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 2E9D2C3279B for ; Fri, 6 Jul 2018 19:32:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D095422CA0 for ; Fri, 6 Jul 2018 19:32:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="Awusc8NQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D095422CA0 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 S934710AbeGFTb4 (ORCPT ); Fri, 6 Jul 2018 15:31:56 -0400 Received: from mail-it0-f67.google.com ([209.85.214.67]:53083 "EHLO mail-it0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934493AbeGFTby (ORCPT ); Fri, 6 Jul 2018 15:31:54 -0400 Received: by mail-it0-f67.google.com with SMTP id p4-v6so17893138itf.2; Fri, 06 Jul 2018 12:31:54 -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=cWTzVI7PHGJeOddwFuS8XZIS1wkI0ra1pYlAy5iZCeY=; b=Awusc8NQv7hmiiw9hI7G2wOuoXiHT+5m5H38yh/guO5U1r4Q3I0EGOy0tGd+IEocsH SlWbQfepiE1zExdBt5V6Szuix/4KjzXPYwBPsMvwryVbOjDhJvOiqg5m/s3lbqcFx7ws f3SydcsfQqioAFw/QP+sntIjvuAy4+Nea6ifM= 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=cWTzVI7PHGJeOddwFuS8XZIS1wkI0ra1pYlAy5iZCeY=; b=Nzha+xkIOSn1xgquwTrIsYCc12jalyYccgscrF7z4rRkzTjCVI1tYF6N9cT03sptUY PzKEe/iSxy/UhPz1RG0IeIy/xf3McT8uoC53dGVYcr5v4gAjRlYwpZgEtQzOgp7WGOR1 PSjMYHqx+R3h28Q8aCjrn3mal5HuW63vz+AKi0Wbgi2Ty1fj9Wbfizx8yd2/o35mmH14 6gD8wY8M1lxT7e9uQh6N9KNjdCoiNQu7CcOZLPKcEeaIDZCWebSmreStH925eM1sgkV6 09CZLLq0XD+1ohx1gfNv2S3HkPLvN1H7dSsWZwmRcbqcSGfKzJIbQ2zxBJv2MdsmcSWd FnIA== X-Gm-Message-State: APt69E29wKkAvET2mGVVK0+ozfS+nahWswBb5+2FoOx3Oyfp0WuazwF9 7O0tVZlDT7uX3ypCWF2yiSEh48Q5/x7G3BYQWyQ= X-Google-Smtp-Source: AAOMgpdoobpU568vggKCfLoeY30l+6L/fmJPMazqsjhe6XIq1GA/sYeYddRxDYONIAfppLl9OG0BDSkvFb0F4UL9y8I= X-Received: by 2002:a24:d0d7:: with SMTP id m206-v6mr8862485itg.1.1530905513786; Fri, 06 Jul 2018 12:31:53 -0700 (PDT) MIME-Version: 1.0 References: <20180705180601.18423-1-mathieu.desnoyers@efficios.com> <20180705180601.18423-4-mathieu.desnoyers@efficios.com> <1846432971.1245.1530892973439.JavaMail.zimbra@efficios.com> <436937568.1359.1530905019620.JavaMail.zimbra@efficios.com> In-Reply-To: <436937568.1359.1530905019620.JavaMail.zimbra@efficios.com> From: Linus Torvalds Date: Fri, 6 Jul 2018 12:31:42 -0700 Message-ID: Subject: Re: [RFC PATCH for 4.18 3/5] rseq: uapi: declare rseq_cs field as union, update includes 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 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 Fri, Jul 6, 2018 at 12:23 PM Mathieu Desnoyers wrote: > > For -rc, I would favor the following simpler approach. Or I could even > just use get_user() instead. Thoughts ? Please just use "get_user()". In fact, we should be thinking seriosly about just removing __get_user() entirely. It's wrong. It optimizes the wrong thing entirely. It _used_ to be that the range check was noticeable, and it really isn't any more. These days the expensive parts are the SMAP costs, and both get_user() and __get_user() have those, except get_user() is safer and doesn't waste I$ on inlining the code to disable and re-enable SMAP. Linus