Thread (8 messages) 8 messages, 5 authors, 2018-09-27

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

From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: 2018-09-27 18:02:13
Also in: linux-kselftest, lkml, stable

----- 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:
quoted
On Tue, 25 Sep 2018 13:39:36 -0400 (EDT)
Mathieu Desnoyers [off-list ref] wrote:
quoted
----- On Sep 18, 2018, at 9:53 AM, Mathieu Desnoyers
mathieu.desnoyers@efficios.com wrote:
quoted
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@samsung.com
-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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