utrace per se has no machine-dependent code. It requires modern support for machine dependencies in generic kernel code, i.e. user_regset and tracehook. The ARM kernel has a tiny subset of those, but not enough to be useful. Long ago I did 98% of the work for implementing user_regset and tracehook support for ARM and posted it, but the ARM kernel maintainers are largely nonresponsive even to working patches.
Thanks, Roland
