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Commit 66ec1191 authored by Mark Rutland's avatar Mark Rutland Committed by Arnaldo Carvalho de Melo
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perf pmu: Unbreak perf record for arm/arm64 with events with explicit PMU 



Currently, perf record is broken on arm/arm64 systems when the PMU is
specified explicitly as part of the event, e.g.

$ ./perf record -e armv8_cortex_a53/cpu_cycles/u true

In such cases, perf record fails to open events unless
perf_event_paranoid is set to -1, even if the PMU in question supports
mode exclusion. Further, even when perf_event_paranoid is toggled, no
samples are recorded.

This is an unintended side effect of commit:

  e3ba76de ("perf tools: Force uncore events to system wide monitoring)

... which assumes that if a PMU has an associated cpu_map, it is an
uncore PMU, and forces events for such PMUs to be system-wide.

This is not true for arm/arm64 systems, which can have heterogeneous
CPUs. To account for this, multiple CPU PMUs are exposed, each with a
"cpus" field under sysfs, which the perf tool parses into a cpu_map. ARM
PMUs do not have a "cpumask" file, and only have a "cpus" file. For the
gory details as to why, see commit:

 7e3fcffe ("perf pmu: Support alternative sysfs cpumask")

Given all of this, we can instead identify uncore PMUs by explicitly
checking for a "cpumask" file, and restore arm/arm64 PMU support back to
a working state. This patch does so, adding a new perf_pmu::is_uncore
field, and splitting the existing cpumask parsing so that it can be
reused.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Tested-by Will Deacon <will.deacon@arm.com>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: 4.12+ <stable@vger.kernel.org>
Fixes: e3ba76de ("perf tools: Force uncore events to system wide monitoring)
Link: http://lkml.kernel.org/r/1507315102-5942-1-git-send-email-mark.rutland@arm.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent e9516c08

tools/perf/util/parse-events.c

+5 −4
Original line number Diff line number Diff line
@@ -309,10 +309,11 @@ static char *get_config_name(struct list_head *head_terms) 
static struct perf_evsel *

__add_event(struct list_head *list, int *idx,

	    struct perf_event_attr *attr,

	    char *name, struct cpu_map *cpus,

	    char *name, struct perf_pmu *pmu,

	    struct list_head *config_terms, bool auto_merge_stats)

{

	struct perf_evsel *evsel;

	struct cpu_map *cpus = pmu ? pmu->cpus : NULL;



	event_attr_init(attr);
@@ -323,7 +324,7 @@ __add_event(struct list_head *list, int *idx, 
	(*idx)++;

	evsel->cpus        = cpu_map__get(cpus);

	evsel->own_cpus    = cpu_map__get(cpus);

	evsel->system_wide = !!cpus;

	evsel->system_wide = pmu ? pmu->is_uncore : false;

	evsel->auto_merge_stats = auto_merge_stats;



	if (name)
@@ -1233,7 +1234,7 @@ static int __parse_events_add_pmu(struct parse_events_state *parse_state, 


	if (!head_config) {

		attr.type = pmu->type;

		evsel = __add_event(list, &parse_state->idx, &attr, NULL, pmu->cpus, NULL, auto_merge_stats);

		evsel = __add_event(list, &parse_state->idx, &attr, NULL, pmu, NULL, auto_merge_stats);

		return evsel ? 0 : -ENOMEM;

	}
@@ -1254,7 +1255,7 @@ static int __parse_events_add_pmu(struct parse_events_state *parse_state, 
		return -EINVAL;



	evsel = __add_event(list, &parse_state->idx, &attr,

			    get_config_name(head_config), pmu->cpus,

			    get_config_name(head_config), pmu,

			    &config_terms, auto_merge_stats);

	if (evsel) {

		evsel->unit = info.unit;

tools/perf/util/pmu.c

+41 −15
Original line number Diff line number Diff line
@@ -470,16 +470,35 @@ static void pmu_read_sysfs(void) 
	closedir(dir);

}



static struct cpu_map *__pmu_cpumask(const char *path)

{

	FILE *file;

	struct cpu_map *cpus;



	file = fopen(path, "r");

	if (!file)

		return NULL;



	cpus = cpu_map__read(file);

	fclose(file);

	return cpus;

}



/*

 * Uncore PMUs have a "cpumask" file under sysfs. CPU PMUs (e.g. on arm/arm64)

 * may have a "cpus" file.

 */

#define CPUS_TEMPLATE_UNCORE	"%s/bus/event_source/devices/%s/cpumask"

#define CPUS_TEMPLATE_CPU	"%s/bus/event_source/devices/%s/cpus"



static struct cpu_map *pmu_cpumask(const char *name)

{

	struct stat st;

	char path[PATH_MAX];

	FILE *file;

	struct cpu_map *cpus;

	const char *sysfs = sysfs__mountpoint();

	const char *templates[] = {

		 "%s/bus/event_source/devices/%s/cpumask",

		 "%s/bus/event_source/devices/%s/cpus",

		CPUS_TEMPLATE_UNCORE,

		CPUS_TEMPLATE_CPU,

		NULL

	};

	const char **template;
@@ -489,20 +508,25 @@ static struct cpu_map *pmu_cpumask(const char *name) 


	for (template = templates; *template; template++) {

		snprintf(path, PATH_MAX, *template, sysfs, name);

		if (stat(path, &st) == 0)

			break;

		cpus = __pmu_cpumask(path);

		if (cpus)

			return cpus;

	}



	if (!*template)

	return NULL;

}



	file = fopen(path, "r");

	if (!file)

		return NULL;

static bool pmu_is_uncore(const char *name)

{

	char path[PATH_MAX];

	struct cpu_map *cpus;

	const char *sysfs = sysfs__mountpoint();



	cpus = cpu_map__read(file);

	fclose(file);

	return cpus;

	snprintf(path, PATH_MAX, CPUS_TEMPLATE_UNCORE, sysfs, name);

	cpus = __pmu_cpumask(path);

	cpu_map__put(cpus);



	return !!cpus;

}



/*
@@ -617,6 +641,8 @@ static struct perf_pmu *pmu_lookup(const char *name) 


	pmu->cpus = pmu_cpumask(name);



	pmu->is_uncore = pmu_is_uncore(name);



	INIT_LIST_HEAD(&pmu->format);

	INIT_LIST_HEAD(&pmu->aliases);

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

tools/perf/util/pmu.h

+1 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ struct perf_pmu { 
	char *name;

	__u32 type;

	bool selectable;

	bool is_uncore;

	struct perf_event_attr *default_config;

	struct cpu_map *cpus;

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