Re: [PATCH backport for 4.18] rseq/selftests: fix parametrized test with -fpie

On 10/04/2018 01:04 PM, Mathieu Desnoyers wrote:

commit ce01a1575f45bf319e374592656441021a7f5823 upstream.

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.

Signed-off-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com Acked-by: "Paul E . McKenney" paulmck@linux.vnet.ibm.com

Thanks for q quick back-port.

Acked-by: Shuah Khan (Samsung OSG) shuah@kernel.org

thanks, -- Shuah