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 10BE4C4167B for ; Mon, 7 Mar 2022 12:25:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242167AbiCGM0U (ORCPT ); Mon, 7 Mar 2022 07:26:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33792 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242140AbiCGM0T (ORCPT ); Mon, 7 Mar 2022 07:26:19 -0500 Received: from elvis.franken.de (elvis.franken.de [193.175.24.41]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 18DA480926; Mon, 7 Mar 2022 04:25:25 -0800 (PST) Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1nRCQS-00072o-02; Mon, 07 Mar 2022 13:25:20 +0100 Received: by alpha.franken.de (Postfix, from userid 1000) id 4DB79C1280; Mon, 7 Mar 2022 13:21:02 +0100 (CET) Date: Mon, 7 Mar 2022 13:21:02 +0100 From: Thomas Bogendoerfer To: "Maciej W. Rozycki" Cc: Jan-Benedict Glaw , Sudip Mukherjee , Ralf Baechle , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] DEC: Limit PMAX memory probing to R3k systems Message-ID: <20220307122102.GC14422@alpha.franken.de> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Fri, Mar 04, 2022 at 08:16:23PM +0000, Maciej W. Rozycki wrote: > Recent tightening of the opcode table in binutils so as to consistently > disallow the assembly or disassembly of CP0 instructions not supported > by the processor architecture chosen has caused a regression like below: > > arch/mips/dec/prom/locore.S: Assembler messages: > arch/mips/dec/prom/locore.S:29: Error: opcode not supported on this processor: r4600 (mips3) `rfe' > > in a piece of code used to probe for memory with PMAX DECstation models, > which have non-REX firmware. Those computers always have an R2000 CPU > and consequently the exception handler used in memory probing uses the > RFE instruction, which those processors use. > > While adding 64-bit support this code was correctly excluded for 64-bit > configurations, however it should have also been excluded for irrelevant > 32-bit configurations. Do this now then, and only enable PMAX memory > probing for R3k systems. > > Reported-by: Jan-Benedict Glaw > Reported-by: Sudip Mukherjee > Signed-off-by: Maciej W. Rozycki > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Cc: stable@vger.kernel.org # v2.6.12+ > --- > Hi, > > I'm assuming this won't go back beyond commit 2a11c8ea20bf ("kconfig: > Introduce IS_ENABLED(), IS_BUILTIN() and IS_MODULE()") or any backport > will have to be rewritten to avoid IS_ENABLED. > > The original actual change named to fix ought to be commit dd82ef87e4c9 > ("PROM interface rework to support a 64-bit kernel.") from the LMO repo: > , > which introduced the `prom_is_rex' macro, which guards this code. Said > commit predates the history of our main repository though. > > This change has actually been verified at runtime with a PMIN system > (effectively a PMAX, but with a slower R2000 CPU) and a 4MAX+ system (an > R4400SC-based machine), and naturally throughout the three possible build > configurations: R3k, R4k/32-bit, R4k/64-bit. > > It took longer than expected, but oh well... Sorry for the inconvenience > caused. > > Please apply, > > Maciej > --- > arch/mips/dec/prom/Makefile | 2 +- > arch/mips/include/asm/dec/prom.h | 15 +++++---------- > 2 files changed, 6 insertions(+), 11 deletions(-) applied to mips-next. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]