linux-kernel - Re: [PATCH 35/35] x86/cpufeatures: Limit shadow stack to Intel CPUs

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Message-ID: <Yf2m1ETkcRpk3v+u@dell9853host>
Date:   Fri, 4 Feb 2022 16:21:08 -0600
From:   John Allen <john.allen@....com>
To:     "H.J. Lu" <hjl.tools@...il.com>
Cc:     Rick Edgecombe <rick.p.edgecombe@...el.com>,
        the arch/x86 maintainers <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>,
        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>,
        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>,
        Dave Martin <Dave.Martin@....com>,
        Weijiang Yang <weijiang.yang@...el.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        joao.moreira@...el.com, Kostya Serebryany <kcc@...gle.com>,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 35/35] x86/cpufeatures: Limit shadow stack to Intel CPUs

On Thu, Feb 03, 2022 at 02:23:43PM -0800, H.J. Lu wrote:
> On Thu, Feb 3, 2022 at 1:58 PM John Allen <john.allen@....com> wrote:
> >
> > On Sun, Jan 30, 2022 at 01:18:38PM -0800, Rick Edgecombe wrote:
> > > Shadow stack is supported on newer AMD processors, but the kernel
> > > implementation has not been tested on them. Prevent basic issues from
> > > showing up for normal users by disabling shadow stack on all CPUs except
> > > Intel until it has been tested. At which point the limitation should be
> > > removed.
> >
> > Hi Rick,
> >
> > I have been testing Yu-Cheng's patchsets on AMD hardware and I am
> > working on testing this version now. How are you testing this new
> > series? I can partially test by calling the prctl enable for shadow
> > stack directly from a program, but I'm not sure how useful that's going
> > to be without the glibc support. Do you have a public repo with the
> > necessary glibc changes to enable shadow stack early?
> >
> 
> The glibc CET branch is at
> 
> https://gitlab.com/x86-glibc/glibc/-/commits/users/hjl/cet/master

Thanks, I ran some smoke tests with the updated glibc and it's looking
good so far. Additionally, I ran the new kselftest and it passed.

Thanks,
John

> 
> -- 
> H.J.