replace asm volatile("pause") with function

core/mem/pmap.c

@@ -6,6 +6,7 @@
 #include <zinnia/pmap.h>
 #include <zinnia/spin.h>
 #include <zinnia/vma.h>
+#include <arch/cpu.h>
 #include <config.h>
 
 // TODO: For now, we assume that we can do generic PTE lookups on every arch that has a MMU.
@@ -231,7 +232,7 @@ void pmap_shootdown(struct pmap* pt) {
         const size_t req = atomic_load(percpu_ref_on(cpu, shootdown_req), ATOMIC_RELAXED);
         while ((ptrdiff_t)(req - atomic_load(percpu_ref_on(cpu, shootdown_ack), ATOMIC_ACQUIRE)) > 0) {
             pmap_shootdown_handle();
-            asm volatile("pause");
+            arch_cpu_pause();
         }
     }
     irq_unlock();