oprofile, s390: Rework hwsampler implementation

This patch is a rework of the hwsampler oprofile implementation that
has been applied recently. Now there are less non-architectural
changes. The only changes are:

* introduction of oprofile_add_ext_hw_sample(), and
* removal of section attributes of oprofile_timer_init/_exit().

To setup hwsampler for oprofile we need to modify start()/stop()
callbacks and additional hwsampler control files in oprofilefs. We do
not reinitialize the timer or hwsampler mode by restarting calling
init/exit() anymore, instead hwsampler_running is used to switch the
mode directly in oprofile_hwsampler_start/_stop(). For locking reasons
there is also hwsampler_file that reflects the value in oprofilefs.

The overall diffstat of the oprofile s390 hwsampler implemenation
shows the low impact to non-architectural code:

 arch/Kconfig                         |    3 +
 arch/s390/Kconfig                    |    1 +
 arch/s390/oprofile/Makefile          |    2 +-
 arch/s390/oprofile/hwsampler.c       | 1256 ++++++++++++++++++++++++++++++++++
 arch/s390/oprofile/hwsampler.h       |  113 +++
 arch/s390/oprofile/hwsampler_files.c |  162 +++++
 arch/s390/oprofile/init.c            |    6 +-
 drivers/oprofile/cpu_buffer.c        |   24 +-
 drivers/oprofile/timer_int.c         |    4 +-
 include/linux/oprofile.h             |    7 +
 10 files changed, 1567 insertions(+), 11 deletions(-)

Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>

2 files changed, 38 insertions, 23 deletions

diff --git a/arch/s390/oprofile/hwsampler_files.c b/arch/s390/oprofile/hwsampler_files.c
index 493f7cc4e86..2e1da2449ba 100644
--- a/arch/s390/oprofile/hwsampler_files.c
+++ b/arch/s390/oprofile/hwsampler_files.c
@@ -8,6 +8,7 @@
 #include <linux/errno.h>
 #include <linux/fs.h>
 
+#include "../../../drivers/oprofile/oprof.h"
 #include "hwsampler.h"
 
 #define DEFAULT_INTERVAL        4096
@@ -22,12 +23,20 @@ static unsigned long oprofile_max_interval;
 static unsigned long oprofile_sdbt_blocks = DEFAULT_SDBT_BLOCKS;
 static unsigned long oprofile_sdb_blocks = DEFAULT_SDB_BLOCKS;
 
-static unsigned long oprofile_hwsampler;
+static int hwsampler_file;
+static int hwsampler_running;   /* start_mutex must be held to change */
+
+static struct oprofile_operations timer_ops;
 
 static int oprofile_hwsampler_start(void)
 {
         int retval;
 
+        hwsampler_running = hwsampler_file;
+
+        if (!hwsampler_running)
+                return timer_ops.start();
+
         retval = hwsampler_allocate(oprofile_sdbt_blocks, oprofile_sdb_blocks);
         if (retval)
                 return retval;
@@ -41,25 +50,20 @@ static int oprofile_hwsampler_start(void)
 
 static void oprofile_hwsampler_stop(void)
 {
+        if (!hwsampler_running) {
+                timer_ops.stop();
+                return;
+        }
+
         hwsampler_stop_all();
         hwsampler_deallocate();
         return;
 }
 
-int oprofile_arch_set_hwsampler(struct oprofile_operations *ops)
-{
-        printk(KERN_INFO "oprofile: using hardware sampling\n");
-        ops->start = oprofile_hwsampler_start;
-        ops->stop = oprofile_hwsampler_stop;
-        ops->cpu_type = "timer";
-
-        return 0;
-}
-
 static ssize_t hwsampler_read(struct file *file, char __user *buf,
                 size_t count, loff_t *offset)
 {
-        return oprofilefs_ulong_to_user(oprofile_hwsampler, buf, count, offset);
+        return oprofilefs_ulong_to_user(hwsampler_file, buf, count, offset);
 }
 
 static ssize_t hwsampler_write(struct file *file, char const __user *buf,
@@ -75,15 +79,16 @@ static ssize_t hwsampler_write(struct file *file, char const __user *buf,
         if (retval)
                 return retval;
 
-        if (oprofile_hwsampler == val)
-                return -EINVAL;
-
-        retval = oprofile_set_hwsampler(val);
+        if (oprofile_started)
+                /*
+                 * save to do without locking as we set
+                 * hwsampler_running in start() when start_mutex is
+                 * held
+                 */
+                return -EBUSY;
 
-        if (retval)
-                return retval;
+        hwsampler_file = val;
 
-        oprofile_hwsampler = val;
         return count;
 }
 
@@ -98,7 +103,7 @@ static int oprofile_create_hwsampling_files(struct super_block *sb,
         struct dentry *hw_dir;
 
         /* reinitialize default values */
-        oprofile_hwsampler = 1;
+        hwsampler_file = 1;
 
         hw_dir = oprofilefs_mkdir(sb, root, "hwsampling");
         if (!hw_dir)
@@ -125,7 +130,6 @@ int oprofile_hwsampler_init(struct oprofile_operations* ops)
         /*
          * create hwsampler files only if hwsampler_setup() succeeds.
          */
-        ops->create_files = oprofile_create_hwsampling_files;
         oprofile_min_interval = hwsampler_query_min_interval();
         if (oprofile_min_interval < 0) {
                 oprofile_min_interval = 0;
@@ -136,11 +140,23 @@ int oprofile_hwsampler_init(struct oprofile_operations* ops)
                 oprofile_max_interval = 0;
                 return -ENODEV;
         }
-        oprofile_arch_set_hwsampler(ops);
+
+        if (oprofile_timer_init(ops))
+                return -ENODEV;
+
+        printk(KERN_INFO "oprofile: using hardware sampling\n");
+
+        memcpy(&timer_ops, ops, sizeof(timer_ops));
+
+        ops->start = oprofile_hwsampler_start;
+        ops->stop = oprofile_hwsampler_stop;
+        ops->create_files = oprofile_create_hwsampling_files;
+
         return 0;
 }
 
 void oprofile_hwsampler_exit(void)
 {
+        oprofile_timer_exit();
         hwsampler_shutdown();
 }
diff --git a/arch/s390/oprofile/init.c b/arch/s390/oprofile/init.c
index f6b3f724f59..059b44b9f17 100644
--- a/arch/s390/oprofile/init.c
+++ b/arch/s390/oprofile/init.c
@@ -11,7 +11,6 @@
 #include <linux/oprofile.h>
 #include <linux/init.h>
 #include <linux/errno.h>
-#include <linux/fs.h>
 
 extern int oprofile_hwsampler_init(struct oprofile_operations* ops);
 extern void oprofile_hwsampler_exit(void);