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=-11.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no 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 F0FB3CA9EA0 for ; Fri, 18 Oct 2019 17:05:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C68C92064A for ; Fri, 18 Oct 2019 17:05:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="pru8Y7xs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2505274AbfJRRFd (ORCPT ); Fri, 18 Oct 2019 13:05:33 -0400 Received: from mail-vs1-f65.google.com ([209.85.217.65]:42443 "EHLO mail-vs1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2505215AbfJRRFb (ORCPT ); Fri, 18 Oct 2019 13:05:31 -0400 Received: by mail-vs1-f65.google.com with SMTP id m22so4484907vsl.9 for ; Fri, 18 Oct 2019 10:05:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=x6GpsgHPaenSyC5p+IrYQknWia4lKY0B5Vf4l4gdQSw=; b=pru8Y7xsWSIdqZR1UXLglz64NrdFImykv1hpXma1k378qh9GF0SPliCcyZB8vMX7gE X3PfTswubuOthM8DCa4MKuMqqB1ZfOPHIhuEN9TMHd7OTZoscSb0DkIwcKzx/zVRsRzZ QpVsX696Og4ZxdvD3yeFj/AnBmqkJaxHpcBabDgxa1/06jnOKR4SPg62RTTmmQ52t+8S vOzXu4T6IK5JJ+sLrpw1VPCRku6gZS08n7Kckhw2KqDpdWTQICKrAUvwcmSbe2WDexT6 KcVKUWL1M2hSYKLv2USJ9PsVEnaLnEqc22VydBFXRMPGh4AiAOA8mz7cgBZHgxDEDolP r6Cg== 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=x6GpsgHPaenSyC5p+IrYQknWia4lKY0B5Vf4l4gdQSw=; b=rLZ53lJURkkhqNXHY0VdIGmIIehCuLH2Tl3vyt+4i771o4eliM4of2xHTatPl8gWBR XnOnh6xaUkNubnJFWFClt46oWKnH8f4IGyN3SJ3slPVUY5xjqdWN9z6PZL4IFf5TVhgx Gg0o3G0CT3NuwJbtreozNigPtgc5B+zUF1RbpRUZj8cJzXN7ahRp0XKQYR9X+LNMIsx1 jPZOms52urQBnV41e1Ov/9J+o2u5AiBlcuXW17HlFk4dPhVAE2YtDUCvL2pZw1o7QFpZ FxVtKEexfaJxgjKuKndoTmauHuvg/Dy2y29Kk6bDKWCS1ck1uv/UBFta43j00ZBxJdWd 5+eg== X-Gm-Message-State: APjAAAU5+lDaOYuDNQxovZ6OMT+ZqZt21tcyjR5dyYA7zIapJD83H8vM 6Sq6L150nqDwFq8NaOdX/+WM51Qczmn3aMx/gSkACQ== X-Google-Smtp-Source: APXvYqwYzSrQhNESR2odZjGb7CA2wtjkk8PIj6W3+g28TbncpOPsZUdRhuZ5AejLhrFJsW3Q8+X1IzSvMoqY0M2m7JA= X-Received: by 2002:a67:ffc7:: with SMTP id w7mr6159173vsq.15.1571418330160; Fri, 18 Oct 2019 10:05:30 -0700 (PDT) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191018161033.261971-14-samitolvanen@google.com> In-Reply-To: From: Sami Tolvanen Date: Fri, 18 Oct 2019 10:05:18 -0700 Message-ID: Subject: Re: [PATCH 13/18] arm64: preserve x18 when CPU is suspended To: Nick Desaulniers Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Ard Biesheuvel , Dave Martin , Kees Cook , Laura Abbott , Mark Rutland , clang-built-linux , Kernel Hardening , Linux ARM , LKML 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 Fri, Oct 18, 2019 at 9:49 AM Nick Desaulniers wrote: > > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S > > index fdabf40a83c8..9a8bd4bc8549 100644 > > --- a/arch/arm64/mm/proc.S > > +++ b/arch/arm64/mm/proc.S > > @@ -73,6 +73,9 @@ alternative_endif > > stp x8, x9, [x0, #48] > > stp x10, x11, [x0, #64] > > stp x12, x13, [x0, #80] > > +#ifdef CONFIG_SHADOW_CALL_STACK > > + stp x18, xzr, [x0, #96] > > Could this be a str/ldr of just x18 rather than stp/ldp of x18 + > garbage? Maybe there's no real cost difference, or some kind of > alignment invariant? Sure, this can be changed to str/ldr. I don't think there's a noticeable difference in cost. Sami