From owner-dev-commits-src-main@freebsd.org Wed Mar 10 19:19:27 2021 Return-Path: Delivered-To: dev-commits-src-main@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id C3DB45749DD; Wed, 10 Mar 2021 19:19:27 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from smtp.freebsd.org (smtp.freebsd.org [96.47.72.83]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4Dwhhv5D9Wz4YJj; Wed, 10 Mar 2021 19:19:27 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from John-Baldwins-MacBook-Pro.local (ralph.baldwin.cx [66.234.199.215]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) (Authenticated sender: jhb) by smtp.freebsd.org (Postfix) with ESMTPSA id 2E53E3F2D; Wed, 10 Mar 2021 19:19:27 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Subject: Re: git: 953a7d7c61f3 - main - Arch64: Clear VFP state on execve() To: Alexander Richardson Cc: src-committers , dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org References: <202103101245.12ACjLn7064810@gitrepo.freebsd.org> From: John Baldwin Message-ID: Date: Wed, 10 Mar 2021 11:19:26 -0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: dev-commits-src-main@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commit messages for the main branch of the src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 10 Mar 2021 19:19:27 -0000 On 3/10/21 9:37 AM, Alexander Richardson wrote: > On Wed, 10 Mar 2021 at 17:29, John Baldwin wrote: >> >> On 3/10/21 4:45 AM, Alex Richardson wrote: >>> The branch main has been updated by arichardson: >>> >>> URL: https://cgit.FreeBSD.org/src/commit/?id=953a7d7c61f3b2f5351dfe668510ec782ae282e8 >>> >>> commit 953a7d7c61f3b2f5351dfe668510ec782ae282e8 >>> Author: Alex Richardson >>> AuthorDate: 2021-03-09 19:11:40 +0000 >>> Commit: Alex Richardson >>> CommitDate: 2021-03-10 12:44:42 +0000 >>> >>> Arch64: Clear VFP state on execve() >>> >>> I noticed that many of the math-related tests were failing on AArch64. >>> After a lot of debugging, I noticed that the floating point exception flags >>> were not being reset when starting a new process. This change resets the >>> VFP inside exec_setregs() to ensure no VFP register state is leaked from >>> parent processes to children. >>> >>> This commit also moves the clearing of fpcr that was added in 65618fdda0f27 >>> from fork() to execve() since that makes more sense: fork() can retain >>> current register values, but execve() should result in a well-defined >>> clean state. >>> >>> Reviewed By: andrew >>> MFC after: 1 week >>> Differential Revision: https://reviews.freebsd.org/D29060 >> >> FYI, cpu_thread_copy() should copy the creating thread's state to the new thread, >> not reset it. POSIX actually says that new threads inherit the "floating point >> environment" from the creating thread for pthread_create(). I have a patch I'm >> testing to fix thix for x86. >> > > I believe sv_setregs is only called for execve() not for new threads? > cpu_copy_thread() is not affected by this patch and I see it does a > bcopy(td0->td_pcb, td->td_pcb, sizeof(struct pcb)); so should be fine? Ah, I thought you touched cpu_copy_thread() as well. I do think cpu_copy_thread() resets some pcb flags which might be the thing to fix (it's what I have to fix for x86 which was copying the state, but then clearing the INITDONE flags such that the copied state was always overwritten by the trap on first use) -- John Baldwin