From: Peter Zijlstra <peterz@infradead.org>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Andi Kleen <andi@firstfloor.org>,
pjt@google.com, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, gregkh@linux-foundation.org,
tim.c.chen@linux.intel.com, dave.hansen@intel.com,
tglx@linutronix.de, luto@amacapital.net,
Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH] x86/retpoline: Also fill return buffer after idle
Date: Tue, 9 Jan 2018 15:12:15 +0100 [thread overview]
Message-ID: <20180109141215.GJ6176@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1515506318.22302.46.camel@infradead.org>
On Tue, Jan 09, 2018 at 01:58:38PM +0000, David Woodhouse wrote:
> Clever GCC, have biscuit.
Well, we requested this feature exactly because of this. It had better
work.
> However, you are suggesting that we turn the static_cpu_has() trick
> from a "nice to have" optimisation which is all very well when it pans
> out, to something we *rely* on for secure operation of the system.
It must work, we 'rely' on it already. GCC doing something stupid there
is a GCC bug. Any GCC bug is a royal pain, they happen, life goes on.
> It never ends well when we rely on all versions of GCC optimising
> things precisely how we want.
>
> If you can build in a sanity check to ensure that the build will *fail*
> when GCC doesn't do what we want, I suppose we could live with that.
> But we don't have such a sanity check at the moment, do we?
We have STATIC_KEYS_SELFTEST, which might or might not qualify.
prev parent reply other threads:[~2018-01-09 14:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-08 23:51 Andi Kleen
2018-01-09 0:00 ` David Woodhouse
2018-01-09 0:24 ` Andi Kleen
2018-01-09 0:28 ` David Woodhouse
2018-01-09 9:37 ` Peter Zijlstra
2018-01-09 13:58 ` David Woodhouse
2018-01-09 14:12 ` Peter Zijlstra [this message]
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