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=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 51456CA9ECB for ; Thu, 31 Oct 2019 17:42:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 29B5C2083E for ; Thu, 31 Oct 2019 17:42:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="vyAZGLuQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729121AbfJaRmb (ORCPT ); Thu, 31 Oct 2019 13:42:31 -0400 Received: from mail-vs1-f68.google.com ([209.85.217.68]:34346 "EHLO mail-vs1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728974AbfJaRma (ORCPT ); Thu, 31 Oct 2019 13:42:30 -0400 Received: by mail-vs1-f68.google.com with SMTP id 127so1725399vsn.1 for ; Thu, 31 Oct 2019 10:42:29 -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=SpMt9swBFV/X7pJxY11yJxvoU/jl5TYZqkYEwxVo1zk=; b=vyAZGLuQJaP6UmPU/5OivZeIeCWgYHlNvqLsuh7U3yYJqNwBg3VduUAZbxG7Wh6UWt vR9hiusZOPdTKmpPzcbCdthcVtfAuVWCA/M8pStelbzfHpRETEdtgYoVIO74pLVcS5Aj PDux1c/zr+9UcdqYc/u8vkoVsM0YeYHd9+PtmsdPd6I9nLItOy76IJT1irNZ7ZvnLPOp Awz0G6XV3jDbzYKy0ICsWxla4idyK6XrPywrZoHibV+ewA3guRirwYmw7BYI3lR697k/ 6y0spqBrB465HxukOz7+BvekqO5c7tmGdGe9sOFhPb3/TuqkcTuslnkiueSXTjL7kZ2a Exew== 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=SpMt9swBFV/X7pJxY11yJxvoU/jl5TYZqkYEwxVo1zk=; b=IT8QDTP1e0YpjKxRed1LY2jCSrvX63CvVZWqhTzDgYqSnVnSFjpkk9rKwT5xB6+HC+ RT9m6VzwegNqSho1574q1vN6dC9gXyAItLzIqa4OMtgkpcidNlDNkHZPKoXA6VGYx1rt JPv9z/oVFDxsJDdaqLpUIZPQADSetGUizEgAaeu7sCKH0tWO9OlE/fjV4Yr2tZEpsYKX GUAvcIwvzJx4ENlDZiT9waM+iXfomRaDTFXcQVM/3+27bU+4m9OOC/1j1YDHFOrZopS+ UxOmuwm0VEopqkkVLVZnGYo4jxm7Cb04efq67TlhKBhGZQecWA9CmoXlzKsU4BNNst60 HpXw== X-Gm-Message-State: APjAAAWg2rL4Atr29D+WNwX6faGyEdCDnDkH4GeFI8chbmwy4kUv2nlA HmWmRU0v5TI0n0rH5RItYW+I6+hkyPQqagWXUkQy0Q== X-Google-Smtp-Source: APXvYqw74Dsa5tbwvZVY6ubm3mq6Ol0GpZBf3HyKWvRWHEbC8fAxc8l0X7gBK5dChGcDSWL/yjwxE6D5ZDxmwT29ntI= X-Received: by 2002:a67:ed8b:: with SMTP id d11mr3309159vsp.104.1572543748924; Thu, 31 Oct 2019 10:42:28 -0700 (PDT) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191031164637.48901-1-samitolvanen@google.com> <20191031164637.48901-14-samitolvanen@google.com> In-Reply-To: From: Sami Tolvanen Date: Thu, 31 Oct 2019 10:42:17 -0700 Message-ID: Subject: Re: [PATCH v3 13/17] arm64: preserve x18 when CPU is suspended To: Nick Desaulniers Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Dave Martin , Kees Cook , Laura Abbott , Mark Rutland , Jann Horn , Miguel Ojeda , Masahiro Yamada , 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 Thu, Oct 31, 2019 at 10:35 AM Nick Desaulniers wrote: > > On Thu, Oct 31, 2019 at 10:27 AM Sami Tolvanen wrote: > > > > On Thu, Oct 31, 2019 at 10:18 AM Nick Desaulniers > > wrote: > > > > +#ifdef CONFIG_SHADOW_CALL_STACK > > > > + ldr x18, [x0, #96] > > > > + str xzr, [x0, #96] > > > > > > How come we zero out x0+#96, but not for other offsets? Is this str necessary? > > > > It clears the shadow stack pointer from the sleep state buffer, which > > is not strictly speaking necessary, but leaves one fewer place to find > > it. > > That sounds like a good idea. Consider adding comments or to the > commit message so that the str doesn't get removed accidentally in the > future. Sure, I'll add a comment in the next version. Sami