Date: Wed, 10 Mar 2021 17:37:50 +0000 From: Alexander Richardson <arichardson@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: src-committers <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: <CA%2BZ_v8rRkSrKEEbuxpkKmO7wQ=XwtD6ZiCLf78_HwqWu1v%2BZxw@mail.gmail.com> In-Reply-To: <a2743c54-bbcb-73ce-ffaf-ef2b4b6411c4@FreeBSD.org> References: <202103101245.12ACjLn7064810@gitrepo.freebsd.org> <a2743c54-bbcb-73ce-ffaf-ef2b4b6411c4@FreeBSD.org>
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On Wed, 10 Mar 2021 at 17:29, John Baldwin <jhb@freebsd.org> 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 <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. > 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? Alex
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