K 10
svn:author
V 2
br
K 8
svn:date
V 27
2016-02-04T12:49:28.202787Z
K 7
svn:log
V 347
Reuse gp register for pcpu pointer.

gp (global pointer) is used by compiler in userland only,
so re-use it for pcpup in kernel, save it on stack on switching
out to userland and load back on return to kernel.

Discussed with:	jhb, andrew, kib
Sponsored by:	DARPA, AFRL
Sponsored by:	HEIF5
Differential Revision:	https://reviews.freebsd.org/D5178

END