How to properly use the PMC0 and PMC1 performance counters

[Paul_M_2]

Hi all,

I have a question regarding on how to use the PMC0 and PMC1 together with the APIC_LVTPC. I have developed 2 Linux kernel modules. First, reads PEBS and second, reads LBR. I use PMC0 and PMC1 to count the event.

My problem is that if I load PEBS module and than LBR reading module than only the LBR module working properly. If I load first the LBR module than the PEBS module is not working properly. Somehow the second module is shadowing the first one.

Is there something that I miss? Can the APIC_LVTPC register used with only one event at a time?

Please have a look at the code of PEBS module and LBR module here:

https://github.com/plxplx/rop_detector/blob/master/pebs-lkm/simple-pebs.c

https://github.com/plxplx/rop_detector/blob/master/lbr-lkm/simple-lbr.c

Thanks,

Paul