powerpc/perf: Fix oops when grouping different pmu events

[Michael Ellerman]

On Thu, 2017-11-30 at 08:33:22 UTC, Ravi Bangoria wrote:
> When user tries to group imc (In-Memory Collections) event with
> normal event, (sometime) kernel crashes with following log:
> 
>     Faulting instruction address: 0x00000000
>     [link register   ] c00000000010ce88 power_check_constraints+0x128/0x980
>     ...
>     c00000000010e238 power_pmu_event_init+0x268/0x6f0
>     c0000000002dc60c perf_try_init_event+0xdc/0x1a0
>     c0000000002dce88 perf_event_alloc+0x7b8/0xac0
>     c0000000002e92e0 SyS_perf_event_open+0x530/0xda0
>     c00000000000b004 system_call+0x38/0xe0
> 
> 'event_base' field of 'struct hw_perf_event' is used as flags for
> normal hw events and used as memory address for imc events. While
> grouping these two types of events, collect_events() tries to
> interpret imc 'event_base' as a flag, which causes a corruption
> resulting in a crash.
> 
> Consider only those events which belongs to 'perf_hw_context' in
> collect_events().
> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria at linux.vnet.ibm.com>
> Reviewed-By: Madhavan Srinivasan <maddy at linux.vnet.ibm.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/5aa04b3eb6fca63d2e9827be656dca

cheers