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Date:   Mon, 5 Mar 2018 22:35:50 +0100
From:   Joerg Roedel <joro@8bytes.org>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Brian Gerst <brgerst@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>, Peter Anvin <hpa@zytor.com>,
        the arch/x86 maintainers <x86@kernel.org>,
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        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
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        Denys Vlasenko <dvlasenk@redhat.com>,
        Eduardo Valentin <eduval@amazon.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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        Andrea Arcangeli <aarcange@redhat.com>,
        Waiman Long <llong@redhat.com>, Pavel Machek <pavel@ucw.cz>,
        Joerg Roedel <jroedel@suse.de>
Subject: Re: [PATCH 07/34] x86/entry/32: Restore segments before int registers
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On Mon, Mar 05, 2018 at 12:50:33PM -0800, Linus Torvalds wrote:
> On Mon, Mar 5, 2018 at 12:38 PM, Brian Gerst <brgerst@gmail.com> wrote:
> >
> > There already is a test: single_step_syscall.c
> 
> Ahh, good. So presumably Joerg actually did check it, just didn't even notice ;)

Yeah, sort of. I ran the test, but it didn't catch the failure case in
previous versions which was return to user with kernel-cr3 :)

I could probably add some debug instrumentation to check for that in my
future testing, as there is no NX protection in the user address-range
for the kernel-cr3.


	Joerg