From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753610AbeFDOKp (ORCPT ); Mon, 4 Jun 2018 10:10:45 -0400 Received: from ozlabs.org ([203.11.71.1]:38337 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753580AbeFDOKm (ORCPT ); Mon, 4 Jun 2018 10:10:42 -0400 X-powerpc-patch-notification: thanks X-powerpc-patch-commit: a6b3964ad71a61bb7c61d80a60bea7d42187b2eb In-Reply-To: <20180424041559.32410-1-mpe@ellerman.id.au> To: Michael Ellerman , linuxppc-dev@ozlabs.org From: Michael Ellerman Cc: msuchanek@suse.de, linux-kernel@vger.kernel.org, npiggin@gmail.com Subject: Re: [1/6] powerpc/64s: Add barrier_nospec Message-Id: <40zxfm40PKz9s0w@ozlabs.org> Date: Tue, 5 Jun 2018 00:10:39 +1000 (AEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2018-04-24 at 04:15:54 UTC, Michael Ellerman wrote: > From: Michal Suchanek > > A no-op form of ori (or immediate of 0 into r31 and the result stored > in r31) has been re-tasked as a speculation barrier. The instruction > only acts as a barrier on newer machines with appropriate firmware > support. On older CPUs it remains a harmless no-op. > > Implement barrier_nospec using this instruction. > > mpe: The semantics of the instruction are believed to be that it > prevents execution of subsequent instructions until preceding branches > have been fully resolved and are no longer executing speculatively. > There is no further documentation available at this time. > > Signed-off-by: Michal Suchanek > Signed-off-by: Michael Ellerman Series applied to powerpc next. https://git.kernel.org/powerpc/c/a6b3964ad71a61bb7c61d80a60bea7 cheers