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Date: Fri, 5 Aug 2016 17:54:42 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>, jolsa@kernel.org,
        Ingo Molnar <mingo@redhat.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
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	<linux-arm-kernel@lists.infradead.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>
Subject: Re: [PATCH V3 1/6] perf/core: Adding PMU driver specific
 configuration
Message-ID: <20160805155442.GW6879@twins.programming.kicks-ass.net>
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On Fri, Aug 05, 2016 at 09:41:15AM -0600, Mathieu Poirier wrote:
> On 4 August 2016 at 10:59, Peter Zijlstra <peterz@infradead.org> wrote:
> > On Thu, Jul 28, 2016 at 03:42:18PM -0600, Mathieu Poirier wrote:
> >> This patch somewhat mimics the work done on address filters to
> >> add the infrastructure needed to pass PMU specific HW
> >> configuration to the driver before a session starts.
> >
> > I'm thinking we want to specify a syntax and validate the string matches
> > the syntax in the generic code.
> 
> The syntax is checked in the lexer making sure that nothing other than
> @cfg or @cfg=config is sent to the kernel.  From there validation is
> done in the PMU driver that implements the set_drv_configs()
> interface.
> 
> I am not sure to get you point here - can I ask you to provide more details?

What keeps random userspace from sending malformed strings in? There's
more userspace than just the perf tool.

The kernel needs to validate structure.