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=-16.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 828E4C433E0 for ; Mon, 21 Dec 2020 14:37:40 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3858E22B51 for ; Mon, 21 Dec 2020 14:37:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3858E22B51 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=9jYG0GuJ9B1pp1witojpG/vRvSvRfs4nbP0b62L3c18=; b=3JI+6r8VVrwrMtLCtR1CJDDxl 9cGt2eVmsM/xhf5farSrAjpnO00dOzKz84X5PFJdbeTgf08zr0YM1BG8ycqgPns8ZYFZljdQng04y nY2LG1+zvnNN6nr4qza3L1jj6TyJLdybnXJPwLckADdq9/0OXDQk1fl92/Ep1aHUnyOvKrN8feu35 ZTwPPt5t3z5TTFdvqMQYhCfBuYCY5QtJSOCQbQ9hgpmrwFlvC20wr2B5Qe2vjUAByC2ywmqMPdbAf 3Z6FHmXWL7PAK0ujpQcwGeAJqoe+9/5y0iFmUOGh1pQawQM7mWYNwPtZMZyhhZvQ3jy7qv1Y0LCQX C5aGZ/nwQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1krMIX-0005AG-08; Mon, 21 Dec 2020 14:36:29 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1krMIT-00059i-E7 for linux-arm-kernel@lists.infradead.org; Mon, 21 Dec 2020 14:36:26 +0000 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 349F61FB; Mon, 21 Dec 2020 06:36:17 -0800 (PST) Received: from [10.37.8.22] (unknown [10.37.8.22]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D20C63F6CF; Mon, 21 Dec 2020 06:36:15 -0800 (PST) Subject: Re: [PATCH] arm64: do not descend to vdso directories twice To: Masahiro Yamada , Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org References: <20201218024540.1102650-1-masahiroy@kernel.org> From: Vincenzo Frascino Message-ID: <55dc2724-cdfe-28ad-395d-707fe9bae2db@arm.com> Date: Mon, 21 Dec 2020 14:39:44 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201218024540.1102650-1-masahiroy@kernel.org> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201221_093625_607229_ECD823FF X-CRM114-Status: GOOD ( 24.49 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michael Ellerman , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Masahiro, On 12/18/20 2:45 AM, Masahiro Yamada wrote: > arm64 descends into each vdso directory twice; first in vdso_prepare, > second during the ordinary build process. > > PPC mimicked it and uncovered a problem [1]. In the first descend, > Kbuild directly visits the vdso directories, therefore it does not > inherit subdir-ccflags-y from upper directories. > > This means the command line parameters may differ between the two. > If it happens, the offset values in the generated headers might be > different from real offsets of vdso.so in the kernel. > > This potential danger should be avoided. The vdso directories are > built in the vdso_prepare stage, so the second descend is unneeded. > > [1]: https://lore.kernel.org/linux-kbuild/CAK7LNARAkJ3_-4gX0VA2UkapbOftuzfSTVMBbgbw=HD8n7N+7w@mail.gmail.com/T/#ma10dcb961fda13f36d42d58fa6cb2da988b7e73a > I could not reproduce the problem you are reporting on arm64. Could you please provide some steps? In my case the vDSO library is not rebuilt as a result of the procedure reported in the email you linked at [1]. > Signed-off-by: Masahiro Yamada > --- > > arch/arm64/Makefile | 10 ++++++---- > arch/arm64/kernel/Makefile | 5 +++-- > arch/arm64/kernel/{vdso/vdso.S => vdso-wrap.S} | 0 > arch/arm64/kernel/vdso/Makefile | 1 - > arch/arm64/kernel/{vdso32/vdso.S => vdso32-wrap.S} | 0 > arch/arm64/kernel/vdso32/Makefile | 1 - > 6 files changed, 9 insertions(+), 8 deletions(-) > rename arch/arm64/kernel/{vdso/vdso.S => vdso-wrap.S} (100%) > rename arch/arm64/kernel/{vdso32/vdso.S => vdso32-wrap.S} (100%) > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > index 6a87d592bd00..f18d20a68170 100644 > --- a/arch/arm64/Makefile > +++ b/arch/arm64/Makefile > @@ -179,10 +179,12 @@ ifeq ($(KBUILD_EXTMOD),) > # this hack. > prepare: vdso_prepare > vdso_prepare: prepare0 > - $(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso include/generated/vdso-offsets.h > - $(if $(CONFIG_COMPAT_VDSO),$(Q)$(MAKE) \ > - $(build)=arch/arm64/kernel/vdso32 \ > - include/generated/vdso32-offsets.h) > + $(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso \ > + include/generated/vdso-offsets.h arch/arm64/kernel/vdso/vdso.so > +ifdef CONFIG_COMPAT_VDSO > + $(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 \ > + include/generated/vdso32-offsets.h arch/arm64/kernel/vdso32/vdso.so > +endif > endif The reason why it is currently done in two phases (a bit hacky as per comment) is because vdso-offsets.h is required to be generated before compiling kernel/. Please refer to the comment in arch/arm64/Makefile. Could you explain how your change satisfies the dependency? > > define archhelp > diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile > index 86364ab6f13f..42f6ad2c7eac 100644 > --- a/arch/arm64/kernel/Makefile > +++ b/arch/arm64/kernel/Makefile > @@ -59,9 +59,10 @@ obj-$(CONFIG_CRASH_CORE) += crash_core.o > obj-$(CONFIG_ARM_SDE_INTERFACE) += sdei.o > obj-$(CONFIG_ARM64_PTR_AUTH) += pointer_auth.o > obj-$(CONFIG_ARM64_MTE) += mte.o > +obj-y += vdso-wrap.o > +obj-$(CONFIG_COMPAT_VDSO) += vdso32-wrap.o > > -obj-y += vdso/ probes/ > -obj-$(CONFIG_COMPAT_VDSO) += vdso32/ > +obj-y += probes/ > head-y := head.o > extra-y += $(head-y) vmlinux.lds > > diff --git a/arch/arm64/kernel/vdso/vdso.S b/arch/arm64/kernel/vdso-wrap.S > similarity index 100% > rename from arch/arm64/kernel/vdso/vdso.S > rename to arch/arm64/kernel/vdso-wrap.S > diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile > index a8f8e409e2bf..85222f64f394 100644 > --- a/arch/arm64/kernel/vdso/Makefile > +++ b/arch/arm64/kernel/vdso/Makefile > @@ -45,7 +45,6 @@ endif > # Disable gcov profiling for VDSO code > GCOV_PROFILE := n > > -obj-y += vdso.o > targets += vdso.lds > CPPFLAGS_vdso.lds += -P -C -U$(ARCH) > > diff --git a/arch/arm64/kernel/vdso32/vdso.S b/arch/arm64/kernel/vdso32-wrap.S > similarity index 100% > rename from arch/arm64/kernel/vdso32/vdso.S > rename to arch/arm64/kernel/vdso32-wrap.S > diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile > index a1e0f91e6cea..789ad420f16b 100644 > --- a/arch/arm64/kernel/vdso32/Makefile > +++ b/arch/arm64/kernel/vdso32/Makefile > @@ -155,7 +155,6 @@ c-obj-vdso-gettimeofday := $(addprefix $(obj)/, $(c-obj-vdso-gettimeofday)) > asm-obj-vdso := $(addprefix $(obj)/, $(asm-obj-vdso)) > obj-vdso := $(c-obj-vdso) $(c-obj-vdso-gettimeofday) $(asm-obj-vdso) > > -obj-y += vdso.o > targets += vdso.lds > CPPFLAGS_vdso.lds += -P -C -U$(ARCH) > > -- Regards, Vincenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel