From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759417AbcLPHyF (ORCPT ); Fri, 16 Dec 2016 02:54:05 -0500 Received: from mail-wj0-f194.google.com ([209.85.210.194]:34579 "EHLO mail-wj0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755577AbcLPHx5 (ORCPT ); Fri, 16 Dec 2016 02:53:57 -0500 Subject: Re: default 0 if KASAN expression not working in kbuild To: Randy Dunlap , linux-kbuild@vger.kernel.org References: <18825051-61d0-e8a9-544a-4f7d89f30b3c@infradead.org> Cc: LKML , yann.morin.1998@free.fr, mmarek@suse.com From: Nikolay Borisov Message-ID: <9d39c938-3f52-12f2-c1ae-4e27d9b3a8bd@gmail.com> Date: Fri, 16 Dec 2016 09:53:54 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16.12.2016 09:50, Nikolay Borisov wrote: > > > On 15.12.2016 23:32, Randy Dunlap wrote: >> On 12/15/16 10:09, Nikolay Borisov wrote: >>> Hello, >>> >>> I was doing some kasan-related debugging and when I enabled it I started >>> getting warnings for large stackframes. So CONFIG_FRAME_WARN has : >>> >>> int "Warn for stack frames larger than (needs gcc 4.4)" >>> range 0 8192 >>> default 0 if KASAN >>> default 2048 if GCC_PLUGIN_LATENT_ENTROPY >>> default 1024 if !64BIT >>> default 2048 if 64BIT >>> >>> This means that frame_warns should effectively be disabled when kasan is >>> enabled. However in my case this is not the situation. >>> http://sprunge.us/FiGf here is the config file. It does have >>> CONFIG_KASAN=y and CONFIG_FRAME_WARN=1024 . And even this is erroneous >>> since it's a 64bit kernel, so it should be 2k. I haven't manually set >>> the limit to 1k either. >> >> Yeah, it set FRAME_WARN=1024 for me also. >> >> It seems to be dependent on order of kconfig symbols in >> lib/Kconfig.debug. >> >> If I move the line: >> source "lib/Kconfig.kasan" >> to just after this line: >> menu "Compile-time checks and compiler options" >> it seems to work for me. >> >> Can you test the patch below? > > This patch has another problem that if I move the source line then I no > longer get the kasan option in Memory Debugging section, furthermore the > frame_warn wasn't changed either. So actually kasan is being moved to the "Compile-time checks" menu, yet the frame size still isn't changed for me. > > >>