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=-8.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 B9A2EC352A3 for ; Mon, 10 Feb 2020 16:41:47 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8D15920838 for ; Mon, 10 Feb 2020 16:41:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="JdbRPmn/"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="xZ9yor3P" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8D15920838 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=UBUPsISjmWy8hae/Lgafg6ou9zXIDTCq7CDKlVp7LXI=; b=JdbRPmn//qhyIz y2rIvfUm0WFmExxKRdQeF91yKygoDVGvo7YmQaViraShOrb45aI8nCFpR+/fU+K9LHUglUmWHIMzi ctPh5yBl+NdM4ZrjxrY/QyVqghIuXvDQzNnnxIcjs6UqDRVIVzGHaC3jUmhHPDZab59G4iFnOm7wP VAhgy+eurMPfRPBze8BRpuX4fKm3PNWAqtmUpvBa1pDbw1CF6UwimVXUZOi3A1mp+3toi63L1IYBW tEsxCA4TXhuPpZBnffGJEDLFvA3EqdzxNcpVPgzS4uGPtVi03oFipLhYJkJo+Otz6ix+6YclNjrUk yKZ59XpojdEdXUiAAeLg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j1C7x-0005no-5F; Mon, 10 Feb 2020 16:41:41 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1j1C7u-0005nV-KZ for linux-arm-kernel@lists.infradead.org; Mon, 10 Feb 2020 16:41:39 +0000 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3926920733; Mon, 10 Feb 2020 16:41:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581352898; bh=swgRA1rNS8tBiz0g1uvNqRf9FaXIwO8m18YRqWdGIWU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=xZ9yor3PmK0g2VGI7TH5dURt6qVd/7JoQzVJWSGzhMpbis9o4lzC+9ygWQ0663Ml8 mNsCjyu4UABSsLLe5Ja4m3XnHu6ZdABdFV/OZcz8udClXlNzbDXjPXG7WWBZAvWWNt S1LX2V8l6/MoP4lkNDVfdgj8iQdTmKUYem8h+bsE= Date: Mon, 10 Feb 2020 16:41:32 +0000 From: Will Deacon To: Sami Tolvanen Subject: Re: [PATCH v7 07/11] arm64: efi: restore x18 if it was corrupted Message-ID: <20200210164131.GB21900@willie-the-truck> References: <20191018161033.261971-1-samitolvanen@google.com> <20200128184934.77625-1-samitolvanen@google.com> <20200128184934.77625-8-samitolvanen@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200128184934.77625-8-samitolvanen@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200210_084138_695443_1A2099F1 X-CRM114-Status: GOOD ( 16.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Kees Cook , Ard Biesheuvel , Masahiro Yamada , Catalin Marinas , Jann Horn , Nick Desaulniers , linux-kernel@vger.kernel.org, Steven Rostedt , Miguel Ojeda , clang-built-linux@googlegroups.com, james.morse@arm.com, Masami Hiramatsu , Marc Zyngier , kernel-hardening@lists.openwall.com, Laura Abbott , Dave Martin , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jan 28, 2020 at 10:49:30AM -0800, Sami Tolvanen wrote: > If we detect a corrupted x18, restore the register before jumping back > to potentially SCS instrumented code. This is safe, because the wrapper > is called with preemption disabled and a separate shadow stack is used > for interrupt handling. > > Signed-off-by: Sami Tolvanen > Reviewed-by: Kees Cook > --- > arch/arm64/kernel/efi-rt-wrapper.S | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S > index 3fc71106cb2b..6ca6c0dc11a1 100644 > --- a/arch/arm64/kernel/efi-rt-wrapper.S > +++ b/arch/arm64/kernel/efi-rt-wrapper.S > @@ -34,5 +34,14 @@ ENTRY(__efi_rt_asm_wrapper) > ldp x29, x30, [sp], #32 > b.ne 0f > ret > -0: b efi_handle_corrupted_x18 // tail call > +0: > + /* > + * With CONFIG_SHADOW_CALL_STACK, the kernel uses x18 to store a > + * shadow stack pointer, which we need to restore before returning to > + * potentially instrumented code. This is safe because the wrapper is > + * called with preemption disabled and a separate shadow stack is used > + * for interrupts. > + */ > + mov x18, x2 > + b efi_handle_corrupted_x18 // tail call > ENDPROC(__efi_rt_asm_wrapper) Acked-by: Will Deacon Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel