4 * r7 contains the syscall number (set by stub);
5 * r0..r3 contains arguments 0-3 per standard calling convention;
6 * r4..r5 contains arguments 4-5, but we have to get those from
12 .globl __syscall_common
13 .type __syscall_common,@function
29 .size __syscall_common,.-__syscall_common