On Wed, Mar 10, 2021 at 01:11:38PM +0800, Jin Yao wrote: > A raw PMU event (eventsel+umask) in the form of rNNN is supported > by perf but lacks of checking for the validity of raw encoding. > > For example, bit 16 and bit 17 are not valid on KBL but perf doesn't > report warning when encoding with these bits. > > Before: > > # ./perf stat -e cpu/r031234/ -a -- sleep 1 > > Performance counter stats for 'system wide': > > 0 cpu/r031234/ > > 1.003798924 seconds time elapsed > > It may silently measure the wrong event! > > The kernel supported bits have been exported through > /sys/devices/<pmu>/format/. Perf collects the information to > 'struct perf_pmu_format' and links it to 'pmu->format' list. > > The 'struct perf_pmu_format' has a bitmap which records the > valid bits for this format. For example, > > root@kbl-ppc:/sys/devices/cpu/format# cat umask > config:8-15 > > The valid bits (bit8-bit15) are recorded in bitmap of format 'umask'. > > We collect total valid bits of all formats, save to a local variable > 'masks' and reverse it. Now '~masks' represents total invalid bits. > > bits = config & ~masks; > > The set bits in 'bits' indicate the invalid bits used in config. > Finally we use bitmap_scnprintf to report the invalid bits. > > Some architectures may not export supported bits through sysfs, > so if masks is 0, perf_pmu__warn_invalid_config directly returns. > > After: > > Single event without name: > > # ./perf stat -e cpu/r031234/ -a -- sleep 1 > WARNING: event 'N/A' not valid (bits 16-17 of config '31234' not supported > by kernel)! > > Performance counter stats for 'system wide': > > 0 cpu/r031234/ > > 1.001597373 seconds time elapsed > > Multiple events with names: > > # ./perf stat -e cpu/rf01234,name=aaa/,cpu/r031234,name=bbb/ -a -- sleep 1 > WARNING: event 'aaa' not valid (bits 20,22 of config 'f01234' not supported > by kernel)! > WARNING: event 'bbb' not valid (bits 16-17 of config '31234' not supported > by kernel)! > > Performance counter stats for 'system wide': > > 0 aaa > 0 bbb > > 1.001573787 seconds time elapsed > > Warnings are reported for invalid bits. > > Co-developed-by: Jiri Olsa <jo...@redhat.com> > Signed-off-by: Jin Yao <yao....@linux.intel.com>
Reviewed-by: Jiri Olsa <jo...@redhat.com> thanks, jirka
