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Subject: Re: [PATCH] rseq/selftests: fix parametrized test with -fpie
To:     Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC:     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>,
        "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>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        Joel Fernandes <joelaf@google.com>,
        stable <stable@vger.kernel.org>, shuah <shuah@kernel.org>
From:   Shuah Khan <shuah.kh@samsung.com>
Message-ID: <2bfea3f5-b251-d4b8-d03a-28b575aefae0@samsung.com>
Date:   Thu, 27 Sep 2018 12:10:38 -0600
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On 09/27/2018 12:02 PM, 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.
> 

I was commenting in general, not specific to this patch. No worries. I will
apply this right away.

I have been traveling the last couple of weeks and in the catch up mode still.

thanks,
-- Shuah


>>
>> --
>> Shuah Khan
>> Sr. Linux Kernel Developer
>> Open Source Innovation Group
>> Samsung Research America(Silicon Valley)
>> shuah.kh@samsung.com
> 


-- 
Shuah Khan
Sr. Linux Kernel Developer
Open Source Innovation Group
Samsung Research America(Silicon Valley)
shuah.kh@samsung.com