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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 B72E5C3A5A0 for ; Mon, 19 Aug 2019 16:59:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 93BAC22CEA for ; Mon, 19 Aug 2019 16:59:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727981AbfHSQ7z (ORCPT ); Mon, 19 Aug 2019 12:59:55 -0400 Received: from foss.arm.com ([217.140.110.172]:57500 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726918AbfHSQ7z (ORCPT ); Mon, 19 Aug 2019 12:59:55 -0400 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 14C1F360; Mon, 19 Aug 2019 09:59:54 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 472E53F718; Mon, 19 Aug 2019 09:59:53 -0700 (PDT) Date: Mon, 19 Aug 2019 17:59:48 +0100 From: Mark Rutland To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, clang-built-linux@googlegroups.com Cc: Nathan Chancellor , Nick Desaulniers Subject: Enabling UBSAN breaks KCOV in clang (8.0.*) on arm64 Message-ID: <20190819165947.GA30292@lakrids.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I found that when I enable both KCOV and UBSAN on arm64, clang fails to emit any __sanitizer_cov_trace_*() calls in the resulting binary, rendering KCOV useless. For example, when building v5.3-rc3's arch/arm64/kernel/setup.o: * With defconfig + CONFIG KCOV: clang -Wp,-MD,arch/arm64/kernel/.setup.o.d -nostdinc -isystem /mnt/data/opt/toolchain/llvm/8.0.0/clang+llvm-8.0.0-x86_64-linux-sles11.3/lib/clang/8.0.0/include -I./arch/arm64/include -I./arch/arm64/include/generated -I./include -I./arch/arm64/include/uapi -I./arch/arm64/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -include ./include/linux/compiler_types.h -D__KERNEL__ -mlittle-endian -DKASAN_SHADOW_SCALE_SHIFT=3 -Qunused-arguments -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -Werror=implicit-function-declaration -Werror=implicit-int -Wno-format-security -std=gnu89 --target=aarch64-linux --prefix=/mnt/data/opt/toolchain/kernel-org-crosstool/gcc-8.1.0-nolibc/aarch64-linux/bin/ --gcc-toolchain=/mnt/data/opt/toolchain/kernel-org-crosstool/gcc-8.1.0-nolibc/aarch64-linux -no-integrated-as -Werror=unknown-warning-option -mgeneral-regs-only -DCONFIG_AS_LSE=1 -fno-asynchronous-unwind-tables -DKASAN_SHADOW_SCALE_SHIFT=3 -fno-delete-null-pointer-checks -Wno-address-of-packed-member -O2 -Wframe-larger-than=2048 -fstack-protector-strong -Wno-format-invalid-specifier -Wno-gnu -Wno-tautological-compare -mno-global-merge -Wno-unused-const-variable -fno-omit-frame-pointer -fno-optimize-sibling-calls -g -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -fno-strict-overflow -fno-merge-all-constants -fno-stack-check -Werror=date-time -Werror=incompatible-pointer-types -Wno-initializer-overrides -Wno-format -Wno-sign-compare -Wno-format-zero-length -fsanitize-coverage=trace-pc -DKBUILD_BASENAME='"setup"' -DKBUILD_MODNAME='"setup"' -c -o arch/arm64/kernel/setup.o arch/arm64/kernel/setup.c ... and there are 44 calls to __sanitizer_cov_trace_pc in the resulting setup.o * with defconfig + CONFIG_KCOV + CONFIG_UBSAN: clang -Wp,-MD,arch/arm64/kernel/.setup.o.d -nostdinc -isystem /mnt/data/opt/toolchain/llvm/8.0.0/clang+llvm-8.0.0-x86_64-linux-sles11.3/lib/clang/8.0.0/include -I./arch/arm64/include -I./arch/arm64/include/generated -I./include -I./arch/arm64/include/uapi -I./arch/arm64/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -include ./include/linux/compiler_types.h -D__KERNEL__ -mlittle-endian -DKASAN_SHADOW_SCALE_SHIFT=3 -Qunused-arguments -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -Werror=implicit-function-declaration -Werror=implicit-int -Wno-format-security -std=gnu89 --target=aarch64-linux --prefix=/mnt/data/opt/toolchain/kernel-org-crosstool/gcc-8.1.0-nolibc/aarch64-linux/bin/ --gcc-toolchain=/mnt/data/opt/toolchain/kernel-org-crosstool/gcc-8.1.0-nolibc/aarch64-linux -no-integrated-as -Werror=unknown-warning-option -mgeneral-regs-only -DCONFIG_AS_LSE=1 -fno-asynchronous-unwind-tables -DKASAN_SHADOW_SCALE_SHIFT=3 -fno-delete-null-pointer-checks -Wno-address-of-packed-member -O2 -Wframe-larger-than=2048 -fstack-protector-strong -Wno-format-invalid-specifier -Wno-gnu -Wno-tautological-compare -mno-global-merge -Wno-unused-const-variable -fno-omit-frame-pointer -fno-optimize-sibling-calls -g -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -fno-strict-overflow -fno-merge-all-constants -fno-stack-check -Werror=date-time -Werror=incompatible-pointer-types -Wno-initializer-overrides -Wno-format -Wno-sign-compare -Wno-format-zero-length -fsanitize=shift -fsanitize=integer-divide-by-zero -fsanitize=unreachable -fsanitize=signed-integer-overflow -fsanitize=bounds -fsanitize=object-size -fsanitize=bool -fsanitize=enum -fsanitize-coverage=trace-pc -DKBUILD_BASENAME='"setup"' -DKBUILD_MODNAME='"setup"' -c -o arch/arm64/kernel/setup.o arch/arm64/kernel/setup.c ... and there are 0 calls to __sanitizer_cov_trace_pc in the resulting setup.o, even though -fsanitize-coverage=trace-pc was passed to clang. If I remove -fsanitize=bounds, there are 121 calls to __sanitizer_cov_trace_pc in setup.o. Removing the other options enabled by UBSAN didn't have any effect on setup.o. I'm using the llvm.org 8.0.{0,1} binaries [1,2], along with the kernel.org crosstool 8.1.0 binaries [3]. Any ideas as to what's going on? Thanks, Mark. [1] http://releases.llvm.org/download.html#8.0.0 [2] http://releases.llvm.org/download.html#8.0.1 [3] https://mirrors.edge.kernel.org/pub/tools/crosstool/