On 3/10/21 9:37 AM, Alexander Richardson wrote:
On Wed, 10 Mar 2021 at 17:29, John Baldwin <j...@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 <arichard...@freebsd.org>
AuthorDate: 2021-03-09 19:11:40 +0000
Commit: Alex Richardson <arichard...@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?
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
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