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 C354FCA9ECB for ; Thu, 31 Oct 2019 17:27:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 921F420650 for ; Thu, 31 Oct 2019 17:27:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="uKrGepNX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728973AbfJaR1k (ORCPT ); Thu, 31 Oct 2019 13:27:40 -0400 Received: from mail-ua1-f65.google.com ([209.85.222.65]:46748 "EHLO mail-ua1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728561AbfJaR1k (ORCPT ); Thu, 31 Oct 2019 13:27:40 -0400 Received: by mail-ua1-f65.google.com with SMTP id i31so659973uae.13 for ; Thu, 31 Oct 2019 10:27:39 -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=46AmydREw6SfU27IOaxxeyDyoZWG9jeVi2WIEFhrMqA=; b=uKrGepNXzPXDPzJbvbemKuf7R6S5LOyd1Myup06RKzLSP2nrNd0gQdYUKo5Mow3DAS +SE7IfD6gsDwY0qy8BSl0pYU8GPWYV87yKCwXeFmUj8tfcvjCxE6XCZvWViSX7BLJr2h JeRICf0gxuCWKgnMwiCuZSLMzerlDUIsThoYOFbNVmV4Iio6o99JIWYLgpdzR7oI4BDx tISF+YHwsfL5BB8DS6m0YqBcFdYRIfZsqtAtZCMGUCUGgOjGgmE4qf5gvZ9MBWNon0hF l2JKhPx8hF2es29OTb38GxXTjoyqOeNJvDE0LRnzacnT1nPR0db8A8Us17QUjMd2B+Rn jUDw== 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=46AmydREw6SfU27IOaxxeyDyoZWG9jeVi2WIEFhrMqA=; b=lT2dbtZ6ORTh+rlD71NXXNgjr2olUht7e6XZSwCVcBCax/NSuyQVghcu1b+jqZs2B/ yZw7X+CHzLb1ihr12axohwTjgiTsSYphjQkGCfsDCW5u8cgqtMJO2QCJvwpmaMnT3vny qi8PhR9VXutB2yBDV6XIIXQ9V81pocM+XrPorgWRGcQkt56EJ0t2C//PVY8juUf5j/e9 lWUk9CTpx2rI2oHZpEK56g1GD2VGZ+HSPRg+cfiqhdGMMGt0s47HpR4ov+0g3GjcmUf9 LhEPw+/W0zNkOI40PFlNmbd+OJTsXXC0n8p1mPrYWA2E6IsfrkqgXDAU99N8aziAdL8n bbcg== X-Gm-Message-State: APjAAAXhrilFQwnygwXWMcDj5FlP28osF3YUq419H4g+/EuwpOZrCCHb w3SnovP/u4CaHhdc03m1k+6skNC5zJOcRCxqlCIRbw== X-Google-Smtp-Source: APXvYqwHBpr5C3UNKE6XLzBUe1Jy/aZ4Jd12qOfI93i2wDsaUH2oAUrgK4KH1mAvPJ/zcWPVngS0f/6vsb1FU+PAYk8= X-Received: by 2002:a9f:3772:: with SMTP id a47mr3382097uae.53.1572542858440; Thu, 31 Oct 2019 10:27:38 -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 10:27:26 -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 10:18 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. Sami