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

[Mathieu Desnoyers]

----- 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.

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