K 10
svn:author
V 6
andrew
K 8
svn:date
V 27
2016-02-02T10:28:56.038891Z
K 7
svn:log
V 316
Implement single stepping on arm64. We need to set the single step bits in
the processor and debug state registers. A flag has been added to the pcb
to tell us when to enable single stepping for a given thread.

Reviewed by:	kib
Sponsored by:	ABT Systems Ltd
Differential Revision:	https://reviews.freebsd.org/D4730

END