On 9/16/22 17:02, Disha Goel wrote:
>
> On 9/13/22 5:25 PM, Athira Rajeev wrote:
>> For PERF_SAMPLE_BRANCH_STACK sample type, different branch_sample_type
>> ie branch filters are supported. The branch filters are requested via
>> event attribute "branch_sample_type". Multiple branch filters can be
>> passed in event attribute.
>>
>> Example:
>> perf record -b -o- -B --branch-filter any,ind_call true
>>
>> Powerpc does not support having multiple branch filters at
>> sametime. In powerpc, branch filters for branch stack sampling
>> is set via MMCRA IFM bits [32:33]. But currently when requesting
>> for multiple filter types, the "perf record" command does not
>> report any error.
>>
>> Example:
>> perf record -b -o- -B --branch-filter any,save_type true
>> perf record -b -o- -B --branch-filter any,ind_call true
>>
>> The "bhrb_filter_map" function in PMU driver code does the
>> validity check for supported branch filters. But this check
>> is done for single filter. Hence "perf record" will proceed
>> here without reporting any error.
>>
>> Fix power_pmu_event_init to return EOPNOTSUPP when multiple
>> branch filters are requested in the event attr.
>>
>> After the fix:
>> perf record --branch-filter any,ind_call -- ls
>> Error:
>> cycles: PMU Hardware doesn't support sampling/overflow-interrupts.
>> Try 'perf stat'
>>
>> Reported-by: Disha Goel <disg...@linux.vnet.ibm.com>
>> Signed-off-by: Athira Rajeev <atraj...@linux.vnet.ibm.com>
>> Reviewed-by: Madhavan Srinivasan <ma...@linux.ibm.com>
>
> Tested-by: Disha Goel <disg...@linux.vnet.ibm.com>
Patch looks good to me.
Reviewed-By: Kajol Jain <kj...@linux.ibm.com>
Thanks,
Kajol Jain
>
>> ---
>> arch/powerpc/perf/core-book3s.c | 15 +++++++++++++++
>> 1 file changed, 15 insertions(+)
>>
>> diff --git a/arch/powerpc/perf/core-book3s.c
>> b/arch/powerpc/perf/core-book3s.c
>> index 13919eb96931..2c2d235cb8d8 100644
>> --- a/arch/powerpc/perf/core-book3s.c
>> +++ b/arch/powerpc/perf/core-book3s.c
>> @@ -2131,6 +2131,21 @@ static int power_pmu_event_init(struct perf_event
>> *event)
>> if (has_branch_stack(event)) {
>> u64 bhrb_filter = -1;
>>
>> + /*
>> + * powerpc does not support having multiple branch filters
>> + * at sametime. Branch filters are set via MMCRA IFM[32:33]
>> + * bits for power8 and above. Return EOPNOTSUPP when multiple
>> + * branch filters are requested in the event attr.
>> + *
>> + * When opening event via perf_event_open, branch_sample_type
>> + * gets adjusted in perf_copy_attr function. Kernel will
>> + * automatically adjust the branch_sample_type based on the
>> + * event modifier settings to include
>> PERF_SAMPLE_BRANCH_PLM_ALL.
>> + * Hence drop the check for PERF_SAMPLE_BRANCH_PLM_ALL.
>> + */
>> + if (hweight64(event->attr.branch_sample_type &
>> ~PERF_SAMPLE_BRANCH_PLM_ALL) > 1)
>> + return -EOPNOTSUPP;
>> +
>> if (ppmu->bhrb_filter_map)
>> bhrb_filter = ppmu->bhrb_filter_map(
>> event->attr.branch_sample_type);
