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 EFFAFC25B4E for ; Sun, 22 Jan 2023 13:48:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229863AbjAVNso (ORCPT ); Sun, 22 Jan 2023 08:48:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55920 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229749AbjAVNsm (ORCPT ); Sun, 22 Jan 2023 08:48:42 -0500 Received: from out4-smtp.messagingengine.com (out4-smtp.messagingengine.com [66.111.4.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A1C194; Sun, 22 Jan 2023 05:48:41 -0800 (PST) Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailout.nyi.internal (Postfix) with ESMTP id C691F5C00C4; Sun, 22 Jan 2023 08:48:38 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute2.internal (MEProxy); Sun, 22 Jan 2023 08:48:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kroah.com; h=cc :cc:content-type:date:date:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to; s=fm3; t=1674395318; x=1674481718; bh=G6Tmbr8jJi ekEMSLf/7eP5hUcSQKeQ34idx3MZC2d/w=; b=JYFfCQrKisVdRrPZz7Kyk8Z9yk qT/7HN/eqwv4s7gE/7/CiUmyysAMGuqcnuLZ9nuEng/dhu6IC9llA4Sh4+WZdgT7 CXwC5Rp1lChn260SLl20zjMOF0q4bmy2+sQIuNY4iWwaS/FCEHVuXdbR1wO0eRJ1 DrAMzQ8LyJCbE2ygvsqNLNEF+hB3wM+l97h7YjbMpjVDxCCvZtDmo5c5Yw6SNtss NoqIH4iRQiNn72wuHDBi/aBgzWEJnVgJbHDQvu9G4x9tpFvMSzPRi+lgU4SSAZ3Q PLxztj3qBDBrOL9G1sFeK+QLCXAaL4BJwv2ugoh0pLQ1SSxdeIJPCKYm48lQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:date:date:feedback-id :feedback-id:from:from:in-reply-to:in-reply-to:message-id :mime-version:references:reply-to:sender:subject:subject:to:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm3; t=1674395318; x=1674481718; bh=G6Tmbr8jJiekEMSLf/7eP5hUcSQK eQ34idx3MZC2d/w=; b=MAUx8A7xuxLYgp9LNcxbtmHGGTweeXjmydnOoS8HcubH LqJR6zyObcHVBEt0UpvFFqNCcItb5tSdU7NarBPb5eMEJKb1w7wBWCV8/+e0z+Pu MJv0+QIoAFcCa4aTkoXcDiNR0zo+mWu7wdsXWaJM7pJNNShzucAd8QxRL0Q1XyD4 m8GEQYDWCIG41Gy5fYCvnRvRKu8nCfUrmuDhM/eZTUys+HGUvdY+4PGzQPz4/yf5 rzlETK0yH33QGLTI7c+Tm2bprCk4J8pkLDkd0EJ7Z4qJWWrG10JTfHsaVxTaeuO1 Rte1XQg4v8P4iu41L4YMJZRWVaepkxSC7TA+SmUTmA== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrudduiedgheekucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvfevuffkfhggtggujgesthdtredttddtvdenucfhrhhomhepifhrvghg ucfmjfcuoehgrhgvgheskhhrohgrhhdrtghomheqnecuggftrfgrthhtvghrnhepgeehue ehgfdtledutdelkeefgeejteegieekheefudeiffdvudeffeelvedttddvnecuffhomhgr ihhnpehkvghrnhgvlhdrohhrghenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmh epmhgrihhlfhhrohhmpehgrhgvgheskhhrohgrhhdrtghomh X-ME-Proxy: Feedback-ID: i787e41f1:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sun, 22 Jan 2023 08:48:37 -0500 (EST) Date: Sun, 22 Jan 2023 14:48:35 +0100 From: Greg KH To: Lee Jones Cc: Ard Biesheuvel , Mark Rutland , 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 Tue, Jan 17, 2023 at 04:56:19PM +0000, Lee Jones wrote: > On Thu, 05 Jan 2023, Greg KH wrote: > > > On Wed, Jan 04, 2023 at 05:32:18PM +0100, Ard Biesheuvel wrote: > > > On Wed, 4 Jan 2023 at 17:30, Mark Rutland wrote: > > > > > > > > On Wed, Jan 04, 2023 at 05:15:34PM +0100, Ard Biesheuvel wrote: > > > > > On Wed, 4 Jan 2023 at 17:13, Mark Rutland wrote: > > > > > > > > > > > > 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. > > > > > > > > > > > > > > > > Apologies for the confusion. > > > > > > > > > > I have a patch for this queued up, but AIUI, that cannot be merged all > > > > > the way back to v5.10, so these need to remain separate changes in any > > > > > case. > > > > > > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=c2530a04a73e6b75ed71ed14d09d7b42d6300013 > > > > > > > > Ah, ok, thanks for the pointer! > > > > > > > > I'm a little uneasy here, still. > > > > > > > > By backporting this we're also backporting the new breakage of the stack > > > > unwinder, and the minimal change for backports would be to add the lock and not > > > > the new stack (which was added for additinoal robustness, not to fix the bug > > > > the lock fixes). > > > > > > > > I do appreciate that the additional stack is likely more useful than the > > > > occasional diagnostic output from the kernel, but it does seem like this has > > > > traded off one bug for another, and I'm just a little annoyed because I pointed > > > > that out before the first pull request was made. > > > > > > > > I do know that this isn't malicious, and I'm not trying to start a fight, but > > > > now we have to consider whether we want/need to backport a stack unwinder fix > > > > to account for this, and we hadn't had that discussion before. > > > > > > > > > > In that case, let's drop these backports for the time being, and > > > collaborate on a solution that works for all of us. > > > > > > Greg, could you please drop these again? Thanks. > > > > Dropped now from all queues, thanks. > > Now in Mainline as: > > 18bba1843fc7f efi: rt-wrapper: Add missing include > ff7a167961d1b arm64: efi: Execute runtime services from a dedicated stack > > Would you be kind enough to re-collect them please? Now queued up for 5.10.y and newer. greg k-h