timer_settime

arm/disarm and fetch state of POSIX per-process timer

sys_timer_settime(timer_t timer_id, int flags, const struct __kernel_itimerspec *new_setting, struct __kernel_itimerspec *old_setting)

register	value
`x8`	110, the syscall number
`x0`	timer_t timer_id
`x1`	int flags
`x2`	const struct __kernel_itimerspec *new_setting
`x3`	struct __kernel_itimerspec *old_setting
`x0`	the return value

Then run svc #0 to enter the kernel.

Same syscall on other architectures