From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Message-ID: <542B8C7F.70108@fds-team.de>
Date: Wed, 01 Oct 2014 07:09:19 +0200
From: Sebastian Lackner <sebastian@fds-team.de>
MIME-Version: 1.0
To: Andy Lutomirski <luto@amacapital.net>,
	Thomas Gleixner <tglx@linutronix.de>, X86 ML <x86@kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>
CC: Anish Bhatt <anish@chelsio.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Chuck Ebbert <cebbert.lkml@gmail.com>, stable@vger.kernel.org
Subject: Re: [PATCH v2 1/2] x86_64,entry: Filter RFLAGS.NT on entry from userspace
References: <cover.1412138935.git.luto@amacapital.net> <0e906bdeba3660c9766248d3d7229e78a423ca5b.1412138935.git.luto@amacapital.net>
In-Reply-To: <0e906bdeba3660c9766248d3d7229e78a423ca5b.1412138935.git.luto@amacapital.net>
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <stable.vger.kernel.org>

> +	testl $X86_EFLAGS_NT,EFLAGS(%rsp)	/* saved EFLAGS match cpu */
> +	jz 1f
> +	pushq_cfi $(X86_EFLAGS_IF|X86_EFLAGS_FIXED)
> +	popfq_cfi
> +1:
> +

Do you think it makes sense to change the order here, so that no jump happens if
NT is not set (which happens a bit more often, than the other way round)? Just a
guess though, haven't measured if pipeline effects have such a big influence in this
case. ;)