Re: [PATCH v7 1/8] perf pmu: "Compat" supports matching multiple identifiers

[Jing Zhang]

在 2023/8/24 下午11:05, Robin Murphy 写道:
> On 21/08/2023 9:36 am, Jing Zhang wrote:
>> The jevent "Compat" is used for uncore PMU alias or metric definitions.
>>
>> The same PMU driver has different PMU identifiers due to different
>> hardware versions and types, but they may have some common PMU event.
>> Since a Compat value can only match one identifier, when adding the
>> same event alias to PMUs with different identifiers, each identifier
>> needs to be defined once, which is not streamlined enough.
>>
>> So let "Compat" supports matching multiple identifiers for uncore PMU
>> alias. For example, the Compat value {43401;436*} can match the PMU
>> identifier "43401", that is, CMN600_r0p0, and the PMU identifier with
>> the prefix "436", that is, all CMN650, where "*" is a wildcard.
>> Tokens in Unit field are delimited by ';' with no spaces.
> 
> I wonder is there any possibility of supporting multiple values as a JSON array, rather than a single delimited string? Otherwise, if we're putting restrictions on what characters a driver can expose as an identifier, then I think that really wants explicitly documenting. AFAICT there's currently not even any documentation of the de-facto ABI that it's expected to be a free-form string rather than completely arbitrary binary data.
> 

I'm sorry I almost missed this message, as it was in my spam folder.

If we put multiple values as an array, its parsing in jevent.py will become complicated.
I agree that we need to document the character restrictions for driver identifier composition.
Both Unit and Compat have the same problem, so certain characters need to be restricted in
the identifiers and names of drivers. However, it seems that there is no such document.

Thanks,
Jing

> Thanks,
> Robin.
> 
>> Signed-off-by: Jing Zhang <renyu.zj@xxxxxxxxxxxxxxxxx>
>> Reviewed-by: John Garry <john.g.garry@xxxxxxxxxx>
>> ---
>>   tools/perf/util/pmu.c | 33 +++++++++++++++++++++++++++++++--
>>   tools/perf/util/pmu.h |  1 +
>>   2 files changed, 32 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
>> index ad209c8..6402423 100644
>> --- a/tools/perf/util/pmu.c
>> +++ b/tools/perf/util/pmu.c
>> @@ -776,6 +776,35 @@ static bool pmu_uncore_alias_match(const char *pmu_name, const char *name)
>>       return res;
>>   }
>>   +bool pmu_uncore_identifier_match(const char *id, const char *compat)
>> +{
>> +    char *tmp = NULL, *tok, *str;
>> +    bool res;
>> +    int n;
>> +
>> +    /*
>> +     * The strdup() call is necessary here because "compat" is a const str*
>> +     * type and cannot be used as an argument to strtok_r().
>> +     */
>> +    str = strdup(compat);
>> +    if (!str)
>> +        return false;
>> +
>> +    tok = strtok_r(str, ";", &tmp);
>> +    for (; tok; tok = strtok_r(NULL, ";", &tmp)) {
>> +        n = strlen(tok);
>> +        if ((tok[n - 1] == '*' && !strncmp(id, tok, n - 1)) ||
>> +            !strcmp(id, tok)) {
>> +            res = true;
>> +            goto out;
>> +        }
>> +    }
>> +    res = false;
>> +out:
>> +    free(str);
>> +    return res;
>> +}
>> +
>>   struct pmu_add_cpu_aliases_map_data {
>>       struct list_head *head;
>>       const char *name;
>> @@ -847,8 +876,8 @@ static int pmu_add_sys_aliases_iter_fn(const struct pmu_event *pe,
>>       if (!pe->compat || !pe->pmu)
>>           return 0;
>>   -    if (!strcmp(pmu->id, pe->compat) &&
>> -        pmu_uncore_alias_match(pe->pmu, pmu->name)) {
>> +    if (pmu_uncore_alias_match(pe->pmu, pmu->name) &&
>> +        pmu_uncore_identifier_match(pmu->id, pe->compat)) {
>>           __perf_pmu__new_alias(idata->head, -1,
>>                         (char *)pe->name,
>>                         (char *)pe->desc,
>> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
>> index b9a02de..9d4385d 100644
>> --- a/tools/perf/util/pmu.h
>> +++ b/tools/perf/util/pmu.h
>> @@ -241,6 +241,7 @@ void pmu_add_cpu_aliases_table(struct list_head *head, struct perf_pmu *pmu,
>>   char *perf_pmu__getcpuid(struct perf_pmu *pmu);
>>   const struct pmu_events_table *pmu_events_table__find(void);
>>   const struct pmu_metrics_table *pmu_metrics_table__find(void);
>> +bool pmu_uncore_identifier_match(const char *id, const char *compat);
>>   void perf_pmu_free_alias(struct perf_pmu_alias *alias);
>>     int perf_pmu__convert_scale(const char *scale, char **end, double *sval);