GCOV support

Change-Id: I73a446754cd03178055459eb75c7b2f87b51b0f3
Reviewed-on: http://gfw160.austin.ibm.com:8080/gerrit/635
Tested-by: Jenkins Server
Reviewed-by: A. Patrick Williams III <iawillia@us.ibm.com>

1 files changed, 102 insertions, 0 deletions

diff --git a/src/include/usr/gcov.h b/src/include/usr/gcov.h
new file mode 100644
index 000000000..dd249e1d5
--- /dev/null
+++ b/src/include/usr/gcov.h
@@ -0,0 +1,102 @@
+//  IBM_PROLOG_BEGIN_TAG
+//  This is an automatically generated prolog.
+//
+//  $Source: src/include/usr/gcov.h $
+//
+//  IBM CONFIDENTIAL
+//
+//  COPYRIGHT International Business Machines Corp. 2012
+//
+//  p1
+//
+//  Object Code Only (OCO) source materials
+//  Licensed Internal Code Source Materials
+//  IBM HostBoot Licensed Internal Code
+//
+//  The source code for this program is not published or other-
+//  wise divested of its trade secrets, irrespective of what has
+//  been deposited with the U.S. Copyright Office.
+//
+//  Origin: 30
+//
+//  IBM_PROLOG_END
+#ifndef __USR_GCOV_H
+#define __USR_GCOV_H
+
+/** @file gcov.h
+ *  @brief Header file to generate gcov_info chain for each module.
+ *
+ *  Each gcov-instrumented module needs to have its own gcov_info chain
+ *  and associated linking function.  Each .o file will have its own
+ *  gcov_info object which is added to the chain when the module is loaded
+ *  (static initializers) by calling the __gcov_init function.
+ *
+ *  We make the gcov_info chain unique per-module, instead of a single
+ *  global chain, so that we don't have bad pointers if a module was
+ *  loaded and then unloaded.
+ */
+
+#include <stddef.h>
+
+/** @struct gcov_info
+ *  @brief Structure generated by gcc.  Do not use.
+ *
+ *  This structure is automatically generated and instances of it created by
+ *  gcc when the --coverage compile option is used.  We don't need to
+ *  manipulate this structure from code except to fix up the chains as objects
+ *  are added to the chain.  The rest of this structure is parsed by the
+ *  Gcov.pm debug tool.
+ */
+struct gcov_info
+{
+    unsigned int version;  // Purposefully chose 'unsigned int' to match gcc.
+    gcov_info* next;
+    // Really there is more after here in the structure, but this is all
+    // we care about from an in-memory perspective.
+};
+
+// Preprocessor magic to create a variable name based off the module name.
+// GCOV_INFO_OBJ() will create a post-processed name like
+// 'foobar_gcov_info_head' or 'core_gcov_info_head'.
+#ifdef __HOSTBOOT_MODULE
+    #define __GCOV_PREFIX __HOSTBOOT_MODULE
+#else
+    #define __GCOV_PREFIX core
+#endif
+
+#define __GCOV_INFO_OBJ(X,Y) X ## Y
+#define _GCOV_INFO_OBJ(X,Y) __GCOV_INFO_OBJ(X,Y)
+#define GCOV_INFO_OBJ() _GCOV_INFO_OBJ(__GCOV_PREFIX, _gcov_info_head)
+
+/** Pointer to the beginning of the gcov_info chain for this module. */
+gcov_info* GCOV_INFO_OBJ() = NULL;
+
+/** Function called by module loading to add the object gcov_info instance
+ *  to the chain.
+ */
+extern "C"
+void __gcov_init(gcov_info* i_info)
+{
+    // Atomically push i_info onto the gcov_info_head stack.
+    do
+    {
+        i_info->next = GCOV_INFO_OBJ();
+    } while (!__sync_bool_compare_and_swap(&GCOV_INFO_OBJ(),
+                                           i_info->next, i_info));
+}
+
+/** Unneeded function but must be defined to compile.
+ *
+ *  This function appears to be typically used by libgcov.so when instrumented
+ *  on a real linux-based system.  It can be used to merge counters across
+ *  multiple runs or when a 'fork' occurs.  It doesn't appear that this
+ *  function ever gets called for us but the unresolved symbol is added to
+ *  the module (by gcc) so we've created a stub here to pass compile.
+ */
+extern "C"
+void __gcov_merge_add()
+{
+    while(1);
+}
+
+#endif