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, 552 insertions, 0 deletions

diff --git a/src/lib/gcov-io.c b/src/lib/gcov-io.c
new file mode 100644
index 0000000000..37c1c3e350
--- /dev/null
+++ b/src/lib/gcov-io.c
@@ -0,0 +1,552 @@
+/* File format for coverage information
+   Copyright (C) 1996, 1997, 1998, 2000, 2002, 2003, 2004, 2005, 2007,
+   2008  Free Software Foundation, Inc.
+   Contributed by Bob Manson <manson@cygnus.com>.
+   Completely remangled by Nathan Sidwell <nathan@codesourcery.com>.
+
+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/>.  */
+
+/* Routines declared in gcov-io.h.  This file should be #included by
+   another source file, after having #included gcov-io.h.  */
+
+#if !IN_GCOV
+static void gcov_write_block (unsigned);
+static gcov_unsigned_t *gcov_write_words (unsigned);
+#endif
+static const gcov_unsigned_t *gcov_read_words (unsigned);
+#if !IN_LIBGCOV
+static void gcov_allocate (unsigned);
+#endif
+
+static inline gcov_unsigned_t from_file (gcov_unsigned_t value)
+{
+#if !IN_LIBGCOV
+  if (gcov_var.endian)
+    {
+      value = (value >> 16) | (value << 16);
+      value = ((value & 0xff00ff) << 8) | ((value >> 8) & 0xff00ff);
+    }
+#endif
+  return value;
+}
+
+/* Open a gcov file. NAME is the name of the file to open and MODE
+   indicates whether a new file should be created, or an existing file
+   opened. If MODE is >= 0 an existing file will be opened, if
+   possible, and if MODE is <= 0, a new file will be created. Use
+   MODE=0 to attempt to reopen an existing file and then fall back on
+   creating a new one.  If MODE < 0, the file will be opened in
+   read-only mode.  Otherwise it will be opened for modification.
+   Return zero on failure, >0 on opening an existing file and <0 on
+   creating a new one.  */
+
+GCOV_LINKAGE int
+#if IN_LIBGCOV
+gcov_open (const char *name)
+#else
+gcov_open (const char *name, int mode)
+#endif
+{
+#if IN_LIBGCOV
+  const int mode = 0;
+#endif
+#if GCOV_LOCKED
+  struct flock s_flock;
+  int fd;
+
+  s_flock.l_whence = SEEK_SET;
+  s_flock.l_start = 0;
+  s_flock.l_len = 0; /* Until EOF.  */
+  s_flock.l_pid = getpid ();
+#endif
+
+  gcc_assert (!gcov_var.file);
+  gcov_var.start = 0;
+  gcov_var.offset = gcov_var.length = 0;
+  gcov_var.overread = -1u;
+  gcov_var.error = 0;
+#if !IN_LIBGCOV
+  gcov_var.endian = 0;
+#endif
+#if GCOV_LOCKED
+  if (mode > 0)
+    {
+      /* Read-only mode - acquire a read-lock.  */
+      s_flock.l_type = F_RDLCK;
+      fd = open (name, O_RDONLY);
+    }
+  else
+    {
+      /* Write mode - acquire a write-lock.  */
+      s_flock.l_type = F_WRLCK;
+      fd = open (name, O_RDWR | O_CREAT, 0666);
+    }
+  if (fd < 0)
+    return 0;
+
+  while (fcntl (fd, F_SETLKW, &s_flock) && errno == EINTR)
+    continue;
+
+  gcov_var.file = fdopen (fd, (mode > 0) ? "rb" : "r+b");
+
+  if (!gcov_var.file)
+    {
+      close (fd);
+      return 0;
+    }
+
+  if (mode > 0)
+    gcov_var.mode = 1;
+  else if (mode == 0)
+    {
+      struct stat st;
+
+      if (fstat (fd, &st) < 0)
+	{
+	  fclose (gcov_var.file);
+	  gcov_var.file = 0;
+	  return 0;
+	}
+      if (st.st_size != 0)
+	gcov_var.mode = 1;
+      else
+	gcov_var.mode = mode * 2 + 1;
+    }
+  else
+    gcov_var.mode = mode * 2 + 1;
+#else
+  if (mode >= 0)
+    gcov_var.file = fopen (name, (mode > 0) ? "rb" : "r+b");
+
+  if (gcov_var.file)
+    gcov_var.mode = 1;
+  else if (mode <= 0)
+    {
+      gcov_var.file = fopen (name, "w+b");
+      if (gcov_var.file)
+	gcov_var.mode = mode * 2 + 1;
+    }
+  if (!gcov_var.file)
+    return 0;
+#endif
+
+  setbuf (gcov_var.file, (char *)0);
+
+  return 1;
+}
+
+/* Close the current gcov file. Flushes data to disk. Returns nonzero
+   on failure or error flag set.  */
+
+GCOV_LINKAGE int
+gcov_close (void)
+{
+  if (gcov_var.file)
+    {
+#if !IN_GCOV
+      if (gcov_var.offset && gcov_var.mode < 0)
+	gcov_write_block (gcov_var.offset);
+#endif
+      fclose (gcov_var.file);
+      gcov_var.file = 0;
+      gcov_var.length = 0;
+    }
+#if !IN_LIBGCOV
+  free (gcov_var.buffer);
+  gcov_var.alloc = 0;
+  gcov_var.buffer = 0;
+#endif
+  gcov_var.mode = 0;
+  return gcov_var.error;
+}
+
+#if !IN_LIBGCOV
+/* Check if MAGIC is EXPECTED. Use it to determine endianness of the
+   file. Returns +1 for same endian, -1 for other endian and zero for
+   not EXPECTED.  */
+
+GCOV_LINKAGE int
+gcov_magic (gcov_unsigned_t magic, gcov_unsigned_t expected)
+{
+  if (magic == expected)
+    return 1;
+  magic = (magic >> 16) | (magic << 16);
+  magic = ((magic & 0xff00ff) << 8) | ((magic >> 8) & 0xff00ff);
+  if (magic == expected)
+    {
+      gcov_var.endian = 1;
+      return -1;
+    }
+  return 0;
+}
+#endif
+
+#if !IN_LIBGCOV
+static void
+gcov_allocate (unsigned length)
+{
+  size_t new_size = gcov_var.alloc;
+
+  if (!new_size)
+    new_size = GCOV_BLOCK_SIZE;
+  new_size += length;
+  new_size *= 2;
+
+  gcov_var.alloc = new_size;
+  gcov_var.buffer = XRESIZEVAR (gcov_unsigned_t, gcov_var.buffer, new_size << 2);
+}
+#endif
+
+#if !IN_GCOV
+/* Write out the current block, if needs be.  */
+
+static void
+gcov_write_block (unsigned size)
+{
+  if (fwrite (gcov_var.buffer, size << 2, 1, gcov_var.file) != 1)
+    gcov_var.error = 1;
+  gcov_var.start += size;
+  gcov_var.offset -= size;
+}
+
+/* Allocate space to write BYTES bytes to the gcov file. Return a
+   pointer to those bytes, or NULL on failure.  */
+
+static gcov_unsigned_t *
+gcov_write_words (unsigned words)
+{
+  gcov_unsigned_t *result;
+
+  gcc_assert (gcov_var.mode < 0);
+#if IN_LIBGCOV
+  if (gcov_var.offset >= GCOV_BLOCK_SIZE)
+    {
+      gcov_write_block (GCOV_BLOCK_SIZE);
+      if (gcov_var.offset)
+	{
+	  gcc_assert (gcov_var.offset == 1);
+	  memcpy (gcov_var.buffer, gcov_var.buffer + GCOV_BLOCK_SIZE, 4);
+	}
+    }
+#else
+  if (gcov_var.offset + words > gcov_var.alloc)
+    gcov_allocate (gcov_var.offset + words);
+#endif
+  result = &gcov_var.buffer[gcov_var.offset];
+  gcov_var.offset += words;
+
+  return result;
+}
+
+/* Write unsigned VALUE to coverage file.  Sets error flag
+   appropriately.  */
+
+GCOV_LINKAGE void
+gcov_write_unsigned (gcov_unsigned_t value)
+{
+  gcov_unsigned_t *buffer = gcov_write_words (1);
+
+  buffer[0] = value;
+}
+
+/* Write counter VALUE to coverage file.  Sets error flag
+   appropriately.  */
+
+#if IN_LIBGCOV
+GCOV_LINKAGE void
+gcov_write_counter (gcov_type value)
+{
+  gcov_unsigned_t *buffer = gcov_write_words (2);
+
+  buffer[0] = (gcov_unsigned_t) value;
+  if (sizeof (value) > sizeof (gcov_unsigned_t))
+    buffer[1] = (gcov_unsigned_t) (value >> 32);
+  else
+    buffer[1] = 0;
+}
+#endif /* IN_LIBGCOV */
+
+#if !IN_LIBGCOV
+/* Write STRING to coverage file.  Sets error flag on file
+   error, overflow flag on overflow */
+
+GCOV_LINKAGE void
+gcov_write_string (const char *string)
+{
+  unsigned length = 0;
+  unsigned alloc = 0;
+  gcov_unsigned_t *buffer;
+
+  if (string)
+    {
+      length = strlen (string);
+      alloc = (length + 4) >> 2;
+    }
+
+  buffer = gcov_write_words (1 + alloc);
+
+  buffer[0] = alloc;
+  buffer[alloc] = 0;
+  memcpy (&buffer[1], string, length);
+}
+#endif
+
+#if !IN_LIBGCOV
+/* Write a tag TAG and reserve space for the record length. Return a
+   value to be used for gcov_write_length.  */
+
+GCOV_LINKAGE gcov_position_t
+gcov_write_tag (gcov_unsigned_t tag)
+{
+  gcov_position_t result = gcov_var.start + gcov_var.offset;
+  gcov_unsigned_t *buffer = gcov_write_words (2);
+
+  buffer[0] = tag;
+  buffer[1] = 0;
+
+  return result;
+}
+
+/* Write a record length using POSITION, which was returned by
+   gcov_write_tag.  The current file position is the end of the
+   record, and is restored before returning.  Returns nonzero on
+   overflow.  */
+
+GCOV_LINKAGE void
+gcov_write_length (gcov_position_t position)
+{
+  unsigned offset;
+  gcov_unsigned_t length;
+  gcov_unsigned_t *buffer;
+
+  gcc_assert (gcov_var.mode < 0);
+  gcc_assert (position + 2 <= gcov_var.start + gcov_var.offset);
+  gcc_assert (position >= gcov_var.start);
+  offset = position - gcov_var.start;
+  length = gcov_var.offset - offset - 2;
+  buffer = (gcov_unsigned_t *) &gcov_var.buffer[offset];
+  buffer[1] = length;
+  if (gcov_var.offset >= GCOV_BLOCK_SIZE)
+    gcov_write_block (gcov_var.offset);
+}
+
+#else /* IN_LIBGCOV */
+
+/* Write a tag TAG and length LENGTH.  */
+
+GCOV_LINKAGE void
+gcov_write_tag_length (gcov_unsigned_t tag, gcov_unsigned_t length)
+{
+  gcov_unsigned_t *buffer = gcov_write_words (2);
+
+  buffer[0] = tag;
+  buffer[1] = length;
+}
+
+/* Write a summary structure to the gcov file.  Return nonzero on
+   overflow.  */
+
+GCOV_LINKAGE void
+gcov_write_summary (gcov_unsigned_t tag, const struct gcov_summary *summary)
+{
+  unsigned ix;
+  const struct gcov_ctr_summary *csum;
+
+  gcov_write_tag_length (tag, GCOV_TAG_SUMMARY_LENGTH);
+  gcov_write_unsigned (summary->checksum);
+  for (csum = summary->ctrs, ix = GCOV_COUNTERS_SUMMABLE; ix--; csum++)
+    {
+      gcov_write_unsigned (csum->num);
+      gcov_write_unsigned (csum->runs);
+      gcov_write_counter (csum->sum_all);
+      gcov_write_counter (csum->run_max);
+      gcov_write_counter (csum->sum_max);
+    }
+}
+#endif /* IN_LIBGCOV */
+
+#endif /*!IN_GCOV */
+
+/* Return a pointer to read BYTES bytes from the gcov file. Returns
+   NULL on failure (read past EOF).  */
+
+static const gcov_unsigned_t *
+gcov_read_words (unsigned words)
+{
+  const gcov_unsigned_t *result;
+  unsigned excess = gcov_var.length - gcov_var.offset;
+
+  gcc_assert (gcov_var.mode > 0);
+  if (excess < words)
+    {
+      gcov_var.start += gcov_var.offset;
+#if IN_LIBGCOV
+      if (excess)
+	{
+	  gcc_assert (excess == 1);
+	  memcpy (gcov_var.buffer, gcov_var.buffer + gcov_var.offset, 4);
+	}
+#else
+      memmove (gcov_var.buffer, gcov_var.buffer + gcov_var.offset, excess * 4);
+#endif
+      gcov_var.offset = 0;
+      gcov_var.length = excess;
+#if IN_LIBGCOV
+      gcc_assert (!gcov_var.length || gcov_var.length == 1);
+      excess = GCOV_BLOCK_SIZE;
+#else
+      if (gcov_var.length + words > gcov_var.alloc)
+	gcov_allocate (gcov_var.length + words);
+      excess = gcov_var.alloc - gcov_var.length;
+#endif
+      excess = fread (gcov_var.buffer + gcov_var.length,
+		      1, excess << 2, gcov_var.file) >> 2;
+      gcov_var.length += excess;
+      if (gcov_var.length < words)
+	{
+	  gcov_var.overread += words - gcov_var.length;
+	  gcov_var.length = 0;
+	  return 0;
+	}
+    }
+  result = &gcov_var.buffer[gcov_var.offset];
+  gcov_var.offset += words;
+  return result;
+}
+
+/* Read unsigned value from a coverage file. Sets error flag on file
+   error, overflow flag on overflow */
+
+GCOV_LINKAGE gcov_unsigned_t
+gcov_read_unsigned (void)
+{
+  gcov_unsigned_t value;
+  const gcov_unsigned_t *buffer = gcov_read_words (1);
+
+  if (!buffer)
+    return 0;
+  value = from_file (buffer[0]);
+  return value;
+}
+
+/* Read counter value from a coverage file. Sets error flag on file
+   error, overflow flag on overflow */
+
+GCOV_LINKAGE gcov_type
+gcov_read_counter (void)
+{
+  gcov_type value;
+  const gcov_unsigned_t *buffer = gcov_read_words (2);
+
+  if (!buffer)
+    return 0;
+  value = from_file (buffer[0]);
+  if (sizeof (value) > sizeof (gcov_unsigned_t))
+    value |= ((gcov_type) from_file (buffer[1])) << 32;
+  else if (buffer[1])
+    gcov_var.error = -1;
+
+  return value;
+}
+
+/* Read string from coverage file. Returns a pointer to a static
+   buffer, or NULL on empty string. You must copy the string before
+   calling another gcov function.  */
+
+#if !IN_LIBGCOV
+GCOV_LINKAGE const char *
+gcov_read_string (void)
+{
+  unsigned length = gcov_read_unsigned ();
+
+  if (!length)
+    return 0;
+
+  return (const char *) gcov_read_words (length);
+}
+#endif
+
+GCOV_LINKAGE void
+gcov_read_summary (struct gcov_summary *summary)
+{
+  unsigned ix;
+  struct gcov_ctr_summary *csum;
+
+  summary->checksum = gcov_read_unsigned ();
+  for (csum = summary->ctrs, ix = GCOV_COUNTERS_SUMMABLE; ix--; csum++)
+    {
+      csum->num = gcov_read_unsigned ();
+      csum->runs = gcov_read_unsigned ();
+      csum->sum_all = gcov_read_counter ();
+      csum->run_max = gcov_read_counter ();
+      csum->sum_max = gcov_read_counter ();
+    }
+}
+
+#if !IN_LIBGCOV
+/* Reset to a known position.  BASE should have been obtained from
+   gcov_position, LENGTH should be a record length.  */
+
+GCOV_LINKAGE void
+gcov_sync (gcov_position_t base, gcov_unsigned_t length)
+{
+  gcc_assert (gcov_var.mode > 0);
+  base += length;
+  if (base - gcov_var.start <= gcov_var.length)
+    gcov_var.offset = base - gcov_var.start;
+  else
+    {
+      gcov_var.offset = gcov_var.length = 0;
+      fseek (gcov_var.file, base << 2, SEEK_SET);
+      gcov_var.start = ftell (gcov_var.file) >> 2;
+    }
+}
+#endif
+
+#if IN_LIBGCOV
+/* Move to a given position in a gcov file.  */
+
+GCOV_LINKAGE void
+gcov_seek (gcov_position_t base)
+{
+  gcc_assert (gcov_var.mode < 0);
+  if (gcov_var.offset)
+    gcov_write_block (gcov_var.offset);
+  fseek (gcov_var.file, base << 2, SEEK_SET);
+  gcov_var.start = ftell (gcov_var.file) >> 2;
+}
+#endif
+
+#if IN_GCOV > 0
+/* Return the modification time of the current gcov file.  */
+
+GCOV_LINKAGE time_t
+gcov_time (void)
+{
+  struct stat status;
+
+  if (fstat (fileno (gcov_var.file), &status))
+    return 0;
+  else
+    return status.st_mtime;
+}
+#endif /* IN_GCOV */