From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762656AbdJQN4O (ORCPT ); Tue, 17 Oct 2017 09:56:14 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:47632 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762639AbdJQN4M (ORCPT ); Tue, 17 Oct 2017 09:56:12 -0400 Date: Tue, 17 Oct 2017 14:56:08 +0100 From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, adech.fo@gmail.com, aryabinin@virtuozzo.com, catalin.marinas@arm.com, christoffer.dall@linaro.org, dvyukov@google.com, linux-kbuild@vger.kernel.org, marc.zyngier@arm.com, will.deacon@arm.com, yamada.masahiro@socionext.com Subject: Re: [PATCH 4/4] arm64: vdso: remove pointless gcov option Message-ID: <20171017135607.copc5duf5oon4azr@lakrids.cambridge.arm.com> References: <20171016132440.38098-1-mark.rutland@arm.com> <20171016132440.38098-5-mark.rutland@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171016132440.38098-5-mark.rutland@arm.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 16, 2017 at 02:24:40PM +0100, Mark Rutland wrote: > The arm64 VDSO Makefile explicitly disables gcov; a practice we seem to > have inherited from other VDSO Makefiles. > > The arm64 VDSO is written entirely in assembly, so this is not > necessary. Further, if the VDSO were written in C it would be necessary > to disable all other instrumentation, and this alone would not be > sufficient. Evidently, I haven't looked hrough the history thoroughly enough. It turns out that this was deliberately added in commit: 543097843ca7c9ac ("arm64: build vdso without libgcov") ... this is necessary because we use the compiler to do the actual linking. That causes us to have -lgcov in the compilr flags, and the link can fail. Please ignore this patch for now. Thanks, Mark. > This patch remosves the redundant GCOV option for now. > > Cc: Catalin Marinas > Reported-by: Will Deacon > Signed-off-by: Mark Rutland > --- > arch/arm64/kernel/vdso/Makefile | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile > index 62c84f7cb01b..350190b749dd 100644 > --- a/arch/arm64/kernel/vdso/Makefile > +++ b/arch/arm64/kernel/vdso/Makefile > @@ -15,9 +15,6 @@ ccflags-y := -shared -fno-common -fno-builtin > ccflags-y += -nostdlib -Wl,-soname=linux-vdso.so.1 \ > $(call cc-ldoption, -Wl$(comma)--hash-style=sysv) > > -# Disable gcov profiling for VDSO code > -GCOV_PROFILE := n > - > # Workaround for bare-metal (ELF) toolchains that neglect to pass -shared > # down to collect2, resulting in silent corruption of the vDSO image. > ccflags-y += -Wl,-shared > -- > 2.11.0 >