arm: perf: cleanups and initial refactoring

Hi Mark,

Quoted 20 lines · Mark Rutland

While reorganising the ARM perf backend to provide support for heterogeneous PMUs in big.LITTLE systems, I encountered a couple of issues requiring some preparatory work in addition to some opportunities for general cleanup in the backend. This series consists of those initial cleanups.

Currently the event mapping code in the ARM perf backend requires multi-dimensional tables to map from common event encodings to raw hardware values, where empty slots must be initialised to non-zero values. The current way of organising this results in very large support files which we can simplify with some macro use to remove a few hundred lines and make things more legible.

The PMU naming is somewhat of a mess, with most names not being supported by the perf tool. Given that no-one has complained, it seems that the PMUs are not being accessed by name in a perf context, and we can fix these to be consistent and usable with current tools. We update the OProfile name mangling to ensure that OProfile (which accesses the PMUs in its own namespace) are not adversely affected.

Quoted 3 lines

To prepare for reorganisation of the PMU probing code, new platform_device_id values are added to allow ARMv6, ARMv7, and XScale PMU platform_devices to be distinguished.

I ran Vince Weaver's perf events test suite [1] against a kernel with these patches applied on an 8074 Dragonboard [2] and didn't see any regressions. The patches also look good to me.

Tested-by Christopher Covington <[email protected]>