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 X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F180C433DF for ; Tue, 26 May 2020 13:07:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6CE722084C for ; Tue, 26 May 2020 13:07:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729628AbgEZNHQ (ORCPT ); Tue, 26 May 2020 09:07:16 -0400 Received: from elvis.franken.de ([193.175.24.41]:39894 "EHLO elvis.franken.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728061AbgEZNHP (ORCPT ); Tue, 26 May 2020 09:07:15 -0400 Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1jdZIW-00088o-01; Tue, 26 May 2020 15:07:12 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id ACC34C041A; Tue, 26 May 2020 15:04:41 +0200 (CEST) Date: Tue, 26 May 2020 15:04:41 +0200 From: Thomas Bogendoerfer To: yuanjunqing Cc: paulburton@kernel.org, chenhc@lemote.com, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, liulichao@loongson.cn Subject: Re: [PATCH] MIPS: Fix IRQ tracing when call handle_fpe() Message-ID: <20200526130441.GB8487@alpha.franken.de> References: <20200525033123.13114-1-yuanjunqing66@163.com> <20200525084234.GA5057@alpha.franken.de> <76f2c756-0ae4-83f5-becf-6f1b3319f6fd@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <76f2c756-0ae4-83f5-becf-6f1b3319f6fd@163.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 26, 2020 at 03:07:16PM +0800, yuanjunqing wrote: > > 在 2020/5/25 下午4:42, Thomas Bogendoerfer 写道: > > On Mon, May 25, 2020 at 11:31:23AM +0800, YuanJunQing wrote: > >> Register "a1" is unsaved in this function, > >> when CONFIG_TRACE_IRQFLAGS is enabled, > >> the TRACE_IRQS_OFF macro will call trace_hardirqs_off(), > >> and this may change register "a1". > >> The variment of register "a1" may send SIGFPE signal > >> to task when call do_fpe(),and this may kill the task. > >> > >> Signed-off-by: YuanJunQing > >> --- > >> arch/mips/kernel/genex.S | 6 ++++-- > >> 1 file changed, 4 insertions(+), 2 deletions(-) > >> > >> diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S > >> index 8236fb291e3f..956a76429773 100644 > >> --- a/arch/mips/kernel/genex.S > >> +++ b/arch/mips/kernel/genex.S > >> @@ -480,16 +480,18 @@ NESTED(nmi_handler, PT_SIZE, sp) > >> /* gas fails to assemble cfc1 for some archs (octeon).*/ \ > >> .set mips1 > >> SET_HARDFLOAT > >> - cfc1 a1, fcr31 > >> + cfc1 s0, fcr31 > >> .set pop > >> CLI > >> TRACE_IRQS_OFF > >> + move a1,s0 > >> .endm > > do we realy need to read fcr31 that early ? Wouldn't it work to > > just move the cfc1 below TRACE_IRQS_OFF ? > > > > yes, it can work when we just move the cfc1 below TRACE_IRQS_OFF, >  and the code is written as follows. > > CLI > TRACE_IRQS_OFF > .set mips1 > SET_HARDFLOAT > cfc1 a1, fcr31 > .set pop >   .endm good, could we do the same with _cfcmsa a1, MSA_CSR in the msa case ? Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]