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Date: Wed, 13 Oct 2010 16:47:36 +0200
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Paul Mackerras <paulus@samba.org>,
        Stephane Eranian <eranian@google.com>,
        Cyrill Gorcunov <gorcunov@openvz.org>,
        Tom Zanussi <tzanussi@gmail.com>,
        Masami Hiramatsu <mhiramat@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Robert Richter <robert.richter@amd.com>
Subject: Re: [RFC PATCH 1/9] uaccess: Make copy_from_user_nmi() globally
	available
Message-ID: <20101013144734.GB5335@nowhere>
References: <1286946421-32202-1-git-send-regression-fweisbec@gmail.com> <1286946421-32202-2-git-send-regression-fweisbec@gmail.com> <1286954156.29097.53.camel@twins>
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On Wed, Oct 13, 2010 at 09:15:56AM +0200, Peter Zijlstra wrote:
> On Wed, 2010-10-13 at 07:06 +0200, Frederic Weisbecker wrote:
> > In order to support user stack dump safely in perf samples from
> > generic code, export copy_from_user_nmi() from x86 and make it
> > generally available. For most archs it will map to
> > copy_from_user_inatomic, but for x86 we need to take care of
> > not faulting from NMIs.
> > 
> > Since perf is the first user for now, let the overriden x86
> > implementation in the perf source file.
> 
> It might make sense to call it copy_from_user_gup() because that's
> bascially what it does, it doesn't rely on NMI context anymore, its just
> NMI-safe.
> 
> Its a best effort software page table walk, and with the stacked
> kmap_atomic bits Andrew took it should work from any context.


Ok, I'll do the rename. Does that work on any arch?

Thanks.