perf: add arch-dependent get_num_counters function

Change-Id: I2230af87e0c764d97115e833dccb1842946c1b94
Fujitsu: POSTK_DEBUG_ARCH_DEP_109

arch/arm64/kernel/perfctr.c

@@ -183,3 +183,8 @@ int ihk_mc_perfctr_fixed_init(int counter, int mode)
 {
 	return -1;
 }
+
+int ihk_mc_perf_get_num_counters(void)
+{
+	return cpu_pmu.per_cpu[ihk_mc_get_processor_id()].num_events;
+}

arch/x86_64/kernel/perfctr.c

@@ -498,3 +498,8 @@ int ihk_mc_perfctr_alloc_counter(unsigned int *type, unsigned long *config, unsi
 
 	return ret;
 }
+
+int ihk_mc_perf_get_num_counters(void)
+{
+	return NUM_PERF_COUNTERS;
+}

kernel/syscall.c

@@ -3768,9 +3768,10 @@ perf_counter_alloc(struct thread *thread)
 {
 	int ret = -EINVAL;
 	int i = 0;
+	const int counters = ihk_mc_perf_get_num_counters();
 
 	// find avail generic counter
-	for (i = 0; i < NUM_PERF_COUNTERS; i++) {
+	for (i = 0; i < counters; i++) {
 		if(!(thread->pmc_alloc_map & (1 << i))) {
 			ret = i;
 			break;

lib/include/ihk/perfctr.h

@@ -72,6 +72,7 @@ int ihk_mc_perfctr_read_mask(unsigned long counter_mask, unsigned long *value);
 unsigned long ihk_mc_perfctr_read(int counter);
 unsigned long ihk_mc_perfctr_read_msr(int counter);
 int ihk_mc_perfctr_alloc_counter(unsigned int *type, unsigned long *config, unsigned long pmc_status);
+int ihk_mc_perf_get_num_counters(void);
 
 #endif