Messages in this thread Patch in this message | | | Date | Sat, 6 Mar 2021 20:12:39 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH v2] perf pmu: Validate raw event with sysfs exported format bits |
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On Fri, Mar 05, 2021 at 08:56:25AM +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 > > 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 use strbuf 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 not valid (bits 16 17 of config '31234' not supported by kernel)! > > Performance counter stats for 'system wide': > > 0 cpu/r031234/ > > 1.001414935 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 > 36 bbb > > 1.001565999 seconds time elapsed > > Warning is reported for invalid bits. > > Signed-off-by: Jin Yao <yao.jin@linux.intel.com> > --- > tools/perf/util/parse-events.c | 3 +++ > tools/perf/util/pmu.c | 46 ++++++++++++++++++++++++++++++++++ > tools/perf/util/pmu.h | 3 +++ > 3 files changed, 52 insertions(+) > > diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c > index 42c84adeb2fb..c0c0fab22cb8 100644 > --- a/tools/perf/util/parse-events.c > +++ b/tools/perf/util/parse-events.c > @@ -356,6 +356,9 @@ __add_event(struct list_head *list, int *idx, > struct perf_cpu_map *cpus = pmu ? perf_cpu_map__get(pmu->cpus) : > cpu_list ? perf_cpu_map__new(cpu_list) : NULL; > > + if (pmu && attr->type == PERF_TYPE_RAW) > + perf_pmu__warn_invalid_config(pmu, attr->config, name); > + > if (init_attr) > event_attr_init(attr); > > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c > index 44ef28302fc7..31e975b75766 100644 > --- a/tools/perf/util/pmu.c > +++ b/tools/perf/util/pmu.c > @@ -1812,3 +1812,49 @@ int perf_pmu__caps_parse(struct perf_pmu *pmu) > > return nr_caps; > } > + > +void perf_pmu__warn_invalid_config(struct perf_pmu *pmu, __u64 config, > + char *name) > +{ > + struct perf_pmu_format *format; > + __u64 masks = 0, bits; > + struct strbuf buf = STRBUF_INIT; > + unsigned int i; > + > + list_for_each_entry(format, &pmu->format, list) { > + /* > + * Skip extra configs such as config1/config2. > + */ > + if (format->value > 0) > + continue; > + > + for_each_set_bit(i, format->bits, PERF_PMU_FORMAT_BITS) > + masks |= 1ULL << i; > + } > + > + /* > + * Kernel doesn't export any valid format bits. > + */ > + if (masks == 0) > + goto out; > + > + bits = config & ~masks; > + if (bits == 0) > + goto out; > + > + for_each_set_bit(i, (unsigned long *)&bits, sizeof(bits) * 8) > + strbuf_addf(&buf, " %d", i); > + > + if (name) { > + pr_warning("WARNING: event '%s' not valid (bits%s of config " > + "'%llx' not supported by kernel)!\n", > + name, buf.buf, config); > + } else { > + pr_warning("WARNING: event not valid (bits%s of config " > + "'%llx' not supported by kernel)!\n", > + buf.buf, config); > + } > + > +out: > + strbuf_release(&buf); > +}
actualy we do have bitmap_scnprintf, which is already doing the printing in a nice way.. we could use it like below, only compile tested
jirka
--- diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c index 31e975b75766..37ca5eee2667 100644 --- a/tools/perf/util/pmu.c +++ b/tools/perf/util/pmu.c @@ -1818,7 +1818,7 @@ void perf_pmu__warn_invalid_config(struct perf_pmu *pmu, __u64 config, { struct perf_pmu_format *format; __u64 masks = 0, bits; - struct strbuf buf = STRBUF_INIT; + char buf[50]; unsigned int i; list_for_each_entry(format, &pmu->format, list) { @@ -1836,25 +1836,15 @@ void perf_pmu__warn_invalid_config(struct perf_pmu *pmu, __u64 config, * Kernel doesn't export any valid format bits. */ if (masks == 0) - goto out; + return; bits = config & ~masks; if (bits == 0) - goto out; - - for_each_set_bit(i, (unsigned long *)&bits, sizeof(bits) * 8) - strbuf_addf(&buf, " %d", i); + return; - if (name) { - pr_warning("WARNING: event '%s' not valid (bits%s of config " - "'%llx' not supported by kernel)!\n", - name, buf.buf, config); - } else { - pr_warning("WARNING: event not valid (bits%s of config " - "'%llx' not supported by kernel)!\n", - buf.buf, config); - } + bitmap_scnprintf((unsigned long *)&bits, sizeof(bits) * 8, buf, sizeof(buf)); -out: - strbuf_release(&buf); + pr_warning("WARNING: event '%s' not valid (bits%s of config " + "'%llx' not supported by kernel)!\n", + name ?: "N/A", buf, config); }
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