[PATCH v2 0/5] perf: Enabling PMUv3 on 32bit ARM systems

[Marc Zyngier]

PMUv3 has been introduced with ARMv8 and, while it has only been used
on 64bit systems so far, it would definitely be useful for 32bit
guests running under KVM/arm64, for example.

This is done in three steps:
(1) Move the driver from arch/arm64 to drivers/perf
(2) Add a handful of system register accessors so that we can reuse
    the driver on 32bit
(3) Provide the same accessors on 32bit, enable compilation, and
    make it the default selection for mach-virt.

In the process, CPU_V7 is "upgraded" to also cover ARMv8 systems.

Tested on a 32bit VM running on a X-Gene system:

root at zomby-woof:~# uname -a
Linux zomby-woof 4.12.0-rc5+ #7239 SMP PREEMPT Tue Jun 13 14:35:46 BST 2017 armv7l GNU/Linux
root at zomby-woof:~# dmesg | grep -i pmu
[    2.440279] hw perfevents: enabled with armv8_pmuv3 PMU driver, 5 counters available
root at zomby-woof:~# perf stat -e cycles,L1-icache-loads,dTLB-load-misses ~maz/hackbench 100 process 1000
Running with 100*40 (== 4000) tasks.
Time: 59.370

 Performance counter stats for '/home/maz/hackbench 100 process 1000':

      323663890100      cycles                                                      
       46297944079      L1-icache-loads                                             
           6570884      dTLB-load-misses                                            

      60.777397600 seconds time elapsed

* From v1:
  - Fixed encodings for some CP15 accessors
  - Added a terse note saying that CPU_V7 also covers ARMv8
  - Rebased on v4.12-rc5

Marc Zyngier (5):
  arm64: perf: Move PMUv3 driver to drivers/perf
  arm64: perf: Abstract system register accesses away
  ARM: Make CONFIG_CPU_V7 valid for 32bit ARMv8 implementations
  ARM: perf: Allow the use of the PMUv3 driver on 32bit ARM
  ARM: mach-virt: Select PMUv3 driver by default

 arch/arm/Kconfig                                   |   1 +
 arch/arm/include/asm/arm_pmuv3.h                   | 128 +++++++++++++++++++++
 arch/arm/mm/Kconfig                                |   2 +-
 arch/arm64/include/asm/arm_pmuv3.h                 | 110 ++++++++++++++++++
 arch/arm64/include/asm/perf_event.h                |  55 ---------
 arch/arm64/kernel/Makefile                         |   1 -
 drivers/perf/Kconfig                               |   8 ++
 drivers/perf/Makefile                              |   1 +
 .../perf_event.c => drivers/perf/arm_pmuv3.c       |  43 +++----
 include/kvm/arm_pmu.h                              |   2 +-
 include/linux/perf/arm_pmuv3.h                     |  77 +++++++++++++
 11 files changed, 346 insertions(+), 82 deletions(-)
 create mode 100644 arch/arm/include/asm/arm_pmuv3.h
 create mode 100644 arch/arm64/include/asm/arm_pmuv3.h
 rename arch/arm64/kernel/perf_event.c => drivers/perf/arm_pmuv3.c (97%)
 create mode 100644 include/linux/perf/arm_pmuv3.h

-- 
2.11.0