oprofile: convert oprofile from timer_hook to hrtimer

Oprofile is currently broken on systems running with NOHZ enabled.
A maximum of 1 tick is accounted via the timer_hook if a cpu sleeps
for a longer period of time. This does bad things to the percentages
in the profiler output. To solve this problem convert oprofile to
use a restarting hrtimer instead of the timer_hook.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>
diff --git a/drivers/oprofile/oprof.h b/drivers/oprofile/oprof.h
index cb92f5c..47e12cb 100644
--- a/drivers/oprofile/oprof.h
+++ b/drivers/oprofile/oprof.h
@@ -34,7 +34,8 @@
 struct dentry;
 
 void oprofile_create_files(struct super_block *sb, struct dentry *root);
-void oprofile_timer_init(struct oprofile_operations *ops);
+int oprofile_timer_init(struct oprofile_operations *ops);
+void oprofile_timer_exit(void);
 
 int oprofile_set_backtrace(unsigned long depth);
 int oprofile_set_timeout(unsigned long time);