.syntax unified
    .cpu cortex-a7
    .thumb
    @ maze entry logger: ring buffer of 8 (lr,sp) at MAILBOX, return 0.
    @ Preserves all regs except r0 (return value) and r12 (IP, clobber-ok).
    .text
    .global maze_stub
maze_stub:
    push {r0-r3}
    movw r12, #:lower16:0x08006888
    movt r12, #:upper16:0x08006888
    ldr r0, [r12, #32]
    add r0, #1
    and r0, #7
    str r0, [r12, #32]
    lsl r0, #3
    add r0, r12
    str lr, [r0]
    str sp, [r0, #4]
    pop {r0-r3}
    movs r0, #0
    bx lr