Re: [PATCH 0/4] x86-64: fix vclock_gettime()

From: Petr Tesarik
Date: Thu May 14 2009 - 10:27:53 EST


Andi Kleen pÃÅe v Ät 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


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