selftests/powerpc: Purge extra count_pmc() calls of ebb selftests

An extra count on ebb_state.stats.pmc_count[PMC_INDEX(pmc)] is being per-
formed when count_pmc() is used to reset PMCs on a few selftests. This
extra pmc_count can occasionally invalidate results, such as the ones from
cycles_test shown hereafter. The ebb_check_count() failed with an above
the upper limit error due to the extra value on ebb_state.stats.pmc_count.

Furthermore, this extra count is also indicated by extra PMC1 trace_log on
the output of the cycle test (as well as on pmc56_overflow_test):

==========
...
[21]: counter = 8
[22]: register SPRN_MMCR0 = 0x0000000080000080
[23]: register SPRN_PMC1 = 0x0000000080000004
[24]: counter = 9
[25]: register SPRN_MMCR0 = 0x0000000080000080
[26]: register SPRN_PMC1 = 0x0000000080000004
[27]: counter = 10
[28]: register SPRN_MMCR0 = 0x0000000080000080
[29]: register SPRN_PMC1 = 0x0000000080000004
>> [30]: register SPRN_PMC1 = 0x000000004000051e
PMC1 count (0x280000546) above upper limit 0x2800003e8 (+0x15e)
[FAIL] Test FAILED on line 52
failure: cycles
==========

Signed-off-by: Desnes A. Nunes do Rosario <desnesn@linux.ibm.com>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200626164737.21943-1-desnesn@linux.ibm.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 191

Based on 1 normalized pattern(s):

licensed under gplv2

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 99 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190528170027.163048684@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

selftests/powerpc: Make reg.h common to all powerpc selftests

Currently there is a reg.h in pmu/ebb that has defines that are useful
in other powerpc selftests so move this up into selftests/powerpc
folder. Also include in utils.h - as this is often used in self tests.
Add in some other useful register defines.

Signed-off-by: Rashmica Gupta <rashmicy@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

selftests/powerpc: Add have_hwcap2() helper

We already do this twice and want to add another so add a helper.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

selftests/powerpc: Run EBB tests only on POWER8

EBB (Event Based Branches) are currently only available on POWER8, so we
should skip them on other CPUs.

I've found that at least one test loops forever on 970MP (cycles_with_freeze_test).

Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
[mpe: Minor change log editing, add skip to cpu_event_vs_ebb_test]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

selftests/powerpc: Dump MMCR2 as part of the EBB HW state

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

selftests/powerpc: Move core_busy_loop() into asm

There is at least one bug in core_busy_loop(), we use r0, but it's
not in the clobber list. We were getting away with this it seems but
that was luck.

It's also fishy to be touching the stack, even if we do it below the
stack pointer. It seems we get away with it, but looking at the
generated code that may just be luck.

So move it into assembler, do all the stack handling by hand. We create
a stack frame to save the non-volatiles in, so we can muck around with
them.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

selftests/powerpc: Add tests of PMU EBBs

The Power8 Performance Monitor Unit (PMU) has a new feature called Event
Based Branches (EBB). This commit adds tests of the kernel API for using
EBBs.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>