From: David Woodhouse <dwmw2@infradead.org>
To: Andy Lutomirski <luto@amacapital.net>,
Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Jon Masters <jcm@jonmasters.org>,
Henrique de Moraes Holschuh <hmh@hmh.eng.br>,
Andi Kleen <andi@firstfloor.org>,
tglx@linutronix.de, x86@kernel.org, linux-kernel@vger.kernel.org,
pjt@google.com, torvalds@linux-foundation.org,
gregkh@linux-foundation.org, peterz@infradead.org,
thomas.lendacky@amd.com, arjan.van.de.ven@intel.com
Subject: Re: Improve retpoline for Skylake
Date: Mon, 15 Jan 2018 19:07:52 +0100 [thread overview]
Message-ID: <1516039672.4937.13.camel@infradead.org> (raw)
In-Reply-To: <AEECA9A9-9A42-4A44-81D4-88F4C74E11E8@amacapital.net>
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On Mon, 2018-01-15 at 10:06 -0800, Andy Lutomirski wrote:
>
> > Refill or not, you are aware that a correctly timed SMI in a leaf
> > function will cause the next ret to speculate into userspace, because
> > there is guaranteed peturbance in the RSB? (On the expectation that the
> > SMM handler isn't entirely devoid of function calls).
>
> Couldn't firmware fill the RSB with a some known safe address, maybe
> even 0, and then immediately do RSM?
Why don't we just unconditionally declare that *all* firmware that uses
SMI for anything at all is broken?
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next prev parent reply other threads:[~2018-01-15 18:08 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-12 18:45 Improve retpoline for Skylake Andi Kleen
2018-01-12 18:45 ` [PATCH 1/4] x86/retpoline: Add new mode RETPOLINE_UNDERFLOW Andi Kleen
2018-01-12 22:13 ` Dominik Brodowski
2018-01-12 22:57 ` Andi Kleen
2018-01-12 18:45 ` [PATCH 2/4] x86/retpoline: Avoid return buffer underflows on context switch Andi Kleen
2018-01-12 18:45 ` [PATCH 3/4] x86/retpoline: Fill return buffer after idle Andi Kleen
2018-01-12 18:45 ` [PATCH 4/4] x86/retpoline: Fill return buffer on interrupt return to kernel Andi Kleen
2018-01-12 19:12 ` Improve retpoline for Skylake David Woodhouse
2018-01-12 19:21 ` Andi Kleen
2018-01-12 22:03 ` Henrique de Moraes Holschuh
2018-01-15 8:26 ` Jon Masters
2018-01-15 9:06 ` David Woodhouse
2018-01-15 10:03 ` Thomas Gleixner
2018-01-15 10:20 ` David Woodhouse
2018-01-15 16:57 ` Andy Lutomirski
2018-01-15 17:38 ` Andrew Cooper
2018-01-15 17:56 ` Van De Ven, Arjan
2018-01-15 18:06 ` Andy Lutomirski
2018-01-15 18:07 ` David Woodhouse [this message]
2018-01-15 18:10 ` Andy Lutomirski
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