The sun mmu is very broken, and we all can thank crashme for

The sun mmu is very broken, and we all can thank crashme for
helping me find this bug.  On execution of an atomic load/store instruction
the chip will only say that a read fault is happening, we then load up a
readonly translation to the accessed page, and we get the fault again still
showing a read-fault.  We end up faulting in a loop forever and the process
appears to be completely stuck.  The algorithm to fix this problem goes like
this.  If we get a non-text fault, and the fault type is VM_PROT_READ, and
the SER_PROT bit is set in the syncronous fault error register, we take
a peek at the instruction at pc.  If this instruction is indeed an ldstub
or a swap variant we or in VM_PROT_WRITE to the fault type.