrisk , Joel Fernandes , Andrew Hunter , linux-arm-kernel Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 9, 2018 at 10:28 AM Mathieu Desnoyers wrote: > > So, another twist to this story: ppc32 does not implement u64 get_user(). I was going to say that "that's not possible", since we actually have 64-bit arguments at least in the form of "loff_t __user *". But when I started looking, it turns out that yeah, we do "copy_from_user()" on them, and instead made the x86 copy_from_user() have special cases for constant sizes. So a 8-byte copy_from_user() is fine. It ends up being a "get_user()" on x86 anyway. Linus