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 86B8EC77B61 for ; Fri, 28 Apr 2023 11:49:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345500AbjD1LtE (ORCPT ); Fri, 28 Apr 2023 07:49:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41656 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229682AbjD1Ls6 (ORCPT ); Fri, 28 Apr 2023 07:48:58 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id E59672713 for ; Fri, 28 Apr 2023 04:48:55 -0700 (PDT) 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 8361EC14; Fri, 28 Apr 2023 04:49:39 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.21.9]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1C2113F5A1; Fri, 28 Apr 2023 04:48:53 -0700 (PDT) Date: Fri, 28 Apr 2023 12:48:47 +0100 From: Mark Rutland To: Ard Biesheuvel Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon , Marc Zyngier , Ryan Roberts , Anshuman Khandual , Kees Cook Subject: Re: [PATCH v3 01/60] arm64: kernel: Disable latent_entropy GCC plugin in early C runtime Message-ID: References: <20230307140522.2311461-1-ardb@kernel.org> <20230307140522.2311461-2-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-kernel@vger.kernel.org On Fri, Apr 28, 2023 at 11:54:16AM +0100, Ard Biesheuvel wrote: > On Fri, 28 Apr 2023 at 11:38, Mark Rutland wrote: > > > > On Tue, Mar 07, 2023 at 03:04:23PM +0100, Ard Biesheuvel wrote: > > > Avoid build issues in the early C code related to the latent_entropy GCC > > > plugin, by incorporating the C flags fragment that disables it. > > > > > > Signed-off-by: Ard Biesheuvel > > > > Just to check, are you seeing issues today? IIUC the plugin only instruments > > functions which are explicitly marked with __latent_entropy, and if we're > > seeing that happen unexpectedly (or due to that being applying to __meminit / > > __init), we might need to do likewise for other noinstr code. > > > > I don't quite remember, tbh, but it is unlikely that I would have > written or included this patch without having run into some actual > issue. Sure. Looking at the series, from patch 15 onwards you mark portions of the PI code as __init. As __init currently implies __latent_entropy (which I think is a bit crazy as of itself...), that's why this'll start to fail. It would be nice if we could mention that in the commit message, e.g. | In subsequent patches we'll mark portions of the early C code as __init. | Unfortunarely, __init implies __latent_entropy, and this would result in the | early C code being instrumented in an unsafe manner. | | Disable the latent entropy plugin for the early C code. ... though my ack stands regardless of whether we add such wording. Mark. > > Regardless, for this patch: > > > > Acked-by: Mark Rutland > > > > Thanks,