Currently mips and parisc are the only architectures not yet converted to the generic compat_sys_ptrace. The conversion is rather trivial and only involves splitting the current compat_ptrace handler into a compat_arch_ptrace with all the meat and the existing compat_sys_ptrace that does all the boilerplate code, just like the generic sys_ptrace. To get the generic compat_sys_ptrace you have to add a #define __ARCH_WANT_COMPAT_SYS_PTRACE to ptrace.h for now, but once mips and parisc are converted this will of course be removed. Take a look at the powerpc conversion as an example: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git&a=commitdiff&h=81e695c026eeda9a97e412fa4f458e5cab2f6c85
