feat (counter): Support for cpumask

[cvonelm]

This PR adds support for the cpumask field of PMU events.

Some PMUs do not refer to a core component but to some piece of uncore, such as the amd_iommu_0 PMU found on modern AMD processors.

To be able to still measure them, perf associates every uncore PMU with a logical core. This relationship is recorded in the cpumask field.

This PR makes lo2s respect this cpumask field, only opening the PMU events on the cores recorded in cpumask.

Note that this works as both -E and --userspace-metric-event.

This PR is marked DRAFT for these reasons:

• This is missing any sanity checks. Currently trying to open an uncore PMU event in process mode will silently ignore the given PMU event.
• Are we fine with how --list-events looks?

Currently it prints something like this:

List of Kernel PMU events:

  amd_iommu_0/cmd_processed/ # [ UNCORE ]
  amd_iommu_0/cmd_processed_inv/ # [ UNCORE ]
  amd_iommu_0/ign_rd_wr_mmio_1ff8h/ # [ UNCORE ]
  amd_iommu_0/int_dte_hit/ # [ UNCORE ]
  amd_iommu_0/int_dte_mis/ # [ UNCORE ]
  amd_iommu_0/mem_dte_hit/ # [ UNCORE ]
  amd_iommu_0/mem_dte_mis/ # [ UNCORE ]
  amd_iommu_0/mem_iommu_tlb_pde_hit/ # [ UNCORE ]
  amd_iommu_0/mem_iommu_tlb_pde_mis/ # [ UNCORE ]
  amd_iommu_0/mem_iommu_tlb_pte_hit/ # [ UNCORE ]
  amd_iommu_0/mem_iommu_tlb_pte_mis/ # [ UNCORE ]
  amd_iommu_0/mem_pass_excl/ # [ UNCORE ]
  amd_iommu_0/mem_pass_pretrans/ # [ UNCORE ]
  amd_iommu_0/mem_pass_untrans/ # [ UNCORE ]
  amd_iommu_0/mem_target_abort/ # [ UNCORE ]
  amd_iommu_0/mem_trans_total/ # [ UNCORE ]
  amd_iommu_0/page_tbl_read_gst/ # [ UNCORE ]
  amd_iommu_0/page_tbl_read_nst/ # [ UNCORE ]
  amd_iommu_0/page_tbl_read_tot/ # [ UNCORE ]
  amd_iommu_0/smi_blk/ # [ UNCORE ]
  amd_iommu_0/smi_recv/ # [ UNCORE ]
  amd_iommu_0/tlb_inv/ # [ UNCORE ]
  amd_iommu_0/vapic_int_guest/ # [ UNCORE ]
  amd_iommu_0/vapic_int_non_guest/ # [ UNCORE ]
  cpu/branch-instructions/
  cpu/branch-misses/
  cpu/cache-misses/
  cpu/cache-references/
  cpu/cpu-cycles/
  cpu/instructions/
  cpu/stalled-cycles-backend/
  cpu/stalled-cycles-frontend/
  msr/aperf/
  msr/irperf/
  msr/mperf/
  msr/tsc/
  power/energy-pkg/ # [ UNCORE ]

(* Only available in process-monitoring mode
(# Only available in system-monitoring mode

This PR does not address the second part of Issue #262, which is support for uncore events in process mode.

I think before we attempt to band-aid fix support for such a system-mode event in process mode we should have a discussion about a more general solution to combining system-mode and process mode measurements.

[cvonelm]

Also the question is if this should be recorded on a new "uncore" location, instead of "core X"

[cvonelm]

As this PR is completely based on an EventDescription Rework which turned out to be a cluttery mess, I am closing this PR in favour of an implementation on the current EventDescription or a properly reworked version.