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 9045FC678DF for ; Wed, 4 Jan 2023 16:13:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235365AbjADQNy (ORCPT ); Wed, 4 Jan 2023 11:13:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36342 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239835AbjADQNb (ORCPT ); Wed, 4 Jan 2023 11:13:31 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 9E397E2C; Wed, 4 Jan 2023 08:13:30 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1E07E165C; Wed, 4 Jan 2023 08:14:12 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.37.146]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E6AA63F71A; Wed, 4 Jan 2023 08:13:28 -0800 (PST) Date: Wed, 4 Jan 2023 16:13:22 +0000 From: Mark Rutland To: Ard Biesheuvel Cc: Lee Jones , stable@vger.kernel.org, linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, will@kernel.org, catalin.marinas@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 02:56:19PM +0100, 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. Hold on, why did this go into mainline when I had an outstanding comment w.r.t. the stack unwinder? >From your last reply to me there I was expecting a respin with that fixed. Mark.