Set control registers on all cores

Question

I need to enable cr4 bit 8 (PCE) on all cores of a given system. I currently have a working module which sets this bit on the core it runs on when the module is loaded. I am stuck here and haven't found much documentation on how to parallelize this to run on all cores:

1) It appears that the unload doesn't always happen on the core the load happened on, so I can't clean up correctly

2) I can't figure out any way to force the module initialization to be executed on a particular core - if I could, I could simply have have a module can be called separately for each core to set all cores. There doesn't seem to be a sched_setaffinity equivalent available for modules.

Is there any way to force this module to run on all cores, either through parallelization or iterating across all cores? I can't modify the kernel itself or make the module load at boot, so I can't just change what the register is initially set to.

Thanks for any hints, I'm going crazy here trying to figure this out!

Answer 1

Figured it out - smp_call_function() calls a function on all cores of the system. It's just very tricky to get a search result that brings this up (little / no documentation) :-/

This works perfectly, and you can verify each core runs the code by printing smp_processor_id() within the called function.

EDIT: This function only calls other cores, so you still have to call the function once separately to get the core the module is currently running on!