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SubjectRe: [PATCH v1] perf tools: Fix pattern matching for same substring used in different pmu type
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And, though this patch is to fix the uncore_imc/uncore_imc_free_running mismatching issue. We are 
also surprised to see it can solve another hybrid PMU issue on Alderlake.

On Alderlake,

# ./perf stat -e cpu/event=0xc2,umask=0x2/ true

Performance counter stats for 'true':

702,246 cpu_core/event=0xc2,umask=0x2/
<not counted> cpu_atom/event=0xc2,umask=0x2/

It should error out with the wrong PMU rather than using 'cpu_core' and'cpu_atom' instead.

This is still the pattern matching issue. The pattern is "cpu*". Both "cpu_core" and "cpu_atom" can
match the pattern "cpu*", so the parser wrongly thinks they are the same PMU type.

Now with this patch,

# ./perf stat -e cpu/cpu-cycles/ true
event syntax error: 'cpu/cpu-cycles/'
\___ Cannot find PMU `cpu'. Missing kernel support?
Run 'perf list' for a list of valid events

Thanks
Jin Yao

On 6/9/2021 12:57 PM, Jin Yao wrote:
> Some different pmu types may have same substring. For example,
> on Icelake server, we have pmu types "uncore_imc" and
> "uncore_imc_free_running". Both pmu types have substring "uncore_imc".
> But the parser would wrongly think they are the same pmu type.
>
> We enable an imc event,
> perf stat -e uncore_imc/event=0xe3/ -a -- sleep 1
>
> Perf actually expands the event to:
> uncore_imc_0/event=0xe3/
> uncore_imc_1/event=0xe3/
> uncore_imc_2/event=0xe3/
> uncore_imc_3/event=0xe3/
> uncore_imc_4/event=0xe3/
> uncore_imc_5/event=0xe3/
> uncore_imc_6/event=0xe3/
> uncore_imc_7/event=0xe3/
> uncore_imc_free_running_0/event=0xe3/
> uncore_imc_free_running_1/event=0xe3/
> uncore_imc_free_running_3/event=0xe3/
> uncore_imc_free_running_4/event=0xe3/
>
> That's because the "uncore_imc_free_running" matches the
> pattern "uncore_imc*".
>
> Now we check that the last characters of pmu name is
> '_<digit>'.
>
> Fixes: b2b9d3a3f021 ("perf pmu: Support wildcards on pmu name in dynamic pmu events")
> Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
> ---
> tools/perf/util/parse-events.y | 2 ++
> tools/perf/util/pmu.c | 25 ++++++++++++++++++++++++-
> tools/perf/util/pmu.h | 1 +
> 3 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
> index aba12a4d488e..7a694c7f7f1a 100644
> --- a/tools/perf/util/parse-events.y
> +++ b/tools/perf/util/parse-events.y
> @@ -317,6 +317,8 @@ event_pmu_name opt_pmu_config
> strncmp($1, "uncore_", 7))
> name += 7;
> if (!fnmatch(pattern, name, 0)) {
> + if (!perf_pmu__valid_suffix($1, name))
> + continue;
> if (parse_events_copy_term_list(orig_terms, &terms))
> CLEANUP_YYABORT;
> if (!parse_events_add_pmu(_parse_state, list, pmu->name, terms, true, false))
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 88c8ecdc60b0..78af01959830 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -3,6 +3,7 @@
> #include <linux/compiler.h>
> #include <linux/string.h>
> #include <linux/zalloc.h>
> +#include <linux/ctype.h>
> #include <subcmd/pager.h>
> #include <sys/types.h>
> #include <errno.h>
> @@ -768,7 +769,7 @@ bool pmu_uncore_alias_match(const char *pmu_name, const char *name)
> */
> for (; tok; name += strlen(tok), tok = strtok_r(NULL, ",", &tmp)) {
> name = strstr(name, tok);
> - if (!name) {
> + if (!name || !perf_pmu__valid_suffix(tok, (char *)name)) {
> res = false;
> goto out;
> }
> @@ -1872,3 +1873,25 @@ bool perf_pmu__has_hybrid(void)
>
> return !list_empty(&perf_pmu__hybrid_pmus);
> }
> +
> +bool perf_pmu__valid_suffix(char *tok, char *pmu_name)
> +{
> + char *p;
> +
> + /*
> + * The pmu_name has substring tok. If the format of
> + * pmu_name is <tok> or <tok>_<digit>, return true.
> + */
> + p = pmu_name + strlen(tok);
> + if (*p == 0)
> + return true;
> +
> + if (*p != '_')
> + return false;
> +
> + ++p;
> + if (*p == 0 || !isdigit(*p))
> + return false;
> +
> + return true;
> +}
> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> index a790ef758171..ebfd2b71532b 100644
> --- a/tools/perf/util/pmu.h
> +++ b/tools/perf/util/pmu.h
> @@ -133,5 +133,6 @@ void perf_pmu__warn_invalid_config(struct perf_pmu *pmu, __u64 config,
> char *name);
>
> bool perf_pmu__has_hybrid(void);
> +bool perf_pmu__valid_suffix(char *tok, char *pmu_name);
>
> #endif /* __PMU_H */
>

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