From mboxrd@z Thu Jan  1 00:00:00 1970
From: dave.martin@linaro.org (Dave Martin)
Date: Fri, 25 Jan 2013 17:22:24 +0000
Subject: [PATCH 19/19] [INCOMPLETE] ARM: make return_address available
 for ARM_UNWIND
In-Reply-To: <1359133703.21576.233.camel@gandalf.local.home>
References: <1359123276-15833-1-git-send-email-arnd@arndb.de>
 <1359123276-15833-20-git-send-email-arnd@arndb.de>
 <20130125162608.GD2069@linaro.org>
 <1359132254.21576.230.camel@gandalf.local.home>
 <20130125165934.GE2069@linaro.org>
 <1359133703.21576.233.camel@gandalf.local.home>
Message-ID: <20130125172224.GA1961@linaro.org>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Fri, Jan 25, 2013 at 12:08:23PM -0500, Steven Rostedt wrote:
> On Fri, 2013-01-25 at 16:59 +0000, Dave Martin wrote:
> 
> > Cool.  Are you aware of return_address being used elsewhere?  Currently
> > I'm not aware of anything else which uses it, and grep is not finding
> > any calls outside ftrace.h that I can see.
> 
> softirq.c has a trace_preempt_off() use of CALLER_ADDR1.
> 
> kernel/sched/core.c has CALLER_ADDR1, 2 an 3.

These cases look safe to me ... sched/core.c:get_parent_ip() looks like
it uses notrace purely to avoid the spurious extra frame which it would
otherwise insert, and the code in softirq.c doesn't appear to be in a
notrace context.

Am I being too optimistic, or does that match your understanding?

Cheers
---Dave