[PATCH 1/2] coresight: Use %px to print pcsr instead of %p

[Leo Yan]

Hi Mathieu, Kees,

On Fri, Apr 06, 2018 at 09:47:31AM -0600, Mathieu Poirier wrote:
> On 5 April 2018 at 00:26, Kees Cook <keescook at chromium.org> wrote:
> > On Tue, Mar 13, 2018 at 10:24 AM, Mathieu Poirier
> > <mathieu.poirier at linaro.org> wrote:
> >> From: Leo Yan <leo.yan at linaro.org>
> >>
> >> Commit ad67b74d2469 ("printk: hash addresses printed with %p") lets
> >> printk specifier %p to hash all addresses before printing, this was
> >> resulting in the high 32 bits of pcsr can only output zeros.  So
> >> module cannot completely print pc value and it's pointless for debugging
> >> purpose.
> >>
> >> This patch fixes this by using %px to print pcsr instead.
> >
> > Why is %p (and now %px) needed here at all? %pS is already used, which
> > should give useful debugging details, yes?
> 
> Hey Leo,
> 
> I've taken a second look at this and Kees has a point, %pS should be
> sufficient here.  Please test again and see if %px is absolutely
> necessary.  If you think that is the case please provide a snapshot of
> the corner case that makes the change mandatory.

Sorry I missed replying for this patch due to my email filter and
thanks for suggestion.

I can think out one case which should use %px: if CPU is locked up in
firmwares (e.g. NS-EL2 or ARM-TF in S-EL3), we can rely on %px to read
back PC hex value; for this case the CPU PC address is out of kernel
space.

How about you guys think for this?

Thanks,
Leo Yan