linux-kernel - [PATCH 0/4] ppc64 ftrace implementation

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Message-ID: <20150603130257.GA19424@lst.de>
Date:	Wed, 3 Jun 2015 15:02:57 +0200
From:	Torsten Duwe <duwe@....de>
To:	Michael Ellerman <mpe@...erman.id.au>,
	ppc-dev <linuxppc-dev@...ts.ozlabs.org>
Cc:	Jiri Kosina <jkosina@...e.cz>,
	Steven Rostedt <rostedt@...dmis.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH 0/4] ppc64 ftrace implementation

On Tue, May 19, 2015 at 11:52:47AM +0200, Jiri Kosina wrote:
> On Tue, 19 May 2015, Michael Ellerman 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?
> 
> The situation when traced function recurses to itself is different from 
> the situation when tracing core infrastrcuture would recurse to itself 
> while performing tracing.

I have used this inspiration to add a catch-all parachute for ftrace_caller,
see my last reply. It reappears here as patch 4/4. Expect noticable performance
impact compared to the selected "notrace" attributation discussed here. This should
still be done in a second step especially for the hardware assistance functions
I mentioned.

	Torsten


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