linux-kernel - Re: [PATCH v2 2/5] perf pmu: Support more complex PMU event aliasing

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Message-ID: <20190616095844.GC2500@krava>
Date:   Sun, 16 Jun 2019 11:58:44 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     John Garry <john.garry@...wei.com>
Cc:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        alexander.shishkin@...ux.intel.com, namhyung@...nel.org,
        tmricht@...ux.ibm.com, brueckner@...ux.ibm.com,
        kan.liang@...ux.intel.com, ben@...adent.org.uk,
        mathieu.poirier@...aro.org, mark.rutland@....com,
        will.deacon@....com, linux-kernel@...r.kernel.org,
        linuxarm@...wei.com, linux-arm-kernel@...ts.infradead.org,
        zhangshaokun@...ilicon.com
Subject: Re: [PATCH v2 2/5] perf pmu: Support more complex PMU event aliasing

On Fri, Jun 14, 2019 at 10:08:00PM +0800, John Garry wrote:
> The jevent "Unit" field is used for uncore PMU alias definition.
> 
> The form uncore_pmu_example_X is supported, where "X" is a wildcard,
> to support multiple instances of the same PMU in a system.
> 
> Unfortunately this format not suitable for all uncore PMUs; take the Hisi
> DDRC uncore PMU for example, where the name is in the form
> hisi_scclX_ddrcY.
> 
> For the current jevent parsing, we would be required to hardcode an uncore
> alias translation for each possible value of X. This is not scalable.
> 
> Instead, add support for "Unit" field in the form "hisi_sccl,ddrc", where
> we can match by hisi_scclX and ddrcY. Tokens in Unit field are 
> delimited by ','.
> 
> Signed-off-by: John Garry <john.garry@...wei.com>
> ---
>  tools/perf/util/pmu.c | 39 ++++++++++++++++++++++++++++++++++-----
>  1 file changed, 34 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 7e7299fee550..bc71c60589b5 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -700,6 +700,39 @@ struct pmu_events_map *perf_pmu__find_map(struct perf_pmu *pmu)
>  	return map;
>  }
>  
> +static bool pmu_uncore_alias_match(const char *pmu_name, const char *name)
> +{
> +	char *tmp, *tok, *str;
> +	bool res;
> +
> +	str = strdup(pmu_name);
> +	if (!str)
> +		return false;
> +
> +	/*
> +	 * uncore alias may be from different PMU with common
> +	 * prefix or matching tokens.
> +	 */
> +	tok = strtok_r(str, ",", &tmp);
> +	if (strncmp(pmu_name, tok, strlen(tok))) {

if tok is NULL in here we crash

> +		res = false;
> +		goto out;
> +	}
> +
> +	for (; tok; name += strlen(tok), tok = strtok_r(NULL, ",", &tmp)) {

why is name shifted in here?

jirka

> +		name = strstr(name, tok);
> +		if (!name) {
> +			res = false;
> +			goto out;
> +		}
> +	}
> +
> +	res = true;
> +out:
> +	free(str);
> +	return res;
> +}
> +
>  /*
>   * From the pmu_events_map, find the table of PMU events that corresponds
>   * to the current running CPU. Then, add all PMU events from that table
> @@ -730,12 +763,8 @@ static void pmu_add_cpu_aliases(struct list_head *head, struct perf_pmu *pmu)
>  			break;
>  		}
>  
> -		/*
> -		 * uncore alias may be from different PMU
> -		 * with common prefix
> -		 */
>  		if (pmu_is_uncore(name) &&
> -		    !strncmp(pname, name, strlen(pname)))
> +		    pmu_uncore_alias_match(pname, name))
>  			goto new_alias;
>  
>  		if (strcmp(pname, name))
> -- 
> 2.17.1
>