Index: kernel/arch/amd64/src/smp/ap.S
===================================================================
--- kernel/arch/amd64/src/smp/ap.S	(revision 19077a55c863a5fe2d8072efd0b5fa2f9a95cca3)
+++ kernel/arch/amd64/src/smp/ap.S	(revision 4afd4ab1cf55802dd65cdbbe092a477f1110b2ff)
@@ -99,4 +99,6 @@
 start64:
 	movq (ctx), %rsp
+	pushq $0
+	movq %rsp, %rbp
 	call main_ap - AP_BOOT_OFFSET + BOOT_OFFSET   # never returns