From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 40zxfn3hY2zF0dT for ; Tue, 5 Jun 2018 00:10:41 +1000 (AEST) 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) List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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