Re: [PATCH] rseq/selftests: fix parametrized test with -fpie

[Paul E. McKenney]

On Thu, Sep 27, 2018 at 02:02:08PM -0400, Mathieu Desnoyers wrote:
> ----- On Sep 27, 2018, at 9:58 AM, Shuah Khan shuah.kh@xxxxxxxxxxx wrote:
> 
> > On 09/27/2018 07:22 AM, Steven Rostedt wrote:
> >> On Tue, 25 Sep 2018 13:39:36 -0400 (EDT)
> >> Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> wrote:
> >> 
> >>> ----- On Sep 18, 2018, at 9:53 AM, Mathieu Desnoyers
> >>> mathieu.desnoyers@xxxxxxxxxxxx wrote:
> >>>
> >>>> On x86-64, the parametrized selftest code for rseq crashes with a
> >>>> segmentation fault when compiled with -fpie. This happens when the
> >>>> param_test binary is loaded at an address beyond 32-bit on x86-64.
> >>>>
> >>>> The issue is caused by use of a 32-bit register to hold the address
> >>>> of the loop counter variable.
> >>>>
> >>>> Fix this by using a 64-bit register to calculate the address of the
> >>>> loop counter variables as an offset from rip.
> >>>
> >>> Should this fix go through tip or the selftests tree ?
> >>>
> >> 
> >> I usually have changes like this pulled through Shuah's tree with an
> >> ack from the maintainer of the code that it tests.
> >> 
> >> -- Steve
> >> 
> > 
> > Right that is what I prefer. I usually wait for an Ack. I can pull this
> > in.
> 
> I am maintainer of the code that it tests as well, so being both author
> of the selftest patch and giving an ack to it seems a bit silly. :) Other
> rseq co-maintainers could weight in though: Peter, Paul, and Boqun.

Here you go!  ;-)

Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxx>

> Thanks,
> 
> Mathieu
> 
> > 
> > thanks,
> > -- Shuah
> > 
> > --
> > Shuah Khan
> > Sr. Linux Kernel Developer
> > Open Source Innovation Group
> > Samsung Research America(Silicon Valley)
> > shuah.kh@xxxxxxxxxxx
> 
> -- 
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com
>