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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 3433BC4360C for ; Thu, 26 Sep 2019 12:20:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0B101207FF for ; Thu, 26 Sep 2019 12:20:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726195AbfIZMUQ (ORCPT ); Thu, 26 Sep 2019 08:20:16 -0400 Received: from foss.arm.com ([217.140.110.172]:48064 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725768AbfIZMUQ (ORCPT ); Thu, 26 Sep 2019 08:20:16 -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 240B6142F; Thu, 26 Sep 2019 05:20:15 -0700 (PDT) Received: from [10.37.12.151] (unknown [10.37.12.151]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BFDC43F67D; Thu, 26 Sep 2019 05:20:13 -0700 (PDT) Subject: Re: [PATCH 1/4] arm64: vdso32: Introduce COMPAT_CC_IS_GCC From: Vincenzo Frascino To: Catalin Marinas Cc: ard.biesheuvel@linaro.org, ndesaulniers@google.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, will@kernel.org, linux-arm-kernel@lists.infradead.org References: <20190920142738.qlsjwguc6bpnez63@willie-the-truck> <20190926060353.54894-1-vincenzo.frascino@arm.com> <20190926060353.54894-2-vincenzo.frascino@arm.com> <20190926080616.GB26802@iMac.local> <0ff3d5f4-11c9-4207-c6ab-2f8e9ee7de5e@arm.com> Message-ID: Date: Thu, 26 Sep 2019 13:22:01 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <0ff3d5f4-11c9-4207-c6ab-2f8e9ee7de5e@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/26/19 11:56 AM, Vincenzo Frascino wrote: > On 9/26/19 9:06 AM, Catalin Marinas wrote: >> On Thu, Sep 26, 2019 at 07:03:50AM +0100, Vincenzo Frascino wrote: >>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >>> index 37c610963eee..afe8c948b493 100644 >>> --- a/arch/arm64/Kconfig >>> +++ b/arch/arm64/Kconfig >>> @@ -110,7 +110,7 @@ config ARM64 >>> select GENERIC_STRNLEN_USER >>> select GENERIC_TIME_VSYSCALL >>> select GENERIC_GETTIMEOFDAY >>> - select GENERIC_COMPAT_VDSO if (!CPU_BIG_ENDIAN && COMPAT) >>> + select GENERIC_COMPAT_VDSO if (!CPU_BIG_ENDIAN && COMPAT && COMPAT_CC_IS_GCC) >>> select HANDLE_DOMAIN_IRQ >>> select HARDIRQS_SW_RESEND >>> select HAVE_PCI >>> @@ -313,6 +313,9 @@ config KASAN_SHADOW_OFFSET >>> default 0xeffffff900000000 if ARM64_VA_BITS_36 && KASAN_SW_TAGS >>> default 0xffffffffffffffff >>> >>> +config COMPAT_CC_IS_GCC >>> + def_bool $(success,$(CROSS_COMPILE_COMPAT)gcc --version | head -n 1 | grep -q arm) >> >> Nitpick: I prefer COMPATCC instead of COMPAT_CC for consistency with >> HOSTCC. >> > > Ok, will change this in v2. > >> Now, could we not generate a COMPATCC in the Makefile and use >> $(COMPATCC) here instead of $(CROSS_COMPILE_COMPAT)gcc? It really >> doesn't make sense to check that gcc is gcc. >> > > All right, COMPATCC is already in the makefile, I will use it in here. > What you are proposing seems not possible because Kconfig runs first and then the arch Makefile, hence compatcc does not take effect on the Kconfig. I will post v2 with what I proposed, please feel free to comment if you have a better idea. arch/arm64/configs/defconfig:726:warning: symbol value 'm' invalid for REMOTEPROC # # configuration written to .config # make[1]: Leaving directory '/data1/Projects/LinuxKernel/linux-out' make[1]: Entering directory '/data1/Projects/LinuxKernel/linux-out' $COMPATCC is [arm-linux-gnueabihf-gcc] GEN Makefile >> A next step would be to check that COMPATCC can actually generate 32-bit >> objects. But it's not essential at this stage. >> > > We are already checking this making sure that arm is present in the triple (grep > -q arm). > >>> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile >>> index 84a3d502c5a5..34f53eb11878 100644 >>> --- a/arch/arm64/Makefile >>> +++ b/arch/arm64/Makefile >>> @@ -54,19 +54,8 @@ $(warning Detected assembler with broken .inst; disassembly will be unreliable) >>> endif >>> >>> ifeq ($(CONFIG_GENERIC_COMPAT_VDSO), y) >>> - CROSS_COMPILE_COMPAT ?= $(CONFIG_CROSS_COMPILE_COMPAT_VDSO:"%"=%) >>> - >>> - ifeq ($(CONFIG_CC_IS_CLANG), y) >>> - $(warning CROSS_COMPILE_COMPAT is clang, the compat vDSO will not be built) >>> - else ifeq ($(strip $(CROSS_COMPILE_COMPAT)),) >>> - $(warning CROSS_COMPILE_COMPAT not defined or empty, the compat vDSO will not be built) >>> - else ifeq ($(shell which $(CROSS_COMPILE_COMPAT)gcc 2> /dev/null),) >>> - $(error $(CROSS_COMPILE_COMPAT)gcc not found, check CROSS_COMPILE_COMPAT) >>> - else >>> - export CROSS_COMPILE_COMPAT >>> - export CONFIG_COMPAT_VDSO := y >>> - compat_vdso := -DCONFIG_COMPAT_VDSO=1 >>> - endif >>> + export CONFIG_COMPAT_VDSO := y >>> + compat_vdso := -DCONFIG_COMPAT_VDSO=1 >>> endif >> >> Has CONFIG_CROSS_COMPILE_COMPAT_VDSO actually been removed from >> lib/vdso/Kconfig? (I haven't checked the subsequent patches). >> > -- Regards, Vincenzo