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 5333DC33CAF for ; Thu, 16 Jan 2020 21:58:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1EDDE20728 for ; Thu, 16 Jan 2020 21:58:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="VNVb2CG8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388251AbgAPV6G (ORCPT ); Thu, 16 Jan 2020 16:58:06 -0500 Received: from mail-vs1-f67.google.com ([209.85.217.67]:34361 "EHLO mail-vs1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729380AbgAPV6G (ORCPT ); Thu, 16 Jan 2020 16:58:06 -0500 Received: by mail-vs1-f67.google.com with SMTP id g15so13691680vsf.1 for ; Thu, 16 Jan 2020 13:58:05 -0800 (PST) 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=90kSKrsPpbCluN0U4RDiVNxyzvDrsXuzgr4VAEgKFuc=; b=VNVb2CG8c3HkjMqddLo98y3OPZa+WSPTAgoYdSf7FbWI5WNi3wnlLK0p32BzwbDJkl DxW3dVwqqXEzvQDJ/t2t8XVh7UcdBnxl57fQBAwB07GY+Kc5s2di8Ti7bcTy/S2/pe8U ishyY7KqIu0u9X9VZYcJD0ArT3LnkwpSs93Icdin/XOuAUh49RrudpoY+q52GTTYSx40 GpnMdqP6bRbODHeQRjbKNwwaXhmlW1mB68/yoKkEelegSKWRaD4DkiQa+ct5BY9CQ8b+ WhW5jUQJ1e+6OM3m0IRmGb8dXhOkx9FNog8QbWSOqQkVjep7R9pRuyilDTthUXsbS/HD LriA== 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=90kSKrsPpbCluN0U4RDiVNxyzvDrsXuzgr4VAEgKFuc=; b=KEkNnaUhOKkzLdXcA5i1GVSycc9i45LRPAvjr+qjJzrmWSTEF7m9/sSXS9XDKwKqDm bDcu1UF/MS6VcAJ7jdLhik9v4KeYQH0wux/mc59T8Ig6VZbF8Wnm0u81z4tSNKnmSzg/ Z7M2y7p/0K8g59dvL1950+GMvBuKlcSeM7vBVywVi6ikS5UCvZG98MfvbPHI2+gY0IM8 +hI3z3QMMGdh0zOytrLpuchhTuyZ+p5mxtyIleBQ8AiP8elREM4tE347X9K+5+ihbfn1 678JX6R6WiyZF4PMYnUaXZbImydQk3KyfPCqmsj5gozednWCDlGboNr6Zo9oCTTuE1DM Iw6A== X-Gm-Message-State: APjAAAUaK2LCpOKRi1iXk31gCJK/6V1kw8qSa9/BkEUeRWRepEfBEi5H k6aPW0CG/SckVQH/oAOtXzBNDzYnDRAFBUFt4dQs6w== X-Google-Smtp-Source: APXvYqzrUqH5/W2UZ+FeXG0hZr7Tack1J9k9eB9pBix6w41rOK+OkTqsOrnRDdc5aMPEGFoHQeXxcn/0tewoHbFlgSg= X-Received: by 2002:a67:ae43:: with SMTP id u3mr3413809vsh.44.1579211884786; Thu, 16 Jan 2020 13:58:04 -0800 (PST) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191206221351.38241-1-samitolvanen@google.com> <20191206221351.38241-15-samitolvanen@google.com> <20200116182414.GC22420@willie-the-truck> In-Reply-To: <20200116182414.GC22420@willie-the-truck> From: Sami Tolvanen Date: Thu, 16 Jan 2020 13:57:53 -0800 Message-ID: Subject: Re: [PATCH v6 14/15] arm64: implement Shadow Call Stack To: Will Deacon Cc: Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Mark Rutland , Dave Martin , Kees Cook , Laura Abbott , Marc Zyngier , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux , Kernel Hardening , linux-arm-kernel , 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, Jan 16, 2020 at 10:24 AM Will Deacon wrote: > > .macro irq_stack_entry > > mov x19, sp // preserve the original sp > > +#ifdef CONFIG_SHADOW_CALL_STACK > > + mov x20, x18 // preserve the original shadow stack > > +#endif > > Hmm, not sure about corrupting x20 here. Doesn't it hold the PMR value from > kernel_entry? You're right, and it's used in el1_irq after irq_handler if CONFIG_ARM64_PSEUDO_NMI is enabled. Thanks for pointing this out. Looks like one of x24-x29 should be safe here, and the comment needs to be updated to explain why x20-x23 shouldn't be corrupted. Sami