io_getevents

read asynchronous I/O events from the completion queue

sys_io_getevents(aio_context_t ctx_id, long min_nr, long nr, struct io_event *events, struct __kernel_timespec *timeout)

register	value
`r1`	245, the syscall number
`r2`	aio_context_t ctx_id
`r3`	long min_nr
`r4`	long nr
`r5`	struct io_event *events
`r6`	struct __kernel_timespec *timeout
`r2`	the return value

Then run svc 0 to enter the kernel.

Same syscall on other architectures