From patchwork Wed Apr 29 03:45:13 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Masahiro Yamada X-Patchwork-Id: 11515997 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A298781 for ; Wed, 29 Apr 2020 03:47:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8B8AB20731 for ; Wed, 29 Apr 2020 03:47:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588132042; bh=t5gr+NO6w6OxyLnxWIRjbd8KZPnJg5NDZvD9pZx0ZtE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=uTmzaa5Qe+GlDFWXNpCMgQriw6Hx6k449WvQfuQuH6X4zlWY26WxBazHo8/sSPoVE VbFmkqn5V6p2kC40SSQ2IbK5HKWdk8DfgAvKu5Vk+hWqKp8TskUgqKbekpNuB/57mf J7Wid8vXs6wCbuYccsdywIq8A4MieYGv0U4m1ijo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726692AbgD2Dqa (ORCPT ); Tue, 28 Apr 2020 23:46:30 -0400 Received: from conuserg-12.nifty.com ([210.131.2.79]:30765 "EHLO conuserg-12.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726599AbgD2Dq3 (ORCPT ); Tue, 28 Apr 2020 23:46:29 -0400 Received: from oscar.flets-west.jp (softbank126090202047.bbtec.net [126.90.202.47]) (authenticated) by conuserg-12.nifty.com with ESMTP id 03T3jXlc020748; Wed, 29 Apr 2020 12:45:35 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-12.nifty.com 03T3jXlc020748 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1588131935; bh=a/8yLvdu6xS3Gj2bx6HeWvVtgMKV8ZR+HSeVW/CO80E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BHXkufn8HbfXGioq28uVr88OWCXL5Rx7FVk0ASGpkAQE0zd9aZwVSjkgojnGDG5cp nPZhkMa9l9cy+RfgkE+Bx6MXNiSMCg5K9b77C7LgZyNNYV9ksEowrBzAJ25oCWRVMu e8QuXw573q+aw6j15TCxTkGULcogeT5smoP35iqyBsRN3ZvUSTuYQTe8HE+2mv2kZZ jTD4IqsTa0Xjkj6DuLjOGyUrmV0u2xQRfhEN2Y3rKOe7svt/GA9EinxUdns8fodC2f zFycDImm+xZyKhDwa8qNjYyRRN8WRJW3vhK5gESXaK8azIfLO2+uY7JgYb/lZCQn9E Z2xUkuYoEEmuQ== X-Nifty-SrcIP: [126.90.202.47] From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: bpf , Arnd Bergmann , Sam Ravnborg , linux-kernel@vger.kernel.org, Masahiro Yamada Subject: [PATCH v2 01/15] bpfilter: match bit size of bpfilter_umh to that of the kernel Date: Wed, 29 Apr 2020 12:45:13 +0900 Message-Id: <20200429034527.590520-2-masahiroy@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200429034527.590520-1-masahiroy@kernel.org> References: <20200429034527.590520-1-masahiroy@kernel.org> MIME-Version: 1.0 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org bpfilter_umh is built for the default machine bit of the compiler, which may not match to the bit size of the kernel. This happens in the scenario below: You can use biarch GCC that defaults to 64-bit for building the 32-bit kernel. In this case, Kbuild passes -m32 to teach the compiler to produce 32-bit kernel space objects. However, it is missing when building bpfilter_umh. It is built as a 64-bit ELF, and then embedded into the 32-bit kernel. The 32-bit kernel and 64-bit umh is a bad combination. In theory, we can have 32-bit umh running on 64-bit kernel, but we do not have a good reason to support such a usecase. The best is to match the bit size between them. Pass -m32 or -m64 to the umh build command if it is found in $(KBUILD_CFLAGS). Evaluate CC_CAN_LINK against the kernel bit-size. Signed-off-by: Masahiro Yamada --- Changes in v2: - New patch init/Kconfig | 4 +++- net/bpfilter/Makefile | 5 +++-- usr/include/Makefile | 4 ++++ 3 files changed, 10 insertions(+), 3 deletions(-) diff --git a/init/Kconfig b/init/Kconfig index a494212a3a79..57562a8e2761 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -45,7 +45,9 @@ config CLANG_VERSION default $(shell,$(srctree)/scripts/clang-version.sh $(CC)) config CC_CAN_LINK - def_bool $(success,$(srctree)/scripts/cc-can-link.sh $(CC)) + bool + default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(m64-flag)) if 64BIT + default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(m32-flag)) config CC_HAS_ASM_GOTO def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC)) diff --git a/net/bpfilter/Makefile b/net/bpfilter/Makefile index 36580301da70..f6209e4827b9 100644 --- a/net/bpfilter/Makefile +++ b/net/bpfilter/Makefile @@ -5,14 +5,15 @@ hostprogs := bpfilter_umh bpfilter_umh-objs := main.o -KBUILD_HOSTCFLAGS += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi +KBUILD_HOSTCFLAGS += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi \ + $(filter -m32 -m64, $(KBUILD_CFLAGS)) HOSTCC := $(CC) ifeq ($(CONFIG_BPFILTER_UMH), y) # builtin bpfilter_umh should be compiled with -static # since rootfs isn't mounted at the time of __init # function is called and do_execv won't find elf interpreter -KBUILD_HOSTLDFLAGS += -static +KBUILD_HOSTLDFLAGS += -static $(filter -m32 -m64, $(KBUILD_CFLAGS)) endif $(obj)/bpfilter_umh_blob.o: $(obj)/bpfilter_umh diff --git a/usr/include/Makefile b/usr/include/Makefile index 5a7ee3e5ed86..55362f3ab393 100644 --- a/usr/include/Makefile +++ b/usr/include/Makefile @@ -8,6 +8,10 @@ # We cannot go as far as adding -Wpedantic since it emits too many warnings. UAPI_CFLAGS := -std=c90 -Wall -Werror=implicit-function-declaration +# In theory, we do not care -m32 or -m64 for header compile tests. +# It is here just because CONFIG_CC_CAN_LINK is tested with -m32 or -m64. +UAPI_CFLAGS += $(filter -m32 -m64, $(KBUILD_CFLAGS)) + override c_flags = $(UAPI_CFLAGS) -Wp,-MMD,$(depfile) -I$(objtree)/usr/include # The following are excluded for now because they fail to build.