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 0EE30C433E3 for ; Mon, 27 Jul 2020 12:20:17 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 9180D2074F for ; Mon, 27 Jul 2020 12:20:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9180D2074F 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 0A8954B9F0; Mon, 27 Jul 2020 08:20:16 -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 5t-8g+U+5+8k; Mon, 27 Jul 2020 08:20:14 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 958084B9F3; Mon, 27 Jul 2020 08:20:14 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id AB21D4B9F1 for ; Mon, 27 Jul 2020 08:20:13 -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 1T4lxCo6PV3o for ; Mon, 27 Jul 2020 08:20:12 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 2658E4B9F0 for ; Mon, 27 Jul 2020 08:20:12 -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 AA11C30E; Mon, 27 Jul 2020 05:20:11 -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 1B4F93F66E; Mon, 27 Jul 2020 05:20:10 -0700 (PDT) Subject: Re: [kvm-unit-tests PATCH] arm64: Compile with -mno-outline-atomics for GCC >= 10 From: Alexandru Elisei To: Andrew Jones References: <20200717164727.75580-1-alexandru.elisei@arm.com> <20200718091145.zheu46pfjwsntr3a@kamzik.brq.redhat.com> <202d475d-95df-2350-a8e9-9264144993ac@arm.com> Message-ID: <1bf2eab6-c6df-8b4c-b365-7216e7b9a9d7@arm.com> Date: Mon, 27 Jul 2020 13:21:03 +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: <202d475d-95df-2350-a8e9-9264144993ac@arm.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 7/18/20 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. Thanks, Alex _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm