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=-11.5 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,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 60BEEC433DF for ; Sat, 18 Jul 2020 13:49:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 474B82073A for ; Sat, 18 Jul 2020 13:49:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726627AbgGRNtf (ORCPT ); Sat, 18 Jul 2020 09:49:35 -0400 Received: from foss.arm.com ([217.140.110.172]:43882 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726569AbgGRNtf (ORCPT ); Sat, 18 Jul 2020 09:49:35 -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 4952B12FC; Sat, 18 Jul 2020 06:49:34 -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 AC3B93F718; Sat, 18 Jul 2020 06:49:33 -0700 (PDT) Subject: Re: [kvm-unit-tests PATCH] arm64: Compile with -mno-outline-atomics for GCC >= 10 To: Andrew Jones Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, pbonzini@redhat.com References: <20200717164727.75580-1-alexandru.elisei@arm.com> <20200718091145.zheu46pfjwsntr3a@kamzik.brq.redhat.com> From: Alexandru Elisei Message-ID: <202d475d-95df-2350-a8e9-9264144993ac@arm.com> Date: Sat, 18 Jul 2020 14:50:19 +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: <20200718091145.zheu46pfjwsntr3a@kamzik.brq.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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 Thanks, Alex 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=-11.5 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,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 5ED98C433E2 for ; Sat, 18 Jul 2020 13:49:39 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id CDBCF2073A for ; Sat, 18 Jul 2020 13:49:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CDBCF2073A 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 299BF4B15D; Sat, 18 Jul 2020 09:49:38 -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 SYyjWoVIoeAF; Sat, 18 Jul 2020 09:49:36 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id DE8F24B141; Sat, 18 Jul 2020 09:49:36 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 4C4C14B141 for ; Sat, 18 Jul 2020 09:49:36 -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 CHShZ7zAS91x for ; Sat, 18 Jul 2020 09:49:34 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mm01.cs.columbia.edu (Postfix) with ESMTP id CBC514B113 for ; Sat, 18 Jul 2020 09:49:34 -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 4952B12FC; Sat, 18 Jul 2020 06:49:34 -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 AC3B93F718; Sat, 18 Jul 2020 06:49:33 -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> From: Alexandru Elisei Message-ID: <202d475d-95df-2350-a8e9-9264144993ac@arm.com> Date: Sat, 18 Jul 2020 14:50:19 +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: <20200718091145.zheu46pfjwsntr3a@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, 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 Thanks, Alex _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm