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=-12.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 B965AC433E8 for ; Mon, 27 Jul 2020 12:38:18 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 4570C20714 for ; Mon, 27 Jul 2020 12:38:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4570C20714 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id CE0E14B947; Mon, 27 Jul 2020 08:38:17 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id k5+Zd46p2djm; Mon, 27 Jul 2020 08:38:16 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 8DE814B94A; Mon, 27 Jul 2020 08:38:16 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id AD9F64B893 for ; Mon, 27 Jul 2020 08:38:15 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id zgv++etcMXEh for ; Mon, 27 Jul 2020 08:38:14 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 3EDE74B87F for ; Mon, 27 Jul 2020 08:38:14 -0400 (EDT) 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 E1CDA30E; Mon, 27 Jul 2020 05:38:13 -0700 (PDT) Received: from [192.168.0.110] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 52EE93F66E; Mon, 27 Jul 2020 05:38:13 -0700 (PDT) Subject: Re: [kvm-unit-tests PATCH] arm64: Compile with -mno-outline-atomics for GCC >= 10 To: Andrew Jones References: <20200717164727.75580-1-alexandru.elisei@arm.com> <20200718091145.zheu46pfjwsntr3a@kamzik.brq.redhat.com> <202d475d-95df-2350-a8e9-9264144993ac@arm.com> <1bf2eab6-c6df-8b4c-b365-7216e7b9a9d7@arm.com> <20200727123031.7v52lu23mmhailar@kamzik.brq.redhat.com> From: Alexandru Elisei Message-ID: Date: Mon, 27 Jul 2020 13:39:09 +0100 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: <20200727123031.7v52lu23mmhailar@kamzik.brq.redhat.com> Content-Language: en-US Cc: pbonzini@redhat.com, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi Drew, On 7/27/20 1:30 PM, Andrew Jones wrote: > On Mon, Jul 27, 2020 at 01:21:03PM +0100, Alexandru Elisei wrote: >> Hi Drew, >> >> On 7/18/20 2:50 PM, Alexandru Elisei wrote: >>> Hi, >>> >>> On 7/18/20 10:11 AM, Andrew Jones wrote: >>>> On Fri, Jul 17, 2020 at 05:47:27PM +0100, Alexandru Elisei wrote: >>>>> GCC 10.1.0 introduced the -m{,no-}outline-atomics flags which, according to >>>>> man 1 gcc: >>>>> >>>>> "Enable or disable calls to out-of-line helpers to implement atomic >>>>> operations. These helpers will, at runtime, determine if the LSE >>>>> instructions from ARMv8.1-A can be used; if not, they will use the >>>>> load/store-exclusive instructions that are present in the base ARMv8.0 ISA. >>>>> [..] This option is on by default." >>>>> >>>>> Unfortunately the option causes the following error at compile time: >>>>> >>>>> aarch64-linux-gnu-ld -nostdlib -pie -n -o arm/spinlock-test.elf -T /path/to/kvm-unit-tests/arm/flat.lds \ >>>>> arm/spinlock-test.o arm/cstart64.o lib/libcflat.a lib/libfdt/libfdt.a /usr/lib/gcc/aarch64-linux-gnu/10.1.0/libgcc.a lib/arm/libeabi.a arm/spinlock-test.aux.o >>>>> aarch64-linux-gnu-ld: /usr/lib/gcc/aarch64-linux-gnu/10.1.0/libgcc.a(lse-init.o): in function `init_have_lse_atomics': >>>>> lse-init.c:(.text.startup+0xc): undefined reference to `__getauxval' >>>>> >>>>> This is happening because we are linking against our own libcflat which >>>>> doesn't implement the function __getauxval(). >>>>> >>>>> Disable the use of the out-of-line functions by compiling with >>>>> -mno-outline-atomics if we detect a GCC version greater than 10. >>>>> >>>>> Signed-off-by: Alexandru Elisei >>>>> --- >>>>> >>>>> Tested with gcc versions 10.1.0 and 5.4.0 (cross-compilation), 9.3.0 >>>>> (native). >>>>> >>>>> I've been able to suss out the reason for the build failure from this >>>>> rejected gcc patch [1]. >>>>> >>>>> [1] https://patches.openembedded.org/patch/172460/ >>>>> >>>>> arm/Makefile.arm64 | 6 ++++++ >>>>> 1 file changed, 6 insertions(+) >>>>> >>>>> diff --git a/arm/Makefile.arm64 b/arm/Makefile.arm64 >>>>> index dfd0c56fe8fb..3223cb966789 100644 >>>>> --- a/arm/Makefile.arm64 >>>>> +++ b/arm/Makefile.arm64 >>>>> @@ -9,6 +9,12 @@ ldarch = elf64-littleaarch64 >>>>> arch_LDFLAGS = -pie -n >>>>> CFLAGS += -mstrict-align >>>>> >>>>> +# The -mno-outline-atomics flag is only valid for GCC versions 10 and greater. >>>>> +GCC_MAJOR_VERSION=$(shell $(CC) -dumpversion 2> /dev/null | cut -f1 -d.) >>>>> +ifeq ($(shell expr "$(GCC_MAJOR_VERSION)" ">=" "10"), 1) >>>>> +CFLAGS += -mno-outline-atomics >>>>> +endif >>>> How about this patch instead? >>>> >>>> diff --git a/Makefile b/Makefile >>>> index 3ff2f91600f6..0e21a49096ba 100644 >>>> --- a/Makefile >>>> +++ b/Makefile >>>> @@ -17,6 +17,11 @@ DESTDIR := $(PREFIX)/share/kvm-unit-tests/ >>>> >>>> .PHONY: arch_clean clean distclean cscope >>>> >>>> +# cc-option >>>> +# Usage: OP_CFLAGS+=$(call cc-option, -falign-functions=0, -malign-functions=0) >>>> +cc-option = $(shell if $(CC) -Werror $(1) -S -o /dev/null -xc /dev/null \ >>>> + > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;) >>>> + >>>> #make sure env CFLAGS variable is not used >>>> CFLAGS = >>>> >>>> @@ -43,12 +48,6 @@ OBJDIRS += $(LIBFDT_objdir) >>>> #include architecture specific make rules >>>> include $(SRCDIR)/$(TEST_DIR)/Makefile >>>> >>>> -# cc-option >>>> -# Usage: OP_CFLAGS+=$(call cc-option, -falign-functions=0, -malign-functions=0) >>>> - >>>> -cc-option = $(shell if $(CC) -Werror $(1) -S -o /dev/null -xc /dev/null \ >>>> - > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;) >>>> - >>>> COMMON_CFLAGS += -g $(autodepend-flags) -fno-strict-aliasing -fno-common >>>> COMMON_CFLAGS += -Wall -Wwrite-strings -Wempty-body -Wuninitialized >>>> COMMON_CFLAGS += -Wignored-qualifiers -Werror >>>> diff --git a/arm/Makefile.arm64 b/arm/Makefile.arm64 >>>> index dfd0c56fe8fb..dbc7524d3070 100644 >>>> --- a/arm/Makefile.arm64 >>>> +++ b/arm/Makefile.arm64 >>>> @@ -9,6 +9,9 @@ ldarch = elf64-littleaarch64 >>>> arch_LDFLAGS = -pie -n >>>> CFLAGS += -mstrict-align >>>> >>>> +mno_outline_atomics := $(call cc-option, -mno-outline-atomics, "") >>>> +CFLAGS += $(mno_outline_atomics) >>>> + >>>> define arch_elf_check = >>>> $(if $(shell ! $(OBJDUMP) -R $(1) >&/dev/null && echo "nok"), >>>> $(error $(shell $(OBJDUMP) -R $(1) 2>&1))) >>>> >>>> >>>> Thanks, >>>> drew >>> Looks much better than my version. Do you want me to spin a v2 or do you want to >>> send it as a separate patch? If that's the case, I tested the same way I did my >>> patch (gcc 10.1.0 and 5.4.0 for cross-compiling, 9.3.0 native): >>> >>> Tested-by: Alexandru Elisei >> Gentle ping regarding this. >> > Hi Alexandru, > > I was on vacation all last week and have been digging myself out of email > today. I'll send this as a proper patch with your T-b later today or > tomorrow. Great, thanks, I was worried my reply might have slipped by unnoticed. Thanks, Alex > > Thanks, > drew > _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm