arc: Add support for Newlib

Add support for Newlib as an OS/ABI.  The only thing that is specific to it
relatively to "generic" baremetal target is location of PC register in jump
buffer for longjump support.

Sniffer uses .ivt section to decide if ELF file is for ARC Newlib or not.

gdb/ChangeLog:

	* arc-newlib-tdep.c: New file.
	* configure.tgt: Add newlib support for ARC.

3 files changed, 80 insertions, 1 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index b346137..109aac9 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,10 @@
 2016-10-12  Anton Kolesov  <anton.kolesov@synopsys.com>
 
+	* arc-newlib-tdep.c: New file.
+	* configure.tgt: Add newlib support for ARC.
+
+2016-10-12  Anton Kolesov  <anton.kolesov@synopsys.com>
+
 	* arc-tdep.h (struct gdbarch_tdep) <jb_pc>: New field.
 	* arc-tdep.c (arc_get_longjmp_target): New function.
 	(arc_gdbarch_init): Set get_longjmp_target if jb_pc is non-negative.
diff --git a/gdb/arc-newlib-tdep.c b/gdb/arc-newlib-tdep.c
new file mode 100644
index 0000000..d93bf85
--- /dev/null
+++ b/gdb/arc-newlib-tdep.c
@@ -0,0 +1,69 @@
+/* Target-dependent code for Newlib ARC.
+
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   Contributed by Synopsys Inc.
+
+   This file is part of GDB.
+
+   This program 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.
+
+   This program 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 "defs.h"
+
+#include "gdbarch.h"
+#include "arc-tdep.h"
+#include "osabi.h"
+
+/* Implement the 'init_osabi' method of struct gdb_osabi_handler.  */
+
+static void
+arc_newlib_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+  if (arc_debug)
+    debug_printf ("arc-newlib: Initialization.\n");
+
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  /* Offset of original PC in longjmp jump buffer (in registers).  Value of PC
+     offset can be found in newlib/libc/machine/arc/setjmp.S.  */
+  tdep->jb_pc = 18;
+}
+
+/* Recognize ARC Newlib object files.  */
+
+static enum gdb_osabi
+arc_newlib_osabi_sniffer (bfd *abfd)
+{
+  if (arc_debug)
+    debug_printf ("arc-newlib: OS/ABI sniffer.\n");
+
+  /* crt0.S in libgloss for ARC defines .ivt section for interrupt handlers.
+     If this section is not present then this is likely not a newlib - could be
+     a Linux application or some non-newlib baremetal application.  */
+  if (bfd_get_section_by_name (abfd, ".ivt") != NULL)
+    return GDB_OSABI_NEWLIB;
+  else
+    return GDB_OSABI_UNKNOWN;
+}
+
+/* Provide a prototype to silence -Wmissing-prototypes.  */
+extern initialize_file_ftype _initialize_arc_newlib_tdep;
+
+void
+_initialize_arc_newlib_tdep (void)
+{
+  gdbarch_register_osabi_sniffer (bfd_arch_arc, bfd_target_elf_flavour,
+				  arc_newlib_osabi_sniffer);
+  gdbarch_register_osabi (bfd_arch_arc, 0, GDB_OSABI_NEWLIB,
+			  arc_newlib_init_osabi);
+}
diff --git a/gdb/configure.tgt b/gdb/configure.tgt
index ef041de..a64fe42 100644
--- a/gdb/configure.tgt
+++ b/gdb/configure.tgt
@@ -83,8 +83,13 @@ am33_2.0*-*-linux*)
 			solib-svr4.o"
 	;;
 
+arc*-*-elf32)
+	# Target: baremetal ARC elf32 (newlib) target
+	gdb_target_obs="arc-newlib-tdep.o arc-tdep.o"
+	;;
+
 arc*-*-*)
-	# Target: baremetal ARC elf32 target
+	# Target: Unidentified ARC target
 	gdb_target_obs="arc-tdep.o"
 	;;