From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Paul E. McKenney" <paulmck@linux.ibm.com>
Subject: Re: [PATCH] rseq/selftests: fix parametrized test with -fpie
Date: Thu, 27 Sep 2018 11:18:06 -0700
Message-ID: <20180927181806.GI4222@linux.ibm.com>
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To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: shuah kh <shuah.kh@samsung.com>, rostedt <rostedt@goodmis.org>, Thomas Gleixner <tglx@linutronix.de>, Shuah Khan <shuahkh@osg.samsung.com>, linux-kselftest <linux-kselftest@vger.kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>, linux-api <linux-api@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>, Boqun Feng <boqun.feng@gmail.com>, Andy Lutomirski <luto@amacapital.net>, Dave Watson <davejwatson@fb.com>, Paul Turner <pjt@google.com>, Andrew Morton <akpm@linux-foundation.org>, Russell King <linux@arm.linux.org.uk>, Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>, Andi Kleen <andi@firstfloor.org>, Chris Lameter <cl@linux.com>, Ben Maurer <bmaurer@fb.com>, Josh Triplett <josh@joshtriplett.org>, Linus Torvalds <torvalds@linux-found>
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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@samsung.com 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@efficios.com> wrote:
> >> 
> >>> ----- On Sep 18, 2018, at 9:53 AM, Mathieu Desnoyers
> >>> mathieu.desnoyers@efficios.com 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@linux.ibm.com>

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