From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1210D2C80 for ; Wed, 6 Oct 2021 02:43:15 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 9AA8C611AE; Wed, 6 Oct 2021 02:43:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1633488195; bh=MQgdRVTnbMJVvWkGZSlQjMAdeQNOwFmejBVlgfTVeCg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kTn8n8T6ka9CnRdawCfnAtucbwEIWcyo8eXPkLNPYOdIA1/qy9proCCwD7nAQD82Q GNJTPIJxVJzVE0V7EkLCbKgAv5h+4MKrTyoVFcKUzU/Qi6/weqYZGOHIJQDoQ2x7OI nnR70T9MkUQzwNcg/PomRMAmYzV9oa11zRa7PCsORBAGCwQF0FjAUrZgFRi4JKL3wh nMsLQy7pNAbSIcw4xqAQQoRwDwZw2CvOsegkpYhUBwAoSwI2pTFj8LEsE3QX3XEqbq vDXWncSp3MY/krOcUR/4D98KnyikeBQ7r0Bw83PP/TDBVw4gvk1Lh2PiYJt0V7Jz6I lQA9RsGsMzAuA== Date: Tue, 5 Oct 2021 19:43:10 -0700 From: Nathan Chancellor To: Andrey Konovalov Cc: Andrey Ryabinin , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Nick Desaulniers , Arnd Bergmann , kasan-dev , LKML , llvm@lists.linux.dev Subject: Re: [PATCH] kasan: Always respect CONFIG_KASAN_STACK Message-ID: References: <20210922205525.570068-1-nathan@kernel.org> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Sun, Oct 03, 2021 at 08:04:53PM +0200, Andrey Konovalov wrote: > On Wed, Sep 22, 2021 at 10:55 PM Nathan Chancellor wrote: > > > > Currently, the asan-stack parameter is only passed along if > > CFLAGS_KASAN_SHADOW is not empty, which requires KASAN_SHADOW_OFFSET to > > be defined in Kconfig so that the value can be checked. In RISC-V's > > case, KASAN_SHADOW_OFFSET is not defined in Kconfig, which means that > > asan-stack does not get disabled with clang even when CONFIG_KASAN_STACK > > is disabled, resulting in large stack warnings with allmodconfig: > > > > drivers/video/fbdev/omap2/omapfb/displays/panel-lgphilips-lb035q02.c:117:12: > > error: stack frame size (14400) exceeds limit (2048) in function > > 'lb035q02_connect' [-Werror,-Wframe-larger-than] > > static int lb035q02_connect(struct omap_dss_device *dssdev) > > ^ > > 1 error generated. > > > > Ensure that the value of CONFIG_KASAN_STACK is always passed along to > > the compiler so that these warnings do not happen when > > CONFIG_KASAN_STACK is disabled. > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/1453 > > References: 6baec880d7a5 ("kasan: turn off asan-stack for clang-8 and earlier") > > Signed-off-by: Nathan Chancellor > > --- > > scripts/Makefile.kasan | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan > > index 801c415bac59..b9e94c5e7097 100644 > > --- a/scripts/Makefile.kasan > > +++ b/scripts/Makefile.kasan > > @@ -33,10 +33,11 @@ else > > CFLAGS_KASAN := $(CFLAGS_KASAN_SHADOW) \ > > $(call cc-param,asan-globals=1) \ > > $(call cc-param,asan-instrumentation-with-call-threshold=$(call_threshold)) \ > > - $(call cc-param,asan-stack=$(stack_enable)) \ > > $(call cc-param,asan-instrument-allocas=1) > > endif > > This part of code always looked weird to me. > > Shouldn't we be able to pull all these options out of the else section? > > Then, the code structure would make sense: first, try applying > KASAN_SHADOW_OFFSET; if failed, use CFLAGS_KASAN_MINIMAL; and then try > applying all these options one by one. Prior to commit 1a69e7ce8391 ("kasan/Makefile: support LLVM style asan parameters"), all the flags were run under one cc-option, meaning that if $(KASAN_SHADOW_OFFSET) was not set, the whole call would fail. However, after that commit, it is possible to do this but I was not sure if that was intentional so I went for the minimal fix. Cheers, Nathan