perfmon: fix overflo test only working on 64 bit counters.

3 files changed, 15 insertions, 3 deletions

diff --git a/kern/perfmon.c b/kern/perfmon.c
index 4bedd99..e7a1dfd 100644
--- a/kern/perfmon.c
+++ b/kern/perfmon.c
@@ -632,6 +632,12 @@ perfmon_event_write(struct perfmon_event *event, uint64_t value)
     return 0;
 }
 
+int
+perfmon_get_pmc_width(void)
+{
+    return pmu_driver.get_pmc_width();
+}
+
 #endif /* CONFIG_PERFMON_TEST */
 
 void
diff --git a/kern/perfmon_i.h b/kern/perfmon_i.h
index 5cb4d45..28cf16b 100644
--- a/kern/perfmon_i.h
+++ b/kern/perfmon_i.h
@@ -32,6 +32,11 @@
  */
 int perfmon_event_write(struct perfmon_event *event, uint64_t value);
 
+/*
+ * Returns the bit width of the register used in perfmon.
+ */
+int perfmon_get_pmc_width(void);
+
 #endif /* CONFIG_PERFMON_TEST */
 
 #endif /* _KERN_PERFMON_H */
diff --git a/test/test_perfmon_cpu.c b/test/test_perfmon_cpu.c
index 60db729..8ecb241 100644
--- a/test/test_perfmon_cpu.c
+++ b/test/test_perfmon_cpu.c
@@ -55,9 +55,11 @@ test_run(void *arg)
     struct perfmon_event *ev_cycle, *ev_instruction;
     struct perfmon_group *group;
     int error;
+    uint64_t pmc_max;
 
     (void)arg;
 
+    pmc_max = (1 << perfmon_get_pmc_width()) - 1;
     error = perfmon_group_create(&group);
     error_check(error, "perfmon_group_create");
 
@@ -85,10 +87,9 @@ test_run(void *arg)
 
     printf("checking with overflow ...\n");
     /* TODO: choose value depending of architecture */
-    perfmon_event_write(ev_cycle,
-                        UINT64_MAX - perfmon_event_read(ev_cycle) / 2);
+    perfmon_event_write(ev_cycle, pmc_max - perfmon_event_read(ev_cycle) / 2);
     perfmon_event_write(ev_instruction,
-                        UINT64_MAX - perfmon_event_read(ev_instruction) / 3);
+                        pmc_max - perfmon_event_read(ev_instruction) / 3);
     perfmon_event_reset(ev_cycle);
     perfmon_event_reset(ev_instruction);