[PATCH 21/36] perf pmu: Add helper function is_pmu_core to detect PMU CORE devices

Arnaldo Carvalho de Melo
2017-12-06T14:42:58Z

From: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>

On some platforms, PMU core devices sysfs name is not cpu.
Adding function is_pmu_core to detect PMU core devices using
core device specific hints in sysfs.

For arm64 platforms, all core devices have file "cpus" in sysfs.

Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
Tested-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Tested-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/n/tip-y1woxt1k2pqqwpprhonnft2s@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/pmu.c | 39 +++++++++++++++++++++++++++++++++++----
1 file changed, 35 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 4e7dd3a0f123..732ff579ec65 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -537,6 +537,34 @@ static bool pmu_is_uncore(const char *name)
}

/*
+ * PMU CORE devices have different name other than cpu in sysfs on some
+ * platforms. looking for possible sysfs files to identify as core device.
+ */
+static int is_pmu_core(const char *name)
+{
+ struct stat st;
+ char path[PATH_MAX];
+ const char *sysfs = sysfs__mountpoint();
+
+ if (!sysfs)
+ return 0;
+
+ /* Look for cpu sysfs (x86 and others) */
+ scnprintf(path, PATH_MAX, "%s/bus/event_source/devices/cpu", sysfs);
+ if ((stat(path, &st) == 0) &&
+ (strncmp(name, "cpu", strlen("cpu")) == 0))
+ return 1;
+
+ /* Look for cpu sysfs (specific to arm) */
+ scnprintf(path, PATH_MAX, "%s/bus/event_source/devices/%s/cpus",
+ sysfs, name);
+ if (stat(path, &st) == 0)
+ return 1;
+
+ return 0;
+}
+
+/*
* Return the CPU id as a raw string.
*
* Each architecture should provide a more precise id string that
@@ -609,7 +637,6 @@ static void pmu_add_cpu_aliases(struct list_head *head, struct perf_pmu *pmu)
*/
i = 0;
while (1) {
- const char *pname;

pe = &map->table[i++];
if (!pe->name) {
@@ -618,9 +645,13 @@ static void pmu_add_cpu_aliases(struct list_head *head, struct perf_pmu *pmu)
break;
}

- pname = pe->pmu ? pe->pmu : "cpu";
- if (strncmp(pname, name, strlen(pname)))
- continue;
+ if (!is_pmu_core(name)) {
+ /* check for uncore devices */
+ if (pe->pmu == NULL)
+ continue;
+ if (strncmp(pe->pmu, name, strlen(pe->pmu)))
+ continue;
+ }

/* need type casts to override 'const' */
__perf_pmu__new_alias(head, NULL, (char *)pe->name,
--
2.13.6