From mboxrd@z Thu Jan  1 00:00:00 1970
From: Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH] rseq/selftests: fix parametrized test with -fpie
Date: Thu, 27 Sep 2018 09:22:35 -0400
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To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: 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>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, 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-foundation.org>
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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