futex_wait

sys_futex_wait(void *uaddr, unsigned long val, unsigned long mask, unsigned int flags, struct __kernel_timespec *timespec, clockid_t clockid)

register	value
`r20`	455, the syscall number
`r26`	void *uaddr
`r25`	unsigned long val
`r24`	unsigned long mask
`r23`	unsigned int flags
`r22`	struct __kernel_timespec *timespec
`r21`	clockid_t clockid
`r28`	the return value

Then run ble 0x100(%sr2, %r0) to enter the kernel.

Same syscall on other architectures