powerpc/perf: Add support for caps under sysfs in powerpc

Add caps support under "/sys/bus/event_source/devices/<pmu>/"
for powerpc. This directory can be used to expose some of the
specific features that powerpc PMU supports to the user.
Example: pmu_name. The name of PMU registered will depend on
platform, say power9 or power10 or it could be Generic Compat
PMU.

Currently the only way to know which is the registered
PMU is from the dmesg logs. But clearing the dmesg will make it
difficult to know exact PMU backend used. And even extracting
from dmesg will be complicated, as we need to parse the dmesg
logs and add filters for pmu name. Whereas by exposing it via
caps will make it easy as we just need to directly read it from
the sysfs.

Add a caps directory to /sys/bus/event_source/devices/cpu/
for power8, power9, power10 and generic compat PMU in respective
PMU driver code. Update the pmu_name file under caps folder
in core-book3s using "attr_update".

The information exposed currently:
- pmu_name : Underlying PMU name from the driver

Example result with power9 pmu:

# ls /sys/bus/event_source/devices/cpu/caps
pmu_name

# cat /sys/bus/event_source/devices/cpu/caps/pmu_name
POWER9

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220520084630.15181-1-atrajeev@linux.vnet.ibm.com

powerpc/perf: Give generic PMU a nice name

When booting on a machine that uses the compat pmu driver we see this:

[ 0.071192] GENERIC_COMPAT performance monitor hardware support registered

Which is a bit shouty. Give it a nicer name.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220610044006.2095806-1-joel@jms.id.au

powerpc: declare unmodified attribute_group usages const

Inspired by (bd75b4ef4977: Constify static attribute_group structs),
accepted by linux-next, reported:
https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20220210202805.7750-4-rikard.falkeborn@gmail.com/

Nearly all singletons of type struct attribute_group are never modified,
and so are candidates for being const. Declare them as const.

Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220307231414.86560-1-rmclure@linux.ibm.com

powerpc/perf: Add __init attribute to eligible functions

Some functions defined in 'arch/powerpc/perf' are deserving of an
`__init` macro attribute. These functions are only called by other
initialization functions and therefore should inherit the attribute.
Also, change function declarations in header files to include `__init`.

Signed-off-by: Nick Child <nick.child@ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211216220035.605465-5-nick.child@ibm.com

powerpc/pmu: Make the generic compat PMU use the architected events

This changes generic-compat-pmu.c so that it only uses architected
events defined in Power ISA v3.0B, rather than event encodings which,
while common to all the IBM Power Systems implementations, are
nevertheless implementation-specific rather than architected. The
intention is that any CPU implementation designed to conform to Power
ISA v3.0B or later can use generic-compat-pmu.c.

In addition to the existing events for cycles and instructions, this
adds several other architected events, including alternative encodings
for some events. In order to make it possible to measure cycles and
instructions at the same time as each other, we set the CC5-6RUN bit
in MMCR0, which makes PMC5 and PMC6 count instructions and cycles
regardless of the run bit, so their events are now PM_CYC and
PM_INST_CMPL rather than PM_RUN_CYC and PM_RUN_INST_CMPL (the latter
are still available via other event codes).

Note that POWER9 has an erratum where one architected event
(PM_FLOP_CMPL, floating-point operations completed, code 0x100f4) does
not work correctly. Given that there is a specific PMU driver for P9
which will be used in preference to generic-compat-pmu.c, that is not
a real problem.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Reviewed-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/YJD7L9yeoxvxqeYi@thinks.paulus.ozlabs.org

powerpc/perf: Update Power PMU cache_events to u64 type

Events of type PERF_TYPE_HW_CACHE was described for Power PMU
as: int (*cache_events)[type][op][result];

where type, op, result values unpacked from the event attribute config
value is used to generate the raw event code at runtime.

So far the event code values which used to create these cache-related
events were within 32 bit and `int` type worked. In power10,
some of the event codes are of 64-bit value and hence update the
Power PMU cache_events to `u64` type in `power_pmu` struct.
Also propagate this change to existing all PMU driver code paths
which are using ppmu->cache_events.

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1594996707-3727-4-git-send-email-atrajeev@linux.vnet.ibm.com

powerpc/perf: Add generic compat mode pmu driver

Most of the power processor generation performance monitoring
unit (PMU) driver code is bundled in the kernel and one of those
is enabled/registered based on the oprofile_cpu_type check at
the boot.

But things get little tricky incase of "compat" mode boot.
IBM POWER System Server based processors has a compactibility
mode feature, which simpily put is, Nth generation processor
(lets say POWER8) will act and appear in a mode consistent
with an earlier generation (N-1) processor (that is POWER7).
And in this "compat" mode boot, kernel modify the
"oprofile_cpu_type" to be Nth generation (POWER8). If Nth
generation pmu driver is bundled (POWER8), it gets registered.

Key dependency here is to have distro support for latest
processor performance monitoring support. Patch here adds
a generic "compat-mode" performance monitoring driver to
be register in absence of powernv platform specific pmu driver.

Driver supports only "cycles" and "instruction" events.
"0x0001e" used as event code for "cycles" and "0x00002"
used as event code for "instruction" events. New file
called "generic-compat-pmu.c" is created to contain the driver
specific code. And base raw event code format modeled
on PPMU_ARCH_207S.

Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
[mpe: Use SPDX tag for license]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>