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Message-ID: <a862be68-dc81-6db5-c79b-5bbd87ccddaf@intel.com>
Date: Wed, 23 Sep 2020 15:20:27 -0700
From: "Yu, Yu-cheng" <yu-cheng.yu@...el.com>
To: Dave Hansen <dave.hansen@...el.com>,
Sean Christopherson <sean.j.christopherson@...el.com>,
Andy Lutomirski <luto@...nel.org>
Cc: X86 ML <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
LKML <linux-kernel@...r.kernel.org>,
"open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
Linux-MM <linux-mm@...ck.org>,
linux-arch <linux-arch@...r.kernel.org>,
Linux API <linux-api@...r.kernel.org>,
Arnd Bergmann <arnd@...db.de>,
Balbir Singh <bsingharora@...il.com>,
Borislav Petkov <bp@...en8.de>,
Cyrill Gorcunov <gorcunov@...il.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Eugene Syromiatnikov <esyr@...hat.com>,
Florian Weimer <fweimer@...hat.com>,
"H.J. Lu" <hjl.tools@...il.com>, Jann Horn <jannh@...gle.com>,
Jonathan Corbet <corbet@....net>,
Kees Cook <keescook@...omium.org>,
Mike Kravetz <mike.kravetz@...cle.com>,
Nadav Amit <nadav.amit@...il.com>,
Oleg Nesterov <oleg@...hat.com>, Pavel Machek <pavel@....cz>,
Peter Zijlstra <peterz@...radead.org>,
Randy Dunlap <rdunlap@...radead.org>,
"Ravi V. Shankar" <ravi.v.shankar@...el.com>,
Vedvyas Shanbhogue <vedvyas.shanbhogue@...el.com>,
Dave Martin <Dave.Martin@....com>,
Weijiang Yang <weijiang.yang@...el.com>
Subject: Re: [PATCH v12 8/8] x86: Disallow vsyscall emulation when CET is
enabled
On 9/23/2020 3:08 PM, Dave Hansen wrote:
> On 9/23/20 3:06 PM, Yu, Yu-cheng wrote:
>> I think I'll add a check here for (r + 8) >= TASK_SIZE_MAX. It is
>> better than getting a fault.
>
> There's also wrmsr_safe().
>
Yes, thanks.
Since I am going to change this to:
fpu__prepare_write(), then write to the XSAVES area.
The kernel does not expect XRSTORS to fail ("Bad FPU state detected..."
message). So maybe still check the address first.
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