access_process_vm device memory infrastructure

access_process_vm device memory infrastructure

In order to be able to debug things like the X server and programs using
the PPC Cell SPUs, the debugger needs to be able to access device memory
through ptrace and /proc/pid/mem.

This patch:

Add the generic_access_phys access function and put the hooks in place
to allow access_process_vm to access device or PPC Cell SPU memory.

[[email protected]: Add documentation for the vm_ops->access function]
Signed-off-by: Rik van Riel <[email protected]>
Signed-off-by: Benjamin Herrensmidt <[email protected]>
Cc: Dave Airlie <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>