nvdimm: Fix dereference after free in register_nvdimm_pmu()

'nd_pmu->pmu.attr_groups' is dereferenced in function
'nvdimm_pmu_free_hotplug_memory' call after it has been freed. Because in
function 'nvdimm_pmu_free_hotplug_memory' memory pointed by the fields of
'nd_pmu->pmu.attr_groups' is deallocated it is necessary to call 'kfree'
after 'nvdimm_pmu_free_hotplug_memory'.

Fixes: 0fab1ba6ad6b ("drivers/nvdimm: Add perf interface to expose nvdimm performance stats")
Co-developed-by: Ivanov Mikhail <ivanov.mikhail1@huawei-partners.com>
Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Link: https://lore.kernel.org/r/20230817114103.754977-1-konstantin.meskhidze@huawei.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

nvdimm: Fix memleak of pmu attr_groups in unregister_nvdimm_pmu()

Memory pointed by 'nd_pmu->pmu.attr_groups' is allocated in function
'register_nvdimm_pmu' and is lost after 'kfree(nd_pmu)' call in function
'unregister_nvdimm_pmu'.

Fixes: 0fab1ba6ad6b ("drivers/nvdimm: Add perf interface to expose nvdimm performance stats")
Co-developed-by: Ivanov Mikhail <ivanov.mikhail1@huawei-partners.com>
Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Link: https://lore.kernel.org/r/20230817115945.771826-1-konstantin.meskhidze@huawei.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

drivers/nvdimm: Fix build failure when CONFIG_PERF_EVENTS is not set

The following build failure occurs when CONFIG_PERF_EVENTS is not set
as generic pmu functions are not visible in that scenario.

|-- s390-randconfig-r044-20220313
| |-- nd_perf.c:(.text):undefined-reference-to-perf_pmu_migrate_context
| |-- nd_perf.c:(.text):undefined-reference-to-perf_pmu_register
| `-- nd_perf.c:(.text):undefined-reference-to-perf_pmu_unregister

Similar build failure in nds32 architecture:
nd_perf.c:(.text+0x21e): undefined reference to `perf_pmu_migrate_context'
nd_perf.c:(.text+0x434): undefined reference to `perf_pmu_register'
nd_perf.c:(.text+0x57c): undefined reference to `perf_pmu_unregister'

Fix this issue by adding check for CONFIG_PERF_EVENTS config option
and disabling the nvdimm perf interface incase this config is not set.

Also remove function declaration of perf_pmu_migrate_context,
perf_pmu_register, perf_pmu_unregister functions from nd.h as these are
common pmu functions which are part of perf_event.h and since we
are disabling nvdimm perf interface incase CONFIG_PERF_EVENTS option
is not set, we not need to declare them in nd.h

Also move the platform_device header file addition part from nd.h to
nd_perf.c and add stub functions for register_nvdimm_pmu and
unregister_nvdimm_pmu functions to handle CONFIG_PERF_EVENTS=n
case.

Fixes: 0fab1ba6ad6b ("drivers/nvdimm: Add perf interface to expose nvdimm performance stats") (Commit id based on libnvdimm-for-next tree)
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Link: https://lore.kernel.org/all/62317124.YBQFU33+s%2FwdvWGj%25lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/20220323164550.109768-1-kjain@linux.ibm.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/nvdimm: Add perf interface to expose nvdimm performance stats

A common interface is added to get performance stats reporting
support for nvdimm devices. Added interface defines supported
event list, config fields for the event attributes and their
corresponding bit values which are exported via sysfs.

Interface also added support for pmu register/unregister functions,
cpu hotplug feature along with macros for handling events addition
via sysfs. It adds attribute groups for format, cpumask and events
to the pmu structure.

User could use the standard perf tool to access perf events exposed
via nvdimm pmu.

[Declare pmu functions in nd.h file to resolve implicit-function-declaration
warning and make hotplug function static as reported by kernel test robot]

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Link: https://lore.kernel.org/all/202202241242.zqzGkguy-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Madhavan Srinivasan <maddy@in.ibm.com>
Link: https://lore.kernel.org/r/20220225143024.47947-3-kjain@linux.ibm.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>