From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <owner-linux-mm@kvack.org>
Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200])
	by kanga.kvack.org (Postfix) with ESMTP id BD0286B000D
	for <linux-mm@kvack.org>; Mon,  5 Mar 2018 16:35:53 -0500 (EST)
Received: by mail-wr0-f200.google.com with SMTP id q15so11862675wra.22
        for <linux-mm@kvack.org>; Mon, 05 Mar 2018 13:35:53 -0800 (PST)
Received: from theia.8bytes.org (8bytes.org. [2a01:238:4383:600:38bc:a715:4b6d:a889])
        by mx.google.com with ESMTPS id u7si1575029edb.449.2018.03.05.13.35.51
        for <linux-mm@kvack.org>
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Mon, 05 Mar 2018 13:35:51 -0800 (PST)
Date: Mon, 5 Mar 2018 22:35:50 +0100
From: Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH 07/34] x86/entry/32: Restore segments before int registers
Message-ID: <20180305213550.GV16484@8bytes.org>
References: <1520245563-8444-1-git-send-email-joro@8bytes.org>
 <1520245563-8444-8-git-send-email-joro@8bytes.org>
 <CA+55aFym-18UbD5K3n1Ki=mvpuLqa7E6E=qG0aE-dctzTap_WQ@mail.gmail.com>
 <20180305131231.GR16484@8bytes.org>
 <CA+55aFwn5EkHTfrUFww54CDWovoUornv6rSrao43agbLBQD6-Q@mail.gmail.com>
 <CAMzpN2hscOXJFzm07Hk=2Ttr3wQFSisxP=EZhRMtAU6xSm8zSw@mail.gmail.com>
 <CA+55aFwxiZ9bD2Zu5xV0idz_dDctPvrrWA2r54+NL4aj9oeN8Q@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CA+55aFwxiZ9bD2Zu5xV0idz_dDctPvrrWA2r54+NL4aj9oeN8Q@mail.gmail.com>
Sender: owner-linux-mm@kvack.org
List-ID: <linux-mm.kvack.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>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>, Andrew Lutomirski <luto@kernel.org>, Dave Hansen <dave.hansen@intel.com>, Josh Poimboeuf <jpoimboe@redhat.com>, =?iso-8859-1?Q?J=FCrgen_Gro=DF?= <jgross@suse.com>, Peter Zijlstra <peterz@infradead.org>, Borislav Petkov <bp@alien8.de>, Jiri Kosina <jkosina@suse.cz>, Boris Ostrovsky <boris.ostrovsky@oracle.com>, David Laight <David.Laight@aculab.com>, Denys Vlasenko <dvlasenk@redhat.com>, Eduardo Valentin <eduval@amazon.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Will Deacon <will.deacon@arm.com>, "Liguori, Anthony" <aliguori@amazon.com>, Daniel Gruss <daniel.gruss@iaik.tugraz.at>, Hugh Dickins <hughd@google.com>, Kees Cook <keescook@google.com>, Andrea Arcangeli <aarcange@redhat.com>, Waiman Long <llong@redhat.com>, Pavel Machek <pavel@ucw.cz>, Joerg Roedel <jroedel@suse.de>

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

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>