From: Andi Kleen <andi@firstfloor.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
Andi Kleen <andi@firstfloor.org>, X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH 4/7] x86: Add support for rd/wr fs/gs base
Date: Thu, 1 May 2014 23:15:54 +0200 [thread overview]
Message-ID: <20140501211554.GH2382@two.firstfloor.org> (raw)
In-Reply-To: <CALCETrVQiZPb1M183Fq61dbFAjnJScuB2y+rdH8BQ+yp-MO+Mw@mail.gmail.com>
> If usergs == kernelgs, then ebx will always be 1 and we'll never end
> up in paranoid_userspace.
You may miss a reschedule in this obscure case. It shouldn't really
happen because loading a kernel pointer is not useful for user space.
Doesn't seem like a real issue to me.
We only happen need to handle it to avoid crashing.
> Alternatively, what if the paranoid entry checked whether we're coming
> from userspace at the very beginning and, if so, just jumped to the
> non-paranoid entry?
That would work, but I doubt it would be worth it.
-Andi
next prev parent reply other threads:[~2014-05-01 21:15 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-28 22:12 Add support for RD/WR FS/GSBASE Andi Kleen
2014-04-28 22:12 ` [PATCH 1/7] percpu: Add a DEFINE_PER_CPU_2PAGE_ALIGNED Andi Kleen
2014-05-02 15:18 ` Tejun Heo
2014-04-28 22:12 ` [PATCH 2/7] x86: Naturally align the debug IST stack Andi Kleen
2014-04-28 22:12 ` [PATCH 3/7] x86: Add C intrinsics for new rd/wr fs/gs base instructions Andi Kleen
2014-04-29 14:10 ` Konrad Rzeszutek Wilk
2014-04-28 22:12 ` [PATCH 4/7] x86: Add support for rd/wr fs/gs base Andi Kleen
2014-04-29 18:19 ` Andy Lutomirski
2014-04-29 23:39 ` Andi Kleen
2014-04-30 4:52 ` H. Peter Anvin
2014-04-30 4:57 ` H. Peter Anvin
2014-04-30 23:44 ` Andy Lutomirski
2014-04-30 23:47 ` Andy Lutomirski
2014-05-01 21:15 ` Andi Kleen [this message]
2014-05-01 21:39 ` Andy Lutomirski
2014-05-01 21:51 ` Andi Kleen
2014-05-01 21:53 ` Andy Lutomirski
2014-05-01 21:58 ` H. Peter Anvin
2014-05-01 22:06 ` Andy Lutomirski
2014-05-01 22:18 ` Andi Kleen
2014-05-01 22:45 ` H. Peter Anvin
2014-04-28 22:12 ` [PATCH 5/7] x86: Make old K8 swapgs workaround conditional Andi Kleen
2014-04-30 4:57 ` H. Peter Anvin
2014-04-28 22:12 ` [PATCH 6/7] x86: Enumerate kernel FSGS capability in AT_HWCAP2 Andi Kleen
2014-04-28 22:12 ` [PATCH 7/7] x86: Add documentation for rd/wr fs/gs base Andi Kleen
2014-04-29 2:23 ` Randy Dunlap
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