     nv-fp-regs [ 8 * 80 + save-fp ] each-index
     nv-vec-regs [ 16 * 224 + save-vec ] each-index
 
+    ! Stick old stack pointer in a non-volatile register so that
+    ! callbacks can access their arguments
+    nv-reg 11 MR
+
     ! Load VM into vm-reg
     0 vm-reg LOAD32 rc-absolute-ppc-2/2 rt-vm jit-rel
 

    432 save-at ;

[
    ! Create stack frame
    0 MFLR
    1 1 callback-frame-size neg STWU
    0 1 callback-frame-size lr-save + STW

    ! Save all non-volatile registers


    ! Tear down stack frame and return
    0 1 callback-frame-size lr-save + LWZ
    1 1 callback-frame-size ADDI
    0 MTLR
    BLR
] callback-stub jit-define
