arm: recognize instruction fetch pagefault

. an instruction fetch pagefault generates a prefetch
	  abort exception, this should also be a source of
	  a pagefault event
	. the saved_lr argument to the C exception handler was
	  sometimes an address, sometimes a pointer to that address;
	  the kernel sometimes dereferences it, so it should always be
	  an in-kernel address, never a userspace address. fix in mpx.S
	  makes it always a pointer.
	. move dumping of all processes over serial out of
	  the arch-specific arch_system.c

kernel/proc.c

@@ -1894,3 +1894,15 @@ void release_fpu(struct proc * p) {
 	if (*fpu_owner_ptr == p)
 		*fpu_owner_ptr = NULL;
 }
+
+void ser_dump_proc()
+{
+        struct proc *pp;
+
+        for (pp= BEG_PROC_ADDR; pp < END_PROC_ADDR; pp++)
+        {
+                if (isemptyp(pp))
+                        continue;
+                print_proc_recursive(pp);
+        }
+}