Date: Wed, 10 Mar 2021 09:29:51 -0800 From: John Baldwin <jhb@FreeBSD.org> To: Alex Richardson <arichardson@FreeBSD.org>, src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: Re: git: 953a7d7c61f3 - main - Arch64: Clear VFP state on execve() Message-ID: <a2743c54-bbcb-73ce-ffaf-ef2b4b6411c4@FreeBSD.org> In-Reply-To: <202103101245.12ACjLn7064810@gitrepo.freebsd.org> References: <202103101245.12ACjLn7064810@gitrepo.freebsd.org>
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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 <arichardson@FreeBSD.org> > AuthorDate: 2021-03-09 19:11:40 +0000 > Commit: Alex Richardson <arichardson@FreeBSD.org> > 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. -- John Baldwin
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