Subject: Re: [PATCH] ppc64 ftrace: mark data_access callees "notrace" (pt.1)

From: Torsten Duwe <[email-masked]>
Date: Wed, 20 May 2015 11:03:25 +0200

On Tue, May 19, 2015 at 01:27:07PM +1000, Michael Ellerman wrote:
> On Mon, 2015-05-18 at 14:29 +0200, Jiri Kosina wrote:
> > 
> > ftrace already handles recursion protection by itself (depending on the 
> > per-ftrace-ops FTRACE_OPS_FL_RECURSION_SAFE flag).
> 
> OK, so I wonder why that's not working for us?

IIRC a data access fault happens just before that flag is looked at ;-)

I'm now thinking about a hybrid solution: mark the most critical functions
"notrace", especially those directly involved with MMU loading, and add
a per-thread flag to catch the not-so-obvious cases.

	Torsten