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Subject: Re: [PATCH 0/4] x86-64: fix vclock_gettime()
From: Petr Tesarik <ptesarik@suse.cz>
To: Andi Kleen <andi@firstfloor.org>
Cc: linux-kernel@vger.kernel.org, linux-x86_64@vger.kernel.org, mingo@elte.hu,
       zwane@arm.linux.org.uk
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Date: Thu, 14 May 2009 16:27:40 +0200
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Andi Kleen píše v Čt 14. 05. 2009 v 16:02 +0200:
> > Sorry, this doesn't work, because the function is inlined. And even if
> > it wasn't, the vDSO must be self-contained by definition. User-space
> > cannot simply call into kernel-space.
> 
> Wrong, it can call into vsyscall space.

Ah, yes, you're right. The vsyscall is always mapped and it is a special
case for the instruction replacement code already.

So, is there any reason not to put the rdtsc_barrier() around
vget_cycles() in vread_tsc() ?

Petr Tesarik