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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,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 EAE04C76186 for ; Wed, 17 Jul 2019 08:12:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B80DA2077C for ; Wed, 17 Jul 2019 08:12:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="s80NVPKz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726135AbfGQIMT (ORCPT ); Wed, 17 Jul 2019 04:12:19 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:53136 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725799AbfGQIMT (ORCPT ); Wed, 17 Jul 2019 04:12:19 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x6H89Csd029424; Wed, 17 Jul 2019 08:11:25 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=mpjya3Lap+ZyvSIITTGtisS8qHruXjjl3vkeQTXCh/A=; b=s80NVPKzItHCxLnLJU4/xUQ99WKWLt2cg/r1U7tWkUeuJs5xpfHmHRcBOjOfCwOUq0va P/1fKVUh/eLT/pv2gYEapFBFwMzFgObROFks2had3y7dSdgRR8mSbhsg9ip2amW2FppS DquGBMlJyGb/UU/AJ9mXbDr6gbdG9GbQ38ZiPU1ZyjBcU/OFIP5um89zITBil+uOejZF oSHCYAAuW40xP6r7J9kOvI0u7jTWZhqwbwqIrhWiOI4oXVKq9bHMk23JKwGVobd7BJss UT2ernRLTvqH3dSXGro1/LWfjNMSLBVPXQYI1iOduGfgEYN0uJAjsBwLTWbcevUuWGk4 Pw== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by aserp2120.oracle.com with ESMTP id 2tq78ps04v-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 17 Jul 2019 08:11:25 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x6H87isD117366; Wed, 17 Jul 2019 08:11:24 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3020.oracle.com with ESMTP id 2tsmcc8rcy-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 17 Jul 2019 08:11:24 +0000 Received: from abhmp0005.oracle.com (abhmp0005.oracle.com [141.146.116.11]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x6H8BLuA009883; Wed, 17 Jul 2019 08:11:21 GMT Received: from [10.175.27.185] (/10.175.27.185) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 17 Jul 2019 08:11:21 +0000 Subject: Re: [PATCH v3 0/6] Tracing vs CR2 To: Peter Zijlstra Cc: tglx@linutronix.de, bp@alien8.de, mingo@kernel.org, rostedt@goodmis.org, luto@kernel.org, torvalds@linux-foundation.org, hpa@zytor.com, dave.hansen@linux.intel.com, jgross@suse.com, linux-kernel@vger.kernel.org, zhe.he@windriver.com, joel@joelfernandes.org, devel@etsukata.com References: <20190711114054.406765395@infradead.org> <4c71e14d-3a32-c3bb-8e3b-6e5100853192@oracle.com> <20190717080725.GK3402@hirez.programming.kicks-ass.net> From: Vegard Nossum Message-ID: Date: Wed, 17 Jul 2019 10:09:45 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190717080725.GK3402@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9320 signatures=668688 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=944 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907170097 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9320 signatures=668688 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=995 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907170097 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/17/19 10:07 AM, Peter Zijlstra wrote: > On Tue, Jul 16, 2019 at 09:33:50PM +0200, Vegard Nossum wrote: >> ------------[ cut here ]------------ >> General protection fault in user access. Non-canonical address? >> WARNING: CPU: 0 PID: 5039 at arch/x86/mm/extable.c:126 >> ex_handler_uaccess+0x5d/0x70 [...] > > > https://lkml.kernel.org/r/57754f11-2c65-a2c8-2f6d-bfab0d2f8b53@etsukata.com > > Does something like the below help? > > diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c > index c8d0f05721a1..80ad4ccb7025 100644 > --- a/kernel/stacktrace.c > +++ b/kernel/stacktrace.c > @@ -226,12 +226,16 @@ unsigned int stack_trace_save_user(unsigned long *store, unsigned int size) > .store = store, > .size = size, > }; > + mm_segment_t fs; > > /* Trace user stack if not a kernel thread */ > if (current->flags & PF_KTHREAD) > return 0; > > + fs = get_fs(); > + set_fs(USER_DS); > arch_stack_walk_user(consume_entry, &c, task_pt_regs(current)); > + set_fs(fs); > return c.len; > } > #endif > Yes. Vegard