Looking around speedstep-smi, there is a lot of call to
speedstep_get_state() which is used as an index for the array
speedstep_freqs.  But speedstep_get_state() will return the value of ebx
after a call to a SMI handler.  It's not safe IMHO.

From: Bruno Ducrot
Signed-off-by: Dave Jones <davej@redhat.com>