From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Rik van Riel <riel@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Lutomirski <luto@kernel.org>,
dave.hansen@intel.linux.com, Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH RFC 1/3] fpu/x86: add make_fpregs_active(_newstate) helper functions
Date: Mon, 17 Oct 2016 16:04:17 -0700 [thread overview]
Message-ID: <20161017230416.GA18900@test-lenovo> (raw)
In-Reply-To: <CALCETrUKOF3PxUBXJ0xMwDdooCwv2R9Eso24kcb0mm1ZYYYdzg@mail.gmail.com>
On Mon, Oct 17, 2016 at 01:57:06PM -0700, Andy Lutomirski wrote:
> Dave and/or Yu-cheng: didn't one of you have some code to allow a user
> xstate buffer to be filled from the copy in kernel memory? If we did
> that, we could avoid this mess entirely.
In copy_fpstate_to_sigframe() (arch/x86/kernel/fpu/signal.c), the
assumption was we have lazy fpu:
if (fpregs_active() || we want an #NM exception)
copy_fpregs_to_sigframe();
else
copy kernel buffer to user buffer;
But this is not the true anymore. Or do you mean something else?
-- Yu-cheng
next prev parent reply other threads:[~2016-10-17 23:05 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-17 20:09 [PATCH RFC 0/3] x86/fpu: defer FPU state loading until return to userspace riel
2016-10-17 20:09 ` [PATCH RFC 1/3] fpu/x86: add make_fpregs_active(_newstate) helper functions riel
2016-10-17 20:57 ` Andy Lutomirski
2016-10-17 23:04 ` Yu-cheng Yu [this message]
2016-10-17 23:30 ` Andy Lutomirski
2016-10-17 23:45 ` Yu-cheng Yu
2016-10-18 1:23 ` Andy Lutomirski
2016-10-17 20:09 ` [PATCH RFC 2/3] x86/fpu: prepare misc FPU state handling code for lazy FPU loading riel
2016-10-17 20:09 ` [PATCH RFC 3/3] x86/fpu: defer FPU state load until return to userspace riel
2016-10-17 20:58 ` Andy Lutomirski
2016-10-18 0:06 ` Rik van Riel
2016-10-18 7:58 ` [PATCH RFC 0/3] x86/fpu: defer FPU state loading " Ingo Molnar
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