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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS 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 52FDAC43381 for ; Thu, 21 Feb 2019 10:06:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 292622147A for ; Thu, 21 Feb 2019 10:06:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727046AbfBUKGI (ORCPT ); Thu, 21 Feb 2019 05:06:08 -0500 Received: from relay.sw.ru ([185.231.240.75]:49990 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725891AbfBUKGH (ORCPT ); Thu, 21 Feb 2019 05:06:07 -0500 Received: from [172.16.25.12] by relay.sw.ru with esmtp (Exim 4.91) (envelope-from ) id 1gwlEu-0007TL-Ng; Thu, 21 Feb 2019 13:06:00 +0300 Subject: Re: [PATCH] kasan: turn off asan-stack for clang-8 and earlier To: Arnd Bergmann Cc: Andrey Konovalov , Masahiro Yamada , Michal Marek , Andrew Morton , Dmitry Vyukov , Nick Desaulniers , Mark Brown , Qian Cai , Alexander Potapenko , Martin Schwidefsky , Christoph Lameter , LKML , Linux Kbuild mailing list , kasan-dev References: <20190219214940.391081-1-arnd@arndb.de> From: Andrey Ryabinin Message-ID: Date: Thu, 21 Feb 2019 13:06:20 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/20/19 8:35 PM, Arnd Bergmann wrote: > On Wed, Feb 20, 2019 at 6:00 PM Andrey Ryabinin wrote: >> On 2/20/19 5:51 PM, Arnd Bergmann wrote: >>> On Wed, Feb 20, 2019 at 3:45 PM Andrey Konovalov wrote: >>> I would have to some more research, but I expect several hundred >>> patches before we get to a clean randconfig build with a broken >>> compiler. >> >> Manually maintaining asan-stack parameter for the sake of one broken compiler isn't a great idea either. >> >> Couple alternative suggestions: >> >> 1) If we can't fix the problem or the cost of fixing is too high, maybe just hide it? Disable -Wframe-larger-then on pre clang-9 compilers. >> >> 2) Fallback cflags. The idea is to try to compile every the file with "-mllvm -asan-stack=1 -Wframe-larger-than=2048 -Werror" at first, >> and fallback to "-mllvm -asan-stack=0" if failed. So it would be something similar to $(call cc-option, -mllvm -asan-stack=1 -Wframe-larger-than=2048 -Werror, -mllvm -asan-stack=0) >> except that "cc-option" tries options only once on some code example while we need to try options on every file that we actually compile. >> Honestly, I'm not sure that it's worthy to hack Kbuild engine for that particular use-case. > > My original plan was to put this under CONFIG_KASAN_EXTRA to allow you > to still enable it in older compilers, but you just removed that option ;-) > > Maybe bringing it back would be a compromise? That way it's hidden from > all the build testing bots (because of the !CONFIG_COMPILE_TEST dependency), > but anyone who really wants it can still have the option, and set > CONFIG_FRAME_WARN > to whichever value they like. > I think there is much simpler solution: --- lib/Kconfig.kasan | 2 ++ 1 file changed, 2 insertions(+) diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index 219cddc913ac..6cd035f06cee 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -105,6 +105,8 @@ endchoice config KASAN_STACK int + range 0 1 + prompt "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && (CLANG_VERSION < 90000) default 0 if CC_IS_CLANG && (CLANG_VERSION < 90000) default 1 help -- AFAIK, randconfig is not able to randomize int config options, so it will be disabled for build robots, but users still will be able to enable it.