[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <202301191646.E739868F@keescook>
Date: Thu, 19 Jan 2023 16:46:24 -0800
From: Kees Cook <keescook@...omium.org>
To: Rick Edgecombe <rick.p.edgecombe@...el.com>
Cc: x86@...nel.org, "H . Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
linux-doc@...r.kernel.org, linux-mm@...ck.org,
linux-arch@...r.kernel.org, linux-api@...r.kernel.org,
Arnd Bergmann <arnd@...db.de>,
Andy Lutomirski <luto@...nel.org>,
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>,
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>,
Weijiang Yang <weijiang.yang@...el.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
John Allen <john.allen@....com>, kcc@...gle.com,
eranian@...gle.com, rppt@...nel.org, jamorris@...ux.microsoft.com,
dethoma@...rosoft.com, akpm@...ux-foundation.org,
Andrew.Cooper3@...rix.com, christina.schimpe@...el.com,
Yu-cheng Yu <yu-cheng.yu@...el.com>
Subject: Re: [PATCH v5 04/39] x86/cpufeatures: Enable CET CR4 bit for shadow
stack
On Thu, Jan 19, 2023 at 01:22:42PM -0800, Rick Edgecombe wrote:
> From: Yu-cheng Yu <yu-cheng.yu@...el.com>
>
> Setting CR4.CET is a prerequisite for utilizing any CET features, most of
> which also require setting MSRs.
>
> Kernel IBT already enables the CET CR4 bit when it detects IBT HW support
> and is configured with kernel IBT. However, future patches that enable
> userspace shadow stack support will need the bit set as well. So change
> the logic to enable it in either case.
>
> Clear MSR_IA32_U_CET in cet_disable() so that it can't live to see
> userspace in a new kexec-ed kernel that has CR4.CET set from kernel IBT.
>
> Tested-by: Pengfei Xu <pengfei.xu@...el.com>
> Tested-by: John Allen <john.allen@....com>
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@...el.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
--
Kees Cook
Powered by blists - more mailing lists