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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 5F94CCA9EC9 for ; Fri, 1 Nov 2019 03:59:51 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id AA242208CB for ; Fri, 1 Nov 2019 03:59:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="LILcQjVb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AA242208CB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17220-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 1736 invoked by uid 550); 1 Nov 2019 03:59:45 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 1712 invoked from network); 1 Nov 2019 03:59:44 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=jWbfirm5A7lClilm5TrxMUwFVETsZ0QZ3dgXNGgwJk0=; b=LILcQjVb+J77OLR0Wqh8wnQrNbg/1wbjTbvcWvcASlmFUoRhF+FiABYaQL4F6fbQbF uxzeSY91YoL9miij3Kit1NzjdfNC1KqoUlTChwS9qCXgWIlOVwAzcIYT52gA3K2PVO/8 zI4nwynvLe0KA4Pq1Usu8zAit0zL/9zkfYAew= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=jWbfirm5A7lClilm5TrxMUwFVETsZ0QZ3dgXNGgwJk0=; b=GfYHrILE1r8yttPpk0kwlj+sgBP8RjvOrHfHji5uPjHnL6Slml51eH/OBB7IWoKajs HIpkM4cB/xIJehceU7q/YEcp3WI/dFo63YfZHXkJEMvdod852ICQE0uKKJ8Ec2AeHm6S e05fSWYUBJyF6uVd8t4qjW0oloPenlKCWnqnacBgXw4c3lZmDFSSocUGnNs4qEwwxZEB jUireutr3BeTnT+gflQc75UJXjViv3kMi4PZ2vftSD59mp+dzDsVjrjWERkdG9cUC1zi 5bXI3l+y7w1mgmg+Gb6OeFg4+mb4dYY60s0YhfDLhpoKZyE/oKB3Oao6aCEUiUkTlXnx 560w== X-Gm-Message-State: APjAAAXhLJEtzUuXs0uL0ABcgu+xlN8cg/zK7PfF0E1C8bAAKgj+TqCB ABrma7WxnfrDJXz9SAY7XYPDwg== X-Google-Smtp-Source: APXvYqy5NPe898RXSU+w1c0UaOFby31e22ngkYRTC9hJdLIA+7oZafTpdC/J3+7KdM9QjpM8htFvPw== X-Received: by 2002:a63:ee48:: with SMTP id n8mr11288858pgk.374.1572580772699; Thu, 31 Oct 2019 20:59:32 -0700 (PDT) Date: Thu, 31 Oct 2019 20:59:30 -0700 From: Kees Cook To: Nick Desaulniers Cc: Sami Tolvanen , Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Dave Martin , Laura Abbott , Mark Rutland , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux , Kernel Hardening , Linux ARM , LKML Subject: Re: [PATCH v3 13/17] arm64: preserve x18 when CPU is suspended Message-ID: <201910312059.59F983B@keescook> References: <20191018161033.261971-1-samitolvanen@google.com> <20191031164637.48901-1-samitolvanen@google.com> <20191031164637.48901-14-samitolvanen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Oct 31, 2019 at 10:34:53AM -0700, 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. > Reviewed-by: Nick Desaulniers Yeah, with the comment added: Reviewed-by: Kees Cook -Kees -- Kees Cook