diff --git a/sys/cddl/dev/dtrace/arm/dtrace_asm.S b/sys/cddl/dev/dtrace/arm/dtrace_asm.S
index a536492c02b..9cbf1172d55 100644
--- a/sys/cddl/dev/dtrace/arm/dtrace_asm.S
+++ b/sys/cddl/dev/dtrace/arm/dtrace_asm.S
@@ -195,3 +195,25 @@ ENTRY(dtrace_caller)
 	mov	r0, #-1
 	RET
 END(dtrace_caller)
+
+/*
+uint32_t
+dtrace_cas32(uint32_t *target, uint32_t cmp, uint32_t new)
+
+void *
+dtrace_casptr(volatile void *target, volatile void *cmp, volatile void *new)
+*/
+ENTRY(dtrace_cas32)
+EENTRY(dtrace_casptr)
+1:	ldrex	r3, [r0]	/* Load target */
+	cmp	r3, r1		/* Check if *target == cmp */
+	bne	2f		/* No, return */
+	strex	r3, r2, [r0]	/* Store new to target */
+	cmp	r3, #0		/* Did the store succeed? */
+	bne	1b		/* No, try again */
+	mov	r0, r2		/* Return the new value of the store */
+2:	movne	r0, r3		/* The first compare failed, return */
+				/* the value loaded from memory */
+	RET
+EEND(dtrace_casptr)
+END(dtrace_cas32)
diff --git a/sys/cddl/dev/dtrace/arm/dtrace_isa.c b/sys/cddl/dev/dtrace/arm/dtrace_isa.c
index 14adb4c3b5d..c054702655a 100644
--- a/sys/cddl/dev/dtrace/arm/dtrace_isa.c
+++ b/sys/cddl/dev/dtrace/arm/dtrace_isa.c
@@ -262,34 +262,3 @@ dtrace_fuword64(void *uaddr)
 	}
 	return (dtrace_fuword64_nocheck(uaddr));
 }
-
-#define __with_interrupts_disabled(expr) \
-	do {						\
-		u_int cpsr_save, tmp;			\
-							\
-		__asm __volatile(			\
-			"mrs  %0, cpsr;"		\
-			"orr  %1, %0, %2;"		\
-			"msr  cpsr_fsxc, %1;"		\
-			: "=r" (cpsr_save), "=r" (tmp)	\
-			: "I" (PSR_I | PSR_F)		    \
-			: "cc" );		\
-		(expr);				\
-		 __asm __volatile(		\
-			"msr  cpsr_fsxc, %0"	\
-			: /* no output */	\
-			: "r" (cpsr_save)	\
-			: "cc" );		\
-	} while(0)
-
-uint32_t dtrace_cas32(uint32_t *target, uint32_t cmp, uint32_t new)
-{
-	return atomic_cmpset_32((uint32_t*)target, (uint32_t)cmp, (uint32_t)new);
-
-}
-
-void * dtrace_casptr(volatile void *target, volatile void *cmp, volatile void *new)
-{
-        return (void*)dtrace_cas32((uint32_t*)target, (uint32_t)cmp, (uint32_t)new);
-}
-