K 10
svn:author
V 3
kib
K 8
svn:date
V 27
2015-11-24T09:13:21.711409Z
K 7
svn:log
V 589
On PowerPC 64bit, the linux-compat mb() definition is implemented with
lwsync instruction, which does not provide Store/Load barrier.  Fix
this by using "full" sync barrier for mb().

atomic_store_rel() does not need full barrier, change mb() call there
to the lwsync instruction if not hitting the known CPU erratas
(i.e. on 32bit).  Provide powerpc_lwsync() helper to isolate the
lwsync/sync compile time selection, and use it in atomic_store_rel()
and several other places which duplicate the code.

Noted by:	alc
Reviewed and tested by:	nwhitehorn
Sponsored by:	The FreeBSD Foundation

END