libdw: Handle GNU DebugFission split ranges.

GNU DebugFission split dwarf handles DW_FORM_sec_offset specially for
attributes that point to ranges. The .debug_ranges section is not in
the .dwo file, but in the main/skeleton object file. The sec_offset is
not relocated (in the ELF file), but is an offset against the skeleton
DIE DW_AT_GNU_ranges_base attribute. dwarf_formudata is changed so it
still looks like a normal offset ptr into the .debug_ranges section.
dwarf_ranges is adapted to look for the .debug_ranges in the main object
file. dwarf_highpc and dwarf_lowpc now handle the highpc and lowpc
attributes being inherited for the split unit DIE from the skeleton.

A new testcase is added to iterate over all ranges in a split GNU
DebugFission file.

Signed-off-by: Mark Wielaard <[email protected]>

1 files changed, 90 insertions, 0 deletions

diff --git a/tests/all-dwarf-ranges.c b/tests/all-dwarf-ranges.c
new file mode 100644
index 00000000..4331a05b
--- /dev/null
+++ b/tests/all-dwarf-ranges.c
@@ -0,0 +1,90 @@
+/* Test program for dwarf_ranges
+   Copyright (C) 2015, 2018 Red Hat, Inc.
+   This file is part of elfutils.
+
+   This file 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 of the License, or
+   (at your option) any later version.
+
+   elfutils 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.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+#include ELFUTILS_HEADER(dw)
+#include <dwarf.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <inttypes.h>
+
+static void
+ranges_die (Dwarf_Die *die)
+{
+  Dwarf_Addr base, start, end;
+  int ranges = dwarf_ranges (die, 0, &base, &start, &end);
+  if (ranges < 0)
+    puts (dwarf_errmsg (-1));
+  else if (ranges > 0)
+    {
+      printf ("die: %s (%x)\n", dwarf_diename (die) ?: "<unknown>",
+	      dwarf_tag (die));
+      for (ptrdiff_t off = 0;
+	   (off = dwarf_ranges (die, off, &base, &start, &end)); )
+	if (off == -1)
+	  {
+	    puts (dwarf_errmsg (-1));
+	    break;
+	  }
+	else
+	  printf (" %"PRIx64"..%"PRIx64"\n", start, end);
+      printf ("\n");
+    }
+}
+
+static void
+walk_tree (Dwarf_Die *dwarf_die)
+{
+  Dwarf_Die die = *dwarf_die;
+  do
+    {
+      Dwarf_Die child;
+      ranges_die (&die);
+      if (dwarf_child (&die, &child) == 0)
+	walk_tree (&child);
+    }
+  while (dwarf_siblingof (&die, &die) == 0);
+}
+
+int
+main (int argc, char *argv[])
+{
+  assert (argc >= 2);
+  const char *name = argv[1];
+
+  int fd = open (name, O_RDONLY);
+  Dwarf *dbg = dwarf_begin (fd, DWARF_C_READ);
+
+  Dwarf_CU *cu = NULL;
+  Dwarf_Die cudie, subdie;
+  uint8_t unit_type;
+  while (dwarf_get_units (dbg, cu, &cu, NULL,
+			  &unit_type, &cudie, &subdie) == 0)
+    {
+      Dwarf_Die die = (unit_type == DW_UT_skeleton
+		       ? subdie : cudie);
+      walk_tree (&die);
+    }
+  dwarf_end (dbg);
+
+  return 0;
+}