Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A8A39C433F5 for ; Thu, 2 Dec 2021 14:45:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358750AbhLBOtC (ORCPT ); Thu, 2 Dec 2021 09:49:02 -0500 Received: from foss.arm.com ([217.140.110.172]:36192 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358717AbhLBOsX (ORCPT ); Thu, 2 Dec 2021 09:48:23 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F39C6142F; Thu, 2 Dec 2021 06:45:00 -0800 (PST) Received: from lakrids (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F1CDC3F766; Thu, 2 Dec 2021 06:44:59 -0800 (PST) Date: Thu, 2 Dec 2021 14:44:51 +0000 From: Mark Rutland To: Marco Elver Cc: Kefeng Wang , Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, joey.gouly@arm.com Subject: Re: [PATCH v3] arm64: Enable KCSAN Message-ID: References: <20211202143331.15259-1-wangkefeng.wang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 02, 2021 at 03:36:06PM +0100, Marco Elver wrote: > On Thu, 2 Dec 2021 at 15:23, Kefeng Wang wrote: > > > > This patch enables KCSAN for arm64, with updates to build rules > > to not use KCSAN for several incompatible compilation units. > > > > Resent GCC version(at least GCC10) made outline-atomics as the > > s/Resent/Recent/ > > > default option(unlike Clang), which will cause linker errors > > for kernel/kcsan/core.o. Disables the out-of-line atomics by > > no-outline-atomics to fix the linker errors. > > > > Meanwhile, as Mark said[1], there is a specific issue on arm64 > > about ARM64_BTI with Clang 11 if KCSAN enabled, which is fixed > > by Clang 12, add CLANG_VERSION check. And also some latent issues > > are need to be fixed which isn't just a KCSAN problem, we make > > the KCSAN depends on EXPERT for now. > > > > Tested selftest and kcsan_test(built with GCC11 and Clang 13), > > and all passed. > > > > [1] https://lkml.org/lkml/2021/12/1/354 > > Please use lore/kernel.org permalinks. For this one it'd be: > https://lkml.kernel.org/r/YadiUPpJ0gADbiHQ@FVFF77S0Q05N > > (But I think if this is the final version of the patch, hopefully a > maintainer can amend the commit message.) > > > Signed-off-by: Kefeng Wang > > Acked-by: Marco Elver # kernel/kcsan > > is still valid, given nothing changed there. I leave the rest to Mark. I want to do some compiler / config testing before I ack this (just to make sure there isn't some latent issue I've forgotten about), but otherwise I think this should be fine. I'll try to have that done in the next few days. Any other review/testing would be appreciated! Thanks, Mark. > > Thanks, > -- Marco > > > --- > > Tested on Qemu with clang 13 / gcc 11, based on 5.16-rc3. > > > > [ 0.221518] kcsan: enabled early > > [ 0.222422] kcsan: strict mode configured > > ... > > [ 5.839223] kcsan: selftest: 3/3 tests passed > > ... > > [ 517.895102] # kcsan: pass:24 fail:0 skip:0 total:24 > > [ 517.896393] # Totals: pass:168 fail:0 skip:0 total:168 > > [ 517.897502] ok 1 - kcsan > > > > v3: > > - add EXPERT and CLANG_VERSION depends suggested by Mark Rutland > > v2: > > - tested on GCC11 and disable outline-atomics for kernel/kcsan/core.c > > suggested by Marco Elver > > > > arch/arm64/Kconfig | 1 + > > arch/arm64/kernel/vdso/Makefile | 1 + > > arch/arm64/kvm/hyp/nvhe/Makefile | 1 + > > kernel/kcsan/Makefile | 1 + > > 4 files changed, 4 insertions(+) > > > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > > index 4ff73299f8a9..3a7b17742cde 100644 > > --- a/arch/arm64/Kconfig > > +++ b/arch/arm64/Kconfig > > @@ -150,6 +150,7 @@ config ARM64 > > select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN > > select HAVE_ARCH_KASAN_SW_TAGS if HAVE_ARCH_KASAN > > select HAVE_ARCH_KASAN_HW_TAGS if (HAVE_ARCH_KASAN && ARM64_MTE) > > + select HAVE_ARCH_KCSAN if EXPERT && (CC_IS_GCC || CLANG_VERSION >= 120000) > > select HAVE_ARCH_KFENCE > > select HAVE_ARCH_KGDB > > select HAVE_ARCH_MMAP_RND_BITS > > diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile > > index 700767dfd221..60813497a381 100644 > > --- a/arch/arm64/kernel/vdso/Makefile > > +++ b/arch/arm64/kernel/vdso/Makefile > > @@ -32,6 +32,7 @@ ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO > > CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) $(GCC_PLUGINS_CFLAGS) \ > > $(CC_FLAGS_LTO) > > KASAN_SANITIZE := n > > +KCSAN_SANITIZE := n > > UBSAN_SANITIZE := n > > OBJECT_FILES_NON_STANDARD := y > > KCOV_INSTRUMENT := n > > diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile > > index c3c11974fa3b..24b2c2425b38 100644 > > --- a/arch/arm64/kvm/hyp/nvhe/Makefile > > +++ b/arch/arm64/kvm/hyp/nvhe/Makefile > > @@ -89,6 +89,7 @@ KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_CFI) > > # cause crashes. Just disable it. > > GCOV_PROFILE := n > > KASAN_SANITIZE := n > > +KCSAN_SANITIZE := n > > UBSAN_SANITIZE := n > > KCOV_INSTRUMENT := n > > > > diff --git a/kernel/kcsan/Makefile b/kernel/kcsan/Makefile > > index c2bb07f5bcc7..e893b0e1d62a 100644 > > --- a/kernel/kcsan/Makefile > > +++ b/kernel/kcsan/Makefile > > @@ -8,6 +8,7 @@ CFLAGS_REMOVE_debugfs.o = $(CC_FLAGS_FTRACE) > > CFLAGS_REMOVE_report.o = $(CC_FLAGS_FTRACE) > > > > CFLAGS_core.o := $(call cc-option,-fno-conserve-stack) \ > > + $(call cc-option,-mno-outline-atomics) \ > > -fno-stack-protector -DDISABLE_BRANCH_PROFILING > > > > obj-y := core.o debugfs.o report.o > > -- > > 2.26.2 > >