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Date: Wed, 21 Dec 2011 13:46:01 +0200
From: Gleb Natapov <gleb@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Joerg Roedel <joro@8bytes.org>, Avi Kivity <avi@redhat.com>,
        Robert Richter <robert.richter@amd.com>,
        Benjamin Block <bebl@mageta.org>,
        Hans Rosenfeld <hans.rosenfeld@amd.com>, hpa@zytor.com,
        tglx@linutronix.de, suresh.b.siddha@intel.com, eranian@google.com,
        brgerst@gmail.com, Andreas.Herrmann3@amd.com, x86@kernel.org,
        linux-kernel@vger.kernel.org, Benjamin Block <benjamin.block@amd.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC 4/5] x86, perf: implements lwp-perf-integration (rc1)
Message-ID: <20111221114601.GA2446@redhat.com>
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On Tue, Dec 20, 2011 at 07:40:04PM +0100, Ingo Molnar wrote:
> > The point is, if user-space re-programs LWP it will continue 
> > to write its samples to the new ring-buffer virtual-address 
> > set up by user-space. It will still use that virtual address 
> > in another address-space after a task-switch. This allows 
> > processes to corrupt memory of other processes. [...]
> 
> That's nonsense. As i said it my previous mail the LWPC should 
> be per task and switched on task switch - just like the DS/PEBS 
> context is.
> 
Is it? Looking at arch/x86/kernel/cpu/perf_event_intel_ds.c it seems
like DS is per cpu, not per task.

--
			Gleb.