oprofile, s390: Enhance OProfile to support System zs hardware sampling feature

OProfile is enhanced to export all files for controlling System z's
hardware sampling, and to invoke hwsampler exported functions to
initialize and use System z's hardware sampling.

The patch invokes hwsampler_setup() during oprofile init and exports
following hwsampler files under oprofilefs if hwsampler's setup
succeeded:

A new directory for hardware sampling based files

 /dev/oprofile/hwsampling/

The userland daemon must explicitly write to the following files
to disable (or enable) hardware based sampling

 /dev/oprofile/hwsampling/hwsampler

to modify the actual sampling rate

 /dev/oprofile/hwsampling/hw_interval

to modify the amount of sampling memory (measured in 4K pages)

 /dev/oprofile/hwsampling/hw_sdbt_blocks

The following files are read only and show
the possible minimum sampling rate

 /dev/oprofile/hwsampling/hw_min_interval

the possible maximum sampling rate

 /dev/oprofile/hwsampling/hw_max_interval

The patch splits the oprofile_timer_[init/exit] function so that it
can be also called through user context (oprofilefs) to avoid kernel
oops.

Applied with following changes:
* whitespace changes in Makefile and timer_int.c

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Maran Pakkirisamy <maranp@linux.vnet.ibm.com>
Signed-off-by: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>

3 files changed, 153 insertions, 2 deletions

diff --git a/arch/s390/oprofile/Makefile b/arch/s390/oprofile/Makefile
index d698cddcfbd..00d8fc8e442 100644
--- a/arch/s390/oprofile/Makefile
+++ b/arch/s390/oprofile/Makefile
@@ -6,4 +6,4 @@ DRIVER_OBJS = $(addprefix ../../../drivers/oprofile/, \
                 oprofilefs.o oprofile_stats.o  \
                 timer_int.o )
 
-oprofile-y :=   $(DRIVER_OBJS) init.o backtrace.o hwsampler.o
+oprofile-y :=   $(DRIVER_OBJS) init.o backtrace.o hwsampler.o hwsampler_files.o
diff --git a/arch/s390/oprofile/hwsampler_files.c b/arch/s390/oprofile/hwsampler_files.c
new file mode 100644
index 00000000000..493f7cc4e86
--- /dev/null
+++ b/arch/s390/oprofile/hwsampler_files.c
@@ -0,0 +1,146 @@
+/**
+ * arch/s390/oprofile/hwsampler_files.c
+ *
+ * Copyright IBM Corp. 2010
+ * Author: Mahesh Salgaonkar (mahesh@linux.vnet.ibm.com)
+ */
+#include <linux/oprofile.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+
+#include "hwsampler.h"
+
+#define DEFAULT_INTERVAL        4096
+
+#define DEFAULT_SDBT_BLOCKS     1
+#define DEFAULT_SDB_BLOCKS      511
+
+static unsigned long oprofile_hw_interval = DEFAULT_INTERVAL;
+static unsigned long oprofile_min_interval;
+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 oprofile_hwsampler_start(void)
+{
+        int retval;
+
+        retval = hwsampler_allocate(oprofile_sdbt_blocks, oprofile_sdb_blocks);
+        if (retval)
+                return retval;
+
+        retval = hwsampler_start_all(oprofile_hw_interval);
+        if (retval)
+                hwsampler_deallocate();
+
+        return retval;
+}
+
+static void oprofile_hwsampler_stop(void)
+{
+        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);
+}
+
+static ssize_t hwsampler_write(struct file *file, char const __user *buf,
+                size_t count, loff_t *offset)
+{
+        unsigned long val;
+        int retval;
+
+        if (*offset)
+                return -EINVAL;
+
+        retval = oprofilefs_ulong_from_user(&val, buf, count);
+        if (retval)
+                return retval;
+
+        if (oprofile_hwsampler == val)
+                return -EINVAL;
+
+        retval = oprofile_set_hwsampler(val);
+
+        if (retval)
+                return retval;
+
+        oprofile_hwsampler = val;
+        return count;
+}
+
+static const struct file_operations hwsampler_fops = {
+        .read           = hwsampler_read,
+        .write          = hwsampler_write,
+};
+
+static int oprofile_create_hwsampling_files(struct super_block *sb,
+                                                struct dentry *root)
+{
+        struct dentry *hw_dir;
+
+        /* reinitialize default values */
+        oprofile_hwsampler = 1;
+
+        hw_dir = oprofilefs_mkdir(sb, root, "hwsampling");
+        if (!hw_dir)
+                return -EINVAL;
+
+        oprofilefs_create_file(sb, hw_dir, "hwsampler", &hwsampler_fops);
+        oprofilefs_create_ulong(sb, hw_dir, "hw_interval",
+                                &oprofile_hw_interval);
+        oprofilefs_create_ro_ulong(sb, hw_dir, "hw_min_interval",
+                                &oprofile_min_interval);
+        oprofilefs_create_ro_ulong(sb, hw_dir, "hw_max_interval",
+                                &oprofile_max_interval);
+        oprofilefs_create_ulong(sb, hw_dir, "hw_sdbt_blocks",
+                                &oprofile_sdbt_blocks);
+
+        return 0;
+}
+
+int oprofile_hwsampler_init(struct oprofile_operations* ops)
+{
+        if (hwsampler_setup())
+                return -ENODEV;
+
+        /*
+         * 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;
+                return -ENODEV;
+        }
+        oprofile_max_interval = hwsampler_query_max_interval();
+        if (oprofile_max_interval < 0) {
+                oprofile_max_interval = 0;
+                return -ENODEV;
+        }
+        oprofile_arch_set_hwsampler(ops);
+        return 0;
+}
+
+void oprofile_hwsampler_exit(void)
+{
+        hwsampler_shutdown();
+}
diff --git a/arch/s390/oprofile/init.c b/arch/s390/oprofile/init.c
index 7a995113b91..f6b3f724f59 100644
--- a/arch/s390/oprofile/init.c
+++ b/arch/s390/oprofile/init.c
@@ -11,16 +11,21 @@
 #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);
 
 extern void s390_backtrace(struct pt_regs * const regs, unsigned int depth);
 
 int __init oprofile_arch_init(struct oprofile_operations* ops)
 {
         ops->backtrace = s390_backtrace;
-        return -ENODEV;
+
+        return oprofile_hwsampler_init(ops);
 }
 
 void oprofile_arch_exit(void)
 {
+        oprofile_hwsampler_exit();
 }