arc: Add support for Linux coredump files

With the implemenations in this patch, ARC gdb can handle
coredump related matters.  The binutils counter part of
this patch has already been pushed [1].

v2 [2]:
- arc_linux_collect_gregset: Use "reg <= ARC_LAST_REGNUM" instead of
  "reg < ARC_LAST_REGNUM" for the condition check of the for-loop.
- arc-linux-tdep.c: Use "ARC_LAST_REGNUM < ARRAY_SIZE (...)" instead of
  "ARC_LAST_REGNUM <= ARRAY_SIZE (...)" for the "asserts".
- Use "buf + arc_linux_core_reg_offsets[ARC_ERET_REGNUM]" instead of
  "buf + REG_OFF (6)".
- Fix a few typos/indentation.

v3 [3]:
- Use gdb_assert_not_reached(text) instead of gdb_assert (!text).
- Remove unnecessary braces in the for loop.

[1] arc: Add support for ARC HS extra registers in core files
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=2745674244d6aecddcf636475034bdb9c0a6b4a0

[2] First remarks
https://sourceware.org/pipermail/gdb-patches/2020-September/171912.html

[3] Second remarks
https://sourceware.org/pipermail/gdb-patches/2020-October/172302.html

gdb/ChangeLog:

	* arc-linux-tdep.h: New file.
	* arc-linux-tdep.c (arc_linux_core_reg_offsets,
	arc_linux_supply_gregset, arc_linux_supply_v2_regset,
	arc_linux_collect_gregset, arc_linux_collect_v2_regset,
	arc_linux_gregset, arc_linux_v2_regset,
	arc_linux_iterate_over_regset_sections,
	arc_linux_core_read_description): Implement.
	(arc_linux_init_osabi): Set iterate_over_regset_sections.
	* arc-tdep.h (ARC_OFFSET_NO_REGISTER): Declare.
        (arc_gdbarch_features_create): Add.
	* arc-tdep.c (arc_gdbarch_features_create): Not static anymore.

1 files changed, 52 insertions, 0 deletions

diff --git a/gdb/arc-linux-tdep.h b/gdb/arc-linux-tdep.h
new file mode 100644
index 0000000..c26cacd
--- /dev/null
+++ b/gdb/arc-linux-tdep.h
@@ -0,0 +1,52 @@
+/* Target dependent code for GNU/Linux ARC.
+
+   Copyright 2020 Free Software Foundation, 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/>.  */
+
+#ifndef ARC_LINUX_TDEP_H
+#define ARC_LINUX_TDEP_H
+
+#include "gdbarch.h"
+#include "regset.h"
+
+#define ARC_LINUX_SIZEOF_V2_REGSET (3 * ARC_REGISTER_SIZE)
+
+/* Reads registers from the NT_PRSTATUS data array into the regcache.  */
+
+void arc_linux_supply_gregset (const struct regset *regset,
+			       struct regcache *regcache, int regnum,
+			       const void *gregs, size_t size);
+
+/* Reads regsiters from the NT_ARC_V2 data array into the regcache.  */
+
+void arc_linux_supply_v2_regset (const struct regset *regset,
+				 struct regcache *regcache, int regnum,
+				 const void *v2_regs, size_t size);
+
+/* Writes registers from the regcache into the NT_PRSTATUS data array.  */
+
+void arc_linux_collect_gregset (const struct regset *regset,
+				const struct regcache *regcache,
+				int regnum, void *gregs, size_t size);
+
+/* Writes registers from the regcache into the NT_ARC_V2 data array.  */
+
+void arc_linux_collect_v2_regset (const struct regset *regset,
+				  const struct regcache *regcache,
+				  int regnum, void *v2_regs, size_t size);
+
+#endif /* ARC_LINUX_TDEP_H */