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>

1 files changed, 21 insertions, 0 deletions

diff --git a/include/linux/oprofile.h b/include/linux/oprofile.h
index 7f5cfd3b37dd..b517d869e1ad 100644
--- a/include/linux/oprofile.h
+++ b/include/linux/oprofile.h
@@ -91,6 +91,27 @@ int oprofile_arch_init(struct oprofile_operations * ops);
  */
 void oprofile_arch_exit(void);
 
+#ifdef CONFIG_HAVE_HWSAMPLER
+/**
+ * setup hardware sampler for oprofiling.
+ */
+
+int oprofile_set_hwsampler(unsigned long);
+
+/**
+ * hardware sampler module initialization for the s390 arch
+ */
+
+int oprofile_arch_set_hwsampler(struct oprofile_operations *ops);
+
+/**
+ * Add an s390 hardware sample.
+ */
+void oprofile_add_ext_hw_sample(unsigned long pc, struct pt_regs * const regs,
+        unsigned long event, int is_kernel,
+        struct task_struct *task);
+#endif /* CONFIG_HAVE_HWSAMPLER */
+
 /**
  * Add a sample. This may be called from any context.
  */