arm64: Clear out any singlestep state on a ptrace detach operation

Make sure to clear out any ptrace singlestep state when a ptrace(2)
PTRACE_DETACH call is made on arm64 systems.

Otherwise, the previously ptraced task will die off with a SIGTRAP
signal if the debugger just previously singlestepped the ptraced task.

Cc: <stable@vger.kernel.org>
Signed-off-by: John Blackwood <john.blackwood@ccur.com>
[will: added comment to justify why this is in the arch code]
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
John Blackwood 2015-12-07 11:50:34 +00:00 • committed by Will Deacon
commit 5db4fd8c52