From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754889AbdBPLwg (ORCPT ); Thu, 16 Feb 2017 06:52:36 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:51456 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754478AbdBPLwe (ORCPT ); Thu, 16 Feb 2017 06:52:34 -0500 Subject: Re: [PATCH] powerpc/xmon: Fix an unexpected xmon onoff state change To: "Guilherme G. Piccoli" , Michael Ellerman , Pan Xinhui , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <1487144990-5969-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> <87shnek9hd.fsf@concordia.ellerman.id.au> <72cfff06-bd93-a727-0b93-31dfa3a7ac65@linux.vnet.ibm.com> Cc: benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com From: Pan Xinhui Date: Thu, 16 Feb 2017 19:51:27 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <72cfff06-bd93-a727-0b93-31dfa3a7ac65@linux.vnet.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17021611-0012-0000-0000-0000021235CE X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17021611-0013-0000-0000-000007008788 Message-Id: <8466dffc-d75c-d83a-2a4f-d567721db7d5@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-02-16_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=2 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1702160119 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2017/2/16 18:57, Guilherme G. Piccoli 写道: > On 16/02/2017 03:09, Michael Ellerman wrote: >> Pan Xinhui writes: >> >>> Once xmon is triggered by sysrq-x, it is enabled always afterwards even >>> if it is disabled during boot. This will cause a system reset interrut >>> fail to dump. So keep xmon in its original state after exit. >>> >>> Signed-off-by: Pan Xinhui >>> --- >>> arch/powerpc/xmon/xmon.c | 5 ++++- >>> 1 file changed, 4 insertions(+), 1 deletion(-) >>> >>> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c >>> index 9c0e17c..721212f 100644 >>> --- a/arch/powerpc/xmon/xmon.c >>> +++ b/arch/powerpc/xmon/xmon.c >>> @@ -76,6 +76,7 @@ static int xmon_gate; >>> #endif /* CONFIG_SMP */ >>> >>> static unsigned long in_xmon __read_mostly = 0; >>> +static int xmon_off = 0; >>> >>> static unsigned long adrs; >>> static int size = 1; >>> @@ -3250,6 +3251,8 @@ static void sysrq_handle_xmon(int key) >>> /* ensure xmon is enabled */ >>> xmon_init(1); >>> debugger(get_irq_regs()); >>> + if (xmon_off) >>> + xmon_init(0); >>> } >> >> I don't think this is right. >> >> xmon_off is only true if you boot with xmon=off on the command line. >> >> So if you boot with CONFIG_XMON_DEFAULT=n, and nothing on the command >> line, then enter xmon via sysrq, then exit, xmon will still be enabled. >> > > Agreed, noticed it after some work in V2 of my patch. I'm addressing it > there, so maybe no harm in keeping this way here.. > Hi, mpe I cooked a new patch. And as Paul mentioned in slack, we need keep xmon on too if xmon=early is set in cmdline. hi, Guilherme feel free to include it in your new patchset. :) thanks xinhui --------patch----- powerpc/xmon: Fix an unexpected xmon onoff state change Once xmon is triggered by sysrq-x, it is enabled always afterwards even if it is disabled during boot. This will cause a system reset interrupt fail to dump. So keep xmon in its original state after exit. We have several ways to set xmon on or off. 1) by a build config CONFIG_XMON_DEFAULT. 2) by a boot cmdline with xmon or xmon=early or xmon=on to enable xmon and xmon=off to disable xmon. This value will override that in step 1. 3) by a debugfs interface. We need someone implement it in the future. And this value can override those in step 1 and 2. Signed-off-by: Pan Xinhui --- arch/powerpc/xmon/xmon.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c index 9c0e17c..f6e5c3d 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -76,6 +76,7 @@ static int xmon_gate; #endif /* CONFIG_SMP */ static unsigned long in_xmon __read_mostly = 0; +static int xmon_off = !IS_ENABLED(CONFIG_XMON_DEFAULT); static unsigned long adrs; static int size = 1; @@ -3250,6 +3251,8 @@ static void sysrq_handle_xmon(int key) /* ensure xmon is enabled */ xmon_init(1); debugger(get_irq_regs()); + if (xmon_off) + xmon_init(0); } static struct sysrq_key_op sysrq_xmon_op = { @@ -3266,16 +3269,16 @@ static int __init setup_xmon_sysrq(void) __initcall(setup_xmon_sysrq); #endif /* CONFIG_MAGIC_SYSRQ */ -static int __initdata xmon_early, xmon_off; +static int __initdata xmon_early; static int __init early_parse_xmon(char *p) { if (!p || strncmp(p, "early", 5) == 0) { /* just "xmon" is equivalent to "xmon=early" */ - xmon_init(1); xmon_early = 1; + xmon_off = 0; } else if (strncmp(p, "on", 2) == 0) - xmon_init(1); + xmon_off = 0; else if (strncmp(p, "off", 3) == 0) xmon_off = 1; else if (strncmp(p, "nobt", 4) == 0) @@ -3289,10 +3292,9 @@ early_param("xmon", early_parse_xmon); void __init xmon_setup(void) { -#ifdef CONFIG_XMON_DEFAULT - if (!xmon_off) - xmon_init(1); -#endif + if (xmon_off) + return; + xmon_init(1); if (xmon_early) debugger(NULL); } -- 2.9.3 > Thanks, > > > Guilherme > > > >> cheers >> >