K 10
svn:author
V 6
mhorne
K 8
svn:date
V 27
2020-12-11T20:01:45.120130Z
K 7
svn:log
V 381
riscv: small counter(9) improvements

Prefer atomics to critical section. This reduces the cost of the
increment operation and removes the possibility of it being interrupted
by counter_u64_zero().

Use CPU_FOREACH() macro to skip absent CPUs.

Replace hand-rolled address calculation with zpcpu_get().

Reviewed by:	markj
Differential Revision:	https://reviews.freebsd.org/D27536

END