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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7585CC4708E for ; Wed, 4 Jan 2023 14:55:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235134AbjADOz5 (ORCPT ); Wed, 4 Jan 2023 09:55:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44816 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236020AbjADOzr (ORCPT ); Wed, 4 Jan 2023 09:55:47 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F9DB1EACF; Wed, 4 Jan 2023 06:55:46 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1A6BC6175D; Wed, 4 Jan 2023 14:55:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0EC0CC433F0; Wed, 4 Jan 2023 14:55:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672844145; bh=4+asDLO/hYiXl7igLLqD39zSJqLFzA//VD+dBoT82RE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MEzGd3QPx4I0elS9qkY+UUdwE8Bj+DFo7YGz7kmoCOe6nq3MV5CjGkUp5TilfTICW v6bXJNij4kqeJVUvbquVM32d5qvCMH0sBjO7FHMjY/NkKB0UTpkigZJZzrKU7BoPL7 5DPPEZ6cOHTp7ufAFHJkAt9uj1d3RJxmv8EW/FWU= Date: Wed, 4 Jan 2023 15:52:03 +0100 From: Greg KH To: Lee Jones Cc: Ard Biesheuvel , stable@vger.kernel.org, linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, Sami Tolvanen , Kees Cook Subject: Re: [PATCH 1/2] arm64: efi: Execute runtime services from a dedicated stack Message-ID: References: <20221205201210.463781-1-ardb@kernel.org> <20221205201210.463781-2-ardb@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org On Wed, Jan 04, 2023 at 02:42:30PM +0000, Lee Jones wrote: > On Wed, 04 Jan 2023, Ard Biesheuvel wrote: > > > On Wed, 4 Jan 2023 at 11:40, Lee Jones wrote: > > > > > > On Mon, 05 Dec 2022, Ard Biesheuvel wrote: > > > > > > > With the introduction of PRMT in the ACPI subsystem, the EFI rts > > > > workqueue is no longer the only caller of efi_call_virt_pointer() in the > > > > kernel. This means the EFI runtime services lock is no longer sufficient > > > > to manage concurrent calls into firmware, but also that firmware calls > > > > may occur that are not marshalled via the workqueue mechanism, but > > > > originate directly from the caller context. > > > > > > > > For added robustness, and to ensure that the runtime services have 8 KiB > > > > of stack space available as per the EFI spec, introduce a spinlock > > > > protected EFI runtime stack of 8 KiB, where the spinlock also ensures > > > > serialization between the EFI rts workqueue (which itself serializes EFI > > > > runtime calls) and other callers of efi_call_virt_pointer(). > > > > > > > > While at it, use the stack pivot to avoid reloading the shadow call > > > > stack pointer from the ordinary stack, as doing so could produce a > > > > gadget to defeat it. > > > > > > > > Signed-off-by: Ard Biesheuvel > > > > --- > > > > arch/arm64/include/asm/efi.h | 3 +++ > > > > arch/arm64/kernel/efi-rt-wrapper.S | 13 +++++++++- > > > > arch/arm64/kernel/efi.c | 25 ++++++++++++++++++++ > > > > 3 files changed, 40 insertions(+), 1 deletion(-) > > > > > > Could we have this in Stable please? > > > > > > Upstream commit: ff7a167961d1b ("arm64: efi: Execute runtime services from a dedicated stack") > > > > > > Ard, do we need Patch 2 as well, or can this be applied on its own? > > > > > > > Thanks for the reminder. > > > > Only patch #1 is needed. It should be applied to v5.10 and later. > > Perfect, thanks Ard. Now queued up, thanks. greg k-h