Commit 9fbc61f8 authored by Kan Liang's avatar Kan Liang Committed by Arnaldo Carvalho de Melo
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perf pmu: Add support for PMU capabilities 



The PMU capabilities information, which is located at
/sys/bus/event_source/devices/<dev>/caps, is required by perf tool.  For
example, the max LBR information is required to stitch LBR call stack.

Add perf_pmu__caps_parse() to parse the PMU capabilities information.
The information is stored in a list.

The following patch will store the capabilities information in perf
header.

Committer notes:

Here's an example of such directories and its files in an i5 7th gen
machine:

  [root@seventh ~]# ls -lad /sys/bus/event_source/devices/*/caps
  drwxr-xr-x. 2 root root 0 Apr 14 13:33 /sys/bus/event_source/devices/cpu/caps
  drwxr-xr-x. 2 root root 0 Apr 14 13:33 /sys/bus/event_source/devices/intel_pt/caps
  [root@seventh ~]# ls -la /sys/bus/event_source/devices/intel_pt/caps
  total 0
  drwxr-xr-x. 2 root root    0 Apr 14 13:33 .
  drwxr-xr-x. 5 root root    0 Apr 14 13:12 ..
  -r--r--r--. 1 root root 4096 Apr 16 13:10 cr3_filtering
  -r--r--r--. 1 root root 4096 Apr 16 11:42 cycle_thresholds
  -r--r--r--. 1 root root 4096 Apr 16 13:10 ip_filtering
  -r--r--r--. 1 root root 4096 Apr 16 13:10 max_subleaf
  -r--r--r--. 1 root root 4096 Apr 14 13:33 mtc
  -r--r--r--. 1 root root 4096 Apr 14 13:33 mtc_periods
  -r--r--r--. 1 root root 4096 Apr 16 13:10 num_address_ranges
  -r--r--r--. 1 root root 4096 Apr 16 13:10 output_subsys
  -r--r--r--. 1 root root 4096 Apr 16 13:10 payloads_lip
  -r--r--r--. 1 root root 4096 Apr 16 13:10 power_event_trace
  -r--r--r--. 1 root root 4096 Apr 14 13:33 psb_cyc
  -r--r--r--. 1 root root 4096 Apr 14 13:33 psb_periods
  -r--r--r--. 1 root root 4096 Apr 16 13:10 ptwrite
  -r--r--r--. 1 root root 4096 Apr 16 13:10 single_range_output
  -r--r--r--. 1 root root 4096 Apr 16 12:03 topa_multiple_entries
  -r--r--r--. 1 root root 4096 Apr 16 13:10 topa_output
  [root@seventh ~]# cat /sys/bus/event_source/devices/intel_pt/caps/topa_output
  1
  [root@seventh ~]# cat /sys/bus/event_source/devices/intel_pt/caps/topa_multiple_entries
  1
  [root@seventh ~]# cat /sys/bus/event_source/devices/intel_pt/caps/mtc
  1
  [root@seventh ~]# cat /sys/bus/event_source/devices/intel_pt/caps/power_event_trace
  0
  [root@seventh ~]#

  [root@seventh ~]# ls -la /sys/bus/event_source/devices/cpu/caps/
  total 0
  drwxr-xr-x. 2 root root    0 Apr 14 13:33 .
  drwxr-xr-x. 6 root root    0 Apr 14 13:12 ..
  -r--r--r--. 1 root root 4096 Apr 16 13:10 branches
  -r--r--r--. 1 root root 4096 Apr 14 13:33 max_precise
  -r--r--r--. 1 root root 4096 Apr 16 13:10 pmu_name
  [root@seventh ~]# cat /sys/bus/event_source/devices/cpu/caps/max_precise
  3
  [root@seventh ~]# cat /sys/bus/event_source/devices/cpu/caps/branches
  32
  [root@seventh ~]# cat /sys/bus/event_source/devices/cpu/caps/pmu_name
  skylake
  [root@seventh ~]#

Wow, first time I've heard about
/sys/bus/event_source/devices/cpu/caps/max_precise, I think I'll use it!
:-)

Signed-off-by: default avatarKan Liang <kan.liang@linux.intel.com>
Reviewed-by: default avatarAndi Kleen <ak@linux.intel.com>
Acked-by: default avatarJiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-2-kan.liang@linux.intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent f8ff18be

tools/perf/util/pmu.c

+82 −0
Original line number Diff line number Diff line
@@ -850,6 +850,7 @@ static struct perf_pmu *pmu_lookup(const char *name) 


	INIT_LIST_HEAD(&pmu->format);

	INIT_LIST_HEAD(&pmu->aliases);

	INIT_LIST_HEAD(&pmu->caps);

	list_splice(&format, &pmu->format);

	list_splice(&aliases, &pmu->aliases);

	list_add_tail(&pmu->list, &pmus);
@@ -1594,3 +1595,84 @@ int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt, 
	va_end(args);

	return ret;

}



static int perf_pmu__new_caps(struct list_head *list, char *name, char *value)

{

	struct perf_pmu_caps *caps = zalloc(sizeof(*caps));



	if (!caps)

		return -ENOMEM;



	caps->name = strdup(name);

	if (!caps->name)

		goto free_caps;

	caps->value = strndup(value, strlen(value) - 1);

	if (!caps->value)

		goto free_name;

	list_add_tail(&caps->list, list);

	return 0;



free_name:

	zfree(caps->name);

free_caps:

	free(caps);



	return -ENOMEM;

}



/*

 * Reading/parsing the given pmu capabilities, which should be located at:

 * /sys/bus/event_source/devices/<dev>/caps as sysfs group attributes.

 * Return the number of capabilities

 */

int perf_pmu__caps_parse(struct perf_pmu *pmu)

{

	struct stat st;

	char caps_path[PATH_MAX];

	const char *sysfs = sysfs__mountpoint();

	DIR *caps_dir;

	struct dirent *evt_ent;

	int nr_caps = 0;



	if (!sysfs)

		return -1;



	snprintf(caps_path, PATH_MAX,

		 "%s" EVENT_SOURCE_DEVICE_PATH "%s/caps", sysfs, pmu->name);



	if (stat(caps_path, &st) < 0)

		return 0;	/* no error if caps does not exist */



	caps_dir = opendir(caps_path);

	if (!caps_dir)

		return -EINVAL;



	while ((evt_ent = readdir(caps_dir)) != NULL) {

		char path[PATH_MAX + NAME_MAX + 1];

		char *name = evt_ent->d_name;

		char value[128];

		FILE *file;



		if (!strcmp(name, ".") || !strcmp(name, ".."))

			continue;



		snprintf(path, sizeof(path), "%s/%s", caps_path, name);



		file = fopen(path, "r");

		if (!file)

			continue;



		if (!fgets(value, sizeof(value), file) ||

		    (perf_pmu__new_caps(&pmu->caps, name, value) < 0)) {

			fclose(file);

			continue;

		}



		nr_caps++;

		fclose(file);

	}



	closedir(caps_dir);



	return nr_caps;

}

tools/perf/util/pmu.h

+9 −0
Original line number Diff line number Diff line
@@ -22,6 +22,12 @@ enum { 


struct perf_event_attr;



struct perf_pmu_caps {

	char *name;

	char *value;

	struct list_head list;

};



struct perf_pmu {

	char *name;

	__u32 type;
@@ -33,6 +39,7 @@ struct perf_pmu { 
	struct perf_cpu_map *cpus;

	struct list_head format;  /* HEAD struct perf_pmu_format -> list */

	struct list_head aliases; /* HEAD struct perf_pmu_alias -> list */

	struct list_head caps;    /* HEAD struct perf_pmu_caps -> list */

	struct list_head list;    /* ELEM */

};
@@ -107,4 +114,6 @@ bool pmu_uncore_alias_match(const char *pmu_name, const char *name); 


int perf_pmu__convert_scale(const char *scale, char **end, double *sval);



int perf_pmu__caps_parse(struct perf_pmu *pmu);



#endif /* __PMU_H */