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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 85FA6C433C1 for ; Sat, 20 Mar 2021 04:49:41 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id ED8336197D for ; Sat, 20 Mar 2021 04:49:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ED8336197D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:42534 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lNTYR-0001Pk-OT for qemu-devel@archiver.kernel.org; Sat, 20 Mar 2021 00:49:39 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:55716) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lNTXb-0000dV-Tj for qemu-devel@nongnu.org; Sat, 20 Mar 2021 00:48:47 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:59326) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lNTXY-0003Bi-FC for qemu-devel@nongnu.org; Sat, 20 Mar 2021 00:48:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616215722; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=DIlC0yFaVwd1Mn2tnr/miENdMF3yBBzUtKisv14gNog=; b=Dwqg8mtTv/D5qR2KeHq5FZSpesTsF3pdjNMIrhOYA7xoSH7h2PXGxiPc8MAchCSufpDmj0 JBlaONF7R7O+Q/mNEyu9azS/2IHs5nyoyqo5/HoLHBphw+t8LOwvpymJtipOuWzPoIigob TA+SRcuxp/6Tzuc6ROQ3kCJOuP7GanI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-312-kVo_TSNeMNemOJyqhuHajw-1; Sat, 20 Mar 2021 00:48:40 -0400 X-MC-Unique: kVo_TSNeMNemOJyqhuHajw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1ED96107ACCA; Sat, 20 Mar 2021 04:48:39 +0000 (UTC) Received: from thuth.remote.csb (ovpn-112-13.ams2.redhat.com [10.36.112.13]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8EBCA6F125; Sat, 20 Mar 2021 04:48:33 +0000 (UTC) Subject: Re: [PATCH] configure: Improve alias attribute check To: Gavin Shan , qemu-devel@nongnu.org References: <20210320042753.69297-1-gshan@redhat.com> From: Thomas Huth Message-ID: <584e6cec-dd1d-7aa5-5f67-43bfcd9ae66a@redhat.com> Date: Sat, 20 Mar 2021 05:48:32 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210320042753.69297-1-gshan@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=thuth@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.251, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: richard.henderson@linaro.org, laurent@vivier.eu, qemu-arm@nongnu.org, shan.gavin@gmail.com, pbonzini@redhat.com, philmd@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 20/03/2021 05.27, Gavin Shan wrote: > It's still possible that the wrong value is returned from the alias > of variable even if the program can be compiled without issue. This > improves the check by executing the binary to check the result. > > If alias attribute can't be working properly, the @target_page in > exec-vary.c will always return zeroes when we have the following gcc > version. > > # gcc --version > gcc (GCC) 11.0.0 20210210 (Red Hat 11.0.0-0) > > This abstracts the code from exec-vary.c and use it as indicator to > enable gcc alias attribute or not. > > Signed-off-by: Gavin Shan > --- > configure | 34 ++++++++++++++++++++++++++++++---- > 1 file changed, 30 insertions(+), 4 deletions(-) > > diff --git a/configure b/configure > index f7d022a5db..8321f380d5 100755 > --- a/configure > +++ b/configure > @@ -75,6 +75,7 @@ fi > > TMPB="qemu-conf" > TMPC="${TMPDIR1}/${TMPB}.c" > +TMPC_B="${TMPDIR1}/${TMPB}_b.c" > TMPO="${TMPDIR1}/${TMPB}.o" > TMPCXX="${TMPDIR1}/${TMPB}.cxx" > TMPE="${TMPDIR1}/${TMPB}.exe" > @@ -4878,13 +4879,38 @@ fi > > attralias=no > cat > $TMPC << EOF > -int x = 1; > +static int x; > extern const int y __attribute__((alias("x"))); > -int main(void) { return 0; } > +extern int read_y(void); > +void write_x(int val); > + > +void write_x(int val) > +{ > + x = val; > +} > + > +int main(void) > +{ > + return read_y(); > +} > EOF > -if compile_prog "" "" ; then > - attralias=yes > +cat > $TMPC_B << EOF > +extern const int y; > +extern void write_x(int val); > +int read_y(void); > + > +int read_y(void) > +{ > + write_x(1); > + return y; > +} > +EOF > + > +TMPC+=" ${TMPC_B}" > +if compile_prog "" "" && ! $TMPE; then What about cross-compiling? Running an executable won't work if QEMU gets cross-compiled... Thomas