linux-kernel - Re: [PATCH v3] perf pmu: Validate raw event with sysfs exported format bits

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Message-ID: <YEX91MTGMU41zeuF@krava>
Date:   Mon, 8 Mar 2021 11:35:00 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Jin Yao <yao.jin@...ux.intel.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v3] perf pmu: Validate raw event with sysfs exported
 format bits

On Mon, Mar 08, 2021 at 11:15:06AM +0800, Jin Yao wrote:

SNIP

> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 44ef28302fc7..03ab1e6d0418 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -1812,3 +1812,39 @@ 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;
> +	char buf[100];
> +	unsigned int i;
> +
> +	list_for_each_entry(format, &pmu->format, list)	{
> +		/*
> +		 * Skip extra configs such as config1/config2.
> +		 */
> +		if (format->value > 0)
> +			continue;

sorry I did not notice before, but could you please use more direct
approach like:

		if (format->value == PERF_PMU_FORMAT_VALUE_CONFIG) {
			break;
		}

this will be more obvious, also no need for the comment.. I spent some
time looking what's the value for ;-)

thanks,
jirka

> +
> +		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)
> +		return;
> +
> +	bits = config & ~masks;
> +	if (bits == 0)
> +		return;
> +
> +	bitmap_scnprintf((unsigned long *)&bits, sizeof(bits) * 8, buf, sizeof(buf));
> +
> +	pr_warning("WARNING: event '%s' not valid (bits %s of config "
> +		   "'%llx' not supported by kernel)!\n",
> +		   name ?: "N/A", buf, config);
> +}
> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> index 8164388478c6..160b0f561771 100644
> --- a/tools/perf/util/pmu.h
> +++ b/tools/perf/util/pmu.h
> @@ -123,4 +123,7 @@ int perf_pmu__convert_scale(const char *scale, char **end, double *sval);
>  
>  int perf_pmu__caps_parse(struct perf_pmu *pmu);
>  
> +void perf_pmu__warn_invalid_config(struct perf_pmu *pmu, __u64 config,
> +				   char *name);
> +
>  #endif /* __PMU_H */
> -- 
> 2.17.1
>