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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 4B45BCA9EA0 for ; Mon, 4 Nov 2019 11:39:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1D1072184C for ; Mon, 4 Nov 2019 11:39:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727976AbfKDLji (ORCPT ); Mon, 4 Nov 2019 06:39:38 -0500 Received: from foss.arm.com ([217.140.110.172]:40534 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726441AbfKDLjh (ORCPT ); Mon, 4 Nov 2019 06:39:37 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D25E61FB; Mon, 4 Nov 2019 03:39:36 -0800 (PST) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9781E3F71A; Mon, 4 Nov 2019 03:39:34 -0800 (PST) Date: Mon, 4 Nov 2019 11:39:30 +0000 From: Mark Rutland To: Sami Tolvanen Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Dave Martin , Kees Cook , Laura Abbott , Marc Zyngier , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 04/17] arm64: kernel: avoid x18 __cpu_soft_restart Message-ID: <20191104113929.GA45140@lakrids.cambridge.arm.com> References: <20191018161033.261971-1-samitolvanen@google.com> <20191101221150.116536-1-samitolvanen@google.com> <20191101221150.116536-5-samitolvanen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191101221150.116536-5-samitolvanen@google.com> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 01, 2019 at 03:11:37PM -0700, Sami Tolvanen wrote: > From: Ard Biesheuvel > > The code in __cpu_soft_restart() uses x18 as an arbitrary temp register, > which will shortly be disallowed. So use x8 instead. > > Link: https://patchwork.kernel.org/patch/9836877/ > Signed-off-by: Ard Biesheuvel > [Sami: updated commit message] > Signed-off-by: Sami Tolvanen > Reviewed-by: Mark Rutland > Reviewed-by: Kees Cook Trivial nit, but the commit title is missing "in" between x18 and __cpu_soft_restart. Mark. > --- > arch/arm64/kernel/cpu-reset.S | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S > index 6ea337d464c4..32c7bf858dd9 100644 > --- a/arch/arm64/kernel/cpu-reset.S > +++ b/arch/arm64/kernel/cpu-reset.S > @@ -42,11 +42,11 @@ ENTRY(__cpu_soft_restart) > mov x0, #HVC_SOFT_RESTART > hvc #0 // no return > > -1: mov x18, x1 // entry > +1: mov x8, x1 // entry > mov x0, x2 // arg0 > mov x1, x3 // arg1 > mov x2, x4 // arg2 > - br x18 > + br x8 > ENDPROC(__cpu_soft_restart) > > .popsection > -- > 2.24.0.rc1.363.gb1bccd3e3d-goog >