FTrace on MPC8xx

Stefan Roese ml at
Thu Apr 14 01:21:33 EST 2011

Hi Joakim,

On Wednesday 13 April 2011 16:58:21 Joakim Tjernlund wrote:
> > This is on a 2.6.38 kernel (2.6.32 fails too). Debugging shows that
> > __copy_tofrom_user() fails with return code 4 (called via
> > ftrace_modify_code()).
> > 
> > Before digging deeper: Has anybody tried/tested ftrace on MPC8xx? Any
> > ideas what going wrong here?
> Just an idea, remove the usage of dcbX insn, these has been problematic
> before.

I originally tested with 2.6.32. Same problem there. And your 8xx patches with 
the dcbX changes are not included in 2.6.32 yet.

> How big was the size to copy_tofrom_user()? Did it mange to copy
> any bytes?

The size in __copy_tofrom_user is 4. And its the first call in 
ftrace_modify_code() that fails directly. This works just fine on a PPC440EPx 

Best regards,

More information about the Linuxppc-dev mailing list