Implement GCC code coverage analysis

In order to provide some insight on what code is executed during
coreboot's run time and how well our test scenarios work, this
adds code coverage support to coreboot's ram stage. This should
be easily adaptable for payloads, and maybe even romstage.

See http://gcc.gnu.org/onlinedocs/gcc/Gcov.html for
more information.

To instrument coreboot, select CONFIG_COVERAGE ("Code coverage
support") in Kconfig, and recompile coreboot. coreboot will then
store its code coverage information into CBMEM, if possible.
Then, run "cbmem -CV" as root on the target system running the
instrumented coreboot binary. This will create a whole bunch of
.gcda files that contain coverage information. Tar them up, copy
them to your build system machine, and untar them. Then you can
use your favorite coverage utility (gcov, lcov, ...) to visualize
code coverage.

For a sneak peak of what will expect you, please take a look
at http://www.coreboot.org/~stepan/coreboot-coverage/

Change-Id: Ib287d8309878a1f5c4be770c38b1bc0bb3aa6ec7
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/2052
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Reviewed-by: Martin Roth <martin@se-eng.com>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

1 files changed, 1157 insertions, 0 deletions

diff --git a/src/lib/libgcov.c b/src/lib/libgcov.c
new file mode 100644
index 0000000000..4adf75ebff
--- /dev/null
+++ b/src/lib/libgcov.c
@@ -0,0 +1,1157 @@
+/* Routines required for instrumenting a program.  */
+/* Compile this one with gcc.  */
+/* Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
+   2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009, 2010, 2011
+   Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+#define __COREBOOT__
+#ifdef __COREBOOT__
+#include <stdlib.h>
+#include <string.h>
+#include <console/console.h>
+#include <assert.h>
+typedef s32 pid_t;
+#define gcc_assert(x) ASSERT(x)
+#define fprintf(file, x...) printk(BIOS_ERR, x)
+#define alloca(size)   __builtin_alloca (size)
+#include "gcov-glue.c"
+
+/* Define MACROs to be used by coreboot compilation.  */
+# define L_gcov
+# define L_gcov_interval_profiler
+# define L_gcov_pow2_profiler
+# define L_gcov_one_value_profiler
+# define L_gcov_indirect_call_profiler
+# define L_gcov_average_profiler
+# define L_gcov_ior_profiler
+
+# define HAVE_CC_TLS 0
+# define __GCOV_KERNEL__
+
+# define IN_LIBGCOV 1
+# define IN_GCOV 0
+#else /* __COREBOOT__ */
+#include "tconfig.h"
+#include "tsystem.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "libgcc_tm.h"
+#endif /* __COREBOOT__ */
+
+#ifndef __COREBOOT__
+#if defined(inhibit_libc)
+#define IN_LIBGCOV (-1)
+#else
+#undef NULL /* Avoid errors if stdio.h and our stddef.h mismatch.  */
+#include <stdio.h>
+#define IN_LIBGCOV 1
+#if defined(L_gcov)
+#define GCOV_LINKAGE /* nothing */
+#endif
+#endif
+#endif /* __COREBOOT__ */
+#include "gcov-io.h"
+
+#if defined(inhibit_libc)
+/* If libc and its header files are not available, provide dummy functions.  */
+
+#ifdef L_gcov
+void __gcov_init (struct gcov_info *p __attribute__ ((unused))) {}
+void __gcov_flush (void) {}
+#endif
+
+#ifdef L_gcov_merge_add
+void __gcov_merge_add (gcov_type *counters  __attribute__ ((unused)),
+		       unsigned n_counters __attribute__ ((unused))) {}
+#endif
+
+#ifdef L_gcov_merge_single
+void __gcov_merge_single (gcov_type *counters  __attribute__ ((unused)),
+			  unsigned n_counters __attribute__ ((unused))) {}
+#endif
+
+#ifdef L_gcov_merge_delta
+void __gcov_merge_delta (gcov_type *counters  __attribute__ ((unused)),
+			 unsigned n_counters __attribute__ ((unused))) {}
+#endif
+
+#else
+
+#ifndef __COREBOOT__
+#include <string.h>
+#if GCOV_LOCKED
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/stat.h>
+#endif
+#else
+void __gcov_merge_add(gcov_type *counters  __attribute__ ((unused)),
+			unsigned n_counters __attribute__ ((unused))) {}
+#endif /* __COREBOOT__ */
+
+#ifdef L_gcov
+#include "gcov-io.c"
+
+struct gcov_fn_buffer
+{
+  struct gcov_fn_buffer *next;
+  unsigned fn_ix;
+  struct gcov_fn_info info;
+  /* note gcov_fn_info ends in a trailing array.  */
+};
+
+/* Chain of per-object gcov structures.  */
+static struct gcov_info *gcov_list;
+
+/* Size of the longest file name. */
+static size_t gcov_max_filename = 0;
+
+/* Make sure path component of the given FILENAME exists, create
+   missing directories. FILENAME must be writable.
+   Returns zero on success, or -1 if an error occurred.  */
+
+static int
+create_file_directory (char *filename)
+{
+#ifdef __COREBOOT__
+  (void) filename;
+  return 0;
+#else
+#if !defined(TARGET_POSIX_IO) && !defined(_WIN32)
+  (void) filename;
+  return -1;
+#else
+  char *s;
+
+  s = filename;
+
+  if (HAS_DRIVE_SPEC(s))
+    s += 2;
+  if (IS_DIR_SEPARATOR(*s))
+    ++s;
+  for (; *s != '\0'; s++)
+    if (IS_DIR_SEPARATOR(*s))
+      {
+        char sep = *s;
+	*s  = '\0';
+
+        /* Try to make directory if it doesn't already exist.  */
+        if (access (filename, F_OK) == -1
+#ifdef TARGET_POSIX_IO
+            && mkdir (filename, 0755) == -1
+#else
+            && mkdir (filename) == -1
+#endif
+            /* The directory might have been made by another process.  */
+	    && errno != EEXIST)
+	  {
+            fprintf (stderr, "profiling:%s:Cannot create directory\n",
+		     filename);
+            *s = sep;
+	    return -1;
+	  };
+
+	*s = sep;
+      };
+  return 0;
+#endif
+#endif
+}
+
+static struct gcov_fn_buffer *
+free_fn_data (const struct gcov_info *gi_ptr, struct gcov_fn_buffer *buffer,
+	      unsigned limit)
+{
+  struct gcov_fn_buffer *next;
+  unsigned ix, n_ctr = 0;
+
+  if (!buffer)
+    return 0;
+  next = buffer->next;
+
+  for (ix = 0; ix != limit; ix++)
+    if (gi_ptr->merge[ix])
+      free (buffer->info.ctrs[n_ctr++].values);
+  free (buffer);
+  return next;
+}
+
+static struct gcov_fn_buffer **
+buffer_fn_data (const char *filename, const struct gcov_info *gi_ptr,
+		struct gcov_fn_buffer **end_ptr, unsigned fn_ix)
+{
+  unsigned n_ctrs = 0, ix = 0;
+  struct gcov_fn_buffer *fn_buffer;
+  unsigned len;
+
+  for (ix = GCOV_COUNTERS; ix--;)
+    if (gi_ptr->merge[ix])
+      n_ctrs++;
+
+  len = sizeof (*fn_buffer) + sizeof (fn_buffer->info.ctrs[0]) * n_ctrs;
+  fn_buffer = (struct gcov_fn_buffer *)malloc (len);
+
+  if (!fn_buffer)
+    goto fail;
+
+  fn_buffer->next = 0;
+  fn_buffer->fn_ix = fn_ix;
+  fn_buffer->info.ident = gcov_read_unsigned ();
+  fn_buffer->info.lineno_checksum = gcov_read_unsigned ();
+  fn_buffer->info.cfg_checksum = gcov_read_unsigned ();
+
+  for (n_ctrs = ix = 0; ix != GCOV_COUNTERS; ix++)
+    {
+      gcov_unsigned_t length;
+      gcov_type *values;
+
+      if (!gi_ptr->merge[ix])
+	continue;
+
+      if (gcov_read_unsigned () != GCOV_TAG_FOR_COUNTER (ix))
+	{
+	  len = 0;
+	  goto fail;
+	}
+
+      length = GCOV_TAG_COUNTER_NUM (gcov_read_unsigned ());
+      len = length * sizeof (gcov_type);
+      values = (gcov_type *)malloc (len);
+      if (!values)
+	goto fail;
+
+      fn_buffer->info.ctrs[n_ctrs].num = length;
+      fn_buffer->info.ctrs[n_ctrs].values = values;
+
+      while (length--)
+	*values++ = gcov_read_counter ();
+      n_ctrs++;
+    }
+
+  *end_ptr = fn_buffer;
+  return &fn_buffer->next;
+
+fail:
+  fprintf (stderr, "profiling:%s:Function %u %s %u \n", filename, fn_ix,
+	   len ? "cannot allocate" : "counter mismatch", len ? len : ix);
+
+  return (struct gcov_fn_buffer **)free_fn_data (gi_ptr, fn_buffer, ix);
+}
+
+/* Add an unsigned value to the current crc */
+
+static gcov_unsigned_t
+crc32_unsigned (gcov_unsigned_t crc32, gcov_unsigned_t value)
+{
+  unsigned ix;
+
+  for (ix = 32; ix--; value <<= 1)
+    {
+      unsigned feedback;
+
+      feedback = (value ^ crc32) & 0x80000000 ? 0x04c11db7 : 0;
+      crc32 <<= 1;
+      crc32 ^= feedback;
+    }
+
+  return crc32;
+}
+
+/* Check if VERSION of the info block PTR matches libgcov one.
+   Return 1 on success, or zero in case of versions mismatch.
+   If FILENAME is not NULL, its value used for reporting purposes
+   instead of value from the info block.  */
+
+static int
+gcov_version (struct gcov_info *ptr, gcov_unsigned_t version,
+	      const char *filename)
+{
+  if (version != GCOV_VERSION)
+    {
+      char v[4], e[4];
+
+      GCOV_UNSIGNED2STRING (v, version);
+      GCOV_UNSIGNED2STRING (e, GCOV_VERSION);
+
+      fprintf (stderr,
+	       "profiling:%s:Version mismatch - expected %.4s got %.4s\n",
+	       filename? filename : ptr->filename, e, v);
+      return 0;
+    }
+  return 1;
+}
+
+/* Dump the coverage counts. We merge with existing counts when
+   possible, to avoid growing the .da files ad infinitum. We use this
+   program's checksum to make sure we only accumulate whole program
+   statistics to the correct summary. An object file might be embedded
+   in two separate programs, and we must keep the two program
+   summaries separate.  */
+
+static void
+gcov_exit (void)
+{
+  struct gcov_info *gi_ptr;
+  const struct gcov_fn_info *gfi_ptr;
+  struct gcov_summary this_prg; /* summary for program.  */
+  struct gcov_summary all_prg;  /* summary for all instances of program.  */
+  struct gcov_ctr_summary *cs_ptr;
+  const struct gcov_ctr_info *ci_ptr;
+  unsigned t_ix;
+  int f_ix = 0;
+  gcov_unsigned_t c_num;
+  const char *gcov_prefix;
+  int gcov_prefix_strip = 0;
+  size_t prefix_length;
+  char *gi_filename, *gi_filename_up;
+  gcov_unsigned_t crc32 = 0;
+
+  memset (&all_prg, 0, sizeof (all_prg));
+  /* Find the totals for this execution.  */
+  memset (&this_prg, 0, sizeof (this_prg));
+  for (gi_ptr = gcov_list; gi_ptr; gi_ptr = gi_ptr->next)
+    {
+      crc32 = crc32_unsigned (crc32, gi_ptr->stamp);
+      crc32 = crc32_unsigned (crc32, gi_ptr->n_functions);
+ 
+      for (f_ix = 0; (unsigned)f_ix != gi_ptr->n_functions; f_ix++)
+	{
+	  gfi_ptr = gi_ptr->functions[f_ix];
+
+	  if (gfi_ptr && gfi_ptr->key != gi_ptr)
+	    gfi_ptr = 0;
+
+	  crc32 = crc32_unsigned (crc32, gfi_ptr ? gfi_ptr->cfg_checksum : 0);
+	  crc32 = crc32_unsigned (crc32,
+				  gfi_ptr ? gfi_ptr->lineno_checksum : 0);
+	  if (!gfi_ptr)
+	    continue;
+
+	  ci_ptr = gfi_ptr->ctrs;
+	  for (t_ix = 0; t_ix != GCOV_COUNTERS_SUMMABLE; t_ix++)
+	    {
+	      if (!gi_ptr->merge[t_ix])
+		continue;
+
+	      cs_ptr = &this_prg.ctrs[t_ix];
+	      cs_ptr->num += ci_ptr->num;
+	      crc32 = crc32_unsigned (crc32, ci_ptr->num);
+
+	      for (c_num = 0; c_num < ci_ptr->num; c_num++)
+		{
+		  cs_ptr->sum_all += ci_ptr->values[c_num];
+		  if (cs_ptr->run_max < ci_ptr->values[c_num])
+		    cs_ptr->run_max = ci_ptr->values[c_num];
+		}
+	      ci_ptr++;
+	    }
+	}
+    }
+
+#ifndef __COREBOOT__
+  {
+    /* Check if the level of dirs to strip off specified. */
+    char *tmp = getenv("GCOV_PREFIX_STRIP");
+    if (tmp)
+      {
+	gcov_prefix_strip = atoi (tmp);
+	/* Do not consider negative values. */
+	if (gcov_prefix_strip < 0)
+	  gcov_prefix_strip = 0;
+      }
+  }
+
+  /* Get file name relocation prefix.  Non-absolute values are ignored. */
+  gcov_prefix = getenv("GCOV_PREFIX");
+  if (gcov_prefix)
+    {
+      prefix_length = strlen(gcov_prefix);
+
+      /* Remove an unnecessary trailing '/' */
+      if (IS_DIR_SEPARATOR (gcov_prefix[prefix_length - 1]))
+	prefix_length--;
+    }
+  else
+#endif
+    prefix_length = 0;
+
+  /* If no prefix was specified and a prefix stip, then we assume
+     relative.  */
+  if (gcov_prefix_strip != 0 && prefix_length == 0)
+    {
+      gcov_prefix = ".";
+      prefix_length = 1;
+    }
+  /* Allocate and initialize the filename scratch space plus one.  */
+  gi_filename = (char *) alloca (prefix_length + gcov_max_filename + 2);
+  if (prefix_length)
+    memcpy (gi_filename, gcov_prefix, prefix_length);
+  gi_filename_up = gi_filename + prefix_length;
+
+  /* Now merge each file.  */
+  for (gi_ptr = gcov_list; gi_ptr; gi_ptr = gi_ptr->next)
+    {
+      unsigned n_counts;
+      struct gcov_summary prg; /* summary for this object over all
+				  program.  */
+      struct gcov_ctr_summary *cs_prg, *cs_tprg, *cs_all;
+      int error = 0;
+      gcov_unsigned_t tag, length;
+      gcov_position_t summary_pos = 0;
+      gcov_position_t eof_pos = 0;
+      const char *fname, *s;
+      struct gcov_fn_buffer *fn_buffer = 0;
+      struct gcov_fn_buffer **fn_tail = &fn_buffer;
+
+      fname = gi_ptr->filename;
+
+      /* Avoid to add multiple drive letters into combined path.  */
+      if (prefix_length != 0 && HAS_DRIVE_SPEC(fname))
+        fname += 2;
+
+      /* Build relocated filename, stripping off leading
+         directories from the initial filename if requested. */
+      if (gcov_prefix_strip > 0)
+        {
+          int level = 0;
+          s = fname;
+          if (IS_DIR_SEPARATOR(*s))
+            ++s;
+
+          /* Skip selected directory levels. */
+	  for (; (*s != '\0') && (level < gcov_prefix_strip); s++)
+	    if (IS_DIR_SEPARATOR(*s))
+	      {
+		fname = s;
+		level++;
+	      }
+        }
+
+      /* Update complete filename with stripped original. */
+      if (prefix_length != 0 && !IS_DIR_SEPARATOR (*fname))
+        {
+          /* If prefix is given, add directory separator.  */
+	  strcpy (gi_filename_up, "/");
+	  strcpy (gi_filename_up + 1, fname);
+	}
+      else
+        strcpy (gi_filename_up, fname);
+
+      if (!gcov_open (gi_filename))
+	{
+	  /* Open failed likely due to missed directory.
+	     Create directory and retry to open file. */
+          if (create_file_directory (gi_filename))
+	    {
+	      fprintf (stderr, "profiling:%s:Skip\n", gi_filename);
+	      continue;
+	    }
+	  if (!gcov_open (gi_filename))
+	    {
+              fprintf (stderr, "profiling:%s:Cannot open\n", gi_filename);
+	      continue;
+	    }
+	}
+
+      tag = gcov_read_unsigned ();
+      if (tag)
+	{
+	  /* Merge data from file.  */
+	  if (tag != GCOV_DATA_MAGIC)
+	    {
+	      fprintf (stderr, "profiling:%s:Not a gcov data file\n",
+		       gi_filename);
+	      goto read_fatal;
+	    }
+	  length = gcov_read_unsigned ();
+	  if (!gcov_version (gi_ptr, length, gi_filename))
+	    goto read_fatal;
+
+	  length = gcov_read_unsigned ();
+	  if (length != gi_ptr->stamp)
+	    /* Read from a different compilation. Overwrite the file.  */
+	    goto rewrite;
+
+	  /* Look for program summary.  */
+	  for (f_ix = 0;;)
+	    {
+	      struct gcov_summary tmp;
+
+	      eof_pos = gcov_position ();
+	      tag = gcov_read_unsigned ();
+	      if (tag != GCOV_TAG_PROGRAM_SUMMARY)
+		break;
+
+	      f_ix--;
+	      length = gcov_read_unsigned ();
+	      if (length != GCOV_TAG_SUMMARY_LENGTH)
+		goto read_mismatch;
+	      gcov_read_summary (&tmp);
+	      if ((error = gcov_is_error ()))
+		goto read_error;
+	      if (summary_pos || tmp.checksum != crc32)
+		goto next_summary;
+
+	      for (t_ix = 0; t_ix != GCOV_COUNTERS_SUMMABLE; t_ix++)
+		if (tmp.ctrs[t_ix].num != this_prg.ctrs[t_ix].num)
+		  goto next_summary;
+	      prg = tmp;
+	      summary_pos = eof_pos;
+
+	    next_summary:;
+	    }
+
+	  /* Merge execution counts for each function.  */
+	  for (f_ix = 0; (unsigned)f_ix != gi_ptr->n_functions;
+	       f_ix++, tag = gcov_read_unsigned ())
+	    {
+	      gfi_ptr = gi_ptr->functions[f_ix];
+
+	      if (tag != GCOV_TAG_FUNCTION)
+		goto read_mismatch;
+
+	      length = gcov_read_unsigned ();
+	      if (!length)
+		/* This function did not appear in the other program.
+		   We have nothing to merge.  */
+		continue;
+
+	      if (length != GCOV_TAG_FUNCTION_LENGTH)
+		goto read_mismatch;
+
+	      if (!gfi_ptr || gfi_ptr->key != gi_ptr)
+		{
+		  /* This function appears in the other program.  We
+		     need to buffer the information in order to write
+		     it back out -- we'll be inserting data before
+		     this point, so cannot simply keep the data in the
+		     file.  */
+		  fn_tail = buffer_fn_data (gi_filename,
+					    gi_ptr, fn_tail, f_ix);
+		  if (!fn_tail)
+		    goto read_mismatch;
+		  continue;
+		}
+
+	      length = gcov_read_unsigned ();
+	      if (length != gfi_ptr->ident)
+		goto read_mismatch;
+
+	      length = gcov_read_unsigned ();
+	      if (length != gfi_ptr->lineno_checksum)
+		goto read_mismatch;
+
+	      length = gcov_read_unsigned ();
+	      if (length != gfi_ptr->cfg_checksum)
+		goto read_mismatch;
+
+	      ci_ptr = gfi_ptr->ctrs;
+	      for (t_ix = 0; t_ix < GCOV_COUNTERS; t_ix++)
+		{
+		  gcov_merge_fn merge = gi_ptr->merge[t_ix];
+
+		  if (!merge)
+		    continue;
+
+		  tag = gcov_read_unsigned ();
+		  length = gcov_read_unsigned ();
+		  if (tag != GCOV_TAG_FOR_COUNTER (t_ix)
+		      || length != GCOV_TAG_COUNTER_LENGTH (ci_ptr->num))
+		    goto read_mismatch;
+		  (*merge) (ci_ptr->values, ci_ptr->num);
+		  ci_ptr++;
+		}
+	      if ((error = gcov_is_error ()))
+		goto read_error;
+	    }
+
+	  if (tag)
+	    {
+	    read_mismatch:;
+	      fprintf (stderr, "profiling:%s:Merge mismatch for %s %u\n",
+		       gi_filename, f_ix >= 0 ? "function" : "summary",
+		       f_ix < 0 ? -1 - f_ix : f_ix);
+	      goto read_fatal;
+	    }
+	}
+      goto rewrite;
+
+    read_error:;
+      fprintf (stderr, "profiling:%s:%s merging\n", gi_filename,
+	       error < 0 ? "Overflow": "Error");
+
+      goto read_fatal;
+
+    rewrite:;
+      gcov_rewrite ();
+      if (!summary_pos)
+	{
+	  memset (&prg, 0, sizeof (prg));
+	  summary_pos = eof_pos;
+	}
+
+      /* Merge the summaries.  */
+      for (t_ix = 0; t_ix < GCOV_COUNTERS_SUMMABLE; t_ix++)
+	{
+	  cs_prg = &prg.ctrs[t_ix];
+	  cs_tprg = &this_prg.ctrs[t_ix];
+	  cs_all = &all_prg.ctrs[t_ix];
+
+	  if (gi_ptr->merge[t_ix])
+	    {
+	      if (!cs_prg->runs++)
+		cs_prg->num = cs_tprg->num;
+	      cs_prg->sum_all += cs_tprg->sum_all;
+	      if (cs_prg->run_max < cs_tprg->run_max)
+		cs_prg->run_max = cs_tprg->run_max;
+	      cs_prg->sum_max += cs_tprg->run_max;
+	    }
+	  else if (cs_prg->runs)
+	    goto read_mismatch;
+
+	  if (!cs_all->runs && cs_prg->runs)
+	    memcpy (cs_all, cs_prg, sizeof (*cs_all));
+	  else if (!all_prg.checksum
+		   && (!GCOV_LOCKED || cs_all->runs == cs_prg->runs)
+		   && memcmp (cs_all, cs_prg, sizeof (*cs_all)))
+	    {
+	      fprintf (stderr, "profiling:%s:Invocation mismatch - some data files may have been removed%s\n",
+		       gi_filename, GCOV_LOCKED
+		       ? "" : " or concurrently updated without locking support");
+	      all_prg.checksum = ~0u;
+	    }
+	}
+
+      prg.checksum = crc32;
+
+      /* Write out the data.  */
+      if (!eof_pos)
+	{
+	  gcov_write_tag_length (GCOV_DATA_MAGIC, GCOV_VERSION);
+	  gcov_write_unsigned (gi_ptr->stamp);
+	}
+
+      if (summary_pos)
+	gcov_seek (summary_pos);
+
+      /* Generate whole program statistics.  */
+      gcov_write_summary (GCOV_TAG_PROGRAM_SUMMARY, &prg);
+
+      if (summary_pos < eof_pos)
+	gcov_seek (eof_pos);
+
+      /* Write execution counts for each function.  */
+      for (f_ix = 0; (unsigned)f_ix != gi_ptr->n_functions; f_ix++)
+	{
+	  unsigned buffered = 0;
+
+	  if (fn_buffer && fn_buffer->fn_ix == (unsigned)f_ix)
+	    {
+	      /* Buffered data from another program.  */
+	      buffered = 1;
+	      gfi_ptr = &fn_buffer->info;
+	      length = GCOV_TAG_FUNCTION_LENGTH;
+	    }
+	  else
+	    {
+	      gfi_ptr = gi_ptr->functions[f_ix];
+	      if (gfi_ptr && gfi_ptr->key == gi_ptr)
+		length = GCOV_TAG_FUNCTION_LENGTH;
+	      else
+		length = 0;
+	    }
+
+	  gcov_write_tag_length (GCOV_TAG_FUNCTION, length);
+	  if (!length)
+	    continue;
+
+	  gcov_write_unsigned (gfi_ptr->ident);
+	  gcov_write_unsigned (gfi_ptr->lineno_checksum);
+	  gcov_write_unsigned (gfi_ptr->cfg_checksum);
+
+	  ci_ptr = gfi_ptr->ctrs;
+	  for (t_ix = 0; t_ix < GCOV_COUNTERS; t_ix++)
+	    {
+	      if (!gi_ptr->merge[t_ix])
+		continue;
+
+	      n_counts = ci_ptr->num;
+	      gcov_write_tag_length (GCOV_TAG_FOR_COUNTER (t_ix),
+				     GCOV_TAG_COUNTER_LENGTH (n_counts));
+	      gcov_type *c_ptr = ci_ptr->values;
+	      while (n_counts--)
+		gcov_write_counter (*c_ptr++);
+	      ci_ptr++;
+	    }
+	  if (buffered)
+	    fn_buffer = free_fn_data (gi_ptr, fn_buffer, GCOV_COUNTERS);
+	}
+
+      gcov_write_unsigned (0);
+
+    read_fatal:;
+      while (fn_buffer)
+	fn_buffer = free_fn_data (gi_ptr, fn_buffer, GCOV_COUNTERS);
+
+      if ((error = gcov_close ()))
+	  fprintf (stderr, error  < 0 ?
+		   "profiling:%s:Overflow writing\n" :
+		   "profiling:%s:Error writing\n",
+		   gi_filename);
+    }
+}
+
+/* Add a new object file onto the bb chain.  Invoked automatically
+   when running an object file's global ctors.  */
+
+void
+__gcov_init (struct gcov_info *info)
+{
+  if (!info->version || !info->n_functions)
+    return;
+  if (gcov_version (info, info->version, 0))
+    {
+      size_t filename_length = strlen(info->filename);
+
+      /* Refresh the longest file name information */
+      if (filename_length > gcov_max_filename)
+        gcov_max_filename = filename_length;
+
+#ifndef __COREBOOT__
+      if (!gcov_list)
+	atexit (gcov_exit);
+#endif
+
+      info->next = gcov_list;
+      gcov_list = info;
+    }
+  info->version = 0;
+}
+
+/* Called before fork or exec - write out profile information gathered so
+   far and reset it to zero.  This avoids duplication or loss of the
+   profile information gathered so far.  */
+
+void
+__gcov_flush (void)
+{
+  const struct gcov_info *gi_ptr;
+
+  gcov_exit ();
+  for (gi_ptr = gcov_list; gi_ptr; gi_ptr = gi_ptr->next)
+    {
+      unsigned f_ix;
+
+      for (f_ix = 0; f_ix < gi_ptr->n_functions; f_ix++)
+	{
+	  unsigned t_ix;
+	  const struct gcov_fn_info *gfi_ptr = gi_ptr->functions[f_ix];
+
+	  if (!gfi_ptr || gfi_ptr->key != gi_ptr)
+	    continue;
+	  const struct gcov_ctr_info *ci_ptr = gfi_ptr->ctrs;
+	  for (t_ix = 0; t_ix != GCOV_COUNTERS; t_ix++)
+	    {
+	      if (!gi_ptr->merge[t_ix])
+		continue;
+
+	      memset (ci_ptr->values, 0, sizeof (gcov_type) * ci_ptr->num);
+	      ci_ptr++;
+	    }
+	}
+    }
+}
+
+#endif /* L_gcov */
+
+#ifdef L_gcov_merge_add
+/* The profile merging function that just adds the counters.  It is given
+   an array COUNTERS of N_COUNTERS old counters and it reads the same number
+   of counters from the gcov file.  */
+void
+__gcov_merge_add (gcov_type *counters, unsigned n_counters)
+{
+  for (; n_counters; counters++, n_counters--)
+    *counters += gcov_read_counter ();
+}
+#endif /* L_gcov_merge_add */
+
+#ifdef L_gcov_merge_ior
+/* The profile merging function that just adds the counters.  It is given
+   an array COUNTERS of N_COUNTERS old counters and it reads the same number
+   of counters from the gcov file.  */
+void
+__gcov_merge_ior (gcov_type *counters, unsigned n_counters)
+{
+  for (; n_counters; counters++, n_counters--)
+    *counters |= gcov_read_counter ();
+}
+#endif
+
+#ifdef L_gcov_merge_single
+/* The profile merging function for choosing the most common value.
+   It is given an array COUNTERS of N_COUNTERS old counters and it
+   reads the same number of counters from the gcov file.  The counters
+   are split into 3-tuples where the members of the tuple have
+   meanings:
+  
+   -- the stored candidate on the most common value of the measured entity
+   -- counter
+   -- total number of evaluations of the value  */
+void
+__gcov_merge_single (gcov_type *counters, unsigned n_counters)
+{
+  unsigned i, n_measures;
+  gcov_type value, counter, all;
+
+  gcc_assert (!(n_counters % 3));
+  n_measures = n_counters / 3;
+  for (i = 0; i < n_measures; i++, counters += 3)
+    {
+      value = gcov_read_counter ();
+      counter = gcov_read_counter ();
+      all = gcov_read_counter ();
+
+      if (counters[0] == value)
+	counters[1] += counter;
+      else if (counter > counters[1])
+	{
+	  counters[0] = value;
+	  counters[1] = counter - counters[1];
+	}
+      else
+	counters[1] -= counter;
+      counters[2] += all;
+    }
+}
+#endif /* L_gcov_merge_single */
+
+#ifdef L_gcov_merge_delta
+/* The profile merging function for choosing the most common
+   difference between two consecutive evaluations of the value.  It is
+   given an array COUNTERS of N_COUNTERS old counters and it reads the
+   same number of counters from the gcov file.  The counters are split
+   into 4-tuples where the members of the tuple have meanings:
+
+   -- the last value of the measured entity
+   -- the stored candidate on the most common difference
+   -- counter
+   -- total number of evaluations of the value  */
+void
+__gcov_merge_delta (gcov_type *counters, unsigned n_counters)
+{
+  unsigned i, n_measures;
+  gcov_type value, counter, all;
+
+  gcc_assert (!(n_counters % 4));
+  n_measures = n_counters / 4;
+  for (i = 0; i < n_measures; i++, counters += 4)
+    {
+      /* last = */ gcov_read_counter ();
+      value = gcov_read_counter ();
+      counter = gcov_read_counter ();
+      all = gcov_read_counter ();
+
+      if (counters[1] == value)
+	counters[2] += counter;
+      else if (counter > counters[2])
+	{
+	  counters[1] = value;
+	  counters[2] = counter - counters[2];
+	}
+      else
+	counters[2] -= counter;
+      counters[3] += all;
+    }
+}
+#endif /* L_gcov_merge_delta */
+
+#ifdef L_gcov_interval_profiler
+/* If VALUE is in interval <START, START + STEPS - 1>, then increases the
+   corresponding counter in COUNTERS.  If the VALUE is above or below
+   the interval, COUNTERS[STEPS] or COUNTERS[STEPS + 1] is increased
+   instead.  */
+
+void
+__gcov_interval_profiler (gcov_type *counters, gcov_type value,
+			  int start, unsigned steps)
+{
+  gcov_type delta = value - start;
+  if (delta < 0)
+    counters[steps + 1]++;
+  else if (delta >= steps)
+    counters[steps]++;
+  else
+    counters[delta]++;
+}
+#endif
+
+#ifdef L_gcov_pow2_profiler
+/* If VALUE is a power of two, COUNTERS[1] is incremented.  Otherwise
+   COUNTERS[0] is incremented.  */
+
+void
+__gcov_pow2_profiler (gcov_type *counters, gcov_type value)
+{
+  if (value & (value - 1))
+    counters[0]++;
+  else
+    counters[1]++;
+}
+#endif
+
+/* Tries to determine the most common value among its inputs.  Checks if the
+   value stored in COUNTERS[0] matches VALUE.  If this is the case, COUNTERS[1]
+   is incremented.  If this is not the case and COUNTERS[1] is not zero,
+   COUNTERS[1] is decremented.  Otherwise COUNTERS[1] is set to one and
+   VALUE is stored to COUNTERS[0].  This algorithm guarantees that if this
+   function is called more than 50% of the time with one value, this value
+   will be in COUNTERS[0] in the end.
+
+   In any case, COUNTERS[2] is incremented.  */
+
+static inline void
+__gcov_one_value_profiler_body (gcov_type *counters, gcov_type value)
+{
+  if (value == counters[0])
+    counters[1]++;
+  else if (counters[1] == 0)
+    {
+      counters[1] = 1;
+      counters[0] = value;
+    }
+  else
+    counters[1]--;
+  counters[2]++;
+}
+
+#ifdef L_gcov_one_value_profiler
+void
+__gcov_one_value_profiler (gcov_type *counters, gcov_type value)
+{
+  __gcov_one_value_profiler_body (counters, value);
+}
+#endif
+
+#ifdef L_gcov_indirect_call_profiler
+
+/* By default, the C++ compiler will use function addresses in the
+   vtable entries.  Setting TARGET_VTABLE_USES_DESCRIPTORS to nonzero
+   tells the compiler to use function descriptors instead.  The value
+   of this macro says how many words wide the descriptor is (normally 2),
+   but it may be dependent on target flags.  Since we do not have access
+   to the target flags here we just check to see if it is set and use
+   that to set VTABLE_USES_DESCRIPTORS to 0 or 1.
+
+   It is assumed that the address of a function descriptor may be treated
+   as a pointer to a function.  */
+
+#ifdef TARGET_VTABLE_USES_DESCRIPTORS
+#define VTABLE_USES_DESCRIPTORS 1
+#else
+#define VTABLE_USES_DESCRIPTORS 0
+#endif
+
+/* Tries to determine the most common value among its inputs. */
+void
+__gcov_indirect_call_profiler (gcov_type* counter, gcov_type value,
+			       void* cur_func, void* callee_func)
+{
+  /* If the C++ virtual tables contain function descriptors then one
+     function may have multiple descriptors and we need to dereference
+     the descriptors to see if they point to the same function.  */
+  if (cur_func == callee_func
+      || (VTABLE_USES_DESCRIPTORS && callee_func
+	  && *(void **) cur_func == *(void **) callee_func))
+    __gcov_one_value_profiler_body (counter, value);
+}
+#endif
+
+
+#ifdef L_gcov_average_profiler
+/* Increase corresponding COUNTER by VALUE.  FIXME: Perhaps we want
+   to saturate up.  */
+
+void
+__gcov_average_profiler (gcov_type *counters, gcov_type value)
+{
+  counters[0] += value;
+  counters[1] ++;
+}
+#endif
+
+#ifdef L_gcov_ior_profiler
+/* Increase corresponding COUNTER by VALUE.  FIXME: Perhaps we want
+   to saturate up.  */
+
+void
+__gcov_ior_profiler (gcov_type *counters, gcov_type value)
+{
+  *counters |= value;
+}
+#endif
+
+#ifdef L_gcov_fork
+/* A wrapper for the fork function.  Flushes the accumulated profiling data, so
+   that they are not counted twice.  */
+
+pid_t
+__gcov_fork (void)
+{
+  __gcov_flush ();
+  return fork ();
+}
+#endif
+
+#ifdef L_gcov_execl
+/* A wrapper for the execl function.  Flushes the accumulated profiling data, so
+   that they are not lost.  */
+
+int
+__gcov_execl (const char *path, char *arg, ...)
+{
+  va_list ap, aq;
+  unsigned i, length;
+  char **args;
+
+  __gcov_flush ();
+
+  va_start (ap, arg);
+  va_copy (aq, ap);
+
+  length = 2;
+  while (va_arg (ap, char *))
+    length++;
+  va_end (ap);
+
+  args = (char **) alloca (length * sizeof (void *));
+  args[0] = arg;
+  for (i = 1; i < length; i++)
+    args[i] = va_arg (aq, char *);
+  va_end (aq);
+
+  return execv (path, args);
+}
+#endif
+
+#ifdef L_gcov_execlp
+/* A wrapper for the execlp function.  Flushes the accumulated profiling data, so
+   that they are not lost.  */
+
+int
+__gcov_execlp (const char *path, char *arg, ...)
+{
+  va_list ap, aq;
+  unsigned i, length;
+  char **args;
+
+  __gcov_flush ();
+
+  va_start (ap, arg);
+  va_copy (aq, ap);
+
+  length = 2;
+  while (va_arg (ap, char *))
+    length++;
+  va_end (ap);
+
+  args = (char **) alloca (length * sizeof (void *));
+  args[0] = arg;
+  for (i = 1; i < length; i++)
+    args[i] = va_arg (aq, char *);
+  va_end (aq);
+
+  return execvp (path, args);
+}
+#endif
+
+#ifdef L_gcov_execle
+/* A wrapper for the execle function.  Flushes the accumulated profiling data, so
+   that they are not lost.  */
+
+int
+__gcov_execle (const char *path, char *arg, ...)
+{
+  va_list ap, aq;
+  unsigned i, length;
+  char **args;
+  char **envp;
+
+  __gcov_flush ();
+
+  va_start (ap, arg);
+  va_copy (aq, ap);
+
+  length = 2;
+  while (va_arg (ap, char *))
+    length++;
+  va_end (ap);
+
+  args = (char **) alloca (length * sizeof (void *));
+  args[0] = arg;
+  for (i = 1; i < length; i++)
+    args[i] = va_arg (aq, char *);
+  envp = va_arg (aq, char **);
+  va_end (aq);
+
+  return execve (path, args, envp);
+}
+#endif
+
+#ifdef L_gcov_execv
+/* A wrapper for the execv function.  Flushes the accumulated profiling data, so
+   that they are not lost.  */
+
+int
+__gcov_execv (const char *path, char *const argv[])
+{
+  __gcov_flush ();
+  return execv (path, argv);
+}
+#endif
+
+#ifdef L_gcov_execvp
+/* A wrapper for the execvp function.  Flushes the accumulated profiling data, so
+   that they are not lost.  */
+
+int
+__gcov_execvp (const char *path, char *const argv[])
+{
+  __gcov_flush ();
+  return execvp (path, argv);
+}
+#endif
+
+#ifdef L_gcov_execve
+/* A wrapper for the execve function.  Flushes the accumulated profiling data, so
+   that they are not lost.  */
+
+int
+__gcov_execve (const char *path, char *const argv[], char *const envp[])
+{
+  __gcov_flush ();
+  return execve (path, argv, envp);
+}
+#endif
+#endif /* inhibit_libc */