CVSROOT: /cvs
Module name: src
Changes by: [email protected] 2014/09/22 06:12:23
Modified files:
sys/arch/hppa/hppa: lock_machdep.c machdep.c
sys/arch/hppa/include: atomic.h lock.h
Log message:
implement atomic_{cas,swap}_{uint,ulong,ptr} and
atomic_{add,sub}_{int,long}_nv. sys/atomic.h turns these into the
rest of the atomic api.
on uniprocessor hppa systems "atomic" operations are implemented
as a non-interruptable sequence by disabling all interrupts on the
cpu, doing the operation, and then restoring the interrupt mask.
this isnt enough on MP systems, so we added a global atomic memory
mutex that is taken inside the interrupt disabling above to coordinate
operations between cpus.
this is a lot of overhead though cos mutexes dance around with ipls,
which is unecessary in our case because of the interrupt disabling
that is already done. also, hppa spinlocks are implemented with
ldcw which requires the word it operates on to be 16 byte aligned.
mutexes arent guaranteed to have this alignment so they compensate
by having lots of words inside themselves so they can hit the
appropriate one to use for the ldcw op.
with this in mind, this change pulls __cpu_simple_locks, which are
simply ldcw spinlocks with a 16 byte aligned word, out of
src/sys/arch/hppa/include/lock.h into src/sys/arch/hppa/include/atomic.h
so atomic.h can use them. lock.h includes atomic.h, so it still
gets and provides the same functionality as before.
finally, this also pulls the rwlock cas implementation apart. cas
ops now share the same serialising lock on MP systems as the other
memory operations, and rw_cas is defined as a wrapper around
atomic_cas_uint.
ok kettenis@
