s390/perf: cpum_cf: fallback to software sampling events

The CPU-measurement counter facility does not support sampling events
and returns -EINVAL in that case.  This return code lets the perf tool
fail.  To fall back to software sampling events, return -ENOENT instead.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c
index 86ec7447e1f5..390d9ae57bb2 100644
--- a/arch/s390/kernel/perf_cpum_cf.c
+++ b/arch/s390/kernel/perf_cpum_cf.c
@@ -367,13 +367,6 @@ static int __hw_perf_event_init(struct perf_event *event)
         if (ev >= PERF_CPUM_CF_MAX_CTR)
                 return -EINVAL;
 
-        /* The CPU measurement counter facility does not have any interrupts
-         * to do sampling.  Sampling must be provided by external means,
-         * for example, by timers.
-         */
-        if (hwc->sample_period)
-                return -EINVAL;
-
         /* Use the hardware perf event structure to store the counter number
          * in 'config' member and the counter set to which the counter belongs
          * in the 'config_base'.  The counter set (config_base) is then used
@@ -418,6 +411,12 @@ static int cpumf_pmu_event_init(struct perf_event *event)
         case PERF_TYPE_HARDWARE:
         case PERF_TYPE_HW_CACHE:
         case PERF_TYPE_RAW:
+                /* The CPU measurement counter facility does not have overflow
+                 * interrupts to do sampling.  Sampling must be provided by
+                 * external means, for example, by timers.
+                 */
+                if (is_sampling_event(event))
+                        return -ENOENT;
                 err = __hw_perf_event_init(event);
                 break;
         default: