Re: [tip:x86/urgent] x86, trace: Fix CR2 corruption when tracing page faults

[Peter Zijlstra]

On Wed, Mar 05, 2014 at 01:54:21PM +0100, Peter Zijlstra wrote:
> On Wed, Mar 05, 2014 at 07:33:44AM -0500, Steven Rostedt wrote:
> > Then we better make sure that __do_page_fault() is never inlined.
> > Otherwise, it wont be available to trace.
> > 
> > I'm fine with adding "notrace" to do_page_fault() and to
> > trace_do_page_fault() as long as we also include a "noinline" to
> > __do_page_fault(). Would need a comment stating why that noinline is
> > there though.
> 
> When CONFIG_TRACING there's two callers, which makes it highly unlikely
> GCC would inline the massive __do_page_fault() function, but sure.
> 
> How about something like so then; still has the normal_do_page_fault()
> thing, although I suppose we could drop that.
> 
> It also puts trace_page_fault_entries() and trace_do_page_fault() under
> CONFIG_TRACING. I could only find the entry_32.S user; I suppose the
> 64bit one is hidden by CPP goo somewhere?

> +trace_errorentry page_fault normal_do_page_fault

ah found it; its in there. That also means the normal_do_page_fault()
thing won't actually compile proper.

Lemme do one with that.
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