Re: [tip:perfcounters/core] perf_counter: x86: Fix call-chain supportto use NMI-safe methods

From: H. Peter Anvin
Date: Tue Jun 16 2009 - 14:38:23 EST

Mathieu Desnoyers wrote:
> With respect to cr2, yes, this is the only window we care about.
> However, the rest of vmalloc_fault() must be audited for other non
> nmi-suitable data structure use (e.g. "current"), which I did in the
> past.
> My intent was just to respond to Peter's concerns by showing that the
> part of page fault handler which needs to be NMI-reentrant is really not
> that big.

Even if that is true now, you want it to be true for all future time,
and all to support an out-of-tree piece of code. All of this is
virtually impossible to test for without said out-of-tree piece of code,
so I will object to it anyway.


H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

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