From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934837AbdAIJ4F (ORCPT ); Mon, 9 Jan 2017 04:56:05 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:46549 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S934800AbdAIJz7 (ORCPT ); Mon, 9 Jan 2017 04:55:59 -0500 Date: Mon, 9 Jan 2017 15:25:23 +0530 From: Vaidyanathan Srinivasan To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Segher Boessenkool , Michael Ellerman , Joel Stanley Subject: Re: [PATCH 4.4 54/58] powerpc: Convert cmp to cmpd in idle enter sequence Reply-To: svaidy@linux.vnet.ibm.com References: <20170106213906.290654840@linuxfoundation.org> <20170106213909.123550674@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20170106213909.123550674@linuxfoundation.org> User-Agent: Mutt/1.7.1 (2016-10-04) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17010909-0024-0000-0000-0000037F8C59 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17010909-0025-0000-0000-000010D370B7 Message-Id: <20170109095523.GA3273@drishya.in.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-01-09_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1701090155 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Greg Kroah-Hartman [2017-01-06 22:44:39]: > 4.4-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Segher Boessenkool > > commit 80f23935cadb1c654e81951f5a8b7ceae0acc1b4 upstream. > > PowerPC's "cmp" instruction has four operands. Normally people write > "cmpw" or "cmpd" for the second cmp operand 0 or 1. But, frequently > people forget, and write "cmp" with just three operands. > > With older binutils this is silently accepted as if this was "cmpw", > while often "cmpd" is wanted. With newer binutils GAS will complain > about this for 64-bit code. For 32-bit code it still silently assumes > "cmpw" is what is meant. > > In this instance the code comes directly from ISA v2.07, including the > cmp, but cmpd is correct. Backport to stable so that new toolchains can > build old kernels. > > Fixes: 948cf67c4726 ("powerpc: Add NAP mode support on Power7 in HV mode") > Reviewed-by: Vaidyanathan Srinivasan > Signed-off-by: Segher Boessenkool > Signed-off-by: Michael Ellerman > Signed-off-by: Joel Stanley > Signed-off-by: Greg Kroah-Hartman Acked-by: Vaidyanathan Srinivasan The change from cmp to cmpd is correct. This code will execute in 64-bit mode only and fix applies to stable as described above. > > > --- > arch/powerpc/kernel/idle_power7.S | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/arch/powerpc/kernel/idle_power7.S > +++ b/arch/powerpc/kernel/idle_power7.S > @@ -44,7 +44,7 @@ > std r0,0(r1); \ > ptesync; \ > ld r0,0(r1); \ > -1: cmp cr0,r0,r0; \ > +1: cmpd cr0,r0,r0; \ > bne 1b; \ > IDLE_INST; \ > b . > >