reading a core's current task from memory

Hi dear list members,

I'm maintaining a Linux kernel debugger through jtag that has been
doing quite well on unicore/SH4 systems so far, now I'd like to
support ARM/SMP systems and do some improvements: I'm looking for a
simple way to know which is the current task executing on one each
core by accessing memory from jtag. Knowing a core's current when it
is running kernel core is easy as the sp registers gives direct access
to the current thread_info, now suppose a core is running a usermode
code page, then sp and pc are virtual memory.

through the jtag interface I can access any symbol which offset I know
from the vmlinux symbol table, and any field which offset is not
dependent of the configure options for a given kernel version. Sadly I
can't easily access the per_cpu runqueues and the rq->curr field this
way.

I'd be grateful for any suggestion as of how to do !

many thanks,

M.