s390/cpum_cf: Corrected return code for unauthorized counter sets

Previously, the cpum_cf PMU returned -EPERM if a counter is requested and
the counter set to which the counter belongs is not authorized.  According
to the perf_event_open() system call manual, an error code of EPERM indicates
an unsupported exclude setting or CAP_SYS_ADMIN is missing.

Use ENOENT to indicate that particular counters are not available when the
counter set which contains the counter is not authorized.  For generic events,
this might trigger a fall back, for example, to a software event.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/perf_cpum_cf.c

@@ -157,10 +157,14 @@ static int validate_ctr_auth(const struct hw_perf_event *hwc)
 
 	cpuhw = &get_cpu_var(cpu_hw_events);
 
-	/* check authorization for cpu counter sets */
+	/* Check authorization for cpu counter sets.
+	 * If the particular CPU counter set is not authorized,
+	 * return with -ENOENT in order to fall back to other
+	 * PMUs that might suffice the event request.
+	 */
 	ctrs_state = cpumf_state_ctl[hwc->config_base];
 	if (!(ctrs_state & cpuhw->info.auth_ctl))
-		err = -EPERM;
+		err = -ENOENT;
 
 	put_cpu_var(cpu_hw_events);
 	return err;
@@ -536,7 +540,7 @@ static int cpumf_pmu_add(struct perf_event *event, int flags)
 	 */
 	if (!(cpuhw->flags & PERF_EVENT_TXN))
 		if (validate_ctr_auth(&event->hw))
-			return -EPERM;
+			return -ENOENT;
 
 	ctr_set_enable(&cpuhw->state, event->hw.config_base);
 	event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
@@ -611,7 +615,7 @@ static int cpumf_pmu_commit_txn(struct pmu *pmu)
 	state = cpuhw->state & ~((1 << CPUMF_LCCTL_ENABLE_SHIFT) - 1);
 	state >>= CPUMF_LCCTL_ENABLE_SHIFT;
 	if ((state & cpuhw->info.auth_ctl) != state)
-		return -EPERM;
+		return -ENOENT;
 
 	cpuhw->flags &= ~PERF_EVENT_TXN;
 	perf_pmu_enable(pmu);