Closing on the CR2 leak bug

Closing on the CR2 leak bug

[H. Peter Anvin]

So we need to get something into x86/urgent for the CR2 bug.

It seems like a no-brainer to do the hoisting patch, for which I prefer
the version proposed by Jiri Olsa which reads %cr2 and then passes it to
__do_page_fault() in a GPR:

http://lkml.kernel.org/r/20140228160526.GD1133@krava.brq.redhat.com

As fart as I can tell this should fix Vince's problem as well.

Anyone who objects to this?  Otherwise I will put it in tip:x86/urgent
tomorrow.

Do we need any more refinements this late in the -rc cycle?

	-hpa

Re: Closing on the CR2 leak bug

[Steven Rostedt]

On Tue, 04 Mar 2014 14:34:00 -0800
"H. Peter Anvin" <hpa@zytor.com> wrote:

> So we need to get something into x86/urgent for the CR2 bug.
> 
> It seems like a no-brainer to do the hoisting patch, for which I prefer
> the version proposed by Jiri Olsa which reads %cr2 and then passes it to
> __do_page_fault() in a GPR:
> 
> http://lkml.kernel.org/r/20140228160526.GD1133@krava.brq.redhat.com
> 
> As fart as I can tell this should fix Vince's problem as well.
> 
> Anyone who objects to this?  Otherwise I will put it in tip:x86/urgent
> tomorrow.
> 
> Do we need any more refinements this late in the -rc cycle?
> 

The only other issue is if perf traces from function context and traces
the trace_do_page_fault() call. But other than that, sure, take Jiri's
patch.

Acked-by: Steven Rostedt <rostedt@goodmis.org>

Please also add the reported/tested-by from Vince Weaver and add a
Link: to the other thread, as it got pretty detailed there too.


 -- Steve

Re: Closing on the CR2 leak bug

[H. Peter Anvin]

On 03/04/2014 03:41 PM, Steven Rostedt wrote:
> 
> The only other issue is if perf traces from function context and traces
> the trace_do_page_fault() call. But other than that, sure, take Jiri's
> patch.
> 

Is there a known codepath on which that can happen?

	-hpa

Re: Closing on the CR2 leak bug

[Steven Rostedt]

On Tue, 04 Mar 2014 15:44:26 -0800
"H. Peter Anvin" <hpa@zytor.com> wrote:

> On 03/04/2014 03:41 PM, Steven Rostedt wrote:
> > 
> > The only other issue is if perf traces from function context and traces
> > the trace_do_page_fault() call. But other than that, sure, take Jiri's
> > patch.
> > 
> 
> Is there a known codepath on which that can happen?

I'm not sure. Jiri, is there a way we can trace userspace from
the ftrace function event? What would be the command to try? I know you
had a patch to prevent it, but is it currently possible?

-- Steve