From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:49518 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031157AbeCSSXd (ORCPT ); Mon, 19 Mar 2018 14:23:33 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Arnd Bergmann , Dmitry Vyukov , Kees Cook , Sasha Levin Subject: [PATCH 4.9 126/241] lkdtm: turn off kcov for lkdtm_rodata_do_nothing: Date: Mon, 19 Mar 2018 19:06:31 +0100 Message-Id: <20180319180756.416129214@linuxfoundation.org> In-Reply-To: <20180319180751.172155436@linuxfoundation.org> References: <20180319180751.172155436@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Arnd Bergmann [ Upstream commit 7064dc7fc13b2994d33ae540ffb7a3a05ac463bf ] I ran into a link error on ARM64 for lkdtm_rodata_do_nothing: drivers/misc/built-in.o: In function `lkdtm_rodata_do_nothing': :(.rodata+0x68c8): relocation truncated to fit: R_AARCH64_CALL26 against symbol `__sanitizer_cov_trace_pc' defined in .text section in kernel/built-in.o I did not analyze this further, but my theory is that we would need a trampoline to call __sanitizer_cov_trace_pc(), but the linker (correctly) only adds trampolines for callers in executable sections. Disabling KCOV for this one file avoids the build failure with no other practical downsides I can think of. The problem can only happen on kernels that contain both kcov and lkdtm, so if we want to backport this, it should be in the earliest version that has both (v4.8). Fixes: 5c9a8750a640 ("kernel: add kcov code coverage") Fixes: 9a49a528dcf3 ("lkdtm: add function for testing .rodata section") Signed-off-by: Arnd Bergmann Acked-by: Dmitry Vyukov Acked-by: Kees Cook Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/misc/Makefile | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/misc/Makefile +++ b/drivers/misc/Makefile @@ -61,6 +61,8 @@ lkdtm-$(CONFIG_LKDTM) += lkdtm_perms.o lkdtm-$(CONFIG_LKDTM) += lkdtm_rodata_objcopy.o lkdtm-$(CONFIG_LKDTM) += lkdtm_usercopy.o +KCOV_INSTRUMENT_lkdtm_rodata.o := n + OBJCOPYFLAGS := OBJCOPYFLAGS_lkdtm_rodata_objcopy.o := \ --set-section-flags .text=alloc,readonly \