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=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 2ACB5C3279B for ; Sat, 30 Jun 2018 19:01:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB39325449 for ; Sat, 30 Jun 2018 19:01:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="EK7vIj9P" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DB39325449 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 S1751890AbeF3TBf (ORCPT ); Sat, 30 Jun 2018 15:01:35 -0400 Received: from mail-io0-f194.google.com ([209.85.223.194]:36284 "EHLO mail-io0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751523AbeF3TBc (ORCPT ); Sat, 30 Jun 2018 15:01:32 -0400 Received: by mail-io0-f194.google.com with SMTP id k3-v6so11349321iog.3 for ; Sat, 30 Jun 2018 12:01:32 -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=/u+jU+4Ef6tjMWtVtI80r0J7E5Z6EDU4kldRmqBNPmk=; b=EK7vIj9P93hZysHHTkXTuoT+wjqCs1MXhIL+oS3ZGa97RSBiS4ncseApWguRRWKkhY m2RK3ltowN2/gwG24epAhBT1HqlvuJ0jAUTEct7B6trbl6+Nw/NLc6VyNFwdQwzWM3ZA V9iSuOTZ/dJWcoh9u/EGhFr41Qw0PXU7AED58= 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=/u+jU+4Ef6tjMWtVtI80r0J7E5Z6EDU4kldRmqBNPmk=; b=C6xAx7LflW+uv8lSoXZkM3raTaA+XcQFSXHq+/c8D55fHIl2cyNkvflmD2vqt9j75l NXqEa0YPYtjuN4AEKvV62Nql6iIRutW0OmVceJl70zcL31/2CAA4MbK3wXxgXA/j+ob4 osQ/eLMxwen+bYSAuZwD2cLJ2J7FTZdvpl3xBqjksBgMyEc2rMJ4rsaL771novmhxfz0 XLlRJKwFpw0OWNoMISaZZjB4G5zFNrZ7C8pVc4wpaZ1cl9D8Vs4UqMgDlFxManvomnlz RAq6h2TLvfMyYSmlooTDJua64wRsB9fBskJCSXuDCgpHrcdzdi9NM0P0QN/9EZmJSe/P L5Fg== X-Gm-Message-State: APt69E0JAvwwXtUumC2aB5Zc8/0PmpgD67zGhxISJ4GUJcRx5a1bQV8I 7YDv62jTkeLQaQij+XOzzNC/lDZ6gAKwcJI2toQ= X-Google-Smtp-Source: AAOMgpcPCeosIbFdKXIPK0PpmSKxm1mbAhdvlsDKE13UXagvRXdGVe2GtT2DGnj2+YPAv17A8cTSbGdPJkSIwOpgGT8= X-Received: by 2002:a6b:274f:: with SMTP id n76-v6mr16967713ion.259.1530385291614; Sat, 30 Jun 2018 12:01:31 -0700 (PDT) MIME-Version: 1.0 References: <20180630084933.GA15210@gmail.com> In-Reply-To: <20180630084933.GA15210@gmail.com> From: Linus Torvalds Date: Sat, 30 Jun 2018 12:01:20 -0700 Message-ID: Subject: Re: [GIT PULL] x86 fixes To: Ingo Molnar , Andy Lutomirski Cc: Linux Kernel Mailing List , Thomas Gleixner , Peter Zijlstra , Andrew Morton 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 Sat, Jun 30, 2018 at 1:49 AM Ingo Molnar wrote: > > --- a/arch/x86/entry/entry_32.S > +++ b/arch/x86/entry/entry_32.S > @@ -477,7 +477,7 @@ ENTRY(entry_SYSENTER_32) > * whereas POPF does not.) > */ > addl $PT_EFLAGS-PT_DS, %esp /* point esp at pt_regs->flags */ > - btr $X86_EFLAGS_IF_BIT, (%esp) > + btrl $X86_EFLAGS_IF_BIT, (%esp) > popfl Ho humm. Just looking at this patch, my reaction was "why isn't this an 'andl $~X86_EFLAGS_IF' instead"? Yeah, I guess the 'andl' is two bytes longer (due to the 32-bit constant - because IF is bit 9, you can't use a byte constant, and you don't want to get a partial word write just before the popfl). But btr is really pretty heavy operation for older CPU's (it's gotten better, but 32-bit code presumably cares more about the older CPUs). It really doesn't matter, I guess. The btr goes back to commit c2c9b52fab0d ("x86/entry/32: Restore FLAGS on SYSEXIT"). Andy? Linus