From: Athira Rajeev atrajeev@linux.vnet.ibm.com
[ Upstream commit b9c001276d4a756f98cc7dc4672eff5343949203 ]
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. eg:
$ perf record -b -o- -B --branch-filter any,ind_call true
None of the Power PMUs support having multiple branch filters at the same time. 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.
eg: $ 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 disgoel@linux.vnet.ibm.com Signed-off-by: Athira Rajeev atrajeev@linux.vnet.ibm.com Tested-by: Disha Goeldisgoel@linux.vnet.ibm.com Reviewed-by: Madhavan Srinivasan maddy@linux.ibm.com Reviewed-by: Kajol Jain kjain@linux.ibm.com [mpe: Tweak comment and change log wording] Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20220921145255.20972-1-atrajeev@linux.vnet.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/perf/core-book3s.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c index 6f013e418834..5433cb961fab 100644 --- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -1963,6 +1963,23 @@ static int power_pmu_event_init(struct perf_event *event) if (has_branch_stack(event)) { u64 bhrb_filter = -1;
+ /* + * Currently no PMU supports having multiple branch filters + * at the same time. 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(). 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) { + local_irq_restore(irq_flags); + return -EOPNOTSUPP; + } + if (ppmu->bhrb_filter_map) bhrb_filter = ppmu->bhrb_filter_map( event->attr.branch_sample_type);