diff --git a/sys/arm64/arm64/genassym.c b/sys/arm64/arm64/genassym.c
index 646752c742ec..818c0e371f10 100644
--- a/sys/arm64/arm64/genassym.c
+++ b/sys/arm64/arm64/genassym.c
@@ -34,8 +34,18 @@ __FBSDID("$FreeBSD$");
 #include <sys/proc.h>
 
 #include <machine/frame.h>
+#include <machine/machdep.h>
 #include <machine/pcb.h>
 
+/* Sizeof arm64_bootparams, rounded to keep stack alignment */
+ASSYM(BOOTPARAMS_SIZE, roundup2(sizeof(struct arm64_bootparams),
+    STACKALIGNBYTES + 1));
+ASSYM(BP_MODULEP, offsetof(struct arm64_bootparams, modulep));
+ASSYM(BP_KERN_L1PT, offsetof(struct arm64_bootparams, kern_l1pt));
+ASSYM(BP_KERN_DELTA, offsetof(struct arm64_bootparams, kern_delta));
+ASSYM(BP_KERN_STACK, offsetof(struct arm64_bootparams, kern_stack));
+ASSYM(BP_KERN_L0PT, offsetof(struct arm64_bootparams,kern_l0pt));
+
 ASSYM(TDF_ASTPENDING, TDF_ASTPENDING);
 ASSYM(TDF_NEEDRESCHED, TDF_NEEDRESCHED);
 
diff --git a/sys/arm64/arm64/locore.S b/sys/arm64/arm64/locore.S
index 8b8cc4e7e8c2..9ed76fb8f688 100644
--- a/sys/arm64/arm64/locore.S
+++ b/sys/arm64/arm64/locore.S
@@ -153,18 +153,18 @@ virtdone:
 	sub	x26, x26, x29
 	sub	x24, x24, x29
 
-	sub	sp, sp, #(64 * 4)
+	sub	sp, sp, #BOOTPARAMS_SIZE
 	mov	x0, sp
 
 	/* Degate the delda so it is VA -> PA */
 	neg	x29, x29
 
-	str	x1,  [x0]	/* modulep */
-	str	x26, [x0, 8]	/* kern_l1pt */
-	str	x29, [x0, 16]	/* kern_delta */
+	str	x1,  [x0, #BP_MODULEP]
+	str	x26, [x0, #BP_KERN_L1PT]
+	str	x29, [x0, #BP_KERN_DELTA]
 	adr	x25, initstack
-	str	x25, [x0, 24]	/* kern_stack */
-	str	x24, [x0, 32]	/* kern_l0pt */
+	str	x25, [x0, #BP_KERN_STACK]
+	str	x24, [x0, #BP_KERN_L0PT]
 
 	/* trace back starts here */
 	mov	fp, #0